text: Astronomers estimate that the Solar System as we know it today will not change drastically until the Sun has fused almost all the hydrogen fuel in its core into helium, beginning its evolution from the main sequence of the Hertzsprung–Russell diagram and into its red-giant phase. Even so, the Solar System will continue to evolve until then.

text: Astronomers estimate that the Solar System as we know it today will not change drastically until the Sun has fused almost all the hydrogen fuel in its core into helium, beginning

entity_name: Stellar evolution

text: its evolution

text: from the

entity_name: Main sequence

text: main sequence

text: of the

entity_name: Hertzsprung–Russell diagram

text: Hertzsprung–Russell diagram

text: and into its

entity_name: Red giant

text: red-giant

text: phase. Even so, the Solar System will continue to evolve until then.

method: Bert-ConvKNRM

text: Planets rotate at varying rates and thus may take a slightly oblate shape because of the centrifugal force. With such an oblate shape, the gravitational attraction will deviate somewhat from that of a homogeneous sphere. This phenomenon is quite noticeable for artificial Earth satellites, especially those in low orbits. At larger distances the effect of this oblateness becomes negligible. Planetary motions in the Solar System can be computed with sufficient precision if they are treated as point masses.

text: Laplace's analytical discussion of the Solar System is given in his Mécanique céleste published in five volumes. The first two volumes, published in 1799, contain methods for calculating the motions of the planets, determining their figures, and resolving tidal problems. The third and fourth volumes, published in 1802 and 1805, contain applications of these methods, and several astronomical tables. The fifth volume, published in 1825, is mainly historical, but it gives as appendices the results of Laplace's latest researches. Laplace's own investigations embodied in it are so numerous and valuable that it is regrettable to have to add that many results are appropriated from other writers with scanty or no acknowledgement, and the conclusions – which have been described as the organized result of a century of patient toil – are frequently mentioned as if they were due to Laplace.

method: ICT-DRMMTKS

text: In January 2011, Jane Espenson and Kevin Grazier made public a map of the Twelve Colonies that the show creators worked from. This map reveals that Picon, Caprica, Gemenon and Tauron orbit Helios Alpha; Leonis and Virgon orbit Helios Beta; Libran, Scorpia and Sagittaron orbit Helios Gamma, and Aerilon, Canceron and Aquaria orbit Helios Delta. It also reveals the names of gas giants, minor planets and moons in the Colonies' solar system (the Cyrannus system) and includes cultural details on each colony.

text: In January 2011,

entity_name: Jane Espenson

text: Jane Espenson

text: and

entity_name: Kevin Grazier

text: Kevin Grazier

text: made public a map of the Twelve Colonies that the show creators worked from. This map reveals that Picon, Caprica, Gemenon and Tauron orbit Helios Alpha; Leonis and Virgon orbit Helios Beta; Libran, Scorpia and Sagittaron orbit Helios Gamma, and Aerilon, Canceron and Aquaria orbit Helios Delta. It also reveals the names of gas giants, minor planets and moons in the Colonies' solar system (the Cyrannus system) and includes cultural details on each colony.

method: Bert-DRMMTKS

text: The time frame of the Solar System's formation has been determined using radiometric dating. Scientists estimate that the Solar System is 4.6 billion years old. The oldest known mineral grains on Earth are approximately 4.4 billion years old. Rocks this old are rare, as Earth's surface is constantly being reshaped by erosion, volcanism, and plate tectonics. To estimate the age of the Solar System, scientists use meteorites, which were formed during the early condensation of the solar nebula. Almost all meteorites (see the Canyon Diablo meteorite) are found to have an age of 4.6 billion years, suggesting that the Solar System must be at least this old.

text: The time frame of the Solar System's formation has been determined using

entity_name: Radiometric dating

text: radiometric dating

text: . Scientists estimate that the Solar System is 4.6 billion years old. The

entity_name: Oldest dated rocks

entity_section: Oldest terrestrial material

text: oldest known mineral grains

text: on

entity_name: Earth

text: Earth

text: are approximately 4.4 billion years old. Rocks this old are rare, as Earth's surface is constantly being reshaped by

entity_name: Erosion

text: erosion

entity_name: Volcanism

text: volcanism

text: , and

entity_name: Plate tectonics

text: plate tectonics

text: . To estimate the age of the Solar System, scientists use

entity_name: Meteorite

text: meteorite

text: s, which were formed during the early condensation of the solar nebula. Almost all meteorites (see the

entity_name: Canyon Diablo (meteorite)

text: Canyon Diablo meteorite

text: ) are found to have an age of 4.6 billion years, suggesting that the Solar System must be at least this old.

method: UNH-qee

text: Uranus is the seventh planet from the Sun. It has the third-largest planetary radius and fourth-largest planetary mass in the Solar System. Uranus is similar in composition to Neptune, and both have different bulk chemical composition from that of the larger gas giants Jupiter and Saturn. For this reason, scientists often classify Uranus and Neptune as "ice giants" to distinguish them from the gas giants. Uranus's atmosphere is similar to Jupiter's and Saturn's in its primary composition of hydrogen and helium, but it contains more "ices" such as water, ammonia, and methane, along with traces of other hydrocarbons. It is the coldest planetary atmosphere in the Solar System, with a minimum temperature of , and has a complex, layered cloud structure with water thought to make up the lowest clouds and methane the uppermost layer of clouds. The interior of Uranus is mainly composed of ices and rock.

text: Uranus is the seventh

entity_name: Planet

text: planet

text: from the

entity_name: Sun

text: Sun

text: . It has the third-largest planetary radius and fourth-largest planetary mass in the

entity_name: Solar System

text: Solar System

text: . Uranus is similar in composition to

entity_name: Neptune

text: Neptune

text: , and both have different bulk chemical composition from that of the larger

entity_name: Gas giant

text: gas giant

text: s

entity_name: Jupiter

text: Jupiter

text: and

entity_name: Saturn

text: Saturn

text: . For this reason, scientists often classify Uranus and Neptune as "

entity_name: Ice giant

text: ice giant

text: s" to distinguish them from the gas giants. Uranus's atmosphere is similar to Jupiter's and Saturn's in its primary composition of

entity_name: Hydrogen

text: hydrogen

text: and

entity_name: Helium

text: helium

text: , but it contains more "

entity_name: Volatiles

text: ices

text: " such as water,

entity_name: Ammonia

text: ammonia

text: , and

entity_name: Methane

text: methane

text: , along with traces of other

entity_name: Hydrocarbon

text: hydrocarbon

text: s. It is the coldest planetary

entity_name: Atmosphere

text: atmosphere

text: in the Solar System, with a minimum temperature of , and has a complex, layered

entity_name: Cloud

text: cloud

text: structure with water thought to make up the lowest clouds and methane the uppermost layer of clouds. The interior of Uranus is mainly composed of ices and rock.

method: UNH-ecn

text: From Earth's point of view, the ring system appears about 3.7 milliarcseconds across. For comparison, if it were the same distance from our solar system Saturn's ring system would be 0.006 milliarcseconds across.

text: Tolkien's cosmology is based on a clear dualism between the spiritual and the material world.While the Ainur, the first created but immaterial angelic beings have the "subcreative" power of imagination, the power to create independent life or physical reality is reserved for Eru Ilúvatar (God); this power of (primary) creation is expressed by the concept of a "Secret Fire" or  "Flame Imperishable". The term for the material universe is Eä, "the World that Is", as distinguished from the purely idealist pre-figuration of creation in the minds of the Ainur.  Eä contains our Earth (and solar system) in a mythical ancient past, of which Middle-earth is the main continent. Eä (Quenya for "let [these things] be!") was the word spoken by Eru Ilúvatar (metaphorically, in the purported Quenya-language account of creation) by which he brought the physical universe into actuality.

text: Tolkien's cosmology is based on a clear

entity_name: Dualism (philosophy of mind)

text: dualism

text: between the spiritual and the material world.While the Ainur, the first created but immaterial angelic beings have the "

entity_name: Mythopoeia

entity_section: Subcreation

text: subcreative

text: " power of imagination, the power to create independent life or physical reality is reserved for

entity_name: Eru Ilúvatar

text: Eru Ilúvatar

entity_name: God

text: God

text: ); this power of (primary) creation is expressed by the concept of a "Secret Fire" or  "Flame Imperishable". The term for the material universe is Eä, "the World that Is", as distinguished from the purely

entity_name: Idealism

text: idealist

text: pre-figuration of creation in the minds of the

entity_name: Ainur (Middle-earth)

text: Ainur

text: .  Eä contains our

entity_name: Arda (Tolkien)

text: Earth

text: (and solar system) in a mythical ancient past, of which

entity_name: Middle-earth

text: Middle-earth

text: is the main continent. Eä (

entity_name: Quenya

text: Quenya

text: for "let [these things] be!") was the

entity_name: Logos (Christianity)

text: word

text: spoken by Eru Ilúvatar (metaphorically, in the purported

text: Quenya

text: -language account of creation) by which he brought the physical universe into actuality.

text: In phases of the meteorites Semarkona and Chervony Kut, a correlation between the concentration of Ni, the granddaughter of Fe, and the abundance of the stable iron isotopes provided evidence for the existence of Fe at the time of formation of the Solar System. Possibly the energy released by the decay of Fe, along with that released by Al, contributed to the remelting and differentiation of asteroids after their formation 4.6 billion years ago. The abundance of Ni present in extraterrestrial material may bring further insight into the origin and early history of the Solar System.

text: In phases of the meteorites Semarkona and Chervony Kut, a correlation between the concentration of Ni, the

entity_name: Decay product

text: granddaughter

text: of Fe, and the abundance of the stable iron isotopes provided evidence for the existence of Fe at the time of

text: formation of the Solar System

text: . Possibly the energy released by the decay of Fe, along with that released by

text: Al

text: , contributed to the remelting and

entity_name: Planetary differentiation

text: differentiation

text: of

entity_name: Asteroid

text: asteroid

text: s after their formation 4.6 billion years ago. The abundance of Ni present in

text: extraterrestrial

text: material may bring further insight into the origin and early history of the

text: Solar System

text: The first cycle opens towards the end of the 22nd century on the first planet successfully colonized by humanity, Aldebaran-4 (commonly known simply as Aldebaran), the fourth planet of the Aldebaran solar system and the only discovered to be hospitable. It is revealed that since its colonization 100 years previous, communication with Earth has been impossible, the reason for which is not explained.As a result, the colonists have had to put in place an autocratic society, making do with what is available to them on the planet. The original population of 3,000 colonists rapidly grows to around 20,000 habitants when the cycle begins.

text: The first cycle opens towards the end of the 22nd century on the first planet successfully colonized by humanity, Aldebaran-4 (commonly known simply as Aldebaran), the fourth planet of the

entity_name: Aldebaran

text: Aldebaran

text: solar system and the only discovered to be hospitable. It is revealed that since its colonization 100 years previous, communication with Earth has been impossible, the reason for which is not explained.As a result, the colonists have had to put in place an

entity_name: Autocracy

text: autocratic

text: society, making do with what is available to them on the planet. The original population of 3,000 colonists rapidly grows to around 20,000 habitants when the cycle begins.

text: Jupiter's mass is 2.5 times that of all the other planets in the Solar System combined—this is so massive that its barycenter with the Sun lies above the Sun's surface at 1.068 solar radii from the Sun's center. Jupiter is much larger than Earth and considerably less dense: its volume is that of about 1,321 Earths, but it is only 318 times as massive. Jupiter's radius is about 1/10 the radius of the Sun, and its mass is 0.001 times the mass of the Sun, so the densities of the two bodies are similar. A "Jupiter mass" ( or ) is often used as a unit to describe masses of other objects, particularly extrasolar planets and brown dwarfs. So, for example, the extrasolar planet HD 209458 b has a mass of , while Kappa Andromedae b has a mass of .

text: Jupiter's mass is 2.5 times that of all the other planets in the Solar System combined—this is so massive that its

entity_name: Barycenter

text: barycenter

text: with the

text: Sun

text: lies above the

entity_name: Photosphere

text: Sun's surface

text: at 1.068

entity_name: Solar radius

text: solar radii

text: from the Sun's center. Jupiter is much larger than Earth and considerably less dense: its volume is that of about 1,321 Earths, but it is only 318 times as massive. Jupiter's radius is about 1/10 the

text: radius of the Sun

text: , and its mass is 0.001 times the

entity_name: Solar mass

text: mass of the Sun

text: , so the densities of the two bodies are similar. A "

entity_name: Jupiter mass

text: Jupiter mass

text: " ( or ) is often used as a unit to describe masses of other objects, particularly

entity_name: Exoplanet

text: extrasolar planet

text: s and

entity_name: Brown dwarf

text: brown dwarfs

text: . So, for example, the extrasolar planet

text: HD 209458 b

text: has a mass of , while

entity_name: Kappa Andromedae b

text: Kappa Andromedae b

text: has a mass of .

text: The original research on Kepler-444 was published in The Astrophysical Journal on 27 January 2015 under the title "An ancient extrasolar system with five sub-Earth-size planets" by a team of 40 authors, the abstract reads as follows:

text: The original research on Kepler-444 was published in

entity_name: The Astrophysical Journal

text: The Astrophysical Journal

text: on 27 January 2015 under the title "An ancient extrasolar system with five sub-Earth-size planets" by a team of 40 authors, the abstract reads as follows:

text: The early Solar System may have begun with five giant planets. In numerical simulations of the jumping-Jupiter scenario the ice giant is often ejected following its gravitational encounters with Jupiter and Saturn, leaving planetary systems that begin with four giant planets with only three. Although beginning with a higher-mass planetesimal disk was found to stabilize four-planet systems, the massive disk either resulted in excess migration of Jupiter and Saturn after the encounters between an ice giant and Jupiter or prevented these encounters by damping eccentricities. This problem led David Nesvorný to investigate planetary systems beginning with five giant planets. After conducting thousands of simulations he reported that simulations beginning with five giant planets were 10 times as likely to reproduce the current orbits of the outer planets. A follow-up study by David Nesvorny and Alessandro Morbidelli sought initial resonant configurations that would would reproduce the semi-major axis of the four outer planets, Jupiter's eccentricity, and a jump from <2.1 to >2.3 in Jupiter's and Saturn's period ratio. While less than 1% of the best four-planet models met these criteria roughly 5% of the best five-planet models were judged successful, with Jupiter's eccentricity being the most difficult to reproduce. A separate study by Konstantin Batygin and Michael Brown found similar probabilities (4% vs 3%) of reproducing the current outer Solar System beginning with four or five giant planets using the best initial conditions. Their simulations differed in that the planetesimal disk was placed close to the outer planet resulting in a period of migration before planetary encounters began. Criteria included reproducing the the oscillations of Jupiter's and Saturn's eccentricities, a period when Neptune's eccentricity exceeded 0.2 during which hot classical Kuiper belt objects were captured, and the retention of a primordial cold classical Kuiper belt, but not the jump in Jupiter's and Saturn's period ratio. Their results also indicate that if Neptune's eccentricity exceeded 0.2, preserving a cold classical belt may require the ice giant to be ejected in as little as 10,000 years.

text: The early Solar System may have begun with five giant planets. In numerical simulations of the jumping-Jupiter scenario the ice giant is often

entity_name: Rogue planet

text: ejected

text: following its gravitational encounters with Jupiter and Saturn, leaving

entity_name: Planetary system

text: planetary system

text: s that begin with four giant planets with only three. Although beginning with a higher-mass planetesimal disk was found to stabilize four-planet systems, the massive disk either resulted in excess migration of Jupiter and Saturn after the encounters between an ice giant and Jupiter or prevented these encounters by damping eccentricities. This problem led David Nesvorný to investigate planetary systems beginning with five giant planets. After conducting thousands of simulations he reported that simulations beginning with five giant planets were 10 times as likely to reproduce the current orbits of the outer planets. A follow-up study by David Nesvorny and Alessandro Morbidelli sought initial resonant configurations that would would reproduce the semi-major axis of the four outer planets, Jupiter's eccentricity, and a jump from <2.1 to >2.3 in Jupiter's and Saturn's period ratio. While less than 1% of the best four-planet models met these criteria roughly 5% of the best five-planet models were judged successful, with Jupiter's eccentricity being the most difficult to reproduce. A separate study by

entity_name: Konstantin Batygin

text: Konstantin Batygin

text: and Michael Brown found similar probabilities (4% vs 3%) of reproducing the current outer Solar System beginning with four or five giant planets using the best initial conditions. Their simulations differed in that the planetesimal disk was placed close to the outer planet resulting in a period of migration before planetary encounters began. Criteria included reproducing the the oscillations of Jupiter's and Saturn's eccentricities, a period when Neptune's eccentricity exceeded 0.2 during which hot classical Kuiper belt objects were captured, and the retention of a primordial

entity_name: Classical Kuiper belt object

text: cold classical Kuiper belt

text: , but not the jump in Jupiter's and Saturn's period ratio. Their results also indicate that if Neptune's eccentricity exceeded 0.2, preserving a cold classical belt may require the ice giant to be ejected in as little as 10,000 years.

text: The star contains about half of a solar mass of matter, compressed into a diameter of about , making its surface gravity 67 billion times that of Earth. Its outer crust, compressed to about 7,000 kg per cubic centimeter, is mainly iron nuclei with a high concentration of neutrons, overlaid with about  of white dwarf star material. The atmosphere, mostly iron vapor, is about  thick. The star shrinks slightly as it cools, causes the crust to crack and produce mountains  high. Large volcanos, formed by liquid material oozing from deep cracks, can be many centimeters high and hundred meters in diameters, and will eventually collapse, causing starquakes.

text: The star contains about half of a

text: solar mass

text: of matter, compressed into a

entity_name: Diameter

text: diameter

text: of about , making its

entity_name: Surface gravity

text: surface gravity

text: billion

text: times that of Earth. Its outer crust, compressed to about 7,000 kg per

entity_name: Cubic centimetre

text: cubic centimeter

text: , is mainly iron

entity_name: Atomic nucleus

text: nuclei

text: with a high concentration of

entity_name: Neutron

text: neutron

text: s, overlaid with about  of

entity_name: White dwarf

text: white dwarf star

text: material. The

text: atmosphere

text: , mostly iron vapor, is about  thick. The star shrinks slightly as it cools, causes the crust to crack and produce mountains  high. Large

entity_name: Volcano

text: volcano

text: s, formed by liquid material oozing from deep cracks, can be many centimeters high and hundred meters in diameters, and will eventually collapse, causing

entity_name: Asteroseismology

text: starquake

text: s.

text: The drag from the solar atmosphere may cause the orbit of the Moon to decay. Once the orbit of the Moon closes to a distance of , it will cross the Earth's Roche limit. This means that tidal interaction with the Earth would break apart the Moon, turning it into a ring system. Most of the orbiting ring will then begin to decay, and the debris will impact the Earth. Hence, even if the Earth is not swallowed up by the Sun, the planet may be left moonless. The ablation and vaporization caused by its fall on a decaying trajectory towards the Sun may remove Earth's crust and mantle, then finally destroy it after at most 200 years. Following this event, Earth's sole legacy will be a very slight increase (0.01%) of the solar metallicity.

text: The drag from the solar atmosphere may cause the orbit of the Moon to decay. Once the orbit of the Moon closes to a distance of , it will cross the Earth's

entity_name: Roche limit

text: Roche limit

text: . This means that tidal interaction with the Earth would break apart the Moon, turning it into a ring system. Most of the orbiting ring will then begin to decay, and the debris will impact the Earth. Hence, even if the Earth is not swallowed up by the Sun, the planet may be left moonless. The

entity_name: Ablation

text: ablation

text: and

entity_name: Vaporization

text: vaporization

text: caused by its fall on a decaying trajectory towards the Sun may remove Earth's

entity_name: Crust (geology)

text: crust

text: and mantle, then finally destroy it after at most 200 years. Following this event, Earth's sole legacy will be a very slight increase (0.01%) of the solar

entity_name: Metallicity

text: metallicity

text: Some of the moons of Jupiter, Saturn, and other planets are believed to have formed from smaller, circumplanetary analogs of the protoplanetary disks.  The formation of planets and moons in geometrically thin, gas- and dust-rich disks is the reason the planets are arranged in an ecliptic plane. Tens of millions of years after the formation of the Solar System, the inner few AU of the Solar System likely contained dozens of moon- to Mars-sized bodies that were accreting and consolidating into the terrestrial planets that we now see. The Earth's moon likely formed after a Mars-sized protoplanet obliquely impacted the proto-Earth ~30 million years after the formation of the Solar System.

text: Some of the moons of Jupiter, Saturn, and other planets are believed to have formed from smaller, circumplanetary analogs of the protoplanetary disks.  The formation of planets and moons in geometrically thin, gas- and dust-rich disks is the reason the

text: planets

text: are arranged in an

entity_name: Ecliptic

text: ecliptic plane

text: . Tens of millions of years after the formation of the Solar System, the inner few AU of the Solar System likely contained dozens of moon- to Mars-sized bodies that were accreting and consolidating into the terrestrial planets that we now see. The Earth's moon likely formed after a Mars-sized protoplanet obliquely

text: impacted

text: the proto-Earth ~30 million years after the formation of the Solar System.

text: In the Hipparchian and Ptolemaic systems of astronomy, the epicycle (from , literally on the circle, meaning circle moving on another circle) was a geometric model used to explain the variations in speed and direction of the apparent motion of the Moon, Sun, and planets. In particular it explained the apparent retrograde motion of the five planets known at the time. Secondarily, it also explained changes in the apparent distances of the planets from Earth.

text: In the Hipparchian and

text: Ptolemaic system

text: s of

text: astronomy

text: , the epicycle (from , literally on the circle, meaning circle moving on another circle) was a geometric model used to explain the variations in speed and direction of the apparent motion of the

text: Moon

text: Sun

text: , and

text: planets

text: . In particular it explained the

text: apparent retrograde motion

text: of the five planets known at the time. Secondarily, it also explained changes in the apparent distances of the planets from Earth.

text: Hope comes in the form of the Nebula 71 Star, a Saturn-like artificial satellite that observes the Earth incognito. Fearing that Gori may eventually make the Earth uninhabitable, they dispatch Spectreman, their super-cyborg agent, to battle the menace of the mad apeman. Spectreman disguises himself as a Japanese man named Jôji Gamô to walk among the humans and scout out Gori's weekly menace for the Nebula 71 Star. He works with a government-run group called the Pollution G-Men, run by Chief Kurata. This group investigates phenomena involving pollution, but they don't (until late in the show's run) have the facilities to handle giant monsters, so unbeknownst to them, their comical-yet-mysterious teammate Jòji disappears on them, only to help them as Spectreman!

text: Hope comes in the form of the Nebula 71 Star, a

text: Saturn

text: -like

text: artificial satellite

text: that observes the Earth incognito. Fearing that Gori may eventually make the Earth uninhabitable, they dispatch Spectreman, their super-cyborg agent, to battle the menace of the mad apeman. Spectreman disguises himself as a Japanese man named Jôji Gamô to walk among the humans and scout out Gori's weekly menace for the Nebula 71 Star. He works with a government-run group called the Pollution G-Men, run by Chief Kurata. This group investigates phenomena involving pollution, but they don't (until late in the show's run) have the facilities to handle giant monsters, so unbeknownst to them, their comical-yet-mysterious teammate Jòji disappears on them, only to help them as Spectreman!

text: This list contains a selection of objects estimated to be between 100 and 200 km in radius (200 and 400 km in diameter). The largest of these may lie above the boundary for hydrostatic equilibrium, but most are irregular. Most of the trans-Neptunian objects listed with a radius smaller than 200 km have "assumed sizes based on a generic albedo of 0.09" since they are too far away to directly measure their sizes with existing instruments. Mass switches from 10 kg to 10 kg (Zg). Main-belt asteroids have orbital elements constrained by (2.0 AU < a < 3.2 AU; q > 1.666 AU) according to JPL Solar System Dynamics (JPLSSD). This list is not complete, missing many poorly known TNOs.

text: This list contains a selection of objects estimated to be between 100 and 200 km in radius (200 and 400 km in diameter). The largest of these may lie above the boundary for hydrostatic equilibrium, but most are irregular. Most of the

text: trans-Neptunian object

text: s listed with a radius smaller than 200 km have "assumed sizes based on a generic

text: albedo

text: of 0.09" since they are too far away to directly measure their sizes with existing instruments. Mass switches from 10 kg to 10 kg (Zg).

text: Main-belt asteroid

text: s have orbital elements constrained by (2.0 AU < a < 3.2 AU; q > 1.666 AU) according to JPL Solar System Dynamics (JPLSSD). This list is not complete, missing many poorly known TNOs.

text: The heliosphere and planetary magnetic fields (for those planets that have them) partially shield the Solar System from high-energy interstellar particles called cosmic rays. The density of cosmic rays in the interstellar medium and the strength of the Sun's magnetic field change on very long timescales, so the level of cosmic-ray penetration in the Solar System varies, though by how much is unknown.

text: The heliosphere and planetary magnetic fields (for those planets that have them) partially shield the Solar System from high-energy interstellar particles called

text: cosmic ray

text: s. The density of cosmic rays in the

text: interstellar medium

text: and the strength of the Sun's magnetic field change on very long timescales, so the level of cosmic-ray penetration in the Solar System varies, though by how much is unknown.

text: Researchers have found that the mineral, which has the same atomic arrangement as a man-made component of some types of concrete, forms under low pressure at a temperature of at least . These conditions of high temperature and low pressure are consistent with a hypothesis that the krotite grains found in the meteorite formed as high-temperature condensates from the solar nebula from which the solar system formed, approximately 4.6 billion years ago. Thus, they are likely to be among the earliest minerals formed in the solar system.

text: Researchers have found that the mineral, which has the same atomic arrangement as a man-made component of some types of

text: concrete

text: , forms under low

text: pressure

text: at a

text: temperature

text: of at least . These conditions of high temperature and low pressure are consistent with a hypothesis that the krotite grains found in the meteorite formed as high-temperature

text: condensate

text: s from the

text: solar nebula

text: from which the

text: solar system

text: formed, approximately 4.6 billion years ago. Thus, they are likely to be among the earliest minerals formed in the solar system.

text: Early in the year 1979, Japan's famed rocketship, the JX-1 Hawk is launched from the Mt Fuji Interstellar Exploration Agency site into space on a 9-month journey to investigate the planet Saturn up close. It was discovered that a small, runaway "planet," which some scientists believed to be the solid mega-dense core of a collapsed star that had somehow run amok, and was subsequently named "Gorath" by the international scientific community, had entered Earth's solar system. Upon encountering Gorath and attempting to investigate its rapid movement in the solar system, they discover that Gorath is smaller than Earth but with 6000 times Earth's gravity. The JX-1 is caught in its gravity well and its entire crew of the spacecraft lost their lives as the enormous gravity well of the approaching celestial body destroyed the ship.

text: At 19% of the solar radius, near the edge of the core, temperatures are about 10 million kelvin and fusion power density is 6.9 W/m, which is about 2.5% of the maximum value at the solar center. The density here is about 40 g/cm, or about 27% of that at the center. Some 91% of the solar energy is produced within this radius. Within 24% of the radius (the outer "core" by some definitions), 99% of the Sun's power is produced. Beyond 30% of the solar radius, where temperature is 7 million K and density has fallen to 10 g/cm the rate of fusion is almost nil. There are two distinct reactions in which 4 H nuclei may eventually result in one He nucleus: "proton-proton chain reaction" and the "CNO cycle" (see below).

text: The relationship between man and sun in sonnet 7 is metaphysical.  The sun is the center of our being, but is also an object of desire.  We want the sun's immortality.  But man and the sun rely on one another to coexist.  Man needs sun to survive on earth, and the sun would be of no significance without man.  Man will cycle ad nauseam in this world yet the sun stays the same.  The sun is reliable and unchanging.  To the sun, one man is the same to another is the same to another.

text: The relationship between man and sun in sonnet 7 is metaphysical.  The sun is the center of our being, but is also an object of desire.  We want the sun's immortality.  But man and the sun rely on one another to coexist.  Man needs sun to survive on earth, and the sun would be of no significance without man.  Man will cycle

text: ad nauseam

text: in this world yet the sun stays the same.  The sun is reliable and unchanging.  To the sun, one man is the same to another is the same to another.

text: In 1687, Isaac Newton published Philosophiæ Naturalis Principia Mathematica, which provided an explanation for Kepler's laws in terms of universal gravitation and what came to be known as Newton's laws of motion. This placed Heliocentrism on a firm theoretical foundation, although Newton's Heliocentrism was of a somewhat modern kind. Already in the mid-1680s he recognized the "deviation of the Sun" from the centre of gravity of the solar system. For Newton it was not precisely the centre of the Sun or any other body that could be considered at rest, but "the common centre of gravity of the Earth, the Sun and all the Planets is to be esteem'd the Centre of the World", and this centre of gravity "either is at rest or moves uniformly forward in a right line". Newton adopted the "at rest" alternative in view of common consent that the centre, wherever it was, was at rest.

text: In 1687,

text: Isaac Newton

text: published

text: Philosophiæ Naturalis Principia Mathematica

text: , which provided an explanation for Kepler's laws in terms of

text: universal gravitation

text: and what came to be known as

text: Newton's laws of motion

text: . This placed Heliocentrism on a firm theoretical foundation, although Newton's Heliocentrism was of a somewhat modern kind. Already in the mid-1680s he recognized the "deviation of the Sun" from the centre of gravity of the solar system. For Newton it was not precisely the centre of the Sun or any other body that could be considered at rest, but "the common centre of gravity of the Earth, the Sun and all the Planets is to be esteem'd the Centre of the World", and this centre of gravity "either is at rest or moves uniformly forward in a right line". Newton adopted the "at rest" alternative in view of common consent that the centre, wherever it was, was at rest.

text: The planet orbits 3.07 times further out and is 7.13 times less massive than the first companion, having a semi-amplitude of only 42 m/s. Its mass is 2.44 times that of Jupiter and its diameter is roughly the same size as Jupiter's. The orbital resonance of the planet orbiting the brown dwarf is 5:1. The eccentricity of the planet is higher than that of all the planets and dwarf planets in the Solar System except Eris, which has an eccentricity of 0.44.

text: The planet orbits 3.07 times further out and is 7.13 times less massive than the first companion, having a semi-

text: amplitude

text: of only 42 m/s. Its mass is 2.44 times that of

text: Jupiter

text: and its

text: diameter

text: is roughly the same size as Jupiter's. The

text: orbital resonance

text: of the planet orbiting the brown dwarf is 5:1. The

text: eccentricity

text: of the planet is higher than that of all the

text: planet

text: s and

text: dwarf planet

text: s in the

text: Solar System

text: except

text: Eris

text: , which has an eccentricity of 0.44.

text: One of the main problems when generating hypotheses on the formation and evolution of objects in the Solar System is the lack of samples that can be analysed in the laboratory, where a large suite of tools are available and the full body of knowledge derived from terrestrial geology can be brought to bear. Fortunately, direct samples from the Moon, asteroids and Mars are present on Earth, removed from their parent bodies and delivered as meteorites. Some of these have suffered contamination from the oxidising effect of Earth's atmosphere and the infiltration of the biosphere, but those meteorites collected in the last few decades from Antarctica are almost entirely pristine.

text: One of the main problems when generating hypotheses on the formation and evolution of objects in the Solar System is the lack of samples that can be analysed in the laboratory, where a large suite of tools are available and the full body of knowledge derived from terrestrial geology can be brought to bear. Fortunately, direct samples from the Moon,

text: asteroid

text: s and

text: Mars

text: are present on Earth, removed from their parent bodies and delivered as

text: meteorite

text: s. Some of these have suffered contamination from the

text: oxidising

text: effect of Earth's atmosphere and the infiltration of the

text: biosphere

text: , but those meteorites collected in the last few decades from

text: Antarctica

text: are almost entirely pristine.

text: The exterior surface of a transpired solar collector consists of thousands of tiny micro-perforations that allow the boundary layer of heat to be captured and uniformly drawn into an air cavity behind the exterior panels. This solar heated ventilation air is drawn into the building’s ventilation system from air outlets positioned along the top of the collector and the air is then distributed in the building via conventional means or using a solar ducting system.

text: The Solar Energy Museum is structurally separate from the Solar Ark itself. It is officially called the solar lab. It is a museum and exhibition centre that mostly provides information about solar energy. There are several exhibitions, workshops and science classes held at the solar lab, which are primarily aimed at the younger generations, to help them become more aware of the photovoltaic science and how it impacts the world. The solar lab is divided into ten zones that provide a wide range of activities for visitors. Some of these activities include a solar system simulator, an adventure wall, an artistic approach to the sun, a solar library and a control deck, where visitors can view real time data related to the power being generated by the Solar Ark.

text: The

text: Solar Energy

text: Museum is structurally separate from the Solar Ark itself. It is officially called the solar lab. It is a museum and exhibition centre that mostly provides information about solar energy. There are several exhibitions, workshops and science classes held at the solar lab, which are primarily aimed at the younger generations, to help them become more aware of the photovoltaic science and how it impacts the world. The solar lab is divided into ten zones that provide a wide range of activities for visitors. Some of these activities include a

text: solar system

text: simulator, an adventure wall, an artistic approach to the sun, a solar library and a control deck, where visitors can view real time data related to the power being generated by the Solar Ark.

text: Two observations supported the idea that the Earth was the center of the Universe. First, the Sun appears to revolve around the Earth once per day. While the Moon and the planets have their own motions, they also appear to revolve around the Earth about once per day. The stars appeared to be on a celestial sphere, rotating once each day along an axis through the north and south geographic poles of the Earth. Second, the Earth does not seem to move from the perspective of an Earth-bound observer; it appears to be solid, stable, and unmoving.

text: Two observations supported the idea that the Earth was the center of the

text: Universe

text: . First, the Sun appears to revolve around the Earth once per day. While the Moon and the planets have their own motions, they also appear to revolve around the Earth about once per day. The stars appeared to be on a

text: celestial sphere

text: , rotating once each day along an axis through the north and south geographic poles of the Earth. Second, the Earth does not seem to move from the perspective of an Earth-bound observer; it appears to be solid, stable, and unmoving.

text: Metal Storm is an action-platform video game developed by Tamtex and published by Irem for the Nintendo Entertainment System. It was released in North America in February 1991 and in Japan on April 24, 1992. The story takes place in 2501, when a laser weapon at a defense outpost on Pluto has malfunctioned and begun destroying the Solar System. The player takes on the role of the M-308 Gunner, which storms into the defense base in order to activate the self-destruct system before the laser gun destroys Earth. The M-308 is equipped with a gravity control device which allows the player to flip between the floor and ceiling, a main feature of the game. Metal Storm received positive reviews from gaming publications.

text: Metal Storm is an

text: action

text: platform

text: video game developed by Tamtex and published by

text: Irem

text: for the

text: Nintendo Entertainment System

text: . It was released in North America in February 1991 and in Japan on April 24, 1992. The story takes place in 2501, when a laser weapon at a defense outpost on

text: Pluto

text: has malfunctioned and begun destroying the

text: Solar System

text: . The player takes on the role of the M-308 Gunner, which storms into the defense base in order to activate the self-destruct system before the laser gun destroys

text: Earth

text: . The M-308 is equipped with a gravity control device which allows the player to flip between the floor and ceiling, a main feature of the game. Metal Storm received positive reviews from gaming publications.

text: Jupiter is the fifth planet from the Sun and the largest in the Solar System. It is a giant planet with a mass one-thousandth that of the Sun, but two and a half times that of all the other planets in the Solar System combined. Jupiter is a gas giant, along with Saturn, with the other two giant planets, Uranus and Neptune, being ice giants. Jupiter was known to astronomers of ancient times. The Romans named it after their god Jupiter. When viewed from Earth, Jupiter can reach an apparent magnitude of −2.94, bright enough for its reflected light to cast shadows, and making it on average the third-brightest object in the night sky after the Moon and Venus.

text: Jupiter is the fifth

text: planet

text: from the

text: Sun

text: and the

text: largest

text: in the

text: Solar System

text: . It is a

text: giant planet

text: with a

text: mass

text: one-thousandth that of the Sun, but two and a half times that of all the other planets in the Solar System combined. Jupiter is a

text: gas giant

text: , along with

text: Saturn

text: , with the other two

text: giant planet

text: s,

text: Uranus

text: and

text: Neptune

text: , being

text: ice giant

text: s. Jupiter was known to

text: astronomer

text: s of ancient times. The

text: Romans

text: named it after

text: their god

text: Jupiter

text: . When viewed from

text: Earth

text: , Jupiter can reach an

text: apparent magnitude

text: of −2.94, bright enough for its reflected light to cast shadows, and making it on average the third-brightest object in the

text: night sky

text: after the

text: Moon

text: and

text: Venus

text: The main reason for the slowing down of the Earth's rotation is tidal friction, which alone would lengthen the day by 2.3 ms/century. Other contributing factors are the movement of the Earth's crust relative to its core, changes in mantle convection, and any other events or processes that cause a significant redistribution of mass. These processes change the Earth's moment of inertia, affecting the rate of rotation due to conservation of angular momentum, sometimes increasing earth's rotational speed (decreasing the solar day and opposing tidal friction). For example, glacial rebound shortens the solar day by 0.6 ms/century and the 2004 Indian Ocean earthquake is thought to have shortened it by 2.68 microseconds.  It is evident from the figure that the Earth has actually sped up since the initiation of the current system in 1971, and the rate of leap second insertions has therefore been decreasing.

text: The main reason for the slowing down of the Earth's rotation is

text: tidal friction

text: , which alone would lengthen the day by 2.3 ms/century. Other contributing factors are the movement of the Earth's

text: crust

text: relative to its

text: core

text: , changes in

text: mantle convection

text: , and any other events or processes that cause a significant redistribution of mass. These processes change the Earth's

text: moment of inertia

text: , affecting the rate of rotation due to conservation of

text: angular momentum

text: , sometimes increasing earth's rotational speed (decreasing the solar day and opposing tidal friction). For example,

text: glacial rebound

text: shortens the solar day by 0.6 ms/century and the

entity_name: 2004 Indian Ocean earthquake and tsunami

text: 2004 Indian Ocean earthquake

text: is thought to have shortened it by 2.68 microseconds.  It is evident from the figure that the Earth has actually sped up since the initiation of the current system in 1971, and the rate of leap second insertions has therefore been decreasing.

text: This nebula includes the open cluster Pismis 24, which is home to several massive stars. One of the brightest stars in the cluster, Pismis 24-1, was thought possibly to be the most massive on record, approaching 300 solar masses, until it was discovered to be a multiple system of at least three stars; component stars would still remain near 100 solar masses each, making them among the more massive stars on record.

text: This nebula includes the open cluster Pismis 24, which is home to several

text: massive stars

text: . One of the brightest stars in the cluster,

text: Pismis 24-1

text: , was thought possibly to be the most massive on record, approaching 300

text: solar mass

text: es, until it was discovered to be a

text: multiple system

text: of at least three stars; component stars would still remain near 100 solar masses each, making them among the more massive stars on record.

text: Present day elemental abundances are superimposed on an (evolving) galactic-average set of elemental abundances that was inherited by the Solar System, along with some atoms from local nucleosynthesis sources, at the time of the Sun's formation. Knowledge of these average planetary system elemental abundances is serving as a powerful tool for tracking chemical and physical processes involved in the formation of planets, and the evolution of their surfaces.  Awaiting more on this here cf. cosmic abundance.

text: Present day elemental abundances are superimposed on an (evolving) galactic-average set of elemental abundances that was inherited by the Solar System, along with some atoms from local

text: nucleosynthesis

text: sources, at the time of the Sun's formation. Knowledge of these average planetary system

text: elemental abundance

text: s is serving as a powerful tool for tracking chemical and physical processes involved in the

text: formation of planets

text: , and the evolution of their surfaces.  Awaiting more on this here cf.

text: cosmic abundance

text: Another problem of limited sample sizes in astronomy, here practical rather than essential, is in the Titius–Bode law on spacing of satellites in an orbital system. Originally observed for the Solar System, the difficulty in observing other solar systems has limited data to test this.

text: Another problem of limited sample sizes in astronomy, here practical rather than essential, is in the

text: Titius–Bode law

text: on spacing of satellites in an orbital system. Originally observed for the Solar System, the difficulty in observing other solar systems has limited data to test this.

text: The age determined from the Canyon Diablo meteorite has been confirmed by hundreds of other age determinations, from both terrestrial samples and other meteorites. The meteorite samples, however, show a spread from 4.53 to 4.58 billion years ago. This is interpreted as the duration of formation of the solar nebula and its collapse into the solar disk to form the Sun and the planets. This 50 million year time span allows for accretion of the planets from the original solar dust and meteorites.

text: Two decades before Arthur Conan Doyle's writing, the Canadian-American dynamic astronomer Simon Newcomb had published a series of books analyzing motions of planets in the solar system. The notoriously spiteful Newcomb could have been an inspiration for Professor Moriarty.

text: Two decades before

text: Arthur Conan Doyle

text: 's writing, the Canadian-American dynamic astronomer

text: Simon Newcomb

text: had published a series of books analyzing motions of planets in the solar system. The notoriously spiteful Newcomb could have been an inspiration for Professor Moriarty.

text: Titan is the sixth ellipsoidal moon from Saturn. Frequently described as a planet-like moon, Titan's diameter is 50% larger than Earth's natural satellite, the Moon, and it is 80% more massive. It is the second-largest moon in the Solar System, after Jupiter's moon Ganymede, and is larger than the smallest planet, Mercury, although only 40% as massive. Discovered in 1655 by the Dutch astronomer Christiaan Huygens,  Titan was the first known moon of Saturn, and the sixth known planetary satellite. Titan orbits Saturn at 20 Saturn radii. From Titan's surface Saturn subtends an arc of 5.7 degrees and would appear 11.4 times the size our moon does to us.

text: Titan is the sixth ellipsoidal moon from

text: Saturn

text: . Frequently described as a planet-like moon, Titan's diameter is 50% larger than Earth's natural satellite, the

text: Moon

text: , and it is 80% more massive. It is the

text: second-largest moon

text: in the

text: Solar System

text: , after Jupiter's moon

text: Ganymede

text: , and is larger than the smallest planet,

text: Mercury

text: , although only 40% as massive. Discovered in 1655 by the Dutch astronomer

text: Christiaan Huygens

text: ,  Titan was the first known moon of Saturn, and the sixth known planetary satellite. Titan orbits Saturn at 20 Saturn radii. From Titan's surface Saturn subtends an arc of 5.7 degrees and would appear 11.4 times the size our moon does to us.

text: Outside the bright inner portion of the nebula, there are a series of concentric rings, thought to have been ejected before the formation of the planetary nebula, while the star was on the asymptotic giant branch of the Hertzsprung-Russell diagram. These rings are very evenly spaced, suggesting that the mechanism responsible for their formation ejected them at very regular intervals and at very similar speeds. The total mass of the rings is about 0.1 solar masses. The pulsations that formed the rings probably started 15,000 years ago and ceased about  years ago, when the formation of the bright central part began (see above).

text: Outside the bright inner portion of the nebula, there are a series of concentric rings, thought to have been ejected before the formation of the planetary nebula, while the star was on the

text: asymptotic giant branch

text: of the

text: Hertzsprung-Russell diagram

text: . These rings are very evenly spaced, suggesting that the mechanism responsible for their formation ejected them at very regular intervals and at very similar speeds. The total mass of the rings is about 0.1 solar masses. The pulsations that formed the rings probably started 15,000 years ago and ceased about  years ago, when the formation of the bright central part began (see above).

text: Apart from their distance to the Sun, different bodies show chemical variations indicating their formation and history. Neptune is denser than Uranus, taken as one piece of evidence that the two may have switched places in the early Solar System. Comets show both high volatile content, and grains containing refractory materials. This also indicates some mixing of materials through the Solar System when those comets formed. Mercury's inventory of materials by volatility is being used to evaluate different models for its formation and/or subsequent modification.

text: The age difference between CAIs and chondrules measured in these studies verifies the chronology of the early solar system derived from extinct short-lived nuclide methods such as Al-Mg, thus improving our understanding of the development of the solar system and the formation of the earth.

text: Achieving these objectives would reduce the cost of planning and deploying solar energy systems, improve efficiency of solar energy systems through more accurate and complete solar resource information, and increase the value of the solar energy produced by solar technologies.

text: At the end of 2011, there were 230,000 solar power projects in the United Kingdom, with a total installed generating capacity of 750 megawatts (MW). By February 2012 the installed capacity had reached 1,000 MW. Solar power use has increased very rapidly in recent years, albeit from a small base, as a result of reductions in the cost of photovoltaic (PV) panels, and the introduction of a Feed-in tariff (FIT) subsidy in April 2010. In 2012, the government said that 4 million homes across the UK will be powered by the sun within eight years, representing 22,000 MW of installed solar power capacity by 2020. As of April 2015, PV capacity had risen to 6,562 MW across 698,860 installations.

text: At the end of 2011, there were 230,000 solar power projects in the United Kingdom, with a total installed generating capacity of 750

text: megawatts

text: (MW). By February 2012 the installed capacity had reached 1,000 MW.

text: Solar power

text: use has increased very rapidly in recent years, albeit from a small base, as a result of reductions in the cost of

text: photovoltaic

text: (PV) panels, and the introduction of a

text: Feed-in tariff

text: (FIT) subsidy in April 2010. In 2012, the government said that 4 million homes across the UK will be powered by the sun within eight years, representing 22,000 MW of installed solar power capacity by 2020. As of April 2015, PV capacity had risen to 6,562 MW across 698,860 installations.

text: The crew find a way to heal the nebula; the Doctor points out that it has a regenerative power, so they need only be a helping hand.  Captain Janeway takes Voyager back inside to repair the damage done in the first encounter. Torres attempts to modify the engines to produce a suitable beam of energy, though the ship is more depleted than before. As they enter, the natural defenses of the nebula attack the ship more intensely, lodging it deeper and further from the wound. Chakotay finds a flow of energy in the nebula and believes it is the circulatory system. The ship reaches the injury using the "blood flow", initiates the repair, and leaves through the rupture before it finishes healing.

text: The crew find a way to heal the nebula; the Doctor points out that it has a regenerative power, so they need only be a helping hand.

text: Captain Janeway

text: takes Voyager back inside to repair the damage done in the first encounter. Torres attempts to modify the engines to produce a suitable beam of energy, though the ship is more depleted than before. As they enter, the natural defenses of the nebula attack the ship more intensely, lodging it deeper and further from the wound. Chakotay finds a flow of energy in the nebula and believes it is the circulatory system. The ship reaches the injury using the "blood flow", initiates the repair, and leaves through the rupture before it finishes healing.

text: It has recently installed largest hybrid solar system in Australia with an 170KW panel system and additional batteries.

text: Copernicus' 1543 work on the heliocentric model of the solar system tried to demonstrate that the sun was the center of the universe. Few were bothered by this suggestion, and the pope and several archbishops were interested enough by it to want more detail. His model was later used to create the calendar of Pope Gregory XIII. However, the idea that the earth moved around the sun was doubted by most of Copernicus' contemporaries. It contradicted not only empirical observation, due to the absence of an observable stellar parallax, but more significantly at the time, the authority of Aristotle.

text: Copernicus' 1543 work on the heliocentric model of the solar system tried to demonstrate that the sun was the center of the universe. Few were bothered by this suggestion, and the pope and several archbishops were interested enough by it to want more detail. His model was later used to create the

text: calendar

text: of

text: Pope Gregory XIII

text: . However, the idea that the earth moved around the sun was doubted by most of Copernicus' contemporaries. It contradicted not only empirical observation, due to the absence of an observable

text: stellar parallax

text: , but more significantly at the time, the authority of Aristotle.

text: Solar shingles are manufactured by several companies but the two main manufacturers of solar roof shingles are Dow and CertainTeed. Other active companies in the US include SunTegra Solar Roof Systems, and Atlantis Energy Systems (asphalt and slate systems),

text: Solar shingles are manufactured by several companies but the two main manufacturers of solar roof shingles are Dow and

text: CertainTeed

text: . Other active companies in the US include SunTegra Solar Roof Systems, and Atlantis Energy Systems (asphalt and slate systems),

text: Gravity does not play a role, as it is obvious from the fact that wetting takes place independent of the orientation of the pores relative to the direction of gravity. The exact process is still not understood theoretically in detail but its known from experiments that low molar mass systems tend to fill the pores completely, whereas polymers of sufficient chain length just cover the walls. This process happens typically within a minute for temperatures about 50 K above the melting temperature or glass transition temperature, even for highly viscous polymers, such as, for instance, polytetrafluoroethylene, and this holds even for pores with an aspect ratio as large as 10,000. The complete filling, on the other hand, takes days. To obtain nanotubes, the polymer/template system is cooled down to room temperature or the solvent is evaporated, yielding pores covered with solid layers. The resulting tubes can be removed by mechanical forces for tubes up to 10 µm in length, i.e., by just drawing them out from the pores or by selectively dissolving the template. The diameter of the nanotubes, the distribution of the diameter, the homogeneity along the tubes, and the lengths can be controlled.

text: Gravity does not play a role, as it is obvious from the fact that wetting takes place independent of the orientation of the pores relative to the direction of gravity. The exact process is still not understood theoretically in detail but its known from experiments that low molar mass systems tend to fill the pores completely, whereas polymers of sufficient chain length just cover the walls. This process happens typically within a minute for temperatures about 50 K above the melting temperature or glass transition temperature, even for highly viscous polymers, such as, for instance,

text: polytetrafluoroethylene

text: , and this holds even for pores with an aspect ratio as large as 10,000. The complete filling, on the other hand, takes days. To obtain nanotubes, the polymer/template system is cooled down to room temperature or the solvent is evaporated, yielding pores covered with solid layers. The resulting tubes can be removed by mechanical forces for tubes up to 10 µm in length, i.e., by just drawing them out from the pores or by selectively dissolving the template. The diameter of the nanotubes, the distribution of the diameter, the homogeneity along the tubes, and the lengths can be controlled.

text: In order to reduce the size and weight of the magnet of the magnetic sail, it may be possible to inflate the magnetic field using a plasma in the same way that the plasma around the Earth stretches out the Earth's magnetic field in the magnetosphere. In this approach, called mini-magnetospheric plasma propulsion (M2P2), currents that run through the plasma will augment and partially replace the currents in the coil. This is expected to be especially useful far from the Sun, where the increased effective size of a M2P2 sail compensates for the reduced dynamic pressure of the solar wind. The original NASA design proposes a spacecraft containing a can-shaped electromagnet into which a plasma is injected. The plasma pressure stretches the magnetic field and inflates a bubble of plasma around the spacecraft. The plasma then generates a kind of miniaturized magnetosphere around the spacecraft, analogous to the magnetosphere that surrounds the Earth. The protons and electrons which make up the solar wind are deflected by this magnetosphere and the reaction accelerates the spacecraft. The thrust of the M2P2 device would be steerable to some extent, potentially allowing the spacecraft to 'tack' into the solar wind and allowing efficient changes of orbit.

text: In order to reduce the size and weight of the

text: magnet

text: of the magnetic sail, it may be possible to inflate the magnetic field using a plasma in the same way that the plasma around the Earth stretches out the Earth's magnetic field in the

text: magnetosphere

text: . In this approach, called mini-magnetospheric plasma propulsion (M2P2), currents that run through the plasma will augment and partially replace the currents in the coil. This is expected to be especially useful far from the Sun, where the increased effective size of a M2P2 sail compensates for the reduced dynamic pressure of the solar wind. The original

text: NASA

text: design proposes a spacecraft containing a can-shaped electromagnet into which a plasma is injected. The

text: plasma

text: pressure stretches the magnetic field and inflates a bubble of plasma around the spacecraft. The plasma then generates a kind of miniaturized magnetosphere around the spacecraft, analogous to the

text: magnetosphere

text: that surrounds the Earth. The protons and electrons which make up the

text: solar wind

text: are deflected by this magnetosphere and the reaction accelerates the spacecraft. The thrust of the M2P2 device would be steerable to some extent, potentially allowing the spacecraft to 'tack' into the solar wind and allowing efficient changes of orbit.

text: To establish the presence of Al in very ancient materials  requires demonstrating that samples must contain clear excesses of Mg /Mg which correlates with the ratio of Al/Mg. The stable Al is then a surrogate for extinct  Al.  The different Al/Mg ratios are coupled to different chemical phases in a sample and are the result of normal chemical separation processes associated with the growth of the crystals in the CAIs. Clear evidence of the presence of Al at an abundance ratio of 5×10  was shown by Lee, et al.  The value  (Al/Al ~ 5x10) has now been generally established as the high value in early Solar system samples and has been generally used as a refined time scale chronometer for the early Solar system. Lower values imply a more recent time of formation. If this Al is the result of pre-solar stellar sources, then this implies a close connection in time between the formation of the solar system and the production in some exploding star. Many materials which had been presumed to be very early (e.g. chondrules) appear to have formed a few million years later (Hutcheon & Hutchison). Other extinct radioactive nuclei, which clearly had a stellar origin, were then being discovered.

text: In the Solar System, many of the asteroid-sized moons have retrograde orbits, whereas all the large moons except Triton (the largest of Neptune's moons) have prograde orbits. The particles in Saturn's Phoebe ring are thought to have a retrograde orbit because they originate from the irregular moon Phoebe.

text: In the Solar System, many of the asteroid-sized moons have retrograde orbits, whereas all the large moons except

text: Triton

text: (the largest of Neptune's moons) have prograde orbits. The particles in Saturn's

text: Phoebe ring

text: are thought to have a retrograde orbit because they originate from the irregular moon

text: Phoebe

text: Heliocentrism, or heliocentricism, is the astronomical model in which the Earth and planets revolve around a relatively stationary Sun at the center of our Solar System. The word comes from the Greek (ἥλιος helios "sun" and κέντρον kentron "center").

text: Heliocentrism, or heliocentricism, is the

text: astronomical

text: model in which the Earth and planets revolve around a relatively stationary Sun at the center of our

text: Solar System

text: . The word comes from the

text: Greek

text: ἥλιος

text: helios

text: "sun" and

text: κέντρον

text: kentron "center").

text: IRAS 17423-1755 also known as Henize 3-1475 is a planetary nebula, located in the constellation of Sagittarius around 18 000 light-years away from earth. The central star is more than 12 000 times as luminous as our Sun.

text: IRAS 17423-1755 also known as Henize 3-1475 is a

text: planetary nebula

text: , located in the constellation of Sagittarius around 18 000 light-years away from earth. The central star is more than 12 000 times as luminous as our Sun.

text: It was discovered by William Herschel on March 4, 1790. He described it as "a beautiful planetary nebula of a considerable degree of brightness, not very well defined." The nebula is located about 1.23 kiloparsecs (3.79×10 m) or about 4,000 light years from the Sun.

text: It was discovered by

text: William Herschel

text: on March 4, 1790. He described it as "a beautiful planetary nebula of a considerable degree of brightness, not very well defined." The nebula is located about 1.23

text: kiloparsecs

text: (3.79×10 m) or about 4,000

text: light year

text: s from the

text: Sun

text: Many argue that the differences between the ice giants and the gas giants extend to their formation. The Solar System is hypothesised  to have formed from a giant rotating ball of gas and dust known as the presolar nebula. Much of the nebula's gas, primarily hydrogen and helium, formed the Sun, and the dust grains collected together to form the first protoplanets. As the planets grew, some of them eventually accreted enough matter for their gravity to hold on to the nebula's leftover gas. The more gas they held onto, the larger they became; the larger they became, the more gas they held onto until a critical point was reached, and their size began to increase exponentially. The ice giants, with only a few Earth masses of nebular gas, never reached that critical point. Recent simulations of planetary migration have suggested that both ice giants formed closer to the Sun than their present positions, and moved outwards after formation (the Nice model).

text: Many argue that the differences between the ice giants and the gas giants extend to their formation. The Solar System is hypothesised  to have formed from a giant rotating ball of gas and dust known as the

text: presolar nebula

text: . Much of the nebula's gas, primarily hydrogen and helium, formed the Sun, and the dust grains collected together to form the first protoplanets. As the planets grew, some of them eventually accreted enough matter for their gravity to hold on to the nebula's leftover gas. The more gas they held onto, the larger they became; the larger they became, the more gas they held onto until a critical point was reached, and their size began to increase exponentially. The ice giants, with only a few Earth masses of nebular gas, never reached that critical point. Recent simulations of

text: planetary migration

text: have suggested that both ice giants formed closer to the Sun than their present positions, and moved outwards after formation (the

text: Nice model

text: The game takes place in a borderless and randomly generated universe, filled with asteroids, planets, stars and solar systems. Life forms are also present in the game. They appear on planets sufficiently big to store life, and are represented by a variety of ships of different size and attack power. Spaceships are coloured green if they belong to the player's planet, or to a planet that belongs to the player's solar system; red if they belong to an enemy planet or solar system; and white if they don't belong to any planet or system. All the spaceships in the map are controlled by the game's artificial intelligence (AI), and they will constantly engage in combat against enemy ships, asteroids or planets to destroy them.

text: The game takes place in a borderless and randomly generated universe, filled with asteroids, planets, stars and

text: solar system

text: s. Life forms are also present in the game. They appear on planets sufficiently big to store life, and are represented by a variety of ships of different size and attack power. Spaceships are coloured green if they belong to the player's planet, or to a planet that belongs to the player's solar system; red if they belong to an enemy planet or solar system; and white if they don't belong to any planet or system. All the spaceships in the map are controlled by the game's

text: artificial intelligence

text: (AI), and they will constantly engage in combat against enemy ships, asteroids or planets to destroy them.

text: The current standard theory for Solar System formation, the nebular hypothesis, has fallen into and out of favour since its formulation by Emanuel Swedenborg, Immanuel Kant, and Pierre-Simon Laplace in the 18th century. The most significant criticism of the hypothesis was its apparent inability to explain the Sun's relative lack of angular momentum when compared to the planets. However, since the early 1980s studies of young stars have shown them to be surrounded by cool discs of dust and gas, exactly as the nebular hypothesis predicts, which has led to its re-acceptance.

text: The current standard

text: theory

text: for Solar System formation, the

text: nebular hypothesis

text: , has fallen into and out of favour since its formulation by

text: Emanuel Swedenborg

text: Immanuel Kant

text: , and

text: Pierre-Simon Laplace

text: in the 18th century. The most significant criticism of the hypothesis was its apparent inability to explain the Sun's relative lack of

text: angular momentum

text: when compared to the planets. However, since the early 1980s studies of young stars have shown them to be surrounded by cool discs of dust and gas, exactly as the nebular hypothesis predicts, which has led to its re-acceptance.

text: However, over time, the cumulative probability of a chance encounter with a star increases, and disruption of the planets becomes all but inevitable. Assuming that the Big Crunch or Big Rip scenarios for the end of the Universe do not occur, calculations suggest that the gravity of passing stars will have completely stripped the dead Sun of its remaining planets within 1 quadrillion (10) years. This point marks the end of the Solar System. Although the Sun and planets may survive, the Solar System, in any meaningful sense, will cease to exist.

text: However, over time, the

text: cumulative probability

text: of a chance encounter with a star increases, and disruption of the planets becomes all but inevitable. Assuming that the

text: Big Crunch

text: or

text: Big Rip

text: scenarios for the end of the Universe do not occur, calculations suggest that the gravity of passing stars will have completely stripped the dead Sun of its remaining planets within 1 quadrillion (10) years. This point marks the end of the Solar System. Although the Sun and planets may survive, the Solar System, in any meaningful sense, will cease to exist.

text: The main problem is that the beings have no idea what is happening as the planets that are wiped out seem exactly the same, but do not respond to signals and outside communication is impossible. All probes sent do not return, nor reply once they reach the surface of the planet.

text: The first episode illustrates how the formation and behaviour of the Sun affects each planet in the Solar System. During this episode, Cox visits India to view and explain the workings of a total solar eclipse and the partial eclipses that occur on other planets. He travels to the Iguazu Falls to relate the causality between river levels, and sunspot fluctuations. An explanation of the Earth's exposure to the power of the Sun occurs in Death Valley, California, USA, with an experiment inspired by John Herschel's actinometer. He also travels to Norway to observe and explain the defensive role of the Earth's magnetosphere against the sun's solar wind and its role in forming the Aurora Borealis. He also relates the Voyager missions and their continuing exploration of the massive reach of the sun's gravitational forces on objects in the farthest regions of the solar system. Finally, in the clear skies of the Atacama Desert, at the Paranal Observatory he is able to observe, with the naked eye, the myriad of stars on the Milky Way and relates the meaning of their diverse colours as mapped on the Hertzsprung–Russell diagram.

text: The first episode illustrates how the formation and behaviour of the

text: Sun

text: affects each planet in the

text: Solar System

text: . During this episode, Cox visits India to view and explain the workings of a total

text: solar eclipse

text: and the partial eclipses that occur on other planets. He travels to the

text: Iguazu Falls

text: to relate the causality between river levels, and

text: sunspot

text: fluctuations. An explanation of the Earth's exposure to the power of the Sun occurs in

text: Death Valley

text: , California, USA, with an experiment inspired by

text: John Herschel

text: 's

text: actinometer

text: . He also travels to Norway to observe and explain the defensive role of the Earth's

text: magnetosphere

text: against the sun's

text: solar wind

text: and its role in forming the

text: Aurora Borealis

text: . He also relates the Voyager missions and their continuing exploration of the massive reach of the sun's gravitational forces on objects in the

text: farthest regions

text: of the solar system. Finally, in the clear skies of the

text: Atacama Desert

text: , at the

text: Paranal Observatory

text: he is able to observe, with the naked eye, the myriad of stars on the

text: Milky Way

text: and relates the meaning of their diverse colours as mapped on the

text: Hertzsprung–Russell diagram

text: Episode 3 is almost entirely non-combat.  In order to get around the UN's refusal to allow them to leave Earth, GGG stages an elaborate ploy together with their related organizations and the Secretary General of the UN, Rose Approval.  The result is that three of GGG's Division ships and their crew (that is, the entirety of the main cast) are exiled from Earth, and are free to follow Ikumi Kaidou's directions to the Tri-Solar System.  Their enemy is revealed to be the 11 Sol Masters, sentient programs designed to regenerate the Tri-Solar System after the Z-Master was eradicated.

text: , the orbit of shapes and forms

text: , the orbit of shapes and forms

text: Gravity manipulation is a process as commonplace as modern electronics, employed not only in starship propulsion and artificial gravity, but also weapons and shielding against weapons. Controlled/artificial gravity is referred to as "gravy." Gravitic weapons in particular are both common and well developed due to their dual purpose—not only are they potent weapons, they can compress matter into neutronium which can then fuel an annie plant. The degree of this control is dependent on the number of projectors. For example, the battleplate Tunguska was able to manipulate not only individual limbs but individual digits of crew on board the Serial Peacemaker while the much smaller ship can only create nodes of gravity in a few points on the ship and without the same level of control. However, the generation of gravity is beyond the capabilities of the sophonts of the Milky Way, necessitating ships to be constructed around annie plants as sources of gravity to manipulate.

text: The prospects of colonizing the Solar System planets became more dim with increasing discoveries about conditions on them. Conversely, the potential value of the asteroids increased, as a vast accumulation of mineral wealth, accessible in conditions of minimal gravity, and supplementing Earth's dwindling resources. Stories of asteroid mining became more and more numerous since the late 1940s, with the next logical step being depictions of a society on terraformed asteroids — in some cases dug under the surface, in others having dome colonies and in still others provided with an atmosphere which is kept in place by an artificial gravity.

text: The prospects of colonizing the Solar System planets became more dim with increasing discoveries about conditions on them. Conversely, the potential value of the asteroids increased, as a vast accumulation of mineral wealth, accessible in conditions of minimal gravity, and supplementing Earth's dwindling resources. Stories of

text: asteroid mining

text: became more and more numerous since the late 1940s, with the next logical step being depictions of a society on terraformed asteroids — in some cases dug under the surface, in others having dome colonies and in still others provided with an atmosphere which is kept in place by an artificial gravity.

text: Most dust in the Solar System is highly processed dust, recycled from the material out of which the Solar System formed and subsequently collected in the planetesimals, and leftover solid material such as comets and asteroids, and reformed in each of those bodies' collisional lifetimes. During the Solar System's formation history, the most abundant element was (and still is) H. The metallic elements: magnesium, silicon, and iron, which are the principal ingredients of rocky planets, condensed into solids at the highest temperatures of the planetary disk.  Some molecules such as CO, N, NH, and free oxygen, existed in a gas phase. Some molecules, for example, graphite (C) and SiC would condense into solid grains in the planetary disk; but carbon and SiC grains found in meteorites are presolar based on their isotopic compositions, rather than from the planetary disk formation. Some molecules also formed complex organic compounds and some molecules formed frozen ice mantles, of which either could coat the "refractory" (Mg, Si, Fe) grain cores. Stardust once more provides an exception to the general trend, as it appears to be totally unprocessed since its thermal condensation within stars as refractory crystalline minerals. The condensation of graphite occurs within supernova interiors as they expand and cool, and do so even in gas containing more oxygen than carbon, a surprising carbon chemistry made possible by the intense radioactive environment of supernovae. This special example of dust formation has merited specific review.

text: Most dust in the

text: Solar System

text: is highly processed dust, recycled from the material out of which the Solar System formed and subsequently collected in the planetesimals, and leftover solid material such as

text: comet

text: s and

text: asteroid

text: s, and reformed in each of those bodies' collisional lifetimes. During the Solar System's formation history, the most abundant element was (and still is) H. The metallic elements: magnesium, silicon, and iron, which are the principal ingredients of rocky planets, condensed into solids at the highest temperatures of the planetary disk.  Some molecules such as CO, N, NH, and free oxygen, existed in a gas phase. Some molecules, for example, graphite (C) and SiC would condense into solid grains in the planetary disk; but carbon and SiC grains found in meteorites are presolar based on their isotopic compositions, rather than from the planetary disk formation. Some molecules also formed complex organic compounds and some molecules formed frozen ice mantles, of which either could coat the "refractory" (Mg, Si, Fe) grain cores. Stardust once more provides an exception to the general trend, as it appears to be totally unprocessed since its thermal condensation within stars as refractory crystalline minerals. The condensation of graphite occurs within supernova interiors as they expand and cool, and do so even in gas containing more oxygen than carbon, a surprising carbon chemistry made possible by the intense radioactive environment of supernovae. This special example of dust formation has merited specific review.

text: The Sun wobbles around the "true" center known as a barycenter, which lies just inside the Sun. When the Sun's position is 90 degree from the barycenter relative to Earth, it would come close to "unblocking" from view a planet 180 degrees from Earth, enough to reveal the aforementioned hypothetical signature.

text: The Sun wobbles around the "true" center known as a barycenter, which lies

text: just inside the Sun

text: . When the Sun's position is 90 degree from the barycenter relative to Earth, it would come close to "unblocking" from view a planet 180 degrees from Earth, enough to reveal the aforementioned hypothetical signature.

text: MEDPOR is a high-density porous polyethylene (Medpor) Implant manufactured from linear high-density polyethylene.Development in polymer chemistry has allowed introduction of newer biocompatible material such as porous polyethylene (PP) to be introduced into the ﬁeld of orbital implant surgery. Porous polyethylene enucleation implants have been used since at least 1989. It is available in dozens of prefabricated spherical and non-spherical shapes and in different sizes or plain blocks for individualized intraoperative customizing.The material is firm but malleable and allows direct suturing of muscles to implant without wrapping or extra steps. Additionally, the smooth surface is less abrasive and irritating than other materials used for similar purposes. Polyethylene also becomes vascularized, allowing placement of a titanium motility post that joins the implant to the prosthesis in the same way that the peg is used for hydroxyapatite implants.

text: This apparent retrogradation puzzled ancient astronomers, and was one reason they named these bodies 'planets' in the first place: 'Planet' comes from the Greek word for 'wanderer'. In the geocentric model of the Solar System proposed by Apollonius in the third century BCE, retrograde motion was explained by having the planets travel in deferents and epicycles. It was not understood to be an illusion until the time of Copernicus, although the Greek astronomer Aristarchus in 240 BCE proposed a heliocentric model for the Solar System.

text: This apparent retrogradation puzzled ancient astronomers, and was one reason they named these bodies 'planets' in the first place: 'Planet' comes from the Greek word for 'wanderer'. In the

text: geocentric model

text: of the Solar System proposed by

text: Apollonius

text: in the third century BCE, retrograde motion was explained by having the planets travel in

text: deferents and epicycle

text: s. It was not understood to be an illusion until the time of

text: Copernicus

text: , although the Greek astronomer

text: Aristarchus

text: in 240 BCE proposed a

text: heliocentric model

text: for the Solar System.

text: The theory also helped to explain the empirically observed regular pattern of increase in the diameters of the orbits of the planets of the Solar System, from inward to outward.  This result was a natural outcome of the increasing size of "planetary eddies" of gas and dust farther from the center of the early solar system.

text: The theory also helped to explain the empirically observed regular pattern of increase in the diameters of the

text: orbit

text: s of the planets of the Solar System, from inward to outward.  This result was a natural outcome of the increasing size of "planetary eddies" of gas and dust farther from the center of the early solar system.

text: In the anime Dragon Ball Z, gravity simulation plays a key part in various characters' training regime. It is also used to demonstrate the characters' increasing strength. For example, when Goku first arrives on King Kai's planet, he is nearly crushed by the gravity, which is ten times that of Earth's. By the end of his visit, nearly a year later, he is able to move at great speed under such conditions. This method of training gradually appears more and more in the universe, and the gravity gets stronger as well. Ten times Earth's gravity goes from a seemingly indomitable level of opposition to nothing, and several hundred times Earth's gravity becomes the standard. Vegeta even had a Gravity Room built into his house.

text: In the anime

text: Dragon Ball Z

text: , gravity simulation plays a key part in various characters' training regime. It is also used to demonstrate the characters' increasing strength. For example, when

text: Goku

text: first arrives on King Kai's planet, he is nearly crushed by the gravity, which is ten times that of Earth's. By the end of his visit, nearly a year later, he is able to move at great speed under such conditions. This method of training gradually appears more and more in the universe, and the gravity gets stronger as well. Ten times Earth's gravity goes from a seemingly indomitable level of opposition to nothing, and several hundred times Earth's gravity becomes the standard.

text: Vegeta

text: even had a Gravity Room built into his house.

text: The detailed features of the planets are another problem. The solar nebula hypothesis predicts that all planets will form exactly in the ecliptic plane. Instead, the orbits of the classical planets have various (but small) inclinations with respect to the ecliptic. Furthermore, for the gas giants it is predicted that their rotations and moon systems will also not be inclined with respect to the ecliptic plane. However, most gas giants have substantial axial tilts with respect to the ecliptic, with Uranus having a 98° tilt.   The Moon being relatively large with respect to the Earth and other moons which are in irregular orbits with respect to their planet is yet another issue. It is now believed these observations are explained by events which happened after the initial formation of the Solar System.

text: The detailed features of the planets are another problem. The solar nebula hypothesis predicts that all planets will form exactly in the ecliptic plane. Instead, the orbits of the

text: classical planets

text: have various (but small) inclinations with respect to the ecliptic. Furthermore, for the gas giants it is predicted that their rotations and moon systems will also not be inclined with respect to the ecliptic plane. However, most gas giants have substantial axial tilts with respect to the ecliptic, with

text: Uranus

text: having a 98° tilt.   The

text: Moon

text: being relatively large with respect to the Earth and other moons which are in irregular orbits with respect to their planet is yet another issue. It is now believed these observations are explained by events which happened after the initial formation of the Solar System.

text: Ideas concerning the origin and fate of the world date from the earliest known writings; however, for almost all of that time, there was no attempt to link such theories to the existence of a "Solar System", simply because almost no one knew or believed that the Solar System, in the sense we now understand it, existed. The first step towards a theory of Solar System formation was the general acceptance of heliocentrism, the model which placed the Sun at the centre of the system and the Earth in orbit around it. This conception had been gestating for thousands of years, but was only widely accepted by the end of the 17th century. The first recorded use of the term "Solar System" dates from 1704.

text: Ideas concerning the origin and fate of the world date from the earliest known writings; however, for almost all of that time, there was no attempt to link such theories to the existence of a "Solar System", simply because almost no one knew or believed that the Solar System, in the sense we now understand it, existed. The first step towards a theory of

text: Solar System formation

text: was the general acceptance of

text: heliocentrism

text: , the model which placed the Sun at the centre of the system and the Earth in orbit around it. This conception had been gestating for thousands of years, but was only widely accepted by the end of the 17th century. The first recorded use of the term "Solar System" dates from 1704.

text: The asteroid belt formed from the primordial solar nebula as a group of planetesimals. Planetesimals are the smaller precursors of the protoplanets. Between Mars and Jupiter, however, gravitational perturbations from Jupiter imbued the protoplanets with too much orbital energy for them to accrete into a planet. Collisions became too violent, and instead of fusing together, the planetesimals and most of the protoplanets shattered. As a result, 99.9% of the asteroid belt's original mass was lost in the first 100 million years of the Solar System's history. Some fragments eventually found their way into the inner Solar System, leading to meteorite impacts with the inner planets. Asteroid orbits continue to be appreciably perturbed whenever their period of revolution about the Sun forms an orbital resonance with Jupiter. At these orbital distances, a Kirkwood gap occurs as they are swept into other orbits.

text: The asteroid belt formed from the primordial

text: solar nebula

text: as a group of

text: planetesimal

text: s. Planetesimals are the smaller precursors of the

text: protoplanet

text: s. Between Mars and Jupiter, however,

text: gravitational

text: perturbations from Jupiter imbued the protoplanets with too much orbital energy for them to

text: accrete

text: into a planet. Collisions became too violent, and instead of fusing together, the planetesimals and most of the protoplanets shattered. As a result, 99.9% of the asteroid belt's original mass was lost in the first 100 million years of the Solar System's history. Some fragments eventually found their way into the inner

text: Solar System

text: , leading to meteorite impacts with the inner planets. Asteroid orbits continue to be appreciably

text: perturbed

text: whenever their period of revolution about the Sun forms an

text: orbital resonance

text: with Jupiter. At these orbital distances, a

text: Kirkwood gap

text: occurs as they are swept into other orbits.

text: The ideas from this research have had major impact on subsequent solar system exploration; the Galileo (Jupiter satellite tour) mission and the Cassini (Saturn satellite tour) were made possible by the gravity assist method. Flandro (also in 1965) studied gravity assist trajectories to Pluto; these are the basis for the New Horizons mission launched in January 2006, which arrived at Pluto in 2015.

text: The ideas from this research have had major impact on subsequent solar system exploration; the

text: Galileo

text: (Jupiter satellite tour) mission and the

text: Cassini

text: (Saturn satellite tour) were made possible by the gravity assist method. Flandro (also in 1965) studied gravity assist trajectories to Pluto; these are the basis for the

text: New Horizons

text: mission launched in January 2006, which arrived at Pluto in 2015.

text: During the summer of 1964 at the NASA Jet Propulsion Laboratory (JPL), Flandro was assigned the task of studying techniques for exploring the outer planets of the solar system.  In this study  he discovered the rare alignment of the outer planets (Jupiter, Saturn, Uranus, and Neptune) and conceived the Planetary Grand Tour multi-planet mission utilizing the gravity-assist technique to reduce the mission duration from forty years to less than ten years. This work was exploited by NASA with the Voyager 1 and Voyager 2 missions.

text: During the summer of 1964 at the NASA Jet Propulsion Laboratory (

text: JPL

text: ), Flandro was assigned the task of studying techniques for exploring the outer planets of the solar system.  In this study  he discovered the rare alignment of the outer planets (Jupiter, Saturn, Uranus, and Neptune) and conceived the

text: Planetary Grand Tour

text: multi-planet mission utilizing the gravity-assist technique to reduce the mission duration from forty years to less than ten years. This work was exploited by

text: NASA

text: with the

text: Voyager 1

text: and

text: Voyager 2

text: missions.

text: Scafetta has argued, "At least 60% of the warming of the Earth observed since 1970 appears to be induced by natural cycles which are present in the solar system." According to Scafetta, the only reasonable explanation is that the climate system is modulated by astronomical oscillations.  Natural cycles known with certainty are the 11 (Schwabe) and 22 (Hale) year solar cycles, the cycles of the planets and luni-solar nodal cycles. Jupiter has an orbital period of 11.9 years while Saturn has an orbital period of 29.4 years. These periods predict three other major cycles which are associated with Jupiter and Saturn: about 10 years, the opposition of two planets; about 20 years, their synodic cycle; and about 60 years, the repetition of the combined orbits of the two planets. The major lunar cycles are about 18.6 and 8.85 years. Scafetta's climate model is based primarily on a comparison of secular periodic changes of global surface temperature and the Sun´s periodic  movement around barycenter of the Solar System caused by the revolving planets Jupiter, Saturn, Uranus and Neptune. Periodic modulation of Moon´s orbital parameters by these planets and subsequent modulation of lunar tides is also discussed. According to Scafetta, who provides no physical explanation of that process, external forcing of celestial origin simply drives the adjustment of the natural rhythms by letting their own energy flow with the same frequency of the forcing. It just passes to the climatic system the information of how it has to oscillate, not the entire energy to make it oscillate. The effect of a periodic external forcing, even if weak, may become macroscopic and all components of the system gradually synchronize with it.

text: Scafetta has argued, "At least 60% of the warming of the Earth observed since 1970 appears to be induced by natural cycles which are present in the solar system." According to Scafetta, the only reasonable explanation is that the climate system is modulated by astronomical oscillations.  Natural cycles known with certainty are the 11 (

text: Schwabe

text: ) and 22 (

text: Hale

text: ) year solar cycles, the cycles of the planets and luni-solar

text: nodal cycles

text: Jupiter

text: has an orbital period of 11.9 years while

text: Saturn

text: has an orbital period of 29.4 years. These periods predict three other major cycles which are associated with Jupiter and Saturn: about 10 years, the opposition of two planets; about 20 years, their synodic cycle; and about 60 years, the repetition of the combined orbits of the two planets. The major lunar cycles are about

text: 18.6 and 8.85 years

text: . Scafetta's climate model is based primarily on a comparison of secular periodic changes of global surface temperature and the Sun´s periodic  movement around

text: barycenter of the Solar System

text: caused by the revolving planets Jupiter, Saturn, Uranus and Neptune. Periodic modulation of

text: Moon´s orbital parameters

text: by these planets and subsequent modulation of lunar tides is also discussed. According to Scafetta, who provides no physical explanation of that process, external forcing of celestial origin simply drives the adjustment of the natural rhythms by letting their own energy flow with the same frequency of the forcing. It just passes to the climatic system the information of how it has to oscillate, not the entire energy to make it oscillate. The effect of a periodic external forcing, even if weak, may become macroscopic and all components of the system gradually synchronize with it.

text: In the General History of Nature and Theory of the Heavens (Allgemeine Naturgeschichte und Theorie des Himmels) (1755), Kant laid out the Nebular hypothesis, in which he deduced that the Solar System formed from a large cloud of gas, a nebula. Thus he tried to explain the order of the solar system, which Isaac Newton had explained as imposed from the beginning by God. Kant also correctly deduced that the Milky Way was a large disk of stars, which he theorized also formed from a (much larger) spinning cloud of gas. He further suggested that other nebulae might also be similarly large and distant disks of stars. These postulations opened new horizons for astronomy: for the first time extending astronomy beyond the solar system to galactic and extragalactic realms.

text: In the General History of Nature and Theory of the Heavens (Allgemeine Naturgeschichte und Theorie des Himmels) (1755), Kant laid out the

text: Nebular hypothesis

text: , in which he deduced that the

text: Solar System

text: formed from a large cloud of gas, a

text: nebula

text: . Thus he tried to explain the order of the solar system, which

text: Isaac Newton

text: had explained as imposed from the beginning by God. Kant also correctly deduced that the

text: Milky Way

text: was a large disk of stars, which he theorized also formed from a (much larger) spinning cloud of gas. He further suggested that other nebulae might also be similarly large and distant disks of stars. These postulations opened new horizons for astronomy: for the first time extending astronomy beyond the solar system to galactic and extragalactic realms.

text: Ethan Siegel, who is deeply skeptical of the existence of an undiscovered new planet in the Solar System, nevertheless speculates that at least one super-Earth, which have been commonly discovered in other planetary systems but have not been discovered in the Solar System, might have been ejected from the inner Solar System due to the inward migration of Jupiter in the early Solar System. Hal Levison thinks that the chance of an ejected object ending up in the inner Oort cloud is only about 2%, and speculates that many objects must have been thrown past the Oort cloud if one has entered a stable orbit.

text: Ethan Siegel, who is deeply skeptical of the existence of an undiscovered new planet in the Solar System, nevertheless speculates that at least one

text: super-Earth

text: , which have been commonly discovered in other planetary systems but have not been discovered in the Solar System, might have been

text: ejected

text: from the inner Solar System due to the inward migration of Jupiter in the early Solar System.

text: Hal Levison

text: thinks that the chance of an ejected object ending up in the inner

text: Oort cloud

text: is only about 2%, and speculates that many objects must have been thrown past the Oort cloud if one has entered a stable orbit.

text: Most people attribute the introduction of outer billiards to Bernhard Neumann in the late 1950s, though it seemsthat a few people cite an earlier construction in 1945, due to M. Day.  Jürgen Moser popularized the system in the 1970s as a toy model forcelestial mechanics.   This system has been studied classically in the Euclidean plane, and more recently inthe hyperbolic plane.  One can also consider higher-dimensional spaces, though no serious study has yet been made.Bernhard Neumann informally posed the question as to whether or not one canhave unbounded orbits in an outer billiards system, and Moser put it in writing in 1973.Sometimes this basic question has been called the Moser-Neumann question.This question, originally posed for shapes in the Euclidean plane andsolved only recently, has been aguiding problem in the field.

text: Most people attribute the introduction of outer billiards to

text: Bernhard Neumann

text: in the late 1950s, though it seemsthat a few people cite an earlier construction in 1945, due to M. Day.

text: Jürgen Moser

text: popularized the system in the 1970s as a toy model for

text: celestial mechanics

text: .   This system has been studied classically in the

text: Euclidean plane

text: , and more recently inthe

text: hyperbolic plane

text: .  One can also consider higher-dimensional spaces, though no serious study has yet been made.

text: Bernhard Neumann

text: informally posed the question as to whether or not one canhave unbounded orbits in an outer billiards system, and Moser put it in writing in 1973.Sometimes this basic question has been called the Moser-Neumann question.This question, originally posed for shapes in the

text: Euclidean plane

text: andsolved only recently, has been aguiding problem in the field.

text: The design of a solar car is severely limited by the amount of energy input into the car. Solar cars are built for solar car races and also for public use  List of prototype solar-powered cars. Even the best solar cells can only collect limited power and energy over the area of a car's surface. This limits solar cars to ultralight composite bodies to save weight. Solar cars lack the safety and convenience features of conventional vehicles. The first solar family car was built in 2013 by students in the Netherlands.  This vehicle is capable of 550 miles on one charge during sunlight.  It weighs 850 pounds and has a 1.5kw solar array.  Solar vehicles must be light and efficient.  3,000 pound or even 2,000 pound vehicles are less practical.  Stella Lux the predecessor to Stella broke a record with a 932 mile single charge range. The Dutch are trying to commercialize this technology. During racing Stella Lux is capable of 700 miles during daylight. At 45mph Stella Lux has infinite range. This is again due to high efficiency including a Coefficient of drag of .16.  The average family who never drive more than 200 miles a day would never need to charge from the mains.  They would only plug in if they wanted to return energy to the grid. Solar cars are often fitted with gauges and/or wireless telemetry, to carefully monitor the car's energy consumption, solar energy capture and other parameters. Wireless telemetry is typically preferred as it frees the driver to concentrate on driving, which can be dangerous in such a small, lightweight car. The Solar Electric Vehicle system was designed and engineered as an easy to install (2 to 3 hours) integrated accessory system with a custom molded low profile solar module, supplemental battery pack and a proven charge controlling system.

text: The design of a solar car is severely limited by the amount of energy input into the car. Solar cars are built for

text: solar car races

text: and also for public use

text: List of prototype solar-powered cars

text: . Even the best solar cells can only collect limited power and energy over the area of a car's surface. This limits solar cars to ultralight composite bodies to save weight. Solar cars lack the safety and convenience features of conventional vehicles. The first solar family car was built in 2013 by students in the Netherlands.  This vehicle is capable of 550 miles on one charge during sunlight.  It weighs 850 pounds and has a 1.5kw solar array.  Solar vehicles must be light and efficient.  3,000 pound or even 2,000 pound vehicles are less practical.  Stella Lux the predecessor to Stella broke a record with a 932 mile single charge range. The Dutch are trying to commercialize this technology. During racing Stella Lux is capable of 700 miles during daylight. At 45mph Stella Lux has infinite range. This is again due to high efficiency including a

text: Coefficient of drag

text: of .16.  The average family who never drive more than 200 miles a day would never need to charge from the mains.  They would only plug in if they wanted to return energy to the grid. Solar cars are often fitted with gauges and/or

text: wireless telemetry

text: , to carefully monitor the car's energy consumption, solar energy capture and other parameters. Wireless telemetry is typically preferred as it frees the driver to concentrate on driving, which can be dangerous in such a small, lightweight car. The Solar Electric Vehicle system was designed and engineered as an easy to install (2 to 3 hours) integrated accessory system with a custom molded low profile solar module, supplemental battery pack and a proven charge controlling system.

text: The migration of the outer planets is also necessary to account for the existence and properties of the Solar System's outermost regions. Originally, the Kuiper belt was much denser and closer to the Sun, with an outer edge at approximately 30 AU. Its inner edge would have been just beyond the orbits of Uranus and Neptune, which were in turn far closer to the Sun when they formed (most likely in the range of 15–20 AU), and in opposite locations, with Uranus farther from the Sun than Neptune.

text: The migration of the outer planets is also necessary to account for the existence and properties of the

text: Solar System

text: 's outermost regions. Originally, the

text: Kuiper belt

text: was much denser and closer to the

text: Sun

text: , with an outer edge at approximately 30 AU. Its inner edge would have been just beyond the orbits of

text: Uranus

text: and

text: Neptune

text: , which were in turn far closer to the Sun when they formed (most likely in the range of 15–20 AU), and in opposite locations, with Uranus farther from the Sun than Neptune.

text: Solar power in Arizona has the potential to, according to then-Governor Janet Napolitano, make Arizona "the Persian Gulf of solar energy". In 2012, Arizona had 1,106 MW of photovoltaic (PV) solar power systems, and 6 MW of concentrated solar power (CSP), bringing the total to over 1,112 megawatts (MW) of solar power. The Solana Generating Station is a 280 MW parabolic trough solar plant which is the largest plant of its type in the world. Solana includes 6 hours of power storage by molten salt. The plant will provide 5% of the power from Arizona Public Service, the state's largest utility.

text: Solar power in Arizona has the potential to, according to then-Governor

text: Janet Napolitano

text: , make

text: Arizona

text: "the Persian Gulf of solar energy". In 2012, Arizona had 1,106 MW of

text: photovoltaic

text: (PV)

text: solar power system

text: s, and 6 MW of

text: concentrated solar power

text: (CSP), bringing the total to over 1,112

text: megawatt

text: s (MW) of

text: solar power

text: . The

text: Solana Generating Station

text: is a 280 MW

text: parabolic trough

text: solar plant which is the largest plant of its type in the world. Solana includes 6 hours of power

text: storage by molten salt

text: . The plant will provide 5% of the power from

text: Arizona Public Service

text: , the state's largest utility.

text: Comparing this method of detecting extrasolar planets with other techniques such as the transit method, one advantage is that the intensity of the planetary deviation does not depend on the planet mass as strongly as effects in other techniques do. This makes microlensing well suited to finding low-mass planets. It also allows detection of planets further away from the host star than most of the other methods. One disadvantage is that followup of the lens system is very difficult after the event has ended, because it takes a long time for the lens and the source to be sufficiently separated to resolve them separately.

text: Comparing this method of detecting extrasolar planets with other techniques such as the

text: transit

text: method, one advantage is that the intensity of the planetary deviation does not depend on the planet mass as strongly as effects in other techniques do. This makes microlensing well suited to finding low-mass planets. It also allows detection of planets further away from the host star than most of the other methods. One disadvantage is that followup of the lens system is very difficult after the event has ended, because it takes a long time for the lens and the source to be sufficiently separated to resolve them separately.

text: The current understanding of gravity is based on Albert Einstein's general theory of relativity, which is formulated within the framework of classical physics. On the other hand, the nongravitational forces are described within the framework of quantum mechanics, a radically different formalism for describing physical phenomena based on the wave-like nature of matter. The necessity of a quantum mechanical description of gravity follows from the fact that one cannot consistently couple a classical system to a quantum one.

text: The current understanding of

text: gravity

text: is based on

text: Albert Einstein

text: 's

text: general theory of relativity

text: , which is formulated within the framework of

text: classical physics

text: . On the other hand, the

text: nongravitational forces

text: are described within the framework of quantum mechanics, a radically different formalism for describing physical phenomena based on the wave-like nature of matter. The necessity of a quantum mechanical description of gravity follows from the fact that one cannot consistently couple a classical system to a quantum one.

text: When reporting on the masses of extrasolar planets, astronomers often discuss them in terms of multiples of Jupiter's mass ( = 1.9  kg).For example, "Astronomers recently discovered a planet outside our Solar System with a mass of approximately 3 Jupiters." Furthermore, the mass of Jupiter is nearly equal to one thousandth of the mass of the Sun.

text: When reporting on the masses of

text: extrasolar planet

text: s, astronomers often discuss them in terms of multiples of

text: Jupiter's mass

text: ( = 1.9  kg).For example, "Astronomers recently discovered a planet outside our Solar System with a mass of approximately 3 Jupiters." Furthermore, the mass of Jupiter is nearly equal to one thousandth of the mass of the Sun.

text: A straight line connecting the pericenter and apocenter is the line of apsides. This is the major axis of the ellipse, its greatest diameter.  For a two-body system the center of mass of the system lies on this line at one of the two foci of the ellipse. When one body is sufficiently larger than the other it may be taken to be at this focus.  However whether or not this is the case, both bodies are in similar elliptical orbits each having one focus at the system's center of mass, with their respective lines of apsides being of length inversely proportional to their masses.  Historically, in geocentric systems, apsides were measured from the center of the Earth. However, in the case of the Moon, the center of mass of the Earth–Moon system, or Earth–Moon barycenter, as the common focus of both the Moon's and Earth's orbits about each other, is about 74% of the way from Earth's center to its surface.

text: A straight line connecting the pericenter and apocenter is the line of apsides. This is the major axis of the

text: ellipse

text: , its greatest diameter.  For a two-body system the

text: center of mass

text: of the system lies on this line at one of the two

text: foci

text: of the ellipse. When one body is sufficiently larger than the other it may be taken to be at this focus.  However whether or not this is the case, both bodies are in

text: similar

text: elliptical orbits each having one focus at the system's center of mass, with their respective lines of apsides being of length inversely proportional to their masses.  Historically, in

text: geocentric systems

text: , apsides were measured from the center of the Earth. However, in the case of the Moon, the center of mass of the Earth–Moon system, or

text: Earth–Moon barycenter

text: , as the common focus of both the Moon's and Earth's orbits about each other, is about 74% of the way from Earth's center to its surface.

text: 39P/Oterma is a currently inactive periodic comet in the Solar System with an orbital period of nearly 20 years. The size of its nucleus is not known.

text: 39P/Oterma is a currently inactive

text: periodic

text: comet

text: in the

text: Solar System

text: with an

text: orbital period

text: of nearly 20 years. The size of its

text: nucleus

text: is not known.

text: The Galilean moons are the four largest moons of Jupiter—Io, Europa, Ganymede, and Callisto. They were discovered by Galileo Galilei around January 1610 and were the first group of objects found to orbit another planet. Their names derive from the lovers of Zeus. They are among the largest objects in the Solar System with the exception of the Sun and the eight planets, with radii larger than any of the dwarf planets. Ganymede is the largest moon in the Solar System, and is even bigger than the planet Mercury. The three inner moons—Io, Europa, and Ganymede—are in a 4:2:1 orbital resonance with each other.

text: The Galilean moons are the four largest

text: moons of Jupiter

text: Io

text: Europa

text: Ganymede

text: , and

text: Callisto

text: . They were discovered by

text: Galileo Galilei

text: around January 1610 and were the first group of objects found to orbit another planet. Their names derive from the lovers of

text: Zeus

text: . They are among

text: the largest objects

text: in the

text: Solar System

text: with the exception of the

text: Sun

text: and the eight

text: planet

text: s, with radii larger than any of the

text: dwarf planet

text: s. Ganymede is the largest moon in the Solar System, and is even bigger than the planet

text: Mercury

text: . The three inner moons—Io, Europa, and Ganymede—are in a 4:2:1

text: orbital resonance

text: with each other.

text: Aryabhata described a geocentric model of the solar system, in which theSun and Moon are each carried by epicycles. They in turn revolve aroundthe Earth. In this model, which is also found in the Paitāmahasiddhānta (c. CE 425), the motions of the planets are each governed by two epicycles, a smaller manda (slow) and a larger śīghra (fast). The order of the planets in terms of distance from earth is taken as: the Moon, Mercury, Venus, the Sun, Mars, Jupiter, Saturn, and the asterisms."

text: Aryabhata described a

text: geocentric

text: model of the solar system, in which theSun and Moon are each carried by

text: epicycle

text: s. They in turn revolve aroundthe Earth. In this model, which is also found in the Paitāmahasiddhānta (c. CE 425), the motions of the planets are each governed by two epicycles, a smaller manda (slow) and a larger śīghra (fast). The order of the planets in terms of distance from earth is taken as: the

text: Moon

text: Mercury

text: Venus

text: , the

text: Sun

text: Mars

text: Jupiter

text: Saturn

text: , and the

text: asterisms

text: The climate system can spontaneously generate changes in global temperature for years to decades at a time but long-term changes in global temperature require external forcings. These forcings are "external" to the climate system but not necessarily external to Earth. Examples of external forcings include changes in atmospheric composition (e.g., increased concentrations of greenhouse gases), solar luminosity, volcanic eruptions, and variations in Earth's orbit around the Sun.

text: The climate system can spontaneously generate changes in global temperature for years to decades at a time but long-term changes in global temperature require external forcings. These forcings are "external" to the climate system but not necessarily external to Earth. Examples of external forcings include changes in atmospheric composition (e.g., increased concentrations of

text: greenhouse gas

text: es),

text: solar luminosity

text: volcanic

text: eruptions, and

text: variations in Earth's orbit

text: around the Sun.

text: The core produces almost all of the Sun's heat via fusion: the rest of the star is heated by the outward transfer of heat from the core. The energy produced by fusion in the core, except a small part carried out by neutrinos, must travel through many successive layers to the solar photosphere before it escapes into space as sunlight or kinetic energy of particles. The energy conversion per unit time (power) of fusion in the core varies with distance from the solar center. At the center of the Sun, fusion power is estimated by models to be about 276.5 watts/m. Despite its intense temperature, the peak power generating density of the core overall is similar to an active compost heap, and is lower than the power density produced by the metabolism of an adult human. The Sun is much hotter than a compost heap due to the Sun's enormous volume.

text: The core produces almost all of the Sun's

text: heat

text: via

text: fusion

text: : the rest of the star is heated by the outward transfer of heat from the core. The energy produced by fusion in the core, except a small part carried out by

text: neutrinos

text: , must travel through many successive layers to the

text: solar photosphere

text: before it escapes into space as

text: sunlight

text: or

text: kinetic energy

text: of particles. The energy conversion per unit time (power) of fusion in the core varies with distance from the solar center. At the center of the Sun, fusion power is estimated by models to be about 276.5 watts/m. Despite its intense temperature, the peak power generating density of the core overall is similar to an active

text: compost heap

text: , and is lower than the power density produced by the metabolism of an adult human. The Sun is much hotter than a compost heap due to the Sun's enormous volume.

text: Even planets in more stable orbits of a binary star system would suffer other kinds of problems according to her such as climatic problems. As an example, a planet in a binary star system orbiting the larger star would be drawn closer to its gravitational field, causing the planet to endure heat of great temperatures during this period. As the planet passes its larger star and reaches the orbit of its smaller star, the gravitational field of that star would give the planet more distance from it. The distance (perhaps along with the smaller solar projection of the star) would send the planet into extreme frigid temperatures.

text: "Well, this story actually acts as a prequel to the Amory Wars," the center of the Coheed and Cambria mythology, Sanchez explains. The Inferno character, who appears in the Coheed concept as a man named Jesse, "dies in the Good Apollo: Volume One, and is resurrected on present-day Earth. So he leaves the solar system that the story takes place in, and gets resurrected in the present day. But before he can tell the story of the Amory Wars, he needs to tell the story of the Blood Machine.

text: Technologies that directly convert solar energy to electric, heat water, and heat space are included in the tax credit. Solar credits do not have a maximum. 30% of all expenditures can be included in the credit. Eligible technologies for the solar credit are equipment that uses solar energy to generate electricity, to heat or cool (or provide hot water for use in) a structure, or to provide solar process heat.  Hybrid lighting systems that use fiber optics to distribute light and illuminate the inside of a building are also eligible for the credit.  Passive solar systems and solar pool heating systems are not included in the credit.

text: The terms "solar array" and "PV system" are often used interchangeably, despite the fact that the solar array does not encompass the entire system. Moreover, "solar panel" is often used as a synonym for "solar module", although a panel consists of a string of several modules. The term "solar system" is also an often used misnomer for a PV system.

text: The terms "solar array" and "PV system" are often used interchangeably, despite the fact that the solar array does not encompass the entire system. Moreover, "solar panel" is often used as a synonym for "solar module", although a panel consists of a string of several modules. The term "

text: solar system

text: " is also an often used

text: misnomer

text: for a PV system.

text: WASP-10b is an extrasolar planet discovered in 2008.

text: WASP-10b is an

text: extrasolar planet

text: discovered in 2008.

text: Beyond the solar system, extrasolar system studies are also considered a field of interest for this journal. This includes detection of exoplanets, as well as determining whether or not given exoplanets or exosystems can be detected. Also the formation and evolution of these planets and systems are of interest.

text: Yellott's achievements particularly in the area of glazing and solar radiation capture have stood the test of time.  According to Dr. Jeffrey Cook, College of Architecture and Design, Arizona State University, writing the introduction to the Passive Solar Journal's John I. Yellott Memorial issue, "he made major contributions in areas of basic research, instrumentation, analytic methods, applications, collaboration, education, and demonstration." Cook also wrote: "[h]e published no definitive book," but "[a]rticles bearing Yellott's name will remain classics in solar energy literature;" he "developed no distinctive demonstration, no outrageous solar machine, and no landmark building or award winning engineering system," yet "as a consultant he influenced such major architectural feats as the St. Louis Arch and the new Hong Kong and Shanghai Bank;” his analysis “contributed to the industry development of architectural glasses . . . that have gained worldwide use.” His pervasive influence in solar science is largely found in the ongoing work of others,  as “he was a mentor to architects, inventors, and students.”  "Thus,” Cook concluded, “as gentle and persuasive as the sun, Yellott touched many people and places.".

text: In addition to showing how the inner solar system formed, Wetherill's work provided the basis for a model of a giant-impact origin for the Moon and the core of Mercury. It also led to explanations for the isotopic abundances of present-day planetary atmospheres. Recently, Wetherill has shown that Jupiter plays an important role in the evolution of the Solar System; by ejecting comets from the solar system, it offers a protective presence to the inner planets. Wetherill's theoretical work supports discussions on the origins of the Solar System as well as on extrasolar planets.

text: In addition to showing how the inner solar system formed, Wetherill's work provided the basis for a model of a giant-impact origin for the

text: Moon

text: and the core of Mercury. It also led to explanations for the isotopic abundances of present-day planetary atmospheres. Recently, Wetherill has shown that

text: Jupiter

text: plays an important role in the evolution of the

text: Solar System

text: ; by ejecting

text: comets

text: from the solar system, it offers a protective presence to the inner planets. Wetherill's theoretical work supports discussions on the origins of the Solar System as well as on

text: extrasolar planets

text: A series of simulations by Gomes et al. start with a Solar System where the giant planets are in a tight orbital configuration.  This configuration is in itself stable, but assuming a rich trans-Neptunian belt, stray transneptunians interacted with these planets, causing them to migrate slowly during a time of several hundred million years. Jupiter is predicted to migrate inward, whereas the other planets go outwards. By this migration, the Solar System became catastrophically unstable when Jupiter and Saturn reached a 2:1 orbital resonance, causing the outer Solar System to reconfigure rapidly to a wide jovian system. As these planets migrated, resonances would be "swept" through the asteroid belt and Kuiper belt. These resonances would increase the orbital eccentricity of the objects, allowing them to enter the inner Solar System and impact with the terrestrial planets.

text: A series of simulations by Gomes et al. start with a

text: Solar System

text: where the giant planets are in a tight orbital configuration.  This configuration is in itself stable, but assuming a rich

text: trans-Neptunian belt

text: , stray transneptunians interacted with these planets, causing them to migrate slowly during a time of several hundred million years. Jupiter is predicted to migrate inward, whereas the other planets go outwards. By this migration, the Solar System became catastrophically unstable when Jupiter and Saturn reached a 2:1

text: orbital resonance

text: , causing the outer Solar System to reconfigure rapidly to a wide jovian system. As these planets migrated, resonances would be "swept" through the asteroid belt and Kuiper belt. These resonances would increase the

text: orbital eccentricity

text: of the objects, allowing them to enter the inner Solar System and impact with the terrestrial planets.

text: HD 33564 b is an extrasolar planet located approximately 68 light-years away in the constellation of Camelopardalis. This planet orbits around F6V star HD 33564. The planet has an eccentric orbit, ranging in distance from 0.737 AU at periastron to 1.497 AU at apastron.

text: HD 33564 b is an

text: extrasolar planet

text: located approximately 68

text: light-year

text: s away in the

text: constellation

text: of

text: Camelopardalis

text: . This planet orbits around F6V star

text: HD 33564

text: . The planet has an

text: eccentric

text: orbit, ranging in distance from 0.737

text: AU

text: at

text: periastron

text: to 1.497

text: AU

text: at

text: apastron

text: Radiometric methods can be used to date different stages of the history of a meteorite. Condensation from the solar nebula is recorded by calcium-aluminium-rich inclusions and chondrules. These can be dated by using radionuclides that were present in the solar nebula (e.g. Al/Mg, Mn/Cr, U/Pb, I/Xe). After the condensed material accretes to planetesimals of sufficient size melting and differentiation take place. These processes can be dated with the U/Pb, Rb/Sr, Sm/Nd and  Lu/Hf methods. Metallic core formation and cooling can be dated by applying the Re/Os method to iron meteorites. Large scale impact events or even the destruction of the parent body can be dated using the Ar/Ar method and the Pu fission track method. After breakup of the parent body meteoroids are exposed to cosmic radiation. The length of this exposure can be dated using the H/He method, Na/Ne, Kr/Kr. After impact on earth (or any other planet with sufficient cosmic ray shielding) cosmogenic radionuclides decay and can be used to date the time since the meteorite fell. Methods to date this terrestrial exposure are Cl, C, Kr.

text: Radiometric methods can be used to date different stages of the history of a meteorite. Condensation from the

text: solar nebula

text: is recorded by

text: calcium-aluminium-rich inclusion

text: s and

text: chondrules

text: . These can be dated by using radionuclides that were present in the solar nebula (e.g.

text: Al/Mg

text: , Mn/Cr,

text: U/Pb

text: I/Xe

text: ). After the condensed material accretes to

text: planetesimal

text: s of sufficient size melting and differentiation take place. These processes can be dated with the

text: U/Pb

text: Rb/Sr

text: Sm/Nd

text: and

text: Lu/Hf

text: methods. Metallic core formation and cooling can be dated by applying the

text: Re/Os method

text: to

text: iron meteorite

text: s. Large scale impact events or even the destruction of the parent body can be dated using the

text: Ar/Ar method

text: and the

text: Pu fission track method

text: . After breakup of the parent body meteoroids are exposed to cosmic radiation. The length of this exposure can be dated using the

text: H/He method

text: , Na/Ne, Kr/Kr. After impact on earth (or any other planet with sufficient cosmic ray shielding) cosmogenic radionuclides decay and can be used to date the time since the meteorite fell. Methods to date this terrestrial exposure are

text: Cl

text: C

text: , Kr.

text: OGLE-2007-BLG-368Lb is an extrasolar planet located approximately 19,230 light-years away in the constellation of Scorpius, orbiting the star OGLE-2007-BLG-368L. This planet was detected on December 8, 2009 by the gravitational microlensing by Sumi. It has mass 6.94% of Jupiter (i.e. 22 times that of Earth) and is located 3.3 AU from the star when observed. Based on those properties it would classify as a Cold Neptune. It is the second Cold Neptune to be observed, the first being OGLE-2005-BLG-169Lb. This planet is most likely be similar to Uranus and Neptune in the solar system in terms of atmospheric and internal properties.

text: OGLE-2007-BLG-368Lb is an

text: extrasolar planet

text: located approximately 19,230

text: light-year

text: s away in the

text: constellation

text: of

text: Scorpius

text: , orbiting the

text: star

text: . This planet was detected on December 8, 2009 by the

text: gravitational microlensing

text: by Sumi. It has

text: mass

text: 6.94% of

text: Jupiter

text: (i.e. 22 times that of

text: Earth

text: ) and is located 3.3

text: AU

text: from the star when observed. Based on those properties it would classify as a Cold Neptune. It is the second Cold Neptune to be observed, the first being

text: . This planet is most likely be similar to

text: Uranus

text: and

text: Neptune

text: in the

text: solar system

text: in terms of atmospheric and internal properties.

text: The focus for discovering new exoplanets has been on sun-like stars. The catalog of more than 400 exoplanets has proved that these searches are successful, because exoplanets of various sizes have been discovered. However, other star types are also a likely place to discover new exoplanets. New research, announced at the meeting, confirms that planet formation is a natural by-product of star formation. Planet formation occurs even around stars much more massive than the Sun. However, the life of the stars which the planets orbit are so short that intelligent extraterrestrial life is not very likely. A and B type stars were surveyed for the research which involved NASA's Spitzer Space Telescope, the Two Micron All-Sky Survey, and astronomers from the Harvard-Smithsonian Center for Astrophysics (CfA) and the National Optical Astronomy Observatory (NOAO).

text: The focus for discovering new

text: exoplanet

text: s has been on sun-like

text: star

text: s. The catalog of more than 400 exoplanets has proved that these searches are successful, because exoplanets of various sizes have been discovered. However, other star types are also a likely place to discover new exoplanets. New research, announced at the meeting, confirms that planet formation is a natural by-product of star formation. Planet formation occurs even around stars much more massive than the

text: Sun

text: . However, the life of the stars which the planets orbit are so short that intelligent

text: extraterrestrial life

text: is not very likely.

text: A and B type stars

text: were surveyed for the research which involved NASA's Spitzer Space Telescope, the Two Micron All-Sky Survey, and astronomers from the

entity_name: Harvard–Smithsonian Center for Astrophysics

text: Harvard-Smithsonian Center for Astrophysics

text: (CfA) and the

text: National Optical Astronomy Observatory

text: (NOAO).

text: If the Solar System were to pass through a dark nebula, a cloud of cosmic dust, severe global climate change would occur.

text: If the Solar System were to pass through a

text: dark nebula

text: , a cloud of

text: cosmic dust

text: , severe global climate change would occur.

text: This is a list of trans-Neptunian objects (TNO) in the Solar System, along with a list of their moons. A trans-Neptunian object is any minor planet in the Solar System that orbits the Sun at a greater distance on average than Neptune.

text: This is a list of trans-Neptunian objects (TNO) in the Solar System, along with a list of their moons. A

text: trans-Neptunian object

text: is any

text: minor planet

text: in the

text: Solar System

text: that

text: orbit

text: s the

text: Sun

text: at a greater distance on average than

text: Neptune

text: Asteroids are minor planets, especially those of the inner Solar System. The larger ones have also been called planetoids. These terms have historically been applied to any astronomical object orbiting the Sun that did not show the disc of a planet and was not observed to have the characteristics of an active comet. As minor planets in the outer Solar System were discovered and found to have volatile-based surfaces that resemble those of comets, they were often distinguished from asteroids of the asteroid belt. In this article, the term "asteroid" refers to the minor planets of the inner Solar System including those co-orbital with Jupiter.

text: Asteroids are

text: minor planet

text: s, especially those of the

text: inner Solar System

text: . The larger ones have also been called planetoids. These terms have historically been applied to any astronomical object orbiting the

text: Sun

text: that did not show the disc of a planet and was not observed to have the characteristics of an active

text: comet

text: . As

text: minor planets in the outer Solar System

text: were discovered and found to have volatile-based surfaces that resemble those of comets, they were often distinguished from asteroids of the

text: asteroid belt

text: . In this article, the term "asteroid" refers to the minor planets of the inner Solar System including those co-orbital with

text: Jupiter

text: Radioisotopes: Accretion may happen within ~10 years of the start of the solar system for a Mars-sized planet. Among the short-lived radionuclides, Al contributes the most heat. Assuming that Al was created simultaneously with the solar nebula, between 10 years and the effective death of the nuclide Al would contribute about 2×10 J of energy to a planet the size and aluminium proportion of Mars, which is enough to completely melt the planet.

text: Radioisotopes: Accretion may happen within ~10 years of the start of the solar system for a Mars-sized planet. Among the short-lived radionuclides,

text: Al

text: contributes the most heat. Assuming that Al was created simultaneously with the

text: solar nebula

text: , between 10 years and the effective death of the nuclide Al would contribute about 2×10 J of energy to a planet the size and aluminium proportion of Mars, which is enough to completely melt the planet.

text: This is also the direction of the Solar System's motion around the center of the galaxy. Thus, the stars which Kepler observed are roughly the same distance from the galactic center as the Solar System, and also close to the galactic plane. This fact is important if position in the galaxy is related to habitability, as suggested by the Rare Earth hypothesis.

text: This is also the direction of the Solar System's motion around the center of the galaxy. Thus, the stars which Kepler observed are roughly the same distance from the galactic center as the

text: Solar System

text: , and also close to the

text: galactic plane

text: . This fact is important if position in the galaxy is related to habitability, as suggested by the

text: Rare Earth hypothesis

text: Michael York, Kevin Michael Richardson, and Robin Atkin Downes voices the three members of Seven Primes, the first Cybertronians who came into distant galaxies looking for planets where they could build Sun Harvesters. It was during the Dynasty's rule that Sun Harvesters were not to be used in solar systems containing life. In 17,000 B.C.E., one of them defied his brothers' rule about destroying planets with life by powering up the Sun Harvester, an act that ignited a war and earned him the name The Fallen. To stop the Sun's destruction the remaining six stole and hid the Matrix of Leadership, sacrificing themselves to make a tomb of their own bodies, sealing the Matrix away. When Sam dies, he has a vision of the Dynasty and they tell him he has earned his destiny. The Dynasty then resurrects Sam, who uses the Matrix of Leadership to bring Optimus back to life and kills the Fallen. Their bodies resembles their brother, the Fallen, the same hands, body, heads and legs.

text: Michael York

text: , Kevin Michael Richardson, and

text: Robin Atkin Downes

text: voices the three members of Seven Primes, the first Cybertronians who came into distant galaxies looking for planets where they could build Sun Harvesters. It was during the Dynasty's rule that Sun Harvesters were not to be used in solar systems containing life. In 17,000 B.C.E., one of them defied his brothers' rule about destroying planets with life by powering up the Sun Harvester, an act that ignited a war and earned him the name The Fallen. To stop the Sun's destruction the remaining six stole and hid the Matrix of Leadership, sacrificing themselves to make a tomb of their own bodies, sealing the Matrix away. When Sam dies, he has a vision of the Dynasty and they tell him he has earned his destiny. The Dynasty then resurrects Sam, who uses the Matrix of Leadership to bring Optimus back to life and kills the Fallen. Their bodies resembles their brother, the Fallen, the same hands, body, heads and legs.

text: The first atmosphere would have consisted of gases in the solar nebula, primarily hydrogen. In addition, there would probably have been simple hydrides such as those now found in gas giants like Jupiter and Saturn, notably water vapor, methane and ammonia. As the solar nebula dissipated, the gases would have escaped, partly driven off by the solar wind.

text: The

text: first atmosphere

text: would have consisted of gases in the

text: solar nebula

text: , primarily

text: hydrogen

text: . In addition, there would probably have been simple hydrides such as those now found in gas giants like

text: Jupiter

text: and

text: Saturn

text: , notably

text: water

text: vapor,

text: methane

text: and

text: ammonia

text: . As the solar nebula dissipated, the gases would have escaped, partly driven off by the

text: solar wind

text: In addition to stepping in to re-form the solar system, Newton invoked God's active intervention to prevent the stars falling in on each other, and perhaps in preventing the amount of motion in the universe from decaying due to viscosity and friction. In private correspondence Newton sometimes hinted that the force of Gravity was due to an immaterial influence:Leibniz jibed that such an immaterial influence would be a continual miracle; this was another strand of his debate with Clarke.

text: Various dynamical groups of asteroids have been discovered orbiting in the inner Solar System. Their orbits are perturbed by the gravity of other bodies in the Solar System and by the Yarkovsky effect. Significant populations include:

text: Various dynamical groups of asteroids have been discovered orbiting in the inner Solar System. Their orbits are perturbed by the gravity of other bodies in the Solar System and by the

text: Yarkovsky effect

text: . Significant populations include:

text: The Science of Aliens asks the question "are we alone in the Universe?" through a combination of artifacts, interactive and audiovisual exhibits. The exhibition has an introduction looking at science fiction archetypes before going on to look at what scientists can tell us about the real possibilities for alien life. The first section explores the variety of life on Earth and the extreme conditions in which it can survive. It looks at recent missions to moons and planets in the Solar System and what they can tell us about alien life before going on to examine some extra-solar planets.

text: The Science of Aliens asks the question "are we alone in the Universe?" through a combination of artifacts, interactive and audiovisual exhibits. The exhibition has an introduction looking at science fiction archetypes before going on to look at what scientists can tell us about the real possibilities for alien life. The first section explores the variety of life on Earth and the extreme conditions in which it can survive. It looks at recent missions to moons and planets in the

text: Solar System

text: and what they can tell us about alien life before going on to examine some extra-solar planets.

text: The head which is produced by the solar furnace is considered to be very clean, without and pollutants. There are different ways of using this energy, such as hydrogen fuel production, foundry applications and high temperature testing. “Solar furnace of Uzbekistan” (which is sometimes called as the sun institute of Uzbekistan) can deal up with all the facilities which are listed above, and can save a lot of recourses, when it is used for melting the metal. Solar furnace of Uzbekistan is a complex optical and mechanical construction, which is supplied with the automatically controlled systems, and it consists of 63 various flat mirrors which track the sun in unison and redirect the solar thermal energy towards the crucible. Solar furnace of Uzbekistan was first opened in the year of 1981 on May, and it is located 1100 meters above the sea level. Solar furnace of Uzbekistan covers huge area on the mountains, and consists of 4 complex subdivisions, which are: the main building of “Solar furnace of Uzbekistan”, heliostatic field, concentrator and manufacturing tower. The “Solar furnace of Uzbekistan” was ready for consumption in 6 years, which means it was built between the years of 1981 and 1987. The place for the “Solar furnace of Uzbekistan” is chosen carefully, because the sun shines there for 270 days a year. The small solar furnace at the complex has the diameter of 2 meters. The heliostatic field of the “Solar furnace of Uzbekistan” currently consists of about 62 heliostats which are installed in a staggered order. The field uses 12090 mirrors in total, and Is the largest concentrator in the world with the area of 1849 square meters. The concentrator at the “Solar furnace of Uzbekistan” uses 10700 mirrors, and the southern part of the concentrator is covered with special sunscreens. The whole “Solar furnace of Uzbekistan” is controlled by the employees from the laboratory which is located on the 6th floor, and the observation ground is located on the highest spot.

text: The head which is produced by the solar furnace is considered to be very clean, without and pollutants. There are different ways of using this energy, such as hydrogen fuel production, foundry applications and high temperature testing. “Solar furnace of Uzbekistan” (which is sometimes called as the sun institute of Uzbekistan) can deal up with all the facilities which are listed above, and can save a lot of recourses, when it is used for melting the metal. Solar furnace of Uzbekistan is a complex optical and mechanical construction, which is supplied with the automatically controlled systems, and it consists of 63 various flat mirrors which track the

text: sun

text: in unison and redirect the solar thermal energy towards the crucible. Solar furnace of Uzbekistan was first opened in the year of 1981 on May, and it is located 1100 meters above the sea level. Solar furnace of Uzbekistan covers huge area on the mountains, and consists of 4 complex subdivisions, which are: the main building of “Solar furnace of Uzbekistan”, heliostatic field, concentrator and manufacturing tower. The “Solar furnace of Uzbekistan” was ready for consumption in 6 years, which means it was built between the years of 1981 and 1987. The place for the “Solar furnace of Uzbekistan” is chosen carefully, because the sun shines there for 270 days a year. The small solar furnace at the complex has the diameter of 2 meters. The heliostatic field of the “Solar furnace of Uzbekistan” currently consists of about 62 heliostats which are installed in a staggered order. The field uses 12090 mirrors in total, and Is the largest concentrator in the world with the area of 1849 square meters. The concentrator at the “Solar furnace of Uzbekistan” uses 10700 mirrors, and the southern part of the concentrator is covered with special sunscreens. The whole “Solar furnace of Uzbekistan” is controlled by the employees from the laboratory which is located on the 6th floor, and the observation ground is located on the highest spot.

text: An ice giant is a giant planet composed mainly of elements heavier than hydrogen and helium, such as oxygen, carbon, nitrogen, and sulfur. There are two known ice giants in the Solar System, Uranus and Neptune. Since 2014, there has been theoretical evidence of the existence of a possible third ice giant, which, if it exists, would be the Solar System's ninth planet.

text: An ice giant is a

text: giant planet

text: composed mainly of elements heavier than

text: hydrogen

text: and

text: helium

text: , such as

text: oxygen

text: carbon

text: nitrogen

text: , and

text: sulfur

text: . There are two known ice giants in the

text: Solar System

text: Uranus

text: and

text: Neptune

text: . Since 2014, there has been theoretical evidence of the existence of a possible third ice giant, which, if it exists, would be the Solar System's

text: ninth planet

text: The main use of this technology is in residential buildings where the demand for hot water has a large impact on energy bills. This generally means a situation with a large family, or a situation in which the hot water demand is excessive due to frequent laundry washing. Commercial applications include laundromats, car washes, military laundry facilities and eating establishments. The technology can also be used for space heating if the building is located off-grid or if utility power is subject to frequent outages. Solar water heating systems are most likely to be cost effective for facilities with water heating systems that are expensive to operate, or with operations such as laundries or kitchens that require large quantities of hot water. Unglazed liquid collectors  are commonly used to heat water for swimming pools but can also be applied to large scale water pre-heating. When loads are large relative to available collector area the bulk of the water heating can be done at low temperature, lower than at swimming pool temperatures where unglazed collectors are well established in the marketplace as the right choice.  Because these collectors need not withstand high temperatures, they can use less expensive materials such as plastic or rubber. Many unglazed collectors are made of polypropylene and must be drained fully to avoid freeze damage when air temperatures drop below 44F on clear nights. A smaller but growing percentage of unglazed collectors are flexible meaning they can withstand water freezing solid inside their absorber. The freeze concern only need be the water filled piping and collector manifolds in a hard freeze condition. Unglazed solar hot water systems should be installed to "drainback" to a storage tank whenever solar radiation is insufficient. There are no thermal shock concerns with unglazed systems.  Commonly used in swimming pool heating since solar energy's early beginnings, unglazed solar collectors heat swimming pool water directly without the need for antifreeze or heat exchangers. Hot water solar systems require heat exchangers due to contamination possibilities and in the case of unglazed collectors, the  pressure difference between the solar working fluid (water) and the load (pressurized cold city water). Large scale unglazed solar hot water heaters like the one at the Minoru Aquatic Center in Richmond BC  operate at lower temperatures than evacuated tube or boxed and glazed collector systems so they require larger more expensive heat exchangers but all other components including vented storage tanks and uninsulated plastic PVC piping reduce costs of this alternative dramatically compared to the higher temperature collector types. When heating hot water we are actually heating cold to warm and warm to hot. We can heat cold to warm as efficiently with unglazed collectors as we can heat warm to hot with high temperature collectors

text: The main use of this technology is in residential buildings where the demand for hot water has a large impact on energy bills. This generally means a situation with a large family, or a situation in which the hot water demand is excessive due to frequent laundry washing. Commercial applications include laundromats, car washes, military laundry facilities and eating establishments. The technology can also be used for space heating if the building is located off-grid or if utility power is subject to frequent outages.

text: Solar water heating

text: In the migration hypothesis, hot Jupiters are thought to form at a distance from the star beyond the frost line, where the planet can form from rock, ice and gases. The planets then migrate inwards to the star where they eventually form a stable orbit. The planets usually move by type II orbital migration, or possibly via interaction with other planets or a stellar companion. It has been shown that approximately 50% of hot Jupiters have distant Jupiter-mass or larger companions. The migration happens during the solar nebula phase, i.e. when gas is still present. Energetic stellar photons and strong stellar winds at this time remove most of the remaining nebula.

text: In the migration hypothesis, hot Jupiters are thought to form at a distance from the star beyond the

text: frost line

text: , where the planet can form from rock, ice and gases. The planets then

text: migrate

text: inwards to the star where they eventually form a stable orbit. The planets usually move by

text: type II

text: orbital migration, or possibly via interaction with other planets or a

text: stellar companion

text: . It has been shown that approximately 50% of hot Jupiters have distant Jupiter-mass or larger companions. The migration happens during the

text: solar nebula

text: phase, i.e. when gas is still present. Energetic stellar photons and strong stellar winds at this time remove most of the remaining nebula.

text: For many thousands of years, civilizations, with a few notable exceptions, did not recognize the existence of the Solar System. It was believed Earth was stationary at the center of the Universe and categorically different from the divine or etherea objects that moved through the sky. Although the Greek philosopher Aristarchus of Samos had speculated on a heliocentric reordering of the cosmos, Nicolaus Copernicus first developed a mathematically predictive heliocentric system. His 17th-century successors, Galileo Galilei, Johannes Kepler, and Isaac Newton, developed a modern understanding of physics that led to the gradual acceptance of the idea that Earth moves around the Sun and that the planets are governed by the same physical laws that govern Earth. In more recent times, this led to the investigation of geological phenomena such as mountains and craters and seasonal meteorological phenomena such as clouds, dust storms, and ice caps on the other planets.

text: For many thousands of years, civilizations, with a few notable exceptions, did not recognize the existence of the

text: Solar System

text: . It was believed Earth was stationary at the center of the

text: Universe

text: and categorically different from the divine or etherea objects that moved through the sky. Although the Greek philosopher

text: Aristarchus of Samos

text: had speculated on a

text: heliocentric

text: reordering of the cosmos,

text: Nicolaus Copernicus

text: first developed a mathematically predictive heliocentric system. His 17th-century successors,

text: Galileo Galilei

text: Johannes Kepler

text: , and

text: Isaac Newton

text: , developed a modern understanding of

text: physics

text: that led to the gradual acceptance of the idea that Earth moves around the Sun and that the planets are governed by the same physical laws that govern Earth. In more recent times, this led to the investigation of geological phenomena such as mountains and craters and seasonal meteorological phenomena such as clouds, dust storms, and ice caps on the other planets.

text:
1. There is no one center of all the celestial circles or spheres.
2. The center of the earth is not the center of the universe, but only of gravity and of the lunar sphere.
3. All the spheres revolve about the sun as their midpoint, and therefore the sun is the center of the universe.
4. The ratio of the earth's distance from the sun to the height of the firmament (outermost celestial sphere containing the stars) is so much smaller than the ratio of the earth's radius to its distance from the sun that the distance from the earth to the sun is imperceptible in comparison with the height of the firmament.
5. Whatever motion appears in the firmament arises not from any motion of the firmament, but from the earth's motion. The earth together with its circumjacent elements performs a complete rotation on its fixed poles in a daily motion, while the firmament and highest heaven abide unchanged.
6. What appear to us as motions of the sun arise not from its motion but from the motion of the earth and our sphere, with which we revolve about the sun like any other planet. The earth has, then, more than one motion.

text:
1. There is no one center of all the celestial circles or spheres.
2. The center of the earth is not the center of the universe, but only of gravity and of the lunar sphere.
3. All the spheres revolve about the sun as their midpoint, and therefore the sun is the center of the universe.
4. The ratio of the earth's distance from the sun to the height of the

text: firmament

text:
(outermost celestial sphere containing the stars) is so much smaller than the ratio of the earth's radius to its distance from the sun that the distance from the earth to the sun is imperceptible in comparison with the height of the firmament.
5. Whatever motion appears in the firmament arises not from any motion of the firmament, but from the earth's motion. The earth together with its circumjacent elements performs a complete rotation on its fixed poles in a daily motion, while the firmament and highest heaven abide unchanged.
6. What appear to us as motions of the sun arise not from its motion but from the motion of the earth and our sphere, with which we revolve about the sun like any other planet. The earth has, then, more than one motion.

text: The Seven Soldiers are reunited but the Earth-1 Diana Prince had been attacked by the Iron Hand. She is able to overcome him, but he is no longer able to stop the giant hand. The heroes create a new Nebula Rod to deal with the giant hand. Unfortunately, whoever uses the Nebula Rod is certain to perish (as did the Crimson Avenger's partner Wing, revealed to be the Unknown Soldier of Victory, when the Nebula Man was stopped). While the heroes argue over who will make the sacrifice, the android Red Tornado takes the Nebula Rod and destroys the Hand, destroying himself in the process.

text: The Seven Soldiers are reunited but the Earth-1

text: Diana Prince

text: had been attacked by the Iron Hand. She is able to overcome him, but he is no longer able to stop the giant hand. The heroes create a new Nebula Rod to deal with the giant hand. Unfortunately, whoever uses the Nebula Rod is certain to perish (as did the Crimson Avenger's partner Wing, revealed to be the Unknown Soldier of Victory, when the Nebula Man was stopped). While the heroes argue over who will make the sacrifice, the android Red Tornado takes the Nebula Rod and destroys the Hand, destroying himself in the process.

text: On April 15, 2000, the Geneva Extrasolar Planet Search Team announced the discovery of a 3 M planet in a 226-day orbit. Three years later on June 30, 2003, the same two teams using the same method discovered a 3.5 M second planet orbiting about halfway between the distances of Mars and Jupiter (or in the middle of the asteroid belt) in the solar system from the star.

text: On April 15, 2000, the

text: Geneva Extrasolar Planet Search Team

text: announced the discovery of a 3

text: M

text: planet

text: in a 226-day orbit. Three years later on June 30, 2003, the same two teams using the same method discovered a 3.5 M

text: second planet

text: orbiting about halfway between the distances of

text: Mars

text: and

text: Jupiter

text: (or in the middle of the

text: asteroid belt

text: ) in the

text: solar system

text: from the star.

text: The jumping-Jupiter scenario specifies an evolution of giant-planet migration described by the Nice model, in which an ice giant (Uranus, Neptune, or an additional Neptune-mass planet) is scattered inward by Saturn and outward by Jupiter, causing the step-wise separation of their orbits. The jumping-Jupiter scenario was proposed by Ramon Brasser, Alessandro Morbidelli, Rodney Gomes, Kleomenis Tsiganis, and Harold Levison after their studies revealed that the smooth divergent migration of Jupiter and Saturn resulted in an inner Solar System significantly different from the current Solar System. The sweeping of secular resonances through the inner Solar System during the migration excited the eccentricities of the terrestrial planets beyond current values and left an asteroid belt with an excessive ratio of high- to low-inclination objects. The step-wise separation of Jupiter and Saturn described in the jumping-Jupiter scenario can allow these resonances to quickly cross the inner Solar System without altering orbits excessively, although the terrestrial planets remain sensitive to its passage. The jumping-Jupiter scenario also results in a number of other differences with the original Nice model. The fraction of lunar impactors from the core of the asteroid belt during the Late Heavy Bombardment is significantly reduced, most of the Jupiter trojans are captured during Jupiter's encounters with the ice giant, as are Jupiter's irregular satellites. In the jumping-Jupiter scenario, the likelihood of preserving four giant planets on orbits resembling their current ones appears to increase if the early Solar System originally contained an additional ice giant, which was later ejected by Jupiter into interstellar space. However, this remains an atypical result, as is the preservation of the current orbits of the terrestrial planets.

text: The jumping-Jupiter scenario specifies an evolution of giant-

text: planet migration

text: described by the

text: Nice model

text: , in which an

text: ice giant

text: (Uranus, Neptune, or an

text: additional Neptune-mass planet

text: ) is scattered inward by Saturn and outward by Jupiter, causing the step-wise separation of their

text: orbit

text: s. The jumping-Jupiter scenario was proposed by Ramon Brasser, Alessandro Morbidelli, Rodney Gomes, Kleomenis Tsiganis, and Harold Levison after their studies revealed that the smooth divergent migration of Jupiter and Saturn resulted in an

text: inner Solar System

text: significantly different from the current Solar System. The sweeping of

text: secular resonance

text: s through the inner Solar System during the migration excited the

text: eccentricities

text: of the

text: terrestrial planet

text: s beyond current values and left an

text: asteroid belt

text: with an excessive ratio of high- to low-

text: inclination

text: objects. The step-wise separation of Jupiter and Saturn described in the jumping-Jupiter scenario can allow these resonances to quickly cross the inner Solar System without altering orbits excessively, although the terrestrial planets remain sensitive to its passage. The jumping-Jupiter scenario also results in a number of other differences with the original Nice model. The fraction of lunar impactors from the core of the asteroid belt during the

text: Late Heavy Bombardment

text: is significantly reduced, most of the

text: Jupiter trojan

text: s are captured during Jupiter's encounters with the ice giant, as are Jupiter's

text: irregular satellites

text: . In the jumping-Jupiter scenario, the likelihood of preserving four giant planets on orbits resembling their current ones appears to increase if the early

text: Solar System

text: originally contained an

text: additional ice giant

text: , which was later ejected by Jupiter into

text: interstellar space

text: . However, this remains an atypical result, as is the preservation of the current orbits of the terrestrial planets.

text: Molten salt can be employed as a thermal energy storage method to retain thermal energy collected by a solar tower or solar trough of a concentrated solar power plant, so that it can be used to generate electricity in bad weather or at night. It was demonstrated in the Solar Two project from 1995–1999. The system is predicted to have an annual efficiency of 99%, a reference to the energy retained by storing heat before turning it into electricity, versus converting heat directly into electricity. The molten salt mixtures vary. The most extended mixture contains sodium nitrate, potassium nitrate and calcium nitrate. It is non-flammable and nontoxic, and has already been used in the chemical and metals industries as a heat-transport fluid, so experience with such systems exists in non-solar applications.

text: Molten salt can be employed as a thermal energy storage method to retain thermal energy collected by a

text: solar tower

text: or

text: solar trough

text: of a

text: concentrated solar power plant

text: , so that it can be used to generate electricity in bad weather or at night. It was demonstrated in the

text: Solar Two

text: project from 1995–1999. The system is predicted to have an annual efficiency of 99%, a reference to the energy retained by storing heat before turning it into electricity, versus converting heat directly into electricity. The molten salt mixtures vary. The most extended mixture contains

text: sodium nitrate

text: potassium nitrate

text: and

text: calcium nitrate

text: . It is non-flammable and nontoxic, and has already been used in the chemical and metals industries as a heat-transport fluid, so experience with such systems exists in non-solar applications.

text: Lead researcher Ivan Ramirez explained the significance of finding solar siblings in a press release for the University of Texas at which he works. "We want to know where we were born. If we can figure out in what part of the galaxy the Sun formed, we can constrain conditions on the early solar system. That could help us understand why we are here." He also said there was a "small, but not zero" chance that planets with life might orbit solar sibling stars, because during the frequent collisions during planetary formation material might have travelled from one system to another. He said the siblings might be "key candidates" in the search for extraterrestrial life. A scenario for transfer of life by this means might require life or a precursor molecule to be shielded from radiation for millions of years, dormant within an outgoing chunk of planetary debris one meter or more in diameter that is produced by a meteorite impact, until this new meteorite impacts on a different planet. Such an unlikely event might have transferred life from another planet to Earth or vice versa.

text: Lead researcher Ivan Ramirez explained the significance of finding solar siblings in a press release for the

text: University of Texas

text: at which he works. "We want to know where we were born. If we can figure out in what part of the galaxy the Sun formed, we can constrain conditions on the early solar system. That could help us understand why we are here." He also said there was a "small, but not zero" chance that planets with life might orbit solar sibling stars, because during the frequent collisions during planetary formation material might have travelled from one system to another. He said the siblings might be "key candidates" in the search for extraterrestrial life. A scenario for transfer of life by this means might require life or a precursor molecule to be shielded from radiation for millions of years, dormant within an outgoing chunk of planetary debris one meter or more in diameter that is produced by a meteorite impact, until this new meteorite impacts on a different planet. Such an unlikely event might have transferred life from another planet to Earth or vice versa.

text: The first attempt to describe the shape of the Milky Way and the position of the Sun within it was carried out by William Herschel in 1785 by carefully counting the number of stars in different regions of the visible sky. He produced a diagram of the shape of the Milky Way with the Solar System close to the center.<ref>William Herschel (1785) "On the Construction of the Heavens," Philosophical Transactions of the Royal Society of London, 75 : 213–266.  Herschel's diagram of the Milky Way appears immediately after the article's last page.  See:

text: The first attempt to describe the shape of the Milky Way and the position of the Sun within it was carried out by

text: William Herschel

text: in 1785 by carefully counting the number of stars in different regions of the visible sky. He produced a diagram of the shape of the Milky Way with the Solar System close to the center.<ref>William Herschel (1785) "On the Construction of the Heavens," Philosophical Transactions of the Royal Society of London, 75 : 213–266.  Herschel's diagram of the Milky Way appears immediately after the article's last page.  See:

text: In standard Big Bang cosmology, the Universe has no center and no edge. A third idea for potentially solving the distant starlight problem, put forward by Russell Humphreys in 1994 and refined by others since, sets this assumption aside and proposes that the Earth is located near the center of a finite and bounded (i.e. spherical) Universe. Time dilation would have allowed billions of years of time to elapse at the edge of the Universe in its own reference frame, while only a few days passed on Earth. Humphreys also finds a place for the "waters above (and below) the Earth," locating them at the edge ("above") and the centre ("below") of the Universe.

text: In standard Big Bang cosmology, the Universe has no center and no edge. A third idea for potentially solving the distant starlight problem, put forward by Russell Humphreys in 1994 and refined by others since, sets this assumption aside and proposes that the Earth is located near the center of a finite and bounded (i.e. spherical) Universe.

text: Time dilation

text: would have allowed billions of years of time to elapse at the edge of the Universe in its own reference frame, while only a few days passed on Earth. Humphreys also finds a place for the "waters above (and below) the Earth," locating them at the edge ("above") and the centre ("below") of the Universe.

text: SRECs represent the environmental attributes from a solar facility, and are produced each time a solar system produces one thousand Kilowatt-hours (KWh) of electricity. For every 1000 kilowatt-hours of electricity produced by an eligible solar facility, one SREC is awarded. In order for a solar facility to be credited with that SREC, the system must be certified and registered.

text: The inner Solar System, the region of the Solar System inside 4 AU, was too warm for volatile molecules like water and methane to condense, so the planetesimals that formed there could only form from compounds with high melting points, such as metals (like iron, nickel, and aluminium) and rocky silicates. These rocky bodies would become the terrestrial planets (Mercury, Venus, Earth, and Mars). These compounds are quite rare in the Universe, comprising only 0.6% of the mass of the nebula, so the terrestrial planets could not grow very large. The terrestrial embryos grew to about 0.05 Earth masses () and ceased accumulating matter about 100,000 years after the formation of the Sun; subsequent collisions and mergers between these planet-sized bodies allowed terrestrial planets to grow to their present sizes (see Terrestrial planets below).

text: The

text: inner Solar System

text: , the region of the Solar System inside 4 AU, was too warm for volatile molecules like water and methane to condense, so the planetesimals that formed there could only form from compounds with high melting points, such as metals (like

text: iron

text: nickel

text: , and

text: aluminium

text: ) and rocky

text: silicate

text: s. These rocky bodies would become the

text: terrestrial planet

text: s (

text: Mercury

text: Venus

text: Earth

text: , and

text: Mars

text: ). These compounds are quite rare in the Universe, comprising only 0.6% of the mass of the nebula, so the terrestrial planets could not grow very large. The terrestrial embryos grew to about 0.05

text: Earth mass

text: es () and ceased accumulating matter about 100,000 years after the formation of the Sun; subsequent collisions and mergers between these planet-sized bodies allowed terrestrial planets to grow to their present sizes (see

text: Terrestrial planets

text: below).

text: Studying how the weather works on other planets has been helpful in understanding how weather works on Earth.  A famous landmark in the Solar System, Jupiter's Great Red Spot, is an anticyclonic storm known to have existed for at least 300 years.  However, weather is not limited to planetary bodies.  A star's corona is constantly being lost to space, creating what is essentially a very thin atmosphere throughout the Solar System.  The movement of mass ejected from the Sun is known as the solar wind.

text: Studying how the weather works on other planets has been helpful in understanding how weather works on Earth.  A famous landmark in the

text: Solar System

text: Jupiter

text: 's

text: Great Red Spot

text: , is an

text: anticyclonic

text: storm known to have existed for at least 300 years.  However, weather is not limited to planetary bodies.  A star's

text: corona

text: is constantly being lost to space, creating what is essentially a very thin atmosphere throughout the Solar System.  The movement of mass ejected from the

text: Sun

text: is known as the

text: solar wind

text: Astrometry is the oldest search method for extrasolar planets, and was originally popular because of its success in characterizing astrometric binary star systems. It dates back at least to statements made by William Herschel in the late 18th century. He claimed that an unseen companion was affecting the position of the star he cataloged as 70 Ophiuchi. The first known formal astrometric calculation for an extrasolar planet was made by W. S. Jacob in 1855 for this star. Similar calculations were repeated by others for another half-century until finally refuted in the early 20th century.For two centuries claims circulated of the discovery of unseen companions in orbit around nearby star systems that all were reportedly found using this method, culminating in the prominent 1996 announcement, of multiple planets orbiting the nearby star Lalande 21185 by George Gatewood. None of these claims survived scrutiny by other astronomers, and the technique fell into disrepute. Unfortunately, changes in stellar position are so small—and atmospheric and systematic distortions so large—that even the best ground-based telescopes cannot produce precise enough measurements. All claims of a planetary companion of less than 0.1 solar mass, as the mass of the planet, made before 1996 using this method are likely spurious. In 2002, the Hubble Space Telescope did succeed in using astrometry to characterize a previously discovered planet around the star Gliese 876.

text: Astrometry is the oldest search method for

text: extrasolar planets

text: , and was originally popular because of its success in characterizing

text: astrometric binary star

text: systems. It dates back at least to statements made by

text: William Herschel

text: in the late 18th century. He claimed that an unseen companion was affecting the position of the star he cataloged as

text: 70 Ophiuchi

text: . The first known formal astrometric calculation for an extrasolar planet was made by

text: W. S. Jacob

text: in 1855 for this star. Similar calculations were repeated by others for another half-century until finally refuted in the early 20th century.For two centuries claims circulated of the discovery of unseen companions in orbit around nearby star systems that all were reportedly found using this method, culminating in the prominent 1996 announcement, of multiple planets orbiting the nearby star

text: Lalande 21185

text: by

text: George Gatewood

text: . None of these claims survived scrutiny by other astronomers, and the technique fell into disrepute. Unfortunately, changes in stellar position are so small—and atmospheric and systematic distortions so large—that even the best ground-based telescopes cannot produce precise enough measurements. All claims of a planetary companion of less than 0.1 solar mass, as the mass of the planet, made before 1996 using this method are likely spurious. In 2002, the

text: Hubble Space Telescope

text: did succeed in using astrometry to characterize a previously discovered planet around the star

text: Gliese 876

text: According to the idea, the solar system had its origin in a gigantic star into which a smaller, dead, waterlogged star fell. This impact caused a huge explosion which flung fragments of the smaller star out into interstellar space where the water condensed and froze into giant blocks of ice. A ring of such blocks formed, which we now call the Milky Way, as well as a number of solar systems among which was our own, but with many more planets than currently exist.

text: According to the idea, the solar system had its origin in a gigantic star into which a smaller, dead, waterlogged star fell. This impact caused a huge explosion which flung fragments of the smaller star out into interstellar space where the water condensed and froze into giant blocks of ice. A ring of such blocks formed, which we now call the

text: Milky Way

text: , as well as a number of solar systems among which was our own, but with many more planets than currently exist.

text: Extraterrestrial natural channels are found elsewhere in the Solar System than the Earth and the longest and widest of which are the outflow channels on Mars and the channels of Venus many of which are tens of kilometres wide (the network of channels flowing from Argyre Planitia on Mars for example is 8000 km in length and the Baltis Vallis Venus is 7000 km compared to the 6,650 km Nile, the largest active channel on Earth). The exact formation of these large ancient channels is unknown although it is theorised that those on Mars may have been formed due to catastrophic flooding and on Venus by lava flow. In planetary science the term "rille" is sometimes used for similar formations found on The Moon and Mercury that are of inconclusive origin. Channels have also been recently discovered on Titan. The Saturnian moon has the only known permanently active channels in the Solar System other than Earth, the largest known of which is 400 km in length.  These are believed to be formed from flowing hydrocarbons in the hypothesized methanological cycle.

text: Extraterrestrial natural channels are found elsewhere in the

text: Solar System

text: than the

text: Earth

text: and the longest and widest of which are the

text: outflow channels

text: on

text: Mars

text: and the channels of

text: Venus

text: many of which are tens of kilometres wide (the network of channels flowing from

text: Argyre Planitia

text: on Mars for example is 8000 km in length and the

text: Baltis Vallis

text: Venus is 7000 km compared to the 6,650 km Nile, the largest active channel on Earth). The exact formation of these large ancient channels is unknown although it is theorised that those on Mars may have been formed due to catastrophic flooding and on Venus by lava flow. In

text: planetary science

text: the term "

text: rille

text: " is sometimes used for similar formations found on

text: The Moon

text: and

text: Mercury

text: that are of inconclusive origin. Channels have also been recently discovered on

text: Titan

text: . The Saturnian moon has the only known permanently active channels in the Solar System other than Earth, the largest known of which is 400 km in length.  These are believed to be formed from flowing hydrocarbons in the hypothesized

text: methanological cycle

text: Over the course of the Solar System's evolution, comets were ejected out of the inner Solar System by the gravity of the giant planets, and sent thousands of AU outward to form the Oort cloud, a spherical outer swarm of cometary nuclei at the farthest extent of the Sun's gravitational pull. Eventually, after about 800 million years, the gravitational disruption caused by galactic tides, passing stars and giant molecular clouds began to deplete the cloud, sending comets into the inner Solar System. The evolution of the outer Solar System also appears to have been influenced by space weathering from the solar wind, micrometeorites, and the neutral components of the interstellar medium.

text: Over the course of the Solar System's evolution,

text: comet

text: s were ejected out of the inner Solar System by the gravity of the giant planets, and sent thousands of AU outward to form the

text: Oort cloud

text: , a spherical outer swarm of cometary nuclei at the farthest extent of the Sun's gravitational pull. Eventually, after about 800 million years, the gravitational disruption caused by

text: galactic tide

text: s, passing stars and giant molecular clouds began to deplete the cloud, sending comets into the inner Solar System. The evolution of the outer Solar System also appears to have been influenced by

text: space weathering

text: from the solar wind, micrometeorites, and the neutral components of the

text: interstellar medium

text: This nebula began to form about 200 years ago, and primarily consists of molecular gas. The outer part of the nebula is the result of interaction between rapid bi-polar outflow and the gas that was ejected when the star was passing through its asymptotic giant branch phase. The lobes are inclined about 24° to the line of sight. The energy being radiatedfrom the nebula consists of scattered light from the star at the core, light being emitted from a compact HII region surrounding the star, and energy from the shock-excited gas in the lobes.

text: This nebula began to form about 200 years ago, and primarily consists of molecular gas. The outer part of the nebula is the result of interaction between rapid bi-polar outflow and the gas that was ejected when the star was passing through its

text: asymptotic giant branch

text: phase. The lobes are inclined about 24° to the line of sight. The energy being radiatedfrom the nebula consists of scattered light from the star at the core, light being emitted from a compact

text: HII region

text: surrounding the star, and energy from the shock-excited gas in the lobes.

text: For most of history, humanity did not recognize or understand the concept of the Solar System. Most people up to the Late Middle Ages–Renaissance believed Earth to be stationary at the centre of the universe and categorically different from the divine or ethereal objects that moved through the sky. Although the Greek philosopher Aristarchus of Samos had speculated on a heliocentric reordering of the cosmos, Nicolaus Copernicus was the first to develop a mathematically predictive heliocentric system. In the 17th century, Galileo Galilei, Johannes Kepler, and Isaac Newton developed an understanding of physics that led to the gradual acceptance of the idea that Earth moves around the Sun and that the planets are governed by the same physical laws that governed Earth. The invention of the telescope led to the discovery of further planets and moons. Improvements in the telescope and the use of unmanned spacecraft have enabled the investigation of geological phenomena, such as mountains, craters, seasonal meteorological phenomena, such as clouds, dust storms and ice caps on the other planets.

text: For most of history, humanity did not recognize or understand the concept of the Solar System. Most people up to the

text: Late Middle Ages

text: Renaissance

text: believed Earth to be stationary at the centre of the

text: universe

text: and categorically different from the divine or ethereal objects that moved through the sky. Although the

text: Greek

text: philosopher

text: Aristarchus of Samos

text: had speculated on a heliocentric reordering of the cosmos,

text: Nicolaus Copernicus

text: was the first to develop a mathematically predictive

text: heliocentric

text: system. In the 17th century,

text: Galileo Galilei

text: Johannes Kepler

text: , and

text: Isaac Newton

text: developed an understanding of

text: physics

text: that led to the gradual acceptance of the idea that Earth moves around the Sun and that the planets are governed by the same physical laws that governed Earth. The invention of the telescope led to the discovery of further planets and moons. Improvements in the telescope and the use of

text: unmanned spacecraft

text: have enabled the investigation of geological phenomena, such as

text: mountains

text: craters

text: , seasonal meteorological phenomena, such as

text: clouds

text: dust storms

text: and

text: ice caps

text: on the other planets.

text: The non-geocentric model of the Universe was proposed by the Pythagorean philosopher Philolaus (d. 390 BC), who taught that at the center of the Universe was a "central fire", around which the Earth, Sun, Moon and Planets revolved in uniform circular motion.  This system postulated the existence of a counter-earth collinear with the Earth and central fire, with the same period of revolution around the central fire as the Earth.  The Sun revolved around the central fire once a year, and the stars were stationary.  The Earth maintained the same hidden face towards the central fire, rendering both it and the "counter-earth" invisible from Earth.  The Pythagorean concept of uniform circular motion remained unchallenged for approximately the next 2000 years, and it was to the Pythagoreans that Copernicus referred to show that the notion of a moving Earth was neither new nor revolutionary. Kepler gave an alternative explanation of the Pythagoreans' "central fire" as the Sun, "as most sects purposely hid[e] their teachings".

text: The non-geocentric model of the

text: Universe

text: was proposed by the

text: Pythagorean

text: philosopher

text: Philolaus

text: (d. 390 BC), who taught that at the center of the Universe was a "central fire", around which the

text: Earth

text: Sun

text: Moon

text: and

text: Planets

text: revolved in uniform circular motion.  This system postulated the existence of a counter-earth collinear with the Earth and central fire, with the same period of revolution around the central fire as the Earth.  The Sun revolved around the central fire once a year, and the stars were stationary.  The Earth maintained the same hidden face towards the central fire, rendering both it and the "counter-earth" invisible from Earth.  The Pythagorean concept of uniform circular motion remained unchallenged for approximately the next 2000 years, and it was to the Pythagoreans that Copernicus referred to show that the notion of a moving Earth was neither new nor revolutionary.

text: Kepler

text: gave an alternative explanation of the Pythagoreans' "central fire" as the Sun, "as most sects purposely hid[e] their teachings".

text: "Any Russian or foreign launch vehicle can orbit such containers," Bryukhanov said. The size of the container and its shape depend on payload characteristics. "This can be an airtight instrument module or a fuel tanker," the deputy general designer continued. "Moreover, depressurized platform featuring large scientific equipment and auxiliary systems, i.e., solar batteries that cannot be stored inside the airtight module".

text: Libra is home to the star Gliese 581, which has a planetary system consisting of at least 6 planets. Both Gliese 581 d,  and Gliese 581 g are debatably the most promising candidates for life, although Gliese 581 g's existences has been disputed and has not been entirely confirmed or agreed on in the scientific community.  Gliese 581 c is considered to be the first Earth-like extrasolar planet to be found within its parent star's habitable zone. Gliese 581 e is possibly the smallest mass exoplanet orbiting a normal star found to date  All of these exoplanets are of significance for establishing the likelihood of life outside of the Solar System.

text: Libra is home to the star

text: Gliese 581

text: , which has a

text: planetary system

text: consisting of at least 6 planets. Both

text: Gliese 581 d

text: ,  and

text: Gliese 581 g

text: are debatably the most promising candidates for life, although Gliese 581 g's existences has been disputed and has not been entirely confirmed or agreed on in the scientific community.

text: Gliese 581 c

text: is considered to be the first Earth-like

text: extrasolar planet

text: to be found within its parent star's

text: habitable zone

text: Gliese 581 e

text: is possibly the smallest mass

text: exoplanet

text: orbiting a normal star found to date  All of these exoplanets are of significance for establishing the likelihood of

text: life

text: outside of the

text: Solar System

text: The appearance of extrasolar planets is largely unknown because of the difficulty in making direct observations of extrasolar planets. In addition, analogies with planets in the Solar System can apply for few of the extrasolar planets known; because most are wholly unlike any of our planets, for example the hot Jupiters.

text: The appearance of extrasolar planets is largely unknown because of the difficulty in making direct observations of

text: extrasolar planets

text: . In addition, analogies with planets in the

text: Solar System

text: can apply for few of the extrasolar planets known; because most are wholly unlike any of our planets, for example the

text: hot Jupiter

text: s.

text: The Principia deals primarily with massive bodies in motion, initially under a variety of conditions and hypothetical laws of force in both non-resisting and resisting media, thus offering criteria to decide, by observations, which laws of force are operating in phenomena that may be observed. It attempts to cover hypothetical or possible motions both of celestial bodies and of terrestrial projectiles. It explores difficult problems of motions perturbed by multiple attractive forces. Its third and final book deals with the interpretation of observations about the movements of planets and their satellites. It shows how astronomical observations prove the inverse square law of gravitation (to an accuracy that was high by the standards of Newton's time); offers estimates of relative masses for the known giant planets and for the Earth and the Sun; defines the very slow motion of the Sun relative to the solar-system barycenter; shows how the theory of gravity can account for irregularities in the motion of the Moon; identifies the oblateness of the figure of the Earth; accounts approximately for marine tides including phenomena of spring and neap tides by the perturbing (and varying) gravitational attractions of the Sun and Moon on the Earth's waters; explains the precession of the equinoxes as an effect of the gravitational attraction of the Moon on the Earth's equatorial bulge; and gives theoretical basis for numerous phenomena about comets and their elongated, near-parabolic orbits.

text: From the Helium isotope abundance data, the cosmic D/H value is estimated to be around 20 ppm which is much lower than the terrestrial D/H ratio of 150 ppm. The enrichment of D/H from the proto-solar reservoir occurs for most of the planets except for Jupiter and Saturn, the massive gaseous planets. The D/H ratios of the atmospheres of Venus and Mars are ~2 × 10 and ~8 × 10 respectively. The D/H ratios of Uranus and Neptune is larger than that of protosolar reservoir by a factor of around 3 due to their Deuterium-rich icy cores. The D/H ratios for comets are much larger than the values for the planets in the solar system with δD value of around 1000‰.

text: From the

text: Helium

text: isotope abundance data, the cosmic D/H value is estimated to be around 20 ppm which is much lower than the terrestrial D/H ratio of 150 ppm. The enrichment of D/H from the proto-solar reservoir occurs for most of the planets except for Jupiter and Saturn, the massive gaseous planets. The D/H ratios of the atmospheres of

text: Venus

text: and Mars are ~2 × 10 and ~8 × 10 respectively. The D/H ratios of Uranus and Neptune is larger than that of protosolar reservoir by a factor of around 3 due to their Deuterium-rich icy cores. The D/H ratios for comets are much larger than the values for the planets in the solar system with δD value of around 1000‰.

text: Following the Babylonians, significant advances in astronomy were made in ancient Greece and the Hellenistic world. Greek astronomy is characterized from the start by seeking a rational, physical explanation for celestial phenomena. In the 3rd century BC, Aristarchus of Samos estimated the size and distance of the Moon and Sun, and was the first to propose a heliocentric model of the solar system. In the 2nd century BC, Hipparchus discovered precession, calculated the size and distance of the Moon and invented the earliest known astronomical devices such as the astrolabe. Hipparchus also created a comprehensive catalog of 1020 stars, and most of the constellations of the northern hemisphere derive from Greek astronomy. The Antikythera mechanism (c. 150–80 BC) was an early analog computer designed to calculate the location of the Sun, Moon, and planets for a given date. Technological artifacts of similar complexity did not reappear until the 14th century, when mechanical astronomical clocks appeared in Europe.

text: Following the Babylonians, significant advances in astronomy were made in

text: ancient Greece

text: and the

text: Hellenistic

text: world.

text: Greek astronomy

text: is characterized from the start by seeking a rational, physical explanation for celestial phenomena. In the 3rd century BC,

text: Aristarchus of Samos

text: estimated the

text: size and distance of the Moon and Sun

text: , and was the first to propose a

text: heliocentric

text: model of the

text: solar system

text: . In the 2nd century BC,

text: Hipparchus

text: discovered

text: precession

text: , calculated the size and distance of the Moon and invented the earliest known astronomical devices such as the

text: astrolabe

text: . Hipparchus also created a comprehensive catalog of 1020 stars, and most of the

text: constellation

text: s of the northern hemisphere derive from Greek astronomy. The

text: Antikythera mechanism

text: (c. 150–80 BC) was an early

text: analog computer

text: designed to calculate the location of the

text: Sun

text: Moon

text: , and

text: planets

text: for a given date. Technological artifacts of similar complexity did not reappear until the 14th century, when mechanical

text: astronomical clock

text: s appeared in

text: Europe

text: Theoretical planetologists also use numerical models to understand how the Solar System planets were formed and develop in the future, their thermal evolution, their tectonics, how magnetic fields are formed in planetary interiors, how convection processes work in the cores and mantles of terrestrial planets and in the interiors of gas giants, how their lithospheres deform, the orbital dynamics of planetary satellites, how dust and ice are transported on the surface of some planets (such as Mars), and how the atmospheric circulation takes place over a planet.

text: Theoretical planetologists also use

text: numerical

text: models to understand how the

text: Solar System

text: planets were formed and develop in the future, their

text: thermal

text: evolution, their

text: tectonics

text: , how

text: magnetic field

text: s are formed in planetary interiors, how

text: convection

text: processes work in the

text: cores

text: and

text: mantle

text: s of

text: terrestrial planet

text: s and in the interiors of

text: gas giants

text: , how their

text: lithosphere

text: s deform, the

text: orbit

text: al dynamics of planetary satellites, how

text: dust

text: and

text: ice

text: are transported on the surface of some planets (such as

text: Mars

text: ), and how the

text: atmospheric circulation

text: takes place over a planet.

text: In Galileo’s day the prevailing model of the universe was based on the assertion by the Greek astronomer Ptolemy almost 15 centuries earlier that all celestial objects revolve around Earth (see Ptolemaic system). Observation of the phases of Venus was inconsistent with this view but was consistent with the Polish astronomer Nicolaus Copernicus’s idea that the solar system is centered on the Sun. Galileo’s observation of the phases of Venus provided the first direct observational evidence for Copernican theory.

text: The first third of the book deals with the proximate universe. The journey starts with the Moon and its formation from an impact with the infant Earth. Next stop is the outer Solar System and the amazing process by particles of dust grew into planets. The nearest star is the place where star formation is considered, followed by the Orion Nebula, where young stars are forming at a furious rate. The last stop in the nearby universe is the center of our galaxy, site of a black hole four million times the mass of the Sun.

text: The first third of the book deals with the proximate universe. The journey starts with the

text: Moon and its formation

text: from an impact with the infant Earth. Next stop is the

text: outer Solar System

text: and the amazing process by particles of dust grew into

text: planets

text: . The nearest star is the place where star formation is considered, followed by the

text: Orion Nebula

text: , where young stars are forming at a furious rate. The last stop in the nearby universe is the

text: center of our galaxy

text: , site of a

text: black hole

text: four million times the mass of the

text: Sun

text: If the total annual primary production of biomass is just over 100 billion (1.0E+11) tonnes of Carbon /yr, and the energy reserve per metric tonne of biomass is between about 1.5E3 – 3E3 Kilowatt hours (5E6 – 10E6 BTU), or 24.8 TW average, then biomass could in principle provide 1.4 times the approximate annual  150E3 Terrawatt hours required for current world energy consumption. For reference, the total solar power on Earth is 174 kTW.  The biomass equivalent to solar energy ratio is 143 ppm (parts per million), given current living system coverage on Earth. Best in class solar cell efficiency is (20–40)%. Additionally, Earth's internal radioactive energy production, largely the driver for volcanic activity, continental drift, etc.,  is in the same range of power, 20 TW. At some 50% carbon mass content in biomass, annual production, this corresponds to about 6% of atmospheric carbon content in CO2 (for the current 400 ppm).

text: If the total annual

text: primary production

text: of

text: biomass

text: is just over 100 billion (1.0E+11) tonnes of Carbon /yr, and the energy reserve per

text: metric tonne

text: of biomass is between about 1.5E3 – 3E3

text: Kilowatt hour

text: s (5E6 – 10E6 BTU), or 24.8 TW average, then biomass could in principle provide 1.4 times the approximate annual  150E3 Terrawatt hours required for current

text: world energy consumption

text: . For reference, the total solar power on Earth is 174 kTW.  The biomass equivalent to solar energy ratio is 143 ppm (parts per million), given current living system coverage on Earth. Best in class solar cell efficiency is (20–40)%. Additionally, Earth's internal radioactive energy production, largely the driver for volcanic activity, continental drift, etc.,  is in the same range of power, 20 TW. At some 50% carbon mass content in biomass, annual production, this corresponds to about 6% of atmospheric carbon content in CO2 (for the current 400 ppm).

text: The Okayama Planet Search Program (OPSP) was started in 2001 with the goal of spectroscopically searching for planetary systems around stars. It reported on the detection of 3 new extrasolar planets: (18 Delphini b, ksi Aql b, and 41 Lyncis b), around intermediate-mass G and K giants 18 Delphini, Xi Aquilae, and HD 81688. Also, it updated the orbital parameters of HD 104985 b, the first planet discovered around the G giants from the survey, by using the data collected during the past six years. Since 2001, it has been conducting a precise Doppler survey of about 300 G and K giants using a 1.88m telescope, the High Dispersion Echelle Spectrograph (HIDES), and an iodine absorption cell I2 cell at the Okayama Astrophysical Observatory (OAO).

text: The Okayama Planet Search Program (OPSP) was started in 2001 with the goal of spectroscopically searching for planetary systems around stars. It reported on the detection of 3 new

text: extrasolar planets

text: 18 Delphini b

text: ksi Aql b

text: , and

text: 41 Lyncis b

text: ), around intermediate-mass G and

text: K giants

text: 18 Delphini

text: Xi Aquilae

text: , and

text: HD 81688

text: . Also, it updated the orbital parameters of

text: HD 104985 b

text: , the first planet discovered around the

text: G giants

text: from the survey, by using the data collected during the past six years. Since 2001, it has been conducting a precise

text: Doppler

text: survey

text: of about 300 G and K giants using a 1.88m telescope, the High Dispersion Echelle Spectrograph (

text: HIDES

text: ), and an iodine absorption cell

text: I2 cell

text: at the

text: Okayama Astrophysical Observatory

text: (OAO).

text: Comets are thought to orbit the Sun at great distances, but then be perturbed by passing stars and the galactic tides. As they come into or leave the inner Solar System they may have their orbit changed by the planets, or alternatively be ejected from the Solar System. It is also possible they may collide with the Sun or a planet.

text: Comets are thought to orbit the Sun at great distances, but then be perturbed by passing stars and the

text: galactic tide

text: s. As they come into or leave the inner Solar System they may have their orbit changed by the planets, or alternatively be ejected from the Solar System. It is also possible they may collide with the Sun or a planet.

text: The geological history of Earth follows the major events in Earth's past based on the geologic time scale, a system of chronological measurement based on the study of the planet's rock layers (stratigraphy). Earth formed about 4.54 billion years ago by accretion from the solar nebula, a disk-shaped mass of dust and gas left over from the formation of the Sun, which also created the rest of the Solar System.

text: The geological history of Earth follows the major events in Earth's past based on the

text: geologic time scale

text: , a system of

text: chronological measurement

text: based on the study of the planet's rock layers (

text: stratigraphy

text: ). Earth formed

text: about 4.54 billion years ago

text: by accretion from the

text: solar nebula

text: , a disk-shaped mass of dust and gas left over from the formation of the Sun, which also created the rest of the

text: Solar System

text: According to this definition, there are eight known planets in the Solar System.  The definition distinguishes planets from smaller bodies and is not useful outside the Solar System, where smaller bodies cannot be found yet. Extrasolar planets, or exoplanets, are covered separately under a complementary 2003 draft guideline for the definition of planets, which distinguishes them from dwarf stars, which are larger.

text: According to this definition, there are

text: eight known planets

text: in the Solar System.  The definition distinguishes planets from smaller bodies and is not useful outside the Solar System, where smaller bodies cannot be found yet.

text: Extrasolar planet

text: s, or exoplanets, are covered separately under a complementary 2003 draft guideline for the definition of planets, which distinguishes them from dwarf stars, which are larger.

text: The biggest technical challenge that has faced the probe designers is the heat to which the latter is subject when it is near the sun. At 0.3 astronomical units from the Sun which undergoes heat flow is 11 solar constant (11 times the amount of received heat in the Earth's orbit) or 22,4 kW per square meter exposed. The temperature can then reach 370 °C. The solar cells and the central compartment of the equipment and instruments are located must be maintained at much lower temperatures. The solar cell should not exceed 165 °C, while the central compartment should be maintained between -10 °C and + 20 °C (or 14 °F and 68 °F). These restrictions require to reject 96% of the heat received from the sun. The conical shape of the solar panels is one of the measures taken to reduce the flow of heat. By tilting the solar panels with respect to sunlight arriving perpendicularly to the axis of the probe, reflected a greater proportion of the solar radiation. Furthermore, as discussed above, the solar panels are covered 50% of its surface mirrors developed by NASA dubbed Second Surface Mirrors (SSM). These are made of fused quartz, with a silver film on the inner face, which is itself covered with a dielectric material. The central compartment sides are entirely covered by these mirrors. For additional protection, multi-layer insulation, consisting of 18 layers of 0.25 mm Mylar or Kapton (depending on location) held apart from each other by small plastic pins intended to prevent the formation of thermal bridges, was used to partially cover the core compartment. In addition to these passive devices, the probe uses an active system based on a system of movable louvers in a star lining the bottom and top side of the compartment. The opening thereof is controlled separately by a bimetal spring whose length varies depending on the temperature and causes the opening or closing of the shutter. Resistors are also used to keep a temperature sufficient for certain equipment.

text: The biggest technical challenge that has faced the probe designers is the heat to which the latter is subject when it is near the sun. At 0.3

text: astronomical units

text: from the Sun which undergoes heat flow is 11 solar constant (11 times the amount of received heat in the Earth's orbit) or 22,4

text: kW

text: per square meter exposed. The temperature can then reach 370 °C. The

text: solar cells

text: and the central compartment of the equipment and instruments are located must be maintained at much lower temperatures. The

text: solar cell

text: should not exceed 165 °C, while the central compartment should be maintained between -10 °C and + 20 °C (or 14 °F and 68 °F). These restrictions require to reject 96% of the heat received from the sun. The conical shape of the solar panels is one of the measures taken to reduce the flow of heat. By tilting the solar panels with respect to sunlight arriving perpendicularly to the axis of the probe, reflected a greater proportion of the

text: solar radiation

text: . Furthermore, as discussed above, the solar panels are covered 50% of its surface mirrors developed by

text: NASA

text: dubbed Second Surface Mirrors (SSM). These are made of fused quartz, with a silver film on the inner face, which is itself covered with a dielectric material. The central compartment sides are entirely covered by these mirrors. For additional protection,

text: multi-layer insulation

text: , consisting of 18 layers of 0.25 mm

text: Mylar

text: or

text: Kapton

text: (depending on location) held apart from each other by small plastic pins intended to prevent the formation of thermal bridges, was used to partially cover the core compartment. In addition to these passive devices, the probe uses an active system based on a system of movable louvers in a star lining the bottom and top side of the compartment. The opening thereof is controlled separately by a bimetal spring whose length varies depending on the temperature and causes the opening or closing of the shutter. Resistors are also used to keep a temperature sufficient for certain equipment.

text: HD 231701 b is an extrasolar planet approximately 354 light years away in the constellation of Sagitta. This planet orbits at 0.55 AU from the star HD 231701 with eccentricity 0.19. Based on its high mass of 1.08 M, the planet is probably a gas giant, meaning the planet has no solid surface and have composition similar to solar system's outer planets.

text: HD 231701 b is an

text: extrasolar planet

text: approximately 354

text: light year

text: s away in the

text: constellation

text: of

text: Sagitta

text: . This planet orbits at 0.55

text: AU

text: from the star

text: HD 231701

text: with

text: eccentricity

text: 0.19. Based on its high mass of 1.08 M, the planet is probably a

text: gas giant

text: , meaning the planet has no solid surface and have composition similar to

text: solar system

text: 's

text: outer planets

text: Note that while Pathfinder is referred to as OV-098, she should not be confused with MPTA-098 - the Main Propulsion Test Article, a steel frame (looking nothing like an Orbiter) used to test the Space Shuttle Main Engines. Pathfinder was originally a "fit check" unit, a simple mockup resembling the production Orbiters in size, shape and weight, intended to be used to ensure that ground handling facilities would be sized to handle Orbiters. She was later rebuilt to resemble them cosmetically, and is currently on display with the external tank used during the propulsion tests (designated MPTA-ET). To further add to the confusion, it appears that Pathfinder was never formally numbered, and the OV-098 designation is both unofficial and retroactive. MPTA-098 was later rebuilt into the Shuttle-C mockup during the 1990s; it is currently in storage at the Stennis Space Center.

text: Note that while

text: Pathfinder

text: is referred to as OV-098, she should not be confused with

text: - the Main Propulsion Test Article, a steel frame (looking nothing like an Orbiter) used to test the

text: Space Shuttle Main Engine

text: s. Pathfinder was originally a "fit check" unit, a simple mockup resembling the production Orbiters in size, shape and weight, intended to be used to ensure that ground handling facilities would be sized to handle Orbiters. She was later rebuilt to resemble them cosmetically, and is currently on display with the

text: external tank

text: used during the propulsion tests (designated

text: MPTA-ET

text: ). To further add to the confusion, it appears that Pathfinder was never formally numbered, and the OV-098 designation is both unofficial and retroactive. MPTA-098 was later rebuilt into the

text: Shuttle-C

text: mockup during the 1990s; it is currently in storage at the

text: Stennis Space Center

text: A past resonance between Jupiter and Saturn may have played a dramatic role in early Solar System history. A 2004 computer model by Alessandro Morbidelli of the Observatoire de la Côte d'Azur in Nice suggested that the formation of a 1:2 resonance between Jupiter and Saturn (due to interactions with planetesimals that caused them to migrate inward and outward, respectively) created a gravitational push that propelled both Uranus and Neptune into higher orbits, and in some scenarios caused them to switch places, which would have doubled Neptune's distance from the Sun. The resultant expulsion of objects from the proto-Kuiper belt as Neptune moved outwards could explain the Late Heavy Bombardment 600 million years after the Solar System's formation and the origin of Jupiter's Trojan asteroids. An outward migration of Neptune could also explain the current occupancy of some of its resonances (particularly the 2:5 resonance) within the Kuiper belt.

text: A past resonance between Jupiter and Saturn may have played a dramatic role in early Solar System history. A 2004

text: computer model

text: by

text: Alessandro Morbidelli

text: of the

text: Observatoire de la Côte d'Azur

text: in

text: Nice

text: suggested that the formation of a 1:2 resonance between Jupiter and Saturn (due to interactions with

text: planetesimals

text: that caused them to migrate inward and outward, respectively) created a gravitational push that propelled both Uranus and Neptune into higher orbits, and in some scenarios caused them to switch places, which would have doubled Neptune's distance from the Sun. The resultant expulsion of objects from the proto-Kuiper belt as Neptune moved outwards could explain the

text: Late Heavy Bombardment

text: 600 million years after the Solar System's formation and the origin of Jupiter's

text: Trojan asteroid

text: s. An outward migration of Neptune could also explain the current occupancy of some of its resonances (particularly the 2:5 resonance) within the Kuiper belt.

text: Passive solar technologies include direct and indirect solar gain for space heating, solar water heating systems based on the thermosiphon, use of thermal mass and phase-change materials for slowing indoor air temperature swings, solar cookers, the solar chimney for enhancing natural ventilation, and earth sheltering.

text: Passive solar technologies include direct and indirect

text: solar gain

text: for space heating,

text: solar water heating

text: systems based on the

text: thermosiphon

text: , use of

text: thermal mass

text: and

text: phase-change materials

text: for slowing indoor air temperature swings,

text: solar cooker

text: s, the

text: solar chimney

text: for enhancing natural ventilation, and

text: earth sheltering

text: With a few exceptions, the farther a planet or belt is from the Sun, the larger the distance between its orbit and the orbit of the next nearer object to the Sun. For example, Venus is approximately 0.33 AU farther out from the Sun than Mercury, whereas Saturn is 4.3 AU out from Jupiter, and Neptune lies 10.5 AU out from Uranus. Attempts have been made to determine a relationship between these orbital distances (for example, the Titius–Bode law), but no such theory has been accepted. The images at the beginning of this section show the orbits of the various constituents of the Solar System on different scales.

text: With a few exceptions, the farther a planet or belt is from the Sun, the larger the distance between its orbit and the orbit of the next nearer object to the Sun. For example, Venus is approximately 0.33 AU farther out from the Sun than Mercury, whereas Saturn is 4.3 AU out from Jupiter, and Neptune lies 10.5 AU out from Uranus. Attempts have been made to determine a relationship between these orbital distances (for example, the

text: Titius–Bode law

text: ), but no such theory has been accepted. The images at the beginning of this section show the orbits of the various constituents of the Solar System on different scales.

text: The Oort cloud is believed to be a vast shell surrounding the Solar System, possibly over a light-year in radius. Across such a vast distance, the gradient of the Milky Way's gravitational field plays a far more noticeable role. Because of this gradient, galactic tides may then deform an otherwise spherical Oort cloud, stretching the cloud in the direction of the galactic centre and compressing it along the other two axes, just as the Earth distends in response to the gravity of the Moon.

text: The Oort cloud is believed to be a vast shell surrounding the Solar System, possibly over a

text: light-year

text: in radius. Across such a vast distance, the gradient of the Milky Way's gravitational field plays a far more noticeable role. Because of this gradient, galactic tides may then deform an otherwise spherical Oort cloud, stretching the cloud in the direction of the galactic centre and compressing it along the other two axes, just as the Earth distends in response to the gravity of the Moon.

text: In Exposition du système du monde, Laplace quotes Newton's assertion that "the wondrous disposition of the Sun, the planets and the comets, can only be the work of an all-powerful and intelligent Being". This, says Laplace, is a "thought in which he [Newton] would be even more confirmed, if he had known what we have shown, namely that the conditions of the arrangement of the planets and their satellites are precisely those which ensure its stability". By showing that the "remarkable" arrangement of the planets could be entirely explained by the laws of motion, Laplace had eliminated the need for the "supreme intelligence" to intervene, as Newton had "made" it do. Laplace cites with approval Leibniz's criticism of Newton's invocation of divine intervention to restore order to the Solar System: "This is to have very narrow ideas about the wisdom and the power of God." He evidently shared Leibniz's astonishment at Newton's belief "that God has made his machine so badly that unless he affects it by some extraordinary means, the watch will very soon cease to go".

text: Solar power is the conversion of sunlight into electricity, either directly using photovoltaics (PV), or indirectly using concentrated solar power (CSP). Concentrated solar power systems use lenses or mirrors and tracking systems to focus a large area of sunlight into a small beam. Photovoltaics convert light into electric current using the photoelectric effect.

text: Solar power is the conversion of

text: sunlight

text: into electricity, either directly using

text: photovoltaics

text: (PV), or indirectly using

text: concentrated solar power

text: (CSP). Concentrated solar power systems use lenses or mirrors and tracking systems to focus a large area of sunlight into a small beam. Photovoltaics convert light into electric current using the

text: photoelectric effect

text: is its orbital angular velocity. That of Jupiter contributes the bulk of the Solar System's angular momentum, 60.3%. Then comes Saturn at 24.5%, Neptune at 7.9%, and Uranus at 5.3%. The Sun forms a counterbalance to all of the planets, so it is near the barycenter when Jupiter is on one side and the other three jovian planets are diametrically opposite on the other side, but the Sun moves to 2.17 solar radii away from the barycenter when all jovian planets are in line on other side. The orbital angular momenta of the Sun and all non-jovian planets, moons, and small Solar System bodies, as well as the axial rotation momenta of all bodies, including the Sun, total only about 2%.

text: is its orbital angular velocity. That of Jupiter contributes the bulk of the Solar System's angular momentum, 60.3%. Then comes Saturn at 24.5%, Neptune at 7.9%, and Uranus at 5.3%. The

text: Sun

text: forms a counterbalance to all of the planets, so it is near the barycenter when Jupiter is on one side and the other three jovian planets are diametrically opposite on the other side, but the Sun moves to 2.17 solar radii away from the barycenter when all jovian planets are in line on other side. The orbital angular momenta of the Sun and all non-jovian planets, moons, and

text: small Solar System bodies

text: , as well as the axial rotation momenta of all bodies, including the Sun, total only about 2%.

text: Heliocentrism, or heliocentricism, is the astronomical model in which the Earth and planets revolve around the Sun at the center of the Solar System. The word comes from the Greek (ἥλιος helios "sun" and κέντρον kentron "center"). Historically, Heliocentrism was opposed to geocentrism, which placed the Earth at the center. The notion that the Earth revolves around the Sun had been proposed as early as the 3rd century BC by Aristarchus of Samos, but at least in the medieval world, Aristarchus's Heliocentrism attracted little attention—possibly because of the loss of scientific works of the Hellenistic Era.

text: astronomical

text: model in which the

text: Earth

text: and planets revolve around the

text: Sun

text: at the center of the

text: Solar System

text: . The word comes from the

text: Greek

text: ἥλιος

text: helios

text: "sun" and

text: κέντρον

text: kentron "center"). Historically, Heliocentrism was opposed to

text: geocentrism

text: , which placed the Earth at the center. The notion that the Earth revolves around the Sun had been proposed as early as the 3rd century BC by

text: Aristarchus of Samos

text: , but at least in the medieval world, Aristarchus's Heliocentrism attracted little attention—possibly because of the loss of scientific works of the Hellenistic Era.

text: The amplitude of the radial velocity oscillations means that the planet has a mass at least 5.7 times that of Jupiter in the Solar System. However, the radial velocity method only yields a minimum value on the planet's mass, depending on the orbital inclination to our line-of-sight. Therefore, the true mass of the planet may be much greater than this lower limit.

text: The amplitude of the radial velocity oscillations means that the planet has a mass at least 5.7 times that of Jupiter in the Solar System. However, the radial velocity method only yields a minimum value on the planet's mass, depending on the orbital

text: inclination

text: to our

text: line-of-sight

text: . Therefore, the

text: true mass

text: of the planet may be much greater than this lower limit.

text: The physical and orbital characteristics of the moons vary widely. The four Galileans are all over  in diameter; the largest Galilean, Ganymede, is the ninth largest object in the Solar System, after the Sun and seven of the planets, Ganymede being larger than Mercury. All other Jovian moons are less than  in diameter, with most barely exceeding . Their orbital shapes range from nearly perfectly circular to highly eccentric and inclined, and many revolve in the direction opposite to Jupiter's spin (retrograde motion). Orbital periods range from seven hours (taking less time than Jupiter does to spin around its axis), to some three thousand times more (almost three Earth years).

text: The physical and orbital characteristics of the moons vary widely. The four Galileans are all over  in diameter; the largest Galilean,

text: Ganymede

text: , is the ninth

text: largest object

text: in the

text: Solar System

text: , after the Sun and seven of the

text: planet

text: s, Ganymede being larger than

text: Mercury

text: . All other Jovian moons are less than  in diameter, with most barely exceeding . Their

text: orbital shapes

text: range from nearly perfectly circular to highly

text: eccentric

text: and

text: inclined

text: , and many revolve in the direction opposite to Jupiter's spin (

text: retrograde motion

text: Orbital period

text: s range from seven hours (taking less time than Jupiter does to spin around its axis), to some three thousand times more (almost three Earth years).

text: Earth, Moon, and Planets focuses on original research articles on formation of stars and planets, evolution of the Solar System including its origin, and the evolution of extra-solar systems including their origins. The focus also includes asteroids, comets, meteoroids, and near-Earth objects, Earth impact hazards, the Solar System-Earth relationship, and related topics. Research coverage encompasses physical and chemical properties of the above-mentioned celestial bodies, and their related chaotic behavior.

text: Earth, Moon, and Planets focuses on

text: original research

text: articles on

text: formation of stars

text: and

text: planets

text: , evolution of the

text: Solar System

text: including its origin, and the evolution of extra-solar systems including their origins. The focus also includes

text: asteroid

text: s,

text: comet

text: s,

text: meteoroid

text: s, and near-Earth objects, Earth impact hazards, the Solar System-Earth relationship, and related topics. Research coverage encompasses

text: physical

text: and

text: chemical properties

text: of the above-mentioned celestial bodies, and their related chaotic behavior.

text: Five hours after launch, Mission Control sent a command to the S-IVB booster to vent its remaining fuel through its engine bell to change the booster's trajectory. This S-IVB would then pass the Moon and enter into a solar orbit, posing no further hazard to Apollo 8. The S-IVB subsequently went into a  solar orbit with an inclination of 23.47° from the plane of the ecliptic, and an orbital period of 340.80 days. After the insertion into trans-Lunar orbit, the Saturn IVB third stage became a derelict object. It will continue to orbit the Sun for many years.

text: Five hours after launch, Mission Control sent a command to the S-IVB booster to vent its remaining fuel through its engine bell to change the booster's trajectory. This S-IVB would then pass the Moon and enter into a solar orbit, posing no further hazard to Apollo 8. The S-IVB subsequently went into a  solar orbit with an

text: inclination

text: of 23.47° from the

text: plane of the ecliptic

text: , and an orbital period of 340.80 days. After the

text: insertion

text: into trans-Lunar orbit, the

text: Saturn IVB

text: third stage

text: became a

text: derelict

text: object

text: . It will continue to

text: orbit the Sun

text: for many years.

text: The Brotherhood are most closely associated with the Guardians of the Galaxy's 'Multiverse' timeline of Earth-691. In this reality, Earth fought a war with them in the 30th century until both Earth and its solar system colonies were conquered in the year 3007, and many races were nearly all wiped out. The Guardians of the Galaxy were made up of different species, and put together by Starhawk. The human Michael Korvac, joined the Badoon and became a cyborg. The Solar System was liberated by the intervention of the Sisterhood in 3014.  Almost all information about the Sisterhood comes from the Guardians of the Galaxy's encounters with them in this timeline. Recent stories as of 2008 have depicted the Sisterhood who exist in the Earth-616 reality as being as warlike as the Brotherhood, suggesting that this origin story does not apply to the "mainstream" version of the Sisterhood.

text: The Brotherhood are most closely associated with the

text: Guardians of the Galaxy

text: 's

text: 'Multiverse' timeline

text: of

text: . In this reality, Earth fought a war with them in the 30th century until both Earth and its solar system colonies were conquered in the year 3007, and many races were nearly all wiped out. The Guardians of the Galaxy were made up of different species, and put together by

text: Starhawk

text: . The human

text: Michael Korvac

text: , joined the Badoon and became a cyborg. The Solar System was liberated by the intervention of the Sisterhood in 3014.  Almost all information about the Sisterhood comes from the Guardians of the Galaxy's encounters with them in this timeline. Recent stories

text: as of 2008

text: have depicted the Sisterhood who exist in the Earth-616 reality as being as warlike as the Brotherhood, suggesting that this origin story does not apply to the "mainstream" version of the Sisterhood.

text: WD 2359-434's mass is 0.85 ± 0.01 Solar masses, its surface gravity is 10 (2.45 · 10) cm·s, or approximately 250,000 of Earth's, corresponding to a radius 6780 km, or 1.06 of Earth's.

text: WD 2359-434's mass is 0.85 ± 0.01

text: Solar mass

text: es, its

text: surface gravity

text: is 10 (2.45 · 10)

text: cm

text: s

text: , or approximately 250,000 of

text: Earth's

text: , corresponding to a radius 6780 km, or 1.06 of

text: Earth's

text: All eight planets in the Solar System orbit the Sun in the direction that the Sun is rotating, which is counterclockwise when viewed from above the Sun's north pole. Six of the planets also rotate about their axis in this same direction. The exceptions—the planets with retrograde rotation—are Venus and Uranus. Venus's axial tilt is 177 degrees, which means it is spinning almost exactly in the opposite direction to its orbit. Uranus has an axial tilt of 97.77 degrees, so its axis of rotation is approximately parallel with the plane of the Solar System. The reason for Uranus's unusual axial tilt is not known with certainty, but the usual speculation is that during the formation of the Solar System, an Earth-sized protoplanet collided with Uranus, causing the skewed orientation.

text: All eight planets in the Solar System orbit the Sun in the direction that the Sun is rotating, which is

text: counterclockwise

text: when viewed from above the Sun's

text: north pole

text: . Six of the planets also rotate about their axis in this same direction. The exceptions—the planets with retrograde rotation—are

text: Venus

text: and

text: Uranus

text: . Venus's axial tilt is 177 degrees, which means it is spinning almost exactly in the opposite direction to its orbit. Uranus has an axial tilt of 97.77 degrees, so its axis of rotation is approximately parallel with the plane of the Solar System. The reason for Uranus's unusual axial tilt is not known with certainty, but the usual speculation is that during the formation of the Solar System, an Earth-sized

text: protoplanet

text: collided with Uranus, causing the skewed orientation.

text: No extrasolar natural satellites have yet been detected. Large planets in the Solar System like Jupiter and Saturn are known to have large moons with some of the conditions for life. Therefore, some scientists speculate that large extrasolar planets (and double planets) may have similarly large moons that are potentially habitable. A moon with sufficient mass may support an atmosphere like Titan and may also sustain liquid water on the surface.

text: No extrasolar natural satellites have yet been detected. Large planets in the Solar System like Jupiter and Saturn are known to have large moons with some of the conditions for life. Therefore, some scientists speculate that large extrasolar planets (and

text: double planet

text: s) may have similarly large moons that are potentially habitable. A moon with sufficient mass may support an atmosphere like Titan and may also sustain liquid water on the surface.

text: Many large plants are under construction. The Desert Sunlight Solar Farm is a 550 MW solar power plant under construction in Riverside County, California, that will use thin-film solar photovoltaic modules made by First Solar. The Topaz Solar Farm is a 550 MW photovoltaic power plant, being built in San Luis Obispo County, California. The Blythe Solar Power Project is a 500 MW photovoltaic station under construction in Riverside County, California. The Agua Caliente Solar Project is a 290 megawatt photovoltaic solar generating facility being built in Yuma County, Arizona. The California Valley Solar Ranch (CVSR) is a 250 megawatt (MW) solar photovoltaic power plant, which is being built by SunPower in the Carrizo Plain, northeast of California Valley. The 230 MW Antelope Valley Solar Ranch is a First Solar photovoltaic project which is under construction in the Antelope Valley area of the Western Mojave Desert, and due to be completed in 2013.

text: Many large plants are under construction. The

text: Desert Sunlight Solar Farm

text: is a 550 MW

text: solar power

text: plant under construction in

text: Riverside County, California

text: , that will use thin-film solar

text: photovoltaic

text: modules made by

text: First Solar

text: . The

text: Topaz Solar Farm

text: is a 550 MW photovoltaic power plant, being built in

text: San Luis Obispo County, California

text: . The

text: Blythe Solar Power Project

text: is a 500 MW photovoltaic station under construction in

text: Riverside County, California

text: . The

text: Agua Caliente Solar Project

text: is a 290 megawatt photovoltaic solar generating facility being built in

text: Yuma County, Arizona

text: . The

text: California Valley Solar Ranch

text: (CVSR) is a 250

text: megawatt

text: (MW)

text: solar photovoltaic

text: power plant

text: , which is being built by

text: SunPower

text: in the

text: Carrizo Plain

text: , northeast of

text: California Valley

text: . The 230 MW

text: Antelope Valley Solar Ranch

text: is a

text: First Solar

text: photovoltaic project which is under construction in the Antelope Valley area of the Western Mojave Desert, and due to be completed in 2013.

text: Below is a list of artificial objects leaving the Solar System. All of these objects are space probes and their upper stages launched by NASA. It does not include those missions that went into orbit around planets, or into orbit around the Sun because they are not leaving the Solar System.

text: Below is a list of artificial objects leaving the

text: Solar System

text: . All of these objects are space probes and their upper stages launched by

text: NASA

text: . It does not include those missions that went into orbit around planets, or into orbit around the Sun because they are not leaving the Solar System.

text: A comet and its dust allow investigation of the Solar System beyond the main planetary orbits. Comets are distinguished by their orbits; long period comets have long elliptical orbits, randomly inclined to the plane of the Solar System, and with periods greater than 200 years. Short period comets are usually inclined less than 30 degrees to the plane of the Solar System, revolve around the Sun in the same counterclockwise direction as the planets orbit, and have periods less than 200 years.

text: A comet and its dust allow investigation of the Solar System beyond the main planetary orbits. Comets are distinguished by their orbits; long period comets have long elliptical orbits, randomly inclined to the plane of the Solar System, and with periods greater than 200 years.

text: Short period comets

text: are usually inclined less than 30 degrees to the plane of the Solar System, revolve around the Sun in the same counterclockwise direction as the planets orbit, and have periods less than 200 years.

text: Earth's rotation period relative to the fixed stars, called its stellar day by the International Earth Rotation and Reference Systems Service (IERS), is  seconds of mean solar time (UT1)  Earth's rotation period relative to the precessing or moving mean vernal equinox, its sidereal day, is  seconds of mean solar time (UT1)  Thus the sidereal day is shorter than the stellar day by about 8.4 ms. The length of the mean solar day in SI seconds is available from the IERS for the periods 1623–2005 and 1962–2005.Recently (1999–2005) the average annual length of the mean solar day in excess of 86400 SI seconds has varied between 0.3 ms and 1 ms, which must be added to both the stellar and sidereal days given in mean solar time above to obtain their lengths in SI seconds.

text: Earth's rotation period relative to the

text: fixed star

text: s, called its stellar day by the

entity_name: International Earth Rotation and Reference Systems Service

text: International Earth Rotation and Reference Systems Service

text: (IERS), is  seconds of mean solar time (UT1)  Earth's rotation period relative to the

text: precessing

text: or moving mean vernal

text: equinox

text: , its

text: sidereal day

text: , is  seconds of mean solar time (UT1)  Thus the sidereal day is shorter than the stellar day by about 8.4 ms. The length of the mean solar day in SI seconds is available from the IERS for the periods 1623–2005 and 1962–2005.Recently (1999–2005) the average annual length of the mean solar day in excess of 86400 SI seconds has varied between 0.3 ms and 1 ms, which must be added to both the stellar and sidereal days given in mean solar time above to obtain their lengths in SI seconds.

text: Several solutions have been proposed to explain the calm weather on Uranus. One proposed explanation for this dearth of cloud features is that Uranus's internal heat appears markedly lower than that of the other giant planets; in astronomical terms, it has a low internal thermal flux. Why Uranus's heat flux is so low is still not understood. Neptune, which is Uranus's near twin in size and composition, radiates 2.61 times as much energy into space as it receives from the Sun. Uranus, by contrast, radiates hardly any excess heat at all. The total power radiated by Uranus in the far infrared (i.e. heat) part of the spectrum is  times the solar energy absorbed in its atmosphere. In fact, Uranus's heat flux is only  W/m², which is lower than the internal heat flux of Earth of about 0.075 W/m². The lowest temperature recorded in Uranus's tropopause is 49 K (−224 °C), making Uranus the coldest planet in the Solar System, colder than Neptune.

text: Several solutions have been proposed to explain the calm weather on Uranus. One proposed explanation for this dearth of cloud features is that Uranus's

text: internal heat

text: appears markedly lower than that of the other giant planets; in astronomical terms, it has a low internal

text: thermal flux

text: . Why Uranus's heat flux is so low is still not understood.

text: Neptune

text: , which is Uranus's near twin in size and composition, radiates 2.61 times as much energy into space as it receives from the Sun. Uranus, by contrast, radiates hardly any excess heat at all. The total power radiated by Uranus in the

text: far infrared

text: (i.e.

text: heat

text: ) part of the spectrum is  times the solar energy absorbed in its

text: atmosphere

text: . In fact, Uranus's heat flux is only  W/m², which is lower than the internal heat flux of Earth of about 0.075 W/m². The lowest temperature recorded in Uranus's tropopause is 49 K (−224 °C), making Uranus the coldest planet in the Solar System, colder than

text: Neptune

text: The oldest material found in the Solar System is dated to  (Gya). By  the primordial Earth had formed. The formation and evolution of Solar System bodies occurred along with the Sun. In theory, a solar nebula partitions a volume out of a molecular cloud by gravitational collapse, which begins to spin and flatten into a circumstellar disk, and then the planets grow out of that disk along with the Sun. A nebula contains gas, ice grains, and dust (including primordial nuclides). According to nebular theory, planetesimals formed by accretion, with the primordial Earth taking 10– (Ma) to form.

text: The oldest material found in the

text: Solar System

text: is dated to  (Gya). By  the primordial Earth had formed. The

text: formation and evolution of Solar System

text: bodies occurred along with the Sun. In theory, a

text: solar nebula

text: partitions a volume out of a

text: molecular cloud

text: by gravitational collapse, which begins to spin and flatten into a

text: circumstellar disk

text: , and then the planets grow out of that disk along with the Sun. A nebula contains gas, ice grains, and

text: dust

text: (including

text: primordial nuclide

text: s). According to

text: nebular theory

text: planetesimal

text: s formed by

text: accretion

text: , with the primordial Earth taking 10– (Ma) to form.

text: The kinematics of the stars, with large proper motion and radial velocity, suggests that the system is a member of the thick disk, the population of stars that comprise most the older members of the Milky Way's spiral arms. This is supported by the parameters of HD 53705; the surface gravity of 4.34 is somewhat low for a G0V star, indicating that it is relatively old and moving towards the end of its main sequence lifetime - which, when coupled with the solar mass, mean that estimates for the star's age are approximately 9 billion years old, approximately twice the solar age. With a peculiar velocity of 75.7 km/s, The orbit of the system about the galaxy has an eccentricity of 0.31 and brings the system up to 151 parsecs away from the galactic plane - again indicative of a thick disk system.

text: The kinematics of the stars, with large proper motion and radial velocity, suggests that the system is a member of the

text: thick disk

text: , the population of stars that comprise most the older members of the Milky Way's spiral arms. This is supported by the parameters of HD 53705; the surface gravity of 4.34 is somewhat low for a G0V star, indicating that it is relatively old and moving towards the end of its

text: main sequence

text: lifetime - which, when coupled with the solar mass, mean that estimates for the star's age are approximately 9 billion years old, approximately twice the solar age. With a

text: peculiar velocity

text: of 75.7 km/s, The orbit of the system about the galaxy has an eccentricity of 0.31 and brings the system up to 151 parsecs away from the

text: galactic plane

text: - again indicative of a thick disk system.

text: In 2010, the County of Ventura completed a solar energy system 492 kilowatts DC in size, on several County buildings. The systems were financed using a solar power purchase agreement, which required no upfront cash from the County. The systems are owned, maintained, and operated by Solar Power Partners and its investors, and were designed and constructed by Solar Power, Inc. The County pays for the solar-generated electricity generated by the system, offsetting a portion of its utility costs.

text: In 2010, the County of Ventura completed a solar energy system 492 kilowatts DC in size, on several County buildings. The systems were financed using a solar

text: power purchase agreement

text: , which required no upfront cash from the County. The systems are owned, maintained, and operated by Solar Power Partners and its investors, and were designed and constructed by Solar Power, Inc. The County pays for the solar-generated electricity generated by the system, offsetting a portion of its utility costs.

text: HD 47186 c is an extrasolar planet located approximately 123 light years away in the constellation of Canis Major, orbiting the star HD 47186. This planet has a minimum mass of 0.35061 times that of Jupiter, or 1.1712 times that of Saturn. It takes 1353.6 days or 3.7059 years to revolve around the star in about the same eccentricity as the dwarf planet Pluto. This planet orbits at about the same distance from the star as the asteroid Vesta is from the Sun.

text: HD 47186 c is an

text: extrasolar planet

text: located approximately 123

text: light year

text: s away in the

text: constellation

text: of

text: Canis Major

text: , orbiting the

text: star

text: HD 47186

text: . This planet has a

text: minimum mass

text: of 0.35061 times that of

text: Jupiter

text: , or 1.1712 times that of

text: Saturn

text: . It takes 1353.6 days or 3.7059 years to

text: revolve

text: around the star in about the same

text: eccentricity

text: as the

text: dwarf planet

text: Pluto

text: . This planet orbits at about the same distance from the star as the

text: asteroid

text: Vesta

text: is from the

text: Sun

text: He was instrumental in identifying for the first time material in meteorites that pre-dated the formation of the solar system 4.6 billion years ago. Zinner and his colleagues found minute amounts of stardust - diamond and silicon carbide - that originated outside the solar system.

text: He was instrumental in identifying for the first time material in meteorites that pre-dated the formation of the solar system 4.6 billion years ago. Zinner and his colleagues found minute amounts of

text: stardust

text: - diamond and silicon carbide - that originated outside the solar system.

text: Predicting the position of the planets in the sky was already performed in ancient times. Careful observations and geometrical calculations produced a model of the motion of the solar system known as the Ptolemaic system, which was based on an Earth-centered system. The parameters of this theory were improved during the Middle Ages by Indian and Islamic astronomers.

text: Predicting the position of the planets in the sky was already performed in ancient times. Careful observations and geometrical calculations produced a model of the motion of the

text: solar system

text: known as the

text: Ptolemaic system

text: , which was based on an

text: Earth

text: -centered system. The parameters of this theory were improved during the Middle Ages by

text: Indian

text: and

text: Islamic astronomers

text: In 1943, the Soviet astronomer Otto Schmidt proposed that the Sun, in its present form, passed through a dense interstellar cloud, emerging enveloped in a cloud of dust and gas, from which the planets eventually formed. This solved the angular momentum problem by assuming that the Sun's slow rotation was peculiar to it, and that the planets did not form at the same time as the Sun. Extensions of the model, together forming the Russian school, include Gurevich and Lebedinsky (in 1950), Safronov (in 1967,1969), Safronov and Vityazeff (in 1985), Safronov and Ruskol (in 1994), and Ruskol (in 1981), among others However, this hypothesis was severely dented by Victor Safronov who showed that the amount of time required to form the planets from such a diffuse envelope would far exceed the Solar System's determined age.

text: In 1943, the Soviet astronomer

text: Otto Schmidt

text: proposed that the Sun, in its present form, passed through a dense

text: interstellar cloud

text: , emerging enveloped in a cloud of dust and gas, from which the planets eventually formed. This solved the angular momentum problem by assuming that the Sun's slow rotation was peculiar to it, and that the planets did not form at the same time as the Sun. Extensions of the model, together forming the Russian school, include Gurevich and Lebedinsky (in 1950), Safronov (in 1967,1969), Safronov and Vityazeff (in 1985), Safronov and Ruskol (in 1994), and Ruskol (in 1981), among others However, this hypothesis was severely dented by

text: Victor Safronov

text: who showed that the amount of time required to form the planets from such a diffuse envelope would far exceed the Solar System's determined age.

text: Laplace developed the nebular hypothesis of the formation of the Solar System, first suggested by Emanuel Swedenborg and expanded by Immanuel Kant, a hypothesis that continues to dominate accounts of the origin of planetary systems. According to Laplace's description of the hypothesis, the Solar System had evolved from a globular mass of incandescent gas rotating around an axis through its centre of mass. As it cooled, this mass contracted, and successive rings broke off from its outer edge. These rings in their turn cooled, and finally condensed into the planets, while the sun represented the central core which was still left. On this view, Laplace predicted that the more distant planets would be older than those nearer the sun.

text: Laplace developed the

text: nebular hypothesis

text: of the formation of the Solar System, first suggested by

text: Emanuel Swedenborg

text: and expanded by

text: Immanuel Kant

text: , a hypothesis that continues to dominate accounts of the origin of planetary systems. According to Laplace's description of the hypothesis, the Solar System had evolved from a globular mass of

text: incandescent

text: gas

text: rotating around an axis through its

text: centre of mass

text: . As it cooled, this mass contracted, and successive rings broke off from its outer edge. These rings in their turn cooled, and finally condensed into the planets, while the sun represented the central core which was still left. On this view, Laplace predicted that the more distant planets would be older than those nearer the sun.

text: Direct insolation is the solar insolation measured at a given location on Earth with a surface element perpendicular to the Sun's rays, excluding diffuse insolation (the solar radiation that is scattered or reflected by atmospheric components in the sky). Direct insolation is equal to the solar irradiance above the atmosphere minus the atmospheric losses due to absorption and scattering. While the solar irradiance above the atmosphere varies with the Earth-Sun distance and solar cycles, the losses depend on the time of day (length of light's path through the atmosphere depending on the Solar elevation angle), cloud cover, moisture content, and other impurities.

text: Direct insolation is the solar

text: insolation

text: measured at a given location on Earth with a surface element perpendicular to the Sun's rays, excluding diffuse insolation (the solar radiation that is scattered or reflected by atmospheric components in the sky). Direct insolation is equal to the

text: solar irradiance

text: above the atmosphere minus the atmospheric losses due to

text: absorption

text: and

text: scattering

text: . While the solar irradiance above the atmosphere varies with the

text: Earth-Sun distance

text: and

text: solar cycle

text: s, the losses depend on the time of day (length of light's path through the atmosphere depending on the

text: Solar elevation angle

text: cloud cover

text: moisture

text: content, and other

text: impurities

text: 2011: Solar applications were introduced – Offers PV Modules, Solar Battery, Solar Home Lamp system, Solar Lantern, Solar Charge controller, Solar Cracker and Solar Home UPS

text: In 2013, astronomers reported, based on Kepler space mission data, that there could be as many as 40 billion Earth- and super-Earth-sized planets orbiting in the habitable zones of Sun-like stars and red dwarfs within the Milky Way. 11 billion of these estimated planets may be orbiting Sun-like stars. The nearest such planet may be 12 light-years away, according to the scientists. However, this does not give estimates for the number of extrasolar terrestrial planets, because there are planets as small as Earth that have been shown to be gas planets (see KOI-314c).

text: In 2013, astronomers reported, based on

text: Kepler space mission

text: data, that there could be as many as 40 billion Earth- and super-Earth-sized

text: planets

text: orbiting in the

text: habitable zone

text: s of

text: Sun-like stars

text: and

text: red dwarf

text: s within the

text: Milky Way

text: . 11 billion of these estimated planets may be orbiting Sun-like stars. The nearest such planet may be 12 light-years away, according to the scientists. However, this does not give estimates for the number of extrasolar terrestrial planets, because there are planets as small as Earth that have been shown to be gas planets (see

text: c).

text: The mass of L 97-12 is 0.59 ± 0.01 Solar masses, and its surface gravity is 10 cm·s, or approximately 102,000 of Earth's, corresponding to a radius of , or 139% of Earth's.

text: The mass of L 97-12 is 0.59 ± 0.01

text: Solar mass

text: es, and its

text: surface gravity

text: is 10 cm·s, or approximately 102,000 of

text: Earth's

text: , corresponding to a radius of , or 139% of

text: Earth's

text: Current spacecraft achieve a change in velocity by the expulsion of propellant, the extraction of momentum from stellar radiation pressure or the stellar wind or the utilisation of a gravity assist ("slingshot") from a planet or moon. These methods are limiting in that rocket propellants have to be accelerated as well and are eventually depleted, and the stellar wind or the gravitational fields of planets can only be utilized locally in the Solar System. In interstellar space and bereft of the above resources, different forms of propulsion are needed to propel a spacecraft, and they are referred to as advanced or exotic.

text: Current

text: spacecraft

text: achieve a change in velocity by the expulsion of

text: propellant

text: , the extraction of momentum from stellar

text: radiation pressure

text: or the

text: stellar wind

text: or the utilisation of a

text: gravity assist

text: ("slingshot") from a planet or moon. These methods are limiting in that

text: rocket propellant

text: s have to be accelerated as well and are eventually depleted, and the stellar wind or the gravitational fields of planets can only be utilized locally in the

text: Solar System

text: . In

text: interstellar space

text: and bereft of the above resources, different forms of propulsion are needed to propel a spacecraft, and they are referred to as advanced or

entity_section: Faster-than-light travel: warped spacetime and wormholes

text: exotic

text: Eta Carinae is found within the Carina Nebula, a giant star-forming region in the Carina–Sagittarius Arm of the Milky Way.  The nebula is a prominent naked eye object in the southern skies showing a complex mix of emission, reflection, and dark nebulosity.  Eta Carinae is known to be at the same distance as the Carina Nebula and its spectrum can be seen reflected off various star clouds in the nebula.  The appearance of the Carina Nebula, and particularly of the Keyhole region, has changed significantly since it was described by John Herschel over  years ago.  This is thought to be due to the reduction in ionising radiation from Eta Carinae since the Great Eruption.  Prior to the Great Eruption the Eta Carinae system contributed up to 20% of the total ionizing flux for the whole Carina Nebula, but that is now mostly blocked by the surrounding gas and dust.

text: Eta Carinae is found within the Carina Nebula, a giant

text: star-forming region

text: in the

text: Carina–Sagittarius Arm

text: of the

text: Milky Way

text: .  The nebula is a prominent naked eye object in the southern skies showing a complex mix of emission, reflection, and dark nebulosity.  Eta Carinae is known to be at the same distance as the Carina Nebula and its spectrum can be seen reflected off various star clouds in the nebula.  The appearance of the Carina Nebula, and particularly of the Keyhole region, has changed significantly since it was described by

text: John Herschel

text: over  years ago.  This is thought to be due to the reduction in ionising radiation from Eta Carinae since the Great Eruption.  Prior to the Great Eruption the Eta Carinae system contributed up to 20% of the total ionizing flux for the whole Carina Nebula, but that is now mostly blocked by the surrounding gas and dust.

text: A close solar passage can be used to increase a craft's energy.  The increased radiation pressure combines with the efficacy of being deep in the Sun's gravity well to substantially increase the energy for runs to the outer Solar System.  The optimal approach to the Sun is done by increasing the orbital eccentricity while keeping the energy level as high as practical.  The minimum approach distance is a function of sail angle, thermal properties of the sail and other structure, load effects on structure, and sail optical characteristics (reflectivity and emissivity).  A close passage can result in substantial optical degradation.  Required turn rates can increase substantially for a close passage.  A sail craft arriving at a star can use a close passage to reduce energy, which also applies to a sail craft on a return trip from the outer Solar System.

text: The solar system, showing the Sun and the planets in the order of their position from the Sun: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto. (Pluto has since been reclassified as a dwarf planet by the International Astronomical Union, but it was still considered a planet at the time the message was transmitted.)

text: The

text: solar system

text: , showing the

text: Sun

text: and the planets in the order of their position from the

text: Sun

text: Mercury

text: Venus

text: Earth

text: Mars

text: Jupiter

text: Saturn

text: Uranus

text: Neptune

text: , and

text: Pluto

text: . (Pluto has since been reclassified as a

text: dwarf planet

text: by the

text: International Astronomical Union

text: , but it was still considered a planet at the time the message was transmitted.)

text: Tidal effects are also present within a galaxy, where their gradients are likely to be steepest. This can have consequences for the formation of stars and planetary systems. Typically a star's gravity will dominate within its own system, with only the passage of other stars substantially affecting dynamics. However, at the outer reaches of the system, the star's gravity is weak and galactic tides may be significant. In the Solar System, the hypothetical Oort cloud, believed to be the source of long-period comets, lies in this transitional region.

text: Tidal effects are also present within a galaxy, where their gradients are likely to be steepest. This can have consequences for the formation of

text: star

text: s and

text: planetary system

text: s. Typically a star's gravity will dominate within its own system, with only the passage of other stars substantially affecting dynamics. However, at the outer reaches of the system, the star's gravity is weak and galactic tides may be significant. In the Solar System, the hypothetical

text: Oort cloud

text: , believed to be the source of long-period

text: comet

text: s, lies in this transitional region.

text: With the publication of his Principia roughly eighty years later (1687), Isaac Newton provided a physical theory that accounted for all three of Kepler's laws, a theory based on Newton's laws of motion and his law of universal gravitation. In particular, Newton proposed that the gravitational force between any two bodies was a central force F(r) that varied as the inverse square of the distance r between them. Arguing from his laws of motion, Newton showed that the orbit of any particle acted upon by one such force is always a conic section, specifically an ellipse if it does not go to infinity. However, this conclusion holds only when two bodies are present (the two-body problem); the motion of three bodies or more acting under their mutual gravitation (the n-body problem) remained unsolved for centuries after Newton, although solutions to a few special cases were discovered. Newton proposed that the orbits of planets about the Sun are largely elliptical because the Sun's gravitation is dominant; to first approximation, the presence of the other planets can be ignored. By analogy, the elliptical orbit of the Moon about the Earth was dominated by the Earth's gravity; to first approximation, the Sun's gravity and those of other bodies of the Solar System can be neglected. However, Newton stated that the gradual apsidal precession of the planetary and lunar orbits was due to the effects of these neglected interactions; in particular, he stated that the precession of the Moon's orbit was due to the perturbing effects of gravitational interactions with the Sun.

text: With the publication of his

text: Principia

text: roughly eighty years later (1687),

text: Isaac Newton

text: provided a physical theory that accounted for all three of Kepler's laws, a theory based on

text: Newton's laws of motion

text: and his

text: law of universal gravitation

text: . In particular, Newton proposed that the gravitational force between any two bodies was a

text: central force

text: F(r) that varied as the

text: inverse square

text: of the distance r between them. Arguing from his laws of motion, Newton showed that the orbit of any particle acted upon by one such force is always a

text: conic section

text: , specifically an ellipse if it does not go to infinity. However, this conclusion holds only when two bodies are present (the

text: two-body problem

text: ); the motion of three bodies or more acting under their mutual gravitation (the

text: n-body problem

text: ) remained unsolved for centuries after Newton, although solutions to a few

text: special cases

text: were discovered. Newton proposed that the orbits of planets about the Sun are largely elliptical because the Sun's gravitation is dominant; to

text: first approximation

text: , the presence of the other planets can be ignored. By analogy, the elliptical orbit of the

text: Moon

text: about the Earth was dominated by the Earth's gravity; to first approximation, the Sun's gravity and those of other bodies of the Solar System can be neglected. However, Newton stated that the gradual apsidal precession of the planetary and lunar orbits was due to the effects of these neglected interactions; in particular, he stated that the precession of the Moon's orbit was due to the perturbing effects of gravitational interactions with the Sun.

text: The first attempt to accurately draw the nebula (as part of a series of sketches of nebulae) was made by John Herschel in 1833, and published in 1836. He described the nebula as such:

text: The first attempt to accurately draw the nebula (as part of a series of sketches of nebulae) was made by

text: John Herschel

text: in 1833, and published in 1836. He described the nebula as such:

text: The planets in direct motion at normal speed possess the front-vedha (or opposite-vedha) aspect, at accelerated motion the left–vedha and in retrograde motion – the backward–vedha (relative to their normal direction of movement). The Sun and the two lunar nodes have fixed front–vedha and vedha to the right and the left.

text: Little is known of satellite systems beyond the Solar System, although it is inferred that natural satellites are common. J1407b is an example of an extrasolar satellite system. It is also theorised that Rogue planets ejected from their planetary system could retain a system of satellites.

text: Little is known of satellite systems beyond the Solar System, although it is inferred that natural satellites are common.

text: is an example of an extrasolar satellite system. It is also theorised that

text: Rogue planet

text: s ejected from their planetary system could retain a system of satellites.

text: Interplanetary Flight: An Introduction to Astronautics is a short, modestly technical introduction to space exploration written by Arthur C. Clarke, and published in 1950. It includes material accessible to readers with a high-school level of science and technical education, covering the elements of orbital mechanics, rocket design and performance, various applications of Earth satellites, a discussion of the more interesting and accessible destinations in the Solar System (such as they were understood at the time of writing),  and in a final chapter covering the rationale and value of human expansion off the Earth.

text: Interplanetary Flight: An Introduction to Astronautics is a short, modestly technical introduction to

text: space exploration

text: written by

text: Arthur C. Clarke

text: , and published in 1950. It includes material accessible to readers with a high-school level of science and technical education, covering the elements of

text: orbital mechanics

text: rocket

text: design and performance, various applications of Earth

text: satellite

text: s, a discussion of the more interesting and accessible destinations in the Solar System (such as they were understood at the time of writing),  and in a final chapter covering the rationale and value of human expansion off the Earth.

text: In general, in the Solar System, planetary formation is thought to have occurred via a process comparable to the long-standing nebular hypothesis: a cloud of interstellar dust and gas collapsed under the influence of gravity to form a rotating disc of material that then further condensed to form the Sun and planets. During the first few million years of the Solar System's history, an accretion process of sticky collisions caused the clumping of small particles, which gradually increased in size. Once the clumps reached sufficient mass, they could draw in other bodies through gravitational attraction and become planetesimals. This gravitational accretion led to the formation of the planets.

text: In general, in the Solar System,

text: planetary formation

text: is thought to have occurred via a process comparable to the long-standing nebular hypothesis: a cloud of interstellar dust and gas collapsed under the influence of gravity to form a rotating disc of material that then further condensed to form the Sun and planets. During the first few million years of the Solar System's history, an

text: accretion

text: process of sticky collisions caused the clumping of small particles, which gradually increased in size. Once the clumps reached sufficient mass, they could draw in other bodies through gravitational attraction and become

text: planetesimal

text: s. This gravitational accretion led to the formation of the planets.

text: In the center of the nebula is a young and massive star that emits jets of hot gas from its poles, forming the bipolar structure.  Dust surrounding the star is also ionized by the star.  The nebula spans about 2 light-years across.

text: Although it is debatable when the Solar System was truly "discovered", three 19th century observations determined its nature and place in the Universe beyond reasonable doubt. First, in 1838, Friedrich Bessel successfully measured a stellar parallax, an apparent shift in the position of a star created by Earth's motion around the Sun. This was not only the first direct, experimental proof of heliocentrism, but also revealed, for the first time, the vast distance between the Solar System and the stars. Then, in 1859, Robert Bunsen and Gustav Kirchhoff, using the newly invented spectroscope, examined the spectral signature of the Sun and discovered that it was composed of the same elements as existed on Earth, establishing for the first time a physical link between Earth and the heavens. Then, Father Angelo Secchi compared the spectral signature of the Sun with those of other stars, and found them virtually identical. The realisation that the Sun was a star led to the hypothesis that other stars could have systems of their own, though this was not to be proven for nearly 140 years.

text: Although it is debatable when the Solar System was truly "discovered", three 19th century observations determined its nature and place in the Universe beyond reasonable doubt. First, in 1838,

text: Friedrich Bessel

text: successfully measured a

text: stellar parallax

text: , an apparent shift in the position of a star created by Earth's motion around the Sun. This was not only the first direct, experimental proof of heliocentrism, but also revealed, for the first time, the vast distance between the Solar System and the stars. Then, in 1859,

text: Robert Bunsen

text: and

text: Gustav Kirchhoff

text: , using the newly invented

text: spectroscope

text: , examined the spectral signature of the Sun and discovered that it was composed of the same elements as existed on Earth, establishing for the first time a physical link between Earth and the heavens. Then, Father

text: Angelo Secchi

text: compared the spectral signature of the Sun with those of other stars, and found them virtually identical. The realisation that the Sun was a star led to the hypothesis that other stars could have systems of their own, though this was not to be proven for nearly 140 years.

text: Support for solar heating and solar power generation systems will continue with the aid of the energy subsidy in accordance with current practice. In the case of one-family houses, solar heating systems are promoted through the tax system by granting an offset for the household.

text: Support for

text: solar heating

text: and

text: solar power

text: generation systems will continue with the aid of the energy subsidy in accordance with current practice. In the case of one-family houses, solar heating systems are promoted through the tax system by granting an

text: offset

text: for the household.

text: In November 2010, American Solar Direct secured a $50 million solar system investment agreement with WGL Holdings. Under the investment agreement structure, American Solar Direct is responsible for marketing and installation of the residential solar systems.

text: In November 2010, American Solar Direct secured a $50 million solar system investment agreement with

text: WGL Holdings

text: . Under the investment agreement structure, American Solar Direct is responsible for marketing and installation of the residential solar systems.

text: During the early Solar System the five giant planets are captured into a series of mean-motion resonances due to gas-driven migration. A disk of planetesimals orbits beyond these planets, extending to 30 AU. The planetesimal disk is stirred by gravitational interactions with Pluto-massed objects exciting eccentricities and inclinations. After several hundred million years these interactions cause the resonance chain of the giant planets to be broken. The planets then begin to migrate, driven by transfers of angular momentum as they scatter planetesimals. A net inward transfer of planetesimals causes Neptune to migrate outward as most planetesimals it scatters outward return to be scattered again while some of the planetesimals it scatters inward encounter Uranus and are prevented from returning. A similar process occurs for Uranus, the extra ice giant, and Saturn resulting in their outward migration and a transfer of planetesimals inward from the outer belt to Jupiter. Jupiter, in contrast, ejects most of the planetesimals from the Solar System, and as a result migrates inward. Neptune migrates outward several AU and the orbits of the other planets diverge during this planetesimal-driven migration. The divergent migration of the planets leads to resonance crossings, exciting the eccentricities of the planets and destabilizing the planetary system. During this instability the extra ice giant enters a Saturn-crossing orbit and is scattered inward by Saturn onto a Jupiter-crossing orbit. Repeated gravitational encounters with the ice giant drive a step-wise separation of Jupiter and Saturn's orbits leading to a rapid increase of their period ratio until it is greater than 2.3. The ice giant also encounters Uranus and Neptune and crosses parts of the asteroid belt as these encounters increase the eccentricity and semi-major axis of its orbit. After 10,000–100,000 years, the ice giant is ejected from the Solar System following an encounter with Jupiter, making it a rogue planet. The remaining planets then continue to migrate at a declining rate and slowly approach their final orbits as most of the remaining planetesimal disk is removed.

text: rogue planet

text: . The remaining planets then continue to migrate at a declining rate and slowly approach their final orbits as most of the remaining planetesimal disk is removed.

text: The Galactic year is the time it takes Earth's solar system to revolve once around the galactic center. It comprises roughly 230 million Earth years.

text: The

text: Galactic year

text: is the time it takes Earth's

text: solar system

text: to revolve once around the

text: galactic center

text: . It comprises roughly 230 million Earth years.

text: Characteristics of any extrasolar satellite are likely to vary, as do the Solar System's moons. For extrasolar giant planets orbiting within their stellar habitable zone, there is a prospect a terrestrial-planet-sized satellite may be capable of supporting life.

text: Characteristics of any extrasolar satellite are likely to vary, as do the Solar System's

entity_name: List of gravitationally rounded objects of the Solar System

text: moons

text: . For extrasolar giant planets orbiting within their stellar

text: habitable zone

text: , there is a prospect a

text: terrestrial-planet

text: -sized satellite may be capable of supporting life.

text: Observationally, Einstein's general relativity (GR) is rather well established for the solar system and double pulsars. However, in GR the metric plays a double role: Measuring distances in spacetime and serving as a gravitational potential for the Christoffel connection. This dichotomy seems to be one of the main obstacles for quantizing gravity. Arthur Stanley Eddington suggested already 1924 in his book 'The Mathematical Theory of Relativity' (2nd Edition) to regard the connection as the basic field and the metric merely as a derived concept.

text: Observationally, Einstein's general relativity (GR) is rather well established for the solar system and double pulsars. However, in GR the metric plays a double role: Measuring distances in spacetime and serving as a gravitational potential for the

text: Christoffel connection

text: . This dichotomy seems to be one of the main obstacles for quantizing gravity.

text: Arthur Stanley Eddington

text: suggested already 1924 in his book 'The Mathematical Theory of Relativity' (2nd Edition) to regard the connection as the basic field and the metric merely as a derived concept.

text: The Harmonia Macrocosmica by Andreaus Cellarius.  This 1660 atlas included the first published heliocentric depiction of the solar system – “the first published maps where Earth was not the center of the solar system," Walker says. "It divides the age of faith from the age of reason."

text: The

text: Harmonia Macrocosmica

text: by

text: Andreaus Cellarius

text: .  This 1660 atlas included the first published heliocentric depiction of the solar system – “the first published maps where Earth was not the center of the solar system," Walker says. "It divides the age of faith from the age of reason."

text: Humanity's first attempt at interstellar space travel ends in disaster as the ship is destroyed near the edge of the Solar System by a transparent barrier.  They come to realize that Sol and every other Earth-like solar system are surrounded by "crystal spheres", while uninhabitable systems are not. Every attempt to break spheres around other systems from the outside fails. Humanity is thus prevented from expanding and colonizing the universe.

text: Humanity's first attempt at interstellar space travel ends in disaster as the ship is destroyed near the edge of the

text: Solar System

text: by a transparent barrier.  They come to realize that Sol and every other Earth-like solar system are surrounded by "crystal spheres", while uninhabitable systems are not. Every attempt to break spheres around other systems from the outside fails. Humanity is thus prevented from expanding and colonizing the universe.

text: The formation of giant planets is an outstanding problem in the planetary sciences. In the framework of the solar nebular model two theories for their formation exist. The first one is the disk instability model, where giant planets form in the massive protoplanetary disks as a result of its gravitational fragmentation (see above). The second possibility is the core accretion model, which is also known as the nucleated instability model. The latter scenario is thought to be the most promising one, because it can explain the formation of the giant planets in relatively low-mass disks (less than ). In this model giant planet formation is divided into two stages: a) accretion of a core of approximately  and b) accretion of gas from the protoplanetary disk. Either method may also lead to the creation of brown dwarfs. Searches as of 2011 have found that core accretion is likely the dominant formation mechanism.

text: The formation of

text: giant planet

text: s is an outstanding problem in the

text: planetary science

text: s. In the framework of the solar nebular model two theories for their formation exist. The first one is the disk instability model, where giant planets form in the massive protoplanetary disks as a result of its

text: gravitational

text: fragmentation (see above). The second possibility is the core accretion model, which is also known as the nucleated instability model. The latter scenario is thought to be the most promising one, because it can explain the formation of the giant planets in relatively low-mass disks (less than ). In this model giant planet formation is divided into two stages: a) accretion of a core of approximately  and b) accretion of gas from the protoplanetary disk. Either method may also lead to the creation of

text: brown dwarfs

text: . Searches as of 2011 have found that core accretion is likely the dominant formation mechanism.

text: At the beginning of the solar system, there were several relatively short-lived radionuclides like Al, Fe, Mn, and I present within the solar nebula. These radionuclides—possibly produced by the explosion of a supernova—are extinct today, but their decay products can be detected in very old material, such as that which constitutes meteorites. By measuring the decay products of extinct radionuclides with a mass spectrometer and using isochronplots, it is possible to determine relative ages of different events in the early history of the solar system. Dating methods based on extinct radionuclides can also be calibrated with the U-Pb method to give absolute ages. Thus both the approximate age and a high time resolution can be obtained. Generally a shorter half-life leads to a higher time resolution at the expense of timescale.

text: At the beginning of the solar system, there were several relatively short-lived radionuclides like Al, Fe, Mn, and I present within the solar nebula. These radionuclides—possibly produced by the explosion of a supernova—are extinct today, but their decay products can be detected in very old material, such as that which constitutes

text: meteorite

text: s. By measuring the decay products of extinct radionuclides with a

text: mass spectrometer

text: and using isochronplots, it is possible to determine relative ages of different events in the early history of the solar system. Dating methods based on extinct radionuclides can also be calibrated with the U-Pb method to give absolute ages. Thus both the approximate age and a high time resolution can be obtained. Generally a shorter half-life leads to a higher time resolution at the expense of timescale.

text: Along with the Sun, the gravitational influence of Jupiter has helped shape the Solar System. The orbits of most of the system's planets lie closer to Jupiter's orbital plane than the Sun's equatorial plane (Mercury is the only planet that is closer to the Sun's equator in orbital tilt), the Kirkwood gaps in the asteroid belt are mostly caused by Jupiter, and the planet may have been responsible for the Late Heavy Bombardment of the inner Solar System's history.

text: Along with the Sun, the

text: gravitational

text: influence of Jupiter has helped shape the Solar System. The orbits of most of the system's planets lie closer to Jupiter's

text: orbital plane

text: than the Sun's

text: equatorial plane

text: Mercury

text: is the only planet that is closer to the Sun's equator in orbital tilt), the

text: Kirkwood gap

text: s in the

text: asteroid belt

text: are mostly caused by Jupiter, and the planet may have been responsible for the

text: Late Heavy Bombardment

text: of the inner Solar System's history.

text: HD 45364 b is an extrasolar planet located approximately 107 light years away in the constellation of Canis Major, orbiting the 8th magnitude G-type main sequence star HD 45364. Its minimum mass is 63% that of Saturn or 19% that of Jupiter. It takes 227 days to orbit the star at a distance 68% that of Earth’s distance from the Sun. This planet was discovered by HARPS on August 8, 2008 and announced together with HD 45364 c. It is located in a 3:2 orbital resonance with HD 45364 c.

text: HD 45364 b is an

text: extrasolar planet

text: located approximately 107

text: light year

text: s away in the

text: constellation

text: of

text: Canis Major

text: , orbiting the 8th

text: magnitude

text: G-type

text: main sequence

text: star

text: HD 45364

text: . Its

text: minimum mass

text: is 63% that of

text: Saturn

text: or 19% that of

text: Jupiter

text: . It takes 227 days to orbit the star at a distance 68% that of

text: Earth

text: ’s distance from the

text: Sun

text: . This planet was discovered by

entity_name: High Accuracy Radial Velocity Planet Searcher

text: HARPS

text: on August 8, 2008 and announced together with

text: HD 45364 c

text: . It is located in a 3:2

text: orbital resonance

text: with

text: HD 45364 c

text: Observations of exo-planets have shown that arrangements of planets similar to the solar system are rare. Most planetary systems have super Earths, several times larger than Earth, close to their star, whereas the Solar System's inner region is depleted in mass with small rocky planets and none inside Mercury's orbit. Only 10% of stars have giant planets similar to Jupiter and Saturn, and those few rarely have stable nearly circular orbits distant from their star. Konstantin Batygin and colleagues argue that these features can be explained if, early in the history of the Solar System, Jupiter and Saturn drifted towards the Sun, sending showers of planetisimals towards the super Earths which sent them spiralling into the Sun, and ferrying icy building blocks into the terrestrial region of the Solar System which provided the building blocks for the rocky planets. The two giant planets then drifted out again to their present position. However, in the view of Batygin and his colleagues: "The concatenation of chance events required for this delicate choreography suggest that small, Earth-like rocky planets - and perhaps life itself - could be rare throughout the cosmos."

text: Observations of exo-planets have shown that arrangements of planets similar to the solar system are rare. Most planetary systems have super Earths, several times larger than Earth, close to their star, whereas the Solar System's inner region is depleted in mass with small rocky planets and none inside Mercury's orbit. Only 10% of stars have giant planets similar to Jupiter and Saturn, and those few rarely have stable nearly circular orbits distant from their star.

text: Konstantin Batygin

text: and colleagues argue that these features can be explained if, early in the history of the Solar System, Jupiter and Saturn drifted towards the Sun, sending showers of planetisimals towards the super Earths which sent them spiralling into the Sun, and ferrying icy building blocks into the terrestrial region of the Solar System which provided the building blocks for the rocky planets. The two giant planets then drifted out again to their present position. However, in the view of Batygin and his colleagues: "The concatenation of chance events required for this delicate choreography suggest that small, Earth-like rocky planets - and perhaps life itself - could be rare throughout the cosmos."

text: The formation of terrestrial planets differs from that of giant gas planets, also called Jovian planets. The particles that make up the terrestrial planets are made from metal and rock that condense in the inner Solar System. However, Jovian planets begin as large, icy planetesimals, which then capture hydrogen and helium gas from the solar nebula.  Differentiation between these two classes of planetesimals arise due to the frost line of the solar nebula.

text: The formation of

text: terrestrial planet

text: s differs from that of giant gas planets, also called

text: Jovian planet

text: s. The particles that make up the terrestrial planets are made from metal and rock that condense in the inner

text: Solar System

text: . However, Jovian planets begin as large, icy planetesimals, which then capture hydrogen and helium gas from the

text: solar nebula

text: .  Differentiation between these two classes of planetesimals arise due to the

text: frost line

text: of the solar nebula.

text: At the end of 2011, there were 230,000 solar power projects in the United Kingdom, with a total installed generating capacity of 750 megawatts (MW). By February 2012 the installed capacity had reached 1,000 MW. Solar power use has increased very rapidly in recent years, albeit from a small base, as a result of reductions in the cost of photovoltaic (PV) panels, and the introduction of a Feed-in tariff (FIT) subsidy in April 2010. In 2012, the government said that 4 million homes across the UK will be powered by the sun within eight years, representing 22,000 MW of installed solar power capacity by 2020.

text: megawatts

text: Solar power

text: photovoltaic

text: (PV) panels, and the introduction of a

text: Feed-in tariff

text: (FIT) subsidy in April 2010. In 2012, the government said that 4 million homes across the UK will be powered by the sun within eight years, representing 22,000 MW of installed solar power capacity by 2020.

text: By definition the inclination of a planet in the solar system is the angle between its orbital plane and the orbital plane of the Earth (the ecliptic). In other cases, for instance a moon orbiting another planet, it is convenient to define the inclination of the moon's orbit as the angle between its orbital plane and the planet's equator.

text: By definition the

text: inclination

text: of a planet in the

text: solar system

text: is the

text: angle

text: between its orbital plane and the orbital plane of the

text: Earth

text: (the

text: ecliptic

text: ). In other cases, for instance a moon orbiting another planet, it is convenient to define the inclination of the

text: moon

text: 's orbit as the angle between its orbital plane and the planet's equator.

text: In the year 2290, the human race has spread to many colonies across the solar system at various lagrangian points. The story begins on the LaGrange point opposite of the Moon, LaGrange Gamma, where the intellicomputer "Dire 51" lies. It was so intelligent that it decided to become ruler of the solar system. While scientists studied the problem with Dire 51, it developed a new type of armed armor and began attacking Earth. The battle between Earth's and Dire 51's forces seemed to be even, so the leaders of Earth decided to send in the M.U.S.H.A. team. The player takes on the role of M.U.S.H.A. pilot Terri, valedictorian from Air & Space University. A M.U.S.H.A. is a specially armed vehicle originally designed for construction work in space, but with advanced weaponry and armor. The latest design, M.U.S.H.A. Aleste, is still in the prototype stage, but is the most advanced design yet. The M.U.S.H.A. team is sent in, but the enemy destroyed four of the fighters, leaving Terri alone to continue the fight.

text: In the year 2290, the human race has spread to many colonies across the solar system at various

text: lagrangian points

text: . The story begins on the LaGrange point opposite of the Moon, LaGrange Gamma, where the intellicomputer "Dire 51" lies. It was so intelligent that it decided to become ruler of the solar system. While scientists studied the problem with Dire 51, it developed a new type of armed armor and began attacking Earth. The battle between Earth's and Dire 51's forces seemed to be even, so the leaders of Earth decided to send in the M.U.S.H.A. team. The player takes on the role of M.U.S.H.A. pilot Terri, valedictorian from Air & Space University. A M.U.S.H.A. is a specially armed vehicle originally designed for construction work in space, but with advanced weaponry and armor. The latest design, M.U.S.H.A. Aleste, is still in the prototype stage, but is the most advanced design yet. The M.U.S.H.A. team is sent in, but the enemy destroyed four of the fighters, leaving Terri alone to continue the fight.

text: South of the Eagle Nebula on the border with Sagittarius is the eclipsing binary W Serpentis, whose primary is a white giant that is interacting with the secondary. The system has been found to contain an accretion disk, and was one of the first discovered Serpentids, which are eclipsing binaries containing exceptionally strong far-ultraviolet spectral lines. It is suspected that such Serpentids are in an earlier evolutionary phase, and will evolve first into double periodic variables and then classical Algol variables. Also near the Eagle Nebula is the eclipsing Wolf–Rayet binary CV Serpentis, consisting of a Wolf–Rayet star and a hot O-type subgiant. The system is surrounded by a ring-shaped nebula, likely formed during the Wolf–Rayet phase of the primary. The eclipses of the system vary erratically, and although there are two theories as to why, neither of them is completely consistent with current understanding of stars.

text: South of the

text: Eagle Nebula

text: on the border with Sagittarius is the eclipsing binary

text: W Serpentis

text: , whose primary is a white giant that is interacting with the secondary. The system has been found to contain an

text: accretion disk

text: , and was one of the first discovered

text: Serpentid

text: s, which are eclipsing binaries containing exceptionally strong

text: far-ultraviolet

text: spectral lines. It is suspected that such Serpentids are in an earlier evolutionary phase, and will evolve first into

text: double periodic variable

text: s and then classical Algol variables. Also near the Eagle Nebula is the eclipsing

text: Wolf–Rayet

text: binary

text: CV Serpentis

text: , consisting of a Wolf–Rayet star and a hot O-type subgiant. The system is surrounded by a ring-shaped

text: nebula

text: , likely formed during the Wolf–Rayet phase of the primary. The eclipses of the system vary erratically, and although there are two theories as to why, neither of them is completely consistent with current understanding of stars.

text: A small moon called Ptero orbits over her, holding every person in Xanth there ever was or might be. The Ida on Ptero has another moon (Pyramid) where the inhabitants use a barter system that results in givers gaining size and receivers losing size. This Ida has Torus, who has Cone, who has Dumbbell and so on.  This continues into infinity, with each moon having different shapes, inhabitants, and rules. Thus, Ida is the caretaker of every conceivable and inconceivable idea. The chain of moons extends to Mundania and cycles back to Ida, herself. In the later books of the Xanth series, a visit to Ida is highly desired.

text: In the ancient Mediterranean, Hebrew, Israelite and Middle Eastern worldview, it was a common belief that shrines, important places such as cities or capitals, or other such places of prominence had a position of centrality to the world and hence equated to the child-bearing, life-giving navel of a mother. These domains constituted what could be regarded as important bond that linked the universe. Thus Nippur, the ancient city of the Mesopotamian people, was often described as the "navel". This suggested to the prominence of the location and the way it was seen to function as a place of centrality and as a link between earth and the heavens and the Universe. The Greeks thought that the conical stone Omphalos ("navel") located at Delphi was the center of the earth.

text: In the ancient Mediterranean,

text: Hebrew

text: Israelite

text: and

text: Middle Eastern

text: worldview

text: , it was a common belief that shrines, important places such as cities or capitals, or other such places of prominence had a position of centrality to the world and hence equated to the child-bearing, life-giving navel of a mother. These domains constituted what could be regarded as important

text: bond

text: that linked the universe. Thus

text: Nippur

text: , the ancient city of the

text: Mesopotamian people

text: , was often described as the "navel". This suggested to the prominence of the location and the way it was seen to function as a place of centrality and as a link between earth and the heavens and the Universe. The

text: Greeks

text: thought that the conical stone

text: Omphalos

text: ("navel") located at

text: Delphi

text: was the center of the earth.

text: Various tax credits are available for Maryland solar power system installations, as of July 2012. Property tax credits vary by county. The Maryland Energy Administration offers a $1000 grant for residential PV systems and $500 for solar hot water (solar thermal). Commercial installations are granted $60/kW (max. 100 kW) for solar panels and $20/square foot (max. 250 square feet) for solar thermal systems.

text: Planets in astrology have a meaning different from the modern astronomical understanding of what a planet is. Before the age of telescopes, the night sky was thought to consist of two very similar components: fixed stars, which remained motionless in relation to each other, and "wandering stars" ( asteres planetai), which moved relative to the fixed stars over the course of the year.

text: Planets in astrology have a meaning different from the modern

text: astronomical

text: understanding of

text: what a planet is

text: . Before the age of telescopes, the night sky was thought to consist of two very similar components: fixed stars, which remained motionless in relation to each other, and "wandering stars" ( asteres planetai), which moved relative to the fixed stars over the course of the year.

text: Of all the planets in the Solar System, the seasons of Mars are the most Earth-like, due to the similar tilts of the two planets' rotational axes. The lengths of the Martian seasons are about twice those of Earth's because Mars's greater distance from the Sun leads to the Martian year being about two Earth years long. Martian surface temperatures vary from lows of about  at the winter polar caps to highs of up to  in equatorial summer. The wide range in temperatures is due to the thin atmosphere which cannot store much solar heat, the low atmospheric pressure, and the low thermal inertia of Martian soil. The planet is 1.52 times as far from the Sun as Earth, resulting in just 43% of the amount of sunlight.

text: Of all the planets in the Solar System, the seasons of Mars are the most Earth-like, due to the similar tilts of the two planets' rotational axes. The lengths of the Martian seasons are about twice those of Earth's because Mars's greater distance from the Sun leads to the Martian year being about two Earth years long. Martian surface temperatures vary from lows of about  at the winter polar caps to highs of up to  in equatorial summer. The wide range in temperatures is due to the thin atmosphere which cannot store much solar heat, the low atmospheric pressure, and the low

text: thermal inertia

text: of Martian soil. The planet is 1.52 times as far from the Sun as Earth, resulting in just 43% of the amount of sunlight.

text: Planetesimals and larger bodies are traditionally thought to have formed via a hierarchical accretion, the formation of large objects via the collision and mergers of small objects. This process begins with the collision of dust due to Brownian motion producing larger aggregates held together by van der Waals forces. The aggregates settle toward the mid-plane of the disk and collide due to gas turbulence forming pebbles and larger objects. Further collisions and mergers eventually yield planetesimals 1–10 km in diameter held together by self-gravity. The growth of the largest planetesimals then accelerates, as gravitational focusing increases their effective cross-section, resulting in runaway accretion forming the larger asteroids. Later, gravitational scattering by the larger objects excites relative motions, causing a transition to slower oligarchic accretion that ends with the formation of planetary embryos. In the outer Solar System the planetary embryos grow large enough to accrete gas, forming the giant planets. In the inner Solar System the orbits of the planetary embryos become unstable, leading to giant impacts and the formation of the terrestrial planets.

text: Planetesimals and larger bodies are traditionally thought to have formed via a hierarchical accretion, the formation of large objects via the collision and mergers of small objects. This process begins with the collision of

text: dust

text: due to

text: Brownian motion

text: producing larger aggregates held together by

text: van der Waals force

text: s. The aggregates settle toward the mid-plane of the disk and collide due to gas turbulence forming pebbles and larger objects. Further collisions and mergers eventually yield planetesimals 1–10 km in diameter held together by self-gravity. The growth of the largest planetesimals then accelerates, as gravitational focusing increases their effective cross-section, resulting in runaway

text: accretion

text: forming the larger

text: asteroid

text: s. Later, gravitational scattering by the larger objects excites relative motions, causing a transition to slower oligarchic accretion that ends with the formation of planetary embryos. In the outer Solar System the planetary embryos grow large enough to accrete gas, forming the giant planets. In the inner Solar System the orbits of the planetary embryos become unstable, leading to giant impacts and the formation of the terrestrial planets.

text: At the time of discovery in 2001, 47 Ursae Majoris was already known to host one extrasolar planet, designated 47 Ursae Majoris b. Further measurements of the radial velocity revealed another periodicity in the data unaccounted for by the first planet. This periodicity could be explained by assuming that a second planet, designated 47 Ursae Majoris c, existed in the system with an orbital period close to 7 years. Observations of the photosphere of 47 Ursae Majoris suggested that the periodicity could not be explained by stellar activity, making the planet interpretation more likely. The planet was announced in 2002.

text: At the time of discovery in 2001, 47 Ursae Majoris was already known to host one extrasolar planet, designated

text: 47 Ursae Majoris b

text: . Further measurements of the radial velocity revealed another periodicity in the data unaccounted for by the first planet. This periodicity could be explained by assuming that a second planet, designated 47 Ursae Majoris c, existed in the system with an

text: orbital period

text: close to 7 years. Observations of the

text: photosphere

text: of 47 Ursae Majoris suggested that the periodicity could not be explained by stellar activity, making the planet interpretation more likely. The planet was announced in 2002.

text: HD 122430 b is a giant planet orbiting around the giant star HD 122430. It has a mass at least 3.71 times that of Jupiter. This planet located at a distance of 1.02 astronomical units away from its star, which is very similar to the Earth’s distance from the Sun. Despite of this, the higher luminosity of the star implies it is heated much more strongly than the Earth is. Its orbit is highly eccentric, around 68%. At periastron, the orbital distance from its parent star is 0.33 AU. At apastron, the distance is 1.71 AU. If this planet were in the Solar System, its orbit would range from just within Mercury’s orbit to just beyond Mars’s orbit.

text: HD 122430 b is a

text: giant planet

text: orbiting around the

text: giant star

text: HD 122430

text: . It has a mass at least 3.71 times that of

text: Jupiter

text: . This planet located at a distance of 1.02

text: astronomical unit

text: s away from its star, which is very similar to the Earth’s distance from the Sun. Despite of this, the higher luminosity of the star implies it is heated much more strongly than the Earth is. Its orbit is highly eccentric, around 68%. At

text: periastron

text: , the orbital distance from its parent star is 0.33 AU. At

text: apastron

text: , the distance is 1.71 AU. If this planet were in the

text: Solar System

text: , its orbit would range from just within

text: Mercury’s

text: orbit to just beyond

text: Mars

text: ’s orbit.

text: Astronomers think that comets originate in both the Oort cloud and the scattered disk. The scattered disk was created when Neptune migrated outward into the proto-Kuiper belt, which at the time was much closer to the Sun, and left in its wake a population of dynamically stable objects that could never be affected by its orbit (the Kuiper belt proper), and a population whose perihelia are close enough that Neptune can still disturb them as it travels around the Sun (the scattered disk). Because the scattered disk is dynamically active and the Kuiper belt relatively dynamically stable, the scattered disk is now seen as the most likely point of origin for periodic comets. The classic Oort cloud theory states that the Oort cloud, a sphere measuring about  in radius, formed at the same time as the solar nebula and occasionally releases comets into the inner Solar System as a giant planet or star passes nearby and causes gravitational disruptions. Examples of such comet clouds may already have been seen in the Helix Nebula.

text: Astronomers think that comets originate in both the

text: Oort cloud

text: and the

text: scattered disk

text: . The scattered disk was created when

text: Neptune

text: migrated outward into the proto-Kuiper belt, which at the time was much closer to the Sun, and left in its wake a population of dynamically stable objects that could never be affected by its orbit (the

text: Kuiper belt

text: proper), and a population whose perihelia are close enough that Neptune can still disturb them as it travels around the Sun (the scattered disk). Because the scattered disk is dynamically active and the Kuiper belt relatively dynamically stable, the scattered disk is now seen as the most likely point of origin for periodic comets. The classic Oort cloud theory states that the Oort cloud, a sphere measuring about  in radius, formed at the same time as the solar nebula and occasionally releases comets into the inner Solar System as a giant planet or star passes nearby and causes gravitational disruptions. Examples of such comet clouds may already have been seen in the

text: Helix Nebula

text: Lyra is one of three constellations (along with neighboring Cygnus and Draco) to be in the Kepler Mission's field of view, and as such it contains many more known exoplanets than most constellations. One of the first discovered by the mission is Kepler-7b, an extremely low-density exoplanet with less than half the mass of Jupiter, yet nearly 1.5 times the radius. Almost as sparse is Kepler-8b, only slightly more massive and of a similar radius. The Kepler-20 system contains five known planets; three of them are only slightly smaller than Neptune, and two while the other two are some of the first Earth-sized exoplanets to be discovered. Kepler-37 is another star with an exoplanet discovered by Kepler; the planet is the smallest known extrasolar planet known as of February 2013.

text: Lyra is one of three constellations (along with neighboring Cygnus and Draco) to be in the

text: Kepler Mission

text: 's field of view, and as such it contains many more known exoplanets than most constellations. One of the first discovered by the mission is

text: , an extremely low-density exoplanet with less than half the mass of Jupiter, yet nearly 1.5 times the radius. Almost as sparse is

text: , only slightly more massive and of a similar radius. The

text: system contains five known planets; three of them are only slightly smaller than

text: Neptune

text: , and two while the other two are some of the first

text: Earth

text: -sized exoplanets to be discovered.

text: is another star with an exoplanet discovered by Kepler; the planet is the smallest known

text: extrasolar planet

text: known as of February 2013.

text: In the case of a geocentric conjunction of two of our solar system's planets, since our solar system's planets appear to travel "along the same line" (the ecliptic), the two planets appear to an Earthbound observer as being near one another in the sky around the time of the conjunction.

text: In the case of a geocentric conjunction of two of our solar system's planets, since our solar system's planets appear to travel "along the same line" (the

text: ecliptic

text: ), the two planets appear to an Earthbound observer as being near one another in the sky around the time of the conjunction.

text: With the repairs completed, scans of the solar system reveal nine planets orbiting a yellow star. When long-range scanners are focused on the familiar-appearing third planet, Computer confirms it to be Earth.  Furthermore, the Moon is slowing down and on a course to re-enter orbit.  In private, a sceptical Koenig says that while he can accept that a chance encounter with a spatial anomaly could have shifted them across space, he cannot conceive it placing the Moon on a trajectory to re-establish its former orbit around Earth.  Bergman is philosophic; there must be a fundamental sense of order to the universe that even Man's worst blunders (such as blasting the Moon out of orbit) cannot alter.

text: With the repairs completed, scans of the solar system reveal nine planets orbiting a yellow star. When long-range scanners are focused on the familiar-appearing third planet, Computer confirms it to be Earth.  Furthermore, the Moon is slowing down and on a course to re-enter orbit.  In private, a sceptical Koenig says that while he can accept that a chance encounter with a spatial anomaly could have shifted them across space, he cannot conceive it placing the Moon on a trajectory to re-establish its former orbit around Earth.  Bergman is philosophic; there must be a fundamental sense of order to the universe that even Man's worst blunders (such as

text: blasting the Moon out of orbit

text: ) cannot alter.

text: The Nice 2 model is a model of the early evolution of the Solar System. The Nice 2 model resembles the original Nice model in that a late instability of the outer Solar System results in gravitational encounters between planets, the disruption of an outer planetesimal disk, and the migrations of the outer planets to new orbits. However, the Nice 2 model differs in its initial conditions and in the mechanism for triggering the late instability. These changes reflect the analysis of the orbital evolution of the outer Solar System during the gas disk phase and the inclusion of gravitational interactions between planetesimals in the outer disk into the model.

text: The Nice 2 model is a model of the early evolution of the

text: Solar System

text: . The Nice 2 model resembles the

text: original Nice model

text: in that a late instability of the outer Solar System results in gravitational encounters between planets, the disruption of an outer

text: planetesimal

text: disk, and the migrations of the

text: outer planets

text: to new orbits. However, the Nice 2 model differs in its initial conditions and in the mechanism for triggering the late instability. These changes reflect the analysis of the orbital evolution of the outer Solar System during the

text: gas disk

text: phase and the inclusion of gravitational interactions between planetesimals in the outer disk into the model.

text: In representations of the Solar System, it is common to draw the trajectory of Earth from the point of view of the Sun, and the trajectory of the Moon from the point of view of Earth. This could give the impression that the Moon orbits Earth in such a way that sometimes it goes backwards when viewed from the Sun's perspective. Because the orbital velocity of the Moon around Earth (1 km/s) is small compared to the orbital velocity of Earth about the Sun (30 km/s), this never happens. There are no rearward loops in the Moon's solar orbit.

text: In representations of the

text: Solar System

text: , it is common to draw the trajectory of Earth from the point of view of the Sun, and the trajectory of the Moon from the point of view of Earth. This could give the impression that the Moon orbits Earth in such a way that sometimes it goes backwards when viewed from the Sun's perspective. Because the orbital velocity of the Moon around Earth (1 km/s) is small compared to the orbital velocity of Earth about the Sun (30 km/s), this never happens. There are no rearward loops in the Moon's solar orbit.

text: In the August 2016 earnings call, Elon Musk announced that Solar City would be introducing a new product where the photovoltaic electrical energy generating devices and system would make up an entire roof surface, rather than merely be the mounting of solar panels on an existing roof, stating "It’s not a thing on a roof. It is the roof," as solar energy systems have generally been designed and installed during the early decades of terrestrial solar power. Assorted styles of solar roof tiles, made of glass, were unveiled at Universal Studios' Colonial Street backlot street set in late October 2016. Also unveiled was the Tesla Powerwall 2, a home battery product designed to store surplus power, either from the tiles or from the grid. Consumer Reports compared the estimated economy of solar roofs to traditional roofing.

text: In the August 2016 earnings call, Elon Musk announced that Solar City would be introducing a new product where the photovoltaic electrical energy generating devices and system would make up an entire roof surface, rather than merely be the mounting of solar panels on an existing roof, stating "It’s not a thing on a roof. It is the roof," as solar energy systems have generally been designed and installed during the early decades of terrestrial solar power. Assorted styles of solar roof tiles, made of glass, were unveiled at

text: Universal Studios

text: Colonial Street

text: backlot street set in late October 2016. Also unveiled was the

text: Tesla Powerwall

text: 2, a home battery product designed to store surplus power, either from the tiles or from the grid.

text: Consumer Reports

text: compared the estimated economy of solar roofs to traditional roofing.

text: In the table below, the expected values are related to the relative speed between Earth and Sun of . With respect to the speed of the solar system around the galactic center of about , or the speed of the solar system relative to the CMB rest frame of about , the null results of those experiments are even more obvious.

text: In the table below, the expected values are related to the relative speed between Earth and Sun of . With respect to the speed of the solar system around the galactic center of about , or the speed of the solar system relative to the

text: CMB rest frame

text: of about , the null results of those experiments are even more obvious.

text: Even if the discussion is limited to the solar system, the Sun is not at the geometric center of any planet's orbit, but rather approximately at one focus of the elliptical orbit. Furthermore, to the extent that a planet's mass cannot be neglected in comparison to the Sun's mass, the center of gravity of the solar system is displaced slightly away from the center of the Sun. (The masses of the planets, mostly Jupiter, amount to 0.14% of that of the Sun.)  Therefore, a hypothetical astronomer on an extrasolar planet would observe a small "wobble" in the Sun's motion.

text: Even if the discussion is limited to the

text: solar system

text: , the Sun is not at the geometric center of any planet's orbit, but rather approximately at one

text: focus

text: of the

text: elliptical

text: orbit. Furthermore, to the extent that a planet's mass cannot be neglected in comparison to the Sun's mass, the center of gravity of the solar system is displaced slightly away from the center of the Sun. (The masses of the planets, mostly

text: Jupiter

text: , amount to 0.14% of that of the Sun.)  Therefore, a hypothetical astronomer on an

text: extrasolar planet

text: would observe a small "wobble" in the Sun's motion.

text: Zinner's PhD research was in high energy physics. He subsequently studied the effects that the environment within our solar system would have on the moon and the parent bodies of meteors, using nuclear particle tracks, micrometeoid craters, and elements in the solar wind. His later research was focused on the information contained in presolar grains carried by early meteorites. These grains were formed in atmospheres and explosions of stars outside of our solar system, and they can provide information about the history of stellar nucleosynthesis and the formation of the solar system.

text: Zinner's PhD research was in

text: high energy physics

text: . He subsequently studied the effects that the environment within our solar system would have on the

text: moon

text: and the parent bodies of

text: meteor

text: s, using nuclear particle tracks,

text: micrometeoid craters

text: , and elements in the solar wind. His later research was focused on the information contained in presolar grains carried by early

text: meteorites

text: . These grains were formed in atmospheres and explosions of stars outside of our solar system, and they can provide information about the history of stellar

text: nucleosynthesis

text: and the formation of the solar system.

text: Eugene N. Parker (born June 10, 1927) is an American solar astrophysicist who received his B.S. degree in physics from Michigan State University in 1948 and Ph.D. from Caltech in 1951.  In the mid-1950s Parker developed the theory on the supersonic solar wind and predicted the Parker spiral shape of the solar magnetic field in the outer solar system.  In 1987, Parker proposed that the solar corona might be heated by myriad tiny "nanoflares", miniature brightenings resembling solar flares that would occur all over the surface of the Sun.

text: Eugene N. Parker (born June 10, 1927) is an American solar

text: astrophysicist

text: who received his B.S. degree in physics from

text: Michigan State University

text: in 1948 and Ph.D. from

text: Caltech

text: in 1951.  In the mid-1950s Parker developed the theory on the supersonic

text: solar wind

text: and predicted the

text: Parker spiral

text: shape of the solar magnetic field in the outer

text: solar system

text: .  In 1987, Parker proposed that the

text: solar corona

text: might be heated by myriad tiny "nanoflares", miniature brightenings resembling

text: solar flares

text: that would occur all over the surface of the Sun.

text: The trans-Neptunian planet hypothesis has been advanced in several forms by a number of astronomers, including Rodney Gomes and Patryk Lykawka. One scenario involves perturbations of Sedna's orbit by a hypothetical planetary-sized body in the Hills cloud. Recent simulations show that Sedna's orbital traits could be explained by perturbations by a Neptune-mass object at 2,000 AU (or less), a Jupiter-mass () at 5,000 AU, or even an Earth-mass object at 1,000 AU. Computer simulations by Patryk Lykawka have suggested that Sedna's orbit may have been caused by a body roughly the size of Earth, ejected outward by Neptune early in the Solar System's formation and currently in an elongated orbit between 80 and 170 AU from the Sun. Mike Brown's various sky surveys have not detected any Earth-sized objects out to a distance of about 100 AU. However, it is possible that such an object may have been scattered out of the Solar System after the formation of the inner Oort cloud.

text: The

text: trans-Neptunian planet

text: hypothesis has been advanced in several forms by a number of astronomers, including Rodney Gomes and

text: Patryk Lykawka

text: . One scenario involves perturbations of Sedna's orbit by a hypothetical planetary-sized body in the Hills cloud. Recent simulations show that Sedna's orbital traits could be explained by perturbations by a Neptune-mass object at 2,000 AU (or less), a Jupiter-mass () at 5,000 AU, or even an Earth-mass object at 1,000 AU. Computer simulations by Patryk Lykawka have suggested that Sedna's orbit may have been caused by a body roughly the size of Earth, ejected outward by Neptune early in the Solar System's formation and currently in an elongated orbit between 80 and 170 AU from the Sun. Mike Brown's various sky surveys have not detected any Earth-sized objects out to a distance of about 100 AU. However, it is possible that such an object may have been scattered out of the Solar System after the formation of the inner Oort cloud.

text: Insolation is a measure of solar radiation energy received on a given surface area in a given time. It is commonly expressed as average irradiance in watts per square meter (W/m2). Direct insolation is the solar irradiance measured at a given location on Earth with a surface element perpendicular to the Sun's rays, excluding diffuse insolation (the solar radiation that is scattered or reflected by atmospheric components in the sky). Direct insolation is equal to the solar constant minus the atmospheric losses due to absorption and scattering. While the solar constant varies with the Earth-Sun distance and solar cycles, the losses depend on the time of day (length of light's path through the atmosphere depending on the Solar elevation angle), cloud cover, moisture content, and other impurities.

text: Insolation

text: is a measure of

text: solar radiation

text: energy received on a given surface area in a given time. It is commonly expressed as average

text: irradiance

text: in watts per square meter (W/m2).

text: Direct insolation

text: is the solar irradiance measured at a given location on Earth with a surface element perpendicular to the Sun's rays, excluding diffuse insolation (the solar radiation that is scattered or reflected by atmospheric components in the sky). Direct insolation is equal to the

text: solar constant

text: minus the atmospheric losses due to

text: absorption

text: and

text: scattering

text: . While the solar constant varies with the

text: Earth-Sun distance

text: and

text: solar cycle

text: Solar elevation angle

text: cloud cover

text: moisture

text: content, and other

text: impurities

text: The refined nebular model was developed entirely on the basis of observations of the Solar System because it was the only one known until the mid-1990s. It was not confidently assumed to be widely applicable to other planetary systems, although scientists were anxious to test the nebular model by finding of protoplanetary discs or even planets around other stars. As of August 30, 2013, the discovery of 941 extrasolar planets has turned up many surprises, and the nebular model must be revised to account for these discovered planetary systems, or new models considered.

text: The refined nebular model was developed entirely on the basis of observations of the Solar System because it was the only one known until the mid-1990s. It was not confidently assumed to be widely applicable to other

text: planetary systems

text: , although scientists were anxious to test the nebular model by finding of protoplanetary discs or even planets around other stars. As of August 30, 2013, the discovery of 941

text: extrasolar planet

text: s has turned up many surprises, and the nebular model must be revised to account for these discovered planetary systems, or new models considered.

text: Most solar systems are currently still locked, but new solar systems are open automatically for the community every day. When a Galaxician "frees" a solar system he/she can decide if the system shall become open for the entire community, or if the system shall become a private project. In this case it is also possible to dedicate the star or solar system to someone.

text: The abundance of helium-3 is thought to be greater on the Moon than on Earth, having been embedded in the upper layer of regolith by the solar wind over billions of years, though still lower in quantity  than in the solar system's gas giants.

text: The abundance of helium-3 is thought to be greater on the Moon than on Earth, having been embedded in the upper layer of

text: regolith

text: by the

text: solar wind

text: over billions of years, though still lower in quantity  than in the

text: solar system

text: 's

text: gas giant

text: s.

text: Solar thermal systems have been constructed to produce concentrated solar power (CSP), for generating electricity. The large Sandia Lab solar power tower uses a Stirling engine heated by a solar mirror concentrator.  Another configuration is the trough system.

text: Solar thermal

text: systems have been constructed to produce

text: concentrated solar power

text: (CSP), for generating electricity. The large Sandia Lab

text: solar power tower

text: uses a

text: Stirling engine

text: heated by a solar mirror

text: concentrator

text: .  Another configuration is the trough system.

text: In 2009, Erik Verlinde argued that gravity can be explained as an entropic force. It claimed (similar to Jacobson's result) that gravity is a consequence of the "information associated with the positions of material bodies". This model combines the thermodynamic approach to gravity with Gerard 't Hooft's holographic principle. It implies that gravity is not a fundamental interaction, but an emergent phenomenon.

text: In 2009,

text: Erik Verlinde

text: argued that gravity can be explained as an entropic force. It claimed (similar to Jacobson's result) that gravity is a consequence of the "information associated with the positions of material bodies". This model combines the thermodynamic approach to gravity with

text: Gerard 't Hooft

text: 's

text: holographic principle

text: . It implies that gravity is not a

text: fundamental interaction

text: , but an

text: emergent phenomenon

text: Despite Young's success and Giants Head of Player Personnel Tom Boisture during the 1980s, that success would not continue into the 1990s. One of his first mistakes was his choice of a new head coach for the Giants after the May 1991 resignation of Bill Parcells. Young's selection of Ray Handley was not met with success as Handley won a total of 14 games in his two year stint. Young—an opponent of free agency—seemed to lose his touch following the introduction of the free agency cycle following the 1992 regular season.  He struggled to adapt to the system, along with the introduction of a salary cap in 1994. He as a result, signed several players to overvalued contracts while losing much of the Giants core talent to other franchises following free agency's inception.

text: Despite Young's success and Giants Head of Player Personnel

text: Tom Boisture

text: during the 1980s, that success would not continue into the 1990s. One of his first mistakes was his choice of a new head coach for the Giants after the May 1991 resignation of

text: Bill Parcells

text: . Young's selection of

text: Ray Handley

text: was not met with success as Handley won a total of 14 games in his two year stint. Young—an opponent of free agency—seemed to lose his touch following the introduction of the free agency cycle following the

text: 1992 regular season

text: .  He struggled to adapt to the system, along with the introduction of a salary cap in 1994. He as a result, signed several players to overvalued contracts while losing much of the Giants core talent to other franchises following free agency's inception.

text: The Sun's magnetic field leads to many effects that are collectively called solar activity. Solar flares and coronal-mass ejections tend to occur at sunspot groups. Slowly changing high-speed streams of solar wind are emitted from coronal holes at the photospheric surface. Both coronal-mass ejections and high-speed streams of solar wind carry plasma and interplanetary magnetic field outward into the Solar System. The effects of solar activity on Earth include auroras at moderate to high latitudes and the disruption of radio communications and electric power. Solar activity is thought to have played a large role in the formation and evolution of the Solar System.

text: The Sun's magnetic field leads to many effects that are collectively called

text: solar activity

text: Solar flares

text: and

text: coronal-mass ejections

text: tend to occur at sunspot groups. Slowly changing high-speed streams of

text: solar wind

text: are emitted from

text: coronal holes

text: at the photospheric surface. Both coronal-mass ejections and high-speed streams of solar wind carry plasma and

text: interplanetary magnetic field

text: outward into the Solar System. The effects of solar activity on Earth include

text: auroras

text: at moderate to high latitudes and the disruption of radio communications and

text: electric power

text: . Solar activity is thought to have played a large role in the

text: formation and evolution of the Solar System

text: One of the main roles of the kidneys in humans and other mammals is to aid in the clearance of various water-soluble molecules, including toxins, toxicants, and metabolic waste.  The body excretes some of these waste molecules via urination, and the role of the kidney is to concentrate the urine, such that waste molecules can be excreted with minimal loss of water and nutrients. The concentration of the excreted molecules determines the urine's specific gravity. In adult humans, normal specific gravity values range from 1.000 to 1.030.

text: One of the main roles of the

text: kidney

text: s in humans and other mammals is to aid in the

text: clearance

text: of various water-soluble molecules, including

text: toxins

text: toxicant

text: s, and

text: metabolic waste

text: .  The body

text: excretes

text: some of these waste molecules via

text: urination

text: , and the role of the kidney is to

text: concentrate

text: the urine, such that waste molecules can be excreted with minimal loss of water and nutrients. The concentration of the excreted molecules determines the urine's

text: specific gravity

text: . In adult humans, normal specific gravity values range from 1.000 to 1.030.

text: Barycentric Dynamical Time (TDB), a form of atomic time, is now used in the construction of the ephemerides of the planets and other solar system objects, for two main reasons. First, these ephemerides are tied to optical and radar observations of planetary motion, and the TDB time scale is fitted so that Newton's laws of motion, with corrections for general relativity, are followed. Next, the time scales based on Earth's rotation are not uniform and therefore, are not suitable for predicting the motion of bodies in our solar system.

text: Barycentric Dynamical Time

text: (TDB), a form of atomic time, is now used in the construction of the ephemerides of the

text: planet

text: s and other solar system objects, for two main reasons. First, these ephemerides are tied to optical and

text: radar

text: observations of planetary motion, and the TDB time scale is fitted so that

text: Newton's laws of motion

text: , with corrections for

text: general relativity

text: , are followed. Next, the time scales based on Earth's rotation are not uniform and therefore, are not suitable for predicting the motion of bodies in our solar system.

text: The Churchlands often invoke the fate of other, erroneous popular theories and ontologies that have arisen in the course of history. For example, Ptolemaic astronomy served to explain and roughly predict the motions of the planets for centuries, but eventually this model of the solar system was eliminated in favor of the Copernican model. The Churchlands believe the same eliminative fate awaits the "sentence-cruncher" model of the mind in which thought and behavior are the result of manipulating sentence-like states called "propositional attitudes".

text: The Churchlands often invoke the fate of other, erroneous popular theories and

text: ontologies

text: that have arisen in the course of history. For example, Ptolemaic astronomy served to explain and roughly predict the motions of the planets for centuries, but eventually this model of the solar system was eliminated in favor of the Copernican model. The Churchlands believe the same eliminative fate awaits the "sentence-cruncher" model of the mind in which thought and behavior are the result of manipulating sentence-like states called "

text: propositional attitude

text: s".

text: In Book 3 Newton also made clear his heliocentric view of the solar system, modified in a somewhat modern way, since already in the mid-1680s he recognised the "deviation of the Sun" from the centre of gravity of the solar system. For Newton, "the common centre of gravity of the Earth, the Sun and all the Planets is to be esteem'd the Centre of the World", and that this centre "either is at rest, or moves uniformly forward in a right line". Newton rejected the second alternative after adopting the position that "the centre of the system of the world is immoveable", which "is acknowledg'd by all, while some contend that the Earth, others, that the Sun is fix'd in that centre". Newton estimated the mass ratios Sun:Jupiter and Sun:Saturn, and pointed out that these put the centre of the Sun usually a little way off the common center of gravity, but only a little, the distance at most "would scarcely amount to one diameter of the Sun".

text: The outward expansion of solar ejecta into interplanetary space provides overdensities of plasma that are efficient at scattering high-energy cosmic rays entering the solar system from elsewhere in the galaxy. The frequency of solar eruptive events is modulated by the cycle, changing the degree of cosmic ray scattering in the outer solar system accordingly. As a consequence, the cosmic ray flux in the inner solar system is anticorrelated with the overall level of solar activity. This anticorrelation is clearly detected in cosmic ray flux measurements at the Earth's surface. The effect amounts to several percent variation over the solar cycle, greater than the typically 0.1% variation in total solar irradiance.

text: The outward expansion of solar ejecta into interplanetary space provides overdensities of plasma that are efficient at scattering high-energy

text: cosmic rays

text: entering the solar system from elsewhere in the galaxy. The frequency of solar eruptive events is modulated by the cycle, changing the degree of cosmic ray scattering in the outer solar system accordingly. As a consequence, the cosmic ray flux in the inner solar system is anticorrelated with the overall level of solar activity. This anticorrelation is clearly detected in cosmic ray flux measurements at the Earth's surface. The effect amounts to several percent variation over the solar cycle, greater than the typically 0.1% variation in total solar irradiance.

text: It is now possible to use computers to search for routes using the nonlinearities in the gravity of the planets and moons of the Solar System. For example, it is possible to plot an orbit from high earth orbit to Mars, passing close to one of the Earth's Trojan points. Collectively referred to as the Interplanetary Transport Network, these highly perturbative, even chaotic, orbital trajectories in principle need no fuel beyond that needed to reach the Lagrange point (in practice keeping to the trajectory requires some course corrections). The biggest problem with them is they can be exceedingly slow, taking many years. In addition launch windows can be very far apart.

text: It is now possible to use computers to search for routes using the nonlinearities in the gravity of the planets and moons of the Solar System. For example, it is possible to plot an orbit from high earth orbit to Mars, passing close to one of the Earth's

text: Trojan point

text: s. Collectively referred to as the

text: Interplanetary Transport Network

text: , these highly perturbative, even chaotic, orbital trajectories in principle need no fuel beyond that needed to reach the Lagrange point (in practice keeping to the trajectory requires some course corrections). The biggest problem with them is they can be exceedingly slow, taking many years. In addition launch windows can be very far apart.

text: The binary nature of the star at the centre of the nebula was discovered in 2014, when a study of why the nebula was not regular was conducted, resolving the previously thought single star into a double star. The two white dwarf stars forming the binary star system at the heart of the nebula orbit each other with a period of about 4 hours. The two stars have a combined mass of about 1.8 solar masses, with each star being slightly less massive than the Sun. As of 2015, they are the most massive binary double white dwarf star system known.

text: The binary nature of the star at the centre of the nebula was discovered in 2014, when a study of why the nebula was not regular was conducted, resolving the previously thought single star into a double star. The two white dwarf stars forming the binary star system at the heart of the nebula orbit each other with a period of about 4 hours. The two stars have a combined mass of about 1.8

text: solar masses

text: , with each star being slightly less massive than the Sun. As of 2015, they are the most massive binary double white dwarf star system known.

text: The objects of the inner Solar System are composed mostly of rock, the collective name for compounds with high melting points, such as silicates, iron or nickel, that remained solid under almost all conditions in the protoplanetary nebula. Jupiter and Saturn are composed mainly of gases, the astronomical term for materials with extremely low melting points and high vapour pressure, such as hydrogen, helium, and neon, which were always in the gaseous phase in the nebula. Ices, like water, methane, ammonia, hydrogen sulfide and carbon dioxide, have melting points up to a few hundred kelvins. They can be found as ices, liquids, or gases in various places in the Solar System, whereas in the nebula they were either in the solid or gaseous phase. Icy substances comprise the majority of the satellites of the giant planets, as well as most of Uranus and Neptune (the so-called "ice giants") and the numerous small objects that lie beyond Neptune's orbit. Together, gases and ices are referred to as volatiles.

text: The objects of the inner Solar System are composed mostly of rock, the collective name for compounds with high melting points, such as

text: silicates

text: , iron or nickel, that remained solid under almost all conditions in the

text: protoplanetary nebula

text: . Jupiter and Saturn are composed mainly of gases, the astronomical term for materials with extremely low melting points and high

text: vapour pressure

text: , such as

text: hydrogen

text: helium

text: , and

text: neon

text: , which were always in the gaseous phase in the nebula. Ices, like

text: water

text: methane

text: ammonia

text: hydrogen sulfide

text: and

text: carbon dioxide

text: , have melting points up to a few hundred kelvins. They can be found as ices, liquids, or gases in various places in the Solar System, whereas in the nebula they were either in the solid or gaseous phase. Icy substances comprise the majority of the satellites of the giant planets, as well as most of Uranus and Neptune (the so-called "

text: ice giant

text: s") and the numerous small objects that lie beyond Neptune's orbit. Together, gases and ices are referred to as

text: volatiles

text: After the formation of the Solar System, the orbits of all the giant planets continued to change slowly, influenced by their interaction with the large number of remaining planetesimals. After 500–600 million years (about 4 billion years ago) Jupiter and Saturn divergently crossed the 2:1 orbital resonance, in which Saturn orbited the Sun once for every two Jupiter orbits. This resonance created a gravitational push against the outer planets, causing Neptune to surge past Uranus and plough into the dense planetesimal belt. The planets scattered the majority of the small icy bodies inwards, while moving outwards themselves. These planetesimals then scattered off the next planet they encountered in a similar manner, moving the planets' orbits outwards while they moved inwards. This process continued until the planetesimals interacted with Jupiter, whose immense gravity sent them into highly elliptical orbits or even ejected them outright from the Solar System. This caused Jupiter to move slightly inward. This scattering scenario explains the trans-Neptunian populations' present low mass.

text: After the

text: formation of the Solar System

text: , the orbits of all the giant planets continued to change slowly, influenced by their interaction with the large number of remaining planetesimals. After 500–600 million years (about 4 billion years ago) Jupiter and Saturn divergently crossed the 2:1

text: orbital resonance

text: , in which Saturn orbited the Sun once for every two Jupiter orbits. This resonance created a gravitational push against the outer planets, causing Neptune to surge past Uranus and plough into the dense planetesimal belt. The planets scattered the majority of the small icy bodies inwards, while moving outwards themselves. These planetesimals then scattered off the next planet they encountered in a similar manner, moving the planets' orbits outwards while they moved inwards. This process continued until the planetesimals interacted with Jupiter, whose immense gravity sent them into highly elliptical orbits or even ejected them outright from the Solar System. This caused Jupiter to move slightly inward. This scattering scenario explains the trans-Neptunian populations' present low mass.

text: The rings of the Solar System's gas giants are aligned with their planet's equator. However, for exoplanets that orbit close to their star, tidal forces from the star would lead to the outermost rings of a planet being aligned with the planet's orbital plane around the star. A planet's innermost rings would still be aligned with the planet's equator so that if the planet has a tilted rotational axis, then the different alignments between the inner and outer rings would create a warped ring system.

text: The rings of the Solar System's gas giants are aligned with their planet's equator. However, for exoplanets that orbit close to their star, tidal forces from the star would lead to the outermost rings of a planet being aligned with the planet's orbital plane around the star. A planet's innermost rings would still be aligned with the planet's equator so that if the planet has a

text: tilted rotational axis

text: , then the different alignments between the inner and outer rings would create a warped ring system.

text: HD 73526 b is an extrasolar planet orbiting about 61 million miles (0.66 AU) away from its parent star. This planet is more massive than Jupiter in the Solar System, so is most likely a gas giant. Based on its orbit and the stellar luminosity, the planet probably receives insolation 61% that of Mercury.

text: HD 73526 b is an

text: extrasolar planet

text: orbiting about 61 million miles (0.66

text: AU

text: ) away from its parent

text: star

text: . This planet is more massive than

text: Jupiter

text: in the

text: Solar System

text: , so is most likely a

text: gas giant

text: . Based on its orbit and the

text: stellar luminosity

text: , the planet probably receives

text: insolation

text: 61% that of

text: Mercury

text: There are also many large plants under construction. The Desert Sunlight Solar Farm under construction in Riverside County, California and Topaz Solar Farm being built in San Luis Obispo County, California are both 550 MW solar parks that will use thin-film solar photovoltaic modules made by First Solar. The Blythe Solar Power Project is a 500 MW photovoltaic station under construction in Riverside County, California. The California Valley Solar Ranch (CVSR) is a 250 megawatt (MW) solar photovoltaic power plant, which is being built by SunPower in the Carrizo Plain, northeast of California Valley. The 230 MW Antelope Valley Solar Ranch is a First Solar photovoltaic project which is under construction in the Antelope Valley area of the Western Mojave Desert, and due to be completed in 2013. The Mesquite Solar project is a photovoltaic solar power plant being built in Arlington, Maricopa County, Arizona, owned by Sempra Generation. Phase 1 will have a nameplate capacity of 150 megawatts.

text: There are also many large plants under construction. The

text: Desert Sunlight Solar Farm

text: under construction in

text: Riverside County, California

text: and

text: Topaz Solar Farm

text: being built in

text: San Luis Obispo County, California

text: are both 550

text: MW

text: solar park

text: s that will use thin-film solar

text: photovoltaic

text: modules made by

text: First Solar

text: . The

text: Blythe Solar Power Project

text: Riverside County, California

text: . The

text: California Valley Solar Ranch

text: (CVSR) is a 250

text: megawatt

text: (MW)

text: solar photovoltaic

text: power plant

text: , which is being built by

text: SunPower

text: in the

text: Carrizo Plain

text: , northeast of

text: California Valley

text: . The 230 MW

text: Antelope Valley Solar Ranch

text: is a

text: First Solar

text: photovoltaic project which is under construction in the Antelope Valley area of the Western Mojave Desert, and due to be completed in 2013. The

text: Mesquite Solar project

text: is a photovoltaic solar power plant being built in

text: Arlington

text: Maricopa County

text: , Arizona, owned by

text: Sempra Generation

text: . Phase 1 will have a

text: nameplate capacity

text: of 150

text: megawatt

text: s.

text: Under Newtonian physics, a two-body system consisting of a lone object orbiting a spherical mass would trace out an ellipse with the spherical mass at a focus. The point of closest approach, called the periapsis (or, because the central body in the Solar System is the Sun, perihelion), is fixed. A number of effects in the Solar System cause the perihelia of planets to precess (rotate) around the Sun. The principal cause is the presence of other planets which perturb one another's orbit. Another (much less significant) effect is solar oblateness.

text: Under Newtonian physics, a two-body system consisting of a lone object orbiting a spherical mass would trace out an

text: ellipse

text: with the spherical mass at a

text: focus

text: . The point of closest approach, called the

text: periapsis

text: (or, because the central body in the Solar System is the Sun,

text: perihelion

text: ), is fixed. A number of effects in the Solar System cause the perihelia of planets to precess (rotate) around the Sun. The principal cause is the presence of other planets which

text: perturb

text: one another's orbit. Another (much less significant) effect is solar

text: oblateness

text: The Hopland store was opened in 1996 on the Solar Living Center grounds. Housed in a strawbale building utilizing passive solar design principles, the store is lighted and heated by an onsite solar system and by south-facing windows that capture the sun’s heat.

text: The Hopland store was opened in 1996 on the

text: Solar Living Center

text: grounds. Housed in a

text: strawbale building

text: utilizing

text: passive solar design

text: principles, the store is lighted and heated by an onsite solar system and by south-facing windows that capture the sun’s heat.

text: What this means for the planet and society remains unclear. But, in the last 20 years there has been an enormous international research effort to understand global change and the Earth system. An aim of this research is to work out if there are planetary boundaries and are we approaching them. Scientists, international governmental organizations and lobbying organizations like World Wide Fund for Nature argue that current consumption levels, particularly in developed countries, are not sustainable because there is a very real danger they will push the planet into a new state. What this new state might look like is still being debated, but sea levels are likely to rise several meters, the pH of the oceans, a measure of its acidity, is likely to drop farther than it has in 20 million years, and global atmospheric and ocean circulations may shift markedly. The major cycles – carbon, nitrogen, sulfur, phosphorus, water – and other important parameters would alter, bringing drought to some places, floods to others. Governments will no longer be able to take for granted the relative environmental stability that has allowed human society to flourish and led to rapid globalization. Most of the population of the planet will be affected. The re-insurance industry is already taking measures to protect its interests and maximize profits as turbulent times approach.

text: What this means for the planet and society remains unclear. But, in the last 20 years there has been an enormous international research effort to understand global change and the Earth system. An aim of this research is to work out if there are planetary boundaries and are we approaching them. Scientists, international governmental organizations and lobbying organizations like

text: World Wide Fund for Nature

text: argue that current consumption levels, particularly in developed countries, are not sustainable because there is a very real danger they will push the planet into a new state. What this new state might look like is still being debated, but sea levels are likely to rise several meters, the

text: pH

text: of the oceans, a measure of its acidity, is likely to drop farther than it has in 20 million years, and global atmospheric and ocean circulations may shift markedly. The major cycles –

text: carbon

text: nitrogen

text: sulfur

text: phosphorus

text: water

text: – and other important parameters would alter, bringing

text: drought

text: to some places, floods to others. Governments will no longer be able to take for granted the relative environmental stability that has allowed human society to flourish and led to rapid globalization. Most of the population of the planet will be affected. The

text: re-insurance

text: industry is already taking measures to protect its interests and maximize profits as turbulent times approach.

text: In 1972, Spacecraft Pioneer 10 took the ID card of mankind into the cosmos. A gold plated aluminum plate that indicates where humankind is located in the Universe, presents the outlook of the man and woman, and contains other information. 18 years later, a plate was found on the shore of the Malaga Island, similar to the one we sent into the cosmos but containing new marks on it. It was carried into a safe place and put under examination. Though hard to believe that we received an answer of any civilization may exist in the cosmos: however, the original illustration of Universe, of solar system, of man  were cancelled on the plate and substituted with abstract new illustrations. Made by anyone, the meaning of these changes was evident: our Universe in the reality is not the Universe, but something else. Solar system is not a solar system, but somewhat else. Man is not man, but instead some sort of other creature. But what does this statement more precisely mean? This is what the author searches in this movie, turning back to the ancient centuries to understand and explain the message.

text: Due to the low voltage of an individual solar cell (typically ca. 0.5V), several cells are wired (also see copper used in PV systems) in series in the manufacture of a "laminate". The laminate is assembled into a protective weatherproof enclosure, thus making a photovoltaic module or solar panel. Modules may then be strung together into a photovoltaic array. In 2012, solar panels available for consumers can have an efficiency of up to about 17%, while commercially available panels can go as far as 27%. It has been recorded that a group from The Fraunhofer Institute for Solar Energy Systems have created a cell that can reach 44.7% efficiency, which makes scientists' hopes of reaching the 50% efficiency threshold a lot more feasible.

text: Due to the low voltage of an individual

text: solar cell

text: (typically ca. 0.5V), several cells are wired (also see

text: copper used in PV systems

text: ) in series in the manufacture of a "laminate". The laminate is assembled into a protective weatherproof enclosure, thus making a photovoltaic module or

text: solar panel

text: . Modules may then be strung together into a photovoltaic array. In 2012, solar panels available for consumers can have an efficiency of up to about 17%, while commercially available panels can go as far as 27%. It has been recorded that a group from The Fraunhofer Institute for Solar Energy Systems have created a cell that can reach 44.7% efficiency, which makes scientists' hopes of reaching the 50% efficiency threshold a lot more feasible.

text: Solar irradiance is about 0.9 W/m brighter during solar maximum than during solar minimum.  Analysis by Camp and Tung shows that this correlates with a variation of ±0.1 °C in measured average global temperature between the peak and minimum of the 11-year solar cycle.  From this data (incorporating the Earth's albedo and the fact that the solar absorption cross-section is 1/4 of the surface area of the Earth), Tung, Zhou and Camp (2008) derive a transient sensitivity value of 0.69 to 0.97 °C/(W/m).  This would correspond to a transient climate sensitivity to carbon dioxide doubling of 2.5 to 3.6 K, similar to the range of the current scientific consensus.  However, they note that this is the transient response to a forcing with an 11-year cycle; due to lag effects, they estimate the equilibrium response to forcing would be about 1.5 times as high.

text: Solar irradiance

text: is about 0.9 W/m brighter during

text: solar maximum

text: than during

text: solar minimum

text: .  Analysis by Camp and Tung shows that this correlates with a variation of ±0.1 °C in measured average global temperature between the peak and minimum of the 11-year solar cycle.  From this data (incorporating the Earth's albedo and the fact that the solar absorption cross-section is 1/4 of the surface area of the Earth), Tung, Zhou and Camp (2008) derive a transient sensitivity value of 0.69 to 0.97 °C/(W/m).  This would correspond to a transient climate sensitivity to carbon dioxide doubling of 2.5 to 3.6 K, similar to the range of the current scientific consensus.  However, they note that this is the transient response to a forcing with an 11-year cycle; due to lag effects, they estimate the equilibrium response to forcing would be about 1.5 times as high.

text: It is divided into five sections. The first, cosmogony, starts with an analysis of the gradual creation of the star systems out of the original nebula. It continues with the Solar System, illustrating its gradual evolution and the movements of the planets. This is followed by the creation of the Earth and the geotectonic evolution of Greece’s land-mass.

text: It is divided into five sections. The first,

text: cosmogony

text: , starts with an analysis of the gradual creation of the

text: star system

text: s out of the original nebula. It continues with the

text: Solar System

text: , illustrating its gradual evolution and the movements of the planets. This is followed by the creation of the Earth and the geotectonic evolution of Greece’s land-mass.

text: Many years later, Brackett returned to the character in a trilogy of books titled The Ginger Star (1974), The Hounds of Skaith (1974) and The Reavers of Skaith (1976). These stories are science fantasies set on a distant but primitive extrasolar planet, since Stark's original Solar System venue had become unacceptable to publishers. As a result, although the character's personality and origins are retained, there are few other links between the Skaith novels and the earlier Stark novellas.

text: Many years later, Brackett returned to the character in a trilogy of books titled The Ginger Star (1974), The Hounds of Skaith (1974) and The Reavers of Skaith (1976). These stories are

text: science fantasies

text: set on a distant but primitive

text: extrasolar planet

text: , since Stark's original

text: Solar System

text: venue had become unacceptable to publishers. As a result, although the character's personality and origins are retained, there are few other links between the Skaith novels and the earlier Stark novellas.

text: The MO diagram for diboron (B-B, electron configuration 1σ1σ2σ2σ1π) requires the introduction of an atomic orbital overlap model for p orbitals. The three dumbbell-shaped p-orbitals have equal energy and are oriented mutually perpendicularly (or orthogonally). The p-orbitals oriented in the x-direction (p) can overlap end-on forming a bonding (symmetrical) σ orbital and an antibonding σ* molecular orbital. In contrast to the sigma 1s MO's, the σ 2p has some non-bonding electron density at either side of the nuclei and the σ* 2p has some electron density between the nuclei.

text: The MO diagram for

text: diboron

text: (B-B, electron configuration 1σ1σ2σ2σ1π) requires the introduction of an atomic orbital overlap model for

text: p orbital

text: s. The three

text: dumbbell

text: -shaped p-orbitals have equal energy and are oriented mutually perpendicularly (or

text: orthogonal

text: ly). The p-orbitals oriented in the x-direction (p) can overlap end-on forming a bonding (symmetrical) σ orbital and an antibonding σ* molecular orbital. In contrast to the sigma 1s MO's, the σ 2p has some non-bonding electron density at either side of the nuclei and the σ* 2p has some electron density between the nuclei.

text: The spin of the Earth starts slowing down dramatically. It is estimated Earth would stop spinning in as little as 5 years. The first effect is the isolation between the Global Positioning System satellites and ground-based atomic clocks. Then stock markets crash because of uncertainty about humanity's future. As times goes on the oceanic bulge of water at the equator moves northward and southward. The water floods Russia, Canada, Antarctica and northern Europe. The atmosphere, once shaking solar heat out over the world and shifting air, stops and whirls to the poles. The air starts to thin at the equator and people have to migrate to more northerly and southerly cities in order to keep up with denser air. There is a higher risk of solar radiation as the magnetosphere weakens because of the slowing inner core. As the Earth slows, the crust, mantle and the molten core slows down at a different speeds, causing massive friction. This creates tremendous earthquakes where the have never been earthquakes before.

text: The

text: spin of the Earth

text: starts slowing down dramatically. It is estimated Earth would stop spinning in as little as 5 years. The first effect is the isolation between the

text: Global Positioning System

text: satellite

text: s and ground-based

text: atomic clock

text: s. Then

text: stock markets crash

text: because of uncertainty about humanity's future. As times goes on the oceanic bulge of water at the

text: equator

text: moves northward and southward. The water floods Russia, Canada, Antarctica and northern Europe. The

text: atmosphere

text: , once shaking

text: solar heat

text: out over the world and shifting air, stops and whirls to the

text: poles

text: . The air starts to thin at the equator and people have to migrate to more northerly and southerly cities in order to keep up with denser air. There is a higher risk of

text: solar radiation

text: as the

text: magnetosphere

text: weakens because of the slowing

text: inner core

text: . As the Earth slows, the

text: crust

text: mantle

text: and the molten

text: core

text: slows down at a different speeds, causing massive friction. This creates tremendous earthquakes where the have never been earthquakes before.

text: The solar observatory added signs along the highway in 2011 with the names of the planets as part of a 1:250 million model of the distances between planets in the Solar System.

text: The solar observatory added signs along the highway in 2011 with the names of the planets as part of a 1:250 million model of the distances between planets in the

text: Solar System

text: The table below shows comparative gravitational accelerations at the surface of the Sun, the Earth's moon, each of the planets in the Solar System and their major moons, Ceres, Pluto, and Eris. For gaseous bodies, the "surface" is taken to mean visible surface: the cloud tops of the gas giants (Jupiter, Saturn, Uranus and Neptune), and the Sun's photosphere. The values in the table have not been de-rated for the centrifugal force effect of planet rotation (and cloud-top wind speeds for the gas giants) and therefore, generally speaking, are similar to the actual gravity that would be experienced near the poles. For reference the time it would take an object to fall 100 metres, the height of a skyscraper, is shown, along with the maximum speed reached. Air resistance is neglected.

text: The table below shows comparative gravitational accelerations at the surface of the Sun, the Earth's moon, each of the planets in the Solar System and their major moons, Ceres, Pluto, and Eris. For gaseous bodies, the "surface" is taken to mean visible surface: the cloud tops of the

text: gas giants

text: (Jupiter, Saturn, Uranus and Neptune), and the Sun's

text: photosphere

text: . The values in the table have not been de-rated for the centrifugal force effect of planet rotation (and cloud-top wind speeds for the gas giants) and therefore, generally speaking, are similar to the actual gravity that would be experienced near the poles. For reference the time it would take an object to fall 100 metres, the height of a skyscraper, is shown, along with the maximum speed reached. Air resistance is neglected.

text: According to current definitions, all planets must revolve around stars; thus, any potential "rogue planets" are excluded. In the Solar System, all the planets orbit the Sun in the same direction as the Sun rotates (counter-clockwise as seen from above the Sun's north pole). At least one extrasolar planet, WASP-17b, has been found to orbit in the opposite direction to its star's rotation. The period of one revolution of a planet's orbit is known as its sidereal period or year. A planet's year depends on its distance from its star; the farther a planet is from its star, not only the longer the distance it must travel, but also the slower its speed, because it is less affected by its star's gravity. No planet's orbit is perfectly circular, and hence the distance of each varies over the course of its year. The closest approach to its star is called its periastron (perihelion in the Solar System), whereas its farthest separation from the star is called its apastron (aphelion). As a planet approaches periastron, its speed increases as it trades gravitational potential energy for kinetic energy, just as a falling object on Earth accelerates as it falls; as the planet reaches apastron, its speed decreases, just as an object thrown upwards on Earth slows down as it reaches the apex of its trajectory.

text: According to current definitions, all planets must revolve around stars; thus, any potential "

text: rogue planet

text: s" are excluded. In the Solar System, all the planets orbit the Sun in the same direction as the Sun rotates (counter-clockwise as seen from above the Sun's north pole). At least one extrasolar planet,

text: , has been found to orbit in the opposite direction to its star's rotation. The period of one revolution of a planet's orbit is known as its

text: sidereal period

text: or year. A planet's year depends on its distance from its star; the farther a planet is from its star, not only the longer the distance it must travel, but also the slower its speed, because it is less affected by its star's

text: gravity

text: . No planet's orbit is perfectly circular, and hence the distance of each varies over the course of its year. The closest approach to its star is called its

text: periastron

text: perihelion

text: in the Solar System), whereas its farthest separation from the star is called its

text: apastron

text: aphelion

text: ). As a planet approaches periastron, its speed increases as it trades gravitational potential energy for kinetic energy, just as a falling object on Earth accelerates as it falls; as the planet reaches apastron, its speed decreases, just as an object thrown upwards on Earth slows down as it reaches the apex of its trajectory.

text: Planetesimals that have survived to the current day are valuable to science because they contain information about the formation of the Solar System. Although their exteriors are subjected to intense solar radiation that can alter their chemistry, their interiors contain pristine material essentially untouched since the planetesimal was formed. This makes each planetesimal a 'time capsule', and their composition might reveal the conditions in the Solar Nebula from which our planetary system was formed.

text: Planetesimals that have survived to the current day are valuable to science because they contain information about the

text: formation of the Solar System

text: . Although their exteriors are subjected to intense solar radiation that can alter their chemistry, their interiors contain pristine material essentially untouched since the planetesimal was formed. This makes each planetesimal a '

text: time capsule

text: ', and their composition might reveal the conditions in the

text: Solar Nebula

text: from which our planetary system was formed.

text: Set in the year AD 2225, mankind has spread from Earth to inhabit nearly all the planets or nearby moons in colonies and settlements. Space travel has grown and improved to the point of being commonplace. For the inhabitants of the solar system, an astronaut career isn't out of the question, and one of the schools set up to train future space voyagers is the Liebe Delta, a space station positioned somewhere in Earth's orbit. This growth is despite the mysterious phenomenon known as the Geduld, a sea of plasma that suddenly erupted from the sun along the Earth's orbital plane in AD 2137. Stretching from the sun to the edge of the solar system, this area of high temperatures and gravity pressures has never been explained.

text: Set in the year AD 2225, mankind has spread from Earth to inhabit nearly all the planets or nearby moons in colonies and settlements. Space travel has grown and improved to the point of being commonplace. For the inhabitants of the solar system, an astronaut career isn't out of the question, and one of the schools set up to train future space voyagers is the Liebe Delta, a space station positioned somewhere in Earth's orbit. This growth is despite the mysterious phenomenon known as the Geduld, a sea of plasma that suddenly erupted from the sun along the Earth's

text: orbital plane

text: in AD 2137. Stretching from the sun to the edge of the solar system, this area of high temperatures and gravity pressures has never been explained.

text: Robert L. Forward has commented that a solar sail could be used to modify the orbit of a satellite about the Earth. In the limit, a sail could be used to "hover" a satellite above one pole of the Earth. Spacecraft fitted with solar sails could also be placed in close orbits such that they are stationary with respect to either the Sun or the Earth, a type of satellite named by Forward a "statite". This is possible because the propulsion provided by the sail offsets the gravitational attraction of the Sun. Such an orbit could be useful for studying the properties of the Sun for long durations. Likewise a solar sail-equipped spacecraft could also remain on station nearly above the polar solar terminator of a planet such as the Earth by tilting the sail at the appropriate angle needed to counteract the planet's gravity.

text: Robert L. Forward

text: has commented that a solar sail could be used to modify the orbit of a satellite about the Earth. In the limit, a sail could be used to "hover" a satellite above one pole of the Earth. Spacecraft fitted with solar sails could also be placed in close orbits such that they are stationary with respect to either the Sun or the Earth, a type of satellite named by Forward a "

text: statite

text: ". This is possible because the propulsion provided by the sail offsets the gravitational attraction of the Sun. Such an orbit could be useful for studying the properties of the Sun for long durations. Likewise a solar sail-equipped spacecraft could also remain on station nearly above the polar

text: solar terminator

text: of a planet such as the Earth by tilting the sail at the appropriate angle needed to counteract the planet's gravity.

text: |-|The eight planets of the Solar System

text: |-|The eight planets of the

text: Solar System

text: Written by Keith Cooper, this is a 100-page journey from our planet Earth, past the other planets of the Solar System and out into deep space, to the farthest depths of the Universe. Lavishly illustrated with full-colour images from the Hubble Space Telescope, the Spitzer Space Telescope, the Mars rovers, Cassini, the Voyager spacecraft and many other space missions, this is an introduction to our Universe, with detailed information on each planet, moon, star, nebulae and galaxy presented within. The Grand Tour was released in autumn 2006.

text: In someway, it helps how planetary systems will evolve after its host star has thrown off its outer layers in a planetary nebula, eventually dying as a black dwarf. The same can go for the future of the Solar System.

text: In someway, it helps how planetary systems will evolve after its host star has thrown off its outer layers in a

text: planetary nebula

text: , eventually dying as a

text: black dwarf

text: . The same can go for the

text: future of the Solar System

text: When 55 Cancri d was discovered, it was thought to be on a fairly low eccentricity orbit similar to Jupiter in the Solar System, though the orbital elements were not well determined. As more data were collected, the best-fit solution for this planet turned out to be highly eccentric, more so than any of the planets in the Solar System. In 2008, after a complete orbit of this planet had been observed, the true orbit was revealed, indicating that as had been originally suspected, the planet's 14 year orbit was in fact near-circular, located about 5.77 AU from the star.

text: When 55 Cancri d was discovered, it was thought to be on a fairly low

text: eccentricity

text: orbit similar to Jupiter in the

text: Solar System

text: , though the

text: orbital elements

text: were not well determined. As more data were collected, the best-fit solution for this planet turned out to be highly eccentric, more so than any of the planets in the Solar System. In 2008, after a complete orbit of this planet had been observed, the true orbit was revealed, indicating that as had been originally suspected, the planet's 14 year orbit was in fact near-circular, located about 5.77

text: AU

text: from the star.

text: The Sun's gravity is sufficiently weak at such a distance that these small galactic perturbations may be enough to dislodge some planetesimals from such distant orbits, sending them towards the Sun and planets by significantly reducing their perihelia. Such a body, being composed of a rock and ice mixture, would become a comet when subjected to the increased solar radiation present in the inner Solar System.

text: The Sun's gravity is sufficiently weak at such a distance that these small galactic perturbations may be enough to dislodge some

text: planetesimals

text: from such distant orbits, sending them towards the Sun and planets by significantly reducing their

text: perihelia

text: . Such a body, being composed of a rock and ice mixture, would become a comet when subjected to the increased solar radiation present in the inner Solar System.

text: HD 23596 b is an exoplanet approximately 170 light years away in the constellation Perseus. The planet is very massive, at least 7.8 times that of Jupiter, classifying as mid-superjovian. Based on its mass, the planet would probably be a gas giant with no solid surface. The planet orbits at the average distance of 2.83 AU, taking 1565 days to complete its orbit with average velocity of 19.7 km/s. The eccentricity of the planet’s orbit is higher than all the planets in the Solar System, bringing as close as 2.00 AU to as far as 3.66 AU from the parent star.

text: HD 23596 b is an

text: exoplanet

text: approximately 170

text: light year

text: s away in the

text: constellation

text: Perseus

text: . The planet is very massive, at least 7.8 times that of

text: Jupiter

text: , classifying as mid-

text: superjovian

text: . Based on its mass, the planet would probably be a

text: gas giant

text: with no solid surface. The planet orbits at the average distance of 2.83 AU, taking 1565 days to complete its orbit with average velocity of 19.7 km/s. The eccentricity of the planet’s orbit is higher than all the planets in the

text: Solar System

text: , bringing as close as 2.00 AU to as far as 3.66 AU from the parent star.

text: The most widely accepted theory of planetary formation, known as the nebular hypothesis, maintains that 4.6 billion years ago, the Solar System formed from the gravitational collapse of a giant molecular cloud which was light years across. Several stars, including the Sun, formed within the collapsing cloud. The gas that formed the Solar System was slightly more massive than the Sun itself. Most of the mass collected in the centre, forming the Sun; the rest of the mass flattened into a protoplanetary disc, out of which the planets and other bodies in the Solar System formed.

text: The most widely accepted theory of planetary formation, known as the

text: nebular hypothesis

text: , maintains that 4.6 billion years ago, the Solar System formed from the gravitational collapse of a giant

text: molecular cloud

text: which was

text: light year

text: s across. Several

text: star

text: s, including the

text: Sun

text: , formed within the collapsing cloud. The gas that formed the Solar System was slightly more massive than the Sun itself. Most of the mass collected in the centre, forming the Sun; the rest of the mass flattened into a

text: protoplanetary disc

text: , out of which the

text: planet

text: s and other bodies in the Solar System formed.

text: Saturn is a gas giant because it is predominantly composed of hydrogen and helium ('gas'). It lacks a definite surface, though it may have a solid core. Saturn's rotation causes it to have the shape of an oblate spheroid; that is, it is flattened at the poles and bulges at its equator. Its equatorial and polar radii differ by almost 10%: 60,268 km versus 54,364 km, respectively. Jupiter, Uranus, and Neptune, the other giant planets in the Solar System, are also oblate but to a lesser extent. Saturn is the only planet of the Solar System that is less dense than water—about 30% less. Although Saturn's core is considerably denser than water, the average specific density of the planet is 0.69 g/cm due to the atmosphere. Jupiter has 318 times the Earth's mass, while Saturn is 95 times the mass of the Earth. Together, Jupiter and Saturn hold 92% of the total planetary mass in the Solar System.

text: Saturn is a

text: gas giant

text: because it is predominantly composed of hydrogen and helium ('gas'). It lacks a definite surface, though it may have a solid core. Saturn's rotation causes it to have the shape of an

text: oblate spheroid

text: ; that is, it is flattened at the poles and bulges at its equator. Its equatorial and polar radii differ by almost 10%: 60,268 km versus 54,364 km, respectively. Jupiter,

text: Uranus

text: , and

text: Neptune

text: , the other giant planets in the Solar System, are also oblate but to a lesser extent. Saturn is the only planet of the Solar System that is less dense than water—about 30% less. Although Saturn's

text: core

text: is considerably denser than water, the average

text: specific density

text: of the planet is 0.69 g/cm due to the atmosphere. Jupiter has 318 times the Earth's mass, while Saturn is 95 times the mass of the

text: Earth

text: . Together, Jupiter and Saturn hold 92% of the total planetary mass in the Solar System.

text: It represents the Sun in the Sweden Solar System, the world's largest scale model of the Solar System.

text: It represents the

text: Sun

text: in the

text: Sweden Solar System

text: , the world's largest scale model of the Solar System.

text: In 1938, Weizsäcker developed a theory on the formation of the Solar System, based on considerations regarding the unequal share of lighter and heavier elements in the Sun and the Solar System's terrestrial planets. His views were later generally acknowledged and refined by a large number of other physicists and astronomers. According to the theory, the Sun and its planets evolved from a gas cloud made up of 99% hydrogen and helium, and 1% of heavier elements. Some 10% of the cloud remained around the Sun as an extensive atmosphere during an initial phase, and the 1% of heavier elements within this 10% of the total mass of the cloud would tally with the fraction of roughly 1% that the planets contribute to the mass of the Solar System today.

text: In 1938, Weizsäcker developed a theory on the

text: formation of the Solar System

text: , based on considerations regarding the unequal share of lighter and heavier

text: element

text: s in the

text: Sun

text: and the

text: Solar System

text: 's

text: terrestrial planet

text: s. His views were later generally acknowledged and refined by a large number of other physicists and astronomers. According to the theory, the Sun and its

text: planet

text: s evolved from a gas cloud made up of 99%

text: hydrogen

text: and

text: helium

text: , and 1% of heavier elements. Some 10% of the cloud remained around the Sun as an extensive

text: atmosphere

text: during an initial phase, and the 1% of heavier elements within this 10% of the total mass of the cloud would tally with the fraction of roughly 1% that the planets contribute to the mass of the Solar System today.

text: An orrery is a planetarium, a working model of the solar system. The "face" of the model looks down from the ceiling of what used to be his living room, with most of the mechanical works in the space above the ceiling. It is driven by a pendulum clock, which has 9 weights or ponds. The planets move around the model in real time, automatically. (A slight "re-setting" must be done by hand every four years to compensate for the February 29th of a leap year.) The planetarium includes a display for the current time and date. The plank that has the year numbers written on it has to be replaced every 22 years.

text: An

text: orrery

text: is a planetarium, a working model of the

text: solar system

text: . The "face" of the model looks down from the ceiling of what used to be his living room, with most of the mechanical works in the space above the ceiling. It is driven by a

text: pendulum clock

text: , which has 9 weights or ponds. The planets move around the model in real time, automatically. (A slight "re-setting" must be done by hand every four years to compensate for the February 29th of a

text: leap year

text: .) The planetarium includes a display for the current time and date. The plank that has the year numbers written on it has to be replaced every 22 years.

text: A handful of light years from Earth, Kulthea is the seventh planet (of 13) in its solar system, with a solar orbit of 350 days.

text: A handful of light years from Earth, Kulthea is the seventh planet (of 13) in its

text: solar system

text: , with a solar

text: orbit

text: of 350 days.

text: An interstellar comet is a comet (or exocomet) located in interstellar space, and not gravitationally bound to a star. Besides known comets within the Solar System, or known extrasolar comets, no interstellar comet, not gravitationally bound to a star, has been conclusively identified. Nonetheless, such comets are conjectured to exist: gravitational scattering by planets and passing stars has ejected many Oort cloud comets from the Solar System, and the likelihood of similar processes in extrasolar planetary systems suggests the existence of a large population of unbound cometary bodies. At present, an interstellar comet can only be detected if it passes through the Solar System, and could be distinguished from an Oort cloud comet by its strongly hyperbolic trajectory (indicating that it is not gravitationally bound to the Sun). Comets with weakly hyperbolic trajectories have been observed, but the trajectories of these comets are consistent with having been knocked loose from the Oort cloud and do not indicate an origin in interstellar space. The most eccentric known comet, C/1980 E1, only has an eccentricity of 1.057, far less eccentric than an interstellar comet would be expected to be.

text: An interstellar comet is a

text: comet

text: (or

text: exocomet

text: ) located in

text: interstellar space

text: , and not

text: gravitationally bound

text: to a

text: star

text: . Besides known comets within the

text: Solar System

text: , or known

text: extrasolar comet

text: s, no interstellar comet, not gravitationally bound to a star, has been conclusively identified. Nonetheless, such comets are conjectured to exist: gravitational scattering by planets and passing stars has ejected many

text: Oort cloud

text: comets from the Solar System, and the likelihood of similar processes in extrasolar planetary systems suggests the existence of a large population of unbound cometary bodies. At present, an interstellar comet can only be detected if it passes through the Solar System, and could be distinguished from an

text: Oort cloud

text: comet by its strongly hyperbolic trajectory (indicating that it is not gravitationally bound to the Sun). Comets with weakly hyperbolic trajectories have been observed, but the trajectories of these comets are consistent with having been knocked loose from the Oort cloud and do not indicate an origin in interstellar space. The most eccentric known comet,

text: C/1980 E1

text: , only has an eccentricity of 1.057, far less eccentric than an interstellar comet would be expected to be.

text: The two inferior planets, Mercury and Venus, which have orbits that are smaller than the Earth's, exhibit the full range of phases as does the Moon, when seen through a telescope. Their phases are "full" when they are at superior conjunction, on the far side of the Sun as seen from the Earth. (It is possible to see them at these times, since their orbits are not exactly in the plane of Earth's orbit, so they usually appear to pass slightly above or below the Sun in the sky. Seeing them from the Earth's surface is difficult, because of sunlight scattered in Earth's atmosphere, but observers in space can see them easily if direct sunlight is blocked from reaching the observer's eyes.) The planets' phases are "new" when they are at inferior conjunction, passing more or less between the Sun and the Earth. (Sometimes they appear to cross the solar disk, which is called a transit of the planet.) At intermediate points on their orbits, these planets exhibit the full range of crescent and gibbous phases.

text: The two

text: inferior planet

text: s,

text: Mercury

text: and

text: Venus

text: , which have orbits that are smaller than the Earth's, exhibit the full range of phases as does the Moon, when seen through a telescope. Their phases are "full" when they are at

text: superior conjunction

text: , on the far side of the Sun as seen from the Earth. (It is possible to see them at these times, since their orbits are not exactly in the plane of Earth's orbit, so they usually appear to pass slightly above or below the Sun in the sky. Seeing them from the Earth's surface is difficult, because of sunlight scattered in Earth's atmosphere, but observers in space can see them easily if direct sunlight is blocked from reaching the observer's eyes.) The planets' phases are "new" when they are at inferior conjunction, passing more or less between the Sun and the Earth. (Sometimes they appear to cross the solar disk, which is called a

text: transit

text: of the planet.) At intermediate points on their orbits, these planets exhibit the full range of crescent and gibbous phases.

text: NGC 7635, also called the Bubble Nebula, Sharpless 162, or Caldwell 11, is a H II region emission nebula in the constellation Cassiopeia. It lies close to the direction of the open cluster Messier 52. The "bubble" is created by the stellar wind from a massive hot, 8.7 magnitude young central star, the 15 ±  SAO 20575 (BD+60 2522). The nebula is near a giant molecular cloud which contains the expansion of the bubble nebula while itself being excited by the hot central star, causing it to glow. It was discovered in 1787 by William Herschel. The star SAO 20575 or BD+602522 is thought to have a mass of 10-40 Solar masses.

text: NGC 7635, also called the Bubble Nebula, Sharpless 162, or Caldwell 11, is a

text: H II region

text: emission nebula in the constellation

text: Cassiopeia

text: . It lies close to the direction of the

text: open cluster

text: Messier 52

text: . The "bubble" is created by the

text: stellar wind

text: from a massive hot, 8.7

text: magnitude

text: young central

text: star

text: , the 15 ±  SAO 20575 (BD+60 2522). The nebula is near a giant

text: molecular cloud

text: which contains the expansion of the bubble nebula while itself being excited by the hot central star, causing it to glow. It was discovered in 1787 by

text: William Herschel

text: . The star

text: SAO 20575

text: or

text: is thought to have a mass of 10-40

text: Solar masses

text: Since there is believed to be no "center" or "edge" of the Universe, there is no particular reference point with which to plot the overall location of the Earth in the universe. Because the observable universe is defined as that region of the Universe visible to terrestrial observers, Earth is, by definition, the center of the observable universe. Reference can be made to the Earth's position with respect to specific structures, which exist at various scales. It is still undetermined whether the Universe is infinite. There have been numerous hypotheses that our universe may be only one such example within a higher multiverse; however, no direct evidence of any sort of multiverse has ever been observed, and some have argued that the hypothesis is not falsifiable.

text: Since there is believed to be no "center" or "edge" of the Universe, there is no particular reference point with which to plot the overall location of the Earth in the universe. Because the

text: observable universe

text: is defined as that region of the Universe visible to terrestrial observers, Earth is, by definition, the center of the observable universe. Reference can be made to the Earth's position with respect to specific structures, which exist at various scales. It is still undetermined whether the Universe is

text: infinite

text: . There have been numerous hypotheses that our universe may be only one such example within a higher

text: multiverse

text: ; however, no direct evidence of any sort of multiverse has ever been observed, and some have argued that the hypothesis is not

text: falsifiable

text: The study proposed a possible surface base on Callisto that would produce rocket propellant for further exploration of the Solar System. Advantages of a base on Callisto include low radiation (due to its distance from Jupiter) and geological stability. Such a base could facilitate remote exploration of Europa, or be an ideal location for a Jovian system waystation servicing spacecraft heading farther into the outer Solar System, using a gravity assist from a close flyby of Jupiter after departing Callisto.

text: The study proposed a possible surface base on Callisto that would produce

text: rocket propellant

text: for further exploration of the Solar System. Advantages of a base on Callisto include low radiation (due to its distance from Jupiter) and geological stability. Such a base could facilitate remote exploration of

text: Europa

text: , or be an ideal location for a Jovian system waystation servicing spacecraft heading farther into the outer Solar System, using a

text: gravity assist

text: from a close flyby of Jupiter after departing Callisto.

text: With the discovery during the latter half of the 20th century of more objects within the Solar System and large objects around other stars, disputes arose over what should constitute a planet. There were particular disagreements over whether an object should be considered a planet if it was part of a distinct population such as a belt, or if it was large enough to generate energy by the thermonuclear fusion of deuterium.

text: With the discovery during the latter half of the 20th century of more objects within the Solar System and large objects around other stars, disputes arose over what should constitute a planet. There were particular disagreements over whether an object should be considered a planet if it was part of a distinct population such as a

text: belt

text: , or if it was large enough to generate energy by the

text: thermonuclear fusion

text: of

text: deuterium

text: Their search was undertaken because hitherto there was no known radioactive isotope of Al that might be useful as a tracer. Theoretical considerations suggested that a state of Al should exist. The life time of Al (  ) was not then known (10-10 yr.) The search for Al took place over many years, long after the discovery of extinct  I (  by Reynolds (1960, Phys. Rev. letters v 4, p 8) which showed that contribution from stellar sources formed ~10 years before the Sun had contributed to the solar system mix. The asteroidal materials that provide meteorite samples were long known to be from the early solar system. Analysis of Ne in some meteorites showed that they had a widely variable isotopic composition. Then Black found that essentially pure Ne was one of the Ne components present which pointed to an extra solar origin of dust from red giant stars. Eberhardt  found that the material obtained by essentially chemically destroying the meteorite matrix resulted in a colloidal sludge residue which contained almost pure Ne. This supported the idea that presolar dust grains were present in the sludge from the meteorite.

text: Their search was undertaken because hitherto there was no known radioactive isotope of Al that might be useful as a tracer. Theoretical considerations suggested that a state of Al should exist. The life time of Al (  ) was not then known (10-10 yr.) The search for Al took place over many years, long after the discovery of extinct  I (  by Reynolds (1960, Phys. Rev. letters v 4, p 8) which showed that contribution from stellar sources formed ~10 years before the Sun had contributed to the solar system mix. The asteroidal materials that provide meteorite samples were long known to be from the early solar system. Analysis of Ne in some meteorites showed that they had a widely variable isotopic composition. Then Black found that essentially pure Ne was one of the Ne components present which pointed to an extra solar origin of dust from

text: red giant star

text: s. Eberhardt  found that the material obtained by essentially chemically destroying the meteorite matrix resulted in a colloidal sludge residue which contained almost pure Ne. This supported the idea that presolar dust grains were present in the sludge from the meteorite.

text: HD 111232 b is an extrasolar planet that orbits almost 2 AU with a mass of at least 6.8 times that of Jupiter. This planet was discovered in the La Silla Observatory by Michel Mayor using the CORALIE spectrograph on 30 June 2003, along with six other planets, including HD 41004 Ab, HD 65216 b, HD 169830 c, HD 216770 b, HD 10647 b, and HD 142415 b.

text: HD 111232 b is an

text: extrasolar planet

text: that orbits almost 2

text: AU

text: with a

text: mass

text: of at least 6.8 times that of

text: Jupiter

text: . This planet was discovered in the

text: La Silla Observatory

text: by

text: Michel Mayor

text: using the

entity_name: Swiss 1.2-metre Leonhard Euler Telescope

text: CORALIE spectrograph

text: on 30 June 2003, along with six other planets, including

text: HD 41004 Ab

text: HD 65216 b

text: HD 169830 c

text: HD 216770 b

text: HD 10647 b

text: , and

text: HD 142415 b

text: forms a binary system with another object with the IAU provisional designation : the first trans-Neptunian binary to be discovered since Pluto, and one of the most symmetrical binaries known in the Solar System. The two bodies are very close in size, with a diameter ratio of 1.2 and a mass ratio of 1.74, assuming similar surfaces and densities. Their orbital period is approximately 570 days, and they orbit at a distance of approximately 4000 km (closest approach) to 40,000 km, with a semi-major axis of about 22,000 km. Their diameters are likely to be in the 100–150 km range, assuming a density of 1–2 g/cm³. Their combined mass is 1/6000th that of the Pluto–Charon system.

text: forms a

text: binary system

text: with another object with the

text: IAU

text: provisional designation

text: : the first

text: trans-Neptunian

text: binary to be discovered since

text: Pluto

text: , and one of the most symmetrical binaries known in the Solar System. The two bodies are very close in size, with a diameter ratio of 1.2 and a mass ratio of 1.74, assuming similar surfaces and densities. Their orbital period is approximately 570 days, and they orbit at a distance of approximately 4000 km (closest approach) to 40,000 km, with a

text: semi-major axis

text: of about 22,000 km. Their diameters are likely to be in the 100–150 km range, assuming a density of 1–2 g/cm³. Their combined mass is 1/6000th that of the Pluto–Charon system.

text: Plutonium-244 is one of several extinct radionuclides that preceded the formation of the solar system. Its half-life of 80 million years ensured its circulation across the solar system before its extinction and indeed, Pu has not yet been found in matter other than meteorites. Radionuclides, such as Pu, undergo decay to produce fissiogenic - arising from fission -  xenon isotopes that can then be used to time the events of the early solar system. In fact, by analyzing data from Earth’s mantle that indicate that about 30% of the existing fissiogenic xenon is attributable to Pu decay, the timing of Earth’s formation can be inferred to have occurred nearly 50-70 million years following the formation of the solar system.

text: Plutonium-244 is one of several extinct

text: radionuclide

text: s that preceded the formation of the solar system. Its half-life of 80 million years ensured its circulation across the solar system before its extinction and indeed, Pu has not yet been found in matter other than meteorites. Radionuclides, such as Pu, undergo decay to produce fissiogenic - arising from fission -  xenon isotopes that can then be used to time the events of the early solar system. In fact, by analyzing data from Earth’s mantle that indicate that about 30% of the existing fissiogenic xenon is attributable to Pu decay, the timing of Earth’s formation can be inferred to have occurred nearly 50-70 million years following the formation of the solar system.

text: In January 2013, the utility trade association Edison Electric Institute (EEI) issued a report titled “Disruptive Challenges: Financial Implications and Strategic Responses to a Changing Retail Electric Business”. The report describes the increasing popularity of consumer-driven rooftop solar, energy efficiency, and demand response as a “vicious cycle.” It details how utilities view rooftop solar as a “disruption” to their current business model, which guarantees utilities specific profit margins from large infrastructure projects funded by ratepayers. Peter Kind of Energy Infrastructure Advocates, the author of the report, makes recommendations on how electric utilities can defend against these ‘disruptive challenges.’ TASC and others in the solar industry have been working since 2013 to defend against utility attacks on core rooftop solar policies across the country.

text: In January 2013, the utility trade association

text: Edison Electric Institute

text: (EEI) issued a report titled “Disruptive Challenges: Financial Implications and Strategic Responses to a Changing Retail Electric Business”. The report describes the increasing popularity of consumer-driven rooftop solar, energy efficiency, and demand response as a “vicious cycle.” It details how utilities view rooftop solar as a “disruption” to their current business model, which guarantees utilities specific profit margins from large infrastructure projects funded by ratepayers. Peter Kind of Energy Infrastructure Advocates, the author of the report, makes recommendations on how electric utilities can defend against these ‘disruptive challenges.’ TASC and others in the solar industry have been working since 2013 to defend against utility attacks on core rooftop solar policies across the country.

text: Modern models of the Universe suggest it does not have a center, unlike previous systems which placed the Earth (Geocentrism) or the Sun (Heliocentrism) at the center of the universe.

text: Modern

text: models

text: of the

text: Universe

text: suggest it does not have a center, unlike previous systems which placed the Earth (

text: Geocentrism

text: ) or the Sun (

text: Heliocentrism

text: ) at the center of the universe.

text: Studies of discs around other stars have also done much to establish a time frame for Solar System formation. Stars between one and three million years old have discs rich in gas, whereas discs around stars more than 10 million years old have little to no gas, suggesting that giant planets within them have ceased forming.

text: HD 45364 c is an extrasolar planet located approximately 107 light years away in the constellation of Canis Major, orbiting the eighth magnitude G-type main sequence star HD 45364. This planet is located in a 3:2 orbital resonance with HD 45364 b. It has a minimum mass 3.5 times more massive than HD 45364 b, or 66% that of Jupiter. Its orbit takes 343 days, which is 22 days less than the Earth’s. Its eccentricity is similar to Mars, in which the orbital distance ranges from 0.81 to 0.98 astronomical units. This planet was discovered by HARPS on August 8, 2008, the same day as the planet HD 45364 b.

text: HD 45364 c is an

text: extrasolar planet

text: located approximately 107

text: light year

text: s away in the

text: constellation

text: of

text: Canis Major

text: , orbiting the eighth

text: magnitude

text: G-type

text: main sequence

text: star

text: HD 45364

text: . This planet is located in a 3:2

text: orbital resonance

text: with

text: HD 45364 b

text: . It has a

text: minimum mass

text: 3.5 times more massive than HD 45364 b, or 66% that of Jupiter. Its orbit takes 343 days, which is 22 days less than the

text: Earth

text: ’s. Its eccentricity is similar to

text: Mars

text: , in which the orbital distance ranges from 0.81 to 0.98

text: astronomical units

text: . This planet was discovered by

text: HARPS

text: on August 8, 2008, the same day as the planet

text: HD 45364 b

text: Table of synodic periods in the Solar System, relative to Earth:

text: There is no evidence that the system is home to any extrasolar planets.

text: The nebula is approximately 8,000 years old. It is approximately circular in cross-section with a little visible internal structure. It was formed from the outflow of material from the stellar wind of the central star as it evolved along the asymptotic giant branch. The nebula is arranged in three concentric shells, with the outermost shell being about 20–30% larger than the inner shell. The owl-like appearance of the nebula is the result of an inner shell that is not circularly symmetric, but instead forms a barrel-like structure aligned at an angle of 45° to the line of sight.

text: The nebula is approximately 8,000 years old. It is approximately circular in cross-section with a little visible internal structure. It was formed from the outflow of material from the

text: stellar wind

text: of the central

text: star

text: as it evolved along the

text: asymptotic giant branch

text: . The nebula is arranged in three concentric shells, with the outermost shell being about 20–30% larger than the inner shell. The owl-like appearance of the nebula is the result of an inner shell that is not circularly symmetric, but instead forms a barrel-like structure aligned at an angle of 45° to the line of sight.

text: During the smooth migration of the giant planets the ν5 secular resonance sweeps through the inner Solar System, exciting the eccentricities of the terrestrial planets. For the original Nice model, these eccentricities can reach levels that destabilize the inner Solar System, leading to collisions between planets or the ejection of Mars, during the slow approach of Jupiter and Saturn to their 2:1 resonance. In later versions of the Nice model, Jupiter's and Saturn's divergent migration across (or from) the 2:1 resonance is more rapid and the nearby ν5 resonance crossings are brief, hence not resulting in the excessive excitation of the orbits of Earth and Mars. The authors proposed that the last two resonance crossings were avoided, also preventing the excessive excitation of the eccentricities of Mercury and Venus. This would occur if gravitational encounters between an ice giant and both gas giants caused the Jupiter–Saturn period ratio to jump from below 2.1 to beyond 2.3. The authors named this alternative evolution the jumping-Jupiter scenario.

text: During the smooth migration of the giant planets the ν5

text: secular resonance

text: sweeps through the

text: inner Solar System

text: , exciting the

text: eccentricities

text: of the terrestrial planets. For the original

text: Nice model

text: , these eccentricities can reach levels that destabilize the inner Solar System, leading to collisions between planets or the ejection of Mars, during the slow approach of Jupiter and Saturn to their 2:1

text: resonance

text: . In later versions of the Nice model, Jupiter's and Saturn's divergent migration across (or from) the 2:1 resonance is more rapid and the nearby ν5 resonance crossings are brief, hence not resulting in the excessive excitation of the orbits of Earth and Mars. The authors proposed that the last two resonance crossings were avoided, also preventing the excessive excitation of the eccentricities of Mercury and Venus. This would occur if gravitational encounters between an ice giant and both gas giants caused the Jupiter–Saturn period ratio to jump from below 2.1 to beyond 2.3. The authors named this alternative evolution the jumping-Jupiter scenario.

text: A recent modification of the Nice model has the Solar System begin with five giant planets, including an additional ice giant, in a chain of mean-motion resonances. About 400 million years after the formation of the Solar System the resonance chain is broken. Instead of being scattered into the disc, the ice giants first migrate outward several AU. This divergent migration eventually leads to a resonance crossing, destabilizing the orbits of the planets. The extra ice giant encounters Saturn and is scattered inward onto a Jupiter-crossing orbit and after a series of encounters is ejected from the Solar System. The remaining planets then continue their migration until the planetesimal disc in nearly depleted with small fractions remaining in various locations.

text: A

text: recent modification

text: of the Nice model has the Solar System begin with five giant planets, including an additional ice giant, in a chain of mean-motion resonances. About 400 million years after the formation of the Solar System the resonance chain is broken. Instead of being scattered into the disc, the ice giants first migrate outward several AU. This divergent migration eventually leads to a resonance crossing, destabilizing the orbits of the planets. The extra ice giant encounters Saturn and is scattered inward onto a Jupiter-crossing orbit and after a series of encounters is ejected from the Solar System. The remaining planets then continue their migration until the planetesimal disc in nearly depleted with small fractions remaining in various locations.

text: The nebula has an overall bubble shape, but with complex filamentary structures.  The nebula contains several hundred solar masses of ionised material, plus several thousand more of unionised gas.  It is largely interstellar material swept up by winds from the central star, although some material does appear to be enriched with the products of fusion and is likely to come directly from the star.  The expansion rate of different portions of the nebula varies from 10km/s to at least 30km/s, leading to age estimates of 78,500 - 236,000 years.  The nebula has been studied at radio and x-ray wavelengths, but it is still unclear whether it was produced at the class O main sequence stage of development, as a red supergiant, luminous blue variable, or mainly as a Wolf-Rayet star.

text: The nebula has an overall bubble shape, but with complex filamentary structures.  The nebula contains several hundred solar masses of ionised material, plus several thousand more of unionised gas.  It is largely interstellar material swept up by winds from the central star, although some material does appear to be enriched with the products of fusion and is likely to come directly from the star.  The expansion rate of different portions of the nebula varies from 10km/s to at least 30km/s, leading to age estimates of 78,500 - 236,000 years.  The nebula has been studied at radio and x-ray wavelengths, but it is still unclear whether it was produced at the class O main sequence stage of development, as a

text: red supergiant

text: luminous blue variable

text: , or mainly as a Wolf-Rayet star.

text: Fresno Yosemite International features a 2.4 megawatt solar system, completed in March 2008. The airport purchases solar-generated electricity from the system, which is owned, operated, and maintained by Solar Power Partners and its investors. Solar Power Partners contracted WorldWater & Solar Technologies Corp to construct the system. The solar system was financed through a solar power purchase agreement, which required no capital outlay from the airport. At the time of commissioning, the system was the largest airport solar system in the nation.

text: Fresno Yosemite International features a 2.4 megawatt solar system, completed in March 2008. The airport purchases solar-generated electricity from the system, which is owned, operated, and maintained by Solar Power Partners and its investors. Solar Power Partners contracted WorldWater & Solar Technologies Corp to construct the system. The solar system was financed through a solar

text: power purchase agreement

text: , which required no capital outlay from the airport. At the time of commissioning, the system was the largest airport solar system in the nation.

text: Gravity is thought of as a large-scale force, with a longer reach than any other. But gravity becomes significant even at masses that are tiny compared to the mass of the universe.

text: In 1974, Lilly's research using various psychoactive drugs led him to believe in the existence of a certain hierarchical group of cosmic entities, the lowest of which he later dubbed Earth Coincidence Control Office (E.C.C.O.) in an autobiography published jointly with his wife Antonietta (often referred to as Toni). To elaborate, "There exists a Cosmic Coincidence Control Center (CCCC) with a Galactic substation called Galactic Coincidence Control (GCC). Within GCC is the Solar System Control Unit (SSCU), within which is the Earth Coincidence Control Office (ECCO)." This conclusion had been predicted in his past works having stated that, "For the first time I began to consider that God really existed in me and that there is a guiding intelligence in the universe."

text: In 1974, Lilly's research using various

text: psychoactive drugs

text: led him to believe in the existence of a certain hierarchical group of

text: cosmic entities

text: , the lowest of which he later dubbed Earth Coincidence Control Office (E.C.C.O.) in an autobiography published jointly with his wife Antonietta (often referred to as Toni). To elaborate, "There exists a Cosmic Coincidence Control Center (CCCC) with a Galactic substation called Galactic Coincidence Control (GCC). Within GCC is the Solar System Control Unit (SSCU), within which is the Earth Coincidence Control Office (ECCO)." This conclusion had been predicted in his past works having stated that, "For the first time I began to consider that God really existed in me and that there is a guiding intelligence in the universe."

text: Amalthea's irregular shape and large size led in the past to a conclusion that it is a fairly strong, rigid body, where it was argued that a body composed of ices or other weak materials would have been pulled into a more spherical shape by its own gravity. However, on 5 November 2002, the Galileo orbiter made a targeted flyby that came within 160 km of Amalthea and the deflection of its orbit was used to compute the moon's mass (its volume had been calculated previously—to within 10% or so—from a careful analysis of all extant images). In the end, Amalthea's density was found to be as low as , so it must be either a relatively icy body or very porous "rubble pile" or, more likely, something in between. Recent measurements of infrared spectra from the Subaru telescope suggest that the moon indeed contains hydrous minerals (or organic materials), indicating that it cannot have formed in its current position, since the hot primordial Jupiter would have melted it. It is therefore likely to have formed farther from the planet or to be a captured Solar System body. No images were taken during this flyby (Galileos cameras had been deactivated due to radiation damage in January 2002), and the resolution of other available images is generally low.

text: Amalthea's irregular shape and large size led in the past to a conclusion that it is a fairly strong, rigid body, where it was argued that a body composed of ices or other weak materials would have been pulled into a more

text: spherical

text: shape by its own gravity. However, on 5 November 2002, the

text: Galileo orbiter

text: made a targeted flyby that came within 160 km of Amalthea and the deflection of its orbit was used to compute the moon's mass (its volume had been calculated previously—to within 10% or so—from a careful analysis of all extant images). In the end, Amalthea's density was found to be as low as , so it must be either a relatively icy body or very porous "

text: rubble pile

text: " or, more likely, something in between. Recent measurements of infrared spectra from the

text: Subaru telescope

text: suggest that the moon indeed contains

text: hydrous

text: minerals (or organic materials), indicating that it cannot have formed in its current position, since the hot primordial Jupiter would have melted it. It is therefore likely to have formed farther from the planet or to be a captured

text: Solar System

text: body. No images were taken during this flyby (Galileos cameras had been deactivated due to radiation damage in January 2002), and the resolution of other available images is generally low.

text: Future developments, such as a variable cycloidal rotor, may improve the cyclogyro design. This technology allows the blades to travel about the horizontal axis along the most aerodynamically desirable orbit as continuously determined by the control system. This orbit will generally be non-circular and elongated, with that orbit shape dynamically modified by the control system as the flight regime and conditions change to keep the relative airflow about the blades optimized. The dynamic counterbalancing of the blades radial movements is used to keep the rotor balanced. This design would also allow their operation and the blade orbit shape to be optimized not only for the highest efficiency, but alternatively also for the highest flight speed or for the highest possible lifting capability or for the most silent operation. In addition to the horizontally elongated blade orbits being conducive to greater stability, the ability of this technology to precisely control in real time the localization and distribution of the lift/thrust generation may also largely eliminate the stability issues which is the most serious problem faced by current cyclogyro designs.; the second biggest problem faced by the current designs, namely that of blade bending due to the centrifugal forces, can also be addressed via the trajectory shape as on flat or nearly flat portions of the trajectory the centrifugal force acting on the blades will respectively be either zero or small.

text: In celestial mechanics, an orbital resonance occurs when two orbiting bodies exert a regular, periodic gravitational influence on each other, usually because their orbital periods are related by a ratio of two small integers. The physics principle behind orbital resonance is similar in concept to pushing a child on a swing, where the orbit and the swing both have a natural frequency, and the other body doing the "pushing" will act in periodic repetition to have a cumulative effect on the motion. Orbital resonances greatly enhance the mutual gravitational influence of the bodies, i.e., their ability to alter or constrain each other's orbits.  In most cases, this results in an unstable interaction, in which the bodies exchange momentum and shift orbits until the resonance no longer exists. Under some circumstances, a resonant system can be stable and self-correcting, so that the bodies remain in resonance.  Examples are the 1:2:4 resonance of Jupiter's moons Ganymede, Europa and Io, and the 2:3 resonance between Pluto and Neptune.  Unstable resonances with Saturn's inner moons give rise to gaps in the rings of Saturn.  The special case of 1:1 resonance (between bodies with similar orbital radii) causes large Solar System bodies to eject most other bodies sharing their orbits; this is part of the much more extensive process of clearing the neighbourhood, an effect that is used in the current definition of a planet.

text: In

text: celestial mechanics

text: , an orbital resonance occurs when two

text: orbit

text: ing bodies exert a regular, periodic

text: gravitational

text: influence on each other, usually because their

text: orbital period

text: s are related by a ratio of two small

text: integer

text: s. The physics principle behind orbital resonance is similar in concept to pushing a child on a swing, where the orbit and the swing both have a

text: natural frequency

text: , and the other body doing the "pushing" will act in periodic repetition to have a cumulative effect on the motion. Orbital resonances greatly enhance the mutual gravitational influence of the bodies, i.e., their ability to alter or constrain each other's orbits.  In most cases, this results in an unstable interaction, in which the bodies exchange

text: momentum

text: and shift orbits until the resonance no longer exists. Under some circumstances, a resonant system can be stable and self-correcting, so that the bodies remain in resonance.  Examples are the 1:2:4 resonance of

text: Jupiter

text: 's moons

text: Ganymede

text: Europa

text: and

text: Io

text: , and the 2:3 resonance between

text: Pluto

text: and

text: Neptune

text: .  Unstable resonances with

text: Saturn

text: 's inner moons give rise to gaps in the

text: rings of Saturn

text: .  The special case of 1:1 resonance (between bodies with similar orbital radii) causes large

text: Solar System

text: bodies to eject most other bodies sharing their orbits; this is part of the much more extensive process of

text: clearing the neighbourhood

text: , an effect that is used in the current

text: definition of a planet

text: The Sun is a star located at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma and magnetic fields. It has a diameter of about , around 109 times that of Earth, and its mass (1.989 kilograms, approximately 330,000 times that of Earth) accounts for some 99.86% of the total mass of the Solar System. Chemically, about three quarters of the Sun's mass consists of hydrogen, while the rest is mostly helium. The remaining 1.69% (equal to 5,600 times the mass of Earth) consists of heavier elements, including oxygen, carbon, neon and iron.

text: The Sun is a

text: star

text: located at the center of the

text: Solar System

text: . It is almost perfectly spherical and consists of hot

text: plasma

text: and

text: magnetic field

text: s. It has a diameter of about , around 109 times that of

text: Earth

text: , and its mass (1.989 kilograms, approximately 330,000 times that of Earth) accounts for some 99.86% of the total mass of the Solar System. Chemically, about three quarters of the Sun's mass consists of

text: hydrogen

text: , while the rest is mostly

text: helium

text: . The remaining 1.69% (equal to 5,600 times the mass of Earth) consists of heavier elements, including

text: oxygen

text: carbon

text: neon

text: and

text: iron

text: 'General Services', a very successful company that provides various personal services such as shopping for you or walking your dogs or supplying a host for a party, but also proudly advertises that no job is too large (One ad campaign idea the staff discusses: "Want somebody murdered? Then DON'T call General Services. But for anything else, call.... It Pays!"), is asked to do the impossible: enable an interplanetary conference to be held on Earth, whose strong gravity is inhospitable to many of the native races of other planets in the solar system.

text: 'General Services', a very successful company that provides various personal services such as shopping for you or walking your dogs or supplying a host for a party, but also proudly advertises that no job is too large (One ad campaign idea the staff discusses: "Want somebody murdered? Then DON'T call General Services. But for anything else, call.... It Pays!"), is asked to do the impossible: enable an interplanetary conference to be held on

text: Earth

text: , whose strong

text: gravity

text: is inhospitable to many of the native races of other planets in the solar system.

text: Ptolemy argued that the Earth was a sphere in the center of the universe, from the simple observation that half the stars were above the horizon and half were below the horizon at any time (stars on rotating stellar sphere), and the assumption that the stars were all at some modest distance from the center of the universe. If the Earth was substantially displaced from the center, this division into visible and invisible stars would not be equal.

text: Sun marketed the Sun Constellation System for High-Performance Computing (HPC). Even before the introduction of the Sun Constellation System in 2007, Sun's products were in use in many of the TOP500 systems and supercomputing centers:

text: Sun marketed the

text: Sun Constellation System

text: for

text: High-Performance Computing

text: (HPC). Even before the introduction of the Sun Constellation System in 2007, Sun's products were in use in many of the

text: systems and supercomputing centers:

text: The gravitational slingshot technique uses the gravity of planets and moons to change the speed and direction of a spacecraft without using fuel. In typical example, a spacecraft is sent to a distant planet on a path that is much faster than what the Hohmann transfer would call for. This would typically mean that it would arrive at the planet's orbit and continue past it. However, if there is a planet between the departure point and the target, it can be used to bend the path toward the target, and in many cases the overall travel time is greatly reduced. A prime example of this are the two crafts of the Voyager program, which used slingshot effects to change trajectories several times in the outer Solar System. It is difficult to use this method for journeys in the inner part of the Solar System, although it is possible to use other nearby planets such as Venus or even the Moon as slingshots in journeys to the outer planets.

text: The gravitational slingshot technique uses the

text: gravity

text: of planets and moons to change the speed and direction of a spacecraft without using fuel. In typical example, a spacecraft is sent to a distant planet on a path that is much faster than what the Hohmann transfer would call for. This would typically mean that it would arrive at the planet's orbit and continue past it. However, if there is a planet between the departure point and the target, it can be used to bend the path toward the target, and in many cases the overall travel time is greatly reduced. A prime example of this are the two crafts of the

text: Voyager program

text: , which used slingshot effects to change trajectories several times in the outer Solar System. It is difficult to use this method for journeys in the inner part of the Solar System, although it is possible to use other nearby planets such as Venus or even the

text: Moon

text: as slingshots in journeys to the outer planets.

text: In our Solar System, all of the planets and most of the other objects that orbit the Sun, with the exception of many comets, do so in the "prograde" direction, i.e. the same sense as the rotation of the Sun. Also the rotations of most planets are prograde, with the exceptions of Venus and Uranus, which have retrograde rotations. Most satellites of planets revolve around their planets in the prograde sense. (In the case of the satellites of Uranus, this means they revolve in the same sense as Uranus's rotation, which is retrograde relative to the Sun.) There are some satellites which orbit in the retrograde sense, but these are generally small and distant from their planets, except for Neptune's satellite Triton, which is large and close. It is thought that these retrograde satellites, including Triton, are bodies which have been captured into orbit around their planets, having been formed elsewhere.

text: In our

text: Solar System

text: , all of the

text: planet

text: s and most of the other objects that orbit the

text: Sun

text: , with the exception of many

text: comet

text: s, do so in the "prograde" direction, i.e. the same sense as the rotation of the Sun. Also the rotations of most planets are prograde, with the exceptions of

text: Venus

text: and

text: Uranus

text: , which have retrograde rotations. Most

text: satellites

text: of planets revolve around their planets in the prograde sense. (In the case of the satellites of Uranus, this means they revolve in the same sense as Uranus's rotation, which is retrograde relative to the Sun.) There are some satellites which orbit in the retrograde sense, but these are generally small and distant from their planets, except for

text: Neptune

text: 's satellite

text: Triton

text: , which is large and close. It is thought that these retrograde satellites, including Triton, are bodies which have been captured into orbit around their planets, having been formed elsewhere.

text: Having faced the house towards the sun we use high performance windows to draw in as much light and warmth as possible. Sunlight then floods into the house and any heat generated is retained by a highly insulated building shell, draught proof windows and doors and thermal mass within the building. Having a sunny site also means that we can fit active solar systems, that are both solar water heating panels and electricity generating solar panels on the roofs, thus further adding to the free heat and electricity gained from the sun.

text: The presence of Neptune has a profound effect on the Kuiper belt's structure due to orbital resonances. Over a timescale comparable to the age of the Solar System, Neptune's gravity destabilises the orbits of any objects that happen to lie in certain regions, and either sends them into the inner Solar System or out into the scattered disc or interstellar space. This causes the Kuiper belt to have pronounced gaps in its current layout, similar to the Kirkwood gaps in the asteroid belt. In the region between 40 and 42 AU, for instance, no objects can retain a stable orbit over such times, and any observed in that region must have migrated there relatively recently.

text: The presence of

text: Neptune

text: has a profound effect on the Kuiper belt's structure due to

text: orbital resonance

text: s. Over a timescale comparable to the age of the Solar System, Neptune's gravity destabilises the orbits of any objects that happen to lie in certain regions, and either sends them into the inner Solar System or out into the

text: scattered disc

text: or interstellar space. This causes the Kuiper belt to have pronounced gaps in its current layout, similar to the

text: Kirkwood gap

text: s in the

text: asteroid belt

text: . In the region between 40 and 42 AU, for instance, no objects can retain a stable orbit over such times, and any observed in that region must have migrated there relatively recently.

text: The church holds that the world is in the End Times, a period prophesied by all the great religions, in which God's divine light will bring about a spiritual Golden Age that will restore a universal religion of light and eventually bring about the restoration of the creation to its original state. The church believes that a new solar epoch has dawned with the advent of the Sun of Righteousness. It teaches that man must learn to process the spiritual forces inherent within the heightened cosmic/solar energy streaming down upon the earth for the survival of the human species and for its continued evolution under a new state of the universe. Cosolargy restores and supplements the ancient spiritual systems of the past for the emergence of a highly developed, spiritually evolved modern individual. It is this tenet of the new advent, or appearance, of God's presence and the non-denominational character of Cosolargy that allows the Church of the Second Advent to claim its teaching to be truly ecumenical and universal, for it is not restricted to Christianity alone.

text: The solar system of Anthony's universe directly parallels the political makeup of modern Earth, as outlined in appendices in the series. Following are the many correspondences:

text: To calculate the actual motion of the Sun, you would need to sum all the influences from all the planets, comets, asteroids, etc. of the Solar System (see n-body problem). If all the planets were aligned on the same side of the Sun, the combined center of mass would lie about 500,000 km above the Sun's surface.

text: To calculate the actual motion of the Sun, you would need to sum all the influences from all the

text: planet

text: s,

text: comet

text: s,

text: asteroid

text: s, etc. of the

text: Solar System

text: (see

text: n-body problem

text: ). If all the planets were aligned on the same side of the Sun, the combined center of mass would lie about 500,000 km above the Sun's surface.

text: Newton made clear his heliocentric view of the solar system – developed in a somewhat modern way, because already in the mid-1680s he recognised the "deviation of the Sun" from the centre of gravity of the solar system. For Newton, it was not precisely the centre of the Sun or any other body that could be considered at rest, but rather "the common centre of gravity of the Earth, the Sun and all the Planets is to be esteem'd the Centre of the World", and this centre of gravity "either is at rest or moves uniformly forward in a right line" (Newton adopted the "at rest" alternative in view of common consent that the centre, wherever it was, was at rest).

text: Newton made clear his

text: heliocentric

text: view of the solar system – developed in a somewhat modern way, because already in the mid-1680s he recognised the "deviation of the Sun" from the centre of gravity of the solar system. For Newton, it was not precisely the centre of the Sun or any other body that could be considered at rest, but rather "the common centre of gravity of the Earth, the Sun and all the Planets is to be esteem'd the Centre of the World", and this centre of gravity "either is at rest or moves uniformly forward in a right line" (Newton adopted the "at rest" alternative in view of common consent that the centre, wherever it was, was at rest).

text: Milutin Milanković (, pronounced ; 28 May 1879 – 12 December 1958) was a Serbian mathematician, astronomer, climatologist, geophysicist,  civil engineer, doctor of technology, university professor and popularizer of science. Milanković gave two fundamental contributions to global science. The first contribution is the "Canon of the Earth’s Insolation", which characterizes the climates of all the planets of the Solar system. The second contribution is the explanation of Earth's long-term climate changes caused by changes in the position of the Earth in comparison to the Sun, now known as Milankovitch cycles. This explained the ice ages occurring in the geological past of the Earth, as well as the climate changes on the Earth which can be expected in the future. He founded planetary climatology by calculating temperatures of the upper layers of the Earth's atmosphere as well as the temperature conditions on planets of the inner Solar system, Mercury, Venus, Mars, and the Moon, as well as the depth of the atmosphere of the outer planets. He demonstrated the interrelatedness of celestial mechanics and the Earth sciences, and enabled consistent transition from celestial mechanics to the Earth sciences and transformation of descriptive sciences into exact ones.

text: Milutin Milanković (, pronounced ; 28 May 1879 – 12 December 1958) was a

text: Serbian

text: mathematician

text: astronomer

text: climatologist

text: geophysicist

text: civil engineer

text: doctor of technology

text: university professor

text: and

entity_section: Notable English-language popularizers of science

text: popularizer of science

text: . Milanković gave two fundamental contributions to global science. The first contribution is the "Canon of the Earth’s

text: Insolation

text: ", which characterizes the climates of all the planets of the

text: Solar system

text: . The second contribution is the explanation of

text: Earth

text: 's long-term

text: climate change

text: s caused by changes in the position of the Earth in comparison to the

text: Sun

text: , now known as

text: Milankovitch cycles

text: . This explained the

text: ice age

text: s occurring in the geological past of the Earth, as well as the climate changes on the Earth which can be expected in the future. He founded planetary climatology by calculating temperatures of the upper layers of the Earth's atmosphere as well as the temperature conditions on planets of the inner Solar system,

text: Mercury

text: Venus

text: Mars

text: , and the

text: Moon

text: , as well as the depth of the atmosphere of the outer planets. He demonstrated the interrelatedness of

text: celestial mechanics

text: and the Earth sciences, and enabled consistent transition from celestial mechanics to the Earth sciences and transformation of

text: descriptive science

text: s into

text: exact ones

text: PV solar systems exist in many different configurations with regard to their relationship to inverter systems, external grids, battery banks, or other electrical loads. Regardless of the ultimate destination of the solar power, though, the central problem addressed by MPPT is that the efficiency of power transfer from the solar cell depends on both the amount of sunlight falling on the solar panels and the electrical characteristics of the load. As the amount of sunlight varies, the load characteristic that gives the highest power transfer efficiency changes, so that the efficiency of the system is optimized when the load characteristic changes to keep the power transfer at highest efficiency. This load characteristic is called the maximum power point and MPPT is the process of finding this point and keeping the load characteristic there. Electrical circuits can be designed to present arbitrary loads to the photovoltaic cells and then convert the voltage, current, or frequency to suit other devices or systems, and MPPT solves the problem of choosing the best load to be presented to the cells in order to get the most usable power out.

text: A portion of Wheelers fiction is based on current theories that the presence of gas giants may actually be a necessary factor in the formation of habitable terrestrial planets, as their mass deflects and breaks up potentially devastating threats. Earth-bound comets from outside the solar system tend to either slingshot past Jupiter and launch into hyperbolic orbits that take them far from the terrestrial planets, or may lose momentum and drift peaceably into the Sun. Without the incredible gravitational presence of Jupiter, it's possible that our planet would experience so many impacts and close calls as to prevent advanced evolution or even the formation of life.

text: A portion of Wheelers fiction is based on current theories that the presence of

text: gas giants

text: may actually be a necessary factor in the formation of habitable

text: terrestrial planets

text: , as their mass deflects and breaks up

text: potentially devastating threats

text: . Earth-bound comets from outside the solar system tend to either

text: slingshot

text: past Jupiter and launch into

text: hyperbolic

text: orbits that take them far from the terrestrial planets, or may lose momentum and drift peaceably into the Sun. Without the incredible gravitational presence of Jupiter, it's possible that our planet would experience so many impacts and close calls as to prevent advanced evolution or even the formation of life.

text: The first released VST image (below on the right) shows the spectacular star-forming region Messier 17, also known as the Omega Nebula or the Swan Nebula, as it has never been seen before. This vast region of gas, dust and hot young stars lies in the heart of the Milky Way in the constellation of Sagittarius (The Archer). The VST field of view is so large that the entire nebula, including its fainter outer parts, is captured — and retains its superb sharpness across the entire image. The data were processed using the Astro-WISE software system developed by E.A. Valentijn and collaborators at Groningen and elsewhere.

text: Solar cells could be used to power a vehicle converted to electric.However, currently the relatively small power generated by solar cells means that the other components in the system must be special to compensate for this.For example, the body of even a small conventional car converted to electric is still rather too heavy to be able to be matched with an electric system that is solely or primarily charged by solar power.Thus, it is usually more practical to create a solar-powered electric vehicle from scratch or specially made parts.

text: Gauss developed a method of calculating the orbit of a body from observations and hence needed an accurate and easily derived gravitational constant suitable for Solar System celestial mechanics on an astronomical scale. In formulating it, he specified distance in astronomical units (approximately the radius of Earth's orbit). Orbital period was specified in days, and mass in Solar masses. The result was roughly equal to the mean angular motion of Earth in its orbit around the Sun. In early celestial mechanics, comparative measurements, such as the size of an orbit versus Earth's orbit, or the mass of a body versus the Sun's mass, were easier to make and known more accurately than the same values in standard units—for instance, kilometers or kilograms. For these reasons, k was more appropriate for theoretical work.

text: Gauss developed a method of calculating the orbit of a body from observations and hence needed an accurate and easily derived gravitational constant suitable for

text: Solar System

text: celestial mechanics

text: on an astronomical scale. In formulating it, he specified distance in

text: astronomical unit

text: s (approximately the radius of

text: Earth's

text: orbit).

text: Orbital period

text: was specified in

text: day

text: s, and

text: mass

text: in

text: Solar mass

text: es. The result was roughly equal to the

text: mean angular motion

text: of Earth in its orbit around the

text: Sun

text: . In early celestial mechanics, comparative measurements, such as the size of an orbit versus Earth's orbit, or the mass of a body versus the Sun's mass, were easier to make and known more accurately than the same values in standard units—for instance,

text: kilometer

text: s or

text: kilogram

text: s. For these reasons, k was more appropriate for theoretical work.

text: Previously, theories describing the formation of the Sun and planets could not explain how the Sun has 99.87% of the mass, yet only 0.54% of the angular momentum in the solar system. In a closed system such as the cloud of gas and dust from which the Sun was formed, mass and angular momentum are both conserved. That conservation would imply that as the mass concentrated in the center of the cloud to form the Sun, it would spin faster, much like a skater pulling their arms in. The high speed of rotation predicted by early theories would have flung the proto-Sun apart before it could have formed. However, magnetohydrodynamic effects transfer the Sun's angular momentum into the outer solar system, slowing its rotation.

text: Previously, theories describing the formation of the Sun and planets could not explain how the Sun has 99.87% of the mass, yet only 0.54% of the

text: angular momentum

text: in the

text: solar system

text: . In a

text: closed system

text: such as the cloud of gas and dust from which the Sun was formed, mass and angular momentum are both

text: conserved

text: . That conservation would imply that as the mass concentrated in the center of the cloud to form the Sun, it would spin faster, much like a skater pulling their arms in. The high speed of rotation predicted by early theories would have flung the proto-Sun apart before it could have formed. However, magnetohydrodynamic effects transfer the Sun's angular momentum into the outer solar system, slowing its rotation.

text: At the back of the vehicle is the service module (: приборно-агрегатный отсек (ПАО), Priborno-Agregatniy Otsek (PAO)). It has an instrumentation compartment (: приборный отсек (ПО), Priborniy Otsek (PO)), a pressurized container shaped like a bulging can that contains systems for temperature control, electric power supply, long-range radio communications, radio telemetry, and instruments for orientation and control. The propulsion compartment (: агрегатный отсек (АО), Agregatniy Otsek (AO)), a non-pressurized part of the service module, contains the main engine and a spare: liquid-fuel propulsion systems for maneuvering in orbit and initiating the descent back to Earth. The ship also has a system of low-thrust engines for orientation, attached to the intermediate compartment (: переходной отсек (ПхО), Perekhodnoi Otsek (PkhO)). Outside the service module are the sensors for the orientation system and the solar array, which is oriented towards the sun by rotating the ship.

text: At the back of the vehicle is the service module (: приборно-агрегатный отсек (ПАО), Priborno-Agregatniy Otsek (PAO)). It has an instrumentation compartment (: приборный отсек (ПО), Priborniy Otsek (PO)), a pressurized container shaped like a bulging can that contains systems for temperature control, electric power supply, long-range

text: radio

text: communications, radio telemetry, and instruments for orientation and control. The propulsion compartment (: агрегатный отсек (АО), Agregatniy Otsek (AO)), a non-pressurized part of the service module, contains the main engine and a spare: liquid-fuel

text: propulsion systems

text: for maneuvering in orbit and initiating the descent back to Earth. The ship also has a system of low-thrust engines for orientation, attached to the intermediate compartment (: переходной отсек (ПхО), Perekhodnoi Otsek (PkhO)). Outside the service module are the sensors for the orientation system and the solar array, which is oriented towards the sun by rotating the ship.

text: An extremely eccentric extrasolar planet was announced around HD 20782 in 2006. In 2009 this planet's orbit was narrowed down, and it was found to have the highest eccentricity of all known exoplanets; this distinction has stood since 2012.

text: An extremely eccentric

text: extrasolar planet

text: was announced around HD 20782 in 2006. In 2009 this planet's orbit was narrowed down, and it was found to have the highest eccentricity of all known exoplanets; this distinction has stood since 2012.

text: The point at which the Solar System ends and interstellar space begins is not precisely defined because its outer boundaries are shaped by two separate forces: the solar wind and the Sun's gravity. The limit of the solar wind's influence is roughly four times Pluto's distance from the Sun; this heliopause, the outer boundary of the heliosphere, is considered the beginning of the interstellar medium. The Sun's Hill sphere, the effective range of its gravitational dominance, is thought to extend up to a thousand times farther and encompasses the theorized Oort cloud.

text: The point at which the Solar System ends and interstellar space begins is not precisely defined because its outer boundaries are shaped by two separate forces: the solar wind and the Sun's gravity. The limit of the solar wind's influence is roughly four times Pluto's distance from the Sun; this heliopause, the outer boundary of the

text: heliosphere

text: , is considered the beginning of the

text: interstellar medium

text: . The Sun's

text: Hill sphere

text: , the effective range of its gravitational dominance, is thought to extend up to a thousand times farther and encompasses the theorized

text: Oort cloud

text: The overall structure of the charted regions of the Solar System consists of the Sun, four relatively small inner planets surrounded by a belt of mostly rocky asteroids, and four giant planets surrounded by the Kuiper belt of mostly icy objects. Astronomers sometimes informally divide this structure into separate regions. The inner Solar System includes the four terrestrial planets and the asteroid belt. The outer Solar System is beyond the asteroids, including the four giant planets. Since the discovery of the Kuiper belt, the outermost parts of the Solar System are considered a distinct region consisting of the objects beyond Neptune.

text: Solar System models, especially mechanical models, called orreries, that illustrate the relative positions and motions of the planets and moons in the Solar System have been built for centuries. While they often showed relative sizes, these models were usually not built to scale. The enormous ratio of interplanetary distances to planetary diameters makes constructing a scale model of the Solar System a challenging task. As one example of the difficulty, the distance between the Earth and the Sun is almost 12,000 times the diameter of the Earth.

text: Solar System models, especially mechanical models, called

text: orrerie

text: s, that illustrate the relative positions and motions of the

text: planet

text: s and

text: moon

text: s in the

text: Solar System

text: have been built for centuries. While they often showed relative sizes, these models were usually not built to scale. The enormous ratio of interplanetary distances to planetary diameters makes constructing a

text: scale model

text: of the Solar System a challenging task. As one example of the difficulty, the distance between the

text: Earth

text: and the

text: Sun

text: is almost 12,000 times the diameter of the Earth.

text: It is suspected that Pluto's satellite system was created by a massive collision, similar to the "big whack" thought to have created the Moon. In both cases, the high angular momenta of the moons can only be explained by such a scenario. The nearly circular orbits of the smaller moons suggests that they were also formed in this collision, rather than being captured Kuiper Belt objects. This and their near orbital resonances with Charon (see below) suggest that they formed closer to Pluto than they are at present and migrated outward as Charon reached its current orbit. Their grey color is different from that of Pluto, one of the reddest bodies in the Solar System. This is thought to be due to a loss of volatiles during the impact or subsequent coalescence, leaving the surfaces of the moons dominated by water ice. However, such an impact should have created additional debris (more moons), yet no moons or rings were discovered by New Horizons, ruling out any more moons of significant size orbiting Pluto.

text: It is suspected that Pluto's satellite system was

text: created by a massive collision

text: , similar to the

text: "big whack"

text: thought to have created the

text: Moon

text: . In both cases, the high

text: angular momenta

text: of the moons can only be explained by such a scenario. The nearly circular orbits of the smaller moons suggests that they were also formed in this collision, rather than being captured Kuiper Belt objects. This and their near

text: orbital resonance

text: s with Charon (see below) suggest that they formed closer to Pluto than they are at present and migrated outward as Charon reached its current orbit. Their grey color is different from that of Pluto, one of the reddest bodies in the Solar System. This is thought to be due to a loss of volatiles during the impact or subsequent coalescence, leaving the surfaces of the moons dominated by water ice. However, such an impact should have created additional debris (more moons), yet no moons or rings were discovered by New Horizons, ruling out any more moons of significant size orbiting Pluto.

text: However, he goes on to say that, "For most people, considering round satellites (including our Moon) "planets" violates the idea of what a planet is."

text: For almost five millennia, the geocentric model of the Earth as the center of the universe had been accepted by all but a few astronomers. In Aristotle's cosmology, Earth's central location was perhaps less significant than its identification as a realm of imperfection, inconstancy, irregularity and change, as opposed to the "heavens", (Moon, Sun, planets, stars) which were regarded as perfect, permanent, unchangeable, and in religious thought, the realm of heavenly beings. The Earth was even composed of different material, the four elements "earth", "water", "fire", and "air", while sufficiently far above its surface (roughly the Moon's orbit), the heavens were composed of different substance called "aether". The heliocentric model that replaced it involved not only the radical displacement of the earth to an orbit around the sun, but its sharing a placement with the other planets implied a universe of heavenly components made from the same changeable substances as the Earth. Heavenly motions no longer needed to be governed by a theoretical perfection, confined to circular orbits.

text: For almost five

text: millennia

text: , the

text: geocentric model

text: of the Earth as the center of the universe had been accepted by all but a few astronomers. In Aristotle's cosmology, Earth's central location was perhaps less significant than its identification as a realm of imperfection, inconstancy, irregularity and change, as opposed to the "heavens", (Moon, Sun, planets, stars) which were regarded as perfect, permanent, unchangeable, and in religious thought, the realm of heavenly beings. The Earth was even composed of different material, the four elements "earth", "water", "fire", and "air", while sufficiently far above its surface (roughly the Moon's orbit), the heavens were composed of different substance called "aether". The

text: heliocentric model

text: that replaced it involved not only the radical displacement of the earth to an orbit around the sun, but its sharing a placement with the other planets implied a universe of heavenly components made from the same changeable substances as the Earth. Heavenly motions no longer needed to be governed by a theoretical perfection, confined to circular orbits.

text: On Earth, the analemma appears as a figure-eight, but on other solar system bodies it may be very different because of the interplay between the tilt of each body's axis and the elliptical shape of its orbit. So, if one of these (like eccentricity) always dominates the other (as is the case on Mars), the curve will be a teardrop. If one of them (like eccentricity) is significant and the other is practically zero (as is the case on Jupiter, with a 3 degree tilt only), it will be something much closer to an ellipse. If both are important enough, that sometimes eccentricity dominates and sometimes axial tilt dominates, a figure-eight results.

text: On Earth, the analemma appears as a

text: figure-eight

text: , but on other solar system bodies it may be very different because of the interplay between the tilt of each body's

text: axis

text: and the elliptical shape of its orbit. So, if one of these (like eccentricity) always dominates the other (as is the case on Mars), the curve will be a teardrop. If one of them (like eccentricity) is significant and the other is practically zero (as is the case on Jupiter, with a 3 degree tilt only), it will be something much closer to an ellipse. If both are important enough, that sometimes eccentricity dominates and sometimes axial tilt dominates, a figure-eight results.

text: Sharpless 264, also known as the Lambda Orionis Ring, is a molecular cloud and H II region, which can be seen in the northern region of the Orion Molecular Cloud Complex (OMCC), in the constellation of Orion. The OMCC is one of the best-known star formation regions and the closest sector of the Milky Way to our Solar System where high-mass stars are born. The nebula is named after its main star, λ Orionis, a blue giant responsible for the ionization of the surrounding material. It is also sometimes called the Angelfish Nebula due to its resemblance to an angelfish.

text: Sharpless 264, also known as the Lambda Orionis Ring, is a

text: molecular cloud

text: and

text: H II region

text: , which can be seen in the northern region of the

text: Orion Molecular Cloud Complex

text: (OMCC), in the constellation of

text: Orion

text: . The OMCC is one of the best-known

text: star formation

text: regions and the closest sector of the

text: Milky Way

text: to our

text: Solar System

text: where high-mass

text: star

text: s are born. The

text: nebula

text: is named after its main star,

text: λ Orionis

text: , a

text: blue giant

text: responsible for the

text: ionization

text: of the surrounding material. It is also sometimes called the Angelfish Nebula due to its resemblance to an

text: angelfish

text: Traditionally, the energies and manifestations of the planets were different based on their declination or motion; for the planets Mercury, Venus, Mars, Jupiter, and Saturn, the diurnal energy represents the planet in direct motion, while the nocturnal energy refers to the retrograde motion of the planets.  For the Moon, this was illustrated by the waxing or waning periods of the Moon, respectively; the Sun's figures were based on the Sun during the day (or northern declination) or during the night (southern declination).  The zodiacal rulerships followed from the diurnal or nocturnal planetary rulership: nocturnal figures are assigned earth and water signs, while diurnal figures are assigned fire and air signs.  The North Node is assigned, by Gerard of Cremona, to Sagittarius and the South Node to Virgo (for the sake of finding the ascendant in astrological traditions of geomancy).  Once the zodiacal rulerships were agreed upon, all the following correspondences followed upon the geomantic figures, including what part of the body they each ruled over, different countries, planetary hours, body and character types, and so on.

text: Traditionally, the energies and manifestations of the planets were different based on their

text: declination

text: or

text: motion

text: ; for the planets Mercury, Venus, Mars, Jupiter, and Saturn, the diurnal energy represents the planet in direct motion, while the nocturnal energy refers to the retrograde motion of the planets.  For the Moon, this was illustrated by the waxing or waning periods of the Moon, respectively; the Sun's figures were based on the Sun during the day (or northern declination) or during the night (southern declination).  The zodiacal rulerships followed from the diurnal or nocturnal planetary rulership: nocturnal figures are assigned earth and water signs, while diurnal figures are assigned fire and air signs.  The North Node is assigned, by Gerard of Cremona, to Sagittarius and the South Node to Virgo (for the sake of finding the ascendant in astrological traditions of geomancy).  Once the zodiacal rulerships were agreed upon, all the following correspondences followed upon the geomantic figures, including what part of the body they each ruled over, different countries,

text: planetary hours

text: , body and character types, and so on.

text: Naturally occurring samarium (Sm) is composed of five stable isotopes, Sm, Sm, Sm, Sm and Sm, and two extremely long-lived radioisotopes, Sm (half life: 1.06 y) and Sm (7 y), with Sm being the most abundant (26.75% natural abundance). Sm is also fairly long-lived (6.8×10 y), but is not long-lived enough to have survived from the formation of the Solar System on Earth, although it remains useful in radiometric dating in the Solar System.

text: Naturally occurring

text: samarium

text: (Sm) is composed of five stable

text: isotope

text: s, Sm, Sm, Sm, Sm and Sm, and two extremely long-lived

text: radioisotope

text: s, Sm (half life: 1.06 y) and Sm (7 y), with Sm being the most abundant (26.75%

text: natural abundance

text: ). Sm is also fairly long-lived (6.8×10 y), but is not long-lived enough to have survived from the formation of the Solar System on Earth, although it remains useful in radiometric dating in the Solar System.

text: In practice the Earth's orbit is slightly elliptic rather than circular and its speed changes somewhat over the course of its orbit, which means the description above is only approximate. Aberration is more accurately calculated using the Earth's instantaneous velocity relative to the center of mass of the Solar System.

text: Most solar collectors are fixed in their array position mounting, but can have a higher performance if they track the path of the sun through the sky (however it is unusual for thermal collectors to be mounted in this way). Solar trackers, used to orient solar arrays may be driven by either passive or active technology, and can have a significant gain in energy yield over the course of a year when compared to a fixed array. Again passive solar tracking would rely on the inherent thermo-dynamic properties of the materials used in the system rather than an external power source to generate its tracking movement. Active Solar Tracking would utilise sensors and motors track the path of the sun across the sky. This action can be caused by geographical and time data being programmed into the controls. However, some systems actually track the brightest point in the sky using light sensors, and manufacturers claim this can add a significant extra yield over and above geographical tracking.

text: Most solar collectors are fixed in their array position mounting, but can have a higher performance if they track the path of the sun through the sky (however it is unusual for thermal collectors to be mounted in this way).

text: Solar tracker

text: s, used to orient solar arrays may be driven by either passive or active technology, and can have a significant gain in energy yield over the course of a year when compared to a fixed array. Again passive solar tracking would rely on the inherent thermo-dynamic properties of the materials used in the system rather than an external power source to generate its tracking movement. Active Solar Tracking would utilise sensors and motors track the path of the sun across the sky. This action can be caused by geographical and time data being programmed into the controls. However, some systems actually track the brightest point in the sky using light sensors, and manufacturers claim this can add a significant extra yield over and above geographical tracking.

text: In 1997, SELF decided to launch a for-profit affiliate, the Solar Electric Light Company, or SELCO, based in Bangalore, India, whose goal would be to sell solar home systems in the states of Karnataka and Andhra Pradesh. Neville Williams stepped down from his role with SELF to run SELCO, and SELF’s board of directors appointed Robert A. Freling as the new executive director. Since 1995, SELCO has sold, serviced, and financed over 115,000 solar systems.

text: In 1997, SELF decided to launch a for-profit affiliate, the

text: Solar Electric Light Company

text: , or SELCO, based in

text: Bangalore

text: , India, whose goal would be to sell solar home systems in the states of

text: Karnataka

text: and

text: Andhra Pradesh

text: . Neville Williams stepped down from his role with SELF to run SELCO, and SELF’s board of directors appointed Robert A. Freling as the new executive director. Since 1995, SELCO has sold, serviced, and financed over 115,000 solar systems.

text: In celestial mechanics, an orbital resonance occurs when two orbiting bodies exert a regular, periodic gravitational influence on each other, usually due to their orbital periods being related by a ratio of two small integers. Orbital resonances greatly enhance the mutual gravitational influence of the bodies. In most cases, this results in an unstable interaction, in which the bodies exchange momentum and shift orbits until the resonance no longer exists. Under some circumstances, a resonant system can be stable and self-correcting, so that the bodies remain in resonance. Examples are the 1:2:4 resonance of Jupiter's moons Ganymede, Europa, and Io, and the 2:3 resonance between Pluto and Neptune. Unstable resonances with Saturn's inner moons give rise to gaps in the rings of Saturn. The special case of 1:1 resonance (between bodies with similar orbital radii) causes large Solar System bodies to clear the neighborhood around their orbits by ejecting nearly everything else around them; this effect is used in the current definition of a planet.

text: In

text: celestial mechanics

text: , an

text: orbital resonance

text: occurs when two

text: orbit

text: ing bodies exert a regular, periodic gravitational influence on each other, usually due to their

text: orbital period

text: s being related by a ratio of two small integers. Orbital resonances greatly enhance the mutual gravitational influence of the bodies. In most cases, this results in an unstable interaction, in which the bodies exchange momentum and shift orbits until the resonance no longer exists. Under some circumstances, a resonant system can be stable and self-correcting, so that the bodies remain in resonance. Examples are the 1:2:4 resonance of

text: Jupiter

text: 's moons

text: Ganymede

text: Europa

text: , and

text: Io

text: , and the 2:3 resonance between

text: Pluto

text: and

text: Neptune

text: . Unstable resonances with

text: Saturn

text: 's inner moons give rise to gaps in the

text: rings of Saturn

text: . The special case of 1:1 resonance (between bodies with similar orbital radii) causes large Solar System bodies to

text: clear the neighborhood

text: around their orbits by ejecting nearly everything else around them; this effect is used in the current

text: definition of a planet

text: The Modified Newtonian dynamics or MOND hypothesis proposed that the force of gravity deviates from the traditional Newtonian value to a very different force law at very low accelerations on the order of 10 m/s. Given the low accelerations placed on the spacecraft while in the outer Solar System, MOND may be in effect, modifying the normal gravitational equations. The Lunar Laser Ranging experiment combined with data of LAGEOS satellites refutes that simple gravity modification is the cause of the Pioneer anomaly. The precession of the longitudes of perihelia of the solar planets or the trajectories of long-period comets have not been reported to experience an anomalous gravitational field toward the Sun of the magnitude capable of describing the Pioneer anomaly.

text: The

text: Modified Newtonian dynamics

text: or MOND

text: hypothesis

text: proposed that the force of gravity deviates from the traditional Newtonian value to a very different force law at very low accelerations on the order of 10 m/s. Given the low accelerations placed on the spacecraft while in the outer Solar System, MOND may be in effect, modifying the normal gravitational equations. The

text: Lunar Laser Ranging experiment

text: combined with data of

text: LAGEOS

text: satellites refutes that simple gravity modification is the cause of the Pioneer anomaly. The precession of the longitudes of perihelia of the solar planets or the trajectories of long-period comets have not been reported to experience an anomalous gravitational field toward the Sun of the magnitude capable of describing the Pioneer anomaly.

text: The shapes of the orbits of an inverse cube law are known as Cotes spirals.  The Binet equation shows that the orbits must be solutions to the equation

text: The shapes of the orbits of an inverse cube law are known as

text: Cotes spiral

text: s.  The Binet equation shows that the orbits must be solutions to the equation

text: Unlike most other chondrites, the minerals in enstatite chondrites contain almost no iron oxide; they are the most oxygen-poor silicate rocks known. They are also the driest objects in the solar system, consisting of only 0.01% water. Metallic Fe-Ni (iron-nickel) and Fe-bearing sulfide minerals contain nearly all of the iron in this type of meteorite. Enstatite chondrites contain a variety of unusual minerals that can only form in extremely reducing conditions, including oldhamite (CaS), niningerite (MgS), perryite (Fe-Ni silicide), and alkali sulfides (e.g., djerfisherite and caswellsilverite). All enstatite chondrites are dominantly composed of enstatite-rich chondrules plus abundant grains of metal and sulfide minerals. Dusty matrix material is uncommon and refractory inclusions are very rare. Chemically, enstatite chondrites are very low in refractory lithophile elements. Their oxygen isotopic compositions are intermediate between ordinary and carbonaceous chondrites, and are similar to rocks found on the Earth and Moon. Their lack of oxygen content may mean that they were originally formed near the center of the solar nebula that created the solar system, possibly within the orbit of Mercury. Most enstatite chondrites have experienced thermal metamorphism on the parent asteroids. They are divided into two groups:

text: Unlike most other chondrites, the minerals in enstatite chondrites contain almost no iron oxide; they are the most oxygen-poor silicate rocks known. They are also the driest objects in the solar system, consisting of only 0.01% water. Metallic Fe-Ni (iron-nickel) and Fe-bearing sulfide minerals contain nearly all of the iron in this type of meteorite. Enstatite chondrites contain a variety of unusual minerals that can only form in extremely reducing conditions, including

text: oldhamite

text: (CaS),

text: niningerite

text: (MgS),

text: perryite

text: (Fe-Ni silicide), and alkali sulfides (e.g.,

text: djerfisherite

text: and

text: caswellsilverite

text: ). All enstatite chondrites are dominantly composed of enstatite-rich chondrules plus abundant grains of metal and sulfide minerals. Dusty matrix material is uncommon and refractory inclusions are very rare. Chemically, enstatite chondrites are very low in refractory lithophile elements. Their oxygen isotopic compositions are intermediate between ordinary and carbonaceous chondrites, and are similar to rocks found on the Earth and Moon. Their lack of oxygen content may mean that they were originally formed near the center of the solar nebula that created the

text: solar system

text: , possibly within the orbit of

text: Mercury

text: . Most enstatite chondrites have experienced thermal metamorphism on the parent asteroids. They are divided into two groups:

text: During the early history of the Solar System, the asteroids melted to some degree, allowing elements within them to be partially or completely differentiated by mass. Some of the progenitor bodies may even have undergone periods of explosive volcanism and formed magma oceans. However, because of the relatively small size of the bodies, the period of melting was necessarily brief (compared to the much larger planets), and had generally ended about 4.5 billion years ago, in the first tens of millions of years of formation. In August 2007, a study of zircon crystals in an Antarctic meteorite believed to have originated from 4 Vesta suggested that it, and by extension the rest of the asteroid belt, had formed rather quickly, within ten million years of the Solar System's origin.

text: During the early history of the Solar System, the asteroids melted to some degree, allowing elements within them to be partially or completely differentiated by mass. Some of the progenitor bodies may even have undergone periods of explosive

text: volcanism

text: and formed

text: magma

text: oceans. However, because of the relatively small size of the bodies, the period of melting was necessarily brief (compared to the much larger planets), and had generally ended about 4.5 billion years ago, in the first tens of millions of years of formation. In August 2007, a study of

text: zircon

text: crystals in an Antarctic meteorite believed to have originated from 4 Vesta suggested that it, and by extension the rest of the asteroid belt, had formed rather quickly, within ten million years of the Solar System's origin.

text: Historically, the center of the Universe had been believed to be a number of locations. Many mythological cosmologies included an axis mundi, the central axis of a flat Earth that connects the Earth, heavens, and other realms together. In the 4th century BCE Greece, the geocentric model was developed based on astronomical observation, proposing that the center of the Universe lies at the center of a spherical, stationary Earth, around which the sun, moon, planets, and stars rotate. With the development of the heliocentric model by Nicolaus Copernicus in the 16th century, the sun was believed to be the center of the Universe, with the planets (including Earth) and stars orbiting it.

text: Historically, the center of the Universe had been believed to be a number of locations. Many mythological cosmologies included an

text: axis mundi

text: , the central axis of a flat Earth that connects the Earth, heavens, and other realms together. In the 4th century BCE Greece, the

text: geocentric model

text: was developed based on astronomical observation, proposing that the center of the Universe lies at the center of a spherical, stationary Earth, around which the sun, moon, planets, and stars rotate. With the development of the

text: heliocentric

text: model by

text: Nicolaus Copernicus

text: in the 16th century, the sun was believed to be the center of the Universe, with the planets (including Earth) and stars orbiting it.

text: Tidal heating (also known as tidal working) occurs through the tidal friction processes: orbital and rotational energy are dissipated as heat in the crust of the moons and planets involved. Io has a similar mass and size as the Moon, but Io is the most geologically active body in the Solar System. This is caused by the heating mechanism of Io. The major heating source of Earth and its moon is radioactive heating, but the heating source on Io is tidal heating. As Jupiter is very massive, the side of Io nearest to Jupiter has a slightly larger gravitational pull than the opposite side. This difference in gravitational forces cause distortion of Io’s shape. Differently from the Earth’s only moon, Jupiter has several moons (i.e. Io, Europa, Ganymede and Callisto). As Io is the innermost moon of Jupiter, Jupiter pulls Io inward and other moons pull Io outward. This causes Io’s orbit to be elliptical and eccentric. The distance between Jupiter and Io changes all the time and the distortion of Io likewise changes all the time. The constant change in the shape of Io results in a large amount of friction in the moon and the friction-induced heating drives strong volcanic activities on the surface of Io.

text: Tidal heating

text: (also known as tidal working) occurs through the tidal friction processes: orbital and rotational energy are dissipated as heat in the crust of the moons and planets involved. Io has a similar mass and size as the

text: Moon

text: , but

text: Io

text: is the most geologically active body in the

text: Solar System

text: . This is caused by the heating mechanism of Io. The major heating source of Earth and its moon is radioactive heating, but the heating source on Io is

text: tidal heating

text: . As Jupiter is very massive, the side of Io nearest to

text: Jupiter

text: has a slightly larger gravitational pull than the opposite side. This difference in gravitational forces cause distortion of Io’s shape. Differently from the Earth’s only moon, Jupiter has several moons (i.e. Io,

text: Europa

text: Ganymede

text: and

text: Callisto

text: ). As Io is the innermost moon of Jupiter, Jupiter pulls Io inward and other moons pull Io outward. This causes Io’s orbit to be elliptical and

text: eccentric

text: . The distance between Jupiter and Io changes all the time and the distortion of Io likewise changes all the time. The constant change in the shape of Io results in a large amount of friction in the moon and the friction-induced heating drives strong volcanic activities on the surface of Io.

text: Ehricke was an accomplished practitioner in the field of astrodynamics and its applications.  His two-volume work entitled Space Flight is probably the most complete and surely the most useful introduction to this complex subject ever written.  It focuses on methods for exploration of the solar system.  He clearly demonstrated the so-called "gravity assist" method for utilizing hyperbolic encounters with an intermediate planet to increase (or decrease) the velocity and orbital elements of a space vehicle.  This technique had opened the entire solar system to robotic exploration by using what he called "Instrumented Comets."  Examples include the Voyager missions to the outer planets and the recent successful New Horizons mission to Pluto. His contribution to this important field of exploration has been neglected for many decades and incorrect claims of "invention" of what is now called gravity assist were made by Minovitch.

text: M60-UCD1's mass is 140 million solar masses. Colours and lack of colour gradients indicate a uniform stellar population about 14.5±0.5 billion years old(indistinguishable from the age of the Universe).Their metallicity is similar to that of the Sun.The orbital velocity dispersion of the innermost stars exceeds 100 km/s,due to the gravity of a dense mass concentration.The galactic nucleus contains a bright and variable X-ray source,presumably a supermassive black hole with a mass of 20 million solar masses (15% of the mass of the entire galaxy). With this proportion of the mass of the black hole to that of the whole galaxy, it is one of the most black hole dominated galaxies known.

text: M60-UCD1's mass is 140 million

text: solar mass

text: es. Colours and lack of colour gradients indicate a uniform stellar population about 14.5±0.5 billion years old(indistinguishable from the age of the

text: Universe

text: ).Their

text: metallicity

text: is similar to that of the

text: Sun

text: .The orbital velocity dispersion of the innermost stars exceeds 100 km/s,due to the gravity of a dense mass concentration.The galactic nucleus contains a bright and variable

text: X-ray source

text: ,presumably a

text: supermassive black hole

text: with a mass of 20 million

text: solar mass

text: es (15% of the mass of the entire galaxy). With this proportion of the mass of the black hole to that of the whole galaxy, it is one of the most black hole dominated galaxies known.

text: They return to the rescue ship to find Rassmussen there, along with a Morpheus pod he claims contains the first patient of the Morpheus process from five years prior. Rassmussen admits that his goal is to aid the Sandmen to leave the station and get to Triton, from where they can infect the rest of the solar system; the gravity shield failure was planned to allow him to send the pod to the rescue ship without attracting attention. Rassmussen attempts to lock the three in a part of the rescue ship with the patient, now a Sandman, but the Doctor engineers their escape, and Nagata shoots Rassmussen before he can launch the ship. The Doctor leads them to the TARDIS, realising that the events that have happened are too choreographed to seem like a real danger. As they are surrounded by Sandmen, the Doctor deactivates the gravity shields, causing the Sandmen to disintegrate, and the three escape into the TARDIS as the station plummets to Neptune.

text: They return to the rescue ship to find Rassmussen there, along with a Morpheus pod he claims contains the first patient of the Morpheus process from five years prior. Rassmussen admits that his goal is to aid the Sandmen to leave the station and get to Triton, from where they can infect the rest of the solar system; the gravity shield failure was planned to allow him to send the pod to the rescue ship without attracting attention. Rassmussen attempts to lock the three in a part of the rescue ship with the patient, now a Sandman, but the Doctor engineers their escape, and Nagata shoots Rassmussen before he can launch the ship. The Doctor leads them to the

text: TARDIS

text: , realising that the events that have happened are too choreographed to seem like a real danger. As they are surrounded by Sandmen, the Doctor deactivates the gravity shields, causing the Sandmen to disintegrate, and the three escape into the TARDIS as the station plummets to Neptune.

text: The capture theory, proposed by M. M. Woolfson in 1964, posits that the Solar System formed from tidal interactions between the Sun and a low-density protostar. The Sun's gravity would have drawn material from the diffuse atmosphere of the protostar, which would then have collapsed to form the planets. However, the capture theory predicts a different age for the Sun than for the planets, whereas the similar ages of the Sun and the rest of the Solar System indicate that they formed at roughly the same time.

text: The capture theory, proposed by

text: M. M. Woolfson

text: in 1964, posits that the Solar System formed from

text: tidal

text: interactions between the Sun and a low-density

text: protostar

text: . The Sun's gravity would have drawn material from the diffuse atmosphere of the protostar, which would then have collapsed to form the planets. However, the capture theory predicts a different age for the Sun than for the planets, whereas the similar ages of the Sun and the rest of the Solar System indicate that they formed at roughly the same time.

text: Hektor is one of the most elongated bodies of its size in the Solar System, being 370 × 200 km. It is thought that Hektor might be a contact binary (two asteroids joined by gravitational attraction) like 216 Kleopatra. Hubble Space Telescope observations of Hektor in 1993 did not show an obvious bilobate shape because of a limited angular resolution. On 17 July 2006, the Keck 10-meter-II-telescope and its laser guide star adaptive optics (AO) system indicated a bilobate shape for Hektor. Additionally, a 12-km-diameter moon of Hektor, S/2006 (624) 1, was detected orbiting with a semi-major axis of  and an orbital period of 2.9651 day. It was confirmed with Keck observations in November 2011. Hektor is, so far, the only known binary trojan asteroid in the  point and the first known trojan with a satellite companion. 617 Patroclus, another large trojan asteroid located in the , is composed of two same-sized components.

text: Hektor is one of the most elongated bodies of its size in the

text: Solar System

text: , being 370 × 200 km. It is thought that Hektor might be a

entity_name: Contact binary (small Solar System body)

text: contact binary

text: (two asteroids joined by gravitational attraction) like

text: 216 Kleopatra

text: Hubble Space Telescope

text: observations of Hektor in 1993 did not show an obvious

text: bilobate

text: shape because of a limited

text: angular resolution

text: . On 17 July 2006, the

text: Keck

text: 10-meter-II-telescope and its

text: laser guide star

text: adaptive optics

text: (AO) system indicated a bilobate shape for Hektor. Additionally, a 12-km-diameter moon of Hektor, S/2006 (624) 1, was detected orbiting with a semi-major axis of  and an orbital period of 2.9651 day. It was confirmed with Keck observations in November 2011. Hektor is, so far, the only known binary trojan asteroid in the  point and the first known trojan with a satellite companion.

text: 617 Patroclus

text: , another large trojan asteroid located in the , is composed of two same-sized components.

text: The nebula is important because of its sheer size, as it spreads several degrees from Orion's Belt to his sword.  It is also one of the most active regions of stellar formation visible in the night sky, and is home to both protoplanetary discs and very young stars. The nebula is bright in infrared wavelengths due to the heat-intensive processes involved in the stellar formation, though the complex contains dark nebulae, emission nebulae, reflection nebulae, and H II regions.

text: The nebula is important because of its sheer size, as it spreads several degrees from

text: Orion's Belt

text: to his sword.  It is also one of the most active regions of

text: stellar formation

text: visible in the night sky, and is home to both

text: protoplanetary discs

text: and very young

text: star

text: s. The nebula is bright in

text: infrared

text: wavelengths due to the heat-intensive processes involved in the stellar formation, though the complex contains

text: dark nebulae

text: emission nebulae

text: reflection nebula

text: e, and

text: H II region

text: s.

text: Six months after the Rock Raiders first discovered the alien galaxy, the Rock Raiders have returned to the planet, and possibly the other planets in the solar system. The planet has now been named Planet U, it is never said what the U stands for, but it is widely accepted that it means Uncharted or Unexplored. The Rock Raiders have now set up quadrants around the planet.

text: After this, the program adopts a serious tone as it profiles each of the planets in the Solar System, from the perspective of what would happen to a man on them. The program claims that whereas most of the planets are either too cold or too hot for life as we know it, life on Mars could almost be normal, something that is of increasing importance for the future. Dr. E.C. Slipher then discusses the Red Planet and the possibility that life is already there. More animation speculates what the conditions on Mars might be like. This section is filled with striking, inventive and atypical Disney animation.

text: After this, the program adopts a serious tone as it profiles each of the planets in the Solar System, from the perspective of what would happen to a man on them. The program claims that whereas most of the planets are either too cold or too hot for life as we know it, life on Mars could almost be normal, something that is of increasing importance for the future.

text: Dr. E.C. Slipher

text: then discusses the Red Planet and the possibility that life is already there. More animation speculates what the conditions on Mars might be like. This section is filled with striking, inventive and atypical Disney animation.

text: The red regions of this nebula are caused by hydrogen gas that has been stimulated to emit its own light by the copious ultraviolet radiation coming from the hot, blue stars of the cluster. The blue areas shine by a different process: they are mainly dust clouds that reflect the bluish light of the same stars.

text: The red regions of this nebula are caused by hydrogen gas that has been stimulated to emit its own light by the copious ultraviolet radiation coming from the hot, blue stars of the cluster. The blue areas shine by a different process: they are mainly dust clouds that reflect the bluish light of the same

text: star

text: s.

text: The Sun formed about 4.6 billion years ago from the collapse of part of a giant molecular cloud that consisted mostly of hydrogen and helium and that probably gave birth to many other stars. This age is estimated using computer models of stellar evolution and through nucleocosmochronology. The result is consistent with the radiometric date of the oldest Solar System material, at 4.567 billion years ago. Studies of ancient meteorites reveal traces of stable daughter nuclei of short-lived isotopes, such as iron-60, that form only in exploding, short-lived stars. This indicates that one or more supernovae must have occurred near the location where the Sun formed. A shock wave from a nearby supernova would have triggered the formation of the Sun by compressing the matter within the molecular cloud and causing certain regions to collapse under their own gravity. As one fragment of the cloud collapsed it also began to rotate because of conservation of angular momentum and heat up with the increasing pressure. Much of the mass became concentrated in the center, whereas the rest flattened out into a disk that would become the planets and other Solar System bodies. Gravity and pressure within the core of the cloud generated a lot of heat as it accreted more matter from the surrounding disk, eventually triggering nuclear fusion. Thus, the Sun was born.

text: The Sun formed about 4.6 billion years ago from the collapse of part of a giant

text: molecular cloud

text: that consisted mostly of hydrogen and helium and that probably gave birth to many other stars. This age is estimated using

text: computer models

text: of

text: stellar evolution

text: and through

text: nucleocosmochronology

text: . The result is consistent with the

text: radiometric date

text: of the oldest Solar System material, at 4.567 billion years ago. Studies of ancient

text: meteorite

text: s reveal traces of stable daughter nuclei of short-lived isotopes, such as

text: , that form only in exploding, short-lived stars. This indicates that one or more supernovae must have occurred near the location where the Sun formed. A

text: shock wave

text: from a nearby supernova would have triggered the formation of the Sun by compressing the matter within the molecular cloud and causing certain regions to collapse under their own gravity. As one fragment of the cloud collapsed it also began to rotate because of

text: conservation of angular momentum

text: and heat up with the increasing pressure. Much of the mass became concentrated in the center, whereas the rest flattened out into a disk that would become the planets and other Solar System bodies. Gravity and pressure within the core of the cloud generated a lot of heat as it accreted more matter from the surrounding disk, eventually triggering

text: nuclear fusion

text: . Thus, the Sun was born.

text: Solar heating systems are a well known second-generation technology and generally consist of solar thermal collectors, a fluid system to move the heat from the collector to its point of usage, and a reservoir or tank for heat storage and subsequent use. The systems may be used to heat domestic hot water, swimming pool water, or for space heating. The heat can also be used for industrial applications or as an energy input for other uses such as cooling equipment. In many climates, a solar heating system can provide a very high percentage (50 to 75%) of domestic hot water energy.Energy received from the sun by the earth is that of electromagnetic radiation. Light ranges of visible, infrared, ultraviolet, x-rays, and radio waves received by the earth through solar energy. The highest power of radiation comes from visible light. Solar power is complicated due to changes in seasons and from day to night. Cloud cover can also add to complications of solar energy, and not all radiation from the sun reaches earth because it is absorbed and dispersed due to clouds and gases within the earth's atmospheres.

text: Solar heating

text: systems are a well known second-generation technology and generally consist of solar thermal collectors, a fluid system to move the heat from the collector to its point of usage, and a reservoir or tank for heat storage and subsequent use. The systems may be used to heat domestic hot water, swimming pool water, or for space heating. The heat can also be used for industrial applications or as an energy input for other uses such as cooling equipment. In many climates, a solar heating system can provide a very high percentage (50 to 75%) of domestic hot water energy.Energy received from the sun by the earth is that of electromagnetic radiation. Light ranges of visible, infrared, ultraviolet, x-rays, and radio waves received by the earth through solar energy. The highest power of radiation comes from visible light. Solar power is complicated due to changes in seasons and from day to night. Cloud cover can also add to complications of solar energy, and not all radiation from the sun reaches earth because it is absorbed and dispersed due to clouds and gases within the earth's atmospheres.

text: Gravity is a function of mass. While the average value of Earth's surface gravity is approximately 9.8 meters per second squared, given sufficiently sensitive instrumentation, it is possible to detect local variations in gravity from the different densities of natural materials: the value of gravity will be greater on top of a granite monolith than over a sand beach. Again with sufficiently sensitive instrumentation, it should be possible to detect gravitational differences between solid rock, and rock excavated for a hidden facility.

text: Gravitational disruption from the outer planets' migration would have sent large numbers of asteroids into the inner Solar System, severely depleting the original belt until it reached today's extremely low mass. This event may have triggered the Late Heavy Bombardment that occurred approximately 4 billion years ago, 500–600 million years after the formation of the Solar System. This period of heavy bombardment lasted several hundred million years and is evident in the cratering still visible on geologically dead bodies of the inner Solar System such as the Moon and Mercury. The oldest known evidence for life on Earth dates to 3.8 billion years ago—almost immediately after the end of the Late Heavy Bombardment.

text: Gravitational disruption from the outer planets' migration would have sent large numbers of asteroids into the inner Solar System, severely depleting the original belt until it reached today's extremely low mass. This event may have triggered the Late Heavy Bombardment that occurred approximately 4 billion years ago, 500–600 million years after the formation of the Solar System. This period of heavy bombardment lasted several hundred million years and is evident in the cratering still visible on geologically dead bodies of the inner Solar System such as the Moon and Mercury. The oldest known evidence for

text: life on Earth

text: dates to 3.8 billion years ago—almost immediately after the end of the Late Heavy Bombardment.

text: The Parker spiral shape of the solar wind changes the shape of the Sun's magnetic field in the outer solar system: beyond about 10-20 astronomical units from the Sun, the magnetic field is nearly toroidal (pointed around the equator of the Sun) rather than poloidal (pointed from the North to the South pole, as in a bar magnet) or radial (pointed outward or inward, as might be expected from the flow of the solar wind if the Sun were not rotating).  The spiral shape also greatly amplifies the strength of the solar magnetic field in the outer solar system.

text: The Parker spiral shape of the solar wind changes the shape of the Sun's magnetic field in the outer solar system: beyond about 10-20

text: astronomical units

text: from the Sun, the magnetic field is nearly

text: toroid

text: al (pointed around the equator of the Sun) rather than

text: poloidal

text: (pointed from the North to the South pole, as in a bar magnet) or

text: radial

text: (pointed outward or inward, as might be expected from the flow of the solar wind if the Sun were not rotating).  The spiral shape also greatly amplifies the strength of the solar magnetic field in the outer solar system.

text: The Solar System travels alone through the Milky Way in a circular orbit approximately 30,000 light years from the Galactic Centre. Its speed is about 220 km/s. The period required for the Solar System to complete one revolution around the Galactic Centre, the galactic year, is in the range of 220–250 million years. Since its formation, the Solar System has completed at least 20 such revolutions.

text: The Solar System travels alone through the

text: Milky Way

text: in a circular orbit approximately 30,000 light years from the

text: Galactic Centre

text: . Its speed is about 220 km/s. The period required for the Solar System to complete one revolution around the Galactic Centre, the

text: galactic year

text: , is in the range of 220–250 million years. Since its formation, the Solar System has completed at least 20 such revolutions.

text: The Sun is the star at the center of the Solar System. It is a nearly perfect sphere of hot plasma, with internal convective motion that generates a magnetic field via a dynamo process. It is by far the most important source of energy for life on Earth. Its diameter is about 109 times that of Earth, and its mass is about 330,000 times that of Earth, accounting for about 99.86% of the total mass of the Solar System.About three quarters of the Sun's mass consists of hydrogen (~73%); the rest is mostly helium (~25%), with much smaller quantities of heavier elements, including oxygen, carbon, neon, and iron.

text: The Sun is the

text: star

text: at the center of the

text: Solar System

text: . It is a nearly perfect sphere of hot

text: plasma

text: , with internal

text: convective

text: motion that generates a

text: magnetic field

text: via a

text: dynamo process

text: . It is by far the most important source of

text: energy

text: for

text: life

text: on

text: Earth

text: . Its diameter is about 109 times that of Earth, and

text: its mass

text: is about 330,000 times that of Earth, accounting for about 99.86% of the total mass of the Solar System.About three quarters of the Sun's mass consists of

text: hydrogen

text: (~73%); the rest is mostly

text: helium

text: (~25%), with much smaller quantities of heavier elements, including

text: oxygen

text: carbon

text: neon

text: , and

text: iron

text: The Solar System's location in the Milky Way is a factor in the evolutionary history of life on Earth. Its orbit is close to circular, and orbits near the Sun are at roughly the same speed as that of the spiral arms. Therefore, the Sun passes through arms only rarely. Because spiral arms are home to a far larger concentration of supernovae, gravitational instabilities, and radiation that could disrupt the Solar System, this has given Earth long periods of stability for life to evolve. The Solar System also lies well outside the star-crowded environs of the galactic centre. Near the centre, gravitational tugs from nearby stars could perturb bodies in the Oort cloud and send many comets into the inner Solar System, producing collisions with potentially catastrophic implications for life on Earth. The intense radiation of the galactic centre could also interfere with the development of complex life. Even at the Solar System's current location, some scientists have speculated that recent supernovae may have adversely affected life in the last 35,000 years, by flinging pieces of expelled stellar core towards the Sun, as radioactive dust grains and larger, comet-like bodies.

text: The Solar System's location in the Milky Way is a factor in the

text: evolutionary history of life

text: on Earth. Its orbit is close to circular, and orbits near the Sun are at roughly the same speed as that of the spiral arms. Therefore, the Sun passes through arms only rarely. Because spiral arms are home to a far larger concentration of

text: supernova

text: e, gravitational instabilities, and radiation that could disrupt the Solar System, this has given Earth long periods of stability for life to evolve. The Solar System also lies well outside the star-crowded environs of the galactic centre. Near the centre, gravitational tugs from nearby stars could perturb bodies in the

text: Oort cloud

text: and send many comets into the inner Solar System, producing collisions with potentially catastrophic implications for life on Earth. The intense radiation of the galactic centre could also interfere with the development of complex life. Even at the Solar System's current location, some scientists have speculated that recent supernovae may have adversely affected life in the last 35,000 years, by flinging pieces of expelled stellar core towards the Sun, as radioactive dust grains and larger, comet-like bodies.

text: Venus may have formed from the solar nebula with a different rotation period and obliquity, reaching its current state because of chaotic spin changes caused by planetary perturbations and tidal effects on its dense atmosphere, a change that would have occurred over the course of billions of years. The rotation period of Venus may represent an equilibrium state between tidal locking to the Sun's gravitation, which tends to slow rotation, and an atmospheric tide created by solar heating of the thick Venusian atmosphere.The 584-day average interval between successive close approaches to Earth is almost exactly equal to 5 Venusian solar days, but the hypothesis of a spin–orbit resonance with Earth has been discounted.

text: Venus may have formed from the

text: solar nebula

text: with a different rotation period and obliquity, reaching its current state because of chaotic spin changes caused by planetary perturbations and

text: tidal

text: effects on its dense atmosphere, a change that would have occurred over the course of billions of years. The rotation period of Venus may represent an equilibrium state between tidal locking to the Sun's gravitation, which tends to slow rotation, and an atmospheric tide created by solar heating of the thick Venusian atmosphere.The 584-day average interval between successive close approaches to Earth is almost exactly equal to 5 Venusian solar days, but the hypothesis of a spin–orbit resonance with Earth has been discounted.

text: Planets may be treated in different ways depending both on the interests of the author and the genre he or she is writing in. In some stories, a planet is mainly considered as an object in space: the interest of the fiction depends upon its astronomical characteristics, such as its mass, its geological composition, its atmosphere, how many moons it has and what size they are, how close it is to its sun (or suns) and how hot they are. Such considerations are found prominently though not exclusively in the hard science fiction genre.

text: Planets may be treated in different ways depending both on the interests of the author and the genre he or she is writing in. In some stories, a planet is mainly considered as an object in space: the interest of the fiction depends upon its astronomical characteristics, such as its mass, its geological composition, its atmosphere, how many moons it has and what size they are, how close it is to its sun (or suns) and how hot they are. Such considerations are found prominently though not exclusively in the

text: hard science fiction

text: genre.

text: Jumps are normally made to and from points far above a solar system's ecliptic, usually where the gravitational influence in the system is most stable; however, so-called "pirate points" exist where local gravitational pull is stable enough to use; though quicker, using such points is also more dangerous due to the random appearance of so-called "Lagrange points".  Jumping requires copious amounts of energy, usually gathered from the nearby star over the course of approximately a week by large solar collectors similar to solar sails and stored in giant capacitors.  A quicker but less common technique is to draw the energy from a fusion reactor, or to take advantage of recharge stations in the vicinity of major jump points.  Jump failures can result from charging the drive too quickly, poor drive maintenance or spatial anomalies.

text: Jumps are normally made to and from points far above a solar system's

text: ecliptic

text: , usually where the gravitational influence in the system is most stable; however, so-called "pirate points" exist where local gravitational pull is stable enough to use; though quicker, using such points is also more dangerous due to the random appearance of so-called "Lagrange points".  Jumping requires copious amounts of energy, usually gathered from the nearby star over the course of approximately a week by large solar collectors similar to

text: solar sails

text: and stored in giant capacitors.  A quicker but less common technique is to draw the energy from a fusion reactor, or to take advantage of recharge stations in the vicinity of major jump points.  Jump failures can result from charging the drive too quickly, poor drive maintenance or spatial anomalies.

text: Observed Solar System objects that periodically become more distant than 103 AU from the Sun include Sedna (which is similar or modestly larger in size), , , , and . There are 595 known objects that have aphelia more than 103 AU from the Sun. This distance is about double the outer limit of the torus-shaped Kuiper belt that lies outside Neptune's orbit. Far beyond this region is the vast spherical Oort cloud enshrouding the Solar System, whose presence was deduced from the orbits of long-period comets.

text: Observed Solar System objects that periodically become more distant than 103 AU from the Sun include

text: Sedna

text: (which is similar or modestly larger in size), , , , and . There are 595 known objects that have aphelia more than 103 AU from the Sun. This distance is about double the outer limit of the torus-shaped

text: Kuiper belt

text: that lies outside Neptune's orbit. Far beyond this region is the vast spherical

text: Oort cloud

text: enshrouding the Solar System, whose presence was deduced from the orbits of long-period comets.

text: Meanwhile, scientists have realized that the sun is losing energy but not mass to the Sun-Eater. This will cause the sun to nova, and the explosion will catapult the Sun-Eater into another solar system where it will consume another sun. The assembled heroes construct a technological means of destroying the Sun-Eater. Lex Luthor angrily bows out of piloting the ship needed, revealing that he was in it simply to save his own skin, prompting Superman to volunteer in the hope that his powers will be restored by the solar surge as the sun is restored. Ferro Lad steals the ship, only to be shunted back to Earth by Hal Jordan, the former Green Lantern then known as Parallax. Parallax sacrifices his life to absorb the Sun-Eater and reignite the sun, simultaneously using his powers to safely restore it to its original form without causing any side-effects such as the mass flooding that would have resulted if the sun had been restored purely by Luthor's plan.

text: Meanwhile, scientists have realized that the sun is losing energy but not mass to the Sun-Eater. This will cause the sun to

text: nova

text: , and the explosion will catapult the Sun-Eater into another solar system where it will consume another sun. The assembled heroes construct a technological means of destroying the Sun-Eater. Lex Luthor angrily bows out of piloting the ship needed, revealing that he was in it simply to save his own skin, prompting Superman to volunteer in the hope that his powers will be restored by the solar surge as the sun is restored. Ferro Lad steals the ship, only to be shunted back to Earth by

text: Hal Jordan

text: , the former

text: Green Lantern

text: then known as

text: Parallax

text: . Parallax sacrifices his life to absorb the Sun-Eater and reignite the sun, simultaneously using his powers to safely restore it to its original form without causing any side-effects such as the mass flooding that would have resulted if the sun had been restored purely by Luthor's plan.

text: The possibility of extraterrestrial life on the Moon was ruled out in the 1960s, and during the 1970s it became clear that most of the other bodies of the Solar System do not harbor highly developed life, although the question of primitive life on bodies in the Solar System remains an open question.

text: Distant Wanderers: The Search for Planets Beyond the Solar System is a book, written by Dorminey, which reports on astronomical research and theory related to the search for extrasolar planets, as of the publication date of 2001. It received reviews from publications including Astronomy magazine,  USA Today, and New Scientist

text: Distant Wanderers: The Search for Planets Beyond the Solar System is a book, written by Dorminey, which reports on astronomical research and theory related to the search for

text: extrasolar planets

text: , as of the publication date of 2001. It received reviews from publications including

text: Astronomy magazine

text: USA Today

text: , and

text: New Scientist

text: For values of e from 0 to 1 the orbit's shape is an increasingly elongated (or flatter) ellipse; for values of e from 1 to infinity the orbit is a hyperbola branch making a total turn of , decreasing from 180 to 0 degrees. The limit case between an ellipse and a hyperbola, when e  equals 1, is parabola.

text: There are types of planets that do not exist in the Solar System: super-Earths and mini-Neptunes, which could be rocky like Earth or a mixture of volatiles and gas like Neptune—a radius of 1.75 times that of Earth is a possible dividing line between the two types of planet. There are hot Jupiters that orbit very close to their star and may evaporate to become chthonian planets, which are the leftover cores. Another possible type of planet is carbon planets, which form in systems with a higher proportion of carbon than in the Solar System.

text: There are types of planets that do not exist in the Solar System:

text: super-Earth

text: s and

text: mini-Neptune

text: s, which could be rocky like Earth or a mixture of volatiles and gas like Neptune—a radius of 1.75 times that of Earth is a possible dividing line between the two types of planet. There are

text: hot Jupiter

text: s that orbit very close to their star and may evaporate to become

text: chthonian planet

text: s, which are the leftover cores. Another possible type of planet is

text: carbon planet

text: s, which form in systems with a higher proportion of carbon than in the Solar System.

text: Pan-STARRS may detect interstellar objects passing through the Solar System. During the formation of a planetary system, it is thought that a very large number of objects are ejected due to gravitational interactions with planets (as many as 10 such objects in the case of the Solar System). Objects ejected from planetary systems of other stars might plausibly be throughout the Milky Way and some may pass through the Solar System.

text: Pan-STARRS may detect

text: interstellar objects

text: passing through the Solar System. During the formation of a planetary system, it is thought that a very large number of objects are ejected due to gravitational interactions with planets (as many as 10 such objects in the case of the Solar System). Objects ejected from planetary systems of other stars might plausibly be throughout the Milky Way and some may pass through the Solar System.

text: Newton made clear his heliocentric view of the Solar System—developed in a somewhat modern way, because already in the mid-1680s he recognised the "deviation of the Sun" from the centre of gravity of the Solar System. For Newton, it was not precisely the centre of the Sun or any other body that could be considered at rest, but rather "the common centre of gravity of the Earth, the Sun and all the Planets is to be esteem'd the Centre of the World", and this centre of gravity "either is at rest or moves uniformly forward in a right line" (Newton adopted the "at rest" alternative in view of common consent that the centre, wherever it was, was at rest).

text: Newton made clear his

text: heliocentric

text: view of the Solar System—developed in a somewhat modern way, because already in the mid-1680s he recognised the "deviation of the Sun" from the centre of gravity of the Solar System. For Newton, it was not precisely the centre of the Sun or any other body that could be considered at rest, but rather "the common centre of gravity of the Earth, the Sun and all the Planets is to be esteem'd the Centre of the World", and this centre of gravity "either is at rest or moves uniformly forward in a right line" (Newton adopted the "at rest" alternative in view of common consent that the centre, wherever it was, was at rest).

text: His work as planetary scientist changed the view of the solar system revolutionizing the way orbital and collisional histories of asteroids are seen.He used his ideas in many fields of the space science that can be summarized in the following activities:

text: In fact, according to the Duhem–Quine thesis, after Pierre Duhem and W. V. Quine, it is impossible to test a theory in isolation.  One must always add auxiliary hypotheses in order to make testable predictions. For example, to test Newton's Law of Gravitation in the solar system, one needs information about the masses and positions of the Sun and all the planets.  Famously, the failure to predict the orbit of Uranus in the 19th century led not to the rejection of Newton's Law but rather to the rejection of the hypothesis that the solar system comprises only seven planets. The investigations that followed led to the discovery of an eighth planet, Neptune. If a test fails, something is wrong. But there is a problem in figuring out what that something is: a missing planet, badly calibrated test equipment, an unsuspected curvature of space, or something else.

text: In fact, according to the

text: Duhem–Quine thesis

text: , after

text: Pierre Duhem

text: and

text: W. V. Quine

text: , it is impossible to test a theory in isolation.  One must always add auxiliary hypotheses in order to make testable predictions. For example, to test

text: Newton's Law of Gravitation

text: in the solar system, one needs information about the masses and positions of the Sun and all the planets.  Famously, the failure to predict the orbit of

text: Uranus

text: in the 19th century led not to the rejection of Newton's Law but rather to the rejection of the hypothesis that the solar system comprises only seven planets. The investigations that followed led to the discovery of an eighth planet,

text: Neptune

text: . If a test fails, something is wrong. But there is a problem in figuring out what that something is: a missing planet, badly calibrated test equipment, an unsuspected curvature of space, or something else.

text: As seen from Earth, all the other planets, asteroids and all objects in the Solar System appear to periodically switch direction as they cross the sky. Though all stars and planets appear to move from east to west on a nightly basis in response to the rotation of Earth, the outer planets generally drift slowly eastward relative to the stars. Asteroids and Kuiper Belt Objects (including Pluto) exhibit apparent retrogradation. This motion is normal for the planets, and so is considered direct motion.  However, since Earth completes its orbit in a shorter period of time than the planets outside its orbit, it periodically overtakes them, like a faster car on a multi-lane highway. When this occurs, the planet being passed will first appear to stop its eastward drift, and then drift back toward the west. Then, as Earth swings past the planet in its orbit, it appears to resume its normal motion west to east. Inner planets Venus and Mercury appear to move in retrograde in a similar mechanism, but as they can never be in opposition to the Sun as seen from Earth, their retrograde cycles are tied to their inferior conjunctions with the Sun. They are unobservable in the Sun's glare and in their "new" phase, with mostly their dark sides toward Earth; they occur in the transition from morning star to evening star.

text: As seen from Earth, all the other planets, asteroids and all objects in the Solar System appear to periodically switch direction as they cross the sky. Though all stars and planets appear to move from east to west on a nightly basis in response to the rotation of Earth, the outer planets generally drift slowly eastward relative to the stars.

text: Asteroids

text: and

text: Kuiper Belt

text: Objects (including

text: Pluto

text: ) exhibit apparent retrogradation. This motion is normal for the planets, and so is considered direct motion.  However, since Earth completes its orbit in a shorter period of time than the planets outside its orbit, it periodically overtakes them, like a faster car on a multi-lane highway. When this occurs, the planet being passed will first appear to stop its eastward drift, and then drift back toward the west. Then, as Earth swings past the planet in its orbit, it appears to resume its normal motion west to east. Inner planets

text: Venus

text: and

text: Mercury

text: appear to move in retrograde in a similar mechanism, but as they can never be

text: in opposition

text: to the Sun as seen from Earth, their retrograde cycles are tied to their inferior conjunctions with the

text: Sun

text: . They are unobservable in the Sun's glare and in their "new" phase, with mostly their dark sides toward Earth; they occur in the transition from morning star to evening star.

text: The outer region of the Solar System is home to the giant planets and their large moons. The centaurs and many short-period comets also orbit in this region. Due to their greater distance from the Sun, the solid objects in the outer Solar System contain a higher proportion of volatiles, such as water, ammonia, and methane than those of the inner Solar System because the lower temperatures allow these compounds to remain solid.

text: The outer region of the Solar System is home to the

text: giant planet

text: s and their large moons. The

text: centaurs

text: and many

text: short-period comet

text: s also orbit in this region. Due to their greater distance from the Sun, the solid objects in the outer Solar System contain a higher proportion of volatiles, such as water, ammonia, and methane than those of the inner Solar System because the lower temperatures allow these compounds to remain solid.

text: Ideas concerning the origin and fate of the world date from the earliest known writings; however, for almost all of that time, there was no attempt to link such theories to the existence of a "Solar System", simply because it was not generally thought that the Solar System, in the sense we now understand it, existed. The first step toward a theory of Solar System formation and evolution was the general acceptance of heliocentrism, which placed the Sun at the centre of the system and the Earth in orbit around it. This concept had developed for millennia (Aristarchus of Samos had suggested it as early as 250 BC), but was not widely accepted until the end of the 17th century. The first recorded use of the term "Solar System" dates from 1704.

text: Ideas concerning the origin and fate of the world date from the earliest known writings; however, for almost all of that time, there was no attempt to link such theories to the existence of a "Solar System", simply because it was not generally thought that the Solar System, in the sense we now understand it, existed. The first step toward a theory of Solar System formation and evolution was the general acceptance of

text: heliocentrism

text: , which placed the Sun at the centre of the system and the

text: Earth

text: in orbit around it. This concept had developed for millennia (

text: Aristarchus of Samos

text: had suggested it as early as 250 BC), but was not widely accepted until the end of the 17th century. The first recorded use of the term "Solar System" dates from 1704.

text: The objectives of this task deal with the advancement of technical and economic viability of emerging solar thermal technologies and their validation with suitable tools by proper theoretical analyses and simulation codes as well as by experiments in special arrangements and adapted facilities. For this purpose, procedures and techniques are defined for the design, evaluation and use of the components and subsystems to optimize concentration, reception, transfer, storage and application of solar thermal energy. In essence, the goals are to investigate innovative multi-discipline advances needed for the further development of concentrating solar thermal systems. This also concerns, among others, process heat applications, the utilization of solar concentration for the development of improved materials, and the introduction of hybrid solar/fossil power plant concepts.

text: Although the sizes of comets are difficult to determine without close observation, Comet Elenin is likely to be less than 10 km in diameter. Elenin himself estimates that the comet nucleus is roughly 3–4 km in diameter. This would make it millions of times smaller than the supposed Nibiru. Comet hysteria is not uncommon. Attempts have been made to correlate Elenin's alignments with the 2011 Japan earthquake, the 2010 Canterbury earthquake, and 2010 Chile earthquake; however, even discounting Elenin's tiny size, earthquakes are driven by forces within the earth, and cannot be triggered by the passage of nearby objects. In 2011, Leonid Elenin ran a simulation on his blog in which he increased the mass of the comet to that of a brown dwarf (0.05 solar masses). He demonstrated that its gravity would have caused noticeable changes in the orbit of Saturn years before its arrival in the inner Solar System.

text: Although the sizes of comets are difficult to determine without close observation, Comet Elenin is likely to be less than 10 km in diameter. Elenin himself estimates that the

text: comet nucleus

text: is roughly 3–4 km in diameter. This would make it millions of times smaller than the supposed Nibiru. Comet hysteria is not uncommon. Attempts have been made to correlate Elenin's alignments with the

text: 2011 Japan earthquake

text: , the

text: 2010 Canterbury earthquake

text: , and

text: 2010 Chile earthquake

text: ; however, even discounting Elenin's tiny size, earthquakes are driven by forces within the earth, and cannot be triggered by the passage of nearby objects. In 2011, Leonid Elenin ran a simulation on his blog in which he increased the mass of the comet to that of a brown dwarf (0.05 solar masses). He demonstrated that its gravity would have caused noticeable changes in the orbit of Saturn years before its arrival in the inner Solar System.

text: For centuries philosophers and scientists suspected that extrasolar planets existed, but there was no way of detecting them or of knowing their frequency or how similar they might be to the planets of the Solar System. Various detection claims made in the nineteenth century were rejected by astronomers. The first confirmed detection came in 1992, with the discovery of several terrestrial-mass planets orbiting the pulsar PSR B1257+12. The first confirmation of an exoplanet orbiting a main-sequence star was made in 1995, when a giant planet was found in a four-day orbit around the nearby star 51 Pegasi. Some exoplanets have been imaged directly by telescopes, but the vast majority have been detected through indirect methods such as the transit method and the radial-velocity method.

text: For centuries philosophers and scientists suspected that extrasolar planets existed, but there was no way of detecting them or of knowing their frequency or how similar they might be to the planets of the

text: Solar System

text: . Various detection claims made in the nineteenth century were rejected by astronomers. The first confirmed detection came in 1992, with the discovery of several terrestrial-mass planets orbiting the

text: pulsar

text: PSR B1257+12

text: . The first confirmation of an exoplanet orbiting a

text: main-sequence

text: star was made in 1995, when a giant planet was found in a four-day orbit around the nearby star

text: 51 Pegasi

text: . Some exoplanets have been

text: imaged directly

text: by telescopes, but the vast majority have been detected through indirect methods such as the

text: transit method

text: and the

text: radial-velocity method

text: Vulcanoids, being an entirely new class of celestial bodies, would be interesting in their own right, but discovering whether or not they exist would yield insights into the formation and evolution of the Solar System. If they exist they might contain material left over from the earliest period of planet formation, and help determine the conditions under which the terrestrial planets, particularly Mercury, formed. In particular, if vulcanoids exist or did exist in the past, they would represent an additional population of impactors that have affected no other planet but Mercury, making that planet's surface appear older than it actually is. If vulcanoids are found not to exist, this would place different constraints on planet formation and suggest that other processes have been at work in the inner Solar System, such as planetary migration clearing out the area.

text: Vulcanoids, being an entirely new class of celestial bodies, would be interesting in their own right, but discovering whether or not they exist would yield insights into the

text: . If they exist they might contain material left over from the earliest period of planet formation, and help determine the conditions under which the

text: terrestrial planets

text: , particularly Mercury, formed. In particular, if vulcanoids exist or did exist in the past, they would represent an additional population of impactors that have affected no other planet but Mercury, making that planet's surface appear older than it actually is. If vulcanoids are found not to exist, this would place different constraints on planet formation and suggest that other processes have been at work in the inner Solar System, such as

text: planetary migration

text: clearing out the area.

text: What is "typical" for a binary system tends to depend on its location in the Solar System (presumably because of different modes of origin and lifetimes of such systems in different populations of minor planets).

text: Within the solar system, space weather is influenced by the solar wind and the interplanetary magnetic field (IMF) carried by the solar wind plasma. A variety of physical phenomena are associated with space weather, including geomagnetic storms and substorms, energization of the Van Allen radiation belts, ionospheric disturbances and scintillation of satellite-to-ground radio signals and long-range radar signals, aurora and geomagnetically induced currents at Earth's surface. Coronal mass ejections and their associated shock waves are also important drivers of space weather as they can compress the magnetosphere and trigger geomagnetic storms. Solar energetic particles (SEP), accelerated by coronal mass ejections or solar flares, are also an important driver of space weather as they can damage electronics onboard spacecraft (e.g. Galaxy 15 failure), and threaten the lives of astronauts.

text: Within the

text: solar system

text: , space weather is influenced by the

text: solar wind

text: and the

text: interplanetary magnetic field

text: (IMF) carried by the solar wind

text: plasma

text: . A variety of physical phenomena are associated with space weather, including

text: geomagnetic storm

text: s and substorms, energization of the

text: Van Allen radiation belt

text: s, ionospheric disturbances and

text: scintillation

text: of satellite-to-ground radio signals and long-range radar signals,

text: aurora

text: and

text: geomagnetically induced current

text: s at Earth's surface.

text: Coronal mass ejection

text: s and their associated

text: shock wave

text: s are also important drivers of space weather as they can compress the

text: magnetosphere

text: and trigger

text: geomagnetic storm

text: s.

text: Solar energetic particles

text: (SEP), accelerated by coronal mass ejections or

text: solar flare

text: s, are also an important driver of space weather as they can damage electronics onboard spacecraft (e.g.

text: Galaxy 15

text: failure), and threaten the lives of

text: astronaut

text: s.

text: The following is a list of parabolic and hyperbolic comets in the Solar System. Many of these comets may come from the Oort cloud, or perhaps even have interstellar origin. Due to the Oort Cloud not being gravitationally attracted enough to the Sun to form into a fairly thin disk, like the inner Solar System, comets originating from it can come from roughly any orientation, and many even orbit retrograde. By definition, a hyperbolic orbit means that the comet will only travel through the Solar System once, with the Sun acting as a gravitational slingshot, sending the comet hurtling out of the Solar System entirely unless its eccentricity is otherwise changed. Comets orbiting in this way still originate from the Solar System, however. Typically comets in the Oort Cloud are thought to have roughly circular orbits around the Sun, but their orbital velocity is so slow that they are easily perturbed by passing stars and the galactic tide.

text: The following is a list of

text: parabolic

text: and

text: hyperbolic

text: comet

text: s in the Solar System. Many of these comets may come from the

text: Oort cloud

text: , or perhaps even have

text: interstellar

text: origin. Due to the Oort Cloud not being gravitationally attracted enough to the Sun to form into a fairly thin disk, like the inner Solar System, comets originating from it can come from roughly any orientation, and many even orbit

text: retrograde

text: . By definition, a hyperbolic orbit means that the comet will only travel through the Solar System once, with the Sun acting as a gravitational slingshot, sending the comet hurtling out of the Solar System entirely unless its

text: eccentricity

text: is otherwise changed. Comets orbiting in this way still originate from the Solar System, however. Typically comets in the Oort Cloud are thought to have roughly circular orbits around the Sun, but their orbital velocity is so slow that they are easily perturbed by

text: passing stars

text: and the

text: galactic tide

text: A certain type of meteorites, CI-chondrites, have a chemical composition that is almost identical to the solar photosphere, except for the abundances of volatile elements. Because the Sun contains 99.86% of the mass of the Solar System, they are considered to have the same composition as the solar nebula with the exception of volatile loss and are therefore representative of the material from which the terrestrial planets, including the Earth, were formed.

text: A certain type of meteorites,

text: CI-chondrites

text: , have a chemical composition that is almost identical to the solar

text: photosphere

text: , except for the abundances of volatile elements. Because the Sun contains 99.86% of the mass of the Solar System, they are considered to have the same composition as the solar nebula with the exception of volatile loss and are therefore representative of the material from which the terrestrial planets, including the Earth, were formed.

text: Earth – third planet from the Sun, the densest planet in the Solar System, the largest of the Solar System's four terrestrial planets, and the only astronomical object known to harbor life.

text: Earth

text: – third planet from the

text: Sun

text: , the densest planet in the

text: Solar System

text: , the largest of the Solar System's four

text: terrestrial planet

text: s, and the only

text: astronomical object

text: known to harbor

text: life

text: Isaac Newton demonstrated that Kepler's laws were derivable from his theory of gravitation and that, in general, the orbits of bodies subject to gravity were conic sections (this assumes that the force of gravity propagates instantaneously). Newton showed that, for a pair of bodies, the orbits' sizes are in inverse proportion to their masses, and that those bodies orbit their common center of mass. Where one body is much more massive than the other (as is the case of an artificial satellite orbiting a planet), it is a convenient approximation to take the center of mass as coinciding with the center of the more massive body.

text: Isaac Newton

text: demonstrated that Kepler's laws were derivable from his theory of

text: gravitation

text: and that, in general, the orbits of bodies subject to gravity were

text: conic section

text: s (this assumes that the force of gravity propagates instantaneously). Newton showed that, for a pair of bodies, the orbits' sizes are in inverse proportion to their

text: mass

text: es, and that those bodies orbit their common

text: center of mass

text: . Where one body is much more massive than the other (as is the case of an artificial satellite orbiting a planet), it is a convenient approximation to take the center of mass as coinciding with the center of the more massive body.

text: The large amount of CO in the atmosphere together with water vapour and sulfur dioxide create a strong greenhouse effect, trapping solar energy and raising the surface temperature to around 740 K (467 °C), hotter than any other planet in the Solar System, even that of Mercury despite being located farther out from the Sun and receiving only 25% of the solar energy (per unit area) Mercury does. The average temperature on the surface is above the melting points of lead (600 K, 327 °C), tin (505 K, 232 °C), and zinc (693 K, 420 °C). The thick troposphere also makes the difference in temperature between the day and night side small, even though the slow retrograde rotation of the planet causes a single solar day to last 116.5 Earth days. The surface of Venus spends 58.3 days of darkness before the sun rises again behind the clouds.

text: The large amount of CO in the atmosphere together with water vapour and

text: sulfur dioxide

text: create a strong

text: greenhouse effect

text: , trapping solar energy and raising the surface temperature to around 740 K (467 °C), hotter than any other planet in the

text: Solar System

text: , even that of

text: Mercury

text: despite being located farther out from the Sun and receiving only 25% of the solar energy (per unit area) Mercury does. The average temperature on the surface is above the melting points of

text: lead

text: (600 K, 327 °C),

text: tin

text: (505 K, 232 °C), and

text: zinc

text: (693 K, 420 °C). The thick troposphere also makes the difference in temperature between the day and night side small, even though the slow

text: retrograde

text: rotation of the planet causes a single solar day to last 116.5 Earth days. The surface of Venus spends 58.3 days of darkness before the sun rises again behind the clouds.

text: Zodiacal light is produced by sunlight reflecting off dust particles in the Solar System known as cosmic dust. Consequently, its spectrum is the same as the solar spectrum. The material producing the zodiacal light is located in a lens-shaped volume of space centered on the sun and extending well out beyond the orbit of Earth. This material is known as the interplanetary dust cloud. Since most of the material is located near the plane of the Solar System, the zodiacal light is seen along the ecliptic. The amount of material needed to produce the observed zodiacal light is quite small. If it were in the form of 1 mm particles, each with the same albedo (reflecting power) as Earth's moon, each particle would be 8 km from its neighbors. The gegenschein may be caused by particles directly opposite the Sun as seen from Earth would be in full phase.

text: Zodiacal light is produced by sunlight reflecting off dust particles in the Solar System known as

text: cosmic dust

text: . Consequently, its

text: spectrum

text: is the same as the

text: solar

text: spectrum. The material producing the zodiacal light is located in a lens-shaped volume of space centered on the sun and extending well out beyond the

text: orbit

text: of Earth. This material is known as the

text: interplanetary dust cloud

text: . Since most of the material is located near the plane of the Solar System, the zodiacal light is seen along the ecliptic. The amount of material needed to produce the observed zodiacal light is quite small. If it were in the form of 1 mm particles, each with the same

text: albedo

text: (reflecting power) as Earth's

text: moon

text: , each particle would be 8 km from its neighbors. The

text: gegenschein

text: may be caused by particles directly opposite the Sun as seen from Earth would be in full

text: phase

text: Brown thinks that no matter where it is speculated to be, if Planet Nine exists, then its mass is higher than what is required to clear its feeding zone in 4.6 billion years, and thus that it dominates the outer edge of the Solar System, which is sufficient to make it a planet by current definitions. Using a metric based on work by Jean-Luc Margot, Brown calculated that only at the smallest size and farthest distance was it on the border of being called a dwarf planet. Margot himself says that Planet Nine satisfies the quantitative criterion for orbit-clearing developed by him in 2015, and that according to that criterion, Planet Nine will qualify as a planet—if and when it is detected.

text: Brown thinks that no matter where it is speculated to be, if Planet Nine exists, then its mass is higher than what is required to

text: clear its feeding zone

text: in 4.6 billion years, and thus that it dominates the outer edge of the Solar System, which is sufficient to make it a

text: planet by current definitions

text: . Using a metric based on work by

text: Jean-Luc Margot

text: , Brown calculated that only at the smallest size and farthest distance was it on the border of being called a dwarf planet. Margot himself says that Planet Nine satisfies the quantitative criterion for orbit-clearing developed by him in 2015, and that according to that criterion, Planet Nine will qualify as a planet—if and when it is detected.

text: T Tauri stars like the young Sun have far stronger stellar winds than more stable, older stars. Uranus and Neptune are thought to have formed after Jupiter and Saturn did, when the strong solar wind had blown away much of the disc material. As a result, the planets accumulated little hydrogen and helium—not more than  each. Uranus and Neptune are sometimes referred to as failed cores. The main problem with formation theories for these planets is the timescale of their formation. At the current locations it would have taken a hundred million years for their cores to accrete. This means that Uranus and Neptune probably formed closer to the Sun—near or even between Jupiter and Saturn—and later migrated or were ejected outward (see Planetary migration below). Motion in the planetesimal era was not all inward toward the Sun; the Stardust sample return from Comet Wild 2 has suggested that materials from the early formation of the Solar System migrated from the warmer inner Solar System to the region of the Kuiper belt.

text: T Tauri stars like the young Sun have far stronger

text: stellar wind

text: s than more stable, older stars. Uranus and Neptune are thought to have formed after Jupiter and Saturn did, when the strong

text: solar wind

text: had blown away much of the disc material. As a result, the planets accumulated little hydrogen and helium—not more than  each. Uranus and Neptune are sometimes referred to as failed cores. The main problem with formation theories for these planets is the timescale of their formation. At the current locations it would have taken a hundred million years for their cores to accrete. This means that Uranus and Neptune probably formed closer to the Sun—near or even between Jupiter and Saturn—and later migrated or were ejected outward (see

text: Planetary migration

text: below). Motion in the planetesimal era was not all inward toward the Sun; the

text: Stardust

text: sample return from

text: Comet Wild 2

text: has suggested that materials from the early formation of the Solar System migrated from the warmer inner Solar System to the region of the Kuiper belt.

text: The IAU's working definition is not always used. One alternate suggestion is that planets should be distinguished from brown dwarfs on the basis of formation. It is widely thought that giant planets form through core accretion, which may sometimes produce planets with masses above the deuterium fusion threshold; massive planets of that sort may have already been observed. Brown dwarfs form like stars from the direct collapse of clouds of gas and this formation mechanism also produces objects that are below the  limit and can be as low as . Objects in this mass range that orbit their stars with wide separations of hundreds or thousands of AU and have large star/object mass ratios likely formed as brown dwarfs; their atmospheres would likely have a composition more similar to their host star than accretion-formed planets which would contain increased abundances of heavier elements. Most directly imaged planets as of April 2014 are massive and have wide orbits so probably represent the low-mass end of brown dwarf formation.

text: The

text: IAU

text: 's working definition is not always used. One alternate suggestion is that planets should be distinguished from

text: brown dwarf

text: s on the basis of formation. It is widely thought that giant planets form through core

text: accretion

text: , which may sometimes produce planets with masses above the deuterium fusion threshold; massive planets of that sort may have already been observed. Brown dwarfs form like stars from the direct collapse of clouds of gas and this formation mechanism also produces objects that are below the  limit and can be as low as . Objects in this mass range that orbit their stars with wide separations of hundreds or thousands of AU and have large star/object mass ratios likely formed as brown dwarfs; their atmospheres would likely have a composition more similar to their host star than accretion-formed planets which would contain increased abundances of heavier elements. Most directly imaged planets as of April 2014 are massive and have wide orbits so probably represent the low-mass end of brown dwarf formation.

text: It is thought that, during the Solar System's formation, Mars was created as the result of a stochastic process of run-away accretion of material from the protoplanetary disk that orbited the Sun. Mars has many distinctive chemical features caused by its position in the Solar System. Elements with comparatively low boiling points, such as chlorine, phosphorus, and sulphur, are much more common on Mars than Earth; these elements were probably pushed outward by the young Sun's energetic solar wind.

text: It is thought that, during the

text: Solar System's formation

text: , Mars was created as the result of a

text: stochastic process

text: of run-away accretion of material from the

text: protoplanetary disk

text: that orbited the Sun. Mars has many distinctive chemical features caused by its position in the Solar System. Elements with comparatively low boiling points, such as

text: chlorine

text: phosphorus

text: , and

text: sulphur

text: , are much more common on Mars than Earth; these elements were probably pushed outward by the young Sun's energetic

text: solar wind

text: Uranus is the third largest (Neptune has a larger mass, but a smaller volume) planet in the Solar System. It orbits the Sun at a distance of about 2.8 billion kilometers (1.7 billion miles), and it completes one orbit every 84 Earth years. The length of a day on Uranus as measured by Voyager 2 is 17 hours, 14 minutes. Uranus is unique among the planets in that its axial tilt is about 90°, meaning that its axis is roughly parallel with, not perpendicular to, the plane of the ecliptic. This extremely large tilt of its axis is thought to be the result of a collision between the accumulating planet Uranus with another planet-sized body early in the history of the Solar System. Given the unusual orientation of its axis, with the polar regions of Uranus exposed for periods of many years to either continuous sunlight or darkness, planetary scientists were not at all sure what to expect when observing Uranus.

text: Uranus

text: is the third largest (Neptune has a larger mass, but a smaller volume) planet in the Solar System. It orbits the Sun at a distance of about 2.8 billion kilometers (1.7 billion miles), and it completes one orbit every 84 Earth years. The length of a day on Uranus as measured by Voyager 2 is 17 hours, 14 minutes. Uranus is unique among the planets in that its axial tilt is about 90°, meaning that its axis is roughly parallel with, not perpendicular to, the

text: plane of the ecliptic

text: . This extremely large tilt of its axis is thought to be the result of a collision between the accumulating planet Uranus with another planet-sized body early in the history of the Solar System. Given the unusual orientation of its axis, with the polar regions of Uranus exposed for periods of many years to either continuous sunlight or darkness, planetary scientists were not at all sure what to expect when observing Uranus.

text: Solar systems based on CPV technology focus and magnify sunlight onto a small area of PV materials to produce energy. CPV systems use fewer material resources than traditional solar systems in an attempt to lower solar energy production costs. The end goal for the solar industry is to achieve grid parity, so that the cost of solar energy is on par, or below, the cost of energy from traditional fossil fuels.

text: Solar systems based on CPV technology focus and magnify sunlight onto a small area of PV materials to produce energy. CPV systems use fewer material resources than traditional solar systems in an attempt to lower solar energy production costs. The end goal for the solar industry is to achieve

text: grid parity

text: , so that the cost of solar energy is on par, or below, the cost of energy from traditional fossil fuels.

text: The initial presentation of this planet occurred at a meeting of the American Astronomical Society in April 2005, however it was another two and a half years before the planet was to be published in a peer-reviewed journal.  It is the first known planet outside our solar system to spend its entire orbit within what astronomers call the "habitable zone".  Furthermore, its discovery made 55 Cancri the first star other than the Sun known to have at least five planets.

text: The initial presentation of this planet occurred at a meeting of the

text: American Astronomical Society

text: in April 2005, however it was another two and a half years before the planet was to be published in a peer-reviewed journal.  It is the first known planet outside our solar system to spend its entire orbit within what astronomers call the "

text: habitable zone

text: ".  Furthermore, its discovery made

text: 55 Cancri

text: the first star other than the

text: Sun

text: known to have at least five planets.

text: Solar insolation is made up of direct, diffuse, and reflected radiation. The absorption factor of a PV cell is deﬁned as the fraction of incident solar irradiance that is absorbed by the cell. At high noon on a cloudless day at the equator, the power of the sun is about 1 kW/m², on the Earth's surface, to a plane that is perpendicular to the sun's rays. As such, PV arrays can track the sun through each day to greatly enhance energy collection. However, tracking devices add cost, and require maintenance, so it is more common for PV arrays to have fixed mounts that tilt the array and face solar noon (approximately due south in the Northern Hemisphere or due north in the Southern Hemisphere). The tilt angle, from horizontal, can be varied for season, but if fixed, should be set to give optimal array output during the peak electrical demand portion of a typical year for a stand-alone system. This optimal module tilt angle is not necessarily identical to the tilt angle for maximum annual array energy output. The optimization of the a photovoltaic system for a specific environment can be complicated as issues of solar flux, soiling, and snow losses should be taken into effect. In addition, recent work has shown that spectral effects can play a role in optimal photovoltaic material selection. For example, the spectral albedo can play a significant role in output depending on the surface around the photovoltaic system  and the type of solar cell material. For the weather and latitudes of the United States and Europe, typical insolation ranges from 4 kWh/m²/day in northern climes to 6.5 kWh/m²/day in the sunniest regions. A photovoltaic installation in the southern latitudes of Europe or the United States may expect to produce 1 kWh/m²/day. A typical 1 kW photovoltaic installation in Australia or the southern latitudes of Europe or United States, may produce 3.5–5 kWh per day, dependent on location, orientation, tilt, insolation and other factors. In the Sahara desert, with less cloud cover and a better solar angle, one could ideally obtain closer to 8.3 kWh/m²/day provided the nearly ever present wind would not blow sand onto the units. The area of the Sahara desert is over 9 million km². 90,600 km², or about 1%, could generate as much electricity as all of the world's power plants combined.

text: Solar insolation

text: is made up of direct, diffuse, and reflected

text: radiation

text: . The absorption factor of a PV cell is deﬁned as the fraction of incident solar irradiance that is absorbed by the cell. At high noon on a cloudless day at the equator, the power of the sun is about 1

text: kW

text: /m², on the Earth's surface, to a plane that is perpendicular to the sun's rays. As such, PV arrays can

text: track the sun

text: through each day to greatly enhance energy collection. However, tracking devices add cost, and require maintenance, so it is more common for PV arrays to have fixed mounts that tilt the array and face

text: solar noon

text: (approximately due south in the Northern Hemisphere or due north in the Southern Hemisphere). The tilt angle, from horizontal, can be varied for season, but if fixed, should be set to give optimal array output during the peak electrical demand portion of a typical year for a stand-alone system. This optimal module tilt angle is not necessarily identical to the tilt angle for maximum annual array energy output. The optimization of the a photovoltaic system for a specific environment can be complicated as issues of solar flux, soiling, and snow losses should be taken into effect. In addition, recent work has shown that spectral effects can play a role in optimal photovoltaic material selection. For example, the spectral

text: albedo

text: can play a significant role in output depending on the surface around the photovoltaic system  and the type of solar cell material. For the weather and latitudes of the United States and Europe, typical insolation ranges from 4 kWh/m²/day in northern climes to 6.5 kWh/m²/day in the sunniest regions. A photovoltaic installation in the southern latitudes of Europe or the United States may expect to produce 1 kWh/m²/day. A typical 1 kW photovoltaic installation in Australia or the southern latitudes of Europe or United States, may produce 3.5–5 kWh per day, dependent on location, orientation, tilt, insolation and other factors. In the

text: Sahara

text: desert, with less cloud cover and a better solar angle, one could ideally obtain closer to 8.3 kWh/m²/day provided the nearly ever present wind would not blow sand onto the units. The area of the Sahara desert is over 9 million km². 90,600 km², or about 1%, could generate as much electricity as all of the world's power plants combined.

text: The Solar System began forming about 4.6 billion years ago, or about 9 billion years after the Big Bang. A fragment of a molecular cloud made mostly of hydrogen and traces of other elements began to collapse, forming a large sphere in the center which would become the Sun, as well as a surrounding disk. The surrounding accretion disk would coalesce into a multitude of smaller objects that would become planets, asteroids, and comets. The Sun is a late-generation star, and the Solar System incorporates matter created by previous generations of stars.

text: The

text: Solar System

text: began forming about 4.6 billion years ago, or about 9 billion years after the Big Bang. A fragment of a molecular cloud made mostly of hydrogen and traces of other elements began to collapse, forming a large sphere in the center which would become the Sun, as well as a surrounding disk. The surrounding accretion disk would coalesce into a multitude of smaller objects that would become planets, asteroids, and comets. The Sun is a late-generation star, and the Solar System incorporates matter created by previous generations of stars.

text: Wolf 489's mass is 0.55 ± 0.03 Solar masses, its surface gravity is 10 (8.91 · 10) cm·s, or approximately 91 000 of Earth's, corresponding to a radius 9089 km, or 143% of Earth's.

text: Wolf 489's mass is 0.55 ± 0.03

text: Solar mass

text: es, its

text: surface gravity

text: is 10 (8.91 · 10) cm·s, or approximately 91 000 of

text: Earth's

text: , corresponding to a radius 9089 km, or 143% of

text: Earth's

text: The behavior of all the orbits in the disk can be determined by considering what happens to the disk. The intersection of the disk with the given periodic orbit comes back to itself every period of the orbit and so do points in its neighborhood. When this neighborhood returns, its shape is transformed.  Among the points back inside the disk are some points that will leave the disk neighborhood and others that will continue to return. The set of points that never leaves the neighborhood of the given periodic orbit form a fractal.

text: More recently George Gatewood began using the Allegheny Observatory to search for extrasolar planets as well as to follow up on claims of extrasolar planets, starting in 1972.  This is done using astrometry, which is the practice of measuring the position of stars. In addition to studying the positions of stars on the thousands of photographic plates in the vaults of the observatory, George Gatewood also designed the Multichannel Astrometric Photometer (MAP) for use with the Thaw telescope to measure the position of a target star and its close neighbors on images taken 6 months apart. This technique takes advantage of parallax. If the target star has a companion then it will wobble due to the gravitational pull of the unseen companion. The size of the companion can be measured by the size of the wobble.

text: More recently

text: George Gatewood

text: began using the Allegheny Observatory to search for extrasolar planets as well as to follow up on claims of extrasolar planets, starting in 1972.  This is done using astrometry, which is the practice of measuring the position of stars. In addition to studying the positions of stars on the thousands of photographic plates in the vaults of the observatory,

text: George Gatewood

text: also designed the Multichannel Astrometric Photometer (MAP) for use with the Thaw telescope to measure the position of a target star and its close neighbors on images taken 6 months apart. This technique takes advantage of parallax. If the target star has a companion then it will wobble due to the gravitational pull of the unseen companion. The size of the companion can be measured by the size of the wobble.

text: There are several stars with confirmed planetary systems in Auriga; there is also a white dwarf with a suspected planetary system. HD 40979 has one planet, HD 40979 b. It was discovered in 2002 through radial velocity measurements on the parent star. HD 40979 is 33.3 parsecs from Earth, a spectral class F8V star of magnitude 6.74—just past the limit of visibility to the naked eye. It is of similar size to the Sun, at 1.1 solar masses and 1.21 solar radii. The planet, with a mass of 3.83 Jupiter masses, orbits with a semi-major axis of 0.83 AU and a period of 263.1 days. HD 45350 has one planet as well. HD 45350 b was discovered through radial velocity measurements in 2004. It has a mass of 1.79 Jupiter masses and orbits every 890.76 days at a distance of 1.92 AU. Its parent star is faint, at an apparent magnitude of 7.88, a G5IV type star 49 parsecs away. It has a mass of 1.02 solar masses and a radius of 1.27 solar radii. HD 43691 b is a significantly larger planet, with a mass of 2.49 Jupiter masses; it is also far closer to its parent star, HD 43691. Discovered in 2007 from radial velocity measurements, it orbits at a distance of 0.24 AU with a period of 36.96 days. HD 43691 has a radius identical to the Sun's, though it is more dense—its mass is 1.38 solar masses. It is a G0IV type star of magnitude 8.03, 93.2 parsecs from Earth.

text: There are several stars with confirmed planetary systems in Auriga; there is also a white dwarf with a suspected planetary system.

text: HD 40979

text: has one planet,

text: HD 40979 b

text: . It was discovered in 2002 through

text: radial velocity

text: measurements on the parent star. HD 40979 is 33.3

text: parsec

text: s from Earth, a

text: spectral class

text: F8V star of magnitude 6.74—just past the limit of visibility to the naked eye. It is of similar size to the Sun, at 1.1 solar masses and 1.21 solar radii. The planet, with a mass of 3.83

text: Jupiter mass

text: es, orbits with a semi-major axis of 0.83

text: AU

text: and a period of 263.1 days.

text: HD 45350

text: has one planet as well.

text: HD 45350 b

text: was discovered through radial velocity measurements in 2004. It has a mass of 1.79 Jupiter masses and orbits every 890.76 days at a distance of 1.92 AU. Its parent star is faint, at an apparent magnitude of 7.88, a G5IV type star 49 parsecs away. It has a mass of 1.02 solar masses and a radius of 1.27 solar radii.

text: HD 43691 b

text: is a significantly larger planet, with a mass of 2.49 Jupiter masses; it is also far closer to its parent star,

text: HD 43691

text: . Discovered in 2007 from radial velocity measurements, it orbits at a distance of 0.24 AU with a period of 36.96 days. HD 43691 has a radius identical to the Sun's, though it is more dense—its mass is 1.38 solar masses. It is a G0IV type star of magnitude 8.03, 93.2 parsecs from Earth.

text: The Dawn mission was designed to study two large bodies in the asteroid belt in order to answer questions about the formation of the Solar System, as well as to test the performance of its ion drive in deep space. Ceres and Vesta were chosen as two contrasting protoplanets, the first one apparently "wet" (i.e. icy and cold) and the other "dry" (i.e. rocky), whose accretion was terminated by the formation of Jupiter. The two bodies provide a bridge in scientific understanding between the formation of rocky planets and the icy bodies of the Solar System, and under what conditions a rocky planet can hold water.

text: The Dawn mission was designed to study two large bodies in the

text: asteroid belt

text: in order to answer questions about the formation of the

text: Solar System

text: , as well as to test the performance of its

text: ion drive

text: in deep space. Ceres and Vesta were chosen as two contrasting

text: protoplanet

text: s, the first one apparently "wet" (i.e. icy and cold) and the other "dry" (i.e. rocky), whose

text: accretion

text: was terminated by the formation of

text: Jupiter

text: . The two bodies provide a bridge in scientific understanding between the formation of

text: rocky planets

text: and the icy bodies of the Solar System, and under what conditions a rocky planet can hold water.

text: Like all main-belt asteroids, Ida's orbit lies between the planets Mars and Jupiter. Its orbital period is 4.84 years, and its rotation period is 4.63 hours. Ida has an average diameter of . It is irregularly shaped and elongated, and apparently composed of two large objects connected together. Its surface is one of the most heavily cratered in the Solar System, featuring a wide variety of crater sizes and ages.

text: Like all main-belt asteroids, Ida's orbit lies between the planets

text: Mars

text: and Jupiter. Its

text: orbital period

text: is 4.84 years, and its

text: rotation period

text: is 4.63 hours. Ida has an average diameter of . It is irregularly shaped and elongated, and apparently composed of two large objects connected together. Its surface is one of the most heavily cratered in the Solar System, featuring a wide variety of crater sizes and ages.

text: The Rho Ophiuchi cloud complex is a dark nebula of gas and dust that is located 1° south of the star ρ Ophiuchi of the constellation Ophiuchus. At an estimated distance of , this cloud is one of the closest star-forming regions to the Solar System.

text: The Rho Ophiuchi cloud complex is a

text: dark nebula

text: of gas and dust that is located 1° south of the

text: star

text: ρ Ophiuchi

text: of the constellation

text: Ophiuchus

text: . At an estimated distance of , this cloud is one of the closest

text: star-forming

text: regions to the

text: Solar System

text: No secondary characteristics have been observed around extrasolar planets. The sub-brown dwarf Cha 110913-773444, which has been described as a rogue planet, is believed to be orbited by a tiny protoplanetary disc and the sub-brown dwarf OTS 44 was shown to be surrounded by a substantial protoplanetary disk of at least 10 Earth masses.

text: No secondary characteristics have been observed around extrasolar planets. The

text: sub-brown dwarf

text: Cha 110913-773444

text: , which has been described as a

text: rogue planet

text: , is believed to be orbited by a tiny

text: protoplanetary disc

text: and the sub-brown dwarf

text: OTS 44

text: was shown to be surrounded by a substantial protoplanetary disk of at least 10 Earth masses.

text: The observatory was established in 1933. Through its first 40 years, its primary research focus was on tracking minor planets and asteroids in the Solar System. Starting in the 1980s, astronomers began to use the facility to measure stars over long periods of time, which led to hunts for extrasolar planets, i.e., planets outside the Solar System. Surveys at Oak Ridge found many such distant planets.

text: The observatory was established in 1933. Through its first 40 years, its primary research focus was on tracking

text: minor planet

text: s and

text: asteroid

text: s in the

text: Solar System

text: . Starting in the 1980s, astronomers began to use the facility to measure stars over long periods of time, which led to hunts for

text: extrasolar planet

text: s, i.e.,

text: planet

text: s outside the Solar System. Surveys at Oak Ridge found many such distant planets.

text: With the influx of additional capital and the power of Gaiam behind it, Real Goods looked for a promising growth opportunity and found it in the residential solar installation market. Since Real Goods was now headquartered in Colorado, yet maintained the SLC, SLI and offices in California, and since the federal government and both states offered attractive tax incentives for installing solar systems, Real Goods opened its residential solar system installation division in both states in 2002. The commercial solar business was also growing, and Real Goods launched its commercial solar installation division in 2004.

text: With the influx of additional

text: capital

text: and the power of Gaiam behind it, Real Goods looked for a promising growth opportunity and found it in the residential solar installation market. Since Real Goods was now headquartered in

text: Colorado

text: , yet maintained the SLC, SLI and offices in California, and since the federal government and both states offered attractive tax incentives for installing solar systems, Real Goods opened its residential solar system installation division in both states in 2002. The commercial solar business was also growing, and Real Goods launched its commercial solar installation division in 2004.

text: Looking beyond the Solar System, there are up to several hundred billion potential stars with possible colonization targets. The main difficulty is the vast distances to other stars: roughly a hundred thousand times further away than the planets in the Solar System. This means that some combination of very high speed (some percentage of the speed of light), or travel times lasting centuries or millennia, would be required. These speeds are far beyond what current spacecraft propulsion systems can provide.

text: Looking beyond the Solar System, there are up to several hundred billion potential stars with possible colonization targets. The main difficulty is the vast distances to other stars: roughly a hundred thousand times further away than the planets in the Solar System. This means that some combination of very high speed (some percentage of the

text: speed of light

text: ), or travel times lasting centuries or millennia, would be required. These speeds are far beyond what current

text: spacecraft propulsion

text: systems can provide.

text: In 1943, in the Journal of the British Astronomical Association, Kenneth Edgeworth hypothesized that, in the region beyond Neptune, the material within the primordial solar nebula was too widely spaced to condense into planets, and so rather condensed into a myriad of smaller bodies. From this he concluded that "the outer region of the solar system, beyond the orbits of the planets, is occupied by a very large number of comparatively small bodies" and that, from time to time, one of their number "wanders from its own sphere and appears as an occasional visitor to the inner solar system", becoming a comet.

text: In 1943, in the Journal of the British Astronomical Association,

text: Kenneth Edgeworth

text: hypothesized that, in the region beyond

text: Neptune

text: , the material within the

text: primordial

text: solar nebula

text: was too widely spaced to condense into planets, and so rather condensed into a myriad of smaller bodies. From this he concluded that "the outer region of the solar system, beyond the orbits of the planets, is occupied by a very large number of comparatively small bodies" and that, from time to time, one of their number "wanders from its own sphere and appears as an occasional visitor to the inner solar system", becoming a

text: comet

text: The number of terraformed worlds in the system is never mentioned in the series though in a deleted scene from the episode "Our Mrs. Reynolds", Captain Malcolm Reynolds mentions to the character Saffron that there are "more than 70 Earths spinning in this galaxy and the meek have inherited not a one." Also, the opening narration of the film Serenity gives us a brief history of the Firefly universe and mentions; "Earth That Was could no longer sustain our numbers; we were so many. We found a new Solar system, dozens of planets and hundreds of moons."

text: The number of terraformed worlds in the system is never mentioned in the series though in a deleted scene from the episode "

text: Our Mrs. Reynolds

text: ", Captain

text: Malcolm Reynolds

text: mentions to the character

text: Saffron

text: that there are "more than 70 Earths spinning in this galaxy and

text: the meek have inherited

text: not a one." Also, the opening narration of the film

text: Serenity

text: gives us a brief history of the Firefly universe and mentions; "Earth That Was could no longer sustain our numbers; we were so many. We found a new

text: Sol

text: ar

text: system

text: , dozens of planets and hundreds of moons."

text: The introduction of the feed-in-tariff (FiT) in 2010 saw rapid growth of the UK photovoltaic market, with many thousands of domestic installations along with numerous commercial, community and industrial projects.  On 13 July 2011, construction of the largest solar park in the United Kingdom was completed in Newark-on-Trent in Nottinghamshire. The 4.9 MW free-field system was built in just seven weeks after being granted planning permission. The system generates an estimated 4,860 MW·h of electricity (an average power of 560 kW) into the national grid each year.  There are several other examples of 4–5 MW field arrays of photovoltaics in the UK, including the 5 MW Langage Solar Park, the 5 MW Westmill Solar Farm, the 4.51 MW Marsten Solar Farm and Toyota's 4.6 MW plant in Burnaston, Derbyshire. The cuts to the FiT made in the fast track review announced by DECC on 9 June 2011 meant that large arrays of solar photovoltaics became a much less attractive investment opportunity for developers, especially for projects greater than 250 kW, so large field arrays such as these were less likely to be built beyond the 1 August 2011 cut off date, at least not until 2012, when PV prices reduced somewhat - a utility scale solar farm is paid 8.9 p/kWhr generated.

text: The introduction of the feed-in-tariff (FiT) in 2010 saw rapid growth of the UK photovoltaic market, with many thousands of domestic installations along with numerous commercial, community and industrial projects.  On 13 July 2011, construction of the largest solar park in the United Kingdom was completed in

text: Newark-on-Trent

text: in

text: Nottinghamshire

text: . The 4.9 MW free-field system was built in just seven weeks after being granted planning permission. The system generates an estimated 4,860 MW·h of electricity (an average power of 560 kW) into the national grid each year.  There are several other examples of 4–5 MW field arrays of photovoltaics in the UK, including the 5 MW Langage Solar Park, the 5 MW Westmill Solar Farm, the 4.51 MW Marsten Solar Farm and Toyota's 4.6 MW plant in Burnaston, Derbyshire. The cuts to the FiT made in the fast track review announced by DECC on 9 June 2011 meant that large arrays of solar photovoltaics became a much less attractive investment opportunity for developers, especially for projects greater than 250 kW, so large field arrays such as these were less likely to be built beyond the 1 August 2011 cut off date, at least not until 2012, when PV prices reduced somewhat - a utility scale solar farm is paid 8.9 p/kWhr generated.

text: Earth (otherwise known as the world, in  Gaia, or in Latin: Tellus, Terra) is the third planet from the Sun, the densest planet in the Solar System, the largest of the Solar System's four terrestrial planets, and the only astronomical object known to harbor life.

text: Earth (otherwise known as the world, in  Gaia, or in

text: Latin

text: Tellus

text: , Terra) is the third

text: planet

text: from the

text: Sun

text: , the densest planet in the

text: Solar System

text: terrestrial planet

text: s, and the only

text: astronomical object

text: known to harbor

text: life

text: The original Nice model begins with the giant planets in a compact configuration with nearly circular orbits. Initially, interactions with planetesimals originating in an outer disk drive a slow divergent migration of the giant planets. This planetesimal-driven migration continues until Jupiter and Saturn cross their mutual 2:1 resonance. The resonance crossing excites the eccentricities of Jupiter and Saturn. The increased eccentricities create perturbations on Uranus and Neptune, increasing their eccentricities until the system becomes chaotic and orbits begin to intersect. Gravitational encounters between the planets then scatter Uranus and Neptune outward into the planetesimal disk. The disk is disrupted, scattering many of the planetesimals onto planet-crossing orbits. A rapid phase of divergent migration of the giant planets is initiated and continues until the disk is depleted. Dynamical friction during this phase dampens the eccentricities of Uranus and Neptune stabilizing the system. In numerical simulations of the original Nice model the final orbits of the giant planets are similar to the current Solar System.

text: The original

text: Nice model

text: begins with the

text: giant planet

text: s in a compact configuration with nearly circular orbits. Initially, interactions with

text: planetesimal

text: s originating in an outer disk drive a slow divergent migration of the giant planets. This

text: planetesimal-driven migration

text: continues until

text: Jupiter

text: and

text: Saturn

text: cross their mutual 2:1

text: resonance

text: . The resonance crossing excites the

text: eccentricities

text: of Jupiter and Saturn. The increased eccentricities create perturbations on

text: Uranus

text: and

text: Neptune

text: , increasing their eccentricities until the system becomes chaotic and orbits begin to intersect. Gravitational encounters between the planets then scatter Uranus and Neptune outward into the planetesimal disk. The disk is disrupted, scattering many of the planetesimals onto planet-crossing orbits. A rapid phase of divergent migration of the giant planets is initiated and continues until the disk is depleted.

text: Dynamical friction

text: during this phase dampens the eccentricities of Uranus and Neptune stabilizing the system. In numerical simulations of the original Nice model the final orbits of the giant planets are similar to the current

text: Solar System

text: In 2014, a new confirmation method called "validation by multiplicity" was announced. From the planets previously confirmed through various methods, it was found that planets in most planetary systems orbit in a relatively flat plane, similar to the planets found in the Solar System. This means that if a star has multiple planet candidates, it is very likely a real planetary system. Transit signals still need to meet several criteria which rule out false-positive scenarios. For instance, it has to have considerable signal-to-noise ratio, it has at least three observed transits, orbital stability of those systems have to be stable and transit curve has to have a shape that partly eclipsing binaries could not mimic the transit signal. In addition, its orbital period needs to be 1.6 days or longer to rule out common false positives caused by eclipsing binaries. Validation by multiplicity method is very efficient and allows to confirm hundreds of Kepler candidates in a relatively short amount of time.

text: The FB-111A had new electronics, known as the SAC Mark IIB avionics suite. For the FB-111A the system used an attack radar improved from the F-111A's system, along with components that would be used on the F-111D, including the inertial navigation system, digital computers, and multi-function displays. Armament for the strategic bombing role was the Boeing AGM-69 SRAM (short-range attack missile); two could be carried in the internal weapons bay and four more on the inner underwing pylons. Nuclear gravity bombs were also typical FB armament. Fuel tanks were often carried on the third non-swivelling pylon of each wing. The FB-111A had a total weapon load of .

text: The FB-111A had new electronics, known as the SAC Mark IIB avionics suite. For the FB-111A the system used an attack radar improved from the F-111A's system, along with components that would be used on the F-111D, including the inertial navigation system, digital computers, and multi-function displays. Armament for the strategic bombing role was the Boeing

text: AGM-69 SRAM

text: (short-range attack missile); two could be carried in the internal weapons bay and four more on the inner underwing pylons. Nuclear gravity bombs were also typical FB armament. Fuel tanks were often carried on the third non-swivelling pylon of each wing. The FB-111A had a total weapon load of .

text: As of 2016 the following observations severely constrain the mass and distance of any possible additional Solar System planet:

text: On May 29, 2012, Pakistan inaugurated its first solar power on-grid power plant in Islamabad. Introduction of Clean Energy by Solar Electricity Generation System is a special grant aid project by the Japan International Cooperation Agency (JICA) under the Coolio Earth Partnership. This project includes the installation of two 178 kW photovoltaic (PV) systems at the premises of the Planning Commission and Pakistan Engineering Council.

text: On May 29, 2012, Pakistan inaugurated its first solar power on-grid power plant in Islamabad. Introduction of Clean Energy by Solar Electricity Generation System is a special grant aid project by the

text: Japan International Cooperation Agency

text: (JICA) under the Coolio Earth Partnership. This project includes the installation of two 178

text: kW

text: photovoltaic (PV) system

text: s at the premises of the Planning Commission and

text: Pakistan Engineering Council

text: Early conceptual designs for the Solar Probe mission used a gravity assist maneuver at Jupiter to cancel the orbital speed of the probe launched from Earth, in order to drop onto a trajectory close to the Sun. The Solar Probe Plus mission design simplifies this trajectory by using repeated gravity assists at Venus, to incrementally decrease the orbital perihelion to achieve multiple passes to approximately 8.5 solar radii, or about .

text: Early conceptual designs for the Solar Probe mission used a

text: gravity assist

text: maneuver at

text: Jupiter

text: to cancel the orbital speed of the probe launched from Earth, in order to drop onto a trajectory close to the Sun. The Solar Probe Plus mission design simplifies this trajectory by using repeated gravity assists at Venus, to incrementally decrease the orbital

text: perihelion

text: to achieve multiple passes to approximately 8.5

text: solar radii

text: , or about .

text: This maneuver can only change an object's velocity relative to a third, uninvolved object, – possibly the “centre of mass” or the Sun. There is no change in the velocities of the two objects involved in the maneuver relative to each other.  The Sun cannot be used in a gravitational slingshot because it is stationary compared to rest of the Solar System, which orbits the Sun.  It may be used to send a spaceship or probe into the galaxy because the Sun revolves around the center of the Milky Way.

text: Saturn's rings could give a further hint to identifying the Solar System. Rings around the planets Jupiter, Uranus and Neptune were unknown when the plaque was designed; however, unlike Saturn the ring systems on these planets are not as easily visible and apparent as Saturn's. Pluto was considered to be a planet when the plaque was designed; in 2006 the IAU reclassified Pluto as a dwarf planet and then in 2008 as a plutoid. Other large bodies classed as dwarf planets, such as Eris, are not depicted, as they were unknown at the time the plaque was made.

text: Saturn's rings could give a further hint to identifying the Solar System.

text: Rings

text: around the planets Jupiter,

text: Uranus

text: and

text: Neptune

text: were unknown when the plaque was designed; however, unlike Saturn the ring systems on these planets are not as easily visible and apparent as Saturn's.

text: Pluto

text: was considered to be a planet when the plaque was designed; in 2006 the

text: IAU

text: reclassified Pluto as a

text: dwarf planet

text: and then in 2008 as a

text: plutoid

text: . Other large bodies classed as dwarf planets, such as

text: Eris

text: , are not depicted, as they were unknown at the time the plaque was made.

text: Direct distance measurements are based upon the astronomical unit (AU), which is the distance between the Earth and the Sun. Historically, observations of transits of Venus were crucial in determining the AU; in the first half of the 20th century, observations of asteroids were also important. Presently the orbit of Earth is determined with high precision using radar measurements of distances to Venus and other nearby planets and asteroids, and by tracking interplanetary spacecraft in their orbits around the Sun through the Solar System. Kepler's laws provide precise ratios of the sizes of the orbits of objects orbiting the Sun, but provides no measurement of the overall scale of the orbit system. Radar is used to measure the distance between the orbits of the Earth and of a second body. From that measurement and the ratio of the two orbit sizes, the size of Earth's orbit is calculated. The Earth's orbit is known with a precision of a few meters.

text: Direct distance measurements are based upon the

text: astronomical unit

text: (AU), which is the distance between the

text: Earth

text: and the

text: Sun

text: . Historically, observations of

text: transits of Venus

text: were crucial in determining the AU; in the first half of the 20th century, observations of

text: asteroids

text: were also important. Presently the orbit of Earth is determined with high precision using radar measurements of distances to

text: Venus

text: and other nearby planets and asteroids, and by tracking interplanetary

text: spacecraft

text: in their orbits around the Sun through the

text: Solar System

text: Kepler's laws

text: provide precise

text: ratio

text: s of the sizes of the orbits of objects orbiting the Sun, but provides no measurement of the overall scale of the orbit system. Radar is used to measure the distance between the orbits of the Earth and of a second body. From that measurement and the ratio of the two orbit sizes, the size of Earth's orbit is calculated. The Earth's orbit is known with a precision of a few meters.

text: Canadian Solar offers solar modules, solar power systems, off-grid solar home application systems and specialized solar products.

text: On October 6, 2008, Agilent Technologies and SunPower Corporation announced that a 1-megawatt solar tracking system at Agilent's campus will start producing electricity in mid-October.  The system features a  parking lot canopy structure with nearly 3,500 SunPower solar panels that track the sun throughout the day. The design of the company's tracking solar system will generate up to 25 percent more energy for Agilent than a similarly sized flat, rooftop system, the company said. As a result, Agilent's solar parking canopy is the largest solar energy generator in Sonoma County, California.

text: On October 6, 2008,

text: Agilent Technologies

text: and SunPower Corporation announced that a 1-megawatt

text: solar tracking system

text: at Agilent's campus will start producing electricity in mid-October.  The system features a

text: parking lot

text: canopy structure with nearly 3,500 SunPower solar panels that track the sun throughout the day. The design of the company's tracking solar system will generate up to 25 percent more energy for Agilent than a similarly sized flat, rooftop system, the company said. As a result, Agilent's solar parking canopy is the largest solar energy generator in

text: Sonoma County

text: , California.

text: Finally, between approximately 4.1 and 3.8 billion years ago, asteroid impacts during the Late Heavy Bombardment caused significant changes to the surface environment of objects in the Solar System. The low gravity of Mars suggests that these impacts could have ejected much of the Martian atmosphere into deep space.

text: Finally, between approximately 4.1 and 3.8 billion years ago,

text: asteroid

text: impacts during the

text: Late Heavy Bombardment

text: caused significant changes to the surface environment of objects in the Solar System. The low

text: gravity

text: of Mars suggests that these impacts could have ejected much of the Martian atmosphere into deep space.

text: The Solar System formed 4.568 billion years ago from the gravitational collapse of a region within a large molecular cloud. This initial cloud was likely several light-years across and probably birthed several stars. As is typical of molecular clouds, this one consisted mostly of hydrogen, with some helium, and small amounts of heavier elements fused by previous generations of stars. As the region that would become the Solar System, known as the pre-solar nebula, collapsed, conservation of angular momentum caused it to rotate faster. The centre, where most of the mass collected, became increasingly hotter than the surrounding disc. As the contracting nebula rotated faster, it began to flatten into a protoplanetary disc with a diameter of roughly 200 AU and a hot, dense protostar at the centre. The planets formed by accretion from this disc, in which dust and gas gravitationally attracted each other, coalescing to form ever larger bodies. Hundreds of protoplanets may have existed in the early Solar System, but they either merged or were destroyed, leaving the planets, dwarf planets, and leftover minor bodies.

text: The Solar System formed 4.568 billion years ago from the gravitational collapse of a region within a large

text: molecular cloud

text: . This initial cloud was likely several light-years across and probably birthed several stars. As is typical of molecular clouds, this one consisted mostly of hydrogen, with some helium, and small amounts of heavier elements fused by previous generations of stars. As the region that would become the Solar System, known as the

text: pre-solar nebula

text: , collapsed,

text: conservation of angular momentum

text: caused it to rotate faster. The centre, where most of the mass collected, became increasingly hotter than the surrounding disc. As the contracting nebula rotated faster, it began to flatten into a

text: protoplanetary disc

text: with a diameter of roughly 200

text: AU

text: and a hot, dense

text: protostar

text: at the centre. The planets formed by

text: accretion

text: from this disc, in which dust and gas gravitationally attracted each other, coalescing to form ever larger bodies. Hundreds of protoplanets may have existed in the early Solar System, but they either merged or were destroyed, leaving the planets, dwarf planets, and leftover

text: minor bodies

text: Following the latest campaign against the NTF, GTVA forces re-engage Shivan forces in the nebula, while testing out new weapon and technology prototypes such as an AWACS cruiser that enables better vision in the nebula, a TAG missile that enables friendly capital ships to instantly lock on to the "tagged" enemy ship, and the Pegasus-class stealth fighter. With the aid of these new technologies, the Alliance destroys a Shivan Ravana-class destroyer.  The 3rd Fleet soon return to GTVA space, where Bosch launches an assault to get the NTF to the Jump Gate.  While the NTF loses many ships, the Iceni escapes with Bosch on board, thanks to sabotage preventing the GTVA Colossus from firing on it.  While pursuing Bosch into the nebula, the GTVA attack Shivan nebular gas mining operations, only for the Shivans to retaliate with a juggernaut-class warship of their own, dubbed the Sathanas. The Sathanas enters Terran–Vasudan space, despite an effort to destroy the jump gate linking the nebula to Gamma Draconis; the node between the two system had stabilised at some point.  With the Shivans encroaching on GTVA space, the Sathanas is engaged by the Colossus as it enters the densely populated Capella system and, thanks to the player's efforts in disabling its beam turrets, is destroyed in the engagement.

text: BHR 71 is a small dark nebula in the constellation of Musca which is 600 light years from the Solar system. It has a diameter of about 1 light year.

text: BHR 71 is a small

text: dark nebula

text: in the constellation of

text: Musca

text: which is 600

text: light year

text: s from the

text: Solar system

text: . It has a diameter of about 1 light year.

text: A minor but notable subset of the materials that make up the foregoing collections were also solidified outside of the Solar System. These are often referred to as interstellar materials, some of which are also presolar i.e. they predate the formation of the Solar System.

text: A minor but notable subset of the materials that make up the foregoing collections were also solidified outside of the Solar System. These are often referred to as interstellar materials, some of which are also

text: presolar

text: i.e. they predate the formation of the Solar System.

text: The Solar System Family Portrait is an image of the Solar System acquired by MESSENGER during November 2010 from approximately the orbit of Mercury.  The mosaic is intended to be complementary to the Voyager Family Portrait acquired from the outer edge of the Solar System on February 14, 1990.

text: The Solar System Family Portrait is an image of the

text: Solar System

text: acquired by

text: MESSENGER

text: during November 2010 from approximately the orbit of Mercury.  The

text: mosaic

text: is intended to be complementary to the

text: Voyager Family Portrait

text: acquired from the outer edge of the Solar System on February 14, 1990.

text: Her contributions to the exploration of the outer solar system were recognized with the naming of Asteroid (7231) Porco which is "Named in honor of Carolyn C. Porco, a pioneer in the study of planetary ring systems...and a leader in spacecraft exploration of the outer solar system."

text: Her contributions to the exploration of the outer solar system were recognized with the naming of Asteroid

text: (7231) Porco

text: which is "Named in honor of Carolyn C. Porco, a pioneer in the study of planetary ring systems...and a leader in spacecraft exploration of the outer solar system."

text: In 1996, ethane was detected in Comet Hyakutake, and it has since been detected in some other comets. The existence of ethane in these distant solar system bodies may implicate ethane as a primordial component of the solar nebula from which the sun and planets are believed to have formed.

text: In 1996, ethane was detected in

text: Comet Hyakutake

text: , and it has since been detected in some other

text: comets

text: . The existence of ethane in these distant solar system bodies may implicate ethane as a primordial component of the

text: solar nebula

text: from which the sun and planets are believed to have formed.

text: If a reference direction from one side of the plane of reference to the other is defined, the two nodes can be distinguished. For geocentric and heliocentric orbits, the ascending node (or north node) is where the orbiting object moves north through the plane of reference, and the descending node (or south node) is where it moves south through the plane. In the case of objects outside the Solar System, the ascending node is the node where the orbiting secondary passes away from the observer, and the descending node is the node where it moves towards the observer.

text: Encyclopedic facts about the Earth and the Solar System.

text: Encyclopedic facts about the

text: Earth

text: and the

text: Solar System

text: Orbiter was developed as a realistic simulator, with accurately modeled planetary motion, gravitation effects (including non-spherical gravity), free space, atmospheric flight and orbital decay. The position of the planets in the solar system is calculated by the VSOP87 solution, while the Earth-Moon system is simulated by the ELP2000 model. Only Newtonian mechanics are simulated, not taking relativistic effects into account. This means that phenomena such as time dilation due to relativistic effects are not simulated, although situations where this is noticeable are very rare.

text: Orbiter was developed as a realistic

text: simulator

text: , with accurately modeled planetary motion,

text: gravitation

text: effects (including non-spherical gravity), free space, atmospheric flight and

text: orbital decay

text: . The position of the planets in the solar system is calculated by the

text: solution, while the Earth-Moon system is simulated by the

text: model. Only

text: Newtonian mechanics

text: are simulated, not taking

text: relativistic effects

text: into account. This means that phenomena such as

text: time dilation

text: due to

text: relativistic effects

text: are not simulated, although situations where this is noticeable are very rare.

text: This method has two major disadvantages. First, planetary transits are only observable when the planet's orbit happens to be perfectly aligned from the astronomers' vantage point. The probability of a planetary orbital plane being directly on the line-of-sight to a star is the ratio of the diameter of the star to the diameter of the orbit (in small stars, the radius of the planet is also an important factor). About 10% of planets with small orbits have such an alignment, and the fraction decreases for planets with larger orbits. For a planet orbiting a Sun-sized star at 1 AU, the probability of a random alignment producing a transit is 0.47%. Therefore, the method cannot guarantee that any particular star is not a host to planets. However, by scanning large areas of the sky containing thousands or even hundreds of thousands of stars at once, transit surveys can find more extrasolar planets than the radial-velocity method. Several surveys have taken that approach, such as the ground-based MEarth Project, SuperWASP, KELT, and HATNet and the space-based COROT and Kepler missions. The transit method has also the advantage of detecting planets around stars that are located a few thousand light years away. The most distant planets detected by Sagittarius Window Eclipsing Extrasolar Planet Search are located near the galactic center. However, reliable follow-up observations of these stars are nearly impossible with current technology.

text: This method has two major disadvantages. First, planetary transits are only observable when the planet's orbit happens to be perfectly aligned from the astronomers' vantage point. The probability of a planetary orbital plane being directly on the line-of-sight to a star is the ratio of the diameter of the star to the diameter of the orbit (in small stars, the radius of the planet is also an important factor). About 10% of planets with small orbits have such an alignment, and the fraction decreases for planets with larger orbits. For a planet orbiting a Sun-sized star at 1

text: AU

text: , the probability of a random alignment producing a transit is 0.47%. Therefore, the method cannot guarantee that any particular star is not a host to planets. However, by scanning large areas of the sky containing thousands or even hundreds of thousands of stars at once, transit surveys can find more extrasolar planets than the radial-velocity method. Several surveys have taken that approach, such as the ground-based

text: MEarth Project

text: SuperWASP

text: KELT

text: , and

text: HATNet

text: and the space-based

text: COROT

text: and

text: Kepler

text: missions. The transit method has also the advantage of detecting planets around stars that are located a few thousand light years away. The most distant planets detected by

entity_name: Sagittarius Window Eclipsing Extrasolar Planet Search

text: Sagittarius Window Eclipsing Extrasolar Planet Search

text: are located near the galactic center. However, reliable follow-up observations of these stars are nearly impossible with current technology.

text: The application of Newton's law of gravity has enabled the acquisition of much of the detailed information we have about the planets in the Solar System, the mass of the Sun, and details of quasars; even the existence of dark matter is inferred using Newton's law of gravity. Although we have not traveled to all the planets nor to the Sun, we know their masses. These masses are obtained by applying the laws of gravity to the measured characteristics of the orbit. In space an object maintains its orbit because of the force of gravity acting upon it. Planets orbit stars, stars orbit galactic centers, galaxies orbit a center of mass in clusters, and clusters orbit in superclusters. The force of gravity exerted on one object by another is directly proportional to the product of those objects' masses and inversely proportional to the square of the distance between them.

text: The application of Newton's law of gravity has enabled the acquisition of much of the detailed information we have about the planets in the Solar System, the mass of the Sun, and details of

text: quasar

text: s; even the existence of

text: dark matter

text: is inferred using Newton's law of gravity. Although we have not traveled to all the planets nor to the Sun, we know their masses. These masses are obtained by applying the laws of gravity to the measured characteristics of the orbit. In space an object maintains its

text: orbit

text: because of the force of gravity acting upon it. Planets orbit stars, stars orbit

text: galactic center

text: s,

text: galaxies

text: orbit a center of mass in clusters, and clusters orbit in

text: supercluster

text: s. The force of gravity exerted on one object by another is directly proportional to the product of those objects' masses and inversely proportional to the square of the distance between them.

text: NGC 6741, also known as the Phantom Streak Nebula, is located about 7000 light-years away in the constellation of Aquila (the Eagle). NGC 6741 is classed as a planetary nebula, though no planets are responsible for this billowy cloud; the term came about in the 18th century because the round gas shells resembled the Solar System's outer giant planets in astronomers' telescopes. Although fairly bright, this object appears very small though a typical telescope and was missed by early surveyors of the skies and only spotted in 1882 by Edward Charles Pickering.

text: NGC 6741, also known as the Phantom Streak Nebula, is located about 7000 light-years away in the constellation of

text: Aquila

text: (the Eagle). NGC 6741 is classed as a

text: planetary nebula

text: , though no planets are responsible for this billowy cloud; the term came about in the 18th century because the round gas shells resembled the Solar System's outer giant planets in astronomers' telescopes. Although fairly bright, this object appears very small though a typical telescope and was missed by early surveyors of the skies and only spotted in 1882 by

text: Edward Charles Pickering

text: This is a list of all confirmed gravitationally rounded objects in the Solar System. These objects all have a rounded, ellipsoidal shape due to the forces of their own gravity (hydrostatic equilibrium) and their sizes range from dwarf planets and moons to the planets and the sun. This list does not include any small Solar System bodies, but it does a sample of planetary-mass objects whose shape has yet to be accurately determined. The Sun's orbital characteristics are listed in relation to the Galactic Center, while all other objects are listed in order of their distance from the Sun.

text: This is a list of all confirmed gravitationally rounded objects in the Solar System. These objects all have a rounded,

text: ellipsoid

text: al shape due to the forces of their own gravity (

text: hydrostatic equilibrium

text: ) and their sizes range from dwarf planets and moons to the planets and the sun. This list does not include any

text: small Solar System bodies

text: , but it does a sample of planetary-mass objects whose shape has yet to be accurately determined. The Sun's orbital characteristics are listed in relation to the

text: Galactic Center

text: , while all other objects are listed in order of their distance from the Sun.

text: The distance from the Solar System is probably about 11,000 light years, or approximately half-way from the Sun to the Galactic Center, but a closer distance of ~2800 ly is not ruled out. GRO J1655-40 and its companion are moving through the Milky Way at around 112 km/s (250,000 miles per hour), in a galactic orbit that depends on its exact distance, but is mostly interior to the "Solar circle", d~8,500 pc, and within 150 pc (~500 ly) of the galactic plane.For comparison, the Sun and other nearby stars have typical speeds on the order of 20 km/s relative to the average velocity of stars moving with the galactic disk's rotation in the solar neighborhood, which supports the idea that the black hole formed from the collapse of the core of a massive star. As the core collapsed, its outer layers exploded as a supernova. Such explosions often seem to leave the remnant system moving through the galaxy with unusually high speed.

text: The distance from the Solar System is probably about 11,000 light years, or approximately half-way from the Sun to the

text: Galactic Center

text: , but a closer distance of ~2800 ly is not ruled out. GRO J1655-40 and its companion are moving through the

text: Milky Way

text: at around 112 km/s (250,000 miles per hour), in a galactic orbit that depends on its exact distance, but is mostly interior to the "Solar circle", d~8,500 pc, and within 150 pc (~500 ly) of the galactic plane.For comparison, the Sun and other nearby stars have typical speeds on the order of 20 km/s relative to the average velocity of stars moving with the galactic disk's rotation in the solar neighborhood, which supports the idea that the black hole formed from the collapse of the core of a massive star. As the core collapsed, its outer layers exploded as a

text: supernova

text: . Such explosions often seem to leave the remnant system moving through the galaxy with unusually high speed.

text: In the article by Burney et al. (2010) another use for solar energy that has been proposed is the Photovoltaic- (or solar-) powered drip irrigation (PVDI) system [which] combines the efficiency of drip irrigation with the reliability of a solar-powered water pump… [Where the] PV array powers a pump (either surface or submersible, depending on the water source) that feeds water to a reservoir. The reservoir then gravity-distributes the water to a low-pressure drip irrigation system. No batteries are used in the system: The pump only runs during the daytime, and energy storage is in the height of the column of water in the reservoir.An important technological advancement for agricultural practices in the region that is related to increasing food security; the PVDI systems were integrated into preexisting local women’s agricultural groups in the Kalalé District of Northern Benin in November 2007. The PVDI systems were conceived, financed, and installed by an NGO, the Solar Electric Light Fund, to boost vegetable production from communal gardens in an effort to combat high malnutrition and poverty levels in the region. (Burney et al., 2010).

text: In the article by Burney et al. (2010) another use for solar energy that has been proposed is the Photovoltaic- (or solar-) powered drip irrigation (PVDI) system [which] combines the efficiency of

text: drip irrigation

text: with the reliability of a solar-powered water pump… [Where the] PV array powers a pump (either surface or submersible, depending on the water source) that feeds water to a reservoir. The reservoir then gravity-distributes the water to a low-pressure drip irrigation system. No batteries are used in the system: The pump only runs during the daytime, and energy storage is in the height of the column of water in the reservoir.An important technological advancement for agricultural practices in the region that is related to increasing food security; the PVDI systems were integrated into preexisting local women’s agricultural groups in the Kalalé District of Northern

text: Benin

text: in November 2007. The PVDI systems were conceived, financed, and installed by an NGO, the Solar Electric Light Fund, to boost vegetable production from communal gardens in an effort to combat high malnutrition and poverty levels in the region. (Burney et al., 2010).

text: have radiation pressure at least half as strong as gravity, and will pass out of the Solar System on hyperbolic orbits if their initial velocities were Keplerian. For rocky dust particles, this corresponds to a diameter of less than 1 µm.

text: have

text: radiation pressure

text: at least half as strong as gravity, and will pass out of the Solar System on hyperbolic orbits if their initial velocities were Keplerian. For rocky dust particles, this corresponds to a diameter of less than 1

text: µm

text: Fictional planets in our Solar System beyond the orbit of Neptune have been employed many times as settings or references in science fiction. Following the general reception of Pluto as the ninth planet of the Solar System in 1930, a hypothetical additional planet was sometimes called a "tenth planet".  Since 1992, a very large number of objects have been found beyond Neptune; all the objects in the following list, however, are purely fictional. Common names for trans-Neptunian planets in fiction include Planet X, after a planet once believed to lie beyond Neptune, and Persephone (or Proserpina), after the wife of Pluto.

text: Fictional planets

text: in our

text: Solar System

text: beyond the orbit of Neptune

text: have been employed many times as settings or references in

text: science fiction

text: . Following the general reception of Pluto as the ninth planet of the Solar System in 1930, a hypothetical additional planet was sometimes called a "tenth planet".  Since 1992, a very large number of objects have been found beyond Neptune; all the objects in the following list, however, are purely fictional. Common names for trans-Neptunian planets in fiction include Planet X, after a planet once believed to lie beyond Neptune, and Persephone (or Proserpina), after the wife of Pluto.

text: In October 2015, astronomer Jean-Luc Margot of the University of California Los Angeles proposed a metric for orbital zone clearance derived from whether an object can clear an orbital zone of extent 2√3 of its Hill radius in a specific time scale. This metric places a clear dividing line between the dwarf planets and the planets of the solar system. The calculation is based on the mass of the host star, the mass of the body, and the orbital period of the body. An Earth-mass body orbiting a solar-mass star clears its orbit at distances of up to 400 astronomical units from the star.  A Mars-mass body at the orbit of Pluto clears its orbit. This metric, which leaves Pluto as a dwarf planet, applies to both the Solar System and to extrasolar systems.

text: In October 2015, astronomer

text: Jean-Luc Margot

text: of the

text: University of California Los Angeles

text: proposed a metric for orbital zone clearance derived from whether an object can clear an orbital zone of extent 2√3 of its

text: Hill radius

text: in a specific time scale. This metric places a clear dividing line between the dwarf planets and the planets of the solar system. The calculation is based on the mass of the host star, the mass of the body, and the orbital period of the body. An Earth-mass body orbiting a solar-mass star clears its orbit at distances of up to 400

text: astronomical unit

text: s from the star.  A Mars-mass body at the orbit of Pluto clears its orbit. This metric, which leaves Pluto as a dwarf planet, applies to both the Solar System and to extrasolar systems.

text: The notion of a heliocentric Solar System, with the Sun at the center, is possibly first suggested in the Vedic literature of ancient India, which often refer to the Sun as the "centre of spheres". Some interpret Aryabhatta's writings in Āryabhaṭīya as implicitly heliocentric.

text: The notion of a heliocentric Solar System, with the

text: Sun

text: at the center, is possibly first suggested in the

text: Vedic

text: literature of

text: ancient India

text: , which often refer to the Sun as the "centre of spheres". Some interpret

text: Aryabhatta

text: 's writings in

text: Āryabhaṭīya

text: as implicitly heliocentric.

text: The following is a list of alleged extrasolar planets not proposed or verified by researchers doing mainstream science.

text: At the back of the vehicle is the service module (Russian: приборно-агрегатный отсек (ПАО); Priborno-Agregatnyi Otsek (PAO)). It has a pressurized container shaped like a bulging can (Instrumentation compartment, PO (Priborniy Otsek)) that contains systems for temperature control, electric power supply, long-range radio communications, radio telemetry, and instruments for orientation and control. A non-pressurized part of the service module (Propulsion compartment, AO (Agregatniy Otsek)) contains the main engine and a liquid-fuelled propulsion system for maneuvering in orbit and initiating the descent back to Earth. The ship also has a system of low-thrust engines for orientation, attached to the Intermediate compartment (PkhO or Perekhodnoi Otsek). Outside the service module are the sensors for the orientation system and the solar array, which is oriented towards the sun by rotating the ship. An incomplete separation between the Service and Reentry modules led to emergency situations during Soyuz 5, Soyuz TMA-10 and Soyuz TMA-11, which led to an incorrect reentry orientation (crew ingress hatch first). The failure of several explosive bolts did not cut the connection between the Service/Reentry modules on the latter two flights.

text: At the back of the vehicle is the service module (Russian: приборно-агрегатный отсек (ПАО); Priborno-Agregatnyi Otsek (PAO)). It has a pressurized container shaped like a bulging can (Instrumentation compartment, PO (Priborniy Otsek)) that contains systems for temperature control, electric power supply, long-range

text: radio

text: communications, radio telemetry, and instruments for orientation and control. A non-pressurized part of the service module (Propulsion compartment, AO (Agregatniy Otsek)) contains the main engine and a liquid-fuelled

text: propulsion system

text: for maneuvering in orbit and initiating the descent back to Earth. The ship also has a system of low-thrust engines for orientation, attached to the Intermediate compartment (PkhO or Perekhodnoi Otsek). Outside the service module are the sensors for the orientation system and the solar array, which is oriented towards the sun by rotating the ship. An incomplete separation between the Service and Reentry modules led to emergency situations during

text: Soyuz 5

text: Soyuz TMA-10

text: and

text: Soyuz TMA-11

text: , which led to an incorrect reentry orientation (crew ingress hatch first). The failure of several explosive bolts did not cut the connection between the Service/Reentry modules on the latter two flights.

text: Ascendancy's primary display is a three-dimensional rotatable model of the star cluster, which details the star cluster's solar systems, starlanes, and civilizations. The player can "zoom in" to view rotatable models of solar systems (including planets and ships); view a planet's surface; and use various screens to manage their fleet, planets, and research. This play style is similar to the Master of Orion series.

text: Ascendancy's primary display is a

text: three-dimensional

text: rotatable model of the star cluster, which details the star cluster's solar systems, starlanes, and civilizations. The player can "zoom in" to view rotatable models of solar systems (including planets and ships); view a planet's surface; and use various screens to manage their fleet, planets, and research. This play style is similar to the

text: Master of Orion

text: series.

text: Asimov noted that the Solar System has a large number of planetary bodies (as opposed to the Sun and natural satellites) and stated that lines dividing "major planets" from minor planets were necessarily arbitrary. Asimov then pointed out that there was a large gap in size between Mercury, the smallest planetary body that was considered to be undoubtedly a major planet, and Ceres, the largest planetary body that was considered to be undoubtedly a minor planet. Only one planetary body known at the time, Pluto, fell within the gap. Rather than arbitrarily decide whether Pluto belonged with the major planets or the minor planets, Asimov suggested that any planetary body that fell within the size gap between Mercury and Ceres be called a mesoplanet, because mesos means "middle" in Greek.

text: Asimov noted that the

text: Solar System

text: has a large number of planetary bodies (as opposed to the

text: Sun

text: and

text: natural satellites

text: ) and stated that lines dividing "major planets" from

text: minor planet

text: s were necessarily arbitrary. Asimov then pointed out that there was a large gap in size between Mercury, the smallest planetary body that was considered to be undoubtedly a major planet, and Ceres, the largest planetary body that was considered to be undoubtedly a minor planet. Only one planetary body known at the time,

text: Pluto

text: , fell within the gap. Rather than arbitrarily decide whether Pluto belonged with the major planets or the minor planets, Asimov suggested that any planetary body that fell within the size gap between Mercury and Ceres be called a mesoplanet, because mesos means "middle" in

text: Greek

text: A sphere of influence (SOI) in astrodynamics and astronomy is the oblate-spheroid-shaped region around a celestial body where the primary gravitational influence on an orbiting object is that body. This is usually used to describe the areas in the Solar System where planets dominate the orbits of surrounding objects (such as moons), despite the presence of the much more massive (but distant) Sun. In a more general sense, the patched conic approximation is only valid within the SOI.

text: A sphere of influence (SOI) in

text: astrodynamics

text: and

text: astronomy

text: is the

text: oblate-spheroid

text: -shaped region around a

text: celestial body

text: where the primary

text: gravitational

text: influence on an

text: orbit

text: ing object is that body. This is usually used to describe the areas in the

text: Solar System

text: where

text: planets

text: dominate the orbits of surrounding objects (such as

text: moon

text: s), despite the presence of the much more massive (but distant)

text: Sun

text: . In a more general sense, the

text: patched conic approximation

text: is only valid within the SOI.

text: Kerbal Space Program makes some changes to the scaling of its solar system for gameplay purposes. For example, Kerbin (the game's analog of Earth) is only  in diameter (approximately 1/10 that of Earth's). Kerbin's density is over 10 times that of Earth's, in order to produce similar gravitational accelerations at the surface. The planets themselves are also significantly closer together than the planets in our solar system. However, there are mods that port the real-world solar system into the game, with accurate scaling and environments, and provide additional parts to make up for the extra power requirements.

text: Kerbal Space Program makes some changes to the scaling of its solar system for gameplay purposes. For example, Kerbin (the game's analog of Earth) is only  in diameter (approximately 1/10 that of Earth's). Kerbin's density is over 10 times that of Earth's, in order to produce similar gravitational accelerations at the surface. The planets themselves are also significantly closer together than the planets in our solar system. However, there are mods that port the real-world

text: solar system

text: into the game, with accurate scaling and environments, and provide additional parts to make up for the extra power requirements.

text: The outer planets are those planets in the Solar System beyond the asteroid belt, and hence refers to the gas giants, which are in order of their distance from the Sun:

text: The outer planets are those planets in the

text: Solar System

text: beyond the

text: asteroid belt

text: , and hence refers to the

text: gas giant

text: s, which are in order of their distance from the Sun:

text: Knowledge of Earth's location in the Universe has been shaped by 400 years of telescopic observations, and has expanded radically in the last century. Initially, Earth was believed to be the center of the Universe,  which consisted only of those planets visible with the naked eye and an outlying sphere of fixed stars. After the acceptance of the heliocentric model in the 17th century, observations by William Herschel and others showed that the Sun lay within a vast, disc-shaped galaxy of stars. By the 20th century, observations of spiral nebulae revealed that our galaxy was one of billions in an expanding universe, grouped into clusters and superclusters. By the end of the 20th century, the overall structure of the visible universe was becoming clearer, with superclusters forming into a vast web of filaments and voids. Superclusters, filaments and voids are the largest coherent structures in the Universe that we can observe. At still larger scales (over 1000 megaparsecs) the Universe becomes homogeneous meaning that all its parts have on average the same density, composition and structure.

text: Knowledge of Earth's location in the Universe has been shaped by 400 years of telescopic observations, and has expanded radically in the last century. Initially, Earth was believed to be the

text: center of the Universe

text: ,  which consisted only of those planets visible with the

text: naked eye

text: and an outlying sphere of

text: fixed stars

text: . After the acceptance of the

text: heliocentric model

text: in the 17th century, observations by

text: William Herschel

text: and others showed that the Sun lay within a vast, disc-shaped

text: galaxy

text: of stars. By the 20th century, observations of

text: spiral nebula

text: e revealed that our galaxy was one of billions in an

text: expanding universe

text: , grouped into clusters and

text: supercluster

text: s. By the end of the 20th century, the

text: overall structure

text: of the visible universe was becoming clearer, with superclusters forming into a vast web of

text: filaments

text: and

text: voids

text: . Superclusters, filaments and voids are the largest coherent structures in the Universe that we can observe. At still larger scales (over 1000

text: megaparsec

text: s) the Universe becomes homogeneous meaning that all its parts have on average the same density, composition and structure.

text: The next brightest star is Delta Velorum, also a multiple star system and one of the brightest eclipsing binaries in the sky. Together with Kappa Velorum, Iota and Epsilon Carinae, it forms the diamond-shaped asterism known as the False Cross—so called because it is sometimes mistaken for the Southern Cross, causing errors in astronavigation.  Appearing as a white star of magnitude 1.95, Delta is actually a triple or possibly quintuple star system located around 80 light-years from the Solar System. Delta A has a magnitude of 1.99 and is an eclipsing binary composed of two A-type white stars (Delta Aa and Ab) which orbit each other every  45.2 days and lie 0.5 AU from each other, with a resulting drop in magnitude of 0.4 when the dimmer one passes.in front of the brighter. Delta B is a 5.1 magnitude yellow G-class star of similar dimensions to our sun which ranges between 26 and 72 AU away from the brighter pair, taking 142 years to complete a revolution. Further out still, at a distance of 1700 AU, are two red dwarfs of magnitudes 11 and 13. If they are part of the multiple system, they take 28000 years to complete and orbit. Also called Markeb, Kappa appears as a blue-white star of spectral type B2IV-V and magnitude 2.47 but is in fact a spectroscopic binary. The two orbit around each other with a period of 116.65 days, but the size, mass and nature of the companion are as yet unclear.

text: The next brightest star is

text: Delta Velorum

text: , also a multiple star system and one of the brightest eclipsing binaries in the sky. Together with

text: Kappa Velorum

text: Iota

text: and

text: Epsilon Carinae

text: , it forms the diamond-shaped

text: asterism

text: known as the

text: False Cross

text: —so called because it is sometimes mistaken for the

text: Southern Cross

text: , causing errors in

text: astronavigation

text: .  Appearing as a white star of magnitude 1.95, Delta is actually a triple or possibly quintuple star system located around 80 light-years from the

text: Solar System

text: . Delta A has a magnitude of 1.99 and is an

text: eclipsing binary

text: composed of two A-type white stars (Delta Aa and Ab) which orbit each other every  45.2 days and lie 0.5 AU from each other, with a resulting drop in magnitude of 0.4 when the dimmer one passes.in front of the brighter. Delta B is a 5.1 magnitude yellow G-class star of similar dimensions to our sun which ranges between 26 and 72 AU away from the brighter pair, taking 142 years to complete a revolution. Further out still, at a distance of 1700 AU, are two red dwarfs of magnitudes 11 and 13. If they are part of the multiple system, they take 28000 years to complete and orbit. Also called Markeb, Kappa appears as a blue-white star of spectral type B2IV-V and magnitude 2.47 but is in fact a spectroscopic binary. The two orbit around each other with a period of 116.65 days, but the size, mass and nature of the companion are as yet unclear.

text: '''Outer Planets Assessment Group''' (OPAG) - responsible for identifying the scientific priorities and pathways for exploration in the outer solar system

text: The Chitauri then counterattacked by infiltrating the Triskelion and capturing The Wasp. The Chitauri leader (known only by his former Nazi identity as Herr Kleiser) took the Wasp to a hidden Chitauri base in Arizona. However, their location was given away when a fleet of damaged Chitauri starships suddenly entered Earth's atmosphere to hover above the formerly secret base, claiming that they were fleeing major defeats across the galaxy by their intergalactic enemies and that the remainder of their forces are forced to the "backwaters" of the Milky Way Galaxy (i.e. Earth's solar system). Disregarding Herr Kleiser's long efforts, the Chitauri ordered him to destroy Earth and its solar system with a doomsday bomb as part of a scorched-earth policy and retreat to the "lower fourth-dimension". The Ultimates and all available S.H.I.E.L.D. and military forces immediately converged on the alien fleet.

text: The Chitauri then counterattacked by infiltrating the Triskelion and capturing

text: The Wasp

text: . The Chitauri leader (known only by his former

text: Nazi

text: identity as

text: Herr Kleiser

text: ) took the Wasp to a hidden Chitauri base in Arizona. However, their location was given away when a fleet of damaged Chitauri starships suddenly entered Earth's atmosphere to hover above the formerly secret base, claiming that they were fleeing major defeats across the galaxy by their intergalactic enemies and that the remainder of their forces are forced to the "backwaters" of the

text: Milky Way

text: Galaxy (i.e. Earth's

text: solar system

text: ). Disregarding Herr Kleiser's long efforts, the Chitauri ordered him to destroy Earth and its solar system with a doomsday bomb as part of a scorched-earth policy and retreat to the "lower fourth-dimension".

text: The Ultimates

text: and all available S.H.I.E.L.D. and military forces immediately converged on the alien fleet.

text: The term "solar collector" commonly refers to solar hot water panels, but may refer to installations such as solar parabolic troughs and solar towers; or basic installations such as solar air heaters. Concentrated solar power plants usually use the more complex collectors to generate electricity by heating a fluid to drive a turbine connected to an electrical generator. Simple collectors are typically used in residential and commercial buildings for space heating. The first solar thermal collector designed for building roofs was patented by William H. Goettl and called the "Solar heat collector and radiator for building roof".

text: The term "solar collector" commonly refers to

text: solar hot water panel

text: s, but may refer to installations such as

text: solar parabolic trough

text: s and

text: solar towers

text: ; or basic installations such as

text: solar air heat

text: ers.

text: Concentrated solar power

text: plants usually use the more complex collectors to generate

text: electricity

text: by heating a fluid to drive a

text: turbine

text: connected to an

text: electrical generator

text: . Simple collectors are typically used in residential and commercial buildings for space heating. The first solar thermal collector designed for building roofs was patented by William H. Goettl and called the "

entity_name: Solar heat collector and radiator for building roof

text: Solar heat collector and radiator for building roof

text: Observations in 2004 revealed the presence of an inner belt containing silicate material at a distance of 6.4 AU from the star. Silicate material was also detected at 16 and 30 AU from the star, with a lack of dust between 6.4 and 16 AU providing evidence that a massive planet may be orbiting in this region. Magnesium-rich olivine has also been detected, strikingly similar to that found in the Solar System comets and different from the olivine found in Solar System asteroids. Olivine crystals can only form closer than 10 AU from the star; therefore they have been transported to the belt after formation, probably by radial mixing.

text: Observations in 2004 revealed the presence of an inner belt containing

text: silicate

text: material at a distance of 6.4 AU from the star. Silicate material was also detected at 16 and 30 AU from the star, with a lack of dust between 6.4 and 16 AU providing evidence that a massive planet may be orbiting in this region. Magnesium-rich

text: olivine

text: has also been detected, strikingly similar to that found in the Solar System

text: comets

text: and different from the olivine found in Solar System asteroids. Olivine crystals can only form closer than 10 AU from the star; therefore they have been transported to the belt after formation, probably by

text: radial mixing

text: Before the introduction of dynamo electric machines, voltaic, or primary, batteries were extensively used for electro-plating and in telegraphy. There are two distinct types of voltaic cells, namely, the "open" and the "closed", or "constant", type. The open type in brief is that type which operated on closed circuit becomes, after a short time, polarized; that is, gases are liberated in the cell which settle on the negative plate and establish a resistance that reduces the current strength. After a brief interval of open circuit these gases are eliminated or absorbed and the cell is again ready for operation. Closed circuit cells are those in which the gases in the cells are absorbed as quickly as liberated and hence the output of the cell is practically uniform. The Leclanché and Daniell cells, respectively, are familiar examples of the "open" and "closed" type of voltaic cell. The "open" cells are used very extensively at present, especially in the dry cell form, and in annunciator and other open circuit signal systems. Batteries of the Daniell or "gravity" type were employed almost generally in the United States and Canada as the source of electromotive force in telegraphy before the dynamo machine became available, and still are largely used for this service or as "local" cells. Batteries of the "gravity" and the Edison-Lalande types are still much used in "closed circuit" systems.

text: Before the introduction of dynamo electric machines, voltaic, or primary, batteries were extensively used for electro-plating and in telegraphy. There are two distinct types of voltaic cells, namely, the "open" and the "closed", or "constant", type. The open type in brief is that type which operated on closed circuit becomes, after a short time, polarized; that is, gases are liberated in the cell which settle on the negative plate and establish a resistance that reduces the current strength. After a brief interval of open circuit these gases are eliminated or absorbed and the cell is again ready for operation. Closed circuit cells are those in which the gases in the cells are absorbed as quickly as liberated and hence the output of the cell is practically uniform. The

text: Leclanché

text: and

text: Daniell cell

text: s, respectively, are familiar examples of the "open" and "closed" type of voltaic cell. The "open" cells are used very extensively at present, especially in the dry cell form, and in

text: annunciator

text: and other open circuit signal systems. Batteries of the Daniell or "gravity" type were employed almost generally in the United States and Canada as the source of electromotive force in telegraphy before the dynamo machine became available, and still are largely used for this service or as "local" cells. Batteries of the "gravity" and the

text: Edison-Lalande

text: types are still much used in "closed circuit" systems.

text: Except for the largest, which are in hydrostatic equilibrium, natural satellites (moons) differ from small Solar System bodies not in size, but in their orbits. The orbits of natural satellites are not centered on the Sun, but around other Solar System objects such as planets, dwarf planets, and small Solar System bodies.

text: Except for the largest, which are in

text: hydrostatic equilibrium

text: natural satellite

text: s (moons) differ from small Solar System bodies not in size, but in their orbits. The orbits of natural satellites are not centered on the

text: Sun

text: , but around other Solar System objects such as planets,

text: dwarf planet

text: s, and small Solar System bodies.

text: The Exoplanet Data Explorer lists extrasolar planets up to 24 Jupiter masses.

text: The

text: Exoplanet Data Explorer

text: lists

text: extrasolar planets

text: up to 24 Jupiter masses.

text: Various scientists have speculated that the Solar System's path through the galaxy is a factor in the periodicity of mass extinctions observed in the Earth's fossil record. One hypothesis supposes that vertical oscillations made by the Sun as it orbits the Galactic Centre cause it to regularly pass through the galactic plane. When the Sun's orbit takes it outside the galactic disc, the influence of the galactic tide is weaker; as it re-enters the galactic disc, as it does every 20–25 million years, it comes under the influence of the far stronger "disc tides", which, according to mathematical models, increase the flux of Oort cloud comets into the Solar System by a factor of 4, leading to a massive increase in the likelihood of a devastating impact.

text: Various scientists have speculated that the Solar System's path through the galaxy is a factor in the periodicity of

text: mass extinction

text: s observed in the Earth's

text: fossil record

text: . One hypothesis supposes that vertical oscillations made by the Sun as it orbits the Galactic Centre cause it to regularly pass through the galactic plane. When the Sun's orbit takes it outside the galactic disc, the influence of the

text: galactic tide

text: is weaker; as it re-enters the galactic disc, as it does every 20–25 million years, it comes under the influence of the far stronger "disc tides", which, according to mathematical models, increase the flux of

text: Oort cloud

text: comets into the Solar System by a factor of 4, leading to a massive increase in the likelihood of a devastating impact.

text: Jeans, in 1931,  divided the various models into 2 groups: those where the material for planet formation came from the Sun and those where it didn't and may be concurrent or consecutive. 		William McCrea, in 1963, divided them into 2 groups also: those that relate the formation of the planets to the formation of the Sun and those where it is independent of the formation of the Sun, where the planets form after the Sun becomes a normal star.

text: The fundamental plane is the plane of the Earth's orbit, called the ecliptic plane.  There are two principal variants of the ecliptic coordinate system: geocentric ecliptic coordinates centered on the Earth and heliocentric ecliptic coordinates centered on the center of mass of the solar system.

text: The Flagship Program is a series of NASA missions to explore the Solar System. It is the largest and most expensive of three classes of NASA Solar System Programs, the other two being the medium-cost New Frontiers Program and the lowest-cost Discovery Program.

text: The Flagship Program is a series of

text: NASA

text: missions to explore the

text: Solar System

text: . It is the largest and most expensive of three classes of NASA Solar System Programs, the other two being the medium-cost

text: New Frontiers Program

text: and the lowest-cost

text: Discovery Program

text: Weinbaum's solar system corresponds to the scientific solar system as envisioned in the mid-1930s, with details supplied from Weinbaum's imagination.  By 1934, the solar system was known to consist of the Sun, nine planets, 26 moons, and a few thousand asteroids and comets.  Unlike the solar system as known today, Weinbaum's system was full of life-forms, many of them intelligent; however, only the humans of Earth possessed the capacity for spaceflight (though there is evidence the Martians may have had it in the past). Weinbaum limited himself to planets and moons as settings, naming the following:

text: Several natural satellites in the Solar System have atmospheres and are subject to atmospheric loss processes. They typically have no magnetic fields of their own, but orbit planets with powerful magnetic fields. Many of these moons lie within the magnetic fields generated by the planets and are less likely to undergo sputtering and pick-up. The shape of the bow shock, however, allows for some moons, such as Titan, to pass through the bow shock when their orbits take them between the Sun and their primary. Titan spends roughly half of its transit time outside of the bow-shock and being subjected to unimpeded solar winds. The kinetic energy gained from pick-up and sputtering associated with the solar winds increases thermal escape throughout the transit of Titan, causing neutral hydrogen to escape. The escaped hydrogen maintains an orbit following in the wake of Titan, creating a neutral hydrogen torus around Saturn. Io, in its transit around Jupiter, encounters a plasma cloud. Interaction with the plasma cloud induces sputtering, kicking off sodium particles. The interaction produces a stationary banana-shaped charged sodium cloud along a part of the orbit of Io.

text: Several

text: natural satellite

text: s in the

text: Solar System

text: have atmospheres and are subject to atmospheric loss processes. They typically have no magnetic fields of their own, but orbit planets with powerful magnetic fields. Many of these moons lie within the magnetic fields generated by the planets and are less likely to undergo

text: sputtering

text: and pick-up. The shape of the

text: bow shock

text: , however, allows for some moons, such as

text: Titan

text: , to pass through the bow shock when their orbits take them between the Sun and their primary. Titan spends roughly half of its transit time outside of the bow-shock and being subjected to unimpeded solar winds. The

text: kinetic energy

text: gained from pick-up and sputtering associated with the solar winds increases thermal escape throughout the transit of Titan, causing neutral hydrogen to escape. The escaped hydrogen maintains an orbit following in the wake of Titan, creating a neutral hydrogen

text: torus

text: around Saturn.

text: Io

text: , in its transit around Jupiter, encounters a plasma cloud. Interaction with the

text: plasma

text: cloud induces sputtering, kicking off

text: sodium

text: particles. The interaction produces a stationary

text: banana

text: -shaped charged sodium cloud along a part of the orbit of Io.

text: A breakthrough in astronomy was made by Polish astronomer Nicolaus Copernicus (1473–1543) when, in 1543, he proposed a heliocentric model of the Solar system, ostensibly as a means to render tables charting planetary motion more accurate and to simplify their production. In heliocentric models of the Solar system, the Earth orbits the Sun along with other bodies in Earth's galaxy, a contradiction according to the Greek-Egyptian astronomer Ptolemy (2nd century CE; see above), whose system placed the Earth at the center of the Universe and had been accepted for over 1,400 years. The Greek astronomer Aristarchus of Samos (c.310 – c.230 BCE) had suggested that the Earth revolves around the Sun, but Copernicus' theory was the first to be accepted as a valid scientific possibility. Copernicus' book presenting the theory (De revolutionibus orbium coelestium, "On the Revolutions of the Celestial Spheres") was published just before his death in 1543 and, as it is now generally considered to mark the beginning of modern astronomy, is also considered to mark the beginning of the Scientific revolution. Copernicus' new perspective, along with the accurate observations made by Tycho Brahe, enabled German astronomer Johannes Kepler (1571–1630) to formulate his laws regarding planetary motion that remain in use today.

text: A breakthrough in

text: astronomy

text: was made by Polish astronomer

text: Nicolaus Copernicus

text: (1473–1543) when, in 1543, he proposed a

text: heliocentric model

text: of the

text: Solar system

text: , ostensibly as a means to render tables charting planetary motion more accurate and to simplify their production. In heliocentric models of the Solar system, the Earth orbits the Sun along with other bodies in

text: Earth's

text: galaxy

text: , a contradiction according to the Greek-Egyptian astronomer Ptolemy (2nd century CE; see above),

text: whose system

text: placed the Earth at the center of the Universe and had been accepted for over 1,400 years. The Greek astronomer

text: Aristarchus of Samos

text: (c.310 – c.230 BCE) had suggested that the Earth revolves around the Sun, but Copernicus' theory was the first to be accepted as a valid scientific possibility. Copernicus' book presenting the theory (

text: De revolutionibus orbium coelestium

text: , "On the Revolutions of the Celestial Spheres") was published just before his death in 1543 and, as it is now generally considered to mark the beginning of modern astronomy, is also considered to mark the beginning of the Scientific revolution. Copernicus' new perspective, along with the accurate observations made by

text: Tycho Brahe

text: , enabled German astronomer

text: Johannes Kepler

text: (1571–1630) to formulate

text: his laws regarding planetary motion

text: that remain in use today.

text: A photovoltaic system, or solar PV system is a power system designed to supply usable solar power by means of photovoltaics. It consists of an arrangement of several components, including solar panels to absorb and directly convert sunlight into electricity, a solar inverter to change the electric current from DC to AC, as well as mounting, cabling and other electrical accessories. PV systems range from small, roof-top mounted or building-integrated systems with capacities from a few to several tens of kilowatts, to large utility-scale power stations of hundreds of megawatts. Nowadays, most PV systems are grid-connected, while stand-alone systems only account for a small portion of the market.

text: A photovoltaic system, or solar PV system is a power system designed to supply usable solar power by means of photovoltaics. It consists of an arrangement of several components, including solar panels to absorb and directly convert sunlight into electricity, a solar inverter to change the electric current from DC to AC, as well as mounting, cabling and other electrical accessories. PV systems range from small,

text: roof-top mounted

text: or

text: building-integrated

text: systems with capacities from a few to several tens of

text: kilowatts

text: , to large utility-scale

text: power stations

text: of hundreds of

text: megawatts

text: . Nowadays, most PV systems are

entity_name: Grid-connected photovoltaic power system

text: grid-connected

text: , while

text: stand-alone

text: systems only account for a small portion of the market.

text: The seven largest natural satellites in the Solar System (those bigger than 2,500 km across) are Jupiter's Galilean moons (Ganymede, Callisto, Io, and Europa), Saturn's moon Titan, Earth's moon, and Neptune's captured natural satellite Triton. Triton, the smallest of these, has more mass than all smaller natural satellites together. Similarly in the next size group of nine natural satellites, between 1,000 km and 1,600 km across, Titania, Oberon, Rhea, Iapetus, Charon, Ariel, Umbriel, Dione, and Tethys, the smallest, Tethys, has more mass than all smaller natural satellites together. As well as the natural satellites of the various planets, there are also over 80 known natural satellites of the dwarf planets, minor planets and other small Solar System bodies. Some studies estimate that up to 15% of all trans-Neptunian objects could have satellites.

text: The seven largest

text: natural satellites

text: in the

text: Solar System

text: (those bigger than 2,500 km across) are

text: Jupiter

text: 's

text: Galilean moon

text: s (

text: Ganymede

text: Callisto

text: Io

text: , and

text: Europa

text: Saturn

text: 's moon

text: Titan

text: , Earth's

text: moon

text: , and

text: Neptune

text: 's captured natural satellite

text: Triton

text: . Triton, the smallest of these, has more mass than all smaller natural satellites together. Similarly in the next size group of nine natural satellites, between 1,000 km and 1,600 km across,

text: Titania

text: Oberon

text: Rhea

text: Iapetus

text: Charon

text: Ariel

text: Umbriel

text: Dione

text: , and

text: Tethys

text: , the smallest, Tethys, has more mass than all smaller natural satellites together. As well as the natural satellites of the various planets, there are also over 80 known natural satellites of the

text: dwarf planet

text: s,

text: minor planet

text: s and other

text: small Solar System bodies

text: . Some studies estimate that up to 15% of all

text: trans-Neptunian object

text: s could have satellites.

text: The grand tack scenario ignores the ongoing accretion of gas on Jupiter and Saturn.  In fact, to drive outward migration and move the planets to the proximity of their current orbits, the solar nebula had to contain a sufficiently large reservoir of gas around the orbits of the two planets. However, this gas would provide a source for accretion, which would affect the growth of Jupiter and Saturn and their mass ratio.  The type of nebula density required for capture in the 3:2 mean-motion resonance is especially dangerous for the survival of the two planets, because it can lead to significant mass growth and ensuing planet-planet scattering. But conditions leading to 2:1 mean-motion resonant systems may also put the planets at danger.

text: Considering the Earth–Moon system as a binary planet, its centre of gravity is within Earth, about  or 72.6% of the Earth's radius from the centre of the Earth. This centre of gravity remains on the line between the centres of the earth and Moon as the Earth completes its diurnal rotation. The path of the Earth–Moon system in its solar orbit is defined as the movement of this mutual centre of gravity around the sun. Consequently, Earth's centre veers inside and outside the solar orbital path during each synodic month as the Moon moves in its orbit around the common centre of gravity.

text: Considering the Earth–Moon system as a

text: binary planet

text: , its centre of gravity is within Earth, about  or 72.6% of the Earth's radius from the centre of the Earth. This centre of gravity remains on the line between the centres of the earth and Moon as the Earth completes its diurnal rotation. The path of the Earth–Moon system in its solar orbit is defined as the movement of this mutual centre of gravity around the sun. Consequently, Earth's centre veers inside and outside the solar orbital path during each synodic month as the Moon moves in its orbit around the common centre of gravity.

text: After Greek astronomy was transmitted to the medieval Islamic world, astronomers made some changes to Ptolemy's cosmological model, but did not greatly change his estimate of the Earth–Sun distance. For example, in his introduction to Ptolemaic astronomy, al-Farghānī gave a mean solar distance of  Earth radii, whereas in his zij, al-Battānī used a mean solar distance of  Earth radii. Subsequent astronomers, such as al-Bīrūnī, used similar values. Later in Europe, Copernicus and Tycho Brahe also used comparable figures ( and  Earth radii), and so Ptolemy's approximate Earth–Sun distance survived through the 16th century.

text: After Greek astronomy was transmitted to the medieval Islamic world, astronomers made some changes to Ptolemy's cosmological model, but did not greatly change his estimate of the Earth–Sun distance. For example, in his introduction to Ptolemaic astronomy,

entity_name: Ahmad ibn Muhammad ibn Kathir al-Farghani

text: al-Farghānī

text: gave a mean solar distance of  Earth radii, whereas in his

text: zij

text: al-Battānī

text: used a mean solar distance of  Earth radii. Subsequent astronomers, such as

text: al-Bīrūnī

text: , used similar values. Later in Europe,

text: Copernicus

text: and

text: Tycho Brahe

text: also used comparable figures ( and  Earth radii), and so Ptolemy's approximate Earth–Sun distance survived through the 16th century.

text: The Kepler problem derives its name from Johannes Kepler, who worked as an assistant to the Danish astronomer Tycho Brahe.  Brahe took extraordinarily accurate measurements of the motion of the planets of the Solar System.  From these measurements, Kepler was able to formulate Kepler's laws, the first modern description of planetary motion:

text: The Kepler problem derives its name from

text: Johannes Kepler

text: , who worked as an assistant to the Danish astronomer

text: Tycho Brahe

text: .  Brahe took extraordinarily accurate measurements of the motion of the planets of the Solar System.  From these measurements, Kepler was able to formulate

text: Kepler's laws

text: , the first modern description of planetary motion:

text: In physics, a gravitational field is a model used to explain the influence that a massive body extends into the space around itself, producing a force on another massive body. Thus, a gravitational field is used to explain gravitational phenomena, and is measured in newtons per kilogram (N/kg). In its original concept, gravity was a force between point masses. Following Newton, Laplace attempted to model gravity as some kind of radiation field or fluid, and since the 19th century explanations for gravity have usually been taught in terms of a field model, rather than a point attraction.

text: In

text: physics

text: , a gravitational field is a

text: model

text: used to explain the influence that a massive body extends into the space around itself, producing a force on another massive body. Thus, a gravitational field is used to explain

text: gravitation

text: al phenomena, and is measured in

text: newtons

text: per

text: kilogram

text: (N/kg). In its original concept,

text: gravity

text: was a

text: force

text: between point

text: mass

text: es. Following

text: Newton

text: Laplace

text: attempted to model gravity as some kind of

text: radiation

text: field or

text: fluid

text: , and since the 19th century explanations for gravity have usually been taught in terms of a field model, rather than a point attraction.

text: In the outer Solar System, comets remain frozen and are extremely difficult or impossible to detect from Earth due to their small size. Statistical detections of inactive comet nuclei in the Kuiper belt have been reported from the Hubble Space Telescope observations, but these detections have been questioned, and have not yet been independently confirmed. As a comet approaches the inner Solar System, solar radiation causes the volatile materials within the comet to vaporize and stream out of the nucleus, carrying dust away with them. The streams of dust and gas thus released form a huge, extremely tenuous atmosphere around the comet called the coma, and the force exerted on the coma by the Sun's radiation pressure and solar wind cause an enormous tail to form, which points away from the Sun.

text: In the outer

text: Solar System

text: , comets remain frozen and are extremely difficult or impossible to detect from Earth due to their small size. Statistical detections of inactive comet nuclei in the

text: Kuiper belt

text: have been reported from the

text: Hubble Space Telescope

text: observations, but these detections have been questioned, and have not yet been independently confirmed. As a comet approaches the inner Solar System,

text: solar radiation

text: causes the volatile materials within the comet to vaporize and stream out of the nucleus, carrying dust away with them. The streams of

text: dust

text: and gas thus released form a huge, extremely tenuous atmosphere around the comet called the

text: coma

text: , and the force exerted on the coma by the Sun's

text: radiation pressure

text: and

text: solar wind

text: cause an enormous tail to form, which points away from the Sun.

text: The Kuiper belt, sometimes called the Edgeworth–Kuiper belt, is a region of the Solar System beyond the planets extending from the orbit of Neptune (at 30 AU) to approximately 55 AU from the Sun. It is similar to the asteroid belt, although it is far larger; 20 times as wide and 20–200 times as massive. Like the asteroid belt, it consists mainly of small bodies (remnants from the Solar System's formation) and at least one dwarf planet—Pluto, wchich may be geologically active. But while the asteroid belt is composed primarily of rock and metal, the Kuiper belt is composed largely of ices, such as methane, ammonia, and water. The objects within the Kuiper belt, together with the members of the scattered disc and any potential Hills cloud or Oort cloud objects, are collectively referred to as trans-Neptunian objects (TNOs).

text: The Kuiper belt, sometimes called the Edgeworth–Kuiper belt, is a region of the

text: Solar System

text: beyond the planets extending from the

text: orbit

text: of

text: Neptune

text: (at 30

text: AU

text: ) to approximately 55 AU from the

text: Sun

text: . It is similar to the

text: asteroid belt

text: , although it is far larger; 20 times as wide and 20–200 times as massive. Like the asteroid belt, it consists mainly of

text: small bodies

text: (remnants from the Solar System's formation) and at least one

text: dwarf planet

text: Pluto

text: , wchich may be geologically active. But while the asteroid belt is composed primarily of

text: rock

text: and

text: metal

text: , the Kuiper belt is composed largely of

text: ice

text: s, such as

text: methane

text: ammonia

text: , and

text: water

text: . The objects within the Kuiper belt, together with the members of the

text: scattered disc

text: and any potential

text: Hills cloud

text: or

text: Oort cloud

text: objects, are collectively referred to as

text: trans-Neptunian object

text: s (TNOs).

text: When all densities are multiplied by 4, and all sizes are halved, orbits are similar; masses are divided by 2, gravitational forces are the same, gravitational accelerations are doubled. Hence velocities are the same and orbital periods are halved.

text: Some aspects of the definition are as yet difficult to apply outside the Solar System.  Techniques for identifying extrasolar objects generally cannot determine whether an object has "cleared its orbit", except indirectly via an orbit-clearing criterion.  The wording of the 2006 definition is heliocentric in its use of the word Sun instead of star or stars, and is thus not applicable to the numerous objects which have been identified in orbit around other stars. A separate "working" definition for extrasolar planets was, however, recommended by a working group of the IAU in 2003 and includes the criterion: "The minimum mass/size required for an extrasolar object to be considered a planet should be the same as that used in the Solar System."

text: Some aspects of the definition are as yet difficult to apply outside the Solar System.  Techniques for identifying extrasolar objects generally cannot determine whether an object has "cleared its orbit", except indirectly via an

text: orbit-clearing criterion

text: .  The wording of the 2006 definition is

text: heliocentric

text: in its use of the word

text: Sun

text: instead of

text: star

text: or

text: stars

text: , and is thus not applicable to the numerous

text: objects

text: which have been identified in orbit around other stars. A separate "working" definition for extrasolar planets was, however, recommended by a working group of the IAU in 2003 and includes the criterion: "The minimum mass/size required for an extrasolar object to be considered a planet should be the same as that used in the Solar System."

text: Callisto  (Jupiter IV) is the second-largest moon of Jupiter, after Ganymede. It is the third-largest moon in the Solar System and the largest object in the Solar System not to be properly  differentiated. Callisto was discovered in 1610 by Galileo Galilei. At  in diameter, Callisto has about 99% the diameter of the planet Mercury but only about a third of its mass. It is the fourth Galilean moon of Jupiter by distance, with an orbital radius of about . It is not in an orbital resonance like the three other Galilean satellites—Io, Europa, and Ganymede—and is thus not appreciably tidally heated. Callisto's rotation is tidally locked to its orbit around Jupiter, so that the same hemisphere always faces inward; Jupiter appears to stand nearly still in Callisto's sky. It is less affected by Jupiter's magnetosphere than the other inner satellites because of its more remote orbit, located just outside Jupiter's main radiation belt.

text: Callisto  (Jupiter IV) is the second-largest

text: moon of Jupiter

text: , after

text: Ganymede

text: . It is the

text: third-largest moon

text: in the

text: Solar System

text: and the largest object in the Solar System not to be properly

text: differentiated

text: . Callisto was discovered in 1610 by

text: Galileo Galilei

text: . At  in diameter, Callisto has about 99% the diameter of the planet

text: Mercury

text: but only about a third of its mass. It is the fourth

text: Galilean moon

text: of

text: Jupiter

text: by distance, with an orbital radius of about . It is not in an

text: orbital resonance

text: like the three other Galilean satellites—

text: Io

text: Europa

text: , and

text: Ganymede

text: —and is thus not appreciably

text: tidally heated

text: . Callisto's rotation is

text: tidally locked

text: to its orbit around Jupiter, so that the same hemisphere always faces inward; Jupiter appears to stand nearly still in Callisto's sky. It is less affected by Jupiter's

text: magnetosphere

text: than the other

text: inner satellite

text: s because of its more remote orbit, located just outside Jupiter's main radiation belt.

text: Several current scientific studies, including the Kepler mission, are aimed at refining estimates using real data from transiting planets. A 2008 study by astronomer Michael Meyer from the University of Arizona of cosmic dust near recently formed Sun-like stars suggests that between 20% and 60% of solar analogs have evidence for the formation of rocky planets, not unlike the processes that led to those of Earth. Meyer's team found discs of cosmic dust around stars and sees this as a byproduct of the formation of rocky planets.

text: Several current scientific studies, including the

text: Kepler mission

text: , are aimed at refining estimates using real data from transiting planets. A 2008 study by astronomer Michael Meyer from the University of Arizona of

text: cosmic dust

text: near recently formed Sun-like stars suggests that between 20% and 60% of solar analogs have evidence for the formation of

text: rocky planets

text: , not unlike the processes that led to those of Earth. Meyer's team found discs of cosmic dust around stars and sees this as a byproduct of the formation of rocky planets.

text: Scientists on one type of solar kite take pride that there will be a minimum of moving parts to control the movement of the solar kite through space and around the earth, moon, comet, or other solar system body. ESA CONTRACT 17679/03/NL/SFe Solar Kite Mission Feasibility Study EXECUTIVE SUMMARY Authors: C. Jack and C. Welch A collection of scientists and engineers are expanding the definition of what is a kite; the solar kite described by authors C. Jack and C. Welch has the inertia of the mass of the kite providing resistance against photonic flow; also, the controlling of the kite to alter the kite's acceleration sets up a kiting scenario: cause the kite to deflect away from the pull of gravity to keep the kite flying intended path supports the inclusion of the solar sail as a kite in photonic flow. The kite is fed start data; the kite tracks the stars and operates three elements to control its attitude to effect its deflections to result in the flight path desired by the ground-directing kite operators. The position of the payload is changed to alter the relative positions of the kite's center of pressure and center of mass; this is done in part by piezoelectric actuators. Also, the struts that hold the centered payload are differentially heated; such causes one of the struts to become longer than the cooler struts and thereby changing the center of mass relative to the center of pressure of the kite. Further, to cause an attitude change, tiny photo thrusters (heated wire) tweak the attitude of the kite; such thrusters do not propel the kite, but are only used to change the attitude of the kite's sail. These mechanisms aim to give authoritative control at minimum power use for giving direction to the kite.  Working solar kite groups are considering at least seventeen means of control of the solar kite/solar sail. West Group. Solar sail designing including a list of control options.

text: One of the most interesting problems is that of star formation. It is known that stars form out of the Interstellar Medium and that this mostly occurs in Giant Molecular Clouds such as the Rosette Nebula for example. It has been known for a long time that an interstellar cloud can collapse due to its self-gravity if it is large enough, but in the ordinary interstellar medium, this can only happen if the cloud has a mass of several thousand solar masses - much larger than that of any star. There must therefore be some process that fragments the cloud into smaller high density clouds whose masses are in the same range as that of stars. Self-gravity cannot do this, but it turns out that there are processes that do this if the magnetic pressure is much larger than the thermal pressure, as it is in Giant Molecular Clouds. These processes rely on the interaction of magnetohydrodynamic waves with a thermal instability. A magnetohydrodynamic wave in a medium in which the magnetic pressure is much larger than the thermal pressure can produce dense regions, but they cannot by themselves make the density high enough for self-gravity to act. However, the gas in star forming regions is heated by cosmic rays and is cooled by radiative processes. The net result is that gas in a thermal equilibrium state in which heating balances cooling can exist in three different phases at the same pressure: a warm phase with a low density, an unstable phase with intermediate density and a cold phase at low temperature. An increase in pressure, due to a supernova or a spiral density wave can flip the gas from the warm phase into the unstable phase and a Magnetohydrodynamic wave can then produce dense fragments in the cold phase whose self-gravity is strong enough for them to collapse to form stars .

text: In some multidimensional theories, the force of gravity is the only force with effect across all dimensions. This explains the relative weakness of gravity compared to the other forces of nature that cannot cross into extra dimensions. In that case, dark matter could exist in a "Hidden Valley" in other dimensions that only interact with the matter in our dimensions through gravity. That dark matter could potentially aggregate in the same way as ordinary matter, forming other-dimensional galaxies.

text: In some

text: multidimensional

text: theories, the force of gravity is the only force with effect across all dimensions. This explains the relative weakness of gravity compared to the other forces of nature that cannot cross into extra dimensions. In that case, dark matter could exist in a "Hidden Valley" in other dimensions that only interact with the matter in our dimensions through gravity. That dark matter could potentially aggregate in the same way as ordinary matter, forming other-dimensional galaxies.

text: An exoplanet causes its host star to move in a small orbit around the center of mass of the star-planet system. This 'wobble' can be observed if the radial velocity of the star is sufficiently high. This is the radial velocity method of detecting exoplanets. Using the mass function and the radial velocity of the host star, the minimum mass of an exoplanet can be determined. Applying this method on Proxima Centauri, the closest star to the solar system, led to the discovery of Proxima Centauri b, a terrestrial planet with a minimum mass of .

text: An

text: exoplanet

text: causes its host star to move in a small orbit around the center of mass of the star-planet system. This 'wobble' can be observed if the radial velocity of the star is sufficiently high. This is the

text: radial velocity method

text: of detecting exoplanets. Using the mass function and the radial velocity of the host star, the minimum mass of an exoplanet can be determined. Applying this method on

text: Proxima Centauri

text: , the closest star to the solar system, led to the discovery of

text: Proxima Centauri b

text: , a

text: terrestrial planet

text: with a minimum mass of .

text: Sedna has the longest orbital period of any known object in the Solar System of comparable size or larger, calculated at around 11,400 years. Its orbit is extremely eccentric, with an aphelion estimated at 937 AU and a perihelion at about 76 AU. This perihelion was the largest of that of any known Solar System object until the discovery of . When Sedna was discovered it was 89.6 AU from the Sun approaching perihelion, and was the most distant object in the Solar System observed. Eris was later detected by the same survey near aphelion at 97 AU. Only the orbits of some long-period comets extend farther than that of Sedna; they are too dim to be discovered except when approaching perihelion in the inner Solar System. Even as Sedna nears its perihelion in mid 2076, the Sun would appear merely as an extremely bright star-like pinpoint in its sky, 100 times brighter than a full moon on Earth (for comparison, the Sun appears from Earth to be roughly 400,000 times brighter than the full Moon), and too far away to be visible as a disc to the naked eye.

text: Sedna has the longest

text: orbital period

text: of any known object in the Solar System of comparable size or larger, calculated at around 11,400 years. Its

text: orbit

text: is extremely

text: eccentric

text: , with an

text: aphelion

text: estimated at 937 AU and a

text: perihelion

text: at about 76 AU. This perihelion was the largest of that of any known Solar System object until the discovery of . When Sedna was discovered it was 89.6 AU from the Sun approaching perihelion, and was the most distant object in the Solar System observed.

text: Eris

text: was later detected by the same survey near aphelion at 97 AU. Only the orbits of some long-period comets extend farther than that of Sedna; they are too dim to be discovered except when approaching perihelion in the inner Solar System. Even as Sedna nears its perihelion in mid 2076, the Sun would appear merely as an extremely bright star-like pinpoint in its sky, 100 times brighter than a full moon on Earth (for comparison, the Sun appears from Earth to be roughly 400,000 times brighter than the full Moon), and too far away to be visible as a disc to the naked eye.

text: The radial position of the condensation/evaporation front varies over time, as the nebula evolves. Occasionally, the term snow line is also used to represent the present distance at which water ice can be stable (even under direct sunlight). This current snow line distance is different from the formation snow line distance during the formation of Solar System, and approximately equals 5 AU. The reason for the difference is that during the formation of Solar System, the solar nebula was an opaque cloud where temperature were lower close to the Sun, and the Sun itself was less energetic. After formation, the ice got buried by infalling dust and it has remained stable a few meters below the surface. If ice within 5 AU is exposed, e.g. by a crater, then it sublimates on short timescales. However, out of direct sunlight ice can remain stable on the surface of asteroids (and the Moon) if it is located in permanently shadowed craters, where temperature may remain very low over the age of the Solar System (e.g. 30–40 K on the Moon).

text: Jupiter Barrier or Jupiter Saturn Barrier is the name for an effect of the gas giants (in particular Jupiter), that reduces the likelihood for objects from the outer Solar System (in particular from the Oort cloud) to reach the inner Solar System.

text: Jupiter Barrier or Jupiter Saturn Barrier is the name for an effect of the

text: gas giant

text: s (in particular

text: Jupiter

text: ), that reduces the likelihood for objects from the

text: outer Solar System

text: (in particular from the

text: Oort cloud

text: ) to reach the

text: inner Solar System

text: A more advanced version of a similarly themed technology is the Vortex engine (AVE) which aims to replace large physical chimneys with a vortex of air created by a shorter, less-expensive structure.Space-based solar power (SBSP) is the concept of collecting solar power in space (using an "SPS", that is, a "solar-power satellite" or a "satellite power system") for use on Earth. It has been in research since the early 1970s. SBSP would differ from current solar collection methods in that the means used to collect energy would reside on an orbiting satellite instead of on Earth's surface. Some projected benefits of such a system are a higher collection rate and a longer collection period due to the lack of a diffusing atmosphere and night time in space.

text: A more advanced version of a similarly themed technology is the

text: Vortex engine

text: (AVE) which aims to replace large physical chimneys with a

text: vortex

text: of air created by a shorter, less-expensive structure.Space-based solar power (SBSP) is the concept of collecting

text: solar power

text: in

text: space

text: (using an "SPS", that is, a "solar-power satellite" or a "satellite power system") for use on

text: Earth

text: . It has been in research since the early 1970s. SBSP would differ from current

text: solar

text: collection methods in that the means used to collect

text: energy

text: would reside on an

text: orbiting

text: satellite

text: instead of on Earth's surface. Some projected benefits of such a system are a higher collection rate and a longer collection period due to the lack of a diffusing

text: atmosphere

text: and night

text: time

text: in

text: space

text: There are three parameters that affect the size and shape of the analemma — obliquity, eccentricity, and the angle between the apse line and the line of solstices. Viewed from an object with a perfectly circular orbit and no axial tilt, the Sun would always appear at the same point in the sky at the same time of day throughout the year and the analemma would be a dot. For an object with a circular orbit but significant axial tilt, the analemma would be a figure of eight with northern and southern lobes equal in size. For an object with an eccentric orbit but no axial tilt, the analemma would be a straight east–west line along the celestial equator.

text: There are three parameters that affect the size and shape of the analemma —

text: obliquity

text: eccentricity

text: , and the angle between the

text: apse line

text: and the line of

text: solstice

text: s. Viewed from an object with a perfectly circular

text: orbit

text: and no axial tilt, the Sun would always appear at the same point in the sky at the same time of day throughout the year and the analemma would be a dot. For an object with a circular orbit but significant axial tilt, the analemma would be a figure of eight with northern and southern lobes equal in size. For an object with an eccentric orbit but no axial tilt, the analemma would be a straight east–west line along the celestial equator.

text: Detailed investigations into Kridsadaporn’s dynamic evolution have been carried out by creating 15 "clone" orbits, integrated forward over a period of 1.2 × 10 years, by changing the last digit of its orbital parameters. Nine (9) clones demonstrated moderate chaotic behaviour jumping between the Jovian mean-motion resonances of 15:7, 9:4, and 11:5 with some orbits becoming Earth-crossers within the integration period. The remaining six (6) clones grew in orbital eccentricity until becoming Jupiter-crossers, and then, behaving as Jupiter-family comets, they were ejected from the Solar System over periods in the order of 10 years.

text: Detailed investigations into Kridsadaporn’s dynamic evolution have been carried out by creating 15 "clone" orbits, integrated forward over a period of 1.2 × 10 years, by changing the last digit of its orbital parameters. Nine (9) clones demonstrated moderate chaotic behaviour jumping between the Jovian mean-motion resonances of 15:7, 9:4, and 11:5 with some orbits becoming

text: Earth-crossers

text: within the integration period. The remaining six (6) clones grew in orbital eccentricity until becoming

text: Jupiter-crossers

text: , and then, behaving as Jupiter-family comets, they were ejected from the Solar System over periods in the order of 10 years.

text: Thus only the product of G and M is needed to predict the motion of the smaller body. Conversely, measurements of the smaller body's orbit only provide information on the product, μ, not G and M separately. The gravitational constant, G, is difficult to measure with high accuracy, while orbits, at least in the solar system, can be measured with great precision and used to determine μ with similar precision.

text: In Astronomia nova (1609), Johannes Kepler had used an elliptical orbit to explain the motion of Mars. In Epitome astronomiae Copernicanae he developed a heliocentric model of the solar system in which all the planets have elliptical orbits. This provided significantly increased accuracy in predicting the position of the planets. Kepler's ideas were not immediately accepted. Galileo for example completely ignored Kepler's work. Kepler proposed Heliocentrism as a physical description of the solar system and Epitome astronomia Copernicanae was placed on the index of prohibited books despite Kepler being a Protestant.

text: In

text: Astronomia nova

text: Johannes Kepler

text: had used an elliptical orbit to explain the motion of Mars. In

text: Epitome astronomiae Copernicanae

text: he developed a heliocentric model of the solar system in which all the planets have elliptical orbits. This provided significantly increased accuracy in predicting the position of the planets. Kepler's ideas were not immediately accepted. Galileo for example completely ignored Kepler's work. Kepler proposed Heliocentrism as a physical description of the solar system and Epitome astronomia Copernicanae was placed on the index of prohibited books despite Kepler being a Protestant.

text: Multiplayer.it said "A simple but solid franchise as Dark Nebula could only give birth to a high-quality sequel, but frankly we didn't expect so many new ideas. The graphics of the game, already excellent, have been further improved and now offer levels rich in details, well defined and unique. Episode Two is immediate and entertaining as Episode One, the tilt controls are very accurate and the action is characterized by a continuous introduction of new challenges to overcome. A must buy. " Touchgen said "Dark Nebula Episode Two is a triumph of budget game design on the AppStore. " 148apps wrote "We loved Dark Nebula: Episode One, but were saddened by its length-Episode Two "only" has twenty levels, but they're all fantastic. " IGN said "Bring on episode three. Dark Nebula is a frenzied tilt game that bangs you over the head every stage with new challenges like laser tripwires, twirling blades, tricky jumps, and boss battles. " Eurogamer said "Hours are casually tossed aside in the process of ensuring that a ball safely reaches its destination, via moving walkways, spiked traps, bounce pads, industrial crushers and laser fire. "

text: In FINAL, Hana is the one with whom the introduction begins, taking a litter of her dog's puppies on a walk when she finds the wounded Ikumi Kaidou (Arma) engaged in combat with Repli-Mamoru.  After the battle concludes (leading to the destruction of a harbor but leaving Hana and her dogs unscathed), Hana takes the unconscious Kaidou back to her home and questions him as to Mamoru's actions and whereabouts.  As the actions in the Trinary Solar System continue, Hana is often looked in upon to show the degradation of the situation on Earth.  Despite the destruction being wrought upon the Earth, Hana remains determined that she will see Mamoru again.  In the finale, she gets her wish, and is seen standing side-by-side with Mamoru and Kaidou before the memorial erected in honor of the GGG members who went missing in the crisis.  She is also one of the singers for the first verse of Someday in the Sea of Stars: Character Version, which plays during said finale.

text: orbits of size 1 and there are no orbits of size p.  Thus we first obtain Babbage's theorem

text: It is a common misconception that this collision will disrupt the orbits of the planets in the Solar System. Although it is true that the gravity of passing stars can detach planets into interstellar space, distances between stars are so great that the likelihood of the Milky Way–Andromeda collision causing such disruption to any individual star system is negligible. Although the Solar System as a whole could be affected by these events, the Sun and planets are not expected to be disturbed.

text: In the distant future, the Earth's resources have been depleted, and many of earth's inhabitants are moving to the new, artificial solar system called IOTA Synthetica. The solar system, like all the solar systems created by the  "Galactic Federation", is very hip and up-scale.

text: Planetary objects that form in the outer Solar System begin as a comet-like mixture of roughly half water and half rock by mass. Simulations of Solar System formation and of extra-solar system formation have shown that planets are likely to migrate inward (i.e., toward the star) as they form.  Outward migration may also occur under particular conditions.  Inward migration presents the possibility that icy planets could move to orbits where their ice melts into liquid form, turning them into ocean planets.  This possibility was first discussed in the professional astronomical literature by Marc Kuchner and Alain Léger in 2003.

text: Planetary objects that form in the outer

text: Solar System

text: begin as a

text: comet

text: -like mixture of roughly half water and half rock by mass. Simulations of

text: Solar System formation

text: and of

text: extra-solar system formation

text: have shown that planets are likely to

text: migrate

text: inward (i.e., toward the star) as they form.  Outward migration may also occur under particular conditions.  Inward migration presents the possibility that

text: icy planet

text: s could move to orbits where their ice melts into liquid form, turning them into ocean planets.  This possibility was first discussed in the professional astronomical literature by

text: Marc Kuchner

text: and

text: Alain Léger

text: in 2003.

text: A 'Stonyhurst disk' is used to determine the longitude and latitude of sunspots. The Earth doesn't orbit precisely around the Sun's equator, so through the year the center of solar pictures moves up and down a little more than 7 degrees. This angle varies sinusoidally through the year and is called B0. Earth crosses the Sun's equator about December 7 and June 7 each year. This means that the lines of latitude on the sun do not appear as lines from the earth, but as elliptical arcs. Sunspots and other features will rotate across the face of the sun along lines of latitude. Stonyhurst disks are transparent overlays that match the size of whole-disk images of the sun. These disks provide a graphic means of locating sunspots on the solar disk in reference to lines of latitude and longitude. Different disk overlays are produced for different dates.

text: A 'Stonyhurst disk' is used to determine the longitude and latitude of sunspots. The Earth doesn't orbit precisely around the Sun's equator, so through the year the center of solar pictures moves up and down a little more than 7 degrees. This angle varies

text: sinusoidal

text: ly through the year and is called B0. Earth crosses the Sun's equator about December 7 and June 7 each year. This means that the lines of latitude on the sun do not appear as lines from the earth, but as elliptical arcs. Sunspots and other features will rotate across the face of the sun along lines of latitude. Stonyhurst disks are transparent overlays that match the size of whole-disk images of the sun. These disks provide a graphic means of locating sunspots on the solar disk in reference to lines of latitude and longitude. Different disk overlays are produced for different dates.

text: An extrasolar planet was detected orbiting it in 2000 by the Geneva Extrasolar Planet Search Team.  This exoplanet is "a gas giant smaller than Jupiter that screams around its primary [star]  in 11 days at only 0.1 AU." This is much closer than the orbit of Mercury in the Solar System.

text: An

text: extrasolar planet

text: was detected orbiting it in 2000 by the

text: Geneva Extrasolar Planet Search Team

text: .  This exoplanet is "a gas giant smaller than

text: Jupiter

text: that screams around its primary [star]  in 11 days at only 0.1 AU." This is much closer than the orbit of

text: Mercury

text: in the

text: Solar System

text: While no water gas was found to be associated with the warm dust belt, two concentrations of icy material were found in the system.  The first belt lies between 4 and 9 AU, and is at the equivalent position of the solar system's asteroid belt, while the second belt is even farther out between 30 and 80 AU, where the solar system's Kuiper Belt would lie. This material may be the source of future water for the rocky planet at 1.8 AU if and when it completes its formation.

text: While no water gas was found to be associated with the warm dust belt, two concentrations of icy material were found in the system.  The first belt lies between 4 and 9

text: AU

text: , and is at the equivalent position of the solar system's asteroid belt, while the second belt is even farther out between 30 and 80

text: AU

text: , where the solar system's Kuiper Belt would lie. This material may be the source of future water for the rocky planet at 1.8

text: AU

text: if and when it completes its formation.

text: The positions and periods of the planets was calculated relative to uniformly moving points. In the case of Mercury and Venus, they move around the Earth at the same mean speed as the Sun. In the case of Mars, Jupiter, and Saturn, they move around the Earth at specific speeds, representing each planet's motion through the zodiac. Most historians of astronomy consider that this two-epicycle model reflects elements of pre-Ptolemaic Greek astronomy. Another element in Aryabhata's model, the śīghrocca, the basic planetary period in relation to the Sun, is seen by some historians as a sign of an underlying heliocentric model.

text: The positions and periods of the planets was calculated relative to uniformly moving points. In the case of Mercury and Venus, they move around the Earth at the same mean speed as the Sun. In the case of Mars, Jupiter, and Saturn, they move around the Earth at specific speeds, representing each planet's motion through the zodiac. Most historians of astronomy consider that this two-epicycle model reflects elements of pre-Ptolemaic

text: Greek astronomy

text: . Another element in Aryabhata's model, the śīghrocca, the basic planetary period in relation to the Sun, is seen by some historians as a sign of an underlying

text: heliocentric

text: model.

text: Barycentric Coordinate Time (TCB, from the French Temps-coordonnée barycentrique) is a coordinate time standard intended to be used as the independent variable of time for all calculations pertaining to orbits of planets, asteroids, comets, and interplanetary spacecraft in the Solar system.  It is equivalent to the proper time experienced by a clock at rest in a coordinate frame co-moving with the barycenter of the Solar system: that is, a clock that performs exactly the same movements as the Solar system but is outside the system's gravity well.  It is therefore not influenced by the gravitational time dilation caused by the Sun and the rest of the system.

text: Barycentric Coordinate Time (TCB, from the

text: French

text: Temps-coordonnée barycentrique) is a

text: coordinate

text: time standard

text: intended to be used as the independent variable of time for all calculations pertaining to orbits of

text: planet

text: s,

text: asteroid

text: s,

text: comet

text: s, and interplanetary

text: spacecraft

text: in the

text: Solar system

text: .  It is equivalent to the

text: proper time

text: experienced by a clock at rest in a coordinate frame

text: co-moving

text: with the

text: barycenter

text: of the Solar system: that is, a clock that performs exactly the same movements as the Solar system but is outside the system's

text: gravity well

text: .  It is therefore not influenced by the

text: gravitational time dilation

text: caused by the

text: Sun

text: and the rest of the system.

text: Jack West, President & CTO of Zep Solar, was inspired as a college student to end reliance on fossil fuels and then subsequently worked from 1990 to 2009 as a solar engineer designing and installing PV systems. West founded Zep Solar in 2009, along with Daniel Flanigan and Christina Manansala.

text: Of the many exoplanets discovered, most exoplanets have a higher orbital eccentricity than our solar system.  Exoplanets found with low orbital eccentricity, near circular orbits, are very close to its star and are tidal locked to the star, like planet Mercury. All eight planets in the Solar System have near-circular orbits.  The exoplanets discovered show that the solar system, with its unusually low eccentricity, is rare and unique. One theory attributes this low eccentricity to the high number of planets in the Solar System; another suggests it arose because of its unique asteroid belts. A few other multiplanetary systems have been found, but none resemble the solar system. The solar system has unique planetesimal systems, which led the planets to have near-circular orbits. Solar planetesimal systems include the asteroid belt, Hilda family, Kuiper belt, Hills cloud, and the Oort cloud. The exoplanet solar systems discovered have either no planetesimal systems or one very large planetesimal system. Low eccentricity is needed for habitability, especially advanced life. High multiplicity planet systems are much more likely to have habitable exoplanets.  The Grand tack hypothesis of the solar system also helps understand the near-circular orbits of the solar system and the other unique features of the solar system.

text: Of the many

text: exoplanet

text: s discovered, most exoplanets have a higher orbital eccentricity than our solar system.  Exoplanets found with low orbital eccentricity, near circular orbits, are very close to its star and are

text: tidal locked

text: to the star, like

text: planet Mercury

text: . All eight planets in the Solar System have near-circular orbits.  The exoplanets discovered show that the solar system, with its unusually low eccentricity, is rare and unique. One theory attributes this low eccentricity to the high number of planets in the Solar System; another suggests it arose because of its unique asteroid belts. A few other

text: multiplanetary systems

text: have been found, but none resemble the solar system. The solar system has unique

text: planetesimal

text: systems, which led the planets to have near-circular orbits. Solar planetesimal systems include the

text: asteroid belt

text: Hilda family

text: Kuiper belt

text: Hills cloud

text: , and the

text: Oort cloud

text: . The exoplanet solar systems discovered have either no planetesimal systems or one very large planetesimal system. Low eccentricity is needed for habitability, especially advanced life. High multiplicity planet systems are much more likely to have habitable exoplanets.  The

text: Grand tack hypothesis

text: of the solar system also helps understand the near-circular orbits of the solar system and the other unique features of the solar system.

text: Weather is not limited to planetary bodies.  Like all stars, the sun's corona is constantly being lost to space, creating what is essentially a very thin atmosphere throughout the Solar System.  The movement of mass ejected from the Sun is known as the solar wind.  Inconsistencies in this wind and larger events on the surface of the star, such as coronal mass ejections, form a system that has features analogous to conventional weather systems (such as pressure and wind) and is generally known as space weather.  Coronal mass ejections have been tracked as far out in the solar system as Saturn.  The activity of this system can affect planetary atmospheres and occasionally surfaces.  The interaction of the solar wind with the terrestrial atmosphere can produce spectacular aurorae, and can play havoc with electrically sensitive systems such as electricity grids and radio signals.

text: Weather is not limited to planetary bodies.  Like all stars, the sun's

text: corona

text: is constantly being lost to space, creating what is essentially a very thin

text: atmosphere

text: throughout the

text: Solar System

text: .  The movement of mass ejected from the Sun is known as the

text: solar wind

text: .  Inconsistencies in this wind and larger events on the surface of the star, such as

text: coronal mass ejection

text: s, form a system that has features analogous to conventional weather systems (such as pressure and wind) and is generally known as

text: space weather

text: .  Coronal mass ejections have been tracked as far out in the

text: solar system

text: as

text: Saturn

text: .  The activity of this system can affect planetary

text: atmospheres

text: and occasionally surfaces.  The interaction of the

text: solar wind

text: with the terrestrial atmosphere can produce spectacular

text: aurorae

text: , and can play havoc with electrically sensitive systems such as

text: electricity grids

text: and radio signals.

text: The series covers topics concerning space exploration, the Solar System, and astronomical objects in the universe. It shows CGI renderings of these aforementioned, video footage, photographs, and views from scientists, project managers, engineers, advocates, writers and other experts.  The episode "7 Wonders of the Solar System", and Season 6 were produced in 3D.

text: The series covers topics concerning

text: space exploration

text: , the

text: Solar System

text: , and

text: astronomical objects

text: in the universe. It shows

text: CGI

text: renderings of these aforementioned, video footage, photographs, and views from scientists, project managers, engineers, advocates, writers and other experts.  The episode "

text: 7 Wonders of the Solar System

text: ", and Season 6 were produced in 3D.

text: K2-22b (also known as EPIC 201637175 b) is an exoplanet 734 ly from Earth, rapidly orbiting the red dwarf K2-22 with an orbital period of 9.145872 hours. It has an upper mass of 445 M and a radius of 2.5 R The planet was not detected in the K2 photometry. K2 photometry reveals the presence of an anomalous light curve consistent with evaporation of dust from the planet. This dust forms a tail both ahead and behind the planet, similar to some comets in the Solar System. The evaporation of this dust requires a low surface gravity from the host planet, implying it is a low mass, "Mars, Mercury, or even lunar sized bodies with surface gravities of 1/6 to 1/3 that of Earth are to be preferred."

text: -22b (also known as EPIC 201637175 b) is an

text: exoplanet

text: ly

text: from

text: Earth

text: , rapidly orbiting the

text: red dwarf

text: with an orbital period of 9.145872 hours. It has an upper mass of 445 M and a radius of 2.5 R The planet was not detected in the K2

text: photometry

text: . K2 photometry reveals the presence of an anomalous light curve consistent with evaporation of dust from the planet. This dust forms a tail both ahead and behind the planet, similar to some comets in the Solar System. The evaporation of this dust requires a low surface gravity from the host planet, implying it is a low mass, "Mars, Mercury, or even lunar sized bodies with surface gravities of 1/6 to 1/3 that of

text: Earth

text: are to be preferred."

text: The spacecraft is comparable in size and general shape to a grand piano and has been compared to a piano glued to a cocktail bar-sized satellite dish. As a point of departure, the team took inspiration from the Ulysses spacecraft, which also carried a radioisotope thermoelectric generator (RTG) and dish on a box-in-box structure through the outer Solar System. Many subsystems and components have flight heritage from APL's CONTOUR spacecraft, which in turn had heritage from APL's TIMED spacecraft.

text: The spacecraft is comparable in size and general shape to a

text: grand piano

text: and has been compared to a piano glued to a cocktail bar-sized satellite dish. As a point of departure, the team took inspiration from the

text: Ulysses

text: spacecraft, which also carried a

text: radioisotope thermoelectric generator

text: (RTG) and dish on a box-in-box structure through the outer Solar System. Many subsystems and components have flight heritage from APL's

text: CONTOUR

text: spacecraft, which in turn had heritage from APL's

text: TIMED

text: spacecraft.

text: "Is there life elsewhere in the universe?" is one of humankind's most profound unanswered questions. A step in the attempt to answer this question is the search for planets outside the Solar System. ESO's observatories are equipped with an arsenal of instruments for finding, studying, and monitoring extrasolar planets. In 2004, the Very Large Telescope detected a faint glow from an apparent planet orbiting a star about 200 light-years from earth. A year later, this detection was confirmed as the first picture of an exoplanet ever recorded. Although the planet is large (five times more massive than Jupiter), this observation is a first step toward identifying the physical structure and chemical composition of exoplanets.

text: "Is there life elsewhere in the universe?" is one of humankind's most profound unanswered questions. A step in the attempt to answer this question is the search for planets outside the Solar System. ESO's observatories are equipped with an arsenal of instruments for finding, studying, and monitoring

text: extrasolar planet

text: s. In 2004, the Very Large Telescope detected a faint glow from an apparent planet orbiting a star about 200 light-years from earth. A year later, this detection was confirmed as the first picture of an exoplanet ever recorded. Although the planet is large (five times more massive than

text: Jupiter

text: ), this observation is a first step toward identifying the physical structure and chemical composition of exoplanets.

text: Direct exploration of the Solar System has yielded no evidence indicating a visit by aliens or their probes. Detailed exploration of areas of the Solar System where resources would be plentiful may yet produce evidence of alien exploration, though the entirety of the Solar System is vast and difficult to investigate.  Attempts to signal, attract, or activate hypothetical Bracewell probes in Earth's vicinity have not succeeded.

text: An increasing number of extrasolar planet discoveries are being made with  planets in  planetary systems known. Rare Earth proponents argue life cannot arise outside Sun-like systems. However, some exobiologists have suggested that stars outside this range may give rise to life under the right circumstances; this possibility is a central point of contention to the theory because these late-K and M category stars make up about 82% of all hydrogen-burning stars.

text: An increasing number of

text: extrasolar planet

text: discoveries are being made with  planets in  planetary systems known. Rare Earth proponents argue life cannot arise outside Sun-like systems. However,

text: some exobiologists have suggested

text: that stars outside this range may give

text: rise to life

text: under the right circumstances; this possibility is a central point of contention to the theory because these late-K and M category stars make up about 82% of all hydrogen-burning stars.

text: HD 169830 b is an extrasolar planet three times the mass of Jupiter. Due to its high mass, it is most likely a gas giant planet, akin to Jupiter and Saturn in the Solar System. This planet at 0.8 AU is slightly farther out than Venus is in the Solar System, orbiting around its star every 262 days.

text: HD 169830 b is an

text: extrasolar planet

text: three times the

text: mass

text: of

text: Jupiter

text: . Due to its high mass, it is most likely a

text: gas giant

text: planet, akin to Jupiter and

text: Saturn

text: in the

text: Solar System

text: . This planet at 0.8 AU is slightly farther out than

text: Venus

text: is in the

text: Solar System

text: , orbiting around its star every 262 days.

text: This article describes extreme locations of the Solar System. Entries listed in bold are Solar System-wide extremes.

text: This article describes extreme locations of the

text: Solar System

text: . Entries listed in bold are Solar System-wide extremes.

text: 582 extrasolar planets (about 29.6% of the total) were discovered using Doppler spectroscopy, as of April 2016.

text: The planets are believed to be the result of a second round of planetary system formation as a result of two white dwarfs merging with each other into a pulsar and a resulting disk of material in orbit around the star. Other scenarios include unusual supernova remnants or a quark-nova. However, the white dwarf–white dwarf merge model seems to be the most likely cause of the formation of the planets.

text: The planets are believed to be the result of a second round of

text: planetary system

text: formation as a result of two

text: white dwarfs

text: merging with each other into a pulsar and a resulting disk of material in orbit around the star. Other scenarios include unusual

text: supernova remnant

text: s or a

text: quark-nova

text: . However, the white dwarf–white dwarf merge model seems to be the most likely cause of the formation of the planets.

text: Check valves used in domestic heating systems to prevent vertical convection, especially in combination with solar thermal installations, also are called gravity brake.

text: Check valves used in domestic heating systems to prevent vertical convection, especially in combination with

text: solar thermal

text: installations, also are called gravity brake.

text: Planetary aberration is the combination of the aberration of light (due to Earth's velocity) and light-time correction (due to the object's motion and distance), as calculated in the rest frame of the Solar System. Both are determined at the instant when the moving object's light reaches the moving observer on Earth. It is so called because it is usually applied to planets and other objects in the Solar System whose motion and distance are accurately known.

text: The Master calls meditation “Surya Yoga” or “Yoga of the Sun” and it is a method that all disciples are encouraged to practice because it is at the heart of the teachings. Meditation is practiced between the Spring and Autumn equinoxes at sunrise. Sunrise is important because it is a time of renewal when the sun’s rays help to transform and renew meditators. In meditation, the practitioner concentrates their thoughts and forces on the sun to reinforce their connection with their spirit. Just as the sun is the center of the solar system, through meditation practitioners connect with their spirit, the center of their being. Meditation allows paths of communication to be established through bridges between people’s higher and lower natures.

text: Growing the star will increase its gravitational force, which increases the number of planets the solar system can have. They will also be able to attract solar systems composed of stars with lower mass than that of the player, or being attracted to stars with bigger mass. If both stars collide, they will be reduced to a lesser size within the same type of object. For example, if the player controls a small star and collides against a medium star, the player will be disintegrated while the AI-controlled star will be reduced to a small star. Being reduced from small star to life planet is not possible, as well as being reduced from small planet to asteroid. In these cases, the player is respawned, with random mass, close to the place where they collided.

text: Growing the star will increase its gravitational force, which increases the number of planets the solar system can have. They will also be able to attract solar systems composed of stars with lower mass than that of the player, or being attracted to stars with bigger mass. If both stars collide, they will be reduced to a lesser size within the same type of object. For example, if the player controls a small star and collides against a medium star, the player will be disintegrated while the AI-controlled star will be reduced to a small star. Being reduced from small star to life planet is not possible, as well as being reduced from small planet to asteroid. In these cases, the player is

text: respawned

text: , with random mass, close to the place where they collided.

text: SIM's new technology was meant to lead to the development of telescopes powerful enough to take images of Earth-like extrasolar planets orbiting distant stars and to determine whether those planets are able to sustain life. NASA has already started developing future missions that will build on SIM's technological legacy. The technological development phase of the mission was completed in November 2006 with the announcement that the eight, mission-technology-milestones set by NASA were reached. The milestones were necessary steps in the technological development before flight control instruments could begin to be designed. The completion of each milestone meant that new systems had to be developed for nanometer control as well as picometer knowledge technology; these systems enable the telescope to make its accurate measurements with extreme accuracy.

text: SIM's new technology was meant to lead to the development of telescopes powerful enough to take images of Earth-like

text: extrasolar planets

text: orbiting distant stars and to determine whether those planets are

text: able to sustain life

text: . NASA has already started developing future missions that will build on SIM's technological legacy. The technological development phase of the mission was completed in November 2006 with the announcement that the eight, mission-technology-milestones set by NASA were reached. The milestones were necessary steps in the technological development before flight control instruments could begin to be designed. The completion of each milestone meant that new systems had to be developed for

text: nanometer

text: control as well as

text: picometer

text: knowledge technology; these systems enable the telescope to make its accurate measurements with extreme accuracy.

text: In 1979, Freitas and Valdes conducted a photographic search of the vicinity of the Earth-Moon triangular libration points  and , and of the solar-synchronized positions in the associated halo orbits, seeking possible orbiting extraterrestrial interstellar probes, but found nothing to a detection limit of about 14th magnitude. The authors conducted a second, more comprehensive photographic search for probes in 1982 that examined the five Earth-Moon Lagrangian positions and included the solar-synchronized positions in the stable L4/L5 libration orbits, the potentially stable nonplanar orbits near L1/L2, Earth-Moon , and also  in the Sun-Earth system. Again no extraterrestrial probes were found to limiting magnitudes of 17–19th magnitude near L3/L4/L5, 10–18th magnitude for /, and 14–16th magnitude for Sun-Earth .

text: In 1979, Freitas and Valdes conducted a photographic search of the vicinity of the Earth-Moon triangular libration points  and , and of the solar-synchronized positions in the associated halo orbits, seeking possible orbiting extraterrestrial interstellar probes, but found nothing to a detection limit of about 14th magnitude. The authors conducted a second, more comprehensive photographic search for probes in 1982 that examined the five Earth-Moon

text: Lagrangian positions

text: and included the solar-synchronized positions in the stable L4/L5 libration orbits, the potentially stable nonplanar orbits near L1/L2, Earth-Moon , and also  in the Sun-Earth system. Again no extraterrestrial probes were found to limiting magnitudes of 17–19th magnitude near L3/L4/L5, 10–18th magnitude for /, and 14–16th magnitude for Sun-Earth .

text: In 2003 it was discovered that 66652 Borasisi is a binary with the components of comparable size (about 100–130 km) orbiting the barycentre on a moderately elliptical orbit. The total system mass is about 3.4 kg.

text: In 2003 it was discovered that 66652 Borasisi is a

text: binary

text: with the components of comparable size (about 100–130 km) orbiting the

text: barycentre

text: on a moderately elliptical orbit. The total system mass is about 3.4 kg.

text: As the Earth turns around its axis, everything attached to it turns with it (imperceptibly to our senses). An object that is moving without being dragged along with this rotation travels in a straight motion over the turning Earth. From our rotating perspective on the planet, its direction of motion changes as it moves, bending in the opposite direction to our actual motion. When viewed from a stationary point in space directly above the north pole, any land feature in the Northern Hemisphere turns anticlockwise—and, fixing our gaze on that location, any other location in that hemisphere rotates around it the same way. The traced ground path of a freely moving body travelling from one point to another therefore bends the opposite way, clockwise, which is conventionally labeled as "right," where it will be if the direction of motion is considered "ahead," and "down" is defined naturally.

text: As the Earth turns around its axis, everything attached to it turns with it (imperceptibly to our senses). An object that is moving without being dragged along with this rotation travels in a straight motion over the turning Earth. From our rotating perspective on the planet, its direction of motion changes as it moves, bending in the opposite direction to our actual motion. When viewed from a stationary point in space directly above the north pole, any land feature in the Northern Hemisphere turns anticlockwise—and, fixing our gaze on that location, any other location in that hemisphere rotates around it the same way. The traced

text: ground path

text: of a freely moving body travelling from one point to another therefore bends the opposite way, clockwise, which is conventionally labeled as "right," where it will be if the direction of motion is considered "ahead," and "down" is defined naturally.

text: In the Solar System, the inner planets are terrestrial, and the outer ones are gas giants, but discoveries of extrasolar planets suggest that this arrangement may not be at all common: numerous Jupiter-sized bodies have been found in close orbit about their primary, disrupting potential HZs. However, present data for extrasolar planets is likely to be skewed towards that type (large planets in close orbits) because they are far easier to identify; thus it remains to be seen which type of planetary system is the norm, or indeed if there is one.

text: In the Solar System, the inner planets are

text: terrestrial

text: , and the outer ones are

text: gas giant

text: s, but discoveries of

text: extrasolar planet

text: s suggest that this arrangement may not be at all common: numerous Jupiter-sized bodies have been found in close orbit about their primary, disrupting potential HZs. However, present data for extrasolar planets is likely to be skewed towards that type (large planets in close orbits) because they are far easier to identify; thus it remains to be seen which type of planetary system is the norm, or indeed if there is one.

text: Copernican heliocentrism is the name given to the astronomical model developed by Nicolaus Copernicus and published in 1543. It positioned the Sun near the center of the Universe, motionless, with Earth and the other planets rotating around it in circular paths modified by epicycles and at uniform speeds. The Copernican model departed from the Ptolemaic system that prevailed in Western culture for centuries, placing Earth at the center of the Universe, and is often regarded as the launching point to modern astronomy and the Scientific Revolution.

text: Copernican heliocentrism is the name given to the astronomical

text: model

text: developed by

text: Nicolaus Copernicus

text: and published in 1543. It positioned the

text: Sun

text: near the center of the

text: Universe

text: , motionless, with Earth and the other planets rotating around it in circular paths modified by epicycles and at uniform speeds. The Copernican model departed from the

text: Ptolemaic

text: system that prevailed in

text: Western culture

text: for centuries, placing Earth at the

text: center of the Universe

text: , and is often regarded as the launching point to modern

text: astronomy

text: and the

text: Scientific Revolution

text: In actual astronomical practice, the delineation of the galactic quadrants is based upon the galactic coordinate system, which places the Sun as the pole of the mapping system. The Sun is used instead of the Galactic Center for practical reasons since all astronomical observations (by humans) to date have been based on Earth or within the solar system.

text: In actual astronomical practice, the delineation of the galactic quadrants is based upon the

text: galactic coordinate system

text: , which places the

text: Sun

text: as the

text: pole of the mapping system

text: . The Sun is used instead of the

text: Galactic Center

text: for practical reasons since all astronomical observations (by

text: human

text: s) to date have been based on

text: Earth

text: or within the

text: solar system

text: The Solar System's planets and officially recognized dwarf planets are known to be orbited by 182 natural satellites, or moons. 19 moons in the Solar System are large enough to be gravitationally rounded, and thus would be considered planets or dwarf planets if they were in direct orbit around the Sun.

text: The

text: Solar System

text: 's planets and officially recognized dwarf planets are known to be orbited by 182

text: natural satellite

text: s, or moons. 19 moons in the Solar System are large enough to be gravitationally rounded, and thus would be considered

text: planets

text: or

text: dwarf planets

text: if they were in direct orbit around the Sun.

text: In the same way, the planet Jupiter is the king of the other planets, a giant in size with spectacular, brightly colored clouds and intense storms. Some astronomers believe that it plays an important protecting role in using its massive gravity to capture or expel from the solar system many comets and asteroids that would otherwise threaten Earth and the inner planets. Jupiter takes 11.9 years to orbit the Sun, spending almost an earth year (361 days) in each sign of the zodiac. Furthermore, Jupiter is usually the fourth-brightest object in the sky (after the Sun, the Moon and Venus).

text: Although the exact size of the two outer CO shells remains elusive, preliminary estimates suggest that one shell extends from about 1.5 to 4.0 arcseconds and the other expands as far as 7.0 arcseconds. Assuming the Jovian orbit of 5.5 AU as the star radius, the inner shell would extend roughly 50 to 150 stellar radii (~300 to 800 AU) with the outer one as far as 250 stellar radii (~1400 AU). The Sun's heliopause is estimated at about 100 AU, so the size of this outer shell would be almost fourteen times the size of the Solar System.

text: Although the exact size of the two outer

text: CO

text: shells remains elusive, preliminary estimates suggest that one shell extends from about 1.5 to 4.0

text: arcseconds

text: and the other expands as far as 7.0

text: arcseconds

text: . Assuming the Jovian orbit of 5.5 AU as the star radius, the inner shell would extend roughly 50 to 150 stellar radii (~300 to 800 AU) with the outer one as far as 250 stellar radii (~1400 AU). The Sun's

text: heliopause

text: is estimated at about 100 AU, so the size of this outer shell would be almost fourteen times the size of the Solar System.

text: Extraterrestrial oceans may be composed of water or other elements and compounds. The only confirmed large stable bodies of extraterrestrial surface liquids are the lakes of Titan, although there is evidence for the existence of oceans elsewhere in the Solar System. Early in their geologic histories, Mars and Venus are theorized to have had large water oceans. The Mars ocean hypothesis suggests that nearly a third of the surface of Mars was once covered by water, and a runaway greenhouse effect may have boiled away the global ocean of Venus. Compounds such as salts and ammonia dissolved in water lower its freezing point, so that water might exist in large quantities in extraterrestrial environments as brine or convecting ice. Unconfirmed oceans are speculated beneath the surface of many dwarf planets and natural satellites; notably, the ocean of Europa is estimated to have over twice the water volume of Earth. The Solar System's giant planets are also thought to have liquid atmospheric layers of yet to be confirmed compositions. Oceans may also exist on exoplanets and exomoons, including surface oceans of liquid water within a circumstellar habitable zone. Ocean planets are a hypothetical type of planet with a surface completely covered with liquid.

text: Extraterrestrial oceans

text: may be composed of water or other

text: element

text: s and

text: compounds

text: . The only confirmed large stable bodies of extraterrestrial surface

text: liquids

text: are the

text: lakes of Titan

text: , although there is evidence for the existence of oceans elsewhere in the

text: Solar System

text: . Early in their geologic histories,

text: Mars

text: and

text: Venus

text: are theorized to have had large water oceans. The

text: Mars ocean hypothesis

text: suggests that nearly a third of the surface of Mars was once covered by water, and a

text: runaway greenhouse effect

text: may have boiled away the global ocean of Venus. Compounds such as

text: salts

text: and

text: ammonia

text: dissolved in water lower its freezing point, so that water might exist in large quantities in extraterrestrial environments as brine or convecting

text: ice

text: . Unconfirmed oceans are speculated beneath the surface of many

text: dwarf planets

text: and natural satellites; notably, the ocean of

text: Europa

text: is estimated to have over twice the water volume of Earth. The Solar System's

text: giant planet

text: s are also thought to have liquid

text: atmospheric

text: layers of yet to be confirmed compositions. Oceans may also exist on

text: exoplanet

text: s and

text: exomoon

text: s, including surface oceans of liquid water within a

text: circumstellar habitable zone

text: Ocean planet

text: s are a hypothetical type of planet with a surface completely covered with liquid.

text: The Earth formed from the same cloud of matter that formed the Sun, but the planets acquired different compositions during the formation and evolution of the solar system. In turn, the natural history of the Earth caused parts of this planet to have differing concentrations of the elements.

text: The

text: Earth

text: formed from the same cloud of matter that formed the Sun, but the planets acquired different compositions during the

text: formation and evolution of the solar system

text: . In turn, the

text: natural history of the Earth

text: caused parts of this planet to have differing concentrations of the elements.

text: Volunteers can choose to search simulated or actual planetary systems. The simulations are used to help Systemic gain a deeper understanding of real extrasolar planets. The real Solar System and the Galilean moons of Jupiter's natural satellites (hidden among the "challenge" data sets) are among the more than 450 data sets of real, and 520 simulated, star systems.

text: Volunteers can choose to search simulated or actual planetary systems. The simulations are used to help Systemic gain a deeper understanding of real extrasolar planets. The real

text: Solar System

text: and the Galilean moons of

text: Jupiter's natural satellites

text: (hidden among the "challenge" data sets) are among the more than 450 data sets of real, and 520 simulated, star systems.

text: NEAs survive in their orbits for just a few million years. They are eventually eliminated by planetary perturbations, causing ejection from the Solar System or a collision with the Sun or a planet. With orbital lifetimes short compared to the age of the Solar System, new asteroids must be constantly moved into near-Earth orbits to explain the observed asteroids. The accepted origin of these asteroids is that asteroid-belt asteroids are moved into the inner Solar System through orbital resonances with Jupiter. The interaction with Jupiter through the resonance perturbs the asteroid's orbit and it comes into the inner Solar System. The asteroid belt has gaps, known as Kirkwood gaps, where these resonances occur as the asteroids in these resonances have been moved onto other orbits. New asteroids migrate into these resonances, due to the Yarkovsky effect that provides a continuing supply of near-Earth asteroids. The known asteroid with the greatest known chance of impacting Earth is  with a 1 in 16 chance of impacting Earth on 5 September 2095. Its 7-meter estimated diameter ensures that an impact would cause little damage.

text: NEAs survive in their orbits for just a few million years. They are eventually eliminated by planetary

text: perturbations

text: , causing ejection from the Solar System or a

text: collision

text: with the Sun or a planet. With orbital lifetimes short compared to the age of the Solar System, new asteroids must be constantly moved into near-Earth orbits to explain the observed asteroids. The accepted origin of these asteroids is that

text: asteroid-belt asteroids

text: are moved into the inner Solar System through

text: orbital resonance

text: s with

text: Jupiter

text: . The interaction with Jupiter through the resonance

text: perturb

text: s the asteroid's orbit and it comes into the inner Solar System. The asteroid belt has gaps, known as

text: Kirkwood gap

text: s, where these resonances occur as the asteroids in these resonances have been moved onto other orbits. New asteroids migrate into these resonances, due to the

text: Yarkovsky effect

text: that provides a continuing supply of near-Earth asteroids. The known asteroid with the greatest known chance of impacting Earth is  with a 1 in 16 chance of impacting Earth on 5 September 2095. Its 7-meter estimated diameter ensures that an impact would cause little damage.

text: In 1687, Isaac Newton stated the law of universal gravitation, described earlier as a hypothesis by Robert Hooke and others. His main achievement was to mathematically derive Kepler's laws of planetary motion from the law of gravitation, thus helping to prove the latter. This introduced gravitation as the force that both kept the Earth and planets moving through the heavens and also kept the air from flying away.  The theory of gravity allowed scientists to construct a plausible heliocentric model for the solar system quickly. In his Principia, Newton explained his system of how gravity, (previously thought of as an occult force) directed the movements of celestial bodies, and kept our solar system in its working order.  His descriptions of centripetal force were a breakthrough in scientific thought which used the newly developed differential calculus, and finally replaced the previous schools of scientific thought, i.e. those of Aristotle and Ptolemy.  However, the process was gradual.

text: In 1687,

text: Isaac Newton

text: stated the

text: law of universal gravitation

text: , described earlier as a hypothesis by

text: Robert Hooke

text: and others. His main achievement was to mathematically derive

text: Kepler's laws of planetary motion

text: from the law of gravitation, thus helping to prove the latter. This introduced

text: gravitation

text: as the force that both kept the Earth and planets moving through the heavens and also kept the air from flying away.  The theory of gravity allowed scientists to construct a plausible heliocentric model for the solar system quickly. In his

text: Principia

text: , Newton explained his system of how gravity, (previously thought of as an occult force) directed the movements of celestial bodies, and kept our solar system in its working order.  His descriptions of centripetal force were a breakthrough in scientific thought which used the newly developed

text: differential calculus

text: , and finally replaced the previous schools of scientific thought, i.e. those of Aristotle and Ptolemy.  However, the process was gradual.

text: Photovoltaic thermal hybrid solar collectors, sometimes known as hybrid PV/T systems or PVT, are systems that convert solar radiation into thermal and electrical energy.It is a combination of Photo voltaic and solar thermal systems into a hybrid form known as PVT solar collectors.  These systems combine a solar cell, which converts sunlight into electricity, with a solar thermal collector, which captures the remaining energy and removes waste heat from the PV module. The capture of both electricity and heat allow these devices to have higher exergy and thus be more overall energy efficient than solar photovoltaic (PV) or solar thermal alone. A significant amount of research has gone into developing PVT technology since the 1970s.

text: Photovoltaic thermal hybrid solar collectors, sometimes known as hybrid PV/T systems or PVT, are systems that convert

text: solar radiation

text: into

text: thermal

text: and

text: electrical energy

text: .It is a combination of Photo voltaic and solar thermal systems into a hybrid form known as PVT solar collectors.  These systems combine a

text: solar cell

text: , which converts sunlight into electricity, with a

text: solar thermal collector

text: , which captures the remaining energy and removes waste heat from the

text: PV module

text: . The capture of both electricity and heat allow these devices to have higher

text: exergy

text: and thus be more overall energy efficient than solar photovoltaic (PV) or solar thermal alone. A significant amount of research has gone into developing PVT technology since the 1970s.

text: The Earth's orbit is an ellipse. The eccentricity is a measure of the departure of this ellipse from circularity. The shape of the Earth's orbit varies in time between nearly circular (with the lowest eccentricity of 0.000055) and mildly elliptical (highest eccentricity of 0.0679)  with the mean eccentricity of 0.0019 as geometric or logarithmic mean. The major component of these variations occurs on a period of 413,000 years (eccentricity variation of ±0.012). A number of other terms vary between components 95,000 and 125,000 years (with a beat period 400,000 years), and loosely combine into a 100,000-year cycle (variation of −0.03 to +0.02). The present eccentricity is 0.017 and decreasing.

text: The Earth's orbit is an

text: ellipse

text: . The

text: eccentricity

text: is a measure of the departure of this ellipse from circularity. The shape of the Earth's orbit varies in time between nearly circular (with the lowest eccentricity of 0.000055) and mildly elliptical (highest eccentricity of 0.0679)  with the mean eccentricity of 0.0019 as geometric or logarithmic mean. The major component of these variations occurs on a period of 413,000 years (eccentricity variation of ±0.012). A number of other terms vary between components 95,000 and 125,000 years (with a beat period 400,000 years), and loosely combine into a 100,000-year cycle (variation of −0.03 to +0.02). The present eccentricity is 0.017 and decreasing.

text: Instruments used for follow-up characterization employing doppler spectroscopy to determine the exoplanet's mass include the HARPS spectrograph of ESO's 3.6-metre telescope as well as the Swiss Euler Telescope, both located at La Silla Observatory, Chile. WASP's design has also been adopted by the Next-Generation Transit Survey. As of 2016, the Extrasolar Planets Encyclopaedia data base contains a total of 2,107 extrasolar planets of which 118 were discoveries by WASP.

text: Instruments used for follow-up characterization employing

text: doppler spectroscopy

text: to determine the exoplanet's mass include the

text: HARPS

text: spectrograph of ESO's 3.6-metre telescope as well as the Swiss

text: Euler Telescope

text: , both located at

text: La Silla Observatory

text: , Chile. WASP's design has also been adopted by the

text: Next-Generation Transit Survey

text: . As of 2016, the

text: Extrasolar Planets Encyclopaedia

text: data base contains a total of 2,107 extrasolar planets of which 118 were discoveries by WASP.

text: European hypotheses of the Swastika are often treated in conjunction with cross symbols in general, such as the sun cross of pagan Bronze Age religion. Beyond its certain presence in the "proto-writing" symbol systems, such as the Vinca script, which  appeared during the Neolithic, nothing certain is known about the symbol's origin. There are nevertheless a number of speculative hypotheses. One hypothesis is that the cross symbols and the swastika share a common origin in simply symbolizing the sun. Another hypothesis is that the four arms of the cross represent four aspects of nature - the sun, wind, water, soil. Some have said the four arms of cross are four seasons, where the division for 90-degree sections correspond to the solstices and equinoxes. The Hindus represent it as the Universe in our own spiral galaxy in the fore finger of Lord Vishnu. This carries most significance in establishing the creation of the Universe and the arms as 'kal' or time, a calendar that is seen to be more advanced than the lunar calendar  where the seasons drift from calendar year to calendar year. The luni-solar solution for correcting season drift was to intercalate an extra month in certain years to restore the lunar cycle to the solar-season cycle. The Star of David is thought to originate as a symbol of that calendar system, where the two overlapping triangles are seen to form a partition of 12 sections around the perimeter with a 13th section in the middle, representing the 12 and sometimes 13 months to a year. As such, the Christian cross, Jewish hexagram star, and Muslim crescent moon are seen to have their origins in different views regarding which calendar system is preferred for marking holy days. Groups in higher latitudes experience the seasons more strongly, offering more advantage to the calendar represented by the swastika/cross.

text: European hypotheses of the Swastika are often treated in conjunction with

text: cross symbol

text: s in general, such as the

text: sun cross

text: of pagan

text: Bronze Age religion

text: . Beyond its certain presence in the "

text: proto-writing

text: " symbol systems, such as the

text: Vinca script

text: , which  appeared during the

text: Neolithic

text: , nothing certain is known about the symbol's origin. There are nevertheless a number of speculative hypotheses. One hypothesis is that the cross symbols and the swastika share a common origin in simply symbolizing the

text: sun

text: . Another hypothesis is that the four arms of the cross represent four aspects of nature - the sun, wind, water, soil. Some have said the four arms of cross are four seasons, where the division for 90-degree sections correspond to the

text: solstice

text: s and

text: equinox

text: es. The Hindus represent it as the Universe in our own spiral galaxy in the fore finger of Lord Vishnu. This carries most significance in establishing the creation of the Universe and the arms as '

text: kal

text: ' or time, a calendar that is seen to be more advanced than the lunar calendar  where the seasons drift from calendar year to calendar year. The

text: luni-solar

text: solution for correcting season drift was to

text: intercalate

text: an extra month in certain years to restore the lunar cycle to the solar-season cycle. The

text: Star of David

text: is thought to originate as a symbol of that calendar system, where the two overlapping triangles are seen to form a partition of 12 sections around the perimeter with a 13th section in the middle, representing the 12 and sometimes 13 months to a year. As such, the Christian cross, Jewish hexagram star, and Muslim crescent moon are seen to have their origins in different views regarding which calendar system is preferred for marking holy days. Groups in higher latitudes experience the seasons more strongly, offering more advantage to the calendar represented by the swastika/cross.

text: Founded in Richmond, Virginia, in 1997, One Ring Zero moved to Brooklyn, New York, in 2001. The group's works are often programmatic and/or collaborative. They include As Smart As We Are, featuring lyrics by Paul Auster, Margaret Atwood, Jonathan Lethem, A.M. Homes, Neil Gaiman, Rick Moody and Dave Eggers. The book/CD The Recipe Project is a collection of recipes set to music and sung word for word in the musical style suggested by the chefs, including Mario Batali, Chris Cosentino, Andrea Reusing, David Chang, John Besh, Mark Kurlansky, Michael Symon, and Isa Chandra Moskowitz. Planets is a collection of compositions representing the solar system and beyond. Hearst says of Planets, "It had been just about 100 years since Holst had composed his song cycle The Planets. It seemed like it was time to musically revisit our solar system and come up with our own song cycle."

text: Founded in

text: Richmond, Virginia

text: , in 1997, One Ring Zero moved to

text: Brooklyn

text: , New York, in 2001. The group's works are often programmatic and/or collaborative. They include

text: As Smart As We Are

text: , featuring lyrics by

text: Paul Auster

text: Margaret Atwood

text: Jonathan Lethem

text: A.M. Homes

text: Neil Gaiman

text: Rick Moody

text: and

text: Dave Eggers

text: . The book/CD

text: The Recipe Project

text: is a collection of recipes set to music and sung word for word in the musical style suggested by the chefs, including

text: Mario Batali

text: Chris Cosentino

text: Andrea Reusing

text: David Chang

text: John Besh

text: Mark Kurlansky

text: Michael Symon

text: , and

text: Isa Chandra Moskowitz

text: Planets

text: is a collection of compositions representing the solar system and beyond. Hearst says of Planets, "It had been just about 100 years since

text: Holst

text: had composed his song cycle

text: The Planets

text: . It seemed like it was time to musically revisit our solar system and come up with our own song cycle."

text: Solar conjunction occurs when a planet or other solar system object is on the opposite side of the sun from the Earth.  From an Earth reference, the sun will pass between the Earth and the object. Communication with any spacecraft in solar conjunction will be severely limited due to the sun's interference on radio transmissions from the spacecraft.

text: Solar conjunction occurs when a

text: planet

text: or other

text: solar system

text: object is on the opposite side of the

text: sun

text: from the

text: Earth

text: .  From an Earth reference, the sun will pass between the Earth and the object. Communication with any

text: spacecraft

text: in solar conjunction will be severely limited due to the sun's interference on radio transmissions from the spacecraft.

text: In the late-58th century, the various planets of Earth’s solar system had banded together and formed the Solar Council.  When their citizens were threatened by a disaster too great for them to handle, the Solar Council's secretary Iona Vane decided to bring the greatest Green Lantern in history, Hal Jordan, to their time.  An unfortunate side effect of the time travel completely erased Jordan's memory.  Vane created the fictitious "Pol Manning" persona and recorded it into Jordan's mind; she even cast herself as his romantic interest.  For years, Jordan lived a double life in the 20th and 58th centuries until his mysterious memory lapses caused him to uncover the Solar Council's deception.  He returned to the 58th century under his own power, where he discovered that his power ring had accidentally created an evil clone.  After Hal defeated his evil doppelgänger, the clone was implanted with the Pol Manning identity and sent to explore the furthest reaches of the universe.

text: In the late-58th century, the various planets of Earth’s solar system had banded together and formed the

text: Solar Council

text: .  When their citizens were threatened by a disaster too great for them to handle, the Solar Council's secretary Iona Vane decided to bring the greatest

text: Green Lantern

text: in history, Hal Jordan, to their time.  An unfortunate side effect of the time travel completely erased Jordan's memory.  Vane created the fictitious "Pol Manning" persona and recorded it into Jordan's mind; she even cast herself as his romantic interest.  For years, Jordan lived a double life in the 20th and 58th centuries until his mysterious memory lapses caused him to uncover the Solar Council's deception.  He returned to the 58th century under his own power, where he discovered that his power ring had accidentally created an evil clone.  After Hal defeated his evil

text: doppelgänger

text: , the clone was implanted with the Pol Manning identity and sent to explore the furthest reaches of the universe.

text: Ultimately, the Solar System is stable in that none of the planets are likely to collide with each other or be ejected from the system in the next few billion years. Beyond this, within five billion years or so Mars's eccentricity may grow to around 0.2, such that it lies on an Earth-crossing orbit, leading to a potential collision. In the same timescale, Mercury's eccentricity may grow even further, and a close encounter with Venus could theoretically eject it from the Solar System altogether or send it on a collision course with Venus or Earth. This could happen within a billion years, according to numerical simulations in which Mercury's orbit is perturbed.

text: Ultimately, the Solar System is stable in that none of the planets are likely to collide with each other or be ejected from the system in the next few billion years. Beyond this, within five billion years or so Mars's eccentricity may grow to around 0.2, such that it lies on an Earth-crossing orbit, leading to a potential collision. In the same timescale, Mercury's eccentricity may grow even further, and a close encounter with Venus could theoretically eject it from the Solar System altogether or send it on a collision course with

text: Venus

text: or

text: Earth

text: . This could happen within a billion years, according to numerical simulations in which Mercury's orbit is perturbed.

text: The Solar System has now been relatively well-studied, and a good overall understanding of the formation and evolution of this planetary system exists. However, there are large numbers of unsolved questions, and the rate of new discoveries is very high, partly due to the large number of interplanetary spacecraft currently exploring the Solar System.

text: First Contact was the last film to feature a physical model of the Enterprise. For the ship's dramatic introduction, the effects team combined motion control shots of the Enterprise model with a computer-generated background. Sequence supervisor Dennis Turner, who had created Generations energy ribbon and specialized in creating natural phenomena, was charged with creating the star cluster, modeled after the Eagle Nebula. The nebular columns and solid areas were modeled with basic wireframe geometry, with surface shaders applied to make the edges of the nebula glow. A particle render that ILM had devised for the earlier tornado film Twister was used to create a turbulent look within the nebula. Once the shots of the Enterprise had been captured, Turner inserted the ship into the computer-generated background and altered its position until the images matched up.

text: First Contact was the last film to feature a physical model of the Enterprise. For the ship's dramatic introduction, the effects team combined

text: motion control

text: shots of the Enterprise model with a computer-generated background. Sequence supervisor Dennis Turner, who had created Generations energy ribbon and specialized in creating natural phenomena, was charged with creating the star cluster, modeled after the

text: Eagle Nebula

text: . The nebular columns and solid areas were modeled with basic wireframe geometry, with surface shaders applied to make the edges of the nebula glow. A particle render that ILM had devised for the earlier tornado film

text: Twister

text: was used to create a turbulent look within the nebula. Once the shots of the Enterprise had been captured, Turner inserted the ship into the computer-generated background and altered its position until the images matched up.

text: The possibility of extraterrestrial life is not, by itself, a paranormal subject. Many scientists are actively engaged in the search for unicellular life within the solar system, carrying out studies on the surface of Mars and examining meteors that have fallen to Earth. Projects such as SETI are conducting an astronomical search for radio activity that would show evidence of intelligent life outside the solar system. Scientific theories of how life developed on Earth allow for the possibility that life developed on other planets as well. The paranormal aspect of extraterrestrial life centers largely around the belief in unidentified flying objects and the phenomena said to be associated with them.

text: The possibility of

text: extraterrestrial life

text: is not, by itself, a paranormal subject. Many scientists are actively engaged in the search for unicellular life within the

text: solar system

text: , carrying out studies on the surface of

text: Mars

text: and examining

text: meteors

text: that have fallen to

text: Earth

text: . Projects such as

entity_name: Search for extraterrestrial intelligence

text: SETI

text: are conducting an astronomical search for

text: radio

text: activity that would show evidence of intelligent life outside the solar system.

text: Scientific theories

text: of how life developed on Earth allow for the possibility that life developed on other

text: planets

text: as well. The paranormal aspect of

text: extraterrestrial life

text: centers largely around the belief in

text: unidentified flying objects

text: and the phenomena said to be associated with them.

text: Many proposals involve deployment of a solar shade or a system of orbital mirrors, for the purpose of reducing insolation and providing light to the dark side of Venus. Another common thread in most proposals involves some introduction of large quantities of hydrogen or water. Proposals also involve either freezing most of Venus's atmospheric CO, or converting it to carbonates, urea or other forms.

text: Many proposals involve deployment of a solar shade or a system of orbital mirrors, for the purpose of reducing

text: insolation

text: and providing light to the dark side of Venus. Another common thread in most proposals involves some introduction of large quantities of

text: hydrogen

text: or

text: water

text: . Proposals also involve either freezing most of Venus's atmospheric CO, or converting it to

text: carbonates

text: urea

text: or other forms.

text: There are also forces external to Earth itself that affect Earth’s climate. Two examples of these external forces are meteors/asteroids becoming meteorites and striking the surface of the earth, and geomagnetic storms from the sun affecting the earth. Asteroids only about two kilometers in diameter, according to Young’s paper referencing original author Michael Paine, can cause craters in Earth’s surface about 40 kilometers in diameter. Such an impact could throw enormous quantities of dust into the sky, blocking out the sun and causing significant climate changes, somewhat similar in effect to a gigantic volcanic eruption. Among other things, meteorites striking Earth also “affect sea level, rainfall, temperature, ocean currents, and atmospheric circulation”. Asteroids and meteors are not, however, the only external forces to affect Earth climate change. Variations in solar output can also bring about climate change on the Earth. More specifically, varying amounts of sun activity, including sunspots, solar flares, solar wind, and massive solar radiation, can all be grouped together as geomagnetic storms, which together, act to affect Earth’s climate. Our sun has a solar activity cycle of about 11 years. During which time, the sun gets sunspots, shoots off solar flares, and blasts earth with solar wind and geomagnetic activity. Despite the appearance that these events seem random, they do overall follow a fairly steady cycle of approximately 11 years. The difference in average solar irradiation received by the earth due to these ‘random’ events, though, is only about 0.1 percent. Overall, the total irradiation generated by the sun, and received by the earth is a major factor affecting Earth climate. The total solar irradiation received by Earth’s surface can be calculated mathematically. This can be done through the following equation:

text: There are also forces external to Earth itself that affect Earth’s climate. Two examples of these external forces are meteors/asteroids becoming

text: meteorites

text: and striking the surface of the earth, and geomagnetic storms from the sun affecting the earth. Asteroids only about two kilometers in diameter, according to Young’s paper referencing original author Michael Paine, can cause craters in Earth’s surface about 40 kilometers in diameter. Such an impact could throw enormous quantities of dust into the sky, blocking out the sun and causing significant climate changes, somewhat similar in effect to a gigantic volcanic eruption. Among other things, meteorites striking Earth also “affect sea level, rainfall, temperature, ocean currents, and atmospheric circulation”. Asteroids and meteors are not, however, the only external forces to affect Earth climate change. Variations in solar output can also bring about climate change on the Earth. More specifically, varying amounts of

text: sun activity

text: , including

text: sunspots

text: solar flares

text: solar wind

text: , and massive

text: solar radiation

text: , can all be grouped together as geomagnetic storms, which together, act to affect Earth’s climate. Our sun has a solar activity cycle of about 11 years. During which time, the sun gets sunspots, shoots off solar flares, and blasts earth with solar wind and

text: geomagnetic activity

text: . Despite the appearance that these events seem random, they do overall follow a fairly steady cycle of approximately 11 years. The difference in average solar irradiation received by the earth due to these ‘random’ events, though, is only about 0.1 percent. Overall, the total irradiation generated by the sun, and received by the earth is a major factor affecting Earth climate. The total solar irradiation received by Earth’s surface can be calculated mathematically. This can be done through the following equation:

text: Tiferet also occupies a place on the middle pillar, and can be seen as a lower reflection of Kether, as well as a higher reflection of Yesod and Malkuth.  Tiferet relates to the sun, and as such, it takes a central place in the lower face of the Tree of Life, much in the same manner that the sun is at the center of the solar system.  It is not the center of the universe, as one could perhaps argue Kether to be, but rather it is the center of our local astronomical system.  Nonetheless, it is the sun that gives light and life, even though it did not create itself.  Tiferet can be seen as a metaphor for these same attributes.

text: MAVEN was built and tested by Lockheed Martin Space Systems. Its design is based on those of the Mars Reconnaissance Orbiter and Mars Odyssey spacecraft. The orbiter has a cubical shape of about  high, with two solar arrays that hold the magnetometers on both ends. The total length is .

text: MAVEN was built and tested by

text: Lockheed Martin Space Systems

text: . Its design is based on those of the

text: Mars Reconnaissance Orbiter

text: and

text: Mars Odyssey

text: spacecraft. The orbiter has a cubical shape of about  high, with two

text: solar arrays

text: that hold the magnetometers on both ends. The total length is .

text: A solar inverter is a balance of system (BOS) component of a photovoltaic system and can be used for both, grid-connected and off-grid systems. Solar inverters have special functions adapted for use with photovoltaic arrays, including maximum power point tracking and anti-islanding protection.Solar micro-inverters differ from conventional inverters, as an individual micro-inverter is attached to each solar panel. This can improve the overall efficiency of the system. The output from several micro-inverters is then combined and often fed to the electrical grid.

text: A

text: solar inverter

text: is a

text: balance of system

text: (BOS) component of a

text: photovoltaic system

text: and can be used for both,

text: grid-connected

text: and

text: off-grid

text: systems. Solar inverters have special functions adapted for use with

text: photovoltaic

text: arrays, including

text: maximum power point tracking

text: and

text: anti-islanding

text: protection.

text: Solar micro-inverter

text: s differ from conventional inverters, as an individual micro-inverter is attached to each solar panel. This can improve the overall efficiency of the system. The output from several micro-inverters is then combined and often fed to the

text: electrical grid

text: This model was also refined by Callippus and after concentric spheres were abandoned, it was brought into nearly perfect agreement with astronomical observations by Ptolemy. The success of such a model is largely due to the mathematical fact that any function (such as the position of a planet) can be decomposed into a set of circular functions (the Fourier modes). Other Greek scientists, such as the Pythagorean philosopher Philolaus, postulated (according to Stobaeus account) that at the center of the Universe was a "central fire" around which the Earth, Sun, Moon and Planets revolved in uniform circular motion.

text: This model was also refined by

text: Callippus

text: and after concentric spheres were abandoned, it was brought into nearly perfect agreement with astronomical observations by

text: Ptolemy

text: . The success of such a model is largely due to the mathematical fact that any function (such as the position of a planet) can be decomposed into a set of circular functions (the

text: Fourier modes

text: ). Other Greek scientists, such as the

text: Pythagorean

text: philosopher

text: Philolaus

text: , postulated (according to

text: Stobaeus

text: account) that at the center of the Universe was a "central fire" around which the

text: Earth

text: Sun

text: Moon

text: and

text: Planet

text: s revolved in uniform circular motion.

text: Neptune is the eighth and farthest known planet from the Sun in the Solar System. In the Solar System, it is the fourth-largest planet by diameter, the third-most-massive planet, and the densest giant planet. Neptune is 17 times the mass of Earth and is slightly more massive than its near-twin Uranus, which is 15 times the mass of Earth and slightly larger than Neptune. Neptune orbits the Sun once every 164.8 years at an average distance of . It is named after the Roman god of the sea and has the astronomical symbol ♆, a stylised version of the god Neptune's trident.

text: Neptune is the eighth and farthest known

text: planet

text: from the

text: Sun

text: in the

text: Solar System

text: . In the Solar System, it is the fourth-largest planet by diameter, the third-most-massive planet, and the densest

text: giant planet

text: . Neptune is 17 times the mass of

text: Earth

text: and is slightly more massive than its near-twin

text: Uranus

text: , which is 15 times the mass of Earth and slightly larger than Neptune. Neptune orbits the Sun once every 164.8

text: years

text: at an average distance of . It is named after the

text: Roman god of the sea

text: and has the

text: astronomical symbol

text: ♆, a stylised version of the god Neptune's

text: trident

text: Particles can be reduced in size by collisions or by space weathering. When ground down to sizes less than 10 micrometres, the grains are removed from the inner Solar System by solar radiation pressure. The dust is then replenished by the infall from comets. Zodiacal dust around nearby stars is called exozodiacal dust; it is a potentially important source of noise for directly imaging extrasolar planets. It has been pointed out that this exozodiacal dust, or hot debris disks, can can be an indicator of planets, as planets tend to scatter the comets to the inner Solar System.

text: Particles can be reduced in size by collisions or by space weathering. When ground down to sizes less than 10 micrometres, the grains are removed from the inner Solar System by solar radiation pressure. The dust is then replenished by the infall from comets. Zodiacal dust around nearby stars is called

text: exozodiacal dust

text: ; it is a potentially important source of noise for directly imaging

text: extrasolar planets

text: . It has been pointed out that this exozodiacal dust, or hot debris disks, can can be an indicator of planets, as planets tend to scatter the comets to the inner Solar System.

text: The orbiter consisted of a cylinder with two solar panel wings and a high gain parabolic antenna attached to the curved surface. A bell-shaped unit holding propulsion systems was attached to the bottom of the cylinder, and mounted on top was a 2.4 meter sphere which held the landers.

text: Today, the Center remains involved in each of NASA's key programs. Goddard has developed more instruments for planetary exploration than any other organization, among them scientific instruments sent to every planet in the Solar System. The Center's contribution to the Earth Science Enterprise includes several spacecraft in the Earth Observing System fleet as well as EOSDIS, a science data collection, processing, and distribution system. For the manned space flight program, Goddard develops tools for use by astronauts during extra-vehicular activity, and built and operates the Lunar Reconnaissance Orbiter and the Solar Dynamics Observatory.

text: Today, the Center remains involved in each of NASA's key programs. Goddard has developed more instruments for

text: planetary exploration

text: than any other organization, among them scientific instruments sent to every planet in the

text: Solar System

text: . The Center's contribution to the

text: Earth Science Enterprise

text: includes several spacecraft in the

text: Earth Observing System

text: fleet as well as

text: EOSDIS

text: , a science data collection, processing, and distribution system. For the manned space flight program, Goddard develops tools for use by astronauts during

text: extra-vehicular activity

text: , and built and operates the

text: Lunar Reconnaissance Orbiter

text: and the

text: Solar Dynamics Observatory

text: The history of the parent body has been reconstructed in detail. The IVB parent body will have formed from material that condensed at the highest temperatures while the solar nebula cooled off. The enrichment in refractory elements was caused by less than 10% of the condensible material going into the parent body. Thermal models suggest that the IVB parent body formed 0.3millionyears after the formation of the calcium-aluminium-rich inclusions, and at a distance from the sun of 0.9Astronomical units.

text: The history of the parent body has been reconstructed in detail. The IVB parent body will have formed from material that condensed at the highest temperatures while the solar nebula cooled off. The enrichment in refractory elements was caused by less than 10% of the condensible material going into the parent body. Thermal models suggest that the IVB parent body formed 0.3millionyears after the formation of the

text: calcium-aluminium-rich inclusion

text: s, and at a distance from the sun of 0.9

text: Astronomical unit

text: s.

text: Most confirmed extrasolar planets have been found using space-based telescopes (as of 01/2015). Many of the detection methods can work more effectively with space-based telescopes that avoid atmospheric haze and turbulence. COROT (2007-2012) and Kepler were space missions dedicated to searching for extrasolar planets using transits. COROT discovered about 30 new exoplanets. Kepler (2009-2013) and K2 (2013- ) have discovered over 2000 verified exoplanets. Hubble Space Telescope and MOST have also found or confirmed a few planets. The infrared Spitzer Space Telescope has been used to detect transits of extrasolar planets, as well as occultation

text: Most confirmed extrasolar planets have been found using space-based telescopes (as of 01/2015). Many of the detection methods can work more effectively with space-based telescopes that avoid atmospheric haze and turbulence.

text: COROT

text: (2007-2012) and

text: Kepler

text: were space missions dedicated to searching for extrasolar planets using transits. COROT discovered about 30 new exoplanets. Kepler (2009-2013) and K2 (2013- ) have discovered over 2000 verified exoplanets.

text: Hubble Space Telescope

text: and

text: MOST

text: have also found or confirmed a few planets. The infrared

text: Spitzer Space Telescope

text: has been used to detect transits of extrasolar planets, as well as

text: occultation

text: Like the majority of long-period extrasolar planets, the orbit of Upsilon Andromedae c is eccentric, more so than any of the major planets in the Solar System (including Pluto). If placed in the Solar System, Upsilon Andromedae c would lie between the orbits of Earth and Venus.

text: Like the majority of long-

text: period

text: extrasolar planets, the orbit of Upsilon Andromedae c is

text: eccentric

text: , more so than any of the major planets in the

text: Solar System

text: (including

text: Pluto

text: ). If placed in the Solar System, Upsilon Andromedae c would lie between the orbits of Earth and

text: Venus

text: Assemblies of solar cells are used to make solar modules which generate electrical power from sunlight, as distinguished from a "solar thermal module" or "solar hot water panel". A solar array generates solar power using solar energy.

text: Assemblies of solar cells are used to make

text: solar module

text: s which generate electrical power from

text: sunlight

text: , as distinguished from a "solar thermal module" or "solar hot water panel". A solar array generates

text: solar power

text: using

text: solar energy

text: Nitrogen was a key target element because the extent and origin of its isotopic variations in solar system materials remain unknown. Target material showed that implanted solar wind nitrogen has a 15N/14N ratio of 2.18 × 10 (that is, ≈40% poorer in 15N relative to terrestrial atmosphere). The 15N/14N ratio of the protosolar nebula was 2.27 × 10, which is the lowest 15N/14N ratio known for solar system objects. This result demonstrates the extreme nitrogen isotopic heterogeneity of the nascent solar system and accounts for the 15N-depleted components observed in solar system reservoirs.

text: An exoplanet (extrasolar planet) is a planet located outside the Solar System. The first confirmed detection of exoplanets was announced in 1992, with two planets found orbiting a pulsar. The first confirmation of an exoplanet orbiting a main-sequence star was made in 1995, when a giant planet was found in a four-day orbit around the nearby star 51 Pegasi. Some exoplanets have been imaged directly by telescopes, but the vast majority have been detected through indirect methods such as the transit method and the radial-velocity method. As of , astronomers have identified  such planets (in  planetary systems and  multiple planetary systems). This is a list of the most notable discoveries.

text: An

text: exoplanet

text: (extrasolar planet) is a

text: planet

text: located outside the

text: Solar System

text: . The first confirmed detection of exoplanets was announced in 1992, with two planets found orbiting a

text: pulsar

text: main-sequence

text: 51 Pegasi

text: . Some exoplanets have been

text: imaged directly

text: transit method

text: and the

text: radial-velocity method

text: . As of , astronomers have identified  such planets (in

text: planetary systems

text: and

text: multiple planetary systems

text: ). This is a list of the most notable discoveries.

text: Heat in a solar thermal system is guided by five basic principles: heat gain; heat transfer; heat storage; heat transport; and heat insulation. Here, heat is the measure of the amount of thermal energy an object contains and is determined by the temperature, mass and specific heat of the object. Solar thermal power plants use heat exchangers that are designed for constant working conditions, to provide heat exchange. Copper heat exchangers are important in solar thermal heating and cooling systems because of copper’s high thermal conductivity, resistance to atmospheric and water corrosion, sealing and joining by soldering, and mechanical strength. Copper is used both in receivers and in primary circuits (pipes and heat exchangers for water tanks) of solar thermal water systems.

text: Heat in a solar thermal system is guided by five basic principles: heat gain;

text: heat transfer

text: heat storage

text: heat transport

text: ; and

text: heat insulation

text: . Here, heat is the measure of the amount of thermal energy an object contains and is determined by the temperature, mass and

text: specific heat

text: of the object. Solar thermal power plants use heat exchangers that are designed for constant working conditions, to provide heat exchange.

text: Copper heat exchangers

text: are important in solar thermal heating and cooling systems because of copper’s high thermal conductivity, resistance to atmospheric and water corrosion, sealing and joining by soldering, and mechanical strength. Copper is used both in receivers and in primary circuits (pipes and heat exchangers for water tanks) of solar thermal water systems.

text: Modelling the formation of the terrestrial and gas giants is relatively straightforward and uncontroversial. The terrestrial planets of the Solar System are widely understood to have formed through collisional accumulation of planetesimals within the protoplanetary disc. The gas giants—Jupiter, Saturn, and their extrasolar counterpart planets—are thought to have formed after solid cores around 10 Earth masses () formed through the same process, while accreting gaseous envelopes from the surrounding solar nebula over the course of a few to several million years (Ma), although alternative models of core formation based on pebble accretion have recently been proposed. Some extrasolar giant planets may instead have formed via gravitational disk instabilities.

text: Modelling the formation of the

text: terrestrial

text: and

text: gas giant

text: s is relatively straightforward and

text: uncontroversial

text: . The terrestrial planets of the

text: Solar System

text: are widely understood to have formed through collisional accumulation of

text: planetesimal

text: s within the

text: protoplanetary disc

text: . The

text: gas giant

text: s—

text: Jupiter

text: Saturn

text: , and their extrasolar counterpart planets—are thought to have formed after solid cores around 10 Earth masses () formed through the same process, while

text: accreting

text: gaseous envelopes from the surrounding

text: solar nebula

text: over the course of a few to several million years (

text: Ma

text: ), although alternative models of core formation based on

text: pebble accretion

text: have recently been proposed. Some extrasolar giant planets may instead have formed via gravitational disk instabilities.

text: The Helix Nebula was the first planetary nebula discovered to contain cometary knots. Its main ring contains knots of nebulosity, which have now been detected in many nearby planetaries.  These knots are highly radially symmetric (from the PNN) and are described as "cometary", each centered on a core of neutral molecular gas and containing bright cusps (local photoionization fronts) towards the central star and tails away from it. All tails extend away from the PNN in a radial direction. Excluding the tails, they are (very approximately) the size of the Solar system, while each of the cusp knots are optically thick due to Lyc photons from the PNN. There are more than 20,000 cometary knots estimated to be in the Helix Nebula.

text: The Helix Nebula was the first planetary nebula discovered to contain

text: cometary knot

text: s. Its main ring contains knots of nebulosity, which have now been detected in many nearby planetaries.  These knots are highly radially symmetric (from the PNN) and are described as "cometary", each centered on a core of neutral molecular gas and containing bright cusps (local

text: photoionization

text: fronts) towards the central star and tails away from it. All tails extend away from the PNN in a radial direction. Excluding the tails, they are (very approximately) the size of the Solar system, while each of the cusp knots are optically thick due to

text: Lyc photon

text: s from the PNN. There are more than 20,000 cometary knots estimated to be in the Helix Nebula.

text: Extrasolar planets have been confirmed in five star systems, four of which were found by the radial velocity method. The spectrum of Epsilon Coronae Borealis was analysed for seven years from 2005 to 2012, revealing a planet around 6.7 times as massive as Jupiter () orbiting every 418 days at an average distance of around 1.3 AU. Epsilon itself is a  orange giant of spectral type K2III that has swollen to  and . Kappa Coronae Borealis is a spectral type K1IV orange subgiant nearly twice as massive as the Sun; around it lie a dust debris disk, and one planet with a period of 3.4 years. This planet's mass is estimated at . The dimensions of the debris disk indicate it is likely there is a second substellar companion. Omicron Coronae Borealis is a K-type clump giant with one confirmed planet with a mass of  that orbits every 187 days—one of the two least massive planets known around clump giants. HD 145457 is an orange giant of spectral type K0III found to have one planet of . Discovered by the Doppler method in 2010, it takes 176 days to complete an orbit. XO-1 is a magnitude 11 yellow main-sequence star located approximately  light-years away, of spectral type G1V with a mass and radius similar to the Sun. In 2006 the hot Jupiter exoplanet XO-1b was discovered orbiting XO-1 by the transit method using the XO Telescope. Roughly the size of Jupiter, it completes an orbit around its star every three days.

text: Extrasolar planets

text: have been confirmed in five star systems, four of which were found by the

text: radial velocity

text: method. The spectrum of

text: Epsilon Coronae Borealis

text: was analysed for seven years from 2005 to 2012, revealing a planet around 6.7 times as massive as

text: Jupiter

text: () orbiting every 418 days at an average distance of around 1.3 AU. Epsilon itself is a  orange giant of spectral type K2III that has swollen to  and .

text: Kappa Coronae Borealis

text: is a spectral type K1IV orange subgiant nearly twice as massive as the Sun; around it lie a dust debris disk, and one planet with a period of 3.4 years. This planet's mass is estimated at . The dimensions of the debris disk indicate it is likely there is a second substellar companion.

text: Omicron Coronae Borealis

text: is a K-type

text: clump giant

text: with one confirmed planet with a mass of  that orbits every 187 days—one of the two least massive planets known around clump giants.

text: HD 145457

text: is an orange giant of spectral type K0III found to have one planet of . Discovered by the Doppler method in 2010, it takes 176 days to complete an orbit.

text: is a magnitude 11

text: yellow main-sequence star

text: located approximately  light-years away, of spectral type G1V with a mass and radius similar to the Sun. In 2006 the

text: hot Jupiter

text: exoplanet

text: was discovered orbiting XO-1 by the

text: transit method

text: using the

text: XO Telescope

text: . Roughly the size of Jupiter, it completes an orbit around its star every three days.

text: in the Cartesian plane, as the path followed by the shadow of the tip of a sundial, as the shape of an open orbit (as distinct from a closed elliptical orbit), such as the orbit of a spacecraft during a gravity assisted swing-by of a planet or more generally any spacecraft exceeding the escape velocity of the nearest planet, as the path of a single-apparition comet (one travelling too fast ever to return to the solar system), as the scattering trajectory of a subatomic particle (acted on by repulsive instead of attractive forces but the principle is the same), and so on.

text: in the

text: Cartesian plane

text: , as the path followed by the shadow of the tip of a sundial, as the shape of an

text: open orbit

text: (as distinct from a closed elliptical orbit), such as the orbit of a

text: spacecraft

text: during a

text: gravity assist

text: ed swing-by of a planet or more generally any spacecraft exceeding the escape velocity of the nearest planet, as the path of a single-apparition

text: comet

text: (one travelling too fast ever to return to the solar system), as the

text: scattering trajectory

text: of a

text: subatomic particle

text: (acted on by repulsive instead of attractive forces but the principle is the same), and so on.

text: Most comets are small Solar System bodies with elongated elliptical orbits that take them close to the Sun for a part of their orbit and then out into the further reaches of the Solar System for the remainder. Comets are often classified according to the length of their orbital periods: The longer the period the more elongated the ellipse.

text: Most comets are

text: small Solar System bodies

text: with elongated

text: elliptical orbit

text: s that take them close to the Sun for a part of their orbit and then out into the further reaches of the Solar System for the remainder. Comets are often classified according to the length of their

text: orbital period

text: s: The longer the period the more elongated the ellipse.

text: PlanetPol did not discover any extrasolar planets.

text: Eclipses can only occur when the Sun, Earth, and Moon are all in a straight line (termed "syzygy"). Solar eclipses occur at new moon, when the Moon is between the Sun and Earth. In contrast, lunar eclipses occur at full moon, when Earth is between the Sun and Moon. The apparent size of the Moon is roughly the same as that of the Sun, with both being viewed at close to one-half a degree wide. The Sun is much larger than the Moon but it is the precise vastly greater distance that gives it the same apparent size as the much closer and much smaller Moon from the perspective of Earth. The variations in apparent size, due to the non-circular orbits, are nearly the same as well, though occurring in different cycles. This makes possible both total (with the Moon appearing larger than the Sun) and annular (with the Moon appearing smaller than the Sun) solar eclipses. In a total eclipse, the Moon completely covers the disc of the Sun and the solar corona becomes visible to the naked eye. Because the distance between the Moon and Earth is very slowly increasing over time, the angular diameter of the Moon is decreasing. Also, as it evolves toward becoming a red giant, the size of the Sun, and its apparent diameter in the sky, are slowly increasing. The combination of these two changes means that hundreds of millions of years ago, the Moon would always completely cover the Sun on solar eclipses, and no annular eclipses were possible. Likewise, hundreds of millions of years in the future, the Moon will no longer cover the Sun completely, and total solar eclipses will not occur.

text: Eclipses can only occur when the Sun, Earth, and Moon are all in a straight line (termed "

text: syzygy

text: Solar eclipse

text: s occur at

text: new moon

text: , when the Moon is between the Sun and Earth. In contrast,

text: lunar eclipse

text: s occur at

text: full moon

text: , when Earth is between the Sun and Moon. The apparent size of the Moon is roughly the same as that of the Sun, with both being viewed at close to one-half a degree wide. The Sun is much larger than the Moon but it is the precise vastly greater distance that gives it the same apparent size as the much closer and much smaller Moon from the perspective of Earth. The variations in apparent size, due to the non-circular orbits, are nearly the same as well, though occurring in different cycles. This makes possible both

text: total

text: (with the Moon appearing larger than the Sun) and

text: annular

text: (with the Moon appearing smaller than the Sun) solar eclipses. In a total eclipse, the Moon completely covers the disc of the Sun and the solar

text: corona

text: becomes visible to the

text: naked eye

text: . Because the distance between the Moon and Earth is very slowly increasing over time, the angular diameter of the Moon is decreasing. Also, as it evolves toward becoming a

text: red giant

text: , the size of the Sun, and its apparent diameter in the sky, are slowly increasing. The combination of these two changes means that hundreds of millions of years ago, the Moon would always completely cover the Sun on solar eclipses, and no annular eclipses were possible. Likewise, hundreds of millions of years in the future, the Moon will no longer cover the Sun completely, and total solar eclipses will not occur.

text: While several Jovian-sized planets have been discovered, most have been found orbiting close to their stars. It is now hypothesized that Jupiter's movement in the Solar System may have cleared the way for the rocky inner planets, including Earth, to form. The similarity extends to the star that centers the system; like the Sun, HIP 11915 is a G-class star.

text: While several Jovian-sized planets have been discovered, most have been found orbiting close to their stars. It is now hypothesized that Jupiter's movement in the Solar System

text: may have cleared the way

text: for the rocky inner planets, including

text: Earth

text: , to form. The similarity extends to the star that centers the system; like the

text: Sun

text: , HIP 11915 is a

text: G-class

text: star.

text: Though life is confirmed only on Earth, many think that extraterrestrial life is not only plausible, but probable or inevitable. Other planets and moons in the Solar System and other planetary systems are being examined for evidence of having once supported simple life, and projects such as SETI are trying to detect radio transmissions from possible alien civilizations. Other locations within the Solar System that may host microbial life include the subsurface of Mars, the upper atmosphere of Venus, and subsurface oceans on some of the moons of the giant planets.Beyond the Solar System, the region around another main-sequence star that could support Earth-like life on an Earth-like planet is known as the habitable zone. The inner and outer radii of this zone vary with the luminosity of the star, as does the time interval during which the zone survives. Stars more massive than the Sun have a larger habitable zone, but remain on the main sequence for a shorter time interval. Small red dwarfs have the opposite problem, with a smaller habitable zone that is subject to higher levels of magnetic activity and the effects of tidal locking from close orbits. Hence, stars in the intermediate mass range such as the Sun may have a greater likelihood for Earth-like life to develop. The location of the star within a galaxy may also affect the likelihood of life forming. Stars in regions with a greater abundance of heavier elements that can form planets, in combination with a low rate of potentially habitat-damaging supernova events, are predicted to have a higher probability of hosting planets with complex life. The variables of the Drake equation are used to discuss the conditions in planetary systems where civilization is most likely to exist. Use of the equation to predict the amount of extraterrestrial life, however, is difficult; because many of the variables are unknown, the equation functions as more of a mirror to what its user already thinks. As a result, the number of civilizations in the galaxy can be estimated as low as 9.1 x 10^-11 or as high as 156 million; for the calculations, see Drake equation.

text: Though life is confirmed only on Earth, many think that

text: extraterrestrial life

text: is not only plausible, but probable or inevitable. Other planets and

text: moons

text: in the

text: Solar System

text: and other

text: planetary system

text: s are being examined for evidence of having once supported simple life, and projects such as

text: SETI

text: are trying to detect radio transmissions from possible alien civilizations. Other locations within the

text: Solar System

text: that may host

text: microbial

text: life include the subsurface of

text: Mars

text: , the upper atmosphere of

text: Venus

text: , and subsurface oceans on some of the

text: moons

text: of the

text: giant planet

text: s.Beyond the Solar System, the region around another

text: main-sequence star

text: that could support Earth-like life on an Earth-like planet is known as the

text: habitable zone

text: . The inner and outer radii of this zone vary with the luminosity of the star, as does the time interval during which the zone survives. Stars more massive than the Sun have a larger habitable zone, but remain on the main sequence for a shorter time interval. Small

text: red dwarf

text: s have the opposite problem, with a smaller habitable zone that is subject to higher levels of magnetic activity and the effects of

text: tidal locking

text: from close orbits. Hence, stars in the intermediate mass range such as the Sun may have a greater likelihood for Earth-like life to develop. The location of the star within a galaxy may also affect the likelihood of life forming. Stars in regions with a greater abundance of heavier elements that can form planets, in combination with a low rate of potentially

text: habitat

text: -damaging

text: supernova

text: events, are predicted to have a higher probability of hosting planets with complex life. The variables of the

text: Drake equation

text: are used to discuss the conditions in planetary systems where civilization is most likely to exist. Use of the equation to predict the amount of extraterrestrial life, however, is difficult; because many of the variables are unknown, the equation functions as more of a mirror to what its user already thinks. As a result, the number of civilizations in the galaxy can be estimated as low as 9.1 x 10^-11 or as high as 156 million; for the calculations, see

text: Drake equation

text: The estimated masses of planets b - f fall in the range between those of Earth and Neptune. Their estimated densities, all lower than that of Earth, imply that none of them have an Earth-like composition; a significant hydrogen/helium atmosphere is predicted for planets c, d, e, f, and g, while planet b may be surrounded by a steam atmosphere or perhaps by a hydrogen atmosphere.  The low densities likely result from high-volume extended atmospheres that surround cores of iron, rock, and possibly HO.  The inner constituents of the Kepler-11 system were, at the time of their discoveries, the most comprehensively understood extrasolar planets smaller than Neptune.  Currently, observations do not place a firm constraint on the mass of planet g (<25 M).  However, formation and evolution studies indicate that the mass of planet g is not much greater than about 7 M.

text: The estimated masses of planets b - f fall in the range between those of

text: Earth

text: and

text: Neptune

text: . Their estimated densities, all lower than that of Earth, imply that none of them have an Earth-like composition; a significant

text: hydrogen

text: helium

text: atmosphere is predicted for planets c, d, e, f, and g, while planet b may be surrounded by a

text: steam

text: atmosphere or perhaps by a

text: hydrogen

text: atmosphere.  The low densities likely result from high-volume extended atmospheres that surround cores of iron, rock, and possibly HO.  The inner constituents of the Kepler-11 system were, at the time of their discoveries, the most comprehensively understood extrasolar planets smaller than Neptune.  Currently, observations do not place a firm constraint on the mass of planet g (<25

text: M

text: ).  However, formation and evolution studies indicate that the mass of planet g is not much greater than about 7

text: M

text: In the future, mankind has made great advances in interstellar travel and subsequently colonised the Solar System. The extrasolar settlements, research outposts, mines, commercial colonies, and spacecraft and space stations throughout the Solar System are protected over by a mighty, interstellar military conglomerate named the Planet Defense Corps.

text: In the future, mankind has made great advances in

text: interstellar travel

text: and subsequently

text: colonised

text: the

text: Solar System

text: . The

text: extrasolar

text: settlements, research outposts, mines, commercial colonies, and spacecraft and

text: space station

text: s throughout the Solar System are protected over by a mighty, interstellar military conglomerate named the Planet Defense Corps.

text: Also, if another similar planet orbited at 0.71 AU from Alpha Centauri B (so that in turn Alpha Centauri B appeared as bright as the Sun seen from the Earth), this hypothetical planet would receive slightly more light from the more luminous Alpha Centauri A, which would shine 4.7 to 7.3 magnitudes dimmer than Alpha Centauri B (or the Sun seen from the Earth), ranging in apparent magnitude between −19.4 (dimmest) and −22.1 (brightest). Thus Alpha Centauri A would appear between 830 and 70 times dimmer than the Sun but some 580 to 6900 times brighter than the full Moon. During such planet's orbital period of 0.6(3) a, an observer on the planet would see this intensely bright companion star circle the sky just as humans see with the Solar System's planets. Furthermore, Alpha Centauri A's sidereal period of approximately eighty years means that this star would move through the local ecliptic as slowly as Uranus with its eighty-four year period, but as the orbit of Alpha Centauri A is more elliptical, its apparent magnitude will be far more variable. Although intensely bright to the eye, the overall illumination would not significantly affect climate nor influence normal plant photosynthesis.

text: Also, if another similar planet orbited at 0.71 AU from Alpha Centauri B (so that in turn Alpha Centauri B appeared as bright as the Sun seen from the Earth), this hypothetical planet would receive slightly more light from the more luminous Alpha Centauri A, which would shine 4.7 to 7.3 magnitudes dimmer than Alpha Centauri B (or the Sun seen from the Earth), ranging in apparent magnitude between −19.4 (dimmest) and −22.1 (brightest). Thus Alpha Centauri A would appear between 830 and 70 times dimmer than the Sun but some 580 to 6900 times brighter than the full Moon. During such planet's orbital period of 0.6(3)

text: a

text: , an observer on the planet would see this intensely bright companion star circle the sky just as humans see with the

text: Solar System

text: 's planets. Furthermore, Alpha Centauri A's

text: sidereal period

text: of approximately eighty years means that this star would move through the local

text: ecliptic

text: as slowly as

text: Uranus

text: with its eighty-four year period, but as the orbit of Alpha Centauri A is more elliptical, its apparent magnitude will be far more variable. Although intensely bright to the eye, the overall illumination would not significantly affect climate nor influence normal plant

text: photosynthesis

text: In 1991, in order to clarify the relationships between space-time coordinates, new time scales were introduced, each with a different frame of reference. Terrestrial Time is time at Earth's surface. Geocentric Coordinate Time is a coordinate time scale at Earth's center. Barycentric Coordinate Time is a coordinate time scale at the center of mass of the solar system, which is called the barycenter. Barycentric Dynamical Time is a dynamical time at the barycenter.

text: The same applies to other more complex biosignatures. Searching for biological remains of the precursors to life, whether ancient or currently existing, would be far easier on an uncontaminated planet. This would similarly apply to searches for DNA sequences on Mars. Life on other planets could have a common origin with Earth life, since in the early Solar System there was much exchange of material between the planets which could have transferred life as well. If so it might be based on DNA too.

text: To gain a better understanding of the set of parts of the solar apparatus just described one should pay particular attention to the apparent motion of the sun or stars, around the earth, regarding the earth as lies center of their daily revolutions. A distinct view of the apparent conical motion of the sun, when it has north or south declination, is necessary, in order to understand how the movable parts of the solar apparatus may be adjusted to trace the sun, in its apparent course, while the sights of the sun compass remains stationary. If one imagined he was at the Earth's equator and the sun had no declination, the sun would rise to him due east, and set due west. At noon the sun would be at the highest point, and in the lowest point at midnight. In other words, when the sun has no declination, its apparent revolutions are in a perfect plane with the Earth's equator.

text: The giant planet is Neptune-sized, about 20-55 Earth-masses (). It has a radius 6.2 times that of Earth's. The star system is 5000 light years from Earth. The planet orbits a close binary, with a more distant binary orbiting at a distance, forming the quadruple star system. The star system has the Kepler Input Catalogue name KIC 4862625 as well as the designation Kepler-64. The close binary (Aa+Ab) that the planet circles has an orbital period of 20 days. They form an eclipsing binary pair. The two stars are (Aa) 1.5 solar mass () F-type main-sequence star and (Ab)  red dwarf. The planet orbits this binary pair in a 138.3-day orbit. The binary pairs have a separation of 1000 AUs. A photometric-dynamical model was used to model the planetary system of the close binary pair. The distant binary (Ba+Bb) have a pair separation of 60 AU. The two stars are (Ba)  G-type main-sequence star and (Bb)  red dwarf. The quadruple star system has an estimated age of 2 gigayears. The system is located at right ascension  declination , so also has a 2MASS catalogue entry of 2MASS 19525162+3957183

text: The

text: giant planet

text: is

text: Neptune

text: -sized, about 20-55

text: Earth-masses

text: (). It has a radius 6.2 times that of Earth's. The star system is 5000

text: light year

text: s from Earth. The planet orbits a close

text: binary

text: , with a more distant binary orbiting at a distance, forming the quadruple star system. The star system has the Kepler Input Catalogue name

text: KIC 4862625

text: as well as the designation

text: . The close binary (Aa+Ab) that the planet circles has an orbital period of 20 days. They form an

text: eclipsing binary

text: pair. The two stars are (Aa) 1.5

text: solar mass

text: F-type main-sequence star

text: and (Ab)

text: red dwarf

text: . The planet orbits this binary pair in a 138.3-day orbit. The binary pairs have a separation of 1000

text: AU

text: s. A photometric-dynamical model was used to model the

text: planetary system

text: of the close binary pair. The distant binary (Ba+Bb) have a pair separation of 60 AU. The two stars are (Ba)

text: G-type main-sequence star

text: and (Bb)  red dwarf. The quadruple star system has an estimated age of 2 gigayears. The system is located at

text: right ascension

text: declination

text: , so also has a

text: catalogue entry of

text: 2MASS 19525162+3957183

text: Diffuse emission nebula, or H II region, in the constellation Sagittarius cataloged as M17, and named the Omega Nebula in 1833 by John Herschel because in his limited-resolution view its shape resembled the Greek letter Ω. Located between five and six thousand light-years from the Earth, It is considered one of the brightest and most massive star-forming regions of our galaxy, containing a collection of over 1000 stars—although it is one of the youngest clusters known, with an age of just 1 million years. Its local geometry is similar to the Orion Nebula except that it is viewed edge-on from the Earth rather than face-on.

text: Diffuse emission nebula, or H II region, in the constellation Sagittarius cataloged as

text: , and named the Omega Nebula in 1833 by

text: John Herschel

text: because in his limited-resolution view its shape resembled the

text: Greek letter Ω

text: . Located between five and six thousand light-years from the Earth, It is considered one of the brightest and most massive star-forming regions of our galaxy, containing a collection of over 1000 stars—although it is one of the youngest clusters known, with an age of just 1 million years. Its local geometry is similar to the Orion Nebula except that it is viewed edge-on from the Earth rather than face-on.

text: Stardust's discovery of crystalline silicates in the dust of comet Wild 2 implies that the dust formed above glass temperature (> 1000 K) in the inner disk region around a hot young star, and was radially mixed in the solar nebula from the inner regions a larger distance from the star or the dust particle condensed in the outflow of evolved red giants or supergiants. The composition of the dust of comet Wild 2 is similar to the composition of dust found in the outer regions of the accretion disks around newly-forming stars.

text: Stardust

text: 's discovery of crystalline silicates in the dust of comet

text: Wild 2

text: implies that the dust formed above

text: glass temperature

text: (> 1000 K) in the inner disk region around a hot young star, and was radially mixed in the solar nebula from the inner regions a larger distance from the star or the dust particle condensed in the outflow of evolved red giants or supergiants. The composition of the dust of comet Wild 2 is similar to the composition of dust found in the outer regions of the accretion disks around newly-forming stars.

text: In astronomy, Galactocentrism is the theory that our sun is at or near the center of the galaxy. Observations by William Herschel in 1785 indicated that the Milky Way was a separate disk-shaped galaxy with the sun in a central position. Although proved incorrect by Harlow Shapley in 1918, the theory was a step in the development of cosmological models as the speculation of the existence of other galaxies, comparable in size and structure to our own, placed the earth in its proper perspective with respect to the rest of the universe.

text: In

text: astronomy

text: , Galactocentrism is the theory that our sun is at or near the center of the

text: galaxy

text: . Observations by

text: William Herschel

text: in 1785 indicated that the

text: Milky Way

text: was a separate disk-shaped galaxy with the sun in a central position. Although proved incorrect by

text: Harlow Shapley

text: in 1918, the theory was a step in the development of

text: cosmological

text: models as the speculation of the existence of other galaxies, comparable in size and structure to our own, placed the earth in its proper perspective with respect to the rest of the

text: universe

text: Sir Isaac Newton had published his Philosophiae Naturalis Principia Mathematica in 1687 in which he gave a derivation of Kepler's laws, which describe the motion of the planets, from his laws of motion and his law of universal gravitation. However, though Newton had privately developed the methods of calculus, all his published work used cumbersome geometric reasoning, unsuitable to account for the more subtle higher-order effects of interactions between the planets. Newton himself had doubted the possibility of a mathematical solution to the whole, even concluding that periodic divine intervention was necessary to guarantee the stability of the Solar System. Dispensing with the hypothesis of divine intervention would be a major activity of Laplace's scientific life. It is now generally regarded that Laplace's methods on their own, though vital to the development of the theory, are not sufficiently precise to demonstrate the stability of the Solar System, and indeed, the Solar System is understood to be chaotic, although it happens to be fairly stable.

text: Sir

text: Isaac Newton

text: had published his

text: Philosophiae Naturalis Principia Mathematica

text: in 1687 in which he gave a derivation of

text: Kepler's laws

text: , which describe the motion of the planets, from his

text: laws of motion

text: and his

text: law of universal gravitation

text: . However, though Newton had privately developed the methods of calculus, all his published work used cumbersome geometric reasoning, unsuitable to account for the more subtle higher-order effects of interactions between the planets. Newton himself had doubted the possibility of a mathematical solution to the whole, even concluding that periodic

text: divine intervention

text: was necessary to guarantee the stability of the Solar System. Dispensing with the hypothesis of divine intervention would be a major activity of Laplace's scientific life. It is now generally regarded that Laplace's methods on their own, though vital to the development of the theory, are not sufficiently

text: precise

text: to demonstrate the

text: stability of the Solar System

text: , and indeed, the Solar System is understood to be

text: chaotic

text: , although it happens to be fairly stable.

text: The five-planet Nice model is a recent variation of the Nice model that begins with five giant planets, the current four plus an additional ice giant, in a chain of mean-motion resonances. After the resonance chain is broken, the five giant planets undergo a period of planetesimal-driven migration, followed by a gravitational instability similar to that in the original Nice model. During the instability the additional giant planet is scattered inward onto a Jupiter-crossing orbit and is ejected from the Solar System following an encounter with Jupiter. An early Solar System with five giant planets was proposed in 2011 after numerical models indicated that this is more likely to reproduce the current Solar System.

text: The five-planet Nice model is a recent variation of the

text: Nice model

text: that begins with five giant planets, the current four plus an additional ice giant, in a chain of mean-motion resonances. After the resonance chain is broken, the five giant planets undergo a period of planetesimal-driven migration, followed by a gravitational instability similar to that in the original Nice model. During the instability the additional giant planet is scattered inward onto a Jupiter-crossing orbit and is ejected from the Solar System following an encounter with Jupiter. An early Solar System with five giant planets was proposed in 2011 after numerical models indicated that this is more likely to reproduce the current Solar System.

text: Before Galileo turned his telescope to the heavens, the planets of the Solar System were not recognized as worlds, or places where a person could potentially set foot; they were visible to observers merely as bright points of light, distinguishable from stars only by their motion.

text: Before

text: Galileo

text: turned his

text: telescope

text: to the heavens, the planets of the

text: Solar System

text: were not recognized as worlds, or places where a person could potentially set foot; they were visible to observers merely as bright points of light, distinguishable from stars only by their motion.

text: The ancients worked from a geocentric perspective for the simple reason that the Earth was where they stood and observed the sky, and it is the sky which appears to move while the ground seems still and steady underfoot. Some Greek astronomers (e.g., Aristarchus of Samos) speculated that the planets (Earth included) orbited the Sun, but the optics (and the specific mathematics – Newton's Law of Gravitation for example) necessary to provide data that would convincingly support the heliocentric model did not exist in Ptolemy's time and would not come around for over fifteen hundred years after his time.  Furthermore, Aristotelian Physics was not designed with these sorts of calculations in mind, and Aristotle's philosophy regarding the heavens was entirely at odds with the concept of heliocentrism.  It was not until Galileo Galilei observed the moons of Jupiter on January 7, 1610, and the phases of Venus in September 1610 that the heliocentric model began to receive broad support among astronomers, who also came to accept the notion that the planets are individual worlds orbiting the Sun (that is, that Earth is a planet and is one among several). Johannes Kepler was able to formulate his three laws of planetary motion, which described the orbits of the planets in our solar system to a remarkable degree of accuracy; Kepler's three laws are still taught today in university physics and astronomy classes, and the wording of these laws has not changed since Kepler first formulated them four hundred years ago.

text: The ancients worked from a

text: geocentric

text: perspective for the simple reason that the Earth was where they stood and observed the sky, and it is the sky which appears to move while the ground seems still and steady underfoot. Some Greek astronomers (e.g.,

text: Aristarchus of Samos

text: ) speculated that the planets (Earth included) orbited the Sun, but the

text: optics

text: (and the specific mathematics –

text: Newton

text: 's

text: Law of Gravitation

text: for example) necessary to provide data that would convincingly support the

text: heliocentric

text: model did not exist in

text: Ptolemy

text: 's time and would not come around for over fifteen hundred years after his time.  Furthermore,

text: Aristotelian Physics

text: was not designed with these sorts of calculations in mind, and

text: Aristotle

text: 's philosophy regarding the heavens was entirely at odds with the concept of heliocentrism.  It was not until

text: Galileo Galilei

text: observed the moons of

text: Jupiter

text: on January 7, 1610, and the phases of

text: Venus

text: in September 1610 that the heliocentric model began to receive broad support among astronomers, who also came to accept the notion that the planets are individual worlds orbiting the Sun (that is, that Earth is a planet and is one among several).

text: Johannes Kepler

text: was able to formulate his three

text: laws of planetary motion

text: , which described the orbits of the planets in our solar system to a remarkable degree of accuracy; Kepler's three laws are still taught today in university physics and astronomy classes, and the wording of these laws has not changed since Kepler first formulated them four hundred years ago.

text: In Earths in the Universe, it is stated that he conversed with spirits from Jupiter, Mars, Mercury, Saturn, Venus, and the Moon, as well as spirits from planets beyond our solar system. From these 'encounters' he concluded that the planets of our solar system are inhabited, and that such an enormous undertaking as the universe could not have been created for just one race on a planet; nor one 'Heaven' derived from its properties per planet. Many Heavenly societies were also needed to increase the perfection of the angelic Heavens and Heaven, to fill in deficiencies and gaps in other societies. He argued: "What would this be to God, Who is infinite, and to whom a thousand or tens of thousands of planets, and all of them full of inhabitants, would be scarcely anything!". Swedenborg and the life on other planets question has been extensively reviewed elsewhere.

text: In Earths in the Universe, it is stated that he conversed with spirits from

text: Jupiter

text: Mars

text: Mercury

text: Saturn

text: Venus

text: , and the

text: Moon

text: , as well as spirits from planets beyond our solar system. From these 'encounters' he concluded that the planets of our solar system are inhabited, and that such an enormous undertaking as the universe could not have been created for just one race on a planet; nor one 'Heaven' derived from its properties per planet. Many Heavenly societies were also needed to increase the perfection of the angelic Heavens and Heaven, to fill in deficiencies and gaps in other societies. He argued: "What would this be to God, Who is infinite, and to whom a thousand or tens of thousands of planets, and all of them full of inhabitants, would be scarcely anything!". Swedenborg and the life on other planets question has been extensively reviewed elsewhere.

text: The U.S. has some of the largest solar farms in the world. Solar Star is a 579 megawatt (MW) farm near Rosamond, California. Completed in June 2015, it uses 1.7 million solar panels, spread over 13 square kilometers (3,200 acres). The Desert Sunlight Solar Farm is a 550 MW solar power plant in Riverside County, California, that uses thin-film solar photovoltaic modules made by First Solar. The Topaz Solar Farm is a 550 MW photovoltaic power plant, in San Luis Obispo County, California. The Blythe Solar Power Project is a 485 MW photovoltaic station planned for Riverside County, California.

text: The U.S. has some of the

text: largest solar farms

text: in the world.

text: Solar Star

text: is a 579

text: megawatt

text: (MW

text: ) farm near

text: Rosamond, California

text: . Completed in June 2015, it uses 1.7 million solar panels, spread over 13 square kilometers (3,200 acres). The

text: Desert Sunlight Solar Farm

text: is a 550 MW

text: solar power

text: plant in

text: Riverside County, California

text: , that uses thin-film solar

text: photovoltaic

text: modules made by

text: First Solar

text: . The

text: Topaz Solar Farm

text: is a 550 MW photovoltaic power plant, in

text: San Luis Obispo County, California

text: . The

text: Blythe Solar Power Project

text: is a 485 MW photovoltaic station planned for

text: Riverside County, California

text: Variations of D/H ratio in the solar system

text: A partial solar eclipse occurred on August 30, 1924. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: occurred on August 30, 1924. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: , thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: The Ross stars in this list (but not all stars in the Ross catalog) are red dwarfs, and they are among the closest stars to the Solar System. They were catalogued beginning in 1926 by the American astronomer Frank Elmore Ross, and some of them are still widely known by the catalog number he gave them (for one that is not, see Ross 780). The stars listed below, despite their faint magnitudes (all numerically greater than 10), have attracted the attention of authors and game developers interested in fiction depicting the earliest stages of humanity's expansion into the galaxy. At least one of the Ross stars has been confirmed to possess multiple extrasolar planets as of 2013.

text: The Ross stars in this list (but not all stars in the Ross catalog) are

text: red dwarfs

text: , and they are among the closest stars to the Solar System. They were catalogued beginning in 1926 by the American astronomer

text: Frank Elmore Ross

text: , and some of them are still widely known by the catalog number he gave them (for one that is not, see

text: Ross 780)

text: . The stars listed below, despite their faint magnitudes (

text: all numerically greater than 10

text: ), have attracted the attention of authors and game developers interested in fiction depicting the earliest stages of humanity's expansion into the galaxy.

text: At least one

text: of the Ross stars has been

text: confirmed

text: to possess multiple extrasolar planets as of 2013.

text: In the 70's, Jürgen Moser sketched a proof, based on K.A.M. theory, that outer billiards relative to a6-times-differentiable  shape of positive curvature has all orbits bounded.In 1982, Raphael Douady gave the full proof of this result.A big advance in the polygonal case came over a period of several years whenthree teams of authors, Vivaldi-Shaidenko (1987), Kolodziej (1989), and Gutkin-Simanyi (1991), each using different methods,showed that outerbilliards relative to a quasirational polygon has all orbits bounded.   The notion of quasirational is technical(see references) but it includes the class of regular polygons and  convex rational polygons, namely those convex polygons whose vertices have rational coordinates.  In the case of rational polygons, all the orbits areperiodic.  In 1995, Tabachnikov showed that outer billiards for the regular pentagon has some aperiodic orbits,thus clarifying the distinction between the dynamics in the rational and regular cases.In 1996, Boyland showed that outer billiards relative to some shapes can have orbits which accumulate onthe shape.In 2005, D. Genin showed that all orbits are bounded when the shape is a trapezoid, thusshowing that quasirationality is not a necessary condition for the system to have all orbits bounded.(Not all trapezoids are quasirational.)

text: In the 70's,

text: Jürgen Moser

text: sketched a proof, based on

text: K.A.M. theory

text: , that outer billiards relative to a6-times-

text: differentiable

text: shape of positive

text: curvature

text: has all orbits bounded.In 1982,

text: Raphael Douady

text: gave the full proof of this result.A big advance in the polygonal case came over a period of several years whenthree teams of authors, Vivaldi-Shaidenko (1987), Kolodziej (1989), and Gutkin-Simanyi (1991), each using different methods,showed that outerbilliards relative to a quasirational polygon has all orbits bounded.   The notion of quasirational is technical(see references) but it includes the class of

text: regular polygons

text: and  convex rational polygons, namely those

text: convex polygon

text: s whose vertices have

text: rational

text: coordinates.  In the case of rational polygons, all the orbits areperiodic.  In 1995, Tabachnikov showed that outer billiards for the

text: regular pentagon

text: has some aperiodic orbits,thus clarifying the distinction between the dynamics in the rational and regular cases.In 1996, Boyland showed that outer billiards relative to some shapes can have orbits which accumulate onthe shape.In 2005, D. Genin showed that all orbits are bounded when the shape is a

text: trapezoid

text: , thusshowing that quasirationality is not a necessary condition for the system to have all orbits bounded.(Not all

text: trapezoids

text: are quasirational.)

text: A partial solar eclipse occurred on May 9, 1967. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: occurred on May 9, 1967. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: Even as the angle increases, the addition of an Earth-based view, e.g., from the Solar Dynamics Observatory, will still provide full-Sun observations for several years. In 2015, contact was lost for several months when the STEREO spacecraft passed behind the Sun. They will then start to approach Earth again, with closest approach sometime in 2023. They will not be recaptured into Earth orbit.

text: Even as the angle increases, the addition of an Earth-based view, e.g., from the

text: Solar Dynamics Observatory

text: , will still provide full-Sun observations for several years. In 2015, contact was lost for several months when the STEREO spacecraft passed behind the Sun. They will then start to approach Earth again, with closest approach sometime in 2023. They will not be recaptured into Earth orbit.

text: The planet Jupiter is two and a half times as massive as all of the other planets in the Solar System combined.

text: The

text: planet

text: Jupiter

text: is two and a half times as massive as all of the other planets in the

text: Solar System

text: combined.

text: The following sections exhibit a collection of real nebulae that contain imaginary stars or planetary systems, or that otherwise serve as settings for works of science fiction:

text: Additionally, the book chronicles some of Galileo's scientific work. Galileo's astronomical discoveries, Dava Sobel claims, led him to adopt the Copernican system, in which the Sun is the center of the solar system with all the planets orbiting it.  However, according to the Biblical interpretation at that time, the Earth was the center of the universe and was stationary.  When Galileo wished to publish a book which argued for the Copernican system, he attained the required stamp of approval from the religious authority (a requirement for all books published in Italy at the time) but circumstances led Pope Urban VIII to ban it and denounce Galileo as a heretic, even though he was a devout Catholic. Unauthorized copies of the book, however, found their way to prominent scholars outside of Italy and it was published in countries that were not under the Pope's rule, such as Germany and Denmark.

text: Additionally, the book chronicles some of Galileo's scientific work. Galileo's astronomical discoveries, Dava Sobel claims, led him to adopt the

text: Copernican

text: system, in which the

text: Sun

text: is the center of the

text: solar system

text: with all the

text: planet

text: s orbiting it.  However, according to the

text: Biblical

text: interpretation at that time, the

text: Earth

text: was the center of the

text: universe

text: and was stationary.  When Galileo wished to publish a book which argued for the Copernican system, he attained the required stamp of approval from the religious authority (a requirement for all books published in Italy at the time) but circumstances led

text: Pope Urban VIII

text: to ban it and denounce Galileo as a

text: heretic

text: , even though he was a devout

text: Catholic

text: . Unauthorized copies of the book, however, found their way to prominent scholars outside of Italy and it was published in countries that were not under the Pope's rule, such as Germany and

text: Denmark

text: Among the extrasolar planets discovered to date are planets the size of Jupiter or larger but possessing very short orbital periods of only a few hours. Such planets would have to orbit very closely to their stars; so closely that their atmospheres would be gradually stripped away by solar radiation. There is no consensus on how to explain these so-called hot Jupiters, but one leading idea is that of planetary migration, similar to the process which is thought to have moved Uranus and Neptune to their current, distant orbit. Possible processes that cause the migration include orbital friction while the protoplanetary disc is still full of hydrogen and helium gasand exchange of angular momentum between giant planets and the particles in the protoplanetary disc.

text: Among the extrasolar planets discovered to date are planets the size of Jupiter or larger but possessing very short orbital periods of only a few hours. Such planets would have to orbit very closely to their stars; so closely that their atmospheres would be gradually stripped away by solar radiation. There is no consensus on how to explain these so-called

text: hot Jupiters

text: , but one leading idea is that of

text: planetary migration

text: , similar to the process which is thought to have moved Uranus and Neptune to their current, distant orbit. Possible processes that cause the migration include orbital friction while the protoplanetary disc is still full of hydrogen and helium gasand exchange of angular momentum between giant planets and the particles in the protoplanetary disc.

text: The heliocentric ecliptic system describes the planets' orbital movement around the Sun, and centers on the barycenter of the solar system (i.e. very close to the center of the Sun). The system is primarily used for computing the positions of planets and other solar system bodies, as well as defining their orbital elements.

text: The heliocentric ecliptic system describes the planets' orbital movement around the Sun, and centers on the

text: barycenter

text: of the solar system (i.e. very close to the center of the Sun). The system is primarily used for computing the positions of planets and other solar system bodies, as well as defining their

text: orbital elements

text: In the religion and philosophy of the Ingush people, the Solar emblem (in the center of the flag) represents not only the sun and the universe but also awareness of the oneness of the spirit in the past, present and future.  The red recalls the struggle of the Ingush people for existence and in the defense of their homeland.  The white symbolizes the divine purity of the thoughts and views of the nation.  The green is the symbol of Islam.

text: In the religion and philosophy of the

text: Ingush people

text: , the Solar emblem (in the center of the flag) represents not only the

text: sun

text: and the universe but also awareness of the oneness of the spirit in the past, present and future.  The red recalls the struggle of the Ingush people for existence and in the defense of their homeland.  The white symbolizes the divine purity of the thoughts and views of the nation.  The green is the symbol of

text: Islam

text: In phases of the meteorites Semarkona and Chervony Kut a correlation between the concentration of Ni, the granddaughter isotope of Fe, and the abundance of the stable iron isotopes could be found, which is evidence for the existence of Fe at the time of formation of the solar system. Possibly the energy released by the decay of Fe contributed, together with the energy released by decay of the radionuclide Al, to the remelting and differentiation of asteroids after their formation 4.6 billion years ago. The abundance of Ni present in extraterrestrial material may also provide further insight into the origin of the solar system and its early history.

text: In phases of the meteorites Semarkona and Chervony Kut a correlation between the concentration of

text: Ni

text: , the

text: granddaughter isotope

text: of Fe, and the abundance of the stable iron isotopes could be found, which is evidence for the existence of Fe at the time of formation of the solar system. Possibly the energy released by the decay of Fe contributed, together with the energy released by decay of the radionuclide

text: Al

text: , to the remelting and

text: differentiation

text: of

text: asteroid

text: s after their formation 4.6 billion years ago. The abundance of

text: Ni

text: present in

text: extraterrestrial

text: material may also provide further insight into the origin of the

text: solar system

text: and its early history.

text: A further twelve bodies, pending refinements of knowledge regarding their physical properties, were possible candidates to join the list under this definition. Some objects in this second list were more likely eventually to be adopted as 'planets' than others. Despite what had been claimed in the media, the proposal did not necessarily leave the Solar System with only twelve planets. Mike Brown, the discoverer of Sedna and Eris, has said that at least 53 known bodies in the Solar System probably fit the definition, and that a complete survey would probably reveal more than 200.

text: A further twelve bodies, pending refinements of knowledge regarding their physical properties, were possible candidates to join the list under this definition. Some objects in this second list were more likely eventually to be adopted as 'planets' than others. Despite what had been claimed in the media, the proposal did not necessarily leave the Solar System with only twelve planets.

text: Mike Brown

text: , the discoverer of

text: Sedna

text: and Eris, has said that at least 53 known bodies in the Solar System probably fit the definition, and that a complete survey would probably reveal more than 200.

text: The motions as described above are simplifications. Due to the movement of Earth around the Earth–Moon center of mass, the apparent path of the Sun wobbles slightly, with a period of about one month. Due to further perturbations by the other planets of the Solar System, the Earth–Moon barycenter wobbles slightly around a mean position in a complex fashion. The ecliptic is actually the apparent path of the Sun throughout the course of a year.

text: The motions as described above are simplifications. Due to the movement of Earth around the Earth–Moon

text: center of mass

text: , the apparent path of the Sun wobbles slightly, with a period of about

text: one month

text: . Due to further

text: perturbations

text: by the other

text: planet

text: s of the

text: Solar System

text: , the Earth–Moon

text: barycenter

text: wobbles slightly around a mean position in a complex fashion. The ecliptic is actually the apparent path of the Sun throughout the course of a

text: year

text: This permanent exhibit focuses on the planets within our solar system. Within this exhibit there are planetary models that are showcased in an array of sizes. Saturn, Jupiter, Uranus and Neptune hang high above the second-floor, nearly 30 feet high. These four models are the largest in the country to be displayed inside a museum or science center. Jupiter, the largest of the models, weighs more than 750 pounds, has a diameter of 10 feet, and hangs approximately 22 feet in the air. Saturn is eight-and-a-half feet in diameter and weighs 450 pounds, with an additional 495 pounds of rings encircling the planet's body. Hanging more than 30 feet high, Saturn floats above Uranus and Neptune which each weigh around 65 pounds. The models are composed of heavy-duty Styrofoam which is painted to resemble each of the planets. The Solar System is completed with smaller models of Earth, Mars, Venus and Mercury mounted at the visitor's level. Created to be a scale model system, Earth is about the size as a soccer ball and Mercury measures up to a mere baseball.

text: This permanent exhibit focuses on the planets within our

text: solar system

text: . Within this exhibit there are planetary models that are showcased in an array of sizes.

text: Saturn

text: Jupiter

text: Uranus

text: and

text: Neptune

text: hang high above the second-floor, nearly 30 feet high. These four models are the largest in the country to be displayed inside a museum or science center.

text: Jupiter

text: , the largest of the models, weighs more than 750 pounds, has a diameter of 10 feet, and hangs approximately 22 feet in the air.

text: Saturn

text: is eight-and-a-half feet in diameter and weighs 450 pounds, with an additional 495 pounds of rings encircling the planet's body. Hanging more than 30 feet high,

text: Saturn

text: floats above

text: Uranus

text: and

text: Neptune

text: which each weigh around 65 pounds. The models are composed of heavy-duty Styrofoam which is painted to resemble each of the planets. The

text: Solar System

text: is completed with smaller models of

text: Earth

text: Mars

text: Venus

text: and

text: Mercury

text: mounted at the visitor's level. Created to be a scale model system,

text: Earth

text: is about the size as a soccer ball and

text: Mercury

text: measures up to a mere baseball.

text: In 1960, 1963, and 1978, W. H. McCrea proposed the protoplanet theory, in which the Sun and planets individually coalesced from matter within the same cloud, with the smaller planets later captured by the Sun's larger gravity. It includes fission in a protoplanetary nebula and there is no solar nebula. Agglomerations of floccules (which are presumed to compose the supersonic turbulence assumed to occur in the interstellar material from which stars are born) formed the Sun and protoplanets, the latter splitting to form planets. The 2 portions can not remain gravitationally bound to each other,  are at a mass ratio of at least 8 to 1, and for inner planets they go into independent orbits while for outer planets one of the portions exits the Solar System. The inner protoplanets were Venus-Mercury and Earth-Mars. The moons of the greater planets were formed from "droplets" in the neck connecting the 2 portions of the dividing protoplanet and these droplets could account for some of the asteroids. Terrestrial planets would have no major moons which does not account for Luna.  It predicts certain observations such as the similar angular velocity of Mars and Earth with similar rotation periods and axial tilts. In this scheme there are 6 principal planets: 2 terrestrial, Venus and Earth, 2 major, Jupiter and Saturn, and 2 outer, Uranus and Neptune; and 3 lesser planets: Mercury, Mars, and Pluto.

text: In 1960, 1963, and 1978,

text: W. H. McCrea

text: proposed the protoplanet theory, in which the Sun and planets individually coalesced from matter within the same cloud, with the smaller planets later captured by the Sun's larger gravity. It includes fission in a protoplanetary nebula and there is no solar nebula. Agglomerations of floccules (which are presumed to compose the supersonic turbulence assumed to occur in the interstellar material from which stars are born) formed the Sun and protoplanets, the latter splitting to form planets. The 2 portions can not remain gravitationally bound to each other,  are at a mass ratio of at least 8 to 1, and for inner planets they go into independent orbits while for outer planets one of the portions exits the Solar System. The inner protoplanets were Venus-Mercury and Earth-Mars. The moons of the greater planets were formed from "droplets" in the neck connecting the 2 portions of the dividing protoplanet and these droplets could account for some of the asteroids. Terrestrial planets would have no major moons which does not account for Luna.  It predicts certain observations such as the similar angular velocity of Mars and Earth with similar rotation periods and axial tilts. In this scheme there are 6 principal planets: 2 terrestrial, Venus and Earth, 2 major, Jupiter and Saturn, and 2 outer, Uranus and Neptune; and 3 lesser planets: Mercury, Mars, and Pluto.

text: Projects[edit]Introduction of Clean Energy by Solar Electricity Generation System[edit]On May 29, 2012, Pakistan inaugurated its first solar power on-grid power plant in Islamabad. Introduction of Clean Energy by Solar Electricity Generation System is a special grant aid project by the Japan International Cooperation Agency (JICA) under the Coolio Earth Partnership. This project includes the installation of two 178 kW photovoltaic (PV) systems at the premises of the Planning Commission and Pakistan Engineering Council.

text: Some Solar System object classes, such as minor planets, dwarf planets and Trans-Neptunian objects have not been detected outside the Solar System.

text: Some Solar System object classes, such as

text: minor planet

text: s,

text: dwarf planet

text: s and

text: Trans-Neptunian object

text: s have not been detected outside the Solar System.

text: Out of the more than 200 extrasolar planet discoveries (as of 2006), 15 planets have high eccentricities (e > 0.6).

text: As he speaks, we transition to the Sun, and watching a Sun Spot spin into view, we dive into and pass through the chromosphere, and head toward the center. The mentor lays down the basis of our story as we travel through the Sun. He explains that the "man in the sun is called the Core (voiced by William Shatner)" and spins a story how he is good and that his children "photons" are sent out to chase away the darkness, and bring life, warmth, and knowledge to Earth. He adds that the only being who does not like the Core is a creature called the "Void" (voiced by Mark Hamill) who is an ancient, malevolent, being who existed before the Big Bang, and who sits at the edge of the solar system, scheming to stop the Core.

text: As he speaks, we

text: transition

text: to the Sun, and watching a Sun Spot spin into view, we dive into and pass through the

text: chromosphere

text: , and head toward the

text: center

text: . The mentor lays down the basis of our story as we travel through the Sun. He explains that the "man in the sun is called the Core (voiced by

text: William Shatner

text: )" and spins a story how he is good and that his children "

text: photons

text: " are sent out to chase away the darkness, and bring life, warmth, and knowledge to Earth. He adds that the only being who does not like the Core is a creature called the "Void" (voiced by

text: Mark Hamill

text: ) who is an ancient, malevolent, being who existed before the

text: Big Bang

text: , and who sits at the edge of the

text: solar system

text: , scheming to stop the Core.

text: Tyson then notes that humans have discovered means of harvesting solar power. At the 1878 World's Fair Augustin Mouchot won a gold medal for his solar power concentrator. In 1913 Frank Shuman constructed a solar powered irrigation plant in Egypt, with a view to transforming Sahara to arable land. Tyson points out that in both cases, the economics and ease of using cheap coal and oil caused these inventions to be overlooked at the time. Today, solar and wind-power systems would be able to collect enough solar energy from the Sun easily. Tyson then compares the motivation for switching to these cleaner forms of energy to the efforts of the Space Race and emphasizes that it is not too late for humanity to correct its course.

text: Tyson then notes that humans have discovered means of harvesting solar power. At the

text: 1878 World's Fair

text: Augustin Mouchot

text: won a gold medal for his

text: solar power concentrator

text: . In 1913

text: Frank Shuman

text: constructed a solar powered

text: irrigation plant

text: in Egypt, with a view to transforming Sahara to

text: arable land

text: . Tyson points out that in both cases, the economics and ease of using cheap coal and

text: oil

text: caused these inventions to be overlooked at the time. Today, solar and wind-power systems would be able to collect enough

text: solar energy

text: from the Sun easily. Tyson then compares the motivation for switching to these cleaner forms of energy to the efforts of the

text: Space Race

text: and emphasizes that it is not too late for humanity to correct its course.

text: A partial solar eclipse will occur on July 12, 2094. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: will occur on July 12, 2094. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: He has also immersed himself in the field of solar technology and designed the façade of a high bay warehouse in Coeseld-Lette using photovoltaic modules.The warehouse's folded design of the solar modules extends vertically, bending over the roof and hovering on a framed mounted system above the landscaped roof. The facade is constructed out of deep-black solar modules and greenish-blue sparkling crash glass, two contrasting components generating an electrifying force. The folding effect arises from the installation of the two main elements on the solar facade: alternating, solar modules and crash glass are arranged gradually in a 32° angle of inclination, which guarantees an optimal solar radiation at the geographical location of Coesfeld.This folded, cascading arrangement of the PV-modules not only optimally uses the sun’s energy, but also provides shade for the glass building behind it. The interior of the warehouse requires no additional cooling. In winter, when the sun is low and the rays are flat, the shading effect is limited and consequently heating is not necessary. As a result, the warehouse can be operated with only an automatic ventilation system. A unique and exemplary symbiosis of engineering and design, his artistic approach to the photovoltaic facade received the architecture award of the Stiftung Deutsche Pfandbriefbank.His highly innovative method of fusing a crash glass picture into single pane safety glass without the use of additional adhesives is patented.

text: He has also immersed himself in the field of solar technology and designed the façade of a

text: high bay warehouse

text: in Coeseld-Lette using

text: photovoltaic modules

text: .The warehouse's folded design of the solar modules extends vertically, bending over the roof and hovering on a framed mounted system above the landscaped roof. The facade is constructed out of deep-black solar modules and greenish-blue sparkling crash glass, two contrasting components generating an electrifying force. The folding effect arises from the installation of the two main elements on the solar facade: alternating, solar modules and crash glass are arranged gradually in a 32° angle of inclination, which guarantees an optimal solar radiation at the geographical location of Coesfeld.This folded, cascading arrangement of the PV-modules not only optimally uses the sun’s energy, but also provides shade for the glass building behind it. The interior of the warehouse requires no additional cooling. In winter, when the sun is low and the rays are flat, the shading effect is limited and consequently heating is not necessary. As a result, the warehouse can be operated with only an automatic ventilation system. A unique and exemplary symbiosis of engineering and design, his artistic approach to the photovoltaic facade received the architecture award of the Stiftung Deutsche Pfandbriefbank.His highly innovative method of fusing a crash glass picture into single pane safety glass without the use of additional adhesives is patented.

text: The long-lived radionuclides Nb, Tc, Tc and Sm are not among the classically defined p-nuclei as they do not naturally occur on Earth (or, in the case of Sm, occur only in barely detectable traces today). By the above definition, however, they are also p-nuclei because they cannot be made in either s- or r-process. From the discovery of their decay products in presolar grains it can be inferred that at least Nb and Sm were present in the solar nebula. This offers the possibility to estimate the time since the last production of these p-nuclei before the formation of the solar system.

text: The

text: long-lived

text: radionuclide

text: s Nb, Tc, Tc and Sm are not among the classically defined p-nuclei as they do not naturally occur on Earth (or, in the case of Sm, occur only in barely detectable traces today). By the above definition, however, they are also p-nuclei because they cannot be made in either s- or r-process. From the discovery of their

text: decay product

text: s in

text: presolar grains

text: it can be inferred that at least Nb and Sm were present in the

text: solar nebula

text: . This offers the possibility to estimate the time since the last production of these p-nuclei before the formation of the

text: solar system

text: The Sagan Planet Walk has inspired the creation of other scale model solar systems in the United States.

text: The challenge was to make sense of the apparently irregular wanderings of the planets on the assumption that all heavenly motion is actually circular and uniform in speed.  Why circular?  Because, Plato held, the circle is the most perfect and symmetrical form; therefore circular motion, at uniform speed, was most fitting for celestial bodies.  Aristotle agreed with Plato.  In Aristotle's cosmos, everything has a "natural" tendency to motion that fulfills its inner potential.  For the cosmos' sublunary part (the region below the moon), the natural tendency is to move in a straight line:  downward for earthen things (such as rocks) and water; upward for air and fiery things (such as sparks).  But in the celestial realm things are not composed of earth, water, air or fire, but of a "fifth element", or "quintessence," which is perfect and eternal.  And its natural motion is uniformly circular.  The stars, the sun, the moon and the planets are carried in their orbits by a complicated arrangement of crystalline spheres, all centered around an immobile earth.

text: The challenge was to make sense of the apparently irregular wanderings of the planets on the assumption that all heavenly motion is actually circular and uniform in speed.  Why circular?  Because, Plato held, the

text: circle

text: is the most perfect and symmetrical form; therefore circular motion, at uniform speed, was most fitting for celestial bodies.  Aristotle agreed with Plato.  In Aristotle's

text: cosmos

text: , everything has a "natural" tendency to motion that fulfills its inner potential.  For the cosmos' sublunary part (the region below the moon), the natural tendency is to move in a straight line:  downward for earthen things (such as rocks) and water; upward for air and fiery things (such as sparks).  But in the

text: celestial

text: realm things are not composed of earth, water, air or fire, but of a "fifth element", or "

text: quintessence

text: ," which is perfect and eternal.  And its natural motion is uniformly circular.  The stars, the sun, the moon and the planets are carried in their orbits by a complicated arrangement of crystalline spheres, all centered around an immobile earth.

text: At the back of the vehicle is the service module (: приборно-агрегатный отсек, Priborno-Agregatniy Otsek (PAO)). It has an instrumentation compartment (: приборный отсек, Priborniy Otsek (PO)), a pressurized container shaped like a bulging can that contains systems for temperature control, electric power supply, long-range radio communications, radio telemetry, and instruments for orientation and control. The propulsion compartment (: агрегатный отсек, Agregatniy Otsek (AO)), a non-pressurized part of the service module, contains the main engine and a spare: liquid-fuel propulsion systems for maneuvering in orbit and initiating the descent back to Earth. The ship also has a system of low-thrust engines for orientation, attached to the intermediate compartment (: переходной отсек, Perekhodnoi Otsek (PkhO)). Outside the service module are the sensors for the orientation system and the solar array, which is oriented towards the sun by rotating the ship.

text: At the back of the vehicle is the service module (: приборно-агрегатный отсек, Priborno-Agregatniy Otsek (PAO)). It has an instrumentation compartment (: приборный отсек, Priborniy Otsek (PO)), a pressurized container shaped like a bulging can that contains systems for temperature control, electric power supply, long-range

text: radio

text: communications, radio telemetry, and instruments for orientation and control. The propulsion compartment (: агрегатный отсек, Agregatniy Otsek (AO)), a non-pressurized part of the service module, contains the main engine and a spare: liquid-fuel

text: propulsion systems

text: for maneuvering in orbit and initiating the descent back to Earth. The ship also has a system of low-thrust engines for orientation, attached to the intermediate compartment (: переходной отсек, Perekhodnoi Otsek (PkhO)). Outside the service module are the sensors for the orientation system and the solar array, which is oriented towards the sun by rotating the ship.

text: A partial solar eclipse occurred on July 19, 1917. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: occurred on July 19, 1917. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: Facts may be understood as information that makes a true sentence true. Facts may also be understood as those things to which a true sentence refers. The statement "Jupiter is the largest planet in the solar system" is about the fact Jupiter is the largest planet in the solar system.

text: Reaching the Earth’s solar system, the Challenger’s crew are horrified to discover that Earth has vanished altogether, with the Moon now occupying Earth’s former orbit. Although the crew locate a large city on the Moon, they are unable to receive any answers to their communications and are unable to leave the ship to explore. This situation is changed when Darv and Astra enter an uncontrolled zone within the Challenger and locate a space shuttle previously unknown to the Angels. Using this, they visit the city and discover the Moon Sentinel, a computerized guardian and archive whom they can question. From the Sentinel they discover that while only one hundred and fifteen years of shipboard time has passed during the Challenger’s entire mission, due to the ship’s use of near-lightspeed travel and the effects of time dilation much more time has passed on Earth – over one million years. During this time, the Earth was removed from the solar system via a tremendous feat of interstellar engineering – desiring to protect the planet from the risk of increased solar activity, the inhabitants of Earth took the planet to orbit another, safer star. The Sentinel does not known which solar system Earth now occupies, but notes that if the Challenger’s crew genuinely are descendants of Earth people they will think as the people of Earth thought, and will find the Earth by following that pattern.

text: Uranus's internal heat appears markedly lower than that of the other giant planets; in astronomical terms, it has a low thermal flux. Why Uranus's internal temperature is so low is still not understood. Neptune, which is Uranus's near twin in size and composition, radiates 2.61 times as much energy into space as it receives from the Sun, but Uranus radiates hardly any excess heat at all. The total power radiated by Uranus in the far infrared (i.e. heat) part of the spectrum is  times the solar energy absorbed in its atmosphere. Uranus's heat flux is only , which is lower than the internal heat flux of Earth of about 0.075 W/m. The lowest temperature recorded in Uranus's tropopause is 49 K (−224 °C), making Uranus the coldest planet in the Solar System.

text: Uranus's

text: internal heat

text: appears markedly lower than that of the other giant planets; in astronomical terms, it has a low

text: thermal flux

text: . Why Uranus's internal temperature is so low is still not understood. Neptune, which is Uranus's near twin in size and composition, radiates 2.61 times as much energy into space as it receives from the Sun, but Uranus radiates hardly any excess heat at all. The total power radiated by Uranus in the

text: far infrared

text: (i.e. heat) part of the spectrum is  times the solar energy absorbed in its

text: atmosphere

text: . Uranus's heat flux is only , which is lower than the internal heat flux of Earth of about 0.075

text: W/m

text: . The lowest temperature recorded in Uranus's

text: tropopause

text: is 49 K (−224 °C), making Uranus the coldest planet in the Solar System.

text: The overview presentation on the Interplanetary Transport System given by Musk on 27 September 2016 included concept slides outlining missions to the Saturnian moon Enceladus, the Jovian moon Europa, Kuiper belt objects, a fuel depot on Pluto and even the uses to take payloads to the Oort Cloud."Musk said ... the system can open up the entire Solar System to people. If fuel depots based on this design were put on asteroids or other areas around the Solar System, people could go anywhere they wanted just by planet or moon hopping. 'The goal of SpaceX is to build the transport system ... Once that transport system is built, then there is a tremendous opportunity for anyone that wants to go to Mars to create something new or build a new planet."Outer planet trips would likely require propellant refills at Mars, and perhaps other locations in the outer Solar System.

text: The overview presentation on the Interplanetary Transport System given by Musk on 27 September 2016 included concept slides outlining missions to the

text: Saturnian

text: moon

text: Enceladus

text: , the

text: Jovian

text: moon

text: Europa

text: Kuiper belt

text: objects, a fuel depot on

text: Pluto

text: and even the uses to take payloads to the

text: Oort Cloud

text: ."Musk said ... the system can open up the entire Solar System to people. If fuel depots based on this design were put on asteroids or other areas around the Solar System, people could go anywhere they wanted just by planet or moon hopping. 'The goal of SpaceX is to build the transport system ... Once that transport system is built, then there is a tremendous opportunity for anyone that wants to go to Mars to create something new or build a new planet."Outer planet trips would likely require propellant refills at Mars, and perhaps other locations in the

text: outer Solar System

text: The large orbit was shaped like an imperfect ellipse (with the longest axis from front to back), and faced to the side and slightly forward. The infratemporal fenestra (opening) behind the eye was narrow and sloped backwards, and the supratemporal fenestra on the top back of the skull was very reduced in size (due to the thickening of the frontoparietal). The basicranium (back part) of the skull was shortened and distanced from the regions below the orbits and around the palate. The occiput sloped backwards and down, and the occipital condyle was deflected in the same direction. The lacrimal bone formed the lower front margin of the orbit, and its surface had rows of node-like ornamentation. The prefrontal and palpebral bones were fused and formed a thick ridge above the orbit. The relatively large jugal bone formed the lower margin of the orbit, extending far forwards and down towards the jaw joint. It was ornamented with ridges and nodes in a radiating arrangement.

text: The large orbit was shaped like an imperfect ellipse (with the longest axis from front to back), and faced to the side and slightly forward. The

text: infratemporal fenestra

text: (opening) behind the eye was narrow and sloped backwards, and the

text: supratemporal fenestra

text: on the top back of the skull was very reduced in size (due to the thickening of the frontoparietal). The basicranium (back part) of the skull was shortened and distanced from the regions below the orbits and around the

text: palate

text: . The occiput sloped backwards and down, and the occipital condyle was deflected in the same direction. The

text: lacrimal bone

text: formed the lower front margin of the orbit, and its surface had rows of node-like ornamentation. The

text: prefrontal

text: and

text: palpebral bone

text: s were fused and formed a thick ridge above the orbit. The relatively large

text: jugal bone

text: formed the lower margin of the orbit, extending far forwards and down towards the jaw joint. It was ornamented with ridges and nodes in a radiating arrangement.

text: Even small spaceships employ artificial gravity to shield their passengers from the effects of high acceleration, allowing them to cross a solar system in a matter of hours or days. The novels present a wide variety of ships, both military and commercial and even personal “yachts.”

text: Luke Skywalker's mission to find the living world of Zonama Sekot takes him and his team to the Chiss capital world of Csilla. There, they look into the planet's library for any information on the living planet, and amidst this, they foil a Chiss conspiracy against the Fel family. As a result of this, Luke and his team are given more time, and Jacen Solo manages to figure out that Zonama Sekot is probably hiding in the Unknown Regions disguised as a moon. The team finds evidence of this as they look into information on a solar system that inhabits the gas giant of Mobus.

text: "Grand Feast for Vultures" also contained an instrumental. This instrumental was composed by Pete during 2008 and contained an impressive amount of riffs, harmonies and time signatures. The big difference compared to the previous instrumental "Godbeater" was the introduction of NWOBHM influences and the Iron Maiden-esque main themes. The new instrumental was first entitled "Enceladus Rising" and this title even made it on the first promotional copies that was shipped off to the US press and radio stations. This error explains why many Americans still calls this track for "Enceladus Rising". Before the actual booklet was being pressed Pete changed his mind and wanted the track to be called "Horsehead Nebula". Pete explained: - "I wanted a title that both included something tremendously big and at the same time something very beautiful. Enceladus was one of the giants in Greek Mythology, but I reckon that he wasn't particularly beautiful. Enceladus is also the name given to one of the moons that goes in orbit around Saturn. That was more interesting and I started thinking about space... I digged up photos of various nebulas and in the back of my head I remembered a photos I had seen of this gigantic nebula with the shape of a horse head. I looked it up and the second I saw the photo I immediately knew I had the right title for the instrumental. The Horsehead Nebula is a dark nebula in the constellation Orion. It is located just to the south of the star Alnitak, which is farthest east on Orion's Belt, and is part of the much larger "Orion Molecular Cloud Complex". The latter is of course bigger, but to use that as a title would have linked our instrumental up to Metallica's "Orion" and it also sounds like something an industrial band would have called their album, so that option was quickly ditched".

text: "Grand Feast for Vultures" also contained an instrumental. This instrumental was composed by Pete during 2008 and contained an impressive amount of riffs, harmonies and time signatures. The big difference compared to the previous instrumental "Godbeater" was the introduction of

text: NWOBHM

text: influences and the

text: Iron Maiden

text: The practical implications of leveraging the latent capacity of water/ice via phase change thermal batteries or "fusion capable thermal batteries" are only understood when other industry contexts are applied.  For example, solar thermal collectors have well known capacities in the applications where that industry applies them.  Namely, into "hot water" applications.  The capacity of the solar collector array is dramatically different when it is applied to a phase change thermal battery system.  SunDrum Solar has experienced similar dramatic capacity increases in their systems because they are connecting them to the source side of heat pumps.

text: Research into extrasolar planets – planets located outside our solar system – is strong at Exeter. A team of international scientists led by Exeter University are exploring the atmospheric conditions of exoplanets using the Hubble Space Telescope. Other international astronomical facilities available to Exeter University to facilitate the detection of exoplanets include the VLT Survey Telescope, the Gemini Observatory and the Spitzer Space Telescope. The university has developed links with the Met Office, also based in Exeter, to build sophisticated climate prediction models.

text: Research into

text: extrasolar planets

text: – planets located outside our solar system – is strong at Exeter. A team of international scientists led by Exeter University are exploring the atmospheric conditions of

text: exoplanets

text: using the

text: Hubble Space Telescope

text: . Other international astronomical facilities available to Exeter University to facilitate the detection of exoplanets include the

text: VLT Survey Telescope

text: , the

text: Gemini Observatory

text: and the

text: Spitzer Space Telescope

text: . The university has developed links with the

text: Met Office

text: , also based in Exeter, to build sophisticated climate prediction models.

text: HR 5171A is the largest known yellow star. It has been calculated to be more than 1,300 times the diameter of the Sun.  If HR 5171A were to be put in the center of the Solar System, it would stretch to a distance of , between the orbits of Jupiter and Saturn. It has a volume approximately 2.274 billion times bigger than the Sun.

text: Georgescu points out that Earth is a closed system in the thermodynamic sense of the term: Earth exchanges energy, but not matter (practically) with the rest of the universe. Hence, mainly two sources of 'low entropy' are available to man, namely the stock of mineral resources in the crust of the Earth; and the flow of radiation, received from the Sun. Since the Sun will continue to shine for billions of years to come, the Earth's mineral stock is the scarcer one of these two main sources of low entropy. Whereas the stock of minerals may be extracted from the crust of the Earth at a rate of our own choosing (practically), the flow of solar radiation arrives at the surface of the Earth at a constant and fixed rate, beyond human control. This natural 'asymmetry' between man's access to the stock of minerals and the flow of solar energy accounts for the historical contrast between urban and rural life: The busy urban life, on the one hand, is associated with industry and the impatient extraction of minerals; the tranquil rural life, on the other hand, is associated with agriculture and the patient reception of the fixed flow of solar energy. Georgescu points out that this 'asymmetry' helps explaining the historical subjection of the countryside by the town since the dawn of civilisation, and he criticises Karl Marx for not taking this subjection properly into account in his theory of historical materialism.

text: Georgescu points out that Earth is a

text: closed system

text: in the thermodynamic sense of the term: Earth exchanges energy, but not matter (practically) with the rest of the universe. Hence, mainly two sources of 'low entropy' are available to man, namely the stock of mineral resources in the crust of the Earth; and the flow of radiation, received from the

text: Sun

text: . Since the Sun will continue to shine for billions of years to come, the Earth's mineral stock is the scarcer one of these two main sources of low entropy. Whereas the stock of minerals may be extracted from the

text: crust of the Earth

text: at a rate of our own choosing (practically), the flow of solar radiation arrives at the surface of the Earth at a constant and fixed rate, beyond human control. This natural 'asymmetry' between man's access to the stock of minerals and the flow of solar energy accounts for the historical contrast between urban and rural life: The busy urban life, on the one hand, is associated with industry and the impatient extraction of minerals; the tranquil rural life, on the other hand, is associated with agriculture and the patient reception of the fixed flow of solar energy. Georgescu points out that this 'asymmetry' helps explaining the historical subjection of the countryside by the town since the dawn of civilisation, and he criticises

text: Karl Marx

text: for not taking this subjection properly into account in his theory of

text: historical materialism

text: Solar power represented a very small part of electricity production in United Kingdom until 2011. The installed base has increased rapidly in recent years as a result of reductions in the cost of photovoltaic (PV) panels, and the introduction of a feed-in tariff (FIT) subsidy in April 2010. As of April 2016, there is a total installed capacity of 9.79 gigawatts (GW) of solar power. placing the United Kingdom in sixth place internationally in terms of total installed capacity, behind China, Germany, Japan USA and Italy, and having overtaken France and Spain in 2015. The 48 megawatts (MW) Southwick Estate solar farm, near Fareham, was the largest in the UK at the time of its completion in March 2015. In 2012, the government had said that 4 million homes across the UK will be powered by the sun within eight years, representing 22  (GW) of installed solar power capacity by 2020.

text: Solar power

text: represented a very small part of electricity production in

text: United Kingdom

text: until 2011. The installed base has increased rapidly in recent years as a result of reductions in the cost of

text: photovoltaic

text: (PV) panels, and the introduction of a

text: feed-in tariff

text: (FIT) subsidy in April 2010. As of April 2016, there is a total installed capacity of 9.79

text: gigawatts (GW)

text: of solar power. placing the United Kingdom in sixth place internationally in terms of total installed capacity, behind

text: China

text: Germany

text: Japan

text: USA

text: and

text: Italy,

text: and having overtaken

text: France

text: and

text: Spain

text: in 2015. The 48

text: megawatts

text: (MW) Southwick Estate solar farm, near Fareham, was the largest in the UK at the time of its completion in March 2015. In 2012, the government had said that 4 million homes across the UK will be powered by the sun within eight years, representing 22  (GW) of installed solar power capacity by 2020.

text: As science fiction became established in the early 20th century, destinations such as the Moon, Mars, Venus, and other bodies within the Solar System began to seem stale. Authors invoked a variety of mechanisms for superluminal travel (or generation starships) and placed their stories on worlds in planetary systems around other stars, an innovation that gave them the freedom to construct exotic fictional planets and themes. This tendency became predominant once the exploration of the Solar System was complete enough to conclusively demonstrate the unlikelihood of any highly developed form of extraterrestrial life here, aside from Humans on Earth.

text: As

text: science fiction

text: became established in the early 20th century, destinations such as

text: the Moon

text: Mars

text: Venus

text: , and other bodies within the

text: Solar System

text: began to seem stale. Authors invoked a variety of mechanisms for

text: superluminal

text: travel (or

text: generation starship

text: s) and placed their stories on worlds in

text: planetary system

text: s around other stars, an innovation that gave them the freedom to construct exotic

text: fictional planets

text: and themes. This tendency became predominant once the exploration of the Solar System was complete enough to conclusively demonstrate the unlikelihood of any highly developed form of

text: extraterrestrial life

text: here, aside from

text: Humans

text: on

text: Earth

text: A solar system of  20,000 solar panels, with a total area of 61,000 sq m, installed on the awnings of the station, has been described as "the world's largest stand alone integrated photovoltaic (BIPV) project". With the power output of 6.68 Megawatt, the system can produce 6.3 million kilowatt-hours (kwh) of electricity per year.

text: A solar system of  20,000

text: solar panel

text: s, with a total area of 61,000 sq m, installed on the awnings of the station, has been described as "the world's largest stand alone integrated photovoltaic (BIPV) project". With the power output of 6.68 Megawatt, the system can produce 6.3 million kilowatt-hours (kwh) of electricity per year.

text: Terrestrial planets have numerous similarities to plutoids (objects like Pluto), which also have a solid surface, but are primarily composed of icy materials. During the formation of the Solar System, there were probably many more (planetesimals), but they have all merged with or been destroyed by the four remaining worlds in the solar nebula.

text: Terrestrial planets have numerous similarities to

text: plutoid

text: s (objects like

text: Pluto

text: ), which also have a solid surface, but are primarily composed of icy materials. During the formation of the Solar System, there were probably many more (

text: planetesimal

text: s), but they have all merged with or been destroyed by the four remaining worlds in the

text: solar nebula

text: The Solar System and all of the visible stars are in different orbits about the core of the Milky Way galaxy.  Thus, their relative positions change over time, and for the nearer stars this movement can be measured.  As a star moves toward or away from us, its apparent brightness changes.  Sirius is currently the brightest star in Earth's night sky, but it has not always been so.  Canopus has persistently been the brightest star over the ages; other stars appear brighter only during relatively temporary periods, during which they are passing the Solar System at a much closer distance than Canopus.  The table below lists the brightest star in Earth's night sky at each period within the last or next 5 million years.

text: The

text: Solar System

text: and all of the visible stars are in different orbits about the core of the

text: Milky Way galaxy

text: .  Thus, their relative positions change over time, and for the nearer stars this movement can be measured.  As a

text: star

text: moves toward or away from us, its

text: apparent brightness

text: changes.

text: Sirius

text: is currently the brightest star in Earth's night sky, but it has not always been so.

text: Canopus

text: has persistently been the brightest star over the ages; other stars appear brighter only during relatively temporary periods, during which they are passing the Solar System at a much closer distance than Canopus.  The table below lists the brightest star in Earth's night sky at each period within the last or next 5 million years.

text: The visible disk of the Milky Way Galaxy is embedded in a much larger, roughly spherical halo of dark matter.  The dark matter density drops off with distance from the galactic center.  It is now believed that about 95% of the Galaxy is composed of dark matter, a type of matter that does not seem to interact with the rest of the Galaxy's matter and energy in any way except through gravity.  The luminous matter makes up approximately 9 x 10 solar masses. The dark matter halo is likely to include around  6 x 10 to 3 x 10 solar masses of dark matter.

text: The visible disk of the

text: Milky Way Galaxy

text: is embedded in a much larger, roughly spherical halo of dark matter.  The dark matter density drops off with distance from the galactic center.  It is now believed that about 95% of the Galaxy is composed of

text: dark matter

text: , a type of matter that does not seem to interact with the rest of the Galaxy's matter and energy in any way except through

text: gravity

text: .  The luminous matter makes up approximately 9 x 10

text: solar mass

text: es. The dark matter halo is likely to include around  6 x 10 to 3 x 10

text: solar mass

text: es of dark matter.

text: A partial solar eclipse occurred on August 9, 1953. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: occurred on August 9, 1953. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: At the bottom of the plaque is a schematic diagram of the Solar System. A small picture of the spacecraft is shown, and the trajectory shows its way past Jupiter and out of the Solar System. Both Pioneers 10 and 11 have identical plaques; however, after launch, Pioneer 11 was redirected towards Saturn and from there it exited the Solar System. In this regard the Pioneer 11 plaque is somewhat inaccurate.The Saturn flyby of Pioneer 11 would also greatly influence its future direction and destination as compared to Pioneer 10, but this fact is not depicted in the plaques.

text: At the bottom of the plaque is a schematic

text: diagram

text: of the Solar System. A small picture of the spacecraft is shown, and the

text: trajectory

text: shows its way past

text: Jupiter

text: and out of the Solar System. Both Pioneers 10 and 11 have identical plaques; however, after launch, Pioneer 11 was redirected towards

text: Saturn

text: and from there it exited the Solar System. In this regard the Pioneer 11 plaque is somewhat inaccurate.The Saturn flyby of Pioneer 11 would also greatly influence its future direction and destination as compared to Pioneer 10, but this fact is not depicted in the plaques.

text: The first civilization known to have a functional theory of the planets were the Babylonians, who lived in Mesopotamia in the first and second millennia BC. The oldest surviving planetary astronomical text is the Babylonian Venus tablet of Ammisaduqa, a 7th-century BC copy of a list of observations of the motions of the planet Venus, that probably dates as early as the second millennium BC. The MUL.APIN is a pair of cuneiform tablets dating from the 7th century BC that lays out the motions of the Sun, Moon, and planets over the course of the year. The Babylonian astrologers also laid the foundations of what would eventually become Western astrology. The Enuma anu enlil, written during the Neo-Assyrian period in the 7th century BC, comprises a list of omens and their relationships with various celestial phenomena including the motions of the planets. Venus, Mercury, and the outer planets Mars, Jupiter, and Saturn were all identified by Babylonian astronomers. These would remain the only known planets until the invention of the telescope in early modern times.

text: The first civilization known to have a functional theory of the planets were the

text: Babylonia

text: ns, who lived in

text: Mesopotamia

text: in the first and second millennia BC. The oldest surviving planetary astronomical text is the Babylonian

text: Venus tablet of Ammisaduqa

text: , a 7th-century BC copy of a list of observations of the motions of the planet Venus, that probably dates as early as the second millennium BC. The

text: MUL.APIN

text: is a pair of

text: cuneiform

text: tablets dating from the 7th century BC that lays out the motions of the Sun, Moon, and planets over the course of the year. The

text: Babylonian astrologers

text: also laid the foundations of what would eventually become

text: Western astrology

text: . The

text: Enuma anu enlil

text: , written during the

text: Neo-Assyrian

text: period in the 7th century BC, comprises a list of

text: omen

text: s and their relationships with various celestial phenomena including the motions of the planets.

text: Venus

text: Mercury

text: , and the outer planets

text: Mars

text: Jupiter

text: , and

text: Saturn

text: were all identified by

text: Babylonian astronomers

text: . These would remain the only known planets until the invention of the

text: telescope

text: in early modern times.

text: An extrasolar object (from extra, Latin for outside or beyond, and solar, Latin for the Sun) is an astronomical object that exists outside the Solar System. It is not applied to stars, or any other celestial object that is larger than a star or the Solar System, such as a galaxy. It is only used for objects (aside from stars) which are also found in the Solar System. The terms for extrasolar examples of Solar System bodies are:

text: An extrasolar object (from extra, Latin for outside or beyond, and solar, Latin for the

text: Sun

text: ) is an

text: astronomical object

text: that exists outside the

text: Solar System

text: . It is not applied to stars, or any other celestial object that is larger than a star or the Solar System, such as a

text: galaxy

text: . It is only used for objects (aside from stars) which are also found in the Solar System. The terms for extrasolar examples of Solar System bodies are:

text: Planetary science or, more rarely, planetology, is the scientific study of planets (including Earth), moons, and planetary systems (in particular those of the Solar System) and the processes that form them. It studies objects ranging in size from micrometeoroids to gas giants, aiming to determine their composition, dynamics, formation, interrelations and history. It is a strongly interdisciplinary field, originally growing from astronomy and earth science, but which now incorporates many disciplines, including planetary geology (together with geochemistry and geophysics), cosmochemistry, atmospheric science, oceanography, hydrology, theoretical planetary science, glaciology, and exoplanetology. Allied disciplines include space physics, when concerned with the effects of the Sun on the bodies of the Solar System, and astrobiology.

text: Planetary science or, more rarely, planetology, is the scientific study of

text: planet

text: s (including

text: Earth

text: moons

text: , and

text: planetary system

text: s (in particular those of the

text: Solar System

text: ) and the processes that form them. It studies objects ranging in size from

text: micrometeoroid

text: s to

text: gas giant

text: s, aiming to determine their composition, dynamics, formation, interrelations and history. It is a strongly

text: interdisciplinary

text: field, originally growing from

text: astronomy

text: and

text: earth science

text: , but which now incorporates many disciplines, including

text: planetary geology

text: (together with

text: geochemistry

text: and

text: geophysics

text: cosmochemistry

text: atmospheric science

text: oceanography

text: hydrology

text: theoretical planetary science

text: glaciology

text: , and

text: exoplanetology

text: . Allied disciplines include

text: space physics

text: , when concerned with the effects of the

text: Sun

text: on the bodies of the Solar System, and

text: astrobiology

text: A photovoltaic system, also solar PV power system, or PV system, is a power system designed to supply usable solar power by means of photovoltaics. It consists of an arrangement of several components, including solar panels to absorb and convert sunlight into electricity, a solar inverter to change the electric current from DC to AC, as well as mounting, cabling and other electrical accessories to set up a working system. It may also use a solar tracking system to improve the system's overall performance and include an integrated battery solution, as prices for storage devices are expected to decline. Strictly speaking, a solar array only encompasses the ensemble of solar panels, the visible part of the PV system, and does not include all the other hardware, often summarized as balance of system (BOS). Moreover, PV systems convert light directly into electricity and shouldn't be confused with other technologies, such as concentrated solar power or solar thermal, used for heating and cooling.

text: A photovoltaic system, also solar PV power system, or PV system, is a

text: power system

text: designed to supply usable

text: solar power

text: by means of

text: photovoltaics

text: . It consists of an arrangement of several components, including

text: solar panel

text: s to absorb and convert sunlight into electricity, a

text: solar inverter

text: to change the electric current from DC to AC, as well as

text: mounting

text: cabling

text: and other electrical accessories to set up a working system. It may also use a

text: solar tracking system

text: to improve the system's overall performance and include an

text: integrated battery solution

text: , as prices for storage devices are expected to decline. Strictly speaking, a solar array only encompasses the ensemble of solar panels, the visible part of the PV system, and does not include all the other hardware, often summarized as

text: balance of system

text: (BOS). Moreover, PV systems convert light directly into electricity and shouldn't be confused with other technologies, such as

text: concentrated solar power

text: or

text: solar thermal

text: , used for heating and cooling.

text: Once the magnetic anomaly has been installed, the swirls are formed because they are protected from the solar wind. The solar wind shielding model proposes that the swirls represent exposed silicate materials whose albedos have been selectively preserved over time from the effects of space weathering via deflection of solar wind ion bombardment. According to this model, optical maturation of exposed silicate surfaces in the inner solar system is at least partly a function of the solar wind ion bombardment. This model suggests that swirl formation is a continuing process, which began after placement of the magnetic anomaly.

text: Once the magnetic anomaly has been installed, the swirls are formed because they are protected from the

text: solar wind

text: . The solar wind shielding model proposes that the swirls represent exposed silicate materials whose albedos have been selectively preserved over time from the effects of space weathering via deflection of solar wind ion bombardment. According to this model, optical maturation of exposed silicate surfaces in the inner solar system is at least partly a function of the solar wind ion bombardment. This model suggests that swirl formation is a continuing process, which began after placement of the magnetic anomaly.

text: The Northern Hemisphere of Earth is the half that is north of the equator. For other planets in the Solar System, north is defined as being in the same celestial hemisphere relative to the invariable plane of the solar system as Earth's North pole.

text: The Northern Hemisphere of

text: Earth

text: is the half that is

text: north

text: of the

text: equator

text: . For other planets in the

text: Solar System

text: , north is defined as being in the same celestial hemisphere relative to the

text: invariable plane

text: of the solar system as Earth's North pole.

text: All the solar planets more distant from the Sun than Earth are similar to Earth in that, since they experience many rotations per revolution around the Sun, there is only a small difference between the length of the sidereal day and that of the solar day—the ratio of the former to the latter never being less than Earth's ratio of 0.997. But the situation is quite different for Mercury and Venus. Mercury's sidereal day is about two-thirds of its orbital period, so by the prograde formula its solar day lasts for two revolutions around the Sun— three times as long as its sidereal day. Venus rotates retrograde with a sidereal day lasting about 243.0 Earth days, or about 1.08 times its orbital period of 224.7 Earth days; hence by the retrograde formula its solar day is about 116.8 Earth days, and it has about 1.9 solar days per orbital period.

text: All the solar planets more distant from the Sun than Earth are similar to Earth in that, since they experience many rotations per revolution around the Sun, there is only a small difference between the length of the sidereal day and that of the solar day—the ratio of the former to the latter never being less than Earth's ratio of 0.997. But the situation is quite different for

text: Mercury

text: and Venus. Mercury's sidereal day is about two-thirds of its orbital period, so by the prograde formula its solar day lasts for two revolutions around the Sun— three times as long as its sidereal day. Venus rotates retrograde with a sidereal day lasting about 243.0 Earth days, or about 1.08 times its orbital period of 224.7 Earth days; hence by the retrograde formula its solar day is about 116.8 Earth days, and it has about 1.9 solar days per orbital period.

text: Compared to all the meteorites found to date, CI chondrites possess the strongest similarity to the elemental distribution within the original solar nebula. For this reason they are also called primitive meteorites. Except for the volatile elements carbon, hydrogen, oxygen and nitrogen as well as the noble gases, which are deficient in the CI chondrites, the elemental ratios are nearly identical. Lithium is another exception, it is enriched in the meteorites (in the sun lithium is involved during nucleosynthesis and therefore diminished).

text: Compared to all the meteorites found to date, CI chondrites possess the strongest similarity to the elemental distribution within the original

text: solar nebula

text: . For this reason they are also called primitive meteorites. Except for the volatile elements

text: carbon

text: hydrogen

text: oxygen

text: and

text: nitrogen

text: as well as the

text: noble gas

text: es, which are deficient in the CI chondrites, the elemental ratios are nearly identical.

text: Lithium

text: is another exception, it is enriched in the meteorites (in the sun lithium is involved during

text: nucleosynthesis

text: and therefore diminished).

text: Astronomers use stellar flux and the inverse-square law to extrapolate circumstellar habitable zone models created for the Solar System to other stars. For example, although the Solar System has a circumstellar habitable zone centered at 1.34 AU from the Sun, a star with 0.25 times the luminosity of the Sun would have a habitable zone centered at

text: Astronomers use stellar flux and the

text: inverse-square law

text: to extrapolate circumstellar habitable zone models created for the Solar System to other stars. For example, although the Solar System has a circumstellar habitable zone centered at 1.34 AU from the Sun, a star with 0.25 times the luminosity of the Sun would have a habitable zone centered at

text: Neptune's orbit has a profound impact on the region directly beyond it, known as the Kuiper belt. The Kuiper belt is a ring of small icy worlds, similar to the asteroid belt but far larger, extending from Neptune's orbit at 30 AU out to about 55 AU from the Sun. Much in the same way that Jupiter's gravity dominates the asteroid belt, shaping its structure, so Neptune's gravity dominates the Kuiper belt. Over the age of the Solar System, certain regions of the Kuiper belt became destabilised by Neptune's gravity, creating gaps in the Kuiper belt's structure. The region between 40 and 42 AU is an example.

text: Neptune's orbit has a profound impact on the region directly beyond it, known as the

text: Kuiper belt

text: . The Kuiper belt is a ring of small icy worlds, similar to the

text: asteroid belt

text: but far larger, extending from Neptune's orbit at 30 AU out to about 55 AU from the Sun. Much in the same way that Jupiter's gravity dominates the

text: asteroid belt

text: , shaping its structure, so Neptune's gravity dominates the Kuiper belt. Over the age of the Solar System, certain regions of the Kuiper belt became destabilised by Neptune's gravity, creating gaps in the Kuiper belt's structure. The region between 40 and 42 AU is an example.

text: A partial solar eclipse occurred on June 1, 2011. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.This eclipse is the second of four partial solar eclipses in 2011, with the others occurring on January 4, 2011, July 1, 2011, and November 25, 2011.

text: A

text: partial solar eclipse

text: occurred on June 1, 2011. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: , thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.This eclipse is the second of four partial solar eclipses in 2011, with the others occurring on

text: January 4, 2011

text: July 1, 2011

text: , and

text: November 25, 2011

text: RW Cygni is a red supergiant of spectral type M2-4Ia-Iab with an effective temperature of 3,920 K. It is a large supergiant, with a radius between 680 - 980 solar radii. Using the more conservative figure, so if it is placed in the center of Solar System, it would be extend past the orbit of Mars. However, it is surpassed in size by other stars like KY Cygni, NML Cygni or BC Cygni, the latter also in the constellation Cygnus. With a mass of about 20 solar masses, it is estimated that their stellar mass loss in powder form is 3.2 × 10-9 solar masses per year.

text: RW Cygni is a red supergiant of spectral type M2-4Ia-Iab with an effective temperature of 3,920

text: K

text: . It is a large supergiant, with a radius between 680 - 980

text: solar radii

text: . Using the more conservative figure, so if it is placed in the center of

text: Solar System

text: , it would be extend past the orbit of

text: Mars

text: . However, it is surpassed in size by other stars like

text: KY Cygni

text: NML Cygni

text: or

text: BC Cygni

text: , the latter also in the constellation Cygnus. With a mass of about 20

text: solar mass

text: es, it is estimated that their stellar mass loss in powder form is 3.2 × 10-9 solar masses per year.

text: Space Travel is a spaceflight simulation video game, presented in a two-dimensional top-down view, with monochrome graphics consisting of white lines on a black background. In it, the player controls a spaceship as it flies through a representation of the solar system. The game has no specific objectives, other than to attempt to land on the various planets and moons of the system. The planets and most of the moons in the solar system are represented to scale both in size and distance from each other, though the orbits are simplified to be circles. To land on a body, the player's ship must cross the line representing the surface while moving at a low enough speed. The player is able to control the ship to go forwards and backwards and turn. The ship moves at a constant level of acceleration relative to the scale of the screen, which the player can control; scaling the screen up high enough allows the player to travel across the solar system in seconds, though they risk overshooting their target and becoming unable to find the solar system again, and scaling down allows the player to be moving slowly enough to land. The ship is always in the center of the screen, facing the top; turning the ship right or left therefore rotates the solar system around the ship instead.

text: Space Travel is a spaceflight

text: simulation video game

text: , presented in a two-dimensional top-down view, with

text: monochrome

text: graphics consisting of white lines on a black background. In it, the player controls a spaceship as it flies through a representation of the

text: solar system

text: . The game has no specific objectives, other than to attempt to land on the various planets and moons of the system. The planets and most of the moons in the solar system are represented to scale both in size and distance from each other, though the orbits are simplified to be circles. To land on a body, the player's ship must cross the line representing the surface while moving at a low enough speed. The player is able to control the ship to go forwards and backwards and turn. The ship moves at a constant level of acceleration relative to the scale of the screen, which the player can control; scaling the screen up high enough allows the player to travel across the solar system in seconds, though they risk overshooting their target and becoming unable to find the solar system again, and scaling down allows the player to be moving slowly enough to land. The ship is always in the center of the screen, facing the top; turning the ship right or left therefore rotates the solar system around the ship instead.

text: There are eight planets in the Solar System, which are in increasing distance from the Sun:

text: There are eight planets in the

text: Solar System

text: , which are in increasing distance from the

text: Sun

text: Algol is about 92.8 light years from the Sun, but about 7.3 million years ago it passed within 9.8 light years of the Solar System and its apparent magnitude was about −2.5, which is considerably brighter than the star Sirius is today. Because the total mass of the Algol system is about 5.8 solar masses, at the closest approach this might have given enough gravity to perturb the Oort cloud of the Solar System somewhat and hence increase the number of comets entering the inner Solar System. However, the actual increase in net cometary collisions is thought to have been quite small.

text: Algol is about 92.8

text: light year

text: s from the Sun, but about 7.3 million years ago it passed within 9.8 light years of the

text: Solar System

text: and its

text: apparent magnitude

text: was about −2.5, which is considerably brighter than the star

text: Sirius

text: is today. Because the total mass of the Algol system is about 5.8 solar masses, at the closest approach this might have given enough

text: gravity

text: to

text: perturb

text: the

text: Oort cloud

text: of the Solar System somewhat and hence increase the number of

text: comet

text: s entering the inner Solar System. However, the actual increase in net cometary collisions is thought to have been quite small.

text: This formula was powerful enough to stand as the basis for all subsequent descriptions of motion within the solar system until the 20th century. During that time, sophisticated methods of perturbation analysis were invented to calculate the deviations of orbits due to the influence of multiple bodies on a planet, moon, comet, or asteroid. The formalism was exact enough to allow mathematicians to predict the existence of the planet Neptune before it was observed.

text: This formula was powerful enough to stand as the basis for all subsequent descriptions of motion within the solar system until the 20th century. During that time, sophisticated methods of

text: perturbation analysis

text: were invented to calculate the deviations of

text: orbit

text: s due to the influence of multiple bodies on a

text: planet

text: moon

text: comet

text: , or

text: asteroid

text: . The formalism was exact enough to allow mathematicians to predict the existence of the planet

text: Neptune

text: before it was observed.

text: Martin Beech from the University of Western Ontario (London, Ontario, Canada) referred to the various hypotheses and experimental results that support non-existence of antimatter in the Universe. He argued that any antimatter  comets and meteors that exist must be (at least) extrasolar in origin because the nebular hypothesis for the formation of the solar system precludes their being solar. Any antimatter in a pre-formation nebula or planetary accretion disc has a comparatively short lifetime, astronomically speaking, before annihilation with the terrene matter that it is mixed with. This lifetime is measured in the hundreds of years, and so any solar antimatter present at the time that the system was formed will have long since been annihilated. Any antimatter comets and meteors must therefore come from another, antimatter, solar system, and be extrasolar. Furthermore, not only must antimatter meteors be extrasolar in origin, they must have been recently (i.e. within the past 10 ~ 10 years) captured by the Solar System. Most meteoroids are broken down to sizes of 10 g within that timeframe, because of meteoroid-upon-meteoroid collisions. Thus any antimatter meteor must be either extrasolar in origin itself, or broken off from an antimatter comet that is extrasolar in origin. The former are unlikely to exist from observational evidence. Any extrasolar meteoroid would have a hyperbolic orbit, but less than 1% of the observed meteoroids have such, and the process of perturbation of ordinary (terrene) solar objects, by planetary encounters, into hyperbolic trajectories accounts for all of those. Beech concluded that a continued null result, however, does not constitute a proof ('Absence of evidence is not evidence of absence', M. Rees) and a single positive detection negates the arguments presented.

text: Martin Beech from the University of Western Ontario (London, Ontario, Canada) referred to the various hypotheses and experimental results that support non-existence of antimatter in the Universe. He argued that any antimatter  comets and meteors that exist must be (at least) extrasolar in origin because the

text: nebular hypothesis

text: for the

text: formation of the solar system

text: precludes their being solar. Any antimatter in a pre-formation nebula or planetary

text: accretion disc

text: has a comparatively short lifetime, astronomically speaking, before annihilation with the terrene matter that it is mixed with. This lifetime is measured in the hundreds of years, and so any solar antimatter present at the time that the system was formed will have long since been annihilated. Any antimatter comets and meteors must therefore come from another, antimatter, solar system, and be extrasolar. Furthermore, not only must antimatter meteors be extrasolar in origin, they must have been recently (i.e. within the past 10 ~ 10 years) captured by the Solar System. Most meteoroids are broken down to sizes of 10 g within that timeframe, because of meteoroid-upon-meteoroid collisions. Thus any antimatter meteor must be either extrasolar in origin itself, or broken off from an antimatter comet that is extrasolar in origin. The former are unlikely to exist from observational evidence. Any extrasolar meteoroid would have a

text: hyperbolic orbit

text: , but less than 1% of the observed meteoroids have such, and the process of perturbation of ordinary (terrene) solar objects, by planetary encounters, into hyperbolic trajectories accounts for all of those. Beech concluded that a continued null result, however, does not constitute a proof ('Absence of evidence is not evidence of absence', M. Rees) and a single positive detection negates the arguments presented.

text: Humans began on Earth. During the age of space exploration, the Solar system was colonized, solving the Earth's overpopulation and resource problems. However, FTL travel was still beyond human science, so the race was confined within the boundaries of the system. After several generations, those living in colonies stopped thinking of themselves as Earthlings and saw the colonies as their home. Tensions arose as the Earth Empire attempted to force their rule on Mars (completely terraformed) and the other colonies. In response, Mars rebelled, and the other colonies joined it. When Mars diplomat's shuttle was ambushed and destroyed on the way to the Lunar summit, each side blamed the other, eventually resulting in a long and bloody war across the entire system. The war ended with the crushing defeat of one of the sides (player's choice which one) and formed the Legions of Iron. Coincidentally, a wormhole was discovered at the edge of the Solar system at the same time. Two more were found shortly after. Thus began the age of interstellar exploration and expansion for the new empire.

text: Humans began on Earth. During the age of space exploration, the Solar system was colonized, solving the Earth's overpopulation and resource problems. However,

text: FTL

text: travel was still beyond human science, so the race was confined within the boundaries of the system. After several generations, those living in colonies stopped thinking of themselves as Earthlings and saw the colonies as their home. Tensions arose as the Earth Empire attempted to force their rule on Mars (completely terraformed) and the other colonies. In response, Mars rebelled, and the other colonies joined it. When Mars diplomat's shuttle was ambushed and destroyed on the way to the Lunar summit, each side blamed the other, eventually resulting in a long and bloody war across the entire system. The war ended with the crushing defeat of one of the sides (player's choice which one) and formed the Legions of Iron. Coincidentally, a wormhole was discovered at the edge of the Solar system at the same time. Two more were found shortly after. Thus began the age of interstellar exploration and expansion for the new empire.

text: While the minimum mass of the object is that of a brown dwarf, this depends on the inclination of the orbit relative to observations from the Solar System. Because of this, if the orbit of HD 4747 B is inclined by less than 40°, the mass of the object will be above the hydrogen burning limit at approximately  that marks the transition between stars and brown dwarfs. Long-term astrometry or direct detection could solve this problem, but no attempt to do so has yet appeared in literature.

text: A partial solar eclipse will occur on July 22, 2047. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: will occur on July 22, 2047. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: One of Kuhn’s most famous examples was of the revolution led first by Copernicus and later by Galileo to overthrow the Earth-centered view of the solar system and replace it with our current sun-centered one. But in other instances, new paradigms leave part of the old paradigms intact, such as Einstein’s theory of relativity, which left Newton’s theory of gravity on Earth intact even as it revolutionized our understanding of mass and energy in the rest of the universe.

text: <blockquote>One of Kuhn’s most famous examples was of the revolution led first by

text: Copernicus

text: and later by

text: Galileo

text: to overthrow the Earth-centered view of the solar system and replace it with our current sun-centered one. But in other instances, new paradigms leave part of the old paradigms intact, such as Einstein’s

text: theory of relativity

text: , which left Newton’s

text: theory of gravity

text: on Earth intact even as it revolutionized our understanding of mass and energy in the rest of the universe.	<br>

text: Kenyon has developed numerical models for planet formation and applied these calculations to the formation of debris disks and Kuiper belt objects. Kenyon and Ben Bromley have suggested that the dwarf planet Sedna in the outer solar system might be an exosolar object captured during a close encounter with another planetary system when the Sun was only a few million years old. This capture mechanism might also explain other unusual [dwarf planets] such as

text: Kenyon has developed numerical models for planet formation and applied these calculations to the formation of

text: debris disks

text: and

text: Kuiper belt objects

text: . Kenyon and Ben Bromley have suggested that the

text: dwarf planet

text: Sedna

text: in the

text: outer solar system

text: might be an exosolar object captured during a close encounter with another planetary system when the Sun was only a few million years old. This capture mechanism might also explain other unusual [dwarf planets] such as

text: Solar energy, radiant light and heat from the sun, has been harnessed by humans since ancient times using a range of ever-evolving technologies. Solar energy technologies include solar heating, solar photovoltaics, concentrated solar power and solar architecture, which can make considerable contributions to solving some of the most urgent problems the world now faces. The International Energy Agency projected that solar power could provide "a third of the global final energy demand after 2060, while CO emissions would be reduced to very low levels." Solar technologies are broadly characterized as either passive solar or active solar depending on the way they capture, convert and distribute solar energy. Active solar techniques include the use of photovoltaic systems and solar thermal collectors to harness the energy. Passive solar techniques include orienting a building to the Sun, selecting materials with favorable thermal mass or light dispersing properties, and designing spaces that naturally circulate air.

text: Solar energy, radiant

text: light

text: and

text: heat

text: from the

text: sun

text: , has been harnessed by humans since

text: ancient times

text: using a range of ever-evolving technologies. Solar energy technologies include

text: solar heating

text: solar photovoltaics

text: concentrated solar power

text: and

text: solar architecture

text: , which can make considerable contributions to solving some of the most urgent problems the world now faces. The

text: International Energy Agency

text: projected that solar power could provide "a third of the global final energy demand after 2060, while CO emissions would be reduced to very low levels." Solar technologies are broadly characterized as either

text: passive solar

text: or

text: active solar

text: depending on the way they capture, convert and distribute solar energy. Active solar techniques include the use of

text: photovoltaic system

text: s and

text: solar thermal collector

text: s to harness the energy. Passive solar techniques include orienting a building to the Sun, selecting materials with favorable

text: thermal mass

text: or light dispersing properties, and designing spaces that

text: naturally circulate air

text: The Earth is constantly immersed in the solar wind, a rarefied flow of hot plasma (a gas of free electrons and positive ions) emitted by the Sun in all directions, a result of the two-million-degree temperature of the Sun's outermost layer, the corona. The solar wind reaches Earth with a velocity typically around 400 km/s, a density of around 5 ions/cm and a magnetic field intensity of around 2–5 nT (for comparison, Earth's surface field is typically 30,000–50,000 nT). During magnetic storms, in particular, flows can be several times faster; the interplanetary magnetic field (IMF) may also be much stronger. Joan Feynman deduced in the 1970s that the long-term averages of solar wind speed correlated with geomagnetic activity.  Her work resulted from data collected by the Explorer 33 spacecraft.The solar wind and magnetosphere consist of plasma (ionized gas), which conducts electricity. It is well known (since Michael Faraday's work around 1830) that when an electrical conductor is placed within a magnetic field while relative motion occurs in a direction that the conductor cuts across (or is cut by), rather than along, the lines of the magnetic field, an electric current is induced within the conductor. The strength of the current depends on a) the rate of relative motion, b) the strength of the magnetic field, c) the number of conductors ganged together and d) the distance between the conductor and the magnetic field, while the direction of flow is dependent upon the direction of relative motion. Dynamos make use of this basic process ("the dynamo effect"), any and all conductors, solid or otherwise are so affected, including plasmas and other fluids.The IMF originates on the Sun, linked to the sunspots, and its field lines (lines of force) are dragged out by the solar wind. That alone would tend to line them up in the Sun-Earth direction, but the rotation of the Sun angles them at Earth by about 45 degrees forming a spiral in the ecliptic plane), known as the Parker spiral. The field lines passing Earth are therefore usually linked to those near the western edge ("limb") of the visible Sun at any time.The solar wind and the magnetosphere, being two electrically conducting fluids in relative motion, should be able in principle to generate electric currents by dynamo action and impart energy from the flow of the solar wind. However, this process is hampered by the fact that plasmas conduct readily along magnetic field lines, but less readily perpendicular to them. Energy is more effectively transferred by temporary magnetic connection between the field lines of the solar wind and those of the magnetosphere. Unsurprisingly this process is known as magnetic reconnection. As already mentioned, it happens most readily when the interplanetary field is directed southward, in a similar direction to the geomagnetic field in the inner regions of both the north magnetic pole and south magnetic pole.

text: The Earth is constantly immersed in the

text: solar wind

text: , a rarefied flow of hot plasma (a gas of free electrons and positive ions) emitted by the Sun in all directions, a result of the two-million-degree temperature of the Sun's outermost layer, the

text: corona

text: . The solar wind reaches Earth with a velocity typically around 400 km/s, a density of around 5 ions/cm and a magnetic field intensity of around 2–5 nT (for comparison, Earth's surface field is typically 30,000–50,000 nT). During

text: magnetic storms

text: , in particular, flows can be several times faster; the

text: interplanetary magnetic field

text: (IMF) may also be much stronger. Joan Feynman deduced in the 1970s that the long-term averages of solar wind speed correlated with geomagnetic activity.  Her work resulted from data collected by the

text: Explorer 33

text: spacecraft.The solar wind and magnetosphere consist of

text: plasma

text: (ionized gas), which conducts electricity. It is well known (since

text: Michael Faraday

text: 's work around 1830) that when an electrical conductor is placed within a magnetic field while relative motion occurs in a direction that the conductor cuts across (or is cut by), rather than along, the lines of the magnetic field, an electric current is induced within the conductor. The strength of the current depends on a) the rate of relative motion, b) the strength of the magnetic field, c) the number of conductors ganged together and d) the distance between the conductor and the magnetic field, while the direction of flow is dependent upon the direction of relative motion.

text: Dynamo

text: s make use of this basic process ("the

text: dynamo effect

text: "), any and all conductors, solid or otherwise are so affected, including plasmas and other fluids.The IMF originates on the Sun, linked to the

text: sunspot

text: s, and its

text: field lines (lines of force)

text: are dragged out by the solar wind. That alone would tend to line them up in the Sun-Earth direction, but the rotation of the Sun angles them at Earth by about 45 degrees forming a spiral in the ecliptic plane), known as the

text: Parker spiral

text: . The field lines passing Earth are therefore usually linked to those near the western edge ("limb") of the visible Sun at any time.The solar wind and the magnetosphere, being two electrically conducting fluids in relative motion, should be able in principle to generate electric currents by dynamo action and impart energy from the flow of the solar wind. However, this process is hampered by the fact that plasmas conduct readily along magnetic field lines, but less readily perpendicular to them. Energy is more effectively transferred by temporary magnetic connection between the field lines of the solar wind and those of the magnetosphere. Unsurprisingly this process is known as

text: magnetic reconnection

text: . As already mentioned, it happens most readily when the interplanetary field is directed southward, in a similar direction to the geomagnetic field in the inner regions of both the

text: north magnetic pole

text: and

text: south magnetic pole

text: Frost & Sullivan, a global management consultancy, gave the Best Practices Award 2014 in the category of Philippines Solar Photovoltaic System Integrator of the Year, to San Carlos Solar Energy, Inc., the solar portfolio company of ThomasLloyd Cleantech Infrastructure Fund.

text: Solar Probe Plus or Solar Probe+, previously NASA Solar Probe, is a planned robotic spacecraft to probe the outer corona of the Sun. It will approach to within 8.5 solar radii (5.9 million kilometers or 3.67 million miles) to the 'surface' (photosphere) of the Sun. The project was announced as a new mission start in the fiscal 2009 budget year. On May 1, 2008 Johns Hopkins University Applied Physics Laboratory announced it will design and build the spacecraft, on a schedule to launch it in 2015. The launch date has since been pushed back to 2018, with the Delta IV Heavy as the launch vehicle.<ref name='Delta 4'/>

text: Solar Probe Plus or Solar Probe+, previously NASA Solar Probe, is a planned robotic spacecraft to probe the outer

text: corona

text: of the

text: Sun

text: . It will approach to within 8.5

text: solar radii

text: (5.9 million kilometers or 3.67 million miles) to the 'surface' (

text: photosphere

text: ) of the Sun. The project was announced as a new mission start in the fiscal 2009 budget year. On May 1, 2008

text: Johns Hopkins University

text: Applied Physics Laboratory

text: announced it will design and build the spacecraft, on a schedule to launch it in 2015. The launch date has since been pushed back to 2018, with the

text: Delta IV Heavy

text: as the launch vehicle.<ref name='Delta 4'/>

text: The size l of the orbit is called the length of the corresponding cycle; when l = 1, the single element in the orbit is called a fixed point of the permutation.

text: The size l of the orbit is called the length of the corresponding cycle; when l = 1, the single element in the orbit is called a

text: fixed point

text: of the permutation.

text: The Sun is near the inner rim of the Orion Arm, within the Local Fluff of the Local Bubble, and in the Gould Belt, at a distance of  from the Galactic Center. The Sun is currently  from the central plane of the Galactic disk. The distance between the local arm and the next arm out, the Perseus Arm, is about . The Sun, and thus the Solar System, is located in the Milky Way's galactic habitable zone.

text: The

text: Sun

text: is near the inner rim of the

text: Orion Arm

text: , within the

text: Local Fluff

text: of the

text: Local Bubble

text: , and in the

text: Gould Belt

text: , at a distance of  from the Galactic Center. The Sun is currently  from the central plane of the Galactic disk. The distance between the local arm and the next arm out, the

text: Perseus Arm

text: , is about . The Sun, and thus the Solar System, is located in the Milky Way's

text: galactic habitable zone

text: Sungenis believes that the Catholic Church condemned heliocentrism as a formal heresy in the 17th century and that the observable universe would fit a geocentric model, with the Earth immobile at the barycenter and everything else revolving around it. He claims that observational evidence from the 2001 Wilkinson Microwave Anisotropy Probe showed the Earth's central position and experiments performed from Dominique Arago in 1818 to Michelson-Morely in 1887 showed that the Earth was not moving. His views are often confused with the Ptolemaic system, where Earth is at the center of the solar system, with the sun and all planets revolving around it. Instead, they more closely resemble the Tychonic system. Catholic writer David Palm has criticized Sungenis' work, particularly as it relates to the teaching of the Catholic Church, stating that Sungenis is misrepresenting it so as to falsely give the impression that geocentrism is "an official church teaching that had been covered up for centuries.".

text: Sungenis believes that the Catholic Church condemned heliocentrism as a formal heresy in the 17th century and that the observable universe would fit a geocentric model, with the Earth immobile at the

text: barycenter

text: and everything else revolving around it. He claims that observational evidence from the 2001

text: Wilkinson Microwave Anisotropy Probe

text: showed the Earth's central position and experiments performed from

text: Dominique Arago

text: in 1818 to

text: Michelson-Morely

text: in 1887 showed that the Earth was not moving. His views are often confused with the

text: Ptolemaic system

text: , where Earth is at the center of the solar system, with the sun and all planets revolving around it. Instead, they more closely resemble the

text: Tychonic system

text: . Catholic writer David Palm has criticized Sungenis' work, particularly as it relates to the teaching of the Catholic Church, stating that Sungenis is misrepresenting it so as to falsely give the impression that geocentrism is "an official church teaching that had been covered up for centuries.".

text: Jor-El was first referred to indirectly in Action Comics #1 in 1938, which only mentioned a scientist who sends his son to Earth. He made his first full-fledged appearance in the Superman newspaper comic strip in 1939, where his name was spelled as "Jor-L". His name first appeared as being spelled "Jor-el" in the Superman novel The Adventures of Superman (1942) written by George Lowther. Later comic books capitalized the "E" in "El." Jor-El's first appearance in an actual comic book was in More Fun Comics #101. After the introduction of DC Comics' multiverse system in the 1960s, it was established that the version of Superman's father during the Golden Age of Comic Books was named "Jor-L", and he lived on the Krypton of the Earth-Two universe. However, "Jor-El" was the father of the Silver Age version of Superman, and he lived on the Krypton of the Earth-One universe.

text: Jor-El was first referred to indirectly in

text: Action Comics

text: #1 in 1938, which only mentioned a scientist who sends his son to Earth. He made his first full-fledged appearance in

text: the Superman newspaper comic strip

text: in 1939, where his name was spelled as "Jor-L". His name first appeared as being spelled "Jor-el" in the Superman novel The Adventures of Superman (1942) written by

text: George Lowther

text: . Later comic books capitalized the "E" in "El." Jor-El's first appearance in an actual comic book was in

text: More Fun Comics

text: #101. After the introduction of

text: DC Comics

text: multiverse

text: system in the 1960s, it was established that the version of Superman's father during the

text: Golden Age of Comic Books

text: was named "Jor-L", and he lived on the Krypton of the

text: Earth-Two

text: universe. However, "Jor-El" was the father of the

text: Silver Age

text: version of Superman, and he lived on the Krypton of the

text: Earth-One

text: universe

text: Hypothetical types of extrasolar planet include:

text: Several groups of carbonaceous chondrites, notably the CM and CI groups, contain high percentages (3% to 22%) of water, as well as organic compounds. They are composed mainly of silicates, oxides and sulfides, with the minerals olivine and serpentine being characteristic. The presence of volatile organic chemicals and water indicates that they have not undergone significant heating (>200 °C) since they were formed, and their compositions are considered to be close to that of the solar nebula from which the Solar System condensed. Other groups of C chondrites, e.g., CO, CV, and CK chondrites, are relatively poor in volatile compounds, and some of these have experienced significant heating on their parent asteroids.

text: Several groups of carbonaceous chondrites, notably the

text: CM

text: and

text: CI

text: groups, contain high percentages (3% to 22%) of

text: water

text: , as well as

text: organic compound

text: s. They are composed mainly of

text: silicate

text: s,

text: oxide

text: s and

text: sulfide

text: s, with the minerals

text: olivine

text: and

text: serpentine

text: being characteristic. The presence of volatile organic chemicals and water indicates that they have not undergone significant heating (>200 °C) since they were formed, and their compositions are considered to be close to that of the

text: solar nebula

text: from which the

text: Solar System

text: condensed. Other groups of C chondrites, e.g., CO, CV, and CK chondrites, are relatively poor in volatile compounds, and some of these have experienced significant heating on their parent asteroids.

text: Mercury is one of four terrestrial planets in the Solar System, and is a rocky body like Earth. It is the smallest planet in the Solar System, with an equatorial radius of . Mercury is also smaller—albeit more massive—than the largest natural satellites in the Solar System, Ganymede and Titan. Mercury consists of approximately 70% metallic and 30% silicate material. Mercury's density is the second highest in the Solar System at 5.427 g/cm, only slightly less than Earth's density of 5.515 g/cm. If the effect of gravitational compression were to be factored out from both planets, the materials of which Mercury is made would be denser than those of Earth, with an uncompressed density of 5.3 g/cm versus Earth's 4.4 g/cm.

text: Mercury is one of four

text: terrestrial planet

text: s in the

text: Solar System

text: , and is a rocky body like Earth. It is the smallest planet in the Solar System, with an

text: equator

text: ial

text: radius

text: of . Mercury is also

text: smaller

text: —albeit more massive—than the

text: largest

text: natural satellite

text: s in the Solar System,

text: Ganymede

text: and

text: Titan

text: . Mercury consists of approximately 70% metallic and 30%

text: silicate

text: material. Mercury's density is the second highest in the Solar System at 5.427 g/cm, only slightly less than Earth's density of 5.515 g/cm. If the effect of

text: gravitational compression

text: were to be factored out from both planets, the materials of which Mercury is made would be denser than those of Earth, with an uncompressed density of 5.3 g/cm versus Earth's 4.4 g/cm.

text: Gradually, the hydrogen burning in the shell around the solar core will increase the mass of the core until it reaches about 45% of the present solar mass. At this point the density and temperature will become so high that the fusion of helium into carbon will begin, leading to a helium flash; the Sun will shrink from around 250 to 11 times its present (main-sequence) radius. Consequently, its luminosity will decrease from around 3,000 to 54 times its current level, and its surface temperature will increase to about 4770 K. The Sun will become a horizontal giant, burning helium in its core in a stable fashion much like it burns hydrogen today. The helium-fusing stage will last only 100 million years. Eventually, it will have to again resort to the reserves of hydrogen and helium in its outer layers and will expand a second time, turning into what is known as an asymptotic giant. Here the luminosity of the Sun will increase again, reaching about 2,090 present luminosities, and it will cool to about 3500 K. This phase lasts about 30 million years, after which, over the course of a further 100,000 years, the Sun's remaining outer layers will fall away, ejecting a vast stream of matter into space and forming a halo known (misleadingly) as a planetary nebula. The ejected material will contain the helium and carbon produced by the Sun's nuclear reactions, continuing the enrichment of the interstellar medium with heavy elements for future generations of stars.

text: Gradually, the hydrogen burning in the shell around the solar core will increase the mass of the core until it reaches about 45% of the present solar mass. At this point the density and temperature will become so high that the fusion of helium into

text: carbon

text: will begin, leading to a

text: helium flash

text: ; the Sun will shrink from around 250 to 11 times its present (main-sequence) radius. Consequently, its luminosity will decrease from around 3,000 to 54 times its current level, and its surface temperature will increase to about 4770 K. The Sun will become a

text: horizontal giant

text: , burning helium in its core in a stable fashion much like it burns hydrogen today. The helium-fusing stage will last only 100 million years. Eventually, it will have to again resort to the reserves of hydrogen and helium in its outer layers and will expand a second time, turning into what is known as an

text: asymptotic giant

text: . Here the luminosity of the Sun will increase again, reaching about 2,090 present luminosities, and it will cool to about 3500 K. This phase lasts about 30 million years, after which, over the course of a further 100,000 years, the Sun's remaining outer layers will fall away, ejecting a vast stream of matter into space and forming a halo known (misleadingly) as a

text: planetary nebula

text: . The ejected material will contain the helium and carbon produced by the Sun's nuclear reactions, continuing the enrichment of the interstellar medium with heavy elements for future generations of stars.

text: This is explained by having the ships warp to another "dimension", presumably a brane universe with different physical laws. Gravity supposedly reaches between branes. In Star Wars, gravity in real spaces forms gravitic "mass shadows" in hyperspace. Hyperspace in Star Wars is unrelated to the presumed space between universal "bubbles" in real life physics.

text: This is explained by having the ships warp to another "

text: dimension

text: ", presumably a

text: brane

text: universe with different physical laws. Gravity supposedly reaches between branes. In Star Wars, gravity in real spaces forms gravitic "mass shadows" in hyperspace. Hyperspace in Star Wars is unrelated to the presumed space between universal "bubbles" in real life

text: physics

text: Ethnographic and anthropological studies such as Prof. Gary Urton's demonstrate that Inka believe systems were inter-related to their view of the cosmos, in particular the way that they observed the motions of the portion of the milky way and planets of the solar system as seen from the Cusco or Qosqo (their capital whose meaning is 'the centre of the earth'). From this perspective their stories depict the movements of constellations, planets, planetary formations, which are connected to their agricultural cycles for a society that relied on cyclical agricultural seasons, which were not only connected to year cycles (as in Europe) but to a much wider cycle of time (every 800 years at a time). This was the main tool to ensure cultural transmission of key information, in spite of regime change or social catastrophes.

text: Gabriel, a minor Aristos, runs a group of planets containing societies devoted to artistic pursuits, assisted by his several daimones, each of whom has his or her own personality and special area of interest. Attending oneirochronon parties and composing operas, having sex with both men and women (at one point, he has sex with two women at once—one in physical reality, one in the oneirochronon) he seems to live a leisurely, decadent life. An elder Ariste, Cressida, warns Gabriel that something is up in a nearby solar system. There appear to be some extra planets in an area which astronomical surveys had said contained none. Cressida is murdered before she can explain more but Gabriel begins to suspect that Saito, the Aristoi whose domain is closest to the mystery solar system, is using it for some undisclosed purpose. Gabriel and some of his advisers leave on a secret mission to the mystery solar system. When they arrive there they discover a horrifying truth: the planets contain life, human life. The most advanced of the planets contains a society similar in nature and technological development to Renaissance Europe. The people here have been left without the guidance and control of an Aristos and are mired in constant warfare and squalor, perishing of diseases which modern technology can easily cure. Someone, presumably Saito, has created human life here and consigned it to perpetual suffering for some unknown reason. Horrified by the suffering they see, Gabriel and some of his companions travel down to the planet to investigate. Posing as visitors from a distant country they identify a local nobleman who they believe to be Saito and arrange a confrontation. While they are waiting for their chance to assassinate Saito they see their spaceship, which had been orbiting the planet, destroyed. Their assassination attempt fails when they realize that the nobleman is actually an artificial lifeform. Gabriel and his companions are captured and imprisoned. It is then that Gabriel is confronted with the truth: the mastermind behind this horrifying experiment is not Saito, but Captain Yuan, the architect of the current galactic civilization who had long been presumed dead. Yuan explains his motives behind creating new life: the galactic society of the Logarchy has become staid and stultifying. Protected from any danger, the people have stopped improving and have become slaves of the Aristoi. He created this new solar system and the life within it in order to give a new start to humanity and create a society free from the restrictions of the Logarchy. Yuan, Saito, and Zhenling, an Ariste who Gabriel had considered an ally and even taken as a lover, then begin a brainwashing program on Gabriel, eventually breaking his will and convincing him to help them with minor duties on their project. However, their plan is foiled when a previously hidden sub personality of Gabriel, that he dubs The Voice, uses his computer privileges to escape. Gabriel manages to defeat Saito and escape along with his friends. He informs the rest of the Logarchy about what has happened and rallies them to a war footing. The Logarchy's forces swarm into the new solar system to provide humanitarian relief and begin to integrate the societies into the galactic society. As Yuan's secrets are revealed it is also discovered that he had tampered with the examination process which forms the backbone of the Logarchy, promoting people to Aristoi who he believed could help him and keeping others back. Captain Yuan himself has escaped to parts unknown and Gabriel makes it his life's mission to track him down and bring him to justice. As he does so he is warned by Zhenling, now imprisoned, that in doing so he will only fulfill Yuan's plan to shake up the galactic status quo.

text: He was born in 1958 in England, and is a 1979 graduate of University College, London (UCL). Jewitt received an M.Sc. and a Ph.D. in astronomy at the California Institute of Technology in 1980 and 1983, respectively. His research interests cover all aspects of the solar system, including the trans-Neptunian Solar System, Solar System formation, ice in the asteroids and the physical properties of comets. Along with Jane Luu, he discovered the first Kuiper belt object (other than Pluto and its largest moon Charon) in 1992 and subsequently identified dozens of additional belt members in a series of pioneering wide field surveys. From these, he discovered that the belt is dynamically divided into regions – the classical Kuiper belt (circular, uninclined orbits, exemplified by ), the scattered disc (also called the "scattered Kuiper belt", which bodies have large elliptical orbits with perihelion near Neptune, discovered in 1997) and the Resonant Kuiper belt objects, whose periods are related simply to Neptune's. Those resonant objects in the 3:2 mean-motion resonance he called plutinos as a reminder that Pluto is one such object. These resonant objects can only be explained if Neptune migrated outwards, opening the door to new models of the Solar System in which unsuspected planet-disk and planet-planet interactions can be important.

text: He was born in 1958 in

text: England

text: , and is a 1979 graduate of

text: University College, London

text: (UCL). Jewitt received an M.Sc. and a Ph.D. in astronomy at the

text: California Institute of Technology

text: in 1980 and 1983, respectively. His research interests cover all aspects of the solar system, including the

text: trans-Neptunian Solar System

text: Solar System

text: formation, ice in the asteroids and the physical properties of

text: comet

text: s. Along with

text: Jane Luu

text: , he discovered the first

text: Kuiper belt object

text: (other than

text: Pluto

text: and its largest moon

text: Charon

text: ) in 1992 and subsequently identified dozens of additional belt members in a series of pioneering wide field surveys. From these, he discovered that the belt is dynamically divided into regions – the

text: classical Kuiper belt

text: (circular, uninclined orbits, exemplified by ), the

text: scattered disc

text: (also called the "scattered Kuiper belt", which bodies have large elliptical orbits with perihelion near Neptune, discovered in 1997) and the

text: Resonant Kuiper belt object

text: s, whose periods are related simply to Neptune's. Those resonant objects in the

entity_section: Mean-motion resonances in the Solar System

text: mean-motion

text: resonance

text: he called

text: plutino

text: s as a reminder that Pluto is one such object. These resonant objects can only be explained if Neptune migrated outwards, opening the door to new models of the Solar System in which unsuspected planet-disk and planet-planet interactions can be important.

text: Spurred greatly by the assassination of the queen and subsequent unrest, the government, then led by a new progressive cabinet headed by Kim Hong-jip and Yu Kil-chun, carried out reforms from October 1895 to February 1896. A special reform body, Gunguk Gimucheo (군국기무처, Deliberative Council), was created to establish rules. Their policies resulted in the official discarding of the lunar calendar in favor of the modern Gregorian solar calendar, the official designation of regnal years independent of the Chinese tradition, the creation of a postal service, the introduction of primary schools and a new educational system and the renewal of the military system.

text: Spurred greatly by the assassination of the queen and subsequent unrest, the government, then led by a new progressive cabinet headed by

text: Kim Hong-jip

text: and

text: Yu Kil-chun

text: , carried out reforms from October 1895 to February 1896. A special reform body, Gunguk Gimucheo (군국기무처, Deliberative Council), was created to establish rules. Their policies resulted in the official discarding of the

text: lunar calendar

text: in favor of the modern Gregorian

text: solar calendar

text: , the official designation of

text: regnal years

text: independent of the Chinese tradition, the creation of a

text: postal service

text: , the introduction of primary schools and a new educational system and the renewal of the military system.

text: An exoplanet (extrasolar planet) is a planet outside the Solar System. More than 2000 such planets have been discovered( planets in  planetary systems including  multiple planetary systems as of ).

text: An exoplanet (extrasolar planet) is a planet outside the Solar System. More than 2000 such planets have been discovered( planets in

text: planetary system

text: s including

text: multiple planetary systems

text: as of ).

text: The solar magnetic field extends well beyond the Sun itself. The electrically conducting solar wind plasma carries the Sun's magnetic field into space, forming what is called the interplanetary magnetic field. In an approximation known as ideal magnetohydrodynamics, plasma particles only move along the magnetic field lines. As a result, the outward-flowing solar wind stretches the interplanetary magnetic field outward, forcing it into a roughly radial structure. For a simple dipolar solar magnetic field, with opposite hemispherical polarities on either side of the solar magnetic equator, a thin current sheet is formed in the solar wind. At great distances, the rotation of the Sun twists the dipolar magnetic field and corresponding current sheet into an Archimedean spiral structure called the Parker spiral. The interplanetary magnetic field is much stronger than the dipole component of the solar magnetic field. The Sun's dipole magnetic field of 50–400 μT (at the photosphere) reduces with the inverse-cube of the distance to about 0.1 nT at the distance of Earth. However, according to spacecraft observations the interplanetary field at Earth's location is around 5 nT, about a hundred times greater. The difference is due to magnetic fields generated by electrical currents in the plasma surrounding the Sun.

text: The solar magnetic field extends well beyond the Sun itself. The electrically conducting solar wind plasma carries the Sun's magnetic field into space, forming what is called the

text: interplanetary magnetic field

text: . In an approximation known as ideal

text: magnetohydrodynamics

text: , plasma particles only move along the magnetic field lines. As a result, the outward-flowing solar wind stretches the interplanetary magnetic field outward, forcing it into a roughly radial structure. For a simple dipolar solar magnetic field, with opposite hemispherical polarities on either side of the solar magnetic equator, a thin

text: current sheet

text: is formed in the solar wind. At great distances, the rotation of the Sun twists the dipolar magnetic field and corresponding current sheet into an

text: Archimedean spiral

text: structure called the

text: Parker spiral

text: . The interplanetary magnetic field is much stronger than the dipole component of the solar magnetic field. The Sun's dipole magnetic field of 50–400

text: μT

text: (at the photosphere) reduces with the inverse-cube of the distance to about 0.1 nT at the distance of Earth. However, according to spacecraft observations the interplanetary field at Earth's location is around 5 nT, about a hundred times greater. The difference is due to magnetic fields generated by electrical currents in the plasma surrounding the Sun.

text: For example, when a pen falls off a desk, that seems to be proof that gravity exists, because gravity made it fall. But what is "gravity"?  In 1500, "gravity" was the pen's desire to go to the center of the earth; in 1700 "gravity" was a force that acted at a distance according to mathematical laws; in the 1900s "gravity" was an effect of curved space-time; and today physicists theorize that "gravity" may be a force carried by subatomic particles called "gravitons". Gendlin views "gravity" as a concept and points out that concepts can't make anything fall. Instead of saying that gravity causes things to fall, it would be more accurate to say that things falling cause [the different concepts of] gravity. Interaction with the world is prior to concepts about the world.

text: For example, when a pen falls off a desk, that seems to be proof that gravity exists, because gravity made it fall. But what is "gravity"?  In 1500, "gravity" was the pen's desire to go to the center of the earth; in 1700 "gravity" was a force that acted at a distance according to mathematical laws; in the 1900s "gravity" was an effect of

text: curved space-time

text: ; and today physicists theorize that "gravity" may be a force carried by subatomic particles called "

text: gravitons

text: ". Gendlin views "gravity" as a concept and points out that concepts can't make anything fall. Instead of saying that gravity causes things to fall, it would be more accurate to say that things falling cause [the different concepts of] gravity. Interaction with the world is prior to concepts about the world.

text: Atmospheric analysis of planetary atmospheres, as is already done on various Solar System bodies and in a rudimentary fashion on several hot Jupiter extrasolar planets, may reveal the presence of chemicals produced by technological civilizations. For example, atmospheric emissions from industry on Earth, including nitrogen dioxide and chlorofluorocarbons, are detectable from space.  Artificial pollution may therefore be detectable on extrasolar planets. However, there remains a possibility of mis-detection; for example, the atmosphere of Titan has detectable signatures of complex chemicals that are similar to what on Earth are industrial pollutants, though obviously not the byproduct of civilisation. Some SETI scientists have proposed searching for artificial atmospheres created by planetary engineering to produce habitable environments for colonisation by an ETI.

text: Atmospheric analysis of planetary atmospheres, as is already done on various Solar System bodies and in a rudimentary fashion on several

text: hot Jupiter

text: extrasolar planets, may reveal the presence of chemicals produced by technological civilizations. For example, atmospheric emissions from industry on Earth, including

text: nitrogen dioxide

text: and

text: chlorofluorocarbon

text: s, are detectable from space.  Artificial pollution may therefore be detectable on extrasolar planets. However, there remains a possibility of mis-detection; for example, the

text: atmosphere of Titan

text: has detectable signatures of complex chemicals that are similar to what on Earth are industrial pollutants, though obviously not the byproduct of civilisation. Some SETI scientists have proposed searching for artificial atmospheres created by planetary engineering to produce habitable environments for colonisation by an ETI.

text: If the formation of pebbles is slow, pebble accretion leads to the formation of a few gas giants in the outer Solar System. The formation of the gas giants is a long-standing problem in planetary science. The accretion of the cores of giant planets via the collision and mergers of planetesimals is slow and may be difficult to complete before the gas disk dissipates. (Although formation via planetesimal collisions can be accomplished within the typical lifetime of a protoplanetary disc.)  The largest planetesimals can grow much faster via pebble accretion, but if the formation or delivery of pebbles is rapid numerous Earth-mass planets form instead of a few giant planet cores. As the largest objects approach Earth-mass the radius from which pebbles are accreted is limited by the Hill radius. This slows their growth relative to their neighbors (growth becomes oligarchic) and allows many objects to accrete similar masses of pebbles. However, if the formation or the delivery of pebbles is slow growth timescales becomes longer than the time required for gravitationally stirring. The largest planetesimals then excite the inclinations and eccentricities of the smaller planetesimals. Their inclined orbits keep small planetesimals outside of the narrow disk of pebbles during most of their orbits, limiting their growth. The period of runaway growth is then extended and the largest objects are able to accrete a sizable fraction of the pebbles and grow into giant planet cores. As the cores grow larger some reach masses sufficient to create partial gaps in the gas disk, altering its pressure gradient and blocking the inward drift of pebbles. Accretion of pebbles is then halted and the gas envelope surrounding the core cools and collapses allowing for the rapid accretion of gas and the formation of a gas giant. Cores that do not grow massive enough to clear gaps in the pebble disk are only able to accrete small gas envelopes and instead become ice giants. The rapid growth via pebble accretion allows the cores to grow large enough to accrete massive gas envelopes forming gas giants while avoiding migrating very close to the star. In simulations cold gas giants like Jupiter and Saturn can form via pebble accretion if their initial embryos began growing beyond 20 AU. This distant formation offers a potential explanation for Jupiter's enrichment in noble gases. However, dedicated formation models indicate that it is difficult to reconcile growth via pebble accretion with the final mass and composition of the solar system ice giants Uranus and Neptune.

text: If the formation of pebbles is slow, pebble accretion leads to the formation of a few

text: gas giant

text: s in the

text: outer Solar System

text: . The

text: formation

text: of the gas giants is a long-standing problem in

text: planetary science

text: . The

text: accretion

text: of the cores of

text: giant planets

text: via the collision and mergers of planetesimals is slow and may be difficult to complete before the gas disk dissipates. (Although formation via planetesimal collisions can be accomplished within the typical lifetime of a

text: protoplanetary disc

text: .)  The largest planetesimals can grow much faster via pebble accretion, but if the formation or delivery of pebbles is rapid numerous

text: Earth-mass

text: planets form instead of a few giant planet cores. As the largest objects approach Earth-mass the radius from which pebbles are accreted is limited by the

text: Hill radius

text: . This slows their growth relative to their neighbors (growth becomes oligarchic) and allows many objects to accrete similar masses of pebbles. However, if the formation or the delivery of pebbles is slow growth timescales becomes longer than the time required for gravitationally stirring. The largest planetesimals then excite the

text: inclination

text: s and eccentricities of the smaller planetesimals. Their inclined orbits keep small planetesimals outside of the narrow disk of pebbles during most of their orbits, limiting their growth. The period of runaway growth is then extended and the largest objects are able to accrete a sizable fraction of the pebbles and grow into giant planet cores. As the cores grow larger some reach masses sufficient to create partial gaps in the gas disk, altering its pressure gradient and blocking the inward drift of pebbles. Accretion of pebbles is then halted and the gas envelope surrounding the core cools and collapses allowing for the rapid accretion of gas and the formation of a gas giant. Cores that do not grow massive enough to clear gaps in the pebble disk are only able to accrete small gas envelopes and instead become

text: ice giant

text: s. The rapid growth via pebble accretion allows the cores to grow large enough to accrete massive gas envelopes forming gas giants while avoiding migrating very close to the star. In simulations cold gas giants like Jupiter and Saturn can form via pebble accretion if their initial embryos began growing beyond 20 AU. This distant formation offers a potential explanation for Jupiter's enrichment in noble gases. However, dedicated formation models indicate that it is difficult to reconcile growth via pebble accretion with the final mass and composition of the solar system ice giants

text: Uranus

text: and

text: Neptune

text: In 1755, Immanuel Kant speculated that observed nebulae may in fact be regions of star and planet formation. In 1796, Laplace elaborated by arguing that the nebula collapsed into a star, and, as it did so, the remaining material gradually spun outward into a flat disc, which then formed the planets.

text: In 1755, Immanuel Kant speculated that observed

text: nebulae

text: may in fact be regions of star and planet formation. In 1796, Laplace elaborated by arguing that the nebula collapsed into a star, and, as it did so, the remaining material gradually spun outward into a flat disc, which then formed the planets.

text: According to the so-called Nice model, after the formation of the Solar System, the orbits of all the giant planets continued to change slowly, influenced by their interaction with the large number of remaining planetesimals. After 500–600 million years (about 4 billion years ago) Jupiter and Saturn fell into a 2:1 resonance: Saturn orbited the Sun once for every two Jupiter orbits. This resonance created a gravitational push against the outer planets, causing Neptune to surge past Uranus and plough into the ancient Kuiper belt. The planets scattered the majority of the small icy bodies inwards, while themselves moving outwards. These planetesimals then scattered off the next planet they encountered in a similar manner, moving the planets' orbits outwards while they moved inwards. This process continued until the planetesimals interacted with Jupiter, whose immense gravity sent them into highly elliptical orbits or even ejected them outright from the Solar System. This caused Jupiter to move slightly inward. Those objects scattered by Jupiter into highly elliptical orbits formed the Oort cloud; those objects scattered to a lesser degree by the migrating Neptune formed the current Kuiper belt and scattered disc. This scenario explains the Kuiper belt's and scattered disc's present low mass. Some of the scattered objects, including Pluto, became gravitationally tied to Neptune's orbit, forcing them into mean-motion resonances. Eventually, friction within the planetesimal disc made the orbits of Uranus and Neptune circular again.

text: According to the so-called

text: Nice model

text: , after the formation of the Solar System, the orbits of all the giant planets continued to change slowly, influenced by their interaction with the large number of remaining planetesimals. After 500–600 million years (about 4 billion years ago) Jupiter and Saturn fell into a 2:1 resonance: Saturn orbited the Sun once for every two Jupiter orbits. This resonance created a gravitational push against the outer planets, causing Neptune to surge past Uranus and plough into the ancient Kuiper belt. The planets scattered the majority of the small icy bodies inwards, while themselves moving outwards. These planetesimals then scattered off the next planet they encountered in a similar manner, moving the planets' orbits outwards while they moved inwards. This process continued until the planetesimals interacted with Jupiter, whose immense gravity sent them into highly elliptical orbits or even ejected them outright from the Solar System. This caused Jupiter to move slightly inward. Those objects scattered by Jupiter into highly elliptical orbits formed the Oort cloud; those objects scattered to a lesser degree by the migrating Neptune formed the current Kuiper belt and scattered disc. This scenario explains the Kuiper belt's and scattered disc's present low mass. Some of the scattered objects, including

text: Pluto

text: , became gravitationally tied to Neptune's orbit, forcing them into

text: mean-motion resonance

text: s. Eventually, friction within the planetesimal disc made the orbits of Uranus and Neptune circular again.

text: According to the nebular hypothesis, the outer two planets are in the "wrong place". Uranus and Neptune (known as the "ice giants") exist in a region where the reduced density of the solar nebula and longer orbital times render their formation highly implausible. The two are instead thought to have formed in orbits near Jupiter and Saturn, where more material was available, and to have migrated outward to their current positions over hundreds of millions of years.

text: According to the nebular hypothesis, the outer two planets are in the "wrong place".

text: Uranus

text: and

text: Neptune

text: (known as the "

text: ice giant

text: s") exist in a region where the reduced density of the solar nebula and longer orbital times render their formation highly implausible. The two are instead thought to have formed in orbits near Jupiter and Saturn, where more material was available, and to have

text: migrated outward

text: to their current positions over hundreds of millions of years.

text: The Nine Planets is a multimedia website by Bill Arnett containing information about the Solar System.  It was one of the first examples of a multimedia website when it first appeared on the World Wide Web in 1994 and, as was common for high traffic websites at the time, it was widely mirrored.  It contains encyclopedic information about the Solar System with a page for each of the major bodies illustrated with photographs, mostly from NASA.

text: The Nine Planets is a multimedia

text: website

text: by Bill Arnett containing information about the

text: Solar System

text: .  It was one of the first examples of a multimedia

text: website

text: when it first appeared on the

text: World Wide Web

text: in 1994 and, as was common for high traffic websites at the time, it was widely

text: mirrored

text: .  It contains encyclopedic information about the

text: Solar System

text: with a page for each of the major bodies illustrated with photographs, mostly from

text: NASA

text: This mode displays the major solar system objects from the Sun to Pluto, and Jupiter's moons, orbits of all solar system moons, all 550,000+ minor planets all positioned with their correct scale, position and phase. The user can move forward and backward in time at various rates, or type in a time and date for which to view the positions of the planets, and can select viewing location. The program can show the solar system the way it would look from any location at any time between 1 AD and 4000 AD. Using this tool a user can watch an eclipse  (e.g., 2017 total solar eclipse) occultation, or astronomical alignment, and preview where the best spot might be to observe a future event. In this mode it is possible to zoom away from the Solar System, through the Milky Way, and out into the cosmos to see a hypothetical view of the entire known universe. Other bodies, spacecraft and orbital reference frames can be added and visualized in the Solar System Mode using the layer manager.

text: This mode displays the major solar system objects from the Sun to Pluto, and Jupiter's moons, orbits of all solar system moons, all 550,000+ minor planets all positioned with their correct scale, position and phase. The user can move forward and backward in time at various rates, or type in a time and date for which to view the positions of the planets, and can select viewing location. The program can show the solar system the way it would look from any location at any time between 1 AD and 4000 AD. Using this tool a user can watch an

text: eclipse

text: (e.g., 2017 total solar eclipse)

text: occultation

text: , or astronomical alignment, and preview where the best spot might be to observe a future event. In this mode it is possible to zoom away from the Solar System, through the Milky Way, and out into the cosmos to see a hypothetical view of the entire known universe. Other bodies, spacecraft and orbital reference frames can be added and visualized in the Solar System Mode using the layer manager.

text: Solar power in New Zealand currently only generates 0.1 percent of New Zealand's electricity since more emphasis has been placed on hydroelectric, geothermal, and wind power in New Zealand's push for renewable energy. Solar power systems were installed in 42 schools in New Zealand in the Schoolgen program, a program developed by Genesis Energy to educate students in solar power. Each participating school has a 2 kW solar panel. Between February 2007 and 29 December 29, 2012, 395.714 MWh were produced.

text: Solar power in New Zealand currently only generates 0.1 percent of New Zealand's electricity since more emphasis has been placed on hydroelectric, geothermal, and wind power in New Zealand's push for renewable energy. Solar power systems were installed in 42 schools in New Zealand in the Schoolgen program, a program developed by

text: Genesis Energy

text: to educate students in solar power. Each participating school has a 2 kW solar panel. Between February 2007 and 29 December 29, 2012, 395.714 MWh were produced.

text: The young stars in H II regions show evidence for containing planetary systems. The Hubble Space Telescope has revealed hundreds of protoplanetary disks (proplyds) in the Orion Nebula. At least half the young stars in the Orion Nebula appear to be surrounded by disks of gas and dust, thought to contain many times as much matter as would be needed to create a planetary system like the Solar System.

text: The young stars in H II regions show evidence for containing planetary systems. The

text: Hubble Space Telescope

text: has revealed hundreds of protoplanetary disks (

text: proplyd

text: s) in the Orion Nebula. At least half the young stars in the Orion Nebula appear to be surrounded by disks of gas and dust, thought to contain many times as much matter as would be needed to create a planetary system like the

text: Solar System

text: If a planet is detectable by both the radial-velocity and the transit methods, then both its true mass and its radius can be determined, as well as its density. Planets with low density are inferred to be composed mainly of hydrogen and helium, whereas planets of intermediate density are inferred to have water as a major constituent. A planet of high density is inferred to be rocky, like Earth and the other terrestrial planets of the Solar System.

text: If a planet is detectable by both the radial-velocity and the transit methods, then both its true mass and its radius can be determined, as well as its

text: density

text: . Planets with low density are inferred to be composed mainly of

text: hydrogen

text: and

text: helium

text: , whereas planets of intermediate density are inferred to have water as a major constituent. A planet of high density is inferred to be rocky, like Earth and the other terrestrial planets of the Solar System.

text: Jones' long-range forecasts were based on a complicated series of cycles linking planetary movements and sun spots. He saw the whole solar system as simply a vast electromagnetic machine automatically controlled by the magnetic fields of the planets, which applies among other things, to the seasons. Therefore, if it were known what the conditions were when the same planets stood in the same relation in the past, we could know what conditions would arise now and in the future.

text: On April 21, 2002 as Nozomi was approaching Earth for the gravity assist maneuver, powerful solar flares damaged the spacecraft's onboard communications and power systems. An electrical short occurred in a power cell used to control the attitude control heating system, allowing the hydrazine fuel to freeze. The fuel thawed out as the craft approached Earth and maneuvers to put the craft on the correct trajectory for its Earth flyby were successful.

text: On April 21, 2002 as Nozomi was approaching Earth for the gravity assist maneuver, powerful

text: solar flare

text: s damaged the spacecraft's onboard communications and power systems. An electrical short occurred in a power cell used to control the attitude control heating system, allowing the

text: hydrazine

text: fuel to freeze. The fuel thawed out as the craft approached Earth and maneuvers to put the craft on the correct trajectory for its Earth flyby were successful.

text: The motion of astronomical bodies has been studied systematically for thousands of years. The stars were observed to rotate uniformly, always maintaining the same relative positions to one another. However, other bodies were observed to wander against the background of the fixed stars; most such bodies were called planets after the Greek word "πλανήτοι" (planētoi) for "wanderers". Although they generally move in the same direction along a path across the sky (the ecliptic), individual planets sometimes reverse their direction briefly, exhibiting retrograde motion.

text: The motion of astronomical bodies has been studied systematically for thousands of years. The stars were observed to rotate uniformly, always maintaining the same relative positions to one another. However, other bodies were observed to wander against the background of the fixed stars; most such bodies were called

text: planet

text: s after the Greek word "πλανήτοι" (planētoi) for "wanderers". Although they generally move in the same direction along a path across the sky (the

text: ecliptic

text: ), individual planets sometimes reverse their direction briefly, exhibiting

text: retrograde motion

text: The most notable examples of mass-independent fractionation in nature are found in the isotopes of oxygen and sulfur. The first example was discovered by Robert N. Clayton, Toshiko Mayeda, and Lawrence Grossman in 1973, in the oxygen isotopic composition of refractory calcium-aluminium-rich inclusions in the Allende meteorite. The inclusions, thought to be among the oldest solid materials in the Solar System, show a pattern of low O/O and O/O relative to samples from the Earth and Moon. Both ratios vary by the same amount in the inclusions, although the mass difference between O and O is almost twice as large as the difference between O and O. Originally this was interpreted as evidence of incomplete mixing of O-rich material (created and distributed by a large star in a supernova) into the Solar nebula. However, recent measurement of the oxygen-isotope composition of the Solar wind, using samples collected by the Genesis spacecraft, shows that the most O-rich inclusions are close to the bulk composition of the solar system. This implies that Earth, the Moon, Mars and asteroids all formed from O- and O-enriched material.  Photochemical dissociation of carbon monoxide in the Solar nebula has been proposed to explain this isotope fractionation.

text: The most notable examples of mass-independent fractionation in nature are found in the isotopes of

text: oxygen

text: and

text: sulfur

text: . The first example was discovered by Robert N. Clayton, Toshiko Mayeda, and Lawrence Grossman in 1973, in the oxygen isotopic composition of

text: refractory

text: calcium-aluminium-rich inclusion

text: s in the

text: Allende meteorite

text: . The inclusions, thought to be among the oldest solid materials in the

text: Solar System

text: , show a pattern of low O/O and O/O relative to samples from the Earth and

text: Moon

text: . Both ratios vary by the same amount in the inclusions, although the mass difference between O and O is almost twice as large as the difference between O and O. Originally this was interpreted as evidence of incomplete mixing of O-rich material (created and distributed by a large star in a

text: supernova

text: ) into the

text: Solar nebula

text: . However, recent measurement of the oxygen-isotope composition of the

text: Solar wind

text: , using samples collected by the

text: Genesis spacecraft

text: , shows that the most O-rich inclusions are close to the bulk composition of the solar system. This implies that Earth, the Moon, Mars and asteroids all formed from O- and O-enriched material.  Photochemical dissociation of

text: carbon monoxide

text: in the Solar nebula has been proposed to explain this isotope fractionation.

text: The interaction between Earth’s magnetic field and the solar wind results in the formation of a collisionless bow shock 60,000–100,000 km upstream of our planet, as long as the solar wind fast magnetosonic Mach number exceeds unity. A recent paper published in Nature Communications by Dr. Lugaz and co-authors (University of New Hampshire, USA) presents one of those extremely rare instances, when the solar wind Mach number reached steady values below 1 for several hours on 17 January 2013. Simultaneous measurements by more than ten spacecraft, including Cluster, in the near-Earth environment reveal the evanescence of the bow shock, the sunward motion of the magnetopause and the extremely rapid and intense loss of electrons in the outer radiation belt. This study allows to directly observe the state of the inner magnetosphere, including the radiation belts during a type of solar wind-magnetosphere coupling which is unusual for planets in our solar system but may be common for close-in extrasolar planets.

text: The Jet Propulsion Laboratory (JPL) Science Division investigates physical and chemical processes on the Earth, in the solar system, and throughout the universe. Explorations of space and terrestrial processes lead to understanding of the universe. Methods for accomplishing scientific work pertaining to the nature of the Earth, the Solar System, the galaxy, etc., are addressed in the JPL Science Division. Techniques in both physical and life sciences are utilized.

text: The

text: Jet Propulsion Laboratory

text: (JPL) Science Division investigates

text: physical

text: and

text: chemical process

text: es on the Earth, in the

text: solar system

text: , and throughout the universe. Explorations of space and terrestrial processes lead to understanding of the universe. Methods for accomplishing

text: scientific

text: work pertaining to the nature of the Earth, the Solar System, the galaxy, etc., are addressed in the JPL Science Division. Techniques in both physical and

text: life sciences

text: are utilized.

text: The average of the true solar day during the course of an entire year is the mean solar day, which contains  solar seconds. Currently, each of these seconds is slightly longer than an SI second because Earth's mean solar day is now slightly longer than it was during the 19th century due to tidal friction. The average length of the mean solar day since the introduction of the leap second in 1972 has been about 0 to 2 ms longer than 86,400 SI seconds. Random fluctuations due to core-mantle coupling have an amplitude of about 5 ms. The mean solar second between 1750 and 1892 was chosen in 1895 by Simon Newcomb as the independent unit of time in his Tables of the Sun. These tables were used to calculate the world's ephemerides between 1900 and 1983, so this second became known as the ephemeris second. In 1967 the SI second was made equal to the ephemeris second.

text: The average of the true solar day during the course of an entire year is the mean solar day, which contains  solar seconds. Currently, each of these seconds is slightly longer than an

text: SI

text: second because Earth's mean solar day is now slightly longer than it was during the 19th century due to

text: tidal friction

text: . The average length of the mean solar day since the introduction of the leap second in 1972 has been about 0 to 2 ms longer than 86,400 SI seconds. Random fluctuations due to core-mantle coupling have an amplitude of about 5 ms. The mean solar second between 1750 and 1892 was chosen in 1895 by

text: Simon Newcomb

text: as the independent unit of time in his

text: Tables of the Sun

text: . These tables were used to calculate the world's

text: ephemerides

text: between 1900 and 1983, so this second became known as the

text: ephemeris second

text: . In 1967 the SI second was made equal to the ephemeris second.

text: In 1996 an exoplanet (47 UMa b) was announced in orbit around 47 Ursae Majoris by Geoffrey Marcy and R. Paul Butler. The discovery was made by observing the Doppler shift of the star's spectrum corresponding to changes in the star's radial velocity as the planet's gravity pulled it around. The planet was the first long-period extrasolar planet discovered. Unlike the majority of known such planets, it has a low-eccentricity orbit. The planet is at least 2.53 times the mass of Jupiter and takes 1,078 days or 2.95 years to orbit its star. If it were to be located in the Solar System, it would lie between the orbits of Mars and Jupiter.

text: In 1996 an

text: exoplanet

text: 47 UMa b

text: ) was announced in orbit around 47 Ursae Majoris by

text: Geoffrey Marcy

text: and

text: R. Paul Butler

text: . The discovery was made by observing the

text: Doppler shift

text: of the star's

text: spectrum

text: corresponding to changes in the star's

text: radial velocity

text: as the planet's

text: gravity

text: pulled it around. The planet was the first long-

text: period

text: extrasolar planet discovered. Unlike the majority of known such planets, it has a low-

text: eccentricity

text: orbit. The planet is at least 2.53 times the mass of

text: Jupiter

text: and takes 1,078 days or 2.95 years to orbit its star. If it were to be located in the Solar System, it would lie between the orbits of

text: Mars

text: and Jupiter.

text: In a daring attempt to save the solar system, a group of ships, led by Nathan R. Gunne, lured the Terraformers through the gate into the X Universe. The Earth gate was then destroyed, trapping the Terraformers in the X-Universe and cutting Earth off from the rest of the network.

text: With most solar water heating systems, the energy output scales linearly with the surface area of the absorbers. Therefore, when comparing figures, take into account the absorber area of the collector because collectors with less absorber area yield less heat, even within the 2 m range. Specifications for many complete solar water heating systems and separate solar collectors can be found at Internet site of the SRCC.

text: A variation of this technology has been developed to be more environmentally friendly, primarily through the use of passive solar energy and gravity.  Brine is streamed down the outside of towers, where it absorbs water from the air.  The brine then enters a chamber and subjected to a partial vacuum and heated. The water vapor is collected and condensed, while the renewed brine is recirculated through the system.  As the condensed water is removed from the system using gravity, it creates the vacuum which lowers the boiling point of the brine.

text: A variation of this technology has been developed to be more environmentally friendly, primarily through the use of

text: passive solar

text: energy and

text: gravity

text: .  Brine is streamed down the outside of towers, where it absorbs water from the air.  The brine then enters a chamber and subjected to a partial

text: vacuum

text: and heated. The water vapor is collected and condensed, while the renewed brine is recirculated through the system.  As the condensed water is removed from the system using gravity, it creates the vacuum which lowers the boiling point of the brine.

text: To recover a multigraph from a rotation system, we form a vertex for each orbit of σ, and an edge for each orbit of θ. A vertex is incident with an edge if these two orbits have a nonempty intersection. Thus, the number of incidences per vertex is the size of the orbit, and the number of incidences per edge is exactly two. If a rotation system is derived from a 2-cell embedding of a connected multigraph G, the graph derived from the rotation system is isomorphic to G.

text: According to Pribulla et al. (2000) a third object could be present in the system. Minimum mass is estimated 5 percent of Solar mass (roughly 50 times the mass of Jupiter), orbital period close to 85 years and eccentricity is inferred to be high (e=0.56). Such object could likely turn out a brown dwarf or even a massive jovian planet. Nevertheless, recent paper of Manzoori (2009) states that minimum mass of the third body is likely close to 0.6 Solar masses, making the object stellar rather substellar. Also orbital period turns out longer than 85 years.

text: According to Pribulla et al. (2000) a third object could be present in the system. Minimum mass is estimated 5 percent of

text: Solar mass

text: (roughly 50 times the mass of

text: Jupiter

text: ), orbital period close to 85 years and eccentricity is inferred to be high (e=0.56). Such object could likely turn out a

text: brown dwarf

text: or even a massive

text: jovian planet

text: . Nevertheless, recent paper of Manzoori (2009) states that minimum mass of the third body is likely close to 0.6

text: Solar mass

text: es, making the object stellar rather substellar. Also orbital period turns out longer than 85 years.

text: Asteroids, comets, and meteoroids are all debris remaining from the nebula in which the Solar System formed 4.6 billion years ago.

text: In the earliest solar system history, the Sun, the planetesimals and the jovian planets were formed. The inner solar system aggregated more slowly than the outer, so the terrestrial planets were not yet formed, including Earth and Moon.

text: In the earliest solar system history, the Sun, the

text: planetesimal

text: s and the

text: jovian planets

text: were formed. The inner solar system aggregated more slowly than the outer, so the terrestrial planets were not yet formed, including

text: Earth

text: and

text: Moon

text: Still other nebulae form as planetary nebulae. This is the final stage of a low-mass star's life, like Earth's Sun. Stars with a mass up to 8–10 solar masses evolve into red giants and slowly lose their outer layers during pulsations in their atmospheres.  When a star has lost enough material, its temperature increases and the ultraviolet radiation it emits can ionize the surrounding nebula that it has thrown off. Our Sun will produce a planetary nebula and its core will remain behind in the form of white dwarf.

text: Still other nebulae form as

text: planetary nebulae

text: . This is the final stage of a low-mass star's life, like

text: Earth

text: 's

text: Sun

text: Star

text: s with a

text: mass

text: up to 8–10 solar masses evolve into

text: red giant

text: s and slowly lose their outer layers during pulsations in their atmospheres.  When a star has lost enough material, its temperature increases and the

text: ultraviolet radiation

text: it emits can

text: ion

text: ize the surrounding nebula that it has thrown off. Our Sun will produce a planetary nebula and its core will remain behind in the form of

text: white dwarf

text: The principal component of the Solar System is the Sun, a G2 main-sequence star that contains 99.86% of the system's known mass and dominates it gravitationally. The Sun's four largest orbiting bodies, the giant planets, account for 99% of the remaining mass, with Jupiter and Saturn together comprising more than 90%. The remaining objects of the Solar System (including the four terrestrial planets, the dwarf planets, moons, asteroids, and comets) together comprise less than 0.002% of the Solar System's total mass.

text: The principal component of the Solar System is the Sun, a

text: G2 main-sequence star

text: that contains 99.86% of the system's known mass and dominates it gravitationally. The Sun's four largest orbiting bodies, the

text: giant planet

text: s, account for 99% of the remaining mass, with Jupiter and Saturn together comprising more than 90%. The remaining objects of the Solar System (including the four

text: terrestrial planet

text: s, the

text: dwarf planet

text: s,

text: moons

text: asteroid

text: s, and

text: comet

text: s) together comprise less than 0.002% of the Solar System's total mass.

text: An illustration of the theory in practice is the Copernican revolution, where Copernicus’ idea of a (sun-centered) solar system was largely ignored (not in the rules) when first introduced; then Galileo was deemed a heretic for supporting the idea (rules called into question); and finally, after a revolution in cosmology, the solar system became an obvious and foundational part of scientific knowledge (new rules).

text: An illustration of the theory in practice is the

text: Copernican revolution

text: , where Copernicus’ idea of a (sun-centered) solar system was largely ignored (not in the rules) when first introduced; then

text: Galileo

text: was deemed a heretic for supporting the idea (rules called into question); and finally, after a revolution in cosmology, the solar system became an obvious and foundational part of scientific knowledge (new rules).

text: The orbiter consisted of a cylinder with two solar panel wings and a high gain parabolic antenna attached to the curved surface. A bell-shaped unit holding propulsion systems was attached to the bottom of the cylinder, and mounted on top was a  sphere which held the lander.

text: The orbiter consisted of a cylinder with two

text: solar panel

text: wings and a high gain parabolic antenna attached to the curved surface. A bell-shaped unit holding propulsion systems was attached to the bottom of the cylinder, and mounted on top was a  sphere which held the lander.

text: The last stage of rocky planet formation is the merger stage. It begins when only a small number of planetesimals remains and embryos become massive enough to perturb each other, which causes their orbits to become chaotic. During this stage embryos expel remaining planetesimals, and collide with each other. The result of this process, which lasts for 10 to 100 million years, is the formation of a limited number of Earth sized bodies. Simulations show that the number of surviving planets is on average from 2 to 5. In the Solar System they may be represented by Earth and Venus. Formation of both planets required merging of approximately 10–20 embryos, while an equal number of them were thrown out of the Solar System. Some of the embryos, which originated in the asteroid belt, are thought to have brought water to Earth. Mars and Mercury may be regarded as remaining embryos that survived that rivalry. Rocky planets, which have managed to coalesce, settle eventually into more or less stable orbits, explaining why planetary systems are generally packed to the limit; or, in other words, why they always appear to be at the brink of instability.

text: The last stage of rocky planet formation is the merger stage. It begins when only a small number of planetesimals remains and embryos become massive enough to perturb each other, which causes their orbits to become

text: chaotic

text: . During this stage embryos expel remaining planetesimals, and collide with each other. The result of this process, which lasts for 10 to 100 million years, is the formation of a limited number of Earth sized bodies. Simulations show that the number of surviving planets is on average from 2 to 5. In the Solar System they may be represented by Earth and

text: Venus

text: . Formation of both planets required merging of approximately 10–20 embryos, while an equal number of them were thrown out of the Solar System. Some of the embryos, which originated in the

text: asteroid belt

text: , are thought to have brought water to Earth. Mars and

text: Mercury

text: may be regarded as remaining embryos that survived that rivalry. Rocky planets, which have managed to coalesce, settle eventually into more or less stable orbits, explaining why planetary systems are generally packed to the limit; or, in other words, why they always appear to be at the brink of instability.

text: Other discoveries made with Hubble data include proto-planetary disks (proplyds) in the Orion Nebula; evidence for the presence of extrasolar planets around Sun-like stars; and the optical counterparts of the still-mysterious gamma ray bursts. HST has also been used to study objects in the outer reaches of the Solar System, including the dwarf planets Pluto and Eris.

text: Other discoveries made with Hubble data include proto-planetary disks (

text: proplyd

text: s) in the

text: Orion Nebula

text: ; evidence for the presence of

text: extrasolar planet

text: s around Sun-like stars; and the optical counterparts of the still-mysterious

text: gamma ray burst

text: s. HST has also been used to study objects in the outer reaches of the Solar System, including the dwarf planets

text: Pluto

text: and

text: Eris

text: Gravity has had an effect on the development of animal life since the first single-celled organism.The size of single biological cells is inversely proportional to the strength of the gravitational field exerted on the cell. That is, in stronger gravitational fields the size of cells decreases, and in weaker gravitational fields the size of cells increases. Gravity is thus a limiting factor in the growth of individual cells.

text: Gravity has had an effect on the development of animal life since the first

text: single-celled organism

text: .The size of single biological cells is

text: inversely proportional

text: to the strength of the gravitational field exerted on the cell. That is, in stronger gravitational fields the size of cells decreases, and in weaker gravitational fields the size of cells increases. Gravity is thus a limiting factor in the growth of individual cells.

text: U.S. wind power installed capacity now exceeds 72,000 MW and supplies 4.1% of the nation's electricity. Texas is firmly established as the leader in wind power development, followed by Iowa and California. Since the U.S. pioneered the technology with Solar One, several solar thermal power stations have also been built.  The largest of these solar thermal power stations are the Ivanpah Solar Power Facility (392 MW), southwest of Las Vegas, and the SEGS group of plants in the Mojave Desert, with a total generating capacity of 354 MW. Large photovoltaic power plants in the USA include Solar Star (579 MW), near Rosamond, California, the Desert Sunlight Solar Farm, a 550 MW solar power plant in Riverside County, California and the Topaz Solar Farm, a 550 MW photovoltaic power plant, in San Luis Obispo County, California. The Geysers in Northern California is the largest complex of geothermal energy production in the world.

text: U.S. wind power

text: installed capacity now exceeds 72,000 MW and supplies 4.1% of the nation's electricity.

text: Texas

text: is firmly established as the leader in wind power development, followed by Iowa and California. Since the U.S. pioneered the technology with

text: Solar One

text: , several

text: solar thermal power

text: stations have also been built.  The largest of these solar thermal power stations are the

text: Ivanpah Solar Power Facility

text: (392 MW), southwest of Las Vegas, and the

text: SEGS

text: group of plants in the Mojave Desert, with a total generating capacity of 354 MW. Large

text: photovoltaic power plant

text: s in the USA include

text: Solar Star

text: (579 MW), near

text: Rosamond, California

text: , the

text: Desert Sunlight Solar Farm

text: , a 550 MW

text: solar power

text: plant in

text: Riverside County, California

text: and the

text: Topaz Solar Farm

text: , a 550 MW

text: photovoltaic

text: power plant, in

text: San Luis Obispo County, California

text: The Geysers

text: in Northern California is the largest complex of

text: geothermal energy

text: production in the world.

text: Yet slower than biological evolution is the time scale of astronomical change. The relations among the celestial bodies of the solar system were first depicted mathematically by Newton. The precision with which the field of celestial mechanics is able to describe the movements of bodies of the solar system is due to the incredibly slow time scale of astronomical, evolutionary change. Boulding's longstanding concern was that equilibrium analysis, market dynamics and growth theory as practised in conventional economics are based on the mathematics of difference and differential equations, as found in celestial mechanics.

text: Yet slower than biological evolution is the time scale of astronomical change. The relations among the celestial bodies of the solar system were first depicted mathematically by

text: Newton

text: . The precision with which the field of celestial mechanics is able to describe the movements of bodies of the solar system is due to the incredibly slow time scale of astronomical, evolutionary change. Boulding's longstanding concern was that equilibrium analysis, market dynamics and growth theory as practised in conventional economics are based on the mathematics of difference and differential equations, as found in

text: celestial mechanics

text: The terrestrial planets may be much smaller than the giant planets due to the sublimation of water ice as pebbles crossed the ice line. The radial drift of pebbles causes them to cross the ice line where water ice sublimates releasing silicate grains. The silicate grains are less sticky than icy grains resulting in bouncing, or fragmentation during collisions and the formation of smaller pebbles. These smaller pebbles are dispersed into a thicker disk by the turbulence in the gas disk. The mass flow of solids drifting through the terrestrial region is also reduced by half by the loss of water ice. In combination these two factors significantly reduce the rate at which mass is accreted by planetesimals in the inner Solar System relative to the outer Solar System. As a result, lunar mass planetary embryos in the inner Solar System are able to grow only to around Mars-mass, whereas in the outer Solar System they are able to grow to more than 10x Earth-mass forming the cores of giant planets. Beginning instead with planetesimals formed via streaming instabilities yields similar results in the inner Solar System. In the asteroid belt the largest planetesimals grow into Mars-massed embryos. These embryos stir the smaller planetesimals, increasing their inclinations, causing them to leave the pebble disk. The growth of these smaller planetesimals is stalled at this point, freezing their size distribution near that of the current asteroid belt. The variation of accretion efficiency with pebble size during this process results in the size sorting of the chondrules observed in the primitive meteorites. In the terrestrial zone pebble accretion plays a smaller role. Here growth is due to a mix of pebble and planetesimal accretion until an oligarchical configuration of isolate lunar-massed embryos forms. Continued growth due to the accretion of inward drifting chondrules increases the mass of these embryos until their orbits are destabilized, leading to giant impacts between the embryos and the formation of Mars-sized embryos. The cutoff of the inward drift of icy pebbles by the formation of Jupiter before the ice line moved into the terrestrial region would limit the water fraction of the planets formed from these embryos.

text: The terrestrial planets may be much smaller than the giant planets due to the sublimation of water ice as pebbles crossed the ice line. The radial drift of pebbles causes them to cross the ice line where water ice

text: sublimates

text: releasing

text: silicate

text: grains. The silicate grains are less sticky than icy grains resulting in bouncing, or fragmentation during collisions and the formation of smaller pebbles. These smaller pebbles are dispersed into a thicker disk by the turbulence in the gas disk. The mass flow of solids drifting through the

text: terrestrial region

text: is also reduced by half by the loss of water ice. In combination these two factors significantly reduce the rate at which mass is accreted by planetesimals in the inner Solar System relative to the outer Solar System. As a result, lunar mass planetary embryos in the inner Solar System are able to grow only to around Mars-mass, whereas in the outer Solar System they are able to grow to more than 10x Earth-mass forming the cores of giant planets. Beginning instead with planetesimals formed via

text: streaming instabilities

text: yields similar results in the inner Solar System. In the asteroid belt the largest planetesimals grow into Mars-massed embryos. These embryos stir the smaller planetesimals, increasing their inclinations, causing them to leave the pebble disk. The growth of these smaller planetesimals is stalled at this point, freezing their size distribution near that of the current asteroid belt. The variation of accretion efficiency with pebble size during this process results in the size sorting of the chondrules observed in the primitive meteorites. In the terrestrial zone pebble accretion plays a smaller role. Here growth is due to a mix of pebble and planetesimal accretion until an oligarchical configuration of isolate lunar-massed embryos forms. Continued growth due to the accretion of inward drifting chondrules increases the mass of these embryos until their orbits are destabilized, leading to giant impacts between the embryos and the formation of Mars-sized embryos. The cutoff of the inward drift of icy pebbles by the formation of Jupiter before the ice line moved into the terrestrial region would limit the water fraction of the planets formed from these embryos.

text: HAT-P-33, or GSC 2461-00988, is an F-type star that lies 419 parsecs (1,367 light years) away from Earth. The star has 1.403 solar masses and 1.777 solar radii; the star is, in other words, 40% more massive than and 77% larger than the Sun. With an effective temperature of 6401 K, HAT-P-33 is hotter than the Sun. It is also more metal-rich, with a metallicity that is measured at [Fe/H] = 0.05. This means that HAT-P-33 has 12% more iron than the amount measured in the Sun. HAT-P-33 is younger than the Sun, at an estimated age of 2.4 billion years. The surface gravity of the star is determined to be 4.09. All the values above are determined with the assumption that planet HAT-P-33b has an irregular, or eccentric, orbit.

text: HAT-P-33, or GSC 2461-00988, is an

text: F-type

text: star that lies 419

text: parsec

text: s (1,367

text: light year

text: s) away from Earth. The star has 1.403

text: solar mass

text: es and 1.777

text: solar radii

text: ; the star is, in other words, 40% more massive than and 77% larger than the Sun. With an effective temperature of 6401

text: K

text: , HAT-P-33 is hotter than the Sun. It is also more metal-rich, with a

text: metallicity

text: that is measured at [Fe/H] = 0.05. This means that HAT-P-33 has 12% more iron than the amount measured in the Sun. HAT-P-33 is younger than the Sun, at an estimated age of 2.4 billion years. The

text: surface gravity

text: of the star is determined to be 4.09. All the values above are determined with the assumption that planet HAT-P-33b has an irregular, or

text: eccentric

text: , orbit.

text: A near-Earth object (NEO) is any small Solar System body whose orbit brings it into proximity with Earth. By definition, a solar system body is a NEO if its closest approach to the Sun (perihelion) is less than 1.3 astronomical unit (AU). NEOs include more than fourteen thousand near-Earth asteroids (NEAs), more than one hundred near-Earth comets (NECs), and a number of solar-orbiting spacecraft and meteoroids, large enough to be tracked in space before striking the Earth. It is now widely accepted that collisions in the past have had a significant role in shaping the geological and biological history of the Earth. NEOs have become of increased interest since the 1980s because of increased awareness of the potential danger some of the asteroids or comets pose, and mitigations are being researched. In January 2016, NASA announced the Planetary Defense Coordination Office to track NEOs larger than 30 to 50 meters in diameter and coordinate an effective threat response and mitigation effort.

text: A near-Earth object (NEO) is any

text: small Solar System body

text: whose orbit brings it into proximity with

text: Earth

text: . By definition, a solar system body is a NEO if its closest approach to the Sun (

text: perihelion

text: ) is less than 1.3

text: astronomical unit

text: (AU). NEOs include more than fourteen thousand near-Earth asteroids (NEAs), more than one hundred near-Earth comets (NECs), and a number of solar-orbiting

text: spacecraft

text: and

text: meteoroid

text: s, large enough to be tracked in space before striking the Earth. It is now widely accepted that collisions in the past have had a significant role in shaping the geological and biological history of the Earth. NEOs have become of increased interest since the 1980s because of increased awareness of the potential danger some of the

text: asteroid

text: s or

text: comet

text: s pose, and mitigations are being researched. In January 2016, NASA announced the

text: Planetary Defense Coordination Office

text: to track NEOs larger than 30 to 50 meters in diameter and coordinate an effective threat response and mitigation effort.

text: The planets of the Solar System can be divided into categories based on their composition:

text: The encounters between the ice giant and Jupiter in the jumping-Jupiter scenario often lead to the ejection of the ice giant. For this ice giant to be retained its eccentricity must be damped by dynamical friction with the planetesimal disk, raising its perihelion beyond Saturn's orbit. The planetesimal disk masses typically used in the Nice model are often insufficient for this, leaving system beginning with four giant planets with only three at the end of the instability. The ejection of the ice giant can be avoided if the disk mass is larger, but the separation of Jupiter and Saturn often grows too large and their eccentricities become too small as the larger disk is cleared. These problems led David Nesvorný of the Southwest Research Institute to propose that the Solar System began with five giant planets, with an additional Neptune-mass planet between Saturn and Uranus. Using thousands of simulations with a variety of initial conditions he found that the simulations beginning with five giant planets were ten times more likely to reproduce the current Solar System. A significant migration of Neptune into the planetesimal disk before planetary encounters begin may also be required to preserve the eccentricity of Jupiter. This migration allows a significant fraction of the disk to be removed reducing the dampening of Jupiter's eccentricity after it ejects the ice giant. A later study by Nathan Kaib and John Chambers, however, found that the observed orbital properties of the terrestrial planets are only reproduced in a few percent of the numerical simulations when one or more ice giants are ejected by Jupiter and Saturn, with only 1% of the simulations successfully producing the orbits of both the terrestrial and the giant planets.

text: The encounters between the ice giant and Jupiter in the jumping-Jupiter scenario often lead to the ejection of the ice giant. For this ice giant to be retained its eccentricity must be damped by dynamical friction with the planetesimal disk, raising its perihelion beyond Saturn's orbit. The planetesimal disk masses typically used in the Nice model are often insufficient for this, leaving system beginning with four giant planets with only three at the end of the instability. The ejection of the ice giant can be avoided if the disk mass is larger, but the separation of Jupiter and Saturn often grows too large and their eccentricities become too small as the larger disk is cleared. These problems led

text: David Nesvorný

text: of the

text: Southwest Research Institute

text: to propose that the Solar System began with five giant planets, with an additional Neptune-mass planet between Saturn and Uranus. Using thousands of simulations with a variety of initial conditions he found that the simulations beginning with five giant planets were ten times more likely to reproduce the current Solar System. A significant migration of Neptune into the planetesimal disk before planetary encounters begin may also be required to preserve the eccentricity of Jupiter. This migration allows a significant fraction of the disk to be removed reducing the dampening of Jupiter's eccentricity after it ejects the ice giant. A later study by Nathan Kaib and John Chambers, however, found that the observed orbital properties of the terrestrial planets are only reproduced in a few percent of the numerical simulations when one or more

text: ice giant

text: s are ejected by Jupiter and Saturn, with only 1% of the simulations successfully producing the orbits of both the terrestrial and the giant planets.

text: 130P/McNaught–Hughes is a periodic comet in the Solar System. It takes 6.65 years to orbit the Sun and is 4.2 km in diameter.

text: 130P/McNaught–Hughes is a

text: periodic

text: comet

text: in the

text: Solar System

text: . It takes 6.65 years to orbit the Sun and is 4.2 km in diameter.

text: In the warmer inner Solar System, planetesimals formed from rocks and metals cooked billions of years ago in the cores of massive stars.These elements constituted only 0.6% of the material in the solar nebula. That is why the terrestrial planets could not grow very large and could not exert large pull on hydrogen and helium gas. Also, the faster collisions among particles close to the Sun were more destructive on average. Even if the terrestrial planets had had hydrogen and helium, the Sun would have heated the gases and caused them to escape. Hence, solar terrestrial planets such as Mercury, Venus, Earth, and Mars are dense small worlds composed mostly from 2% of heavier elements contained in the solar nebula.

text: In the warmer inner Solar System, planetesimals formed from

text: rock

text: s and

text: metal

text: s cooked billions of years ago in the cores of massive

text: star

text: s.These elements constituted only 0.6% of the material in the

text: solar nebula

text: . That is why the terrestrial planets could not grow very large and could not exert large pull on hydrogen and helium gas. Also, the faster collisions among particles close to the Sun were more destructive on average. Even if the terrestrial planets had had

text: hydrogen

text: and

text: helium

text: , the Sun would have heated the gases and caused them to escape. Hence, solar terrestrial planets such as

text: Mercury

text: Venus

text: Earth

text: , and

text: Mars

text: are dense small worlds composed mostly from 2% of heavier elements contained in the solar nebula.

text: The word "semantic" refers to the way that a model represents the real world. The representation (literally, "re-presentation") describes particular aspects of a phenomenon or the manner of interaction among a set of phenomena. For instance, a scale model of a house or of a solar system is clearly not an actual house or an actual solar system; the aspects of an actual house or an actual solar system represented in a scale model are, only in certain limited ways, representative of the actual entity. A scale model of a house is not a house; but to someone who wants to learn about houses, analogous to a scientist who wants to understand reality, a sufficiently detailed scale model may suffice.

text: The word "

text: semantic

text: " refers to the way that a model represents the real world. The representation (literally, "re-presentation") describes particular aspects of a phenomenon or the manner of interaction among a set of phenomena. For instance, a scale model of a house or of a solar system is clearly not an actual house or an actual solar system; the aspects of an actual house or an actual solar system represented in a scale model are, only in certain limited ways, representative of the actual entity. A scale model of a house is not a house; but to someone who wants to learn about houses, analogous to a scientist who wants to understand reality, a sufficiently detailed scale model may suffice.

text: Neon's abundance in the universe is about 1 part in 750; in the Sun and presumably in the proto-solar system nebula, about 1 part in 600. The Galileo spacecraft atmospheric entry probe found that even in the upper atmosphere of Jupiter, the abundance of neon is reduced (depleted) by about a factor of 10, to a level of 1 part in 6,000 by mass. This may indicate that even the ice-planetesimals which brought neon into Jupiter from the outer solar system, formed in a region which was too warm to retain the neon atmospheric component (abundances of heavier inert gases on Jupiter are several times that found in the Sun).

text: Neon's abundance in the universe is about 1 part in 750; in the Sun and presumably in the proto-solar system nebula, about 1 part in 600. The

text: Galileo spacecraft

text: atmospheric entry probe found that even in the upper atmosphere of Jupiter, the abundance of neon is reduced (depleted) by about a factor of 10, to a level of 1 part in 6,000 by mass. This may indicate that even the ice-

text: planetesimal

text: s which brought neon into Jupiter from the outer solar system, formed in a region which was too warm to retain the neon atmospheric component (abundances of heavier inert gases on Jupiter are several times that found in the Sun).

text: Giant planets can significantly influence terrestrial planet formation. The presence of giants tends to increase eccentricities and inclinations (see Kozai mechanism) of planetesimals and embryos in the terrestrial planet region (inside 4 AU in the Solar System). If giant planets form too early, they can slow or prevent inner planet accretion. If they form near the end of the oligarchic stage, as is thought to have happened in the Solar System, they will influence the merges of planetary embryos, making them more violent. As a result, the number of terrestrial planets will decrease and they will be more massive. In addition, the size of the system will shrink, because terrestrial planets will form closer to the central star. The influence of giant planets in the Solar System, particularly that of Jupiter, is thought to have been limited because they are relatively remote from the terrestrial planets.

text: Giant planets can significantly influence

text: terrestrial planet

text: formation. The presence of giants tends to increase

text: eccentricities

text: and

text: inclinations

text: (see

text: Kozai mechanism

text: ) of planetesimals and embryos in the terrestrial planet region (inside 4 AU in the Solar System). If giant planets form too early, they can slow or prevent inner planet accretion. If they form near the end of the oligarchic stage, as is thought to have happened in the Solar System, they will influence the merges of planetary embryos, making them more violent. As a result, the number of terrestrial planets will decrease and they will be more massive. In addition, the size of the system will shrink, because terrestrial planets will form closer to the central star. The influence of giant planets in the Solar System, particularly that of

text: Jupiter

text: , is thought to have been limited because they are relatively remote from the terrestrial planets.

text: After the December 2015 Feed-in Tariff reductions were announced, many free solar panel installers have started to cease trading, or have plans to stop installing, as the returns are no longer financially viable. The change in the feed-in tariff will equate to a 64% decrease in the generation tariff for solar arrays less than 4 kW, which is the largest decrease since the scheme was started in 2010. Unusually, the feed-in tariff changes will mean that larger systems (over 10 kW) will receive higher feed in tariff rate than smaller domestic sized systems, which could result in a strong switch of the remaining free solar panel companies to exclusively providing commercial installations.

text: On the basis of models of planet formation that might include planetary migration from the inner Solar System, such as the fifth giant planet hypothesis, Batygin and Brown suggest that it may be a primordial giant planet core that was ejected from its original orbit during the nebular epoch of the Solar System's evolution.

text: On the basis of models of

text: planet formation

text: that might include

text: planetary migration

text: from the inner Solar System, such as the

text: fifth giant planet hypothesis

text: , Batygin and Brown suggest that it may be a primordial giant planet core that was ejected from its original orbit during the nebular epoch of the Solar System's evolution.

text: Missouri S&T's solar car team has met with much success. Every two years, the team constructs a single-passenger car, its top covered with solar cells, that runs exclusively on solar power. The car houses lithium ion batteries, which are much lighter than conventional lead-acid batteries. Every time the car is rebuilt, changes make it lighter and more efficient. The team regularly enters solar car races in the United States and occasionally enters international races. The car claimed first place in Sunrayce '99, first place in the 2000 Formula Sun Grand Prix, fourth place in the Australian World Solar Challenge in 2001, second place in the 2001 American Solar Challenge, and first place in the 2003 American Solar Challenge. In 2016, the team placed fourth in the American Solar Challenge after not participating for six years.

text: Missouri S&T's

text: solar car

text: team has met with much success. Every two years, the team constructs a single-passenger car, its top covered with

text: solar cells

text: , that runs exclusively on solar power. The car houses

text: lithium ion batteries

text: , which are much lighter than conventional

text: lead-acid batteries

text: . Every time the car is rebuilt, changes make it lighter and more efficient. The team regularly enters

text: solar car races

text: in the United States and occasionally enters international races. The car claimed first place in Sunrayce '99, first place in the 2000 Formula Sun Grand Prix, fourth place in the Australian World Solar Challenge in 2001, second place in the 2001

text: American Solar Challenge

text: , and first place in the 2003 American Solar Challenge. In 2016, the team

text: placed fourth in the American Solar Challenge

text: after not participating for six years.

text: Research topics of the LPI include the formation and evolution of the solar system, petrology and geochemistry of planetary materials and volatiles, planetary interiors, volcanism, tectonism, and impact cratering.  Research interests range from Mercury to Pluto and the icy moons of the solar system.

text: Research topics of the LPI include the

text: , petrology and geochemistry of planetary materials and volatiles, planetary interiors,

text: volcanism

text: , tectonism, and impact cratering.  Research interests range from

text: Mercury

text: to

text: Pluto

text: and the

text: icy moon

text: s of the solar system.

text: Using such methods, many scientists infer that liquid water once covered large areas of Mars and Venus. Water is thought to exist as liquid beneath the surface of some planetary bodies, similar to groundwater on Earth. Water vapour is sometimes considered conclusive evidence for the presence of liquid water, although atmospheric water vapour may be found to exist in many places where liquid water does not. Similar indirect evidence, however, supports the existence of liquids below the surface of several moons and dwarf planets elsewhere in the Solar System. Some are speculated to be large extraterrestrial "oceans". Liquid water is thought to be common in other planetary systems, despite the lack of conclusive evidence, and there is a growing list of extrasolar candidates for liquid water.

text: Using such methods, many scientists infer that liquid water once covered large areas of

text: Mars

text: and

text: Venus

text: . Water is thought to exist as liquid beneath the surface of some planetary bodies, similar to

text: groundwater

text: on Earth. Water vapour is sometimes considered conclusive evidence for the presence of liquid water, although atmospheric water vapour may be found to exist in many places where liquid water does not. Similar indirect evidence, however, supports the existence of liquids below the surface of several

text: moons

text: and

text: dwarf planet

text: s elsewhere in the

text: Solar System

text: . Some are speculated to be large

text: extraterrestrial "oceans"

text: . Liquid water is thought to be common in other

text: planetary system

text: s, despite the lack of conclusive evidence, and there is a growing

entity_name: List of extrasolar candidates for liquid water

text: list of extrasolar candidates for liquid water

text: Players start off on a nearly forgotten planet called "Kalebesh" in the Vega system, as a smuggler. On this planet the player will learn what things are, and get your their missions, which will eventually lead to a new planet called "Axiom". In the storyline players will get to some other planets, and also join the colonials, which are at first their enemy. After a big fight with a Mantis mother ship, they will go to a new star system, "Antares". Here players meet the Admiral, and will help him find his daughter. After another big fight, the player will gain access to another system: "Gemini", where they meet Isaac, Sara, and villagers who survived the war with the Mantis. When finally finishing the extremely hard story line players will reach "Mizar", where they meet the Baumarian Fighters. After yet another big fight players will reach their own solar system, Sol, which is now controlled by Imperials. After stealing and ancient artifact from the Emperor and once again a massive mantis ship, the player will gain entrance to Draconis, the newest system of Pirate Galaxy at the moment. Here the players meet the Methanoids, another alien race. In Draconis is the mother ship of the Mantis: the Mantis hive, where the player will defeat the Mantis Queen to complete the ancient artifact. After experiments with the artifact a wormhole will open to the new system, the Sirius Singularity. Here the next adventure begins. Untold riches and wealth await there, but only for the bravest of pilots who choose to yet again face the mantis and the rogue methanoid criminals.

text: Isotopic abundances indicate processes over the history of the Solar System. To an extent, all bodies formed from the presolar nebula. Various subsequent processes then alter elemental and isotopic ratios. The gas giants in particular have enough gravity to retain primary atmospheres, taken largely from the presolar nebula, as opposed to the later outgassing and reactions of secondary atmospheres. Differences in gas giant atmospheres compared to solar abundances then indicate some process in that planet's history. Meanwhile, gases at small planets such as Venus and Mars have isotopic differences indicating atmospheric escape processes.{argon isotope ratio planet meteorite}{neon isotope ratio meteorite}

text: Isotopic abundances indicate processes over the history of the Solar System. To an extent, all bodies formed from the presolar nebula. Various subsequent processes then alter elemental and isotopic ratios. The gas giants in particular have enough gravity to retain primary atmospheres, taken largely from the presolar nebula, as opposed to the later outgassing and reactions of secondary atmospheres. Differences in gas giant atmospheres compared to solar abundances then indicate some process in that planet's history. Meanwhile, gases at small planets such as Venus and Mars have isotopic differences indicating

text: atmospheric escape

text: processes.{argon isotope ratio planet meteorite}{neon isotope ratio meteorite}

text: In December 2015, astronomers at the Atacama Large Millimeter Array (ALMA) detected a brief series of 350 GHz pulses that they concluded must either be a series of independent sources, or a single, fast moving source. Deciding that the latter was the most likely, they calculated based on its speed that, were it bound to the Sun, the object, which they named "Gna" after a fast-moving messenger goddess in Norse mythology, would be about 12–25 AU distant and have a dwarf planet-sized diameter of 220 to 880 km. However, if it were a rogue planet not gravitationally bound to the Sun, and as far away as 4000 AU, it could be much larger. The paper was never formally accepted, and has been withdrawn until the detection is confirmed. Scientists' reactions to the notice were largely sceptical; Mike Brown commented that, "If it is true that ALMA accidentally discovered a massive outer solar system object in its tiny, tiny, tiny, field of view, that would suggest that there are something like 200,000 Earth-sized planets in the outer solar system ... Even better, I just realized that this many Earth-sized planets existing would destabilize the entire solar system and we would all die."

text: In December 2015, astronomers at the

text: Atacama Large Millimeter Array

text: (ALMA) detected a brief series of 350 GHz pulses that they concluded must either be a series of independent sources, or a single, fast moving source. Deciding that the latter was the most likely, they calculated based on its speed that, were it bound to the Sun, the object, which they named "Gna" after a

text: fast-moving messenger goddess

text: in Norse mythology, would be about 12–25 AU distant and have a

text: dwarf planet

text: -sized diameter of 220 to 880 km. However, if it were a

text: rogue planet

text: not gravitationally bound to the Sun, and as far away as 4000 AU, it could be much larger. The paper was never formally accepted, and has been withdrawn until the detection is confirmed. Scientists' reactions to the notice were largely sceptical; Mike Brown commented that, "If it is true that ALMA accidentally discovered a massive outer solar system object in its tiny, tiny, tiny, field of view, that would suggest that there are something like 200,000 Earth-sized planets in the outer solar system ... Even better, I just realized that this many Earth-sized planets existing would destabilize the entire solar system and we would all die."

text: Others argued that Newton's law should be supplemented with a velocity-dependent potential. However, this implied a conflict with Newtonian celestial dynamics. In his treatise on celestial mechanics, Laplace had shown that if the gravitational influence does not act instantaneously, then the motions of the planets themselves will not exactly conserve momentum (and consequently some of the momentum  would have to be ascribed to the mediator of the gravitational interaction, analogous to ascribing momentum to the mediator of the electromagnetic interaction.) As seen from a Newtonian point of view, if gravitational influence does propagate at a finite speed, then at all points in time a planet is attracted to a point where the Sun was some time before, and not towards the instantaneous position of the Sun. On the assumption of the classical fundamentals, Laplace had shown that if gravity would propagate at a velocity on the order of the speed of light then the solar system would be unstable, and would not exist for a long time. The observation that the solar system is old enough allowed him to put a lower limit on the speed of gravity that turned out to be many orders of magnitude faster than the speed of light. Laplace's estimate for the velocity of gravity is not correct, because in a field theory which respects the principle of relativity, the attraction of a point charge which is moving at a constant velocity is towards the extrapolated instantaneous position, not to the apparent position it seems to occupy when looked at.

text: Others argued that Newton's law should be supplemented with a velocity-dependent potential. However, this implied a conflict with Newtonian celestial dynamics. In his treatise on celestial mechanics,

text: Laplace

text: had shown that if the gravitational influence does not act instantaneously, then the motions of the planets themselves will not exactly conserve momentum (and consequently some of the momentum  would have to be ascribed to the mediator of the gravitational interaction, analogous to ascribing momentum to the mediator of the electromagnetic interaction.) As seen from a Newtonian point of view, if gravitational influence does propagate at a finite speed, then at all points in time a planet is attracted to a point where the Sun was some time before, and not towards the instantaneous position of the Sun. On the assumption of the classical fundamentals, Laplace had shown that if gravity would propagate at a velocity on the order of the speed of light then the solar system would be unstable, and would not exist for a long time. The observation that the solar system is old enough allowed him to put a lower limit on the

text: speed of gravity

text: that turned out to be many orders of magnitude faster than the speed of light. Laplace's estimate for the velocity of gravity is not correct, because in a field theory which respects the principle of relativity, the attraction of a point charge which is moving at a constant velocity is towards the extrapolated instantaneous position, not to the apparent position it seems to occupy when looked at.

text: Planets are generally divided into two main types: large low-density giant planets, and smaller rocky terrestrials. Under IAU definitions, there are eight planets in the Solar System. In order of increasing distance from the Sun, they are the four terrestrials, Mercury, Venus, Earth, and Mars, then the four giant planets, Jupiter, Saturn, Uranus, and Neptune. Six of the planets are orbited by one or more natural satellites.

text: Planets are generally divided into two main types: large low-density

text: giant planet

text: s, and smaller rocky

text: terrestrials

text: . Under IAU definitions, there are eight planets in the Solar System. In order of increasing distance from the

text: Sun

text: , they are the four terrestrials,

text: Mercury

text: Venus

text: , Earth, and

text: Mars

text: , then the four giant planets,

text: Jupiter

text: Saturn

text: Uranus

text: , and

text: Neptune

text: . Six of the planets are orbited by one or more

text: natural satellite

text: s.

text: Astronomical clocks usually represent the solar system using the geocentric model. The center of the dial is often marked with a disc or sphere representing the earth, located at the center of the solar system. The sun is often represented by a golden sphere (as it initially appeared in the Antikythera Mechanism, back in the 2nd century BC), shown rotating around the earth once a day around a 24-hour analog dial. This view accords both with daily experience and with the philosophical world view of pre-Copernican Europe.

text: Astronomical clocks usually represent the solar system using the

text: geocentric

text: model. The center of the dial is often marked with a disc or sphere representing the earth, located at the center of the solar system. The sun is often represented by a golden sphere (as it initially appeared in the

text: Antikythera Mechanism

text: , back in the 2nd century BC), shown rotating around the earth once a day around a

text: 24-hour analog dial

text: . This view accords both with daily experience and with the philosophical world view of pre-

text: Copernican

text: Europe.

text: A potentially habitable planet implies a terrestrial planet within the circumstellar habitable zone and with conditions roughly comparable to those of Earth (i.e. an Earth analog) and thus potentially favourable to Earth-like life. However, the question of what makes a planet habitable is much more complex than having a planet located at the right distance from its host star so that water can be liquid on its surface: various geophysical and geodynamical aspects, the radiation, and the host stars plasma environment can influence the evolution of planets and life, if it originated.

text: A potentially habitable planet implies a

text: terrestrial planet

text: within the circumstellar habitable zone and with conditions roughly comparable to those of Earth (i.e. an

text: Earth analog

text: ) and thus potentially favourable to Earth-like life. However, the question of what makes a planet habitable is much more complex than having a planet located at the right distance from its host star so that water can be liquid on its surface: various

text: geophysical

text: and

text: geodynamical

text: aspects, the radiation, and the host stars

text: plasma

text: environment can influence the evolution of planets and life, if it originated.

text: Newton's Principia formulated the laws of motion and universal gravitation, which dominated scientists' view of the physical universe for the next three centuries.  By deriving Kepler's laws of planetary motion from his mathematical description of gravity, and then using the same principles to account for the trajectories of comets, the tides, the precession of the equinoxes, and other phenomena, Newton removed the last doubts about the validity of the heliocentric model of the Solar System. This work also demonstrated that the motion of objects on Earth and of celestial bodies could be described by the same principles.  His prediction that Earth should be shaped as an oblate spheroid was later vindicated by the measurements of Maupertuis, La Condamine, and others, which helped convince most Continental European scientists of the superiority of Newtonian mechanics over the earlier system of Descartes.

text: Newton's Principia formulated the

text: laws of motion

text: and

text: universal gravitation

text: , which dominated scientists' view of the physical universe for the next three centuries.  By deriving

text: Kepler's laws of planetary motion

text: from his mathematical description of gravity, and then using the same principles to account for the trajectories of

text: comet

text: s, the

text: tide

text: s, the

text: precession of the equinoxes

text: , and other phenomena, Newton removed the last doubts about the validity of the

text: heliocentric

text: model of the Solar System. This work also demonstrated that the

text: motion of objects

text: on Earth and of

text: celestial

text: bodies could be described by the same principles.  His prediction that Earth should be shaped as an

text: oblate spheroid

text: was later vindicated by the measurements of

text: Maupertuis

text: La Condamine

text: , and others, which helped convince most

text: Continental Europe

text: an scientists of the superiority of Newtonian mechanics over the earlier system of

text: Descartes

text: In stars massive enough to ignite helium fusion, an analogous process occurs when the central helium is exhausted and the star collapses once again, causing helium in an outer shell to begin fusing. At the same time hydrogen may begin fusion in a shell just outside the burning helium shell. This puts the star onto the asymptotic giant branch, a second red-giant phase. The helium fusion results in the build up of a carbon–oxygen core. A star below about  will never start fusion in its degenerate carbon–oxygen core. Instead, at the end of the asymptotic-giant-branch phase the star will eject its outer layers, forming a planetary nebula with the core of the star exposed, ultimately becoming a white dwarf. The ejection of the outer mass and the creation of a planetary nebula finally ends the red-giant phase of the star's evolution. The red-giant phase typically lasts only around a billion years in total for a solar mass star, almost all of which is spent on the red-giant branch. The horizontal-branch and asymptotic-giant-branch phases proceed tens of times faster.

text: In stars massive enough to ignite

text: helium fusion

text: , an analogous process occurs when the central helium is exhausted and the star collapses once again, causing helium in an outer shell to begin fusing. At the same time hydrogen may begin fusion in a shell just outside the burning helium shell. This puts the star onto the

text: asymptotic giant branch

text: , a second red-giant phase. The helium fusion results in the build up of a carbon–oxygen core. A star below about  will never start fusion in its degenerate carbon–oxygen core. Instead, at the end of the asymptotic-giant-branch phase the star will eject its outer layers, forming a

text: planetary nebula

text: with the core of the star exposed, ultimately becoming a

text: white dwarf

text: . The ejection of the outer mass and the creation of a planetary nebula finally ends the red-giant phase of the star's evolution. The red-giant phase typically lasts only around a billion years in total for a solar mass star, almost all of which is spent on the red-giant branch. The horizontal-branch and asymptotic-giant-branch phases proceed tens of times faster.

text: A partial solar eclipse occurred on September 10, 1942. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: occurred on September 10, 1942. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: For a list of "fifth planets" in fiction, see Fictional planets of the Solar System

text: For a list of "fifth planets" in fiction, see

text: Fictional planets of the Solar System

text: Solar oscillation modes are essentially divided up into three categories, based on the restoring force that drives them: acoustic, gravity, and surface-gravity wave modes.

text: Marathon takes place in outer space in the year 2794. The player assumes the role of a nameless security officer stationed on the UESC Marathon. The Marathon has arrived in the Tau Ceti solar system and is supporting the colonization effort of the planet, Tau Ceti IV. The game starts with the player making his way to the Marathon on the shuttle Mirata when an alien ship appears and attacks the system. He survives by ejecting seconds before the explosion of the Mirata, and hours later, his officer's escape pod then reaches one of the Marathon docking bays.

text: Marathon takes place in outer space in the year 2794. The player assumes the role of a nameless security officer stationed on the UESC Marathon. The Marathon has arrived in the

text: Tau Ceti

text: solar system and is supporting the colonization effort of the planet, Tau Ceti IV. The game starts with the player making his way to the Marathon on the shuttle Mirata when an alien ship appears and attacks the system. He survives by ejecting seconds before the explosion of the Mirata, and hours later, his officer's escape pod then reaches one of the Marathon docking bays.

text: Recent discoveries have uncovered planets that are thought to be similar in size or mass to  Earth. While there is no universal definition of "Earth-sized", ranges are typically defined by mass. The lower range used in many definitions of the super-Earth class is 1.9 Earth masses, likewise, sub-Earths range up to the size of Venus (~0.815 Earth masses). An upper limit of 1.5 Earth radii is also considered, given that above  the average planet density rapidly decreases with increasing radius, indicating that these planets have a large fraction of volatiles by volume overlying a rocky core. Solar analogs and solar twins are stars that resemble the Sun. To date no solar twin with an exact match as that of the Sun has been found, however, there are some stars that are nearly identical to the Sun, and are such considered solar twins. An exact solar twin would be a G2V star with a 5,778 K temperature, be 4.6 billion years old, with the correct metallicity and a 0.1% solar luminosity variation. Stars with an age of 4.6 billion years are at the most stable state. Proper metallicity and size are also very important to low luminosity variation.

text: Recent discoveries have uncovered planets that are thought to be similar in size or mass to  Earth. While there is no universal definition of "Earth-sized", ranges are typically defined by mass. The lower range used in many definitions of the super-Earth class is 1.9 Earth masses, likewise, sub-Earths range up to the size of Venus (~0.815 Earth masses). An upper limit of 1.5 Earth radii is also considered, given that above  the average planet density rapidly decreases with increasing radius, indicating that these planets have a large fraction of volatiles by volume overlying a rocky core.

text: Solar analog

text: s and

text: solar twins

text: are stars that resemble the Sun. To date no solar twin with an exact match as that of the Sun has been found, however, there are some stars that are nearly identical to the Sun, and are such considered solar twins. An exact solar twin would be a G2V star with a 5,778 K temperature, be 4.6 billion years old, with the correct metallicity and a 0.1%

text: solar luminosity

text: variation. Stars with an age of 4.6 billion years are at the most stable state. Proper metallicity and size are also very important to low luminosity variation.

text: Unfortunately, it is impossible to obtain the complete orbit of a spectroscopic binary unless it is also a visual or an eclipsing binary, so from these objects only a determination of the joint product of mass and the sine of the angle of inclination relative to the line of sight is possible. In the case of eclipsing binaries which are also spectroscopic binaries, it is possible to find a complete solution for the specifications (mass, density, size, luminosity, and approximate shape) of both members of the system.

text: Unfortunately, it is impossible to obtain the complete orbit of a spectroscopic binary unless it is also a visual or an eclipsing binary, so from these objects only a determination of the joint product of mass and the

text: sine

text: of the angle of inclination relative to the line of sight is possible. In the case of eclipsing binaries which are also spectroscopic binaries, it is possible to find a complete solution for the specifications (mass,

text: density

text: , size,

text: luminosity

text: , and approximate shape) of both members of the system.

text: Work with colleague Gerald Sussman using a specially-built computer demonstrated that the solar system as a whole is chaotic on a timescale of about four million years, confirming results from Jacques Laskar. This work was responsible for "shattering the long-held view of the clockwork motion of the planets."

text: Work with colleague

text: Gerald Sussman

text: using a specially-built computer demonstrated that the solar system as a whole is chaotic on a timescale of about four million years, confirming results from Jacques Laskar. This work was responsible for "shattering the long-held view of the clockwork motion of the planets."

text:
||5 January, 01:45 GMT||Aerobee 200A||White Sands||NASA||||NASA||Sub-orbital||Aeronomy/Ultraviolet astronomy||5 January 1974||Successful||Apogee: |-||8 January, 01:40 GMT||Aerobee 200A||White Sands||NASA||||NASA/NRL||Sub-orbital||Aeronomy/Ultraviolet astronomy||8 January 1974||Successful||Apogee: |-||12 January 19:12 GMT||Skylark||El Arenosillo||DFVLR||H-GR-58||DLR||Sub-orbital||Astronomy||12 January 1974||Successful||Apogee: |-||12 January||R-36||LC-162/36, Baikonur||RVSN||DKh||RVSN||Sub-orbital||ICBM test||12 January 1974||Successful||Apogee: |-||15 January 20:00 GMT||Black Brant VC||LC-36, White Sands||NASA||||NASA||Sub-orbital||Solar research||15 January 1974||Successful||Apogee: |-||16 January, 02:00 GMT||Kappa 9M||Kagoshima||ISAS||||ISAS||Sub-orbital||Ionosphere and Solar research||16 January 1974||Successful||Apogee: |-||16 January 17:40 GMT||Nike Apache||Wallops Island||NASA||||NASA||Sub-orbital||Aeronomy||16 January 1974||Successful||Apogee: |-||16 January 18:13 GMT||Super Arcas||Wallops Island||NASA||||NASA||Sub-orbital||Ionosphere research||16 January 1974||Successful||Apogee: |-||16 January||Aerobee 200A||White Sands||NASA||||NASA||Sub-orbital||Solar research||16 January 1974||Successful||Apogee: |-||17 January, 02:37 GMT||Nike Tomahawk||Poker Flat||NASA||||NASA||Sub-orbital||Plasma research||17 January 1974||Successful||Apogee: |-||17 January, 02:37 GMT||Kosmos-3M||LC-132/2, Plesetsk||VKS||Kosmos 628 (Tsiklon)||MO SSSR||LEO||Navigation||Still in orbit||Successful|||-||19 January, 01:38 GMT||Delta 2313||LC-17B, CCAFS||||Skynet 2A||UK Ministry of Defence||Intended: GSO
Achieved: LEO||Comms||25 January 1974||Failure||Placed in incorrect orbit due to carrier rocket malfunction|-||19 January 11:34 GMT||Skua||El Arenosillo||RAE||||RAE||Sub-orbital||Ionosphere research||19 January 1974||Successful||Apogee: |-||19 January||Eridan||ALFS, Kourou||||||||Sub-orbital||Missile test||19 January 1974||Successful||Apogee: |-||20 January||R-36M||LC-103, Baikonur||RVSN||POR||RVSN||Sub-orbital||ICBM test||20 January 1974||Successful||Apogee: |-||21 January, 02:39 GMT||Nike Tomahawk||Poker Flat||NASA||||NASA||Sub-orbital||Plasma research||21 January 1974||Successful||Apogee: |-||21 January 11:30 GMT||Skua 4||El Arenosillo||RAE||||RAE||Sub-orbital||Ionosphere research||21 January 1974||Successful||Apogee: |-||22 January, 02:41 GMT||Nike Tomahawk||Poker Flat||NASA||||NASA||Sub-orbital||Plasma research||22 January 1974||Successful||Apogee: |-||22 January 11:00 GMT||Lambda-3H||Area L, Kagoshima||ISAS||||ISAS||Sub-orbital||X-ray astronomy||22 January 1974||Successful||Apogee: |-||8 January 16:45 GMT||Aerobee 200A||White Sands||NASA||||NASA||Sub-orbital||Solar research||22 January 1974||Successful||Reached |-||22 January||Minuteman I||LF-06, Vandenberg AFB||USAF||||USAF||Sub-orbital||ICBM test||22 January 1974||Successful||Apogee: |-||23 January 11:30 GMT||Skua||El Arenosillo||RAE||||RAE||Sub-orbital||Ionosphere research||23 January 1974||Successful||Apogee: |-||23 January 12:50 GMT||Black Brant VB||Fort Churchill||NRCC||||NRCC||Sub-orbital||Aeronomy/Ionosphere/Aurora research||23 January 1974||Successful||Apogee: |-||24 January 15:00 GMT||Voskhod||Plesetsk||||Kosmos 629 (Zenit-2M)||MOM||LEO||Recon||5 February 1974||Successful|||-||25 January 11:30 GMT||Skua||El Arenosillo||RAE||||RAE||Sub-orbital||Ionosphere research||25 January 1974||Successful||Apogee: |-||25 January||UR-100N||Baikonur Cosmodrome||RVSN||||RVSN||Sub-orbital||ICBM test||25 January 1974||Successful||Apogee: |-||26 January||Minuteman III||LF-25, Vandenberg AFB||USAF||GT-24GB-1||USAF||Sub-orbital||ICBM test||26 January 1974||Successful||Apogee: |-||26 January||UR-100N||Baikonur Cosmodrome||RVSN||||RVSN||Sub-orbital||ICBM test||26 January 1974||Successful||Apogee: |-||27 January 19:08 GMT||Nike Tomahawk||Andøya||NASA||Ferdinand 35
(Polar 3)||NDRE||Sub-orbital||Aurora research||27 January 1974||Successful||Apogee: |-||30 January 11:00 GMT||Voskhod||Plesetsk||||Kosmos 630 (Zenit-4MK)||MOM||LEO||Recon||13 February 1974||Successful|||-||30 January||SSBS||BLB, Biscarosse||DMA||||DMA||Sub-orbital||Missile test||30 January 1974||Successful||Apogee: |-||January||Vertikal' K65UP||LC-107, Kapustin Yar||RVSN||||RVSN||Sub-orbital||Ionosphere/Solar research||January 1974||Successful||Apogee: |-||January||Athena||Wallops Island||Sandia||||USAF||Sub-orbital||Re-entry vehicle test||January 1974||Successful||Apogee: |-||1 February, 06:30 GMT||JCR||Area T, Tanegashima||NASDA||||NASDA||Sub-orbital||Test flight||1 February 1974||Successful||Apogee: |-||4 February 14:40 GMT||Skylark 6AC||LA-2SL, Woomera||BAC||||BAC||Sub-orbital||Astronomy||4 February 1974||Successful||Apogee: |-||4 February||MR-UR-100||LC-177, Baikonur||RVSN||||RVSN||Sub-orbital||ICBM test||4 February 1974||Successful||Apogee: |-||6 February, 00:34 GMT||Kosmos-3M||LC-132/2, Plesetsk||VKS||Kosmos 631 (Tselina-O)||MO SSSR||LEO||ELINT||3 October 1980||Successful|||-||6 February 22:48 GMT||Black Brant IVB||Andoya||DLR||||DFVLR||Sub-orbital||Aurora research||6 February 1974||Successful||Apogee: |-||6 February||Polaris A3||Submarine, WTR||US Navy||||US Navy||Sub-orbital||SLBM test||6 February 1974||Successful||Apogee: |-||6 February||Polaris A3||Submarine, WTR||US Navy||||US Navy||Sub-orbital||SLBM test||6 February 1974||Successful||Apogee: |-||6 February||Polaris A3||Submarine, WTR||US Navy||||US Navy||Sub-orbital||SLBM test||6 February 1974||Successful||Apogee: |-||6 February||Polaris A3||Submarine, WTR||US Navy||||US Navy||Sub-orbital||SLBM test||6 February 1974||Successful||Apogee: |-||6 February||Polaris A3||Submarine, WTR||US Navy||||US Navy||Sub-orbital||SLBM test||6 February 1974||Successful||Apogee: |-||9 February, 02:10 GMT||Aerobee 200A||White Sands||NASA||||NASA||Sub-orbital||Astronomy||9 February 1974||Successful||Apogee: |-||9 February, 06:30 GMT||LS-C||Area T, Tanegashima||NASDA||LE-3||NASDA||Sub-orbital||Test flight||9 February 1974||Successful||Apogee: |-|rowspan=2|11 February 13:48 GMT|rowspan=2|Titan IIIE|rowspan=2|LC-41, CCAFS|rowspan=2|||Boilerplate Viking||NASA||Intended: GSO||Test carrier rocket|rowspan=2|12 February 1974|rowspan=2|Failure|rowspan=2|Upper stage turbopump malfunction|-||SPHINX||NASA||Intended: GSO||Plasma research|-||3 July||Soyuz (11A511)||LC-1/5, Baikonur||||Soyuz 14||||LEO, docked to Salyut 3||Manned orbital flight||19 July 1974||Successful|||-||16 July||Scout||Western Space and Missile Center at Vandenberg AFB||NASA||Aeros 2||NASA||||||||Successful|||-||26 August||Soyuz (11A511)||LC-1/5, Baikonur||||Soyuz 15||||LEO

text: ||5 January, 01:45

text: GMT

text: Aerobee 200A

text: White Sands

text: NASA

text: NASA

text: Sub-orbital

text: Aeronomy

text: Ultraviolet astronomy

text: ||5 January 1974||Successful||

text: Apogee

text: : |-||8 January, 01:40

text: GMT

text: Aerobee 200A

text: White Sands

text: NASA

text: NASA

text: NRL

text: Sub-orbital

text: Aeronomy

text: Ultraviolet astronomy

text: ||8 January 1974||Successful||

text: Apogee

text: : |-||12 January 19:12

text: GMT

text: Skylark

text: El Arenosillo

text: DFVLR

text: DLR

text: Sub-orbital

text: Astronomy

text: ||12 January 1974||Successful||

text: Apogee

text: : |-||12 January||

text: Baikonur

text: RVSN

text: ||DKh||

text: RVSN

text: Sub-orbital

text: ICBM

text: test||12 January 1974||Successful||

text: Apogee

text: : |-||15 January 20:00

text: GMT

text: Black Brant VC

text: White Sands

text: NASA

text: NASA

text: Sub-orbital

text: ||Solar research||15 January 1974||Successful||

text: Apogee

text: : |-||16 January, 02:00

text: GMT

text: Kappa 9M

text: Kagoshima

entity_name: Institute of Space and Astronautical Science

text: ISAS

text: ISAS

text: Sub-orbital

text: Ionosphere

text: and Solar research||16 January 1974||Successful||

text: Apogee

text: : |-||16 January 17:40

text: GMT

text: Nike Apache

text: Wallops Island

text: NASA

text: NASA

text: Sub-orbital

text: Aeronomy

text: ||16 January 1974||Successful||

text: Apogee

text: : |-||16 January 18:13

text: GMT

text: Super Arcas

text: Wallops Island

text: NASA

text: NASA

text: Sub-orbital

text: Ionosphere

text: research||16 January 1974||Successful||

text: Apogee

text: : |-||16 January||

text: Aerobee 200A

text: White Sands

text: NASA

text: NASA

text: Sub-orbital

text: ||Solar research||16 January 1974||Successful||

text: Apogee

text: : |-||17 January, 02:37

text: GMT

text: Nike Tomahawk

text: Poker Flat

text: NASA

text: NASA

text: Sub-orbital

text: Plasma

text: research||17 January 1974||Successful||

text: Apogee

text: : |-||17 January, 02:37

text: GMT

text: Plesetsk

text: VKS

text: Kosmos 628

text: Tsiklon

text: MO SSSR

text: LEO

text: Navigation

text: ||Still in orbit||Successful|||-||19 January, 01:38

text: GMT

text: Delta 2313

entity_name: Cape Canaveral Air Force Station Space Launch Complex 17

text: CCAFS

text: Skynet 2A

text: UK Ministry of Defence

text: ||Intended:

text: GSO

text: <br>Achieved:

text: LEO

text: Comms

text: ||25 January 1974||Failure||Placed in incorrect orbit due to carrier rocket malfunction|-||19 January 11:34

text: GMT

text: Skua

text: El Arenosillo

text: RAE

text: RAE

text: Sub-orbital

text: Ionosphere

text: research||19 January 1974||Successful||

text: Apogee

text: : |-||19 January||

text: Eridan

text: ||ALFS,

text: Kourou

text: Sub-orbital

text: ||Missile test||19 January 1974||Successful||

text: Apogee

text: : |-||20 January||

text: Baikonur

text: RVSN

text: ||POR||

text: RVSN

text: Sub-orbital

text: ICBM

text: test||20 January 1974||Successful||

text: Apogee

text: : |-||21 January, 02:39

text: GMT

text: Nike Tomahawk

text: Poker Flat

text: NASA

text: NASA

text: Sub-orbital

text: Plasma

text: research||21 January 1974||Successful||

text: Apogee

text: : |-||21 January 11:30

text: GMT

text: Skua 4

text: El Arenosillo

text: RAE

text: RAE

text: Sub-orbital

text: Ionosphere

text: research||21 January 1974||Successful||

text: Apogee

text: : |-||22 January, 02:41

text: GMT

text: Nike Tomahawk

text: Poker Flat

text: NASA

text: NASA

text: Sub-orbital

text: Plasma

text: research||22 January 1974||Successful||

text: Apogee

text: : |-||22 January 11:00

text: GMT

text: ||Area L,

text: Kagoshima

text: ISAS

text: ISAS

text: Sub-orbital

text: X-ray astronomy

text: ||22 January 1974||Successful||

text: Apogee

text: : |-||8 January 16:45

text: GMT

text: Aerobee 200A

text: White Sands

text: NASA

text: NASA

text: Sub-orbital

text: ||Solar research||22 January 1974||Successful||Reached |-||22 January||

text: Minuteman I

text: Vandenberg AFB

text: USAF

text: USAF

text: Sub-orbital

text: ICBM

text: test||22 January 1974||Successful||

text: Apogee

text: : |-||23 January 11:30

text: GMT

text: Skua

text: El Arenosillo

text: RAE

text: RAE

text: Sub-orbital

text: Ionosphere

text: research||23 January 1974||Successful||

text: Apogee

text: : |-||23 January 12:50

text: GMT

text: Black Brant VB

text: Fort Churchill

entity_name: National Republican Congressional Committee

text: NRCC

text: NRCC

text: Sub-orbital

text: Aeronomy

text: Ionosphere

text: Aurora

text: research||23 January 1974||Successful||

text: Apogee

text: : |-||24 January 15:00

text: GMT

text: Voskhod

text: Plesetsk

text: Kosmos 629

text: MOM

text: LEO

text: Recon

text: ||5 February 1974||Successful|||-||25 January 11:30

text: GMT

text: Skua

text: El Arenosillo

text: RAE

text: RAE

text: Sub-orbital

text: Ionosphere

text: research||25 January 1974||Successful||

text: Apogee

text: : |-||25 January||

text: Baikonur Cosmodrome

text: RVSN

text: RVSN

text: Sub-orbital

text: ICBM

text: test||25 January 1974||Successful||

text: Apogee

text: : |-||26 January||

text: Minuteman III

text: Vandenberg AFB

text: USAF

text: USAF

text: Sub-orbital

text: ICBM

text: test||26 January 1974||Successful||

text: Apogee

text: : |-||26 January||

text: Baikonur Cosmodrome

text: RVSN

text: RVSN

text: Sub-orbital

text: ICBM

text: test||26 January 1974||Successful||

text: Apogee

text: : |-||27 January 19:08

text: GMT

text: Nike Tomahawk

text: Andøya

text: NASA

text: ||Ferdinand 35<br>(Polar 3)||

entity_name: Norwegian Defence Research Establishment

text: NDRE

text: Sub-orbital

text: Aurora

text: research||27 January 1974||Successful||

text: Apogee

text: : |-||30 January 11:00

text: GMT

text: Voskhod

text: Plesetsk

text: Kosmos 630

text: MOM

text: LEO

text: Recon

text: ||13 February 1974||Successful|||-||30 January||

text: SSBS

text: ||BLB,

text: Biscarosse

text: DMA

text: DMA

text: Sub-orbital

text: ||Missile test||30 January 1974||Successful||

text: Apogee

text: : |-||January||

text: Vertikal' K65UP

text: Kapustin Yar

text: RVSN

text: RVSN

text: Sub-orbital

text: Ionosphere

text: /Solar research||January 1974||Successful||

text: Apogee

text: : |-||January||

text: Athena

text: Wallops Island

text: Sandia

text: USAF

text: Sub-orbital

text: Re-entry vehicle

text: test||January 1974||Successful||

text: Apogee

text: : |-||1 February, 06:30

text: GMT

text: JCR

text: ||Area T,

text: Tanegashima

entity_name: National Space Development Agency of Japan

text: NASDA

text: NASDA

text: Sub-orbital

text: ||Test flight||1 February 1974||Successful||

text: Apogee

text: : |-||4 February 14:40

text: GMT

text: Skylark 6AC

text: Woomera

text: BAC

text: BAC

text: Sub-orbital

text: Astronomy

text: ||4 February 1974||Successful||

text: Apogee

text: : |-||4 February||

text: Baikonur

text: RVSN

text: RVSN

text: Sub-orbital

text: ICBM

text: test||4 February 1974||Successful||

text: Apogee

text: : |-||6 February, 00:34

text: GMT

text: Plesetsk

text: VKS

text: Kosmos 631

text: Tselina-O

text: MO SSSR

text: LEO

text: ELINT

text: ||3 October 1980||Successful|||-||6 February 22:48

text: GMT

text: Black Brant IVB

text: Andoya

text: DLR

text: DFVLR

text: Sub-orbital

text: Aurora

text: research||6 February 1974||Successful||

text: Apogee

text: : |-||6 February||

text: Polaris A3

text: Submarine

text: WTR

text: US Navy

text: US Navy

text: Sub-orbital

text: SLBM

text: test||6 February 1974||Successful||

text: Apogee

text: : |-||6 February||

text: Polaris A3

text: Submarine

text: WTR

text: US Navy

text: US Navy

text: Sub-orbital

text: SLBM

text: test||6 February 1974||Successful||

text: Apogee

text: : |-||6 February||

text: Polaris A3

text: Submarine

text: WTR

text: US Navy

text: US Navy

text: Sub-orbital

text: SLBM

text: test||6 February 1974||Successful||

text: Apogee

text: : |-||6 February||

text: Polaris A3

text: Submarine

text: WTR

text: US Navy

text: US Navy

text: Sub-orbital

text: SLBM

text: test||6 February 1974||Successful||

text: Apogee

text: : |-||6 February||

text: Polaris A3

text: Submarine

text: WTR

text: US Navy

text: US Navy

text: Sub-orbital

text: SLBM

text: test||6 February 1974||Successful||

text: Apogee

text: : |-||9 February, 02:10

text: GMT

text: Aerobee 200A

text: White Sands

text: NASA

text: NASA

text: Sub-orbital

text: Astronomy

text: ||9 February 1974||Successful||

text: Apogee

text: : |-||9 February, 06:30

text: GMT

text: LS-C

text: ||Area T,

text: Tanegashima

text: NASDA

text: NASDA

text: Sub-orbital

text: ||Test flight||9 February 1974||Successful||

text: Apogee

text: : |-|rowspan=2|11 February 13:48

text: GMT

text: Titan III

entity_name: Cape Canaveral Air Force Station Space Launch Complex 41

text: CCAFS

text: Boilerplate

text: Viking

text: NASA

text: ||Intended:

text: GSO

text: ||Test carrier rocket|rowspan=2|12 February 1974|rowspan=2|Failure|rowspan=2|Upper stage turbopump malfunction|-||

text: SPHINX

text: NASA

text: ||Intended:

text: GSO

text: ||Plasma research|-||3 July||

text: Soyuz

text: Baikonur

text: Soyuz 14

text: LEO

text: , docked to

text: Salyut 3

text: ||Manned orbital flight||19 July 1974||Successful|||-||16 July||

text: Scout

text: Western Space and Missile Center

text: at

text: Vandenberg AFB

text: NASA

text: Aeros 2

text: NASA

text: ||||||||Successful|||-||26 August||

text: Soyuz

text: Baikonur

text: Soyuz 15

text: LEO

text: HD 216770 b is an extrasolar planet orbiting the star HD 216770. It has a mass about two thirds that of Jupiter, largest planet in the Solar System. But unlike the gas giants in the Solar System, it orbits in a very eccentric orbit around the star. The mean distance from the star is slightly larger than Mercury's, and it completes one orbit around the star in every 118 days.

text: HD 216770 b is an

text: extrasolar planet

text: orbiting the star

text: HD 216770

text: . It has a mass about two thirds that of

text: Jupiter

text: , largest planet in the

text: Solar System

text: . But unlike the

text: gas giant

text: s in the Solar System, it orbits in a very

text: eccentric

text: orbit around the star. The mean distance from the star is slightly larger than

text: Mercury's

text: , and it completes one orbit around the star in every 118

text: day

text: s.

text: Data collected on the orbital eccentricities of extrasolar planets has surprised most researchers: 90% have an orbital eccentricity greater than that found within the Solar System, and the average is fully 0.25. This means that the vast majority of planets have highly eccentric orbits and of these, even if their average distance from their star is deemed to be within the HZ, they nonetheless would be spending only a small portion of their time within the zone.

text: Gliese 876 b is in a 1:2:4 Laplace resonance with the inner planet Gliese 876 c and the outer planet Gliese 876 e: in the time it takes planet e to complete one orbit, planet b completes two and planet c completes four. This is the second known example of a Laplace resonance, the first being Jupiter's moons Io, Europa and Ganymede. As a result, the orbital elements of the planets change fairly rapidly as they dynamically interact with one another. The planet's orbit has a low eccentricity, similar to the planets in the Solar System. The semimajor axis of the orbit is only 0.208 AU, less than that of Mercury in the Solar System. However Gliese 876 is such a faint star that this puts it in the outer part of the habitable zone.

text: Gliese 876 b is in a 1:2:4

text: Laplace resonance

text: with the inner planet

text: Gliese 876 c

text: and the outer planet

text: Gliese 876 e

text: : in the time it takes planet e to complete one orbit, planet b completes two and planet c completes four. This is the second known example of a Laplace resonance, the first being

text: Jupiter

text: 's

text: moons

text: Io

text: Europa

text: and

text: Ganymede

text: . As a result, the

text: orbital elements

text: of the planets change fairly rapidly as they dynamically interact with one another. The planet's orbit has a low

text: eccentricity

text: , similar to the planets in the

text: Solar System

text: . The

text: semimajor axis

text: of the orbit is only 0.208

text: AU

text: , less than that of

text: Mercury

text: in the Solar System. However Gliese 876 is such a faint star that this puts it in the outer part of the

text: habitable zone

text: Solar power in the United States includes utility-scale solar power plants as well as local distributed generation, mostly from rooftop photovoltaics. As of the end of 2015, the U.S. has 25 gigawatts (GW) of installed photovoltaic capacity with an additional 1.8 GW of concentrated solar power. In the twelve months through September 2016, utility scale solar power generated 33.3 terawatt-hours (TWh), 0.82% of total U.S. electricity. During the same time period total solar generation, including estimated distributed solar photovoltaic generation, was 51.7 TWh, 1.27 % of total U.S. electricity. In terms of total installed capacity, by year end 2015 the USA ranked 4th in the world behind 1.China 2.Germany 3.Japan and ahead of 5.Italy and 6.UK. In 2015, 30% of all new electricity generation capacity in the country came from solar. By 2015, solar employment had overtaken oil and gas as well as coal employment in the U.S.

text: Solar power in the United States includes utility-scale

text: solar power plant

text: s as well as local

text: distributed generation

text: , mostly from rooftop

text: photovoltaics

text: . As of the end of 2015, the U.S. has 25

text: gigawatt

text: s (GW) of installed photovoltaic capacity with an additional 1.8 GW of

text: concentrated solar power

text: . In the twelve months through September 2016, utility scale solar power generated 33.3

text: terawatt-hour

text: s (TWh), 0.82% of total U.S. electricity. During the same time period total solar generation, including estimated distributed solar photovoltaic generation, was 51.7 TWh, 1.27 % of total U.S. electricity. In terms of total installed capacity, by year end 2015 the USA ranked 4th in the world behind 1.

text: China

text: Germany

text: Japan

text: and ahead of 5.

text: Italy

text: and 6.

text: UK

text: . In 2015, 30% of all new electricity generation capacity in the country came from solar. By 2015, solar employment had overtaken oil and gas as well as coal employment in the U.S.

text: Marcy and his team confirmed Michel Mayor and Didier Queloz's discovery of the first extrasolar planet orbiting a Sun-like star—51 Pegasi b. Two months later, Marcy and his team followed this confirmation with the announcement of the discovery of two additional planets around 47 Ursa Majoris and 70 Virginis. Other achievements include discovering the first multiple planet system around a star similar to our own (Upsilon Andromedae), the first transiting planet around another star, simultaneously with David Charbonneau and Timothy Brown (HD209458b), the first extrasolar planet orbiting beyond 5 AU (55 Cancri d), and the first Neptune-sized planets (Gliese 436b and 55 Cancri e). Marcy was a Co-Investigator of the NASA Kepler mission that discovered over 4000 exoplanets, most being smaller than 4 times the size of Earth.  His team, led by Erik Petigura and Andrew Howard, showed that approximately 20% of Sun-like stars have a planet of 1–2 times the size of Earth and receive incident stellar light within a factor of 4 of the light the Earth receives from the Sun, making them warm planets, many of which accommodate liquid water.

text: Marcy and his team confirmed

text: Michel Mayor

text: and

text: Didier Queloz

text: 's discovery of the first extrasolar planet orbiting a Sun-like star—

text: 51 Pegasi b

text: . Two months later, Marcy and his team followed this confirmation with the announcement of the discovery of two additional planets around 47 Ursa Majoris and 70 Virginis. Other achievements include discovering the first multiple planet system around a star similar to our own (

text: Upsilon Andromedae

text: ), the first

text: transiting

text: planet around another star, simultaneously with

text: David Charbonneau

text: and Timothy Brown (

text: ), the first extrasolar planet orbiting beyond 5

text: AU

text: 55 Cancri d

text: ), and the first Neptune-sized planets (

text: Gliese 436b

text: and

text: 55 Cancri e

text: ). Marcy was a Co-Investigator of the NASA Kepler mission that discovered over 4000 exoplanets, most being smaller than 4 times the size of Earth.  His team, led by Erik Petigura and Andrew Howard, showed that approximately 20% of Sun-like stars have a planet of 1–2 times the size of Earth and receive incident stellar light within a factor of 4 of the light the Earth receives from the Sun, making them warm planets, many of which accommodate liquid water.

text: The inner Solar System has been made the goal of at least four unmanned programs. The first was Mariner in the 1960s and '70s, which made multiple visits to Venus and Mars and one to Mercury. Probes launched under the Mariner program were also the first to make a planetary flyby (Mariner 2), to take the first pictures from another planet (Mariner 4), the first planetary orbiter (Mariner 9), and the first to make a gravity assist maneuver (Mariner 10). This is a technique where the satellite takes advantage of the gravity and velocity of planets to reach its destination.

text: The

text: inner Solar System

text: has been made the goal of at least four unmanned programs. The first was

text: Mariner

text: in the 1960s and '70s, which made multiple visits to

text: Venus

text: and

text: Mars

text: and one to

text: Mercury

text: . Probes launched under the Mariner program were also the first to make a planetary flyby (

text: Mariner 2

text: ), to take the first pictures from another planet (

text: Mariner 4

text: ), the first planetary orbiter (

text: Mariner 9

text: ), and the first to make a

text: gravity assist

text: maneuver (

text: Mariner 10

text: ). This is a technique where the satellite takes advantage of the gravity and velocity of planets to reach its destination.

text: A third part of the planet finding mission was the search for Jupiter-mass planets around young stars. The survey would have helped scientists understand more about solar system formation, including the occurrence of hot Jupiters. This portion of the planet hunt is designed to study systems with one or more Jupiter mass planets before the system has reached long term equilibrium. Planet hunting techniques using a star's radial velocity cannot measure the regular, tiny to-and-fro wobble motions induced by planets against the strong atmospheric activity of a youthful star. It is through the techniques pioneered by Albert A. Michelson that the SIM will be able to execute its three primary planet-finding missions.

text: A third part of the planet finding mission was the search for

text: Jupiter

text: -mass planets around young stars. The survey would have helped scientists understand more about solar system formation, including the occurrence of

text: hot Jupiters

text: . This portion of the planet hunt is designed to study systems with one or more Jupiter mass planets before the system has reached long term equilibrium. Planet hunting techniques using a star's radial velocity cannot measure the regular, tiny to-and-fro wobble motions induced by planets against the strong atmospheric activity of a youthful star. It is through the techniques pioneered by

text: Albert A. Michelson

text: that the SIM will be able to execute its three primary planet-finding missions.

text: The region of a planetary system adjacent to the giant planets will be influenced in a different way. In such a region, eccentricities of embryos may become so large that the embryos pass close to a giant planet, which may cause them to be ejected from the system. If all embryos are removed, then no planets will form in this region. An additional consequence is that a huge number of small planetesimals will remain, because giant planets are incapable of clearing them all out without the help of embryos. The total mass of remaining planetesimals will be small, because cumulative action of the embryos before their ejection and giant planets is still strong enough to remove 99% of the small bodies. Such a region will eventually evolve into an asteroid belt, which is a full analog of the asteroid belt in the Solar System, located from 2 to 4 AU from the Sun.

text: The region of a planetary system adjacent to the giant planets will be influenced in a different way. In such a region, eccentricities of embryos may become so large that the embryos pass close to a giant planet, which may cause them to be ejected from the system. If all embryos are removed, then no planets will form in this region. An additional consequence is that a huge number of small planetesimals will remain, because giant planets are incapable of clearing them all out without the help of embryos. The total mass of remaining planetesimals will be small, because cumulative action of the embryos before their ejection and giant planets is still strong enough to remove 99% of the small bodies. Such a region will eventually evolve into an

text: asteroid belt

text: , which is a full analog of the asteroid belt in the Solar System, located from 2 to 4 AU from the Sun.

text: Meteorites are one of the most important tools that cosmochemists have for studying the chemical nature of the Solar System. Many meteorites come from material that is as old as the Solar System itself, and thus provide scientists with a record from the early solar nebula. Carbonaceous chondrites are especially primitive; that is they have retained many of their chemical properties since their formation 4.56 billion years ago, and are therefore a major focus of cosmochemical investigations.

text: Meteorite

text: s are one of the most important tools that cosmochemists have for studying the chemical nature of the Solar System. Many meteorites come from material that is as old as the Solar System itself, and thus provide scientists with a record from the early

text: solar nebula

text: Carbonaceous chondrite

text: s are especially primitive; that is they have retained many of their chemical properties since their formation 4.56 billion years ago, and are therefore a major focus of cosmochemical investigations.

text: A partial solar eclipse will occur on January 6, 2019. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: will occur on January 6, 2019. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: The construction of a full, high-precision Solar System ephemeris is an onerous task. It is possible (and somewhat simpler) to construct partial ephemerides which only concern the planets (or dwarf planets, satellites, asteroids) of interest by "fixing" the motion of the other planets in the model. The two methods are not strictly equivalent, especially when it comes to assigning uncertainties to the results: however, the "best" estimates – at least in terms of quoted uncertainties in the result – for the masses of minor planets and asteroids usually come from partial ephemerides.

text: Running dynamical models of the Solar System with different initial conditions for the simulated length of the history of the Solar System will produce the various populations of objects within the Solar System. As the initial conditions of the model are allowed to vary, each population will be more or less numerous, and will have particular orbital properties. Proving a model of the evolution of the early Solar System is difficult, since the evolution cannot be directly observed. However, the success of any dynamical model can be judged by comparing the population predictions from the simulations to astronomical observations of these populations. At the present time, computer models of the Solar System that are begun with the initial conditions of the Nice scenario best match many aspects of the observed Solar System.

text: Running dynamical models of the Solar System with different initial conditions for the simulated length of the history of the Solar System will produce the various populations of objects within the Solar System. As the initial conditions of the model are allowed to vary, each population will be more or less numerous, and will have particular orbital properties.

text: Proving

text: a model of the evolution of the early Solar System is difficult, since the evolution cannot be directly observed. However, the success of any dynamical model can be judged by comparing the population predictions from the simulations to astronomical observations of these populations. At the present time, computer models of the Solar System that are begun with the initial conditions of the Nice scenario best match many aspects of the observed Solar System.

text: A partial solar eclipse will occur on April 21, 2069. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: will occur on April 21, 2069. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: At the end of the planetary formation epoch the inner Solar System was populated by 50–100 Moon- to Mars-sized planetary embryos. Further growth was possible only because these bodies collided and merged, which took less than 100 million years. These objects would have gravitationally interacted with one another, tugging at each other's orbits until they collided, growing larger until the four terrestrial planets we know today took shape. One such giant collision is thought to have formed the Moon (see Moons below), while another removed the outer envelope of the young Mercury.

text: At the end of the planetary formation epoch the inner Solar System was populated by 50–100 Moon- to Mars-sized

text: planetary embryo

text: s. Further growth was possible only because these bodies collided and merged, which took less than 100 million years. These objects would have gravitationally interacted with one another, tugging at each other's orbits until they collided, growing larger until the four terrestrial planets we know today took shape. One such giant collision is thought to have formed the Moon (see

text: Moons

text: below), while another removed the outer envelope of the young

text: Mercury

text: A numerical simulation was able to explain both the arguments of perihelion and the coincidence of orbital planes with mean-motion resonances caused by a hypothesized  massive object on a highly eccentric and moderately inclined orbit.  The model generated a pattern of high-inclination objects that they speculated as resulting from a combination of mean-motion effect with the Kozai effect relative to the hypothetical planet, and that they subsequently found in databases of minor objects in the Solar System.  Their origin could previously not be explained well.

text: A numerical simulation was able to explain both the arguments of perihelion and the coincidence of orbital planes with

text: mean-motion resonance

text: s caused by a hypothesized  massive object on a highly eccentric and moderately inclined orbit.  The model generated a pattern of high-inclination objects that they speculated as resulting from a combination of mean-motion effect with the Kozai effect relative to the hypothetical planet, and that they subsequently found in databases of minor objects in the Solar System.  Their origin could previously not be explained well.

text: For One Ring Zero's 2010 release, Planets, the band composed thirteen new songs to represent the solar system and beyond.  Tracks on the album include "An Introduction To Planets," "Mercury," "Venus," "Earth," "Mars Part I," "Mars Part II," "Jupiter," "63 Moons," "Saturn," "Uranus," "Neptune," "Pluto," and "Exoplanets."  The concept was inspired by Gustav Holst's nearly century-old orchestral suite "The Planets."  As Hearst and Camp put it, "Seemed like maybe it was time to revisit our solar system with some new tunes.”

text: For One Ring Zero's 2010 release, Planets, the band composed thirteen new songs to represent the solar system and beyond.  Tracks on the album include "An Introduction To Planets," "Mercury," "Venus," "Earth," "Mars Part I," "Mars Part II," "Jupiter," "63 Moons," "Saturn," "Uranus," "Neptune," "Pluto," and "Exoplanets."  The concept was inspired by

text: Gustav Holst

text: 's nearly century-old orchestral suite "

text: The Planets

text: ."  As Hearst and Camp put it, "Seemed like maybe it was time to revisit our solar system with some new tunes.”

text: The Uranian axis of rotation is approximately parallel with the plane of the Solar System, with an axial tilt of 97.77° (as defined by prograde rotation). This gives it seasonal changes completely unlike those of the other planets. Near the solstice, one pole faces the Sun continuously and the other faces away. Only a narrow strip around the equator experiences a rapid day–night cycle, but with the Sun low over the horizon. At the other side of Uranus's orbit the orientation of the poles towards the Sun is reversed. Each pole gets around 42 years of continuous sunlight, followed by 42 years of darkness. Near the time of the equinoxes, the Sun faces the equator of Uranus giving a period of day–night cycles similar to those seen on most of the other planets. In contrast to the other planets, whose motions around the Sun resemble that of spinning tops, Uranus's motion can be visualised as that of a ball rolling on the ecliptic plane near solstices and of a spinning rifle bullet near equinoxes.

text: The Uranian axis of rotation is approximately parallel with the plane of the Solar System, with an

text: axial tilt

text: of 97.77° (as defined by prograde rotation). This gives it seasonal changes completely unlike those of the other planets. Near the

text: solstice

text: , one pole faces the Sun continuously and the other faces away. Only a narrow strip around the equator experiences a rapid day–night cycle, but with the Sun low over the horizon. At the other side of Uranus's orbit the orientation of the poles towards the Sun is reversed. Each pole gets around 42 years of continuous sunlight, followed by 42 years of darkness. Near the time of the

text: equinox

text: es, the Sun faces the equator of Uranus giving a period of day–night cycles similar to those seen on most of the other planets. In contrast to the other planets, whose motions around the Sun resemble that of spinning tops, Uranus's motion can be visualised as that of a ball rolling on the

text: ecliptic

text: plane near solstices and of a spinning rifle bullet near equinoxes.

text: The discovery at California Institute of Technology in 1977 of new forms of the elements calcium, barium and neodymium in the meteorite was believed to show that those elements came from some source outside the early clouds of gas and dust that formed the Solar System.  This supports the theory that shockwaves from a supernova - the explosion of an aging star - may have triggered the formation of, or contributed to the formation of the Solar System.  As further evidence, the Caltech group said the meteorite contained Aluminum 26, a rare form of aluminum.  This acts as a "clock" on the meteorite, dating the explosion of the supernova to within less than 2 million years before the Solar System was formed.  Subsequent studies have found isotopic ratios of krypton, xenon, nitrogen and some other elements whose forms are also unknown in the Solar System.  The conclusion, from many studies with similar findings, is that there were a lot of substances in the presolar disc that were introduced as fine "dust" from nearby stars, including novas, supernovas, and red giants.  These specks persist to this day in meteorites like Allende, and are known as presolar grains.

text: The discovery at

text: California Institute of Technology

text: in 1977 of new forms of the elements

text: calcium

text: barium

text: and

text: neodymium

text: in the meteorite was believed to show that those elements came from some source outside the early clouds of gas and dust that formed the Solar System.  This supports the theory that shockwaves from a

text: supernova

text: - the explosion of an aging star - may have triggered the formation of, or contributed to the formation of the Solar System.  As further evidence, the Caltech group said the meteorite contained

text: Aluminum

text: 26, a rare form of aluminum.  This acts as a "clock" on the meteorite, dating the explosion of the supernova to within less than 2 million years before the Solar System was formed.  Subsequent studies have found isotopic ratios of

text: krypton

text: xenon

text: nitrogen

text: and some other elements whose forms are also unknown in the Solar System.  The conclusion, from many studies with similar findings, is that there were a lot of substances in the presolar disc that were introduced as fine "dust" from nearby stars, including novas, supernovas, and

text: red giant

text: s.  These specks persist to this day in meteorites like Allende, and are known as

text: presolar grains

text: A partial solar eclipse occurred on December 4, 1964. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: occurred on December 4, 1964. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: Solar energy, radiant light and heat from the sun, is harnessed using a range of ever-evolving technologies such as solar heating, photovoltaics, concentrated solar power (CSP), concentrator photovoltaics (CPV), solar architecture and artificial photosynthesis. Solar technologies are broadly characterized as either passive solar or active solar depending on the way they capture, convert and distribute solar energy. Passive solar techniques include orienting a building to the Sun, selecting materials with favorable thermal mass or light dispersing properties, and designing spaces that naturally circulate air. Active solar technologies encompass solar thermal energy, using solar collectors for heating, and solar power, converting sunlight into electricity either directly using photovoltaics (PV), or indirectly using concentrated solar power (CSP).

text: Solar energy

text: , radiant

text: light

text: and

text: heat

text: from the

text: sun

text: , is harnessed using a range of ever-evolving technologies such as

text: solar heating

text: photovoltaics

text: concentrated solar power

text: (CSP),

text: concentrator photovoltaics

text: (CPV),

text: solar architecture

text: and

text: artificial photosynthesis

text: . Solar technologies are broadly characterized as either

text: passive solar

text: or

text: active solar

text: depending on the way they capture, convert and distribute solar energy. Passive solar techniques include orienting a building to the Sun, selecting materials with favorable

text: thermal mass

text: naturally circulate air

text: . Active solar technologies encompass

text: solar thermal energy

text: , using

text: solar collectors

text: for heating, and

text: solar power

text: , converting

text: sunlight

text: into

text: electricity

text: either directly using

text: photovoltaics

text: (PV), or indirectly using

text: concentrated solar power

text: (CSP).

text: A brutal space pirate and mercenary, Nebula seized control of Sanctuary II, a massive spaceship previously under the command of Thanos. Thanos was believed to be dead at this point, and Nebula claimed that he had been her grandfather. Nebula's band of mercenaries and pirates consisted of Skunge, Kehl, Gunthar and Levan.

text: A brutal space pirate and mercenary, Nebula seized control of Sanctuary II, a massive spaceship previously under the command of

text: Thanos

text: . Thanos was believed to be dead at this point, and Nebula claimed that he had been her grandfather. Nebula's band of mercenaries and pirates consisted of

text: Skunge

text: Kehl

text: Gunthar

text: and

text: Levan

text: In 2007, David Faiman, director of the Ben-Gurion National Solar Energy Center, announced that the Center had entered into a project with Zenith to create a home solar energy system that uses a 10 square meter reflector dish.  Zenith bought the rights to solar technology from Ben-Gurion University and Germany's Fraunhofer Institute for Solar Energy Systems ISE to create solar energy using mirrors and lenses that magnify and focus the sun's rays. In testing, the concentrated solar technology proved to be up to five times more efficient than standard flat photovoltaic silicon panels, which would make it almost as cheap as oil and natural gas.  A prototype ready for commercialization achieved a concentration of solar energy that was more than 1,000 times greater than standard flat panels.  According to Faiman, who led the Israeli team that developed the technology, 10% of Israel’s energy needs (1,000 megawatts) could be met from 12 square kilometres of land.

text: In 2007, David Faiman, director of the

text: Ben-Gurion National Solar Energy Center

text: , announced that the Center had entered into a project with Zenith to create a home solar energy system that uses a 10 square meter reflector dish.  Zenith bought the rights to solar technology from

text: Ben-Gurion University

text: and Germany's

entity_name: Fraunhofer Institute for Solar Energy Systems ISE

text: Fraunhofer Institute for Solar Energy Systems ISE

text: to create solar energy using mirrors and lenses that magnify and focus the sun's rays. In testing, the concentrated solar technology proved to be up to five times more efficient than standard flat

text: photovoltaic

text: silicon

text: panels, which would make it almost as cheap as oil and natural gas.  A prototype ready for commercialization achieved a concentration of solar energy that was more than 1,000 times greater than standard flat panels.  According to Faiman, who led the Israeli team that developed the technology, 10% of Israel’s energy needs (1,000

text: megawatts

text: ) could be met from 12 square kilometres of land.

text: The migration of the outer planets is also necessary to account for the existence and properties of the Solar System's outermost regions. Beyond Neptune, the Solar System continues into the Kuiper belt, the scattered disc, and the Oort cloud, three sparse populations of small icy bodies thought to be the points of origin for most observed comets. At their distance from the Sun, accretion was too slow to allow planets to form before the solar nebula dispersed, and thus the initial disc lacked enough mass density to consolidate into a planet. The Kuiper belt lies between 30 and 55 AU from the Sun, while the farther scattered disc extends to over 100 AU, and the distant Oort cloud begins at about 50,000 AU. Originally, however, the Kuiper belt was much denser and closer to the Sun, with an outer edge at approximately 30 AU. Its inner edge would have been just beyond the orbits of Uranus and Neptune, which were in turn far closer to the Sun when they formed (most likely in the range of 15–20 AU), and in opposite locations, with Uranus farther from the Sun than Neptune.

text: The migration of the outer planets is also necessary to account for the existence and properties of the Solar System's outermost regions.

text: Beyond Neptune

text: , the Solar System continues into the

text: Kuiper belt

text: , the

text: scattered disc

text: , and the

text: Oort cloud

text: , three sparse populations of small icy bodies thought to be the points of origin for most observed

text: comet

text: s. At their distance from the Sun, accretion was too slow to allow planets to form before the solar nebula dispersed, and thus the initial disc lacked enough mass density to consolidate into a planet. The Kuiper belt lies between 30 and 55 AU from the Sun, while the farther scattered disc extends to over 100 AU, and the distant Oort cloud begins at about 50,000 AU. Originally, however, the Kuiper belt was much denser and closer to the Sun, with an outer edge at approximately 30 AU. Its inner edge would have been just beyond the orbits of Uranus and Neptune, which were in turn far closer to the Sun when they formed (most likely in the range of 15–20 AU), and in opposite locations, with Uranus farther from the Sun than Neptune.

text: During the day the sun has different positions. For low concentration systems (and low temperatures) tracking can be avoided (or limited to a few positions per year) if nonimaging optics are used. For higher concentrations, however, if the mirrors or lenses do not move, then the focus of the mirrors or lenses changes (but also in these cases nonimaging optics provides the widest acceptance angles for a given concentration). Therefore, it seems unavoidable that there needs to be a tracking system that follows the position of the sun (for solar photovoltaic a solar tracker is only optional). The tracking system increases the cost and complexity. With this in mind, different designs can be distinguished in how they concentrate the light and track the position of the sun.

text: During the day the sun has different positions. For low concentration systems (and low temperatures) tracking can be avoided (or limited to a few positions per year) if

text: nonimaging optics

text: are used. For higher concentrations, however, if the mirrors or lenses do not move, then the focus of the mirrors or lenses changes (but also in these cases

text: nonimaging optics

text: provides the widest

text: acceptance angles

text: for a given concentration). Therefore, it seems unavoidable that there needs to be a tracking system that follows the position of the sun (for solar

text: photovoltaic

text: a

text: solar tracker

text: is only optional). The tracking system increases the cost and complexity. With this in mind, different designs can be distinguished in how they concentrate the light and track the position of the sun.

text: Recently an uptake of Third Party ownership models for small to mid-scale solar photovoltaic systems has been seen in Australia mirroring developments in the same direction in the US with over 70% of all new PV systems installed under such models in California, Colorado and Arizona. In Australia the Solar Power Purchase Agreement approach is pursued under the term Solar Sponsoring

text: Recently an uptake of Third Party ownership models for small to mid-scale solar photovoltaic systems has been seen in Australia mirroring developments in the same direction in the US with over 70% of all new PV systems installed under such models in California, Colorado and Arizona. In Australia the Solar

text: Power Purchase Agreement

text: approach is pursued under the term Solar Sponsoring

text: In 1749, Georges-Louis Leclerc, Comte de Buffon conceived the idea that the planets were formed when a comet collided with the Sun, sending matter out to form the planets. However, Laplace refuted this idea in 1796, showing that any planets formed in such a way would eventually crash into the Sun. Laplace felt that the near-circular orbits of the planets were a necessary consequence of their formation. Today, comets are known to be far too small to have created the Solar System in this way.

text: In 1749,

text: Georges-Louis Leclerc, Comte de Buffon

text: conceived the idea that the planets were formed when a comet collided with the Sun, sending matter out to form the planets. However, Laplace refuted this idea in 1796, showing that any planets formed in such a way would eventually crash into the Sun. Laplace felt that the near-circular orbits of the planets were a necessary consequence of their formation. Today, comets are known to be far too small to have created the Solar System in this way.

text: Schumann resonance -sector boundary -selective fading -Shadow loss -shortwave relay station -side lobe -Signal-to-Interference Ratio -single event upset (SEU) -Single Vegetative Obstruction Model -SINPO code-skip (radio) -skip zone -sky wave -skywave -Solar Maximum Mission (SMM) -Synchronous Meteorological Satellite (SMS) -Software-defined radio -solar activity -solar constant -solar cycle -solar flare -solar flux -solar flux unit -solar maximum -solar minimum -solar radiation storm level -solar rotation rate -solar transition region -solar wind -solstice -Solar Observing Optical Network (SOON) -South Atlantic anomaly -Southern Hemisphere Auroral Radar Experiment -Space weather -spicule (solar physics) -SPLAT!-Sporadic E propagation -spray (solar physics) -Spread spectrum -stratosphere -substorm -sudden ionospheric disturbance (SID) -sunspot -sunspot cycle -sunspot number -super high frequency (SHF) -supergranulation -Surface wave -Solar X-ray Imager (SXI) -synodic -synoptic chart -

text: Schumann resonance

text: sector boundary

text: selective fading

text: Shadow loss

text: shortwave relay station

text: side lobe

text: Signal-to-Interference Ratio

text: single event upset

text: (SEU) -

text: Single Vegetative Obstruction Model

text: SINPO code

text: skip (radio)

text: skip zone

text: sky wave

text: skywave

text: Solar Maximum Mission

text: (SMM) -

text: Synchronous Meteorological Satellite

text: (SMS) -

text: Software-defined radio

text: solar activity

text: solar constant

text: solar cycle

text: solar flare

text: solar flux

text: solar flux unit

text: solar maximum

text: solar minimum

text: solar radiation storm level

text: solar rotation rate

text: solar transition region

text: solar wind

text: solstice

text: Solar Observing Optical Network

text: (SOON) -

text: South Atlantic anomaly

entity_name: Southern Hemisphere Auroral Radar Experiment

text: Southern Hemisphere Auroral Radar Experiment

text: Space weather

text: spicule (solar physics)

text: SPLAT!

text: Sporadic E propagation

text: spray (solar physics)

text: Spread spectrum

text: stratosphere

text: substorm

text: sudden ionospheric disturbance

text: (SID) -

text: sunspot

text: sunspot cycle

text: sunspot number

text: super high frequency

text: (SHF) -

text: supergranulation

text: Surface wave

text: Solar X-ray Imager

text: (SXI) -

text: synodic

text: synoptic chart

text: The University of Georgia Observatory is located on top of the Physics Building on the UGA campus. The observatory hosts colloquia, seminars, research groups, and open houses in addition to being utilized in undergraduate and graduate courses. The observatory is also the home of the Center for Simulational Physics, the Nanoscale Science and Engineering Center and the MRI Physics Lab. In 2013, UGA and Franklin College of Arts and Sciences became the first university to have a star-system named after it. The Kepler mission, NASA's first mission capable of finding earth-size planets, confirmed in 2012 the existence of three new planets in the system known as Kepler-37. This year, NASA authorized the nickname designation of this planetary system as UGA-1785, 1785 for the year the University of Georgia was founded. Roger C. Hunter, a Franklin College alumnus, presented the letter of conformation to then Franklin College dean Allan Dorsey during a visit to campus. Hunter noted the name to be given to this particular star system due to light captured by the Kepler telescope began its journey towards earth in 1801 - the same year Franklin College was founded.

text: The University of Georgia Observatory is located on top of the Physics Building on the UGA campus. The observatory hosts colloquia, seminars, research groups, and open houses in addition to being utilized in undergraduate and graduate courses. The observatory is also the home of the Center for Simulational Physics, the Nanoscale Science and Engineering Center and the MRI Physics Lab. In 2013, UGA and

text: Franklin College of Arts and Sciences

text: became the first university to have a star-system named after it. The Kepler mission, NASA's first mission capable of finding earth-size planets, confirmed in 2012 the existence of three new planets in the system known as Kepler-37. This year, NASA authorized the nickname designation of this planetary system as UGA-1785, 1785 for the year the University of Georgia was founded. Roger C. Hunter, a Franklin College alumnus, presented the letter of conformation to then Franklin College dean Allan Dorsey during a visit to campus. Hunter noted the name to be given to this particular star system due to light captured by the Kepler telescope began its journey towards earth in 1801 - the same year Franklin College was founded.

text: Astronomers expect that the discovery of Planet Nine would aid in understanding the processes behind the formation of the Solar System and other planetary systems, as well as how unusual the Solar System is, with a lack of planets with masses between that of Earth and that of Neptune, compared to other planetary systems.

text: Astronomers expect that the discovery of Planet Nine would aid in understanding the processes behind the formation of the Solar System and other

text: planetary system

text: s, as well as how unusual the Solar System is, with a lack of planets with masses between that of Earth and that of Neptune, compared to other planetary systems.

text: A Small Solar System Body (SSSB) is an object in the Solar System that is neither a planet, nor a dwarf planet, nor a natural satellite. The term was first defined in 2006 by the International Astronomical Union.

text: A Small Solar System Body (SSSB) is an object in the

text: Solar System

text: that is neither a

text: planet

text: , nor a

text: dwarf planet

text: , nor a

text: natural satellite

text: . The term was first

text: defined in 2006

text: by the

text: International Astronomical Union

text: The recorded history of Mars observation dates back to the era of the ancient Egyptian astronomers in the 2nd millennium BCE. Chinese records about the motions of Mars appeared before the founding of the Zhou Dynasty (1045 BCE). Detailed observations of the position of Mars were made by Babylonian astronomers who developed arithmetic techniques to predict the future position of the planet. The ancient Greek philosophers and Hellenistic astronomers developed a geocentric model to explain the planet's motions. Measurements of Mars' angular diameter can be found in ancient Greek and Indian texts. In the 16th century, Nicolaus Copernicus proposed a heliocentric model for the Solar System in which the planets follow circular orbits about the Sun. This was revised by Johannes Kepler, yielding an elliptic orbit for Mars that more accurately fitted the observational data.

text: The recorded history of Mars observation dates back to the era of the ancient

text: Egyptian astronomers

text: in the

text: 2nd millennium BCE

text: Chinese

text: records about the motions of

text: Mars

text: appeared before the founding of the

text: Zhou Dynasty

text: (1045 BCE). Detailed observations of the position of Mars were made by

text: Babylonian astronomers

text: who developed arithmetic techniques to predict the future position of the planet. The ancient

text: Greek philosophers

text: and

text: Hellenistic

text: astronomers

text: developed a

text: geocentric model

text: to explain the planet's motions. Measurements of Mars' angular diameter can be found in ancient Greek and

text: Indian

text: texts. In the 16th century,

text: Nicolaus Copernicus

text: proposed a

text: heliocentric model

text: for the

text: Solar System

text: in which the planets follow circular orbits about the

text: Sun

text: . This was revised by

text: Johannes Kepler

text: , yielding an

text: elliptic orbit

text: for Mars that more accurately fitted the observational data.

text: On 24 August 2006, the International Astronomical Union (IAU) defined what it means to be a "planet" within the Solar System. This definition excluded Pluto as a planet and added it as a member of the new category "dwarf planet", along with Eris and Ceres.

text: On 24 August 2006, the

text: International Astronomical Union

text: (IAU)

text: defined what it means to be a "planet" within the Solar System

text: . This definition excluded Pluto as a planet and added it as a member of the new category "

text: dwarf planet

text: ", along with

text: Eris

text: and

text: Ceres

text: If the Moon were in a perfectly circular orbit, a little closer to the Earth, and in the same orbital plane, there would be total solar eclipses every month. However, the Moon's orbit is inclined (tilted) at more than 5 degrees to the Earth's orbit around the Sun (see ecliptic), so its shadow at new moon usually misses Earth. Earth's orbit is called the ecliptic plane as the Moon's orbit must cross this plane in order for an eclipse (both solar as well as lunar) to occur. In addition, the Moon's actual orbit is elliptical, often taking it far enough away from Earth that its apparent size is not large enough to block the Sun totally. The orbital planes cross each other at a line of nodes resulting in at least two, and up to five, solar eclipses occurring each year; no more than two of which can be total eclipses. However, total solar eclipses are rare at any particular location because totality exists only along a narrow path on the Earth's surface traced by the Moon's shadow or umbra.

text: If the Moon were in a perfectly circular orbit, a little closer to the Earth, and in the same

text: orbital plane

text: , there would be total solar eclipses every month. However, the Moon's orbit is

text: inclined

text: (tilted) at more than 5 degrees to the Earth's orbit around the Sun (see

text: ecliptic

text: ), so its shadow at new moon usually misses Earth. Earth's orbit is called the ecliptic plane as the Moon's orbit must cross this plane in order for an eclipse (both solar as well as

text: lunar

text: ) to occur. In addition, the Moon's actual orbit is elliptical, often taking it far enough away from Earth that its

text: apparent size

text: is not large enough to block the Sun totally. The orbital planes cross each other at a

text: line of nodes

text: resulting in at least two, and up to five, solar eclipses occurring each year; no more than two of which can be total eclipses. However, total solar eclipses are rare at any particular location because totality exists only along a narrow path on the Earth's surface traced by the Moon's shadow or

text: umbra

text: Two scientists with the Harvard–Smithsonian Center for Astrophysics stated that when, and even whether, the two galaxies collide will depend on Andromeda's transverse velocity. Based on current calculations they predict a 50% chance that in a merged galaxy, the Solar System will be swept out three times farther from the galactic core than its current distance. They also predict a 12% chance that the Solar System will be ejected from the new galaxy sometime during the collision. Such an event would have no adverse effect on the system and the chances of any sort of disturbance to the Sun or planets themselves may be remote.

text: Two scientists with the

text: Harvard–Smithsonian Center for Astrophysics

text: stated that when, and even whether, the two galaxies collide will depend on Andromeda's transverse velocity. Based on current calculations they predict a 50% chance that in a merged galaxy, the Solar System will be swept out three times farther from the galactic core than its current distance. They also predict a 12% chance that the Solar System will be ejected from the new galaxy sometime during the collision. Such an event would have no adverse effect on the system and the chances of any sort of disturbance to the Sun or planets themselves may be remote.

text: The works of the classical Indian astronomer and mathematician, Aryabhatta (476–550 AD), deal with the sphericity of the Earth and the motion of the planets. The final two parts of his Sanskrit magnum opus, the Aryabhatiya, which were named the Kalakriya ("reckoning of time") and the Gol ("sphere"), state that the Earth is spherical and that its circumference is 4,967 yojanas. In modern units this is , close to the current equatorial value of .

text: The works of the classical

text: Indian astronomer

text: and

text: mathematician

text: Aryabhatta

text: (476–550 AD), deal with the sphericity of the Earth and the motion of the planets. The final two parts of his

text: Sanskrit

text: magnum opus, the

text: Aryabhatiya

text: , which were named the Kalakriya ("reckoning of time") and the Gol ("sphere"), state that the Earth is spherical and that its circumference is 4,967

text: yojana

text: s. In modern units this is , close to the current

text: equator

text: ial value of .

text: Although the , , and  points are nominally unstable, it turns out that it is possible to find (unstable) periodic orbits around these points, at least in the restricted three-body problem. These periodic orbits, referred to as "halo" orbits, do not exist in a full n-body dynamical system such as the Solar System. However, quasi-periodic (i.e. bounded but not precisely repeating) orbits following Lissajous-curve trajectories do exist in the n-body system. These quasi-periodic Lissajous orbits are what most of Lagrangian-point missions to date have used. Although they are not perfectly stable, a relatively modest effort at station keeping can allow a spacecraft to stay in a desired Lissajous orbit for an extended period of time. It also turns out that, at least in the case of Sun–Earth- missions, it is actually preferable to place the spacecraft in a large-amplitude () Lissajous orbit, instead of having it sit at the Lagrangian point, because this keeps the spacecraft off the direct line between Sun and Earth, thereby reducing the impact of solar interference on Earth–spacecraft communications. Similarly, a large-amplitude Lissajous orbit around  can keep a probe out of Earth's shadow and therefore ensures a better illumination of its solar panels.

text: Although the , , and  points are nominally unstable, it turns out that it is possible to find (unstable) periodic orbits around these points, at least in the restricted three-body problem. These periodic orbits, referred to as

text: "halo" orbits

text: , do not exist in a full n-body dynamical system such as the

text: Solar System

text: . However, quasi-periodic (i.e. bounded but not precisely repeating) orbits following

text: Lissajous-curve

text: trajectories do exist in the n-body system. These quasi-periodic

text: Lissajous orbit

text: s are what most of Lagrangian-point missions to date have used. Although they are not perfectly stable, a relatively modest effort at

text: station keeping

text: can allow a spacecraft to stay in a desired Lissajous orbit for an extended period of time. It also turns out that, at least in the case of Sun–Earth- missions, it is actually preferable to place the spacecraft in a large-amplitude () Lissajous orbit, instead of having it sit at the Lagrangian point, because this keeps the spacecraft off the direct line between Sun and Earth, thereby reducing the impact of solar

text: interference

text: on Earth–spacecraft communications. Similarly, a large-amplitude Lissajous orbit around  can keep a probe out of Earth's shadow and therefore ensures a better illumination of its solar panels.

text: In the Solar System, many of the disturbances of one planet by another are periodic, consisting of small impulses each time a planet passes another in its orbit. This causes the bodies to follow motions that are periodic or quasi-periodic – such as the Moon in its strongly perturbed orbit, which is the subject of lunar theory. This periodic nature led to the discovery of Neptune in 1846 as a result of its perturbations of the orbit of Uranus.

text: In the Solar System, many of the disturbances of one planet by another are periodic, consisting of small impulses each time a planet passes another in its orbit. This causes the bodies to follow motions that are periodic or quasi-periodic – such as the Moon in its

text: strongly perturbed

text: orbit

text: , which is the subject of

text: lunar theory

text: . This periodic nature led to the

text: discovery of Neptune

text: in 1846 as a result of its perturbations of the orbit of

text: Uranus

text: Thanks to the "romance" between carbon and oxygen atoms, which form gases when they combine, the solid material in a given planetary system probably depends on whether carbon abundances were greater, or less, than those of oxygen. What is left over goes into solids. There was more oxygen than carbon in the Solar System, so solid planetary surfaces (as well as primitive meteorites) are largely made up of oxides like SiO (silicates, resulting in silicate planets). If the converse was true, carbides might be the dominant form of "rock" (resulting in carbon planets).

text: Thanks to the "romance" between

text: carbon

text: and

text: oxygen

text: atoms, which form gases when they combine, the solid material in a given

text: planetary system

text: probably depends on whether carbon abundances were greater, or less, than those of oxygen. What is left over goes into solids. There was more oxygen than carbon in the Solar System, so solid planetary surfaces (as well as primitive meteorites) are largely made up of oxides like SiO (

text: silicate

text: s, resulting in

text: silicate planet

text: s). If the converse was true,

text: carbide

text: s might be the dominant form of "rock" (resulting in

text: carbon planet

text: s).

text: Development of a solar car to enter the World Solar Challenge became a Western Engineering reality as a small group of inspired students took on the challenge as part of a fourth year capstone project. The SunStang Project with the encouragement of Professor John Tarasuk, under the student leadership of Matthew Butson undertook a major task: design and build a solar powered car to compete in the World Solar Challenge 1993, with the event date less than two years away. The team of about one dozen was mainly 3rd and 4th year mechanical engineering students and one or two senior electrical students.  The team from early stages had good representation of female students (roughly 30%).  Sub-groups were tasked with designing the chassis, drive system, steering, braking and safety systems.  The vehicle even had a fibre optic rear view vision camera and an adiabatic air conditioning unit designed to work in the hot & dry Australian outback.  Another monumental task of the inaugural team was coordinating the fund-raising effort to pay the expenses of building and shipping the car to the race.  The team arranged goods-in-kind for the magnesium tubes of the vehicle frame from local industry. The motor and solar panels were also sponsor donated.  The tiny cells were laminated and wired together individually to create an energy array.  Team marketing and raising awareness on campus helped collect funds from the student population.  One of the main sponsors of the 1993 vehicle was UWO supporter, turned Australian businessman Jack Cowin, the logo can be seen on both side of the SunStang cockpit.  Team members enjoyed free Hungry Jack's food during the race in Australia in November of 1993.

text: This system is mainly responsible for the correct spacecraft's orientation in space (attitude) despite external disturbance-gravity gradient effects, magnetic-field torques, solar radiation and aerodynamic drag; in addition it may be required to reposition movable parts, such as antennas and solar arrays.

text: Founded by the Center for Environmental Innovation in Roofing and Nationalwide Roofing Contractors Association, Roof Integrated Solar Energy (RISE) Inc. was created to provide a means of evaluating and certifying solar roofing professionals to support the widespread use of rooftop solar energy. RISE evaluates and certifies solar energy installers for knowledge about critical roof system construction and maintenance practices necessary to support successful rooftop solar energy installations based on principles regarding the, installation and maintenance of rooftop solar energy systems without adversely affecting roof system performance and service life. RISE also provides the public with tools to identify skilled rooftop solar energy professionals.

text: The asteroid belt is the circumstellar disc in the Solar System located roughly between the orbits of the planets Mars and Jupiter. It is occupied by numerous irregularly shaped bodies called asteroids or minor planets. The asteroid belt is also termed the main asteroid belt or main belt to distinguish it from other asteroid populations in the Solar System such as near-Earth asteroids and trojan asteroids. About half the mass of the belt is contained in the four largest asteroids: Ceres, Vesta, Pallas, and Hygiea. The total mass of the asteroid belt is approximately 4% that of the Moon, or 22% that of Pluto, and roughly twice that of Pluto's moon Charon (whose diameter is 1200 km).

text: The asteroid belt is the

text: circumstellar disc

text: in the

text: Solar System

text: located roughly between the orbits of the

text: planet

text: s

text: Mars

text: and

text: Jupiter

text: . It is occupied by numerous irregularly shaped bodies called

text: asteroid

text: s or

text: minor planet

text: s. The asteroid belt is also termed the main asteroid belt or main belt to distinguish it from other asteroid populations in the Solar System such as

text: near-Earth asteroids

text: and

text: trojan asteroids

text: . About half the mass of the belt is contained in the four largest asteroids:

text: Ceres

text: Vesta

text: Pallas

text: , and

text: Hygiea

text: . The total mass of the asteroid belt is approximately 4% that of the

text: Moon

text: , or 22% that of

text: Pluto

text: , and roughly twice that of Pluto's moon

text: Charon

text: (whose diameter is 1200 km).

text: Simplicio now gives the greatest argument against the annual motion of the earth that if it moves then it can no longer be the center of the zodiac, the world. Aristotle gives proofs that the universe is finite bounded and spherical. Salvatius points out that these disappear if he denies him the assumption that it is movable, but allows the assumption initially in order not to multiply disputes.

text: Active stars produce disturbances in space weather with the field of heliophysics the science that studies such phenomena; itself primarily an interdisciplinary combination of stellar astronomy and planetary science. In the Solar System, the Sun can produce intense geomagnetic and proton storms capable of causing severe damage to technology including but not limited to large scale power outages, disruption or blackouts of radio communications (including GPS), and temporary to permanent disabling of satellites and other spaceborne technology. Intense solar storms may also be hazardous to high-latitude, high-altitude aviation and to human spaceflight. Geomagnetic storms are the cause of auroras. The most significant known solar storm occurred in September 1859 and is known as the "Carrington event". The damage from the most potent solar storms is capable of existentially threatening the stability of modern human civilization, although proper preparedness and mitigation can substantially reduce the hazards. Proxy data from Earth, as well as analysis of stars similar to the Sun suggest that it may be capable of producing so called superflares, those which are much larger than any flares in the historical record (as much as 1000x stronger every 5000 years).

text: Active stars produce disturbances in

text: space weather

text: with the field of

text: heliophysics

text: the science that studies such phenomena; itself primarily an interdisciplinary combination of

text: stellar astronomy

text: and

text: planetary science

text: . In the

text: Solar System

text: , the

text: Sun

text: can produce intense

text: geomagnetic

text: and

text: proton

text: storms capable of causing severe damage to technology including but not limited to large scale

text: power outage

text: s, disruption or

text: blackouts

text: of radio communications (including

text: GPS

text: ), and temporary to permanent disabling of satellites and other spaceborne technology. Intense solar storms may also be hazardous to high-latitude, high-altitude aviation and to

text: human spaceflight

text: . Geomagnetic storms are the cause of

text: aurora

text: s. The most significant known solar storm occurred in September 1859 and is known as the "Carrington event". The damage from the most potent solar storms is capable of existentially threatening the stability of modern human civilization, although proper preparedness and mitigation can substantially reduce the hazards. Proxy data from Earth, as well as analysis of stars similar to the Sun suggest that it may be capable of producing so called

text: superflare

text: s, those which are much larger than any flares in the historical record (as much as 1000x stronger every 5000 years).

text: SWEEPS-04 is an extrasolar planet orbiting the star SWEEPS J175853.92−291120.6 in the constellation Sagittarius approximately 27,710 light years away (based on a distance modulus of 14.1) from the Solar System, making it (along with SWEEPS-11) the most distant exoplanet(s) known. This planet was found in 2006 by the Sagittarius Window Eclipsing Extrasolar Planet Search (SWEEPS) program that uses the transit method.

text: SWEEPS-04 is an

text: extrasolar planet

text: orbiting the

text: star

text: SWEEPS J175853.92−291120.6

text: in the

text: constellation

text: Sagittarius

text: approximately 27,710

text: light year

text: s away (based on a

text: distance modulus

text: of 14.1) from the

text: Solar System

text: , making it (along with

text: ) the most distant exoplanet(s) known. This planet was found in 2006 by the

text: (SWEEPS) program that uses the

text: transit method

text: Astronomers conjecture that the matter composing the Oort cloud formed closer to the Sun and was scattered far into space by the gravitational effects of the giant planets early in the Solar System's evolution. Although no confirmed direct observations of the Oort cloud have been made, it may be the source of all long-period and Halley-type comets entering the inner Solar System, and many of the centaurs and Jupiter-family comets as well.

text: Astronomers conjecture that the matter composing the Oort cloud formed closer to the Sun and was scattered far into space by the gravitational effects of the

text: giant planet

text: s early in the

text: Solar System's evolution

text: . Although no confirmed direct observations of the Oort cloud have been made, it may be the source of all

text: long-period

text: and

text: Halley-type

text: comets entering the inner Solar System, and many of the

text: centaurs

text: and

text: Jupiter

text: -family comets as well.

text: From the mid-1960s on, the traditional type of planetary romance set in the Solar System fell out of favor; as technological advances revealed most local worlds to be hostile to life, new planetary stories have usually been set on extrasolar planets, generally through the assumption of some form of faster-than-light travel. One exception is the Gor series, published from 1967 to the present. Gor is a Counter-Earth planet in a symmetrical orbit to Earth on the other side of the Sun (not at Earth’s L3 point). Gravitational effects and detection by terrestrial probes are explained away by “superior alien science”, a common conceit in planetary romances.

text: From the mid-1960s on, the traditional type of planetary romance set in the

text: Solar System

text: fell out of favor; as technological advances revealed most local worlds to be hostile to life, new planetary stories have usually been set on

text: extrasolar planet

text: s, generally through the assumption of some form of

text: faster-than-light

text: travel. One exception is the

text: Gor

text: series, published from 1967 to the present. Gor is a

text: Counter-Earth

text: planet in a symmetrical orbit to Earth on the other side of the Sun (not at Earth’s

text: point). Gravitational effects and detection by terrestrial probes are explained away by “superior alien science”, a common

text: conceit

text: in planetary romances.

text: In 2007, a gas giant planet designated V391 Pegasi b was found in orbit by variable star timing method. This planet around an "extreme horizontal branch" star provided clues about what could happen to the planets in the Solar System when the Sun turns into a red giant within the next 5 billion years.

text: In 2007, a

text: gas giant

text: planet

text: designated

text: V391 Pegasi b

text: was found in

text: orbit

text: by

text: variable star timing

text: method. This planet around an "extreme horizontal branch" star provided clues about what could happen to the planets in the

text: Solar System

text: when the

text: Sun

text: turns into a red giant within the next 5 billion years.

text: The term heliophysics  means "physics of the Sun"  (the prefix "helio" (Attic Greek: helios) means Sun), and appears to have been used only in that sense until quite recently. For example, the Debrecen Heliophysical Observatory is an astronomical observatory owned and operated by Konkoly Thege Miklós Astronomical Institute of Hungarian Academy of Sciences, and provides solar data and images of the solar surface obtained in Hungary since the middle of the nineteenth century. In the early times, heliophysics was concerned principally with the superficial layers of the star, and was synonymous with what is now more commonly called "solar physics".  Usage was extended explicitly 1981 to its literal meaning, denoting the physics of the entire Sun: from center to corona. As such it was a direct translation from the French héliophysique, which had been introduced to provide a distinction from physique solaire (solar physics).  It thus became a subdiscipline of heliology. Early in the 21st century the meaning of the term was extended by Dr George Siscoe of Boston University to include the physics of the heliosphere (the space around the Sun beyond the corona, in principle out to the shock where the solar wind encounters the interstellar medium, but excluding the planets and other condensed bodies), although Siscoe's view of the discipline appears not to contain most of the true realm of endeavour.  The term was adopted in Siscoe's restricted sense by the NASA Science Mission Directorate to denote the study of the heliosphere and the objects that interact with it—most notably planetary atmospheres and magnetospheres, the solar corona, and the interstellar medium.  Heliophysics combines several other disciplines, including  solar physics, and stellar physics in general, and also several branches of nuclear physics,  plasma physics and space physics.  The recent extension of heliophysics is closely tied to the study of space weather and the phenomena that affect it, and consequently to climatology.  To quote Siscoe from a recent conference presentation:

text: The term heliophysics  means "physics of the Sun"  (the prefix "helio" (Attic Greek: helios) means Sun), and appears to have been used only in that sense until quite recently. For example, the

text: Debrecen Heliophysical Observatory

text: is an astronomical observatory owned and operated by Konkoly Thege Miklós Astronomical Institute of Hungarian Academy of Sciences, and provides solar data and images of the solar surface obtained in Hungary since the middle of the nineteenth century. In the early times, heliophysics was concerned principally with the superficial layers of the star, and was synonymous with what is now more commonly called "solar physics".  Usage was extended explicitly 1981 to its literal meaning, denoting the physics of the entire

text: Sun

text: : from center to

text: corona

text: . As such it was a direct translation from the French héliophysique, which had been introduced to provide a distinction from physique solaire (

text: solar physics

text: ).  It thus became a subdiscipline of

text: heliology

text: . Early in the 21st century the meaning of the term was extended by Dr George Siscoe of Boston University to include the physics of the

text: heliosphere

text: (the space around the Sun beyond the corona, in principle out to the shock where the solar wind encounters the interstellar medium, but excluding the planets and other condensed bodies), although Siscoe's view of the discipline appears not to contain most of the true realm of endeavour.  The term was adopted in Siscoe's restricted sense by the

text: NASA

text: Science Mission Directorate to denote the study of the heliosphere and the objects that interact with it—most notably planetary

text: atmosphere

text: s and

text: magnetosphere

text: s, the

text: solar corona

text: , and the

text: interstellar medium

text: .  Heliophysics combines several other disciplines, including

text: solar physics

text: , and

text: stellar physics

text: in general, and also several branches of

text: nuclear physics

text: plasma physics

text: and

text: space physics

text: .  The recent extension of heliophysics is closely tied to the study of

text: space weather

text: and the phenomena that affect it, and consequently to

text: climatology

text: .  To quote Siscoe from a recent conference presentation:

text: Gliese 876 b was discovered independently by two different teams, one led by Geoffrey Marcy (with data from Keck Observatory and Lick Observatory) and the other by Xavier Delfosse (at Geneva Observatory). Like the majority of known extrasolar planets, it was discovered by detecting variations in its star's radial velocity as a result of the planet's gravity. This was done by making sensitive measurements of the Doppler shift of the spectral lines of Gliese 876. It was the first discovered of four known planets in the Gliese 876 system.

text: Gliese 876 b was discovered independently by two different teams, one led by

text: Geoffrey Marcy

text: (with data from

text: Keck Observatory

text: and

text: Lick Observatory

text: ) and the other by Xavier Delfosse (at

text: Geneva Observatory

text: ). Like the majority of known extrasolar planets, it was discovered by detecting variations in its star's

text: radial velocity

text: as a result of the planet's

text: gravity

text: . This was done by making sensitive measurements of the

text: Doppler shift

text: of the

text: spectral line

text: s of Gliese 876. It was the first discovered of four known planets in the Gliese 876 system.

text: Among the remaining irregular moons, Sao and Laomedeia follow prograde orbits, whereas Halimede, Psamathe and Neso follow retrograde orbits. Given the similarity of their orbits, it was suggested that Neso and Psamathe could have a common origin in the break-up of a larger moon. Psamathe and Neso have the largest orbits of any natural satellites discovered in the Solar system to date. They take 25 years to orbit Neptune at an average of 125 times the distance between Earth and the Moon. Neptune has the largest Hill sphere in the Solar System, owing primarily to its large distance from the Sun; this allows it to retain control of such distant moons. Nevertheless, Jupiter's S/2003 J 2 orbits at the greatest percentage of the primary's Hill radius of all the moons in the Solar System on average, and the Jovian moons in the Carme and Pasiphae groups orbit at a greater percentage of their primary's Hill radius than Psamathe and Neso.

text: Among the remaining irregular moons, Sao and Laomedeia follow prograde orbits, whereas Halimede, Psamathe and Neso follow retrograde orbits. Given the similarity of their orbits, it was suggested that Neso and Psamathe could have a common origin in the break-up of a larger moon. Psamathe and Neso have the largest orbits of any natural satellites discovered in the Solar system to date. They take 25 years to orbit Neptune at an average of 125 times the distance between Earth and the Moon. Neptune has the largest

text: Hill sphere

text: in the Solar System, owing primarily to its large distance from the Sun; this allows it to retain control of such distant moons. Nevertheless, Jupiter's

text: S/2003 J 2

text: orbits at the greatest percentage of the primary's Hill radius of all the moons in the Solar System on average, and the Jovian moons in the

text: Carme

text: and

text: Pasiphae group

text: s orbit at a greater percentage of their primary's Hill radius than Psamathe and Neso.

text: Steel Beach takes place (as does The Golden Globe) in a universe similar to (but distinct from) Varley's "Eight Worlds" universe: in each, the solar system has been colonized by human refugees fleeing aliens (known simply as "the Invaders") invading the Earth. The home planet and Jupiter are off-limits to humanity, but "Luna" -- the Moon, with its surface transformed to support conditions resembling Earth before the alien conquest of it, has become (along with all the other planets and moons of the solar system) heavily populated. There are also minor colonies set in the Oort cloud beyond the solar system itself.

text: Steel Beach takes place (as does

text: The Golden Globe

text: ) in a universe similar to (but distinct from) Varley's "

text: Eight Worlds

text: " universe: in each, the

text: solar system

text: has been colonized by human refugees fleeing aliens (known simply as "the Invaders") invading the

text: Earth

text: . The home planet and

text: Jupiter

text: are off-limits to humanity, but "Luna" -- the

text: Moon

text: , with its surface transformed to support conditions resembling Earth before the alien conquest of it, has become (along with all the other

text: planet

text: s and moons of the solar system) heavily populated. There are also minor colonies set in the

text: Oort cloud

text: beyond the solar system itself.

text: The first project to describe the shape of the Milky Way and the position of the Sun was undertaken by William Herschel in 1785 by counting the number of stars in different regions of the sky. He produced a diagram of the shape of the galaxy with the Solar System close to the center.<ref>William Herschel (1785) "On the Construction of the Heavens," Philosophical Transactions of the Royal Society of London, 75 : 213-266.  Herschel's diagram of the galaxy appears immediately after the article's last page.  See:

text: The first project to describe the shape of the Milky Way and the position of the Sun was undertaken by

text: William Herschel

text: in 1785 by counting the number of stars in different regions of the sky. He produced a diagram of the shape of the galaxy with

text: the Solar System close to the center

text: .<ref>William Herschel (1785) "On the Construction of the Heavens," Philosophical Transactions of the Royal Society of London, 75 : 213-266.  Herschel's diagram of the galaxy appears immediately after the article's last page.  See:

text: 21st Century Science & Technology has published papers by climate change contrarians including Zbigniew Jaworowski, Nils-Axel Mörner, Hugh Ellsaesser, and Robert E. Stevenson. A 2007 article by LaRouche science advisor Laurence Hecht suggested that the varying levels of cosmic rays, whose change is dependent on Earth's motion through the galaxy, has a larger effect on the climate than local factors such as greenhouse gases or solar and orbital cycles. Christopher Monckton was praised as the leading spokesman of the "global warming swindle" in the introduction to an Executive Intelligence Review interview with him in 2009, but he was also considered to have a relatively limited view of the cabal behind the hoax. A movement newsletter says that environmental groups seek to "force... CO2 emissions agreements down the throats of governments as a way of finishing off the nation-state system" on behalf of synarchist networks.

text: 21st Century Science & Technology

text: has published papers by climate change contrarians including

text: Zbigniew Jaworowski

text: Nils-Axel Mörner

text: , Hugh Ellsaesser, and Robert E. Stevenson. A 2007 article by LaRouche science advisor Laurence Hecht suggested that the varying levels of cosmic rays, whose change is dependent on Earth's motion through the galaxy, has a larger effect on the climate than local factors such as greenhouse gases or solar and orbital cycles.

entity_name: Christopher Monckton, 3rd Viscount Monckton of Brenchley

text: Christopher Monckton

text: was praised as the leading spokesman of the "global warming swindle" in the introduction to an

text: Executive Intelligence Review

text: interview with him in 2009, but he was also considered to have a relatively limited view of the cabal behind the hoax. A movement newsletter says that environmental groups seek to "force... CO2 emissions agreements down the throats of governments as a way of finishing off the nation-state system" on behalf of synarchist networks.

text: This nebula was discovered by the French astronomer Antoine Darquier de Pellepoix in January 1779, who reported that it was "...as large as Jupiter and resembles a planet which is fading". Later the same month, fellow French astronomer Charles Messier independently found the same nebula while searching for comets. It was then entered into his catalogue as the 57th object. Messier and German-born astronomer William Herschel speculated that the nebula was formed by multiple faint stars that were unresolvable with his telescope.

text: This nebula was discovered by the French astronomer

text: Antoine Darquier de Pellepoix

text: in January 1779, who reported that it was "...as large as Jupiter and resembles a planet which is fading". Later the same month, fellow French astronomer

text: Charles Messier

text: independently found the same nebula while searching for

text: comet

text: s. It was then entered into his catalogue as the 57th object. Messier and German-born astronomer

text: William Herschel

text: speculated that the nebula was formed by multiple faint stars that were unresolvable with his telescope.

text: In 2011, Vivint Inc. launched a standalone company, Vivint Solar, as a solar electricity provider that designs, installs, and maintains residential photovoltaic systems. The company offers solar panels via a power purchase agreement (PPA). Vivint Solar owns, installs, and maintains solar panels on customers’ homes in exchange for customers agreeing to purchase the solar energy their panels produce. Customers do not pay for installation, but pay for energy that the panel's produce, for the life of the contracts.  Vivint Solar is similar to other alternative solar companies like SolarCity, SunRun, and Sungevity. Its innovation in the field is the use of microinverters for each separate solar panel, allowing maximum production when some of the panels are in the shade.

text: In 2011, Vivint Inc. launched a standalone company,

text: Vivint Solar

text: , as a

text: solar electricity

text: provider that designs, installs, and maintains residential

text: photovoltaic system

text: s. The company offers solar panels via a

text: power purchase agreement

text: (PPA). Vivint Solar owns, installs, and maintains

text: solar panel

text: s on customers’ homes in exchange for customers agreeing to purchase the solar energy their panels produce. Customers do not pay for installation, but pay for energy that the panel's produce, for the life of the contracts.  Vivint Solar is similar to other alternative solar companies like

text: SolarCity

text: SunRun

text: , and

text: Sungevity

text: . Its innovation in the field is the use of

text: microinverter

text: s for each separate solar panel, allowing maximum production when some of the panels are in the shade.

text: The theory was based on the idea that a star passed close enough to the sun early in its life to cause tidal bulges to form on its surface, which along with the internal process that leads to solar prominences, caused material to be ejected repeatedly from the sun. Due to the gravitational effects of the passing star, two spiral-like arms would have extended from the sun, and while most of the material would have fallen back, part of it would remain in orbit. This orbiting material would cool and condense into numerous small bodies that they termed planetesimals and a few larger protoplanets. Their theory proposed that as these objects collided over time, the planets and their moons were built up, with comets and asteroids being the leftover debris. The "spiral nebulae" photographed at Lick Observatory were thought to possibly be views of other suns undergoing this process. These nebulae are now known to be galaxies rather than developing solar systems.

text: The theory was based on the idea that a star passed close enough to the sun early in its life to cause tidal bulges to form on its surface, which along with the internal process that leads to

text: solar prominence

text: s, caused material to be ejected repeatedly from the sun. Due to the gravitational effects of the passing star, two spiral-like arms would have extended from the sun, and while most of the material would have fallen back, part of it would remain in orbit. This orbiting material would cool and condense into numerous small bodies that they termed

text: planetesimal

text: s and a few larger

text: protoplanet

text: s. Their theory proposed that as these objects collided over time, the planets and their moons were built up, with

text: comet

text: s and

text: asteroid

text: s being the leftover debris. The "spiral nebulae" photographed at

text: Lick Observatory

text: were thought to possibly be views of other suns undergoing this process. These nebulae are now known to be

text: galaxies

text: rather than developing solar systems.

text: In the Solar System, the inclination of the orbit of a planet is defined as the angle between the plane of the orbit of the planet and the ecliptic. Therefore, Earth's inclination is, by definition, zero. Inclination could instead be measured with respect to another plane, such as the Sun's equator or even Jupiter's orbital plane, but the ecliptic is more practical for Earth-bound observers. Most planetary orbits in the Solar System have relatively small inclinations, both in relation to each other and to the Sun's equator. On the other hand, the dwarf planets Pluto and Eris have inclinations to the ecliptic of 17° and 44° respectively, and the large asteroid Pallas is inclined at 34°.

text: In the

text: Solar System

text: , the inclination of the orbit of a

text: planet

text: is defined as the angle between the plane of the orbit of the planet and the ecliptic. Therefore, Earth's inclination is, by definition, zero. Inclination could instead be measured with respect to another plane, such as the

text: Sun

text: 's equator or even

text: Jupiter

text: 's orbital plane, but the ecliptic is more practical for Earth-bound observers. Most planetary orbits in the Solar System have relatively small inclinations, both in relation to each other and to the Sun's equator. On the other hand, the

text: dwarf planet

text: s

text: Pluto

text: and

text: Eris

text: have inclinations to the ecliptic of 17° and 44° respectively, and the large

text: asteroid

text: Pallas

text: is inclined at 34°.

text: In the context of the magnetic field of the Sun, the term magnetogram refers to a pictorial representation of the spatial variations in strength of the solar magnetic field.  Magnetograms are often produced by exploiting the Zeeman effect (or, in some cases, the Hanle effect), which George Ellery Hale employed in the first demonstration that sunspots were magnetic in origin, in 1908.  Solar  magnetograms are produced by suitably instrumented telescopes referred to as magnetographs.  Some magnetographs can only measure the component of the magnetic field along the line of sight from the observer to the source (the field's "longitudinal" component).  One example of such a "line-of-sight" or "longitudinal" magnetograph is the Michelson Doppler Imager (MDI), a scientific instrument that takes magnetograms of the Sun in order to measure velocity and magnetic fields in the Sun's photosphere to learn about the convection zone and about the magnetic fields which control the structure of the solar corona.  A vector magnetograph also measures the component of the magnetic field perpendicular to the line of sight (the field's "transverse" component), from which all three components of the magnetic field vector can be deduced. Two examples include the National Solar Observatory's SOLIS instrument and the Helioseismic and Magnetic Imager aboard NASA's Solar Dynamics Observatory satellite.

text: In the context of the

text: magnetic field

text: of the

text: Sun

text: , the term magnetogram refers to a pictorial representation of the spatial variations in strength of the solar magnetic field.  Magnetograms are often produced by exploiting the

text: Zeeman effect

text: (or, in some cases, the

text: Hanle effect

text: ), which

text: George Ellery Hale

text: employed in the first demonstration that

text: sunspot

text: s were magnetic in origin, in 1908.  Solar  magnetograms are produced by suitably instrumented

text: telescope

text: s referred to as

text: magnetograph

text: s.  Some magnetographs can only measure the component of the

text: magnetic field

text: along the line of sight from the observer to the source (the field's "longitudinal" component).  One example of such a "line-of-sight" or "longitudinal" magnetograph is the

text: Michelson Doppler Imager

text: (MDI), a scientific instrument that takes magnetograms of the

text: Sun

text: in order to measure velocity and magnetic fields in the Sun's

text: photosphere

text: to learn about the

text: convection zone

text: and about the

text: magnetic fields

text: which control the structure of the solar

text: corona

text: .  A

text: vector magnetograph

text: also measures the component of the magnetic field perpendicular to the line of sight (the field's "transverse" component), from which all three components of the

text: magnetic field

text: vector can be deduced. Two examples include the

text: National Solar Observatory's

text: SOLIS instrument and the

text: Helioseismic and Magnetic Imager

text: aboard NASA's

text: Solar Dynamics Observatory

text: satellite.

text: The biggest changes to the Institute resulted from German unification with the retraction of two of the four directors of the institute in 1998 and 2004 after the retirement of Hagfors and Rosenbauer. The institute was renamed "Max Planck Institute of Solar System Research" in 2004 after the last director concerned with Ionosphere and Stratosphere research retired. The two remaining groups, of director S. Solanki dedicated to the sun and heliosphere and of U. Christensen dedicated to planets and comets form the present-day Institute.

text: The biggest changes to the Institute resulted from German unification with the retraction of two of the four directors of the institute in 1998 and 2004 after the retirement of Hagfors and Rosenbauer. The institute was renamed "Max Planck Institute of Solar System Research" in 2004 after the last director concerned with

text: Ionosphere

text: and

text: Stratosphere

text: research retired. The two remaining groups, of director

text: S. Solanki

text: dedicated to the

text: sun

text: and

text: heliosphere

text: and of U. Christensen dedicated to

text: planet

text: s and

text: comet

text: s form the present-day Institute.

text: Le Verrier's first work in astronomy was presented to the Académie des Sciences in September 1839, entitled Sur les variations séculaires des orbites des planètes (On the Secular Variations of the Orbits of the Planets). This work addressed the then most-important question in astronomy: the stability of the Solar System, first investigated by Laplace. He was able to derive some important limits on the motions of the system, but due to the inaccurately-known masses of the planets, his results were tentative.

text: Le Verrier's first work in astronomy was presented to the Académie des Sciences in September 1839, entitled Sur les variations séculaires des orbites des planètes (On the Secular Variations of the Orbits of the Planets). This work addressed the then most-important question in astronomy: the

text: stability of the Solar System

text: , first investigated by

text: Laplace

text: . He was able to derive some important limits on the motions of the system, but due to the inaccurately-known masses of the planets, his results were tentative.

text: The stability of the Solar System is a subject of much inquiry in astronomy. Though the planets have been stable when historically observed, and will be in the short term, their weak gravitational effects on one another can add up in unpredictable ways.For this reason (among others) the Solar System is stated to be chaotic,  and even the most precise long-term models for the orbital motion of the Solar System are not valid over more than a few tens of millions of years.

text: The stability of the Solar System is a subject of much inquiry in

text: astronomy

text: . Though the planets have been stable when historically observed, and will be in the short term, their weak gravitational effects on one another can add up in unpredictable ways.For this reason (among others) the

text: Solar System

text: is stated to be

text: chaotic

text: ,  and even the most precise long-term models for the orbital motion of the Solar System are not valid over more than a few tens of millions of years.

text: The vortex model of 1944, formulated by German physicist and philosopher Baron Carl Friedrich von Weizsäcker, which harkens back to the Cartesian model,  involved a pattern of turbulence-induced eddies in a Laplacian nebular disc. In it a suitable combination of clockwise rotation of each vortex and anti-clockwise rotation of the whole system can lead to individual elements moving around the central mass in Keplerian orbits so there would be little dissipation of energy due to the overall motion of the system but material would be colliding at high relative velocity in the inter-vortex boundaries and in these regions small roller-bearing eddies would coalesce to give annular condensations. It was much criticized as turbulence is a phenomenon associated with disorder and would not spontaneously produce the highly ordered structure required by the hypothesis. As well, it does not provide a solution to the angular momentum problem and does not explain lunar formation nor other very basic characteristics of the Solar System.<ref>Woolfson, M.M. 2000. The Origin and Evolution of universe and the Solar System completely considered that collision of the two suns produce the solar system and universe in the entire 100,00 years of the evolution.

text: The vortex model of 1944, formulated by German physicist and philosopher Baron

text: Carl Friedrich von Weizsäcker

text: , which harkens back to the Cartesian model,  involved a pattern of turbulence-induced eddies in a Laplacian nebular disc. In it a suitable combination of clockwise rotation of each vortex and anti-clockwise rotation of the whole system can lead to individual elements moving around the central mass in Keplerian orbits so there would be little dissipation of energy due to the overall motion of the system but material would be colliding at high relative velocity in the inter-vortex boundaries and in these regions small roller-bearing eddies would coalesce to give annular condensations. It was much criticized as turbulence is a phenomenon associated with disorder and would not spontaneously produce the highly ordered structure required by the hypothesis. As well, it does not provide a solution to the angular momentum problem and does not explain lunar formation nor other very basic characteristics of the Solar System.<ref>Woolfson, M.M. 2000. The Origin and Evolution of universe and the Solar System completely considered that collision of the two suns produce the solar system and universe in the entire 100,00 years of the evolution.

text: Metroid Prime Hunters takes place between Metroid Prime and Metroid Prime 2: Echoes, and is set within the Alimbic Cluster in the Tetra Galaxy, where it was once ruled by the Alimbic race. One day, the Alimbic race disappeared without warning, leaving artifacts scattered throughout the solar system. In the present, the dormant Alimbic race telepathically broadcasts a message to bounty hunters and other intelligent species, stating the key to the "ultimate power" resides in the Alimbic solar system. The solar system consists of two planets (Alinos and Arcterra) and two space stations (the Celestial Archives and the Vesper Defense Outpost).

text: Metroid Prime Hunters takes place between

text: Metroid Prime

text: and

text: Metroid Prime 2: Echoes

text: , and is set within the Alimbic Cluster in the Tetra Galaxy, where it was once ruled by the Alimbic race. One day, the Alimbic race disappeared without warning, leaving artifacts scattered throughout the solar system. In the present, the dormant Alimbic race telepathically broadcasts a message to bounty hunters and other intelligent species, stating the key to the "ultimate power" resides in the Alimbic solar system. The solar system consists of two planets (Alinos and Arcterra) and two space stations (the Celestial Archives and the Vesper Defense Outpost).

text: Eyes on the Solar System (EotSS) is computer simulation software created by the Jet Propulsion Laboratory (JPL) to present realistic simulated views of spacecraft, planets and other features within the Solar System.  Position and orientation of spacecraft and planets represented in the software are based on real data from JPL.  EotSS was released in 2010 and originally required download of plugin for rendering.  As of mid-2012, EotSS is Java based and is cross browser and cross platform compatible.

text: Eyes on the Solar System (EotSS) is computer simulation software created by the

text: Jet Propulsion Laboratory

text: (JPL) to present realistic simulated views of spacecraft, planets and other features within the

text: Solar System

text: .  Position and orientation of spacecraft and planets represented in the software are based on real data from JPL.  EotSS was released in 2010 and originally required download of plugin for rendering.  As of mid-2012, EotSS is Java based and is cross browser and cross platform compatible.

text: Planetary systems are generally believed to form as part of the same process that results in star formation. A protoplanetary disk forms by gravitational collapse of a molecular cloud, called a solar nebula,  and then evolves into a planetary system by collisions and gravitational capture. Radiation pressure can clear a region in the immediate vicinity of the star. As the formation process continues, radiation pressure continues to play a role in affecting the distribution of matter.  In particular, dust and grains can spiral into the star or escape the stellar system under the action of radiation pressure.

text: Planetary system

text: s are generally believed to form as part of the same process that results in

text: star formation

text: . A

text: protoplanetary disk

text: forms by gravitational collapse of a

text: molecular cloud

text: , called a

text: solar nebula

text: ,  and then evolves into a planetary system by collisions and gravitational capture. Radiation pressure can clear a region in the immediate vicinity of the star. As the formation process continues, radiation pressure continues to play a role in affecting the distribution of matter.  In particular, dust and grains can spiral into the star or escape the stellar system under the action of radiation pressure.

text: One possible inference is that the author visualized the universe as the hollow of a sphere, in which the inversion of the sun caused night at one end and day at the diametrically opposite end. However, at the same time, the verse also states that the sun does not actually set or rise. According to Subhash Kak, this implies that according to the author of the verse, the sun does not move and it is the earth that moves, suggesting heliocentrism and rotation of a spherical Earth. According to Jyoti Bhusan Das Gupta, this verse implies that the author "clearly understood that days and nights were local rather than a global phenomenon". Das Gupta adds that the text's interest in the sun's position appears to be "purely ritualistic", and the verse cannot be conclusively taken as an evidence of the author's recognition of the earth as a sphere. According to K. C. Chattopadhyaya, the verse simply implies that the sun has two sides: one bright and the other dark.

text: One possible inference is that the author visualized the universe as the hollow of a sphere, in which the inversion of the sun caused night at one end and day at the diametrically opposite end. However, at the same time, the verse also states that the sun does not actually set or rise. According to

text: Subhash Kak

text: , this implies that according to the author of the verse, the sun does not move and it is the earth that moves, suggesting

text: heliocentrism

text: and

text: rotation

text: of a

text: spherical Earth

text: . According to Jyoti Bhusan Das Gupta, this verse implies that the author "clearly understood that days and nights were local rather than a global phenomenon". Das Gupta adds that the text's interest in the sun's position appears to be "purely ritualistic", and the verse cannot be conclusively taken as an evidence of the author's recognition of the earth as a sphere. According to K. C. Chattopadhyaya, the verse simply implies that the sun has two sides: one bright and the other dark.

text: The following is a list of 456 extrasolar planets that were only detected by radial velocity method –– 31 confirmed and 323 candidates, sorted by orbital periods. Since none of these planets are transiting or directly observed, they do not have measured radii and generally their masses are only minimum. The true masses can be determined when astrometry calculates the inclination of the orbit.

text: The following is a list of 456 extrasolar planets that were only detected by

text: radial velocity method

text: –– 31 confirmed and 323 candidates, sorted by orbital periods. Since none of these planets are transiting or directly observed, they do not have measured radii and generally their masses are only minimum. The

text: true mass

text: es can be determined when

text: astrometry

text: calculates the inclination of the orbit.

text: Milanković put the Sun at the center of his theory, as the only source of heat and light in the Solar system. He considered three cyclical movements of the Earth: eccentricity (100,000-year cycle - Johannes Kepler, 1609), axial tilt (41,000-year cycle - from 22,1° to 24,5°; Presently, the Earth's tilt is 23.5° - Ludwig Pilgrim, 1904), and precession (23,000-year cycle - Hipparchus, 130 BC). Each cycle works on a different time scale and each affects the amount of solar energy received by the planets. Such changes in the geometry of an orbit lead to the changes in the insolation - quantity of heat received by any spot at the surface of a planet. These orbital variations, which are influenced by gravity of the Moon, Sun, Jupiter, and Saturn, are the basis of the Milankovitch cycle. His original contribution to celestial mechanics is called Milanković’s system of vector elements of planetary orbits. He reduced six Lagrangean-Laplacian elliptical elements to two vectors determining mechanics of planetary movements. The first specifies the planet’s orbital plane, the sense of revolution of the planet, and the orbital ellipse parameter; the second specifies the axis of the orbit in its plane and the orbital eccentricity. By applying those vectors he significantly simplified the calculation and directly obtained all the formulas of the classical theory of secular perturbations. Milanković in a simple but original manner, first deduced Newton’s law of gravitation from Kepler’s laws. Then Milankovich treated the two-body and the many-body problems of celestial mechanics. He accepted but corrected the Leverrier and Stockwell computation by using newer and more accurate values for the masses of the planets in the solar system.

text: Milanković put the Sun at the center of his theory, as the only source of heat and light in the Solar system. He considered three cyclical movements of the Earth:

text: eccentricity

text: (100,000-year cycle -

text: Johannes Kepler

text: , 1609),

text: axial tilt

text: (41,000-year cycle - from 22,1° to 24,5°; Presently, the Earth's tilt is 23.5° - Ludwig Pilgrim, 1904), and

text: precession

text: (23,000-year cycle -

text: Hipparchus

text: , 130 BC). Each cycle works on a different time scale and each affects the amount of solar energy received by the planets. Such changes in the geometry of an orbit lead to the changes in the

text: insolation

text: - quantity of heat received by any spot at the surface of a planet. These

text: orbital variations

text: , which are influenced by gravity of the

text: Moon

text: , Sun,

text: Jupiter

text: , and

text: Saturn

text: , are the basis of the

text: Milankovitch cycle

text: . His original contribution to celestial mechanics is called Milanković’s system of vector elements of planetary orbits. He reduced six

text: Lagrangean

text: Laplacian

text: elliptical elements to two vectors determining mechanics of planetary movements. The first specifies the planet’s orbital plane, the sense of revolution of the planet, and the orbital ellipse parameter; the second specifies the axis of the orbit in its plane and the orbital eccentricity. By applying those vectors he significantly simplified the calculation and directly obtained all the formulas of the classical theory of secular

text: perturbations

text: . Milanković in a simple but original manner, first deduced Newton’s law of gravitation from Kepler’s laws. Then Milankovich treated the two-body and the many-body problems of celestial mechanics. He accepted but corrected the

text: Leverrier

text: and

text: Stockwell

text: computation by using newer and more accurate values for the masses of the planets in the solar system.

text: In other animals, the gravity organs and eyes are strictly connected.  A fish, for instance, moves its eyes by reflex when its tail is moved.  Humans have semicircular canals, neck muscle  "stretch" receptors, and the utricle (gravity organ).  Though the semicircular canals cause most of the reflexes which are responsive to acceleration, the maintaining of balance is mediated by the stretch of neck muscles and the pull of gravity on the utricle (otolith organ) of the inner ear.

text: In other animals, the gravity organs and eyes are strictly connected.  A fish, for instance, moves its eyes by reflex when its tail is moved.  Humans have semicircular canals, neck muscle  "stretch" receptors, and the

text: utricle

text: (gravity organ).  Though the semicircular canals cause most of the reflexes which are responsive to acceleration, the maintaining of balance is mediated by the stretch of neck muscles and the pull of gravity on the utricle (otolith organ) of the inner ear.

text: In the Ptolemaic system, each planet is moved by a system of two spheres: one called its deferent; the other, its epicycle. The deferent is a circle whose center point, called the eccentric and marked in the diagram with an X, is removed from the Earth. The original purpose of the eccentric was to account for the differences of the lengths of the seasons (autumn is the shortest by a week or so), by placing the Earth away from the center of rotation of the rest of the universe. Another sphere, the epicycle, is embedded inside the deferent sphere and is represented by the smaller dotted line to the right. A given planet then moves around the epicycle at the same time the epicycle moves along the path marked by the deferent. These combined movements cause the given planet to move closer to and further away from the Earth at different points in its orbit, and explained the observation that planets slowed down, stopped, and moved backward in retrograde motion, and then again reversed to resume normal, or prograde, motion.

text: In the Ptolemaic system, each planet is moved by a system of two spheres:

text: one called its deferent; the other, its epicycle

text: . The deferent is a circle whose center point, called the eccentric and marked in the diagram with an X, is removed from the Earth. The original purpose of the eccentric was to account for the differences of the lengths of the seasons (autumn is the shortest by a week or so), by placing the Earth away from the center of rotation of the rest of the universe. Another sphere, the epicycle, is embedded inside the deferent sphere and is represented by the smaller dotted line to the right. A given planet then moves around the epicycle at the same time the epicycle moves along the path marked by the deferent. These combined movements cause the given planet to move closer to and further away from the Earth at different points in its orbit, and explained the observation that planets slowed down, stopped, and moved backward in

text: retrograde motion

text: , and then again reversed to resume normal, or prograde, motion.

text: 90377 Sedna is a large minor planet in the outer reaches of the Solar System that was, , at a distance of about 86 astronomical units (AU) from the Sun, about three times as far as Neptune. Spectroscopy has revealed that Sedna's surface composition is similar to that of some other trans-Neptunian objects, being largely a mixture of water, methane, and nitrogen ices with tholins. Its surface is one of the reddest among Solar System objects. It is most likely a dwarf planet.

text: 90377 Sedna is a large

text: minor planet

text: in the

text: outer reaches of the Solar System

text: that was, , at a distance of about 86

text: astronomical unit

text: s (AU) from the

text: Sun

text: , about three times as far as

text: Neptune

text: Spectroscopy

text: has revealed that Sedna's surface composition is similar to that of some other

text: trans-Neptunian objects

text: , being largely a mixture of water,

text: methane

text: , and

text: nitrogen

text: ices

text: with

text: tholin

text: s. Its surface is one of the

text: reddest

text: among Solar System objects. It is most

text: likely a dwarf planet

text: The nebula seems to be in an S-shape, but on closer inspection reveals to have extensions of the spiral arms, ending in a figure 8. The unusual shape may be due to the combination of other nebula, or it may have been formed by perforation of the original molecular cloud by powerful stellar winds and explosions.

text: The nebula seems to be in an

text: S-shape

text: , but on closer inspection reveals to have extensions of the spiral arms, ending in a figure 8. The unusual shape may be due to the combination of other nebula, or it may have been formed by perforation of the original molecular cloud by powerful stellar winds and explosions.

text: Moreover, the Pluto-Charon system moves in an ellipse around its barycenter with the Sun, as does the Earth-Moon system (and every other planet-moon system or moonless planet in the solar system). In both cases the barycenter is well within the body of the Sun.

text: Moreover, the Pluto-Charon system moves in an ellipse around its barycenter with the

text: Sun

text: , as does the Earth-Moon system (and every other planet-moon system or moonless planet in the solar system). In both cases the barycenter is well within the body of the Sun.

text: Hale–Bopp was the first comet where the noble gas argon was detected. Noble gases are chemically inert and highly volatile, and since different noble elements have different sublimation temperatures, they can be used for probing the temperature histories of the cometary ices. Krypton has a sublimation temperature of 16–20 K and was found to be depleted more than 25 times relative to the solar abundance, while argon with its higher sublimation temperature was enriched relative to the solar abundance. Together these observations indicate that the interior of Hale–Bopp has always been colder than 35–40 K, but has at some point been warmer than 20 K. Unless the solar nebula was much colder and richer in argon than generally believed, this suggests that the comet formed beyond Neptune in the Kuiper belt region and then migrated outward to the Oort cloud.

text: Hale–Bopp was the first comet where the

text: noble gas

text: argon

text: was detected. Noble gases are chemically inert and highly

text: volatile

text: , and since different noble elements have different

text: sublimation

text: temperatures, they can be used for probing the temperature histories of the cometary ices.

text: Krypton

text: has a sublimation temperature of 16–20 K and was found to be depleted more than 25 times relative to the solar abundance, while argon with its higher sublimation temperature was enriched relative to the solar abundance. Together these observations indicate that the interior of Hale–Bopp has always been colder than 35–40 K, but has at some point been warmer than 20 K. Unless the solar nebula was much colder and richer in argon than generally believed, this suggests that the comet formed beyond Neptune in the

text: Kuiper belt

text: region and then migrated outward to the

text: Oort cloud

text: This proof uses the fact that for any action of a (cyclic) group of prime order p, the only possible orbit sizes are 1 and p, which is immediate from the orbit stabilizer theorem.

text: This proof uses the fact that for any

text: action

text: of a (cyclic) group of prime order p, the only possible orbit sizes are 1 and p, which is immediate from the

text: orbit stabilizer theorem

text: Ketura Sun features the world's first fully automated solar panel cleaning system.

text: The lifetimes of these dust particles are very short compared to the lifetime of the Solar System. If one finds grains around a star that is older than about 10,000,000 years, then the grains must have been from recently released fragments of larger objects, i.e. they cannot be leftover grains from the protoplanetary disk (Backman, private communication). Therefore, the grains would be "later-generation" dust. The zodiacal dust in the Solar System is 99.9% later-generation dust and 0.1% intruding interstellar medium dust. All primordial grains from the Solar System's formation were removed long ago.

text: The lifetimes of these dust particles are very short compared to the lifetime of the Solar System. If one finds grains around a star that is older than about 10,000,000 years, then the grains must have been from recently released fragments of larger objects, i.e. they cannot be leftover grains from the

text: protoplanetary disk

text: (Backman, private communication). Therefore, the grains would be "later-generation" dust. The zodiacal dust in the Solar System is 99.9% later-generation dust and 0.1% intruding

text: interstellar medium

text: dust. All primordial grains from the Solar System's formation were removed long ago.

text: A typical example is Bode's law, which provides a simple numerical rule for the distances of the planets in the solar system from the Sun. Once the rule has been derived, through the trial and error matching of various rules with the observed data (exploratory data analysis), there are not enough planets remaining for a rigorous and independent test of the hypothesis (confirmatory data analysis). We have exhausted the natural phenomena. The agreement between data and the numerical rule should be no surprise, as we have deliberately chosen the rule to match the data.  If we are concerned about what Bode's law tells us about the cause system of planetary distribution then we demand confirmation that will not be available until better information about other planetary systems becomes available.

text: A typical example is

text: Bode's law

text: , which provides a simple numerical rule for the distances of the

text: planet

text: s in the

text: solar system

text: from the

text: Sun

text: . Once the rule has been derived, through the

text: trial and error

text: matching of various rules with the observed

text: data

text: (exploratory data analysis), there are not enough planets remaining for a rigorous and independent test of the

text: hypothesis

text: (confirmatory data analysis). We have exhausted the natural

text: phenomena

text: . The agreement between data and the numerical rule should be no surprise, as we have deliberately chosen the rule to match the data.  If we are concerned about what Bode's law tells us about the cause system of planetary distribution then we demand confirmation that will not be available until better information about other planetary systems becomes available.

text: The Moon is Earth's only permanent natural satellite. It is the fifth-largest natural satellite in the Solar System, and the largest among planetary satellites relative to the size of the planet that it orbits (its primary). It is the second-densest satellite among those whose densities are known (after Jupiter's satellite Io).

text: The Moon is Earth's only

text: permanent

text: natural satellite

text: . It is

text: the fifth-largest

text: natural satellite in the

text: Solar System

text: , and the largest among planetary satellites relative to the size of the planet that it orbits (its

text: primary

text: ). It is the second-

text: densest

text: satellite among those whose densities are known (after

text: Jupiter

text: 's satellite

text: Io

text: Earth's orbit is the path through which the Earth travels around the Sun. The average distance between the Earth and the Sun is 149.60 million kilometers (92.96 million miles), and a complete orbit occurs every  days (1 sidereal year), during which time Earth travels 940 million kilometers (584 million miles). Earth's orbit has an eccentricity of 0.0167. Earth's orbital motion gives an apparent movement of the Sun with respect to other stars at a rate of about 1° per day (or a Sun or Moon diameter every 12 hours) eastward as seen from Earth. Earth's orbital speed averages about 30 km/s (108,000 km/h; 67,000 mph), which is fast enough to cover the planet's diameter in seven minutes and the distance to the Moon in four hours.

text: Earth's orbit is the path through which the

text: Earth

text: travels around the

text: Sun

text: . The

text: average distance

text: between the Earth and the Sun is

text: 149.60 million kilometers (92.96 million miles)

text: , and a complete orbit occurs every  days (

text: 1 sidereal year

text: ), during which time Earth travels 940 million kilometers (584 million miles). Earth's orbit has an

text: eccentricity

text: of 0.0167. Earth's orbital motion gives an apparent movement of the Sun with respect to other stars at a rate of about 1° per day (or a Sun or Moon diameter every 12 hours) eastward as seen from Earth. Earth's

text: orbital speed

text: averages about 30 km/s (108,000 km/h; 67,000 mph), which is fast enough to cover the planet's diameter in seven minutes and the distance to the

text: Moon

text: in four hours.

text: The shape of an orbit is determined only by the centripetal forces at each point of the orbit, which are the forces acting perpendicular to the orbit.  By contrast, forces along the orbit change only the speed, but not the direction, of the velocity.

text: The shape of an

text: orbit

text: is determined only by the

text: centripetal force

text: s at each point of the orbit, which are the forces acting perpendicular to the orbit.  By contrast, forces along the orbit change only the speed, but not the direction, of the

text: velocity

text: After Copernicus proposed his heliocentric system, with the Earth in revolution around the Sun, it was possible to build a model of the whole Solar System without scale. To ascertain the scale, it is necessary only to measure one distance within the Solar System, e.g., the mean distance from the Earth to the Sun (now called an astronomical unit, or AU). When found by triangulation, this is referred to as the solar parallax, the difference in position of the Sun as seen from the Earth's centre and a point one Earth radius away, i. e., the angle subtended at the Sun by the Earth's mean radius. Knowing the solar parallax and the mean Earth radius allows one to calculate the AU, the first, small step on the long road of establishing the size and expansion age of the visible Universe.

text: After

text: Copernicus

text: proposed his

text: heliocentric system

text: , with the Earth in revolution around the Sun, it was possible to build a model of the whole Solar System without scale. To ascertain the scale, it is necessary only to measure one distance within the Solar System, e.g., the mean distance from the Earth to the Sun (now called an

text: astronomical unit

text: , or AU). When found by

text: triangulation

text: , this is referred to as the solar parallax, the difference in position of the Sun as seen from the Earth's centre and a point one Earth radius away, i. e., the angle subtended at the Sun by the Earth's mean radius. Knowing the solar parallax and the mean Earth radius allows one to calculate the AU, the first, small step on the long road of establishing the size and

text: expansion age

text: of the visible Universe.

text: An Orbital is similar to a ringworld but is much smaller and does not enclose its primary star within itself, instead orbiting the star in a more conventional manner, making it much more intrinsically stable than a ringworld.  Many different civilizations are known to use Orbitals sized according to the preferences of the builders; the Culture's Orbitals are approximately 10 million kilometres in circumference, which, together with their rotational speed, creates gravity and day-night cycles to normal Culture standard.  To put this another way, with a diameter of 3 million kilometres the orbital completes a full rotation once per standard Culture day to simulate normal Culture gravity via centrifugal force, and as the orbital is itself orbiting a star this in turn gives the day-night cycle. They have widths varying between one thousand and six thousand kilometres, giving them a surface area of between 20 and 120 times that of the Earth (but comprising significantly less mass).

text: An Orbital is similar to a

text: ringworld

text: but is much smaller and does not enclose its primary star within itself, instead orbiting the star in a more conventional manner, making it much more intrinsically stable than a ringworld.  Many different civilizations are known to use Orbitals sized according to the preferences of the builders; the Culture's Orbitals are approximately 10 million kilometres in circumference, which, together with their rotational speed, creates gravity and day-night cycles to normal Culture standard.  To put this another way, with a diameter of 3 million kilometres the orbital completes a full rotation once per standard Culture day to simulate normal Culture gravity via

text: centrifugal force

text: , and as the orbital is itself orbiting a star this in turn gives the day-night cycle. They have widths varying between one thousand and six thousand kilometres, giving them a surface area of between 20 and 120 times that of the Earth (but comprising significantly less mass).

text: In contrast, humanity somehow missed developing gravity technology, and its unfocused expenditure of creativity and resources thus resulted in less immediately rewarding but ultimately more versatile applications and development of a very wide range of knowledge - medicine, heavy industry, electric motors, computers, nuclear power, etc. But without gravity technology, they were restricted to a single solar system, and until recently a single planet.

text: In contrast, humanity somehow missed developing gravity technology, and its unfocused expenditure of creativity and resources thus resulted in less immediately rewarding but ultimately more versatile applications and development of a very wide range of knowledge -

text: medicine

text: heavy industry

text: electric motor

text: s,

text: computers

text: nuclear power

text: , etc. But without gravity technology, they were restricted to a single solar system, and until recently a single planet.

text:
|-| Photovoltaic power systems and components:
Top: solar string inverter and other BOS components Solar array on rooftop in Hong Kong, China BIPV on balcony in Helsinki, Finland
Middle: rooftop system in Boston, United States Westmill solar park in the United Kingdom Dual axis tracker with CPV modules Topaz, one of the world’s largest solar power station, as seen from space
Bottom: commercial rooftop PV system of about 400 kW Power plant on Mt. Komekura, Japan Solar PV system on Germany's highest mountain-top|}

text: |-| Photovoltaic power systems and components:<br>Top: solar string

text: inverter

text: and other

text: BOS

text: components

text: Solar array

text: on rooftop in Hong Kong, China

text: BIPV

text: on balcony in Helsinki, Finland<br>Middle:

text: rooftop system

text: in Boston, United States Westmill

text: solar park

text: in the United Kingdom Dual axis

text: tracker

text: with

text: CPV

text: modules

text: Topaz

text: , one of the

entity_section: World's largest photovoltaic power stations

text: world’s largest

text: solar power station, as seen from space<br>Bottom: commercial rooftop PV system of about 400

text: kW

text: Power plant

text: on Mt. Komekura, Japan Solar PV system on Germany's highest mountain-top|}

text: "Center" is well-defined in a Flat Earth model.  A flat earth would have a definite geographic center.  There would also be a unique point at the exact center of a spherical firmament (or a firmament that was a half-sphere).

text: "Center" is well-defined in a Flat Earth model.  A flat earth would have a definite geographic center.  There would also be a unique point at the exact center of a spherical

text: firmament

text: (or a firmament that was a half-sphere).

text: The Cybermen mention having encountered the Doctor previously on "Planet 14".  The identity of "Planet 14" is uncertain, and has been the subject of much fan discussion and speculation. In an essay in About Time, a critical analysis of classic Doctor Who, Lawrence Miles and Tat Wood suggest that Planet 14 may be Telos, placing that planet as the fourteenth in the Solar System, after Mercury, Venus, Earth, Mondas, Mars, the time-looped planet mentioned in Image of the Fendahl, Jupiter, Saturn, Uranus, Neptune, Pluto, "Cassius" (mentioned in The Sun Makers as a planet beyond Pluto) and "Xena" (a name popularly used for the dwarf planet Eris prior to its official naming; in the essay, Miles and Wood confuse it with Sedna, another trans-Neptunian object discovered by the same team of astronomers).

text: The Cybermen mention having encountered the Doctor previously on "Planet 14".  The identity of "Planet 14" is uncertain, and has been the subject of much fan discussion and speculation. In an essay in About Time, a critical analysis of classic Doctor Who,

text: Lawrence Miles

text: and

text: Tat Wood

text: suggest that Planet 14 may be

text: Telos

text: , placing that planet as the fourteenth in the

text: Solar System

text: , after

text: Mercury

text: Venus

text: Earth

text: Mondas

text: Mars

text: , the time-looped planet mentioned in

text: Image of the Fendahl

text: Jupiter

text: Saturn

text: Uranus

text: Neptune

text: Pluto

text: , "Cassius" (mentioned in

text: The Sun Makers

text: as a planet beyond Pluto) and "Xena" (a name popularly used for the dwarf planet

text: Eris

text: prior to its official naming; in the essay, Miles and Wood confuse it with

text: Sedna

text: , another

text: trans-Neptunian object

text: discovered by the same team of astronomers).

text: If all Solar System bodies were point masses, or were rigid bodies having spherically symmetric mass distributions, then an invariable plane defined on orbits alone would be truly invariable and would constitute an inertial frame of reference. But almost all are not, allowing the transfer of a very small amount of momenta from axial rotations to orbital revolutions due to tidal friction and to bodies being non-spherical. This causes a change in the magnitude of the orbital angular momentum, as well as a change in its direction (precession) because the rotational axes are not parallel to the orbital axes. Nevertheless, these changes are exceedingly small compared to the total angular momenta of the system (which is conserved despite these effects, ignoring the even much tinier amounts of angular momentum ejected in material and gravitational waves leaving the Solar System, and the extremely tiny torques exerted on the Solar System by other stars, etc.), and for almost all purposes the plane defined on orbits alone can be considered invariable when working in Newtonian dynamics.

text: If all Solar System bodies were point masses, or were rigid bodies having spherically symmetric mass distributions, then an invariable plane defined on orbits alone would be truly invariable and would constitute an inertial frame of reference. But almost all are not, allowing the transfer of a very small amount of momenta from axial rotations to orbital revolutions due to tidal friction and to bodies being non-spherical. This causes a change in the magnitude of the orbital angular momentum, as well as a change in its direction (precession) because the rotational axes are not parallel to the orbital axes. Nevertheless, these changes are exceedingly small compared to the total angular momenta of the system (which is conserved despite these effects, ignoring the even much tinier amounts of angular momentum ejected in material and gravitational waves leaving the Solar System, and the extremely tiny torques exerted on the Solar System by other stars, etc.), and for almost all purposes the plane defined on orbits alone can be considered invariable when working in

text: Newtonian dynamics

text: The result of U-corrected Pb-Pb dating has produced ages of 4567.35 ± 0.28 My for CAIs (A) and chondrules with ages between 4564.71 ± 0.30 and 4567.32 ± 0.42 My (B and C) (see figure). This supports the idea that CAIs crystallization and chondrule formation occurred around the same time during the formation of the solar system. However, chondrules continued to form for approximately 3 My after CAIs. Hence the best age for the original formation of the solar system is 4567.7 My. This date also represents the time of initiation of planetary accretion. Successive collisions between accreted bodies led to the formation of larger and larger planetesimals, finally forming the earth-moon system in a giant impact event.

text: The result of U-corrected Pb-Pb dating has produced ages of 4567.35 ± 0.28 My for CAIs (A) and chondrules with ages between 4564.71 ± 0.30 and 4567.32 ± 0.42 My (B and C) (see figure). This supports the idea that CAIs crystallization and chondrule formation occurred around the same time during the formation of the solar system. However, chondrules continued to form for approximately 3 My after CAIs. Hence the best age for the original formation of the solar system is 4567.7 My. This date also represents the time of initiation of

text: planetary accretion

text: . Successive collisions between accreted bodies led to the formation of larger and larger planetesimals, finally forming the earth-moon system in a giant impact event.

text: The compromises of living where you like and liking where you live; of doing what you like and liking what you do; and, of having the child you like and liking the child you have -- these do not make choices easier.  Do we love the people we love and love the people we love -- both?  Green theory does not always distinguish public space from private space. As for political ideologies and Green theory, Timothy O'Riordan (1990) in "Major Projects and the Environment" in Geographical Journal, indicates there to be "dry greens" (perhaps conservative and market centered), "shallow greens" (perhaps liberal and sustainable development centered), and "deep greens" (perhaps radical and ecosystem or earth centered).  This, of course, may be an oversimplification.  "Dry Greens" may be the least appreciated environmentalists and might not even be given that title.  However, a very good economic treatment is given in "The Plundered Planet" by Paul Collier (2010).  Collier may put the plight of the bottom billion (poorest and worst off people) on the planet above environmentalism.  He believes protecting the viability of the planet and the bottom billion must both be done.  Green theorists, of course, emphasize equality such that the bottom billion are equal to the top billion.  How that works out is  challenging.  If the planet does need a billion less people, then there is no agreed upon way of choosing.  Market solution would include rising food prices and only those with ability to pay survive.  Each culture, religion, and academic discipline has developed and produced different solutions to the "Who survives?" conundrum.

text: Proposals for the study of planets external to the Solar System  include; the evaluation of the most effective means for the direct studies of exoplanets provided affirmation for the use of starshades. Planet Hunter  Deep search of 65 nearby stars for Earth analogs.  Mark Clampin/Goddard Space flight centre - Extrasolar planet imaging coronograph-to produce fundamental physical characteristics of giant planets in other planetary systems. Detecting Extrasolar Planets by Sharing the Burden

text: Proposals for the study of planets external to the Solar System  include; the evaluation of the most effective means for the

text: direct studies of exoplanets

text: provided affirmation for the use of starshades. Planet Hunter  Deep search of 65 nearby stars for Earth analogs.  Mark Clampin/Goddard Space flight centre - Extrasolar planet imaging coronograph-to produce fundamental physical characteristics of

text: giant planet

text: s in other

text: planetary system

text: s. Detecting Extrasolar Planets by Sharing the Burden

text: The planetary systems of stars other than the Sun and the Solar System are a staple element in much science fiction. Tau Ceti is the second closest main sequence star to the Sun (after Alpha Centauri A) having spectral class G, making it a popular story setting or system of origin in science fiction tales. The Sun, itself of spectral class G, provides an obvious model for the possibility that the star might harbor worlds capable of supporting life. But Tau Ceti, weighing in at ~0.78 , is metal-poor and so is thought to be unlikely to host rocky planets (see Destination: Void by Frank Herbert below); on the other hand, observations have detected more than ten times as much dust around the star than exists in the Solar System, a condition tending to enhance the probability of such bodies. Since the star's luminosity is barely 55% that of the Sun, those planets would need to circle it at the orbital radius of Venus in order to match the insolation received by the Earth. (See Time for the Stars by Robert Heinlein below.)

text: The

text: planetary system

text: s of

text: star

text: s other than the

text: Sun

text: and the

text: Solar System

text: are a staple element in much

text: science fiction

text: Tau Ceti

text: is the second closest

text: main sequence

text: star to the Sun (after

text: Alpha Centauri A

text: ) having

text: spectral class G

text: , making it a popular story setting or system of origin in science fiction tales. The Sun, itself of spectral class G, provides an obvious model for the possibility that the star might harbor worlds capable of supporting life. But Tau Ceti, weighing in at ~0.78 , is metal-poor and so is thought to be unlikely to host rocky planets (see

text: Destination: Void

text: by Frank Herbert below); on the other hand, observations have detected more than ten times as much dust around the star than exists in the Solar System, a condition tending to enhance the probability of such bodies. Since the star's luminosity is barely 55% that of the

text: Sun

text: , those planets would need to circle it at the orbital radius of

text: Venus

text: in order to match the

text: insolation

text: received by the Earth. (See

text: Time for the Stars

text: by Robert Heinlein below.)

text: Universe: The Definitive Visual Guide is a 528-page, non-fiction book by nine British co-authors (listed alphabetically below) with a short Foreword by Sir Martin Rees, first published in 2005. The book is divided into three sections, beginning with an introduction to theories of the Universe, space exploration, Earth's view of space and how the Universe will end. The second section, "Guide to the Universe," contains information on the Sun and the Solar System, as well as the Milky Way and other types of galaxies. The last section, "The Night Sky," has full-page maps and charts of the night sky for both northern and southern viewers as well as a comprehensive list of the constellations. The book contains full-colour pictures, maps, and probe photographs. There are in-depth looks at features of planets in the Solar System, such as Venus's craters and Mars's ridges. There are also captions describing the scientists and stories behind various discoveries. The book was produced in London, England, by Dorling Kindersley  and is published internationally. A revised and updated edition was published in September 2007, including recent developments such as the reclassification of Pluto as a dwarf planet. In October 2012, the book was revised for a third time adding newly discovered information about planets in other planetary systems and water on Mars.

text: Universe: The Definitive Visual Guide is a 528-page, non-fiction book by nine British co-authors (listed alphabetically below) with a short Foreword by

text: Sir Martin Rees

text: , first published in 2005. The book is divided into three sections, beginning with an introduction to theories of the Universe, space exploration, Earth's view of space and how the Universe will end. The second section, "Guide to the Universe," contains information on the

text: Sun

text: and the

text: Solar System

text: , as well as the

text: Milky Way

text: and other types of

text: galaxies

text: . The last section, "The Night Sky," has full-page maps and charts of the night sky for both northern and southern viewers as well as a comprehensive list of the

text: constellation

text: s. The book contains full-colour pictures, maps, and probe photographs. There are in-depth looks at features of

text: planet

text: s in the Solar System, such as

text: Venus

text: 's

text: crater

text: s and

text: Mars

text: 's ridges. There are also captions describing the scientists and stories behind various discoveries. The book was produced in London, England, by Dorling Kindersley  and is published internationally. A revised and updated edition was published in September 2007, including recent developments such as the reclassification of

text: Pluto

text: as a

text: dwarf planet

text: . In October 2012, the book was revised for a third time adding newly discovered information about

text: planets

text: in other

text: planetary system

text: s and

text: water on Mars

text: Other large CSP facilities include the 354 megawatt (MW) Solar Energy Generating Systems power installation in the USA, Solnova Solar Power Station (Spain, 150 MW), Andasol Solar Power Station (Spain, 150 MW) and the first part of Shams solar power station (United Arab Emirates, 100 MW). Other large PV power stations include the 320 MW Longyangxia Dam Solar Park in China, the 345 MW Charanka Solar Park in India, and the 166 MW Solarpark Meuro in Germany.

text: Other large CSP facilities include the 354

text: megawatt

text: (MW)

text: Solar Energy Generating Systems

text: power installation in the USA,

text: Solnova Solar Power Station

text: (Spain, 150 MW),

text: Andasol Solar Power Station

text: (Spain, 150 MW) and the first part of

text: Shams solar power station

text: United Arab Emirates

text: , 100 MW). Other large PV power stations include the 320 MW Longyangxia Dam Solar Park in China, the 345 MW

text: Charanka Solar Park

text: in

text: India

text: , and the 166 MW

text: Solarpark Meuro

text: in Germany.

text: Ptolemy's epicyclic solar system (still 300 years in the future from the apparent date of the mechanism), carried forward with more epicycles, was more accurate predicting the positions of planets than the view of Copernicus, until Kepler introduced the possibility that orbits are ellipses.

text: Pluto (minor-planet designation: 134340 Pluto) is a dwarf planet in the Kuiper belt, a ring of bodies beyond Neptune. It was the first Kuiper belt object to be discovered. It is the largest and second-most-massive known dwarf planet in the Solar System and the ninth-largest and tenth-most-massive known object directly orbiting the Sun. It is the largest known trans-Neptunian object by volume but is less massive than Eris, a dwarf planet in the scattered disc. Like other Kuiper belt objects, Pluto is primarily made of ice and rock and is relatively small—about one-sixth the mass of the Moon and one-third its volume. It has a moderately eccentric and inclined orbit during which it ranges from 30 to 49 astronomical units or AU (4.4–7.4 billion km) from the Sun. This means that Pluto periodically comes closer to the Sun than Neptune, but a stable orbital resonance with Neptune prevents them from colliding.  Light from the Sun takes about 5.5 hours to reach Pluto at its average distance (39.5 AU).

text: Pluto (

text: minor-planet designation

text: : 134340 Pluto) is a

text: dwarf planet

text: in the

text: Kuiper belt

text: , a ring of

text: bodies beyond Neptune

text: . It was the first Kuiper belt object to be discovered. It is the largest and second-most-massive known dwarf planet in the

text: Solar System

text: and the ninth-largest and tenth-most-massive known object directly orbiting the

text: Sun

text: . It is the largest known trans-Neptunian object by volume but is less massive than

text: Eris

text: , a dwarf planet in the

text: scattered disc

text: . Like other Kuiper belt objects, Pluto is primarily made of ice and rock and is relatively small—about one-sixth the mass of the

text: Moon

text: and one-third its volume. It has a moderately

text: eccentric

text: and inclined orbit during which it ranges from 30 to 49

text: astronomical unit

text: s or AU (4.4–7.4 billion km) from the Sun. This means that Pluto periodically comes closer to the Sun than

text: Neptune

text: , but a stable

text: orbital resonance

text: with Neptune prevents them from colliding.  Light from the Sun takes about 5.5 hours to reach Pluto at its average distance (39.5 AU).

text: The vast majority of the Solar System consists of a near-vacuum known as the interplanetary medium. Along with light, the Sun radiates a continuous stream of charged particles (a plasma) known as the solar wind. This stream of particles spreads outwards at roughly 1.5 million kilometres per hour, creating a tenuous atmosphere that permeates the interplanetary medium out to at least 100 AU (see ). Activity on the Sun's surface, such as solar flares and coronal mass ejections, disturb the heliosphere, creating space weather and causing geomagnetic storms. The largest structure within the heliosphere is the heliospheric current sheet, a spiral form created by the actions of the Sun's rotating magnetic field on the interplanetary medium.

text: The vast majority of the Solar System consists of a near-

text: vacuum

text: known as the

text: interplanetary medium

text: . Along with

text: light

text: , the Sun radiates a continuous stream of charged particles (a

text: plasma

text: ) known as the

text: solar wind

text: . This stream of particles spreads outwards at roughly 1.5 million kilometres per hour, creating a tenuous atmosphere that permeates the interplanetary medium out to at least 100 AU (see ). Activity on the Sun's surface, such as

text: solar flare

text: s and

text: coronal mass ejection

text: s, disturb the heliosphere, creating

text: space weather

text: and causing

text: geomagnetic storm

text: s. The largest structure within the heliosphere is the

text: heliospheric current sheet

text: , a spiral form created by the actions of the Sun's rotating magnetic field on the interplanetary medium.

text: While the new system has seemingly narrowed the gap between the calendar's solar and lunar years, it has not made the calendar more accurate when compared against the actual tropical year. Indeed, it is slightly worse than the old system. (The Thandeikta solar year is about 23 minutes 51.4304 seconds ahead of the mean solar year whereas Makaranta is about 23 minutes 50.8704 seconds ahead.) As a result, the calendar has kept on drifting away from the actual solar year. The calendarists have periodically resorted to modifying its intercalation schedule, based on apparent reckoning, to keep pace, at the expense of making publishing future calendars more than a few years out all but impossible.

text: The solar system of Magical Starsign consists of 6 planets: the planets of fire, wood, wind, water, earth, and another small planet on the fringes of the solar system called Kovomaka. Kovomaka houses the Will-O-Wisp academy of magic, where 6 aspiring magicians are studying in the same class under the guidance of their teacher, Miss Madeline. One day, Principal Biscotti receives word that Master Kale, a graduate of the academy, has become the leader of the space pirates, and is planning to destroy the solar system. He sends Miss Madeline out into space on a mission to prevent Master Kale from achieving his evil plans, but loses all contact with her shortly afterwards. 3 months later, Lassi, one of the current students in the academy, discovers a small spaceship hidden on the roof of the academy building, and goes off into space in search of Miss Madeline. The hero of the story pursues Lassi in another spaceship, but is forced to crash land on another planet. The player must reunite with the other 5 classmates, rescue Miss Madeline, and derail Master Kale's evil plans in a wild journey across outer-space.

text: Another proposal called for using solar panels to provide electrical power to the spacecraft. The panels would be inflatable, reducing their mass. Although advancements in solar panel technology means it should be possible to achieve sufficient power at the distance of Neptune, the high cost of providing the solar panels would possibly eliminate the idea of using solar cells. This design would presumably also use conventional thrusters, because the dim sunlight in the outer Solar System would probably be insufficient to power an ion propulsion system.

text: Another proposal called for using

text: solar panel

text: s to provide electrical power to the spacecraft. The panels would be inflatable, reducing their mass. Although advancements in solar panel technology means it should be possible to achieve sufficient power at the distance of Neptune, the high cost of providing the solar panels would possibly eliminate the idea of using solar cells. This design would presumably also use conventional thrusters, because the dim sunlight in the outer Solar System would probably be insufficient to power an

text: ion propulsion

text: system.

text: 2312 is a 2012 science fiction novel written by Kim Stanley Robinson. It is set in the year 2312 when society has spread out across the solar system. The novel won the 2013 Nebula Award for Best Novel.

text: 2312 is a 2012

text: science fiction

text: novel written by

text: Kim Stanley Robinson

text: . It is set in the year 2312 when society has spread out across the solar system. The novel won the 2013

text: Nebula Award for Best Novel

text: To travel quickly to and from different planets/space stations in the same system, the SPEC system is used. It multiplies the engine speed of the player’s spacecraft, causing the ship to reach high speeds, allowing the player to quickly travel to different locations in a solar system. However, the number of times it multiplies the engine speed is limited by gravity: The closer the player’s ship is to a planet/space station, the less the speed is multiplied. After the player waits, and gets farther away from the gravity of the planet/station, the SPEC drive will “ramp up”, and the player’s ship will stretch and star streaks will appear, until the player’s spacecraft slows down due to gravity, or the player deactivates the SPEC drive.

text: To travel quickly to and from different planets/space stations in the same system, the SPEC system is used. It multiplies the

text: engine

text: speed

text: of the player’s spacecraft, causing the ship to reach high speeds, allowing the player to quickly travel to different locations in a

text: solar system

text: . However, the number of times it multiplies the engine speed is limited by

text: gravity

text: : The closer the player’s ship is to a planet/space station, the less the speed is multiplied. After the player waits, and gets farther away from the gravity of the planet/station, the SPEC drive will “ramp up”, and the player’s ship will stretch and star streaks will appear, until the player’s spacecraft slows down due to gravity, or the player deactivates the SPEC drive.

text: During the Late Middle Ages, Bishop Nicole Oresme discussed the possibility that the Earth rotated on its axis, while Cardinal Nicholas of Cusa in his Learned Ignorance asked whether there was any reason to assert that the Sun (or any other point) was the center of the universe.  In parallel to a mystical definition of God, Cusa wrote that "Thus the fabric of the world (machina mundi) will quasi have its center everywhere and circumference nowhere."

text: During the

text: Late Middle Ages

text: , Bishop

text: Nicole Oresme

text: discussed the possibility that the Earth rotated on its axis, while Cardinal

text: Nicholas of Cusa

text: in his

text: Learned Ignorance

text: asked whether there was any reason to assert that the Sun (or any other point) was the center of the universe.  In parallel to a mystical definition of God, Cusa wrote that "Thus the fabric of the world (machina mundi) will quasi have its center everywhere and circumference nowhere."

text: There do exist orbits within these empty regions where objects can survive for the age of the Solar System. These resonances occur when Neptune's orbital period is a precise fraction of that of the object, such as 1:2, or 3:4. If, say, an object orbits the Sun once for every two Neptune orbits, it will only complete half an orbit by the time Neptune returns to its original position. The most heavily populated resonance in the Kuiper belt, with over 200 known objects, is the 2:3 resonance. Objects in this resonance complete 2 orbits for every 3 of Neptune, and are known as plutinos because the largest of the known Kuiper belt objects, Pluto, is among them. Although Pluto crosses Neptune's orbit regularly, the 2:3 resonance ensures they can never collide. The 3:4, 3:5, 4:7 and 2:5 resonances are less populated.

text: There do exist orbits within these empty regions where objects can survive for the age of the Solar System. These

text: resonances

text: occur when Neptune's orbital period is a precise fraction of that of the object, such as 1:2, or 3:4. If, say, an object orbits the Sun once for every two Neptune orbits, it will only complete half an orbit by the time Neptune returns to its original position. The most heavily populated resonance in the Kuiper belt, with over 200 known objects, is the 2:3 resonance. Objects in this resonance complete 2 orbits for every 3 of Neptune, and are known as

text: plutino

text: s because the largest of the known Kuiper belt objects,

text: Pluto

text: , is among them. Although Pluto crosses Neptune's orbit regularly, the 2:3 resonance ensures they can never collide. The 3:4, 3:5, 4:7 and 2:5 resonances are less populated.

text: The planet HD 99109 b has an orbit comparable in eccentricity to the planet Mars in the Solar System but has a mass at least half that of Jupiter. Stability analysis reveals that Earth-size planets could have stable orbits in the planet's Trojan points, located 60 degrees ahead and behind the planet's position in its orbit.

text: The planet HD 99109 b has an orbit comparable in eccentricity to the planet

text: Mars

text: in the

text: Solar System

text: but has a mass at least half that of

text: Jupiter

text: . Stability analysis reveals that Earth-size planets could have stable orbits in the planet's

text: Trojan points

text: , located 60 degrees ahead and behind the planet's position in its orbit.

text: The earliest scientific models of the Universe were developed by ancient Greek and Indian philosophers and were geocentric, placing the Earth at the center of the Universe. Over the centuries, more precise astronomical observations led Nicolaus Copernicus (1473–1543) to develop the heliocentric model with the Sun at the center of the Solar System. In developing the law of universal gravitation, Sir Isaac Newton (NS: 1643–1727) built upon Copernicus's work as well as observations by Tycho Brahe (1546–1601) and Johannes Kepler's (1571–1630) laws of planetary motion. Further observational improvements led to the realization that our Solar System is located in the Milky Way galaxy and is one of many solar systems and galaxies. It is assumed that galaxies are distributed uniformly and the same in all directions, meaning that the Universe has neither an edge nor a center. Discoveries in the early 20th century have suggested that the Universe had a beginning and that it is expanding at an increasing rate. The majority of mass in the Universe appears to exist in an unknown form called dark matter.

text: The earliest scientific models of the Universe were developed by ancient Greek and Indian philosophers and were

text: geocentric

text: , placing the Earth at the center of the Universe. Over the centuries, more precise astronomical observations led

text: Nicolaus Copernicus

text: (1473–1543) to develop the

text: heliocentric model

text: with the Sun at the center of the

text: Solar System

text: . In developing the

text: law of universal gravitation

text: Sir Isaac Newton

text: NS

text: : 1643–1727) built upon Copernicus's work as well as observations by

text: Tycho Brahe

text: (1546–1601) and

text: Johannes Kepler

text: 's (1571–1630)

text: laws of planetary motion

text: . Further observational improvements led to the realization that our Solar System is located in the

text: Milky Way

text: galaxy and is one of many solar systems and galaxies. It is assumed that galaxies are distributed uniformly and the same in all directions, meaning that the Universe has neither an edge nor a center. Discoveries in the early 20th century have suggested that the Universe had a beginning and that it is expanding at an increasing rate. The majority of mass in the Universe appears to exist in an unknown form called

text: dark matter

text: is a planetoid in the outer reaches of the Solar System.  It is the object with the farthest known perihelion (closest approach to the Sun) in the Solar System, farther than Sedna's. Its discovery was announced on 26 March 2014. It has an absolute magnitude (H) of 4.0, which makes it likely to be a dwarf planet, and it is accepted as a dwarf planet by some.  It is expected to be about half the size of Sedna and similar in size to Huya.  The similarity of 2012 VP113's orbit to the orbits of other known extreme trans-Neptunian objects led Scott Sheppard and Chad Trujillo to suggest that an undiscovered super-Earth in the outer Solar System is shepherding these distant objects into similar type orbits.

text: is a

text: planetoid

text: in the

text: outer reaches of the Solar System

text: .  It is the object with the farthest known

text: perihelion

text: (closest approach to the Sun) in the Solar System, farther than

text: Sedna

text: 's. Its discovery was announced on 26 March 2014. It has an

text: absolute magnitude (H)

text: of 4.0, which makes it

text: likely to be a dwarf planet

text: , and it is accepted as a dwarf planet by some.  It is expected to be about half the size of

text: Sedna

text: and similar in size to

text: Huya

text: .  The similarity of 2012 VP113's orbit to the orbits of other known extreme trans-Neptunian objects led

text: Scott Sheppard

text: and

text: Chad Trujillo

text: to suggest that an undiscovered super-Earth in the outer Solar System is shepherding these distant objects into similar type orbits.

text: The inclination is one of the six orbital elements describing the shape and orientation of a celestial orbit. It is the angular distance of the orbital plane from the plane of reference (usually the primary's equator or the ecliptic), normally stated in degrees. In the Solar System, orbital inclination is usually stated with respect to Earth's orbit.

text: The inclination is one of the six

text: orbital elements

text: describing the shape and orientation of a celestial

text: orbit

text: . It is the

text: angular

text: distance of the orbital plane from the

text: plane of reference

text: (usually the primary's

text: equator

text: or the

text: ecliptic

text: ), normally stated in

text: degrees

text: . In the Solar System, orbital inclination is usually stated with respect to Earth's orbit.

text: Descartes espoused mechanical philosophy, a form of natural philosophy popular in the 17th century. He thought everything physical in the universe to be made of tiny "corpuscles" of matter. Corpuscularianism is closely related to atomism. The main difference was that Descartes maintained that there could be no vacuum, and all matter was constantly swirling to prevent a void as corpuscles moved through other matter. The World presents a corpuscularian cosmology in which swirling vortices explain, among other phenomena, the creation of the Solar System and the circular motion of planets around the Sun.

text: Descartes espoused

text: mechanical philosophy

text: , a form of

text: natural philosophy

text: popular in the 17th century. He thought everything physical in the universe to be made of tiny "corpuscles" of matter.

text: Corpuscularianism

text: is closely related to

text: atomism

text: . The main difference was that Descartes maintained that there could be no

text: vacuum

text: , and all matter was constantly swirling to prevent a void as corpuscles moved through other matter. The World presents a corpuscularian cosmology in which swirling vortices explain, among other phenomena, the creation of the

text: Solar System

text: and the circular motion of planets around the

text: Sun

text: Kepler had found that the distance between the planets increased in proportion to their distance from the Sun, and this led him to assume that the universe was created with a divine harmony, and that the size of the planets would increase in the same way. He had written in 1618, "Nothing is more in concord with nature than that the order of magnitude should be the same as the order of the spheres". When Horrocks's measurements of Venus, coupled with some erroneous measurements by Kepler and Gassendi, seemed to confirm this, Horrocks tentatively proposed a law which stated that all planets (with the exception of Mars) would be the same angular size when viewed from the Sun, this being 28 arc seconds. This meant that the assumption Kepler had made about the sizes of the planets held true, and led Horrocks to the false conclusion that the distance between each planet and the Sun was about 15,000 times its radius. Thus he estimated the average distance from the Earth to the Sun to be approximately 60 million miles (97 million km), suggesting that the Solar System was ten times larger than traditionally believed. His figure was much lower than the 93 million miles (150 million km) that the Astronomical Unit is known to be today, but, despite being based on a false premise, was more accurate than any suggested up to that time.

text: Kepler had found that the distance between the planets increased in proportion to their distance from the Sun, and this led him to assume that the universe was created with a divine harmony, and that the size of the planets would increase in the same way. He had written in 1618, "Nothing is more in concord with nature than that the order of magnitude should be the same as the order of the spheres". When Horrocks's measurements of Venus, coupled with some erroneous measurements by Kepler and Gassendi, seemed to confirm this, Horrocks tentatively proposed a law which stated that all planets (with the exception of Mars) would be the same angular size when viewed from the Sun, this being 28 arc seconds. This meant that the assumption Kepler had made about the sizes of the planets held true, and led Horrocks to the false conclusion that the distance between each planet and the Sun was about 15,000 times its radius. Thus he estimated the average distance from the Earth to the Sun to be approximately 60 million miles (97 million km), suggesting that the Solar System was ten times larger than traditionally believed. His figure was much lower than the 93 million miles (150 million km) that the

text: Astronomical Unit

text: is known to be today, but, despite being based on a false premise, was more accurate than any suggested up to that time.

text: The modern understanding of planetary motion arose from the combined efforts of astronomer Tycho Brahe and physicist Johannes Kepler in the 16th century. Tycho is credited with extremely accurate measurements of planetary motions, from which Kepler was able to derive his laws of planetary motion.  According to these laws, planets move on ellipses (not epicycles) about the Sun (not the Earth). Kepler's second and third laws make specific quantitative predictions: planets sweep out equal areas in equal time, and the square of their orbital periods equals a fixed constant times the cube of their semi-major axis. Subsequent observations of the planetary orbits showed that the long axis of the ellipse (the so-called line of apsides) rotates gradually with time; this rotation is known as apsidal precession. The apses of an orbit are the points at which the orbiting body is closest or furthest away from the attracting center; for planets orbiting the Sun, the apses correspond to the perihelion (closest) and aphelion (furthest).

text: The modern understanding of planetary motion arose from the combined efforts of astronomer

text: Tycho Brahe

text: and physicist

text: Johannes Kepler

text: in the 16th century. Tycho is credited with extremely accurate measurements of planetary motions, from which Kepler was able to derive his

text: laws of planetary motion

text: .  According to these laws, planets move on

text: ellipse

text: s (not epicycles) about the

text: Sun

text: (not the Earth). Kepler's second and third laws make specific quantitative predictions: planets sweep out equal areas in equal time, and the square of their

text: orbital period

text: s equals a fixed constant times the cube of their

text: semi-major axis

text: . Subsequent observations of the planetary orbits showed that the long axis of the ellipse (the so-called line of apsides) rotates gradually with time; this rotation is known as apsidal precession. The

text: apses

text: of an orbit are the points at which the orbiting body is closest or furthest away from the attracting center; for planets orbiting the Sun, the apses correspond to the perihelion (closest) and aphelion (furthest).

text: It is also double star HJ 4486AB, as discovered by Sir John Herschel during February 1836, and is a likely binary system, though no formal orbit has yet been determined. Observations through the 20th Century have been slowly reducing, whose latest separation is 0.364 arcsec in position angle 211°, as determined on date 1997.0905 using CCD speckle interferometry by E.P. Horch (1997). Epsilon Chamaeleontis A or HJ 4486A is an B9Vn dwarf star with an effective temperature of 11000 Kelvin. Apparent visual magnitude of +5.3, and has a mass of 3.3 solar masses. Epsilon Chamaeleontis B or HJ 4486B is also a dwarf star of undetermined 'A' spectral type with an effective temperature of about 9600 Kelvin, being based on the lesser apparent visual magnitude of +6.1, and is about 3.0 solar masses. Observation of the spectrum show strong nebula lines, suggesting the stars are of a young age.

text: It is also double star HJ 4486AB, as discovered by

text: Sir John Herschel

text: during February 1836, and is a likely binary system, though no formal orbit has yet been determined. Observations through the 20th Century have been slowly reducing, whose latest separation is 0.364

text: arcsec

text: in

text: position angle

text: 211°, as determined on date 1997.0905 using CCD speckle interferometry by E.P. Horch (1997). Epsilon Chamaeleontis A or HJ 4486A is an B9Vn

text: dwarf star

text: with an effective temperature of 11000 Kelvin.

text: Apparent visual magnitude

text: of +5.3, and has a mass of 3.3 solar masses. Epsilon Chamaeleontis B or HJ 4486B is also a dwarf star of undetermined 'A' spectral type with an effective temperature of about 9600 Kelvin, being based on the lesser apparent visual

text: magnitude

text: of +6.1, and is about 3.0 solar masses. Observation of the spectrum show strong nebula lines, suggesting the stars are of a young age.

text: The comet was observed to release 21 different organic molecules in gas, including ethanol and glycolaldehyde, a simple sugar. The presence of organic molecules suggests that they are preserved materials synthesized in the outskirts of the solar nebula or at earlier stages of the Solar System formation.

text: The comet was observed to release 21 different

text: organic molecule

text: s in gas, including

text: ethanol

text: and

text: glycolaldehyde

text: , a simple sugar. The presence of organic molecules suggests that they are preserved materials synthesized in the outskirts of the

text: solar nebula

text: or at earlier stages of the

text: Solar System formation

text: Santur is interpreted as a burnt-out sun that was still visible at the time of Homer. Rüdiger speculates that this was the center of the solar system hundreds of millennia ago, and he imagines a fight between the new and the old Suns that was decided 330,000 years ago. Santur is seen as the source of power of the Hyperboreans.

text: Santur is interpreted as a burnt-out sun that was still visible at the time of

text: Homer

text: . Rüdiger speculates that this was the center of the solar system hundreds of millennia ago, and he imagines a fight between the new and the old Suns that was decided 330,000 years ago. Santur is seen as the source of power of the

text: Hyperborean

text: s.

text: Hyakutake had passed through the inner Solar System approximately 17,000 years ago; gravitational interactions with the gas giants during its 1996 passage stretched its orbit greatly, and barycentric fits to the comet's orbit predict it will not return to the inner Solar System again for approximately 70,000 years.

text: Hyakutake had passed through the inner Solar System approximately 17,000 years ago; gravitational interactions with the

text: gas giants

text: during its 1996 passage stretched its orbit greatly, and

text: barycentric fits

text: to the comet's orbit predict it will not return to the inner

text: Solar System

text: again for approximately 70,000 years.

text: Another source of insight within our solar system is the history of the planet Earth, which may have had several episodes of stagnant lid geodynamics during its history. These stagnant-lid periods were not necessarily planet-wide; when supercontinents such as Gondwanaland existed, their presence may have shut off plate motion over large expanses of the Earth’s surface until mantle heat buildup underneath the superplate was sufficient to break them apart.

text: Perhaps the simplest manner in which to understand Hick's theory of pluralism of religions is to share the comparison he makes between his own understanding of religion and the Copernican view of our solar system.  Before Copernicus disseminated his views of the solar-centered universe, the Ptolemaic system ruled in which the stars were painted in the sky, and the sun rose and set around the earth.  In short, the rest of the universe existed for and was centered on earth.  On the other hand, Copernicus asserted that the earth, and other planets as well, circled the sun, which in fact, did not move, but only appeared to move due to the revolution of our planet.  Copernicus introduced our world to the understanding that other planets took similar paths around the sun; while each path differed, all served the same purpose and generated the same result:  every planet makes a full path around our central star. Rotation of a planet about its axis creates day and night for that planet, just as day and night occur on earth.  Although the time frames for a full trip around the sun and for a full day-night cycle differs on a planet-by-planet basis, the concept remains constant throughout our solar system.

text: Perhaps the simplest manner in which to understand Hick's theory of pluralism of religions is to share the comparison he makes between his own understanding of religion and the Copernican view of our solar system.  Before

text: Copernicus

text: disseminated his views of the solar-centered universe, the

text: Ptolemaic system

text: ruled in which the stars were painted in the sky, and the sun rose and set around the earth.  In short, the rest of the universe existed for and was centered on earth.  On the other hand, Copernicus asserted that the earth, and other planets as well, circled the sun, which in fact, did not move, but only appeared to move due to the revolution of our planet.  Copernicus introduced our world to the understanding that other planets took similar paths around the sun; while each path differed, all served the same purpose and generated the same result:  every planet makes a full path around our central star. Rotation of a planet about its axis creates day and night for that planet, just as day and night occur on earth.  Although the time frames for a full trip around the sun and for a full day-night cycle differs on a planet-by-planet basis, the concept remains constant throughout our solar system.

text: The album is subtitled Songs And Planets and features some parts of Gustav Holst's Planets Suite. It represents the completion of an original project started back in 1973, which planned to use Holst's work as a basis. This was ultimately shelved because the band were unable to obtain formal permission from Holst's estate, although some of the idea of a concept album dealing with the solar system could be seen on the band's 1973 album Solar Fire.

text: The album is subtitled Songs And Planets and features some parts of

text: Gustav Holst

text: 's

text: Planets Suite

text: . It represents the completion of an original project started back in 1973, which planned to use Holst's work as a basis. This was ultimately shelved because the band were unable to obtain formal permission from Holst's estate, although some of the idea of a concept album dealing with the solar system could be seen on the band's 1973 album

text: Solar Fire

text: When superflares were originally discovered on solar-type stars it was suggested that these eruptions may be produced by the interaction of the star's magnetic field with the magnetic field of a  gas-giant planet orbiting so close to the primary that the magnetic fields were linked.  Rotation or orbital motion would wind up the magnetic fields until a reconfiguration of the fields would cause an explosive release of energy. The RS Canum Venaticorum variables are close binaries, with orbital periods between 1 and 14 days, in which the primary is an F- or G-type main sequence star, and with strong chromospheric activity at all orbital phases.  These systems have  brightness variations attributed to large starspots on the primary; some show large flares thought to be caused by magnetic reconnection. The companion is close enough to spin up the star by tidal interactions.

text: When superflares were originally discovered on solar-type stars it was suggested that these eruptions may be produced by the interaction of the star's magnetic field with the magnetic field of a  gas-giant planet orbiting so close to the primary that the magnetic fields were linked.  Rotation or orbital motion would wind up the magnetic fields until a reconfiguration of the fields would cause an explosive release of energy. The

text: RS Canum Venaticorum variable

text: s are close binaries, with orbital periods between 1 and 14 days, in which the primary is an F- or G-type main sequence star, and with strong chromospheric activity at all orbital phases.  These systems have  brightness variations attributed to large starspots on the primary; some show large flares thought to be caused by magnetic reconnection. The companion is close enough to spin up the star by tidal interactions.

text: 'World' was also classically used to mean the material universe, or the cosmos: "The worlde is an apte frame of heauen and earthe, and all other naturall thinges contained in them."  The earth was often described as 'the center of the world'.

text: A heliocentric orbit (also called circumsolar orbit) is an orbit around the barycenter of the Solar System, which is usually located within or very near the surface of the Sun. All planets, comets, and asteroids in the Solar System are in such orbits, as are many artificial probes and pieces of debris. The moons of planets in the Solar System, by contrast, are not in heliocentric orbits as they orbit their respective planet.

text: A heliocentric orbit (also called circumsolar orbit) is an

text: orbit

text: around the

text: barycenter

text: of the

text: Solar System

text: , which is usually located within or very near the surface of the

text: Sun

text: . All

text: planet

text: s,

text: comet

text: s, and

text: asteroid

text: s in the Solar System are in such orbits, as are many artificial

text: probes

text: and pieces of

text: debris

text: . The moons of planets in the Solar System, by contrast, are not in heliocentric orbits as they orbit their respective planet.

text: In September 2008, the discovery of an extrasolar planet was announced by the Microlensing Follow Up Network (μFUN)  and the Microlensing Observations in Astrophysics (MOA) Collaboration. This planet was detected by the gravitational microlensing method based on an event recorded in September 2007.

text: In September 2008, the discovery of an

text: extrasolar planet

text: was announced by the Microlensing Follow Up Network (μFUN)  and the

entity_name: Microlensing Observations in Astrophysics

text: Microlensing Observations in Astrophysics

text: (MOA) Collaboration. This planet was detected by the

text: gravitational microlensing

text: method based on an event recorded in September 2007.

text: A super-Earth is an extrasolar planet with a mass between that of Earth and the Solar System's gas giants. The term super-Earth refers only to the mass of the planet and does not imply anything about the surface conditions or habitability.

text: A

text: super-Earth

text: is an

text: extrasolar planet

text: with a mass between that of

text: Earth

text: and the Solar System's

text: gas giant

text: s. The term super-Earth refers only to the mass of the planet and does not imply anything about the surface conditions or habitability.

text: __NOTOC__Elena Vladimirovna Pitjeva is a Russian astronomer working at the Institute of Applied Astronomy, Russian Academy of Sciences, St. Petersburg. She has published over 100 articles, as listed in Google Scholar and the Astrophysics Data System in the field of solar system dynamics and celestial mechanics .She began employment activity as an engineer-observer at the Astrophysical observation station of the Astronomical Observatory of Leningrad State University in Byurakan (Armenia). Then Pitjeva worked at the Institute of Theoretical Astronomy of the USSA Academy of Science and the Institute Applied Astronomy RAS since the date of its foundation in 1988 as researcher and senior researcher. At present she is head of the Laboratory of Ephemeris Astronomy of this institute.Major research interests of Dr. Pitjeva include the construction of numerical ephemerides of the planets, the determination of the planets' and asteroids' masses, the parameters of planet rotation and planetary topography, the solar corona and oblateness and general relativity testing. She is one of creators of the numerical Ephemerides of Planets and the Moon (EPM) of IAA RAS that originated in the seventies of the past century and have been developed since that time.  The version of the EPM2004 ephemeris has been adopted as the ephemeris basis of Russian Astronomical Yearbook since 2006. The updated EPM2008 ephemerides are available to outside users via ftp.The works of Pitjeva have recently been used by several scientists to test several models of modified gravity in the Solar System.Dr. Pitjeva has also contributed to a better understanding an influence of asteroids and Trans-Neptunian Objects on the planets' motion. Recently Dr. Pitjeva collaborated with Dr. Standish and proposed to the IAU Working Group on Numerical Standards for Fundamental Astronomy (NSFA) the values of the masses of the three largest asteroids, the Moon-Earth mass ratio and the astronomical unit in meters, mainly obtained while fitting the constructed DE (JPL) and EPM (IAA RAS) planet ephemerides. These values have been adopted by the 27 General Assembly of International Astronomical Union as Current Best Estimates as the IAU (2009) System of Astronomical Constants.Pitjeva is a member of the International Astronomical Union: OC of Commission 4 “Ephemerides”,Commission 52 “Relativity in Fundamental Astronomy” IAU WG NSFA.”,

text: __NOTOC__Elena Vladimirovna Pitjeva is a

text: Russian

text: astronomer

text: working at the Institute of Applied Astronomy,

text: Russian Academy of Sciences

text: St. Petersburg

text: . She has published over 100 articles, as listed in

text: Google Scholar

text: and the

text: Astrophysics Data System

text: in the field of solar system dynamics and

text: celestial mechanics

text: .She began employment activity as an engineer-observer at the Astrophysical observation station of the Astronomical Observatory of

text: Leningrad State University

text: in

text: Byurakan

text: (Armenia). Then Pitjeva worked at the Institute of Theoretical Astronomy of the USSA Academy of Science and the Institute Applied Astronomy RAS since the date of its foundation in 1988 as researcher and senior researcher. At present she is head of the Laboratory of

text: Ephemeris

text: Astronomy of this institute.Major research interests of Dr. Pitjeva include the construction of numerical ephemerides of the planets, the determination of the planets' and asteroids' masses, the parameters of planet rotation and planetary topography, the solar corona and oblateness and

text: general relativity

text: testing. She is one of creators of the numerical Ephemerides of Planets and the Moon (EPM) of IAA RAS that originated in the seventies of the past century and have been developed since that time.  The version of the EPM2004 ephemeris has been adopted as the ephemeris basis of Russian Astronomical Yearbook since 2006. The updated EPM2008 ephemerides are available to outside users via ftp.The works of Pitjeva have recently been used by several scientists to test several models of modified gravity in the Solar System.Dr. Pitjeva has also contributed to a better understanding an influence of asteroids and

text: Trans-Neptunian Objects

text: on the planets' motion. Recently Dr. Pitjeva collaborated with

text: Dr. Standish

text: and proposed to the IAU Working Group on Numerical Standards for Fundamental Astronomy (NSFA) the values of the masses of the three largest asteroids, the Moon-Earth mass ratio and the astronomical unit in meters, mainly obtained while fitting the constructed DE (JPL) and EPM (IAA RAS) planet ephemerides. These values have been adopted by the 27 General Assembly of

text: International Astronomical Union

text: as Current Best Estimates as the IAU (2009) System of Astronomical Constants.Pitjeva is a member of the

text: International Astronomical Union

text: : OC of Commission 4 “Ephemerides”,Commission 52 “Relativity in Fundamental Astronomy” IAU WG NSFA.”,

text: Giant planet core formation is thought to proceed roughly along the lines of the terrestrial planet formation. It starts with planetesimals that undergo runaway growth, followed by the slower oligarchic stage. Hypotheses do not predict a merger stage, due to the low probability of collisions between planetary embryos in the outer part of planetary systems. An additional difference is the composition of the planetesimals, which in the case of giant planets form beyond the so-called snow line and consist mainly of ice—the ice to rock ratio is about 4 to 1. This enhances the mass of planetesimals fourfold. However, the minimum mass nebula capable of terrestrial planet formation can only form  cores at the distance of Jupiter (5 AU) within 10 million years. The latter number represents the average lifetime of gaseous disks around Sun-like stars. The proposed solutions include enhanced mass of the disk—a tenfold increase would suffice; protoplanet migration, which allows the embryo to accrete more planetesimals; and finally accretion enhancement due to gas drag in the gaseous envelopes of the embryos. Some combination of the above-mentioned ideas may explain the formation of the cores of gas giant planets such as Jupiter and perhaps even Saturn. The formation of planets like Uranus and Neptune is more problematic, since no theory has been capable of providing for the in situ formation of their cores at the distance of 20–30 AU from the central star. One hypothesis is that they initially accreted in the Jupiter-Saturn region, then were scattered and migrated to their present location. Another possible solution is the growth of the cores of the giant planets via pebble accretion. In pebble accretion objects between a cm and a meter in diameter falling toward a massive body are slowed enough by gas drag for them to spiral toward it and be accreted. Growth via pebble accretion may be as much as 1000 time faster than by the accretion of planesimals.

text: Giant planet core formation is thought to proceed roughly along the lines of the terrestrial planet formation. It starts with planetesimals that undergo runaway growth, followed by the slower oligarchic stage. Hypotheses do not predict a merger stage, due to the low probability of collisions between planetary embryos in the outer part of planetary systems. An additional difference is the composition of the

text: planetesimal

text: s, which in the case of giant planets form beyond the so-called

text: snow line

text: and consist mainly of ice—the ice to rock ratio is about 4 to 1. This enhances the mass of planetesimals fourfold. However, the minimum mass nebula capable of terrestrial planet formation can only form  cores at the distance of Jupiter (5 AU) within 10 million years. The latter number represents the average lifetime of gaseous disks around Sun-like stars. The proposed solutions include enhanced mass of the disk—a tenfold increase would suffice; protoplanet migration, which allows the embryo to accrete more planetesimals; and finally accretion enhancement due to

text: gas drag

text: in the gaseous envelopes of the embryos. Some combination of the above-mentioned ideas may explain the formation of the cores of gas giant planets such as

text: Jupiter

text: and perhaps even

text: Saturn

text: . The formation of planets like

text: Uranus

text: and

text: Neptune

text: is more problematic, since no theory has been capable of providing for the in situ formation of their cores at the distance of 20–30 AU from the central star. One hypothesis is that they initially accreted in the Jupiter-Saturn region, then were scattered and migrated to their present location. Another possible solution is the growth of the cores of the giant planets via

text: pebble accretion

text: . In pebble accretion objects between a cm and a meter in diameter falling toward a massive body are slowed enough by gas drag for them to spiral toward it and be accreted. Growth via pebble accretion may be as much as 1000 time faster than by the accretion of planesimals.

text: The established convention for extrasolar planets is that the planets receive designations consisting of the star's name followed by lower-case Roman letters starting from "b", in order of discovery. This system was used by a team led by Krzysztof Goździewski.  On the other hand, a team led by Francesco Pepe proposed a modification of the designation system, where the planets are designated in order of characterization. Since the parameters of the outermost planet were poorly constrained before the introduction of the 4-planet model of the system, this results in a different order of designations for the planets in the Mu Arae system. Both systems agree on the designation of the 640-day planet as "b". The old system designates the 9-day planet as "d", the 310-day planet as "e" and the outer planet as "c".  Since the International Astronomical Union has not defined an official system for designations of extrasolar planets, the issue of which convention is 'correct' remains open, however subsequent scientific publications about this system appear to have adopted the Pepe et al. system, as has the system's entry in the Extrasolar Planets Encyclopaedia.

text: The established convention for extrasolar planets is that the planets receive designations consisting of the star's name followed by lower-case

text: Roman letters

text: starting from "b", in order of discovery. This system was used by a team led by

text: Krzysztof Goździewski

text: .  On the other hand, a team led by

text: Francesco Pepe

text: proposed a modification of the designation system, where the planets are designated in order of characterization. Since the parameters of the outermost planet were poorly constrained before the introduction of the 4-planet model of the system, this results in a different order of designations for the planets in the Mu Arae system. Both systems agree on the designation of the 640-day planet as "b". The old system designates the 9-day planet as "d", the 310-day planet as "e" and the outer planet as "c".  Since the

text: International Astronomical Union

text: has not defined an official system for designations of extrasolar planets, the issue of which convention is 'correct' remains open, however subsequent scientific publications about this system appear to have adopted the Pepe et al. system, as has the system's entry in the

text: Extrasolar Planets Encyclopaedia

text: In 2006, the term "small Solar System body" was also introduced to cover both most minor planets and comets. Other languages prefer "planetoid" (Greek for "planet-like"), and this term is occasionally used in English especially for larger minor planets such as the dwarf planets as well as an alternative for asteroids since they are not star-like. The word "planetesimal" has a similar meaning, but refers specifically to the small building blocks of the planets that existed when the Solar System was forming. The term "planetule" was coined by the geologist William Daniel Conybeare to describe minor planets, but is not in common use. The three largest objects in the asteroid belt, Ceres, Pallas, and Vesta, grew to the stage of protoplanets. Ceres is a dwarf planet, the only one in the inner Solar System.

text: In 2006, the term "

text: small Solar System body

text: " was also introduced to cover both most minor planets and comets. Other languages prefer "planetoid" (Greek for "planet-like"), and this term is occasionally used in English especially for larger minor planets such as the

text: dwarf planet

text: s as well as an alternative for asteroids since they are not star-like. The word "

text: planetesimal

text: " has a similar meaning, but refers specifically to the small building blocks of the planets that existed when the Solar System was forming. The term "planetule" was coined by the geologist

text: William Daniel Conybeare

text: to describe minor planets, but is not in common use. The three largest objects in the asteroid belt,

text: Ceres

text: Pallas

text: , and

text: Vesta

text: , grew to the stage of

text: protoplanet

text: s. Ceres is a

text: dwarf planet

text: , the only one in the inner Solar System.

text: In addition to insulation requirements and limitation of openings of the building fabric, this part considers solar heating and heat gains to structures, it controls heating, mechanical ventilation and air conditioning systems, lighting efficiency, space heating controls, air permeability, solar emission, the certification, testing and commissioning of heating and ventilation systems, and requirements for energy meters.

text: If a Counter-Earth had an electromagnetic energy signature similar to that of Earth's, it would be able to be detected by astronomers since the signature would extend well beyond the surface of an Earth-like planet. The Sun's "wobbling" motion around its "barycenter" would prevent it from blocking all signs of that energy from Earth, at least for part of the year.  The Sun does not remain stationary—relative to its planets—at the center of the solar system because of the gravitational pull of the most massive planet—Jupiter.

text: If a Counter-Earth had an

text: electromagnetic energy signature

text: similar to that of Earth's, it would be able to be detected by astronomers since the signature would extend well beyond the surface of an Earth-like planet. The Sun's "wobbling" motion around its "

text: barycenter

text: " would prevent it from blocking all signs of that energy from Earth, at least for part of the year.  The Sun does not remain stationary—relative to its planets—at the center of the solar system because of the gravitational pull of the most massive planet—Jupiter.

text: Certain light (low atomic number) primordial nuclides (some isotopes of lithium, beryllium and boron) are thought to have arisen not only during the Big Bang, and also (and perhaps primarily) to have been made after the Big Bang, but before the condensation of the Solar System, by the process of cosmic ray spallation on interstellar gas and dust. This explains their higher abundance in cosmic rays as compared with their ratios and abundances of certain other nuclides on Earth. This also explains the overabundance of the early transition metals just before iron in the periodic table; the cosmic-ray spallation of iron thus produces Sc–Cr on one hand and He–B on the other. However, the arbitrary defining qualification for cosmogenic nuclides of being formed "in situ in the Solar System" (meaning inside an already-aggregated piece of the Solar System) prevents primordial nuclides formed by cosmic ray spallation before the formation of the Solar System, from being termed "cosmogenic nuclides"— even though the mechanism for their formation is exactly the same. These same nuclides still arrive on Earth in small amounts in cosmic rays, and are formed in meteoroids, in the atmosphere, on Earth, "cosmogenically." However, beryllium (all of it stable beryllium-9) is present primordially in the Solar System in much larger amounts, having existed prior to the condensation of the Solar System, and thus present in the materials from which the Solar System formed.

text: Certain light (low atomic number)

text: primordial nuclides

text: (some isotopes of lithium, beryllium and boron) are thought to have arisen not only during the

text: Big Bang

text: , and also (and perhaps primarily) to have been made after the Big Bang, but before the condensation of the Solar System, by the process of

text: cosmic ray spallation

text: on interstellar gas and dust. This explains their higher abundance in cosmic rays as compared with their ratios and abundances of certain other nuclides on Earth. This also explains the overabundance of the early transition metals just before iron in the periodic table; the cosmic-ray spallation of iron thus produces Sc–Cr on one hand and He–B on the other. However, the arbitrary defining qualification for cosmogenic nuclides of being formed "in situ in the Solar System" (meaning inside an already-aggregated piece of the Solar System) prevents primordial nuclides formed by cosmic ray spallation before the formation of the Solar System, from being termed "cosmogenic nuclides"— even though the mechanism for their formation is exactly the same. These same nuclides still arrive on Earth in small amounts in cosmic rays, and are formed in meteoroids, in the atmosphere, on Earth, "cosmogenically." However, beryllium (all of it stable beryllium-9) is present primordially in the Solar System in much larger amounts, having existed prior to the condensation of the Solar System, and thus present in the materials from which the Solar System formed.

text: Laghu Parashari is the concise main version of the predictive side of the Hora Shastra, and the Parashari System is most widely followed, having stood the test of time and because it is simple and unambiguous. The ancient Hindu astrologers seem to have confined their exercises to the seven planets – the Sun, the Moon, Mercury, Venus, Mars, Jupiter and Saturn; Rahu and Ketu, these two that are mathematical points, are referred to but rarely. Parashara also refers to five more Chayagrahas which are all actually invisible mathematical solar positions but having impact on the life of individuals and nations. The Rigveda does refer to the total of thirty-four, comprising twenty-seven Nakshatra-divisions of the Zodiac and the seven planets which was the general format then in use. However, elsewhere it also refers to the total of forty-nine by adding to the said thirty-four the two Chayagrahas (the lunar nodes), the twelve rasis (signs) and the Ayanamsa. Varahamihira favoured Satyacharya’s Dasha system though he says many had spoiled it by useless multiplications but Satyacharya did not deviate from the basic Parashari principles. Because of there being nine active planets and equally active twelve signs (including their numerous sub-divisions) and twenty seven nakshatra divisions, yoga-formations are unavoidable.

text: Laghu Parashari

text: is the concise main version of the predictive side of the Hora Shastra, and the Parashari System is most widely followed, having stood the test of time and because it is simple and unambiguous. The ancient Hindu astrologers seem to have confined their exercises to the seven planets – the

text: Sun

text: , the

text: Moon

text: Mercury

text: Venus

text: Mars

text: Jupiter

text: and

text: Saturn

text: Rahu

text: and

text: Ketu

text: , these two that are mathematical points, are referred to but rarely.

text: Parashara

text: also refers to five more Chayagrahas which are all actually invisible mathematical solar positions but having impact on the life of individuals and nations. The

text: Rigveda

text: does refer to the total of thirty-four, comprising twenty-seven

text: Nakshatra

text: -divisions of the

text: Zodiac

text: and the seven planets which was the general format then in use. However, elsewhere it also refers to the total of forty-nine by adding to the said thirty-four the two Chayagrahas (the lunar nodes), the twelve rasis (signs) and the

text: Ayanamsa

text: Varahamihira

text: favoured Satyacharya’s

text: Dasha

text: system though he says many had spoiled it by useless multiplications but Satyacharya did not deviate from the basic Parashari principles. Because of there being nine active planets and equally active twelve signs (including their numerous sub-divisions) and twenty seven

text: nakshatra

text: divisions, yoga-formations are unavoidable.

text: The mass of a planet has consequences for its structure by having a large mass, especially while it is in the hand of process of formation. A body which is more than about one ten-thousandth of the mass of the Earth can overcome its compressive strength and achieve hydrostatic equilibrium: it will be roughly spherical, and since 2006 has been classified as a dwarf planet if it orbits around the Sun (that is, if it is not the satellite of another planet). Smaller bodies like asteroids are classified as "small Solar System bodies".

text: The mass of a planet has consequences for its structure by having a large mass, especially while it is in the hand of

text: process of formation

text: . A body which is more than about one ten-thousandth of the mass of the Earth can overcome its

text: compressive strength

text: and achieve

text: hydrostatic equilibrium

text: : it will be roughly

text: spherical

text: , and since 2006 has been classified as a

text: dwarf planet

text: if it orbits around the Sun (that is, if it is not the

text: satellite

text: of another planet). Smaller bodies like

text: asteroid

text: s are classified as "

text: small Solar System bodies

text: A major challenge that must be addressed in any solar concentrating technology is the changing angle of the incident rays (the rays of sunlight striking the mirrors) as the sun progresses throughout the day.  The reflectors of a CLFR are typically aligned in a north-south orientation and turn about a single axis using a computer controlled solar tracker system. This allows the system to maintain the proper angle of incidence between the sun’s rays and the mirrors, thereby optimizing energy transfer.

text: A major challenge that must be addressed in any solar concentrating technology is the changing angle of the incident rays (the rays of sunlight striking the mirrors) as the sun progresses throughout the day.  The reflectors of a CLFR are typically aligned in a north-south orientation and turn about a single axis using a computer controlled

text: solar tracker

text: system. This allows the system to maintain the proper

text: angle of incidence

text: between the sun’s rays and the mirrors, thereby optimizing energy transfer.

text: Traditionally, no gem other than a ruby or a red spinel is set in the center of a nine gems arrangement. To do so is believed to go against the flow of nature. Because the Sun is the center of the solar system, its gem is positioned in the heart of a Navaratna Talisman.

text: Traditionally, no gem other than a ruby or a red spinel is set in the center of a nine gems arrangement. To do so is believed to go against the flow of nature. Because the Sun is the center of the solar system, its gem is positioned in the heart of a Navaratna

text: Talisman

text: The analysis only considers the Sun's heat for a planet in a Solar System.

text: Even when this planet was taken into account, there still remained significant residuals in the radial velocity measurements, and it was suggested there might be a second planet in orbit. In 1999, astronomers at both San Francisco State University and the Harvard-Smithsonian Center for Astrophysics independently concluded that a three-planet model best fit the data. The two outer planets were designated Upsilon Andromedae c and Upsilon Andromedae d in order of increasing distance from the star. Both of these planets are in more eccentric orbits than any of the planets in the Solar System (including Pluto). Upsilon Andromedae d resides in the system's habitable zone.

text: Even when this planet was taken into account, there still remained significant residuals in the radial velocity measurements, and it was suggested there might be a second planet in orbit. In 1999, astronomers at both

text: San Francisco State University

text: and the

text: independently concluded that a three-planet model best fit the data. The two outer planets were designated

text: Upsilon Andromedae c

text: and

text: Upsilon Andromedae d

text: in order of increasing distance from the star. Both of these planets are in more

text: eccentric

text: orbits than any of the planets in the Solar System (including

text: Pluto

text: ). Upsilon Andromedae d resides in the system's

text: habitable zone

text: Mars Glacier is a glacier in the southeastern corner of Alexander Island, Antarctica,  long and  wide, flowing south into the George VI Ice Shelf. The glacier lies between Two Step Cliffs and Phobos Ridge. Mars Glacier was first sighted from the air by Lincoln Ellsworth on November 23, 1935, and roughly mapped from photos obtained on that flight by W.L.G. Joerg. It was first surveyed in 1949 by the Falkland Islands Dependencies Survey and named by the UK Antarctic Place-Names Committee for the planet Mars, the fourth planet from the sun in the Solar System.

text: Mars Glacier is a

text: glacier

text: in the southeastern corner of

text: Alexander Island

text: , Antarctica,  long and  wide, flowing south into the

text: George VI Ice Shelf

text: . The glacier lies between

text: Two Step Cliffs

text: and

text: Phobos Ridge

text: . Mars Glacier was first sighted from the air by

text: Lincoln Ellsworth

text: on November 23, 1935, and roughly mapped from photos obtained on that flight by

text: W.L.G. Joerg

text: . It was first surveyed in 1949 by the

text: Falkland Islands Dependencies Survey

text: and named by the

text: UK Antarctic Place-Names Committee

text: for the planet

text: Mars

text: , the fourth planet from the

text: sun

text: in the

text: Solar System

text: As of 2015, companies currently offering solar shingles in the United States include Dow, CertainTeed, SunTegra Solar Roof Systems, and Atlantis Energy Systems (asphalt and slate systems). Other companies that may be active include Sun Energy Engineering, and OkSolar.com.  Tesla Solar entered the solar roof market in 2016.

text: The Sun lies close to the inner rim of the Milky Way's Orion Arm, in the Local Interstellar Cloud or the Gould Belt, at a distance of 7.5–8.5 kpc (25,000–28,000 light-years) from the Galactic Center.The Sun is contained within the Local Bubble, a space of rarefied hot gas, possibly produced by the supernova remnant Geminga. The distance between the local arm and the next arm out, the Perseus Arm, is about 6,500 light-years. The Sun, and thus the Solar System, is found in what scientists call the galactic habitable zone.The Apex of the Sun's Way, or the solar apex, is the direction that the Sun travels relative to other nearby stars. This motion is towards a point in the constellation Hercules, near the star Vega. Of the 50 nearest stellar systems within 17 light-years from Earth (the closest being the red dwarf Proxima Centauri at approximately 4.2 light-years), the Sun ranks fourth in mass.

text: The Sun lies close to the inner rim of the

text: Milky Way

text: 's

text: Orion Arm

text: , in the

text: Local Interstellar Cloud

text: or the

text: Gould Belt

text: , at a distance of 7.5–8.5

text: kpc

text: (25,000–28,000 light-years) from the

text: Galactic Center

text: .The Sun is contained within the

text: Local Bubble

text: , a space of rarefied hot gas, possibly produced by the supernova remnant

text: Geminga

text: . The distance between the local arm and the next arm out, the

text: Perseus Arm

text: , is about 6,500 light-years. The Sun, and thus the Solar System, is found in what scientists call the

text: galactic habitable zone

text: .The Apex of the Sun's Way, or the

text: solar apex

text: , is the direction that the Sun travels relative to other nearby stars. This motion is towards a point in the constellation

text: Hercules

text: , near the star

text: Vega

text: . Of the 50

text: nearest stellar systems

text: within 17 light-years from Earth (the closest being the red dwarf

text: Proxima Centauri

text: at approximately 4.2 light-years), the Sun ranks fourth in mass.

text: A system of bodies may have internal kinetic energy due to the relative motion of the bodies in the system. For example, in the Solar System the planets and planetoids are orbiting the Sun. In a tank of gas, the molecules are moving in all directions. The kinetic energy of the system is the sum of the kinetic energies of the bodies it contains.

text: A system of bodies may have internal kinetic energy due to the relative motion of the bodies in the system. For example, in the

text: Solar System

text: the planets and planetoids are orbiting the Sun. In a tank of gas, the molecules are moving in all directions. The kinetic energy of the system is the sum of the kinetic energies of the bodies it contains.

text: The Sun wobbles as it rotates around the galactic center, dragging the Solar System and Earth along with it.  What mathematician Kepler did in arriving at his three famous equations was curve-fit the apparent motions of the planets using Tycho Brahe's data, and not curve-fitting their true circular motions about the Sun (see Figure).  Both Robert Hooke and Newton were well aware that Newton's Law of Universal Gravitation did not hold for the forces associated with elliptical orbits.  In fact, Newton's Universal Law does not account for the orbit of Mercury, the asteroid belt's gravitational behavior, or Saturn's rings.  Newton stated (in the 11th Section of the Principia) that the main reason, however, for failing to predict the forces for elliptical orbits was that his math model was for a body confined to a situation that  hardly existed in the real world, namely, the motions of bodies attracted toward an unmoving center.  Some present physics and astronomy textbooks don't emphasize the negative significance of Newton's assumption and end up teaching that his math model is in effect reality.  It is to be understood that the classical two-body problem solution above is a mathematical idealization.  See also Kepler's first law of planetary motion.

text: The Sun wobbles as it rotates around the galactic center, dragging the Solar System and Earth along with it.  What mathematician

text: Kepler

text: did in arriving at his three famous equations was curve-fit the apparent motions of the planets using

text: Tycho Brahe

text: 's data, and not curve-fitting their true circular motions about the Sun (see Figure).  Both

text: Robert Hooke

text: and Newton were well aware that Newton's Law of Universal Gravitation did not hold for the forces associated with elliptical orbits.  In fact, Newton's Universal Law does not account for the orbit of Mercury, the asteroid belt's gravitational behavior, or

text: Saturn's rings

text: .  Newton stated (in the 11th Section of the Principia) that the main reason, however, for failing to predict the forces for elliptical orbits was that his math model was for a body confined to a situation that  hardly existed in the real world, namely, the motions of bodies attracted toward an unmoving center.  Some present physics and astronomy textbooks don't emphasize the negative significance of Newton's assumption and end up teaching that his math model is in effect reality.  It is to be understood that the classical two-body problem solution above is a mathematical idealization.  See also

text: Kepler's first law of planetary motion

text: Various planets of the Solar System were used as settings for science fiction stories in the first half of the 20th century; but dissatisfaction with the limits imposed by science led many writers early on to forsake the Solar System for fictional planets around distant stars. As increasing knowledge of the Solar System made the prospects of life in the vicinity of Earth marginal at best, the extrasolar planet has become almost the only venue for contemporary science fiction.

text: Various planets of the Solar System were used as settings for science fiction stories in the first half of the 20th century; but dissatisfaction with the limits imposed by science led many writers early on to forsake the Solar System for fictional planets around distant stars. As increasing knowledge of the Solar System made the prospects of life in the vicinity of Earth marginal at best, the

text: extrasolar planet

text: has become almost the only venue for contemporary science fiction.

text: With a luminosity more than 1,000 times that of the Sun, an orbit where a planet could be habitable would be located 37 AU away from Pi Herculis—in Solar System terms, halfway between Neptune and Pluto's orbits. On the other hand, a putative companion would orbit in a scorching region and would be as hot as a planet would at 0.08 AU around a Sun-like star. In any case it's likely that it would soon be swallowed up by the expanding giant.

text: With a luminosity more than 1,000 times that of the

text: Sun

text: , an orbit where a planet could be habitable would be located 37

text: AU

text: away from Pi Herculis—in Solar System terms, halfway between

text: Neptune

text: and

text: Pluto

text: 's orbits. On the other hand, a putative companion would orbit in a scorching region and would be as hot as a planet would at 0.08

text: AU

text: around a Sun-like star. In any case it's likely that it would soon be swallowed up by the expanding giant.

text: Some astronomers search for extrasolar planets that may be conducive to life, narrowing the search to terrestrial planets within the habitable zone of their star. Since 1992 over two thousand exoplanets have been discovered ( planets in  planetary systems including  multiple planetary systems as of ).The extrasolar planets so far discovered range in size from that of terrestrial planets similar to Earth's size to that of gas giants larger than Jupiter.  The number of observed exoplanets is expected to increase greatly in the coming years.

text: Some astronomers search for

text: extrasolar planets

text: that may be conducive to life, narrowing the search to

text: terrestrial planet

text: s within the

text: habitable zone

text: of their star. Since 1992 over two thousand exoplanets have been discovered ( planets in

text: planetary system

text: s including

text: multiple planetary systems

text: as of ).The extrasolar planets so far discovered range in size from that of

text: terrestrial planet

text: s similar to Earth's size to that of gas giants larger than Jupiter.  The number of observed exoplanets is expected to increase greatly in the coming years.

text: Simulations suggest that, while the disk had a relatively high mass at any given moment, over time a substantial fraction (several tenths of a percent) of the mass of Jupiter captured from the Solar nebula was processed through it. However, the disk mass of only 2% that of Jupiter is required to explain the existing satellites. Thus there may have been several generations of Galilean-mass satellites in Jupiter's early history. Each generation of moons would have spiraled into Jupiter, due to drag from the disk, with new moons then forming from the new debris captured from the Solar nebula. By the time the present (possibly fifth) generation formed, the disk had thinned out to the point that it no longer greatly interfered with the moons' orbits. The current Galilean moons were still affected, falling into and being partially protected by an orbital resonance which still exists for Io, Europa, and Ganymede. Ganymede's larger mass means that it would have migrated inward at a faster rate than Europa or Io.

text: Simulations suggest that, while the disk had a relatively high mass at any given moment, over time a substantial fraction (several tenths of a percent) of the mass of Jupiter captured from the Solar nebula was processed through it. However, the disk mass of only 2% that of Jupiter is required to explain the existing satellites. Thus there may have been several generations of Galilean-mass satellites in Jupiter's early history. Each generation of moons would have spiraled into Jupiter, due to drag from the disk, with new moons then forming from the new debris captured from the Solar nebula. By the time the present (possibly fifth) generation formed, the disk had thinned out to the point that it no longer greatly interfered with the moons' orbits. The current Galilean moons were still affected, falling into and being partially protected by an

text: orbital resonance

text: which still exists for Io, Europa, and Ganymede. Ganymede's larger mass means that it would have migrated inward at a faster rate than Europa or Io.

text: Of the nineteen known natural satellites in the Solar System that are massive enough to have lapsed into hydrostatic equilibrium, several remain geologically active today. Io is the most volcanically active body in the Solar System, while Europa, Enceladus, Titan and Triton display evidence of ongoing tectonic activity and cryovolcanism.  In the first three cases, the geological activity is powered by the tidal heating resulting from having eccentric orbits close to their giant-planet primaries. (This mechanism would have also operated on Triton in the past, before its orbit was circularized.) Many other natural satellites, such as Earth's Moon, Ganymede, Tethys and Miranda, show evidence of past geological activity, resulting from energy sources such as the decay of their primordial radioisotopes, greater past orbital eccentricities (due in some cases to past orbital resonances), or the differentiation or freezing of their interiors. Enceladus and Triton both have active features resembling geysers, although in the case of Triton solar heating appears to provide the energy. Titan and Triton have significant atmospheres; Titan also has hydrocarbon lakes. Four of the largest natural satellites, Europa, Ganymede, Callisto, and Titan, are thought to have subsurface oceans of liquid water, while smaller Enceladus may have localized subsurface liquid water.

text: Of the nineteen known natural satellites in the

text: Solar System

text: that are massive enough to have lapsed into hydrostatic equilibrium, several remain geologically active today.

text: Io

text: is the most volcanically active body in the

text: Solar System

text: , while

text: Europa

text: Enceladus

text: Titan

text: and

text: Triton

text: display evidence of ongoing

text: tectonic activity

text: and

text: cryovolcanism

text: .  In the first three cases, the geological activity is powered by the

text: tidal heating

text: resulting from having

text: eccentric orbits

text: close to their giant-planet primaries. (This mechanism would have also operated on Triton in the past, before its orbit was

text: circularized

text: .) Many other natural satellites, such as Earth's

text: Moon

text: Ganymede

text: Tethys

text: and

text: Miranda

text: , show evidence of past geological activity, resulting from energy sources such as the

text: decay

text: of their

text: primordial

text: radioisotope

text: s, greater past orbital eccentricities (due in some cases to past

text: orbital resonance

text: s), or the

text: differentiation

text: or freezing of their interiors. Enceladus and

text: Triton

text: both have active features resembling

text: geysers

text: , although in the case of Triton solar heating appears to provide the energy. Titan and Triton have significant atmospheres; Titan also has

text: hydrocarbon lakes

text: . Four of the largest natural satellites,

text: Europa

text: Ganymede

text: Callisto

text: , and

text: Titan

text: , are thought to have subsurface oceans of liquid water, while smaller Enceladus may have localized subsurface liquid water.

text: Kepler-11b is estimated to be ≤3.3 Earth masses and 1.8 Earth radii, making it around three times (or less) as massive and nearly twice as large as Earth. While the radius of Kepler-11b is fairly well known (with a range of likely radii between 1.75 and 1.83 Earth radii), the mass is not as well constrained, with a range between 0.9 and 3.3 Earth masses. The mass is determined using transit timing variations of Kepler-11c, and is limited by the quality of the data.  Kepler-11b is the closest planet to its host star in the Kepler-11 planetary system. With an estimated density of 1.7 g/cm, comparable to Neptune's, Kepler-11b is denser than the solar system's gas giants but significantly less dense than the terrestrial planets. The estimated density range suggests that it is not of Earth-like composition, yet it is nonetheless composed mostly of elements heavier than helium. The planet's effective temperature is 900 K, and is thus the hottest of the planets discovered in the Kepler-11 system. Kepler-11b orbits its host star every 10.30375 days at a distance of .091 AU. Planet Mercury, in comparison, orbits the Sun every 87.97 days from a distance of .387 AU. Kepler-11b's inclination of 88.5° means that it deviates slightly from the orbital plane, but it does so more than the other five planets with which Kepler-11b was discovered.  Its close proximity to the star implies a strong insolation, which caused the planet to lose all of light-element envelope acquired during formation.  The observed low density does require the presence of a gaseous envelope though, which was most likely produced via outgassing of hydrogen or evaporation of HO from the condensed core.

text: Kepler-11b is estimated to be ≤3.3

text: Earth mass

text: es and 1.8

text: Earth radii

text: , making it around three times (or less) as massive and nearly twice as large as Earth. While the radius of Kepler-11b is fairly well known (with a range of likely radii between 1.75 and 1.83 Earth radii), the mass is not as well constrained, with a range between 0.9 and 3.3 Earth masses. The mass is determined using

text: transit timing variations

text: of

text: , and is limited by the quality of the data.  Kepler-11b is the closest planet to its host star in the Kepler-11 planetary system. With an estimated density of 1.7 g/cm, comparable to

text: Neptune

text: 's, Kepler-11b is denser than the solar system's

text: gas giants

text: but significantly less dense than the

text: terrestrial planets

text: . The estimated density range suggests that it is not of Earth-like composition, yet it is nonetheless composed mostly of elements heavier than helium. The planet's effective temperature is 900 K, and is thus the hottest of the planets discovered in the Kepler-11 system. Kepler-11b orbits its host star every 10.30375 days at a distance of .091

text: AU

text: . Planet

text: Mercury

text: , in comparison, orbits the Sun every 87.97 days from a distance of .387 AU. Kepler-11b's

text: inclination

text: of 88.5° means that it deviates slightly from the orbital plane, but it does so more than the other five planets with which Kepler-11b was discovered.  Its close proximity to the star implies a strong

text: insolation

text: , which caused the planet to lose all of light-element envelope acquired during formation.  The observed low density does require the presence of a gaseous envelope though, which was most likely produced via outgassing of hydrogen or evaporation of HO from the condensed core.

text: Central solar heating is a sub-class of 'large-scale solar heating' systems - a term applied to systems with solar collector areas greater than 500 m².

text: Given the orbital eccentricity of this object, its orbital period is not a fixed value, because it is frequently perturbed by the gravity of the planets. Near perihelion, using an August 2011 epoch, Kazuo Kinoshita shows C/2010 X1 to have a heliocentric orbital period of 600,000 years, though more perturbations will occur.  For objects at such high eccentricity, the Sun's barycentric coordinates are more stable than heliocentric coordinates. The orbit of a long-period comet is properly obtained when the osculating orbit is computed at an epoch after leaving the planetary region and is calculated with respect to the center of mass of the Solar System. Using JPL Horizons with an observed orbital arc of 235 days, the barycentric orbital elements for epoch 2020-Jan-01 generate a semi-major axis of 518 AU and a period of approximately 11,800 years.

text: Given the

text: orbital eccentricity

text: of this object, its

text: orbital period

text: is not a fixed value, because it is frequently

text: perturbed

text: by the gravity of the planets. Near perihelion, using an August 2011 epoch, Kazuo Kinoshita shows C/2010 X1 to have a heliocentric orbital period of 600,000 years, though more perturbations will occur.  For objects at such high eccentricity, the Sun's

text: barycentric coordinates

text: are more stable than heliocentric coordinates. The orbit of a long-period comet is properly obtained when the

text: osculating orbit

text: is computed at an

text: epoch

text: after leaving the planetary region and is calculated with respect to the

text: center of mass of the Solar System

text: . Using

text: JPL Horizons

text: with an observed orbital

text: arc

text: of 235 days, the barycentric orbital elements for epoch 2020-Jan-01 generate a

text: semi-major axis

text: of 518 AU and a period of approximately 11,800 years.

text: Although each planet has unique physical characteristics, a number of broad commonalities do exist among them. Some of these characteristics, such as rings or natural satellites, have only as yet been observed in planets in the Solar System, whereas others are also commonly observed in extrasolar planets.

text: In the late 21st Century, Earth is overcrowded and polluted. An alien race from the Dark Star Solar System called "The Wipers," who look human, start to colonize the planet and go about destroying communication and data technology. In 2117, humans start to evacuate the planet for a place called the White Crystal Solar System.  In 2123, the last of the humans are getting ready to evacuate. Meanwhile, a group of librarians, led by Ms. Bookhart, have built an underground library to protect all human knowledge from the Wipers.  While they are finishing up before they leave for the evacuation site they discover that one book, the third volume of "The History of Wipers on Earth," is missing.  Desperate to find that book, Ms. Bookhart drives the bookmobile to the house of the last person who borrowed that book to see if he forgot to return it.  When she arrives she discovers a Wiper is there destroying everything.  On her way to the evacuation site the bookmobile stalls.  As she is looking for tools to fix the vehicle, a being who calls himself "The Universal Being" appears and puts her in a deep sleep.  The other librarians go to the evacuation site and are sad to leave without Ms. Bookhart, not knowing what happened to her or the missing book.

text: In the late 21st Century,

text: Earth

text: is overcrowded and polluted. An alien race from the Dark Star Solar System called "The Wipers," who look human, start to colonize the planet and go about destroying communication and data technology. In 2117, humans start to evacuate the planet for a place called the White Crystal Solar System.  In 2123, the last of the humans are getting ready to evacuate. Meanwhile, a group of librarians, led by Ms. Bookhart, have built an underground

text: library

text: to protect all human knowledge from the Wipers.  While they are finishing up before they leave for the evacuation site they discover that one book, the third volume of "The

text: History

text: of Wipers on Earth," is missing.  Desperate to find that book, Ms. Bookhart drives the bookmobile to the house of the last person who borrowed that book to see if he forgot to return it.  When she arrives she discovers a Wiper is there destroying everything.  On her way to the evacuation site the bookmobile stalls.  As she is looking for tools to fix the vehicle, a being who calls himself "The Universal Being" appears and puts her in a deep sleep.  The other librarians go to the evacuation site and are sad to leave without Ms. Bookhart, not knowing what happened to her or the missing book.

text: An orrery is a mechanical model of the solar system that illustrates or predicts the relative positions and motions of the planets and moons, usually according to the heliocentric model. It may also represent the relative sizes of these bodies; but since accurate scaling is often not practical due to the actual large ratio differences, a subdued approximation may be used instead. Though the Greeks had working planetaria, the first orrery that was a planetarium of the modern era was produced in 1704, and one was presented to Charles Boyle, 4th Earl of Orrery – whence came the name. They are typically driven by a clockwork mechanism with a globe representing the Sun at the centre, and with a planet at the end of each of the arms.

text: An orrery is a mechanical

text: model of the solar system

text: that illustrates or predicts the relative positions and motions of the

text: planet

text: s and

text: moon

text: s, usually according to the

text: heliocentric

text: model

text: . It may also represent the relative sizes of these bodies; but since accurate scaling is often not practical due to the actual large ratio differences, a subdued approximation may be used instead. Though the Greeks had working

text: planetaria

text: , the first orrery that was a planetarium of the modern era was produced in 1704, and one was presented to

text: Charles Boyle, 4th Earl of Orrery

text: – whence came the name. They are typically driven by a

text: clockwork

text: mechanism with a globe representing the

text: Sun

text: at the centre, and with a planet at the end of each of the arms.

text: An active solar water heating system can be equipped with a bubble pump (also known as geyser pump) instead of an electric pump. A bubble pump circulates the heat transfer fluid (HTF) between collector and storage tank using solar power, without any external energy source, and is suitable for flat panel as well as vacuum tube systems. In a bubble pump system, the closed HTF circuit is under reduced pressure, which causes the liquid to boil at low temperature as it is heated by the sun. The steam bubbles form a geyser pump, causing an upward flow. The system is designed such that the bubbles are separated from the hot fluid and condensed at the highest point in the circuit, after which the fluid flows downward toward the heat exchanger caused by the difference in fluid levels. The HTF typically arrives at the heat exchanger at 70 °C and returns to the circulating pump at 50 °C. In frost-prone climates the HTF is water with propylene glycol anti-freeze added, usually in the ratio of 60 to 40. Pumping typically starts at about 50 °C and increases as the sun rises until equilibrium is reached, which depends on the efficiency of the heat exchanger, the temperature of the water being heated, and the total solar energy available.

text: Considered a detached object,  is particularly unusual for two reasons. With an inclination of 47 degrees, it is the largest possible dwarf planet that has an inclination larger than 45 degrees, traveling further "up and down" than "left to right" around the Sun when viewed edge-on along the ecliptic. Second, it has an unusually circular orbit for a scattered-disc object (SDO). Although it is thought that traditional scattered-disc objects have been ejected into their current orbits by gravitational interactions with Neptune, the low eccentricity of its orbit and the distance of its perihelion (SDOs generally have highly eccentric orbits and perihelia less than 38 AU) seems hard to reconcile with such celestial mechanics. This has led to some uncertainty as to the current theoretical understanding of the outer Solar System. The theories include close stellar passages, rogue planets/planetary embryos in the early Kuiper belt, and resonance interaction with an outward-migrating Neptune. The Kozai mechanism is capable of transferring orbital eccentricity to a higher inclination.

text: Considered a

text: detached object

text: ,  is particularly unusual for two reasons. With an

text: inclination

text: of 47 degrees, it is the largest

text: possible dwarf planet

text: that has an inclination larger than 45 degrees, traveling further "up and down" than "left to right" around the

text: Sun

text: when viewed edge-on along the

text: ecliptic

text: . Second, it has an unusually circular orbit for a

text: scattered-disc object

text: (SDO). Although it is thought that traditional scattered-disc objects have been ejected into their current orbits by gravitational interactions with

text: Neptune

text: , the low eccentricity of its orbit and the distance of its perihelion (SDOs generally have highly eccentric orbits and perihelia less than 38 AU) seems hard to reconcile with such celestial mechanics. This has led to some uncertainty as to the current theoretical understanding of the outer

text: Solar System

text: . The theories include close stellar passages,

text: rogue planet

text: s/

text: planetary embryo

text: s in the early

text: Kuiper belt

text: , and

text: resonance

text: interaction with an

text: outward

text: migrating Neptune

text: . The

text: Kozai mechanism

text: is capable of transferring orbital eccentricity to a higher inclination.

text: The prospects of colonizing the Solar System planets dimmed as they became known to be not very hospitable to life. However, the asteroids came to be imagined as a vast accumulation of mineral wealth, accessible in conditions of minimal gravity, and supplementing Earth's presumably dwindling resources—though the value of such minerals would have to be very high indeed to make such enterprises economically viable. Stories of asteroid mining multiplied after the late 1940s, accompanied by descriptions of a society living in caves or domes on asteroids, or (unscientifically) providing the asteroid with an atmosphere held in place by an "artificial gravity".

text: The demotion of Pluto to a dwarf planet brought the number of planets in our solar system to eight.

text: The demotion of

text: Pluto

text: to a

text: dwarf planet

text: brought the number of planets in our

text: solar system

text: to eight.

text: SWEEPS-11 is an extrasolar planet orbiting the star SWEEPS J175902.67−291153.5 in the constellation Sagittarius, approximately 27,710 light years away from the Solar System (based on a distance modulus of 14.1), making it (along with SWEEPS-04) the most distant exoplanet(s) known. This planet was found in 2006 by the Sagittarius Window Eclipsing Extrasolar Planet Search (SWEEPS) program that uses the transit method.

text: SWEEPS-11 is an

text: extrasolar planet

text: orbiting the

text: star

text: SWEEPS J175902.67−291153.5 in the

text: constellation

text: Sagittarius

text: , approximately 27,710

text: light year

text: s away from the

text: Solar System

text: (based on a

text: distance modulus

text: of 14.1), making it (along with

text: (SWEEPS) program that uses the

text: transit method

text: Various alternative versions of Gravity appear in the What If? storylines What If? Secret Wars #1 (2009), What If? House of M #1 (2009), What If? Spider-Man of House of M #1 (2009), and What If? Secret Invasion #1 (2010) in minor and cameo roles.

text: Various alternative versions of Gravity appear in the

text: What If?

text: storylines What If?

text: Secret Wars

text: #1 (2009), What If?

text: House of M

text: #1 (2009), What If? Spider-Man of House of M #1 (2009), and What If?

text: Secret Invasion

text: #1 (2010) in minor and cameo roles.

text: The Heliophysics Science Division of the Goddard Space Flight Center (NASA) conducts research on the Sun, its extended solar system environment (the heliosphere), and interactions of Earth, other planets, small bodies, and interstellar gas with the heliosphere. Division research also encompasses geospace—Earth's uppermost atmosphere, the ionosphere, and the magnetosphere—and the changing environmental conditions throughout the coupled heliosphere (solar system weather).

text: The Heliophysics Science Division of the

text: Goddard Space Flight Center

text: NASA

text: ) conducts research on the

text: Sun

text: , its extended

text: solar system

text: environment (the

text: heliosphere

text: ), and interactions of

text: Earth

text: , other planets,

text: small bodies

text: , and

text: interstellar gas

text: with the heliosphere. Division research also encompasses

text: geospace

text: —Earth's uppermost atmosphere, the

text: ionosphere

text: , and the

text: magnetosphere

text: —and the changing environmental conditions throughout the coupled heliosphere (solar system weather).

text: The constellation contains the star recently named Kepler-10 which has been confirmed to be orbited by Kepler-10b, the smallest rocky Earth-sized planet yet detected outside of the Solar System.

text: The constellation contains the star recently named

text: which has been confirmed to be orbited by

text: , the smallest rocky Earth-sized planet yet detected outside of the

text: Solar System

text: Different bodies of the Solar System receive light of an intensity inversely proportional to the square of their distance from Sun. A rough table comparing the amount of solar radiation received by each planet in the Solar System follows (from data in ):

text: Different bodies of the

text: Solar System

text: receive light of an intensity inversely proportional to the square of their distance from Sun. A rough table comparing the amount of solar radiation received by each planet in the Solar System follows (from data in ):

text: In the Earth's atmosphere, gravity waves are a mechanism that produce the transfer of momentum from the troposphere to the stratosphere and mesosphere. Gravity waves are generated in the troposphere by frontal systems or by airflow over mountains. At first, waves propagate through the atmosphere without appreciable change in mean velocity.  But as the waves reach more rarefied (thin) air at higher altitudes, their amplitude increases, and nonlinear effects cause the waves to break, transferring their momentum to the mean flow. This transfer of momentum is responsible for the forcing of the many large-scale dynamical features of the atmosphere. For example, this momentum transfer is partly responsible for the driving of the Quasi-Biennial Oscillation, and in the mesosphere, it is thought to be the major driving force of the Semi-Annual Oscillation. Thus, this process plays a key role in the dynamics of the middle atmosphere.

text: In the

text: Earth's

text: atmosphere

text: , gravity waves are a mechanism that produce the transfer of

text: momentum

text: from the

text: troposphere

text: to the

text: stratosphere

text: and

text: mesosphere

text: . Gravity waves are generated in the troposphere by

text: frontal systems

text: or by airflow over

text: mountain

text: s. At first, waves propagate through the atmosphere without appreciable change in

text: mean

text: velocity

text: .  But as the waves reach more rarefied (thin) air at higher

text: altitude

text: s, their

text: amplitude

text: increases, and

text: nonlinear effects

text: cause the waves to break, transferring their momentum to the mean flow. This transfer of momentum is responsible for the forcing of the many large-scale dynamical features of the atmosphere. For example, this momentum transfer is partly responsible for the driving of the

text: Quasi-Biennial Oscillation

text: , and in the

text: mesosphere

text: , it is thought to be the major driving force of the Semi-Annual Oscillation. Thus, this process plays a key role in the

text: dynamics

text: of the middle

text: atmosphere

text: The USOS solar arrays are arranged as four wing pairs, with each wing producing nearly 32.8 kW. These arrays normally track the sun to maximise power generation. Each array is about 375 m (450 yd) in area and  long. In the complete configuration, the solar arrays track the sun by rotating the alpha gimbal once per orbit; the beta gimbal follows slower changes in the angle of the sun to the orbital plane. The Night Glider mode aligns the solar arrays parallel to the ground at night to reduce the significant aerodynamic drag at the station's relatively low orbital altitude.

text: The USOS solar arrays are arranged as four wing pairs, with each wing producing nearly 32.8 kW. These arrays normally track the sun to maximise power generation. Each array is about 375 m (450 yd) in area and  long. In the complete configuration, the solar arrays track the sun by rotating the alpha

text: gimbal

text: once per orbit; the beta gimbal follows slower changes in the angle of the sun to the orbital plane. The

text: Night Glider mode

text: aligns the solar arrays parallel to the ground at night to reduce the significant aerodynamic drag at the station's relatively low orbital altitude.

text: All the rocky planets in the solar system except Earth are generally believed to be in the stagnant lid geodynamic regime. Mars and particularly Venus have evidence of prior resurfacing events, but appear to be tectonically quiescent today. Geodynamic inferences about solar system planets have been extrapolated to exoplanets in order to constrain what kind of geodynamic regimes can be expected given a set of physical criterion such as planetary radius, presence of surface water, and insolation. In particular, the planet Venus has been intensely studied due to its general physical similarities to Earth yet completely different geodynamic regime. Proposed explanations include a lack of surface water, the lack of a magnetic geodynamo, or large-scale evacuation of interior heat shortly after planetary coalescence.

text: All the rocky planets in the solar system except Earth are generally believed to be in the stagnant lid geodynamic regime.

text: Mars

text: and particularly

text: Venus

text: have evidence of prior resurfacing events, but appear to be tectonically quiescent today. Geodynamic inferences about solar system planets have been extrapolated to exoplanets in order to constrain what kind of geodynamic regimes can be expected given a set of physical criterion such as planetary radius, presence of surface water, and insolation. In particular, the planet Venus has been intensely studied due to its general physical similarities to Earth yet completely different geodynamic regime. Proposed explanations include a lack of surface water, the lack of a magnetic geodynamo, or large-scale evacuation of interior heat shortly after planetary coalescence.

text: Solar thermal power stations include the 354 megawatt (MW) Solar Energy Generating Systems power plant in the USA, Solnova Solar Power Station (Spain, 150 MW), Andasol solar power station (Spain, 100 MW), Nevada Solar One (USA, 64 MW), PS20 solar power tower (Spain, 20 MW), and the PS10 solar power tower (Spain, 11 MW). The 370 MW Ivanpah Solar Power Facility, located in California's Mojave Desert, is the world's largest solar-thermal power plant project currently under construction. Many other plants are under construction or planned, mainly in Spain and the USA. In developing countries, three World Bank projects for integrated solar thermal/combined-cycle gas-turbine power plants in Egypt, Mexico, and Morocco have been approved.

text: Solar thermal power

text: stations include the 354

text: megawatt

text: (MW)

text: Solar Energy Generating Systems

text: power plant in the USA,

text: Solnova Solar Power Station

text: (Spain, 150 MW),

text: Andasol solar power station

text: (Spain, 100 MW),

text: Nevada Solar One

text: (USA, 64 MW),

text: PS20 solar power tower

text: (Spain, 20 MW), and the

text: PS10 solar power tower

text: (Spain, 11 MW). The 370 MW

text: Ivanpah Solar Power Facility

text: , located in California's

text: Mojave Desert

text: , is the world's largest solar-thermal power plant project currently under construction. Many other plants are under construction or planned, mainly in Spain and the USA. In developing countries, three

text: World Bank

text: projects for integrated solar thermal/combined-cycle gas-turbine power plants in

text: Egypt

text: Mexico

text: , and

text: Morocco

text: have been approved.

text: The formation of the Solar System began 4.6 billion years ago with the gravitational collapse of a small part of a giant molecular cloud. Most of the collapsing mass collected in the center, forming the Sun, while the rest flattened into a protoplanetary disk out of which the planets, moons, asteroids, and other small Solar System bodies formed.

text: The formation of the

text: Solar System

text: began 4.6

text: billion

text: years ago with the

text: gravitational collapse

text: of a small part of a giant

text: molecular cloud

text: . Most of the collapsing mass collected in the center, forming the

text: Sun

text: , while the rest flattened into a

text: protoplanetary disk

text: out of which the

text: planet

text: s,

text: moons

text: asteroid

text: s, and other

text: small Solar System bodies

text: formed.

text: The center of mass is the average position of all the objects weighed by mass. The Sun is so massive that the Solar System's center of mass is very close to the center of the Sun. However, the gas giants are far enough from the sun that the center of mass of the Solar System can be outside the Sun, despite the Sun having most of the mass of the Solar System.

text: Beyond then turns to the potential for living and working in space, and the place in the Solar System where we might establish a permanent base. Economic models suggest that a viable space activity can be based on recreation, scientific research, and mining. In addition, there is an enormous amount of habitable real estate revealed by discoveries of extrasolar planets, but the difficulty of traveling beyond the Solar System will keep this beyond reach for a long time. More ambitious approaches include terraforming, where an entire planet or moon is altered to allow human habitation.

text: Beyond then turns to the potential for living and working in space, and the place in the

text: Solar System

text: where we might establish a permanent base.

text: Economic models

text: suggest that a viable space activity can be based on

text: recreation

text: scientific research

text: , and

text: mining

text: . In addition, there is an enormous amount of habitable real estate revealed by discoveries of

text: extrasolar planets

text: , but the difficulty of traveling beyond the Solar System will keep this beyond reach for a long time. More ambitious approaches include

text: terraforming

text: , where an entire planet or moon is altered to allow human habitation.

text: A comet is an icy small Solar System body that, when passing close to the Sun, warms and begins to evolve gasses, a process called outgassing. This produces a visible atmosphere or coma, and sometimes also a tail. These phenomena are due to the effects of solar radiation and the solar wind acting upon the nucleus of the comet. Comet nuclei range from a few hundred metres to tens of kilometres across and are composed of loose collections of ice, dust, and small rocky particles. The coma may be up to 15 times the Earth's diameter, while the tail may stretch one astronomical unit. If sufficiently bright, a comet may be seen from the Earth without the aid of a telescope and may subtend an arc of 30° (60 Moons) across the sky. Comets have been observed and recorded since ancient times by many cultures.

text: A comet is an icy

text: small Solar System body

text: that, when passing close to the

text: Sun

text: , warms and begins to evolve gasses, a process called

text: outgassing

text: . This produces a visible atmosphere or

text: coma

text: , and sometimes also a

text: tail

text: . These phenomena are due to the effects of

text: solar radiation

text: and the

text: solar wind

text: acting upon the nucleus of the comet.

text: Comet nuclei

text: range from a few hundred metres to tens of kilometres across and are composed of loose collections of ice, dust, and small rocky particles. The coma may be up to 15 times the Earth's diameter, while the tail may stretch one

text: astronomical unit

text: . If sufficiently bright, a comet may be seen from the Earth without the aid of a telescope and may subtend an arc of 30° (60 Moons) across the sky. Comets have been observed and recorded since ancient times by many cultures.

text: The Nebula is part of a much larger nebula that is known as the Orion Molecular Cloud Complex. The Orion Molecular Cloud Complex extends throughout the constellation of Orion and includes Barnard's Loop, the Horsehead Nebula, M43, M78, and the Flame Nebula. Stars are forming throughout the entire Cloud Complex, but most of the young stars are concentrated in dense clusters like the one illuminating the Orion Nebula.

text: The Nebula is part of a much larger nebula that is known as the

text: Orion Molecular Cloud Complex

text: . The Orion Molecular Cloud Complex extends throughout the

text: constellation

text: of

text: Orion

text: and includes

text: Barnard's Loop

text: , the

text: Horsehead Nebula

text: , and the

text: Flame Nebula

text: . Stars are forming throughout the entire Cloud Complex, but most of the young stars are concentrated in dense clusters like the one illuminating the Orion Nebula.

text: The VLBI radio observations of Sagittarius A* could also be aligned centrally with the images so S2 could be seen to orbit Sagittarius A*. From examining the Keplerian orbit of S2, they determined the mass of Sagittarius A* to be 2.6 ± 0.2 million solar masses, confined in a volume with a radius no more than 17 light-hours (120 AU). Later observations of the star S14 showed the mass of the object to be about 4.1 million solar masses within a volume with radius no larger than 6.25 light-hours (45 AU) or about 6.7 billion kilometres. They also determined the distance from Earth to the Galactic Center (the rotational center of the Milky Way), which is important in calibrating astronomical distance scales, as 8.0 ± 0.6 × 10 parsecs. In November 2004 a team of astronomers reported the discovery of a potential intermediate-mass black hole, referred to as GCIRS 13E, orbiting three light-years from Sagittarius A*. This black hole of 1,300 solar masses is within a cluster of seven stars. This observation may add support to the idea that supermassive black holes grow by absorbing nearby smaller black holes and stars.

text: The VLBI radio observations of Sagittarius A* could also be aligned centrally with the images so S2 could be seen to orbit Sagittarius A*. From examining the

text: Keplerian orbit

text: of S2, they determined the mass of Sagittarius A* to be 2.6 ± 0.2 million

text: solar mass

text: es, confined in a volume with a radius no more than 17 light-hours (120

text: AU

text: ). Later observations of the star S14 showed the mass of the object to be about 4.1 million solar masses within a volume with radius no larger than 6.25 light-hours (45 AU) or about 6.7 billion

text: kilometres

text: . They also determined the distance from Earth to the

text: Galactic Center

text: (the rotational center of the Milky Way), which is important in calibrating astronomical distance scales, as 8.0 ± 0.6 × 10

text: parsec

text: s. In November 2004 a team of astronomers reported the discovery of a potential

text: intermediate-mass black hole

text: , referred to as

text: GCIRS 13E

text: , orbiting three light-years from Sagittarius A*. This black hole of 1,300 solar masses is within a cluster of seven stars. This observation may add support to the idea that supermassive black holes grow by absorbing nearby smaller black holes and stars.

text: Kepler-11e is an exoplanet (extrasolar planet) discovered in the orbit of the sunlike star Kepler-11. It is the fourth of six planets around Kepler-11 discovered by NASA's Kepler spacecraft. Kepler-11e was found by using the transit method, in which the dimming effect that a planet causes as it crosses in front of its star is measured. Kepler-11e is most likely a gas giant like Neptune, having a density that is less than that of Saturn, the least dense planet in the Solar System. Its low density can probably be attributed to a large hydrogen and helium atmosphere.  Kepler-11e has a mass eight times of Earth's mass and a radius 4.5 times that of Earth. The planet orbits its star every 31 days in an ellipse that would fit within the orbit of Mercury. Kepler-11e was announced on February 2, 2011 with its five sister planets after it was confirmed by several observatories.

text: Kepler-11e is an

text: exoplanet

text: (extrasolar planet) discovered in the orbit of the sunlike star

text: . It is the fourth of six planets around Kepler-11 discovered by

text: NASA

text: 's

text: Kepler spacecraft

text: . Kepler-11e was found by using the

text: transit method

text: , in which the dimming effect that a planet causes as it crosses in front of its star is measured. Kepler-11e is most likely a

text: gas giant

text: like

text: Neptune

text: , having a density that is less than that of

text: Saturn

text: , the least dense planet in the Solar System. Its low density can probably be attributed to a large hydrogen and helium atmosphere.  Kepler-11e has a mass eight times of Earth's mass and a radius 4.5 times that of Earth. The planet orbits its star every 31 days in an ellipse that would fit within the orbit of

text: Mercury

text: . Kepler-11e was announced on February 2, 2011 with its five sister planets after it was confirmed by several observatories.

text: Copernicus' major work, De revolutionibus orbium coelestium - On the Revolutions of the Heavenly Spheres (first edition 1543 in Nuremberg, second edition 1566 in Basel), was published during the year of his death, though he had arrived at his theory several decades earlier. The book marks the beginning of the shift away from a geocentric (and anthropocentric) universe with the Earth at its center. Copernicus held that the Earth is another planet revolving around the fixed sun once a year, and turning on its axis once a day. But while Copernicus put the Sun at the center of the celestial spheres, he did not put it at the exact center of the universe, but near it. Copernicus' system used only uniform circular motions, correcting what was seen by many as the chief inelegance in Ptolemy's system.

text: Copernicus' major work,

text: De revolutionibus orbium coelestium

text: - On the Revolutions of the Heavenly Spheres (first edition 1543 in Nuremberg, second edition 1566 in

text: Basel

text: ), was published during the year of his death, though he had arrived at his theory several decades earlier. The book marks the beginning of the shift away from a

text: geocentric

text: (and

text: anthropocentric

text: ) universe with the Earth at its center. Copernicus held that the Earth is another

text: planet

text: revolving around the fixed sun once a year, and turning on its

text: axis

text: once a day. But while Copernicus put the Sun at the center of the celestial spheres, he did not put it at the exact center of the universe, but near it. Copernicus' system used only uniform circular motions, correcting what was seen by many as the chief inelegance in Ptolemy's system.

text: The idea of planets has evolved over its history, from the divine lights of antiquity to the earthly objects of the scientific age. The concept has expanded to include worlds not only in the Solar System, but in hundreds of other extrasolar systems. The ambiguities inherent in defining planets have led to much scientific controversy.

text: In their initial paper Batygin and Brown proposed that Planet Nine formed closer to the Sun and was ejected onto a distant eccentric orbit following a close encounter with Jupiter or Saturn during the nebular epoch. Gravitational interactions with nearby stars in the Sun's birth cluster, or dynamical friction from the gaseous remnants of the solar nebula, then reduced the eccentricity of its orbit, raising its perihelion, leaving it on a very wide but stable orbit. Had it not been flung into the Solar System's farthest reaches, Planet Nine could have accreted more mass from the proto-planetary disk and developed into the core of a gas giant. Instead, its growth was halted early, leaving it with a lower mass of five times Earth's mass, similar to that of Uranus and Neptune. For Planet Nine to have been captured in a distant, stable orbit its ejection must have occurred early, between three million and ten million years after the formation of the Solar System. This timing suggests that Planet Nine is not the planet ejected in a five-planet version of the Nice model, unless that occurred too early to be the cause of the Late Heavy Bombardment, which would then require another explanation. These ejections, however, are likely to have been two events well separated in time.

text: In their initial paper Batygin and Brown proposed that Planet Nine formed closer to the Sun and was ejected onto a distant eccentric orbit following a close encounter with

text: Jupiter

text: or

text: Saturn

text: during the nebular

text: epoch

text: . Gravitational interactions with nearby stars in the Sun's

text: birth cluster

text: , or dynamical friction from the

text: gaseous remnants of the solar nebula

text: , then reduced the eccentricity of its orbit, raising its perihelion, leaving it on a very wide but stable orbit. Had it not been flung into the Solar System's farthest reaches, Planet Nine could have accreted more mass from the

text: proto-planetary disk

text: and developed into the core of a

text: gas giant

text: . Instead, its growth was halted early, leaving it with a lower mass of five times Earth's mass, similar to that of Uranus and Neptune. For Planet Nine to have been captured in a distant, stable orbit its ejection must have occurred early, between three million and ten million years after the formation of the Solar System. This timing suggests that Planet Nine is not the planet ejected in a five-planet version of the Nice model, unless that occurred too early to be the cause of the

text: Late Heavy Bombardment

text: , which would then require another explanation. These ejections, however, are likely to have been two events well separated in time.

text: Sunlight Solar Energy is a national solar power company specializing in the design, finance, installation, and management of commercial and residential solar electric, solar hot water, solar pool, and radiant floor systems.  Sunlight Solar was founded in 1988 by Paul Israel, a graduate of Temple University and co-founder of the Central Oregon Green and Solar Tour.  The company opened its first location in Redmond, Oregon in 1997 and began installing solar for RV's, solar hot water, and off-grid solar electric systems.  In 2003 the company moved operations to Bend, Oregon where the office's 3.6 Kilowatt photovoltaic system is monitored by Frank Vignola of the University of Oregon Solar Radiation Monitoring Lab which helped the Energy Trust of Oregon and Christopher Dymond of the Oregon Department of Energy calculate performance expectations for solar power production in Central Oregon.  In 2004 a state solar incentive program encouraged the company's expansion of operations to Milford, Connecticut.  In 2006 they became a premier dealer for SunPower photovoltaic panels.  In 2008 Sunlight Solar was awarded Sunpower's "Intelegant" award for excellence.  In 2008 Sunlight Solar won the Central Oregon Builder's Association award for  "Sub-Contractor of the Year".  In 2009 the company expanded to Waltham, Massachusetts.  In 2010 the company opened an office in Portland, Oregon.  In 2010 Sunlight Solar partnered with Habitat for Humanity to install 25 photovoltaic systems on new production high performance homes.

text: Sunlight Solar Energy is a national

text: solar power

text: company specializing in the design, finance, installation, and management of commercial and residential

text: solar electric

text: solar hot water

text: solar pool

text: , and

text: radiant floor

text: systems.  Sunlight Solar was founded in 1988 by Paul Israel, a graduate of

text: Temple University

text: and co-founder of the Central Oregon Green and Solar Tour.  The company opened its first location in

text: Redmond, Oregon

text: in 1997 and began installing solar for RV's, solar hot water, and off-grid solar electric systems.  In 2003 the company moved operations to

text: Bend, Oregon

text: where the office's 3.6 Kilowatt photovoltaic system is monitored by Frank Vignola of the University of Oregon Solar Radiation Monitoring Lab which helped the Energy Trust of Oregon and Christopher Dymond of the Oregon Department of Energy calculate performance expectations for solar power production in Central Oregon.  In 2004 a state solar incentive program encouraged the company's expansion of operations to

text: Milford, Connecticut

text: .  In 2006 they became a premier dealer for

text: SunPower

text: photovoltaic

text: panels.  In 2008 Sunlight Solar was awarded Sunpower's "Intelegant" award for excellence.  In 2008 Sunlight Solar won the Central Oregon Builder's Association award for  "Sub-Contractor of the Year".  In 2009 the company expanded to

text: Waltham, Massachusetts

text: .  In 2010 the company opened an office in

text: Portland, Oregon

text: .  In 2010 Sunlight Solar partnered with

text: Habitat for Humanity

text: to install 25 photovoltaic systems on new production high performance homes.

text: The total sum of all solar fluctuations is referred to as solar variation. The collective effect of all solar variations within the Sun's gravitational field is referred to as space weather. A major weather component is the solar wind, a stream of plasma released from the Sun's upper atmosphere. It is responsible for the aurora, natural light displays in the sky in the Arctic and Antarctic. Space weather disturbances can cause solar storms on Earth, disrupting communications, as well as geomagnetic storms in Earth's magnetosphere and sudden ionospheric disturbances in the ionosphere. Variations in solar intensity also affect Earth's climate. These variations can explain events such as ice ages and the Great Oxygenation Event, while the Sun's future expansion into a red giant will likely end life on Earth.

text: The total sum of all solar fluctuations is referred to as solar variation. The collective effect of all solar variations within the Sun's gravitational field is referred to as

text: space weather

text: . A major weather component is the

text: solar wind

text: , a stream of

text: plasma

text: released from the Sun's upper atmosphere. It is responsible for the

text: aurora

text: , natural light displays in the sky in the

text: Arctic

text: and

text: Antarctic

text: . Space weather disturbances can cause

text: solar storms

text: on Earth, disrupting communications, as well as

text: geomagnetic storm

text: s in Earth's

text: magnetosphere

text: and

text: sudden ionospheric disturbance

text: s in the

text: ionosphere

text: . Variations in solar intensity also affect Earth's climate. These variations can explain events such as ice ages and the

text: Great Oxygenation Event

text: , while the Sun's future expansion into a

text: red giant

text: will likely end life on Earth.

text: A rooftop photovoltaic power station, or rooftop PV system, is a photovoltaic system that has its electricity-generating solar panels mounted on the rooftop of a residential or commercial building or structure. The various components of such a system include photovoltaic modules, mounting systems, cables, solar inverters and other electrical accessories.

text: A rooftop photovoltaic power station, or rooftop PV system, is a

text: photovoltaic system

text: that has its

text: electricity

text: -generating

text: solar panel

text: s mounted on the rooftop of a residential or commercial building or structure. The various components of such a system include

text: photovoltaic module

text: s,

text: mounting systems

text: cables

text: solar inverter

text: s and other electrical accessories.

text: In Alien Planet, a more basic scenario is presented where a ship called the Von Braun is sent to explore an alien world outside the solar system. The Von Braun is sent to a binary star system about 6.5 light-years from Earth.  At 20% of the speed of light (0.2c), it takes about 32.5 years to travel to this system. Upon arrival it goes into orbit around Darwin IV, the Von Braun deployed the Darwin Reconnaissance Orbiter to scan the planet from orbit. The Von Braun also dispatches three identically shaped lighter-than-air probes to the planet surface. These three probes are:

text: In Alien Planet, a more basic scenario is presented where a ship called the

text: Von Braun

text: is sent to explore an alien world outside the

text: solar system

text: . The Von Braun is sent to a binary star system about 6.5 light-years from Earth.  At 20% of the speed of light (0.2c), it takes about 32.5 years to travel to this system. Upon arrival it goes into orbit around Darwin IV, the Von Braun deployed the Darwin Reconnaissance Orbiter to scan the planet from orbit. The Von Braun also dispatches three identically shaped

text: lighter-than-air

text: probes to the planet surface. These three probes are:

text: However, studies suggest that Earth already lies near to the inner edge of the habitable zone of the Solar System, and that may harm its long-term livability as the luminosities of main-sequence stars steadily increase over time, pushing the habitable zone outwards. Therefore, superhabitable exoplanets must be warmer than Earth, yet orbit further out than Earth does and closer to the center of the system's habitable zone. This would be possible with a thicker atmosphere or with a higher concentration of greenhouse gases.

text: However, studies suggest that Earth already lies near to the inner edge of the habitable zone of the

text: Solar System

text: , and that may harm its long-term livability as the luminosities of main-sequence stars steadily increase over time, pushing the habitable zone outwards. Therefore, superhabitable exoplanets must be warmer than Earth, yet orbit further out than Earth does and closer to the center of the system's

text: habitable zone

text: . This would be possible with a thicker atmosphere or with a higher concentration of

text: greenhouse gas

text: es.

text: Canadian Solar production facilities in Canada, China, Indonesia, Vietnam and Brazil are structured for the manufacturing of ingots, wafers, solar cells, solar PV modules, solar power systems and specialized solar products.

text: is a possible dwarf planet in the Kuiper belt. 2015 RR is one of the few dwarf planets to survive after the formation of the solar system, along with Pluto and Eris. It was discovered in February 2016 by the Outer Solar System Origins Survey (OSSOS).

text: is a

text: possible

text: dwarf planet

text: in the

text: Kuiper belt

text: . 2015 RR is one of the few dwarf planets to survive after the

text: formation of the solar system

text: , along with

text: Pluto

text: and

text: Eris

text: . It was discovered in February 2016 by the Outer Solar System Origins Survey (OSSOS).

text: where r is the distance between the masses and G is the gravitational constant.  Given this force law and his equations of motion, Newton was able to show that two point masses attracting each other would each follow perfectly elliptical orbits.  The ratio of sizes of these ellipses is m/M, with the larger mass moving on a smaller ellipse.  If M is much larger than m, then the larger mass will appear to be stationary at the focus of the elliptical orbit of the lighter mass m.  This model can be applied approximately to the Solar System.  Since the mass of the Sun is much larger than those of the planets, the force acting on each planet is principally due to the Sun; the gravity of the planets for each other can be neglected to first approximation.

text: where r is the distance between the masses and G is the

text: gravitational constant

text: .  Given this force law and his equations of motion, Newton was able to show that two point masses attracting each other would each follow perfectly elliptical orbits.  The ratio of sizes of these ellipses is m/M, with the larger mass moving on a smaller ellipse.  If M is much larger than m, then the larger mass will appear to be stationary at the focus of the elliptical orbit of the lighter mass m.  This model can be applied approximately to the Solar System.  Since the mass of the Sun is much larger than those of the planets, the force acting on each planet is principally due to the Sun; the gravity of the planets for each other can be neglected to first approximation.

text: It is essentially a geocentric model; the Earth is at the center of the universe. The Sun and Moon and the stars revolve around the Earth, and the other five planets revolve around the Sun. It can be shown that the motions of the planets and the Sun relative to the Earth in Brahe's system are mathematically equivalent to the motions in Copernicus' heliocentric system.

text: It is essentially a

text: geocentric model

text: ; the

text: Earth

text: is at the center of the universe. The

text: Sun

text: and

text: Moon

text: and the stars revolve around the Earth, and the other five

text: planet

text: s revolve around the Sun. It can be shown that the motions of the planets and the Sun relative to the Earth in Brahe's system are mathematically equivalent to the motions in Copernicus'

text: heliocentric

text: system.

text: The ice giants represent one of two fundamentally different categories of giant planets present in the Solar System, the other group being the more-familiar gas giants, which are composed of more than 90% hydrogen and helium (by mass). Their hydrogen is thought to extend all the way down to their small rocky cores, where hydrogen molecular ion transitions to metallic hydrogen under the extreme pressures of hundreds of gigapascals (GPa).

text: The ice giants represent one of two fundamentally different categories of

text: giant planet

text: s present in the

text: Solar System

text: , the other group being the more-familiar

text: gas giant

text: s, which are composed of more than 90%

text: hydrogen

text: and

text: helium

text: (by mass). Their hydrogen is thought to extend all the way down to their small rocky cores, where

text: hydrogen molecular ion

text: transitions to

text: metallic hydrogen

text: under the extreme pressures of hundreds of

text: gigapascal

text: s (GPa).

text: The first published causal explanation of the motions of planets was Johannes Kepler's Astronomia nova published in 1609. He concluded, based on Tycho Brahe's observations of the orbit of Mars, that the orbits were ellipses. This break with ancient thought was happening around the same time that Galileo was proposing abstract mathematical laws for the motion of objects. He may (or may not) have performed the famous experiment of dropping two cannonballs of different weights from the tower of Pisa, showing that they both hit the ground at the same time. The reality of this experiment is disputed, but, more importantly, he did carry out quantitative experiments by rolling balls on an inclined plane. His theory of accelerated motion derived from the results of such experiments, and forms a cornerstone of classical mechanics.

text: The first published

text: causal

text: explanation of the motions of

text: planets

text: was Johannes Kepler's

text: Astronomia nova

text: published in 1609. He concluded, based on

text: Tycho Brahe

text: 's observations of the orbit of

text: Mars

text: , that the orbits were

text: ellipse

text: s. This break with

text: ancient thought

text: was happening around the same time that

text: Galileo

text: was proposing abstract mathematical laws for the motion of objects. He may (or may not) have performed the famous experiment of dropping two cannonballs of different weights from the

text: tower of Pisa

text: , showing that they both hit the ground at the same time. The reality of this experiment is disputed, but, more importantly, he did carry out quantitative experiments by rolling balls on an

text: inclined plane

text: . His theory of accelerated motion derived from the results of such experiments, and forms a cornerstone of classical mechanics.

text: Ter Haar and Cameron distinguished between those theories that consider a closed system, which is a development of the Sun and possibly a solar envelope, that starts with a protosun rather than the Sun itself, and state that Belot calls these theories monistic; and those that consider an open system, which is where there is an interaction between the Sun and some foreign body that is supposed to have been the first step in the developments leading to the planetary system, and state that Belot calls these theories dualistic.	Hervé Reeves' classification  also categorizes them as co-genetic with the Sun or not but also as formed from altered or unaltered stellar/interstellar material. He as well recognizes 4 groups:  1) models based on the solar nebula, originated by Swedenborg, Kant, and Laplace in the 1700s; 2) the ones proposing a cloud captured from interstellar space, major proponents being Alfvén and Gustaf Arrhenius (in 1978) and Alfvén and Arrhenius; 3) the binary hypotheses which propose that a sister star somehow disintegrated and a portion of its dissipating material was captured by the Sun, principal hypothesizer being Lyttleton in the '40s; 4) and the close-approach-filament ideas of Jeans,  Jeffreys, and Woolfson and Dormand.	In Williams and Cremin the categories are: (1) models that regard the origin and formation of the planets as being essentially related to the Sun, with the 2 formation processes taking place concurrently or consecutively, (2) models that regard formation of the planets as being independent of the formation process of the Sun, the planets forming after the Sun becomes a normal star; this has 2 subcategories: a) where the material for the formation of the planets is extracted either from the Sun or another star, b) where the material is acquired from interstellar space. They conclude that the best models are Hoyle's magnetic coupling and McCrea's floccules.

text: The Solar System contains no known super-Earths, because Earth is the largest terrestrial planet in the Solar System, and all larger planets have at least 14 times the mass of Earth.

text: The

text: Solar System

text: contains no known super-Earths, because Earth is the largest

text: terrestrial planet

text: in the Solar System, and all larger planets have at least 14 times the mass of Earth.

text: The goal is to investigate the processes of free energy accumulation in the sun's atmosphere, accelerated particle phenomena and solar flares, and the correlation between solar activity and magnetic storms on Earth. Launch occurred successfully on 30 January 2009, and the first batch of science data was downloaded from the satellite on 19 February 2009. The satellite operates in a 500 x 500 km x 82.5° polar low Earth orbit and was expected to have an operational lifetime of three years.  It developed power system problems during the first eclipse season, about six months after launch, and contact with the satellite was lost on 1 December 2009.  The satellite returned to life on December 29, after its solar panels received enough light to power its control systems, but attempts to revive the satellite failed, and the satellite is considered lost.

text: The goal is to investigate the processes of free energy accumulation in the sun's atmosphere, accelerated particle phenomena and solar flares, and the correlation between solar activity and magnetic storms on Earth. Launch occurred successfully on 30 January 2009, and the first batch of science data was downloaded from the satellite on 19 February 2009. The satellite operates in a 500 x 500 km x 82.5°

text: polar

text: low Earth orbit

text: and was expected to have an operational lifetime of three years.  It developed power system problems during the first eclipse season, about six months after launch, and contact with the satellite was lost on 1 December 2009.  The satellite returned to life on December 29, after its solar panels received enough light to power its control systems, but attempts to revive the satellite failed, and the satellite is considered lost.

text: They may be composed primarily of silicate rocks and/or metals. Within the Solar System, the terrestrial planets are the inner planets closest to the Sun.

text: They may be composed primarily of

text: silicate

text: rock

text: s and/or

text: metal

text: s. Within the

text: Solar System

text: , the terrestrial planets are the

text: inner planets

text: closest to the

text: Sun

text: On February 18, 2011, a portrait of the Solar System was published on the MESSENGER website.  The mosaic contained 34 images, acquired by the MDIS instrument during November 2010.  All the planets were visible with the exception of Uranus and Neptune, due to their vast distances from the Sun. The MESSENGER "family portrait" was intended to be complementary to the Voyager family portrait, which was acquired from the outer Solar System by Voyager 1 on February 14, 1990.

text: On February 18, 2011, a portrait of the Solar System was published on the MESSENGER website.  The mosaic contained 34 images, acquired by the MDIS instrument during November 2010.  All the planets were visible with the exception of

text: Uranus

text: and

text: Neptune

text: , due to their vast distances from the Sun. The MESSENGER "family portrait" was intended to be complementary to the

text: Voyager family portrait

text: , which was acquired from the outer Solar System by

text: Voyager 1

text: on February 14, 1990.

text: This equation is the only place where the metric (and thus gravity) enters into the theory of electromagnetism. Furthermore, the equation is invariant under a change of scale, that is, multiplying the metric by a constant has no effect on this equation. Consequently, gravity can only affect electromagnetism by changing the speed of light relative to the global coordinate system being used. Light is only deflected by gravity because it is slower when near to massive bodies. So it is as if gravity increased the index of refraction of space near massive bodies.

text: This equation is the only place where the metric (and thus gravity) enters into the theory of electromagnetism. Furthermore, the equation is invariant under a change of scale, that is, multiplying the metric by a constant has no effect on this equation. Consequently, gravity can only affect electromagnetism by changing the

text: speed of light

text: relative to the global coordinate system being used. Light is only deflected by gravity because it is slower when near to massive bodies. So it is as if gravity increased the index of refraction of space near massive bodies.

text: In Battle Network 5, he kidnaps Dr. Hikari and uses Nebula to take over the entirety of Cyberworld. As Team ProtoMan or Team Colonel slowly take back the internet, Regal prepares to activate the SoulNet system. Using SoulNet, which was developed by Tadashi Hikari and Dr. Wily to connect human emotions, and Nebula Grey, a monstrous program that is the embodiment of evil, he plans to forever corrupt the population. However, he is thwarted by MegaMan, who destroys Nebula Grey and the DarkChips. After the battle, Regal has a decade of his memory erased; the Team Colonel version of the game reveals that it was Dr. Wily that caused this amnesia. He is seen working at SciLab at the end of the game.

text: Due to the mass-density inverse-square rule, all fuzzballs need not have unimaginable densities. There are also supermassive black holes, which are found at the center of virtually all galaxies. Sagittarius A*, the black hole at the center of our Milky Way galaxy, is 4.3 million . If fuzzball theory is correct, it has a mean density that is “only” 51 times that of gold. At 3.9 billion , a fuzzball would have a radius of 77 astronomical units—about the same size as the termination shock of our solar system’s heliosphere—and a mean density equal to that of the Earth's atmosphere at sea level (1.2 kg/m).

text: Due to the mass-density inverse-square rule, all fuzzballs need not have unimaginable densities. There are also

text: supermassive black hole

text: s, which are found at the center of virtually all galaxies.

text: Sagittarius A*

text: , the black hole at the center of our Milky Way galaxy, is 4.3 million . If fuzzball theory is correct, it has a mean density that is “only” 51 times that of gold. At 3.9 billion , a fuzzball would have a radius of 77

text: astronomical unit

text: s—about the same size as the

text: termination shock

text: of our solar system’s heliosphere—and a mean density equal to that of the Earth's atmosphere at sea level (1.2 kg/m).

text: "Douglas Lin's principal research interests are in the origin of the solar system, star formation, astrophysical fluid dynamics, dynamics of stellar clusters, structure of galaxies, active galactic nuclei, and galaxy formation," according to his UCSC faculty home page. He is one of the scientists who collaborates closely with observational colleagues Burton Jones and Arnold Klemola in working towards accurate estimates of the properties of the Large Magellanic Cloud.  Lin observes that, over recent years, astronomers have newly expanded horizons within which to research.  They have progressed from having only planets within a single solar system, our own, to study, to the point where now they are currently in the midst of "a revolution in the search for extra solar planets. In little over a decade, over 200 extra solar planets have been discovered."  This growth of potential study subjects has led Lin to look toward observing the formation of planetary systems from their creation through to more mature systems, since scientists can now observe "dozens of mature systems and dozens more in birth throes."   His research goal, from the study of this rich new data, is to eventually construct "a unified theory which can explain the statistical properties of planetary systems."

text: "Douglas Lin's principal research interests are in the origin of the solar system, star formation, astrophysical fluid dynamics, dynamics of stellar clusters, structure of galaxies, active galactic nuclei, and galaxy formation," according to his UCSC faculty home page. He is one of the scientists who collaborates closely with observational colleagues

text: Burton Jones

text: and Arnold Klemola in working towards accurate estimates of the properties of the

text: Large Magellanic Cloud

text: .  Lin observes that, over recent years, astronomers have newly expanded horizons within which to research.  They have progressed from having only planets within a single solar system, our own, to study, to the point where now they are currently in the midst of "a revolution in the search for extra solar planets. In little over a decade, over 200 extra solar planets have been discovered."  This growth of potential study subjects has led Lin to look toward observing the formation of planetary systems from their creation through to more mature systems, since scientists can now observe "dozens of mature systems and dozens more in birth throes."   His research goal, from the study of this rich new data, is to eventually construct "a unified theory which can explain the statistical properties of planetary systems."

text: In the episode , a Stargate was used as a weapon capable of destroying an entire solar system. The gate was dialed into a planet in close proximity to a black hole. The gate (protected by a force field) was then sent into a star. The resulting loss of mass caused the sun to go supernova, destroying the solar system and Apophis's fleet, which was orbiting the star at that time.

text: In the episode , a Stargate was used as a weapon capable of destroying an entire solar system. The gate was dialed into a planet in close proximity to a black hole. The gate (protected by a force field) was then sent into a star. The resulting loss of mass caused the sun to go supernova, destroying the solar system and

text: Apophis

text: 's fleet, which was orbiting the star at that time.

text: Planetary environments are at the heart of essential scientific, societal and philosophical questions concerning the place of the Earth in both the Solar System and the Universe beyond, the origins of the Solar System and of life, the conditions required for life to appear and be supported, and the number of habitable worlds in the Universe.

text: The Sun's output of energetic extreme ultraviolet photons is primarily what heats the Earth's upper atmosphere and creates the ionosphere. Solar EUV radiation output undergoes constant changes, both moment to moment and over the Sun's 11-year solar cycle, and these changes are important to understand because they have a significant impact on atmospheric heating, satellite drag, and communications system degradation, including disruption of the Global Positioning System.

text: The Sun's output of energetic extreme ultraviolet photons is primarily what heats the

text: Earth

text: 's upper atmosphere and creates the

text: ionosphere

text: . Solar EUV radiation output undergoes constant changes, both moment to moment and over the Sun's 11-year

text: solar cycle

text: , and these changes are important to understand because they have a significant impact on

text: atmospheric heating

text: satellite drag

text: , and communications system degradation, including disruption of the

text: Global Positioning System

text: From ancient times until the 16th and 17th centuries, the motions of the planets were believed to follow perfectly circular geocentric paths as taught by the ancient Greek philosophers Aristotle and Ptolemy. Variations in the motions of the planets were explained by smaller circular paths overlaid on the larger path (see epicycle). As measurements of the planets became increasingly accurate, revisions to the theory were proposed. In 1543, Nicolaus Copernicus published a heliocentric model of the solar system, although he still believed that the planets traveled in perfectly circular paths centered on the sun.

text: From ancient times until the 16th and 17th centuries, the motions of the planets were believed to follow perfectly circular

text: geocentric

text: paths as taught by the ancient Greek philosophers

text: Aristotle

text: and

text: Ptolemy

text: . Variations in the motions of the planets were explained by smaller circular paths overlaid on the larger path (see

text: epicycle)

text: . As measurements of the planets became increasingly accurate, revisions to the theory were proposed. In 1543,

text: Nicolaus Copernicus

text: published a

text: heliocentric

text: model of the solar system, although he still believed that the planets traveled in perfectly circular paths centered on the sun.

text: In the dense nebulae where stars are produced, much of the hydrogen is in the molecular (H) form, so these nebulae are called molecular clouds. Observations indicate that the coldest clouds tend to form low-mass stars, observed first in the infrared inside the clouds, then in visible light at their surface when the clouds dissipate, while giant molecular clouds, which are generally warmer, produce stars of all masses. These giant molecular clouds have typical densities of 100 particles per cm, diameters of , masses of up to 6 million solar masses (), and an average interior temperature of 10 K. About half the total mass of the galactic ISM is found in molecular clouds and in the Milky Way there are an estimated 6,000 molecular clouds, each with more than . The nearest nebula to the Sun where massive stars are being formed is the Orion nebula,  away. However, lower mass star formation is occurring about 400–450 light years distant in the ρ Ophiuchi cloud complex.

text: In the dense nebulae where stars are produced, much of the hydrogen is in the molecular (H) form, so these nebulae are called

text: molecular cloud

text: s. Observations indicate that the coldest clouds tend to form low-mass stars, observed first in the infrared inside the clouds, then in visible light at their surface when the clouds dissipate, while giant molecular clouds, which are generally warmer, produce stars of all masses. These giant molecular clouds have typical densities of 100 particles per cm, diameters of , masses of up to 6 million

text: solar mass

text: es (), and an average interior temperature of 10 K. About half the total mass of the galactic ISM is found in molecular clouds and in the

text: Milky Way

text: there are an estimated 6,000 molecular clouds, each with more than . The nearest nebula to the

text: Sun

text: where massive stars are being formed is the

text: Orion nebula

text: ,  away. However, lower mass star formation is occurring about 400–450 light years distant in the

text: ρ Ophiuchi cloud complex

text: The ambiguity inherent in the IAU's definition was highlighted in December 2005, when the Spitzer Space Telescope observed Cha 110913-773444 (above), only eight times Jupiter's mass with what appears to be the beginnings of its own planetary system. Were this object found in orbit around another star, it would have been termed a planet.

text: The ambiguity inherent in the IAU's definition was highlighted in December 2005, when the

text: Spitzer Space Telescope

text: observed

text: Cha 110913-773444

text: (above), only eight times Jupiter's mass with what appears to be the beginnings of its own

text: planetary system

text: . Were this object found in orbit around another star, it would have been termed a planet.

text: The vulcanoids, should they be found, may provide scientists with material from the first period of planet formation, as well as insights into the conditions prevalent in the early Solar System. Although every other gravitationally stable region in the Solar System has been found to contain objects, non-gravitational forces (such as the Yarkovsky effect) or the influence of a migrating planet in the early stages of the Solar System's development may have depleted this area of any asteroids that may have been there.

text: The vulcanoids, should they be found, may provide scientists with material from the first period of

text: planet formation

text: , as well as insights into the conditions prevalent in the early

text: Solar System

text: . Although every other gravitationally stable region in the Solar System has been found to contain objects, non-gravitational forces (such as the

text: Yarkovsky effect

text: ) or the influence of a

text: migrating planet

text: in the early stages of the Solar System's development may have depleted this area of any asteroids that may have been there.

text: A gas dwarf is a gas planet with a rocky core that has accumulated a thick envelope of hydrogen, helium, and other volatiles, having as result a total radius between 1.7 and 3.9 Earth radii (). The term is used in a three-tier, metallicity-based classification regime for short-period exoplanets, which also includes the rocky, terrestrial-like planets with less than  and planets greater than , namely ice giants and gas giants. No gas dwarfs are known to exist in the Solar System, but they are common in other planetary systems.

text: A gas dwarf is a gas planet with a rocky core that has accumulated a thick envelope of hydrogen, helium, and other

text: volatiles

text: , having as result a total radius between 1.7 and 3.9

text: Earth radii

text: (). The term is used in a three-tier,

text: metallicity

text: -based classification regime for short-period

text: exoplanet

text: s, which also includes the rocky,

text: terrestrial-like planets

text: with less than  and planets greater than , namely

text: ice giant

text: s and

text: gas giant

text: s. No gas dwarfs are known to exist in the

text: Solar System

text: , but they are common in other

text: planetary system

text: s.

text: 9934 Caccioppoli is a C-type main belt asteroid of the solar system.  It orbits the Sun once every 4.14 years.

text: 9934 Caccioppoli is a

text: C-type

text: main belt asteroid

text: of the

text: solar system

text: .  It orbits the

text: Sun

text: once every 4.14 years.

text: Morbidelli specializes in solar system dynamics, especially planetary formation and migration and the structure of the asteroid and Kuiper belts.

text: Morbidelli specializes in

text: solar system

text: dynamics

text: , especially

text: planetary formation

text: and

text: migration

text: and the structure of the

text: asteroid

text: and

text: Kuiper belt

text: s.

text: The upper and lower size and mass limits of dwarf planets have not been specified by the IAU. There is no defined upper limit, and an object larger or more massive than Mercury that has not "cleared the neighbourhood around its orbit" would be classified as a dwarf planet. The lower limit is determined by the requirements of achieving a hydrostatic equilibrium shape, but the size or mass at which an object attains this shape depends on its composition and thermal history. The original draft of the 2006 IAU resolution redefined hydrostatic equilibrium shape as applying "to objects with mass above 5 kg and diameter greater than 800 km", but this was not retained in the final draft.

text: The upper and lower size and mass limits of dwarf planets have not been specified by the IAU. There is no defined upper limit, and an object larger or more massive than

text: Mercury

text: that has not "cleared the neighbourhood around its orbit" would be classified as a dwarf planet. The lower limit is determined by the requirements of achieving a hydrostatic equilibrium shape, but the size or mass at which an object attains this shape depends on its composition and thermal history. The original draft of the 2006 IAU resolution redefined hydrostatic equilibrium shape as applying "to objects with mass above 5 kg and diameter greater than 800 km", but this was not retained in the final draft.

text: According to Zhu & Qian (2009) a third low-mass object of stellar nature could be responsible of orbital period variations observed for WZ Cep with a periodicity of roughly 32 years. Such a companion would yield a minimum mass of 0.17 Solar masses and be located 26.6 Astronomical Units (nearly the same orbital separation of Neptune in Solar System) from the eclipsing binary. The star could likely turn out a Proxima Centauri-analog, with inferred luminosity 3.7 percent that of Sun and 20 percent of its radius, according to mass-radius relationship.

text: According to Zhu & Qian (2009) a third low-mass object of stellar nature could be responsible of orbital period variations observed for WZ Cep with a periodicity of roughly 32 years. Such a companion would yield a minimum mass of 0.17

text: Solar masses

text: and be located 26.6

text: Astronomical Unit

text: s (nearly the same orbital separation of

text: Neptune

text: in

text: Solar System

text: ) from the eclipsing binary. The star could likely turn out a

text: Proxima Centauri

text: -analog, with inferred luminosity 3.7 percent that of Sun and 20 percent of its radius, according to

text: mass-radius relationship

text: The EIT wavelengths are of great interest to solar physicists because they are emitted by the very hot solar corona but not by the relatively cooler photosphere of the Sun; this reveals structures in the corona that would otherwise be obscured by the brightness of the Sun itself.  EIT was originally conceived as a viewfinder instrument to help select observing targets for the other instruments on board SOHO, but EIT is credited with a good fraction of the original science to come from SOHO, including the first observations of traveling wave phenomena in the corona, characterization of coronal mass ejection onset, and determination of the structure of coronal holes. Before mid-2010, EIT obtained an Fe XII (19.5 nm wavelength) image of the Sun about four times an hour, around the clock; these were immediately uplinked as time-lapse movies to the SOHO web site for immediate viewing by anyone who is interested.  (Since the summer of 2010, when Thorpe commissioning of the Solar Dynamics Observatory was completed, its Atmospheric Imaging Assembly has been able to take much higher resolution solar images much more frequently. The white-light coronagraphs on SOHO are thus able to take images more frequently: they share a CPU and telemetry bandwidth with EIT. The images are used for long-duration studies of the Sun, for detailed structural analyses of solar features, and for real-time space weather prediction by the NOAA Space Weather Prediction Center.

text: The EIT wavelengths are of great interest to solar physicists because they are emitted by the very hot

text: solar corona

text: but not by the relatively cooler

text: photosphere

text: of the Sun; this reveals structures in the corona that would otherwise be obscured by the brightness of the Sun itself.  EIT was originally conceived as a

text: viewfinder

text: instrument to help select observing targets for the other instruments on board SOHO, but EIT is credited with a good fraction of the original science to come from SOHO, including the first observations of traveling wave phenomena in the corona, characterization of

text: coronal mass ejection

text: onset, and determination of the structure of

text: coronal hole

text: s. Before mid-2010, EIT obtained an Fe XII (19.5 nm wavelength) image of the Sun about four times an hour, around the clock; these were immediately uplinked as time-lapse movies to the SOHO web site for immediate viewing by anyone who is interested.  (Since the summer of 2010, when Thorpe commissioning of the

text: Solar Dynamics Observatory

text: was completed, its

text: Atmospheric Imaging Assembly

text: has been able to take much higher resolution solar images much more frequently. The white-light coronagraphs on

text: SOHO

text: are thus able to take images more frequently: they share a CPU and telemetry bandwidth with EIT. The images are used for long-duration studies of the Sun, for detailed structural analyses of solar features, and for real-time

text: space weather

text: prediction by the

entity_name: National Oceanic and Atmospheric Administration

text: NOAA

text: Space Weather Prediction Center

text: Beta Lyrae variables are a class of close binary stars. Their total brightness is variable because the two component stars orbit each other, and in this orbit one component periodically passes in front of the other one, thereby blocking its light. The two component stars of Beta Lyrae systems are quite heavy (several solar masses () each) and extended (giants or supergiants). They are so close, that their shapes are heavily distorted by mutual gravitation forces: the stars have ellipsoidal shapes, and there are extensive mass flows from one component to the other.

text: Beta Lyrae variables are a class of close

text: binary star

text: s. Their total brightness is

text: variable

text: because the two component stars orbit each other, and in this orbit one component periodically passes in front of the other one, thereby blocking its light. The two component stars of Beta Lyrae systems are quite heavy (several

text: solar mass

text: es () each) and extended (

text: giants

text: or

text: supergiant

text: s). They are so close, that their shapes are heavily distorted by mutual

text: gravitation

text: forces: the stars have ellipsoidal shapes, and there are extensive mass flows from one component to the other.

text: Most of the comets seen close to the Sun seem to have reached their current positions through gravitational perturbation of the Oort cloud by the tidal force exerted by the Milky Way. Just as the Moon's tidal force deforms Earth's oceans, causing the tides to rise and fall, the galactic tide also distorts the orbits of bodies in the outer Solar System. In the charted regions of the Solar System, these effects are negligible compared to the gravity of the Sun, but in the outer reaches of the system, the Sun's gravity is weaker and the gradient of the Milky Way's gravitational field has substantial effects. Galactic tidal forces stretch the cloud along an axis directed toward the galactic centre and compress it along the other two axes; these small perturbations can shift orbits in the Oort cloud to bring objects close to the Sun. The point at which the Sun's gravity concedes its influence to the galactic tide is called the tidal truncation radius. It lies at a radius of 100,000 to 200,000 AU, and marks the outer boundary of the Oort cloud.

text: Most of the comets seen close to the Sun seem to have reached their current positions through gravitational perturbation of the Oort cloud by the

text: tidal force

text: exerted by the

text: Milky Way

text: . Just as the

text: Moon

text: 's tidal force deforms Earth's oceans, causing the tides to rise and fall, the galactic tide also distorts the orbits of bodies in the

text: outer Solar System

text: . In the charted regions of the Solar System, these effects are negligible compared to the gravity of the Sun, but in the outer reaches of the system, the Sun's gravity is weaker and the gradient of the Milky Way's gravitational field has substantial effects. Galactic tidal forces stretch the cloud along an axis directed toward the galactic centre and compress it along the other two axes; these small perturbations can shift orbits in the Oort cloud to bring objects close to the Sun. The point at which the Sun's gravity concedes its influence to the galactic tide is called the tidal truncation radius. It lies at a radius of 100,000 to 200,000 AU, and marks the outer boundary of the Oort cloud.

text: There are only a few known mean-motion resonances in the Solar System involving planets, dwarf planets or larger satellites (a much greater number involve asteroids, planetary rings, moonlets and smaller Kuiper belt objects, including many possible dwarf planets).

text: There are only a few known mean-motion resonances in the

text: Solar System

text: involving planets,

text: dwarf planet

text: s or larger

text: satellite

text: s (a much greater number involve

text: asteroid

text: s,

text: planetary ring

text: s,

text: moonlet

text: s and smaller

text: Kuiper belt

text: objects, including many

text: possible dwarf planets

text: The question of "what is an organism", and at what scale is it rational to speak about organisms vs. biospheres, gives rise to a semantic debate. We are all ecologies in the sense that our (human) bodies contain gut bacteria, parasite species, etc., and to them our body is not organism but rather more of a microclimate or biome. Applying that thinking to whole planets:

text: The question of "what is an

text: organism

text: ", and at what scale is it rational to speak about organisms vs. biospheres, gives rise to a semantic debate. We are all ecologies in the sense that our (human) bodies contain

text: gut bacteria

text: parasite

text: species, etc., and to them our body is not organism but rather more of a

text: microclimate

text: or

text: biome

text: . Applying that thinking to whole planets:

text: The equatorial coordinate system is centered at Earth's center, but fixed relative to distant stars and galaxies. The coordinates are based on the location of stars relative to Earth's equator if it were projected out to an infinite distance.  The equatorial describes the sky as seen from the solar system, and modern star maps almost exclusively use equatorial coordinates.

text: Planetary nebula cataloged as MyCn 18 discovered by Mayall and Cannon in the early 20th century, but only resolved as an hourglass shape by the Hubble Space Telescope in 1996 (see image). It is conjectured that the hourglass shape is produced by the expansion of a fast stellar wind within a slowly expanding cloud which is denser near its equator than its poles. The formation of the shape of the inner "eye" is not yet fully understood. Because of the recent resolution of the nebula's detailed appearance, it has only appeared in fictional works since 1996.

text: Planetary nebula cataloged as MyCn 18 discovered by Mayall and Cannon in the early 20th century, but only resolved as an hourglass shape by the

text: Hubble Space Telescope

text: in 1996 (see image). It is conjectured that the hourglass shape is produced by the expansion of a fast stellar wind within a slowly expanding cloud which is denser near its equator than its poles. The formation of the shape of the inner "eye" is not yet fully understood. Because of the recent resolution of the nebula's detailed appearance, it has only appeared in fictional works since 1996.

text: The Kuiper belt  or , sometimes called the Edgeworth–Kuiper belt, is a circumstellar disc in the Solar System beyond the planets, extending from the orbit of Neptune (at 30 AU) to approximately 50 AU from the Sun. It is similar to the asteroid belt, but it is far larger—20 times as wide and 20 to 200 times as massive. Like the asteroid belt, it consists mainly of small bodies, or remnants from the Solar System's formation. Although many asteroids are composed primarily of rock and metal, most Kuiper belt objects are composed largely of frozen volatiles (termed "ices"), such as methane, ammonia and water. The Kuiper belt is home to three officially recognized dwarf planets:  Pluto, Haumea, and Makemake. Some of the Solar System's moons, such as Neptune's Triton and Saturn's Phoebe, are also thought to have originated in the region.

text: The Kuiper belt  or , sometimes called the Edgeworth–Kuiper belt, is a

text: circumstellar disc

text: in the

text: Solar System

text: beyond the

text: planet

text: s, extending from the

text: orbit

text: of

text: Neptune

text: (at 30

text: AU

text: ) to approximately 50 AU from the

text: Sun

text: . It is similar to the

text: asteroid belt

text: , but it is far larger—20 times as wide and 20 to 200 times as massive. Like the asteroid belt, it consists mainly of

text: small bodies

text: , or remnants from the Solar System's formation. Although many asteroids are composed primarily of

text: rock

text: and metal, most Kuiper belt objects are composed largely of frozen

text: volatiles

text: (termed "ices"), such as

text: methane

text: ammonia

text: and

text: water

text: . The Kuiper belt is home to three officially recognized

text: dwarf planet

text: s:

text: Pluto

text: Haumea

text: , and

text: Makemake

text: . Some of the Solar System's

text: moons

text: , such as Neptune's

text: Triton

text: and

text: Saturn

text: 's

text: Phoebe

text: , are also thought to have originated in the region.

text: The visible star in the system, A, is considered to be a solar analog due close mass to the sun. HD 1237 differs from the sun in that HD 1237 is much younger, has high metallicity, has much cooler temperature and is in a binary system.  As of 2000, it has been confirmed that an extrasolar planet orbits the star.  It is of note for being a relatively Sun-like star not very far from the Sun that is home to an extrasolar planet.

text: The visible star in the system, A, is considered to be a

text: solar analog

text: due close mass to the sun. HD 1237 differs from the sun in that HD 1237 is much younger, has high metallicity, has much cooler temperature and is in a binary system.  As of 2000, it has been confirmed that an

text: extrasolar planet

text: orbits the star.  It is of note for being a relatively Sun-like star not very far from the Sun that is home to an extrasolar planet.

text: At a distance of 2.6 parsecs (8.6 ly), the Sirius system contains two of the eight nearest stars to the Solar System (not including the Sun), and is the fifth closest stellar system to ours (again not including the Sun). This proximity is the main reason for its brightness, as with other near stars such as Alpha Centauri and in stark contrast to distant, highly luminous supergiants such as Canopus, Rigel or Betelgeuse. However, it is still around 25 times more luminous than the Sun. The closest large neighbouring star to Sirius is Procyon, 1.61 parsecs (5.24 ly) away. The Voyager 2 spacecraft, launched in 1977 to study the four Jovian planets in the Solar System, is expected to pass within  of Sirius in approximately 296,000 years.

text: At a distance of 2.6 parsecs (8.6 ly), the Sirius system contains two of the eight

text: nearest stars

text: to the

text: Solar System

text: (not including the Sun), and is the fifth closest stellar system to ours (again not including the Sun). This proximity is the main reason for its brightness, as with other near stars such as

text: Alpha Centauri

text: and in stark contrast to distant, highly luminous supergiants such as Canopus, Rigel or Betelgeuse. However, it is still around 25 times more luminous than the Sun. The closest large neighbouring star to Sirius is Procyon, 1.61 parsecs (5.24 ly) away. The

text: Voyager 2

text: spacecraft, launched in 1977 to study the four

text: Jovian planets

text: in the Solar System, is expected to pass within  of Sirius in approximately 296,000 years.

text: This motion is caused by the movement of the stars relative to the Sun and Solar System. The Sun travels in a nearly circular orbit (the solar circle) about the center of the Milky Way at a speed of about 220 km/s at a radius of  from the center, which can be taken as the rate of rotation of the Milky Way itself at this radius.

text: This motion is caused by the movement of the stars relative to the

text: Sun

text: and

text: Solar System

text: . The Sun travels in a nearly circular orbit (the solar circle) about the center of the

text: Milky Way

text: at a speed of about 220 km/s at a radius of  from the center, which can be taken as the rate of rotation of the Milky Way itself at this radius.

text: The nebula's intense red output and its configuration are driven by the radiation emanating from a small group of stars near the nebula's center. This open cluster of stars known as Melotte 15 contains a few bright stars nearly 50 times the mass of our Sun, and many more dim stars that are only a fraction of our Sun's mass.

text: The nebula's intense

text: red

text: output and its configuration are driven by the radiation emanating from a small group of stars near the nebula's center. This

text: open cluster

text: of stars known as Melotte 15 contains a few bright stars nearly 50 times the mass of our Sun, and many more dim stars that are only a fraction of our Sun's mass.

text: The interior atmospheres of the solar system's gas giant planets are composed mainly of hydrogen and helium at temperatures well above their critical points. The gaseous outer atmospheres of Jupiter and Saturn transition smoothly into the dense liquid interior, while the nature of the transition zones of Neptune and Uranus is unknown. Theoretical models of extrasolar planets 55 Cancri e and Gliese 876 d have posited an ocean of pressurized, supercritical fluid water with a sheet of solid high pressure water ice at the bottom.

text: The interior atmospheres of the solar system's

text: gas giant

text: planets are composed mainly of hydrogen and helium at temperatures well above their critical points. The gaseous outer atmospheres of

text: Jupiter

text: and

text: Saturn

text: transition smoothly into the dense liquid interior, while the nature of the transition zones of

text: Neptune

text: and

text: Uranus

text: is unknown. Theoretical models of

text: extrasolar planet

text: s

text: 55 Cancri e

text: and

text: Gliese 876 d

text: have posited an ocean of pressurized, supercritical fluid water with a sheet of solid high pressure water ice at the bottom.

text: Maximum Power Point Tracking Using Bisection Search Method: In order to apply the BST into the MPPT technique in PV systems, the function of y= f(x) and the variable x should be chosen carefully. Fig. 2 shows a power-voltage (P -V) curve. From the (P -V) curve, it can be observed that the change in power with respect to voltage approaches zero at the maximum power point. Obviously, the powers at short circuit voltage (0 V) and open circuit voltage (Voc ) are zero, so maximum power should not happen in these two particular points even though the changes in power at these two points are also zero, which is caused by the small powers around these two points. Thus, tracking the maximum power point is essential to find the root in the function dP by regulating the voltage of solar module or solar array. As a result, the function y= f(x) can be regarded as the change in power dP, where the variable x is the voltage of solar module or solar array.

text: The Hunt GravityPlane (not to be confused with the ground-based gravity plane) is a proposed gravity-powered glider by Hunt Aviation in the USA.  It also has aerofoil wings, improving its lift-drag ratio and making it more efficient. The GravityPlane requires a large size in order to obtain a large enough volume-to-weight ratio to support this wing structure, and no example has yet been built. Unlike a powered glider, the GravityPlane does not consume power during the climbing phase of flight. It does however consume power at the points where it changes its buoyancy between positive and negative values. Hunt claim that this can nevertheless improve the energy efficiency of the craft, similar to the improved energy efficiency of underwater gliders over conventional methods of propulsion. Hunt suggest that the low power consumption should allow the craft to harvest sufficient energy to stay aloft indefinitely. The conventional approach to this requirement is the use of solar panels in a solar-powered aircraft. Hunt has proposed two alternative approaches. One is to use a wind turbine and harvest energy from the airflow generated by the gliding motion, the other is a thermal cycle to extract energy from the differences in air temperature at different altitudes.

text: The Hunt GravityPlane (not to be confused with the ground-based

text: gravity plane

text: ) is a proposed gravity-powered glider by Hunt Aviation in the USA.  It also has aerofoil wings, improving its lift-drag ratio and making it more efficient. The GravityPlane requires a large size in order to obtain a large enough volume-to-weight ratio to support this wing structure, and no example has yet been built. Unlike a

text: powered glider

text: , the GravityPlane does not consume power during the climbing phase of flight. It does however consume power at the points where it changes its buoyancy between positive and negative values. Hunt claim that this can nevertheless improve the energy efficiency of the craft, similar to the improved energy efficiency of

text: underwater glider

text: s over conventional methods of propulsion. Hunt suggest that the low power consumption should allow the craft to harvest sufficient energy to stay aloft indefinitely. The conventional approach to this requirement is the use of

text: solar panel

text: s in a

text: solar-powered aircraft

text: . Hunt has proposed two alternative approaches. One is to use a wind turbine and harvest energy from the airflow generated by the gliding motion, the other is a thermal cycle to extract energy from the differences in air temperature at different altitudes.

text: Historically, the apparent motions of the planets were described by European and Arabic philosophers using the idea of celestial spheres. This model posited the existence of perfect moving spheres or rings to which the stars and planets were attached. It assumed the heavens were fixed apart from the motion of the spheres, and was developed without any understanding of gravity.  After the planets' motions were more accurately measured, theoretical mechanisms such as deferent and epicycles were added. Although the model was capable of reasonably accurately predicting the planets' positions in the sky, more and more epicycles were required as the measurements became more accurate, hence the model became increasingly unwieldy. Originally geocentric  it was modified by Copernicus to place the sun at the centre to help simplify the model. The model was further challenged during the 16th century, as comets were observed traversing the spheres.

text: Historically, the apparent motions of the planets were described by European and Arabic philosophers using the idea of

text: celestial spheres

text: . This model posited the existence of perfect moving spheres or rings to which the stars and planets were attached. It assumed the heavens were fixed apart from the motion of the spheres, and was developed without any understanding of gravity.  After the planets' motions were more accurately measured, theoretical mechanisms such as

text: deferent and epicycle

text: s were added. Although the model was capable of reasonably accurately predicting the planets' positions in the sky, more and more epicycles were required as the measurements became more accurate, hence the model became increasingly unwieldy. Originally

text: geocentric

text: it was modified by

text: Copernicus

text: to place the sun at the centre to help simplify the model. The model was further challenged during the 16th century, as comets were observed traversing the spheres.

text: In planetary science, the survey telescope aims to discover and study remote Solar System bodies such as trans-Neptunian objects, as well as search for extrasolar planet transits. The Galactic plane will also be extensively studied with VST, which will look for signatures of tidal interactions in the Milky Way, and will provide astronomers with data crucial to understand the structure and evolution of our Galaxy. Further afield, the VST will explore nearby galaxies, extragalactic and intra-cluster planetary nebulae, and will perform surveys of faint object and micro-lensing events. The telescope will also peer into the distant Universe to help astronomers find answers to long-standing questions in cosmology. It will target medium-redshift supernovae to help pin down the cosmic distance scale and understand the expansion of the Universe. The VST will also look for cosmic structures at medium-high redshift, active galactic nuclei and quasars to further our understanding of galaxy formation and the Universe’s early history.

text: The Geocentric (Ptolemaic) model of the solar system is still of interest to planetarium makers, as, for technical reasons, a Ptolemaic-type motion for the planet light apparatus has some advantages over a Copernican-type motion. The celestial sphere, still used for teaching purposes and sometimes for navigation, is also based on a Geocentric system which in effect ignores parallax.  However this effect is negligible at the scale of accuracy that applies to a planetarium.

text: The Geocentric (Ptolemaic) model of the

text: solar system

text: is still of interest to

text: planetarium

text: makers, as, for technical reasons, a Ptolemaic-type motion for the planet light apparatus has some advantages over a Copernican-type motion. The

text: celestial sphere

text: , still used for teaching purposes and sometimes for navigation, is also based on a Geocentric system which in effect ignores parallax.  However this effect is negligible at the scale of accuracy that applies to a planetarium.

text: NGC 1514 is a planetary nebula that was discovered by William Herschel on November 13, 1790, describing it "A most singular phaenomenon" and forcing him to rethink his ideas on the construction of the heavens. Up until this point Herschel was convinced that all nebulae consisted of masses of stars too remote to resolve, but now here was a single star "surrounded with a faintly luminous atmosphere." He went on to conclude "Our judgement I may venture to say, will be, that the nebulosity about the star is not of a starry nature".

text: NGC 1514 is a

text: planetary nebula

text: that was discovered by

text: William Herschel

text: on November 13, 1790, describing it "A most singular phaenomenon" and forcing him to rethink his ideas on the construction of the heavens. Up until this point Herschel was convinced that all nebulae consisted of masses of stars too remote to resolve, but now here was a single star "surrounded with a faintly luminous atmosphere." He went on to conclude "Our judgement I may venture to say, will be, that the nebulosity about the star is not of a starry nature".

text: In sunny, warm locations, where freeze protection is not necessary, an ICS (batch type) solar water heater can be extremely cost effective. In higher latitudes, there are often additional design requirements for cold weather, which add to system complexity. This has the effect of increasing the initial cost (but not the life-cycle cost) of a solar water heating system, to a level much higher than a comparable water heater of the conventional type. The biggest single consideration is therefore the large initial financial outlay of solar water heating systems. Offsetting this expense can take several years and the payback period is longer in temperate environments where the insolation is less intense. When calculating the total cost to own and operate, a proper analysis will consider that solar energy is free, thus greatly reducing the operating costs, whereas other energy sources, such as gas and electricity, can be quite expensive over time. Thus, when the initial costs of a solar system are properly financed and compared with energy costs, then in many cases the total monthly cost of solar heat can be less than other more conventional types of water heaters (also in conjunction with an existing water heater). At higher latitudes, solar heaters may be less effective due to lower solar energy, possibly requiring larger and/or dual-heating systems. In addition, government incentives can be significant.

text: In an article in the January 2007 issue of Scientific American, Soter cited the definition's incorporation of current theories of the formation and evolution of the Solar System; that as the earliest protoplanets emerged from the swirling dust of the protoplanetary disc, some bodies "won" the initial competition for limited material and, as they grew, their increased gravity meant that they accumulated more material, and thus grew larger, eventually outstripping the other bodies in the Solar System by a very wide margin. The asteroid belt, disturbed by the gravitational tug of nearby Jupiter, and the Kuiper belt, too widely spaced for its constituent objects to collect together before the end of the initial formation period, both failed to win the accretion competition.

text: In an article in the January 2007 issue of

text: Scientific American

text: , Soter cited the definition's incorporation of current theories of the

text: ; that as the earliest

text: protoplanet

text: s emerged from the swirling dust of the

text: protoplanetary disc

text: , some bodies "won" the initial competition for limited material and, as they grew, their increased gravity meant that they accumulated more material, and thus grew larger, eventually outstripping the other bodies in the Solar System by a very wide margin. The asteroid belt, disturbed by the gravitational tug of nearby Jupiter, and the Kuiper belt, too widely spaced for its constituent objects to collect together before the end of the initial formation period, both failed to win the accretion competition.

text: In general, the effect is size dependent, and will affect the semi-major axis of smaller asteroids, while leaving large asteroids practically unaffected. For kilometre-sized asteroids, the Yarkovsky effect is minuscule over short periods: the force on asteroid 6489 Golevka has been estimated at about 0.25 newton, for a net acceleration of 10 m/s². But it is steady; over millions of years an asteroid's orbit can be perturbed enough to transport it from the asteroid belt to the inner Solar System.

text: In general, the effect is size dependent, and will affect the semi-major axis of smaller asteroids, while leaving large asteroids practically unaffected. For kilometre-sized asteroids, the Yarkovsky effect is minuscule over short periods: the force on asteroid

text: 6489 Golevka

text: has been estimated at about 0.25

text: newton

text: , for a net acceleration of 10 m/s². But it is steady; over millions of years an asteroid's orbit can be perturbed enough to transport it from the

text: asteroid belt

text: to the inner Solar System.

text: It has been argued that the historiography of science is "riddled with Whiggish history."  Like other Whig histories, Whig history of science tends to divide historical actors into "good guys", who are on the side of truth (as is now known) and "bad guys", who opposed the emergence of these truths because of ignorance or bias.  From this Whiggish perspective, Ptolemy would be criticized because his astronomical system placed the Earth at the center of the universe while Aristarchus would be praised because he placed the Sun at the center of the solar system.  This kind of evaluation ignores historical background and the evidence that was available at a particular time: did Aristarchus have evidence to support his idea that the Sun was at the center; were there good reasons to reject Ptolemy's system before the sixteenth century?

text: It has been argued that the

text: historiography of science

text: is "riddled with Whiggish history."  Like other Whig histories, Whig history of science tends to divide historical actors into "good guys", who are on the side of truth (as is now known) and "bad guys", who opposed the emergence of these truths because of ignorance or bias.  From this Whiggish perspective,

text: Ptolemy

text: would be criticized because his astronomical system placed the Earth at the center of the universe while

text: Aristarchus

text: would be praised because he placed the Sun at the center of the solar system.  This kind of evaluation ignores historical background and the evidence that was available at a particular time: did Aristarchus have evidence to support his idea that the Sun was at the center; were there good reasons to reject Ptolemy's system before the sixteenth century?

text: How It Ends then moves to external threats to the planet, beginning with the space rocks that are leftover from the formation of the moon and planets in the Solar System, and continuing with the eventual warming and demise of the Sun. Within the Milky Way galaxy, all the lights eventually go out as the lowest mass stars exhaust their nuclear fuel.  A trillion years from now, the Milky Way will be a dark agglomeration of stellar husks.

text: How It Ends then moves to external threats to the planet, beginning with the space rocks that are leftover from the formation of the

text: moon

text: and

text: planets

text: in the

text: Solar System

text: , and continuing with the eventual warming and demise of the

text: Sun

text: . Within the

text: Milky Way galaxy

text: , all the lights eventually go out as the lowest mass stars exhaust their nuclear fuel.  A trillion years from now, the Milky Way will be a dark agglomeration of stellar husks.

text: Barycentric osculating orbital elements for some objects in the Solar System:

text: The planets, however, do not move in perfect circles but in ellipses.  It was Johannes Kepler, about a century after Copernicus, who reluctantly (for he too had Platonic affinities) realized this.  Thanks to his examination of the meticulous observations compiled by astronomer Tycho Brahe, Kepler "was the first to understand the nature of the departures from uniform circular motion that had puzzled astronomers since the time of Plato."

text: The planets, however, do not move in perfect circles but in

text: ellipse

text: s.  It was

text: Johannes Kepler

text: , about a century after Copernicus, who reluctantly (for he too had Platonic affinities) realized this.  Thanks to his examination of the meticulous observations compiled by astronomer

text: Tycho Brahe

text: , Kepler "was the first to understand the nature of the departures from uniform circular motion that had puzzled astronomers since the time of Plato."

text: Solar access is differentiated from solar rights or solar easement, which is specifically meant for direct sunlight for solar energy systems, whereas solar access is a right to sunlight upon certain building façades regardless of the presence of active or passive solar energy systems.

text: Solar access is differentiated from solar rights or

text: solar easement

text: , which is specifically meant for direct sunlight for solar energy systems, whereas solar access is a right to sunlight upon certain building

text: façades

text: regardless of the presence of active or passive solar energy systems.

text: On the one hand, “causality” is a notion implying the most general idea of “actual scientific knowledge” which guides and stimulates each investigation. In this sense, Kepler already embarked in his MC on a causal investigation by asking for the cause of the number, the sizes and the “motions” (= the speeds) of the heavenly spheres. On the other hand, “causality” implies in Kepler, according to the Aristotelian conception of physical science, the concrete “physical cause”, the efficient cause which produces a motion or is responsible for keeping the body in motion. Original to Kepler, however, and typical of his approach is the resoluteness with which he was convinced that the problem of equipollence of the astronomical hypotheses can be resolved and the consequent introduction of the concept of causality into astronomy – traditionally a mathematical science. This approach is already present in his MC, where he, for instance, relates for the first time the distances of the planets to a power which emerges from the Sun and decreases in proportion to the distance of each planet, up to the sphere of the fixed stars (see Stephenson 1987, pp. 9–10).

text: Out of the 500 possibilities, the band eventually narrowed the list of potential album cuts down to fifteen songs, and then finally decided on the best ten. These included "Ashes," which started life in 2001 as a piano-driven ballad and eventually took the form of a four-minute long anthem of a pop song, "Someday," whose verse was written in 1997 and waited seven years for the rest of the song to show up, and "Everytime I See Your Face," a song that would never see the light of public release. This was due to the addition of "Gravity," a Coldplay-penned composition that Chris Martin (good friend of Danny McNamara) gifted to Embrace after Martin decided that the song sounded a bit more like Embrace than it did Coldplay. "Everytime I See Your Face" was dropped from the album, and "Gravity" not only found itself on Out of Nothing but also in the role of comeback single, being Independiente's preferred choice over "Ashes," which had been the album's intended first single before the introduction of "Gravity." Danny McNamara referred to this decision as the "sexy angle."

text: Out of the 500 possibilities, the band eventually narrowed the list of potential album cuts down to fifteen songs, and then finally decided on the best ten. These included "

text: Ashes

text: ," which started life in 2001 as a piano-driven ballad and eventually took the form of a four-minute long anthem of a pop song, "Someday," whose verse was written in 1997 and waited seven years for the rest of the song to show up, and "Everytime I See Your Face," a song that would never see the light of public release. This was due to the addition of "

text: Gravity

text: ," a

text: Coldplay

text: -penned composition that

text: Chris Martin

text: (good friend of

text: Danny McNamara

text: ) gifted to

text: Embrace

text: after Martin decided that the song sounded a bit more like

text: Embrace

text: than it did

text: Coldplay

text: . "Everytime I See Your Face" was dropped from the album, and "

text: Gravity

text: " not only found itself on Out of Nothing but also in the role of comeback single, being

text: Independiente

text: 's preferred choice over "

text: Ashes

text: ," which had been the album's intended first single before the introduction of "

text: Gravity

text: Danny McNamara

text: referred to this decision as the "sexy angle."

text: The nebular hypothesis is the most widely accepted model in the field of cosmogony to explain the formation and evolution of the Solar System. It suggests that the Solar System formed from nebulous material. The theory was developed by Immanuel Kant and published in his Allgemeine Naturgeschichte und Theorie des Himmels ("Universal Natural History and Theory of the Heavens"), published in 1755. Originally applied to the Solar System, this process of planetary system formation is now thought to be at work throughout the Universe. The widely accepted modern variant of the nebular hypothesis is the solar nebular disk model (SNDM) or simply solar nebular model. This nebular hypothesis offered explanations for a variety of properties of the Solar System, including the nearly circular and coplanar orbits of the planets, and their motion in the same direction as the Sun's rotation. Some elements of the nebular hypothesis are echoed in modern theories of planetary formation, but most elements have been superseded.

text: The nebular hypothesis is the most widely accepted model in the field of

text: cosmogony

text: to explain the

text: . It suggests that the Solar System formed from nebulous material. The theory was developed by

text: Immanuel Kant

text: and published in his

entity_name: Universal Natural History and Theory of Heaven

text: Allgemeine Naturgeschichte und Theorie des Himmels

text: ("Universal Natural History and Theory of the Heavens"), published in 1755. Originally applied to the

text: Solar System

text: , this process of planetary system formation is now thought to be at work throughout the

text: Universe

text: . The widely accepted modern variant of the nebular hypothesis is the solar nebular disk model (SNDM) or simply solar nebular model. This nebular hypothesis offered explanations for a variety of properties of the Solar System, including the nearly circular and coplanar orbits of the planets, and their motion in the same direction as the Sun's rotation. Some elements of the nebular hypothesis are echoed in modern theories of planetary formation, but most elements have been superseded.

text: Stages in circumstellar discs refer to the structure and the main composition of the disc at different times during its evolution. Stages include the phases when the disc is composed mainly of submicron-sized particles, the evolution of these particles into grains and larger objects, the agglomeration of larger objects into planetesimals, and the growth and orbital evolution of planetesimals into the planetary systems, like our Solar System or many other stars.

text: Stages in circumstellar discs refer to the structure and the main composition of the disc at different times during its evolution. Stages include the phases when the disc is composed mainly of submicron-sized particles, the evolution of these particles into grains and larger objects, the agglomeration of larger objects into

text: planetesimal

text: s, and the growth and orbital evolution of planetesimals into the planetary systems, like our

text: Solar System

text: or many other stars.

text: There are several other prominent variable stars in Cepheus. One, μ Cephei, is also known as Herschel's Garnet Star due to its deep red colour. It is a semiregular variable star with a minimum magnitude of 5.1 and a maximum magnitude of 3.4. Its period is approximately 2 years. The star is around 11.8 AU in radius. If it were placed at the center of the Solar System, it would extend to the orbit of Saturn. Another, VV Cephei A, like Mu Cephei, is a red supergiant and a semiregular variable star, located at least 5,000 light-years from Earth. It has a minimum magnitude of 5.4 and a maximum magnitude of 4.8. One of the largest stars in the galaxy, it has a diameter of 1,300 solar diameters. VV Cephei is also an unusually long-period eclipsing binary, but the eclipses, which occur every 20.3 years, are too faint to be observed with the unaided eye. T Cephei, also a red giant, is a Mira variable with a minimum magnitude of 11.3 and a maximum magnitude of 5.2, 685 light-years from Earth. It has a period of 13 months and a diameter of 500 solar diameters.

text: There are several other prominent variable stars in Cepheus. One,

text: μ Cephei

text: , is also known as Herschel's Garnet Star due to its deep red colour. It is a

text: semiregular variable star

text: with a minimum magnitude of 5.1 and a maximum magnitude of 3.4. Its period is approximately 2 years. The star is around 11.8

text: AU

text: in radius. If it were placed at the center of the

text: Solar System

text: , it would extend to the orbit of

text: Saturn

text: . Another,

text: VV Cephei

text: A, like Mu Cephei, is a

text: red supergiant

text: and a semiregular variable star, located at least 5,000 light-years from Earth. It has a minimum magnitude of 5.4 and a maximum magnitude of 4.8. One of the largest stars in the galaxy, it has a diameter of 1,300 solar diameters. VV Cephei is also an unusually long-period

text: eclipsing binary

text: , but the eclipses, which occur every 20.3 years, are too faint to be observed with the unaided eye.

text: T Cephei

text: , also a red giant, is a

text: Mira variable

text: with a minimum magnitude of 11.3 and a maximum magnitude of 5.2, 685 light-years from Earth. It has a period of 13 months and a diameter of 500 solar diameters.

text: The speed of gravitational waves (v) is predicted by general relativity to be the speed of light (c). The extent of any deviation from this relationship can be parameterized in terms of the mass of the hypothetical graviton. The graviton is the name given to an elementary particle that would act as the force carrier for gravity, in quantum theories about gravity. It is expected to be massless if, as it appears, gravitation has an infinite range. (This is because the more massive a gauge boson is, the shorter is the range of the associated force; as with the infinite range of electromagnetism, which is due to the massless photon, the infinite range of gravity implies that any associated force-carrying particle would also be massless.) If the graviton were not massless, gravitational waves would propagate below lightspeed, with lower frequencies (ƒ) being slower than higher frequencies, leading to dispersion of the waves from the merger event. No such dispersion was observed. The observations of the inspiral slightly improve (lower) the upper limit on the mass of the graviton from Solar System observations to , corresponding to  or a Compton wavelength (λ) of greater than  km, roughly 1 light-year. Using the lowest observed frequency of 35 Hz, this translates to a lower limit on v such that the upper limit on 1-v /c is ~ .

text: The speed of gravitational waves (v) is predicted by general relativity to be the speed of light (c). The extent of any deviation from this relationship can be parameterized in terms of the mass of the hypothetical

text: graviton

text: . The graviton is the name given to an

text: elementary particle

text: that would act as the

text: force carrier

text: for gravity, in

text: quantum theories about gravity

text: . It is expected to be massless if, as it appears, gravitation has an infinite range. (This is because the more massive a

text: gauge boson

text: is, the shorter is the range of the associated force; as with the infinite range of

text: electromagnetism

text: , which is due to the massless

text: photon

text: , the infinite range of gravity implies that any associated force-carrying particle would also be massless.) If the graviton were not massless, gravitational waves would propagate below lightspeed, with lower frequencies (ƒ) being slower than higher frequencies, leading to dispersion of the waves from the merger event. No such dispersion was observed. The observations of the inspiral slightly improve (lower) the upper limit on the mass of the graviton from Solar System observations to , corresponding to  or a

text: Compton wavelength

text: (λ) of greater than  km, roughly 1 light-year. Using the lowest observed frequency of 35 Hz, this translates to a lower limit on v such that the upper limit on 1-v /c is ~ .

text: Currently, the direct detection of extrasolar planets (or exoplanets) is extremely difficult. This is primarily due to:

text: Currently, the direct detection of

text: extrasolar planets

text: (or exoplanets) is extremely difficult. This is primarily due to:

text: Over the decades numerous critics and skeptics have investigated Adamski's claims. The aliens Adamski claimed to have met in the 1950s were described by him as "human beings from another world", usually light-skinned, light-haired humanoids that would later be called Nordic aliens. Adamski claimed in his books that these "alien humans" came from Venus, Mars, and other planets in Earth's solar system. However, none of the planets he mentioned are capable of supporting human life, due to their environmental conditions. For example, the first alien Adamski claimed to have met was from Venus, yet the atmospheric pressure on the planet's surface is 92 times that of Earth, it has clouds which rain a toxic substance thought to be sulfuric acid, the atmosphere consists almost entirely of carbon dioxide, with very little oxygen, and the average surface temperature of Venus is 464 °C. In one of his books, Adamski described a trip he took to the far side of the Moon in a UFO, where he claimed to see cities, trees, and snow-capped mountains; he also claimed that the photographs of the Moon's far side that were taken by the Soviet lunar probe Luna 3 in 1959 were altered to depict a barren, lifeless surface instead of what he saw. However, all scientific evidence, and later lunar trips by American astronauts, clearly showed that the far side of the Moon is barren of life and has no atmosphere. Some of Adamski's supporters have put forward the theory that the space people whom Adamski claimed contacted him may have had bases on Venus, Mars, Saturn, etc., and Adamski misunderstood and mistook them for actually living on those planets. However, in his writings Adamski described traveling personally to Venus, Mars, and other planets in Earth's solar system, and he clearly stated that they were all capable of supporting humanoid life. As UFO historian Jerome Clark noted, "some Adamski partisans insisted that Venus, Mars, Saturn, and the rest were merely code words for planets in other solar systems; there is, however, nothing in Adamski's public writings to support this interpretation and considerable testimony to the contrary."

text: Over the decades numerous critics and skeptics have investigated Adamski's claims. The aliens Adamski claimed to have met in the 1950s were described by him as "human beings from another world", usually light-skinned, light-haired humanoids that would later be called

text: Nordic aliens

text: . Adamski claimed in his books that these "alien humans" came from Venus, Mars, and other planets in Earth's solar system. However, none of the planets he mentioned are capable of supporting human life, due to their environmental conditions. For example, the first alien Adamski claimed to have met was from Venus, yet the atmospheric pressure on the planet's surface is 92 times that of Earth, it has clouds which rain a toxic substance thought to be

text: sulfuric acid

text: , the atmosphere consists almost entirely of

text: carbon dioxide

text: , with very little

text: oxygen

text: , and the average surface temperature of Venus is 464 °C. In one of his books, Adamski described a trip he took to the

text: far side of the Moon

text: in a UFO, where he claimed to see cities, trees, and snow-capped mountains; he also claimed that the photographs of the Moon's far side that were taken by the Soviet lunar probe

text: Luna 3

text: in 1959 were altered to depict a barren, lifeless surface instead of what he saw. However, all scientific evidence, and later lunar trips by American astronauts, clearly showed that the far side of the Moon is barren of life and has no atmosphere. Some of Adamski's supporters have put forward the theory that the space people whom Adamski claimed contacted him may have had bases on Venus, Mars, Saturn, etc., and Adamski misunderstood and mistook them for actually living on those planets. However, in his writings Adamski described traveling personally to Venus, Mars, and other planets in Earth's solar system, and he clearly stated that they were all capable of supporting humanoid life. As UFO historian

text: Jerome Clark

text: noted, "some Adamski partisans insisted that Venus, Mars, Saturn, and the rest were merely code words for planets in other solar systems; there is, however, nothing in Adamski's public writings to support this interpretation and considerable testimony to the contrary."

text: Torque multipliers typically employ an epicyclic gear train having one or more stages. Each stage ofgearing multiplies the torque applied.  In epicyclic gear systems, torque is applied to the input gear or ‘sun’ gear. A number of planet gears are arranged around and engaged with this sun gear, and therefore rotate. The outside casing of the multiplier is also engaged with the planet gear teeth, but is prevented from rotating by means of a reaction arm, causing the planet gears to orbit around the sun gear. The planet gears are held in a ‘planet carrier' which also holds the output drive shaft. As the planet gears orbit around the sun gear, the carrier and the output shaft rotate together. Without the reaction arm to prevent rotation of the outer casing, the output shaft cannot apply torque.

text: Torque multipliers typically employ an

text: epicyclic

text: gear train having one or more stages. Each stage ofgearing multiplies the torque applied.  In

text: epicyclic gear systems

text: , torque is applied to the input gear or ‘sun’ gear. A number of planet gears are arranged around and engaged with this sun gear, and therefore rotate. The outside casing of the multiplier is also engaged with the planet gear teeth, but is prevented from rotating by means of a reaction arm, causing the planet gears to orbit around the sun gear. The planet gears are held in a ‘planet carrier' which also holds the output drive shaft. As the planet gears orbit around the sun gear, the carrier and the output shaft rotate together. Without the reaction arm to prevent rotation of the outer casing, the output shaft cannot apply torque.

text: Both the spaceship and the explorer vessel feature cockpits containing icons through which orders are given to various crew members such as the navigator and biotech officer.  Players command both craft in real-time from a first-person perspective by selecting an icon representing the commander's control pad, which translates movement of the mouse into corresponding motions of the spaceship or explorer vessel.  During combat the mouse buttons are used to control the selection and firing of the ship's weapons.  Some encounters with other spaceships result in peaceful conversations which yield important clues or provide opportunities for the player to befriend one of the region's native alien races.  The player's spaceship is capable of hopping between solar systems via hyperpath tunnels, making regional journeys within a solar system, and making short-range maneuvers in circumstances such as spaceship combat.  It may enter orbit around any planet in a solar system and perform a scan to gain information on that planet's general characteristics and topography.  Using the topographic map generated by a scan, the player can choose a landing site.  After doing so, the spaceship's crew transfers to the explorer vessel which undocks from the orbiting spaceship and lands on the planet.  The player drives the explorer vessel around on the planet's surface to collect saleable minerals and lifeforms and, on inhabited worlds, to locate alien trading posts at which the player may barter with the alien race to whom the planet belongs.

text: Both the spaceship and the explorer vessel feature

text: cockpit

text: s containing

text: icon

text: s through which orders are given to various crew members such as the navigator and biotech officer.  Players command both craft in real-time from a first-person perspective by selecting an icon representing the commander's control pad, which translates movement of the

text: mouse

text: into corresponding motions of the spaceship or explorer vessel.  During combat the mouse buttons are used to control the selection and firing of the ship's weapons.  Some encounters with other spaceships result in peaceful conversations which yield important clues or provide opportunities for the player to befriend one of the region's native alien races.  The player's spaceship is capable of hopping between solar systems via

text: hyperpath tunnels

text: , making regional journeys within a solar system, and making short-range maneuvers in circumstances such as spaceship combat.  It may enter orbit around any planet in a solar system and perform a scan to gain information on that planet's general characteristics and

text: topography

text: .  Using the

text: topographic map

text: generated by a scan, the player can choose a landing site.  After doing so, the spaceship's crew transfers to the explorer vessel which undocks from the orbiting spaceship and lands on the planet.  The player drives the explorer vessel around on the planet's surface to collect saleable minerals and lifeforms and, on inhabited worlds, to locate alien trading posts at which the player may barter with the alien race to whom the planet belongs.

text: Gerard Kuiper (in 1944) argued, like Ter Haar, that regular eddies would be impossible and postulated that large gravitational instabilities might occur in the solar nebula, forming condensations. In this, the solar nebula could be either co-genetic with the Sun or captured by it. Density distribution would determine what could form: either a planetary system or a stellar companion. The 2 types of planets were assumed to be due to the Roche limit. No explanation was offered for the Sun's slow rotation which Kuiper saw as a larger G-star problem.

text: Gerard Kuiper

text: (in 1944) argued, like Ter Haar, that regular eddies would be impossible and postulated that large gravitational instabilities might occur in the solar nebula, forming condensations. In this, the solar nebula could be either co-genetic with the Sun or captured by it. Density distribution would determine what could form: either a planetary system or a stellar companion. The 2 types of planets were assumed to be due to the Roche limit. No explanation was offered for the Sun's slow rotation which Kuiper saw as a larger G-star problem.

text: Several places on Earth have been given the nickname "Center (or Centre) of the Universe." In addition, several fictional works have described a depicted location as being at the center of the universe.

text: The weight of a solid core reactor was initially thought to be its main drawback. Immediately after World War II, a complete nuclear reactor was so heavy that it was feared that solid core nuclear thermal engines would be hard-pressed  to achieve a thrust-to-weight ratio of 1:1, which is needed to overcome the gravity of the Earth at launch.  This problem was quickly overcome, however, and over the next twenty-five years U.S. nuclear thermal rocket designs eventually reached thrust-to-weight ratios of approximately 7:1.  This is still a much lower thrust-to-weight ratio than what is achievable with chemical rockets, which have thrust-to-weight ratios on the order of 70:1. That fact, when combined with the large tanks necessary for liquid hydrogen (or other working fluid) storage, means that solid core nuclear thermal engines are best suited for a) use in upper stages, where vehicle velocity is already near orbital, or b) in space "tugs", or intra Solar System transports, which would be used to take payloads and/or people between gravity wells, or c) for launches from a planet smaller than Earth, a planetoid (or "dwarf planet"), an asteroid, or a moon where the required thrust is lower due to lower gravity fields. Currently then, for a solid core nuclear thermal rocket to be more useful than chemical rockets as a first or second stage Earth launch engine, the system would either have to be made much lighter, or provide even higher specific impulse. Until that day, it can be said that the true strength of nuclear rockets currently lies in solar system exploration, outside Earth's gravity well.

text: The weight of a solid core reactor was initially thought to be its main drawback. Immediately after World War II, a complete nuclear reactor was so heavy that it was feared that solid core nuclear thermal engines would be hard-pressed  to achieve a

text: thrust-to-weight ratio

text: of 1:1, which is needed to overcome the

text: gravity

text: of the Earth at launch.  This problem was quickly overcome, however, and over the next twenty-five years U.S. nuclear thermal rocket designs eventually reached thrust-to-weight ratios of approximately 7:1.  This is still a much lower thrust-to-weight ratio than what is achievable with chemical rockets, which have thrust-to-weight ratios on the order of 70:1. That fact, when combined with the large tanks necessary for liquid hydrogen (or other working fluid) storage, means that solid core nuclear thermal engines are best suited for a) use in upper stages, where vehicle velocity is already near orbital, or b) in space "tugs", or intra Solar System transports, which would be used to take payloads and/or people between

text: gravity well

text: s, or c) for launches from a planet smaller than Earth, a planetoid (or "dwarf planet"), an asteroid, or a moon where the required thrust is lower due to lower gravity fields. Currently then, for a solid core nuclear thermal rocket to be more useful than chemical rockets as a first or second stage Earth launch engine, the system would either have to be made much lighter, or provide even higher specific impulse. Until that day, it can be said that the true strength of nuclear rockets currently lies in solar system exploration, outside Earth's gravity well.

text: When the core helium is exhausted, a star with up to about  has a carbon–oxygen core that becomes degenerate and starts helium burning in a shell. As with the earlier collapse of the helium core, this starts convection in the outer layers, triggers a second dredge-up, and causes a dramatic increase in size and luminosity. This is the asymptotic giant branch (AGB) analogous to the red-giant branch but more luminous, with a hydrogen-burning shell contributing most of the energy. Stars only remain on the AGB for around a million years, becoming increasingly unstable until they exhaust their fuel, go through a planetary nebula phase, and then become a carbon–oxygen white dwarf.

text: When the core helium is exhausted, a star with up to about  has a carbon–oxygen core that becomes degenerate and starts helium burning in a shell. As with the earlier collapse of the helium core, this starts convection in the outer layers, triggers a second dredge-up, and causes a dramatic increase in size and luminosity. This is the

text: asymptotic giant branch

text: (AGB) analogous to the red-giant branch but more luminous, with a hydrogen-burning shell contributing most of the energy. Stars only remain on the AGB for around a million years, becoming increasingly unstable until they exhaust their fuel, go through a planetary nebula phase, and then become a carbon–oxygen white dwarf.

text: Due to the magnitude of Jupiter's mass, the center of gravity between it and the Sun lies just above the Sun's surface. Jupiter is the only body in the Solar System for which this is true.

text: The earliest material found in the Solar System is dated to  (billion years ago); therefore, the Earth itself must have been formed by accretion around this time. By , the primordial Earth had formed. The formation and evolution of the Solar System bodies occurred in tandem with the Sun. In theory, a solar nebula partitions a volume out of a molecular cloud by gravitational collapse, which begins to spin and flatten into a circumstellar disk, which the planets then grow out of in tandem with the star. A nebula contains gas, ice grains and dust (including primordial nuclides). In nebular theory, planetesimals commence forming as particulate matter accrues by cohesive clumping and then by gravity. The assembly of the primordial Earth proceeded for 10–.

text: The earliest material found in the Solar System is dated to  (billion years ago); therefore, the Earth itself must have been formed by

text: accretion

text: around this time. By , the primordial Earth had formed. The

text: bodies occurred in tandem with the Sun. In theory, a

text: solar nebula

text: partitions a volume out of a

text: molecular cloud

text: circumstellar disk

text: , which the planets then grow out of in tandem with the star. A nebula contains gas, ice grains and

text: dust

text: (including

text: primordial nuclides

text: ). In

text: nebular theory

text: planetesimal

text: s commence forming as

text: particulate

text: matter accrues by

text: cohesive clumping

text: and then by gravity. The assembly of the primordial Earth proceeded for 10–.

text: Panguite is in a class of refractory minerals that formed under the high temperatures and extremely varied pressures present in the early solar system, up to 4.5 billion years ago. This makes panguite one of the oldest minerals in the Solar System. Zirconium is a key element in determining conditions prior to and during the Solar System’s formation.

text: Panguite is in a class of

text: refractory

text: minerals that formed under the high temperatures and extremely varied pressures present in the early

text: solar system

text: , up to 4.5 billion years ago. This makes panguite one of the oldest minerals in the Solar System. Zirconium is a key element in determining conditions prior to and during the Solar System’s formation.

text: The Shape Dynamics Formulation of gravity possesses a physical Hamiltonian that generates evolution of spatial conformal geometry. This disentangles the problem of time in quantum gravity: The gauge problem (the choice of foliation in the spacetime description) is replaced by the problem of finding spatial conformal geometries, leaving an evolution that is comparable to a system with time dependent Hamiltonian. The problem of time is suggested to be completely solved by restricting oneself to "objective observables," which are those observables that do not depend on any external clock or rod.

text: The Shape Dynamics Formulation of gravity possesses a physical Hamiltonian that generates evolution of spatial conformal geometry. This disentangles the

text: problem of time

text: in quantum gravity: The gauge problem (the choice of foliation in the spacetime description) is replaced by the problem of finding spatial conformal geometries, leaving an evolution that is comparable to a system with time dependent Hamiltonian. The problem of time is suggested to be completely solved by restricting oneself to "objective observables," which are those observables that do not depend on any external clock or rod.

text: In the Solar System, a planet is said to be inferior with respect to another planet if its orbit lies inside the other planet's orbit around the Sun. In this situation, the latter planet is said to be superior to the former. In the reference frame of the Earth, in which the terms were originally used, the inferior planets are Mercury and Venus, while the superior planets are Mars, Jupiter, Saturn, Uranus and Neptune. Dwarf planets like Ceres or Pluto and most asteroids are 'superior' in the sense that they almost all orbit outside the orbit of Earth.

text: In the

text: Solar System

text: , a

text: planet

text: is said to be inferior with respect to another planet if its

text: orbit

text: lies inside the other planet's orbit around the

text: Sun

text: . In this situation, the latter planet is said to be superior to the former. In the reference frame of the

text: Earth

text: , in which the terms were originally used, the inferior planets are

text: Mercury

text: and

text: Venus

text: , while the superior planets are

text: Mars

text: Jupiter

text: Saturn

text: Uranus

text: and

text: Neptune

text: Dwarf planet

text: s like

text: Ceres

text: or

text: Pluto

text: and most

text: asteroids

text: are 'superior' in the sense that they almost all orbit outside the orbit of Earth.

text: By the end of the 19th century the word planet, though it had yet to be defined, had become a working term applied only to a small set of objects in the Solar System. After 1992, however, astronomers began to discover many additional objects beyond the orbit of Neptune, as well as hundreds of objects orbiting other stars. These discoveries not only increased the number of potential planets, but also expanded their variety and peculiarity. Some were nearly large enough to be stars, while others were smaller than Earth's moon. These discoveries challenged long-perceived notions of what a planet could be.

text: By the end of the 19th century the word

text: planet

text: , though it had yet to be defined, had become a working term applied only to a small set of objects in the

text: Solar System

text: . After 1992, however, astronomers began to discover many additional objects beyond the orbit of

text: Neptune

text: , as well as hundreds of

text: objects orbiting other stars

text: . These discoveries not only increased the number of potential planets, but also expanded their variety and peculiarity. Some were nearly large enough to be

text: star

text: s, while others were smaller than Earth's moon. These discoveries challenged long-perceived notions of what a planet could be.

text: All the planets in the Solar System orbit the Sun in an anti-clockwise direction as viewed from above Earth's north pole. Most planets also rotate on their axes in an anti-clockwise direction, but Venus rotates clockwise in retrograde rotation once every 243 Earth days—the slowest rotation of any planet. Because its rotation is so slow, Venus is very close to spherical. A Venusian sidereal day thus lasts longer than a Venusian year (243 versus 224.7 Earth days). Venus's equator rotates at , whereas Earth's is approximately . Venus's rotation has slowed down by  per Venusian sidereal day in the  between the Magellan spacecraft and Venus Express visits. Because of the retrograde rotation, the length of a solar day on Venus is significantly shorter than the sidereal day, at 116.75 Earth days (making the Venusian solar day shorter than Mercury's 176 Earth days). One Venusian year is about 1.92 Venusian solar days. To an observer on the surface of Venus, the Sun would rise in the west and set in the east, although Venus's opaque clouds prevent observing the Sun from the planet's surface.

text: All the planets in the Solar System orbit the Sun in an anti-clockwise direction as viewed from above Earth's north pole. Most planets also rotate on their axes in an anti-clockwise direction, but Venus rotates clockwise in

text: retrograde rotation

text: once every 243 Earth days—the slowest rotation of any planet. Because its rotation is so slow, Venus is very close to spherical. A Venusian

text: sidereal day

text: thus lasts longer than a Venusian year (243 versus 224.7 Earth days). Venus's equator rotates at , whereas Earth's is approximately . Venus's rotation has slowed down by  per Venusian sidereal day in the  between the Magellan spacecraft and Venus Express visits. Because of the retrograde rotation, the length of a

text: solar day

text: on Venus is significantly shorter than the sidereal day, at 116.75 Earth days (making the Venusian solar day shorter than

text: Mercury

text: 's 176 Earth days). One Venusian year is about 1.92 Venusian solar days. To an observer on the surface of Venus, the Sun would rise in the west and set in the east, although Venus's opaque clouds prevent observing the Sun from the planet's surface.

text: The discovery of extrasolar planets led to another ambiguity in defining a planet: the point at which a planet becomes a star. Many known extrasolar planets are many times the mass of Jupiter, approaching that of stellar objects known as brown dwarfs. Brown dwarfs are generally considered stars due to their ability to fuse deuterium, a heavier isotope of hydrogen. Although objects more massive than 75 times that of Jupiter fuse hydrogen, objects of only 13 Jupiter masses can fuse deuterium. Deuterium is quite rare, and most brown dwarfs would have ceased fusing deuterium long before their discovery, making them effectively indistinguishable from supermassive planets.

text: The discovery of extrasolar planets led to another ambiguity in defining a planet: the point at which a planet becomes a star. Many known extrasolar planets are many times the mass of Jupiter, approaching that of stellar objects known as

text: brown dwarf

text: s. Brown dwarfs are generally considered stars due to their ability to fuse

text: deuterium

text: , a heavier isotope of

text: hydrogen

text: . Although objects more massive than 75 times that of Jupiter fuse hydrogen, objects of only 13 Jupiter masses can fuse deuterium. Deuterium is quite rare, and most brown dwarfs would have ceased fusing deuterium long before their discovery, making them effectively indistinguishable from supermassive planets.

text: Heliocentrism is the scientific model that first placed the Sun at the center of the Solar System and put the planets, including Earth, in its orbit. Historically, heliocentrism is opposed to geocentrism, which placed the Earth at the center. Aristarchus of Samos already proposed a heliocentric model in the 3rd century BC. In the 16th century, Nicolaus Copernicus' De revolutionibus presented a full discussion of a heliocentric model of the universe in much the same way as Ptolemy had presented his geocentric model in the 2nd century. This "Copernican revolution" resolved the issue of planetary retrograde motion by arguing that such motion was only perceived and apparent. "Although Copernicus's groundbreaking book...had been [printed] over a century earlier, [the Dutch mapmaker] Joan Blaeu was the first mapmaker to incorporate his revolutionary heliocentric theory into a map of the world."

text: Heliocentrism

text: is the scientific model that first placed the Sun at the center of the

text: Solar System

text: and put the planets, including Earth, in its orbit. Historically, heliocentrism is opposed to

text: geocentrism

text: , which placed the Earth at the center.

text: Aristarchus of Samos

text: already proposed a heliocentric model in the 3rd century BC. In the 16th century,

text: Nicolaus Copernicus

text: De revolutionibus

text: presented a full discussion of a

text: heliocentric model

text: of the universe in much the same way as

text: Ptolemy

text: had presented his geocentric model in the 2nd century. This "

text: Copernican revolution

text: " resolved the issue of planetary

text: retrograde motion

text: by arguing that such motion was only perceived and apparent. "Although Copernicus's groundbreaking book...had been [printed] over a century earlier, [the Dutch mapmaker]

text: Joan Blaeu

text: was the first mapmaker to incorporate his revolutionary heliocentric theory into a map of the world."

text: The birth of the modern widely accepted theory of planetary formation—the solar nebular disk model (SNDM)—can be traced to the Soviet astronomer Victor Safronov. His 1969 book Evolution of the protoplanetary cloud and formation of the Earth and the planets, which was translated to English in 1972, had a long-lasting effect on the way scientists think about the formation of the planets. In this book almost all major problems of the planetary formation process were formulated and some of them solved. Safronov's ideas were further developed in the works of George Wetherill, who discovered runaway accretion. While originally applied only to the Solar System, the SNDM was subsequently thought by theorists to be at work throughout the Universe; as of  astronomers have discovered  extrasolar planets in our galaxy.

text: The birth of the modern widely accepted theory of planetary formation—the solar nebular disk model (SNDM)—can be traced to the Soviet astronomer

text: Victor Safronov

text: . His 1969 book Evolution of the protoplanetary cloud and formation of the Earth and the planets, which was translated to English in 1972, had a long-lasting effect on the way scientists think about the formation of the planets. In this book almost all major problems of the planetary formation process were formulated and some of them solved. Safronov's ideas were further developed in the works of

text: George Wetherill

text: , who discovered

text: runaway accretion

text: . While originally applied only to the

text: Solar System

text: , the SNDM was subsequently thought by theorists to be at work throughout the Universe; as of  astronomers have discovered

text: extrasolar planet

text: s in our

text: galaxy

text: In their future, Earth had colonized several planets in its solar system, including Pluto. Martinex was born on Cerberus Center, Pluto, although it was later revealed his ancestors were from the continent of Africa on Earth.

text: In their future,

text: Earth

text: had colonized several planets in its

text: solar system

text: , including

text: Pluto

text: . Martinex was born on Cerberus Center, Pluto, although it was later revealed his ancestors were from the continent of

text: Africa

text: on Earth.

text: The optical absorption for all diamondoids lies deep in the UV spectral region with optical band gaps around 6 eV and higher. The spectrum of each diamondoid is found to reflect its individual size, shape and symmetry. Due to their well defined size and structure diamondoids also serve as a model system for electronic structure calculations.Many of the optoelectronic properties of diamondoids are determined by thedifference in the nature of the highest occupied and lowest unoccupiedmolecular orbitals: the former is a bulk state, whereas the latter is asurface state.  As a result, the energy of the lowest unoccupied molecularorbital is roughly independent of the size of the diamondoid.

text: Gravity is the weakest of the four fundamental interactions of nature. The gravitational attraction is approximately 10 times weaker than the strong force, 10 times weaker than the electromagnetic force and 10 times weaker than the weak force. As a consequence, gravity has a negligible influence on the behavior of subatomic particles, and plays no role in determining the internal properties of everyday matter (but see quantum gravity). On the other hand, gravity is the dominant interaction at the macroscopic scale, and is the cause of the formation, shape and trajectory (orbit) of astronomical bodies. It is responsible for various phenomena observed on Earth and throughout the Universe; for example, it causes the Earth and the other planets to orbit the Sun, the Moon to orbit the Earth, the formation of tides, the formation and evolution of the Solar System, stars and galaxies.

text: Gravity is the weakest of the four

text: fundamental interaction

text: s of nature. The gravitational attraction is approximately 10 times weaker than the

text: strong force

text: , 10 times weaker than the

text: electromagnetic force

text: and 10 times weaker than the

text: weak force

text: . As a consequence, gravity has a negligible influence on the behavior of subatomic particles, and plays no role in determining the internal properties of everyday matter (but see

text: quantum gravity

text: ). On the other hand, gravity is the dominant interaction at the

text: macroscopic scale

text: , and is the cause of the formation, shape and

text: trajectory

text: orbit

text: ) of astronomical bodies. It is responsible for various phenomena observed on Earth and throughout the Universe; for example, it causes the Earth and the other planets to orbit the Sun, the

text: Moon

text: to orbit the Earth, the formation of

text: tide

text: s, the

text: stars

text: and

text: galaxies

text: Observations over the decades have shown that its colour slightly changes and it exhibits variation in light that indicate the star is actually an ellipsoidal binary with a period of seven days. The system is more luminous than expected, given the spectrum and distance of the primary star, indicating that the companion star must be contributing a good proportion of its light. Stellar evolution modelling has concluded that the system likely begun as a binary system, with one star about double the Sun's mass and the other roughly equivalent to that of the sun. The larger star eventually aged and expanded as it used up its core hydrogen, and begun having its mass siphoned off by the smaller star; the system is likely to have been an Algol-type eclipsing binary at this stage. This star appears now to be an aged star composed mostly of helium with very little hydrogen and with a mass of 0.2 solar masses and around 37 times the luminosity of the Sun and surface temperature of 7000 K, while the once-smaller star is the Delta Scuti variable that is now around two solar masses. Around 0.8 solar masses has been lost from the system over time.

text: Observations over the decades have shown that its colour slightly changes and it exhibits variation in light that indicate the star is actually an ellipsoidal binary with a period of seven days. The system is more luminous than expected, given the spectrum and distance of the primary star, indicating that the companion star must be contributing a good proportion of its light. Stellar evolution modelling has concluded that the system likely begun as a

text: binary system

text: , with one star about double the

text: Sun's mass

text: and the other roughly equivalent to that of the sun. The larger star eventually aged and expanded as it used up its core hydrogen, and begun having its mass siphoned off by the smaller star; the system is likely to have been an

text: Algol-type eclipsing binary

text: at this stage. This star appears now to be an aged star composed mostly of helium with very little hydrogen and with a mass of 0.2

text: solar mass

text: es and around 37 times the luminosity of the

text: Sun

text: and surface temperature of 7000 K, while the once-smaller star is the Delta Scuti variable that is now around two solar masses. Around 0.8 solar masses has been lost from the system over time.

text: Planetary systems can be categorized according to their orbital dynamics as resonant, non-resonant-interacting, hierarchical, or some combination of these. In resonant systems the orbital periods of the planets are in integer ratios. The Kepler-223 system contains four planets in an 8:6:4:3 orbital resonance.Giant planets are found in mean-motion resonances more often than smaller planets.In interacting systems the planets orbits are close enough together that they perturb the orbital parameters. The Solar System could be described as weakly interacting. In strongly interacting systems Kepler's laws do not hold.In hierarchical systems the planets are arranged so that the system can be gravitationally considered as a nested system of two-bodies, e.g. in a star with a close-in hot jupiter with another gas giant much further out, the star and hot jupiter form a pair that appears as a single object to another planet that is far enough out.

text: Planetary systems can be categorized according to their orbital dynamics as resonant, non-resonant-interacting, hierarchical, or some combination of these. In resonant systems the orbital periods of the planets are in integer ratios. The

text: system contains four planets in an 8:6:4:3

text: orbital resonance

text: .Giant planets are found in mean-motion resonances more often than smaller planets.In interacting systems the planets orbits are close enough together that they perturb the orbital parameters. The Solar System could be described as weakly interacting. In strongly interacting systems

text: Kepler's laws

text: do not hold.In hierarchical systems the planets are arranged so that the system can be gravitationally considered as a nested system of two-bodies, e.g. in a star with a close-in hot jupiter with another gas giant much further out, the star and hot jupiter form a pair that appears as a single object to another planet that is far enough out.

text: Most of the information on solar radiation management is from models and computer simulations. The actual results may differ from the predicted effect. The full effects of various solar radiation management proposals are not yet well understood. It may be difficult to predict the ultimate effects of projects, with models presently giving varying results. In the cases of systems which involve tipping points, effects may be irreversible. Furthermore, most modeling to date consider the effects of using solar radiation management to fully counteract the increase in global average surface temperature arising from a doubling or a quadrupling of the preindustrial carbon dioxide concentration. Under these assumptions, it overcompensates for the changes in precipitation from climate change. Solar radiation management is more likely to be optimized in a way that balances counteracting changes to temperature and precipitation, to compensate for some portion of climate change, and/or to slow down the rate of climate change.

text: Most of the information on solar radiation management is from models and computer simulations. The actual results may differ from the predicted effect. The full effects of various solar radiation management proposals are not yet well understood. It may be difficult to predict the ultimate effects of projects, with models presently giving varying results. In the cases of systems which involve

text: tipping points

text: , effects may be irreversible. Furthermore, most modeling to date consider the effects of using solar radiation management to fully counteract the increase in global average surface temperature arising from a doubling or a quadrupling of the preindustrial carbon dioxide concentration. Under these assumptions, it overcompensates for the changes in precipitation from climate change. Solar radiation management is more likely to be optimized in a way that balances counteracting changes to temperature and precipitation, to compensate for some portion of climate change, and/or to slow down the rate of climate change.

text: The absence of inner super-Earths and the small mass of Mercury may be due to the formation of Jupiter's core close to the Sun and its outward migration across the inner Solar System. During its outward migration this core could push material outward in its resonances leaving the region inside Venus's orbit depleted. In a protoplanetary disk that is evolving via a disk wind planetary embryos may migrate outward in a leaving the Solar System without planets inside Mercury. An instability that led to catastrophic collisions between an early generational of inner planets may have resulted in the debris being ground small enough to be lost due to Poynting-Robertson drag. If planetesimal formation was limited to early in the gas disk epoch an inner edge of the planetesimal disk might be located at the silicate condensation line of this time. The magnetic field of some stars may have been aligned with the rotation of the disk, causing the gas in the inner regions of their disks to be depleted faster. This would enable the solid to gas ratio to reach values high enough for the formation of planetesimals via streaming instabilities closer than Mercury's orbit in these systems.

text: The absence of inner super-Earths and the small mass of Mercury may be due to the formation of Jupiter's core close to the Sun and its outward migration across the inner Solar System. During its outward migration this core could push material outward in its resonances leaving the region inside Venus's orbit depleted. In a protoplanetary disk that is evolving via a disk wind planetary embryos may migrate outward in a leaving the Solar System without planets inside Mercury. An instability that led to catastrophic collisions between an early generational of inner planets may have resulted in the debris being ground small enough to be lost due to Poynting-Robertson drag. If planetesimal formation was limited to early in the gas disk epoch an inner edge of the planetesimal disk might be located at the silicate condensation line of this time. The magnetic field of some stars may have been aligned with the rotation of the disk, causing the gas in the inner regions of their disks to be depleted faster. This would enable the solid to gas ratio to reach values high enough for the formation of planetesimals via

text: streaming instabilities

text: closer than Mercury's orbit in these systems.

text: The Copernican Revolution was the paradigm shift from the Ptolemaic model of the heavens, which described the cosmos as having Earth stationary at the center of the universe, to the heliocentric model with the Sun at the center of the Solar System. Beginning with the publication of Nicolaus Copernicus’s De revolutionibus orbium coelestium, contributions to the “revolution” continued until finally ending with Isaac Newton’s work over a century later.

text: The Copernican Revolution was the

text: paradigm shift

text: from the

text: Ptolemaic model

text: of the heavens, which described the cosmos as having

text: Earth

text: stationary at the center of the universe, to the

text: heliocentric model

text: with the

text: Sun

text: at the center of the

text: Solar System

text: . Beginning with the publication of

text: Nicolaus Copernicus

text: ’s

text: De revolutionibus orbium coelestium

text: , contributions to the “revolution” continued until finally ending with

text: Isaac Newton

text: ’s work over a century later.

text: Mercury has the most eccentric orbit of all the planets; its eccentricity is 0.21 with its distance from the Sun ranging from . It takes 87.969 Earth days to complete an orbit. The diagram on the right illustrates the effects of the eccentricity, showing Mercury's orbit overlaid with a circular orbit having the same semi-major axis. Mercury's higher velocity when it is near perihelion is clear from the greater distance it covers in each 5-day interval. In the diagram the varying distance of Mercury to the Sun is represented by the size of the planet, which is inversely proportional to Mercury's distance from the Sun. This varying distance to the Sun leads to Mercury's surface being flexed by tidal bulges raised by the Sun that are about 17 times stronger than the Moon's on Earth. Combined with a 3:2 spin–orbit resonance of the planet's rotation around its axis, it also results in complex variations of the surface temperature.The resonance makes a single solar day on Mercury last exactly two Mercury years, or about 176 Earth days.

text: Mercury has the most

text: eccentric

text: orbit of all the planets; its eccentricity is 0.21 with its distance from the Sun ranging from . It takes 87.969 Earth days to complete an orbit. The diagram on the right illustrates the effects of the eccentricity, showing Mercury's orbit overlaid with a circular orbit having the same

text: semi-major axis

text: . Mercury's higher velocity when it is near perihelion is clear from the greater distance it covers in each 5-day interval. In the diagram the varying distance of Mercury to the Sun is represented by the size of the planet, which is inversely proportional to Mercury's distance from the Sun. This varying distance to the Sun leads to Mercury's surface being flexed by

text: tidal bulge

text: s raised by the

text: Sun

text: that are about 17 times stronger than the Moon's on Earth. Combined with a 3:2

text: spin–orbit resonance

text: of the planet's rotation around its axis, it also results in complex variations of the surface temperature.The resonance makes a single

text: solar day

text: on Mercury last exactly two Mercury years, or about 176 Earth days.

text: Jupiter has been called the Solar System's vacuum cleaner, because of its immense gravity well and location near the inner Solar System. It receives the most frequent comet impacts of the Solar System's planets. It was thought that the planet served to partially shield the inner system from cometary bombardment. However, recent computer simulations suggest that Jupiter does not cause a net decrease in the number of comets that pass through the inner Solar System, as its gravity perturbs their orbits inward roughly as often as it accretes or ejects them. This topic remains controversial among scientists, as some think it draws comets towards Earth from the Kuiper belt while others think that Jupiter protects Earth from the alleged Oort cloud. Jupiter experiences about 200 times more asteroid and comet impacts than Earth.

text: Jupiter has been called the Solar System's vacuum cleaner, because of its immense

text: gravity well

text: and location near the inner Solar System. It receives the most frequent comet impacts of the Solar System's planets. It was thought that the planet served to partially shield the inner system from cometary bombardment. However, recent computer simulations suggest that Jupiter does not cause a net decrease in the number of comets that pass through the inner Solar System, as its gravity perturbs their orbits inward roughly as often as it accretes or ejects them. This topic remains controversial among scientists, as some think it draws comets towards Earth from the

text: Kuiper belt

text: while others think that Jupiter protects Earth from the alleged

text: Oort cloud

text: . Jupiter experiences about 200 times more

text: asteroid

text: and

text: comet

text: impacts than Earth.

text: It is not presently clear whether a lower size bound will be established as part of the definition of small Solar System bodies in the future, or if it will encompass all material down to the level of meteoroids, the smallest macroscopic bodies in orbit around the Sun. (On a microscopic level there are even smaller objects such as interplanetary dust, particles of solar wind and free particles of hydrogen.)

text: It is not presently clear whether a lower size bound will be established as part of the definition of small Solar System bodies in the future, or if it will encompass all material down to the level of

text: meteoroid

text: s, the smallest macroscopic bodies in orbit around the Sun. (On a microscopic level there are even smaller objects such as

text: interplanetary dust

text: , particles of

text: solar wind

text: and free particles of

text: hydrogen

text: The Kreutz sungrazers (, pronounced kroits) are a family of sungrazing comets, characterized by orbits taking them extremely close to the Sun at perihelion. They are believed to be fragments of one large comet that broke up several centuries ago and are named for German astronomer Heinrich Kreutz, who first demonstrated that they were related. A Kreutz sungrazers's aphelion is about 170 AU from the Sun; these sungrazers make their way from the distant outer Solar System from a patch in the sky in Canis Major, to the inner Solar System, to their perihelion point near the Sun, and then leave the inner Solar System in their return trip to their aphelion.

text: The Kreutz sungrazers (, pronounced kroits) are a family of

text: sungrazing comet

text: s, characterized by

text: orbit

text: s taking them extremely close to the

text: Sun

text: at

text: perihelion

text: . They are believed to be fragments of one large

text: comet

text: that broke up several centuries ago and are named for German

text: astronomer

text: Heinrich Kreutz

text: , who first demonstrated that they were related. A Kreutz sungrazers's

text: aphelion

text: is about 170

text: AU

text: from the Sun; these sungrazers make their way from the distant outer Solar System from a patch in the sky in

text: Canis Major

text: , to the inner Solar System, to their perihelion point near the Sun, and then leave the inner Solar System in their return trip to their aphelion.

text: 71P/Clark is a periodic comet in the Solar System with an orbital period of 5.5 years.

text: 71P/Clark is a

text: periodic

text: comet

text: in the

text: Solar System

text: with an orbital period of 5.5 years.

text: Forbes Collins is a versatile British character actor, seen in supporting roles.  The serious demeanour he gives to some of the 'country-fied' characters he has played is lent gravity via a down-to-earth manner combined with his trademark serious expression.

text: Ionization depends primarily on the Sun and its activity. The amount of ionization in the ionosphere varies greatly with the amount of radiation received from the Sun. Thus there is a diurnal (time of day) effect and a seasonal effect. The local winter hemisphere is tipped away from the Sun, thus there is less received solar radiation. The activity of the Sun is associated with the sunspot cycle, with more radiation occurring with more sunspots. Radiation received also varies with geographical location (polar, auroral zones, mid-latitudes, and equatorial regions). There are also mechanisms that disturb the ionosphere and decrease the ionization. There are disturbances such as solar flares and the associated release of charged particles into the solar wind which reaches the Earth and interacts with its geomagnetic field.

text: Ionization depends primarily on the

text: Sun

text: and its

text: activity

text: . The amount of ionization in the ionosphere varies greatly with the amount of radiation received from the Sun. Thus there is a

text: diurnal

text: (time of day) effect and a seasonal effect. The local winter

text: hemisphere

text: is tipped away from the Sun, thus there is less received solar radiation. The activity of the Sun is associated with the

text: sunspot cycle

text: , with more radiation occurring with more sunspots. Radiation received also varies with geographical location (polar,

text: auroral

text: zones,

text: mid-latitudes

text: , and equatorial regions). There are also mechanisms that disturb the ionosphere and decrease the ionization. There are disturbances such as

text: solar flare

text: s and the associated release of charged particles into the

text: solar wind

text: which reaches the Earth and interacts with its

text: geomagnetic

text: field.

text: In modern thought, the orbits of the planets are viewed as the paths of those planets through mostly empty space. Ancient and medieval thinkers, however, considered the celestial orbs to be thick spheres of rarefied matter nested one within the other, each one in complete contact with the sphere above it and the sphere below. When scholars applied Ptolemy's epicycles, they presumed that each planetary sphere was exactly thick enough to accommodate them. By combining this nested sphere model with astronomical observations, scholars calculated what became generally accepted values at the time for the distances to the Sun (about 4 million miles), to the other planets, and to the edge of the universe (about 73 million miles). The nested sphere model's distances to the Sun and planets differ significantly from modern measurements of the distances, and the size of the universe is now known to be inconceivably large and possibly infinite.

text: In modern thought, the

text: orbits of the planets

text: are viewed as the paths of those planets through mostly empty space. Ancient and medieval thinkers, however, considered the celestial orbs to be thick spheres of rarefied matter nested one within the other, each one in complete contact with the sphere above it and the sphere below. When scholars applied Ptolemy's epicycles, they presumed that each planetary sphere was exactly thick enough to accommodate them. By combining this nested sphere model with astronomical observations, scholars calculated what became generally accepted values at the time for the distances to the Sun (about 4 million miles), to the other planets, and to the edge of the universe (about 73 million miles). The nested sphere model's distances to the Sun and planets differ significantly from modern measurements of the distances, and the

text: size of the universe

text: is now known to be inconceivably large and possibly infinite.

text: In astronomy, the Geocentric model (also known as Geocentrism, or the Ptolemaic system) is a superseded description of the universe with the Earth at the center. Under the geocentric model, the Sun, Moon, stars, and planets all circled Earth. The geocentric model served as the predominant description of the cosmos in many ancient civilizations, such as those of Aristotle and Ptolemy.

text: In

text: astronomy

text: , the Geocentric model (also known as Geocentrism, or the Ptolemaic system) is a

text: superseded

text: description of the

text: universe

text: with the

text: Earth

text: at the center. Under the geocentric model, the

text: Sun

text: Moon

text: star

text: s, and

text: planets

text: all circled Earth. The geocentric model served as the predominant description of the cosmos in many ancient civilizations, such as those of

text: Aristotle

text: and

text: Ptolemy

text: Venus is a terrestrial planet and is sometimes called Earth's "sister planet" because of their similar size, mass, proximity to the Sun, and bulk composition. It is radically different from Earth in other respects. It has the densest atmosphere of the four terrestrial planets, consisting of more than 96% carbon dioxide. The atmospheric pressure at the planet's surface is 92 times that of Earth, or roughly the pressure found  underwater on Earth. Venus is by far the hottest planet in the Solar System, with a mean surface temperature of , even though Mercury is closer to the Sun. Venus is shrouded by an opaque layer of highly reflective clouds of sulfuric acid, preventing its surface from being seen from space in visible light. It may have had water oceans in the past, but these would have vaporized as the temperature rose due to a runaway greenhouse effect. The water has probably photodissociated, and the free hydrogen has been swept into interplanetary space by the solar wind because of the lack of a planetary magnetic field. Venus's surface is a dry desertscape interspersed with slab-like rocks and is periodically resurfaced by volcanism.

text: Venus is a

text: terrestrial planet

text: and is sometimes called Earth's "sister planet" because of their similar size, mass, proximity to the Sun, and bulk composition. It is radically different from Earth in other respects. It has the densest

text: atmosphere

text: of the four terrestrial planets, consisting of more than 96%

text: carbon dioxide

text: . The

text: atmospheric pressure

text: at the planet's surface is 92 times that of Earth, or roughly the pressure found  underwater on Earth. Venus is by far the hottest planet in the Solar System, with a mean surface temperature of , even though

text: Mercury

text: is closer to the Sun. Venus is shrouded by an opaque layer of highly reflective clouds of

text: sulfuric acid

text: , preventing its surface from being seen from space in

text: visible light

text: . It may have had water oceans in the past, but these would have vaporized as the temperature rose due to a

text: runaway greenhouse effect

text: . The water has probably

text: photodissociated

text: , and the free hydrogen has been

text: swept into interplanetary space

text: by the

text: solar wind

text: because of the lack of a

text: planetary magnetic field

text: . Venus's surface is a dry desertscape interspersed with slab-like rocks and is periodically resurfaced by

text: volcanism

text: Though not officially recognized, the name "Methuselah" is commonly used for the planet in popular articles. The name comes from the biblical person Methuselah (who in Christian tradition was the oldest person who ever lived). This name is usually used as the informal name to show the similarities to the planets of the solar system, while the "latter name" is used astronomically.  Methuselah is the only planet to have received a biblical name, although three other extrasolar planets have been given mythological names (just like in the Solar System), those planets being Bellerophon, Zarmina and Osiris.

text: Though not officially recognized, the name "Methuselah" is commonly used for the planet in popular articles. The name comes from the

text: biblical

text: person

text: Methuselah

text: (who in Christian tradition was the oldest person who ever lived). This name is usually used as the informal name to show the similarities to the planets of the

text: solar system

text: , while the "latter name" is used astronomically.  Methuselah is the only planet to have received a biblical name, although three other extrasolar planets have been given mythological names (just like in the Solar System), those planets being

text: Bellerophon

text: Zarmina

text: and

text: Osiris

text: The geocentric system is simpler, being smaller and involving few massive objects: that coordinate system defines its center as the center of mass of the Earth itself. The barycentric system can be loosely thought of as being centered on the Sun, but the Solar System is more complicated. Even the much smaller planets exert gravitational force upon the Sun, causing it to shift position slightly as they orbit. Those shifts are very large in comparison to the measurement precisions that are required for astrometry. Thus, the BCRS defines its center of coordinates as the center of mass of the entire Solar System, its barycenter. This stable point for gravity helps to minimize relativistic effects from any observational frames of reference within the Solar System.

text: The geocentric system is simpler, being smaller and involving few massive objects: that coordinate system defines its center as the

text: center of mass

text: of the Earth itself. The barycentric system can be loosely thought of as being centered on the Sun, but the

text: Solar System

text: is more complicated. Even the much smaller planets exert gravitational force upon the Sun, causing it to shift position slightly as they orbit. Those shifts are very large in comparison to the measurement precisions that are required for astrometry. Thus, the BCRS defines its center of coordinates as the center of mass of the entire Solar System, its

text: barycenter

text: . This stable point for gravity helps to minimize relativistic effects from any observational frames of reference within the Solar System.

text: Grameen Shakti is the leading company on renewable energy in Bangladesh and one of the fastest growing solar energy companies in the world. As of December 2010 Grameen Shakti has installed 25MWp solar system. Beside these, Grameen Shakti have installed solar mobile charging van, Solar lighting Boat, Solar emergency Lighting, Solar water Purifier, solar power telecom systems, Off grid power supply system and also nowadays they are encouraging urban people to use hybrid solar- National grid system with low price.

text: Grameen Shakti

text: is the leading company on renewable energy in Bangladesh and one of the fastest growing solar energy companies in the world. As of December 2010

text: Grameen Shakti

text: has installed 25MWp solar system. Beside these,

text: Grameen Shakti

text: have installed solar mobile charging van, Solar lighting Boat, Solar emergency Lighting, Solar water Purifier, solar power telecom systems, Off grid power supply system and also nowadays they are encouraging urban people to use hybrid solar- National grid system with low price.

text: Dr. Research explains that the Sun is 93 million miles away and its light takes 8 minutes to reach the earth. Light from the next closest star, Alpha Centauri, takes more than 4 years to get to us at a speed greater  than 186,000 miles per second. The sun weighs the same as 330,000 earths and is 95% hydrogen and helium gas and not solid. The Sun is compressed by gravity so tightly that the gas at the center is more than 100 times heavier than water with a pressure of one billion tons per square inch while the surface is about one pound per square inch. The center is 30 million degrees Fahrenheit while the surface is only 10,000 degrees, but the corona is 1 million degrees Fahrenheit though nobody knows why, so scientists study the corona during each solar eclipse.

text: Dr. Research explains that the

text: Sun

text: is 93 million miles away and its light takes 8 minutes to reach the earth. Light from the next closest star,

text: Alpha Centauri

text: , takes more than 4 years to get to us at a speed greater  than 186,000 miles per second. The sun weighs the same as 330,000 earths and is 95%

text: hydrogen

text: and

text: helium

text: gas and not solid. The Sun is compressed by

text: gravity

text: so tightly that the gas at the center is more than 100 times heavier than water with a pressure of one billion tons per square inch while the surface is about one pound per square inch. The center is 30 million degrees Fahrenheit while the surface is only 10,000 degrees, but the

text: corona

text: is 1 million degrees Fahrenheit though

text: nobody knows why

text: , so scientists study the corona during each

text: solar eclipse

text: The term planet is ancient, with ties to history, astrology, science, mythology, and religion. Several planets in the Solar System can be seen with the naked eye. These were regarded by many early cultures as divine, or as emissaries of deities. As scientific knowledge advanced, human perception of the planets changed, incorporating a number of disparate objects. In 2006, the International Astronomical Union (IAU) officially adopted a resolution defining planets within the Solar System. This definition is controversial because it excludes many objects of planetary mass based on where or what they orbit. Although eight of the planetary bodies discovered before 1950 remain "planets" under the modern definition, some celestial bodies, such as Ceres, Pallas, Juno and Vesta (each an object in the solar asteroid belt), and Pluto (the first trans-Neptunian object discovered), that were once considered planets by the scientific community, are no longer viewed as such.

text: The term planet is ancient, with ties to history,

text: astrology

text: , science,

text: mythology

text: , and religion. Several planets in the

text: Solar System

text: can be seen with the naked eye. These were regarded by many early cultures as divine, or as emissaries of

text: deities

text: . As scientific knowledge advanced, human perception of the planets changed, incorporating a number of disparate objects. In 2006, the

text: International Astronomical Union

text: (IAU) officially adopted a resolution

text: defining planets

text: within the Solar System. This definition is controversial because it excludes many objects of

text: planetary mass

text: based on where or what they orbit. Although eight of the planetary bodies discovered before 1950 remain "planets" under the modern definition, some celestial bodies, such as

text: Ceres

text: Pallas

text: Juno

text: and

text: Vesta

text: (each an object in the solar asteroid belt), and

text: Pluto

text: (the first trans-Neptunian object discovered), that were once considered planets by the scientific community, are no longer viewed as such.

text: The spacecraft will make a close approach to the Sun every five months. Around closest approach Solar Orbiter will be positioned for several days over roughly the same region of the solar atmosphere like geostationary satellites are stationed over particular spots on the Earth's surface, so the spacecraft will seem to 'hover' for a while over the Sun. Solar Orbiter will therefore be able to watch magnetic activity building up in the atmosphere that can lead to powerful solar flare or eruptions.

text: The spacecraft will make a close approach to the

text: Sun

text: every five months. Around closest approach Solar Orbiter will be positioned for several days over roughly the same region of the solar atmosphere like geostationary satellites are stationed over particular spots on the Earth's surface, so the spacecraft will seem to 'hover' for a while over the Sun. Solar Orbiter will therefore be able to watch magnetic activity building up in the atmosphere that can lead to powerful

text: solar flare

text: or eruptions.

text: The ecliptic coordinate system is a celestial coordinate system commonly used for representing the positions and orbits of Solar System objects. Because most planets (except Mercury), and many small Solar System bodies have orbits with small inclinations to the ecliptic, using it as thefundamental plane is convenient. The system's origin can be either the center of the Sun or the center of the Earth, its primary direction is towards the vernal (northbound) equinox, and it has a right-handed convention. It may be implemented in spherical coordinates or rectangular coordinates.

text: The ecliptic coordinate system is a

text: celestial coordinate system

text: commonly used for representing the positions and

text: orbit

text: s of

text: Solar System

text: objects. Because most

text: planet

text: s (except

text: Mercury

text: ), and many

text: small Solar System bodies

text: have orbits with small

text: inclination

text: s to the

text: ecliptic

text: , using it as the

entity_name: Fundamental plane (spherical coordinates)

text: fundamental plane

text: is convenient. The system's

text: origin

text: can be either the center of the

text: Sun

text: or the center of the

text: Earth

text: , its primary direction is towards the vernal (northbound)

text: equinox

text: , and it has a

text: right-handed

text: convention. It may be implemented in

text: spherical coordinates

text: or

text: rectangular coordinates

text: In the final battle with the Z-Master, J and Kaidou entered Heart Primeval and set "THE POWER" in the J-Ark to overload, creating a cascade reaction that would destroy the Z-Master from within (also critically damaging King J-Der in the process). Judging this to be a fair trade, J and his team were fully willing to sacrifice themselves in order to end the Zonder threat once and for all. It was revealed that the J-Ark survived the final fight, falling into a wormhole generated by "THE POWER" and emerging at a point 90 million light-years outside of the universe. There, the J-Ark began its slow restoration process. From their unique perspective, Tomoro 0117 determined that the universe was contracting in size; tracking down the source of the contraction, the J-Ark reappeared within Earth's solar system in orbit of Jupiter, where they found an exhausted Mamoru Amami and a mysterious device called the Pas-Q Machine. As Mamoru asked Kaidou to take this device to Earth, Pia Decem of the 11 Planetary Masters of Soul attacked; Kaidou returned to Earth with the Machine, but J retreated to the Tri-Star System with Mamoru.

text: The upper atmosphere of Venus can be measured from Earth when the planet crosses the sun in a rare event known as a solar transit. The last solar transit of Venus occurred in 2012. Using quantitative astronomical spectroscopy, scientists were able to analyse sunlight that passed through the planet's atmosphere to reveal chemicals within it. As the technique to analyse light to discover information about a planet's atmosphere only first showed results in 2001, this was the first opportunity to gain conclusive results in this way on the atmosphere of Venus since observation of solar transits began. This solar transit was a rare opportunity considering the lack of information on the atmosphere between 65 and 85 km. The solar transit in 2004 enabled astronomers to gather a large amount of data useful not only in determining the composition of the upper atmosphere of Venus, but also in refining techniques used in searching for extrasolar planets. The atmosphere of mostly CO, absorbs near-infrared radiation, making it easy to observe. During the 2004 transit, the absorption in the atmosphere as a function of wavelength revealed the properties of the gases at that altitude. The Doppler shift of the gases also enabled wind patterns to be measured.

text: The upper atmosphere of Venus can be measured from Earth when the planet crosses the sun in a rare event known as a

text: solar transit

text: . The last solar

text: transit of Venus

text: occurred in 2012. Using quantitative

text: astronomical spectroscopy

text: , scientists were able to analyse sunlight that passed through the planet's atmosphere to reveal chemicals within it. As the technique to analyse light to discover information about a planet's atmosphere only first showed results in 2001, this was the first opportunity to gain conclusive results in this way on the atmosphere of Venus since observation of solar transits began. This solar transit was a rare opportunity considering the lack of information on the atmosphere between 65 and 85 km. The solar transit in 2004 enabled astronomers to gather a large amount of data useful not only in determining the composition of the upper atmosphere of Venus, but also in refining techniques used in searching for

text: extrasolar planet

text: s. The atmosphere of mostly CO, absorbs near-infrared radiation, making it easy to observe. During the 2004 transit, the absorption in the atmosphere as a function of

text: wavelength

text: revealed the properties of the gases at that altitude. The

text: Doppler shift

text: of the gases also enabled wind patterns to be measured.

text: In 1960, the ephemeris second was defined as In 1958, data was published linking the frequency for the caesium transition, newly established, with the ephemeris second. The ephemeris second is the duration of time that, when used as the independent variable in the laws of motion that govern the movement of the planets and moons in the solar system, causes the laws of motion to accurately predict the observed positions of solar system bodies. Within the limits of observing accuracy, ephemeris seconds are of constant length, as are atomic seconds. This publication allowed a value to be chosen for the length of the atomic second that would work properly with the celestial laws of motion.

text: In 1960, the

text: ephemeris second

text: was defined as In 1958, data was published linking the frequency for the caesium transition, newly established, with the ephemeris second. The ephemeris second is the duration of time that, when used as the independent variable in the laws of motion that govern the movement of the planets and moons in the solar system, causes the laws of motion to accurately predict the observed positions of solar system bodies. Within the limits of observing accuracy, ephemeris seconds are of constant length, as are atomic seconds. This publication allowed a value to be chosen for the length of the atomic second that would work properly with the celestial laws of motion.

text: Although there are many icy objects in the Solar System, there are no known ice planets (though Pluto was considered an ice planet until its reclassification in 2006). If a 9th planet suggested in 2016 is found, it will be an ice planet of many times the earth's mass with a surface temperature potentially under 70K.There are several extrasolar ice planet candidates, including OGLE-2005-BLG-390Lb, OGLE-2013-BLG-0341L b and MOA-2007-BLG-192Lb.

text: Although there are many icy objects in the

text: Solar System

text: , there are no known ice planets (though

text: Pluto

text: was considered an ice planet until its

text: reclassification in 2006

text: ). If a 9th planet suggested in 2016 is found, it will be an ice planet of many times the earth's mass with a surface temperature potentially under 70K.There are several extrasolar ice planet candidates, including

text: , OGLE-2013-BLG-0341L b and

text: Compared to other planetary systems the Solar System stands out in lacking planets interior to the orbit of Mercury. The known Solar System also lacks super-Earths (Planet Nine could be a super-Earth beyond the known Solar System). Uncommonly, it has only small rocky planets and large gas giants; elsewhere planets of intermediate size are typical—both rocky and gas—so there is no "gap" as seen between the size of Earth and of Neptune (with a radius 3.8 times as large). Also, these super-Earths have closer orbits than Mercury. This led to hypothesis that all planetary systems start with many close-in planets, and that typically a sequence of their collisions causes consolidation of mass into few larger planets, but in case of the Solar System the collisions caused their destruction and ejection.

text: Compared to other

text: planetary system

text: s the Solar System stands out in lacking planets interior to the orbit of Mercury. The known Solar System also lacks

text: super-Earth

text: s (

text: Planet Nine

text: could be a super-Earth beyond the known Solar System). Uncommonly, it has only small rocky planets and large gas giants; elsewhere planets of intermediate size are typical—both rocky and gas—so there is no "gap" as seen between the size of Earth and of Neptune (with a radius 3.8 times as large). Also, these super-Earths have closer orbits than Mercury. This led to hypothesis that all planetary systems start with many close-in planets, and that typically a sequence of their collisions causes consolidation of mass into few larger planets, but in case of the Solar System the collisions caused their destruction and ejection.

text: The planetary system in the book included a gas giant planet named Megas in a very short-period orbit about its primary star. (Erythro is a moon of Megas.) This was a radical idea in 1989, but was vindicated with the discovery of the first extrasolar planet orbiting a sun-like star (51 Pegasi) in 1995, dubbed "Bellerophon".  Furthermore, the first speculated "habitable" planet discovered, Gliese 581 c, orbits a red dwarf star (Gliese 581) located only 20.3 light years from Earth—a notable similarity to the novel wherein Erythro is the first inhabited extra–solar body.

text: The planetary system in the book included a

text: gas giant planet

text: named Megas in a very short-period orbit about its primary star. (Erythro is a

text: moon

text: of Megas.) This was a radical idea in 1989, but was vindicated with the discovery of the first

text: extrasolar planet

text: orbiting a sun-like star (

text: 51 Pegasi

text: ) in 1995, dubbed "

text: Bellerophon

text: ".  Furthermore, the first speculated "habitable" planet discovered,

text: Gliese 581 c

text: , orbits a red dwarf star (

text: Gliese 581

text: ) located only 20.3

text: light years

text: from Earth—a notable similarity to the novel wherein Erythro is the first inhabited extra–solar body.

text: A partial solar eclipse occurred on December 2, 1956. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: occurred on December 2, 1956. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: The initial orbits of the giant planets in the Nice 2 model correspond to a predicted orbital structure of the outer Solar System at the end of the gas disk phase.  Models of giant planets orbiting in a gas disk predict that they would migrate toward the central star at a rate dependent on the mass of the planet and characteristics of the disk. In a system with multiple planets this migration can, though not necessarily does, result in the convergence of the planet’s orbits and their capture into mean-motion resonances. Investigations focusing on Jupiter and Saturn demonstrated that they can be captured in their mutual 3:2 resonance.However, capture in this resonance requires special conditions.  After the capture into the mutual 3:2 resonance, the gaps that Jupiter and Saturn formed in the disk's density distribution may overlap and their inward migration may be halted or reversed.  Yet, whether the two planets can migrate back toward their current orbits remains unclear.  When Uranus and Neptune are added in turn to the model they are captured into further resonances with the capture of the outer ice giant resulting in the inner ice giant having a higher eccentricity than the other planets.  The end result is a system in a quadruple resonance. A number of stable configurations have been identified with the particular final configuration depending on the starting locations of the planets.

text: Twenty-nine extrasolar planets have been discovered so far by the HATNet project (note that the discovery of the planet WASP-11b/HAT-P-10b, WASP-40b/HAT-P-27b and WASP-51b/HAT-P-30b was simultaneously announced by the SuperWASP team). All have been discovered using the transit method. In addition, the radial velocity followup has detected an additional companion, either a massive planet or a small brown dwarf around the star HAT-P-13, making this the first known transiting planet in a system with an outer companion in a well-characterised orbit.

text: Twenty-nine

text: extrasolar planets

text: have been discovered so far by the HATNet project (note that the discovery of the planet

text: and

text: was simultaneously announced by the

text: SuperWASP

text: team). All have been discovered using the

text: transit method

text: . In addition, the radial velocity followup has detected an additional companion, either a massive planet or a small

text: brown dwarf

text: around the star HAT-P-13, making this the first known transiting planet in a system with an outer companion in a well-characterised orbit.

text: A partial solar eclipse occurred on May 11, 1975. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: occurred on May 11, 1975. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: Of the eight planets in the solar system, Mercury is the smallest and closest to the Sun. The surface of this planet is similar to the Moon in that it shows characteristics of heavy cratering and plains formed through volcanic eruptions on the surface. These features indicate that Mercury has been geologically inactive for billions of years. Knowledge of Mercury's geology was initially quite limited because observations have only been through the Mariner 10 flyby in 1975 and observations from Earth. The MESSENGER (an acronym of MErcury Surface, Space ENvironment, GEochemistry, and Ranging) mission of 2004 is a robotic NASA spacecraft orbiting the planet, the first spacecraft ever to do so. MESSENGER has given additional data which has revealed that Mercury is geologically complex.

text: Of the eight

text: planet

text: s in the

text: solar system

text: Mercury

text: is the smallest and closest to the

text: Sun

text: . The surface of this planet is similar to the

text: Moon

text: in that it shows characteristics of heavy cratering and plains formed through

text: volcanic eruption

text: s on the surface. These features indicate that Mercury has been

text: geologically

text: inactive for billions of years. Knowledge of

text: Mercury's geology

text: was initially quite limited because observations have only been through the

text: Mariner 10

text: flyby in 1975 and observations from

text: Earth

text: . The

text: MESSENGER

text: (an acronym of MErcury Surface, Space ENvironment, GEochemistry, and Ranging) mission of 2004 is a robotic

text: NASA

text: spacecraft orbiting the planet, the first spacecraft ever to do so. MESSENGER has given additional data which has revealed that Mercury is geologically complex.

text: There may also be gas giant planets in this system, already formed (in the first 1-5 Myrs) before the current era of rocky planet formation. While none have been detected to date, by analogy with the solar system, their presence is likely, since evidence for analogues of the solar system's asteroid belt, Kuiper belt, and terrestrial planets have been found.

text: There may also be

text: gas giant

text: planets in this system, already formed (in the first 1-5 Myrs) before the current era of rocky planet formation. While none have been detected to date, by analogy with the solar system, their presence is likely, since evidence for analogues of the solar system's asteroid belt, Kuiper belt, and terrestrial planets have been found.

text: Book 3, subtitled De mundi systemate (On the system of the world), is an exposition of many consequences of universal gravitation, especially its consequences for astronomy. It builds upon the propositions of the previous books, and applies them with further specificity than in Book 1 to the motions observed in the solar system. Here (introduced by Proposition 22, and continuing in Propositions 25–35) are developed several of the features and irregularities of the orbital motion of the Moon, especially the variation. Newton lists the astronomical observations on which he relies, and establishes in a stepwise manner that the inverse square law of mutual gravitation applies to solar system bodies, starting with the satellites of Jupiter and going on by stages to show that the law is of universal application. He also gives starting at Lemma 4 and Proposition 40 the theory of the motions of comets, for which much data came from John Flamsteed and Edmond Halley, and accounts for the tides, attempting quantitative estimates of the contributions of the Sun and Moon to the tidal motions; and offers the first theory of the precession of the equinoxes. Book 3 also considers the harmonic oscillator in three dimensions, and motion in arbitrary force laws.

text: Book 3, subtitled De mundi systemate (On the system of the world), is an exposition of many consequences of universal gravitation, especially its consequences for astronomy. It builds upon the propositions of the previous books, and applies them with further specificity than in Book 1 to the motions observed in the solar system. Here (introduced by Proposition 22, and continuing in Propositions 25–35) are developed

text: several of the features and irregularities

text: of the orbital motion of the Moon, especially the

text: variation

text: . Newton lists the astronomical observations on which he relies, and establishes in a stepwise manner that the inverse square law of mutual gravitation applies to solar system bodies, starting with the satellites of Jupiter and going on by stages to show that the law is of universal application. He also gives starting at Lemma 4 and Proposition 40 the theory of the motions of comets, for which much data came from

text: John Flamsteed

text: and

text: Edmond Halley

text: , and accounts for the tides, attempting quantitative estimates of the contributions of the Sun and Moon to the tidal motions; and offers the first theory of the precession of the equinoxes. Book 3 also considers the

text: harmonic oscillator

text: in three dimensions, and motion in arbitrary force laws.

text: The Sweden Solar System is the world's largest permanent scale model of the Solar System. The Sun is represented by the Ericsson Globe in Stockholm, the largest hemispherical building in the world. The inner planets can also be found in Stockholm but the outer planets are situated northward in other cities along the Baltic Sea. The system was started by Nils Brenning and Gösta Gahm and is on the scale of 1:20 million.

text: The Sweden Solar System is the world's largest permanent

text: scale model of the Solar System

text: . The

text: Sun

text: is represented by the

text: Ericsson Globe

text: in

text: Stockholm

text: , the largest hemispherical building in the world. The inner planets can also be found in Stockholm but the outer planets are situated northward in other cities along the

text: Baltic Sea

text: . The system was started by Nils Brenning and Gösta Gahm and is on the scale of 1:20 million.

text: Chen believed that the Earth went through five tribulations going back to the age of the dinosaurs. Each of these tribulations were survived by beings living in North America who were rescued by God in a flying saucer. He believed the solar system is 4.5 trillion years old, or roughly 300 times the age science gives for the Universe. He believed that the solar system was created by a nuclear war.

text: Chen believed that the Earth went through five tribulations going back to the age of the dinosaurs. Each of these tribulations were survived by beings living in

text: North America

text: who were rescued by God in a

text: flying saucer

text: . He believed the solar system is 4.5 trillion years old, or roughly 300 times the age science gives for the

text: Universe

text: . He believed that the solar system was created by a

text: nuclear war

text: . (The EGF g(z) may not include objects of size zero. This is because they are not distinguished by labels and therefore the presence of two or more of such objects creates orbits whose size is less than

text: With the observations of William Herschel, Friedrich Bessel, and others, astronomers realized that the sun, although the center of Earth's solar system, was not the center of the universe.

text: With the observations of

text: William Herschel

text: Friedrich Bessel

text: , and others, astronomers realized that the sun, although the center of Earth's solar system, was not the center of the universe.

text: Alexis Bouvard (27 June 1767 – 7 June 1843) was a French astronomer. He is particularly noted for his careful observations of the irregularities in the motion of Uranus and his hypothesis of the existence of an eighth planet in the solar system.

text: Alexis Bouvard (27 June 1767 – 7 June 1843) was a French

text: astronomer

text: . He is particularly noted for his careful observations of the irregularities in the motion of

text: Uranus

text: and his hypothesis of the existence of an eighth planet in the

text: solar system

text: An open orbit will have a parabolic shape if it has velocity of exactly the escape velocity at that point in its trajectory, and it will have the shape of a hyperbola when its velocity is greater than the escape velocity. When bodies with escape velocity or greater approach each other, they will briefly curve around each other at the time of their closest approach, and then separate, forever. This may be the case with most comets if they come from outside the solar system.

text: An open orbit will have a parabolic shape if it has velocity of exactly the escape velocity at that point in its trajectory, and it will have the shape of a

text: hyperbola

text: when its velocity is greater than the escape velocity. When bodies with escape velocity or greater approach each other, they will briefly curve around each other at the time of their closest approach, and then separate, forever. This may be the case with most comets if they come from outside the solar system.

text: In the present day, the Sun is losing mass from the emission of electromagnetic energy and by the ejection of matter with the solar wind. It is expelling about (2–3)  per year. The mass loss rate will increase when the Sun enters the red giant stage, climbing to (7–9)  y when it reaches the tip of the red giant branch. This will rise to 10  y on the asymptotic giant branch, before peaking at a rate of 10 to 10  y as the Sun generates a planetary nebula. By the time the Sun becomes a degenerate white dwarf, it will have lost 46% of its starting mass.

text: In the present day, the Sun is losing mass from the emission of electromagnetic energy and by the ejection of matter with the

text: solar wind

text: . It is expelling about (2–3)  per year. The mass loss rate will increase when the Sun enters the

text: red giant

text: stage, climbing to (7–9)  y when it reaches the

text: tip of the red giant branch

text: . This will rise to 10  y on the

text: asymptotic giant branch

text: , before peaking at a rate of 10 to 10  y as the Sun generates a

text: planetary nebula

text: . By the time the Sun becomes a degenerate

text: white dwarf

text: , it will have lost 46% of its starting mass.

text: Early in the 11th century Alhazen wrote a scathing critique of Ptolemy's model in his Doubts on Ptolemy (c. 1028), which some have interpreted to imply he was criticizing Ptolemy's geocentrism, but most agree that he was actually criticizing the details of Ptolemy's model rather than his geocentrism. Abu Rayhan Biruni (b. 973) discussed the possibility of whether the Earth rotated about its own axis and around the Sun, but in his Masudic Canon, he set forth the principles that the Earth is at the center of the universe and that it has no motion of its own. He was aware that if the Earth rotated on its axis, this would be consistent with his astronomical parameters, but he considered it a problem of natural philosophy rather than mathematics.

text: Early in the 11th century

text: Alhazen

text: wrote a scathing critique of

text: Ptolemy

text: 's model in his Doubts on Ptolemy (c. 1028), which some have interpreted to imply he was criticizing Ptolemy's geocentrism, but most agree that he was actually criticizing the details of Ptolemy's model rather than his geocentrism.

text: Abu Rayhan Biruni

text: (b. 973) discussed the possibility of whether the Earth rotated about its own axis and around the Sun, but in his Masudic Canon, he set forth the principles that the Earth is at the center of the universe and that it has no motion of its own. He was aware that if the Earth rotated on its axis, this would be consistent with his astronomical parameters, but he considered it a problem of

text: natural philosophy

text: rather than mathematics.

text: Cloez also played a role in developing a theory on the origin of life elsewhere in the Solar system.

text: Cloez also played a role in developing a theory on the origin of life elsewhere in the

text: Solar system

text: Planetary migration occurs when a planet or other stellar satellite interacts with a disk of gas or planetesimals, resulting in the alteration of the satellite's orbital parameters, especially its semi-major axis.  Planetary migration is the most likely explanation for hot Jupiters, extrasolar planets with jovian masses, but orbits of only a few days.  The generally accepted theory of planet formation from a protoplanetary disk predicts such planets cannot form so close to their stars, as there is insufficient mass at such small radii and the temperature is too high to allow the formation of rocky or icy planetesimals.  It has also become clear that terrestrial-mass planets may be subject to rapid inward migration if they form while the gas disk is still present. This may affect the formation of the cores of the giant planets (which have masses of the order of 10 Earth masses), if those planets form via the core accretion mechanism.

text: Planetary migration occurs when a

text: planet

text: or other stellar satellite interacts with a disk of gas or

text: planetesimal

text: s, resulting in the alteration of the satellite's orbital parameters, especially its

text: semi-major axis

text: .  Planetary migration is the most likely explanation for

text: hot Jupiter

text: s,

text: extrasolar planets

text: with

text: jovian

text: masses, but orbits of only a few days.  The generally accepted

text: theory of planet formation

text: from a

text: protoplanetary disk

text: predicts such planets cannot form so close to their stars, as there is insufficient mass at such small radii and the temperature is too high to allow the formation of rocky or icy planetesimals.  It has also become clear that

text: terrestrial-mass planet

text: s may be subject to rapid inward migration if they form while the gas disk is still present. This may affect the formation of the cores of the giant planets (which have masses of the order of 10 Earth masses), if those planets form via the core accretion mechanism.

text: A partial solar eclipse occurred on April 17, 1996. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: occurred on April 17, 1996. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: Varley has written several novels (his first attempt, Gas Giant, was, he admits, "pretty bad") and numerous short stories, many of them in a future history, "The Eight Worlds". These stories are set a century or two after a race of mysterious and omnipotent aliens, the Invaders, have almost completely eradicated humans from the Earth (they regard whales and dolphins to be the superior Terran lifeforms and humans as only a dangerous infestation). But humans have inhabited virtually every other corner of the solar system, often through the use of wild biological modifications learned, in part, by eavesdropping on alien communications. His detailed speculations on the ways humans might use advances in biological science were revelatory in the 1970s when his story collection The Persistence of Vision was released. The title story won the Hugo and Nebula awards.

text: Varley has written several novels (his first attempt, Gas Giant, was, he admits, "pretty bad") and numerous short stories, many of them in a

text: future history

text: "The Eight Worlds"

text: . These stories are set a century or two after a race of mysterious and omnipotent aliens, the Invaders, have almost completely eradicated humans from the Earth (they regard

text: whale

text: s and

text: dolphin

text: s to be the superior Terran lifeforms and humans as only a dangerous infestation). But humans have inhabited virtually every other corner of the solar system, often through the use of wild biological modifications learned, in part, by

text: eavesdropping

text: on alien communications. His detailed speculations on the ways humans might use advances in biological science were revelatory in the 1970s when his story collection

text: The Persistence of Vision

text: was released. The title story won the

text: Hugo

text: and

text: Nebula

text: awards.

text: The Stardust sign gave visitors a panoramic view of the solar system.  At the sign's center sat a  diameter plastic model of the Earth. Cosmic rays of neon and electric light bulbs beamed from behind the model Earth in all direction. Three-dimensional acrylic glass planets spun alongside 20 scintillating neon starbursts. Across the universe was a jagged galaxy of electric lettering spelling out "Stardust". The sign utilized  of neon tubing with over 11,000 bulbs along its  front. The "S" alone contained 975 lamps. At night the neon constellation was reportedly visible  away.

text: The Stardust sign gave visitors a panoramic view of the solar system.  At the sign's center sat a  diameter plastic model of the Earth. Cosmic rays of neon and electric light bulbs beamed from behind the model Earth in all direction. Three-dimensional

text: acrylic glass

text: planets spun alongside 20 scintillating neon starbursts. Across the universe was a jagged galaxy of electric lettering spelling out "Stardust". The sign utilized  of neon tubing with over 11,000 bulbs along its  front. The "S" alone contained 975 lamps. At night the neon constellation was reportedly visible  away.

text: Formation and evolution of the Solar System –

text: Formation and evolution of the Solar System

text: This is a list of the lists of small Solar System bodies and dwarf planets.

text: This is a list of the lists of

text: small Solar System bodies

text: and

text: dwarf planet

text: s.

text: As the story opens, it is the near future as seen from the perspective of the early 1950s. Earth is in radio contact with civilizations on planets in our solar system, as well as planets in other, distant solar systems, and Commando Cody has just built the world's first spaceship. The rest of the world appears unchanged by these galactic developments. (The exterior of Cody's headquarters building is actually a Republic Pictures office building.)  A mysterious despot, known only as "The Ruler", his base planet even being unknown, is trying to take over the Earth with various disastrous devices. Cody is enlisted by the American government to put an end to the trouble, which takes him into the stratosphere, into outer space, and even to other worlds. The Ruler is finally brought down on Mercury, with the aid of the Mercurian Queen and her soldiers.

text: The planet is not so much notable for its size (which is estimated to be around 1.69 ), or possible composition—although these are unusual—but for the fact that such a relatively small exoplanet was detected at such a relatively large distance from its star. Prior to this, "small" exoplanets such as Gliese 876 d, which has a "year" of less than 2 Earth-days, were detected very close to their stars. OGLE-2005-BLG-390Lb shows a combination of size and orbit that would not make it out of place in the Solar System.

text: The planet is not so much notable for its size (which is estimated to be around 1.69 ), or possible composition—although these are unusual—but for the fact that such a relatively small exoplanet was detected at such a relatively large distance from its star. Prior to this, "small" exoplanets such as

text: Gliese 876 d

text: , which has a "year" of less than 2 Earth-days, were detected very close to their stars. OGLE-2005-BLG-390Lb shows a combination of size and orbit that would not make it out of place in the

text: Solar System

text: The Space Atlas includes star charts, photography, and other information. Trefil, the Robinson Professor of Physics at George Mason University also highlights scientists whose discoveries helped inform this book and human knowledge of the universe, such as Nicolaus Copernicus, who produced the first serious model of the solar system in which the sun was at the center and Earth moved in orbit, and Jocelyn Bell Burnell, who discovered the signals of pulsars.

text: The Space Atlas includes star charts, photography, and other information. Trefil, the Robinson Professor of Physics at

text: George Mason University

text: also highlights scientists whose discoveries helped inform this book and human knowledge of the universe, such as

text: Nicolaus Copernicus

text: , who produced the first serious model of the solar system in which the sun was at the center and Earth moved in orbit, and

text: Jocelyn Bell Burnell

text: , who discovered the signals of

text: pulsar

text: s.

text: A gravity well or gravitational well is a conceptual model of the gravitational field surrounding a body in space – the more massive the body, the deeper and more extensive the gravity well associated with it. The Sun is very massive, relative to other bodies in the Solar System, so the corresponding gravity well that surrounds it appears "deep" and far-reaching. The gravity wells of asteroids and small moons, conversely, are often depicted as very shallow. Anything on the surface of a planet or moon is considered to be at the bottom of that celestial body's gravity well, and so escaping the effects of gravity from such a planet or moon (to enter outer space) is sometimes called "climbing out of the gravity well". The deeper a gravity well is, the more energy any space-bound "climber" must use to escape it.

text: A gravity well or gravitational well is a conceptual model of the gravitational field surrounding a body in space – the more massive the body, the deeper and more extensive the gravity well associated with it. The

text: Sun

text: is very massive, relative to other bodies in the

text: Solar System

text: , so the corresponding gravity well that surrounds it appears "deep" and far-reaching. The gravity wells of asteroids and small moons, conversely, are often depicted as very shallow. Anything on the surface of a planet or moon is considered to be at the bottom of that celestial body's gravity well, and so escaping the effects of

text: gravity

text: from such a planet or moon (to enter outer space) is sometimes called "climbing out of the gravity well". The deeper a gravity well is, the more energy any space-bound "climber" must use to

text: escape it

text: The core of the Sun is considered to extend from the center to about 0.2 to 0.25 of solar radius. It is the hottest part of the Sun and of the Solar System. It has a density of 150 g/cm³ (150 times the density of liquid water) at the center, and a temperature of 15 million degrees Celsius. The core is made of hot, dense gas in the plasmic state (ions and electrons), at a pressure estimated at 265 billion bar (3.84 trillion psi or 26.5 petapascals (PPa)) at the center. Due to fusion, the composition of the solar plasma drops from 68-70% hydrogen by mass at the outer core, to 33% hydrogen at the core/Sun center.

text: The core of the Sun is considered to extend from the center to about 0.2 to 0.25 of

text: solar radius

text: . It is the hottest part of the

text: Sun

text: and of the

text: Solar System

text: . It has a density of 150 g/cm³ (150 times the density of liquid

text: water

text: ) at the center, and a temperature of 15 million degrees Celsius. The core is made of

text: hot, dense gas in the plasmic state

text: (ions and electrons), at a pressure estimated at 265 billion

text: bar

text: (3.84 trillion

text: psi

text: or 26.5

text: peta

text: pascal

text: s (PPa)) at the center. Due to fusion, the composition of the solar plasma drops from 68-70% hydrogen by mass at the outer core, to 33% hydrogen at the core/Sun center.

text: Kamalākara's major work, "Siddhāntatattvaviveka", was compiled in Varanasi at about 1658 and has been published by Sudhakar Dwivedi in the Vārāṇasī series. This work consists of 13 chapters in 3,024 verses. It deals with the topics of: units of time measurement; mean motions of the planets; true longitudes of the planets; the three problems of diurnal rotation; diameters and distances of the planets; the earth's shadow; the moon's crescent; risings and settings; syzygies; lunar eclipses, solar eclipses; planetary transits across the sun's disk; the patas of the moon and sun; the "great problems"; along a conclusion. His other works include Śeṣavāsanā and Sauravāsanā. Kamalākara was bitterly opposed to Munishvara, the author of Siddhāntasārvabhauma.

text: Kamalākara's major work, "Siddhāntatattvaviveka", was compiled in

text: Varanasi

text: at about 1658 and has been published by

text: Sudhakar Dwivedi

text: in the Vārāṇasī series. This work consists of 13 chapters in 3,024 verses. It deals with the topics of: units of time measurement; mean motions of the planets; true longitudes of the planets; the three problems of diurnal rotation; diameters and distances of the planets; the earth's shadow; the moon's crescent; risings and settings; syzygies; lunar eclipses, solar eclipses; planetary transits across the sun's disk; the patas of the moon and sun; the "great problems"; along a conclusion. His other works include Śeṣavāsanā and Sauravāsanā. Kamalākara was bitterly opposed to

text: Munishvara

text: , the author of Siddhāntasārvabhauma.

text: One result of this axis orientation is that, averaged over the Uranian year, the polar regions of Uranus receive a greater energy input from the Sun than its equatorial regions. Nevertheless, Uranus is hotter at its equator than at its poles. The underlying mechanism that causes this is unknown. The reason for Uranus's unusual axial tilt is also not known with certainty, but the usual speculation is that during the formation of the Solar System, an Earth-sized protoplanet collided with Uranus, causing the skewed orientation. Uranus's south pole was pointed almost directly at the Sun at the time of Voyager 2's flyby in 1986. The labelling of this pole as "south" uses the definition currently endorsed by the International Astronomical Union, namely that the north pole of a planet or satellite is the pole that points above the invariable plane of the Solar System, regardless of the direction the planet is spinning. A different convention is sometimes used, in which a body's north and south poles are defined according to the right-hand rule in relation to the direction of rotation.

text: One result of this axis orientation is that, averaged over the Uranian year, the polar regions of Uranus receive a greater energy input from the Sun than its equatorial regions. Nevertheless, Uranus is hotter at its equator than at its poles. The underlying mechanism that causes this is unknown. The reason for Uranus's unusual axial tilt is also not known with certainty, but the usual speculation is that during the formation of the Solar System, an Earth-sized

text: protoplanet

text: collided with Uranus, causing the skewed orientation. Uranus's south pole was pointed almost directly at the Sun at the time of Voyager 2's flyby in 1986. The labelling of this pole as "south" uses the definition currently endorsed by the

text: International Astronomical Union

text: , namely that the north pole of a planet or satellite is the pole that points above the invariable plane of the Solar System, regardless of the direction the planet is spinning. A different convention is sometimes used, in which a body's north and south poles are defined according to the

text: right-hand rule

text: in relation to the direction of rotation.

text: The interplanetary medium is the material which fills the Solar System, and through which all the larger Solar System bodies, such as planets, dwarf planets, asteroids, and comets, move.

text: The interplanetary medium is the material which fills the

text: Solar System

text: , and through which all the larger Solar System bodies, such as

text: planet

text: s,

text: dwarf planet

text: s,

text: asteroid

text: s, and

text: comet

text: s, move.

text: The isotopic homogeneity of our planet and the Solar System provides a blank slate on which to detect the effect of nuclear processes on Earth, in the Solar System, and in objects coming to us from outside the Solar System.  Awaiting more here, see natural abundance.

text: The isotopic homogeneity of our

text: planet

text: and the Solar System provides a blank slate on which to detect the effect of nuclear processes on Earth, in the Solar System, and in objects coming to us from outside the Solar System.  Awaiting more here, see

text: natural abundance

text: Research is in progress at universities such as Radboud University Nijmegen and Delft University of Technology. For example, at Massachusetts Institute of Technology researchers have developed approaches for conversion of windows into sunlight concentrators for generation of electricity. They paint a mixture of dyes onto a pane of glass or plastic. The dyes absorb sunlight and re-emit it as fluorescence within the glass, where it is confined by internal reflection, emerging at the edges of the glass, where it encounters solar cells optimized for conversion of such concentrated sunlight. The concentration factor is about 40, and the optical design yields a solar concentrator that unlike lens-based concentrators, need not be directed accurately at the sun, and can produce output even from diffuse light. Covalent Solar is working on commercialization of the process.

text: Research is in progress at universities such as

text: Radboud University Nijmegen

text: and

text: Delft University of Technology

text: . For example, at

text: Massachusetts Institute of Technology

text: researchers have developed approaches for conversion of windows into sunlight concentrators for generation of electricity. They paint a mixture of dyes onto a pane of glass or plastic. The dyes absorb sunlight and re-emit it as fluorescence within the glass, where it is confined by

text: internal reflection

text: , emerging at the edges of the glass, where it encounters solar cells optimized for conversion of such concentrated sunlight. The concentration factor is about 40, and the optical design yields a

text: solar concentrator

text: that unlike lens-based concentrators, need not be directed accurately at the sun, and can produce output even from diffuse light. Covalent Solar is working on commercialization of the process.

text: A partial solar eclipse will occur on June 21, 2058. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: will occur on June 21, 2058. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: In pebble accretion the accretion of objects ranging from cm's up to meters in diameter onto planetesimals in a protoplanetary disk is enhanced by aerodynamic drag. The rapid growth of the planetesimals via pebble accretion allows for the formation of giant planet cores in the outer Solar System before the dispersal of the gas disk. A reduction in the size of pebbles as they lose water ice after crossing the ice line and a declining density of gas with distance from the sun slow the rates of pebble accretion in the inner Solar System resulting in smaller terrestrial planets, a small mass of Mars and a low mass asteroid belt.

text: Impacts between planet-sized bodies in the early Solar System are important aspects in the formation and growth of planets and planetary cores.

text: Over the blue portion there's an oval with a sun. The sun has seventeen rays that represent the different regions of the town. The sun, being the center of our solar system, represents Orocovis as the center of the island of Puerto Rico.

text: Over the blue portion there's an

text: oval

text: with a

text: sun

text: . The sun has seventeen rays that represent the different regions of the town. The sun, being the center of our

text: solar system

text: , represents Orocovis as the center of the island of

text: Puerto Rico

text: In 2011, the refereed journal Energy Policy published two articles by Mark Z. Jacobson, a professor of engineering at Stanford University, and research scientist Mark A. Delucchi, about changing our energy supply mix and "Providing all global energy with wind, water, and solar power". The articles analyze the feasibility of providing worldwide energy for electric power, transportation, and heating/cooling from wind, water, and sunlight (WWS), which are safe clean options. In Part I, Jacobson and Delucchi discuss WWS energy system characteristics, aspects of energy demand, WWS resource availability, WWS devices needed, and material requirements.  They estimate that 3,800,000 5 MW wind turbines, 5350 100 MW geothermal power plants, and 270 new 1300 MW hydroelectric power plants will be required. In terms of solar power, an additional 49,000 300 MW concentrating solar plants, 40,000 300 MW solar photovoltaic power plants, and 1.7 billion 3 kW rooftop photovoltaic systems will also be needed. Such an extensive WWS infrastructure could decrease world power demand by 30%.  In Part II, Jacobson and Delucchi address variability of supply, system economics, and energy policy initiatives associated with a WWS system. The authors advocate producing all new energy with WWS by 2030 and replacing existing energy supply arrangements by 2050. Barriers to implementing the renewable energy plan are seen to be "primarily social and political, not technological or economic". Energy costs with a WWS system should be similar to today's energy costs.

text: In 2011, the refereed journal

text: Energy Policy

text: published two articles by

text: Mark Z. Jacobson

text: , a professor of engineering at

text: Stanford University

text: , and research scientist Mark A. Delucchi, about changing our energy supply mix and "Providing all global energy with wind, water, and solar power". The articles analyze the feasibility of providing worldwide energy for electric power, transportation, and heating/cooling from wind, water, and sunlight (WWS), which are safe clean options. In Part I, Jacobson and Delucchi discuss WWS energy system characteristics, aspects of energy demand, WWS resource availability, WWS devices needed, and material requirements.  They estimate that 3,800,000 5 MW

text: wind turbines

text: , 5350 100 MW

text: geothermal power

text: plants, and 270 new 1300 MW

text: hydroelectric power

text: plants will be required. In terms of

text: solar power

text: , an additional 49,000 300 MW

text: concentrating solar

text: plants, 40,000 300 MW

text: solar photovoltaic

text: power plants, and 1.7 billion 3 kW rooftop photovoltaic systems will also be needed. Such an extensive WWS infrastructure could decrease world power demand by 30%.  In Part II, Jacobson and Delucchi address variability of supply, system economics, and energy policy initiatives associated with a WWS system. The authors advocate producing all new energy with WWS by 2030 and replacing existing energy supply arrangements by 2050. Barriers to implementing the renewable energy plan are seen to be "primarily social and political, not technological or economic". Energy costs with a WWS system should be similar to today's energy costs.

text: The researchers at the MPS are studying the complete range of dynamic and often spectacular processes occurring on the Sun – from the interior to the outer heliosphere. At the heart of this research is the magnetic field, which plays a decisive role in these processes. It is generated by gas currents in the interior of the Sun and causes, among other things, dark spots on the surface. Answers to the following questions are being sought: Why does the magnetic field change with an eleven-year cycle? How does the magnetic field produce the various structures on the Sun? How is the corona heated to many millions of degrees?Instruments developed by MPS aboard the space- craft SOHO and Ulysses have provided fundamentally new insights: Measurements of the ultraviolet spectrometer SUMER on board SOHO played a decisive role in recognising the significance of the magnetic field for dynamic processes and Ulysses measured the three-dimensional structure of the solar wind for the first time.Another important research topic at the "The Sun and Heliosphere" department is the influence on the Earth due to the Sun’s variable activity. Scientists are working intensively on the project STEREO, in which two identical spacecraft trace disturbances from the Sun to the Earth from different observational points, permitting predictions of potentially dangerous events.The physical processes involved in the origin and development of magnetic fields on the Sun take place on very small scales and therefore require measurements with very high spatial resolution. The balloon-borne telescope Sunrise, built under Institute leadership and flown in June 2009, was able to make out structures on the Sun’s surface as small as 100 kilometers.Future projects will stress research into the physical causes of the Sun’s variations. The ambitious Solar Orbiter Mission, based on a suggestion from the Institute, will see a probe approach our star to within a fifth of the Earth-Sun distance in order to investigate the magnetic field and its effects in the various layers of the solar atmosphere.

text: The researchers at the MPS are studying the complete range of dynamic and often spectacular processes occurring on the Sun – from the interior to the outer heliosphere. At the heart of this research is the

text: magnetic field

text: , which plays a decisive role in these processes. It is generated by gas currents in the interior of the

text: Sun

text: and causes, among other things, dark spots on the surface. Answers to the following questions are being sought: Why does the magnetic field change with an eleven-year cycle? How does the magnetic field produce the various structures on the Sun? How is the corona heated to many millions of degrees?Instruments developed by MPS aboard the space- craft

text: SOHO

text: and

text: Ulysses

text: have provided fundamentally new insights: Measurements of the ultraviolet spectrometer

text: SUMER

text: on board

text: SOHO

text: played a decisive role in recognising the significance of the magnetic field for dynamic processes and

text: Ulysses

text: measured the three-dimensional structure of the solar wind for the first time.Another important research topic at the "The Sun and Heliosphere" department is the influence on the Earth due to the Sun’s variable activity. Scientists are working intensively on the project

text: STEREO

text: , in which two identical spacecraft trace disturbances from the Sun to the Earth from different observational points, permitting predictions of potentially dangerous events.The physical processes involved in the origin and development of magnetic fields on the Sun take place on very small scales and therefore require measurements with very high spatial resolution. The balloon-borne telescope

text: Sunrise

text: , built under Institute leadership and flown in June 2009, was able to make out structures on the Sun’s surface as small as 100 kilometers.Future projects will stress research into the physical causes of the Sun’s variations. The ambitious

text: Solar Orbiter

text: Mission, based on a suggestion from the Institute, will see a probe approach our star to within a fifth of the Earth-Sun distance in order to investigate the magnetic field and its effects in the various layers of the solar atmosphere.

text: The oligarch theory of planet formation states that there were hundreds of planet-sized objects, known as oligarchs, in the early stages of the Solar System's evolution. In 2005, astronomer Eugene Chiang speculated that although some of these oligarchs became the planets we know today, most would have been flung outward by gravitational interactions. Some may have escaped the Solar System altogether to become free-floating planets, whereas others would be orbiting in a halo around the Solar System, with orbital periods of millions of years. This halo would lie at between 1,000 and 10,000 AU from the Sun, or between a third and a thirtieth the distance to the Oort cloud.

text: The oligarch theory of

text: planet formation

text: states that there were hundreds of planet-sized objects, known as oligarchs, in the early stages of the Solar System's evolution. In 2005, astronomer Eugene Chiang speculated that although some of these oligarchs became the planets we know today, most would have been flung outward by gravitational interactions. Some may have escaped the Solar System altogether to become

text: free-floating planets

text: , whereas others would be orbiting in a halo around the Solar System, with orbital periods of millions of years. This halo would lie at between 1,000 and 10,000 AU from the Sun, or between a third and a thirtieth the distance to the

text: Oort cloud

text: The total installed solar power in Brazil was estimated to be 69 MWp at the end of 2015 and generates less than 0.01 percent of the country's electricity demand. Changes to net metering rules for small-scale solar were announced in November 2015 although there were only 1,300 grid-connected systems at that time. Brazil expects to have 1.2 million systems in the year 2024.

text: The total installed solar power in Brazil was estimated to be 69 MWp at the end of 2015 and generates less than 0.01 percent of the country's electricity demand. Changes to

text: net metering

text: rules for small-scale solar were announced in November 2015 although there were only 1,300 grid-connected systems at that time. Brazil expects to have 1.2 million systems in the year 2024.

text: Post-graduation, Shapley received a fellowship to Princeton University for graduate work, where he studied under Henry Norris Russell and used the period-luminosity relation for Cepheid variable stars (discovered by Henrietta Swan Leavitt) to determine distances to globular clusters. He was instrumental in moving astronomy away from the idea that Cepheids were spectroscopic binaries, and toward the concept that they were pulsators. He was the first to realize that the Milky Way Galaxy was much larger than previously believed, and that the Sun's place in the galaxy was in a nondescript location. This discovery by Shapley is a part of the Copernican principle, according to which the Earth is not at the center of our Solar System, our galaxy, or our Universe.

text: Post-graduation, Shapley received a fellowship to

text: Princeton University

text: for graduate work, where he studied under

text: Henry Norris Russell

text: and used the period-luminosity relation for

text: Cepheid variable star

text: s (discovered by

text: Henrietta Swan Leavitt

text: ) to determine distances to

text: globular cluster

text: s. He was instrumental in moving astronomy away from the idea that Cepheids were spectroscopic binaries, and toward the concept that they were pulsators. He was the first to realize that the

text: Milky Way Galaxy

text: was much larger than previously believed, and that the Sun's place in the galaxy was in a nondescript location. This discovery by Shapley is a part of the

text: Copernican principle

text: , according to which the Earth is not at the center of our Solar System, our galaxy, or our Universe.

text: Garthaan Saal contained the power of the entire Nova Corps within his body which increased him to the size of a giant and drove him mad. Supernova's desire for revenge against Nebula led him on a quest to track her down and exact his revenge. He had heard that Nebula had recently been a member of the Avengers (in actuality this was a temporal counterpart to Kang's long lost love Ravonna who assumed the guise of Nebula).

text: Garthaan Saal contained the power of the entire Nova Corps within his body which increased him to the size of a giant and drove him mad. Supernova's desire for revenge against Nebula led him on a quest to track her down and exact his revenge. He had heard that Nebula had recently been a member of the Avengers (in actuality this was a temporal counterpart to Kang's long lost love

text: Ravonna

text: who assumed the guise of Nebula).

text: In 2002 NASA began development of several spaceflight cold stowage systems to work in conjunction with the large (ISS Rack sized) ESA MELFI and Cryosystem freezers. One of these was for a system capable of rapidly freezing bagged irregularly shaped science samples to below -160ºC in as fast as 1ºC/min for a 100ml sample, being able to maintain a complement of frozen samples without electrical power for several hours, and to be of a compact double middeck locker format, to enable transfer between the ISS and the Space Shuttle Orbiter cabin for transport to/from orbit. The combination of these goals presented several significant technical challenges, and prompted NASA to implement a two-phase development approach. In the first phase, two competing designs were matured through Preliminary Design Review (PDR) and completed functional demonstration of key freezer components. In the second phase one of the designs was then developed through to the completed flight freezers. NASA awarded a contract to UAB CBSE to build the GLACIER freezer system in 2005. The first GLACIER freezers flew on STS-126 in 2008.

text: The Nice ()  model is a scenario for the dynamical evolution of the Solar System. It is named for the location of the Observatoire de la Côte d'Azur, where it was initially developed, in Nice, France. It proposes the migration of the giant planets from an initial compact configuration into their present positions, long after the dissipation of the initial protoplanetary gas disk. In this way, it differs from earlier models of the Solar System's formation. This planetary migration is used in dynamical simulations of the Solar System to explain historical events including the Late Heavy Bombardment of the inner Solar System, the formation of the Oort cloud, and the existence of populations of small Solar System bodies including the Kuiper belt, the Neptune and Jupiter trojans, and the numerous resonant trans-Neptunian objects dominated by Neptune. Its success at reproducing many of the observed features of the Solar System means that it is widely accepted as the current most realistic model of the Solar System's early evolution, although it is not universally favoured among planetary scientists. One of its limitations that it does not reproduce the outer-system satellites and the Kuiper belt (see below).

text: The Nice ()  model is a scenario for the

text: dynamical evolution

text: of the

text: Solar System

text: . It is named for the location of the

text: Observatoire de la Côte d'Azur

text: , where it was initially developed, in

text: Nice

text: , France. It proposes the

text: migration

text: of the

text: giant planet

text: s from an initial compact configuration into their present positions, long after the dissipation of the initial

text: protoplanetary gas disk

text: . In this way, it differs from

entity_name: History of Solar System formation and evolution hypotheses

text: earlier models

text: of the Solar System's formation. This planetary migration is used in

text: dynamical simulation

text: s of the Solar System to explain historical events including the

text: Late Heavy Bombardment

text: of the

text: inner Solar System

text: , the formation of the

text: Oort cloud

text: , and the existence of populations of

text: small Solar System bodies

text: including the

text: Kuiper belt

text: , the

text: Neptune

text: and

text: Jupiter

text: trojan

text: s, and the numerous

text: resonant trans-Neptunian object

text: s dominated by Neptune. Its success at reproducing many of the observed features of the Solar System means that it is widely accepted as the current most realistic model of the Solar System's early evolution, although it is not universally favoured among

text: planetary scientists

text: . One of its limitations that it does not reproduce the outer-system satellites and the Kuiper belt (see below).

text: The ISA and the Ministry of Science and Technology formed and operated the National Knowledge Center on Near Earth Objects at Tel-Aviv University in order to study minor bodies in the Solar System. The goal is to map the objects which pose a threat to earth and to find a solution to eliminate them.

text: The ISA and the Ministry of Science and Technology formed and operated the National Knowledge Center on Near Earth Objects at

text: Tel-Aviv University

text: in order to study minor bodies in the

text: Solar System

text: . The goal is to map the objects which pose a threat to earth and to find a solution to eliminate them.

text: According to the traditional, literal Mormon interpretation of the Book of Abraham, Kolob is an actual star or planet in this universe that is, or is near, the physical throne of God. According to Smith, this star was discovered by Methuselah and Abraham by looking through the Urim and Thummim, a set of seer stones bound into a pair of spectacles. LDS Church leader and historian B. H. Roberts (1857–1933) interpreted Smith's statements to mean that our solar system and its governing "planet" (the Sun) revolved around a star known as Kae-e-vanrash, which itself revolved with its own solar system around a star called Kli-flos-is-es or Hah-ko-kau-beam, which themselves revolve around Kolob, which he characterized as "the great centre of that part of the universe to which our planetary system belongs". Roberts was confident that this hierarchy of stars orbiting other stars would be confirmed by astronomers.

text: According to the traditional, literal Mormon interpretation of the Book of Abraham, Kolob is an actual star or planet in this universe that is, or is near, the physical throne of God. According to Smith, this star was discovered by

text: Methuselah

text: and

text: Abraham

text: by looking through the

text: Urim and Thummim

text: , a set of

text: seer stones

text: bound into a pair of spectacles. LDS Church leader and historian

text: B. H. Roberts

text: (1857–1933) interpreted Smith's statements to mean that our

text: solar system

text: and its governing "planet" (the Sun) revolved around a star known as Kae-e-vanrash, which itself revolved with its own solar system around a star called Kli-flos-is-es or Hah-ko-kau-beam, which themselves revolve around Kolob, which he characterized as "the great centre of that part of the universe to which our planetary system belongs". Roberts was confident that this hierarchy of stars orbiting other stars would be confirmed by astronomers.

text: Most of the major bodies of the Solar System orbit the Sun in nearly the same plane. This is likely due to the way in which the Solar System formed from a protoplanetary disk. Probably the closest current representation of the disk is known as the invariable plane of the Solar System. Earth's orbit, and hence, the ecliptic, is inclined a little more than 1° to the invariable plane, and the other major planets are also within about 6° of it. Because of this, most Solar System bodies appear very close to the ecliptic in the sky. The ecliptic is well defined by the motion of the Sun. The invariable plane is defined by the angular momentum of the entire Solar System, essentially the summation of all of the orbital motions and rotations of all the bodies of the system, a somewhat uncertain value that requires precise knowledge of every object in the system. For these reasons, the ecliptic is used as the reference plane of the Solar System out of convenience.

text: Most of the major bodies of the

text: Solar System

text: orbit the

text: Sun

text: in nearly the same plane. This is likely due to the way in which the Solar System formed from a

text: protoplanetary disk

text: . Probably the closest current representation of the disk is known as the

text: invariable plane

text: of the Solar System. Earth's orbit, and hence, the ecliptic, is inclined a little more than 1° to the invariable plane, and the other major planets are also within about 6° of it. Because of this, most Solar System bodies appear very close to the ecliptic in the sky. The ecliptic is well defined by the motion of the

text: Sun

text: . The invariable plane is defined by the

text: angular momentum

text: of the entire Solar System, essentially the

text: summation

text: of all of the

text: orbit

text: al motions and

text: rotations

text: of all the bodies of the system, a somewhat uncertain value that requires precise knowledge of every object in the system. For these reasons, the ecliptic is used as the reference plane of the Solar System out of convenience.

text: Planetary mass is a measure of the mass of a planet-like object. Within the Solar System, planets are usually measured in the astronomical system of units, where the unit of mass is the solar mass (), the mass of the Sun. In the study of extrasolar planets, the unit of measure is typically the mass of Jupiter () for large gas giant planets, and the mass of Earth () for smaller rocky terrestrial planets.

text: Planetary mass is a measure of the

text: mass

text: of a

text: planet

text: -like object. Within the

text: Solar System

text: , planets are usually measured in the

text: astronomical system of units

text: , where the unit of mass is the

text: solar mass

text: (), the mass of the

text: Sun

text: . In the study of

text: extrasolar planet

text: s, the unit of measure is typically the mass of

text: Jupiter

text: () for large

text: gas giant

text: planets, and the mass of

text: Earth

text: () for smaller rocky

text: terrestrial planet

text: s.

text: PSR B1257+12 A, alternatively designated PSR B1257+12 b, also named Draugr, is an extrasolar planet approximately 2,300 light-years away in the constellation of Virgo. The planet is the innermost object orbiting the pulsar PSR B1257+12, i.e. a pulsar planet in the dead stellar system. It is about twice as massive as the Moon, and is listed as the least massive planet known, including among the planets in the Solar System.

text: PSR B1257+12 A, alternatively designated PSR B1257+12 b, also named Draugr, is an

text: extrasolar planet

text: approximately 2,300

text: light-year

text: s away in the

text: constellation

text: of

text: Virgo

text: . The planet is the innermost object orbiting the

text: pulsar

text: PSR B1257+12

text: , i.e. a

text: pulsar planet

text: in the dead stellar system. It is about twice as massive as the

text: Moon

text: , and is listed as the

text: least massive planet

text: known, including among the planets in the

text: Solar System

text: The orbits of planets around the Sun do not really follow an identical ellipse each time, but actually trace out a flower-petal shape because the major axis of each planet's elliptical orbit also precesses within its orbital plane, partly in response to perturbations in the form of the changing gravitational forces exerted by other planets. This is called perihelion precession or apsidal precession.

text: The

text: orbit

text: s of planets around the

text: Sun

text: do not really follow an identical ellipse each time, but actually trace out a flower-petal shape because the major axis of each planet's elliptical orbit also precesses within its orbital plane, partly in response to perturbations in the form of the changing gravitational forces exerted by other planets. This is called

text: perihelion precession or apsidal precession

text: The minor planet's name "Dioretsa" is the word "asteroid" spelled backwards, and is the first numbered of currently more than 20 known minor planets with a retrograde motion in the Solar System. Naming citation was published on 1 May 2003 (M.P.C. 48396).

text: The minor planet's name "Dioretsa" is the word "

text: asteroid

text: " spelled backwards, and is the first numbered of currently more than 20 known

text: minor planets with a retrograde motion

text: in the Solar System. Naming citation was published on 1 May 2003 (

text: M.P.C.

text: In Galactic Attack, the player's job was to liberate the solar system from the dreaded Kazanta invaders by destroying the Kzanta's ships and bombarding the Kzanta's forces on the planets of the solar system and then beaming down armies to secure the planets. The game's framing uses the same loose Star Trek framing as Empire; the universe is two dimensional, with the user's starship placed in the center of their tactical screen. Ships have phasers which fire in a cone, with damage proportionate to distance, a limited number of torpedoes that can be in flight at any given time and which proceed in a straight line until they hit a target or time out, deflector shields, a range of warp speeds, and a limited energy supply that slowly automatically regenerates. Weapons were fired on compass bearings by typing in degree headings.

text: In Galactic Attack, the player's job was to liberate the solar system from the dreaded Kazanta invaders by destroying the Kzanta's ships and bombarding the Kzanta's forces on the planets of the solar system and then beaming down armies to secure the planets. The game's framing uses the same loose

text: Star Trek

text: framing as Empire; the universe is two dimensional, with the user's starship placed in the center of their tactical screen. Ships have phasers which fire in a cone, with damage proportionate to distance, a limited number of torpedoes that can be in flight at any given time and which proceed in a straight line until they hit a target or time out, deflector shields, a range of warp speeds, and a limited energy supply that slowly automatically regenerates. Weapons were fired on compass bearings by typing in degree headings.

text: Most of the planets discovered outside the Solar System are giant planets, because they are more easily detectable. But since 2005, hundreds of potentially terrestrial extrasolar planets have been found, with several being confirmed as terrestrial. Most of these are super-Earths, i.e. planets with masses between Earth's and Neptune's; super-Earths may be gas planets or terrestrial, depending on their mass and other parameters.

text: Most of the planets discovered outside the

text: Solar System

text: are

text: giant planet

text: s, because they are more easily detectable. But since 2005, hundreds of potentially terrestrial extrasolar planets have been found, with several being confirmed as terrestrial. Most of these are

text: super-Earth

text: s, i.e. planets with masses between Earth's and Neptune's; super-Earths may be

text: gas planet

text: s or terrestrial, depending on their mass and other parameters.

text: Originally, two spacecraft were to be built by NASA and ESA, as the International Solar Polar Mission.  One would be sent over Jupiter, then under the Sun.  The other would fly under Jupiter, then over the Sun.  This would provide simultaneous coverage.  Due to cutbacks, the US spacecraft was canceled in 1981.  One spacecraft was designed, and the project recast as Ulysses, due to the indirect and untried flight path.  NASA would provide the Radioisotope Thermoelectric Generator (RTG) and launch services, ESA would build the spacecraft assigned to Astrium GmbH, Friedrichshafen, Germany (formerly Dornier Systems). The instruments would be split into teams from universities and research institutes in Europe and the United States. This process provided the 10 instruments on board.

text: The first documented astrarium clock was completed in 1364 by Giovanni de' Dondi (1318–1388), a scholar and physician of the Middle Ages interested in astronomy and horology. The original clock, consisting of 107 wheels and pinions, was lost, perhaps during the sacking of Mantua in 1630, but de' Dondi left detailed descriptions which have survived, enabling the reconstruction of the clock. It displays the mean time, sidereal, or star, time and the motions of the sun, moon and the five then known planets Venus, Mars, Saturn, Mercury, and Jupiter. It was conceived according to a Ptolemaic conception of the solar system. De' Dondi was inspired by his father Jacopo who had designed the astronomical clock in the Piazzi dei Signori, Padua, in 1344 - one of the first of its type.

text: The first documented astrarium clock was completed in 1364 by

text: Giovanni de' Dondi

text: (1318–1388), a scholar and physician of the

text: Middle Ages

text: interested in astronomy and

text: horology

text: . The original clock, consisting of 107 wheels and

text: pinion

text: s, was lost, perhaps during the sacking of Mantua in 1630, but de' Dondi left detailed descriptions which have survived, enabling the reconstruction of the clock. It displays the mean time, sidereal, or star, time and the motions of the sun, moon and the five then known planets

text: Venus

text: Mars

text: Saturn

text: Mercury

text: , and

text: Jupiter

text: . It was conceived according to a

text: Ptolemaic

text: conception of the solar system. De' Dondi was inspired by his father

text: Jacopo

text: who had designed the

text: astronomical clock

text: in the Piazzi dei Signori, Padua, in 1344 - one of the first of its type.

text: JA Solar Holdings is a solar development company based in Shanghai. They design, develop, manufacture and sell solar cell and solar module products and are based in the People’s Republic of China. The Company is also engaged in the manufacturing and sales of monocrystalline and multicrystalline solar cells. It sells its products primarily through a team of sales and marketing personnel to solar module manufacturers, who assemble and integrate its solar cells into modules and systems that convert sunlight into electricity. It also manufactures a variety of standard and specialty solar modules. JA Solar Holdings also sells its products to customers in Germany, Sweden, Spain, South Korea, and the United States. The company was founded in 2005 and is based in Ningjin, in the People’s Republic of China. In December 2009 investors began to notice the growing market share of JA Solar which was fueled by a large subsidy from the Chinese Government.

text: JA Solar Holdings is a solar development company based in Shanghai. They design, develop, manufacture and sell

text: solar cell

text: and

text: solar module

text: products and are based in the

text: People’s Republic of China

text: . The Company is also engaged in the manufacturing and sales of monocrystalline and multicrystalline solar cells. It sells its products primarily through a team of sales and marketing personnel to

text: solar module

text: manufacturers, who assemble and integrate its solar cells into modules and systems that convert sunlight into electricity. It also manufactures a variety of standard and specialty solar modules. JA Solar Holdings also sells its products to customers in

text: Germany

text: Sweden

text: Spain

text: South Korea

text: , and the

text: United States

text: . The company was founded in 2005 and is based in

text: Ningjin

text: , in the People’s Republic of China. In December 2009 investors began to notice the growing market share of JA Solar which was fueled by a large subsidy from the Chinese Government.

text: A dish Stirling or dish engine system consists of a stand-alone parabolic reflector that concentrates light onto a receiver positioned at the reflector's focal point. The reflector tracks the Sun along two axes. The working fluid in the receiver is heated to  and then used by a Stirling engine to generate power. Parabolic-dish systems provide high solar-to-electric efficiency (between 31% and 32%), and their modular nature provides scalability. The Stirling Energy Systems (SES), United Sun Systems (USS) and Science Applications International Corporation (SAIC) dishes at UNLV, and Australian National University's Big Dish in Canberra, Australia are representative of this technology. A world record for solar to electric efficiency was set at 31.25% by SES dishes at the National Solar Thermal Test Facility (NSTTF) in New Mexico on January 31, 2008, a cold, bright day. According to its developer, Ripasso Energy, a Swedish firm, in 2015 its Dish Sterling system being tested in the Kalahari Desert in South Africa showed 34% efficiency. The SES installation in Maricopa, Phoenix was the largest Stirling Dish power installation in the world until it was sold to United Sun Systems. Subsequently, larger parts of the installation have been moved to China as part of the huge energy demand.

text: A dish Stirling or dish engine system consists of a stand-alone

text: parabolic reflector

text: that concentrates light onto a receiver positioned at the reflector's focal point. The reflector tracks the Sun along two axes. The working fluid in the receiver is heated to  and then used by a

text: Stirling engine

text: to generate power. Parabolic-dish systems provide high solar-to-electric efficiency (between 31% and 32%), and their modular nature provides scalability. The

text: Stirling Energy Systems

text: (SES),

text: United Sun Systems

text: (USS) and

entity_name: Science Applications International Corporation

text: Science Applications International Corporation (SAIC)

text: dishes at

text: UNLV

text: , and

text: Australian National University

text: 's

text: Big Dish

text: in

text: Canberra

text: , Australia are representative of this technology. A world record for solar to electric efficiency was set at 31.25% by SES dishes at the

text: National Solar Thermal Test Facility

text: (NSTTF) in New Mexico on January 31, 2008, a cold, bright day. According to its developer,

text: Ripasso Energy

text: , a Swedish firm, in 2015 its Dish Sterling system being tested in the

text: Kalahari Desert

text: in South Africa showed 34% efficiency. The SES installation in Maricopa, Phoenix was the largest Stirling Dish power installation in the world until it was sold to

text: United Sun Systems

text: . Subsequently, larger parts of the installation have been moved to China as part of the huge energy demand.

text: Solar System –  gravitationally bound system comprising the Sun and the objects that orbit it, either directly or indirectly. Of those objects that orbit the Sun directly, the largest eight are the planets (including Earth), with the remainder being significantly smaller objects, such as dwarf planets and small Solar System bodies. Of the objects that orbit the Sun indirectly, the moons, two are larger than the smallest planet, Mercury.

text: Solar System

text: –  gravitationally bound system comprising the Sun and the objects that orbit it, either directly or indirectly. Of those objects that orbit the Sun directly, the largest eight are the planets (including Earth), with the remainder being significantly smaller objects, such as dwarf planets and small Solar System bodies. Of the objects that orbit the Sun indirectly, the moons, two are larger than the smallest planet, Mercury.

text: A partial solar eclipse occurred on December 15, 1982. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: occurred on December 15, 1982. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: The Solar System has evolved considerably since its initial formation. Many moons have formed from circling discs of gas and dust around their parent planets, while other moons are thought to have formed independently and later been captured by their planets. Still others, such as Earth's Moon, may be the result of giant collisions. Collisions between bodies have occurred continually up to the present day and have been central to the evolution of the Solar System. The positions of the planets often shifted due to gravitational interactions. This planetary migration is now thought to have been responsible for much of the Solar System's early evolution.

text: The Solar System has

text: evolved

text: considerably since its initial formation. Many moons have formed from circling discs of gas and dust around their parent planets, while other moons are thought to have formed independently and later been captured by their planets. Still others, such as Earth's

text: Moon

text: , may be the result of

text: giant collisions

text: . Collisions between bodies have occurred continually up to the present day and have been central to the evolution of the Solar System. The positions of the planets often shifted due to gravitational interactions. This

text: planetary migration

text: is now thought to have been responsible for much of the Solar System's early evolution.

text: MTC is a proposed Mars analog to Universal Time (UT1) on Earth. It is defined as the mean solar time at Mars's prime meridian. The prime meridian was first proposed by German astronomers Wilhelm Beer and Johann Heinrich Mädler in 1830 as marked by the fork in the albedo feature later named Sinus Meridiani by Italian astronomer Giovanni Schiaparelli. This convention was readily adopted by the astronomical community, the result being that Mars had a universally accepted prime meridian half a century before the International Meridian Conference of 1880 established one for Earth. The definition of the Martian prime meridian has since been refined on the basis of spacecraft imagery as the center of the crater Airy-0 in Terra Meridiani. The name "MTC" is intended to parallel the Terran Coordinated Universal Time (UTC), but this is somewhat misleading: what distinguishes UTC from other forms of UT is its leap seconds, but MTC does not use any such scheme. MTC is more closely analogous to UT1.

text: MTC is a proposed Mars analog to Universal Time (

text: ) on Earth. It is defined as the mean solar time at Mars's prime meridian. The prime meridian was first proposed by German astronomers

text: Wilhelm Beer

text: and

text: Johann Heinrich Mädler

text: in 1830 as marked by the fork in the

text: albedo feature

text: later named

text: Sinus Meridiani

text: by Italian astronomer

text: Giovanni Schiaparelli

text: . This convention was readily adopted by the astronomical community, the result being that Mars had a universally accepted prime meridian half a century before the

text: International Meridian Conference

text: of 1880 established one for Earth. The definition of the Martian prime meridian has since been refined on the basis of spacecraft imagery as the center of the crater

text: in Terra Meridiani. The name "MTC" is intended to parallel the Terran

text: Coordinated Universal Time

text: (UTC), but this is somewhat misleading: what distinguishes UTC from other forms of UT is its

text: leap second

text: s, but MTC does not use any such scheme. MTC is more closely analogous to

text: There are no known lava worlds in the Solar System and the existence of extrasolar lava planets remains theoretical. Several known exoplanets are likely lava worlds, given their small enough masses, sizes and orbits. Likely lava exoplanets include COROT-7b, Kepler-10b, Alpha Centauri Bb, and Kepler-78b.

text: There are no known lava worlds in the

text: Solar System

text: and the existence of extrasolar lava planets remains theoretical. Several known exoplanets are likely lava worlds, given their small enough masses, sizes and orbits. Likely lava exoplanets include

text: Alpha Centauri Bb

text: , and

text: The Astronomia novas introduction, specifically the discussion of scripture, was the most widely distributed of Kepler’s works in the seventeenth century. The introduction outlines the four steps Kepler took during his research. The first is his claim that the sun itself and not any imaginary point near the sun (as in the Copernican system) is the point where all the planes of the eccentrics of the planets intersect, or the center of the orbits of the planets. The second step consists of Kepler placing the sun as the center and mover of the other planets. This step also contains Kepler’s reply to objections against placing the sun at the center of the universe, including objections based on scripture. In reply to scripture, he argues that it is not meant to claim physical dogma, and the content should be taken spiritually. In the third step, he posits that the sun is the source of the motion of all planets, using Brahe’s proof based on comets that planets do not rotate on orbs. The fourth step consists of describing the path of planets as not a circle, but an oval.

text: The Astronomia novas introduction, specifically the discussion of scripture, was the most widely distributed of Kepler’s works in the seventeenth century. The introduction outlines the four steps Kepler took during his research. The first is his claim that the sun itself and not any imaginary point near the sun (as in the

text: Copernican system

text: ) is the point where all the planes of the eccentrics of the planets intersect, or the center of the orbits of the planets. The second step consists of Kepler placing the sun as the center and mover of the other planets. This step also contains Kepler’s reply to objections against placing the sun at the center of the universe, including objections based on scripture. In reply to scripture, he argues that it is not meant to claim physical dogma, and the content should be taken spiritually. In the third step, he posits that the sun is the source of the motion of all planets, using Brahe’s proof based on comets that planets do not rotate on orbs. The fourth step consists of describing the path of planets as not a circle, but an oval.

text: Since the planets are very remote from each other, and since their mass is small as compared to the mass of the Sun, the gravitational forces between the planets can be neglected, and the planetary motion is considered, to a first approximation, as taking place along Kepler's orbits, which are defined by the equations of the two-body problem, the two bodies being the planet and the Sun.

text: Since the planets are very remote from each other, and since their mass is small as compared to the mass of the Sun, the gravitational forces between the planets can be neglected, and the planetary motion is considered, to a first approximation, as taking place along Kepler's orbits, which are defined by the equations of the

text: two-body problem

text: , the two bodies being the planet and the Sun.

text: The chemical composition of comets should reflect both the conditions in the outer solar nebula some 4.5 x 10 ayr, and the nature of the natal interstellar cloud from which the Solar system was formed. While comets retain a strong signature of their ultimate interstellar origins, significant processing must have occurred in the protosolar nebula. Early models of coma chemistry showed that reactions can occur rapidly in the inner coma, where the most important reactions are proton transfer reactions. Such reactions can potentially cycle deuterium between the different coma molecules, altering the initial D/H ratios released from the nuclear ice, and necessitating the construction of accurate models of cometary deuterium chemistry, so that gas-phase coma observations can be safely extrapolated to give nuclear D/H ratios.

text: The chemical composition of comets should reflect both the conditions in the outer solar nebula some 4.5 x 10 ayr, and the nature of the natal interstellar cloud from which the

text: Solar system

text: was formed. While comets retain a strong signature of their ultimate interstellar origins, significant processing must have occurred in the protosolar nebula. Early models of coma chemistry showed that reactions can occur rapidly in the inner coma, where the most important reactions are proton transfer reactions. Such reactions can potentially cycle deuterium between the different coma molecules, altering the initial D/H ratios released from the nuclear ice, and necessitating the construction of accurate models of cometary deuterium chemistry, so that gas-phase coma observations can be safely extrapolated to give nuclear D/H ratios.

text: However, the question of what makes a planet habitable is much more complex than havinga planet located at the right distance from its host star so that water can be liquidon its surface: various geophysical and geodynamical aspects, the radiation, and the host stars plasma environment can influence the evolution of planets and life, if it originated.

text: However, the question of what makes a planet habitable is much more complex than havinga planet located at the right distance from its host star so that water can be liquidon its surface: various

text: geophysical

text: and

text: geodynamical

text: plasma

text: The songs, art and lyrics of this album tell the story of the rise of the heliocentric world view - the idea that the earth revolves around the sun, and that the sun is stationary and at the center of the solar system. Nicolaus Copernicus and Galileo Galilei were the first popular ambassadors of this idea, although ancient Greek astronomers like Aristarchus had already posited this theory centuries before.

text: The songs, art and lyrics of this album tell the story of the rise of the heliocentric world view - the idea that the earth revolves around the sun, and that the sun is stationary and at the center of the solar system.

text: Nicolaus Copernicus

text: and

text: Galileo Galilei

text: were the first popular ambassadors of this idea, although ancient Greek astronomers like

text: Aristarchus

text: had already posited this theory centuries before.

text: Light-time correction can be applied to any object whose distance and motion are known. In particular, it is usually necessary to apply it to the motion of a planet or other Solar System object. For this reason, the combined displacement of the apparent position due to the effects of light-time correction and aberration is known as planetary aberration. By convention, light-time correction is not applied to the positions of stars, because their motion and distance may not be known accurately.

text: Light-time correction can be applied to any object whose distance and motion are known. In particular, it is usually necessary to apply it to the motion of a

text: planet

text: or other

text: Solar System

text: object. For this reason, the combined displacement of the apparent position due to the effects of light-time correction and aberration is known as planetary aberration. By convention, light-time correction is not applied to the positions of stars, because their

text: motion

text: and distance may not be known accurately.

text: Many scholastic commentators on Aristotle's On the Heavens and Sacrobosco's Treatise on the Sphere unanimously agreed that the earth is spherical or round. Grant observes that no author who had studied at a medieval university thought that the earth was flat.

text: Many

text: scholastic

text: commentators on Aristotle's

text: On the Heavens

text: and Sacrobosco's Treatise on the Sphere unanimously agreed that the earth is spherical or round. Grant observes that no author who had studied at a

text: medieval university

text: thought that the earth was flat.

text: This game takes place in a fictional solar system called the Lylat system, which is inhabited by humanlike animal races (e.g. foxes, frogs, dogs, birds, rabbits, apes). It contains the planets Corneria and Venom, representing good and evil, respectively. One can visit many other planets, asteroid belts, space stations, etc. while going through the course of the game. Which path the player chooses affects what places they will encounter.

text: The Exoplanet Data Explorer / Exoplanet Orbit Database lists extrasolar planets up to 24 Jupiter masses.

text: The Exoplanet Data Explorer / Exoplanet Orbit Database lists

text: extrasolar planets

text: up to 24 Jupiter masses.

text: G 99-47's mass is 0.71 ± 0.03 Solar masses; its surface gravity is 10 (1.58 · 10) cm·s, or approximately 162 000 of Earth's, corresponding to a radius 7711 km, or 121% of Earth's.

text: G 99-47's mass is 0.71 ± 0.03

text: Solar mass

text: es; its

text: surface gravity

text: is 10 (1.58 · 10) cm·s, or approximately 162 000 of

text: Earth's

text: , corresponding to a radius 7711 km, or 121% of

text: Earth's

text: The sense-reference distinction is commonly confused with that between connotation and denotation, which originates with Mill. According to Mill, a common term like 'white' denotes all white things, as snow, paper'.  But according to Frege, a common term does not refer to any individual white thing, but rather to an abstract Concept (Begriff).  We must distinguish between the relation of reference, which holds between a proper name and the object it refers to, such as between the name 'Earth', and the planet Earth, and the relation of 'falling under', such as when the Earth falls under the concept planet.  The relation of a proper name to the object it designates is direct, whereas a word like 'planet' has no such direct relation at all to the Earth at all, but only to a concept that the Earth falls under. Moreover, judging of anything that it falls under this concept is not in any way part of our knowledge of what the word 'planet' means. The distinction between connotation and denotation is closer to that between Concept and Object, than to that between 'sense' and 'reference'.

text: The sense-reference distinction is commonly confused with that between

text: connotation and denotation

text: , which originates with Mill. According to Mill, a common term like 'white' denotes all white things, as snow, paper'.  But according to Frege, a common term does not refer to any individual white thing, but rather to an abstract Concept (Begriff).  We must distinguish between the relation of reference, which holds between a proper name and the object it refers to, such as between the name 'Earth', and the planet Earth, and the relation of 'falling under', such as when the Earth falls under the concept planet.  The relation of a proper name to the object it designates is direct, whereas a word like 'planet' has no such direct relation at all to the Earth at all, but only to a concept that the Earth falls under. Moreover, judging of anything that it falls under this concept is not in any way part of our knowledge of what the word 'planet' means. The distinction between connotation and denotation is closer to that between Concept and Object, than to that between 'sense' and 'reference'.

text: Many Solar System objects are known to possess satellite systems, though their origin is still unclear.  Notable examples include the largest satellite system, the Jovian system, with 67 known moons (including the large Galilean moons)  and the Saturnian System with 62 known moons (and the most visible ring system in the Solar System).  Both satellite systems are large and diverse.  In fact all of the giant planets of the Solar System possess large satellite systems as well as planetary rings, and it is inferred that this is a general pattern.  Several objects farther from the Sun also have satellite systems consisting of multiple moons, including the complex Plutonian system where multiple objects orbit a common center of mass, as well as many asteroids and plutinos.  Apart from the Earth-Moon system and Mars' system of two tiny natural satellites, the other terrestrial planets are generally not considered satellite systems, although some have been orbited by artificial satellites originating from Earth.

text: Many Solar System objects are known to possess satellite systems, though their origin is still unclear.  Notable examples include the largest satellite system, the Jovian system, with

text: 67 known moons

text: (including the large

text: Galilean moons

text: )  and the Saturnian System with

text: 62 known moons

text: (and the most visible ring system in the Solar System).  Both satellite systems are large and diverse.  In fact all of the giant planets of the Solar System possess large satellite systems as well as planetary rings, and it is inferred that this is a general pattern.  Several objects farther from the Sun also have satellite systems consisting of multiple moons, including the complex Plutonian system where multiple objects orbit a common

text: center of mass

text: , as well as many asteroids and plutinos.  Apart from the Earth-Moon system and Mars' system of two tiny natural satellites, the other terrestrial planets are generally not considered satellite systems, although some have been orbited by artificial satellites originating from Earth.

text: Earth, along with the Solar System, is situated in the Milky Way and orbits about 28,000 light-years from its center. It is about 20 light-years above the galactic plane in the Orion Arm.

text: Earth, along with the Solar System, is situated in the

text: Milky Way

text: and orbits about 28,000

text: light-year

text: s from its center. It is about 20 light-years above the

text: galactic plane

text: in the

text: Orion Arm

text: There has been a debate if whether the siphon mechanism plays a role in blood circulation. However, in the 'closed loop' of circulation this was discounted; 'In contrast, in "closed" systems, like the circulation, gravity does not hinder uphill flow nor does it cause downhill flow, because gravity acts equally on the ascending and descending limbs of the circuit', but for 'historical reasons', the term is used. One hypothesis (in 1989) was that a siphon existed in the circulation of the giraffe. But further research, in 2004 found that, 'There is no hydrostatic gradient and since the "fall" of fluid does not assist the ascending arm, there is no siphon. The giraffe’s high arterial pressure, which is sufficient to raise the blood 2 m from heart to head with sufficient remaining pressure to perfuse the brain, supports this concept.' However, a paper written in 2005 urged more research on the hypothesis;

text: There has been a debate if whether the siphon mechanism plays a role in

text: blood

text: circulation

text: . However, in the 'closed loop' of circulation this was discounted; 'In contrast, in "closed" systems, like the circulation, gravity does not hinder uphill flow nor does it cause downhill flow, because gravity acts equally on the ascending and descending limbs of the circuit', but for 'historical reasons', the term is used. One hypothesis (in 1989) was that a siphon existed in the circulation of the

text: giraffe

text: . But further research, in 2004 found that, 'There is no hydrostatic gradient and since the "fall" of fluid does not assist the ascending arm, there is no siphon. The giraffe’s high arterial pressure, which is sufficient to raise the blood 2 m from heart to head with sufficient remaining pressure to perfuse the brain, supports this concept.' However, a paper written in 2005 urged more research on the hypothesis;

text: When ancient astronomers viewed the sky, they saw the Sun, Moon, and stars moving overhead in a regular fashion. They also saw the "wanderers" or "planetai" (our planets). The regularity in the motions of the wandering bodies suggested that their positions might be predictable.

text: When ancient astronomers viewed the sky, they saw the Sun, Moon, and stars moving overhead in a regular fashion. They also saw the "wanderers" or "planetai" (our

text: planet

text: s). The regularity in the motions of the wandering bodies suggested that their positions might be predictable.

text: The concept is applicable to other planets and celestial bodies. For locations in the solar system with weaker gravity than Earth's (such as the Moon or Mars), the strength-to-density requirements for tether materials are not as problematic. Currently available materials (such as Kevlar) are strong and light enough that they could be used as the tether material for elevators there.

text: The concept is applicable to other planets and

text: celestial bodies

text: . For locations in the solar system with weaker gravity than Earth's (such as the

text: Moon

text: or

text: Mars

text: ), the strength-to-density requirements for tether materials are not as problematic. Currently available materials (such as

text: Kevlar

text: ) are strong and light enough that they could be used as the tether material for elevators there.

text: The planets were originally thought to have formed in or near their current orbits. However, this view underwent radical change during the late 20th and early 21st centuries. Currently, it is thought that the Solar System looked very different after its initial formation: several objects at least as massive as Mercury were present in the inner Solar System, the outer Solar System was much more compact than it is now, and the Kuiper belt was much closer to the Sun.

text: The planets were originally thought to have formed in or near their current orbits. However, this view underwent radical change during the late 20th and early 21st centuries. Currently, it is thought that the Solar System looked very different after its initial formation: several objects at least as massive as Mercury were present in the inner Solar System, the outer Solar System was much more compact than it is now, and the

text: Kuiper belt

text: was much closer to the Sun.

text: The thinking that the heliocentric view was also not true in a strict sense was achieved in steps. That the Sun was not the center of the universe, but one of innumerable stars, was strongly advocated by the mystic Giordano Bruno. Over the course of the 18th and 19th centuries, the status of the Sun as merely one star among many became increasingly obvious.  By the 20th century, even before the discovery that there are many galaxies, it was no longer an issue.

text: The thinking that the heliocentric view was also not true in a strict sense was achieved in steps. That the Sun was not the center of the universe, but one of innumerable stars, was strongly advocated by the mystic

text: Giordano Bruno

text: . Over the course of the 18th and 19th centuries, the status of the Sun as merely one star among many became increasingly obvious.  By the 20th century, even before the discovery that there are many galaxies, it was no longer an issue.

text: HD 142022 is a binary star system located in the southernmost constellation of Octans located at a distance of 117 ly. The primary star (HD 142022 A) has a spectral type of G9V and has apparent magnitude of 7.69. Its mass is 1% less than the Sun but the radius is only 70.5%. The star is old, only 400 million years younger than the Universe itself. It is a Population I star with metallicity of 55% greater than solar.

text: HD 142022 is a

text: binary star system

text: located in the southernmost

text: constellation

text: of

text: Octans

text: located at a

text: distance

text: of 117

text: ly

text: . The primary star (HD 142022 A) has a

text: spectral type

text: of G9V and has

text: apparent magnitude

text: of 7.69. Its mass is 1% less than the

text: Sun

text: but the radius is only 70.5%. The star is old, only 400 million years younger than the

text: Universe

text: itself. It is a

text: Population I

text: star with metallicity of 55% greater than solar.

text: In 1616, the Roman Inquisition's consultants gave their assessment of the proposition that the sun is immobile and at the center of the universe and that the Earth moves around it, judging both to be "foolish and absurd in philosophy" and that the first was "formally heretical" while the second was "at least erroneous in faith".  (The original assessment document from the Inquisition was made widely available in 2014.)

text: In 1616, the Roman Inquisition's consultants gave their assessment of the proposition that the

text: sun

text: is immobile and

text: at the center of the universe

text: and that the

text: Earth

text: moves around it, judging both to be "foolish and absurd in philosophy" and that the first was "formally heretical" while the second was "at least erroneous in faith".  (The original assessment document from the Inquisition was made widely available in 2014.)

text: The Sun's motion about the centre of mass of the Solar System is complicated by perturbations from the planets. Every few hundred years this motion switches between prograde and retrograde.

text: The Sun's motion about the

text: centre of mass

text: of the Solar System is complicated by perturbations from the planets. Every few hundred years this motion switches between prograde and retrograde.

text: A planet is defined according to the 2006 International Astronomical Union (IAU) definition; as a body in orbit around the Sun that was large enough to have achieved hydrostatic equilibrium and to have cleared the neighbourhood around its orbit.  The practical meaning of "cleared the neighborhood" is that a planet is comparatively massive enough for its gravitation to control the orbits of all objects in its vicinity. By the IAU's definition, there are eight planets in the Solar System; four terrestrial planets (Mercury, Venus, Earth and Mars) and four giant planets, which can be divided further into two gas giants (Jupiter and Saturn) and two ice giants (Uranus and Neptune). When excluding the Sun, the four giant planets account for more than 99 percent of the mass of the Solar System.

text: A

text: planet

text: is defined according to the 2006

text: International Astronomical Union

text: (IAU) definition; as a body in orbit around the

text: Sun

text: that was large enough to have achieved

text: hydrostatic equilibrium

text: and to have

text: cleared the neighbourhood around its orbit

text: .  The practical meaning of "cleared the neighborhood" is that a planet is comparatively massive enough for its gravitation to control the orbits of all objects in its vicinity. By the IAU's definition, there are eight planets in the

text: Solar System

text: ; four

text: terrestrial planet

text: s (Mercury, Venus, Earth and Mars) and four

text: giant planet

text: s, which can be divided further into two

text: gas giant

text: s (Jupiter and Saturn) and two

text: ice giant

text: s (Uranus and Neptune). When excluding the Sun, the four giant planets account for more than 99 percent of the mass of the Solar System.

text: Gravity is most accurately described by the general theory of relativity (proposed by Albert Einstein in 1915) which describes gravity not as a force, but as a consequence of the curvature of spacetime caused by the uneven distribution of mass/energy. The most extreme example of this curvature of spacetime is a black hole, from which nothing can escape once past its event horizon, not even light. More gravity results in gravitational time dilation, where time lapses more slowly at a lower (stronger) gravitational potential. However, for most applications, gravity is well approximated by Newton's law of universal gravitation, which postulates that gravity causes a force where two bodies of mass are directly drawn (or 'attracted') to each other according to a mathematical relationship, where the attractive force is directly proportional to the product of their masses and inversely proportional to the square of the distance between them.

text: Gravity is most accurately described by the

text: general theory of relativity

text: (proposed by

text: Albert Einstein

text: in 1915) which describes gravity not as a

text: force

text: , but as a consequence of the curvature of

text: spacetime

text: caused by the uneven distribution of

text: mass

text: energy

text: . The most extreme example of this curvature of spacetime is a

text: black hole

text: , from which nothing can escape once past its event horizon, not even light. More gravity results in

text: gravitational time dilation

text: , where time lapses more slowly at a lower (stronger)

text: gravitational potential

text: . However, for most applications, gravity is well approximated by

text: Newton's law of universal gravitation

text: , which postulates that gravity causes a

text: force

text: where two bodies of mass are directly drawn (or 'attracted') to each other according to a mathematical relationship, where the attractive force is

text: directly proportional

text: to the product of their masses and

text: inversely proportional

text: to the

text: square

text: of the

text: distance

text: between them.

text: In summary, Earth’s climate is determined by a compilation of many things and factors. It can be somewhat easy to overlook the solar effects on Earth’s climate, however to overlook these would be a tragedy, seeing as how solar factors actually can have a huge impact and influence over Earth’s climate. These effects include effects from the primary factors of Earth’s axial tilt angle, Earth’s orbital eccentricity, and the precession of solstices and equinoxes, as well as some secondary, external effects, such as meteorite/asteroid impacts on the earth’s surface and solar activity from the sun, including sunspots, solar flares, and solar winds/geomagnetic storms. Overall, the Earth climate system is an amazingly, wonderfully complex design with many factors and components. Including things such as the ever so important solar effects on Earth’s climate, how those solar effects can affect mankind in everyday life, as well as how those effects can stretch their influence throughout the ages, even until the end of time.

text: The goal of the mission is to understand the formation of the Pluto system, the Kuiper belt, and the transformation of the early Solar System.  The spacecraft collected data on the atmospheres, surfaces, interiors and environments of Pluto and its moons. It will also study other objects in the Kuiper belt. "By way of comparison, New Horizons gathered 5,000 times as much data at Pluto as Mariner did at the Red Planet."

text: The goal of the mission is to understand the formation of the Pluto system, the Kuiper belt, and the transformation of the early Solar System.  The spacecraft collected data on the atmospheres, surfaces, interiors and environments of Pluto and its moons. It will also study other objects in the Kuiper belt. "By way of comparison, New Horizons gathered 5,000 times as much data at Pluto as

text: Mariner

text: did at the

text: Red Planet

text: In modern calculations the terms "geocentric" and "heliocentric" are often used to refer to reference frames.  In such systems the origin in the center of mass of the Earth, of the Earth–Moon system, of the Sun, of the Sun plus the major planets, or of the entire solar system can be selected; see center-of-mass frame. Right Ascension and Declination are examples of geocentric coordinates, used in Earth-based observations, while the heliocentric latitude and longitude are used for orbital calculations.  This leads to such terms as "heliocentric velocity" and "heliocentric angular momentum". In this heliocentric picture, any planet of the Solar System can be used as a source of mechanical energy because it moves relatively to the Sun. A smaller body (either artificial or natural) may gain heliocentric velocity due to gravity assist – this effect can change the body's mechanical energy in heliocentric reference frame (although it will not changed in the planetary one). However, such selection of "geocentric" or "heliocentric" frames is merely a matter of computation. It does not have philosophical implications and does not constitute a distinct physical or scientific model. From the point of view of General Relativity, inertial reference frames do not exist at all, and any practical reference frame is only an approximation to the actual space-time, which can have higher or lower precision.

text: In modern calculations the terms "geocentric" and "heliocentric" are often used to refer to

text: reference frames

text: .  In such systems the origin in the

text: center of mass

text: of the Earth, of the Earth–Moon system, of the Sun, of the Sun plus the major planets, or of the entire solar system can be selected; see

text: center-of-mass frame

text: Right Ascension

text: and

text: Declination

text: are examples of geocentric coordinates, used in Earth-based observations, while the heliocentric latitude and longitude are used for orbital calculations.  This leads to such terms as "heliocentric

text: velocity

text: " and "heliocentric

text: angular momentum

text: ". In this heliocentric picture, any

text: planet

text: of the Solar System can be used as a source of

text: mechanical energy

text: because it moves relatively to the Sun. A smaller

text: body

text: (either

text: artificial

text: or

text: natural

text: ) may gain heliocentric velocity due to

text: gravity assist

text: – this effect can change the body's mechanical energy in heliocentric reference frame (although it will not changed in the planetary one). However, such selection of "geocentric" or "heliocentric" frames is merely a matter of computation. It does not have philosophical implications and does not constitute a distinct physical or scientific

text: model

text: . From the point of view of

text: General Relativity

text: inertial reference frame

text: s do not exist at all, and any practical reference frame is only an approximation to the actual space-time, which can have higher or lower precision.

text: R Doradus (HD 29712 or P Doradus) is the name of a red giant Mira variable star in the far-southern constellation Dorado, although visually it appears more closely associated with the constellation Reticulum. Its distance from Earth is . Having a uniform disk diameter of  arcsec, it is currently believed to be the star with the largest apparent size as viewed from Earth (not counting the Sun). The estimated diameter of R Doradus is 515 ± 70 million km (3.46 AU) or  times the diameter of the Sun. If placed at the centre of the Solar System, the orbit of Mars and most of the main asteroid belt would be contained within the star.

text: R Doradus (HD 29712 or P Doradus) is the name of a

text: red giant

text: Mira variable

text: star

text: in the far-southern

text: constellation

text: Dorado

text: , although visually it appears more closely associated with the constellation

text: Reticulum

text: . Its distance from Earth is . Having a

text: uniform disk diameter

text: of

text: arcsec

text: , it is currently believed to be the star with the largest apparent size as viewed from Earth (not counting the

text: Sun

text: ). The estimated diameter of R Doradus is 515 ± 70 million km (3.46 AU) or  times the diameter of the

text: Sun

text: . If placed at the centre of the

text: Solar System

text: , the orbit of

text: Mars

text: and most of the main asteroid belt would be contained within the star.

text: The Solar System is stable in human terms, and far beyond, given that none of the planets will collide with each other or be ejected from the system in the next few billion years, and the Earth's orbit will be relatively stable.

text: The Solar System is stable in human terms, and far beyond, given that none of the planets will collide with each other or be ejected from the system in the next few billion years, and the

text: Earth's orbit

text: will be relatively stable.

text: Most giant planets (except Neptune) have retinues of moons, rings, ring shepherds, and moon Trojans analogous to mini-solar systems. These systems are postulated to have accreted from analogous gas clouds, and possibly with analogous migrations during their formation periods. The Cassini mission was defended on the grounds that Saturn system dynamics would contribute to studies of Solar System dynamics and formation.

text: Most giant planets (

text: except Neptune

text: ) have retinues of moons, rings, ring shepherds, and moon Trojans analogous to mini-solar systems. These systems are postulated to have accreted from analogous gas clouds, and possibly with analogous migrations during their formation periods. The Cassini mission was defended on the grounds that Saturn system dynamics would contribute to studies of Solar System dynamics and formation.

text: Possibilities of life in the Solar System are considered next, with emphasis on Mars, Titan, and outer moons harboring liquid water. Next is a summary of the rapidly changing state of play in the search for extrasolar planets or exoplanets. After centuries of speculation and decades of futile searching, planets around other stars were first discovered in 1995 and the number is now over 850, with several thousand more candidates from the Kepler mission. The book ends with the search for extraterrestrial intelligence (SETI) and the use of the Drake equation to frame discussions of cosmic companionship.

text: Possibilities of life in the

text: Solar System

text: are considered next, with emphasis on

text: Mars

text: Titan

text: , and outer

text: moons

text: harboring

text: liquid water

text: . Next is a summary of the rapidly changing state of play in the search for

text: extrasolar planets

text: or exoplanets. After centuries of speculation and decades of futile searching, planets around other stars were first discovered in 1995 and the number is now over 850, with several thousand more candidates from the

text: Kepler mission

text: . The book ends with the search for extraterrestrial intelligence (

text: SETI

text: ) and the use of the

text: Drake equation

text: to frame discussions of cosmic companionship.

text: The solar convection can supply the required heating, but in a way not yet known in detail. Actually, it is still unclear how this energy is transmitted from the chromosphere(where it could be absorbed or reflected), and then dissipated into the corona instead of dispersing into the solar wind.Furthermore, where does it occur exactly ? : in the low corona or mainly in the higher corona, where the magnetic field lines open into the space heliosphere, driving the solar wind into the solar system.

text: The solar convection can supply the required heating, but in a way not yet known in detail. Actually, it is still unclear how this energy is transmitted from the chromosphere(where it could be absorbed or reflected), and then dissipated into the corona instead of dispersing into the solar wind.Furthermore, where does it occur exactly ? : in the low

text: corona

text: or mainly in the higher corona, where the magnetic field lines open into the space

text: heliosphere

text: , driving the

text: solar wind

text: into the

text: solar system

text: The Quine-Duhem thesis argues that it's impossible to test a single hypothesis on its own, since each one comes as part of an environment of theories. Thus we can only say that the whole package of relevant theories has been collectively falsified, but cannot conclusively say which element of the package must be replaced. An example of this is given by the discovery of the planet Neptune: when the motion of Uranus was found not to match the predictions of Newton's laws, the theory "There are seven planets in the solar system" was rejected, and not Newton's laws themselves. Popper discussed this critique of naïve falsificationism in Chapters 3 and 4 of The Logic of Scientific Discovery. For Popper, theories are accepted or rejected via a sort of selection process. Theories that say more about the way things appear are to be preferred over those that do not; the more generally applicable a theory is, the greater its value. Thus Newton's laws, with their wide general application, are to be preferred over the much more specific "the solar system has seven planets".

text: The

text: Quine-Duhem thesis

text: argues that it's impossible to test a single hypothesis on its own, since each one comes as part of an environment of theories. Thus we can only say that the whole package of relevant theories has been collectively falsified, but cannot conclusively say which element of the package must be replaced. An example of this is given by the discovery of the planet

text: Neptune

text: : when the motion of

text: Uranus

text: was found not to match the predictions of Newton's laws, the theory "There are seven planets in the solar system" was rejected, and not Newton's laws themselves. Popper discussed this critique of

text: naïve falsificationism

text: in Chapters 3 and 4 of

text: The Logic of Scientific Discovery

text: . For Popper, theories are accepted or rejected via a sort of selection process. Theories that say more about the way things appear are to be preferred over those that do not; the more generally applicable a theory is, the greater its value. Thus Newton's laws, with their wide general application, are to be preferred over the much more specific "the solar system has seven planets".

text: In 1887,  Isaac Roberts took the first photographs of Andromeda, which was still commonly thought to be a nebula within our galaxy. Roberts actually mistook Andromeda and similar spiral nebulae as solar systems being formed. In 1912, Vesto Slipher used spectroscopy to measure the radial velocity of Andromeda with respect to our solar system—the largest velocity yet measured, at .

text: In 1887,

text: Isaac Roberts

text: took the first photographs of Andromeda, which was still commonly thought to be a nebula within our galaxy. Roberts actually mistook Andromeda and similar spiral nebulae as solar systems being formed. In 1912,

text: Vesto Slipher

text: used

text: spectroscopy

text: to measure the radial velocity of Andromeda with respect to our

text: solar system

text: —the largest velocity yet measured, at .

text: Most planets that have been discovered are within a couple of AU from their host star because the most used methods (radial-velocity and transit) require observation of several orbits to confirm that the planet exists and there has only been enough time since these methods were first used to cover small separations. Some planets with larger orbits have been discovered by direct imaging but there is a middle range of distances, roughly equivalent to the Solar System's gas giant region, which is largely unexplored. Direct imaging equipment for exploring that region was installed on two large telescopes that began operation in 2014, e.g. Gemini Planet Imager and VLT-SPHERE. The microlensing method has detected a few planets in the 1–10 AU range.It appears plausible that in most exoplanetary systems, there are one or two giant planets with orbits comparable in size to those of Jupiter and Saturn in the Solar System. Giant planets with substantially larger orbits are now known to be rare, at least around Sun-like stars.

text: Most planets that have been discovered are within a couple of AU from their host star because the most used methods (radial-velocity and transit) require observation of several orbits to confirm that the planet exists and there has only been enough time since these methods were first used to cover small separations. Some planets with larger orbits have been discovered by direct imaging but there is a middle range of distances, roughly equivalent to the Solar System's gas giant region, which is largely unexplored. Direct imaging equipment for exploring that region was installed on two large telescopes that began operation in 2014, e.g.

text: Gemini Planet Imager

text: and

entity_name: Spectro-Polarimetric High-Contrast Exoplanet Research

text: VLT-SPHERE

text: . The

text: microlensing

text: method has detected a few planets in the 1–10 AU range.It appears plausible that in most exoplanetary systems, there are one or two giant planets with orbits comparable in size to those of Jupiter and Saturn in the Solar System. Giant planets with substantially larger orbits are now known to be rare, at least around Sun-like stars.

text: The fourth episode begins at the Grand Canyon, Arizona, USA, where Cox draws comparisons of the canyon to Mars and the massive Valles Marineris. A trip to Kīlauea on Hawaii shows the constant geological activity of Earth, and again a comparison to Mars and the massive Olympus Mons is seen. Both comparisons are insightful in the sense that Earth's systems are still dynamic and active whereas Mars' have gradually slowed into inactivity. Cox then switches view closer to the sun and the scorched greenhouse planet Venus, a planet often referred to as "Earth's twin", and compares it to the vulcan geology of the Deccan Plateau. An example of Earth's interconnectivity with the solar system reveals that Jupiter's gravitational effect could potentially send an asteroid through the Asteroid Belt on a collision course with Earth, as evidenced by Meteor Crater. The same gravitational force is also shown to give the Jovian moon Io geological life (given the absence of meteor impact evidence there) as paralleled by the volcanism of Erta Ale in Ethiopia. All in all, with the universal laws of physics at play throughout the solar system, its interconnectedness can also be seen.

text: The fourth episode begins at the

text: Grand Canyon

text: , Arizona, USA, where Cox draws comparisons of the canyon to Mars and the massive

text: Valles Marineris

text: . A trip to

text: Kīlauea

text: on

text: Hawaii

text: shows the constant geological activity of Earth, and again a comparison to Mars and the massive

text: Olympus Mons

text: is seen. Both comparisons are insightful in the sense that Earth's systems are still dynamic and active whereas Mars' have gradually slowed into inactivity. Cox then switches view closer to the sun and the scorched greenhouse planet

text: Venus

text: , a planet often referred to as "Earth's twin", and compares it to the vulcan geology of the

text: Deccan Plateau

text: . An example of Earth's interconnectivity with the solar system reveals that Jupiter's gravitational effect could potentially send an asteroid through the

text: Asteroid Belt

text: on a collision course with Earth, as evidenced by

text: Meteor Crater

text: . The same gravitational force is also shown to give the Jovian moon

text: Io

text: geological life (given the absence of meteor impact evidence there) as paralleled by the volcanism of

text: Erta Ale

text: in Ethiopia. All in all, with the universal laws of physics at play throughout the solar system, its interconnectedness can also be seen.

text: Johannes Kepler published his first two laws about planetary motion in 1609, having found them by analyzing the astronomical observations of Tycho Brahe. Kepler's third law was published in 1619. The first law was "The orbit of every planet is an ellipse with the Sun at one of the two foci."

text: Johannes Kepler

text: published his first two laws about planetary motion in 1609, having found them by analyzing the astronomical observations of

text: Tycho Brahe

text: . Kepler's third law was published in 1619. The first law was "The

text: orbit

text: of every

text: planet

text: is an

text: ellipse

text: with the Sun at one of the two

text: foci

text: Since comets are thought to be ancient, and contain material unchanged since their formation in the early Solar System, these questions will directly help support theories on the Solar System formation. The Principal Investigator is Mark Bentley from The Space Research Institute (IWF) in Austria. The hardware is contributed by universities in Austria, the Netherlands and Germany.

text: Since comets are thought to be ancient, and contain material unchanged since their formation in the early Solar System, these questions will directly help support theories on the Solar System formation. The Principal Investigator is Mark Bentley from The Space Research Institute (

entity_name: Institut für Weltraumforschung (Space Research Institute)

text: IWF

text: ) in Austria. The hardware is contributed by universities in Austria, the Netherlands and Germany.

text: Stockholm Globe Arena represents the Sun in the Sweden Solar System.

text: Stockholm Globe Arena represents the

text: Sun

text: in the

text: Sweden Solar System

text: Scientific investigation has resulted in several culturally transformative shifts in our view of the planet. In the West, belief in a flat Earth was displaced by the idea of spherical Earth, credited to Pythagoras in the 6th century BC. Earth was further believed to be the center of the universe until the 16th century when scientists first theorized that it was a moving object, comparable to the other planets in the Solar System. Due to the efforts of influential Christian scholars and clerics such as James Ussher, who sought to determine the age of Earth through analysis of genealogies in Scripture, Westerners before the 19th century generally believed Earth to be a few thousand years old at most. It was only during the 19th century that geologists realized Earth's age was at least many millions of years. Lord Kelvin used thermodynamics to estimate the age of Earth to be between 20 million and 400 million years in 1864, sparking a vigorous debate on the subject; it was only when radioactivity and radioactive dating were discovered in the late 19th and early 20th centuries that a reliable mechanism for determining Earth's age was established, proving the planet to be billions of years old. The perception of Earth shifted again in the 20th century when humans first viewed it from orbit, and especially with photographs of Earth returned by the Apollo program.

text: Scientific investigation has resulted in several culturally transformative shifts in our view of the planet. In the West, belief in a

text: flat Earth

text: was displaced by the idea of

text: spherical Earth

text: , credited to

text: Pythagoras

text: in the 6th century BC. Earth was further believed to be

text: the center of the universe

text: until the 16th century when scientists first theorized that it was

text: a moving object

text: , comparable to the other planets in the Solar System. Due to the efforts of influential Christian scholars and clerics such as

text: James Ussher

text: , who sought to determine the age of Earth through analysis of genealogies in Scripture, Westerners before the 19th century generally believed Earth to be a few thousand years old at most. It was only during the 19th century that geologists realized

text: Earth's age

text: was at least many millions of years.

text: Lord Kelvin

text: used

text: thermodynamics

text: to estimate the age of Earth to be between 20 million and 400 million years in 1864, sparking a vigorous debate on the subject; it was only when radioactivity and

text: radioactive dating

text: were discovered in the late 19th and early 20th centuries that a reliable mechanism for determining Earth's age was established, proving the planet to be billions of years old. The perception of Earth shifted again in the 20th century when humans first viewed it from orbit, and especially with photographs of Earth returned by the

text: Apollo program

text: The abundance of the chemical elements on Earth varies from air to crust to ocean, and in various types of life. The abundance of elements in Earth's crust differs from that in the Solar system (as seen in the Sun and heavy planets like Jupiter) mainly in selective loss of the very lightest elements (hydrogen and helium) and also volatile neon, carbon (as hydrocarbons), nitrogen and sulfur, as a result of solar heating in the early formation of the solar system. Oxygen, the most abundant Earth element by mass, is retained on Earth by combination with silicon. Aluminum at 8% by mass is more common in the Earth's crust than in the universe and solar system, but the composition of the far more bulky mantle, which has magnesium and iron in place of aluminum (which occurs there only at 2% of mass) more closely mirrors the elemental composition of the solar system, save for the noted loss of volatile elements to space, and loss of iron which has migrated to the Earth's core.

text: The

text: abundance of the chemical elements

text: on Earth varies from air to crust to ocean, and in various types of life. The abundance of elements in Earth's crust differs from that in the Solar system (as seen in the Sun and heavy planets like Jupiter) mainly in selective loss of the very lightest elements (hydrogen and helium) and also volatile neon, carbon (as hydrocarbons), nitrogen and sulfur, as a result of solar heating in the early formation of the solar system. Oxygen, the most abundant Earth element by mass, is retained on Earth by combination with silicon. Aluminum at 8% by mass is more common in the Earth's crust than in the universe and solar system, but the composition of the far more bulky mantle, which has magnesium and iron in place of aluminum (which occurs there only at 2% of mass) more closely mirrors the elemental composition of the solar system, save for the noted loss of volatile elements to space, and loss of iron which has migrated to the Earth's core.

text: Gravity, or gravitation, is a natural phenomenon by which all things with mass are brought toward (or gravitate toward) one another, including planets, stars and galaxies. Since energy and mass are equivalent, all forms of energy, including light, also cause gravitation and are under the influence of it. On Earth, gravity gives weight to physical objects and causes the ocean tides.  The gravitational attraction of the original gaseous matter present in the Universe caused it to begin coalescing, forming stars — and the stars to group together into galaxies — so gravity is responsible for many of the large scale structures in the Universe.  Gravity has an infinite range, although its effects become increasingly weaker on farther objects.

text: Gravity, or gravitation, is a

text: natural phenomenon

text: by which all things with

text: mass

text: are brought toward (or gravitate toward) one another, including

text: planet

text: s,

text: star

text: s and

text: galaxies

text: . Since

text: energy and mass are equivalent

text: , all forms of

text: energy

text: , including

text: light

text: , also cause gravitation and are under the influence of it. On

text: Earth

text: , gravity gives

text: weight

text: to physical objects and causes the ocean

text: tides

text: .  The gravitational attraction of the original gaseous matter present in the

text: Universe

text: caused it to begin coalescing, forming

text: star

text: s — and the stars to group together into

text: galaxies

text: — so gravity is responsible for many of the large scale structures in the Universe.  Gravity has an infinite range, although its effects become increasingly weaker on farther objects.

text: Didier Queloz was a Ph.D. student at the University of Geneva when he and Michel Mayor, his doctoral advisor, discovered the first exoplanet around a main sequence star. Queloz performed an analysis on 51 Pegasi using radial velocity measurements (Doppler spectroscopy), and was astonished to find a planet with an orbital period of 4.2 days. He had been performing the analysis as an exercise to hone his skills. The planet, 51 Pegasi b, challenged the then accepted views of planetary formation, being a hot Jupiter or roaster.He has received the 2011 BBVA Foundation Frontiers of Knowledge Award of Basic Sciences (co-winner with Michel Mayor) for developing new astronomical instruments and experimental techniques that led to the first observation of planets outside the solar system.

text: Didier Queloz was a

text: Ph.D.

text: student at the

text: University of Geneva

text: when he and

text: Michel Mayor

text: , his doctoral advisor, discovered the first exoplanet around a

text: main sequence

text: star

text: . Queloz performed an analysis on

text: 51 Pegasi

text: using radial velocity measurements (

text: Doppler spectroscopy

text: ), and was astonished to find a planet with an orbital period of 4.2 days. He had been performing the analysis as an exercise to hone his skills. The planet,

text: 51 Pegasi b

text: , challenged the then accepted views of planetary formation, being a

text: hot Jupiter

text: or roaster.He has received the 2011

entity_name: BBVA Foundation Frontiers of Knowledge Award

text: BBVA Foundation Frontiers of Knowledge Award

text: of Basic Sciences (co-winner with

text: Michel Mayor

text: ) for developing new astronomical instruments and experimental techniques that led to the first observation of planets outside the solar system.

text: This phenomenon, known as Vainshtein screening, is at play not just in massive gravity, but also in related theories of modified gravity such as DGP and certain scalar-tensor theories, where it is crucial for hiding the effects of modified gravity in the solar system. This allows these theories to match terrestrial and solar-system tests of gravity as well as general relativity does, while maintaining large deviations at larger distances. In this way these theories can lead to cosmic acceleration and have observable imprints on the large-scale structure of the Universe without running afoul of other, much more stringent constraints from observations closer to home.

text: This phenomenon, known as Vainshtein screening, is at play not just in massive gravity, but also in related theories of modified gravity such as

text: DGP

text: and certain

text: scalar-tensor theories

text: , where it is crucial for hiding the effects of modified gravity in the solar system. This allows these theories to match

text: terrestrial and solar-system tests of gravity

text: as well as general relativity does, while maintaining large deviations at larger distances. In this way these theories can lead to cosmic acceleration and have observable imprints on the

text: large-scale structure of the Universe

text: without running afoul of other, much more stringent constraints from observations closer to home.

text: The hypothesis of comets made of anti-matter can be traced back to the 1940s, when physicist Vladimir Rojansky proposed, in his paper The Hypothesis of the Existence of Contraterrene Matter the possibility that some comets and meteoroids could be made from "contraterrene" matter (i.e. antimatter). Such objects, Rojanski stated, would (if they existed at all) have their origins outside the Solar System. He hypothesized that if there were an antimatter object in orbit in the Solar System, it would exhibit the behavior of comets observed in the 1940s: As its atoms annihilated with "terrene" matter from other bodies and solar wind, it would generate volatile compounds and undergo a change of composition to elements with lower atomic masses. From this basis he propounded the hypothesis that some objects that had been identified as comets may, in fact, be antimatter objects, suggesting, based upon calculations using the Stefan-Boltzmann law, that it would be possible to determine the existence of such objects within the Solar System by observing their temperatures. An antimatter body subjected to normal levels of meteoric bombardment (per 1940s figures), and absorbing half of the energy created by the annihilation of normal matter and antimatter, would have a temperature of  for bombardment figures calculated by Wylie or  for  calculations by Nininger. In the 1970s, when comet Kohoutek was observed, Rojanski again suggested hypothesis of anti-matter comets in a letter in Physical Review Letters, and suggested that gamma-ray observations be made of the comet to test this hypothesis.

text: The hypothesis of comets made of anti-matter can be traced back to the 1940s, when physicist

text: Vladimir Rojansky

text: proposed, in his paper The Hypothesis of the Existence of Contraterrene Matter the possibility that some comets and meteoroids could be made from "contraterrene" matter (i.e. antimatter). Such objects, Rojanski stated, would (if they existed at all) have their origins outside the Solar System. He hypothesized that if there were an antimatter object in orbit in the Solar System, it would exhibit the behavior of comets observed in the 1940s: As its atoms annihilated with "terrene" matter from other bodies and

text: solar wind

text: , it would generate volatile compounds and undergo a change of composition to elements with lower

text: atomic mass

text: es. From this basis he propounded the hypothesis that some objects that had been identified as comets may, in fact, be antimatter objects, suggesting, based upon calculations using the

text: Stefan-Boltzmann law

text: , that it would be possible to determine the existence of such objects within the Solar System by observing their temperatures. An antimatter body subjected to normal levels of meteoric bombardment (per 1940s figures), and absorbing half of the energy created by the annihilation of normal matter and antimatter, would have a temperature of  for bombardment figures calculated by Wylie or  for  calculations by Nininger. In the 1970s, when

text: comet Kohoutek

text: was observed, Rojanski again suggested hypothesis of anti-matter comets in a letter in

text: Physical Review Letters

text: , and suggested that

text: gamma-ray

text: observations be made of the comet to test this hypothesis.

text: Players can hide in nebulae to be undetectable on opponent players' radars.  The computer-controlled ships are also fooled by this.  The player in the nebula, however, has his own radar jammed, so they can not see what was approaching (if anything), and the nebulae does not stop lasers. Also when hiding, the player is not replenishing his dwindling energy stores.

text: Players can hide in nebulae to be undetectable on opponent players' radars.  The computer-controlled ships are also fooled by this.  The player in the nebula, however, has his own radar jammed, so they can not see what was approaching (if anything), and the nebulae does not stop

text: laser

text: s. Also when hiding, the player is not replenishing his dwindling energy stores.

text: In 2009, Erik Verlinde disclosed a conceptual model that describes gravity as an entropic force. On 6 January 2010 he published a preprint of a 29-page paper titled On the Origin of Gravity and the Laws of Newton. The paper was published in the Journal of High Energy Physics in April 2011. Reversing the logic of over 300 years, it argued (similar to Jacobson's result) that gravity is a consequence of the "information associated with the positions of material bodies". This model combines the thermodynamic approach to gravity with Gerard 't Hooft's holographic principle. It implies that gravity is not a fundamental interaction, but an emergent phenomenon which arises from the statistical behavior of microscopic degrees of freedom encoded on a holographic screen.  The paper drew a variety of responses from the scientific community. Andrew Strominger, a string theorist at Harvard said “Some people have said it can’t be right, others that it’s right and we already knew it — that it’s right and profound, right and trivial."

text: In 2009,

text: Erik Verlinde

text: disclosed a conceptual model that describes gravity as an entropic force. On 6 January 2010 he published a

text: preprint

text: of a 29-page paper titled On the Origin of Gravity and the Laws of Newton. The paper was published in the

text: Journal of High Energy Physics

text: in April 2011. Reversing the logic of over 300 years, it argued (similar to Jacobson's result) that gravity is a consequence of the "information associated with the positions of material bodies". This model combines the thermodynamic approach to gravity with

text: Gerard 't Hooft

text: 's

text: holographic principle

text: . It implies that gravity is not a

text: fundamental interaction

text: , but an

text: emergent phenomenon

text: which arises from the statistical behavior of microscopic

entity_name: Degrees of freedom (physics and chemistry)

text: degrees of freedom

text: encoded on a holographic screen.  The paper drew a variety of responses from the scientific community.

text: Andrew Strominger

text: , a string theorist at Harvard said “Some people have said it can’t be right, others that it’s right and we already knew it — that it’s right and profound, right and trivial."

text: Electron degeneracy pressure will halt the gravitational collapse of a star if its mass is below the Chandrasekhar limit (1.39 solar masses).  This is the pressure that prevents a white dwarf star from collapsing. A star exceeding this limit and without significant thermally generated pressure will continue to collapse to form either a neutron star or black hole, because the degeneracy pressure provided by the electrons is weaker than the inward pull of gravity.

text: Electron degeneracy pressure will halt the gravitational collapse of a star if its

text: mass

text: is below the

text: Chandrasekhar limit

text: solar masses

text: ).  This is the pressure that prevents a

text: white dwarf

text: star from collapsing. A star exceeding this limit and without significant thermally generated pressure will continue to collapse to form either a

text: neutron star

text: or

text: black hole

text: , because the degeneracy pressure provided by the electrons is weaker than the inward pull of

text: gravity

text: Different sets of elements are used for various astronomical bodies. The eccentricity, , and either the semi-major axis, , or the distance of periapsis, , are used to specify the shape and size of an orbit. The angle of the ascending node, , the inclination, , and the argument of periapsis, , or the longitude of periapsis, , specify the orientation of the orbit in its plane. Either the longitude at epoch, , the mean anomaly at epoch, , or the time of perihelion passage, , are used to specify a known point in the orbit. The choices made depend whether the vernal equinox or the node are used as the primary reference. The semi-major axis is known if the mean motion and the gravitational mass are known.

text: Different sets of elements are used for various astronomical bodies. The eccentricity, , and either the semi-major axis, , or the distance of periapsis, , are used to specify the shape and size of an orbit. The angle of the ascending node, , the inclination, , and the argument of periapsis, , or the longitude of periapsis, , specify the orientation of the orbit in its plane. Either the longitude at epoch, , the mean anomaly at epoch, , or the time of perihelion passage, , are used to specify a known point in the orbit. The choices made depend whether the vernal equinox or the node are used as the primary reference. The semi-major axis is known if the mean motion and the

text: gravitational mass

text: are known.

text: The crater record on the Moon and on the terrestrial planets is part of the main evidence for the Late Heavy Bombardment (LHB): an intensification in the number of impactors, at about 600 million years after the Solar System's formation. In the initial Nice model icy planetesimals are scattered onto planet-crossing orbits when the outer disc is disrupted by Uranus and Neptune causing a sharp spike of impacts by icy objects. The migration of outer planets also causes mean-motion and secular resonances to sweep through the inner Solar System. In the asteroid belt these excite the eccentricities of the asteroids driving them onto orbits that intersect those of the terrestrial planets causing a more extended period of impacts by stony objects and removing roughly 90% of its mass.

text: The crater record on the

text: Moon

text: and on the terrestrial planets is part of the main evidence for the Late Heavy Bombardment (LHB): an intensification in the number of impactors, at about 600 million years after the Solar System's formation. In the initial Nice model icy planetesimals are scattered onto planet-crossing orbits when the outer disc is disrupted by Uranus and Neptune causing a sharp spike of impacts by icy objects. The migration of outer planets also causes mean-motion and secular resonances to sweep through the inner Solar System. In the asteroid belt these excite the eccentricities of the asteroids driving them onto orbits that intersect those of the terrestrial planets causing a more extended period of impacts by stony objects and removing roughly 90% of its mass.

text: -Tauri and Herbig Ae/Be stars suggest massive dust disks consisting of millimeter-sized grains, which disappear after several million years (e.g.,). A lot of work on detecting water ices in the Universe was done on the Infrared Space Observatory (ISO). For instance, broad emission bands of water ice at 43 and 60 μm were found in the disk of the isolated Herbig Ae/Be star HD 100546 in Musca. The one at 43 μm is much weaker than the one at 60 μm, which means the water ice, is located in the outer parts of the disk at temperatures below 50 K. There is also another broad ice feature between 87 and 90 μm, which is very similar to the one in NGC 6302  (the Bug or Butterfly nebula in Scorpius). Crystalline ices were also detected in the proto-planetary disks of ε-Eridani and the isolated Fe star HD 142527 in Lupus. 90% of the ice in the latter was found crystalline at temperature around 50 K. HST demonstrated that relatively old circumstellar disks, as the one around the 5-million-year-old B9.5Ve Herbig Ae/Be star HD 141569A, are dusty. Li & Lunine found water ice there. Knowing the ices usually exist at the outer parts of the proto-planetary nebulae, Hersant et al. proposed an interpretation of the volatile enrichment, observed in the four giant planets of the Solar System, with respect to the Solar abundances. They assumed the volatiles had been trapped in the form of hydrates and incorporated in the planetesimals flying in the protoplanets’ feeding zones.

text: -Tauri

text: and

text: Herbig Ae/Be stars

text: suggest massive dust disks consisting of millimeter-sized grains, which disappear after several million years (e.g.,). A lot of work on detecting water ices in the Universe was done on the

text: Infrared Space Observatory

text: (ISO). For instance, broad

text: emission bands

text: of water ice at 43 and 60 μm were found in the disk of the isolated

text: Herbig Ae/Be star

text: HD 100546 in

text: Musca

text: . The one at 43 μm is much weaker than the one at 60 μm, which means the water ice, is located in the outer parts of the disk at temperatures below 50 K. There is also another broad ice feature between 87 and 90 μm, which is very similar to the one in

text: NGC 6302

text: (the Bug or Butterfly nebula in

text: Scorpius

text: ). Crystalline ices were also detected in the proto-planetary disks of

text: ε-Eridani

text: and the isolated Fe star HD 142527 in

text: Lupus

text: . 90% of the ice in the latter was found crystalline at temperature around 50 K.

text: HST

text: demonstrated that relatively old

text: circumstellar disks

text: , as the one around the 5-million-year-old B9.5Ve

text: Herbig Ae/Be star

text: HD 141569A, are dusty. Li & Lunine found water ice there. Knowing the ices usually exist at the outer parts of the

text: proto-planetary nebulae

text: , Hersant et al. proposed an interpretation of the

text: volatile

text: enrichment, observed in the four

text: giant planets

text: of the

text: Solar System

text: , with respect to the Solar

text: abundances

text: . They assumed the

text: volatiles

text: had been trapped in the form of hydrates and incorporated in the

text: planetesimal

text: s flying in the

text: protoplanets’

text: feeding zones.

text: The table below lists Solar System bodies once considered to be planets.

text: The table below lists

text: Solar System

text: bodies once considered to be planets.

text: Built originally in 1994 as the private residence and special project of Rolf Disch, the Heliotrope is a one-of-a-kind design.  The Heliotrope in Freiburg was the first building in the world to create more energy than it uses, of which is entirely renewable, emissions free and CO neutral.  The structure physically rotates to track the sun, which allows it to harness the maximum natural sunlight and warmth possible from the sun.  Several different energy generation modules are used in the building including a  dual-axis solar photovoltaic tracking panel, a geothermal heat exchanger, a combined heat and power unit (CHP) and solar-thermal balcony railing to provide heat and warm water.  These innovations in combination with the superior insulation of the residence allow the Heliotrope to produce anywhere between four and six times its energy usage depending on the time of year.  The Heliotrope is also fitted with a grey-water cleansing system and built-in natural waste composting.After the success of Freiburg’s Heliotrope, Hansgrohe contracted Rolf Disch Solar Architecture to design and built another Heliotrope to be used as a visitor’s center and showroom in Offenburg, Germany.  A third Heliotrope was then contracted and built in Hilpoltstein, Bavaria to be used as a technical dental laboratory. Disch’s unique design accommodates different utilization from private residences to laboratories, all the while maintaining the structure’s positive energy balance.In addition to the original Heliotrope design, Rolf Disch Solar Architecture has drawn plans for larger versions of the project to be built as rotating hotels, which give every guest a beautiful view, as well as administrative buildings and even an exhibition pavilion for the EXPO 2010 in Shanghai.

text: Built originally in 1994 as the private residence and special project of Rolf Disch, the

text: Heliotrope

text: is a one-of-a-kind design.  The Heliotrope in Freiburg was the first building in the world to create more energy than it uses, of which is entirely renewable, emissions free and CO neutral.  The structure physically rotates to track the sun, which allows it to harness the maximum natural sunlight and warmth possible from the sun.  Several different energy generation modules are used in the building including a

text: dual-axis solar photovoltaic tracking panel

text: , a

text: geothermal heat exchanger

text: , a

text: combined heat and power unit (CHP)

text: and

text: solar-thermal

text: balcony railing to provide heat and warm water.  These innovations in combination with the superior insulation of the residence allow the Heliotrope to produce anywhere between four and six times its energy usage depending on the time of year.  The Heliotrope is also fitted with a

text: grey-water cleansing system

text: and built-in natural waste composting.After the success of Freiburg’s Heliotrope,

text: Hansgrohe

text: contracted Rolf Disch Solar Architecture to design and built another Heliotrope to be used as a visitor’s center and showroom in

text: Offenburg

text: Germany

text: .  A third Heliotrope was then contracted and built in

text: Hilpoltstein

text: Bavaria

text: to be used as a technical dental laboratory. Disch’s unique design accommodates different utilization from private residences to laboratories, all the while maintaining the structure’s positive energy balance.In addition to the original Heliotrope design, Rolf Disch Solar Architecture has drawn plans for larger versions of the project to be built as rotating hotels, which give every guest a beautiful view, as well as administrative buildings and even an exhibition pavilion for the

text: EXPO 2010

text: in

text: Shanghai

text: In January 2016, the existence of a hypothetical super-Earth sized ninth planet in the solar system, referred to as Planet Nine, was proposed as an explanation for the orbital behavior of six trans-Neptunian objects.

text: In January 2016, the existence of a hypothetical super-Earth sized ninth planet in the solar system, referred to as

text: Planet Nine

text: , was proposed as an explanation for the orbital behavior of six

text: trans-Neptunian object

text: s.

text: Apart from drastically adding to the number of known Solar System objects, Pan-STARRS will remove or mitigate the observational bias inherent in many current surveys. For instance, among currently known objects there is a bias favoring low orbital inclination, and thus an object such as  escaped detection until recently despite its bright apparent magnitude of 17, which is not much fainter than Pluto. Also, among currently known comets, there is a bias favoring those with short perihelion distances. Reducing the effects of this observational bias will enable a more complete picture of Solar System dynamics. For instance, it is expected that the number of Jupiter trojans larger than 1 km may in fact roughly match the number of asteroid-belt objects, although the currently known population of the latter is several orders of magnitude larger. Pan-STARRS data will elegantly complement the WISE (infrared) survey. WISE infrared images will permit an estimate of size for asteroids and trojan objects tracked over longer periods of time by Pan-STARRS.

text: Apart from drastically adding to the number of known Solar System objects, Pan-STARRS will remove or mitigate the observational bias inherent in many current surveys. For instance, among currently known objects there is a bias favoring low orbital

text: inclination

text: , and thus an object such as  escaped detection until recently despite its bright apparent magnitude of 17, which is not much fainter than

text: Pluto

text: . Also, among currently known comets, there is a bias favoring those with short

text: perihelion

text: distances. Reducing the effects of this observational bias will enable a more complete picture of Solar System dynamics. For instance, it is expected that the number of Jupiter trojans larger than 1 km may in fact roughly match the number of asteroid-belt objects, although the currently known population of the latter is several orders of magnitude larger. Pan-STARRS data will elegantly complement the WISE (infrared) survey. WISE infrared images will permit an estimate of size for asteroids and trojan objects tracked over longer periods of time by Pan-STARRS.

text: Department of Terrestrial Magnetism, Washington, D.C.The Department of Terrestrial Magnetism was founded in 1904 to map the geomagnetic field of the Earth. A crucial part of this mission included the use of two ships. The Galilee (ship) was chartered in 1905, but when it proved unsuitable for carrying out magnetic observations, a nonmagnetic ship was specially commissioned. The Carnegie (ship) was built in 1909 and completed seven cruises to measure the Earth's magnetic field before it suffered an explosion and burned.  Its captain was J. P. Ault. Over the years the research direction of the department shifted, but the historic goal—to understand the Earth and its place in the universe—has remained the same. Today the department is home to an interdisciplinary team of astronomers and astrophysicists, geophysicists and geochemists, cosmochemists and planetary scientists. These Carnegie researchers are discovering planets outside the Solar System, determining the age and structure of the universe, and studying the causes of earthquakes and volcanoes. With colleagues from the Geophysical Laboratory, these investigators are also helping to define the new and exciting field of astrobiology. The department supports a number of interdisciplinary areas of research. Astronomy and Astrophysics at DTM uses pioneering detection methods to discover and understand planets outside the Solar system. By observing and modeling other planetary systems, researchers are able to apply those implications to our own system. The Geophysics group at DTM studies earthquakes and volcanoes and the Earth’s structures and processes that produce them. Cosmochemists study the origins of the Solar system, the early evolution of meteorites and the nature of the impact process on Earth. Astrobiological research focuses on life’s origins and chemical and physical evolution from the interstellar medium through planetary formation.

text: Department of Terrestrial Magnetism, Washington, D.C.The Department of Terrestrial Magnetism was founded in 1904 to map the geomagnetic field of the Earth. A crucial part of this mission included the use of two ships. The

text: Galilee (ship)

text: was chartered in 1905, but when it proved unsuitable for carrying out magnetic observations, a nonmagnetic ship was specially commissioned. The

text: Carnegie (ship)

text: was built in 1909 and completed seven cruises to measure the Earth's magnetic field before it suffered an explosion and burned.  Its captain was J. P. Ault. Over the years the research direction of the department shifted, but the historic goal—to understand the Earth and its place in the universe—has remained the same. Today the department is home to an interdisciplinary team of astronomers and astrophysicists, geophysicists and geochemists, cosmochemists and planetary scientists. These Carnegie researchers are discovering planets outside the Solar System, determining the age and structure of the universe, and studying the causes of earthquakes and volcanoes. With colleagues from the Geophysical Laboratory, these investigators are also helping to define the new and exciting field of

text: astrobiology

text: . The department supports a number of interdisciplinary areas of research. Astronomy and Astrophysics at DTM uses pioneering detection methods to discover and understand planets outside the Solar system. By observing and modeling other planetary systems, researchers are able to apply those implications to our own system. The Geophysics group at DTM studies earthquakes and volcanoes and the Earth’s structures and processes that produce them. Cosmochemists study the origins of the Solar system, the early evolution of meteorites and the nature of the impact process on Earth. Astrobiological research focuses on life’s origins and chemical and physical evolution from the interstellar medium through planetary formation.

text: The following works or series use multiple planets and other locations within the Solar System as their primary settings:

text: Earth's orbit around the Sun is an ellipse. The semi-major axis of this ellipse is defined to be half of the straight line segment that joins the aphelion and perihelion. The centre of the sun lies on this straight line segment, but not at its midpoint. Because ellipses are well-understood shapes, measuring the points of its extremes defined the exact shape mathematically, and made possible calculations for the entire orbit as well as predictions based on observation. In addition, it mapped out exactly the largest straight-line distance that Earth traverses over the course of a year, defining times and places for observing the largest parallax (apparent shifts of position) in nearby stars. Knowing Earth's shift and a star's shift enabled the star's distance to be calculated. But all measurements are subject to some degree of error or uncertainty, and the uncertainties in the length of the astronomical unit only increased uncertainties in the stellar distances. Improvements in precision have always been a key to improving astronomical understanding. Throughout the twentieth century, measurements became increasingly precise and sophisticated, and ever more dependent on accurate observation of the effects described by Einstein's theory of relativity and upon the mathematical tools it used.

text: Earth's orbit around the Sun is an

text: ellipse

text: . The

text: semi-major axis

text: of this ellipse is defined to be half of the straight line segment that joins the aphelion and perihelion. The centre of the sun lies on this straight line segment, but not at its midpoint. Because ellipses are well-understood shapes, measuring the points of its extremes defined the exact shape mathematically, and made possible calculations for the entire orbit as well as predictions based on observation. In addition, it mapped out exactly the largest straight-line distance that Earth traverses over the course of a year, defining times and places for observing the largest

text: parallax

text: (apparent shifts of position) in nearby stars. Knowing Earth's shift and a star's shift enabled the star's distance to be calculated. But all measurements are subject to some degree of error or uncertainty, and the uncertainties in the length of the astronomical unit only increased uncertainties in the stellar distances. Improvements in precision have always been a key to improving astronomical understanding. Throughout the twentieth century, measurements became increasingly precise and sophisticated, and ever more dependent on accurate observation of the effects described by

text: Einstein's

text: theory of relativity

text: and upon the mathematical tools it used.

text: The solar system presented in Orbiter consists of the Sun, the eight planets and their major moons. Many dwarf planets, asteroids, and comets not included in the simulator are available as add-ons. Although Orbiter contains a database of over 100,000 stars, these are for display purposes only and interstellar travel is currently not possible in the simulator. The simulator also includes a planetarium mode that allows ecliptic and celestial grids to be overlaid onto the star map, along with labels of the constellations and other celestial markers. The planetarium mode can also display labels indicating the location and identity of objects in the solar system, such as planets, moons, or vessels, that appear within a certain proximity based on their type. This mode can also display labels on the celestial bodies in the solar system at certain coordinates on their surface for indicating cities, historical markers, geological formations, and other interesting sites.

text: The solar system presented in Orbiter consists of the

text: Sun

text: , the eight

text: planet

text: s and their major

text: moons

text: . Many

text: dwarf planet

text: s,

text: asteroid

text: s, and

text: comet

text: s not included in the simulator are available as add-ons. Although Orbiter contains a database of over 100,000 stars, these are for display purposes only and

text: interstellar travel

text: is currently not possible in the simulator. The simulator also includes a planetarium mode that allows

text: ecliptic

text: and

text: celestial

text: grids to be overlaid onto the star map, along with labels of the

text: constellation

text: s and other celestial markers. The planetarium mode can also display labels indicating the location and identity of objects in the solar system, such as planets, moons, or vessels, that appear within a certain proximity based on their type. This mode can also display labels on the celestial bodies in the solar system at certain coordinates on their surface for indicating cities, historical markers, geological formations, and other interesting sites.

text: In 1992, Aleksander Wolszczan discovered the first extrasolar planets around PSR B1257+12. This discovery presented important evidence concerning the widespread existence of planets outside the Solar System, although it is very unlikely that any life form could survive in the environment of intense radiation near a pulsar.

text: In 1992,

text: Aleksander Wolszczan

text: discovered the first

text: extrasolar planet

text: s around

text: PSR B1257+12

text: . This discovery presented important evidence concerning the widespread existence of planets outside the

text: Solar System

text: , although it is very unlikely that any

text: life form

text: could survive in the environment of intense radiation near a pulsar.

text: Another solar project in Adelaide is the  Adelaide Solar City Programme, which plans a 50 KW rooftop solar photovoltaic system. The installation will comprise 288 solar panels. This system will be installed on the roof of a historical market building which according to Dario De Bortoli, Adelaide Solar City Program Manager, is a proof of the fact that solar power systems can be installed even in historical buildings without much renovation.

text: Another solar project in Adelaide is the

text: Adelaide Solar City Programme

text: , which plans a 50 KW rooftop solar

text: photovoltaic

text: system. The installation will comprise 288 solar panels. This system will be installed on the roof of a historical market building which according to Dario De Bortoli, Adelaide Solar City Program Manager, is a proof of the fact that solar power systems can be installed even in historical buildings without much renovation.

text: No name is ever established for the mysterious planet, but the inhabitants seem to know of Earth, Venus and Mars, referring to them by name in one episode. Exactly where the planet is located is also never made clear. In the episode On a Clear Night You Can See Earth, Captain Steve Burton (Gary Conway) claims to have seen Earth through a set of infrared goggles invented by the giants, implying that the two planets are indeed separate worlds, but near enough to be able to see one from the other. The only established method by which Earth people may reach the giants planet is some sort of high-altitude flight, passing through what one giant calls a "dimension lock" (a term whose meaning is obscure).

text: Available evidence indicates that both bodies formed very early in the history of the Solar System, thereby retaining a record of events and processes from the time of the formation of the terrestrial planets. Radionuclide dating of pieces of meteorites thought to come from Vesta suggests that Vesta differentiated quickly, in three million years or less. Thermal evolution studies suggest that Ceres must have formed some time later, more than three million years after the formation of CAIs (the oldest known objects of Solar System origin).

text: Available evidence indicates that both bodies formed very early in the history of the Solar System, thereby retaining a record of events and processes from the time of the formation of the terrestrial planets.

text: Radionuclide

text: dating of pieces of meteorites thought to come from Vesta suggests that Vesta differentiated quickly, in three million years or less. Thermal evolution studies suggest that Ceres must have formed some time later, more than three million years after the formation of

text: CAI

text: s (the oldest known objects of Solar System origin).

text: Rogue planets in fiction usually originate outside the solar system, but their erratic paths lead them to within detectable range of Earth.  In reality, no rogue planet has ever been detected transiting the Solar System.

text: HD 11964 c is an extrasolar planet approximately 107 light-years away in the constellation of Cetus.  The planet was discovered in a close-orbit around the yellow subgiant star HD 11964.  The planet has a minimum mass 35 times the mass of Earth and is located in a mildly eccentric orbit which takes almost 38 days to complete. HD 11964 c was a possible planet discovered on the same day as HD 11964 b in 2005. HD 11964 c was first proposed in a paper published in 2007, and finally confirmed with new data presented in a review of multi-planet systems which appeared on the arXiv preprint website in 2008.

text: HD 11964 c is an

text: extrasolar planet

text: approximately 107

text: light-year

text: s away in the

text: constellation

text: of

text: Cetus

text: .  The planet was discovered in a close-orbit around the

text: yellow subgiant

text: star

text: HD 11964

text: .  The planet has a

text: minimum mass

text: 35 times the mass of

text: Earth

text: and is located in a mildly eccentric orbit which takes almost 38

text: day

text: s to complete. HD 11964 c was a possible planet discovered on the same day as

text: HD 11964 b

text: in 2005. HD 11964 c was first proposed in a paper published in 2007, and finally confirmed with new data presented in a review of multi-planet systems which appeared on the

text: arXiv

text: preprint

text: website in 2008.

text: The interplanetary magnetic field (IMF) is the solar magnetic field carried by the solar wind among the planets of the Solar System.

text: The interplanetary magnetic field (IMF) is the

text: solar magnetic field

text: carried by the

text: solar wind

text: among the

text: planet

text: s of the

text: Solar System

text: Because of the limited techniques currently available to detect exoplanets, many of those found to date have been of a size associated, in the Solar System, with giant planets. Because these large planets are inferred to share more in common with Jupiter than with the other giant planets, some have claimed that "jovian planet" is a more accurate term for them. Many of the exoplanets are much closer to their parent stars and hence much hotter than the giant planets in the Solar System, making it possible that some of those planets are a type not observed in the Solar System. Considering the relative abundances of the elements in the universe (approximately 98% hydrogen and helium) it would be surprising to find a predominantly rocky planet more massive than Jupiter. On the other hand, models of planetary-system formation have suggested that giant planets would be inhibited from forming as close to their stars as many of the extrasolar giant planets have been observed to orbit.

text: Because of the limited

text: techniques currently available

text: to detect

text: exoplanet

text: s, many of those found to date have been of a size associated, in the Solar System, with giant planets. Because these large planets are inferred to share more in common with Jupiter than with the other giant planets, some have claimed that "jovian planet" is a more accurate term for them. Many of the exoplanets are much closer to their parent stars and hence much hotter than the giant planets in the Solar System, making it possible that some of those planets are a type not observed in the Solar System. Considering the relative

text: abundances of the elements in the universe

text: (approximately 98% hydrogen and helium) it would be surprising to find a predominantly rocky planet more massive than Jupiter. On the other hand, models of planetary-system formation have suggested that giant planets would be inhibited from forming as close to their stars as many of the extrasolar giant planets have been observed to orbit.

text: According to Blavatsky's teaching, every solar system in the universe is the expression of what is termed a "Logos" or "Solar Deity". Ranked below this Solar Deity are seven ministers or planetary spirits, with each of these celestial beings being in control of evolution on a particular planet.In The Secret Doctrine, Blavatsky stated that each planet had a sevenfold constitution, known as the "Planetary Chains"; these consist not only of a physical globe but also of two astral bodies, two mental bodies, and two spiritual bodies, all overlapping in the same space. According to Blavatsky, evolution occurs on descending and ascending arcs, from the first spiritual globe on to the first mental globe, then from the first astral globe to the first physical globe, and then on from there.She claimed that there were different levels of evolution, from mineral on to vegetable, animal, human, and then to superhuman or spiritual. Different levels of evolution occur in a successive order on each planet; thus when mineral evolution ends on the first planet and it proceeds on to vegetable evolution, then mineral evolution begins on the second planet.

text: According to Blavatsky's teaching, every

text: solar system

text: in the universe is the expression of what is termed a "Logos" or "Solar Deity". Ranked below this Solar Deity are seven ministers or planetary spirits, with each of these celestial beings being in control of evolution on a particular planet.In The Secret Doctrine, Blavatsky stated that each planet had a sevenfold constitution, known as the "Planetary Chains"; these consist not only of a physical globe but also of two astral bodies, two mental bodies, and two spiritual bodies, all overlapping in the same space. According to Blavatsky, evolution occurs on descending and ascending arcs, from the first spiritual globe on to the first mental globe, then from the first astral globe to the first physical globe, and then on from there.She claimed that there were different levels of evolution, from mineral on to vegetable, animal, human, and then to superhuman or spiritual. Different levels of evolution occur in a successive order on each planet; thus when mineral evolution ends on the first planet and it proceeds on to vegetable evolution, then mineral evolution begins on the second planet.

text: It takes the Solar System about 240 million years to complete one orbit of the Milky Way (a galactic year), so the Sun is thought to have completed 18–20 orbits during its lifetime and 1/1250 of a revolution since the origin of humans. The orbital speed of the Solar System about the center of the Milky Way is approximately  or 0.073% of the speed of light. The Sun moves through the heliosphere at . At this speed, it takes around 1,400 years for the Solar System to travel a distance of 1 light-year, or 8 days to travel 1 AU (astronomical unit).  The Solar System is headed in the direction of the zodiacal constellation Scorpius, which follows the ecliptic.

text: It takes the Solar System about 240 million years to complete one orbit of the Milky Way (a

text: galactic year

text: ), so the Sun is thought to have completed 18–20 orbits during its lifetime and 1/1250 of a revolution since the

text: origin of humans

text: . The

text: orbital speed

text: of the Solar System about the center of the Milky Way is approximately  or 0.073% of the

text: speed of light

text: . The Sun moves through the heliosphere at . At this speed, it takes around 1,400 years for the Solar System to travel a distance of 1 light-year, or 8 days to travel 1 AU (

text: astronomical unit

text: ).  The Solar System is headed in the direction of the zodiacal constellation Scorpius, which follows the ecliptic.

text: Wonders of the Solar System  is a 2010 book by the theoretical physicists Brian Cox and Andrew Cohen. The book is about the universe, cosmology as well as the Solar System, and is explained in a way that is accessible to a general reader. The book is based on a series with the same name Wonders of the Solar System.

text: Wonders of the Solar System  is a 2010 book by the

text: theoretical physicists

text: Brian Cox

text: and Andrew Cohen. The book is about

text: the universe

text: cosmology

text: as well as

text: the Solar System

text: , and is explained in a way that is accessible to a general reader. The book is based on a series with the same name

text: Wonders of the Solar System

text: The series contains a number of assumptions about the solar system which are outlandish by modern standards but which still seemed plausible, at least to the general public, in the time the stories were written. All of the planets of the solar system, and many of the moons and asteroids, are suitable for life, and most are already occupied by humanoid extraterrestrial races. The initial adventures take place in the planets of the solar system but later stories (after the character invents the "vibration drive") take the hero to other stars, other dimensions and even the distant past and almost to the end of the Universe. For example, they visit the star Deneb, which is the origin of Earth humans, as well as many other humanoid races across the Solar System and beyond.

text: The series contains a number of assumptions about the

text: solar system

text: which are outlandish by modern standards but which still seemed plausible, at least to the general public, in the time the stories were written. All of the planets of the solar system, and many of the moons and asteroids, are suitable for life, and most are already occupied by

text: humanoid

text: extraterrestrial

text: races. The initial adventures take place in the planets of the solar system but later stories (after the character invents the "vibration drive") take the hero to other stars, other dimensions and even the distant past and almost to the end of the Universe. For example, they visit the star

text: Deneb

text: , which is the origin of Earth humans, as well as many other humanoid races across the Solar System and beyond.

text: in arcseconds for binary star systems, extrasolar planets, solar system objects and other astronomical objects, we use orbital distance (semi-major axis),

text: in

text: arcseconds

text: for

text: binary star system

text: s,

text: extrasolar planet

text: s,

text: solar system objects

text: and other

text: astronomical object

text: s, we use

text: orbital distance

text: semi-major axis

text: A hiking path leads past the telescope; in 2004 part of this was turned into a planet trail with information panels about the Solar System with its planets. The trail ends at the 39 cm model of the Sun next to the visitor centre.

text: A hiking path leads past the telescope; in 2004 part of this was turned into a planet trail with information panels about the

text: Solar System

text: with its

text: planets

text: . The trail ends at the 39 cm model of the

text: Sun

text: next to the visitor centre.

text: Historically, equations of motion first appeared in classical mechanics to describe the motion of massive objects, a notable application was to celestial mechanics to predict the motion of the planets as if they orbit like clockwork (this was how Neptune was predicted before its discovery), and also investigate the stability of the solar system.

text: Historically, equations of motion first appeared in

text: classical mechanics

text: to describe the motion of

text: massive objects

text: , a notable application was to

text: celestial mechanics

text: to predict the motion of the planets as if they orbit like clockwork (this was how

text: Neptune

text: was predicted before its discovery), and also investigate the

text: stability of the solar system

text: HD 181433 c is an extrasolar planet located approximately 87 light years away in the constellation of Pavo, orbiting the star HD 181433. This planet has mass at least 0.64 times that of Jupiter and takes 962 days to orbit the star at an orbital distance of 1.76 AU or 263 Gm. However, the orbit is eccentric, which ranges from 1.27 AU (190 Gm) at periastron to 2.25 AU (337 Gm) at apastron. François Bouchy et al. have published a paper detailing the HD 181433 planetary system in Astronomy and Astrophysics.

text: HD 181433 c is an

text: extrasolar planet

text: located approximately 87

text: light year

text: s away in the

text: constellation

text: of

text: Pavo

text: , orbiting the

text: star

text: HD 181433

text: . This planet has

text: mass

text: at least 0.64 times that of

text: Jupiter

text: and takes 962 days to orbit the star at an

text: orbital distance

text: of 1.76 AU or 263 Gm. However, the orbit is eccentric, which ranges from 1.27 AU (190 Gm) at

text: periastron

text: to 2.25 AU (337 Gm) at

text: apastron

text: . François Bouchy et al. have published a paper detailing the HD 181433 planetary system in

text: Astronomy and Astrophysics

text: The defining dynamic characteristic of a planet is that it has cleared its neighborhood. A planet that has cleared its neighborhood has accumulated enough mass to gather up or sweep away all the planetesimals in its orbit. In effect, it orbits its star in isolation, as opposed to sharing its orbit with a multitude of similar-sized objects. This characteristic was mandated as part of the IAU's official definition of a planet in August, 2006. This criterion excludes such planetary bodies as Pluto, Eris and Ceres from full-fledged planethood, making them instead dwarf planets. Although to date this criterion only applies to the Solar System, a number of young extrasolar systems have been found in which evidence suggests orbital clearing is taking place within their circumstellar discs.

text: The defining dynamic characteristic of a planet is that it has cleared its neighborhood. A planet that has cleared its neighborhood has accumulated enough mass to gather up or sweep away all the

text: planetesimal

text: s in its orbit. In effect, it orbits its star in isolation, as opposed to sharing its orbit with a multitude of similar-sized objects. This characteristic was mandated as part of the

text: IAU

text: 's official

text: definition of a planet

text: in August, 2006. This criterion excludes such planetary bodies as

text: Pluto

text: Eris

text: and

text: Ceres

text: from full-fledged planethood, making them instead

text: dwarf planet

text: s. Although to date this criterion only applies to the Solar System, a number of young extrasolar systems have been found in which evidence suggests orbital clearing is taking place within their

text: circumstellar disc

text: s.

text: The solution of this problem is important to classical physics, since many naturally occurring forces are central.  Examples include gravity and electromagnetism as described by Newton's law of universal gravitation and Coulomb's law, respectively.  The problem is also important because some more complicated problems in classical physics (such as the two-body problem with forces along the line connecting the two bodies) can be reduced to a central-force problem.  Finally, the solution to the central-force problem often makes a good initial approximation of the true motion, as in calculating the motion of the planets in the Solar System.

text: The solution of this problem is important to classical physics, since many naturally occurring forces are central.  Examples include gravity and electromagnetism as described by

text: Newton's law of universal gravitation

text: and

text: Coulomb's law

text: , respectively.  The problem is also important because some more complicated problems in classical physics (such as the

text: two-body problem

text: with forces along the line connecting the two bodies) can be reduced to a central-force problem.  Finally, the solution to the central-force problem often makes a good initial approximation of the true motion, as in calculating the motion of the planets in the

text: Solar System

text: The rest frame of the center of mass of our solar system isn't a perfect inertial frame of reference since our solar system orbits around the center of the Milky Way. An estimation for the time of period of circulation is 230 million years (estimations vary between 225 and 250 million years). As the estimation for the distance between our solar system and the center of the Milky Way is about 28000 Ly, the assumed orbital speed of our solar system is

text: The rest frame of the center of mass of our solar system isn't a perfect inertial frame of reference since our solar system orbits around the center of the

text: Milky Way

text: . An estimation for the time of period of circulation is 230 million years (estimations vary between 225 and 250 million years). As the estimation for the distance between our solar system and the center of the Milky Way is about 28000

text: Ly

text: , the assumed

text: orbital speed

text: of our solar system is

text: Uranus is the third-largest planet in the Solar System. It orbits the Sun at a distance of about 2.8 billion kilometers (1.7 billion miles) and completes one orbit every 84 years. The length of a day on Uranus as measured by Voyager 2 is 17 hours and 14 minutes. Uranus is distinguished by the fact that it is tipped on its side. Its unusual position is thought to be the result of a collision with a planet-sized body early in the Solar System's history. Given its odd orientation, with its polar regions exposed to sunlight or darkness for long periods, scientists were not sure what to expect at Uranus.

text: Uranus is the third-largest planet in the

text: Solar System

text: . It orbits the

text: Sun

text: at a distance of about 2.8 billion kilometers (1.7 billion miles) and completes one orbit every 84 years. The length of a

text: day

text: on Uranus as measured by Voyager 2 is 17 hours and 14 minutes. Uranus is distinguished by the fact that it is tipped on its side. Its unusual position is thought to be the result of a collision with a planet-sized body early in the Solar System's

text: history

text: . Given its odd orientation, with its polar regions exposed to sunlight or darkness for long periods, scientists were not sure what to expect at Uranus.

text: Small bodies of the Solar System also experience an orbital decay.

text: Small bodies of the

text: Solar System

text: also experience an orbital decay.

text: Wasserburg's research led to a better understanding of the origins and history of the solar system and its component bodies and the precursor stellar sources contributing to the solar system; this research established a time scale for the development of the early solar system, including the processes of nucleosynthesis and the formation and evolution of the planets, the Moon and the meteorites. More recently he is investigating models of the chemical evolution of the Galaxy.

text: Wasserburg's research led to a better understanding of the origins and history of the solar system and its component bodies and the precursor stellar sources contributing to the solar system; this research established a time scale for the development of the early solar system, including the processes of

text: nucleosynthesis

text: and the formation and evolution of the planets, the Moon and the meteorites. More recently he is investigating models of the chemical evolution of the Galaxy.

text: G 240-72 has mass 0.81 Solar masses and surface gravity 10 (2.29 · 10) cm·s, or approximately 234 000 of Earth's, corresponding to a radius 6850 km, or 107% of Earth's.

text: G 240-72 has mass 0.81

text: Solar mass

text: es and

text: surface gravity

text: 10 (2.29 · 10) cm·s, or approximately 234 000 of

text: Earth's

text: , corresponding to a radius 6850

text: km

text: , or 107% of

text: Earth's

text: In the fully developed Aristotelian system, the spherical Earth is at the center of the universe, and all other heavenly bodies are attached to 47–55 transparent, rotating spheres surrounding the Earth, all concentric with it. (The number is so high because several spheres are needed for each planet.) These spheres, known as crystalline spheres, all moved at different uniform speeds to create the revolution of bodies around the Earth. They were composed of an incorruptible substance called aether. Aristotle believed that the moon was in the innermost sphere and therefore touches the realm of Earth, causing the dark spots (macula) and the ability to go through lunar phases.  He further described his system by explaining the natural tendencies of the terrestrial elements: Earth, water, fire, air, as well as celestial aether.  His system held that Earth was the heaviest element, with the strongest movement towards the center, thus water formed a layer surrounding the sphere of Earth. The tendency of air and fire, on the other hand, was to move upwards, away from the center, with fire being lighter than air. Beyond the layer of fire, were the solid spheres of aether in which the celestial bodies were embedded. They, themselves, were also entirely composed of aether.

text: In the fully developed Aristotelian system, the spherical Earth is at the center of the universe, and all other heavenly bodies are attached to 47–55 transparent, rotating spheres surrounding the Earth, all concentric with it. (The number is so high because several spheres are needed for each planet.) These spheres, known as crystalline spheres, all moved at different uniform speeds to create the revolution of bodies around the Earth. They were composed of an incorruptible substance called

text: aether

text: . Aristotle believed that the moon was in the innermost sphere and therefore touches the realm of Earth, causing the dark spots (

text: macula

text: ) and the ability to go through

text: lunar phases

text: .  He further described his system by explaining the natural tendencies of the terrestrial elements: Earth, water, fire, air, as well as celestial aether.  His system held that Earth was the heaviest element, with the strongest movement towards the center, thus water formed a layer surrounding the sphere of Earth. The tendency of air and fire, on the other hand, was to move upwards, away from the center, with fire being lighter than air. Beyond the layer of fire, were the solid spheres of aether in which the celestial bodies were embedded. They, themselves, were also entirely composed of aether.

text: A partial solar eclipse will occur on March 11, 2062. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: will occur on March 11, 2062. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: The various planets are thought to have formed from the solar nebula, the disc-shaped cloud of gas and dust left over from the Sun's formation. The currently accepted method by which the planets formed is accretion, in which the planets began as dust grains in orbit around the central protostar. Through direct contact, these grains formed into clumps up to 200 metres in diameter, which in turn collided to form larger bodies (planetesimals) of ~10 kilometres (km) in size. These gradually increased through further collisions, growing at the rate of centimetres per year over the course of the next few million years.

text: The various planets are thought to have formed from the solar nebula, the disc-shaped cloud of gas and dust left over from the Sun's formation. The currently accepted method by which the planets formed is

text: accretion

text: , in which the planets began as dust grains in orbit around the central protostar. Through direct contact, these grains formed into clumps up to 200 metres in diameter, which in turn collided to form larger bodies (

text: planetesimals

text: ) of ~10 kilometres (km) in size. These gradually increased through further collisions, growing at the rate of centimetres per year over the course of the next few million years.

text: Nine Views () is an ambiental installation in Zagreb, Croatia which, together with the sculpture Prizemljeno Sunce (The Grounded Sun), makes up a consistent model of the Solar System.

text: Nine Views () is an ambiental

text: installation

text: in

text: Zagreb

text: Croatia

text: which, together with the sculpture Prizemljeno Sunce (The Grounded Sun), makes up a consistent

text: model of the Solar System

text: The motion of Epsilon Eridani along the line of sight to Earth, known as the radial velocity, has been regularly observed for more than twenty years. Periodic changes in this data yielded evidence of a giant planet orbiting Epsilon Eridani, making it one of the nearest extrasolar systems with a candidate exoplanet. The detection of this orbiting planetary object, Epsilon Eridani b, was announced by Bruce Campbell, Gordon Walker and Stephenson Yang in 1987. A preliminary orbit was published in 2000 by a team of astronomers led by Artie Hatzes, based on six independent data sets with four different telescopes. Observations indicate that this planet, designated Epsilon Eridani b and later named AEgir (sic), orbits with a period of about 7 years at a mean separation of 3.4 astronomical units (AU), where 1 AU is the mean distance between Earth and the Sun. Although this discovery has been controversial because of the amount of background noise in the radial velocity data, many astronomers regard the planet as confirmed.

text: The motion of Epsilon Eridani along the line of sight to Earth, known as the

text: radial velocity

text: , has been regularly observed for more than twenty years. Periodic changes in this data

text: yielded evidence

text: of a

text: giant planet

text: orbiting Epsilon Eridani, making it one of the nearest extrasolar systems with a candidate

text: exoplanet

text: . The detection of this orbiting planetary object,

text: Epsilon Eridani b

text: , was announced by Bruce Campbell, Gordon Walker and Stephenson Yang in 1987. A preliminary orbit was published in 2000 by a team of astronomers led by

text: Artie Hatzes

text: , based on six independent data sets with four different telescopes. Observations indicate that this planet, designated

text: Epsilon Eridani b

text: and later named AEgir (sic), orbits with a period of about 7 years at a mean separation of 3.4

text: astronomical units

text: (AU), where 1 AU is the mean distance between Earth and the Sun. Although this discovery has been controversial because of the amount of background noise in the radial velocity data, many astronomers regard the planet as confirmed.

text: The Space Science and Engineering Center (SSEC) is a research and development center with primary focus on Earth science research and technology to enhance understanding of the atmosphere of Earth, the other planets in the Solar System, and the cosmos. SSEC is part of the University of Wisconsin–Madison's Graduate School.

text: The Space Science and Engineering Center (SSEC) is a research and development center with primary focus on

text: Earth science

text: research and technology to enhance understanding of the

text: atmosphere

text: of Earth, the other planets in the Solar System, and the cosmos. SSEC is part of the

text: University of Wisconsin–Madison

text: 's Graduate School.

text: Planetary science is the study of the assemblage of planets, moons, dwarf planets, comets, asteroids, and other bodies orbiting the Sun, as well as extrasolar planets. The Solar System has been relatively well-studied, initially through telescopes and then later by spacecraft. This has provided a good overall understanding of the formation and evolution of this planetary system, although many new discoveries are still being made.

text: Planetary science is the study of the assemblage of

text: planet

text: s,

text: moons

text: dwarf planet

text: s,

text: comet

text: s,

text: asteroid

text: s, and other bodies orbiting the Sun, as well as extrasolar planets. The

text: Solar System

text: has been relatively well-studied, initially through telescopes and then later by spacecraft. This has provided a good overall understanding of the formation and evolution of this planetary system, although many new discoveries are still being made.

text: The incremental effect of gravitational perturbations between the planets causes the inner Solar System as a whole to behave chaotically over long time periods. This does not significantly affect the stability of the Solar System over intervals of a few million years or less, but over billions of years the orbits of the planets become unpredictable. Computer simulations of the Solar System's evolution over the next five billion years suggest that there is a small (less than 1%) chance that a collision could occur between Earth and either Mercury, Venus, or Mars. During the same interval, the odds that the Earth will be scattered out of the Solar System by a passing star are on the order of one part in 10. In such a scenario, the oceans would freeze solid within several million years, leaving only a few pockets of liquid water about  underground. There is a remote chance that the Earth will instead be captured by a passing binary star system, allowing the planet's biosphere to remain intact. The odds of this happening are about one chance in three million.

text: The incremental effect of

text: gravitational perturbation

text: s between the planets causes the inner Solar System as a whole to behave

text: chaotically

text: over long time periods. This does not significantly affect the

text: stability of the Solar System

text: over intervals of a few million years or less, but over billions of years the orbits of the planets become unpredictable. Computer simulations of the Solar System's evolution over the next five billion years suggest that there is a small (less than 1%) chance that a collision could occur between Earth and either Mercury, Venus, or Mars. During the same interval, the odds that the Earth will be scattered out of the Solar System by a passing star are on the order of one part in 10. In such a scenario, the oceans would freeze solid within several million years, leaving only a few pockets of liquid water about  underground. There is a remote chance that the Earth will instead be captured by a passing binary star system, allowing the planet's biosphere to remain intact. The odds of this happening are about one chance in three million.

text: λ Orionis (also known as Meissa or Heka) is the star representing the head of Orion and can be found to the North of the quadrangle defined by the stars Betelgeuse, Bellatrix, Rigel and Saiph. This star can be found at the centre of open cluster Collinder 69 composed of fourth and fifth-magnitude young hot stars, visible to the naked eye.  It can be resolved with a pair of binoculars. The star phi2 Orionis , an orange giant which can be seen in the southeastern sector of the cluster, is not part of this region, although it might appear to be so due to projection effects. Its distance from the Sun is, in fact, only 116 light-years, as opposed to over 1400 light-years for the cluster itself and its associated nebula. Conversely, the nebula itself is not visible with binoculars or small amateur telescopes. It becomes clearly visible in long exposure photographs.

text: λ Orionis

text: (also known as Meissa or Heka) is the

text: star

text: representing the head of

text: Orion

text: and can be found to the

text: North

text: of the quadrangle defined by the stars

text: Betelgeuse

text: Bellatrix

text: Rigel

text: and

text: Saiph

text: . This star can be found at the centre of open cluster

text: Collinder 69

text: composed of fourth and fifth-magnitude young hot stars, visible to the naked eye.  It can be resolved with a pair of

text: binoculars

text: . The star

text: phi2 Orionis

text: , an

text: orange giant

text: which can be seen in the southeastern sector of the cluster, is not part of this region, although it might appear to be so due to projection effects. Its distance from the

text: Sun

text: is, in fact, only 116

text: light-years

text: , as opposed to over 1400

text: light-years

text: for the cluster itself and its associated nebula. Conversely, the nebula itself is not visible with

text: binoculars

text: or small amateur

text: telescopes

text: . It becomes clearly visible in long exposure

text: photographs

text: Other book projects followed, providing Naar with an opportunity to return to researching and writing on scientific topics, especially environmental themes. Jacques Cousteau wrote the introduction to Naar's 1973 book, Design for a Limited Planet, which featured interviews and photographs with pioneers of solar energy in the American Southwest and sold over 100,000 copies. As an early advocate of solar energy—he helped mount the first solar collectors on the roof of the White House—Naar later became president of the New York Metropolitan Solar Energy Society, and served for two years (1996-1998) as deputy director of renewable energy programs at the United States Agency for International Development. As a consultant, he worked with entities such as NRDC (Natural Resources Defense Council) and SELCO (Solar Electric Light Company India). In 1991, the American Library Association included Design for a Livable Planet (coauthored by Naar and his son Alex) among its "Best Books of the Year for Young Adults". His 2005 survey collection, Getting the Picture, was included in the "Best Designed Books 2006" exhibition at the Stedelijk Museum, Amsterdam.

text: Other book projects followed, providing Naar with an opportunity to return to researching and writing on scientific topics, especially environmental themes.

text: Jacques Cousteau

text: wrote the introduction to Naar's 1973 book, Design for a Limited Planet, which featured interviews and photographs with pioneers of solar energy in the American Southwest and sold over 100,000 copies. As an early advocate of solar energy—he helped mount the first solar collectors on the roof of the White House—Naar later became president of the New York Metropolitan Solar Energy Society, and served for two years (1996-1998) as deputy director of renewable energy programs at the

entity_name: United States Agency for International Development

text: United States Agency for International Development

text: . As a consultant, he worked with entities such as

text: NRDC

text: (Natural Resources Defense Council) and

text: SELCO

text: (Solar Electric Light Company India). In 1991, the American Library Association included Design for a Livable Planet (coauthored by Naar and his son Alex) among its "Best Books of the Year for Young Adults". His 2005 survey collection, Getting the Picture, was included in the "Best Designed Books 2006" exhibition at the

text: Stedelijk Museum

text: , Amsterdam.

text: Solar-like oscillations are oscillations in distant stars that are excited in the same way as those in the Sun, namely by turbulent convection in its outer layers. Stars that show solar-like oscillations are called solar-like oscillators. The oscillations are standing pressure and mixed pressure-gravity modes that are excited over a range in frequency, with the amplitudes roughly following a bell-shaped distribution.  Unlike opacity-driven oscillators, all the modes in the frequency range are excited, making the oscillations relatively easy to identify.  The surface convection also damps the modes, and each is well-approximated in frequency space by a Lorentzian curve, the width of which corresponds to the lifetime of the mode: the faster it decays, the broader is the Lorentzian.  All stars with surface convection zones are expected to show solar-like oscillations, including cool main-sequence stars (up to surface temperatures of about 7000K), subgiants and red giants. Because of the small amplitudes of the oscillations, their study has advanced tremendously thanks to space-based missions (mainly COROT and Kepler).

text: Solar-like oscillations are

text: oscillation

text: s in distant

text: star

text: s that are excited in the same way as those in the

text: Sun

text: , namely by turbulent

text: convection

text: in its outer layers. Stars that show solar-like oscillations are called solar-like oscillators. The oscillations are standing pressure and mixed pressure-gravity modes that are excited over a range in frequency, with the amplitudes roughly following a bell-shaped distribution.  Unlike opacity-driven oscillators, all the modes in the frequency range are excited, making the oscillations relatively easy to identify.  The surface convection also damps the modes, and each is well-approximated in frequency space by a Lorentzian curve, the width of which corresponds to the lifetime of the mode: the faster it decays, the broader is the Lorentzian.  All stars with surface convection zones are expected to show solar-like oscillations, including cool main-sequence stars (up to surface temperatures of about 7000K), subgiants and red giants. Because of the small amplitudes of the oscillations, their study has advanced tremendously thanks to space-based missions (mainly

text: COROT

text: and

text: Kepler

text: Bodies in the inner Solar System experienced a heavy bombardment of large rocky bodies in the first billion years or so of the Solar System. The impact which created Caloris must have occurred after most of the heavy bombardment had finished, because fewer impact craters are seen on its floor than exist on comparably-sized regions outside the crater.  Similar impact basins on the Moon such as the Mare Imbrium and Mare Orientale are believed to have formed at about the same time, possibly indicating that there was a 'spike' of large impacts towards the end of the heavy bombardment phase of the early Solar System. Based on MESSENGER's photographs, Caloris' age has been determined to be between 3.8 and 3.9 billion years.

text: Bodies in the inner Solar System experienced a heavy bombardment of large rocky bodies in the first billion years or so of the Solar System. The impact which created Caloris must have occurred after most of the heavy bombardment had finished, because fewer

text: impact crater

text: s are seen on its floor than exist on comparably-sized regions outside the crater.  Similar impact basins on the Moon such as the

text: Mare Imbrium

text: and

text: Mare Orientale

text: are believed to have formed at about the same time, possibly indicating that there was a 'spike' of large impacts towards the end of the heavy bombardment phase of the early Solar System. Based on MESSENGER's photographs, Caloris' age has been determined to be between 3.8 and 3.9 billion years.

text: There are several more single-planet systems in Aquarius. HD 210277, a magnitude 6.63 yellow star located 21.29 parsecs from Earth, is host to one known planet: HD 210277 b. The 1.23 Jupiter mass planet orbits at nearly the same distance as Earth orbits the Sun - 1.1 AU, though its orbital period is significantly longer at around 442 days. HD 210277 b was discovered earlier than most of the other planets in Aquarius, detected by the radial velocity method in 1998. The star it orbits resembles the Sun beyond their similar spectral class; it has a radius of 1.1 solar radii and a mass of 1.09 solar masses. HD 212771 b, a larger planet at 2.3 Jupiter masses, orbits host star HD 212771 at a distance of 1.22 AU. The star itself, barely below the threshold of naked-eye visibility at magnitude 7.6, is a G8IV (yellow subgiant) star located 131 parsecs from Earth. Though it has a similar mass to the Sun - 1.15 solar masses - it is significantly less dense with its radius of 5 solar radii. Its lone planet was discovered in 2010 by the radial velocity method, like several other exoplanets in the constellation.

text: There are several more single-planet systems in Aquarius.

text: HD 210277

text: , a magnitude 6.63 yellow star located 21.29 parsecs from Earth, is host to one known planet:

text: HD 210277 b

text: . The 1.23 Jupiter mass planet orbits at nearly the same distance as Earth orbits the Sun - 1.1 AU, though its orbital period is significantly longer at around 442 days. HD 210277 b was discovered earlier than most of the other planets in Aquarius, detected by the radial velocity method in 1998. The star it orbits resembles the Sun beyond their similar

text: spectral class

text: ; it has a radius of 1.1 solar radii and a mass of 1.09 solar masses.

text: HD 212771 b

text: , a larger planet at 2.3 Jupiter masses, orbits host star

text: HD 212771

text: at a distance of 1.22 AU. The star itself, barely below the threshold of naked-eye visibility at magnitude 7.6, is a G8IV (yellow subgiant) star located 131 parsecs from Earth. Though it has a similar mass to the Sun - 1.15 solar masses - it is significantly less dense with its radius of 5 solar radii. Its lone planet was discovered in 2010 by the radial velocity method, like several other exoplanets in the constellation.

text: A partial solar eclipse occurred on November 2, 1910. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: occurred on November 2, 1910. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: The discovery was advocated as a piece of evidence for the popular solar nebula accretion model, where planets are formed from the accretion of smaller objects. In this model, giant planet embryos grow large enough to acquire large envelopes of hydrogen and helium. However, opponents of this model emphasize that only one example of such a dense planet is not proof. In fact, such a huge core is difficult to explain even by the core accretion model.

text: The discovery was advocated as a piece of evidence for the popular

text: solar nebula

text: accretion model, where planets are formed from the accretion of smaller objects. In this model, giant planet embryos grow large enough to acquire large envelopes of

text: hydrogen

text: and

text: helium

text: . However, opponents of this model emphasize that only one example of such a dense planet is not proof. In fact, such a huge core is difficult to explain even by the core accretion model.

text: The standard model for the formation of the Solar System (including the Earth) is the solar nebula hypothesis. In this model, the Solar System formed from a large, rotating cloud of interstellar dust and gas called the solar nebula. It was composed of hydrogen and helium created shortly after the Big Bang 13.8 Ga (billion years ago) and heavier elements ejected by supernovae. About 4.5 Ga, the nebula began a contraction that may have been triggered by the shock wave of a nearby supernova. A shock wave would have also made the nebula rotate. As the cloud began to accelerate, its angular momentum, gravity and inertia flattened it into a protoplanetary disk perpendicular to its axis of rotation. Small perturbations due to collisions and the angular momentum of other large debris created the means by which kilometer-sized protoplanets began to form, orbiting the nebular center.

text: The standard model for the formation of the

text: Solar System

text: (including the

text: Earth

text: ) is the

text: solar nebula hypothesis

text: . In this model, the Solar System formed from a large, rotating cloud of interstellar dust and gas called the

text: solar nebula

text: . It was composed of

text: hydrogen

text: and

text: helium

text: created

text: shortly after

text: the

text: Big Bang

text: Ga

text: (billion years ago) and heavier

text: elements

text: ejected by

text: supernovae

text: . About 4.5

text: Ga

text: , the nebula began a contraction that may have been triggered by the

text: shock wave

text: of a nearby

text: supernova

text: . A shock wave would have also made the nebula rotate. As the cloud began to accelerate, its

text: angular momentum

text: gravity

text: and

text: inertia

text: flattened it into a

text: protoplanetary disk

text: perpendicular to its axis of rotation. Small

text: perturbations

text: due to collisions and the angular momentum of other large debris created the means by which kilometer-sized

text: protoplanet

text: s began to form, orbiting the nebular center.

text: The Sun is orbiting the center of the Milky Way, going in the direction of Cygnus. The Sun's orbit around the Milky Way is expected to be roughly elliptical with the addition of perturbations due to the galactic spiral arms and non-uniform mass distributions. In addition the Sun oscillates up and down relative to the galactic plane approximately 2.7 times per orbit. It has been argued that the Sun's passage through the higher density spiral arms often coincides with mass extinctions on Earth, perhaps due to increased impact events. It takes the Solar System about 225–250 million years to complete one orbit through the Milky Way (a galactic year), so it is thought to have completed 20–25 orbits during the lifetime of the Sun. The orbital speed of the Solar System about the center of the Milky Way is approximately 251 km/s (156 mi/s). At this speed, it takes around 1,190 years for the Solar System to travel a distance of 1 light-year, or 7 days to travel 1 AU.

text: The Sun is orbiting the center of the Milky Way, going in the direction of

text: Cygnus

text: . The Sun's orbit around the Milky Way is expected to be roughly elliptical with the addition of perturbations due to the galactic spiral arms and non-uniform mass distributions. In addition the Sun oscillates up and down relative to the galactic plane approximately 2.7 times per orbit. It has been argued that the Sun's passage through the higher density spiral arms often coincides with

text: mass extinction

text: s on Earth, perhaps due to increased

text: impact events

text: . It takes the Solar System about 225–250 million years to complete one orbit through the Milky Way (a

text: galactic year

text: ), so it is thought to have completed 20–25 orbits during the lifetime of the Sun. The

text: orbital speed

text: of the Solar System about the center of the Milky Way is approximately 251 km/s (156 mi/s). At this speed, it takes around 1,190 years for the Solar System to travel a distance of 1 light-year, or 7 days to travel 1

text: AU

text: In the traditional approach to modeling effects of gravity, general relativity is assumed to be valid at cosmological scales as well as in the Solar System, where its predictions have been more accurately tested. Not changing the rules of gravity, however, implies the presence of dark matter and dark energy in parts of the Universe where the curvature of the space-time manifold is far less than that in the Solar System. It is phenomenologically possible to alter the equations of gravity in regions of low space-time curvature such that the dynamics of the space-time causes what we assign to the presence of dark matter and dark energy. Dark fluid hypothesizes that the dark fluid is a specific kind of fluid whose attractive and repulsive behaviors depend on the local energy density. In this theory, the dark fluid behaves like dark matter in the regions of space where the baryon density is high. The idea is that when the dark fluid is in the presence of matter, it slows down and coagulates around it; this then attracts more dark fluid to coagulate around it, thus amplifying the force of gravity near it. This description is similar to theories of dark matter. The effect is always present, but only becomes noticeable in the presence of a really large mass such as a galaxy. If this effect sounds very much like a description of dark matter, then that's not a coincidence, as a special case of the equations of dark fluid reproduces dark matter.

text: In the traditional approach to modeling effects of gravity,

text: general relativity

text: is assumed to be valid at cosmological scales as well as in the Solar System, where its predictions have been more accurately tested. Not changing the rules of gravity, however, implies the presence of

text: dark matter

text: and

text: dark energy

text: in parts of the Universe where the curvature of the

text: space-time

text: manifold

text: is far less than that in the Solar System. It is phenomenologically possible to alter the equations of gravity in regions of low space-time curvature such that the dynamics of the space-time causes what we assign to the presence of

text: dark matter

text: and

text: dark energy

text: . Dark fluid hypothesizes that the dark fluid is a specific kind of fluid whose attractive and repulsive behaviors depend on the local energy density. In this theory, the dark fluid behaves like

text: dark matter

text: in the regions of space where the baryon density is high. The idea is that when the dark fluid is in the presence of matter, it slows down and coagulates around it; this then attracts more dark fluid to coagulate around it, thus amplifying the force of gravity near it. This description is similar to theories of

text: dark matter

text: . The effect is always present, but only becomes noticeable in the presence of a really large mass such as a galaxy. If this effect sounds very much like a description of dark matter, then that's not a coincidence, as a special case of the equations of dark fluid reproduces dark matter.

text: The planets were thought by Ptolemy to orbit Earth in deferent and epicycle motions. Although the idea that the planets orbited the Sun had been suggested many times, it was not until the 17th century that this view was supported by evidence from the first telescopic astronomical observations, performed by Galileo Galilei. At about the same time, by careful analysis of pre-telescopic observation data collected by Tycho Brahe, Johannes Kepler found the planets' orbits were not circular but elliptical. As observational tools improved, astronomers saw that, like Earth, the planets rotated around tilted axes, and some shared such features as ice caps and seasons. Since the dawn of the Space Age, close observation by space probes has found that Earth and the other planets share characteristics such as volcanism, hurricanes, tectonics, and even hydrology.

text: The planets were thought by

text: Ptolemy

text: to orbit

text: Earth

text: in

text: deferent and epicycle

text: motions. Although the idea that the

text: planets orbited the Sun

text: had been suggested many times, it was not until the 17th century that this view was supported by evidence from the first

text: telescopic

text: astronomical observations

text: , performed by

text: Galileo Galilei

text: . At about the same time, by careful analysis of pre-telescopic observation data collected by

text: Tycho Brahe

text: Johannes Kepler

text: found the planets' orbits were not circular but

text: elliptical

text: . As observational tools improved,

text: astronomer

text: s saw that, like Earth, the planets rotated around tilted axes, and some shared such features as

text: ice cap

text: s and seasons. Since the dawn of the

text: Space Age

text: , close observation by

text: space probe

text: s has found that Earth and the other planets share characteristics such as

text: volcanism

text: hurricane

text: s,

text: tectonics

text: , and even

text: hydrology

text: In 2009, it was shown that the presence of a smaller planet at Jupiter's position in the Solar System might increase the impact rate of comets on the Earth significantly. A planet of Jupiter's mass still seems to provide increased protection against asteroids, but the total effect on all orbital bodies within the Solar System is unclear. Computer simulations in 2016 have continued to erode the theory.

text: Orbitals spin to mimic the effects of gravity and are sized so that the rate of rotation necessary to produce a comfortable gravity level is approximately equal to one day. In the case of the standard Culture day and gravity, this diameter is around three million kilometres. For such an orbital to reproduce the equivalent to the Earth's gravity (9.8 m/s at sea level), whilst maintaining Earth's 24-hour period of rotation, it would need to have a diameter of approximately 3.71 million kilometres, and spinning at 486,000 km/hr. By tilting the axis of the Orbital relative to its orbit around a star a convenient day-night cycle can be experienced by the inhabitants. Since the edges of the Orbital are built as high walls, the rotation prevents the atmosphere from escaping, thus protecting the inhabitants from radiation. The walls are typically hundreds or thousands of kilometres high, made of a 'monocrystal' material.

text: Orbitals

text: spin to mimic the effects

text: of

text: gravity

text: and are sized so that the rate of

text: rotation

text: necessary to produce a comfortable gravity level is approximately equal to one

text: day

text: . In the case of the standard Culture day and gravity, this

text: diameter

text: is around three million kilometres. For such an orbital to reproduce the equivalent to the Earth's gravity (9.8 m/s at sea level), whilst maintaining Earth's 24-hour period of rotation, it would need to have a diameter of approximately 3.71 million kilometres, and spinning at 486,000 km/hr. By tilting the

text: axis

text: of the Orbital relative to its

text: orbit

text: around a

text: star

text: a convenient day-night cycle can be experienced by the inhabitants. Since the edges of the Orbital are built as high walls, the rotation prevents the atmosphere from escaping, thus protecting the inhabitants from

text: radiation

text: . The walls are typically hundreds or thousands of kilometres high, made of a 'monocrystal' material.

text: In 2009, Southern California Edison entered into a contract with Solar Millennium to purchase solar thermal power up to 726 MW. Southern California Edison also entered into a contract with Stirling Energy Systems to buy electricity from a 500 megawatt, 4,600 acre (19 km), solar power plant which was due to open in 2009. The purchase was canceled in late 2010, as changes in technology reduced the cost of photovoltaic-based solar power to below that of solar Stirling generated power. This would have been the first commercial application of the dish stirling system. A different technology from the more familiar solar panel, the dish concentrates solar energy by the use of reflective surfaces and by the use of the Stirling heat engine to convert the heat into electricity.

text: In 2009, Southern California Edison entered into a contract with

text: Solar Millennium

text: to purchase solar thermal power up to 726 MW. Southern California Edison also entered into a contract with

text: Stirling Energy Systems

text: to buy electricity from a 500 megawatt, 4,600 acre (19 km), solar power plant which was due to open in 2009. The purchase was canceled in late 2010, as changes in technology reduced the cost of photovoltaic-based solar power to below that of solar Stirling generated power. This would have been the first commercial application of the

text: dish stirling system

text: . A different technology from the more familiar solar panel, the dish concentrates solar energy by the use of reflective surfaces and by the use of the

text: Stirling heat engine

text: to convert the heat into electricity.

text: In the history of astronomy, a handful of Solar System bodies have been counted as the fifth planet from the Sun. Under the present definition of a planet, Jupiter is counted as the fifth.

text: In the

text: history of astronomy

text: , a handful of

text: Solar System

text: bodies have been counted as the fifth planet from the

text: Sun

text: . Under the present definition of a

text: planet

text: Jupiter

text: is counted as the fifth.

text: The nebular hypothesis says that the Solar System formed from the gravitational collapse of a fragment of a giant molecular cloud. The cloud was about 20 parsec (65 light years) across, while the fragments were roughly 1 parsec (three and a quarter light-years) across. The further collapse of the fragments led to the formation of dense cores 0.01–0.1 pc (2,000–20,000 AU) in size. One of these collapsing fragments (known as the pre-solar nebula) formed what became the Solar System. The composition of this region with a mass just over that of the Sun () was about the same as that of the Sun today, with hydrogen, along with helium and trace amounts of lithium produced by Big Bang nucleosynthesis, forming about 98% of its mass. The remaining 2% of the mass consisted of heavier elements that were created by nucleosynthesis in earlier generations of stars. Late in the life of these stars, they ejected heavier elements into the interstellar medium.

text: The nebular hypothesis says that the Solar System formed from the gravitational collapse of a fragment of a giant

text: molecular cloud

text: . The cloud was about 20

text: parsec

text: (65 light years) across, while the fragments were roughly 1 parsec (three and a quarter

text: light-year

text: s) across. The further collapse of the fragments led to the formation of dense cores 0.01–0.1

text: pc

text: AU

text: ) in size. One of these collapsing fragments (known as the pre-solar nebula) formed what became the Solar System. The composition of this region with a mass just over that of the Sun () was about the same as that of the Sun today, with

text: hydrogen

text: , along with

text: helium

text: and trace amounts of

text: lithium

text: produced by

text: Big Bang nucleosynthesis

text: , forming about 98% of its mass. The remaining 2% of the mass consisted of

text: heavier elements

text: that were created by

text: nucleosynthesis

text: in earlier generations of stars. Late in the life of these stars, they ejected heavier elements into the

text: interstellar medium

text: Another such example would be HIP 11915, which has a planetary system containing a Jupiter-like planet orbiting at a similar distance that the planet Jupiter does in the Solar System. To strengthen the similarities, the star is class G5V, very similar temperature of 5750 K, its sun-like mass and radius, and is only 500 million years younger than the Sun. As such, the habitable zone would extend in the same area as the zone in the Solar System, around 1 AU. This would allow an Earth-like planet to exist around 1 AU.

text: Another such example would be

text: HIP 11915

text: , which has a planetary system containing a

text: Jupiter-like planet

text: orbiting at a similar distance that the planet

text: Jupiter

text: does in the Solar System. To strengthen the similarities, the star is class G5V, very similar temperature of 5750 K, its sun-like mass and radius, and is only 500 million years younger than the Sun. As such, the habitable zone would extend in the same area as the zone in the Solar System, around 1 AU. This would allow an Earth-like planet to exist around 1 AU.

text: Triton is the largest natural satellite of the planet Neptune. It was discovered on October 10, 1846, by English astronomer William Lassell. It is the only large moon in the Solar System with a retrograde orbit, an orbit in the opposite direction to its planet's rotation. At  in diameter, it is the seventh-largest moon in the Solar System. Because of its retrograde orbit and composition similar to Pluto's, Triton is thought to have been a dwarf planet captured from the Kuiper belt. Triton has a surface of mostly frozen nitrogen, a mostly water-ice crust, an icy mantle and a substantial core of rock and metal. The core makes up two-thirds of its total mass. Triton has a mean density of 2.061 g/cm and is composed of approximately 15–35% water ice.

text: Triton is the largest

text: natural satellite

text: of the

text: planet

text: Neptune

text: . It was discovered on October 10, 1846, by English astronomer

text: William Lassell

text: . It is the only large moon in the

text: Solar System

text: with a

text: retrograde orbit

text: , an orbit in the opposite direction to its planet's rotation. At  in diameter, it is the

text: seventh-largest moon

text: in the Solar System. Because of its retrograde orbit and composition similar to

text: Pluto

text: 's, Triton is thought to have been a

text: dwarf planet

text: captured from the

text: Kuiper belt

text: . Triton has a surface of mostly

text: frozen nitrogen

text: , a mostly

text: water-ice

text: crust, an icy

text: mantle

text: and a substantial

text: core

text: of rock and metal. The core makes up two-thirds of its total mass. Triton has a mean density of 2.061 g/cm and is composed of approximately 15–35% water ice.

text: The treatise uses a geocentric model of the solar system, in which the Sun and Moon are each carried by epicycles which in turn revolve around the Earth.  In this model, which is also found in the Paitāmahasiddhānta (ca. AD 425), the motions of the planets are each governed by two epicycles, a smaller manda (slow) epicycle and a larger śīghra (fast) epicycle.

text: The treatise uses a

text: geocentric

text: model of the solar system, in which the Sun and Moon are each carried by

text: epicycle

text: s which in turn revolve around the Earth.  In this model, which is also found in the Paitāmahasiddhānta (ca. AD 425), the motions of the planets are each governed by two epicycles, a smaller manda (slow) epicycle and a larger śīghra (fast) epicycle.

text: About 99 percent of all European and 90 percent of all U.S. solar power systems are connected to the electrical grid, while off-grid systems are somewhat more common in Australia and South Korea. PV systems rarely use battery storage. This may change soon, as government incentives for distributed energy storage are being implemented and investments in storage solutions are gradually becoming economically viable for small systems. A solar array of a typical residential PV system is rack-mounted on the roof, rather than integrated into the roof or facade of the building, as this is significantly more expensive. Utility-scale solar power stations are ground-mounted, with fixed tilted solar panels rather than using expensive tracking devices. Crystalline silicon is the predominant material used in 90 percent of worldwide produced solar modules, while rival thin-film has lost market-share in recent years. About 70 percent of all solar cells and modules are produced in China and Taiwan, leaving only 5 percent to European and US-manufacturers. The installed capacity for both, small rooftop systems and large solar power stations is growing rapidly and in equal parts, although there is a notable trend towards utility-scale systems, as the focus on new installations is shifting away from Europe to sunnier regions, such as the Sunbelt in the U.S., which are less opposed to ground-mounted solar farms and cost-effectiveness is more emphasized by investors.

text: About 99 percent of all European and 90 percent of all U.S. solar power systems are connected to the

text: electrical grid

text: , while off-grid systems are somewhat more common in Australia and South Korea. PV systems rarely use battery storage. This may change soon, as government incentives for distributed energy storage are being implemented and investments in storage solutions are gradually becoming economically viable for small systems. A solar array of a typical residential PV system is rack-mounted on the roof, rather than integrated into the roof or facade of the building, as this is significantly more expensive. Utility-scale

text: solar power station

text: s are ground-mounted, with fixed tilted solar panels rather than using expensive tracking devices. Crystalline silicon is the predominant material used in 90 percent of worldwide produced solar modules, while rival thin-film has lost market-share in recent years. About 70 percent of all solar cells and modules are produced in China and Taiwan, leaving only 5 percent to European and US-

text: manufacturers

text: . The installed capacity for both, small rooftop systems and large solar power stations is growing rapidly and in equal parts, although there is a notable trend towards utility-scale systems, as the focus on new installations is shifting away from Europe to sunnier regions, such as the

text: Sunbelt

text: in the U.S., which are less opposed to ground-mounted solar farms and cost-effectiveness is more emphasized by investors.

text: In that capacity, he was an early eyewitness to the horrors of the Holocaust, and his research and subsequent report alerted many organizations in the United States to the forgotten people of World War II – the displaced Jews. Upon completion of his report, Fleishman made a 60-city U.S. lecture tour, discussing these refugees’ relief and rehabilitation needs. The trip influenced his life as he became deeply involved in various Jewish causes and with minority affairs. A longtime member of the Assembly of the Jewish Agency in Israel, Fleishman made 57 visits to Israel between 1955 and 1997, becoming a personal friend of many of the founders and leaders of the state.

text: In that capacity, he was an early eyewitness to the horrors of the

text: Holocaust

text: , and his research and subsequent report alerted many organizations in the United States to the forgotten people of World War II – the displaced

text: Jews

text: . Upon completion of his report, Fleishman made a 60-city U.S. lecture tour, discussing these refugees’ relief and rehabilitation needs. The trip influenced his life as he became deeply involved in various Jewish causes and with minority affairs. A longtime member of the Assembly of the Jewish Agency in Israel, Fleishman made 57 visits to Israel between 1955 and 1997, becoming a personal friend of many of the founders and leaders of the state.

text: After Danmaje's death in 1870 his successor, Haruna Karami, continued the expansionist policy with the strong backing of his able lieutenant Usman Danyaya, the then barden of Ningi. Haruna died in 1886 and Abubakar Gajigi was appointed the leader. Abubakar maintained Ningi's struggle to survive as a state of its own without losing any territory to the neighboring emirates.

text: Image morphing is a technique to synthesize a fluid transformation from one image (source image) to another (destination image). Source image can be one or more than one images. There are two parts in the image morphing implementation. The first part is warping and the second part is cross-dissolving.

text: Image morphing

text: is a technique to synthesize a fluid transformation from one image (source image) to another (destination image). Source image can be one or more than one images. There are two parts in the image morphing implementation. The first part is warping and the second part is cross-dissolving.

text: In 2015, the Muslim Rashtriya Manch published a book title "Yoga and Islam" on universal appeal and acceptance of Yoga. The Manch expressed its views that 'Yoga' does not have anything to do with religion, further stating that "Namaaz is one sort of Yoga asana". The move was supported by the Union Ministry of Ayurveda, Yoga and Naturopathy, Unani, Siddha and Homoeopathy (AYUSH) but Hindu groups expressed reservations.

text: In 2015, the Muslim Rashtriya Manch published a book title "Yoga and Islam" on universal appeal and acceptance of Yoga. The Manch expressed its views that 'Yoga' does not have anything to do with religion, further stating that "Namaaz is one sort of Yoga asana". The move was supported by the Union

text: Ministry of Ayurveda, Yoga and Naturopathy, Unani, Siddha and Homoeopathy

text: (AYUSH) but Hindu groups expressed reservations.

text: With the introduction of the Space Shuttle, NASA and the Air Force needed an upper stage to boost payloads out of low Earth orbit. A new version of Centaur, the Centaur-G, was developed, with both Challenger and Discovery modified to carry the stage. Centaur-G was optimized for installation in the Orbiter payload bay by increasing the hydrogen tank diameter to 14 feet while retaining the 10-foot-diameter (3.0 m) oxygen tank. Its initial mission, scheduled for May 16, 1986, was to boost the Galileo probe to Jupiter, then, just six days later, the Ulysses probe. Ulysses would also be boosted to Jupiter in order to use the planet's gravity to reach a highly inclined solar orbit to allow observation of the Sun's polar regions. A shortened version of the Centaur-G was also planned for use on shuttle missions involving Department of Defense payloads and was to be used for launching the Magellan probe to Venus.

text: With the introduction of the

text: Space Shuttle

text: , NASA and the Air Force needed an upper stage to boost payloads out of low Earth orbit. A new version of Centaur, the Centaur-G, was developed, with both

text: Challenger

text: and

text: Discovery

text: modified to carry the stage. Centaur-G was optimized for installation in the Orbiter payload bay by increasing the hydrogen tank diameter to 14 feet while retaining the 10-foot-diameter (3.0 m) oxygen tank. Its initial mission, scheduled for May 16, 1986, was to boost the

text: Galileo

text: probe to

text: Jupiter

text: , then, just six days later, the

text: Ulysses

text: probe. Ulysses would also be boosted to Jupiter in order to

text: use the planet's gravity

text: to reach a

text: highly inclined

text: solar orbit to allow observation of the Sun's polar regions. A shortened version of the Centaur-G was also planned for use on shuttle missions involving

text: Department of Defense

text: payloads and was to be used for launching the

text: Magellan

text: probe to Venus.

text: As of 2011, Soondh has a total number of 245 houses and population of 1140 of which 583 include are males while 557 are females according to the report published by Census India in 2011. The literacy rate of Soondh is 77.33% higher than the state average of 75.84%. The population of children under the age of 6 years is 121 which is 10.61% of total population of Soondh, and child sex ratio is approximately 779 as compared to Punjab state average of 846.

text: As of 2011, Soondh has a total number of 245 houses and population of 1140 of which 583 include are males while 557 are females according to the report published by

text: Census India in 2011

text: . The

text: literacy rate

text: of Soondh is 77.33% higher than the state average of 75.84%. The population of children under the age of 6 years is 121 which is 10.61% of total population of Soondh, and

text: child sex ratio

text: is approximately 779 as compared to Punjab state average of 846.

text: A partial solar eclipse will occur on January 14, 2029. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: will occur on January 14, 2029. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: There is one Gatha Temple on the bank of Indrayani river. A big statue of Tukaram sitting with a Veena in his hand is located at the entrance of the big Gatha temple. In the Gatha temple, about 4,000 abhangs (verses) created by Tukaram maharaj were carved on the walls.

text: There is one Gatha Temple on the bank of Indrayani river. A big statue of

text: Tukaram

text: sitting with a

text: Veena

text: in his hand is located at the entrance of the big Gatha temple. In the Gatha temple, about 4,000 abhangs (verses) created by Tukaram maharaj were carved on the walls.

text: A partial solar eclipse occurred on August 20, 1906. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: occurred on August 20, 1906. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: Responsible Officers

text: Responsible Officers

text: The small digits of the species are slender and clawed. The small beak structure is formed by the projections of the rostral and mental shields. Preanal pores are present on R, ornata.This gecko regulates its temperature by moving to warmer or cooler positions.The female of the species is often larger and matures at an early age, less than 1 year, which allows greater development of its eggs for increased viability of its offspring. They produce two leathery eggs.

text: When the Sun formed from its protostar, around 4.56 billion years ago, the solar wind blew all gas particles from the central part of the Solar Nebula. In this way most lighter volatile elements (e.g. hydrogen, helium, oxygen, carbon), that had not yet condensed in the inner, warmer regions of the nebula, were lost. This fractionation process is the reason why the terrestrial planets and asteroid belt are relatively enriched in heavy elements in respect to the Sun or the gas planets.

text: When the Sun formed from its

text: protostar

text: , around 4.56 billion years ago, the

text: solar wind

text: blew all

text: gas

text: particle

text: s from the central part of the Solar Nebula. In this way most lighter

text: volatile

text: elements (e.g.

text: hydrogen

text: helium

text: oxygen

text: carbon

text: ), that had not yet condensed in the inner, warmer regions of the nebula, were lost. This fractionation process is the reason why the

text: terrestrial planet

text: s and

text: asteroid belt

text: are relatively enriched in heavy elements in respect to the Sun or the

text: gas planet

text: s.

text: Doug Shaffer (born July 8, 1963) is an American college diving coach.  He is the current co-head coach of the LSU Tigers and Lady Tigers swimming and diving teams of Louisiana State University with responsibilities for the dive team. Dave Geyer is head coach of the swimming team.

text: Doug Shaffer (born July 8, 1963) is an American college

text: diving

text: coach.  He is the current co-

text: head coach

text: of the

text: LSU Tigers and Lady Tigers

text: swimming

text: and

text: diving

text: teams of

text: Louisiana State University

text: with responsibilities for the dive team.

text: Dave Geyer

text: is head coach of the swimming team.

text: Koob is from Cascade, Iowa.

text: Koob is from

text: Cascade, Iowa

text: When Mr. Lillie left the firm in 1839, the name changed to William Fairbairn & Sons and the company's attention turned to railway  locomotives.

text: When Mr. Lillie left the firm in 1839, the name changed to William Fairbairn & Sons and the company's attention turned to

text: railway

text: locomotives

text: Thomas Jackson also known as Tommy (16 March 1898 – 1975) was a football (soccer) player in the early years of professional football in England, who played over 200 games for Aston Villa.

text: Thomas Jackson also known as Tommy (16 March 1898 – 1975) was a

text: football (soccer)

text: player in the early years of professional football in

text: England

text: , who played over 200 games for

text: Aston Villa

text: After the merger of HP and EEsof, the EEsof products were combined with the HP simulator, Microwave Design System (MDS). HP's own entry, MDS, had been introduced in 1985.  It was developed in-house and comprised a linear circuit simulator with integrated schematic capture and graphical layout with back-annotation, a first for RF EDA software.  MDS was offered on UNIX workstations from HP, Sun, and Apollo as well on the PC.  Prior to the introduction of MDS, HP had a marketing relationship with EEsof and sold Touchstone software on HP platforms such as the Series 200 (but not on the PC).  The marketing relationship ended after the introduction of HP's MDS product.

text: The game world includes approximately 150 solar systems, each of which contains between zero and eight planets ranging from inhospitable gas giants to habitable earth-like worlds.  Thirty sentient species are native to this region of space and inhabit various planets throughout the sector.  Six of these possess fleets of spaceships which may be encountered in some solar systems and in interstellar space.  The spacefaring alien races include the perpetually depressed Dweenle, the deeply religious two warring branches of the Tandelou, and the mercantile oriented Humna Humna. The central part of the game world is dominated by the massive Cloud Nebula mentioned in the game's title; it is infested with the powerful spaceships of the hostile Umanu and Uhlek.

text: The game world includes approximately 150 solar systems, each of which contains between zero and eight planets ranging from inhospitable gas giants to habitable earth-like worlds.  Thirty sentient species are native to this region of space and inhabit various planets throughout the sector.  Six of these possess fleets of spaceships which may be encountered in some solar systems and in interstellar space.  The spacefaring alien races include the perpetually

text: depressed

text: Dweenle, the deeply religious two warring branches of the Tandelou, and the mercantile oriented Humna Humna. The central part of the game world is dominated by the massive Cloud Nebula mentioned in the game's title; it is infested with the powerful spaceships of the hostile Umanu and Uhlek.

text: Orderic tells us that Edgar was the commander of an English fleet which operated off the coast of the region of Syria in support of the First Crusade, whose crews eventually burned their dilapidated ships and joined the advance by land to Jerusalem. This is doubtful, as this fleet is known to have arrived off the Syrian coast by March 1098: since Edgar invaded Scotland late in 1097, he could not have made the voyage in the time available. It may be though that he travelled overland to the Mediterranean and joined the fleet en route; this is the view taken by Runciman. William of Malmesbury recorded that Edgar made a pilgrimage to Jerusalem in 1102, and it may be that Orderic's report is the product of confusion, conflating the expedition of the English fleet with Edgar's later journey. Some modern historians have suggested that at some point during these years Edgar served in the Varangian Guard of the Byzantine Empire, a unit which was at that time composed primarily of English emigrants, but this is unsupported by evidence. William of Malmesbury stated that on his way back from Jerusalem Edgar was given rich gifts by both the Byzantine and the German emperors, each of whom offered him an honoured place at court, but that he insisted on returning home instead.

text: Orderic tells us that Edgar was the commander of an English fleet which operated off the coast of the

text: region of Syria

text: in support of the

text: First Crusade

text: , whose crews eventually burned their dilapidated ships and joined the advance by land to

text: Jerusalem

text: . This is doubtful, as this fleet is known to have arrived off the Syrian coast by March 1098: since Edgar invaded Scotland late in 1097, he could not have made the voyage in the time available. It may be though that he travelled overland to the Mediterranean and joined the fleet en route; this is the view taken by Runciman.

text: William of Malmesbury

text: recorded that Edgar made a pilgrimage to Jerusalem in 1102, and it may be that Orderic's report is the product of confusion, conflating the expedition of the English fleet with Edgar's later journey. Some modern historians have suggested that at some point during these years Edgar served in the

text: Varangian Guard

text: of the

text: Byzantine Empire

text: , a unit which was at that time composed primarily of English emigrants, but this is unsupported by evidence. William of Malmesbury stated that on his way back from Jerusalem Edgar was given rich gifts by both the Byzantine and the German emperors, each of whom offered him an honoured place at court, but that he insisted on returning home instead.

text: The Cedar Hill Longhorns compete in the following sports:

text: The school was situated at Langton Hall, historically the seat of the Norcliffe family. The Hall that was leased to Woodleigh School, now owned by their descendants, the Howard-Vyse family, is a Grade II* listed building.

text: The school was situated at Langton Hall, historically the seat of the Norcliffe family. The Hall that was leased to Woodleigh School, now owned by their descendants, the Howard-Vyse family, is a

text: Grade II*

text: listed building.

text: The hammam is divided into 3 sections:

text: The hammam is divided into 3 sections:

text: He was promoted to Lieutenant General in 1993.

text: de:Kedrowyru:Кедровый

text: de:Kedrowy

text: ru:Кедровый

text: OLE Nepal has worked in partnership with various central and local level agencies within the Ministry of Education system to ensure that they build the necessary institutional capacity to implement ICT-based Education on a national level. The project has gained tremendously from the inputs provided by government trainers, curriculum experts, district level school supervisors, resource persons and teachers. The OLPC project was implemented in partnership with the Department of Education and the District Education Offices in the program districts. The DoE and OLE Nepal has also worked together to promote awareness about ICT-based Education. Teacher trainings have been conducted with help of government trainers who were prepared in providing ICT-based Education training. OLE Nepal has consulted with subject experts from the Curriculum Development Center in the preparation and review of the E-Paath activities. All in all, OLE Nepal opts to work with and empower existing resources within our public education system instead of creating a parallel system.

text: The Bauhaus typeface design is based on Herbert Bayer's 1925 experimental Universal typeface.

text: The Bauhaus

text: typeface

text: design is based on

text: Herbert Bayer

text: 's 1925 experimental Universal typeface.

text: He was born in Manchester, son of gentleman farmer John Walker Cash, and educated at the Quaker schools at Bootham in York and at Kendal. He studied medicine at Edinburgh University, where he qualified MB  in 1876 and  MD in 1879. After a period of post-graduate work in Berlin, Vienna and Paris he returned to Berlin to carry out investigative work at the Physiological Institute on muscle behaviour and in Leipzig on the digestion of fats.

text: He was born in Manchester, son of gentleman farmer John Walker Cash, and educated at the Quaker schools at Bootham in York and at Kendal. He studied medicine at

text: Edinburgh University

text: , where he qualified MB  in 1876 and  MD in 1879. After a period of post-graduate work in Berlin, Vienna and Paris he returned to Berlin to carry out investigative work at the Physiological Institute on muscle behaviour and in Leipzig on the digestion of fats.

text: Church of Saint Catherine (Kostel svaté Kateřiny)

text: Most systems use a deterministic dynamic routing algorithm:When a device chooses a path to a particular final destination, that device always chooses the same path to that destination until it receives information that makes it think some other path is better.A few routing algorithms do not use a deterministic algorithm to find the "best" link for a packet to get from its original source to its final destination.Instead, to avoid congestion in switched systems or network hot spots in packet systems, a few algorithms use a randomized algorithm—Valiant's paradigm—that routes a path to a randomly picked intermediate destination, and from there to its true final destination.In many early telephone switches, a randomizer was often used to select the start of a path through a multistage switching fabric.

text: Most systems use a deterministic

text: dynamic routing

text: algorithm:When a device chooses a path to a particular final destination, that device always chooses the same path to that destination until it receives information that makes it think some other path is better.A few routing algorithms do not use a deterministic algorithm to find the "best" link for a packet to get from its original source to its final destination.Instead, to avoid congestion in switched systems or network hot spots in packet systems, a few algorithms use a randomized algorithm—Valiant's paradigm—that routes a path to a randomly picked intermediate destination, and from there to its true final destination.In many early telephone switches, a

text: randomizer

text: was often used to select the start of a path through a

text: multistage switching fabric

text: To coincide with the introduction of the UK’s Psychoactive Substances Act 2016 on 26 May 2016, Amanda Feilding released the report, “Roadmaps to Regulation: New Psychoactive Substances.” The document surveys the complex and unique world of NPS production and distribution and suggests a harm reductive model for the legal regulation of this vast array of substances. The NPS report is part of wider family of forthcoming reports, “Roadmaps to Regulation: Cannabis, Psychedelics, MDMA and NPS“.

text: The music is performed by a single musician playing a wooden whistle (tatil) and a small drum (tacún). The music is made of a repetitive and monotonous melody.

text: Orbits of spacecraft are also possible around Lagrangian points—also referred to as libration points—gravity wells that exist at five points in relation to two larger solar system bodies.  For example, there are five of these points in the Sun-Earth system, five in the Earth-Moon system, and so on.  Small spacecraft may orbit around these gravity wells with a minimum of propellant required for station-keeping purposes.  Two orbits that have been used for such purposes include halo and Lissajous orbits.

text: Orbits of spacecraft are also possible around

text: Lagrangian point

text: s—also referred to as

text: libration point

text: s—

text: gravity well

text: s that exist at five points in relation to two larger solar system bodies.  For example, there are five of these points in the Sun-Earth system, five in the Earth-Moon system, and so on.  Small spacecraft may orbit around these gravity wells with a minimum of propellant required for station-keeping purposes.  Two orbits that have been used for such purposes include

text: halo

text: and

text: Lissajous

text: orbits.

text: Evidence for the domestication of the horse comes from three kinds of sources: 1) changes in the skeletons and teeth of ancient horses; 2) changes in the geographic distribution of ancient horses, particularly the introduction of horses into regions where no wild horses had existed; and3) archaeological sites containing artifacts, images, or evidence of changes in human behavior connected with horses.

text: Evidence for the domestication of the horse comes from three kinds of sources: 1) changes in the skeletons and teeth of ancient horses; 2) changes in the geographic distribution of ancient horses, particularly the introduction of horses into regions where no wild horses had existed; and3)

text: archaeological

text: sites containing artifacts, images, or evidence of changes in human behavior connected with horses.

text: On September 13, 2016, both "Missin U" and "Rivals" impacted US urban adult contemporary radio as the album's third and fourth singles.

text: The Solar System formed 4.6 billion years ago from the gravitational collapse of a giant interstellar molecular cloud. The vast majority of the system's mass is in the Sun, with most of the remaining mass contained in Jupiter. The four smaller inner planets, Mercury, Venus, Earth and Mars, are terrestrial planets, being primarily composed of rock and metal. The four outer planets are giant planets, being substantially more massive than the terrestrials. The two largest, Jupiter and Saturn, are gas giants, being composed mainly of hydrogen and helium; the two outermost planets, Uranus and Neptune, are ice giants, being composed mostly of substances with relatively high melting points compared with hydrogen and helium, called volatiles, such as water, ammonia and methane. All planets have almost circular orbits that lie within a nearly flat disc called the ecliptic.

text: The Solar System

text: formed 4.6 billion years ago

text: from the

text: gravitational collapse

text: of a giant interstellar

text: molecular cloud

text: . The vast majority of the system's

text: mass

text: is in the Sun, with most of the remaining mass contained in

text: Jupiter

text: . The four smaller inner planets,

text: Mercury

text: Venus

text: Earth

text: and

text: Mars

text: , are

text: terrestrial planet

text: s, being primarily composed of rock and metal. The four outer planets are

text: giant planet

text: s, being substantially more massive than the terrestrials. The two largest, Jupiter and

text: Saturn

text: , are

text: gas giant

text: s, being composed mainly of

text: hydrogen

text: and

text: helium

text: ; the two outermost planets,

text: Uranus

text: and

text: Neptune

text: , are

text: ice giant

text: s, being composed mostly of substances with relatively high melting points compared with hydrogen and helium, called

text: volatiles

text: , such as water,

text: ammonia

text: and

text: methane

text: . All planets have almost circular orbits that lie within a nearly flat disc called the

text: ecliptic

text: Weathered ultramafic rocks may form lateritic nickel ore deposits.

text: Weathered ultramafic rocks may form

text: lateritic nickel ore deposits

text: 79360 Sila–Nunam is a double cold classical Kuiper belt object (cubewano) with components of almost equal size, orbiting beyond Neptune in the Solar System. The name of the system is the combined names of the two bodies, Sila and Nunam.

text: 79360 Sila–Nunam is a

text: double

text: cold

text: classical Kuiper belt object

text: (cubewano) with components of almost equal size, orbiting beyond

text: Neptune

text: in the

text: Solar System

text: . The name of the system is the combined names of the two bodies, Sila and Nunam.

text: Usually, there is a partial rubber closure on the top of the disposal unit to prevent food waste from flying back up out of the grinding chamber. It may also be used to attenuate noise from the grinding chamber for quieter operation.

text: All the planets in the Solar System except Mercury were observed; the telescope could not point at any part of the sky within 45° of the Sun, and Mercury's greatest angular distance from the Sun is only about 28°. IUE observations of Venus showed that the amount of sulfur monoxide and sulfur dioxide in its atmosphere declined by a large amount during the 1980s. The reason for this decline is not yet fully understood, but one hypothesis is that a large volcanic eruption had injected sulfur compounds into the atmosphere, and that they were declining following the end of the eruption.

text: All the planets in the

text: Solar System

text: except

text: Mercury

text: were observed; the telescope could not point at any part of the sky within 45° of the Sun, and Mercury's

text: greatest angular distance from the Sun

text: is only about 28°. IUE observations of

text: Venus

text: showed that the amount of

text: sulfur monoxide

text: and

text: sulfur dioxide

text: in its atmosphere declined by a large amount during the 1980s. The reason for this decline is not yet fully understood, but one hypothesis is that a large

text: volcanic

text: eruption had injected sulfur compounds into the atmosphere, and that they were declining following the end of the eruption.

text: The microsite and rankings closed in March 2002 with the demise of Dreamarena.

text: The first round was held on July 15.

text: The first round was held on July 15.

text: Open Flemish Liberals and Democrats (), commonly known as Open Vld or simply as the VLD, is  a liberal and conservative-liberal Flemish political party in Belgium. The party was created in 1992 from the former Party for Freedom and Progress (PVV) and politicians from other parties. The party led the government for three cabinets under Guy Verhofstadt from 1999 until March 2008. Open VLD most recently formed the Federal Government (the so-called "Swedish government") with N-VA, CD&V and the Francophone Reformist Movement (MR).

text: Open Flemish Liberals and Democrats (), commonly known as Open Vld or simply as the VLD, is  a

text: liberal

text: and

text: conservative-liberal

text: Flemish

text: political party in Belgium

text: . The party was created in 1992 from the former

text: Party for Freedom and Progress

text: (PVV) and politicians from other parties. The party led the government for three cabinets under

text: Guy Verhofstadt

text: from 1999 until March 2008. Open VLD most recently formed the Federal Government (the so-called "Swedish government") with

text: N-VA

text: CD&V

text: and the Francophone

text: Reformist Movement

text: (MR).

text: The film first premiered at the 62nd Locarno International Film Festival on 13 August 2009.

text: The film first premiered at the 62nd

text: Locarno International Film Festival

text: on 13 August 2009.

text: Recent observations with the Hubble Space Telescope have yielded the major discovery of protoplanetary disks within the Orion Nebula, which have been dubbed proplyds. HST has revealed more than 150 of these within the nebula, and they are considered to be systems in the earliest stages of solar system formation. The sheer numbers of them have been used as evidence that the formation of star systems is fairly common in our universe.

text: Recent observations with the

text: Hubble Space Telescope

text: have yielded the major discovery of

text: protoplanetary disk

text: s within the Orion Nebula, which have been dubbed proplyds. HST has revealed more than 150 of these within the nebula, and they are considered to be systems in the earliest stages of

text: solar system formation

text: . The sheer numbers of them have been used as evidence that the formation of star systems is fairly common in our

text: universe

text: Since the discovery of Newton's law of universal gravitation in the 17th century, the stability of the Solar System has preoccupied many mathematicians, starting with Laplace. The stable orbits that arise in a two-body approximation ignore the influence of other bodies. The effect of these added interactions on the stability of the Solar System is very small, but at first it was not known whether they might add up over longer periods to significantly change the orbital parameters and lead to a completely different configuration, or whether some other stabilising effects might maintain the configuration of the orbits of the planets.

text: Since the discovery of

text: Newton's law of universal gravitation

text: in the 17th century, the

text: stability of the Solar System

text: has preoccupied many mathematicians, starting with

text: Laplace

text: . The stable orbits that arise in a

text: two-body approximation

text: ignore the influence of other bodies. The effect of these added interactions on the stability of the

text: Solar System

text: is very small, but at first it was not known whether they might add up over longer periods to significantly change the orbital parameters and lead to a completely different configuration, or whether some other stabilising effects might maintain the configuration of the orbits of the planets.

text: Pachyrhachis is one of three genera of Cenomanian snakes with hindlimbs. Although many modern pythons and boas still retain remnants of legs, in the form of small spurs, the tiny legs of Pachyrhachis included a hip, knee, and ankle joint.  Pachyrhachis was originally described by Haas (1979, 1980) who noted it had a puzzling melange of snake and lizard features; its status as an early snake was later confirmed (Caldwell and Lee 1997).

text: Pachyrhachis is one of three genera of

text: Cenomanian

text: snakes with hindlimbs. Although many modern

text: pythons

text: and

text: boa

text: s still retain remnants of legs, in the form of small spurs, the tiny legs of Pachyrhachis included a hip, knee, and ankle joint.  Pachyrhachis was originally described by Haas (1979, 1980) who noted it had a puzzling melange of snake and lizard features; its status as an early snake was later confirmed (Caldwell and Lee 1997).

text: All projections of the future of the Earth, the Solar System, and the Universe must account for the second law of thermodynamics, which states that entropy, or a loss of the energy available to do work, must increase over time. Stars eventually must exhaust their supply of hydrogen fuel and burn out. Close encounters gravitationally fling planets from their star systems, and star systems from galaxies.

text: All projections of the

text: future of the Earth

text: the Solar System

text: , and

text: the Universe

text: must account for the

text: second law of thermodynamics

text: , which states that

text: entropy

text: , or a loss of the energy available to do work, must increase over time. Stars eventually must exhaust their supply of

text: hydrogen

text: fuel and burn out. Close encounters gravitationally fling planets from their star systems, and star systems from galaxies.

text: Roughly 39,000 Indonesians in Saudi Arabia registered to vote in Indonesia's 2004 presidential election through one of the 27 polling stations set up for them in the kingdom; they represented nearly half of all Indonesian in the Middle East who registered to vote.

text: Roughly 39,000 Indonesians in Saudi Arabia registered to vote in

text: Indonesia's 2004 presidential election

text: through one of the 27 polling stations set up for them in the kingdom; they represented nearly half of all Indonesian in the

text: Middle East

text: who registered to vote.

text: It is now known from study of the sun and primitive meteorites that the solar system was initially almost homogeneous in isotopic composition. Deviations from the (evolving) galactic average, locally sampled around the time that the sun's nuclear burning began, can generally be accounted for by mass fractionation (see the article on mass-independent fractionation) plus a limited number of nuclear decay and transmutation processes. There is also evidence for injection of short-lived (now extinct) isotopes from a nearby supernova explosion that may have triggered solar nebula collapse. Hence deviations from natural abundance on earth are often measured in parts per thousand (per mille or ‰) because they are less than one percent (%).

text: It is now known from study of the sun and primitive meteorites that the solar system was initially almost homogeneous in isotopic composition. Deviations from the (evolving) galactic average, locally sampled around the time that the sun's nuclear burning began, can generally be accounted for by mass fractionation (see the article on

text: mass-independent fractionation

text: ) plus a limited number of nuclear decay and transmutation processes. There is also evidence for injection of short-lived (now extinct) isotopes from a nearby supernova explosion that may have triggered solar nebula collapse. Hence deviations from natural abundance on earth are often measured in parts per thousand (

text: per mille

text: or ‰) because they are less than one percent (%).

text: The word tobiano is of Spanish origin, probable first used in South America to describe horses brought in by a Dutch emigrant named Tobias.

text: The word tobiano is of

text: Spanish

text: origin, probable first used in South America to describe horses brought in by a Dutch emigrant named Tobias.

text: In his final years, he suffered from Parkinson's disease and died at age 89.

text: In his final years, he suffered from

text: Parkinson's disease

text: and died at age 89.

text: When a solar water heating and hot-water central heating system are used in conjunction, solar heat will either be concentrated in a pre-heating tank that feeds into the tank heated by the central heating, or the solar heat exchanger will replace the lower heating element and the upper element will remain in place to provide for any heating that solar cannot provide. However, the primary need for central heating is at night and in winter when solar gain is lower. Therefore, solar water heating for washing and bathing is often a better application than central heating because supply and demand are better matched. In many climates, a solar hot water system can provide up to 85% of domestic hot water energy. This can include domestic non-electric concentrating solar thermal systems. In many northern European countries, combined hot water and space heating systems (solar combisystems) are used to provide 15 to 25% of home heating energy. When combined with storage, large scale solar heating can provide 50-97% of annual heat consumption for district heating.

text: When a solar water heating and hot-water central heating system are used in conjunction, solar heat will either be concentrated in a pre-heating tank that feeds into the tank heated by the

text: central heating

text: , or the solar heat exchanger will replace the lower heating element and the upper element will remain in place to provide for any heating that solar cannot provide. However, the primary need for central heating is at night and in winter when solar gain is lower. Therefore, solar water heating for washing and bathing is often a better application than central heating because supply and demand are better matched. In many climates, a solar hot water system can provide up to 85% of domestic hot water energy. This can include domestic non-electric

text: concentrating solar thermal

text: systems. In many northern European countries, combined hot water and space heating systems (

text: solar combisystem

text: s) are used to provide 15 to 25% of home heating energy. When combined with

text: storage

text: , large scale solar heating can provide 50-97% of annual heat consumption for

text: district heating

text: It is related to the orrery, which illustrates the relative positions and motions of the planets and moons in the solar system in a heliocentric model.

text: It is related to the

text: orrery

text: , which illustrates the relative positions and motions of the planets and moons in the solar system in a heliocentric model.

text: The station has four distinct groups of tracks, giving a total of 26 tracks:

text: A partial

text: solar eclipse

text: occurred on October 12, 1996. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: is given by the

text: is given by the

text: for which the denominator

text: for which the denominator

text: is left adjoint of

text: is left adjoint of

text: and the

text: and the

text: is decreasing and that

text: is decreasing and that

text: are constant.

text: are constant.

text: 120 years ago, in preparation for the coming doom, mankind began anexodus to the manmade satellites in outer space.  But the "Day ofJudgment" arrived even before half the population had escaped tospace.  The shift in the tectonic plate caused the shape of thePacific Ocean to change and a new continent was created.

text: In 2005, Jack Wisdom suggested that e actually had a period of 261 days and had a mass similar to that of Neptune in a 261-day orbit (corresponding to 0.77 AU in distance). However, the planets were found to not conflict, and hence 55 Cancri f, the first occurrence of a fifth extrasolar planet in one system, was announced in 2007. With a similar mass to c, it has a 260-day orbit, towards the inner edge of 55 Cancri A's habitable zone. The planet itself is not thought to be conducive to life, but hypothetical moons in principle could maintain at least microbial life.

text: In 2005,

text: Jack Wisdom

text: suggested that e actually had a period of 261 days and had a mass similar to that of Neptune in a 261-day orbit (corresponding to 0.77 AU in distance). However, the planets were found to not conflict, and hence

text: 55 Cancri f

text: , the first occurrence of a fifth extrasolar planet in one system, was announced in 2007. With a similar mass to

text: c

text: , it has a 260-day orbit, towards the inner edge of 55 Cancri A's

text: habitable zone

text: . The planet itself is not thought to be conducive to life, but hypothetical

text: moons

text: in principle could maintain at least microbial life.

text: In the case of orbital elements for objects within the solar system, only a few of the classical orbital elements are affected by a switch of equinox: the longitude of the ascending node, and (to a much lesser extent) the inclination. If another set of orbital elements are used, such as the position and velocity vectors for a particular epoch, all components can be affected by a switch of equinox.

text: The Golden Globe and Steel Beach take place in a universe similar to, but different from, Varley’s "Eight Worlds" universe; in both universes, the solar system has been colonized by human refugees fleeing aliens (known simply as "the Invaders") invading the Earth. Earth and Jupiter are off-limits to humanity, but Earth's moon (known as Luna) and the other planets and moons of the solar system have all become heavily populated. There are also minor colonies set in the Oort cloud beyond the solar system itself.  The Golden Globe story is told initially from a first person perspective, but a substantial portion of the book comes in the form of extended flashbacks.

text: The Golden Globe and Steel Beach take place in a universe similar to, but different from, Varley’s "

text: Eight Worlds

text: " universe; in both universes, the

text: solar system

text: Earth

text: . Earth and

text: Jupiter

text: are off-limits to humanity, but Earth's

text: moon

text: (known as Luna) and the other

text: planet

text: s and moons of the solar system have all become heavily populated. There are also minor colonies set in the

text: Oort cloud

text: beyond the solar system itself.  The Golden Globe story is told initially from a

text: first person

text: perspective, but a substantial portion of the book comes in the form of extended

text: flashbacks