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.

method: Bert-ConvKNRM

text: Original Version – In the mid-1990s, the ozone layer had begun to rapidly disappear, and an ozone hole covered most of planet Earth. After the death of his wife Brenda Wyatt in 1995, the now-mortal Connor became the supervisor of a team attempting to create an artificial shield, which would cover the planet and protect it from the sun's radiation. In 1999, the team succeeded in its goal, and Earth gained its artificial shield, filtering sunlight in place of the ozone layer. MacLeod was proud in having apparently saved humanity. However, the shield had the side-effect of condemning the planet to a state of constant night, and humanity could no longer see the sun, the moon, or the stars. Humanity began to lose hope, and fell into a sharp decline. The Shield fell under the control of the Shield Corporation, taxing for its services for the purposes of profit. Meanwhile, Connor, as years passed, had physically aged into a frail old man, and expected to eventually die of natural causes. He had also been able to learn the source of his immortality. Connor was a reincarnation of an alien humanoid from the planet Zeist. In fact, all Immortals had been reincarnations from exiled criminals from Zeist (though the "reincarnation" aspect never made it into the film).

text: Original Version – In the mid-1990s, the

entity_name: Ozone layer

text: ozone layer

text: had begun to rapidly disappear, and an

entity_name: Ozone depletion

text: ozone hole

text: covered most of planet Earth. After the death of his wife Brenda Wyatt in 1995, the now-mortal Connor became the supervisor of a team attempting to create an artificial shield, which would cover the planet and protect it from the sun's radiation. In 1999, the team succeeded in its goal, and Earth gained its artificial shield, filtering sunlight in place of the ozone layer. MacLeod was proud in having apparently saved humanity. However, the shield had the side-effect of condemning the planet to a state of constant night, and humanity could no longer see the sun, the moon, or the stars. Humanity began to lose hope, and fell into a sharp decline. The Shield fell under the control of the Shield Corporation, taxing for its services for the purposes of profit. Meanwhile, Connor, as years passed, had physically aged into a frail old man, and expected to eventually die of natural causes. He had also been able to learn the source of his immortality. Connor was a reincarnation of an alien humanoid from the planet Zeist. In fact, all Immortals had been reincarnations from exiled criminals from Zeist (though the "reincarnation" aspect never made it into the film).

method: ICT-DRMMTKS

text: The Stargate Command setting was transferred from the fictional military facility located in Creek Mountain, to the Cheyenne Mountain military complex. The unnamed planet from the film was named Abydos in the series and the distance from Earth changed from millions of light-years away (in an entirely different galaxy, "the Kalium galaxy") to becoming the closest planet to Earth with a Stargate, residing in the same galaxy as Earth. Also in SG-1, Stargate travel is limited to the Stargate network in the Milky Way galaxy (unless a tremendous amount of power is used to lengthen the subspace wormhole of a Stargate to another galaxy's Stargate). Ra was the last of an unnamed race in the film, being of a humanoid species with large black eyes and a lack of facial features. In SG-1, however, Ra is one of many "Goa'uld System Lords," who are a race of parasitic eel-like creatures. There were also changes to the Stargate. The unique set of 39 Stargate symbols in the film were replaced with the concept of 38 symbols that are the same for each Stargate (Earth's symbols based on Earth's constellations), plus a single point of origin symbol that is unique to that individual gate. While the kawoosh effect in the movie was created by filming the actual swirl of water in a glass tube, and looked like a vortex on the back of the Gate; on the TV series this effect was completely created in CG by the Canadian visual effects company Rainmaker. At the beginning of Season 9, the original movie wormhole sequence was substituted by a new sequence similar to the one already used on Stargate Atlantis, but being blue as it was in the movie and SG-1, whereas in Atlantis it's green and in Universe, it's white.

text: The

entity_name: Stargate Program

entity_section: Stargate Command

text: Stargate Command

text: setting was transferred from the fictional military facility located in Creek Mountain, to the

entity_name: Cheyenne Mountain Complex

text: Cheyenne Mountain military complex

text: . The unnamed planet from the film was named

entity_name: List of recurring alien characters in Stargate SG-1

entity_section: Abydonians

text: Abydos

text: in the series and the distance from Earth changed from millions of

entity_name: Light-year

text: light-year

text: s away (in an entirely different

entity_name: Galaxy

text: galaxy

text: , "the Kalium galaxy") to becoming the closest planet to

entity_name: Earth

text: Earth

text: with a Stargate, residing in the same galaxy as Earth. Also in SG-1, Stargate travel is limited to the Stargate network in the

entity_name: Milky Way

text: Milky Way galaxy

text: (unless a tremendous amount of power is used to lengthen the subspace wormhole of a Stargate to another galaxy's Stargate). Ra was the last of an unnamed race in the film, being of a humanoid species with large black eyes and a lack of facial features. In SG-1, however, Ra is one of many "

entity_name: Goa'uld

text: Goa'uld

entity_section: System Lords

text: System Lord

text: s," who are a race of parasitic eel-like creatures. There were also changes to the Stargate. The unique set of 39 Stargate symbols in the film were replaced with the concept of 38 symbols that are the same for each Stargate (Earth's symbols based on Earth's constellations), plus a single point of origin symbol that is unique to that individual gate. While the

entity_name: Stargate (device)

text: kawoosh

text: effect in the movie was created by filming the actual swirl of water in a glass tube, and looked like a vortex on the back of the Gate; on the TV series this effect was completely created in

entity_name: Computer graphics

text: CG

text: by the Canadian

entity_name: Visual effects

text: visual effects

text: company Rainmaker. At the beginning of Season 9, the original movie wormhole sequence was substituted by a new sequence similar to the one already used on Stargate Atlantis, but being blue as it was in the movie and SG-1, whereas in Atlantis it's green and in Universe, it's white.

text: Study of Earth's magnetosphere began in 1600, when William Gilbert discovered that the magnetic field on the surface of Earth resembled that on a terrella, a small, magnetized sphere. In the 1940s, Walter M. Elsasser proposed the model of dynamo theory, which attributes Earth's magnetic field to the motion of  Earth's iron outer core. Through the use of magnetometers, scientists were able to study the variations in Earth's magnetic field as functions of both time and latitude and longitude. Beginning in the late 1940s, rockets were used to study cosmic rays. In 1958, Explorer 1, the first of the Explorer series of space missions, was launched to study the intensity of cosmic rays above the atmosphere and measure the fluctuations in this activity. This mission observed the existence of the Van Allen radiation belt (located in the inner region of Earth's magnetosphere), with the Explorer 3 mission later that year definitively proving its existence. Also in 1958, Eugene Parker proposed the idea of the solar wind. The term 'magnetosphere' was proposed by Thomas Gold in 1959. The Explorer 12 mission (1961) led to the observation by Cahill and Amazeen in 1963 of a sudden decrease in the strength of the magnetic field near the noon meridian, later named the magnetopause. In 1983, the International Cometary Explorer observed the magnetotail, or the distant magnetic field.

text: Study of Earth's magnetosphere began in 1600, when

entity_name: William Gilbert (astronomer)

text: William Gilbert

text: discovered that the magnetic field on the surface of Earth resembled that on a

entity_name: Terrella

text: terrella

text: , a small, magnetized sphere. In the 1940s,

entity_name: Walter M. Elsasser

text: Walter M. Elsasser

text: proposed the model of

entity_name: Dynamo theory

text: dynamo theory

text: , which attributes

entity_name: Earth's magnetic field

text: Earth's magnetic field

text: to the motion of  Earth's

entity_name: Iron

text: iron

entity_name: Outer core

text: outer core

text: . Through the use of

entity_name: Magnetometer

text: magnetometer

text: s, scientists were able to study the variations in Earth's magnetic field as functions of both time and latitude and longitude. Beginning in the late 1940s, rockets were used to study

entity_name: Cosmic ray

text: cosmic rays

text: . In 1958,

entity_name: Explorer 1

text: Explorer 1

text: , the first of the Explorer series of space missions, was launched to study the intensity of cosmic rays above the atmosphere and measure the fluctuations in this activity. This mission observed the existence of the

entity_name: Van Allen radiation belt

text: Van Allen radiation belt

text: (located in the inner region of Earth's magnetosphere), with the

entity_name: Explorer 3

text: Explorer 3

text: mission later that year definitively proving its existence. Also in 1958,

entity_name: Eugene Parker

text: Eugene Parker

text: proposed the idea of the

entity_name: Solar wind

text: solar wind

text: . The term 'magnetosphere' was proposed by

entity_name: Thomas Gold

text: Thomas Gold

text: in 1959. The Explorer 12 mission (1961) led to the observation by Cahill and Amazeen in 1963 of a sudden decrease in the strength of the magnetic field near the noon meridian, later named the

entity_name: Magnetopause

text: magnetopause

text: . In 1983, the

entity_name: International Cometary Explorer

text: International Cometary Explorer

text: observed the magnetotail, or the distant magnetic field.

method: UNH-ecn

text: According to radiometric dating and other sources of evidence, Earth formed about 4.54 billion years ago. Earth gravitationally interacts with other objects in space, especially the Sun and the Moon. During one orbit around the Sun, Earth rotates about its axis 366.26 times, creating 365.26 solar days or one sidereal year. Earth's axis of rotation is tilted 23.4° away from the perpendicular of its orbital plane, producing seasonal variations on the planet's surface within a period of one tropical year (365.24 solar days). The Moon is the Earth's only permanent natural satellite; their gravitational interaction causes ocean tides, stabilizes the orientation of Earth's rotational axis, and gradually slows Earth's rotational rate.

text: According to

entity_name: Radiometric dating

text: radiometric dating

text: and other sources of evidence, Earth formed about 4.54 billion years ago.

entity_name: Gravity of Earth

text: Earth gravitationally

text: interacts with other objects in space, especially the Sun and the

entity_name: Moon

text: Moon

text: . During one orbit around the Sun, Earth rotates about its axis 366.26 times, creating 365.26

entity_name: Solar time

text: solar days

text: or one

entity_name: Sidereal year

text: sidereal year

text: . Earth's axis of rotation is tilted 23.4° away from the perpendicular of its

entity_name: Orbital plane (astronomy)

text: orbital plane

text: , producing seasonal variations on the planet's surface within a period of one

entity_name: Tropical year

text: tropical year

text: (365.24 solar days). The Moon is the Earth's only permanent

entity_name: Natural satellite

text: natural satellite

text: ; their gravitational interaction causes ocean tides, stabilizes the orientation of Earth's rotational axis, and gradually slows Earth's rotational rate.

method: UNH-tfidf-stem

method: UNH-tfidf-ptsim

method: UNH-tfidf-lem

method: UNH-qee

text: Part of the novel takes place on Mangala, one of the colony worlds. Mangala is a primarily desert planet which orbits its red dwarf primary in 3:2 resonance. As a result, it has a year-long day and a year-long night, each 15 Earth days long. (Mangala is also the Sanskrit name for the planet Mars.) Most of its settlers are from various European countries - emigrants to the frontier worlds tend to take the Jackaroo shuttle whose launch point is closest to their home on Earth, leading to different worlds having majorities from particular nations of groups of nations.

text: Part of the novel takes place on Mangala, one of the colony worlds. Mangala is a primarily desert planet which orbits its

entity_name: Red dwarf

text: red dwarf

text: primary in

entity_name: Orbital resonance

text: 3:2 resonance

text: . As a result, it has a year-long day and a year-long night, each 15 Earth days long. (Mangala is also the Sanskrit name for the planet Mars.) Most of its settlers are from various European countries - emigrants to the frontier worlds tend to take the Jackaroo shuttle whose launch point is closest to their home on Earth, leading to different worlds having majorities from particular nations of groups of nations.

text: The four outer planets, or giant planets (sometimes called Jovian planets), collectively make up 99% of the mass known to orbit the Sun. Jupiter and Saturn are together over 400 times the mass of Earth and consist overwhelmingly of hydrogen and helium; Uranus and Neptune are far less massive (<20 Earth masses each) and are composed primarily of ices. For these reasons, some astronomers suggest they belong in their own category, "ice giants". All four giant planets have rings, although only Saturn's ring system is easily observed from Earth. The term superior planet designates planets outside Earth's orbit and thus includes both the outer planets and Mars.

text: The four outer planets, or giant planets (sometimes called Jovian planets), collectively make up 99% of the mass known to orbit the Sun. Jupiter and Saturn are together over 400 times the mass of Earth and consist overwhelmingly of hydrogen and helium; Uranus and Neptune are far less massive (<20 Earth masses each) and are composed primarily of ices. For these reasons, some astronomers suggest they belong in their own category, "ice giants". All four giant planets have

entity_name: Ring system

text: rings

text: , although only Saturn's ring system is easily observed from Earth. The term

entity_name: Inferior and superior planets

text: superior planet

text: designates planets outside Earth's orbit and thus includes both the outer planets and Mars.

method: UvABottomUpChangeOrder

text: Rosebraugh's first book, "The Logic of Political Violence: Lessons in Reform and Revolution" was published in 2003 and is a comparison study between the use of non-violence and politically motivated violence in historical justice struggles. His second book, "Burning Rage of a Dying Planet: Speaking for the Earth Liberation Front" was published in 2004 and is a memoir of his time speaking on behalf of the Earth Liberation Front. In 2009, Rosebraugh was the contributing editor of the book, "This Country Must Change: Essays on the Necessity of Revolution in the U.S.A.," a compilation of essays from prominent political prisoners and activists in the United States.

text: Rosebraugh's first book, "The Logic of Political Violence: Lessons in Reform and Revolution" was published in 2003 and is a comparison study between the use of non-violence and politically motivated violence in historical justice struggles. His second book, "Burning Rage of a Dying Planet: Speaking for the Earth Liberation Front" was published in 2004 and is a memoir of his time speaking on behalf of the

entity_name: Earth Liberation Front

text: Earth Liberation Front

text: . In 2009, Rosebraugh was the contributing editor of the book, "This Country Must Change: Essays on the Necessity of Revolution in the U.S.A.," a compilation of essays from prominent political prisoners and activists in the United States.

text: In this system the revolution of the earth around fire "at the centre" or "the fire of the hearth" (Central Fire) was not yearly but daily, while the moon's revolution was monthly, and the sun's yearly. It was the earth's speedy travel past the slower moving sun that resulted in the appearance on earth of the sun rising and setting.  Further from the Central Fire, the planets' revolution was slower still and the outermost "sky" (i.e. stars) probably fixed.

method: dangnt-nlp

text: This method can be used to estimate the depth of the magnetic materials beneath the earth. The magnetic data is processed by the spectral methods such as Fourier transforms. The FFT algorithm makes the spectral analysis of signals fast, easy and efficient.The FFT computations can be performed in the machines which allow us to perform contour mapping. The upward continuation method attenuates the wave number anomalies associated with the shallow magnetic sources. Thus the signal components contain the information about the objects situated deep beneath the earth.

text: This method can be used to estimate the depth of the magnetic materials beneath the earth. The magnetic data is processed by the spectral methods such as Fourier transforms. The FFT algorithm makes the spectral analysis of signals fast, easy and efficient.The FFT computations can be performed in the machines which allow us to perform

entity_name: Contour line

text: contour mapping.

text: The upward continuation method attenuates the wave number anomalies associated with the shallow magnetic sources. Thus the signal components contain the information about the objects situated deep beneath the earth.

method: Bert-DRMMTKS

text: The series Diplodo focuses on five dinosaur-like creatures, known as the diplodorians. These creatures are from Diplodorianrex, the sister planet of Earth, which lies in the fourth dimension. The story explains that whatever happens to one planet also affects the other planet. The Diplodos have successfully defended their home planet and put up a strong defensive shield. This results in the Diplidos' enemies, led by the evil Santos, targeting Earth in order to destroy the Diplodos' home planet. With this threat, the five chosen Diplodos travel to Earth in order to defend the planet, which will result in saving their own. Here, they meet and become allies with two children, Peter and Joan.

text: The series Diplodo focuses on five

entity_name: Dinosaur

text: dinosaur

text: -like creatures, known as the diplodorians. These creatures are from Diplodorianrex, the sister planet of

text: Earth

text: , which lies in the

entity_name: Parallel universe (fiction)

text: fourth dimension

text: . The story explains that whatever happens to one planet also affects the other planet. The Diplodos have successfully defended their home planet and put up a strong

entity_name: Force field (fiction)

text: defensive shield

text: . This results in the Diplidos' enemies, led by the evil Santos, targeting Earth in order to destroy the Diplodos' home planet. With this threat, the five chosen Diplodos travel to Earth in order to defend the planet, which will result in saving their own. Here, they meet and become allies with two children, Peter and Joan.

text: The journal was originally named Terrestrial Magnetism by the American Geophysical Union's president Louis Agricola Bauer in 1896. It was entitled Terrestrial Magnetism and Atmospheric Electricity from 1899–1948. In 1980, three specialized sections were established: A: Space Physics, B: Solid Earth, and C: Oceans. Subsequently, further sections have been added: D: Atmospheres in 1984, E: Planets in 1991, F: Earth Surface in 2003, and G: Biogeosciences in 2005.

text: The journal was originally named Terrestrial Magnetism by the American Geophysical Union's president

entity_name: Louis Agricola Bauer

text: Louis Agricola Bauer

text: in 1896. It was entitled Terrestrial Magnetism and Atmospheric Electricity from 1899–1948. In 1980, three specialized sections were established: A: Space Physics, B: Solid Earth, and C: Oceans. Subsequently, further sections have been added: D: Atmospheres in 1984, E: Planets in 1991, F: Earth Surface in 2003, and G: Biogeosciences in 2005.

text: The geology of Mars is differentiable from that of Earth by, among other things, its extremely large volcanoes and lack of crust movement. A goal of the MEP is to understand these differences from Earth along with the way that wind, water, volcanoes, tectonics, cratering and other processes have shaped the surface of Mars. Rocks can help scientists describe the sequence of events in Mars' history, tell whether there was an abundance of water on the planet through identifying minerals that are formed only in water, and tell if Mars once had a magnetic field (which would point toward Mars at one point being a dynamic Earth-like planet).

text: The

entity_name: Geology of Mars

text: geology of Mars

text: is differentiable from that of Earth by, among other things, its extremely large volcanoes and lack of crust movement. A goal of the MEP is to understand these differences from Earth along with the way that wind, water, volcanoes, tectonics,

entity_name: Impact crater

text: cratering

text: and other processes have shaped the surface of Mars. Rocks can help scientists describe the sequence of events in Mars' history, tell whether there was an abundance of water on the planet through identifying minerals that are formed only in water, and tell if Mars once had a

entity_name: Magnetosphere

text: magnetic field

text: (which would point toward Mars at one point being a dynamic Earth-like planet).

text: Assuming that the true mass is the minimum mass, the radius may be calculated using various models. For example, if Gliese 581 c is a rocky planet with a large iron core, it should have a radius approximately 50% larger than that of Earth, according to Udry's team. Gravity on such a planet's surface would be approximately 2.24 times as strong as on Earth. However, if Gliese 581 c is an icy and/or watery planet, its radius would be less than 2 times that of Earth, even with a very large outer hydrosphere, according to density models compiled by Diana Valencia and her team for Gliese 876 d. Gravity on the surface of such an icy and/or watery planet would be at least 1.25 times as strong as on Earth.They claim the real value of the radius may be anything between the two extremes calculated by density models outlined above.

text: Assuming that the true mass is the minimum mass, the radius may be calculated using various models. For example, if Gliese 581 c is a

entity_name: Rock (geology)

text: rocky

text: planet with a large iron core, it should have a radius approximately 50% larger than that of Earth, according to Udry's team.

entity_name: Gravity

text: Gravity

text: on such a planet's surface would be approximately 2.24 times as strong as on Earth. However, if Gliese 581 c is an

entity_name: Ice

text: icy

text: and/or

entity_name: Water

text: water

text: y planet, its radius would be less than 2 times that of Earth, even with a very large outer

entity_name: Hydrosphere

text: hydrosphere

text: , according to density models compiled by Diana Valencia and her team for

entity_name: Gliese 876 d

text: Gliese 876 d

text: . Gravity on the surface of such an icy and/or watery planet would be at least 1.25 times as strong as on Earth.They claim the real value of the radius may be anything between the two extremes calculated by density models outlined above.

text: When close to a planet with a strong magnetosphere such as Earth or a gas giant, the magnetic sail could generate more thrust by interacting with the magnetosphere instead of the solar wind, and may therefore be more efficient.

text: When close to a planet with a strong

text: magnetosphere

text: such as

text: Earth

text: or a

entity_name: Gas giant

text: gas giant

text: , the magnetic sail could generate more thrust by interacting with the magnetosphere instead of the solar wind, and may therefore be more efficient.

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: Uranus's mass is roughly 14.5 times that of Earth, making it the least massive of the giant planets. Its diameter is slightly larger than Neptune's at roughly four times that of Earth. A resulting density of 1.27 g/cm makes Uranus the second least dense planet, after Saturn. This value indicates that it is made primarily of various ices, such as water, ammonia, and methane. The total mass of ice in Uranus's interior is not precisely known, because different figures emerge depending on the model chosen; it must be between 9.3 and 13.5 Earth masses. Hydrogen and helium constitute only a small part of the total, with between 0.5 and 1.5 Earth masses. The remainder of the non-ice mass (0.5 to 3.7 Earth masses) is accounted for by rocky material.

text: Uranus's mass is roughly 14.5 times that of Earth, making it the least massive of the giant planets. Its diameter is slightly larger than Neptune's at roughly four times that of Earth. A resulting density of 1.27 g/cm makes Uranus the second least dense planet, after Saturn. This value indicates that it is made primarily of various ices, such as water, ammonia, and methane. The total mass of ice in Uranus's interior is not precisely known, because different figures emerge depending on the model chosen; it must be between 9.3 and 13.5 Earth masses.

entity_name: Hydrogen

text: Hydrogen

text: and

entity_name: Helium

text: helium

text: constitute only a small part of the total, with between 0.5 and 1.5 Earth masses. The remainder of the non-ice mass (0.5 to 3.7 Earth masses) is accounted for by

text: rocky material

text: The seasons of the show as listed do not match the internally referenced season chronology because of two fictitious seasons. Internally season one references the Joe Rutherford (Ben Stiller) season, and seasons two and three reference the Annie (Abigail Spencer) season. Neither of these seasons actually occurred but are frequently mentioned during the course of various real episodes. Season three also announced a nonexistent season with superfan Hathwell Crisping.

text: Magnetofossils are not only being studied for their paleoenvironmental or paleoclimatic indicators.  As mentioned above, magnetofossils hold a remanent magnetization when they are formed.  That is, the magnetite (or greigite) aligns in the direction of the geomagnetic field.  The magnetite crystals can be thought of as being a simple magnet with a north and south pole, this north-south orientation aligns with the north-south magnetic poles of the Earth.  These fossils are then buried within the rock record.  Researchers can examine these rock samples in a remanent magnetometer where the effects of Earth's current magnetic field is removed, to determine the remanent, or initial, magnetization of the rock sample when it was formed.  In knowing the orientation of the rock in-situ and the remanent magnetization, researchers can determine the Earth's geomagnetic field at the time the rock was formed.  This can be used as an indicator of magnetic field direction, or reversals in the Earth's magnetic field, where the Earth's north and south magnetic poles switch (which happen on average every 450,000 years).

text: Magnetofossils are not only being studied for their paleoenvironmental or paleoclimatic indicators.  As mentioned above, magnetofossils hold a remanent magnetization when they are formed.  That is, the magnetite (or greigite) aligns in the direction of the geomagnetic field.  The magnetite crystals can be thought of as being a simple magnet with a north and south pole, this north-south orientation aligns with the north-south magnetic poles of the Earth.  These fossils are then buried within the rock record.  Researchers can examine these rock samples in a remanent

text: magnetometer

text: where the effects of Earth's current magnetic field is removed, to determine the remanent, or initial, magnetization of the rock sample when it was formed.  In knowing the orientation of the rock in-situ and the remanent magnetization, researchers can determine the Earth's geomagnetic field at the time the rock was formed.  This can be used as an indicator of magnetic field direction, or

entity_name: Geomagnetic reversal

text: reversals in the Earth's magnetic field

text: , where the Earth's north and south magnetic poles switch (which happen on average every 450,000 years).

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,

entity_name: Isaac Newton

text: Isaac Newton

text: published

entity_name: Philosophiæ Naturalis Principia Mathematica

text: Philosophiæ Naturalis Principia Mathematica

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

entity_name: Newton's law of universal gravitation

text: universal gravitation

text: and what came to be known as

entity_name: Newton's laws of motion

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: When William Gilbert published de Magnete in 1600, he concluded that the Earth is magnetic and proposed the first hypothesis for the origin of this magnetism: permanent magnetism such as that found in lodestone. In 1919, Joseph Larmor proposed that a dynamo might be generating the field. However, even after he advanced his hypothesis, some prominent scientists advanced alternative explanations. Einstein believed that there might be an asymmetry between the charges of the electron and proton so that the Earth's magnetic field would be produced by the entire Earth. The Nobel Prize winner Patrick Blackett did a series of experiments looking for a fundamental relation between angular momentum and magnetic moment, but found none.

text: When

text: William Gilbert

text: published

entity_name: De Magnete

text: de Magnete

text: in 1600, he concluded that the Earth is magnetic and proposed the first hypothesis for the origin of this magnetism: permanent magnetism such as that found in

entity_name: Lodestone

text: lodestone

text: . In 1919,

text: Joseph Larmor

text: proposed that a

text: dynamo

text: might be generating the field. However, even after he advanced his hypothesis, some prominent scientists advanced alternative explanations.

text: Einstein

text: believed that there might be an asymmetry between the charges of the

text: electron

text: and

text: proton

text: so that the

text: Earth's magnetic field

text: would be produced by the entire Earth. The

text: Nobel Prize

text: winner

text: Patrick Blackett

text: did a series of experiments looking for a fundamental relation between

text: angular momentum

text: and

text: magnetic moment

text: , but found none.

text: While not constant but varying depending on latitude and altitude, the numerical value of the acceleration caused by Earth's gravity on the surface lies between 9.74 and 9.87, which is quite close to 10. This means that as a result of Newton's second law, the weight of a kilogram of mass on Earth's surface corresponds roughly to 10 newtons of force exerted on an object.

text: While not constant but varying depending on

text: latitude

text: and

text: altitude

text: , the numerical value of the

text: acceleration caused by Earth's gravity

text: on the surface lies between 9.74 and 9.87, which is quite close to 10. This means that as a result of

text: Newton's second law

text: , the weight of a kilogram of mass on Earth's surface corresponds roughly to 10

text: newtons

text: of force exerted on an object.

text: Venus is a planet with striking geology. Of all the other planets in the Solar System, it is the one nearest to Earth and most like it in terms of mass, but has no magnetic field or recognizable plate tectonic system. Much of the ground surface is exposed volcanic bedrock, some with thin and patchy layers of soil covering, in marked contrast with Earth, the Moon, and Mars. Some impact craters are present, but Venus is similar to Earth in that there are much fewer craters than on the other rocky planets that are largely covered by them. This is due in part to the thickness of the Venusian atmosphere disrupting small impactors before they strike the ground, but the paucity of large craters may be due to volcanic re-surfacing, possibly of a catastrophic nature. Volcanism appears to be the dominant agent of geological change on Venus. Some of the volcanic landforms appear to be unique to the planet. There are shield and composite volcanoes similar to those found on Earth. Given that Venus has approximately the same size, density, and composition as Earth, it is plausible that volcanism may be continuing on the planet today, although convincing direct observations of a volcanic eruption have not yet occurred, leaving modern volcanism an open question.

text: Venus is a

text: planet

text: with striking

text: geology

text: . Of all the other planets in the Solar System, it is the one nearest to Earth and most like it in terms of mass, but has no magnetic field or recognizable

text: plate tectonic

text: system. Much of the ground surface is exposed volcanic bedrock, some with thin and patchy layers of soil covering, in marked contrast with Earth, the Moon, and Mars. Some impact craters are present, but Venus is similar to Earth in that there are much fewer craters than on the other rocky planets that are largely covered by them. This is due in part to the thickness of the Venusian atmosphere disrupting small impactors before they strike the ground, but the paucity of large craters may be due to volcanic re-surfacing, possibly of a catastrophic nature. Volcanism appears to be the dominant agent of geological change on Venus. Some of the volcanic landforms appear to be unique to the planet. There are

text: shield

text: and

text: composite

text: volcanoes similar to those found on Earth. Given that Venus has approximately the same size, density, and composition as Earth, it is plausible that volcanism may be continuing on the planet today, although convincing direct observations of a volcanic eruption have not yet occurred, leaving modern volcanism an open question.

text: The Martian year comprises 687 Martian days, each of which is 24 hours and 37 minutes long. (Burroughs presumably derived this from the figures published by Lowell, but erroneously substituted the number of 24-hour Earth days in the Martian year, rather than the number of 24.6-hour Martian days, which is only 669.) The days are hot (again known to be false) and the nights are cold, and there appears to be little variation in climate across the planet except at the poles.

text: The Martian year comprises 687 Martian days, each of which is 24 hours and 37 minutes long. (Burroughs presumably derived this from the figures published by Lowell, but erroneously substituted the number of 24-hour Earth days in the Martian year, rather than the number of 24.6-hour

text: Martian days

text: , which is only 669.) The days are hot (again known to be false) and the nights are cold, and there appears to be little variation in climate across the planet except at the poles.

text: As it is typical for supermassive planets, this orbits further from its host star than Earth is from the Sun. The planet’s year is over three Earth years. However, the orbital eccentricity of this object is much greater than Earth's: 0.1 vs. 0.017. Like most known extrasolar planets, it was detected by the wobble method, which detects planets through the circular wobbling motion of the star caused by the gravity of orbiting body.

text: As it is typical for supermassive planets, this orbits further from its host star than Earth is from the Sun. The planet’s year is over three Earth years. However, the

text: orbital eccentricity

text: of this object is much greater than Earth's: 0.1 vs. 0.017. Like most known extrasolar planets, it was detected by the

text: wobble method

text: , which detects planets through the circular wobbling motion of the star caused by the gravity of orbiting body.

text: This spectral range probably accounts for between 5% and 10% of stars in the local Milky Way galaxy. Whether fainter late K and M class red dwarf stars are also suitable hosts for habitable planets is perhaps the most important open question in the entire field of planetary habitability given their prevalence (habitability of red dwarf systems). Gliese 581 c, a "super-Earth", has been found orbiting in the "habitable zone" (HZ) of a red dwarf and may possess liquid water. However it is also possible that a greenhouse effect may render it too hot to support life, while its neighbor, Gliese 581 d, may be a more likely candidate for habitability. In September 2010, the discovery was announced of another planet, Gliese 581 g, in an orbit between these two planets. However, reviews of the discovery have placed the existence of this planet in doubt, and it is listed as "unconfirmed". In September 2012, the discovery of two planets orbiting Gliese 163 was announced. One of the planets, Gliese 163 c, about 6.9 times the mass of Earth and somewhat hotter, was considered to be within the habitable zone.

text: This spectral range probably accounts for between 5% and 10% of stars in the local

text: Milky Way galaxy

text: . Whether fainter late K and M class

text: red dwarf

text: stars are also suitable hosts for habitable planets is perhaps the most important open question in the entire field of planetary habitability given their prevalence (

text: habitability of red dwarf systems

text: Gliese 581 c

text: , a "

text: super-Earth

text: ", has been found orbiting in the "

text: habitable zone

text: " (HZ) of a

text: red dwarf

text: and may possess liquid water. However it is also possible that a greenhouse effect may render it too hot to support life, while its neighbor,

text: Gliese 581 d

text: , may be a more likely candidate for habitability. In September 2010, the discovery was announced of another planet,

text: Gliese 581 g

text: , in an orbit between these two planets. However, reviews of the discovery have placed the existence of this planet in doubt, and it is listed as "unconfirmed". In September 2012, the discovery of two planets orbiting

text: Gliese 163

text: was announced. One of the planets,

text: Gliese 163 c

text: , about 6.9 times the mass of Earth and somewhat hotter, was considered to be within the habitable zone.

text: Cosmic pluralism, the plurality of worlds, or simply pluralism, describes the philosophical belief in numerous "worlds" (planets, dwarf planets or natural satellites) in addition to Earth (possibly an infinite number), which may harbour extraterrestrial life.

text: Cosmic pluralism, the plurality of worlds, or simply pluralism, describes the philosophical belief in numerous "

text: world

text: s" (

text: planet

text: s,

text: dwarf planet

text: s or

text: natural satellite

text: s) in addition to

text: Earth

text: (possibly an infinite number), which may harbour

text: extraterrestrial life

text: The time of sunset varies throughout the year, and is determined by the viewer's position on Earth, specified by longitude and latitude, and elevation. Small daily changes and noticeable semi-annual changes in the timing of sunsets are driven by the axial tilt of Earth, daily rotation of the Earth, the planet's movement in its annual elliptical orbit around the Sun, and the Earth and Moon's paired revolutions around each other. During winter and spring, the days get longer and sunsets occur later every day until the day of the latest sunset, which occurs after the summer solstice. In the Northern Hemisphere, the latest sunset occurs late in June or in early July, but not on the summer solstice of June 21. This date depends on the viewer's latitude (connected with the Earth's slower movement around the aphelion around July 4). Likewise, the earliest sunset does not occur on the winter solstice, but rather about two weeks earlier, again depending on the viewer's latitude. In the Northern Hemisphere, it occurs in early December or late November (influenced by the Earth's faster movement near its perihelion, which occurs around January 3).

text: The time of sunset varies throughout the year, and is determined by the viewer's position on Earth, specified by longitude and latitude, and elevation. Small daily changes and noticeable semi-annual changes in the timing of sunsets are driven by the axial tilt of Earth, daily rotation of the Earth, the planet's movement in its annual elliptical orbit around the Sun, and the Earth and Moon's paired revolutions around each other. During winter and spring, the days get longer and sunsets occur later every day until the day of the latest sunset, which occurs after the summer solstice. In the

text: Northern Hemisphere

text: , the latest sunset occurs late in June or in early July, but not on the summer solstice of June 21. This date depends on the viewer's latitude (connected with the Earth's slower movement around the

text: aphelion

text: around July 4). Likewise, the earliest sunset does not occur on the winter solstice, but rather about two weeks earlier, again depending on the viewer's latitude. In the Northern Hemisphere, it occurs in early December or late November (influenced by the Earth's faster movement near its

text: perihelion

text: , which occurs around January 3).

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: The 186-day period planet orbits about 83% the Earth-Sun distance from the giant star 14 Andromedae. It has a minimum mass 4.8 times the mass of Jupiter. The planet orbits with an eccentricity of 0.0094, which means the orbital distance over the course of its revolution varies by only 0.02 AU. This planet was discovered on July 3, 2008 by Sato et al., who discovered the wobbling of 14 Andromedae caused by the planet’s gravity during its orbit with the Doppler spectroscopy.

text: The 186-day period planet orbits about 83% the

text: Earth

text: Sun

text: distance from the giant star

text: 14 Andromedae

text: . It has a

text: minimum mass

text: 4.8 times the mass of

text: Jupiter

text: . The planet orbits with an eccentricity of 0.0094, which means the orbital distance over the course of its revolution varies by only 0.02

text: AU

text: . This planet was discovered on July 3, 2008 by Sato et al., who discovered the wobbling of 14 Andromedae caused by the planet’s gravity during its orbit with the

text: Doppler spectroscopy

text: Jochen and Michael watch the stars one night, because they make an eerie acquaintance. Suddenly, an old man, who introduces himself as Lodeweik (Rudolf Schündler), with an odd little tree space. He tells them that he had come from the planet Krypton to Earth and need help, because destroying the planet Krypton. Xenon wanted and that even the whole earth was in danger. Next he tells of the conflict between Krypton, a planet of cold and Xenon, on a scorching heat prevails. As it turns out, are Mrs. Markward and her mysterious companion Tobias emissaries of the planet Xenon, to pursue and make the Lodeweik. For Earth, they are planning a series of disasters, and use the chemical plant as a secret base. In the shop of Glasuscheck is an old mirror, which can move with Markward and Tobias through time. It starts a wild chase to Lodeweik. Even Mr. Feucht, father of Jochen, is increasingly recognizing the threat posed particularly by the power plant, and is working diligently to find a solution. He brings himself into trouble and escapes an assault. Michael and Jochen are Lodeweik's friends with this and try to help as far as they can.

text: Jochen and Michael watch the stars one night, because they make an eerie acquaintance. Suddenly, an old man, who introduces himself as Lodeweik (

text: Rudolf Schündler

text: ), with an odd little tree space. He tells them that he had come from the planet Krypton to Earth and need help, because destroying the planet Krypton. Xenon wanted and that even the whole earth was in danger. Next he tells of the conflict between Krypton, a planet of cold and Xenon, on a scorching heat prevails. As it turns out, are Mrs. Markward and her mysterious companion Tobias emissaries of the planet Xenon, to pursue and make the Lodeweik. For Earth, they are planning a series of disasters, and use the chemical plant as a secret base. In the shop of Glasuscheck is an old mirror, which can move with Markward and Tobias through time. It starts a wild chase to Lodeweik. Even Mr. Feucht, father of Jochen, is increasingly recognizing the threat posed particularly by the power plant, and is working diligently to find a solution. He brings himself into trouble and escapes an assault. Michael and Jochen are Lodeweik's friends with this and try to help as far as they can.

text: The Magnet Men are evil people from another planet. Underdog defeats them when they make the Earth cold.

text: We will consider here a gyrocompass, as a gyroscope which is free to rotate about one of its symmetry axis, and the whole rotating gyroscope is also free to rotate on the horizontal plane, about the local vertical, the zenith. Therefore there are two independent local rotations. In addition to these rotations we will also consider the rotation of the Earth about its North-South (NS) axis, and we will model the planet as a perfect sphere. We will neglect friction and the rotation of the Earth about the Sun.

text: Observations with the HARPS spectrograph could not confirm the 10.24-day variation. Instead, two other periodicities were detected at 8.78 and 40.0 days, with amplitudes below the HET observational errors. The 40-day variation coincides with the rotational period of the star and is therefore caused by activity, but the shorter-period variation is not explained by activity and is therefore caused by a planet. Its semi-amplitude of 4.1 m/s corresponds to a minimum mass of 8.4 Earth masses, making the planet a Super-Earth.

text: Observations with the

entity_name: High Accuracy Radial Velocity Planet Searcher

text: HARPS

text: spectrograph could not confirm the 10.24-day variation. Instead, two other periodicities were detected at 8.78 and 40.0 days, with amplitudes below the HET observational errors. The 40-day variation coincides with the rotational period of the star and is therefore caused by activity, but the shorter-period variation is not explained by activity and is therefore caused by a planet. Its semi-amplitude of 4.1 m/s corresponds to a minimum mass of 8.4 Earth masses, making the planet a Super-Earth.

text: The Earth's naturally varying electric and magnetic fields are measured over a wide range of magnetotelluric frequencies from 10,000 Hz to 0.0001 Hz (10,000 s). These fields are due to electric currents flowing in the Earth and the magnetic fields that induce these currents. The magnetic fields are produced mainly by the interaction between the solar wind and the magnetosphere. In addition, worldwide thunderstorm activity causes magnetic fields at frequencies above 1 Hz. Combined, these natural phenomena create strong MT source signals over the entire frequency spectrum.

text: The Earth's naturally varying electric and

text: magnetic fields

text: are measured over a wide range of magnetotelluric frequencies from 10,000 Hz to 0.0001 Hz (10,000 s). These fields are due to electric currents flowing in the Earth and the magnetic fields that induce these currents. The magnetic fields are produced mainly by the interaction between the

text: solar wind

text: and the

text: magnetosphere

text: . In addition, worldwide

text: thunderstorm

text: activity causes magnetic fields at frequencies above 1 Hz. Combined, these natural phenomena create strong MT source signals over the entire frequency spectrum.

text: The gravitational attraction of the Sun and Moon on the Earth's equatorial bulge cause the rotational axis of the Earth to precess in space similar to the action of a top. This is called precession. Nutation is the smaller amplitude shorter-period (< 18.6 years) wobble that is superposed on the precessional motion of the Celestial pole. It is due to shorter-period fluctuations in the strength of the torque exerted on Earth's equatorial bulge by the sun, moon, and planets. When the short-term periodic oscillations of this motion are averaged out, they are considered "mean" as opposed to "true" values.  Thus, the vernal equinox, the equatorial plane of the Earth, and the ecliptic plane vary according to date and are specified for a particular epoch.  Models representing the ever-changing orientation of the Earth in space are available from the International Earth Rotation and Reference Systems Service.

text: The gravitational attraction of the Sun and Moon on the Earth's equatorial bulge cause the rotational axis of the Earth to precess in space similar to the action of a top. This is called

text: precession

text: Nutation

text: is the smaller amplitude shorter-period (< 18.6 years) wobble that is superposed on the precessional motion of the

text: Celestial pole

text: . It is due to shorter-period fluctuations in the strength of the torque exerted on Earth's equatorial bulge by the sun, moon, and planets. When the short-term periodic oscillations of this motion are averaged out, they are considered "mean" as opposed to "true" values.  Thus, the vernal equinox, the equatorial plane of the Earth, and the ecliptic plane vary according to date and are specified for a particular

text: epoch

text: .  Models representing the ever-changing orientation of the Earth in space are available from the

entity_name: International Earth Rotation and Reference Systems Service

text: International Earth Rotation and Reference Systems Service

text: Titan orbits Saturn once every 15 days and 22 hours. Like the Moon and many of the satellites of the giant planets, its rotational period (its day) is identical to its orbital period; Titan is thus tidally locked in synchronous rotation with Saturn, and permanently shows one face to the planet, hence, Titan's "day" is equal to its orbit period. Because of this, there is a sub-Saturnian point on its surface, from which the planet would always appear to hang directly overhead. Longitudes on Titan are measured westward, starting from the meridian passing through this point. Its orbital eccentricity is 0.0288, and the orbital plane is inclined 0.348 degrees relative to the Saturnian equator. Viewed from Earth, Titan reaches an angular distance of about 20 Saturn radii (just over ) from Saturn and subtends a disk 0.8 arcseconds in diameter.

text: Titan orbits Saturn once every 15 days and 22 hours. Like the

text: Moon

text: and many of the satellites of the

text: giant planet

text: s, its

text: rotational period

text: (its day) is identical to its orbital period; Titan is thus

text: tidally locked

text: in

text: synchronous rotation

text: with Saturn, and permanently shows one face to the planet, hence, Titan's "day" is equal to its orbit period. Because of this, there is a sub-Saturnian point on its surface, from which the planet would always appear to hang directly overhead. Longitudes on Titan are measured westward, starting from the meridian passing through this point. Its orbital eccentricity is 0.0288, and the orbital plane is inclined 0.348 degrees relative to the Saturnian equator. Viewed from Earth, Titan reaches an angular distance of about 20 Saturn radii (just over ) from Saturn and subtends a disk 0.8

text: arcsecond

text: s in diameter.

text: Kepler-186f's axial tilt (obliquity) is likely very small, in which case it would not have tilt-induced seasons as Earth and Mars do. Its orbit is probably close to circular, so it will also lack eccentricity-induced seasonal changes like those of Mars. However, the axial tilt could be larger (about 23 degrees) if another undetected nontransiting planet orbits between it and Kepler-186e; planetary formation simulations have shown that the presence of at least one additional planet in this region is likely. If such a planet exists, it cannot be much more massive than Earth as it would then cause orbital instabilities.

text: axial tilt

text: (obliquity) is likely very small, in which case it would not have tilt-induced seasons as Earth and Mars do. Its orbit is probably close to circular, so it will also lack eccentricity-induced seasonal changes like those of

text: Mars

text: . However, the axial tilt could be larger (about 23 degrees) if another undetected nontransiting planet orbits between it and Kepler-186e; planetary formation simulations have shown that the presence of at least one additional planet in this region is likely. If such a planet exists, it cannot be much more massive than Earth as it would then cause orbital instabilities.

text: The planet was originally called "New Earth", which later became "Nu-Earth" as it was an Earth-like paradise before the war started. Many of its place names have the prefix 'Nu-', i.e. Nu-Atlanta.

text: The planet was originally called "New Earth", which later became "Nu-Earth" as it was an Earth-like

text: paradise

text: before the war started. Many of its place names have the prefix 'Nu-', i.e. Nu-Atlanta.

text: The dipole model of the Earth's magnetic field is a first order approximation of the rather complex true Earth's magnetic field.  Due to effects of the interplanetary magnetic field, and the solar wind, the dipole model is particularly inaccurate at high L-shells (e.g., above L=3), but may be a good approximation for lower L-shells.  For more precise work, or for any work at higher L-shells, a more accurate model that incorporates solar effects, such as the Tsyganenko magnetic field model, is recommended.

text: The dipole model of the Earth's magnetic field is a first order approximation of the rather complex true

text: Earth's magnetic field

text: .  Due to effects of the

text: interplanetary magnetic field

text: , and the

text: solar wind

text: , the dipole model is particularly inaccurate at high

text: L-shell

text: s (e.g., above L=3), but may be a good approximation for lower L-shells.  For more precise work, or for any work at higher L-shells, a more accurate model that incorporates solar effects, such as the

text: Tsyganenko magnetic field model

text: , is recommended.

text: The chimps then discover that Kilowatt has survived, and they are able to make contact with Comet and Houston back on Earth through a walkie-talkie. Houston reminds them that if they can redesign the probe, then they can use it to get back to Earth. They manage to do this with help from the planet's inhabitants and they use an erupting volcano to get the thrust they need to escape the planet's gravity. They go into space, and just as they are about to re-enter the wormhole, Titan hands the controls over to Ham, since Ham is the only one who can withstand the pressure, and thus, the only one who can pilot the ship home. Titan and Luna once again pass out. Ham is unsure if he is up to the task until he has a mental conversation with his grandfather, who tells him to believe in himself and to just do things his (Ham's) way.

text: An equatorial bulge is a difference between the equatorial and polar diameters of a planet, due to the force exerted by its rotation.  A rotating body tends to form an oblate spheroid rather than a sphere.  The Earth has an equatorial bulge of : that is, its diameter measured across the equatorial plane () is 42.77 km more than that measured between the poles (). An observer standing at sea level on either pole, therefore, is 21.36 km closer to Earth's centrepoint than if standing at sea level on the equator. The value of Earth's radius may be approximated by the average of these radii.

text: An equatorial bulge is a difference between the equatorial and polar

text: diameter

text: s of a planet, due to the force exerted by its

text: rotation

text: .  A rotating body tends to form an

text: oblate spheroid

text: rather than a

text: sphere

text: .  The

text: Earth

text: has an equatorial bulge of : that is, its diameter measured across the equatorial plane () is 42.77 km more than that measured between the poles (). An observer standing at sea level on either pole, therefore, is 21.36 km closer to

text: Earth's centrepoint

text: than if standing at sea level on the equator. The value of Earth's radius may be approximated by the average of these radii.

text: The gravitational attraction between Earth and the Moon causes tides on Earth. The same effect on the Moon has led to its tidal locking: its rotation period is the same as the time it takes to orbit Earth. As a result, it always presents the same face to the planet. As the Moon orbits Earth, different parts of its face are illuminated by the Sun, leading to the lunar phases; the dark part of the face is separated from the light part by the solar terminator.

text: The gravitational attraction between Earth and the Moon causes

text: tide

text: s on Earth. The same effect on the Moon has led to its

text: tidal locking

text: : its rotation period is the same as the time it takes to orbit Earth. As a result, it always presents the same face to the planet. As the Moon orbits Earth, different parts of its face are illuminated by the Sun, leading to the

text: lunar phase

text: s; the dark part of the face is separated from the light part by the

text: solar terminator

text: Every planet has geographical poles. If, like the Earth, a body generates a magnetic field, it will also possess magnetic poles.

text: Every planet has geographical poles. If, like

text: the Earth

text: , a body generates a

text: magnetic field

text: , it will also possess

text: magnetic poles

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 bulk composition of the Earth by elemental-mass is roughly similar to the gross composition of the solar system, with the major differences being that Earth is missing a great deal of the volatile elements hydrogen, helium, neon, and nitrogen, as well as carbon which has been lost as volatile hydrocarbons. The remaining elemental composition is roughly typical of the "rocky" inner planets, which formed in the thermal zone where solar heat drove volatile compounds into space. The Earth retains oxygen as the second-largest component of its mass (and largest atomic-fraction), mainly from this element being retained in silicate minerals which have a very high melting point and low vapor pressure.

text: The bulk composition of the Earth by elemental-mass is roughly similar to the gross composition of the solar system, with the major differences being that Earth is missing a great deal of the volatile elements hydrogen, helium, neon, and nitrogen, as well as carbon which has been lost as volatile hydrocarbons. The remaining elemental composition is roughly typical of the "rocky" inner planets, which formed in the thermal zone where solar heat drove volatile compounds into space. The Earth retains oxygen as the second-largest component of its mass (and largest atomic-fraction), mainly from this element being retained in

text: silicate minerals

text: which have a very high melting point and low vapor pressure.

text: Haumea is a plutoid, a dwarf planet beyond Neptune's orbit. Its classification as a dwarf planet means it is presumed to be massive enough to have been rounded by its own gravity into a shape in hydrostatic equilibrium, but not massive enough to have cleared its neighbourhood of similar objects.  Haumea appears to have a triaxial ellipsoid shape resulting its rapid rotation complicated by tidal interactions with its moons.  This contrasts with the simpler oblate shape typically assumed by less rapidly rotating astronomical bodies such as the Earth, Jupiter (or a water balloon tossed with moderate spin).  Like the earth, Haumea is flattened at the poles (indeed much more so), but its equator, instead of being round like the Earth's, is elliptical, with two big bulges 180 degrees apart in longitude, buoyed up, as it were, by the greater centrifugal force they experience by virtue of being farther from the axis of rotation.  In other words, Haumea is spinning so fast that if it spun much faster these bulges would distort into a dumbbell shape and split the planet in two. Haumea was initially listed as a classical Kuiper belt object in 2006 by the Minor Planet Center, but no longer. The nominal trajectory suggests that it is in the weak 7:12 resonance with Neptune (orbiting the Sun 7 times for every 12 orbits of Neptune), because its perihelion distance of 35 AU is near the limit of stability with Neptune. There are precovery images of Haumea dating back to March 22, 1955 from the Palomar Mountain Digitized Sky Survey. Further observations of the orbit will be required to verify its dynamic status.

text: Haumea is a

text: plutoid

text: , a

text: dwarf planet

text: beyond Neptune's orbit. Its classification as a dwarf planet means it is presumed to be massive enough to have been rounded by its own gravity into a shape in hydrostatic equilibrium, but not massive enough to have

text: cleared its neighbourhood

text: of similar objects.  Haumea appears to have a triaxial

text: ellipsoid

text: shape resulting its rapid

text: rotation

text: complicated by tidal interactions with its moons.  This contrasts with the simpler

text: oblate

text: shape typically assumed by less rapidly rotating astronomical bodies such as the Earth, Jupiter (or a

text: water balloon

text: tossed with moderate spin).  Like the earth, Haumea is flattened at the poles (indeed much more so), but its equator, instead of being round like the Earth's, is elliptical, with two big bulges 180 degrees apart in longitude, buoyed up, as it were, by the greater centrifugal force they experience by virtue of being farther from the axis of rotation.  In other words, Haumea is spinning so fast that if it spun much faster these bulges would distort into a dumbbell shape and split the planet in two. Haumea was initially listed as a classical Kuiper belt object in 2006 by the

text: Minor Planet Center

text: , but no longer. The nominal trajectory suggests that it is in the weak 7:12

text: resonance with Neptune

text: (orbiting the Sun 7 times for every 12 orbits of Neptune), because its

text: perihelion

text: distance of 35 AU is near the

text: limit of stability

text: with Neptune. There are

text: precovery

text: images of Haumea dating back to March 22, 1955 from the

text: Palomar Mountain

text: Digitized Sky Survey

text: . Further observations of the orbit will be required to verify its dynamic status.

text: The fifth season of Keeping Up with the Kardashians began airing on August 22, 2010 and concluded with another "Junk in the Trunk" episode on December 20. The sixth season commenced on June 12, 2011 and ended with a television special "Kim's Fairytale Wedding: A Kardashian Event" which aired two extended episodes on October 9 and 10. The show later returned on December 19 with the episode "Kendall's Sweet 16". Starting with the seventh season, which premiered on May 20, 2012, the half-hour reality series was extended to a full hour in a new 9:00/8:00 pm time slot. The season concluded on October 28. The eighth season of the series started airing on June 2, 2013; it became the longest season with 21 episodes and ended on December 1. The ninth and tenth seasons aired in 2014 and 2015, respectively. The latter season included a television special entitled "About Bruce" which aired on May 17 and 18, 2015. The eleventh season premiered on November 15, one month after the previous season finished. The twelfth season of the show debuted on May 1, 2016.

text: The fifth season of Keeping Up with the Kardashians began airing on August 22, 2010 and concluded with another "

entity_name: List of Keeping Up with the Kardashians episodes

text: Junk in the Trunk

text: " episode on December 20. The sixth season commenced on June 12, 2011 and ended with a television special "

text: Kim's Fairytale Wedding: A Kardashian Event

text: " which aired two extended episodes on October 9 and 10. The show later returned on December 19 with the episode "

text: Kendall's Sweet 16

text: ". Starting with the seventh season, which premiered on May 20, 2012, the half-hour reality series was extended to a full hour in a new 9:00/8:00 pm time slot. The season concluded on October 28. The eighth season of the series started airing on June 2, 2013; it became the longest season with 21 episodes and ended on December 1. The ninth and tenth seasons aired in 2014 and 2015, respectively. The latter season included a television special entitled "

text: About Bruce

text: " which aired on May 17 and 18, 2015. The eleventh season premiered on November 15, one month after the previous season finished. The twelfth season of the show debuted on May 1, 2016.

text: The Moon is a relatively large, terrestrial, planet-like natural satellite, with a diameter about one-quarter of Earth's. It is the largest moon in the Solar System relative to the size of its planet, although Charon is larger relative to the dwarf planet Pluto. The natural satellites of other planets are also referred to as "moons", after Earth's.

text: The Moon is a relatively large,

text: terrestrial

text: , planet-like

text: natural satellite

text: , with a diameter about one-quarter of Earth's. It is the largest moon in the Solar System relative to the size of its planet, although

text: Charon

text: is larger relative to the

text: dwarf planet

text: Pluto

text: . The natural satellites of other planets are also referred to as "moons", after Earth's.

text: The extended night version of "Girls on Film", similar to "Planet Earth" wasn't a remix, but a completely new arrangement of the song.

text: The extended night version of "Girls on Film", similar to "

text: Planet Earth

text: " wasn't a remix, but a completely new arrangement of the song.

text: The magnetic field of the Earth, and of other planets that have magnetic fields, is generated by dynamo action in which convection of molten iron in the planetary core generates electric currents which in turn give rise to magnetic fields. In simulations of planetary dynamos, reversals often emerge spontaneously from the underlying dynamics. For example, Gary Glatzmaier and collaborator Paul Roberts of UCLA ran a numerical model of the coupling between electromagnetism and fluid dynamics in the Earth's interior. Their simulation reproduced key features of the magnetic field over more than 40,000 years of simulated time and the computer-generated field reversed itself. Global field reversals at irregular intervals have also been observed in the laboratory liquid metal experiment VKS2.

text: The magnetic field of the Earth, and of other planets that have magnetic fields, is generated by

text: dynamo action

text: in which convection of molten iron in the planetary core generates electric currents which in turn give rise to magnetic fields. In

text: simulations

text: of planetary dynamos, reversals often emerge spontaneously from the underlying dynamics. For example, Gary Glatzmaier and collaborator Paul Roberts of

text: UCLA

text: ran a numerical model of the coupling between electromagnetism and fluid dynamics in the Earth's interior. Their simulation reproduced key features of the magnetic field over more than 40,000 years of simulated time and the computer-generated field reversed itself. Global field reversals at irregular intervals have also been observed in the laboratory

text: liquid

text: metal

text: experiment

text: In contrast to the previously bleak picture for life, 1997 studies by Robert Haberle and Manoj Joshi of NASA's Ames Research Center in California have shown that a planet's atmosphere (assuming it included greenhouse gases CO and HO) need only be 100 millibar, or 10% of Earth's atmosphere, for the star's heat to be effectively carried to the night side, a figure well within the bounds of photosynthesis. Research two years later by Martin Heath of Greenwich Community College has shown that seawater, too, could effectively circulate without freezing solid if the ocean basins were deep enough to allow free flow beneath the night side's ice cap. Additionally, a 2010 study concluded that Earth-like water worlds tidally locked to their stars would still have temperatures above  on the night side. Climate models constructed in 2013 indicate that cloud formation on tidally locked planets would minimize the temperature difference between the day and the night side, greatly improving habitability prospects for red dwarf planets. Further research, including a consideration of the amount of photosynthetically active radiation, has suggested that tidally locked planets in red dwarf systems might at least be habitable for higher plants.

text: In contrast to the previously bleak picture for life, 1997 studies by Robert Haberle and Manoj Joshi of

text: NASA

text: 's

text: Ames Research Center

text: in California have shown that a planet's atmosphere (assuming it included greenhouse gases

text: CO

text: and

text: HO

text: ) need only be 100 milli

text: bar

text: , or 10% of Earth's atmosphere, for the star's heat to be effectively carried to the night side, a figure well within the bounds of photosynthesis. Research two years later by Martin Heath of

text: Greenwich Community College

text: has shown that seawater, too, could effectively circulate without freezing solid if the ocean basins were deep enough to allow free flow beneath the night side's ice cap. Additionally, a 2010 study concluded that Earth-like

text: water worlds

text: tidally locked to their stars would still have temperatures above  on the night side. Climate models constructed in 2013 indicate that cloud formation on tidally locked planets would minimize the temperature difference between the day and the night side, greatly improving habitability prospects for red dwarf planets. Further research, including a consideration of the amount of photosynthetically active radiation, has suggested that tidally locked planets in red dwarf systems might at least be habitable for higher plants.

text: This large spinning mass of super-hot metal is responsible for the magnetosphere, which protects the Earth from solar wind and the most harmful components of solar radiation coming from our Sun. The magnetosphere protects both Earth's atmosphere and life to the present day and distinguishes the planet from its close celestial neighbour, Mars, which no longer has a significant magnetic field nor comparable atmosphere.  The term catastrophe is, here, in the mathematical sense of "a large, sudden change or discontinuity", as contrasted with "a disaster", because this event was necessary for life to emerge and evolve on Earth: without it, Earth's atmosphere would have been, as on Mars, stripped away by solar wind long before the present epoch.

text: This large spinning mass of super-hot metal is responsible for the

text: magnetosphere

text: , which protects the Earth from

text: solar wind

text: and the most harmful components of

text: solar radiation

text: coming from our

text: Sun

text: . The magnetosphere protects both

text: Earth's atmosphere

text: and

text: life

text: to the present day and distinguishes the planet from its close celestial neighbour,

text: Mars

text: , which no longer has a significant magnetic field nor comparable atmosphere.  The term catastrophe is, here, in the mathematical sense of "a large, sudden change or discontinuity", as contrasted with "a disaster", because this event was necessary for life to emerge and evolve on Earth: without it, Earth's atmosphere would have been, as on Mars, stripped away by solar wind long before the present epoch.

text: , of an oblate spheroid (similar to the shape of the planet Earth) is:

text: , of an

text: oblate spheroid

text: (similar to the shape of the planet

text: Earth

text: ) is:

text: In 2015, two planets were discovered around WASP-47. One was potentially a large terrestrial planet, with less than 22 Earth masses and 1.8 Earth radii, the other is of similar mass at 15.2 Earth masses but with 3.6 Earth radii it is almost certainly a gas giant. They orbit on either side of a previously discovered hot Jupiter, the smaller, terrestrial planet closer in. A similar orbital architecture is also exhibited by the Kepler-30 system.

text: A related problem is that of centrifugal forces for the Earth-Moon-Sun system, where three rotations appear: the daily rotation of the Earth about its axis, the lunar-month rotation of the Earth-Moon system about their center of mass, and the annual revolution of the Earth-Moon system about the Sun. These three motions influence the tides.

text: A related problem is that of centrifugal forces for the Earth-Moon-Sun system, where three rotations appear: the daily rotation of the Earth about its axis, the lunar-month rotation of the Earth-Moon system about their center of mass, and the annual revolution of the Earth-Moon system about the Sun. These three motions influence the

text: tides

text: The COROT team then published a second paper on COROT-7b's mass, removing stellar activity through analysis only of radial velocity data for which multiple measurements were taken in a given night. The planet is weighed at 7.42 Earth masses, yielding an average density of 10.4 ± 1.8 g cm, far higher than the Earth's and similar to that of the second rocky planet found, Kepler-10b.

text: The COROT team then published a second paper on COROT-7b's mass, removing stellar activity through analysis only of radial velocity data for which multiple measurements were taken in a given night. The planet is weighed at 7.42 Earth masses, yielding an average density of 10.4 ± 1.8 g cm, far higher than the Earth's and similar to that of the second rocky planet found,

text: When DC made use of its multiverse means of continuity tracking between the early 1960s and mid-1980s, it was declared that the Daily Star was the newspapers name in the Golden Age or "Earth-Two" versions of Clark Kent, Lois Lane and Jimmy Olsen, while the Daily Planet was used in the Silver Age or "Earth-One" versions. The Clark Kent of Earth-Two eventually became the editor-in-chief of the Daily Star, something his Earth-One counterpart did not achieve.

text: When DC made use of its

text: multiverse

text: means of continuity tracking between the early 1960s and mid-1980s, it was declared that the Daily Star was the newspapers name in the

text: Golden Age

text: or "Earth-Two" versions of Clark Kent, Lois Lane and Jimmy Olsen, while the Daily Planet was used in the

text: Silver Age

text: or "Earth-One" versions. The

text: Clark Kent of Earth-Two

text: eventually became the editor-in-chief of the Daily Star, something his Earth-One counterpart did not achieve.

text: Wagner uses the metaphor of day and night in the second act to designate the realms inhabited by Tristan and Isolde. The world of Day is one in which the lovers are bound by the dictates of King Marke's court and in which the lovers must smother their mutual love and pretend as if they do not care for each other: it is a realm of falsehood and unreality. Under the dictates of the realm of Day, Tristan was forced to remove Isolde from Ireland and to marry her to his Uncle Marke – actions against Tristan's secret desires. The realm of Night, in contrast, is the representation of intrinsic reality, in which the lovers can be together and their desires can be openly expressed and reach fulfilment: it is the realm of oneness, truth and reality and can only be achieved fully upon the deaths of the lovers. The realm of Night, therefore, becomes also the realm of death: the only world in which Tristan and Isolde can be as one forever, and it is this realm that Tristan speaks of at the end of Act Two ("Dem Land das Tristan meint, der Sonne Licht nicht scheint"). In Act Three, Tristan rages against the daylight and frequently cries out for release from his desires (Sehnen). In this way, Wagner implicitly equates the realm of Day with Schopenhauer's concept of Phenomenon and the realm of Night with Schopenhauer's concept of Noumenon. While none of this is explicitly stated in the libretto, Tristan's comments on Day and Night in Acts 2 and 3, as well as musical allusions to "Tristan" in The Mastersingers of Nürnberg and Parsifal make it very clear that this was, in fact, Wagner's intention.

text: Wagner uses the metaphor of day and night in the second act to designate the realms inhabited by Tristan and Isolde. The world of Day is one in which the lovers are bound by the dictates of King Marke's court and in which the lovers must smother their mutual love and pretend as if they do not care for each other: it is a realm of falsehood and unreality. Under the dictates of the realm of Day, Tristan was forced to remove Isolde from Ireland and to marry her to his Uncle Marke – actions against Tristan's secret desires. The realm of Night, in contrast, is the representation of intrinsic reality, in which the lovers can be together and their desires can be openly expressed and reach fulfilment: it is the realm of oneness, truth and reality and can only be achieved fully upon the deaths of the lovers. The realm of Night, therefore, becomes also the realm of death: the only world in which Tristan and Isolde can be as one forever, and it is this realm that Tristan speaks of at the end of Act Two ("Dem Land das Tristan meint, der Sonne Licht nicht scheint"). In Act Three, Tristan rages against the daylight and frequently cries out for release from his desires (Sehnen). In this way, Wagner implicitly equates the realm of Day with Schopenhauer's concept of

text: Phenomenon

text: and the realm of Night with Schopenhauer's concept of

text: Noumenon

text: . While none of this is explicitly stated in the libretto, Tristan's comments on Day and Night in Acts 2 and 3, as well as musical allusions to "Tristan" in

text: The Mastersingers of Nürnberg

text: and

text: Parsifal

text: make it very clear that this was, in fact, Wagner's intention.

text: In the case of gravity on a planet surface, g(r) is simply the approximately constant and uniform gravitational field, like on Earth where:

text: In the case of gravity on a planet surface, g(r) is simply the approximately constant and uniform

text: gravitational field

text: , like on Earth where:

text: Magnetostratigraphy is a chronostratigraphic technique used to date sedimentary and volcanic sequences. The method works by collecting oriented samples at measured intervals throughout a section. The samples are analyzed to determine their detrital remanent magnetism (DRM), that is, the polarity of Earth's magnetic field at the time a stratum was deposited. For sedimentary rocks, this is possible because, when very fine-grained magnetic minerals (< 17 μm), behave like tiny compasses as they fall through the water column and orient themselves with Earth's magnetic field. Upon burial, that orientation is preserved.  For volcanic rocks, magnetic minerals, which form in the melt, orient themselves with the ambient magnetic field, and are fixed in place upon crystallization of the lava.

text: Magnetostratigraphy is a chronostratigraphic technique used to date sedimentary and volcanic sequences. The method works by collecting oriented samples at measured intervals throughout a section. The samples are analyzed to determine their detrital

text: remanent

text: magnetism (DRM), that is, the polarity of Earth's magnetic field at the time a stratum was deposited. For sedimentary rocks, this is possible because, when very fine-grained magnetic minerals (< 17

text: μm

text: ), behave like tiny compasses as they fall through the water column and orient themselves with

text: Earth's magnetic field

text: . Upon burial, that orientation is preserved.  For volcanic rocks, magnetic minerals, which form in the melt, orient themselves with the ambient magnetic field, and are fixed in place upon crystallization of the lava.

text: A geomagnetic storm is a temporary disturbance of the Earth's Magnetosphere caused by a solar wind shock wave and/or cloud of magnetic field that interacts with the Earth's magnetic field. The increase in solar wind pressure compresses the magnetosphere and the solar wind's magnetic field interacts with the Earth’s magnetic field to transfer increased energy into the magnetosphere.  Both interactions increase plasma movement through the magnetosphere (driven by increased electric fields) and an increase in electric current in the magnetosphere and ionosphere.

text: A geomagnetic storm is a temporary disturbance of the Earth's

text: Magnetosphere

text: caused by a

text: solar wind

text: shock wave and/or cloud of magnetic field that interacts with the

text: Earth's magnetic field

text: . The increase in solar wind pressure compresses the magnetosphere and the solar wind's magnetic field interacts with the Earth’s magnetic field to transfer increased energy into the magnetosphere.  Both interactions increase plasma movement through the magnetosphere (driven by increased electric fields) and an increase in electric current in the magnetosphere and ionosphere.

text: Transit-timing variation measurements indicate that Kepler-52b, Kepler-52c and Kepler-57b have maximum masses between 30 and 100 times that of Earth, although the actual masses could be much lower. With radii about 2 Earth radii in size, they might have densities larger than that of an iron planet of the same size. They orbit very close to their stars, so they could be the remnant cores (chthonian planets) of evaporated gas giants or brown dwarfs. If cores are massive enough they could remain compressed for billions of years despite losing the atmospheric mass.

text: Transit-timing variation

text: measurements indicate that Kepler-52b, Kepler-52c and Kepler-57b have maximum masses between 30 and 100 times that of Earth, although the actual masses could be much lower. With radii about 2 Earth radii in size, they might have densities larger than that of an

text: iron planet

text: of the same size. They orbit very close to their stars, so they could be the remnant cores (

text: chthonian planet

text: s) of evaporated

text: gas giant

text: s or

text: brown dwarf

text: s. If cores are massive enough they could remain compressed for billions of years despite losing the atmospheric mass.

text: With a minimum mass of about 5 Earth masses, the innermost planet falls into the regime of Super-Earths. The two outer planets straddle the commonly accepted upper limit between Super-Earths and Neptunes at , so they could be either predominantly rocky or gaseous. All three planets orbit within 0.5 AU and are likely too hot to maintain liquid water.

text: With a minimum mass of about 5 Earth masses, the innermost planet falls into the regime of

text: Super-Earth

text: s. The two outer planets straddle the commonly accepted upper limit between Super-Earths and Neptunes at , so they could be either predominantly rocky or gaseous. All three planets orbit within 0.5 AU and are likely too hot to maintain liquid water.

text: Discovered on 5 January 2010, a planet HD 156668 b with a minimum mass of 4.15 Earth masses, is the second least massive planet detected by the radial velocity method. The only confirmed radial velocity planet smaller than this planet is Gliese 581 e at 1.9 Earth masses (see above). On 24 August astronomers using ESO’s HARPS instrument announced the discovery of a planetary system with up to seven planets orbiting a Sun-like star, HD 10180, one of which, although not yet confirmed, has an estimated minimum mass of 1.35 ± 0.23 times that of Earth, which would be the lowest mass of any exoplanet found to date orbiting a main-sequence star. Although unconfirmed, there is 98.6% probability that this planet does exist.

text: Discovered on 5 January 2010, a planet

text: HD 156668 b

text: with a

text: minimum mass

text: of 4.15

text: Earth mass

text: es, is the second least massive planet detected by the

text: radial velocity method

text: . The only confirmed radial velocity planet smaller than this planet is Gliese 581 e at 1.9 Earth masses (see above). On 24 August astronomers using ESO’s HARPS instrument announced the discovery of a planetary system with up to seven planets orbiting a Sun-like star,

text: HD 10180

text: , one of which, although not yet confirmed, has an estimated minimum mass of 1.35 ± 0.23 times that of Earth, which would be the lowest mass of any exoplanet found to date orbiting a main-sequence star. Although unconfirmed, there is 98.6% probability that this planet does exist.

text: No transit-time variations have yet been found for this transit. As of 2012, "the given data does not allow us to conclude that there is a [second] planet in the mass range 0.1–5 Earth-masses and the period range 0.76–1.23 or 1.91–3.18 days."

text: Celestia also does not simulate gravity. That means, for example, that a near-Earth object approaching the Earth will not collide with the planet after being caught by the Earth's gravity unless the person who defined the NEO's trajectory for Celestia included that effect.

text: Celestia also does not simulate

text: gravity

text: . That means, for example, that a

text: near-Earth object

text: approaching the Earth will not collide with the planet after being caught by the Earth's gravity unless the person who defined the NEO's trajectory for Celestia included that effect.

text: The axial tilt of Neptune is 28.32°, which is similar to the tilts of Earth (23°) and Mars (25°). As a result, this planet experiences similar seasonal changes. The long orbital period of Neptune means that the seasons last for forty Earth years. Its sidereal rotation period (day) is roughly 16.11 hours. Because its axial tilt is comparable to Earth's, the variation in the length of its day over the course of its long year is not any more extreme.

text: Crutzen proposed the Industrial Revolution as the start of Anthropocene. Lovelock proposes that the Anthropocene began with the first application of the Newcomen atmospheric engine in 1712. Although it is apparent that the Industrial Revolution ushered in an unprecedented global human impact on the planet, much of Earth’s landscape already had been profoundly modified by human activities. The human impact on Earth has grown progressively, with few substantial slowdowns.

text: Crutzen proposed the

text: Industrial Revolution

text: as the start of Anthropocene. Lovelock proposes that the Anthropocene began with the first application of the

text: Newcomen atmospheric engine

text: in 1712. Although it is apparent that the Industrial Revolution ushered in an unprecedented global human impact on the planet, much of Earth’s landscape already had been profoundly modified by human activities. The human impact on Earth has grown progressively, with few substantial slowdowns.

text: The planet has three moons and is the third planet from its sun, providing a possible origin for their religious, cultural, and scientific fixation with the number three. The star around which the planet revolves is dying, which is the reason for the aliens leaving it to make refuge on Earth. Ironically, though they seek occupancy on Earth, the brightness of the sun is higher in contrast to their own, thus suffering from photophobia, made evident in their host bodies wearing sunglasses to aid them. The length of Mor-Tax's seasons and days are unknown. While it is stated the mating season is every nine years, it is not clarified if this is in reference to the time on Earth or on Mor-Tax.

text: The planet has three moons and is the third planet from its sun, providing a possible origin for their religious, cultural, and scientific fixation with the

text: number three

text: . The star around which the planet revolves is dying, which is the reason for the aliens leaving it to make refuge on Earth. Ironically, though they seek occupancy on Earth, the brightness of the sun is higher in contrast to their own, thus suffering from

text: photophobia

text: , made evident in their host bodies wearing sunglasses to aid them. The length of Mor-Tax's seasons and days are unknown. While it is stated the mating season is every nine years, it is not clarified if this is in reference to the time on Earth or on Mor-Tax.

text: It is an ellipsoid of revolution, whose short (polar) axis (connecting the two flattest spots called geographical north and south poles) is approximately aligned with the rotation axis of the Earth. The ellipsoid is defined by the equatorial axis a and the polar axis b; their difference is about 21 km or 0.335 percent. Additional parameters are the mass function J2, the correspondent gravity formula, and the rotation period (usually 86164 seconds).

text: It is an

text: ellipsoid of revolution

text: , whose short (polar) axis (connecting the two flattest spots called geographical north and south poles) is approximately aligned with the rotation axis of the Earth. The ellipsoid is defined by the equatorial axis a and the polar axis b; their difference is about 21 km or 0.335 percent. Additional parameters are the

text: mass function

text: J2, the correspondent

text: gravity

text: formula, and the rotation period (usually 86164 seconds).

text: Day & Night follows two characters, Day and Night. Inside Day is a day scene with a sun in the center, and inside Night is a night scene with a moon in the center.  Whatever goes on inside of Day or Night expresses normal events that typically occur within a day or night, respectively, and these events often correspond with actions or emotions or actions that Day or Night express. For example, when Day is happy he will have a rainbow inside him, and when Night is happy he will have fireworks inside him.

text: The vast amounts of data that his expeditions yielded were analyzed and discussed together with other leading Dutch Earth scientists of the time J.H.F. Umbgrove, B.G. Escher and Ph.H. Kuenen, the results were published in 1948. An important result was the discovery of elongated belts of negative gravity anomalies along the oceanic trenches. The mean gravity force appeared to be the same on land and at sea, which was in agreement with the principle of isostasy. Vening Meinesz was especially intrigued by the oceanic trenches. The coexisitence of active volcanism, large negative gravity anomalies and the sudden difference in terrain elevation could only be explained by assuming the Earth's crust was somehow pushed together at these places. As a geophysicist, he was prejudiced that the crust was too rigid to deform at that scale in such a way. His discoveries could be explained only with the development of the theory of plate tectonics in the '50s.

text: The vast amounts of data that his expeditions yielded were analyzed and discussed together with other leading Dutch

text: Earth scientists

text: of the time

text: J.H.F. Umbgrove

text: B.G. Escher

text: and

text: Ph.H. Kuenen

text: , the results were published in 1948. An important result was the discovery of elongated belts of negative

text: gravity anomalies

text: along the

text: oceanic trench

text: es. The mean gravity force appeared to be the same on land and at sea, which was in agreement with the principle of

text: isostasy

text: . Vening Meinesz was especially intrigued by the oceanic trenches. The coexisitence of active

text: volcanism

text: , large negative gravity anomalies and the sudden difference in terrain elevation could only be explained by assuming the

text: Earth's crust

text: was somehow pushed together at these places. As a geophysicist, he was prejudiced that the crust was too rigid to deform at that scale in such a way. His discoveries could be explained only with the development of the theory of

text: plate tectonics

text: in the '50s.

text: While tidal forces from the primary are common on satellites, most satellite systems remain stable.  Perturbation between satellites can occur, particularly in the early formation, as the gravity of satellites affect each other, and can result in ejection from the system or collisions between satellites or with the primary.  Simulations show that such interactions cause the orbits of the inner moons of the Uranus system to be chaotic and possibly unstable.  Some of Io's active can be explained by perturbation from Europa's gravity as their orbits resonate.Perturbation has been suggested as a reason that Neptune does not follow the 10,000:1 ratio of mass between the parent planet and collective moons as seen in all other known giant planets. One theory of the Earth-Moon system suggest that a second companion which formed at the same time as the Moon, was perturbed by the Moon early in the system's history, causing it to impact with the Moon.

text: While tidal forces from the primary are common on satellites, most satellite systems remain stable.

text: Perturbation

text: between satellites can occur, particularly in the early formation, as the gravity of satellites affect each other, and can result in ejection from the system or collisions between satellites or with the primary.  Simulations show that such interactions cause the orbits of the inner moons of the Uranus system to be chaotic and possibly unstable.  Some of Io's active can be explained by perturbation from Europa's gravity as their orbits resonate.Perturbation has been suggested as a reason that Neptune does not follow the 10,000:1 ratio of mass between the parent planet and collective moons as seen in all other known giant planets. One theory of the Earth-Moon system suggest that a second companion which formed at the same time as the Moon, was perturbed by the Moon early in the system's history, causing it to impact with the Moon.

text: The force of gravity on the surface of the Earth, normally denoted g, has remained constant in both direction and magnitude since the formation of the planet. As a result, both plant and animal life have evolved to rely upon and cope with it in various ways.

text: The force of gravity on the surface of the Earth, normally denoted

text: g

text: , has remained constant in both direction and magnitude since the formation of the planet. As a result, both

text: plant

text: and

text: animal

text: life have evolved to rely upon and cope with it in various ways.

text: After several missions with SG-1, Jonas is confronted with his past in "Shadow Play" and learns more of the effects of naqahdriah on people. In "Metamorphosis", the Goa'uld Nirrti learns via an Ancient DNA Resequencer that Jonas is different from other humans, but she is killed before this is further investigated. In "Prophecy", Nirrti's experiments cause clairvoyant visions in Jonas, and the doctors remove a potentially lethal tumor from his brain. After SG-1 finds the de-ascended Daniel on another planet in the season 7 premiere "Fallen"/"Homecoming", Jonas and Daniel join forces and succeed in driving Anubis away from Kelowna. The three Langaran nations agree to meet for peace talks for the greater good of the planet, and Jonas decides to become a peace negotiator for his people. While Jonas returns to his planet, Daniel rejoins SG-1. Jonas last appears in season 7's "Fallout" to ask Earth for help saving his homeworld from the destructive powers of naqahdriah in the planet's core. Season 10's "Counterstrike" mentions that the Ori conquered Langara, Jonas's homeworld. Langara's story arc is resumed in Stargate Universes "Seizure", where Earth eventually agrees to protect Langara from the Lucian Alliance, while the Langarans remove the Stargate from their facility.

text: After several missions with SG-1, Jonas is confronted with his past in "

text: Shadow Play

text: " and learns more of the effects of naqahdriah on people. In "

text: Metamorphosis

text: ", the Goa'uld

text: Nirrti

text: learns via an

text: Ancient

text: DNA Resequencer

text: that Jonas is different from other humans, but she is killed before this is further investigated. In "

text: Prophecy

text: ", Nirrti's experiments cause clairvoyant visions in Jonas, and the doctors remove a potentially lethal tumor from his brain. After SG-1 finds the

text: de-ascended

text: Daniel on another planet in the season 7 premiere "

text: Fallen

text: Homecoming

text: ", Jonas and Daniel join forces and succeed in driving Anubis away from Kelowna. The three Langaran nations agree to meet for peace talks for the greater good of the planet, and Jonas decides to become a peace negotiator for his people. While Jonas returns to his planet, Daniel rejoins SG-1. Jonas last appears in season 7's "

text: Fallout

text: " to ask Earth for help saving his homeworld from the destructive powers of naqahdriah in the planet's core. Season 10's "

text: Counterstrike

text: " mentions that the

text: Ori

text: conquered Langara, Jonas's homeworld. Langara's story arc is resumed in

text: Stargate Universe

text: s "Seizure", where Earth eventually agrees to protect Langara from the

text: Lucian Alliance

text: , while the Langarans remove the Stargate from their facility.

text: The events of the story unfold on Earth at some undisclosed era in the future when the planet has ceased to rotate, hence the opening line, "At Columbine Sept Heures it was always dusk."

text: The rotation of the Earth causes day and night. It is day on the part of the globe that is currently visible.The places on earth that pass under the fixed meridian (the golden belt running from the North Pole  to the South Pole) have noon at the same time. The globe rotates once every 24 hours.

text: The

text: rotation of the Earth

text: causes day and night. It is day on the part of the globe that is currently visible.The places on earth that pass under the fixed

text: meridian

text: (the golden belt running from the

text: North Pole

text: to the

text: South Pole

text: ) have noon at the same time. The globe rotates once every 24 hours.

text: The similar concept reused from the past series Ultraman Ginga and its successor, Ultraman Ginga S,  are the embodiments of Ultramen and other Ultra Monsters but unlike the aforementioned past series, instead of being figures that cursed into these dolls, they are OOPArts on Earth studied by several researchers, among them being Takashi Ozora, Daichi's father. As a result of the Ultra Flare, these Spark Dolls were given life as rampaging monsters in the worldwide which Xio fought till nowadays. Eventually, it is also revealed that Earth is not the only Planet with it. As shown, alien planets like Planet Gold developed their own Spark Doll, Rudian, which was used by the planet's royal prince, tE-rU. They were also seen as useful monster weapons sought by intergalactic outlaws like Alien Zarab, Alien Nackle Bandero and etc.

text: The similar concept reused from the past series

text: Ultraman Ginga

text: and its successor,

text: Ultraman Ginga S

text: ,  are the embodiments of Ultramen and other Ultra Monsters but unlike the aforementioned past series, instead of being figures that cursed into these dolls, they are

text: OOPArts

text: on Earth studied by several researchers, among them being Takashi Ozora, Daichi's father. As a result of the Ultra Flare, these Spark Dolls were given life as rampaging monsters in the worldwide which Xio fought till nowadays. Eventually, it is also revealed that Earth is not the only Planet with it. As shown, alien planets like Planet Gold developed their own Spark Doll, Rudian, which was used by the planet's royal prince, tE-rU. They were also seen as useful monster weapons sought by intergalactic outlaws like Alien Zarab, Alien Nackle Bandero and etc.

text: , there will be no Rossby Waves; Rossby Waves owe their origin to the gradient of the tangential speed of the planetary rotation (planetary vorticity). A "cylinder" planet has no Rossby Waves. It also means that at the equator of any rotating, sphere-like planet, including Earth, one will still have Rossby Waves, despite the fact that

text: Mariner 4 flew past Mars on July 14, 1965, providing the first close-up photographs of another planet. The pictures, gradually played back to Earth from a small tape recorder on the probe, showed impact craters.  It provided radically more accurate data about the planet; a surface atmospheric pressure of about 1% of Earth's and daytime temperatures of −100 °C (−148 °F) were estimated. No magnetic field or Martian radiation belts were detected. The new data meant redesigns for then planned Martian landers, and showed life would have a more difficult time surviving there than previously anticipated.

text: Mariner 4 flew past Mars on July 14, 1965, providing the first close-up photographs of another planet. The pictures, gradually played back to Earth from a small tape recorder on the probe, showed impact craters.  It provided radically more accurate data about the planet; a surface

text: atmospheric pressure

text: of about 1% of Earth's and daytime temperatures of −100 °C (−148 °F) were estimated. No

text: magnetic field

text: or

text: Martian radiation belts

text: were detected. The new data meant redesigns for then planned Martian landers, and showed life would have a more difficult time surviving there than previously anticipated.

text: The surface velocity due to the Earth's rotation is a maximum at the Equator and is equal to the circumference (pi × the diameter of the Earth) per 24 hours (or 3.14159 × 12,756 ÷ 24 = 1670 km/h = 1 equatorial velocity unit, EVU). The time of an Earth's rotation is inversely related to the angular velocity and the surface velocity (T = 1 day for 2 pi radians, or at the equator, 1 circumferential unit per 1 EVU = 40,075 km ÷ 1670 km/h ÷ 24 h/day = 1 day).

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: At the dawn of the 21st century, numerical modeling of the Earth's magnetic field has not been successfully demonstrated, but appears to be in reach. Initial models are focused on field generation by convection in the planet's fluid outer core. It was possible to show the generation of a strong, Earth-like field when the model assumed a uniform core-surface temperature and exceptionally high viscosities for the core fluid. Computations which incorporated more realistic parameter values yielded magnetic fields that were less Earth-like, but also point the way to model refinements which may ultimately lead to an accurate analytic model.  Slight variations in the core-surface temperature, in the range of a few millikelvins, result in significant increases in convective flow and produce more realistic magnetic fields.

text: Stealing diamonds to power his Planet Splitter, LaBond plans to turn the planet Signus Uno into a second moon to provide more natural resources for Earth. Appears in the Super Friends episode "The Planet Splitter" (1973).

text: Stealing diamonds to power his Planet Splitter, LaBond plans to turn the planet Signus Uno into a second moon to provide more natural resources for Earth. Appears in the

text: Super Friends

text: episode "The Planet Splitter" (1973).

text: The gravitational gradient of the Earth, that is, the change in the gravitational acceleration vector from one point on the Earth’s surface to another, is customarily measured in units of eotvos. The Earth's gravity gradient is dominated by the component due to Earth's near-spherical shape, which results in a vertical tensile gravity gradient of 3,080 E (an elevation increase of 1 m gives a decrease of gravity of about 0.3 mGal), and horizontal compressive gravity gradients of 1/2 that, or 1,540 E. Earth’s rotation perturbs this in a direction-dependent manner by about 5 E. Gravity gradient anomalies in mountainous areas can be as large as several hundred E.

text: The

text: gravitational gradient

text: of the Earth, that is, the change in the gravitational acceleration vector from one point on the Earth’s surface to another, is customarily measured in units of eotvos. The Earth's gravity gradient is dominated by the component due to Earth's near-spherical shape, which results in a vertical tensile gravity gradient of 3,080 E (an elevation increase of 1

text: m

text: gives a decrease of gravity of about 0.3 mGal), and horizontal compressive gravity gradients of 1/2 that, or 1,540 E. Earth’s rotation perturbs this in a direction-dependent manner by about 5 E. Gravity gradient anomalies in mountainous areas can be as large as several hundred E.

text: It appears that Johannes Werner inspired by Amerigo Vespucci's letter written in 1502 where he wrote: "...I maintain that I learned [my longitude] ... by the eclipses and conjunctions of the Moon with the planets; and I have lost many nights of sleep in reconciling my calculations with the precepts of those sages who have devised the manuals and written of the movements, conjunctions, aspects, and eclipses of the two luminaries and of the wandering stars, such as the wise King Don Alfonso in his Tables, Johannes Regiomontanus in his Almanac, and Blanchinus, and the Rabbi Zacuto in his almanac, which is perpetual; and these were composed in different meridians: King Don Alfonso's book in the meridian of Toledo, and Johannes Regiomontanus's in that of Ferrara, and the other two in that of Salamanca."2 The best "clock" to use for reference, is the stars. In the roughly 27.3 solar days of a lunar orbit, the Moon moves a full 360 degrees around the sky, returning to its old position among the stars. This is 13 degrees per day, or just over 0.5 degree per hour. So, while the rotation of the Earth causes the stars and the Moon to appear to move from east to west across the night sky, the Moon, because of its own orbit around the Earth, fights back against this apparent motion, and seems to move eastward (or retrograde) by about 0.5 degree per hour. In other words, the Moon "moves" west only 11.5 degrees per hour."

text: It appears that Johannes Werner inspired by Amerigo Vespucci's letter written in 1502 where he wrote: "...I maintain that I learned [my longitude] ... by the eclipses and conjunctions of the Moon with the planets; and I have lost many nights of sleep in reconciling my calculations with the precepts of those sages who have devised the manuals and written of the movements, conjunctions, aspects, and eclipses of the two luminaries and of the wandering stars, such as the wise King Don Alfonso in his Tables, Johannes Regiomontanus in his Almanac, and Blanchinus, and the

text: Rabbi Zacuto

text: in his almanac, which is perpetual; and these were composed in different meridians: King Don Alfonso's book in the meridian of Toledo, and Johannes Regiomontanus's in that of Ferrara, and the other two in that of Salamanca."2 The best "clock" to use for reference, is the stars. In the roughly 27.3 solar days of a lunar orbit, the Moon moves a full 360 degrees around the sky, returning to its old position among the stars. This is 13 degrees per day, or just over 0.5 degree per hour. So, while the rotation of the Earth causes the stars and the Moon to appear to move from east to west across the night sky, the Moon, because of its own orbit around the Earth, fights back against this apparent motion, and seems to move eastward (or retrograde) by about 0.5 degree per hour. In other words, the Moon "moves" west only 11.5 degrees per hour."

text: It is likely that this magnetic field is generated by a dynamo effect, in a manner similar to the magnetic field of Earth. This dynamo effect would result from the circulation of the planet's iron-rich liquid core. Particularly strong tidal effects caused by the planet's high orbital eccentricity would serve to keep the core in the liquid state necessary for this dynamo effect.

text: It is likely that this magnetic field is generated by a

text: dynamo

text: effect, in a manner similar to the magnetic field of Earth. This dynamo effect would result from the circulation of the planet's iron-rich liquid core. Particularly strong tidal effects caused by the planet's high orbital eccentricity would serve to keep the core in the liquid state necessary for this dynamo effect.

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: K-type main-sequence stars are smaller than the Sun and live longer, remaining on the main sequence 15 to 30 billion years compared to the Sun's estimated 10 billion. Despite these properties, the small M-type and K-type stars can pose a threat to life. Because of their high stellar activity at the beginning of their lives, they emit strong solar winds. The duration of this period is inversely linked to the size of the star. However, because of the uncertainty of the age of Kepler-442, it is likely it may have passed this stage, making Kepler-442b potentially more suitable for habitability. Because it is closer to its star than Earth is to the Sun, the planet will probably rotate much more slowly than Earth; its day could be weeks or months long (see Tidal effects on rotation rate, axial tilt and orbit). This is reflected on its orbital distance just outside of the point where the tidal interactions from its star would be strong enough to tidally locked.

text: K-type main-sequence stars are smaller than the Sun and live longer, remaining on the

text: main sequence

text: 15 to 30 billion years compared to the Sun's estimated 10 billion. Despite these properties, the small M-type and K-type stars can pose a threat to life. Because of their high stellar activity at the beginning of their lives, they emit strong solar winds. The duration of this period is inversely linked to the size of the star. However, because of the uncertainty of the age of Kepler-442, it is likely it may have passed this stage, making Kepler-442b potentially more suitable for habitability. Because it is closer to its star than Earth is to the Sun, the planet will probably rotate much more slowly than Earth; its day could be weeks or months long (see

entity_section: Tidal effects on rotation rate, axial tilt and orbit

text: Tidal effects on rotation rate, axial tilt and orbit

text: ). This is reflected on its orbital distance just outside of the point where the tidal interactions from its star would be strong enough to tidally locked.

text: Perhaps the most commonly encountered rotating reference frame is the Earth. Moving objects on the surface of the Earth experience a Coriolis force, and appear to veer to the right in the northern hemisphere, and to the left in the southern. Movements of air in the atmosphere and water in the ocean are notable examples of this behavior: rather than flowing directly from areas of high pressure to low pressure, as they would on a non-rotating planet, winds and currents tend to flow to the right of this direction north of the equator, and to the left of this direction south of the equator. This effect is responsible for the rotation of large cyclones (see Coriolis effects in meteorology).

text: Perhaps the most commonly encountered rotating reference frame is the

text: Earth

text: . Moving objects on the surface of the Earth experience a Coriolis force, and appear to veer to the right in the

text: northern hemisphere

text: , and to the left in the

text: southern

text: . Movements of air in the atmosphere and water in the ocean are notable examples of this behavior: rather than flowing directly from areas of high pressure to low pressure, as they would on a non-rotating planet, winds and currents tend to flow to the right of this direction north of the

text: equator

text: , and to the left of this direction south of the equator. This effect is responsible for the rotation of large

text: cyclones

text: (see

text: Coriolis effects in meteorology

text: The strength of the gravitational field is numerically equal to the acceleration of objects under its influence.  The rate of acceleration of falling objects near the Earth's surface varies very slightly depending on latitude, surface features such as mountains and ridges, and perhaps unusually high or low sub-surface densities. For purposes of weights and measures, a standard gravity value is defined by the International Bureau of Weights and Measures, under the International System of Units (SI).

text: The strength of the gravitational field is numerically equal to the acceleration of objects under its influence.  The rate of acceleration of falling objects near the Earth's surface varies very slightly depending on latitude, surface features such as mountains and ridges, and perhaps unusually high or low sub-surface densities. For purposes of weights and measures, a

text: standard gravity

text: value is defined by the

entity_name: International Bureau of Weights and Measures

text: International Bureau of Weights and Measures

text: , under the

text: International System of Units

text: (SI).

text: Brain size was previously considered a major indicator of the intelligence of an animal. Since most of the brain is used for maintaining bodily functions, greater ratios of brain to body mass may increase the amount of brain mass available for more complex cognitive tasks. Allometric analysis indicates that mammalian brain size scales at approximately the ⅔ or ¾ exponent of the body mass. Comparison of a particular animal's brain size with the expected brain size based on such allometric analysis provides an encephalisation quotient that can be used as another indication of animal intelligence. Sperm whales have the largest brain mass of any animal on earth, averaging  and  in mature males.

text: Brain size

text: was previously considered a major indicator of the intelligence of an animal. Since most of the brain is used for maintaining bodily functions, greater ratios of

text: brain to body mass

text: may increase the amount of brain mass available for more complex cognitive tasks.

text: Allometric

text: analysis indicates that mammalian brain size scales at approximately the ⅔ or ¾ exponent of the body mass. Comparison of a particular animal's brain size with the expected brain size based on such allometric analysis provides an

text: encephalisation quotient

text: that can be used as another indication of animal intelligence.

text: Sperm whale

text: s have the largest brain mass of any animal on earth, averaging  and  in mature males.

text: The instrument's main scientific goals are the discovery and characterization of terrestrial super-Earths by combining the measurements using transit photometry and doppler spectroscopy which provide both, the size and mass of the exoplanet. Based on the resulting density, rocky (terrestrial) Super-Earths can be distinguished from gaseous exoplanets.

text: The instrument's main scientific goals are the discovery and characterization of terrestrial

text: super-Earth

text: s by combining the measurements using

text: transit photometry

text: and

text: doppler spectroscopy

text: which provide both, the size and mass of the exoplanet. Based on the resulting density, rocky (terrestrial) Super-Earths can be distinguished from gaseous exoplanets.

text: The Coriolis effect causes subtle trajectory variations caused by a rotating reference frame.The coordinate system that is used to specify the location of the point of firing and the location of the target is the system of latitudes and longitudes, which is in fact a rotating coordinate system, since the planet Earth is a rotating sphere. During its flight, the projectile moves in a straight line (not counting gravitation and air resistance for now). Since the target is co-rotating with the Earth, it is in fact a moving target, relative to the projectile, so in order to hit it the gun must be aimed to the point where the projectile and the target will arrive simultaneously.When the straight path of the projectile is plotted in the rotating coordinate system that is used, then this path appears as curvilinear. The fact that the coordinate system is rotating must be taken into account, and this is achieved by adding terms for a "centrifugal force" and a "Coriolis effect" to the equations of motion. When the appropriate Coriolis term is added to the equation of motion the predicted path with respect to the rotating coordinate system is curvilinear, corresponding to the actual straight line motion of the projectile.For an observer with his frame of reference in the northern hemisphere Coriolis makes the projectile appear to curve over to the right. Actually it is not the projectile swinging to the right but the earth (frame of reference) rotating to the left which produces this result. The opposite will seem to happen in the southern hemisphere.

text: The

text: Coriolis effect

text: causes subtle trajectory variations caused by a

text: rotating reference frame

text: .The

text: coordinate system

text: that is used to specify the location of the point of firing and the location of the target is the system of latitudes and longitudes, which is in fact a rotating coordinate system, since the planet Earth is a rotating sphere. During its flight, the projectile moves in a straight line (not counting gravitation and air resistance for now). Since the target is co-rotating with the Earth, it is in fact a

text: moving target

text: , relative to the projectile, so in order to hit it the gun must be aimed to the point where the projectile and the target will arrive simultaneously.When the straight path of the projectile is plotted in the rotating coordinate system that is used, then this path appears as

text: curvilinear

text: . The fact that the coordinate system is rotating must be taken into account, and this is achieved by adding terms for a "centrifugal force" and a "

text: Coriolis effect

text: " to the

text: equations of motion

text: . When the appropriate Coriolis term is added to the equation of motion the predicted path with respect to the rotating coordinate system is curvilinear, corresponding to the actual straight line motion of the projectile.For an observer with his frame of reference in the northern hemisphere Coriolis makes the projectile appear to curve over to the right. Actually it is not the projectile swinging to the right but the earth (frame of reference) rotating to the left which produces this result. The opposite will seem to happen in the southern hemisphere.

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

entity_name: Formation and evolution of the Solar System

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: In the Babylon 5 universe, Minbar is a planet in the system of Chi Draconis — a binary star system just over 26 light years from Earth.  It is the seventh planet in orbit around the local suns and has two moons. Its day is shorter than Earth's, at 20 hours and 47 minutes, and its year is about 1.5 Earth years.  Like Earth, Minbar has an oxygen—nitrogen atmosphere.  The polar caps are larger than those on Earth; the northern cap covers 23% of the planet's surface and, on the whole, Minbar's climate is colder than that of Earth - more like the climate on Earth during the last Ice Age. The planet is noted for vast crystalline structures; many cities are carved directly from crystal. The population of the planet is about 4 billion, and the capital city is located at Yedor.

text: In the Babylon 5 universe, Minbar is a planet in the system of

text: Chi Draconis

text: — a binary

text: star system

text: just over 26 light years from Earth.  It is the seventh planet in orbit around the local suns and has two moons. Its day is shorter than Earth's, at 20 hours and 47 minutes, and its year is about 1.5 Earth years.  Like Earth, Minbar has an oxygen—nitrogen atmosphere.  The polar caps are larger than those on Earth; the northern cap covers 23% of the planet's surface and, on the whole, Minbar's climate is colder than that of Earth - more like the climate on Earth during the last Ice Age. The planet is noted for vast crystalline structures; many cities are carved directly from crystal. The population of the planet is about 4 billion, and the capital city is located at Yedor.

text: The Dutch EP, released in a white sleeve with photos taken from the Rio tour book, featured twelve-inch versions – or "Night Versions" in early Duran Duran parlance – lifted from four of the band's more popular singles – "Hungry Like The Wolf", "Rio", "Planet Earth" and "Girls on Film". A rare misprint of the Dutch sleeve is existing, stating "Hold back the rain" to be included instead of "Planet earth".

text: In Man of Steel, Superman's powers are explained to be the result of Krypton's atmosphere and gravity being much more severe than Earth's, resulting in Kryptonians being naturally much stronger than humans while on a planet like Earth. It is also explained that Kryptonians can absorb the radiation of stars like "our" Sun, but were unable to absorb the radiaton of their planet's star due to it being older and of a different nature. In this version Superman displays enormous strength, durability and speed but his feats are more Herculean in nature and he has to put effort into lifting oil rigs, flying and battling other Kryptonians, similar to the John Byrne reboot. Throughout his life Clark learned to control his super-senses and heat vision, which had caused him trouble in his childhood. As in some comics, he is depicted as being more powerful than Zod and other Kryptonians due to his lifetime of exposure to Earth's yellow sun, which allowed him to absorb and metabolize its radiation in greater amounts and with more efficiency. This gave him an advantage and victory over them despite their superior fighting skills and quickly adapting to their newfound abilities. Superman was also able to utilize microscopic vision when he used said vision to lock on to the Kryptonian warship hovering over Earth while in Smallville. The only powers not featured in the film are freeze breath and super-breath.

text: In

text: Man of Steel

text: , Superman's powers are explained to be the result of Krypton's atmosphere and gravity being much more severe than Earth's, resulting in Kryptonians being naturally much stronger than humans while on a planet like Earth. It is also explained that Kryptonians can absorb the radiation of stars like "our" Sun, but were unable to absorb the radiaton of their planet's star due to it being older and of a different nature. In this version Superman displays enormous strength, durability and speed but his feats are more Herculean in nature and he has to put effort into lifting oil rigs, flying and battling other Kryptonians, similar to the John Byrne reboot. Throughout his life Clark learned to control his super-senses and heat vision, which had caused him trouble in his childhood. As in some comics, he is depicted as being more powerful than Zod and other Kryptonians due to his lifetime of exposure to Earth's yellow sun, which allowed him to absorb and metabolize its radiation in greater amounts and with more efficiency. This gave him an advantage and victory over them despite their superior fighting skills and quickly adapting to their newfound abilities. Superman was also able to utilize microscopic vision when he used said vision to lock on to the Kryptonian warship hovering over Earth while in Smallville. The only powers not featured in the film are freeze breath and super-breath.

text: Gethen appears to have a surface gravity more or less similar to Earth and a human-compatible atmosphere (the Earth envoy sent there shows no sign of discomfort). Because of its cold climate, the planet is sometimes called "Winter".

text: Gethen appears to have a surface

text: gravity

text: more or less similar to

text: Earth

text: and a human-compatible

text: atmosphere

text: (the Earth envoy sent there shows no sign of discomfort). Because of its cold climate, the planet is sometimes called "Winter".

text: A reference ellipsoid, customarily chosen to be the same size (volume) as the geoid, is described by its semi-major axis (equatorialradius) a and flattening f. The quantity f = , where b is the semi-minor axis (polar radius), is a purely geometrical one. The mechanical ellipticity of the Earth (dynamical flattening, symbol J) can be determined to high precision by observation of satellite orbit perturbations. Its relationship with the geometrical flattening is indirect. The relationship depends on the internal density distribution, or, in simplest terms, the degree of central concentration of mass.

text: A

text: reference ellipsoid

text: , customarily chosen to be the same size (volume) as the geoid, is described by its semi-major axis (equatorialradius) a and flattening f. The quantity f = , where b is the semi-minor axis (polar radius), is a purely geometrical one. The mechanical ellipticity of the Earth (dynamical flattening, symbol J) can be determined to high precision by observation of satellite orbit perturbations. Its relationship with the geometrical flattening is indirect. The relationship depends on the internal density distribution, or, in simplest terms, the degree of central concentration of mass.

text: On December 20, 2011, the Kepler Space Telescope team reported the discovery of a five planet system containing three small gas giants and the first two Earth-sized extrasolar planets, Kepler-20e (the first known extrasolar planet smaller than Earth orbiting a main-sequence star) and Kepler-20f, orbiting a Sun-like star. Although the planets are Earth-sized, they are not Earth-like in the respect that they are much closer to their star than Earth, and are hence not near the habitable zone, with expected surface temperatures of  and  , respectively. The three other Neptune-sized planets in the system, Kepler-20b, Kepler-20c, and Kepler-20d, all orbit similarly close to the star. Kepler-20g is an non-transiting exoplanet orbiting Kepler-20.

text: On December 20, 2011, the

text: Kepler Space Telescope

text: team reported the discovery of a five planet system containing three small gas giants and the first two

text: Earth-sized

text: extrasolar planet

text: s,

text: (the first known extrasolar planet smaller than

text: Earth

text: orbiting a main-sequence star) and

text: , orbiting a

text: Sun-like star

text: . Although the planets are

text: Earth-sized

text: , they are not

text: Earth-like

text: in the respect that they are much closer to their star than Earth, and are hence not near the habitable zone, with expected surface temperatures of  and  , respectively. The three other

text: Neptune-sized

text: planets in the system,

text: , and

text: , all orbit similarly close to the star.

text: is an non-transiting

text: exoplanet

text: orbiting Kepler-20.

text: The sixth season was originally announced to be the final season, but in June 2014, MTV announced that Fantasy Factory would return for a seventh season. The seventh season premiered on January 1, 2015 and ended March 5, 2015.

text: Emperor Tod Spengo (Jon Lovitz), with General Afir (Thalmus Rasulala) at his side, takes over a small planet at the edge of the galaxy populated entirely by idiots, and renames it after himself. He orders that all the resources of the planet should be engaged to create his "Super Death Ray Laser"; the laser's purpose is to destroy Earth, thus making Spengo the greatest planet in the Universe. When Spengo looks at exactly where his laser would strike, he sees Marge Nelson (Teri Garr) exercising — and falls in love.  Using his Magnobeam (a giant magnet), he kidnaps Marge and her husband, Dick (Jeffrey Jones), as they are on their way to a 20th-anniversary weekend, hoping to make Marge his wife before he blows up the Earth. Dick and Marge get separated on Spengo: Marge is sent to the lap of luxury, waited on by small people with fish or dog heads, while Dick is thrown into a dungeon. In the dungeon, however, Dick meets the rightful king of Spengo, Raff (Eric Idle), who has plans hidden in his pants for his son, called the White Bird, out in the desert.

text: Emperor Tod Spengo (

text: Jon Lovitz

text: ), with General Afir (

text: Thalmus Rasulala

text: ) at his side, takes over a small planet at the edge of the galaxy populated entirely by idiots, and renames it after himself. He orders that all the resources of the planet should be engaged to create his "Super Death Ray Laser"; the laser's purpose is to destroy Earth, thus making Spengo the greatest planet in the Universe. When Spengo looks at exactly where his laser would strike, he sees Marge Nelson (

text: Teri Garr

text: ) exercising — and falls in love.  Using his Magnobeam (a giant magnet), he kidnaps Marge and her husband, Dick (

text: Jeffrey Jones

text: ), as they are on their way to a 20th-anniversary weekend, hoping to make Marge his wife before he blows up the Earth. Dick and Marge get separated on Spengo: Marge is sent to the lap of luxury, waited on by small people with fish or dog heads, while Dick is thrown into a dungeon. In the dungeon, however, Dick meets the rightful king of Spengo, Raff (

text: Eric Idle

text: ), who has plans hidden in his pants for his son, called the White Bird, out in the desert.

text: Over four times as massive as the Earth, it circles the primary at a distance of 0.36 AU with an orbital period of approximately 66 days. Because it and PSR B1257+12 C have very similar masses and orbit close to each other, they were expected to cause measurable perturbations in each other's orbits. Detecting such perturbations confirmed that the planets were real. Accurate masses of the two planets, as well as their inclinations, were calculated from how much the planets perturb each other.

text: Over four times as massive as the Earth, it circles the primary at a distance of 0.36 AU with an orbital period of approximately 66

text: day

text: s. Because it and

text: PSR B1257+12 C

text: have very similar masses and orbit close to each other, they were expected to cause measurable

text: perturbations

text: in each other's orbits. Detecting such perturbations confirmed that the planets were real. Accurate masses of the two planets, as well as their

text: inclination

text: s, were calculated from how much the planets perturb each other.

text: The Earth's magnetic field protects the Earth from the deadly solar wind and has long been used for navigation. It originates in the fluid motions of the Earth's outer core (see geodynamo). The magnetic field in the upper atmosphere gives rise to the auroras.

text: The

text: Earth's magnetic field

text: protects the Earth from the deadly

text: solar wind

text: and has long been used for navigation. It originates in the fluid motions of the

text: Earth's outer core

text: (see

text: geodynamo

text: ). The magnetic field in the upper atmosphere gives rise to the

text: auroras

text: A group of alien invaders, the Mykonians, view humans as being unworthy of such a resource-rich planet, and implant their Parasite Machine into the crust of the planet to draw energy directly from the Earth's core. The Parasite Machine is causing the Earth's core to cool, weakening its magnetic field. This will eventually cause solar radiation levels to rise and obliterate all of the planet's biomass, making it suitable for Mykonian colonization. In the campaign, Mykonian forces are usually present in northern Europe, where the cool temperatures allow for more efficient data transfer.

text: A group of alien invaders, the Mykonians, view humans as being unworthy of such a resource-rich planet, and implant their Parasite Machine into the

text: crust

text: of the planet to draw energy directly from the Earth's

text: core

text: . The Parasite Machine is causing the Earth's core to cool, weakening its

text: magnetic field

text: . This will eventually cause

text: solar radiation

text: levels to rise and obliterate all of the planet's

text: biomass

text: , making it suitable for Mykonian colonization. In the campaign, Mykonian forces are usually present in

text: northern Europe

text: , where the cool temperatures allow for more efficient data transfer.

text: Many red dwarfs are orbited by exoplanets, but large Jupiter-sized planets are comparatively rare. Doppler surveys of a wide variety of stars indicate about 1 in 6 stars with twice the mass of the Sun are orbited by one or more Jupiter-sized planets, vs. 1 in 16 for Sun-like stars and only 1 in 50 for red dwarfs. On the other hand, microlensing surveys indicate that long-orbital-period Neptune-mass planets are found around one in three red dwarfs.Observations with HARPS further indicate 40% of red dwarfs have a "super-Earth" class planet orbiting in the habitable zone where liquid water can exist on the surface. Computer simulations of the formation of planets around low mass stars predict that Earth-sized planets are most abundant, but more than 90% of the simulated planets are at least 10% water by mass, suggesting that many Earth-sized planets orbiting red dwarf stars are covered in deep oceans.

text: Many red dwarfs are orbited by

text: exoplanet

text: s, but large

text: Jupiter

text: -sized planets are comparatively rare. Doppler surveys of a wide variety of stars indicate about 1 in 6 stars with twice the mass of the Sun are orbited by one or more Jupiter-sized planets, vs. 1 in 16 for Sun-like stars and only 1 in 50 for red dwarfs. On the other hand,

text: microlensing

text: surveys indicate that long-orbital-period

text: Neptune

text: -mass planets are found around one in three red dwarfs.Observations with

text: HARPS

text: further indicate 40% of red dwarfs have a "

text: super-Earth

text: " class planet orbiting in the habitable zone where liquid water can exist on the surface. Computer simulations of the formation of planets around low mass stars predict that Earth-sized planets are most abundant, but more than 90% of the simulated planets are at least 10% water by mass, suggesting that many Earth-sized planets orbiting red dwarf stars are covered in deep oceans.

text: Being tidally locked to a giant planet or sub-brown dwarf would allow for more moderate climates on a moon than there would be if the moon were a similar-sized planet orbiting in locked rotation in the habitable zone of the star.  This is especially true of red dwarf systems, where comparatively high gravitational forces and low luminosities leave the habitable zone in an area where tidal locking would occur. If tidally locked, one rotation about the axis may take a long time relative to a planet (for example, ignoring the slight axial tilt of Earth's moon and topographical shadowing, any given point on it has two weeks – in Earth time – of sunshine and two weeks of night in its lunar day) but these long periods of light and darkness are not as challenging for habitability as the eternal days and eternal nights on a planet tidally locked to its star.

text: Being tidally locked to a giant planet or

text: sub-brown dwarf

text: would allow for more moderate climates on a moon than there would be if the moon were a similar-sized planet orbiting in locked rotation in the habitable zone of the star.  This is especially true of

text: red dwarf

text: systems, where comparatively high gravitational forces and low luminosities leave the habitable zone in an area where tidal locking would occur. If tidally locked, one rotation about the axis may take a long time relative to a planet (for example, ignoring the slight axial tilt of Earth's moon and topographical shadowing, any given point on it has two weeks – in Earth time – of sunshine and two weeks of night in its lunar day) but these long periods of light and darkness are not as challenging for habitability as the eternal days and eternal nights on a planet tidally locked to its star.

text: Venus orbits the Sun in 225 days, spending about 18.75 days in each sign of the zodiac. Venus is the second-brightest object in the night sky, the Moon being the brightest. It is usually beheld as a twin planet to Earth.

text: If a planet is radically tilted,  seasons will be extreme and make it more difficult for a biosphere to achieve homeostasis. The axial tilt of the Earth is higher now (in the Quaternary) than it has been in the past, coinciding with reduced polar ice, warmer temperatures and less seasonal variation.  Scientists do not know whether this trend will continue indefinitely with further increases in axial tilt (see Snowball Earth).

text: If a planet is radically tilted,  seasons will be extreme and make it more difficult for a

text: biosphere

text: to achieve

text: homeostasis

text: . The axial tilt of the Earth is higher now (in the

text: Quaternary

text: ) than it has been in the past, coinciding with reduced polar

text: ice

text: , warmer temperatures and less seasonal variation.  Scientists do not know whether this trend will continue indefinitely with further increases in axial tilt (see

text: Snowball Earth

text: A star with a planet will move in its own small orbit in response to the planet's gravity. This leads to variations in the speed with which the star moves toward or away from Earth, i.e. the variations are in the radial velocity of the star with respect to Earth. The radial velocity can be deduced from the displacement in the parent star's spectral lines due to the Doppler effect. The radial-velocity method measures these variations in order to confirm the presence of the planet using the binary mass function.

text: A star with a planet will move in its own small orbit in response to the planet's gravity. This leads to variations in the speed with which the star moves toward or away from Earth, i.e. the variations are in the

text: radial velocity

text: of the star with respect to Earth. The radial velocity can be deduced from the displacement in the parent star's

text: spectral line

text: s due to the

text: Doppler effect

text: . The radial-velocity method measures these variations in order to confirm the presence of the planet using the

text: binary mass function

text: The atmosphere of Earth is the layer of gases, commonly known as air, that surrounds the planet Earth and is retained by Earth's gravity. The atmosphere of Earth protects life on Earth by absorbing ultraviolet solar radiation, warming the surface through heat retention (greenhouse effect), and reducing temperature extremes between day and night (the diurnal temperature variation).

text: The atmosphere of Earth is the layer of

text: gas

text: es, commonly known as air, that surrounds the planet

text: Earth

text: and is retained by

text: Earth's gravity

text: . The atmosphere of Earth protects

text: life on Earth

text: by absorbing

text: ultraviolet

text: solar radiation

text: , warming the surface through heat retention (

text: greenhouse effect

text: ), and reducing

text: temperature

text: extremes between

text: day

text: and

text: night

text: (the

text: diurnal temperature variation

text: Seeing no other solution, the time traveler Waverider (a pre-Flashpoint future version of Booster Gold) summons Brainiac back. Brainiac reveals he was the pre-Flashpoint Brainiac who, surviving that event, sought to explore the history of the Multiverse, but became mutated by the effects of the previous crises. He realizes what a monster he has become and wishes to put things right. He prepares to send everyone back where they came from, but is prevented by the damaging effects of the original crisis in Crisis on Infinite Earths. The heroes resolve to change the outcome of that Crisis. As Brainiac sends the pre-Crisis Supergirl and Barry Allen back to meet their fates in the original Crisis story, pre-Flashpoint Superman and Zero Hour Parallax (seeking redemption) volunteer to go with them, changing the outcome of the crisis. Brainiac explains that this has brought changes to the Multiverse, causing everything to "return to what it was before I [Brainiac] brought you here." The old worlds of the classic Multiverse live on in both their original versions and the modernized forms depicted in The Multiversity. All worlds and timelines now exist. The Earth 2 team are left behind on the planet, but Telos transports the planet into Earth 2's universe. He appears in the sky to tell the Wonders that he has remembered his real name and where his family is and that the planet will be their New Earth 2. Once again able to channel the power of the Green, Alan terraforms the planet and makes contact with the space fleet carrying the displaced Earth 2 refugees leading them to their new home.

text: Seeing no other solution, the time traveler

text: Waverider

text: (a pre-Flashpoint future version of

text: Booster Gold

text: ) summons Brainiac back. Brainiac reveals he was the pre-Flashpoint Brainiac who, surviving that event, sought to explore the history of the Multiverse, but became mutated by the effects of the previous crises. He realizes what a monster he has become and wishes to put things right. He prepares to send everyone back where they came from, but is prevented by the damaging effects of the original crisis in

text: Crisis on Infinite Earths

text: . The heroes resolve to change the outcome of that Crisis. As Brainiac sends the pre-Crisis Supergirl and Barry Allen back to meet their fates in the original Crisis story, pre-Flashpoint Superman and Zero Hour Parallax (seeking redemption) volunteer to go with them, changing the outcome of the crisis. Brainiac explains that this has brought changes to the Multiverse, causing everything to "return to what it was before I [Brainiac] brought you here." The old worlds of the classic Multiverse live on in both their original versions and the modernized forms depicted in

text: The Multiversity

text: . All worlds and timelines now exist. The Earth 2 team are left behind on the planet, but Telos transports the planet into Earth 2's universe. He appears in the sky to tell the Wonders that he has remembered his real name and where his family is and that the planet will be their New Earth 2. Once again able to channel the power of the Green, Alan terraforms the planet and makes contact with the space fleet carrying the displaced Earth 2 refugees leading them to their new home.

text: The player moves around in a board game-type environment trying to prevent space aliens (of increasing strength and potency) from destroying human civilization (as they build their temple on Earth). Accomplishing a complete revolution around the board (going from the start line back to the start line) ends each chapter. When a chapter begins, all four vehicles are on the start line and the player who wins the previous chapter usually starts first. There are questions that must be answered with a "yes" or a "no." Failure to succeed in this quest will result in the extraterrestrials taking over planet Earth. Up to four players can compete.

text: The player moves around in a

text: board game

text: -type environment trying to prevent

text: space aliens

text: (of increasing strength and potency) from destroying human civilization (as they build their temple on Earth). Accomplishing a complete revolution around the board (going from the start line back to the start line) ends each chapter. When a chapter begins, all four vehicles are on the start line and the player who wins the previous chapter usually starts first. There are questions that must be answered with a "yes" or a "no." Failure to succeed in this quest will result in the extraterrestrials taking over planet Earth. Up to four players can compete.

text: The Hunters series (Season 1 episode 13 final) features an alien species living on Earth and intending to use the Project Orion technology on a ship in order to come back to their planet

text: The Hunters series

text: (Season 1 episode 13 final) features an alien species living on Earth and intending to use the Project Orion technology on a ship in order to come back to their planet

text: In season one, Ted King was cast as the inspector Andy Trudeau, Dorian Gregory was cast as his inspector partner Darryl Morris, and Brian Krause was cast as the Halliwell sisters' whitelighter Leo Wyatt. King departed Charmed at the end of the first season, while Gregory remained on the show until the seventh season. In season two, Greg Vaughan joined the series as the Halliwell sisters' new next-door neighbor Dan Gordon, while Karis Paige Bryant was cast as his niece Jenny Gordon. Bryant left her role midway through the second season, while Vaughan left at the end of the season. Australian actor Julian McMahon joined the cast of Charmed in season three as the half-demon Cole Turner. He departed the show midway through season five. Drew Fuller joined Charmed at the end of the fifth season as Piper and Leo's second son from the future, Chris Halliwell. Fuller left his role at the end of season six. In the eighth and final season, Kaley Cuoco joined the show as the young witch Billie Jenkins.

text: In season one,

text: Ted King

text: was cast as the inspector

text: Andy Trudeau

text: Dorian Gregory

text: was cast as his inspector partner

text: Darryl Morris

text: , and

text: Brian Krause

text: was cast as the Halliwell sisters'

text: whitelighter

text: Leo Wyatt

text: . King departed Charmed at the end of the first season, while Gregory remained on the show until the seventh season. In season two,

text: Greg Vaughan

text: joined the series as the Halliwell sisters' new next-door neighbor

text: Dan Gordon

text: , while Karis Paige Bryant was cast as his niece

text: Jenny Gordon

text: . Bryant left her role midway through the second season, while Vaughan left at the end of the season. Australian actor

text: Julian McMahon

text: joined the cast of Charmed in season three as the half-demon

text: Cole Turner

text: . He departed the show midway through season five.

text: Drew Fuller

text: joined Charmed at the end of the fifth season as Piper and Leo's second son from the future,

text: Chris Halliwell

text: . Fuller left his role at the end of

text: season six

text: . In the

text: eighth and final season

text: Kaley Cuoco

text: joined the show as the young witch

text: Billie Jenkins

text: Kepler-11d is an exoplanet discovered in the orbit of the sun-like star Kepler-11. It is named for the telescope that discovered it, a NASA spacecraft named Kepler that is designed to detect Earth-like planets by measuring small dips in the brightness of their host stars as the planets cross in front. This process, known as the transit method, was used to note the presence of six planets in orbit around Kepler-11, of which Kepler-11d is the third from its star. Kepler-11d orbits Kepler-11 well within the orbit of Mercury approximately every 23 days. The planet is approximately six times more massive than the Earth, and has a radius that is three and a half times larger than that of Earth's. It is, however, far hotter than Earth is. Its low density, comparable to that of Saturn, suggests that Kepler-11d has a large hydrogen–helium atmosphere. Kepler-11d was announced with its five sister planets on February 2, 2011 after extensive follow-up studies.

text: Kepler-11d is an

text: exoplanet

text: discovered in the orbit of the sun-like star

text: . It is named for the telescope that discovered it, a

text: NASA

text: spacecraft named

text: Kepler

text: that is designed to detect

text: Earth-like planets

text: by measuring small dips in the brightness of their host stars as the planets cross in front. This process, known as the

text: transit method

text: , was used to note the presence of six planets in orbit around Kepler-11, of which Kepler-11d is the third from its star. Kepler-11d orbits Kepler-11 well within the orbit of

text: Mercury

text: approximately every 23 days. The planet is approximately six times more massive than the Earth, and has a radius that is three and a half times larger than that of Earth's. It is, however, far hotter than Earth is. Its low density, comparable to that of

text: Saturn

text: , suggests that Kepler-11d has a large hydrogen–helium atmosphere. Kepler-11d was announced with its five sister planets on February 2, 2011 after extensive follow-up studies.

text: Geophysics  is a subject of natural science concerned with the physical processes and physical properties of the Earth and its surrounding space environment, and the use of quantitative methods for their analysis. The term geophysics sometimes refers only to the geological applications: Earth's shape; its gravitational and magnetic fields; its internal structure and composition; its dynamics and their surface expression in plate tectonics, the generation of magmas, volcanism and rock formation. However, modern geophysics organizations use a broader definition that includes the water cycle including snow and ice; fluid dynamics of the oceans and the atmosphere; electricity and magnetism in the ionosphere and magnetosphere and solar-terrestrial relations; and analogous problems associated with the Moon and other planets.

text: Geophysics  is a subject of

text: natural science

text: concerned with the physical processes and physical properties of the

text: Earth

text: and its surrounding space environment, and the use of quantitative methods for their analysis. The term geophysics sometimes refers only to the geological applications: Earth's

text: shape

text: ; its

text: gravitational

text: and

text: magnetic fields

text: ; its

text: internal structure

text: and

text: composition

text: ; its

text: dynamics

text: and their surface expression in

text: plate tectonics

text: , the generation of

text: magma

text: s,

text: volcanism

text: and rock formation. However, modern geophysics organizations use a broader definition that includes the

text: water cycle

text: including snow and ice;

text: fluid dynamics

text: of the oceans and the

text: atmosphere

text: electricity

text: and

text: magnetism

text: in the

text: ionosphere

text: and

text: magnetosphere

text: and solar-terrestrial relations; and analogous problems associated with the

text: Moon

text: and other planets.

text: Day for night is a set of cinematic techniques used to simulate a night scene while filming in daylight. It is often employed when it is too difficult or expensive to actually shoot during nighttime. Because both film stocks and digital image sensors lack the sensitivity of the human eye in low light conditions, night scenes recorded in natural light, with or without moonlight, may be underexposed to the point where little or nothing is visible. This problem can be avoided by using daylight to substitute for darkness. When shooting day for night, the scene is typically underexposed in-camera or darkened during post-production, with a blue tint added. Additional effects are often used to heighten the impression of night.

text: Day for night is a set of

text: cinematic

text: techniques used to simulate a night scene while filming in daylight. It is often employed when it is too difficult or expensive to actually shoot during nighttime. Because both

text: film stock

text: s and digital

text: image sensors

text: lack the sensitivity of the

text: human eye

text: in low light conditions, night scenes recorded in natural light, with or without moonlight, may be

text: underexposed

text: to the point where little or nothing is visible. This problem can be avoided by using daylight to substitute for darkness. When shooting day for night, the scene is typically underexposed in-camera or darkened during

text: post-production

text: , with a blue tint added. Additional effects are often used to heighten the impression of night.

text: Theoretical models show that Hot Jupiters and Hot Neptunes can evolve by hydrodynamic loss of their atmospheres to Mini-Neptunes (as it could be the Super-Earth GJ 1214 b), or even to rocky planets known as chthonian planets (after migrating towards the proximity of their parent star). The amount of the outermost layers that is lost depends on the size and the material of the planet and the distance from the star. In a typical system a gas giant orbiting 0.02 AU around its parent star loses 5–7% of its mass during its lifetime, but orbiting closer than 0.015 AU can mean evaporation of the whole planet except for its core.

text: Theoretical models show that Hot Jupiters and Hot Neptunes can evolve by hydrodynamic loss of their atmospheres to Mini-Neptunes (as it could be the Super-Earth

text: GJ 1214 b

text: ), or even to rocky planets known as

text: chthonian planet

text: s (after migrating towards the proximity of their parent star). The amount of the outermost layers that is lost depends on the size and the material of the planet and the distance from the star. In a typical system a gas giant orbiting 0.02 AU around its parent star loses 5–7% of its mass during its lifetime, but orbiting closer than 0.015 AU can mean evaporation of the whole planet except for its core.

text: Apart from the Earth's magnetic field, some other bodies such as Jupiter and Saturn, and the Sun have significant magnetic fields whose major component is a dipole, an axisymmetric magnetic field. These magnetic fields are self-sustained through fluid motion in the Sun or planets, with the necessary non symmetry for the planets deriving from the Coriolis force caused by their rapid rotation, and one cause of non-symmetry for the Sun being its differential rotation. The magnetic fields of planets with slow rotation periods and/or solid cores, such as Mercury, Venus and Mars, have dissipated to almost nothing by comparison.

text: Apart from the

text: Earth's magnetic field

text: , some other bodies such as

text: Jupiter

text: and

text: Saturn

text: , and the

text: Sun

text: have significant magnetic fields whose major component is a

text: dipole

text: , an axisymmetric magnetic field. These magnetic fields are self-sustained through fluid motion in the Sun or planets, with the necessary non symmetry for the planets deriving from the

text: Coriolis force

text: caused by their rapid rotation, and one cause of non-symmetry for the Sun being its

text: differential rotation

text: . The magnetic fields of planets with slow rotation periods and/or solid cores, such as

text: Mercury

text: Venus

text: and

text: Mars

text: , have dissipated to almost nothing by comparison.

text: An atmosphere that is dense will circulate heat, potentially allowing a wide area on the surface to be habitable. For example, Venus has a solar rotation rate approximately 117 times slower than Earth's, producing prolonged days and nights. Despite the uneven distribution of sunlight over time intervals shorter than several months, unilluminated areas of Venus are kept almost as hot as the day side by globally circulating winds. Simulations have shown that an atmosphere containing appropriate levels of CO and HO need only be a tenth the pressure of Earth's atmosphere (100 mbar) to effectively distribute heat to the night side. Current technology cannot determine the atmospheric or surface composition of the planet due to the overpowering light of its parent star.

text: An atmosphere that is dense will circulate heat, potentially allowing a wide area on the surface to be habitable. For example,

text: Venus

text: has a

text: solar

text: rotation rate approximately 117 times slower than Earth's, producing prolonged days and nights. Despite the uneven distribution of sunlight over time intervals shorter than several months, unilluminated areas of Venus are kept almost as hot as the day side by globally circulating winds. Simulations have shown that an atmosphere containing appropriate levels of CO and HO need only be a tenth the pressure of Earth's atmosphere (100

text: mbar

text: ) to effectively distribute heat to the night side. Current technology cannot determine the atmospheric or surface composition of the planet due to the overpowering light of its parent star.

text: While life on Earth is regarded to have spawned relatively early in the planet's history, the evolution from multicellular to intelligent organisms took around 800 million years. Civilizations on Earth have existed for about 10,000 years and radio communication with space is not older than 80 years. Relative to the age of the Solar System (~4.57 Ga) this is a tiny age span, an age span in which extreme climatic variations, super volcanoes or large meteorite impacts were absent. These events would severely harm intelligent life, as well as life in general.  For example, the Permian-Triassic mass extinction, caused by widespread and continuous volcanic eruptions in an area the size of Western Europe, led to the extinction of 95% of known species around 251.2 Ma ago.  About 65 million years ago, the Chicxulub impact at the Cretaceous–Paleogene boundary (~65.5 Ma) on the Yucatán peninsula in Mexico led to a mass extinction of the most advanced species at that time.

text: While life on Earth is regarded to have spawned relatively early in the planet's history, the evolution from multicellular to intelligent organisms took around 800 million years. Civilizations on Earth have existed for about 10,000 years and radio communication with space is not older than 80 years. Relative to the age of the Solar System (~4.57 Ga) this is a tiny age span, an age span in which extreme climatic variations, super volcanoes or large meteorite impacts were absent. These events would severely harm intelligent life, as well as life in general.  For example, the

text: Permian-Triassic mass extinction

text: , caused by widespread and continuous volcanic eruptions in an area the size of Western Europe, led to the extinction of 95% of known species around 251.2

text: Ma

text: ago.  About 65 million years ago, the

text: Chicxulub

text: impact at the

text: Cretaceous–Paleogene boundary

text: (~65.5 Ma) on the

text: Yucatán peninsula

text: in

text: Mexico

text: led to a mass extinction of the most advanced species at that time.

text: Aside from searching for Earth-sized planets SIM Lite was scheduled to perform what has been dubbed the "Broad Survey". The Broad Survey would have looked at approximately 1,500 stars to help determine the abundance of Neptune-mass and larger planets around all star-types in Earth's sector of the Milky Way.

text: Aside from searching for Earth-sized planets SIM Lite was scheduled to perform what has been dubbed the "Broad Survey". The Broad Survey would have looked at approximately 1,500 stars to help determine the abundance of

text: Neptune

text: -mass and larger planets around all star-types in Earth's sector of the

text: Milky Way

text: This list contains the fastest-rotating minor planets with a period of less than 100 seconds, or 0.027 hours. Bodies with a highly uncertain period, having a quality of less than 2, are highlighted in dark-grey. The fastest rotating bodies are all unnumbered near-Earth objects (NEOs) with a diameter of less than 100 meters (see table).

text: This list contains the

text: fastest-rotating

text: minor planets with a period of less than 100 seconds, or 0.027 hours. Bodies with a highly uncertain period, having a

text: quality

text: of less than 2, are highlighted in dark-grey. The fastest rotating bodies are all unnumbered

text: near-Earth object

text: s (NEOs) with a diameter of less than 100 meters (see table).

text: Watkins served as project scientist for the  GRACE,  GRAIL and GRACE Follow-On missions. He was an originator of the concept for the GRACE mission, which uses a pair of Earth-orbiting satellites to make detailed measurements of Earth's gravity field anomalies. In addition, he has been a pioneer in the development and use of gravity data for new science applications to better understand Earth’s climate and its evolution. Other research interests include mission design, instrument design and science analysis for acquisition and use of remote sensing data for Earth and other planets.

text: Watkins served as project scientist for the

text: GRACE

text: GRAIL

text: and GRACE Follow-On missions. He was an originator of the concept for the GRACE mission, which uses a pair of Earth-orbiting satellites to make detailed measurements of Earth's gravity field anomalies. In addition, he has been a pioneer in the development and use of gravity data for new science applications to better understand Earth’s climate and its evolution. Other research interests include mission design, instrument design and science analysis for acquisition and use of remote sensing data for Earth and other planets.

text: The Phases of Venus result from the planet's orbit around the Sun inside the Earth's orbit giving the telescopic observer a sequence of progressive lighting similar in appearance to the moon's phases. It presents a full image when it is on the opposite side of the Sun. It shows a quarter phase when it is at its maximum elongation from the Sun. Venus presents a thin crescent in telescopic views as it comes around to the near side between the Earth and the Sun and presents its new phase when it is between the Earth and the Sun. Since the planet has an atmosphere it can be seen at new in a telescope by the halo of light refracted around the planet. The full cycle from new to full to new again takes 584 days (the time it takes Venus to overtake the Earth in its orbit). The planet also changes in apparent size from 9.9 arc seconds at full (superior conjunction) up to a maximum of 68 arc seconds at new (inferior conjunction). Venus reaches its greatest magnitude of −4.5 when it is an intermediate crescent shape at the point in its orbit, when it is 68 million km away from the Earth (a combination of its closeness and the fact that it is 28% illuminated).

text: The Phases of Venus result from the planet's

text: orbit

text: around the

text: Sun

text: inside the

text: Earth

text: 's orbit giving the

text: telescopic

text: observer a sequence of progressive lighting similar in appearance to the

text: moon's phases

text: . It presents a

text: full

text: image when it is on the opposite side of the Sun. It shows a

text: quarter phase

text: when it is at its maximum

text: elongation

text: from the Sun. Venus presents a thin crescent in telescopic views as it comes around to the near side between the Earth and the Sun and presents its

text: new phase

text: when it is between the Earth and the Sun. Since the planet has an atmosphere it can be seen at new in a telescope by the halo of light refracted around the planet. The full cycle from new to full to new again takes 584 days (the time it takes Venus to overtake the Earth in its orbit). The planet also changes in apparent size from 9.9

text: arc seconds

text: at full (

text: superior conjunction

text: ) up to a maximum of 68 arc seconds at new (

text: inferior conjunction

text: ). Venus reaches its greatest

text: magnitude

text: of −4.5 when it is an intermediate crescent shape at the point in its orbit, when it is 68 million km away from the Earth (a combination of its closeness and the fact that it is 28% illuminated).

text: The precise strength of Earth's gravity varies depending on location. The nominal "average" value at the Earth's surface, known as  is, by definition, 9.80665 m/s (about 32.1740 ft/s). This quantity is denoted variously as ,  (though this sometimes means the normal equatorial value on Earth, 9.78033 m/s), , gee, or simply  (which is also used for the variable local value).

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 Moon-to-Earth mass ratio of 0.01230 (≈ ) is also notably close to 1 when compared to all other satellite-to-planet ratios. Consequently, some scientists view the Earth-Moon system as a double planet as well, though this is a minority view. Eris's lone satellite, Dysnomia, has a radius somewhere around 1/4 that of Eris; assuming similar densities (Dysnomia's compositional make-up may or may not differ substantially from Eris's), the mass ratio would be near , a value intermediate to the Moon/Earth and Charon/Pluto ratios.

text: The Moon-to-Earth mass ratio of 0.01230 (≈ ) is also notably close to 1 when compared to all other satellite-to-planet ratios. Consequently, some scientists view the Earth-Moon system as a double planet as well, though this is a minority view.

text: Eris

text: 's lone satellite,

text: Dysnomia

text: , has a radius somewhere around 1/4 that of

text: Eris

text: ; assuming similar densities (Dysnomia's compositional make-up may or may not differ substantially from Eris's), the mass ratio would be near , a value intermediate to the Moon/Earth and Charon/Pluto ratios.

text: Luckily, the inventor George Stephenson saves the Doctor just in time. Later, the Doctor and Peri visit Stephenson in his cottage. Stephenson has planned a meeting of scientific and engineering geniuses in the village. The Doctor is worried about the wisdom of such a meeting in the current circumstances, but elsewhere the Master is so desperate to see the event take place he uses mind-control over Stephenson's young aide, Luke Ward, telling him to kill anyone who tries to prevent it. The Master wants to use the finest brains of the Industrial Revolution to help speed up Earth's development and then use the planet as a powerbase. He strikes a deal with the Rani that she may return to Earth at any time to harvest more brain fluid if she helps him achieve this.

text: Luckily, the inventor

text: George Stephenson

text: saves the Doctor just in time. Later, the Doctor and Peri visit Stephenson in his cottage. Stephenson has planned a meeting of scientific and engineering geniuses in the village. The Doctor is worried about the wisdom of such a meeting in the current circumstances, but elsewhere the Master is so desperate to see the event take place he uses mind-control over Stephenson's young aide, Luke Ward, telling him to kill anyone who tries to prevent it. The Master wants to use the finest brains of the

text: Industrial Revolution

text: to help speed up Earth's development and then use the planet as a powerbase. He strikes a deal with the Rani that she may return to Earth at any time to harvest more brain fluid if she helps him achieve this.

text: Kepler-452b has a probable mass five times that of Earth, and its surface gravity is twice Earth's, though calculations of mass for exoplanets are only rough estimates. If it is a terrestrial planet, it is most likely a super-Earth with many active volcanoes due to its higher mass and density. The clouds on the planet would be thick and misty, covering much of the surface as viewed from space.

text: Kepler-452b has a probable mass five times that of Earth, and its surface gravity is twice Earth's, though calculations of mass for exoplanets are only rough estimates. If it is a

text: terrestrial planet

text: , it is most likely a

text: super-Earth

text: with many active volcanoes due to its higher mass and density. The clouds on the planet would be thick and misty, covering much of the surface as viewed from space.

text: Before the scientific search for and study of extrasolar planets, the possibility was argued through philosophy and science fiction. The mediocrity principle suggests that planets like Earth should be common in the universe, while the Rare Earth hypothesis suggests that they are extremely rare. Philosophers have pointed out that the size of the universe is such that a near-identical planet must exist somewhere. In the future, technology may be used by humans to artificially produce an Earth analog by terraforming. The multiverse theory suggests that an Earth analog could exist in another universe or even be another version of the Earth itself in a parallel universe.

text: Before the scientific search for and study of

text: extrasolar planet

text: s, the possibility was argued through philosophy and science fiction. The

text: mediocrity principle

text: suggests that planets like Earth should be common in the

text: universe

text: , while the

text: Rare Earth hypothesis

text: suggests that they are extremely rare. Philosophers have pointed out that the size of the universe is such that a near-identical planet must exist somewhere. In the future,

text: technology

text: may be used by humans to artificially produce an Earth analog by

text: terraforming

text: . The

text: multiverse

text: theory suggests that an Earth analog could exist in another universe or even be another version of the Earth itself in a

text: parallel universe

text: Five evil cyborgs, called the "Five Dastardly Bombers" are bent on taking over the universe. At the planet Earth, they capture the original Bomberman, and he is placed in a prison cell in their base. He awakens in the dungeon of Magnet Bomber and must fight his way to a final showdown with the Magnet Bomber himself. In the following four levels, Bomberman will challenge Golem Bomber, Pretty Bomber, Brain Bomber, and their leader, Plasma Bomber in an effort to free the Earth of these alien invaders as well as save himself.

text: Five evil

text: cyborgs

text: , called the "Five Dastardly Bombers" are bent on taking over the

text: universe

text: . At the planet

text: Earth

text: , they capture the original

text: Bomberman

text: , and he is placed in a prison cell in their base. He awakens in the dungeon of

text: Magnet

text: Bomber and must fight his way to a final showdown with the Magnet Bomber himself. In the following four levels, Bomberman will challenge

text: Golem

text: Bomber,

text: Pretty

text: Bomber,

text: Brain

text: Bomber, and their leader,

text: Plasma

text: Bomber in an effort to free the Earth of these alien invaders as well as save himself.

text: In 1687 Isaac Newton published the Principia in which he included a proof that a rotating self-gravitating fluid body in equilibrium takes the form of an oblate ellipsoid of revolution which he termed an oblate spheroid. Current practice uses the word 'ellipsoid' alone in preference to the full term 'oblate ellipsoid of revolution' or the older term 'oblate spheroid'. In the rare instances (some asteroids and planets) where a more general ellipsoid shape is required as a model the term used is triaxial (or scalene) ellipsoid. A great many ellipsoids have been used with various sizes and centres but modern (post-GPS) ellipsoids are centred at the actual center of mass of the Earth or body being modeled.

text: In 1687

text: Isaac Newton

text: published the

text: Principia

text: in which he included a proof that a rotating self-gravitating fluid body in equilibrium takes the form of an oblate

text: ellipsoid

text: of revolution which he termed an

text: oblate

text: spheroid

text: . Current practice uses the word 'ellipsoid' alone in preference to the full term 'oblate ellipsoid of revolution' or the older term 'oblate spheroid'. In the rare instances (some

text: asteroid

text: s and

text: planet

text: s) where a more general ellipsoid shape is required as a model the term used is

text: triaxial

text: (or scalene) ellipsoid. A great many ellipsoids have been used with various sizes and centres but modern (post-

text: GPS

text: ) ellipsoids are centred at the actual

text: center of mass

text: of the Earth or body being modeled.

text: Ninety-one complete episodes were produced and aired between 2000 and 2005. However, not all episodes were broadcast in the exact order they were produced. The first season originally produced 22 episodes, five of which, prior to the season finale were held back by Fox and were included as part of the second season. 17 episodes were produced for season two, with the addition of the five season one episodes, making it a 22-episode season. Many problems occurred during the production of season three. 19 episodes had been produced for season three, and with Fox cancelling the series later being picked up by The WB, only 11 episode aired through the two networks, 12 & 13 never aired, and episodes 14 through 19, were included as part of season four. The fourth season originally produced 22 episodes, with the new addition of six from season three, making it the longest season with 28 episodes. Season five produced 13 episodes and was the only season to have all its episodes intact.

text: Ninety-one complete episodes were produced and aired between 2000 and 2005. However, not all episodes were broadcast in the exact order they were produced. The first season originally produced 22 episodes, five of which, prior to the season finale were held back by

text: Fox

text: and were included as part of the second season. 17 episodes were produced for season two, with the addition of the five season one episodes, making it a 22-episode season. Many problems occurred during the production of season three. 19 episodes had been produced for season three, and with Fox cancelling the series later being picked up by

text: The WB

text: , only 11 episode aired through the two networks, 12 & 13 never aired, and episodes 14 through 19, were included as part of season four. The fourth season originally produced 22 episodes, with the new addition of six from season three, making it the longest season with 28 episodes. Season five produced 13 episodes and was the only season to have all its episodes intact.

text: Now the question arises: when an Earthling (or Oscar for simplicity's sake) and his twin on Twin Earth say 'water' do they mean the same thing? (The twin is also called 'Oscar' on his own planet, of course. Indeed, the inhabitants of that planet call their own planet 'Earth'. For convenience, we refer to this putative planet as 'Twin Earth', and extend this naming convention to the objects and people that inhabit it, in this case referring to Oscar's twin as Twin-Oscar.)  Ex hypothesi, their brains are molecule-for-molecule identical. Yet, at least according to Putnam, when Oscar says 'water', the term refers to HO, whereas when Twin Oscar says 'water' it refers to XYZ. The result of this is that the contents of a person's brain are not sufficient to determine the reference of terms they use, as one must also examine the causal history that led to this individual acquiring the term. (Oscar, for instance, learned the word 'water' in a world filled with HO, whereas Twin Oscar learned 'water' in a world filled with XYZ.)

text: The narrator, 16-year-old Jeremy Grant, who has been recently orphaned, travels from Australia to Scotland to stay with his scientist uncle, Dr Lachlan McKinnon, at his estate, Inverard. He discovers that the irascible McKinnon and his colleagues, including Swedish Professor Lars Bergman, American engineer Spike Stranahan, science student Janet Campbell, Cockney housekeeper Madge Smith and engineer Kurt Oppenheim, are building an atomic-powered spaceship to travel to Hesikos, the wandering 'lost planet' which is now within a few days' flight of Earth, and which is known to have near-Earth gravity and a breathable atmosphere.

text: The narrator, 16-year-old Jeremy Grant, who has been recently orphaned, travels from Australia to Scotland to stay with his scientist uncle, Dr Lachlan McKinnon, at his estate, Inverard. He discovers that the irascible McKinnon and his colleagues, including Swedish Professor Lars Bergman, American engineer Spike Stranahan, science student Janet Campbell,

text: Cockney

text: housekeeper Madge Smith and engineer Kurt Oppenheim, are building an atomic-powered spaceship to travel to Hesikos, the wandering 'lost planet' which is now within a few days' flight of Earth, and which is known to have near-

text: Earth gravity

text: and a breathable atmosphere.

text: The star is orbited by one known planet, designated Gliese 436 b. The planet has an orbital period of 2.6 Earth days and transits the star as viewed from Earth. It has a mass of 22.2 Earth masses and is roughly 55,000 km in diameter, giving it a mass and radius similar to the ice giant planets Uranus and Neptune in the Solar System. In general, Doppler spectroscopy measurements do not measure the true mass of the planet, but instead measure the product

text: The star is orbited by one known planet, designated

text: Gliese 436 b

text: . The planet has an orbital period of 2.6 Earth days and

text: transits

text: the star as viewed from Earth. It has a mass of 22.2

text: Earth mass

text: es and is roughly 55,000 km in diameter, giving it a mass and radius similar to the

text: ice giant

text: planets

text: Uranus

text: and

text: Neptune

text: in the Solar System. In general, Doppler spectroscopy measurements do not measure the true mass of the planet, but instead measure the product

text: Kepler-4 is named for the Kepler spacecraft, a NASA telescope tasked with finding Earth-like planets that transit their stars as seen from Earth. As the previous three planets that Kepler confirmed had already been confirmed by other finds, Kepler-4 and its planet were the first to be discovered by the Kepler team. The star and its system were announced in Washington, D.C. at the 215th meeting of the American Astronomical Society on January 4, 2010, along with Kepler-5, Kepler-6, Kepler-7, and Kepler-8. Of the presented planets, Kepler-4b was the smallest, around the size of planet Neptune. The discovery of Kepler-4b and the other planets presented at the AAS meeting helped to confirm that the Kepler spacecraft was indeed functional.

text: Kepler-4 is named for the

text: Kepler

text: spacecraft, a

text: NASA

text: telescope tasked with finding

text: Earth-like planets

text: that

text: transit

text: their stars as seen from

text: Earth

text: . As the previous three planets that Kepler confirmed had already been confirmed by other finds, Kepler-4 and its planet were the first to be discovered by the Kepler team. The star and its system were announced in

text: Washington, D.C.

text: at the

entity_name: American Astronomical Society 215th meeting

text: 215th meeting of the American Astronomical Society

text: on January 4, 2010, along with

text: , and

text: . Of the presented planets,

text: was the smallest, around the size of planet

text: Neptune

text: . The discovery of Kepler-4b and the other planets presented at the AAS meeting helped to confirm that the Kepler spacecraft was indeed functional.

text: Cygnus is one of the constellations that the Kepler satellite surveyed in its search for extrasolar planets, and as a result, there are about a hundred stars in Cygnus with known planets, the most of any constellation. One of the most notable systems is the Kepler-11 system, containing six transiting planets, all within a plane of approximately one degree. With a spectral type of G6V, the star is somewhat cooler than the Sun. The planets are very close to the star; all but the last planet are closer to Kepler-11 than Mercury is to the Sun, and all the planets are more massive than Earth. The naked-eye star 16 Cygni, a triple star approximately 70 light-years from Earth composed two Sun-like stars and a red dwarf, contains a planet orbiting one of the sun-like stars, found due to variations in the star's radial velocity. Gliese 777, another naked-eye multiple star system containing a yellow star and a red dwarf, also contains a planet. The planet is somewhat similar to Jupiter, but with slightly more mass and a more eccentric orbit. The Kepler-22 system is also notable, in that its extrasolar planet is believed to be the first "Earth-twin" planet ever discovered.

text: Cygnus is one of the constellations that the

text: Kepler satellite

text: surveyed in its search for

text: extrasolar planet

text: s, and as a result, there are about a hundred stars in Cygnus with known planets, the most of any constellation. One of the most notable systems is the

text: system, containing six

text: transiting planet

text: s, all within a plane of approximately one degree. With a spectral type of G6V, the star is somewhat cooler than the Sun. The planets are very close to the star; all but the last planet are closer to Kepler-11 than

text: Mercury

text: is to the Sun, and all the planets are more massive than Earth. The naked-eye star

text: 16 Cygni

text: , a triple star approximately 70 light-years from Earth composed two Sun-like stars and a

text: red dwarf

text: , contains a planet orbiting one of the sun-like stars, found due to variations in the star's radial velocity.

text: Gliese 777

text: , another naked-eye multiple star system containing a yellow star and a red dwarf, also contains a planet. The planet is somewhat similar to

text: Jupiter

text: , but with slightly more mass and a more eccentric orbit. The

text: system is also notable, in that its extrasolar planet is believed to be the first "Earth-twin" planet ever discovered.

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: After the Moon, Venus was the second object in the Solar System to be explored by radar from the Earth.  The first studies were carried out in 1961 at NASA's Goldstone Observatory, part of the Deep Space Network. At successive inferior conjunctions, Venus was observed both by Goldstone and the National Astronomy and Ionosphere Center in Arecibo. The studies carried out were similar to the earlier measurement of transits of the meridian, which had revealed in 1963 that the rotation of Venus was retrograde (it rotates in the opposite direction to that in which it orbits the Sun). The radar observations also allowed astronomers to determine that the rotation period of Venus was 243.1 days, and that its axis of rotation was almost perpendicular to its orbital plane. It was also established that the radius of the planet was , some  less than the best previous figure obtained with terrestrial telescopes.

text: After the Moon, Venus was the second object in the

text: Solar System

text: to be explored by radar from the Earth.  The first studies were carried out in 1961 at

text: NASA

text: 's

entity_name: Goldstone Deep Space Communications Complex

text: Goldstone Observatory

text: , part of the

text: Deep Space Network

text: . At successive

text: inferior conjunctions

text: , Venus was observed both by Goldstone and the

text: National Astronomy and Ionosphere Center

text: in

text: Arecibo

text: . The studies carried out were similar to the earlier measurement of transits of the

text: meridian

text: , which had revealed in 1963 that the rotation of Venus was

text: retrograde

text: (it rotates in the opposite direction to that in which it orbits the Sun). The radar observations also allowed astronomers to determine that the

text: rotation period

text: of Venus was 243.1 days, and that its

text: axis of rotation

text: was almost perpendicular to its

text: orbital plane

text: . It was also established that the

text: radius

text: of the planet was , some  less than the best previous figure obtained with terrestrial telescopes.

text: The five classical planets, being visible to the naked eye, have been known since ancient times and have had a significant impact on mythology, religious cosmology, and ancient astronomy. In ancient times, astronomers noted how certain lights moved across the sky in relation to the other stars. Ancient Greeks called these lights πλάνητες ἀστέρες (, "wandering stars") or simply πλανῆται (, "wanderers"), from which today's word "planet" was derived. In ancient Greece, China, Babylon, and indeed all pre-modern civilizations, it was almost universally believed that Earth was the center of the Universe and that all the "planets" circled Earth. The reasons for this perception were that stars and planets appeared to revolve around Earth each day and the apparently common-sense perceptions that Earth was solid and stable and that it was not moving but at rest.

text: The five

text: classical planet

text: s, being visible to the naked eye, have been known since ancient times and have had a significant impact on

text: mythology

text: religious cosmology

text: , and ancient

text: astronomy

text: . In ancient times, astronomers noted how certain lights moved across the sky in relation to the other stars. Ancient Greeks called these lights

text: πλάνητες

text: ἀστέρες

text: (, "wandering stars") or simply

text: πλανῆται

text: (, "wanderers"), from which today's word "planet" was derived. In

text: ancient Greece

text: China

text: Babylon

text: , and indeed all pre-modern civilizations, it was almost universally believed that Earth was the

text: center of the Universe

text: and that all the "planets" circled Earth. The reasons for this perception were that stars and planets appeared to revolve around Earth each day and the apparently

text: common-sense

text: perceptions that Earth was solid and stable and that it was not moving but at rest.

text: The effect is caused by the non-concentricity of the Earth and its magnetic dipole. The SAA is the near-Earth region where the Earth's magnetic field is weakest relative to an idealized Earth-centered dipole field.

text: The effect is caused by the

text: non-concentricity

text: of the Earth and its magnetic

text: dipole

text: . The SAA is the near-Earth region where the

text: Earth's magnetic field

text: is weakest relative to an idealized Earth-centered dipole field.

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: The site holds various facilities. The main Land Magnetic Range is a secure and magnetically stable environment, used to measure the magnetic fields found in Mine Counter Measure Vessel equipment. The range uses inbuilt coil systems which enable the Earth's magnetic field to be reduced to zero, simulate anywhere on the planet, or provide only the vertical or horizontal portion of the Earth field to pass through the item under test, which an equivalent Sea Range cannot do. The Compass Test Centre inspects and tests magnetic compasses, whilst also delivering them to RAF stations across the UK. The Compass Base Calibration Surveys is a designated area of survey and certification, used for accurate swinging of Aircraft Navigation Equipment for both military and civilian airfields.

text: Jupiter is the largest, at 318 Earth masses, whereas Mercury is the smallest, at 0.055 Earth masses.

text: Kepler-440b is a super-Earth with a radius 1.86 times that of Earth. The planet orbits Kepler-440 once every 101.1 days.

text: Kepler-440b is a

text: super-Earth

text: with a radius 1.86 times that of

text: Earth

text: . The planet orbits Kepler-440 once every 101.1 days.

text: Remaining essentially "untouched" were day-to-day social relations between husband and wife and children. Attempts at establishing new religions and personal habits come to naught. The revolutions' "results look rather petty as measured by the brotherhood of man and the achievement of justice on this earth. The blood of the martyrs seems hardly necessary to establish decimal coinage." (p. 259)

text: If the moon's mass is not too low compared to the planet, it may in turn stabilize the planet's axial tilt, i.e. its obliquity against the orbit around the star. On Earth, the Moon has played an important role in stabilizing the axial tilt of the Earth, thereby reducing the impact of gravitational perturbations from the other planets and ensuring only moderate climate variations throughout the planet. On Mars, however, a planet without significant tidal effects from its relatively low-mass moons Phobos and Deimos, axial tilt can undergo extreme changes from 13° to 40° on timescales of  to .

text: If the moon's mass is not too low compared to the planet, it may in turn stabilize the planet's

text: axial tilt

text: , i.e. its obliquity against the orbit around the star. On Earth, the

text: Moon

text: has played an important role in stabilizing the axial tilt of the Earth, thereby reducing the impact of gravitational perturbations from the other planets and ensuring only moderate climate variations throughout the planet. On

text: Mars

text: , however, a planet without significant tidal effects from its relatively low-mass moons

text: Phobos

text: and

text: Deimos

text: , axial tilt can undergo extreme changes from 13° to 40° on timescales of  to .

text: Although the network had concerns that the script was too depressing, Moore successfully defended the writing by saying that it might be the last episode of the series and that viewers who had stuck with the show for three and a half seasons would not be put off by yet another "dark" episode. Writers Weddle and Thompson considered giving the characters some leeway in interpreting what they had found.  Among the options debated were giving the fleet some hope that Earth might be some other planet, allowing a character to discover a new part of the Prophecy of Pythia, giving one of the characters a vision of an Earth-like planet, and placing a clue in the ruins that would direct the fleet to yet another planet. All were rejected.

text: Ferrimagnetic materials have high resistivity and have anisotropic properties. The anisotropy is actually induced by an external applied field. When this applied field aligns with the magnetic dipoles it causes a net magnetic dipole moment and causes the magnetic dipoles to precess at a frequency controlled by the applied field, called Larmor or precession frequency. As a particular example, a microwave signal circularly polarized in the same direction as this precession strongly interacts with the magnetic dipole moments; when it is polarized in the opposite direction the interaction is very low. When the interaction is strong, the microwave signal can pass through the material. This directional property is used in the construction of microwave devices like isolators, circulators and gyrators. Ferrimagnetic materials are also used to produce optical isolators and circulators. Ferrimagnetic minerals in various rock types are used to study ancient geomagnetic properties of Earth and other planets. That field of study is known as paleomagnetism.

text: Ferrimagnetic materials have high

text: resistivity

text: and have

text: anisotropic

text: properties. The

text: anisotropy

text: is actually induced by an external applied field. When this applied field aligns with the magnetic dipoles it causes a net magnetic dipole moment and causes the magnetic dipoles to precess at a frequency controlled by the applied field, called

text: Larmor

text: or

text: precession frequency

text: . As a particular example, a

text: microwave

text: signal

text: circularly polarized

text: in the same direction as this precession strongly interacts with the

text: magnetic dipole moments

text: ; when it is polarized in the opposite direction the interaction is very low. When the interaction is strong, the microwave signal can pass through the material. This directional property is used in the construction of microwave devices like

text: isolator

text: s,

text: circulator

text: s and

text: gyrator

text: s. Ferrimagnetic materials are also used to produce

text: optical isolator

text: s and

text: circulators

text: . Ferrimagnetic minerals in various rock types are used to study ancient geomagnetic properties of Earth and other planets. That field of study is known as

text: paleomagnetism

text: Earth's rotation period relative to the Sun—its mean solar day—is 86,400 seconds of mean solar time (86,400.0025 SI seconds). Because Earth's solar day is now slightly longer than it was during the 19th century due to tidal deceleration, each day varies between 0 and 2 SI ms longer.

text: Earth's rotation period relative to the Sun—its mean solar day—is 86,400 seconds of mean solar time (86,400.0025

text: SI

text: seconds). Because Earth's solar day is now slightly longer than it was during the 19th century due to

text: tidal deceleration

text: , each day varies between 0 and 2 SI

text: ms

text: longer.

text: Left in the care of an unscrupulous scientist called "Doc 30", he escaped while Douglas remained behind. When the Earth was dying due to the extinguishing of the sun in the so-called the Final Night, he first helps Perry White, who was determined the Daily Planet would not miss one day of delivery. Then he becomes involved with the Legion of Super-Heroes, who had become stranded in the present day. This team joins with dozens of other superheroes to help try to save the Earth. Ferro comes close to heroically sacrificing his life in an effort to stop the Sun-Eater. At the last instant, he is saved by Hal Jordan, who was maintaining the power and identity of Parallax. Jordan seemingly sacrifices his own life and the sun is restored. Ferro remains with the team, although it was some time before they informed him they were from the 31st Century.

text: Left in the care of an unscrupulous scientist called "Doc 30", he escaped while Douglas remained behind. When the Earth was dying due to the extinguishing of the sun in the so-called the

text: Final Night

text: , he first helps

text: Perry White

text: , who was determined the

text: Daily Planet

text: would not miss one day of delivery. Then he becomes involved with the Legion of Super-Heroes, who had become stranded in the present day. This team joins with dozens of other superheroes to help try to save the Earth. Ferro comes close to heroically sacrificing his life in an effort to stop the Sun-Eater. At the last instant, he is saved by

text: Hal Jordan

text: , who was maintaining the power and identity of

text: Parallax

text: . Jordan seemingly sacrifices his own life and the sun is restored. Ferro remains with the team, although it was some time before they informed him they were from the 31st Century.

text: In Philolaus's system a sphere of the fixed stars, the five planets, the Sun, Moon and Earth, all moved round his Central Fire. According to Aristotle writing in Metaphysics, Philolaus added a tenth unseen body, he called Counter-Earth, as without it there would be only nine revolving bodies, and the Pythagorean number theory required a tenth. However, according to Greek scholar George Burch, Aristotle was lampooning Philolaus's ideas. In reality, Philolaus' ideas predated the idea of spheres by hundreds of years. Nearly two-thousand years later Nicolaus Copernicus would mention in De revolutionibus that Philolaus already knew about the Earth's revolution around a central fire.

text: In Philolaus's system a sphere of the fixed

text: star

text: s, the five

text: planet

text: s, the

text: Sun

text: Moon

text: and Earth, all moved round his Central Fire. According to

text: Aristotle

text: writing in

text: Metaphysics

text: , Philolaus added a tenth unseen body, he called

text: Counter-Earth

text: , as without it there would be only nine revolving bodies, and the Pythagorean

text: number theory

text: required a tenth. However, according to Greek scholar George Burch, Aristotle was lampooning Philolaus's ideas. In reality, Philolaus' ideas predated the idea of spheres by hundreds of years. Nearly two-thousand years later

text: Nicolaus Copernicus

text: would mention in

text: De revolutionibus

text: that Philolaus already knew about the Earth's revolution around a central fire.

text: This planet may have Earth-like moons with bodies of water and possibly life. But giving the planet's high eccentricity, life on the moons may not evolve as well as those on Earth. From the surface of the moon, ones may see parent planet in the sky about half of the times with different phases just like the Moon seen from Earth, as well as other moons. If this planet has rings nearly as prominent as Saturn's, then the rings can be seen surrounding the planet, making this scenery even more amazing.

text: This planet may have

text: Earth-like moons

text: with bodies of water and possibly life. But giving the planet's high eccentricity, life on the moons may not evolve as well as those on Earth. From the surface of the moon, ones may see parent planet in the sky about half of the times with different phases just like the

text: Moon

text: seen from Earth, as well as other moons. If this planet has rings nearly as prominent as Saturn's, then the rings can be seen surrounding the planet, making this scenery even more amazing.

text: Rare Earth's assertion that the Moon's stabilization of Earth's obliquity and spin is a requirement for complex life has been questioned. Kasting argues that a moonless Earth would still possess habitats with climates suitable for complex life and questions whether the spin rate of a moonless Earth can be predicted. Although the giant impact theory posits that the impact forming the Moon increased Earth's rotational speed to make a day about 5 hours long, the Moon has slowly "stolen" much of this speed to reduce Earth's solar day since then to about 24 hours and continues to do so: in 100 million years Earth's solar day will be roughly 24 hours 38 minutes (the same as Mars's solar day); in 1 billion years, 30 hours 23 minutes. Larger secondary bodies would exert proportionally larger tidal forces that would in turn decelerate their primaries faster and potentially increase the solar day of a planet in all other respects like earth to over 120 hours within a few billion years. This long solar day would make effective heat dissipation for organisms in the tropics and subtropics extremely difficult in a similar manner to tidal locking to a red dwarf star. Short days (high rotation speed) causes high wind speeds at ground level. Long days (slow rotation speed) cause the day and night temperatures to be too extreme.

text: Rare Earth's assertion that the Moon's stabilization of Earth's obliquity and spin is a requirement for complex life has been questioned. Kasting argues that a moonless Earth would still possess habitats with climates suitable for complex life and questions whether the spin rate of a moonless Earth can be predicted. Although the

text: giant impact theory

text: posits that the impact forming the Moon increased Earth's rotational speed to make a day about 5 hours long, the Moon has slowly "

text: stolen

text: " much of this speed to reduce Earth's solar day since then to about 24 hours and continues to do so: in 100 million years Earth's solar day will be roughly 24 hours 38 minutes (the same as Mars's solar day); in 1 billion years, 30 hours 23 minutes. Larger secondary bodies would exert proportionally larger tidal forces that would in turn decelerate their primaries faster and potentially increase the solar day of a planet in all other respects like earth to over 120 hours within a few billion years. This long solar day would make effective heat dissipation for organisms in the tropics and subtropics extremely difficult in a similar manner to tidal locking to a red dwarf star. Short days (high rotation speed) causes high wind speeds at ground level. Long days (slow rotation speed) cause the day and night temperatures to be too extreme.

text: The dusty material in the system was analyzed in 2007 by a group led by Dr. Carey Lisse, of the Johns Hopkins University Applied Physics Laboratory in Laurel, MD, USA.  Observations were made using the infrared spectrometer on board the Spitzer Space Telescope, and interpreted using the results of the NASA Deep Impact and STARDUST missions. Analysis of the atomic and mineral composition, dust temperature, and dust mass show a huge amount of warm material similar to metal rich S-type asteroids in a narrow belt at 1.8 ± 0.2 AU from the  HD 113766 A. The group found at least a Mars' mass worth of warm dust in particles of size 10 m or less, and very likely as much as a few Earth masses of dust if one adds in the contribution of material in bodies up to 1 km in radius which are currently thought to be the basic building blocks of rocky planet formation. Comparison with current planetary formation theories suggests that the disk is in the early stages of terrestrial (rocky) planet formation.  This can be also inferred by the presence of metals in the rocky material making up the disk.  If planets had already formed the high density metals should have sunk to their cores during the molten stage of planet formation; a process known as planetary differentiation.

text: The dusty material in the system was analyzed in 2007 by a group led by Dr. Carey Lisse, of the

text: Johns Hopkins University Applied Physics Laboratory

text: in

text: Laurel, MD

text: , USA.  Observations were made using the

text: infrared

text: spectrometer

text: on board the

text: Spitzer Space Telescope

text: , and interpreted using the results of the

text: NASA

text: Deep Impact

text: and

text: STARDUST

text: missions. Analysis of the atomic and mineral composition, dust temperature, and dust mass show a huge amount of warm material similar to metal rich S-type

text: asteroid

text: s in a narrow belt at 1.8 ± 0.2

text: AU

text: from the  HD 113766 A. The group found at least a Mars' mass worth of warm dust in particles of size 10 m or less, and very likely as much as a few Earth masses of dust if one adds in the contribution of material in bodies up to 1 km in radius which are currently thought to be the basic building blocks of rocky planet formation. Comparison with current planetary formation theories suggests that the disk is in the early stages of terrestrial (rocky) planet formation.  This can be also inferred by the presence of metals in the rocky material making up the disk.  If planets had already formed the high density metals should have sunk to their cores during the molten stage of planet formation; a process known as

text: planetary differentiation

text: The atmosphere of planet Earth, and the Earth's magnetic field, protect us from impact and irradiation by a wide range of objects that fly around in space.  Those who know about these effects can often learn from them a lot about the history of extraterrestrial materials.

text: As with all exoplanets, Kepler-11d is named first for its host star, Kepler-11. Because Kepler-11d was announced at the same time as the five other planets in the system, their names are sorted by their distances from the host star; thus, because Kepler-11d is the third planet from Kepler-11, it was given the designation d. Kepler-11 was named for the Kepler spacecraft, a NASA Earth-trailing satellite purposed with discovering Earth-like planets in a small area of the sky between the constellations Cygnus and Lyra by observing planets that transit, or cross in front of, their host stars with respect to Earth. The transit causes the star's brightness to dim slightly and at a regular rate, a phenomenon that the Kepler satellite notes till future study can prove or disprove the existence of a planetary body. Kepler-11d was flagged by Kepler-11, given the designation KOI-157.

text: As with all exoplanets, Kepler-11d is named first for its host star,

text: . Because Kepler-11d was announced at the same time as the five other planets in the system, their names are sorted by their distances from the host star; thus, because Kepler-11d is the third planet from Kepler-11, it was given the designation d. Kepler-11 was named for the

text: Kepler spacecraft

text: , a

text: NASA

text: Earth-trailing satellite purposed with discovering

text: Earth-like planets

text: in a small area of the sky between the constellations

text: Cygnus

text: and

text: Lyra

text: by observing planets that

text: transit

text: , or cross in front of, their host stars with respect to Earth. The transit causes the star's brightness to dim slightly and at a regular rate, a phenomenon that the Kepler satellite notes till future study can prove or disprove the existence of a planetary body. Kepler-11d was flagged by Kepler-11, given the designation

text: KOI

text: Because Earth follows an elliptical orbit around the Sun, its solar mass can be computed from the equation for the orbital period of a small body orbiting a central mass. Based upon the length of the year, the distance from Earth to the Sun (an astronomical unit or AU), and the gravitational constant (), the mass of the Sun is given by:

text: Because Earth follows an

text: elliptical orbit

text: around the Sun, its solar mass can be computed from the equation for the

text: orbital period

text: of a small body orbiting a central mass. Based upon the length of the year, the distance from Earth to the Sun (an

text: astronomical unit

text: or AU), and the

text: gravitational constant

text: (), the mass of the Sun is given by:

text: A terrestrial planet of the right size is needed to retain an atmosphere, like Earth and Venus. On Earth, once the giant impact of Theia thinned Earth's Atmosphere other events were needed to make the atmosphere capable of sustaining life for a long time span. On Earth the Late Heavy Bombardment reseeded Earth with water lost after the impact of Theia. The development of an ozone layer formed protection from ultraviolet (UV) radiation from the Sun.  Nitrogen and carbon dioxide are needed in a correct ratio for life to form. Nitrogen is needed for amino and nucleic acids. Lightning is needed for nitrogen fixation to happen. The carbon dioxide gas needed for life comes from sources such as volcanoes and geysers. Carbon dioxide is only needed at low levels, in Earth's atmosphere it is at 0.04 percent (400 ppm) by volume of the atmosphere. At high levels carbon dioxide is a poisonous. Precipitation is needed to have a stable water cycle. A proper atmosphere must reduce temperature extremes between day and night (the diurnal temperature variation).

text: A terrestrial planet of the right size is needed to retain an atmosphere, like Earth and Venus. On Earth, once the giant impact of

text: Theia

text: thinned

text: Earth's Atmosphere

text: other events were needed to make the atmosphere capable of sustaining life for a long time span. On Earth the

text: Late Heavy Bombardment

text: reseeded Earth with water lost after the impact of Theia. The development of an

text: ozone layer

text: formed protection from

text: ultraviolet

text: (UV) radiation from the Sun.

text: Nitrogen

text: and

text: carbon dioxide

text: are needed in a correct ratio for life to form. Nitrogen is needed for

text: amino

text: and

text: nucleic acid

text: s.

text: Lightning

text: is needed for

text: nitrogen fixation

text: to happen. The carbon dioxide

text: gas

text: needed for life comes from sources such as

text: volcano

text: es and

text: geyser

text: s. Carbon dioxide is only needed at low levels, in Earth's atmosphere it is at 0.04 percent (400

text: ppm

text: ) by volume of the atmosphere. At high levels carbon dioxide is a poisonous.

text: Precipitation

text: is needed to have a stable water cycle. A proper atmosphere must reduce

text: temperature

text: extremes between

text: day

text: and

text: night

text: (the

text: diurnal temperature variation

text: Genji is a Super-Earth but only moderately so: it has 2.8 times the mass and 1.36 times the diameter of Earth, and 1.5 times Earth's gravity. The side of the planet that constantly faces its companion world Chujo (“Moonside”) is mostly land, the other hemisphere (“Starside”) is mostly ocean. The mean surface temperature is +20 °C, slightly warmer than Earth. Although humans in good condition can physically accommodate to the high gravity, the sea level air pressure of 3.1 bars which results from this gravity (as per the barometric formula) requires artificial decompression for safe breathing. Only at 5,800 meters (an altitude found on this planet only in the form of a few small highlands that are cold and arid) the atmospheric pressure drops to Earth-standard 1 bar.

text: Genji is a

text: Super-Earth

text: but only moderately so: it has 2.8 times the mass and 1.36 times the diameter of Earth, and 1.5 times

text: Earth's gravity

text: . The side of the planet that constantly faces its companion world Chujo (“Moonside”) is mostly land, the other hemisphere (“Starside”) is mostly ocean. The mean surface temperature is +20 °C, slightly warmer than Earth. Although humans in good condition can physically accommodate to the high gravity, the sea level air pressure of 3.1 bars which results from this gravity (as per the

text: barometric formula

text: ) requires artificial decompression for

text: safe breathing

text: . Only at 5,800 meters (an altitude found on this planet only in the form of a few small highlands that are cold and arid) the atmospheric pressure drops to Earth-standard 1 bar.

text: Earth science generally recognizes 4 spheres, the lithosphere, the hydrosphere, the atmosphere, and the biosphere as correspondent to rocks, water, air, and life respectively. Some scientists include, as part of the spheres of the Earth, the cryosphere (corresponding to ice) as a distinct portion of the hydrosphere, as well as the pedosphere (corresponding to soil) as an active and intermixed sphere. Earth science (also known as geoscience, the geosciences or the Earth Sciences), is an all-embracing term for the sciences related to the planet Earth. There are four major disciplines in earth sciences, namely geography, geology, geophysics and geodesy. These major disciplines use physics, chemistry, biology, chronology and mathematics to build a qualitative and quantitative understanding of the principal areas or spheres of Earth.

text: Earth science generally recognizes 4 spheres, the

text: lithosphere

text: , the

text: hydrosphere

text: , the

text: atmosphere

text: , and the

text: biosphere

text: as correspondent to

text: rocks

text: water

text: air

text: , and

text: life

text: respectively. Some scientists include, as part of the spheres of the Earth, the

text: cryosphere

text: (corresponding to

text: ice

text: ) as a distinct portion of the hydrosphere, as well as the

text: pedosphere

text: (corresponding to

text: soil

text: ) as an active and intermixed sphere.

text: Earth science

text: (also known as geoscience, the geosciences or the Earth Sciences), is an all-embracing term for the

text: science

text: s related to the planet

text: Earth

text: . There are four major

text: discipline

text: s in earth sciences, namely

text: geography

text: geology

text: geophysics

text: and

text: geodesy

text: . These major disciplines use

text: physics

text: chemistry

text: biology

text: chronology

text: and

text: mathematics

text: to build a qualitative and quantitative understanding of the principal areas or

text: spheres

text: of Earth.

text: Gethen orbits its primary star once every 0.96 Earth years (8401 Earth hours). The planet rotates around its axis in 23.08 earth hours, so a Gethenian year consists of 364 local days.

text: Gethen

text: orbits

text: its primary star once every 0.96 Earth years (8401 Earth hours). The planet rotates around its axis in 23.08 earth hours, so a Gethenian year consists of 364 local days.

text: According to one hypothesis, super-Earths of about two Earth masses may be conducive to life. The higher surface gravity would lead to a thicker atmosphere, increased surface erosion and hence a flatter topography. The end result could be an "archipelago planet" of shallow oceans dotted with island chains ideally suited for biodiversity. A more massive planet of two Earth masses would also retain more heat within its interior from its initial formation much longer, sustaining plate tectonics (which is vital for regulating the carbon cycle and hence the climate) for longer. The thicker atmosphere and stronger magnetic field would also shield life on the surface against harmful cosmic rays.

text: According to one hypothesis, super-Earths of about two Earth masses may be conducive to life. The higher surface gravity would lead to a thicker atmosphere, increased surface erosion and hence a flatter topography. The end result could be an "archipelago planet" of shallow oceans dotted with island chains ideally suited for

text: biodiversity

text: . A more massive planet of two Earth masses would also retain more heat within its interior from its initial formation much longer, sustaining

text: plate tectonics

text: (which is vital for regulating the

text: carbon cycle

text: and hence the

text: climate

text: ) for longer. The thicker atmosphere and stronger magnetic field would also shield life on the surface against harmful

text: cosmic rays

text: In geology, the structure of the interior of a planet is often illustrated using a diagram of a cross section of the planet that passes through the planet's center, as in the cross section of Earth at right.

text: In

text: geology

text: , the structure of the interior of a

text: planet

text: is often illustrated using a diagram of a cross section of the planet that passes through the planet's center, as in the cross section of

text: Earth

text: at right.

text: .  However, velocity at the surface is equal to the product of radius and rotational velocity, and therefore the force is directly proportional to radius.  Viewing the globe as a series of rotating discs, the radius R toward the poles gets very small and thus a smaller force is produced for the same rotational velocity (approaching zero at the pole). Moving towards the equator, v^2 increases much faster than R, thus producing the greatest force at the equator.  In addition, because the Earth’s dense core is included in the cross sectional disc at the equator, it contributes more to the mass of the disc.  Similarly, there is a bulge in the water envelope of the oceans surrounding Earth;  this bulge is created by the greater centrifugal force at the equator and is independent of tides. Sea level at the equator is 21.36 km higher than sea level at the poles, in terms of distance from the center of the planet.

text: For a rapidly rotating planet such as the Earth, calculation of trajectories passing close to it, less than a dozen radii, should include the oblateness of the planet—its gravitational field is not spherically symmetric. For even closer trajectories, gravity anomalies may be important.

text: For a rapidly rotating planet such as the Earth, calculation of trajectories passing close to it, less than a dozen radii, should include the oblateness of the planet—its gravitational field is not spherically symmetric. For even closer trajectories,

text: gravity anomalies

text: may be important.

text: This is larger than the planet Earth would weigh if weighed on another Earth. The atomic nuclei in one jug also repel those in the other with the same force. However, these repulsive forces are canceled by the attraction of the electrons in jug A with the nuclei in jug B and the attraction of the nuclei in jug A with the electrons in jug B, resulting in no net force. Electromagnetic forces are tremendously stronger than gravity but cancel out so that for large bodies gravity dominates.

text: This is larger than the planet Earth would weigh if weighed on another Earth. The

text: atomic nuclei

text: in one jug also repel those in the other with the same force. However, these repulsive forces are canceled by the attraction of the electrons in jug A with the nuclei in jug B and the attraction of the nuclei in jug A with the electrons in jug B, resulting in no net force. Electromagnetic forces are tremendously stronger than gravity but cancel out so that for large bodies gravity dominates.

text: Earth's magnetism varies from place to place and differences in the Earth's magnetic field (the magnetosphere) can be caused by two things:

text: K2-3d is a super-Earth, meaning it has a mass and radius bigger than Earth's, but smaller than that of the ice giants Uranus and Neptune. It has a surface temperature of  and a radius of 1.61 . Normally, a planet of this size would be a mini-Neptune, with no solid surface. However, its unusual density when fit for a radius of K2-3d's size would make it an exception to this rule, giving it a solid surface: its density is 11.7±6.7 g/cm. This is far greater than the density of iron. Because of this, a composition of almost pure iron with some silicate (rocky) mixed in is likely, giving it a mass of around 7.5 . For it to be completely iron, it would have to be 14 times more massive than Earth; however, this is unlikely.

text: K2-3d is a

text: super-Earth

text: , meaning it has a mass and radius bigger than Earth's, but smaller than that of the ice giants

text: Uranus

text: and

text: Neptune

text: . It has a surface temperature of  and a radius of 1.61 . Normally, a planet of this size would be a

text: mini-Neptune

text: , with no solid surface. However, its unusual

text: density

text: when fit for a radius of K2-3d's size would make it an exception to this rule, giving it a solid surface: its density is 11.7±6.7 g/cm. This is far greater than the density of

text: iron

text: . Because of this, a composition of almost pure iron with some silicate (rocky) mixed in is likely, giving it a mass of around 7.5 . For it to be completely iron, it would have to be 14 times more massive than Earth; however, this is unlikely.

text: Athanael (Jack Benny), the third trumpet player in the orchestra of a late night radio show sponsored by Paradise Coffee (motto: "It's Heavenly"), falls asleep listening to the announcer, who is doing his best to prove it is "the coffee that makes you sleep."  Athanael dreams he is an angel (junior grade) and a trumpeter in the orchestra of Heaven. Due to the praise of his girlfriend Elizabeth (Alexis Smith), the assistant of the deputy chief of the department of small planet management (Guy Kibbee), he is given the mission of destroying planet 339001 (Earth) and its troublesome inhabitants by blowing the "Last Trumpet" at exactly midnight, signaling the end of the world.

text: Athanael (Jack Benny), the third

text: trumpet

text: player in the orchestra of a late night radio show sponsored by Paradise Coffee (motto: "It's Heavenly"), falls asleep listening to the announcer, who is doing his best to prove it is "the coffee that makes you sleep."  Athanael dreams he is an angel (junior grade) and a trumpeter in the orchestra of Heaven. Due to the praise of his girlfriend Elizabeth (

text: Alexis Smith

text: ), the assistant of the deputy chief of the department of small planet management (

text: Guy Kibbee

text: ), he is given the mission of destroying planet 339001 (Earth) and its troublesome inhabitants by blowing the "Last Trumpet" at exactly midnight, signaling the

text: end of the world

text: In his 1966 article, ibn Baz did claim that the sun orbited the earth, and that "the earth is fixed and stable, spread out by God for mankind and made a bed and cradle for them, fixed down by mountains lest it shake". As a result of the publication of his first article, ibn Baz was ridiculed by Egyptian journalists as an example of Saudi primitiveness, and King Faisal was reportedly so angered by the first article that he ordered the destruction of every unsold copy of the two papers that had published it. In 1982 Ibn Baz published a book, Al-adilla al-naqliyya wa al-ḥissiyya ʿala imkān al-ṣuʾūd ila al-kawākib wa ʾala jarayān al-shams wa al-qamar wa sukūn al-arḍ ("Treatise on the textual and rational proofs of the rotation of the sun and the motionlessness of the earth and the possibility of ascension to other planets"). In it, he republished the 1966 article, together with a second article on the same subject written later in 1966, and repeated his belief that the sun orbited the earth. In 1985, he changed his mind concerning the rotation of the earth (and, according to Lacey, ceased to assert its flatness), when Prince Sultan bin Salman returned home after a week aboard the space shuttle Discovery to tell him that he had seen the earth rotate.

text: In his 1966 article, ibn Baz did claim that the sun orbited the earth, and that "the earth is fixed and stable, spread out by God for mankind and made a bed and cradle for them, fixed down by mountains lest it shake". As a result of the publication of his first article, ibn Baz was ridiculed by Egyptian journalists as an example of Saudi primitiveness, and

text: King Faisal

text: was reportedly so angered by the first article that he ordered the destruction of every unsold copy of the two papers that had published it. In 1982 Ibn Baz published a book, Al-adilla al-naqliyya wa al-ḥissiyya ʿala imkān al-ṣuʾūd ila al-kawākib wa ʾala jarayān al-shams wa al-qamar wa sukūn al-arḍ ("Treatise on the textual and rational proofs of the rotation of the sun and the motionlessness of the earth and the possibility of ascension to other planets"). In it, he republished the 1966 article, together with a second article on the same subject written later in 1966, and repeated his belief that the sun orbited the earth. In 1985, he changed his mind concerning the rotation of the earth (and, according to Lacey, ceased to assert its flatness), when

text: Prince Sultan bin Salman

text: returned home after a week aboard the space shuttle

text: Discovery

text: to tell him that he had seen the earth rotate.

text: Orpheus was the fourth planet in our solar system, it was also the sixth largest. Its orbit intersected Earth's orbital path every 50 years. Rich in life, it gave rise to sophisticated human, animal and robot civilizations. About 2.1 billion years ago, after avoiding proto-Earth for countless years, these two planets inevitably collided. Orpheus was obliterated and the Earth shattered. Eventually, Orpheus's fragments coalesced to form Earth's moon, which stabilized our planet's erratic rotation and allowed life to germinate. Robota is the story of life before the collision and the conflict between animal life and the machines that sought to dominate them.

text: Orpheus was the fourth planet in our solar system, it was also the sixth largest. Its orbit intersected Earth's orbital path every 50 years. Rich in life, it gave rise to sophisticated human, animal and robot civilizations. About 2.1 billion years ago, after avoiding proto-

text: Earth

text: for countless years, these two planets inevitably collided. Orpheus was obliterated and the Earth shattered. Eventually, Orpheus's fragments coalesced to form Earth's moon, which stabilized our planet's erratic rotation and allowed life to germinate. Robota is the story of life before the collision and the conflict between animal life and the machines that sought to dominate them.

text: While revolution is often used as a synonym for rotation, in many fields, particularly astronomy and related fields, revolution, often referred to as orbital revolution for clarity, is used when one body moves around another while rotation is used to mean the movement around an axis. Moons revolve around their planet, planets revolve about their star (such as the Earth around the Sun); and stars slowly revolve about their galaxial center. The motion of the components of galaxies is complex, but it usually includes a rotation component.

text: While revolution is often used as a synonym for rotation, in many fields, particularly astronomy and related fields, revolution, often referred to as orbital revolution for clarity, is used when one body moves around another while rotation is used to mean the movement around an axis. Moons revolve around their planet, planets revolve about their star (such as the Earth around the Sun); and stars slowly revolve about their

text: galaxial center

text: . The motion of the components of

text: galaxies

text: is complex, but it usually includes a rotation component.

text: Earth mass () is the unit of mass equal to that of the Earth. 1  = . Earth mass is often used to describe masses of rocky terrestrial planets. It is also used to describe Neptune-mass planets. One Earth mass is  times a Jupiter mass.

text: Earth mass () is the unit of

text: mass

text: equal to that of the

text: Earth

text: . 1  = . Earth mass is often used to describe masses of rocky

text: terrestrial planet

text: s. It is also used to describe Neptune-mass planets. One Earth mass is  times a Jupiter mass.

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: For a planet, angular momentum is distributed between the spin of the planet and its revolution in its orbit, and these are often exchanged by various mechanisms. The conservation of angular momentum in the Earth–Moon system results in the transfer of angular momentum from Earth to Moon, due to tidal torque the Moon exerts on the Earth. This in turn results in the slowing down of the rotation rate of Earth, at about 65.7 nanoseconds per day, and in gradual increase of the radius of Moon's orbit, at about 3.82 centimeters per year.

text: For a planet, angular momentum is distributed between the spin of the planet and its revolution in its orbit, and these are often exchanged by various mechanisms. The conservation of angular momentum in the

text: Earth–Moon system

text: results in the transfer of angular momentum from Earth to Moon, due to

text: tidal torque

text: the Moon exerts on the Earth. This in turn results in the slowing down of the rotation rate of Earth, at about 65.7 nanoseconds per day, and in gradual increase of the radius of Moon's orbit, at about 3.82 centimeters per year.

text: Five star systems have been found to have planets, four of which have been discovered by the High Accuracy Radial Velocity Planet Searcher (HARPS) in Chile. HD 4308 is a star with around 83% of the Sun's mass located 72 light-years away with a super-Earth planet with an orbital period of around 15 days. HD 215497 is an orange star of spectral type K3V around 142 light-years distant. It is orbited by a hot super-Earth every 3 days and a second planet around the size of Saturn with a period of around 567 days. HD 221287 has a spectral type of F7V and lies 173 light-years away, and has a super-Jovian planet. HD 7199 has spectral type KOIV/V and is located 117 light-years away. It has a planet with around 30% the mass of Jupiter that has an orbital period of 615 days. HD 219077 has a planet around 10 times as massive as Jupiter in a highly eccentric orbit.

text: Five star systems have been found to have planets, four of which have been discovered by the

text: High Accuracy Radial Velocity Planet Searcher

text: (HARPS) in Chile.

text: HD 4308

text: is a star with around 83% of the Sun's mass located 72 light-years away with a

text: super-Earth

text: planet with an orbital period of around 15 days.

text: HD 215497

text: is an orange star of spectral type K3V around 142 light-years distant. It is orbited by a hot super-Earth every 3 days and a second planet around the size of Saturn with a period of around 567 days.

text: HD 221287

text: has a spectral type of F7V and lies 173 light-years away, and has a

text: super-Jovian

text: planet.

text: HD 7199

text: has spectral type KOIV/V and is located 117 light-years away. It has a planet with around 30% the mass of Jupiter that has an orbital period of 615 days.

text: HD 219077

text: has a planet around 10 times as massive as Jupiter in a highly eccentric orbit.

text: The Earth's rate of rotation is slowing down mainly because of tidal interactions with the Moon and the Sun. Since the solid parts of the Earth are ductile, the Earth's equatorial bulge has been decreasing in step with the decrease in the rate of rotation.

text: The Earth's rate of rotation is slowing down mainly because of tidal interactions with the Moon and the Sun. Since the solid parts of the Earth are

text: ductile

text: , the Earth's equatorial bulge has been decreasing in step with the decrease in the rate of rotation.

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: Day and Night meet and at first are uneasy about each other. They are dismissive of each other because each perceives the other as being different, and their prejudices result in a physical altercation between the two. However, as the characters discovers the many fascinating events that occur in each other, they learn to appreciate them, and learn to like one another. At the end of the film, the Sun descends in Day and rises in Night, so that when the Sun is at the same height above the horizon in both, both characters appear to be identical. As the Sun continues its course, Day becomes Night, and Night becomes Day.

text: Monarch's battles get underway, as Eve of Shadows (Earth-13), Vampire Batman (Earth-43), Ray "the Ray" Palmer (Earth-6), Scarab (Earth-26), Hal Jordan Jr. (Earth-12), Starwoman (Earth-7), Johnny Quick (Earth-3), and Wonder Woman (Earth-34) are selected as Monarch's champions. The Batman of Earth-19 and Apollo of Earth-50 become Monarch's "backups", held in stasis. Throughout the series, tensions build between the all-American Superman of Earth-31 and his Russian Earth-30 counterpart. Superman-31 and Vampire Bat discover that a transporter miraculously designed by Earth-33's Ted Kord can travel the multiverse. After the group realizes the connection between Monarch and Captain Atom, Breach volunteers to collect the other counterparts from across the 52 earths in an attempt to overpower Monarch. In the conclusion, the Supermen fight is interrupted by a barrage of alternate Captain Atoms, who Monarch is able to overpower and absorb into himself. This reveals Ted Kord-33 and Breach (actually the brainwashed Breach of New Earth, not of Earth-8) to be his accomplices. Breach betrays Monarch by giving Superman-31 the transporter to save everyone on board the ship. The last man standing after Superman-31's departure and Superman of Earth-16's sacrifice, the Red Son Superman of Earth-30 becomes Monarch's final team member.

text: Monarch's battles get underway, as Eve of Shadows (

text: ), Vampire Batman (

text: ), Ray "the Ray" Palmer (

text: ), Scarab (

entity_name: Captain Carrot and His Amazing Zoo Crew!

text: ), Hal Jordan Jr. (

text: ), Starwoman (

text: ), Johnny Quick (

text: ), and Wonder Woman (

text: ) are selected as Monarch's champions. The Batman of

text: and Apollo of

text: become Monarch's "backups", held in stasis. Throughout the series, tensions build between the all-American Superman of

text: and his Russian

text: counterpart. Superman-31 and Vampire Bat discover that a transporter miraculously designed by

text: 's Ted Kord can travel the multiverse. After the group realizes the connection between Monarch and Captain Atom, Breach volunteers to collect the other counterparts from across the 52 earths in an attempt to overpower Monarch. In the conclusion, the Supermen fight is interrupted by a barrage of alternate Captain Atoms, who Monarch is able to overpower and absorb into himself. This reveals Ted Kord-33 and Breach (actually the brainwashed Breach of

text: New Earth

text: , not of

text: ) to be his accomplices. Breach betrays Monarch by giving Superman-31 the transporter to save everyone on board the ship. The last man standing after Superman-31's departure and Superman of

text: 's sacrifice, the Red Son Superman of Earth-30 becomes Monarch's final team member.

text: Timekeeping on Mars can be more complex, since the planet has a solar day of approximately 24 hours and 39 minutes, known as a sol. Earth controllers for some Mars missions have synchronized their sleep/wake cycles with the Martian day, because solar-powered rover activity on the surface was tied to periods of light and dark. The difference in day length caused the sleep/wake cycles to slowly drift with respect to the day/night cycles on Earth, repeating approximately once every 36 days.

text: Timekeeping on Mars

text: can be more complex, since the planet has a solar day of approximately 24 hours and 39 minutes, known as a

text: sol

text: . Earth controllers for some Mars missions have synchronized their sleep/wake cycles with the Martian day, because solar-powered rover activity on the surface was tied to periods of light and dark. The difference in day length caused the sleep/wake cycles to slowly drift with respect to the day/night cycles on Earth, repeating approximately once every 36 days.

text: The planet's highly eccentric orbit means the planet would experience extreme seasonal effects. Despite this, simulations suggest that an Earth-like moon would be able to support liquid water at its surface over the course of a year.  Due to the eccentric orbit of this massive gas giant, it is unlikely that a habitable planet could survive in this system.

text: The planet's highly eccentric orbit means the planet would experience extreme

text: season

text: al effects. Despite this, simulations suggest that an

text: Earth

text: -like

text: moon

text: would be able to support liquid water at its surface over the course of a year.  Due to the eccentric orbit of this massive gas giant, it is unlikely that a

text: habitable planet

text: could survive in this system.

text: and has a magnitude of about 9.81 meters per second squared (this measurement is taken from sea level and may vary depending on location), and points toward the center of the Earth. This observation means that the force of gravity on an object at the Earth's surface is directly proportional to the object's mass. Thus an object that has a mass of

text: and has a magnitude of about 9.81

text: meter

text: s per second squared (this measurement is taken from sea level and may vary depending on location), and points toward the center of the Earth. This observation means that the force of gravity on an object at the Earth's surface is directly proportional to the object's mass. Thus an object that has a mass of

text: In many cultures, nights are named after the previous day. For example,"Friday night" usually means the entire night between Friday and Saturday. This difference from the civil day often leads to confusion. Events starting at midnight are often announced as occurring the day before. TV-guides tend to list nightly programs at the previous day, although programming a VCR requires the strict logic of starting the new day at 00:00 (to further confuse the issue, VCRs set to the 12-hour clock notation will label this "12:00 AM"). Expressions like "today", "yesterday" and "tomorrow" become ambiguous during the night.   Because Jews and Muslims begin their days at nightfall, "Saturday" night, for example, is what most people would call Friday night.

text: In many cultures, nights are named after the previous day. For example,"Friday night" usually means the entire night between Friday and Saturday. This difference from the civil day often leads to confusion. Events starting at midnight are often announced as occurring the day before. TV-guides tend to list nightly programs at the previous day, although programming a

text: VCR

text: requires the strict logic of starting the new day at 00:00 (to further confuse the issue, VCRs set to the 12-hour clock notation will label this "12:00 AM"). Expressions like "today", "yesterday" and "tomorrow" become ambiguous during the night.   Because Jews and Muslims begin their days at nightfall, "Saturday" night, for example, is what most people would call Friday night.

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: Kepler296f is a super-Earth with a radius 1.79 times that of Earth. The planet orbits Kepler-296 once every 63.3 days.

text: Kepler296f is a

text: super-Earth

text: with a radius 1.79 times that of

text: Earth

text: . The planet orbits Kepler-296 once every 63.3 days.

text: Some asteroids that cross the orbits of planets may occasionally get close enough to a planet or asteroid so that an observer from that asteroid can make out the disc of the nearby object without the aid of binoculars or a telescope. For example, in September 2004, 4179 Toutatis came about four times the distance from the Earth that the Moon does. At the closest point in its encounter, the Earth would have appeared about the same size as the Moon appears from Earth. The Moon would also be easily visible as a small shape in Toutatis's sky at that time.

text: Some asteroids that cross the orbits of planets may occasionally get close enough to a planet or asteroid so that an observer from that asteroid can make out the disc of the nearby object without the aid of binoculars or a telescope. For example, in September 2004,

text: 4179 Toutatis

text: came about four times the distance from the Earth that the Moon does. At the closest point in its encounter, the Earth would have appeared about the same size as the Moon appears from Earth. The Moon would also be easily visible as a small shape in Toutatis's sky at that time.

text: A planet that is too small cannot hold much of an atmosphere. Hence the surface temperature becomes more variable and the average temperature drops. Substantial and long-lasting oceans become impossible. A small planet will also tend to have a rough surface, with large mountains and deep canyons. The core will cool faster, and plate tectonics will either not last as long as they would on a larger planet or may not occur at all. A planet that is too large will retain too much of its atmosphere and will be like Venus. Venus is similar in size and mass to Earth, but has a surface atmosphere pressure that is 92 times that of Earth's. Venus mean surface temperature is 735 K (462 °C; 863 °F) making Venus the hottest planet in the Solar System. Earth had a similar early atmosphere to Venus, but lost it in the giant impact event.

text: A planet that is too small cannot hold much of an atmosphere. Hence the surface temperature becomes more variable and the average temperature drops. Substantial and long-lasting oceans become impossible. A small planet will also tend to have a rough surface, with large mountains and deep canyons. The core will cool faster, and

text: plate tectonics

text: will either not last as long as they would on a larger planet or may not occur at all. A planet that is too large will retain too much of its atmosphere and will be like

text: Venus

text: . Venus is similar in size and mass to Earth, but has a surface atmosphere pressure that is 92 times that of Earth's. Venus mean surface temperature is 735 K (462 °C; 863 °F) making Venus the hottest planet in the Solar System. Earth had a similar early atmosphere to Venus, but lost it in the

text: giant impact event

text: Strange Days on Planet Earth is a four-part (1 hour each) television program on PBS concerning human impact on the environment. It is narrated by Edward Norton. The show was produced by Sea Studios Foundation.  Strange Days on Planet Earth grew into an ongoing partnership with the National Geographic Society to bring focus on our personal connection to the planet’s life systems.

text: Strange Days on Planet Earth is a four-part (1 hour each) television program on

text: PBS

text: concerning

text: human impact on the environment

text: . It is narrated by

text: Edward Norton

text: . The show was produced by

text: Sea Studios Foundation

text: .  Strange Days on Planet Earth grew into an ongoing partnership with the

text: National Geographic Society

text: to bring focus on our personal connection to the planet’s life systems.

text: Earth meanwhile increasingly falls under the control of transnational corporations (transnats) that come to dominate its governments, particularly smaller nations adopted as "flags of convenience" for extending their influence into Martian affairs. As UNOMA's power erodes, the Mars treaty is renegotiated in a move led by Frank Chalmers; the outcome is impressive but proves short-lived as the transnats find ways around it through loop-holes. Things get worse as the nations of Earth start to clash over limited resources, expanding debt, and population growth as well as restrictions on access to a new longevity treatment developed by Martian science—one that holds the promise of lifespans into the hundreds of years. In 2061, with Boone dead and exploding immigration threatening the fabric of Martian society, Bogdanov launches a revolution against what many now view as occupying transnat troops operating only loosely under an UNOMA rubber-stamp approval. Initially successful, the revolution proves infeasible on the basis of both a greater-than-expected willingness of the Earth troops to use violence and the extreme vulnerability of life on a planet without a habitable atmosphere. A series of exchanges sees the cutting of the space elevator, bombardment of several Martian cities (including the city where Bogdanov is himself organizing the rebellion; he is killed), the destruction of Phobos and its military complex, and the unleashing of a great flood of torrential groundwater freed by nuclear detonations.

text: Earth

text: meanwhile increasingly falls under the control of

text: transnational corporation

text: The superseded belief that the Earth is flat, and denial of all of the overwhelming evidence that supports an approximately round globe that rotates around its axis and revolves around the Sun, persists into the 21st century. Modern proponents of flat-Earth cosmology (or flat-earthers) refuse to accept any kind of contrary evidence, dismissing all spaceflights and images from space as hoaxes and accusing all organizations and even private citizens of conspiring to "hide the truth". They claim that no actual satellites are orbiting the Earth, that the International Space Station is fake, and that these are lies from all governments involved in this grand cover-up. Adherents of the modern flat-Earth model propose that the Sun is only 3,000 miles above the Earth and that the Moon and the Sun orbit above, but not around, a flat Earth. Modern flat-earthers believe that Antarctica is not a continent but a massive ice flow, with a wall 150 feet or higher, which circles the perimeter of the Earth, keeps everything from falling off the edge, and contains all the ocean water. Flat-earthers also assert that no one is allowed to explore Antarctica, despite contrary evidence shown. According to them, all photos and videos of ships sinking under the horizon and of the bottoms of city skylines and clouds below the horizon, revealing the curvature of the Earth, have been manipulated, CGI, or somehow faked. Therefore, regardless of any scientific or empirical evidence provided, flat-earthers will stubbornly conclude it is fabricated or altered in some way.

text: The

text: superseded belief

text: that the

text: Earth

text: is

text: flat

text: , and denial of all of the overwhelming evidence that supports an approximately round globe that rotates around its axis and revolves around the

text: Sun

text: , persists into the

text: 21st century

text: . Modern proponents of flat-Earth

text: cosmology

text: (or

text: flat-earther

text: s) refuse to accept any kind of contrary evidence, dismissing all

text: spaceflight

text: s and images from space as

text: hoax

text: es and accusing all organizations and even private citizens of

text: conspiring

text: to "hide the truth". They claim that no actual

text: satellite

text: s are orbiting the Earth, that the

text: International Space Station

text: is fake, and that these are lies from all governments involved in this grand

text: cover-up

text: . Adherents of the modern flat-Earth model propose that the Sun is only 3,000 miles above the Earth and that the

text: Moon

text: and the Sun orbit above, but not around, a flat Earth. Modern flat-earthers believe that

text: Antarctica

text: is not a continent but a massive

text: ice flow

text: , with a wall 150 feet or higher, which circles the perimeter of the Earth, keeps everything from falling off the edge, and contains all the ocean water. Flat-earthers also assert that no one is allowed to explore Antarctica, despite contrary evidence shown. According to them, all photos and videos of ships sinking under the horizon and of the bottoms of city

text: skyline

text: s and clouds below the horizon, revealing the

text: curvature of the Earth

text: , have been

text: manipulated

text: CGI

text: , or somehow faked. Therefore, regardless of any scientific or

text: empirical evidence

text: provided, flat-earthers will stubbornly conclude it is fabricated or altered in some way.

text: Venus has been the subject of a number of terraforming proposals. The proposals seek to remove or convert the dense carbon dioxide atmosphere, reduce Venus's  surface temperature, and establish a day/night light cycle closer to that of Earth. On the other hand, research has demonstrated that the planet's 243-day rotation period is actually an advantage in preserving Earth-like conditions on Venus if the planet is successfully terraformed.

text: Venus has been the subject of a number of

text: terraforming

text: proposals. The proposals seek to remove or convert the dense carbon dioxide atmosphere, reduce Venus's  surface temperature, and establish a day/night light cycle closer to that of Earth. On the other hand, research has demonstrated that the planet's 243-day rotation period is actually an advantage in preserving Earth-like conditions on Venus if the planet is successfully terraformed.

text: From the point of view of most of the population of the Earth, a new planet appears out of nothing close to the Moon, shortly after a total lunar eclipse.  Over a period of few days the planet appears to consume the Moon.  On Earth, the new planet's gravity causes death and destruction as it raises huge ocean tides and causes earthquakes and volcanic eruptions.  Flying saucers appear in the skies, apparently trying to mitigate some of the disastrous effects. Then after a spectacular battle in space between the new planet and another, the skies are empty again.  Earth is left without a Moon.

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: The planet has many animals, some from the Ice Age megafauna of the Earth and others from totally alien worlds. In addition - as the soldiers of the 35th Maine rapidly discover - humans are not the dominant form of life on this planet, which is called Valennia. Rather, humans are the enemies and sometime cattle of nine-foot-tall alien nomads. Valennia, additionally, is smaller than the Earth. There are fewer and smaller freshwater oceans, gravity is lighter, and most of the land masses are contiguous.

text: The planet has many animals, some from the Ice Age

text: megafauna

text: of the Earth and others from totally alien worlds. In addition - as the soldiers of the 35th Maine rapidly discover - humans are not the dominant form of life on this planet, which is called Valennia. Rather, humans are the enemies and sometime cattle of nine-foot-tall alien nomads. Valennia, additionally, is smaller than the Earth. There are fewer and smaller freshwater oceans, gravity is lighter, and most of the land masses are contiguous.

text: The type of gravity model used for the Earth depends upon the degree of fidelity required for a given problem.  For many problems such as aircraft simulation, it may be sufficient to consider gravity to be a constant, defined as:

text: The spacecraft will use several gravity assist flybys of other planets to enable it to reach Saturn. The baseline design envisaged a September 2020 launch, followed by four gravity assists (Earth–Venus–Earth–Earth), and arrival at Saturn 9 years later in October 2029. This is one of several available Earth-to-Saturn transfer options from the year 2018 through 2022. Current NASA plans do not give the TSSM a priority, however, and it is unlikely any of the proposed launch dates can be met.

text: The spacecraft will use several

text: gravity assist

text: flyby

text: s of other planets to enable it to reach Saturn. The baseline design envisaged a September 2020 launch, followed by four gravity assists (

text: Earth

text: Venus

text: –Earth–Earth), and arrival at Saturn 9 years later in October 2029. This is one of several available Earth-to-Saturn transfer options from the year 2018 through 2022. Current NASA plans do not give the TSSM a priority, however, and it is unlikely any of the proposed launch dates can be met.

text: Effective gravity on the Earth's surface varies by around 0.7%, from 9.7639 m/s on the Nevado Huascarán mountain in Peru to 9.8337 m/s at the surface of the Arctic Ocean. In large cities, it ranges from 9.766 in Kuala Lumpur, Mexico City, and Singapore to 9.825 in Oslo and Helsinki.

text: Effective gravity on the Earth's surface varies by around 0.7%, from 9.7639 m/s on the

text: Nevado Huascarán

text: mountain in Peru to 9.8337 m/s at the surface of the

text: Arctic Ocean

entity_section: Comparative gravities in various cities around the world

text: In large cities, it ranges

text: from 9.766 in

text: Kuala Lumpur

text: Mexico City

text: , and

text: Singapore

text: to 9.825 in

text: Oslo

text: and

text: Helsinki

text: Dynamo theory is a proposed mechanism to explain how celestial bodies like the Earth generate magnetic fields. The presence or lack of a magnetic field can help constrain the dynamics of a planetary core. Refer to Earth's magnetic field for further details. A dynamo requires a source of thermal and/or compositional buoyancy as a driving force. Thermal buoyancy from a cooling core alone cannot drive the necessary convection as indicated by modelling, thus compositional buoyancy (from changes of phase) is required. On Earth the buoyancy is derived from crystallization of the inner core (which can occur as a result of temperature). Examples of compositional buoyancy include precipitation of iron alloys onto the inner core and liquid immiscibility both, which could influence convection both positively and negatively depending on ambient temperatures and pressures associated with the host-body. Other celestial bodies that exhibit magnetic fields are Mercury, Jupiter, Ganymede, and Saturn.

text: Dynamo theory

text: is a proposed mechanism to explain how celestial bodies like the Earth generate magnetic fields. The presence or lack of a magnetic field can help constrain the dynamics of a planetary core. Refer to

text: Earth's magnetic field

text: for further details. A dynamo requires a source of thermal and/or compositional buoyancy as a driving force. Thermal buoyancy from a cooling core alone cannot drive the necessary convection as indicated by modelling, thus compositional buoyancy (from

text: changes of phase

text: ) is required. On Earth the buoyancy is derived from

text: crystallization

text: of the inner core (which can occur as a result of temperature). Examples of compositional buoyancy include precipitation of iron alloys onto the inner core and liquid immiscibility both, which could influence convection both positively and negatively depending on ambient temperatures and pressures associated with the host-body. Other celestial bodies that exhibit magnetic fields are Mercury, Jupiter, Ganymede, and Saturn.

text: Venus is the second planet from the Sun, orbiting it every 224.7 Earth days. It has the longest rotation period (243 days) of any planet in the Solar System and rotates in the opposite direction to most other planets. It has no natural satellite. It is named after the Roman goddess of love and beauty. It is the second-brightest natural object in the night sky after the Moon, reaching an apparent magnitude of −4.6, bright enough to cast shadows. Because Venus orbits within Earth's orbit it is an inferior planet and never appears to venture far from the Sun; its maximum angular distance from the Sun (elongation) is 47.8°.

text: Venus is the second

text: planet

text: from the

text: Sun

text: , orbiting it every 224.7

text: Earth

text: days. It has the longest

text: rotation period

text: (243 days) of any planet in the

text: Solar System

text: and

text: rotates

text: in the opposite direction to most other planets. It has no

text: natural satellite

text: . It is named after the

text: Roman goddess of love and beauty

text: . It is the second-brightest natural object in the night sky after the

text: Moon

text: , reaching an

text: apparent magnitude

text: of −4.6, bright enough to cast shadows. Because Venus orbits within Earth's orbit it is an

text: inferior planet

text: and never appears to venture far from the Sun; its maximum angular distance from the Sun (

text: elongation

text: ) is 47.8°.

text: An approximate value for gravity at a distance  from the centre of the Earth can be obtained by assuming that the Earth's density is spherically symmetric. The gravity depends only on the mass inside the sphere of radius . All the contributions from outside cancel out as a consequence of the inverse-square law of gravitation. Another consequence is that the gravity is the same as if all the mass were concentrated at the centre. Thus, the gravitational acceleration at this radius is

text: An approximate value for gravity at a distance  from the centre of the Earth can be obtained by assuming that the Earth's density is spherically symmetric. The gravity depends only on the mass inside the sphere of radius . All the contributions from outside cancel out as a consequence of the

text: inverse-square law

text: of gravitation. Another consequence is that the gravity is the same as if all the mass were concentrated at the centre. Thus, the gravitational acceleration at this radius is

text: Philolaus's ideas were all eventually superseded by the modern belief that a spherical Earth rotating on its own axis was one of several spherical planets following the laws of gravity and revolving around a much larger Sun.  The idea of a Counter-Earth waned after the heliocentric model of the solar system became widely accepted from the 16th century.  In the contemporary world "Counter-Earth" usually refers to a hypothetical planet with an orbit as Burch described, on the other side of the "Central fire"—i.e. the Sun. It cannot be seen from Earth, not because Earth faces away from the center,

text: Philolaus's ideas were all eventually

text: superseded

text: by the modern belief that a spherical Earth rotating on its own axis was one of several spherical planets following the laws of gravity and revolving around a much larger Sun.  The idea of a Counter-Earth waned after the heliocentric model of the solar system became widely accepted from the 16th century.  In the contemporary world "Counter-Earth" usually refers to a hypothetical planet with an orbit as Burch described, on the other side of the "Central fire"—i.e. the Sun. It cannot be seen from Earth, not because Earth faces away from the center,

text: In a 2014 letter to the journal Nature, astronomers Chad Trujillo and Scott S. Sheppard inferred the possible existence of a massive trans-Neptunian planet from similarities in the orbits of the distant trans-Neptunian objects Sedna and . On 20 January 2016, researchers Konstantin Batygin and Michael E. Brown at Caltech explained how a massive outer planet would be the likeliest explanation for the similarities in orbits of six distant objects, and they proposed specific orbital parameters. The predicted planet would be a super-Earth, with an estimated mass of 10 Earths (approximately 5,000 times the mass of Pluto), a diameter two to four times that of Earth, and a highly elliptical orbit with an orbital period of approximately 15,000 years.

text: In a 2014 letter to the journal

text: Nature

text: , astronomers

text: Chad Trujillo

text: and

text: Scott S. Sheppard

text: inferred the possible existence of a massive trans-Neptunian planet from similarities in the orbits of the distant trans-Neptunian objects

text: Sedna

text: and . On 20 January 2016, researchers

text: Konstantin Batygin

text: and

text: Michael E. Brown

text: at

text: Caltech

text: explained how a massive outer planet would be the likeliest explanation for the similarities in orbits of six distant objects, and they proposed specific orbital parameters. The predicted planet would be a

text: super-Earth

text: , with an estimated mass of 10 Earths (approximately 5,000 times the mass of

text: Pluto

text: ), a diameter two to four times that of Earth, and a highly

text: elliptical orbit

text: with an orbital period of approximately 15,000 years.

text: This is a version of the real-world planet Earth where humans have made contact with Transformers. Earth is the third planet from the Sun in the Solar System in the Milky Way galaxy. It is a world populated by a wide variety of native organic lifeforms, most notably, humans. Versions of this planet are known to exist in many dimensions within the multiverse, and it frequently becomes involved in the conflicts of the Transformers. Perhaps too frequently. Whenever something (or someone) leaves, escapes, or is otherwise ejected from Cybertron, there's a disproportionate chance it will eventually wind up on Earth. In some universes, Earth becomes the post-apocalyptic planet Gaea, while in others, Earth is the planet that formed around Unicron.

text: This is a version of the real-world planet

text: Earth

text: where humans have made contact with Transformers. Earth is the third planet from the

text: Sun

text: in the

text: Solar System

text: in the

text: Milky Way

text: galaxy. It is a world populated by a wide variety of native organic lifeforms, most notably,

text: human

text: s. Versions of this planet are known to exist in many dimensions within the multiverse, and it frequently becomes involved in the conflicts of the Transformers. Perhaps too frequently. Whenever something (or someone) leaves, escapes, or is otherwise ejected from

text: Cybertron

text: , there's a disproportionate chance it will eventually wind up on Earth. In some universes, Earth becomes the post-apocalyptic planet

text: Gaea

text: , while in others, Earth is the planet that formed around

text: Unicron

text: There has been at least one attempt within Marvel canon to change the designation of Earth-616. In the final story arc of X-Man (issues #71–74), writer Steven Grant began to refer to the planet as "Earth-611" due to the destruction of several other Earths (which were all apparently "higher on the list" of the multiverse than the Marvel Earth) by a godlike entity. This change, an allusion to the events of DC's Crisis on Infinite Earths, was not adopted by other writers.

text: There has been at least one attempt within Marvel canon to change the designation of Earth-616. In the final story arc of

text: X-Man

text: (issues #71–74), writer

text: Steven Grant

text: began to refer to the planet as "Earth-611" due to the destruction of several other Earths (which were all apparently "higher on the list" of the multiverse than the Marvel Earth) by a godlike entity. This change, an allusion to the events of DC's

text: Crisis on Infinite Earths

text: , was not adopted by other writers.

text: Neptune's mass of 1.0243 kg is intermediate between Earth and the larger gas giants: it is 17 times that of Earth but just 1/19th that of Jupiter. Its gravity at 1 bar is 11.15 m/s, 1.14 times the surface gravity of Earth, and surpassed only by Jupiter. Neptune's equatorial radius of 24,764 km is nearly four times that of Earth. Neptune, like Uranus, is an ice giant, a subclass of giant planet, due to their smaller size and higher concentrations of volatiles relative to Jupiter and Saturn. In the search for extrasolar planets, Neptune has been used as a metonym: discovered bodies of similar mass are often referred to as "Neptunes", just as scientists refer to various extrasolar bodies as "Jupiters".

text: Neptune's mass of 1.0243 kg is intermediate between Earth and the larger

text: gas giant

text: s: it is 17 times that of Earth but just 1/19th that of

text: Jupiter

text: . Its

text: gravity

text: at 1 bar is 11.15 m/s, 1.14 times the

text: surface gravity

text: of Earth, and surpassed only by Jupiter. Neptune's

text: equator

text: ial radius of 24,764 km is nearly four times that of Earth. Neptune, like

text: Uranus

text: , is an

text: ice giant

text: , a subclass of

text: giant planet

text: , due to their smaller size and higher concentrations of

text: volatiles

text: relative to Jupiter and

text: Saturn

text: . In the search for

text: extrasolar planet

text: s, Neptune has been used as a

text: metonym

text: : discovered bodies of similar mass are often referred to as "Neptunes", just as scientists refer to various extrasolar bodies as "Jupiters".

text: Copernicus obliquely refers to Earth as a planet in De Revolutionibus when he says, "Having thus assumed the motions which I ascribe to the Earth later on in the volume, by long and intense study I finally found that if the motions of the other planets are correlated with the orbiting of the earth..." Galileo also asserts that Earth is a planet in the Dialogue Concerning the Two Chief World Systems: "[T]he Earth, no less than the moon or any other planet, is to be numbered among the natural bodies that move circularly."

text: Copernicus obliquely refers to Earth as a planet in De Revolutionibus when he says, "Having thus assumed the motions which I ascribe to the Earth later on in the volume, by long and intense study I finally found that if the motions of the other planets are correlated with the orbiting of the earth..."

text: Galileo

text: also asserts that Earth is a planet in the

entity_name: Dialogue Concerning the Two Chief World Systems

text: Dialogue Concerning the Two Chief World Systems

text: : "[T]he Earth, no less than the moon or any other planet, is to be numbered among the natural bodies that move circularly."

text: When an expedition was sent out to Vinea, it found that the local population had regressed to a relatively primitive level, and was currently governed by a conclave of digital personalities taken from great leaders from the Vinean past. The planet had entered a wider, tidally-locked orbit around its suns, with one side permanently scorched and the other forever frozen. The effects on Vinea's climate were more or less compensated for by an artificial temperature regulation system, including large orbital mirrors acting as artificial suns for the 'night' side. A project for relocating the Earth-Vinean population was put into place, and the rebuilding of the planet's civilization began.

text: When an expedition was sent out to Vinea, it found that the local population had regressed to a relatively primitive level, and was currently governed by a conclave of digital personalities taken from great leaders from the Vinean past. The planet had entered a wider,

text: tidally-locked

text: orbit around its suns, with one side permanently scorched and the other forever frozen. The effects on Vinea's

text: climate

text: were more or less compensated for by an artificial temperature regulation system, including large orbital mirrors acting as artificial suns for the 'night' side. A project for relocating the Earth-Vinean population was put into place, and the rebuilding of the planet's civilization began.

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: In July 2012, NASA announced that astronomers at the University of Central Florida, using the Spitzer Space Telescope, strongly believe they have observed a second planet. This strong candidate planet was given the preliminary designation UCF-1.01, after the University of Central Florida. It was measured to have a radius of around two thirds that of Earth and, assuming an Earth-like density of 5.5 g/cm, was estimated to have a mass of 0.3 times that of Earth and a surface gravity of around two thirds that of Earth. It orbits at 0.0185 AU from the star, every 1.3659 days. The astronomers also believe they have found some evidence for an additional planet candidate, UCF-1.02, which is of a similar size, though with only one detected transit its orbital period is unknown. If these planets are confirmed in the future, they may be given the designations "Gliese 436 c" and "Gliese 436 d".

text: In July 2012, NASA announced that astronomers at the

text: University of Central Florida

text: , using the

text: Spitzer Space Telescope

text: , strongly believe they have observed a second planet. This strong candidate planet was given the preliminary designation UCF-1.01, after the University of Central Florida. It was measured to have a radius of around two thirds that of Earth and, assuming an Earth-like density of 5.5 g/cm, was estimated to have a mass of 0.3 times that of Earth and a surface gravity of around two thirds that of Earth. It orbits at 0.0185 AU from the star, every 1.3659 days. The astronomers also believe they have found some evidence for an additional planet candidate, UCF-1.02, which is of a similar size, though with only one detected transit its orbital period is unknown. If these planets are confirmed in the future, they may be given the designations "Gliese 436 c" and "Gliese 436 d".

text: Jupiter mass ( or ) is the unit of mass equal to the total mass of the planet Jupiter (, 317.83 Earth mass; one Earth mass equals 0.00315 Jupiter masses). Jupiter mass is used to describe masses of the gas giants, such as the outer planets and extrasolar planets. It is also used in describing brown dwarfs.

text: Jupiter mass ( or ) is the unit of

text: mass

text: equal to the total mass of the planet

text: Jupiter

text: (, 317.83

text: Earth mass

text: ; one Earth mass equals 0.00315 Jupiter masses). Jupiter mass is used to describe masses of the

text: gas giant

text: s, such as the

text: outer planet

text: s and

text: extrasolar planet

text: s. It is also used in describing

text: brown dwarf

text: s.

text: The presence of a magnetic field at Uranus was not known until Voyager's arrival. The intensity of the field is roughly comparable to that of Earth's, though it varies much more from point to point because of its large offset from the center of Uranus. The peculiar orientation of the magnetic field suggests that the field is generated at an intermediate depth in the interior where the pressure is high enough for water to become electrically conductive. Voyager 2 found that one of the most striking influences of the sideways position of the planet is its effect on the tail of the magnetic field, which is itself tilted 60 degrees from the planet's axis of rotation. The magnetotail was shown to be twisted by the planet's rotation into a long corkscrew shape behind the planet.

text: The presence of a magnetic field at Uranus was not known until Voyager's arrival. The intensity of the field is roughly comparable to that of Earth's, though it varies much more from point to point because of its large offset from the center of Uranus. The peculiar orientation of the magnetic field suggests that the field is generated at an intermediate depth in the interior where the pressure is high enough for water to become electrically conductive. Voyager 2 found that one of the most striking influences of the sideways position of the planet is its effect on the tail of the

text: magnetic field

text: , which is itself tilted 60 degrees from the planet's

text: axis of rotation

text: . The

text: magnetotail

text: was shown to be twisted by the planet's rotation into a long corkscrew shape behind the planet.

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: The bands seen in the atmosphere of Jupiter are due to counter-circulating streams of material called zones and belts, encircling the planet parallel to its equator. The zones are the lighter bands, and are at higher altitudes in the atmosphere. They have an internal updraft and are high-pressure regions. The belts are the darker bands, are lower in the atmosphere, and have an internal downdraft. They are low-pressure regions. These structures are somewhat analogous to the high and low-pressure cells in Earth's atmosphere, but they have a very different structure—latitudinal bands that circle the entire planet, as opposed to small confined cells of pressure. This appears to be a result of the rapid rotation and underlying symmetry of the planet. There are no oceans or landmasses to cause local heating and the rotation speed is much higher than that of Earth.

text: The bands seen in the

text: atmosphere of Jupiter

text: are due to counter-circulating streams of material called zones and belts, encircling the planet parallel to its equator. The zones are the lighter bands, and are at higher altitudes in the atmosphere. They have an internal updraft and are high-pressure regions. The belts are the darker bands, are lower in the atmosphere, and have an internal downdraft. They are low-pressure regions. These structures are somewhat analogous to the high and low-pressure cells in Earth's atmosphere, but they have a very different structure—latitudinal bands that circle the entire planet, as opposed to small confined cells of pressure. This appears to be a result of the rapid rotation and underlying symmetry of the planet. There are no oceans or landmasses to cause local heating and the rotation speed is much higher than that of Earth.

text: A famous example of a revolution in scientific thought is the Copernican Revolution. In Ptolemy's school of thought, cycles and epicycles (with some additional concepts) were used for modeling the movements of the planets in a cosmos that had a stationary Earth at its center. As accuracy of celestial observations increased, complexity of the Ptolemaic cyclical and epicyclical mechanisms had to increase to maintain the calculated planetary positions close to the observed positions. Copernicus proposed a cosmology in which the Sun was at the center and the Earth was one of the planets revolving around it. For modeling the planetary motions, Copernicus used the tools he was familiar with, namely the cycles and epicycles of the Ptolemaic toolbox. Yet Copernicus' model needed more cycles and epicycles than existed in the then-current Ptolemaic model, and due to a lack of accuracy in calculations, his model did not appear to provide more accurate predictions than the Ptolemy model. Copernicus' contemporaries rejected his cosmology, and Kuhn asserts that they were quite right to do so: Copernicus' cosmology lacked credibility.

text: A famous example of a revolution in scientific thought is the

text: Copernican Revolution

text: . In

text: Ptolemy

text: 's school of thought,

text: cycles and epicycles

text: (with some additional concepts) were used for modeling the movements of the

text: planet

text: s in a cosmos that had a stationary Earth at its center. As

text: accuracy

text: of

text: celestial observation

text: s increased, complexity of the Ptolemaic cyclical and epicyclical mechanisms had to increase to maintain the calculated planetary positions close to the observed positions.

text: Copernicus

text: proposed a cosmology in which the Sun was at the center and the Earth was one of the planets revolving around it. For modeling the planetary motions, Copernicus used the tools he was familiar with, namely the cycles and epicycles of the Ptolemaic toolbox. Yet Copernicus' model needed more cycles and epicycles than existed in the then-current Ptolemaic model, and due to a lack of accuracy in calculations, his model did not appear to provide more accurate predictions than the Ptolemy model. Copernicus' contemporaries rejected his

text: cosmology

text: , and Kuhn asserts that they were quite right to do so: Copernicus' cosmology lacked credibility.

text: Gliese 581 c  or Gl 581 c is a planet orbiting the red dwarf Gliese 581. It is the second planet discovered in the system and the third in order from the star. With a mass at least 5.5 times that of the Earth, it is classified as a super-Earth (a category of planets from 5 to 10 Earth masses).

text: Gliese 581 c  or Gl 581 c is a planet orbiting the

text: red dwarf

text: Gliese 581

text: . It is the second planet discovered in the system and the third in order from the star. With a mass at least 5.5 times that of the

text: Earth

text: , it is classified as a

text: super-Earth

text: (a category of planets from 5 to 10 Earth masses).

text: The Earth's magnetic field has two main components.  The stronger component known as the Earth’s poles, reverses direction at irregular intervals.  The weaker variations are the Earth’s magnetic map.  Within these weaker areas the local directions and intensities change gradually (secular variation).   A compass does not point to the true North Pole but to direction that is a function of the North Magnetic Pole and the local secular variation to yield a magnetic declination.The magnetic declination at any given time can be frozen into a clay formation that contains magnetite and is heated above the Curie point.  In general, many cultures used long-term fire hearths made of clay bricks, or a space lined with clay, that were baked into place by use.  These artifacts of occupation can yield the magnetic declination from the last time they were fired or used.Archaeomagnetic dating was described in the 1992 publication “Paleomagnetism: Magnetic Domains to Geologic Terranes.” By Robert F. Butler.

text: The

text: Earth's magnetic field

text: has two main components.  The stronger component known as the Earth’s poles, reverses direction at irregular intervals.  The weaker variations are the Earth’s magnetic map.  Within these weaker areas the local directions and intensities change gradually (secular variation).   A compass does not point to the true

text: North Pole

text: but to direction that is a function of the

text: North Magnetic Pole

text: and the local secular variation to yield a

text: magnetic declination

text: .The magnetic declination at any given time can be frozen into a clay formation that contains magnetite and is heated above the

text: Curie point

text: .  In general, many cultures used long-term fire hearths made of clay bricks, or a space lined with clay, that were baked into place by use.  These artifacts of occupation can yield the magnetic declination from the last time they were fired or used.Archaeomagnetic dating was described in the 1992 publication “Paleomagnetism: Magnetic Domains to Geologic Terranes.” By Robert F. Butler.

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: The habitable zone of 40 Eridani A, where a planet could exist with liquid water, is near 0.68 (calculated from habitable zone) AU from A. At this distance a planet would complete a revolution in 223 Earth days (according to the third Kepler's law) and 40 Eridani A would appear nearly 20% wider than the Sun does on Earth. An observer on a planet in the 40 Eridani A system would see the B/C pair as unusually bright (magnitudes -8 and -6) white and reddish-orange stars in the night sky. This is not bright enough to diminish the darkness at night, though they would be visible in daylight (assuming an Earth-normal atmosphere). (By comparison, Earth's full moon is magnitude −12.6, and Venus at its brightest is −4.7.)

text: The

text: habitable zone

text: of 40 Eridani A, where a planet could exist with liquid water, is near 0.68 (calculated from

text: habitable zone

text: AU

text: from A. At this distance a planet would complete a revolution in 223 Earth days (according to the third

text: Kepler's law

text: ) and 40 Eridani A would appear nearly 20% wider than the Sun does on Earth. An observer on a planet in the 40 Eridani A system would see the B/C pair as unusually bright (

text: magnitudes

text: -8 and -6) white and reddish-orange stars in the night sky. This is not bright enough to diminish the darkness at night, though they would be visible in daylight (assuming an Earth-normal atmosphere). (By comparison, Earth's full moon is magnitude −12.6, and

text: Venus

text: at its brightest is −4.7.)

text: Shortly after the events of Alpha, the Earth Federation has covered up many of the events in the climatic battle with the antagonist Aerogaters, but the gravity shock wave from the detonation of the Excelion (from Gunbuster) in the Battle of the Solar System's Absolute Defense is rapidly approaching the Earth, and threatens to wipe out the space colonies and the planet. The Earth's only hope is the Aegis System, which could shield the Earth Sphere from the shock wave.

text: Shortly after the events of Alpha, the

text: Earth Federation

text: has covered up many of the events in the climatic battle with the antagonist Aerogaters, but the gravity shock wave from the detonation of the Excelion (from

text: Gunbuster

text: ) in the Battle of the Solar System's Absolute Defense is rapidly approaching the

text: Earth

text: , and threatens to wipe out the space colonies and the planet. The Earth's only hope is the Aegis System, which could shield the Earth Sphere from the shock wave.

text: The  appeared in Battle in Outer Space, The Natals are a diminutive alien race who want the Earth as a colony for their planet and enslave all of humanity. The aliens display a wide array of technologies and ingenuity in their attempt to overthrow the Earth by various means, including mind control, sabotage, anti-gravity rays, space-torpedoes, saucer attacks, and finally their huge Mothership.

text: The  appeared in

text: Battle in Outer Space

text: , The Natals are a diminutive alien race who want the Earth as a colony for their planet and enslave all of humanity. The aliens display a wide array of technologies and ingenuity in their attempt to overthrow the Earth by various means, including mind control, sabotage, anti-gravity rays, space-torpedoes, saucer attacks, and finally their huge Mothership.

text: The best-studied example of a bow shock is that occurring where the Sun's wind encounters Earth's magnetopause, although bow shocks occur around all magnetized planets, such as Jupiter or Saturn. Earth's bow shock is about  thick and located about  from the planet.

text: The best-studied example of a bow shock is that occurring where the

text: Sun's wind

text: encounters

text: Earth

text: 's magnetopause, although bow shocks occur around all magnetized planets, such as

text: Jupiter

text: or

text: Saturn

text: . Earth's bow shock is about  thick and located about  from the planet.

text: Kaltenegger is known for her studies of the atmospheres of extrasolar planets, especially Earth-like onesand is a pioneer in the study of the Earth as an astronomical object evolving in time. She studied the change in the Earth's spectral fingerprint as a comparison with the evolutionary stages of Earthlike exoplanets to generate an "Alien ID Chart" - pointing out that as biology and geology change the Earth through the ages, its appearance to a telescope observing it from distant stars would also change. She also investigated the ability of future telescopes like the James Webb Space Telescope to detect evidence of life using spectral biomarkers (biosignatures) and generated the first spectra of Earth seen as a transiting exoplanet in 2009 concluding that it will be a hard problem for JWST and bigger future telescopes are needed to find signatures of life on many planets. In 2009 she discussed how one can determine habitability for moons around giant planets  coinciding with the suggestion of such a moon in the movie Avatar (2009 film).Super-volcanoes on exoplanets: In 2010 she explored whether we could observe geological activity, that is very important for habitability, on exoplanets, finding that about 10 times Pinatubo eruptions could be detected around the closest exoplanets, showing us if other planets are similar to our own Earth. 2011 she led a team to model the spectral fingerprint of Gliese 581 d, one of the first small Radial Velocity planets to be discovered in the habitable zone of its star. In 2013 she was part of the team announcing the discovery of the first two potentially habitable Kepler planets, with radii smaller than 2 Earth radii in the habitable zone of their stars, Kepler 62e and Kepler 62f  and investigated whether or not these planets could still be habitable and how their spectra would look like if they were water worlds.

text: Kaltenegger is known for her studies of the atmospheres of extrasolar planets, especially Earth-like onesand is a pioneer in the study of the Earth as an astronomical object evolving in time. She studied the change in the Earth's spectral fingerprint as a comparison with the evolutionary stages of Earthlike exoplanets to generate an "Alien ID Chart" - pointing out that as biology and geology change the Earth through the ages, its appearance to a telescope observing it from distant stars would also change. She also investigated the ability of future telescopes like the

text: James Webb Space Telescope

text: to detect evidence of life using spectral biomarkers (

text: biosignatures

text: ) and generated the first

text: spectra of Earth seen as a transiting exoplanet

text: in 2009 concluding that it will be a hard problem for JWST and bigger future telescopes are needed to find signatures of life on many planets. In 2009 she discussed how one can determine

text: habitability for moons around giant planets

text: coinciding with the suggestion of such a moon in the movie

text: Avatar (2009 film)

text: Super-volcanoes on exoplanets

text: : In 2010 she explored whether we could observe geological activity, that is very important for habitability, on exoplanets, finding that about 10 times Pinatubo eruptions could be detected around the closest exoplanets, showing us if other planets are similar to our own Earth. 2011 she led a team to model the spectral fingerprint of

text: Gliese 581 d

text: , one of the first small Radial Velocity planets to be discovered in the

text: habitable zone

text: of its star. In 2013 she was part of the team announcing the discovery of the first two potentially habitable Kepler planets, with radii smaller than 2 Earth radii in the habitable zone of their stars,

text: Kepler 62e

text: and

text: Kepler 62f

text: and investigated whether or not these planets could still be habitable and how their spectra would look like if they were water worlds.

text: On June 21, 2012, the discovery of two planets orbiting the star was announced. The planets, a super-Earth and a "mini-Neptune" are unusual in that they have very close orbits; their semi-major axes differ by only 0.013 AU. The outer planet orbits only 11% further than the inner one. Coupled with masses significantly higher than Earth, their gravitational influence to each other is significant, meaning that their interaction causes extreme transit timing variations for both. Kepler-36b and c have estimated densities of 6.8 and 0.86 g/cm, respectively. The two planets are close to a 7:6 orbital resonance.

text: On June 21, 2012, the discovery of two planets orbiting the star was announced. The planets, a

text: super-Earth

text: and a "

text: mini-Neptune

text: " are unusual in that they have very close orbits; their

text: semi-major axes

text: differ by only 0.013

text: AU

text: . The outer planet orbits only 11% further than the inner one. Coupled with masses significantly higher than Earth, their gravitational influence to each other is significant, meaning that their interaction causes extreme

text: transit timing variation

text: s for both. Kepler-36b and c have estimated densities of 6.8 and 0.86 g/cm, respectively. The two planets are close to a 7:6

text: orbital resonance

text: Because the signal from an Earth-size planet is so close to the noise level (only 80 ppm), the increased noise means each individual transit is only a 2.7 σ event, instead of the intended 4 σ. This, in turn, means more transits must be observed to be sure of a detection. Scientific estimates indicated that a mission lasting 7 to 8 years, as opposed to the originally planned 3.5 years, would be needed to find all transiting Earth-sized planets. On April 4, 2012, the Kepler mission was approved for extension through the fiscal year 2016, but this also depended on all remaining reaction wheels staying healthy, which turned out not to be the case (see Spacecraft history below).

text: Because the signal from an Earth-size planet is so close to the noise level (only 80 ppm), the increased noise means each individual transit is only a 2.7 σ event, instead of the intended 4 σ. This, in turn, means more transits must be observed to be sure of a detection. Scientific estimates indicated that a mission lasting 7 to 8 years, as opposed to the originally planned 3.5 years, would be needed to find all transiting Earth-sized planets. On April 4, 2012, the Kepler mission was approved for extension through the fiscal year 2016, but this also depended on all remaining reaction wheels staying healthy, which turned out not to be the case (see

text: Spacecraft history

text: below).

text: One night in the Evergreen Forest, Schaeffer the sheepdog is playing with his human owners, Tommy and Julie, when their father, Dan the Forest Ranger has a surprise for them. As Schaeffer takes a brief nap, he is awoken by a glowing red plane that lands in front of the cabin. Schaeffer goes to investigate, but the pilot gets a call from his commanding officer to return to his base. Panicking, Schaeffer climbs into the passenger seat of the plane and is flown away from Earth and to a strange jungle planet. Upon his arrival to a giant base filled with weaponry, he's chased by the forces of the Imperial Commander Cyril Sneer, but escapes them. Schaeffer runs into Sophia Tutu, a friend of his from the planet Earth, although Sophia doesn't seem to know Schaeffer. Sophia takes Schaeffer to meet Broo, her pet sheepdog puppy. Meanwhile, Cyril Sneer plans to conquer Earth with the help of a magic star (which Broo wears around his neck). The star has enough power to launch his firepower to raid the planet. He sends out his army to hunt down every animal in the jungle and find the star.

text: One night in the Evergreen Forest, Schaeffer the

text: sheepdog

text: is playing with his human owners, Tommy and Julie, when their father, Dan the Forest Ranger has a surprise for them. As Schaeffer takes a brief nap, he is awoken by a glowing red plane that lands in front of the cabin. Schaeffer goes to investigate, but the pilot gets a call from his commanding officer to return to his base. Panicking, Schaeffer climbs into the passenger seat of the plane and is flown away from

text: Earth

text: and to a strange jungle planet. Upon his arrival to a giant base filled with weaponry, he's chased by the forces of the Imperial Commander Cyril Sneer, but escapes them. Schaeffer runs into Sophia Tutu, a friend of his from the planet Earth, although Sophia doesn't seem to know Schaeffer. Sophia takes Schaeffer to meet Broo, her pet sheepdog puppy. Meanwhile, Cyril Sneer plans to conquer Earth with the help of a magic star (which Broo wears around his neck). The star has enough power to launch his firepower to raid the planet. He sends out his army to hunt down every animal in the jungle and find the star.

text: Pangrelor, the fantasy world depicted in Antiquitas Lost, is envisioned as a habitable mega-planet, or "Super-Earth" orbiting a binary star system. The size of the world is referred to obliquely (ten times larger than earth), and the planet is frequently described as having two suns. Gravitational forces are not explained, though the characters seem to experience gravity and temperatures similar to those of Earth.

text: Pangrelor, the fantasy world depicted in Antiquitas Lost, is envisioned as a habitable mega-planet, or "

text: Super-Earth

text: " orbiting a binary star system. The size of the world is referred to obliquely (ten times larger than earth), and the planet is frequently described as having two suns. Gravitational forces are not explained, though the characters seem to experience gravity and temperatures similar to those of Earth.

text: Gas planets can also have large solid cores: the Saturn-mass planet HD 149026 b has only two-thirds of Saturn's radius, so it may have a rock–ice core of 60 Earth masses or more. Corot-20b has 4.24 times Jupiter's mass but a radius of only 0.84 that of Jupiter—it may have a metal core of 800 Earth masses if the heavy elements are concentrated in the core, or a core of 300 Earth masses if the heavy elements are more distributed throughout the planet.

text: Gas planets can also have large solid cores: the Saturn-mass planet

text: HD 149026 b

text: has only two-thirds of Saturn's radius, so it may have a rock–ice core of 60 Earth masses or more.

text: has 4.24 times Jupiter's mass but a radius of only 0.84 that of Jupiter—it may have a metal core of 800 Earth masses if the heavy elements are concentrated in the core, or a core of 300 Earth masses if the heavy elements are more distributed throughout the planet.

text: Religions, such as those of the Egyptian and Greeks, imagined stories of the sun as the god Amon Ra and Apollo. Compared to those myths, the naturalist’s description of the sun as a raging nuclear furnace that is a mass of storms and unpredictable coronas is chaotic. All life on earth depends for its existence on the cycles of day and night as it orbits this raging near-chaos. Our planet is an island in the universe of perhaps infinite space, and no “sponsor” is going to save us from destroying our planet and ourselves. We are free to do that. If the infinite reaches of space-time are the wide water in which Earth is a minuscule island, that “water” is inescapable because there is no place else to go.

text: Universal time (UT1) tracks the Earth's rotation in time, which performs one revolution in about 24 hours. The Earth's rotation is uneven, so UT is not linear with respect to atomic time. It is practically proportional to the sidereal time, which is also a direct measure of Earth rotation. The excess revolution time is called length of day (LOD).

text: Universal time

text: ) tracks the Earth's rotation in time, which performs one revolution in about 24 hours. The Earth's rotation is uneven, so UT is not linear with respect to

text: atomic time

text: . It is practically proportional to the

text: sidereal time

text: , which is also a direct measure of Earth rotation. The excess revolution time is called

text: length of day (LOD)

text: Kepler-296e is a super-Earth with a radius 1.75 times that of Earth. The planet orbits Kepler-296 once every 34.1 days.

text: Kepler-296e is a

text: super-Earth

text: with a radius 1.75 times that of

text: Earth

text: . The planet orbits Kepler-296 once every 34.1 days.

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: Earth's mass is constantly changing due to many contributors. Earth primarily gains mass from micrometeorites and cosmic dust, whereas it loses hydrogen and helium gas. The combined effect is a net loss of material, though the annual mass deficit represents an inconsequential fraction of its total mass, or even the uncertainty in its mass. So its inclusion does not affect total mass calculations.A number of other mechanisms are responsible for mass adjustments, and can be classified into two categories: physical transfer of matter, and mass that is gained or lost through the absorption or release of energy due to the mass–energy equivalence principle.  Several examples are provided for completeness, but their relative contribution is negligible.

text: Earth's mass is constantly changing due to many contributors. Earth primarily gains mass from micrometeorites and cosmic dust, whereas it loses hydrogen and helium gas. The combined effect is a net loss of material, though the annual mass deficit represents an inconsequential fraction of its total mass, or even the uncertainty in its mass. So its inclusion does not affect total mass calculations.A number of other mechanisms are responsible for mass adjustments, and can be classified into two categories: physical transfer of

text: matter

text: , and mass that is gained or lost through the absorption or release of energy due to the

text: mass–energy equivalence

text: principle.  Several examples are provided for completeness, but their relative contribution is negligible.

text: A reformed Emerson traveled to the Earth's magnetic North pole to study it. Emerson was at the point where the lines of magnetic force converge when an earthquake plunged him into a deep crevice. At the bottom of the crevice lay a glowing blue blob. The radiation from the blob altered Emerson's perceptions, allowing him to understand the blob's intentions to dehydrate the entire Earth. Emerson was able to subconsciously influence Hal Jordan into becoming Green Lantern, but was unable to bring the Lantern to the North Pole. In desperation, Emerson created a mental duplicate of his evil alter ego. Doctor Polaris took advantage of the situation and attacked Green Lantern by blocking his power battery with a magnetic barrier. Doctor Polaris flew into Earth's orbit in order to increase the solar radiation reaching the planet. As he left the Earth's magnetic field, the barrier around the power ring faded, allowing Green Lantern to recover. Green Lantern managed to use micrometeorites to form an iron mask around Polaris' head, blocking off his vision. Back on Earth, Emerson was able to use telepathy to warn Green Lantern of the alien threat. Once Green Lantern disintegrated the blob, the mental image of the evil Doctor Polaris faded away.

text: A reformed Emerson traveled to the Earth's magnetic

text: North pole

text: to study it. Emerson was at the point where the lines of magnetic force converge when an earthquake plunged him into a deep crevice. At the bottom of the crevice lay a glowing blue blob. The radiation from the blob altered Emerson's perceptions, allowing him to understand the blob's intentions to dehydrate the entire Earth. Emerson was able to subconsciously influence Hal Jordan into becoming Green Lantern, but was unable to bring the Lantern to the North Pole. In desperation, Emerson created a mental duplicate of his evil alter ego. Doctor Polaris took advantage of the situation and attacked Green Lantern by blocking his power battery with a magnetic barrier. Doctor Polaris flew into Earth's orbit in order to increase the solar radiation reaching the planet. As he left the Earth's magnetic field, the barrier around the power ring faded, allowing Green Lantern to recover. Green Lantern managed to use micrometeorites to form an iron mask around Polaris' head, blocking off his vision. Back on Earth, Emerson was able to use

text: telepathy

text: to warn Green Lantern of the alien threat. Once Green Lantern disintegrated the blob, the mental image of the evil Doctor Polaris faded away.

text: Mr. Comics had the license until 2005 and released a six-issue miniseries, Revolution on the Planet of the Apes, by Joe O'Brien, Ty Templeton Sam Agro, and other writers, with art by Gabriel Morrissette and additional artists. The story picked up shortly after Caesar's conquest of the Earth after the apes' revolt and attempted to bridge the time gap before Battle for the Planet of the Apes (1973). Further stories were slated for release, including the next planned title, Empire on the Planet of the Apes, but the graphic novel collecting the Revolution miniseries was canceled, as was the Empire follow-up.

text: Mr. Comics had the license until 2005 and released a six-issue miniseries, Revolution on the Planet of the Apes, by Joe O'Brien,

text: Ty Templeton

text: Sam Agro, and other writers, with art by

text: Gabriel Morrissette

text: and additional artists. The story picked up shortly after

text: Caesar

text: 's

text: conquest of the Earth after the apes' revolt

text: and attempted to bridge the time gap before

text: Battle for the Planet of the Apes

text: (1973). Further stories were slated for release, including the next planned title, Empire on the Planet of the Apes, but the graphic novel collecting the Revolution miniseries was canceled, as was the Empire follow-up.

text: The plot unfolds across a time span of over 6,000 years. Kai's death (or undeath) occurs 2,008 years before the beginning of the events of the series. For the first two seasons, each episode is focused on space travel and usually one different planet.  Each of the last two seasons has a single location for all episodes. At the beginning of Season 3 the crew spends about 4,000 years in cryostats before arriving at the twin planets of Fire and Water. In Season 4, the Lexx reaches our Earth in the present.

text: In The Day the Earth Stood Still (1951), a flying saucer lands on the Mall in Washington DC, where it is surrounded by troops and tanks. The alien Klaatu delivers an ultimatum that the Earth must learn to live in peace or it will be destroyed. The War of the Worlds (1953) has a montage sequence where the countries of Earth join together to fight the Martian invaders. The montage conspicuously omits the Soviet Union, implying that the aliens are a metaphor for communists. The most elaborate science fiction films in the 1950s were This Island Earth (1955) and Forbidden Planet (1956). In the climax of both films, the characters witness the explosion of alien planets, implying Earth's possible fate. The World, the Flesh and the Devil (1959) is also in the science fiction genre. In it, a man, a woman, and a bigot (the devil) roam New York City after a nuclear war. Only those three characters appear in the film. Also released in 1959 was On the Beach, directed by Stanley Kramer and starring Ava Gardner, Gregory Peck and Fred Astaire.  Based on the  eponymous novel by Nevil Shute, the film deals with the citizens of Australia as they await radioactive fallout, a result of a catastrophic nuclear war in the Northern Hemisphere. The French author Stefan Wul's 1957 novel Niourk provided a portrait of New York after World War III.  The 1959 novel Alas, Babylon depicted the effects of nuclear war on a small town in Florida; a television adaptation was broadcast in 1960.

text: In

text: The Day the Earth Stood Still

text: (1951), a flying saucer lands on the

text: Mall in Washington DC

text: , where it is surrounded by troops and tanks. The alien Klaatu delivers an ultimatum that the Earth must learn to live in peace or it will be destroyed.

text: The War of the Worlds

text: (1953) has a montage sequence where the countries of Earth join together to fight the Martian invaders. The montage conspicuously omits the Soviet Union, implying that the aliens are a metaphor for communists. The most elaborate science fiction films in the 1950s were

text: This Island Earth

text: (1955) and

text: Forbidden Planet

text: (1956). In the climax of both films, the characters witness the explosion of alien planets, implying Earth's possible fate.

entity_name: The World, the Flesh and the Devil (1959 film)

text: The World, the Flesh and the Devil

text: (1959) is also in the science fiction genre. In it, a man, a woman, and a bigot (the devil) roam New York City after a nuclear war. Only those three characters appear in the film. Also released in 1959 was

text: On the Beach

text: , directed by

text: Stanley Kramer

text: and starring

text: Ava Gardner

text: Gregory Peck

text: and

text: Fred Astaire

text: .  Based on the

text: eponymous novel

text: by

text: Nevil Shute

text: , the film deals with the citizens of

text: Australia

text: as they await radioactive fallout, a result of a catastrophic

text: nuclear war

text: in the

text: Northern Hemisphere

text: . The

text: French

text: author

text: Stefan Wul

text: 's 1957 novel

text: Niourk

text: provided a portrait of New York after World War III.  The 1959 novel

text: Alas, Babylon

text: depicted the effects of nuclear war on a small town in Florida; a television adaptation was broadcast in 1960.

text: During a meteor shower said to be the most spectacular in 10,000 years, an asteroid hidden by the meteor field strikes the Moon. Fragments of the asteroid and of the Moon itself penetrate Earth's atmosphere and make impact.  The initial damage is minimal, though significant physical damage to the lunar surface can be seen from Earth.  Experts believe that the Moon has stabilized into a slightly closer orbit. Then strange anomalies begin to manifest themselves on Earth, including cell phone disruptions, unusual static discharges and odd tidal behavior. The world's leading scientists, including Alex Kittner, Maddie Rhodes, and Roland Emerson, begin piecing together evidence that suggests the moon's properties have been permanently altered because the asteroid that hit the Moon was actually a fragment of a brown dwarf; the fragment is highly magnetized and more massive than the Earth despite being only 19 kilometers across, and it is still inside the moon.  When the Moon's new, more elliptical orbit brings it closer to Earth, electromagnetic surges begin affecting the surface, causing people, vehicles, and other objects to levitate at random, worldwide.  Alex, Maddie, Roland and the rest of their team soon discover that the Moon's new orbit will cause it to collide with the Earth in 39 days, completely destroying the planet.  After a failed attempt by the United States to destroy the Moon with nuclear weapons, the three scientists plan an international mission to the Moon, where astronauts must construct a device to magnetize the Moon's core, causing it to disgorge the embedded brown dwarf fragment, eliminating the magnetic effects and restoring the Moon to a stable orbit.  Because of their unique expertise, Alex and Roland must join an American astronaut and a Russian cosmonaut on the mission, which is expected to be a one-way trip.

text: During a

text: meteor shower

text: said to be the most spectacular in 10,000 years, an

text: asteroid

text: hidden by the meteor field strikes the

text: Moon

text: . Fragments of the asteroid and of the Moon itself penetrate Earth's

text: atmosphere

text: and make impact.  The initial damage is minimal, though significant physical damage to the

text: lunar surface

text: can be seen from Earth.  Experts believe that the Moon has stabilized into a slightly closer orbit. Then strange anomalies begin to manifest themselves on Earth, including

text: cell phone

text: disruptions, unusual

text: static discharges

text: and odd

text: tidal behavior

text: . The world's leading scientists, including Alex Kittner, Maddie Rhodes, and Roland Emerson, begin piecing together evidence that suggests the moon's properties have been permanently altered because the asteroid that hit the Moon was actually a fragment of a

text: brown dwarf

text: ; the fragment is highly magnetized and more massive than the Earth despite being only 19 kilometers across, and it is still inside the moon.  When the Moon's new, more elliptical orbit brings it closer to Earth,

text: electromagnetic

text: surges begin affecting the surface, causing people, vehicles, and other objects to levitate at random, worldwide.  Alex, Maddie, Roland and the rest of their team soon discover that the Moon's new orbit will cause it to collide with the Earth in 39 days, completely destroying the planet.  After a failed attempt by the

text: United States

text: to destroy the Moon with nuclear weapons, the three scientists plan an international mission to the Moon, where

text: astronauts

text: must construct a device to magnetize the Moon's core, causing it to disgorge the embedded brown dwarf fragment, eliminating the magnetic effects and restoring the Moon to a stable orbit.  Because of their unique expertise, Alex and Roland must join an American astronaut and a Russian cosmonaut on the mission, which is expected to be a one-way trip.

text: Orbiting the star are three planets, whose discovery was announced in 2008; the discovery paper was published in 2009. The inner planet has a mass at least 7.5 times that of Earth, and is termed a super-Earth (this classification is based solely on the mass of the planet and should not be taken to imply that the planet could support Earthlike conditions). The middle planet and the outer planet are gas giants. The orbital periods for three planets are 9.3743 days for a 7.56 M planet, 962 days for a 0.64 M planet, and 2172 days for a 0.54 M planet. This solution is unstable, more data are required to constrain the orbital position of planet d.

text: Orbiting the star are three

text: planets

text: , whose discovery was announced in 2008; the discovery paper was published in 2009. The inner planet has a mass at least 7.5 times that of Earth, and is termed a

text: super-Earth

text: (this classification is based solely on the mass of the planet and should not be taken to imply that the planet could support Earthlike conditions). The middle planet and the outer planet are

text: gas giant

text: s. The

text: orbital period

text: s for three planets are 9.3743 days for a 7.56 M planet, 962 days for a 0.64

text: M

text: planet, and 2172 days for a 0.54 M planet. This solution is unstable, more data are required to constrain the orbital position of planet d.

text: A planet's atmospheric conditions influence its ability to retain heat, so that the location of the habitable zone is also specific to each type of planet: desert planets (also known as dry planets), with very little water, will have less water vapor in the atmosphere than Earth and so have a reduced greenhouse effect, meaning that a desert planet could maintain oases of water closer to its star than Earth is to the Sun. The lack of water also means there is less ice to reflect heat into space, so the outer edge of desert-planet habitable zones is further out.

text: A planet's atmospheric conditions influence its ability to retain heat, so that the location of the habitable zone is also specific to each type of planet:

text: desert planet

text: s (also known as dry planets), with very little water, will have less water vapor in the atmosphere than Earth and so have a reduced

text: greenhouse effect

text: , meaning that a desert planet could maintain oases of water closer to its star than Earth is to the Sun. The lack of water also means there is less ice to reflect heat into space, so the outer edge of desert-planet habitable zones is further out.

text: By 2.8 billion years from now, the surface temperature of the Earth will have reached , even at the poles. At this point, any remaining life will be extinguished due to the extreme conditions. If the Earth loses its surface water by this point, the planet will stay in the same conditions until the Sun becomes a red giant. If this scenario doesn't happen, then in about 3–4 billion years the amount of water vapour in the lower atmosphere will rise to 40% and a moist greenhouse effect will commence once the luminosity from the Sun reaches 35–40% more than its present-day value. A "runaway greenhouse" effect will ensue, causing the atmosphere to heat up and raising the surface temperature to around . This is sufficient to melt the surface of the planet. However, most of the atmosphere will be retained until the Sun has entered the red giant stage.

text: Tau Ceti e is an unconfirmed, fourth-known planet orbiting Tau Ceti that was detectedby statistical analyses of the data of the star's variations in radial velocity that were obtained using HIRES, AAPS, and HARPS. Few properties of the planet are known other than its orbit and mass. It orbits at a distance of 0.552 AU (between the orbits of Venus and Mercury in the Solar System) with an orbital period of 168 days and has a minimum mass of 4.3 Earth masses. Because the minimum mass of a super-Earth is 5 Earth masses, Tau Ceti e may be Earth sized. If it possesses an Earth-like atmosphere, the surface temperature would be around .

text: Tau Ceti e is an unconfirmed, fourth-known

text: planet

text: orbiting Tau Ceti that was detectedby statistical analyses of the data of the star's variations in

text: radial velocity

text: that were obtained using

text: HIRES

text: AAPS

text: , and

text: HARPS

text: . Few properties of the planet are known other than its orbit and mass. It orbits at a distance of 0.552

text: AU

text: (between the orbits of

text: Venus

text: and

text: Mercury

text: in the

text: Solar System

text: ) with an orbital period of 168 days and has a

text: minimum mass

text: of 4.3

text: Earth mass

text: es. Because the minimum mass of a super-Earth is 5 Earth masses, Tau Ceti e may be Earth sized. If it possesses an Earth-like atmosphere, the surface temperature would be around .

text: How Daniels survived being vaporized in "Cold Front" was never explained. However, Daniels continued to make occasional appearances in the series. In the first-season finale, "Shockwave", Daniels transported Archer to an altered version of the 31st century in which the United Federation of Planets had never existed. Daniels, apparently the only other person besides Archer left on Earth who knew about the main timeline, helped the captain restore the original timeline. In the third-season episode "Carpenter Street", he sent Archer and T'Pol back to the year 2004 to investigate why some Xindi Reptilians were on Earth in that time period. He was also seen in the episode "Azati Prime", in which he transported Archer into the future – placing him aboard a future starship called the Enterprise-J, to inform him about the Sphere Builders and their relationship to the Xindi. He later transported Archer to the year 2161, giving him a glimpse of the inauguration ceremony for the United Federation of Planets (which occurred in a later episode, in "These Are the Voyages..."), warning Archer that allowing the Xindi to change history would result in the destruction of the UFP before it even existed. In his final appearance in the fourth-season premiere, "Storm Front", he was apparently extremely ill: parts of him were more than a hundred years old while other parts were almost at a fetal stage. He used his last remaining strength to transport Archer and the Enterprise to Earth in the year 1944 to stop an alien race from changing history and allowing the Nazis to win World War II. After warning T'Pol that the Temporal Cold War had exploded into a full-fledged conflict, Daniels apparently died, but with the collapse of the Temporal War, Daniels reappeared and returned Archer to his original timeline.

text: How Daniels survived being vaporized in "Cold Front" was never explained. However, Daniels continued to make occasional appearances in the series. In the first-season finale, "

text: Shockwave

text: ", Daniels transported Archer to an altered version of the 31st century in which the

text: United Federation of Planets

text: had never existed. Daniels, apparently the only other person besides Archer left on Earth who knew about the main timeline, helped the captain restore the original timeline. In the third-season episode "

entity_name: Carpenter Street (Star Trek: Enterprise)

text: Carpenter Street

text: ", he sent Archer and T'Pol back to the year 2004 to investigate why some Xindi Reptilians were on Earth in that time period. He was also seen in the episode "

text: Azati Prime

text: ", in which he transported Archer into the future – placing him aboard a future starship called the

text: Enterprise-J

text: , to inform him about the

text: Sphere Builder

text: s and their relationship to the

text: Xindi

text: . He later transported Archer to the year 2161, giving him a glimpse of the inauguration ceremony for the United Federation of Planets (which occurred in a later episode, in "

text: These Are the Voyages...

text: "), warning Archer that allowing the Xindi to change history would result in the destruction of the UFP before it even existed. In his final appearance in the fourth-season premiere, "

text: Storm Front

text: ", he was apparently extremely ill: parts of him were more than a hundred years old while other parts were almost at a fetal stage. He used his last remaining strength to transport Archer and the Enterprise to Earth in the year 1944 to stop an alien race from changing history and allowing the

text: Nazis

text: to win

text: World War II

text: . After warning T'Pol that the Temporal Cold War had exploded into a full-fledged conflict, Daniels apparently died, but with the collapse of the Temporal War, Daniels reappeared and returned Archer to his original timeline.

text: In Philolaus' system, the Earth did not rotate and its inhabited surface faced away from the Central Fire—possibly because it (the Earth) was flat. The revolution of the Earth around the Central Fire was not yearly but daily, while the Moon's revolution was monthly, and the sun's yearly. It was the Earth's speedy travel past the slower moving Sun that resulted in the appearance on Earth of the Sun rising and setting.  Further from the Central Fire, the Planets' movement was slower still, and the outermost "sky" (i.e. stars) probably fixed.

text: This season is similar to season one, because this season stars the same cast members and is also taped in Orlando, Florida. After the next season ended the show moved out of Florida and moved to Nickelodeon on Sunset (formerly The Aquarius Theater) in Hollywood, California. Season 2 is also the final season for Angelique Bates, whose contract with the show was not renewed.

text: This season is similar to season one, because this season stars the same cast members and is also taped in

text: Orlando, Florida

text: . After the next season ended the show moved out of Florida and moved to

text: Nickelodeon on Sunset

text: (formerly The Aquarius Theater) in

text: Hollywood, California

text: . Season 2 is also the final season for

text: Angelique Bates

text: , whose contract with the show was not renewed.

text: Because this is the period of rotation in a precessing reference frame, it is not directly related to the mean rotation rate of Earth in an inertial frame, which is given by ω =  where T is the slightly longer stellar day given by Aoki et al. as 86  s. This can be calculated by noting that ω is the magnitude of the vector sum of the rotations leading to the sidereal day and the precession of that rotation vector. In fact, the period of Earth's rotation varies on hourly to interannual timescales by around 1 millisecond, together with a secular increase in length of day of about 2.3 ms per century, mostly from tidal friction slowing Earth's rotation.

text: Because this is the period of rotation in a precessing reference frame, it is not directly related to the mean rotation rate of Earth in an inertial frame, which is given by ω =  where T is the slightly longer stellar day given by Aoki et al. as 86  s. This can be calculated by noting that ω is the magnitude of the vector sum of the rotations leading to the sidereal day and the precession of that rotation vector. In fact, the period of Earth's rotation varies on hourly to interannual timescales by around 1

text: millisecond

text: , together with a secular increase in length of day of about 2.3 ms per century, mostly from

text: tidal friction

text: slowing Earth's rotation.

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: There are 15 planets in our universe which contain human life. We started our divine cycle on the Moon and, via six other planets, arrived on Mars. Then again, via six other planets, we finally arrived on Earth. Each of these planets pushed the development of the human body a bit further. For example, on the Moon, we reached only a fishlike phase but on Mars, we were already like an ape. This means that there are no other planets in our universe which contain human life which is as developed as on Earth.

text: There are 15 planets in our

text: universe

text: which contain human life. We started our divine cycle on the

text: Moon

text: and, via six other planets, arrived on

text: Mars

text: . Then again, via six other planets, we finally arrived on

text: Earth

text: . Each of these planets pushed the development of the human body a bit further. For example, on the

text: Moon

text: , we reached only a fishlike phase but on

text: Mars

text: , we were already like an ape. This means that there are no other planets in our

text: universe

text: which contain human life which is as developed as on

text: Earth

text: A terrestrial planet, telluric planet, or rocky planet is a planet that is composed primarily of silicate rocks or metals. Within the Solar System, the terrestrial planets are the inner planets closest to the Sun, i.e. Mercury, Venus, Earth, and Mars. The terms "terrestrial planet" and "telluric planet" are derived from Latin words for Earth (Terra and Tellus), as these planets are, in terms of composition, "Earth-like".

text: A terrestrial planet, telluric planet, or rocky planet is a

text: planet

text: that is composed primarily of

text: silicate

text: rocks

text: 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: , i.e.

text: Mercury

text: Venus

text: Earth

text: , and

text: Mars

text: . The terms "terrestrial planet" and "telluric planet" are derived from

text: Latin

text: words for

text: Earth

text: (Terra and Tellus), as these planets are, in terms of composition, "Earth-like".

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: Urth gives Peyton his own flawed, yet still valuable singing bell to examine. He then has Peyton throw it back to him. The toss falls short and the bell is destroyed when it crashes to the floor. Urth has demonstrated that Peyton had been off-planet very recently, despite his claim to the contrary, and had not yet readjusted to Earth's gravity. The killer is taken away to be psycho-probed. Urth requests a perfect bell as his fee.

text: The first success of this technique was made in 2003 by both OGLE and MOA of the microlensing event OGLE 2003–BLG–235 (or MOA 2003–BLG–53). Combining their data, they found the most likely planet mass to be 1.5 times the mass of Jupiter. As of January 2011, eleven exoplanets have been detected by this method, including OGLE-2005-BLG-071Lb, OGLE-2005-BLG-390Lb, OGLE-2005-BLG-169Lb, two exoplanets around OGLE-2006-BLG-109L, and MOA-2007-BLG-192Lb. Notably, at the time of its announcement in January 2006, the planet OGLE-2005-BLG-390Lb probably had the lowest mass of any known exoplanet orbiting a regular star, with a median at 5.5 times the mass of the Earth and roughly a factor two uncertainty. This record was contested in 2007 by Gliese 581 c  with a minimal mass of 5 Earth masses, and since 2009 Gliese 581 e is the lightest known "regular" exoplanet, with minimum 1.9 Earth masses.

text: The first success of this technique was made in 2003 by both OGLE and MOA of the microlensing event

text: OGLE 2003–BLG–235 (or MOA 2003–BLG–53)

text: . Combining their data, they found the most likely planet mass to be 1.5 times the mass of Jupiter. As of January 2011, eleven exoplanets have been detected by this method, including

text: , two exoplanets around

text: , and

text: . Notably, at the time of its announcement in January 2006, the planet OGLE-2005-BLG-390Lb probably had the lowest mass of any known exoplanet orbiting a regular star, with a median at 5.5 times the mass of the Earth and roughly a factor two uncertainty. This record was contested in 2007 by

text: Gliese 581 c

text: with a minimal mass of 5 Earth masses, and since 2009

text: Gliese 581 e

text: is the lightest known "regular" exoplanet, with minimum 1.9 Earth masses.

text: Earth's atmosphere and oceans were formed by volcanic activity and outgassing that included water vapor. The origin of the world's oceans was condensation augmented by water and ice delivered by asteroids, proto-planets, and comets. In this model, atmospheric "greenhouse gases" kept the oceans from freezing while the newly forming Sun was only at 70% luminosity. By , the Earth's magnetic field was established, which helped prevent the atmosphere from being stripped away by the solar wind. The atmosphere and oceans of the Earth continuously shape the land by eroding and transporting solids on the surface.

text: Earth's atmosphere and oceans were formed by

text: volcanic

text: activity and

text: outgassing

text: that included

text: water vapor

text: . The

text: origin of the world's oceans

text: was condensation augmented by water and ice delivered by

text: asteroid

text: s,

text: proto-planets

text: , and

text: comet

text: s. In

text: this model

text: , atmospheric "

text: greenhouse gas

text: es" kept the oceans from freezing while the newly forming Sun was only at 70%

text: luminosity

text: . By , the

text: Earth's magnetic field

text: was established, which helped prevent the atmosphere from being stripped away by the

text: solar wind

text: . The atmosphere and oceans of the Earth continuously shape the land by eroding and transporting solids on the surface.

text: The Space Bikers are a gang of alien bikers (most of the gang is made up of women, while only of them is a male) who like to cause mayhem on Earth. However, it was revealed in the third season that all five of the gang work at a school on their home planet, and their homeworld is much like Earth, and that their role as bikers is merely just a hobby.

text: The Earth's magnetic field is thought to be produced by convection currents in the outer liquid of Earth's core. The Dynamo theory proposes that these movements produce electric currents that, in turn, produce the magnetic field.

text: The Earth's magnetic field is thought to be produced by convection currents in the outer liquid of Earth's core. The

text: Dynamo theory

text: proposes that these movements produce electric currents that, in turn, produce the magnetic field.

text: version of the  invaded the Earth, masking their true intentions with peaceful purposes. They had the ability to control any creature with a certain DNA compound called M-Base, a compound which both the mutant soldiers of M-Force and they can also alter DNA so they can control other creature like the kaiju. They used their control of M-Base to send the monsters on rampages across the globe – Rodan in New York City, Anguirus in Shanghai, Kamacuras in Paris, Zilla in Sydney, King Caesar in Okinawa, Kumonga in Arizona, and  Ebirah in Tokai. After allowing them to cause enough damage to their locations, the Xiliens teleported the monsters away, telling the people of the Earth that they rescued them, and want only peace between their planets (Earth and Planet X). They warned humanity of a small run-away planet known as Gorath, saying that unless we aimed all our firepower at it, Gorath would collide with the Earth (the planet was the main concern in Gorath, an older film).

text: version of the  invaded the

text: Earth

text: , masking their true intentions with peaceful purposes. They had the ability to control any creature with a certain

text: DNA

text: compound called M-Base, a compound which both the mutant soldiers of M-Force and they can also alter DNA so they can control other creature like the

text: kaiju

text: . They used their control of M-Base to send the monsters on rampages across the globe –

text: Rodan

text: in New York City,

text: Anguirus

text: in Shanghai,

text: Kamacuras

text: in Paris,

text: Zilla

text: in Sydney,

text: King Caesar

text: in

text: Okinawa

text: Kumonga

text: in

text: Arizona

text: , and

text: Ebirah

text: in

text: Tokai

text: . After allowing them to cause enough damage to their locations, the Xiliens teleported the monsters away, telling the people of the Earth that they rescued them, and want only peace between their planets (Earth and

text: Planet X

text: ). They warned humanity of a small run-away planet known as

text: Gorath

text: , saying that unless we aimed all our firepower at it, Gorath would collide with the Earth (the planet was the main concern in

text: Gorath

text: , an older film).

text: The phenomenon of day and night is due to the rotation of a celestial body about its axis, creating an illusion of the sun rising and setting. Different bodies spin at very different rates, however. Some may spin much faster than Earth, while others spin extremely slowly, leading to very long days and nights. The planet Venus rotates once every 224.7 days – by far the slowest rotation period of any of the major planets. In contrast, the gas giant Jupiter's sidereal day is only 9 hours and 56 minutes. However, it is not just the sidereal rotation period which determines the length of a planet's day-night cycle but the length of its orbital period as well - Venus has a rotation period of 224.7 days, but a day-night cycle just 116.75 days long due to its retrograde rotation and orbital motion around the Sun. Mercury has the longest day-night cycle as a result of its 3:2 resonance between its orbital period and rotation period - this resonance gives it a day-night cycle 176 days long. A planet may experience large temperature variations between day and night, such as Mercury, the planet closest to the sun. This is one consideration in terms of planetary habitability or the possibility of extraterrestrial life.

text: The phenomenon of day and night is due to the rotation of a

text: celestial body

text: about its axis, creating an illusion of the sun rising and setting. Different bodies spin at very different rates, however. Some may spin much faster than

text: Earth

text: , while others spin extremely slowly, leading to very long days and nights. The planet

text: Venus

text: rotates once every 224.7 days – by far the slowest rotation period of any of the major planets. In contrast, the gas giant

text: Jupiter

text: 's

text: sidereal day

text: is only 9 hours and 56 minutes. However, it is not just the sidereal rotation period which determines the length of a planet's day-night cycle but the length of its orbital period as well - Venus has a rotation period of 224.7 days, but a day-night cycle just 116.75 days long due to its

text: retrograde

text: rotation and orbital motion around the Sun. Mercury has the longest day-night cycle as a result of its 3:2 resonance between its orbital period and rotation period - this resonance gives it a day-night cycle 176 days long. A planet may experience large temperature variations between day and night, such as

text: Mercury

text: , the planet closest to the sun. This is one consideration in terms of

text: planetary habitability

text: or the possibility of

text: extraterrestrial life

text: In both Hipparchian and Ptolemaic systems, the planets are assumed to move in a small circle called an epicycle, which in turn moves along a larger circle called a deferent. Both circles rotate clockwise and are roughly parallel to the plane of the Sun's orbit (ecliptic). Despite the fact that the system is considered geocentric, each planet's motion was not centered on the Earth but at a point slightly away from Earth called the eccentric. The orbits of planets in this system are similar to epitrochoids.

text: In both Hipparchian and Ptolemaic systems, the

text: planet

text: s are assumed to move in a small circle called an epicycle, which in turn moves along a larger circle called a deferent. Both circles rotate clockwise and are roughly parallel to the plane of the Sun's orbit (

text: ecliptic

text: ). Despite the fact that the system is considered

text: geocentric

text: , each planet's motion was not centered on the Earth but at a point slightly away from Earth called the eccentric. The

text: orbit

text: s of planets in this system are similar to

text: epitrochoid

text: s.

text: Mercury's magnetic field is approximately a magnetic dipole (meaning the field has only two magnetic poles)  apparently global, on planet Mercury. Data from Mariner 10 led to its discovery in 1974; the spacecraft measured the field's strength as 1.1% that of Earth's magnetic field. The origin of the magnetic field can be explained by dynamo theory,.  The magnetic field is strong enough near the bow shock to slow the solar wind, which induces a magnetosphere.

text: Mercury's magnetic field is approximately a magnetic

text: dipole

text: (meaning the field has only two magnetic poles)  apparently global, on

text: planet Mercury

text: . Data from

text: Mariner 10

text: led to its discovery in 1974; the spacecraft measured the field's strength as 1.1% that of

text: Earth's magnetic field

text: . The origin of the magnetic field can be explained by

text: dynamo theory

text: ,.  The magnetic field is strong enough near the

text: bow shock

text: to slow the

text: solar wind

text: , which induces a

text: magnetosphere

text: The Librarian then draws the Flood towards Earth to allow the IsoDidact to fire the seven Halo rings. She sends Chant-to-Green off to the lesser Ark with the planet's remaining humans and passes her title of Lifeshaper on to Chant while remaining on Earth herself. During her last days on Earth, the Gravemind sends down ancient human essences, including the Lord of Admirals, to reveal that the Domain was created by the Precursors as the collection of wisdom from over 100 billion years of knowledge and that it was ingrained in Precursor architecture for safekeeping. In short, the Domain is the mythical Organon. Sadly, the Librarian realizes that the Halos will destroy all of this, and that without the Domain, the Ur-Didact will spend the eons to come in complete silence, dwelling on his own madness and rage. As she watches the Portal's construction, she sincerely hopes humanity will one day inherit the Mantle.

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: In the case of the New Washington/Franklin planetary system, the configuration of the planets addresses a problem with having a red-dwarf as a central sun. Any planet close enough to the sun to maintain an Earth-like climate would be tidally locked with its orbit so it would always keep the same face toward its sun. In order to restore a night-day cycle, Pournelle created a double planet. New Washington and Franklin are about the same size and orbit a common center with a period of 40 hours. They are tidally locked in this orbit, so they always present the same face to one another. Together they orbit their sun once every 52 days.

text: In the case of the New Washington/Franklin planetary system, the configuration of the planets addresses a problem with having a red-dwarf as a central sun. Any planet close enough to the sun to maintain an Earth-like climate would be

text: tidally locked

text: with its orbit so it would always keep the same face toward its sun. In order to restore a night-day cycle, Pournelle created a double planet. New Washington and Franklin are about the same size and orbit a common center with a period of 40 hours. They are tidally locked in this orbit, so they always present the same face to one another. Together they orbit their sun once every 52 days.

text: In Australia, Season 1 was released in 2004, Season 2 and Season 3 in 2006, Season 4 and Season 5 in 2007, Season 6 and Season 7 in 2008 and Season 8 in 2009.

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: Kepler-78b is 69% more massive than Earth and 20% larger. Two independent teams were involved in pioneering work to estimate the mass of the planet. The estimates were made possible because Kepler-78b's gravity causes a "wobble" in the orbit of the host star. While the method has been used to characterize gas giants, ordinarily it is hard to estimate the mass of Earth-sized exoplanets because their gravity is too weak to produce a visible influence on their stars. In this case, the planet's orbit is so close to its star that its gravitational influence has a detectable effect.

text: Kepler-78b is 69% more massive than Earth and 20% larger. Two independent teams were involved in pioneering work to estimate the mass of the planet. The estimates were made possible because Kepler-78b's gravity causes a "wobble" in the orbit of the host star. While the method has been used to characterize

text: gas giants

text: , ordinarily it is hard to estimate the mass of Earth-sized exoplanets because their gravity is too weak to produce a visible influence on their stars. In this case, the planet's orbit is so close to its star that its gravitational influence has a detectable effect.

text: Kepler-12b has a mass of 0.431 Jupiters. Its radius of 1.695 Jupiter radii, however, indicates that the planet is almost 70% more than the size of Jupiter. With an orbit of 0.0556 AU, Kepler-12b's average orbit is approximately 5% the average distance between the Earth and Sun. The orbit lasts 4.4379637 days. Kepler-12b has an orbital inclination of 88.86º, indicating that the planet is seen as nearly edge-on with respect to the Earth and to its host star. According to Kepler's official website, the mass and radius of the planet can be compared to 137 Earths (in mass) and 19 Earths (for its radius). The planet's density is 0.111 grams/cm, about a tenth of the density of water, and its equilibrium temperature is 1481 K (some 5.8 times greater than Jupiter's equilibrium temperature). Additionally, Kepler-12b has an almost totally circular orbit, with an orbital eccentricity of less than 0.01.

text: Kepler-12b has a mass of 0.431 Jupiters. Its radius of 1.695

text: Jupiter radii

text: , however, indicates that the planet is almost 70% more than the size of Jupiter. With an orbit of 0.0556

text: AU

text: , Kepler-12b's

text: average orbit

text: is approximately 5% the average distance between the Earth and Sun. The orbit lasts 4.4379637 days. Kepler-12b has an

text: orbital inclination

text: of 88.86º, indicating that the planet is seen as nearly edge-on with respect to the Earth and to its host star. According to Kepler's official website, the mass and radius of the planet can be compared to 137 Earths (in mass) and 19 Earths (for its radius). The planet's density is 0.111 grams/cm, about a tenth of the density of water, and its

text: equilibrium temperature

text: is 1481

text: K

text: (some 5.8 times greater than Jupiter's equilibrium temperature). Additionally, Kepler-12b has an almost totally circular orbit, with an

text: orbital eccentricity

text: of less than 0.01.

text: The water planet Aquarius is heading towards Earth after flooding the home planet of the warrior race of the Dinguil. The Dinguil use warp technology to make the planet move towards Earth faster than usual. The warrior race plans to flood Earth and make it their new home. When Earth learns of this, they make plans to evacuate humanity. Unfortunately, the Dinguil destroy the evacuation fleets. The space battleship Yamato, under the newly revived Jyuzo Okita (who seemingly died in the first season of the original series) now has to fight the Dinguil and stop Aquarius from flooding the Earth.

text: The hemisphere of the Earth experiencing daytime at any given instant changes continuously as the planet rotates on its own axis. The axis of the Earth's rotation is not perpendicular to the plane of its orbit around the Sun (which is parallel with the direction of sunlight), and so the length of the daytime period varies from one point on the planet to another. Additionally, since the axis of rotation is relatively fixed in comparison to the stars, it moves with respect to the Sun as the planet orbits the star. This creates seasonal variations in the length of the daytime period at most points on the planet's surface.

text: The

text: hemisphere

text: of the Earth experiencing daytime at any given instant changes continuously as the planet rotates on its own axis. The axis of the Earth's rotation is not perpendicular to the plane of its

text: orbit

text: around the

text: Sun

text: (which is parallel with the direction of sunlight), and so the length of the daytime period varies from one point on the planet to another. Additionally, since the axis of rotation is relatively fixed in comparison to the stars, it moves with respect to the Sun as the planet orbits the star. This creates seasonal variations in the length of the daytime period at most points on the planet's surface.

text: Diurnal parallax is a parallax that varies with rotation of the Earth or with difference of location on the Earth. The Moon and to a smaller extent the terrestrial planets or asteroids seen from different viewing positions on the Earth (at one given moment) can appear differently placed against the background of fixed stars.

text: Diurnal parallax is a parallax that varies with rotation of the Earth or with difference of location on the Earth. The Moon and to a smaller extent the

text: terrestrial planet

text: s or

text: asteroid

text: s seen from different viewing positions on the Earth (at one given moment) can appear differently placed against the background of fixed stars.

text: Given the Moon's high velocity and rapidly increasing distance from Earth, Koenig made the hard decision to not attempt an evacuation and instead remain on Alpha, where the base's personnel could sustain themselves and search for another planet on which to settle; the search for a "new Earth" would become a dominant theme in the series' two seasons.

text: Another set of scientific arguments against a Hollow Earth or any hollow planet comes from gravity. Massive objects tend to clump together gravitationally, creating non-hollow spherical objects such as stars and planets. The solid sphere is the best way in which to minimize the gravitational potential energy of a physical object; having hollowness is  unfavorable in the energetic sense. In addition, ordinary matter is not strong enough to support a hollow shape of planetary size against the force of gravity; a planet-sized hollow shell with the known, observed thickness of the Earth's crust would not be able to achieve hydrostatic equilibrium with its own mass and would collapse.

text: Another set of scientific arguments against a Hollow Earth or any hollow planet comes from

text: gravity

text: . Massive objects tend to clump together gravitationally, creating non-hollow spherical objects such as stars and planets. The solid sphere is the best way in which to minimize the

text: gravitational potential energy

text: of a physical object; having hollowness is  unfavorable in the energetic sense. In addition, ordinary matter is not strong enough to support a hollow shape of planetary size against the force of gravity; a planet-sized hollow shell with the known, observed thickness of the Earth's crust would not be able to achieve

text: hydrostatic equilibrium

text: with its own mass and would collapse.

text: Mass estimates range from 0.32  for a pure water/ice composition to 3.77  if made up entirely of iron (both implausible extremes). For a body with radius 1.11 , a composition similar to that of Earth (i.e., 1/3 iron, 2/3 silicate rock) yields a mass of 1.44 , taking into account the higher density due to the higher average pressure compared to Earth.

text: Mass estimates range from 0.32  for a pure

text: water

text: /ice composition to 3.77  if made up entirely of

text: iron

text: (both implausible extremes). For a body with radius 1.11 , a composition similar to that of Earth (i.e., 1/3 iron, 2/3

text: silicate rock

text: ) yields a mass of 1.44 , taking into account the higher density due to the higher average

text: pressure

text: compared to Earth.

text: The concept of hydrostatic equilibrium has also become important in determining whether an astronomical object is a planet, dwarf planet, or small Solar System body. According to the definition of planet adopted by the International Astronomical Union in 2006, one defining characteristic of planets and dwarf planets is that they are objects that have sufficient gravity to overcome their own rigidity and assume hydrostatic equilibrium. Such a body will normally have the differentiated interior and geology of a world (a planemo), though near-hydrostatic bodies such as the proto-planet 4 Vesta may also be differentiated. Sometimes the equilibrium shape is an oblate spheroid, as is the case with Earth. However, in the cases of moons in synchronous orbit, nearly unidirectional tidal forces create a scalene ellipsoid. Also, the dwarf planet  is scalene due to its rapid rotation.

text: The concept of hydrostatic equilibrium has also become important in determining whether an astronomical object is a

text: planet

text: dwarf planet

text: , or

text: small Solar System body

text: . According to the

text: definition of planet

text: adopted by the

text: International Astronomical Union

text: in 2006, one defining characteristic of planets and dwarf planets is that they are objects that have sufficient gravity to overcome their own rigidity and assume hydrostatic equilibrium. Such a body will normally have the differentiated interior and geology of a world (a

text: planemo

text: ), though near-hydrostatic bodies such as the proto-planet

text: 4 Vesta

text: may also be differentiated. Sometimes the equilibrium shape is an

text: oblate spheroid

text: , as is the case with Earth. However, in the cases of moons in synchronous orbit, nearly unidirectional tidal forces create a

text: scalene ellipsoid

text: . Also, the dwarf planet  is scalene due to its rapid rotation.

text: Before the term Copernican principle was even coined, Earth was repeatedly shown not to have any special location in the universe. The Copernican Revolution dethroned Earth to just one of many planets orbiting the Sun. William Herschel found that the Solar System is moving through space within our disk-shaped Milky Way galaxy. Edwin Hubble showed that our galaxy is just one of many galaxies in the universe. Examination of our galaxy's position and motion in the universe led to the Big Bang theory and the whole of modern cosmology.

text: Before the term Copernican principle was even coined, Earth was repeatedly shown not to have any special location in the universe. The

text: Copernican Revolution

text: dethroned Earth to just one of many planets orbiting the Sun.

text: William Herschel

text: found that the Solar System is moving through space within our disk-shaped

text: Milky Way

text: galaxy.

text: Edwin Hubble

text: showed that our galaxy is just one of many galaxies in the universe. Examination of our galaxy's position and motion in the universe led to the

text: Big Bang theory

text: and the whole of modern

text: cosmology

text: Traditionally, night and day were each allocated four pahars, or "watches." The first pahar of the day (or din pahar) was timed to begin at sunrise, and the first pahar of the night (raat pahar) was timed to begin at sunset.

text: The Egyptians portrayed the god Ra as being carried across the sky in a solar barque, accompanied by lesser gods, and to the Greeks, he was Helios, carried by a chariot drawn by fiery horses. From the reign of Elagabalus in the late Roman Empire the Sun's birthday was a holiday celebrated as Sol Invictus (literally "Unconquered Sun") soon after the winter solstice, which may have been an antecedent to Christmas. Regarding the fixed stars, the Sun appears from Earth to revolve once a year along the ecliptic through the zodiac, and so Greek astronomers categorized it as one of the seven planets (Greek planetes, "wanderer"); the naming of the days of the weeks after the seven planets dates to the Roman era.

text: The Egyptians portrayed the god

text: Ra

text: as being carried across the sky in a solar barque, accompanied by lesser gods, and to the Greeks, he was

text: Helios

text: , carried by a chariot drawn by fiery horses. From the reign of

text: Elagabalus

text: in the

text: late Roman Empire

text: the Sun's birthday was a holiday celebrated as

text: Sol Invictus

text: (literally "Unconquered Sun") soon after the winter solstice, which may have been an antecedent to Christmas. Regarding the

text: fixed star

text: s, the Sun appears from Earth to revolve once a year along the

text: ecliptic

text: through the

text: zodiac

text: , and so Greek astronomers categorized it as one of the seven

text: planets

text: (Greek planetes, "wanderer"); the naming of the

text: days of the weeks

text: after the seven planets dates to the

text: Roman era

text: The Earth is not a perfect sphere but an oblate spheroid, with an equatorial diameter about 43 kilometers larger than its polar diameter. Because of the Earth's axial tilt, during most of the year the half of this bulge that is closest to the Sun is off-center, either to the north or to the south, and the far half is off-center on the opposite side. The gravitational pull on the closer half is stronger, since gravity decreases with distance, so this creates a small torque on the Earth as the Sun pulls harder on one side of the Earth than the other.  The axis of this torque is roughly perpendicular to the axis of the Earth's rotation so the axis of rotation precesses. If the Earth were a perfect sphere, there would be no precession.

text: The Earth is not a perfect sphere but an

text: oblate spheroid

text: , with an equatorial diameter about 43 kilometers larger than its polar diameter. Because of the Earth's

text: axial tilt

text: , during most of the year the half of this bulge that is closest to the Sun is off-center, either to the north or to the south, and the far half is off-center on the opposite side. The gravitational pull on the closer half is stronger, since gravity decreases with distance, so this creates a small torque on the Earth as the Sun pulls harder on one side of the Earth than the other.  The axis of this torque is roughly perpendicular to the axis of the Earth's rotation so the axis of rotation

text: precesses

text: . If the Earth were a perfect sphere, there would be no precession.

text: In keeping with a long tradition in western art, the sculptor personified time with figures representing night and day.  Night has long, smooth, graceful curves that are repeated in the lines of the swan in flight beneath her.  In comparison, Day is more angular and his muscles are more pronounced, as are the veins in the arms and hands.  Day rests upon an otter, hunting among a school of Northern pike and Night floats upon a swan in flight, holding a small bird in her hand.

text: In about 5 to 6 billion years, the Sun will have depleted the hydrogen fuel in its core and will begin to expand. At its largest, its surface (photosphere) will approximately reach the current orbit of Earth. It will then lose its atmosphere completely; its outer layers forming a planetary nebula and the core a white dwarf. The evolution of the Sun into and through the red-giant phase has been extensively modelled, but it remains unclear whether Earth will be engulfed by the Sun or will continue in orbit. The uncertainty arises in part because as the Sun burns hydrogen, it loses mass causing Earth (and all planets) to orbit farther away. There are also significant uncertainties in calculating the orbits of the planets over the next 5–6.5 billion years, so the fate of Earth is not well understood. At its brightest, the red-giant Sun will be several thousand times more luminous than today but its surface will be at about half the temperature. In its red giant phase, the Sun will be so bright that any water on Earth will boil away into space, leaving it unable to support life.

text: In about 5 to 6 billion years, the Sun will have depleted the hydrogen fuel in its core and will begin to expand. At its largest, its surface (

text: photosphere

text: ) will approximately reach the current orbit of Earth. It will then lose its atmosphere completely; its outer layers forming a

text: planetary nebula

text: and the core a

text: white dwarf

text: . The evolution of the Sun into and through the red-giant phase has been extensively modelled, but it remains unclear whether Earth will be engulfed by the Sun or will continue in orbit. The uncertainty arises in part because as the Sun burns hydrogen, it loses mass causing Earth (and all planets) to orbit farther away. There are also significant uncertainties in calculating the orbits of the planets over the next 5–6.5 billion years, so the fate of Earth is not well understood. At its brightest, the red-giant Sun will be several thousand times more luminous than today but its surface will be at about half the temperature. In its red giant phase, the Sun will be so bright that any water on Earth will boil away into space, leaving it unable to support life.

text: Kepler-6 was named for the Kepler Mission, a NASA project launched in 2009 that aims to discover Earth-like planets that transit, or cross in front of, their home stars with respect to Earth. Unlike stars like the Sun or Sirius, Kepler-6 does not have a common and colloquial name. The discovery of Kepler-6b was announced by the Kepler team on January 4, 2010 at the 215th meeting of the American Astronomical Society along with planets around Kepler-4, Kepler-5, Kepler-7, and Kepler-8. It was the third planet to be discovered by the Kepler spacecraft; the first three planets to be verified by data from Kepler had been previously discovered. These three planets were used to test the accuracy of Kepler's measurements.

text: Kepler-6 was named for the

text: Kepler Mission

text: , a

text: NASA

text: project launched in 2009 that aims to discover

text: Earth-like

text: planets that

text: transit

text: , or cross in front of, their home stars with respect to

text: Earth

text: . Unlike stars like the

text: Sun

text: or

text: Sirius

text: , Kepler-6 does not have a common and colloquial name. The discovery of Kepler-6b was announced by the Kepler team on January 4, 2010 at the

text: 215th meeting

text: of the

text: American Astronomical Society

text: along with planets around

text: , and

text: . It was the third planet to be discovered by the Kepler spacecraft; the first three planets to be verified by data from Kepler had been previously discovered. These three planets were used to test the accuracy of Kepler's measurements.

text: Between the time of the previous analysis and June 2012, the rest of the radial-velocity measurements used in 2011 were made public, allowing them to be reduced using HARPS-TERRA. These were then analysed via a Bayesian probability analysis, which was previously used to discover HD 10180 i and j, which confirmed planet b and made a first characterisation of planet c, which was previously only described as a trend. After the first two signals were introduced, the next most powerful signal was at around 35.5 days, with an analytic false alarm probability of 0.156. Through 10 trials, the false alarm probability was found to be 0.44%, low enough for it to be included as a periodic, planetary signal. With a minimum mass of around 11 Earths, the planet lies at the accepted border between Super-Earths and gaseous, Neptune-like bodies of 10 Earths.After accepting the third signal, a strong peak at 3.6 days became apparent. With a false alarm probability much lower than that of the previously accepted body, it was immediately accepted. With a minimum mass of around 4.5 Earths, it is a small Super-Earth.

text: Between the time of the previous analysis and June 2012, the rest of the radial-velocity measurements used in 2011 were made public, allowing them to be reduced using HARPS-TERRA. These were then analysed via a

text: Bayesian probability

text: analysis, which was previously used to discover

text: HD 10180

text: i and j, which confirmed planet b and made a first characterisation of planet c, which was previously only described as a trend. After the first two signals were introduced, the next most powerful signal was at around 35.5 days, with an analytic false alarm probability of 0.156. Through 10 trials, the false alarm probability was found to be 0.44%, low enough for it to be included as a periodic, planetary signal. With a minimum mass of around 11 Earths, the planet lies at the accepted border between

text: Super-Earth

text: s and gaseous, Neptune-like bodies of 10 Earths.After accepting the third signal, a strong peak at 3.6 days became apparent. With a false alarm probability much lower than that of the previously accepted body, it was immediately accepted. With a minimum mass of around 4.5 Earths, it is a small Super-Earth.

text: Siena Blaze has the power to fire deadly force blasts of electromagnetic energy. When she fires these blasts, she literally rips apart large sections of the Earth's magnetic field, and causes localized ecological disasters. Siena does not seem to care that using her blasts could destroy the ecosystems of the entire planet. She also can manipulate magnetic fields to inhibit other mutants from teleporting. She can surround herself with an aura of magnetic energy with equal polarity to the Earth's geomagnetic field, causing the Earth to repel her upwards, and enabling her to fly via magnetic levitation. She can also teleport vast distances by turning herself into magnetic energy, and turning back at a desired location.

text: Siena Blaze has the power to fire deadly force blasts of

text: electromagnetic

text: energy. When she fires these blasts, she literally rips apart large sections of the Earth's magnetic field, and causes localized ecological disasters. Siena does not seem to care that using her blasts could destroy the ecosystems of the entire planet. She also can manipulate magnetic fields to inhibit other mutants from

text: teleporting

text: . She can surround herself with an aura of magnetic energy with equal polarity to the Earth's

text: geomagnetic

text: field, causing the Earth to repel her upwards, and enabling her to fly via

text: magnetic levitation

text: . She can also teleport vast distances by turning herself into magnetic energy, and turning back at a desired location.

text: The movie takes place some thirty years after a devastating war between the Union and the Consortium that resulted in the death of 10% of the Earth's population. The Newton 5 space colony is suddenly attacked by a vast extraterrestrial spacecraft, killing 200,000 people in the process. The alien spaceship then proceeds to annihilate a military base on Jupiter's moon Io.  Base commander Noah Trager, aided by recently graduated space cadets, manages to escape to the nearby Magellan research vessel commanded by professor Karteez Rumla. Rumla (encouraged by Senator Jeremy Uvan who was on the military base) insists that the Magellan continue its original classified mission rather than return to Earth. Pursued by the alien spaceship, the refugees head toward section 9 in space—the Magellans original destination—when the research vessel suddenly is ejected into hyperspace by an unknown space phenomenon. After traveling through interstellar space, the vessel is drawn towards an unidentified ice planet where it lands automatically in a crater. The planet has a breathable atmosphere and earth-like gravity, but an unknown force field keeps the Magellan and the 1426 refugees on board trapped on the surface. The planet's orbit is also highly unusual, resembling that of a spacecraft rather than a planet. It is located so far from Earth even the Andromeda galaxy is not visible in the sky. The Magellan is stranded and its crew has to cope with the fact that returning to Earth is impossible.

text: The movie takes place some thirty years after a devastating war between the Union and the Consortium that resulted in the death of 10% of the Earth's population. The Newton 5 space colony is suddenly attacked by a vast extraterrestrial spacecraft, killing 200,000 people in the process. The alien spaceship then proceeds to annihilate a military base on

text: Jupiter

text: 's moon

text: Io

text: .  Base commander Noah Trager, aided by recently graduated space cadets, manages to escape to the nearby Magellan research vessel commanded by professor Karteez Rumla. Rumla (encouraged by Senator Jeremy Uvan who was on the military base) insists that the Magellan continue its original classified mission rather than return to Earth. Pursued by the alien spaceship, the refugees head toward section 9 in space—the Magellans original destination—when the research vessel suddenly is ejected into hyperspace by an unknown space phenomenon. After traveling through interstellar space, the vessel is drawn towards an unidentified

text: ice planet

text: where it lands automatically in a crater. The planet has a breathable atmosphere and earth-like gravity, but an unknown force field keeps the Magellan and the 1426 refugees on board trapped on the surface. The planet's orbit is also highly unusual, resembling that of a spacecraft rather than a planet. It is located so far from Earth even the

text: Andromeda galaxy

text: is not visible in the sky. The Magellan is stranded and its crew has to cope with the fact that returning to Earth is impossible.

text: A synodic day is the period it takes for a planet to rotate once in relation to the body it is orbiting. For Earth, the synodic day is known as a solar day, and is about 24 hours long.

text: A synodic day is the period it takes for a

text: planet

text: to rotate once in relation to the

text: body

text: it is

text: orbit

text: ing. For

text: Earth

text: , the synodic day is known as a

text: solar day

text: , and is about 24 hours long.

text: s seasons 1–5 aired on NBC on Sunday nights at 9pm EST. Season 6 aired on NBC on Tuesday nights at 9pm EST. In October 2007, new episodes of season 7 aired on the USA Network on Thursday nights at 9pm EST. In June 2008 the remaining episodes of the seventh season until the end of the eighth season aired on Sunday nights at 9pm EST on USA. Starting on January 9, 2008, reruns of season 7 began airing on NBC and May 6, 2009, reruns of season 8 began airing on NBC. Criminal Intent's season finale aired August 9, 2009. June 20, 2010, reruns of season 9 began airing on Sunday nights on NBC. The show moved to Tuesday nights at 10pm EST on USA as of the ninth season which premiered on March 30, 2010 and ended July 6, 2010. The show returned to Sunday nights at 9pm EST on USA for the tenth and final season when it premiered May 1, 2011.

text: s seasons 1–5 aired on NBC on Sunday nights at 9pm

text: EST

text: . Season 6 aired on NBC on Tuesday nights at 9pm EST. In October 2007, new episodes of season 7 aired on the USA Network on Thursday nights at 9pm EST. In June 2008 the remaining episodes of the seventh season until the end of the eighth season aired on Sunday nights at 9pm EST on USA. Starting on January 9, 2008, reruns of season 7 began airing on NBC and May 6, 2009, reruns of season 8 began airing on NBC. Criminal Intent's season finale aired August 9, 2009. June 20, 2010, reruns of season 9 began airing on Sunday nights on NBC. The show moved to Tuesday nights at 10pm EST on USA as of the ninth season which premiered on March 30, 2010 and ended July 6, 2010. The show returned to Sunday nights at 9pm EST on USA for the tenth and final season when it premiered May 1, 2011.

text: Most nebulae are of vast size, even millions of light years in diameter.  Contrary to fictional depictions where starships hide in nebulae as thick as cloud banks, in reality a nebula that is barely visible to the human eye from Earth would appear larger, but no brighter, from close by.  The Orion Nebula, the brightest nebula in the sky that occupies a region twice the diameter of the full Moon, can be viewed with the naked eye but was missed by early astronomers.  Although denser than the space surrounding them, most nebulae are far less dense than any vacuum created on Earth – a nebular cloud the size of the Earth would have a total mass of only a few kilograms. Many nebulae are visible due to their fluorescence caused by the embedded hot stars, while others are so diffuse they can only be detected with long exposures and special filters. Some nebulae are variably illuminated by T Tauri variable stars. Nebulae are often star-forming regions, such as in the "Pillars of Creation" in the Eagle Nebula. In these regions the formations of gas, dust, and other materials "clump" together to form denser regions, which attract further matter, and eventually will become dense enough to form stars. The remaining material is then believed to form planets and other planetary system objects.

text: Most nebulae are of vast size, even millions of

text: light year

text: s in diameter.  Contrary to fictional depictions where starships hide in nebulae as thick as cloud banks, in reality a nebula that is barely visible to the human eye from Earth would appear larger, but no brighter, from close by.  The

text: Orion Nebula

text: , the brightest nebula in the sky that occupies a region twice the diameter of the full Moon, can be viewed with the naked eye but was missed by early astronomers.  Although denser than the space surrounding them, most nebulae are far less dense than any

text: vacuum

text: created on Earth – a nebular cloud the size of the

text: Earth

text: would have a total mass of only a few

text: kilogram

text: s. Many nebulae are visible due to their fluorescence caused by the embedded hot stars, while others are so diffuse they can only be detected with long exposures and special filters. Some nebulae are variably illuminated by

text: T Tauri

text: variable stars. Nebulae are often star-forming regions, such as in the "

text: Pillars of Creation

text: " in the

text: Eagle Nebula

text: . In these regions the formations of gas, dust, and other materials "clump" together to form denser regions, which attract further matter, and eventually will become dense enough to form

text: star

text: s. The remaining material is then believed to form

text: planet

text: s and other

text: planetary system

text: objects.

text: They visit a high gravity planet they encounter many insect-like aliens who have adapted to 1.5 times Earth's gravity. High gravity means thicker atmosphere and easier flight.

text: They visit a high gravity planet they encounter many

text: insect

text: -like

text: aliens

text: who have adapted to 1.5 times Earth's

text: gravity

text: . High gravity means thicker

text: atmosphere

text: and easier flight.

text: On an equinox, day and night are of approximately equal duration all over the planet. They are not exactly equal, however, due to the angular size of the sun and atmospheric refraction. To avoid this ambiguity, the word equilux is sometimes used to mean a day in which the durations of light and darkness are equal. See Length of equinoctial day and night for further discussion.

text: On an equinox, day and night are of approximately equal duration all over the planet. They are not exactly equal, however, due to the angular size of the sun and atmospheric refraction. To avoid this ambiguity, the word equilux is sometimes used to mean a day in which the durations of light and darkness are equal. See

text: Length of equinoctial day and night

text: for further discussion.

text: According to the descriptions of the Book of Genesis (which was one of the main sources of Beatus), the Earth was thought to be plane and to sustain the vault of heaven, where the Sun, the Moon, and many other minor luminaries like planets and stars, moved. There were two sorts of water masses: The waters above the firmament, which were contained by the vault of heaven and occasionally fell to Earth in form of rain, when the floodgates opened, and the waters below, which nurtured the rivers, the streams and the great salt water masses.

text: According to the descriptions of the

text: Book of Genesis

text: (which was one of the main sources of Beatus), the Earth was thought to be plane and to sustain the vault of heaven, where the Sun, the Moon, and many other minor

text: luminaries

text: like planets and stars, moved. There were two sorts of water masses: The waters above the firmament, which were contained by the vault of heaven and occasionally fell to Earth in form of rain, when the floodgates opened, and the waters below, which nurtured the rivers, the streams and the great salt water masses.

text: Geta is a harsh planet settled by humanity centuries before the novel begins.  The planet has one large satellite, Scowlmoon; the two are in a mutual tidal lock, so the moon is only visible from half the planet. The planet's day is about half as long as Earth's.  Geta is much drier than Earth, with eleven separate bodies of water large enough to be called seas; most of the land area is desert.

text: Geta is a harsh planet settled by humanity centuries before the novel begins.  The planet has one large satellite, Scowlmoon; the two are in a mutual

text: tidal lock

text: , so the moon is only visible from half the planet. The planet's day is about half as long as Earth's.  Geta is much drier than Earth, with eleven separate bodies of water large enough to be called seas; most of the land area is desert.

text: The Nexus includes a variety of ecologies. Some planets, such as Barrayar and Sergyar, have gravity and atmosphere similar to Earth’s, and supplies of water. Others, such as Beta Colony and Komarr, can only be inhabited by people if they are gathered in cities under domes or arcologies with a controlled climate. Human life requires Earth-based botanical life, and Bujold devotes a good deal of attention in some novels to this. Most inhabited planets undergo terraforming, that is, the destruction of native plant and animal life and the imposition of Earth-based forms. In Komarr, we learn that terraforming may eventually provide a breathable atmosphere outside the domed cities. In A Civil Campaign, the possibility of genetically engineered animals which can eat native vegetation and produce manure suitable for Earth vegetation is welcomed by the vice-regents of the newly colonized planet Sergyar.

text: The Nexus includes a variety of ecologies. Some planets, such as Barrayar and Sergyar, have gravity and atmosphere similar to Earth’s, and supplies of water. Others, such as Beta Colony and Komarr, can only be inhabited by people if they are gathered in cities under domes or

text: arcologies

text: with a controlled climate. Human life requires Earth-based botanical life, and Bujold devotes a good deal of attention in some novels to this. Most inhabited planets undergo

text: terraforming

text: , that is, the destruction of native plant and animal life and the imposition of Earth-based forms. In Komarr, we learn that terraforming may eventually provide a breathable atmosphere outside the domed cities. In A Civil Campaign, the possibility of genetically engineered animals which can eat native vegetation and produce manure suitable for Earth vegetation is welcomed by the vice-regents of the newly colonized planet Sergyar.

text: The International Astronomical Union (IAU) defines the geographic north pole of a planet or any of its satellites in the Solar System as the planetary pole that is in the same celestial hemisphere relative to the invariable plane of the Solar System as Earth's North pole. This definition means that an object's direction of rotation may be negative (retrograde rotation) — in other words, it rotates clockwise when viewed from above its north pole, rather than the "normal" counterclockwise direction exhibited by Earth's north pole. Venus rotates in the opposite direction to the other planets, and Uranus has been knocked on its side and rotates almost perpendicular to the rest of the Solar System. The ecliptic remains within 3° of the invariable plane over five million years, but is now inclined about 23.44° to Earth's celestial equator used for the coordinates of poles. This large inclination means that the declination of a pole relative to Earth's celestial equator could be negative even though a planet's north pole (such as Uranus) is north of the invariable plane.

text: The

text: International Astronomical Union

text: (IAU) defines the

text: geographic north pole

text: of a

text: planet

text: or any of its satellites in the

text: Solar System

text: as the planetary pole that is in the same celestial hemisphere relative to the

text: invariable plane

text: of the Solar System as Earth's North pole. This definition means that an object's direction of rotation may be negative (

text: retrograde

text: rotation) — in other words, it rotates clockwise when viewed from above its north pole, rather than the "normal" counterclockwise direction exhibited by Earth's north pole.

text: Venus

text: rotates in the opposite direction to the other planets, and

text: Uranus

text: has been knocked on its side and rotates almost perpendicular to the rest of the Solar System. The

text: ecliptic

text: remains within 3° of the invariable plane over five million years, but is now inclined about 23.44° to Earth's

text: celestial equator

text: used for the coordinates of poles. This large inclination means that the declination of a pole relative to Earth's celestial equator could be negative even though a planet's north pole (such as Uranus) is north of the invariable plane.

text: A planetarium will show the orbital period of each planet and the rotation rate, as shown in the table above. A tellurion will show the earth with the moon revolving around the sun. It will use the angle of inclination of the equator from the table above to show how it rotates around its own axis. It will show the earth's moon, rotating around the earth. A lunarium is designed to show the complex motions of the moon as it revolves around the earth.

text: A planetarium will show the orbital period of each planet and the rotation rate, as shown in the table above. A tellurion will show the

text: earth with the moon

text: revolving around the sun. It will use the angle of inclination of the equator from the table above to show how it rotates around its own axis. It will show the earth's moon, rotating around the earth. A lunarium is designed to show the

text: complex motions of the moon

text: as it revolves around the earth.

text: The star rotates at an inclination of 8 degrees relative to Earth.  It is probable that this planet shares that inclination.

text: Similarly, while the orbital speed of an outer planet is less than that of the Earth, a spacecraft leaving the Earth at the minimum speed needed to travel to some outer planet is slowed by the Sun's gravity to a speed far less than the orbital speed of that outer planet. Thus, there must be some way to accelerate the spacecraft when it reaches that outer planet if it is to enter orbit about it. However, if the spacecraft is accelerated to more than the minimum required, less total propellant will be needed to enter orbit about the target planet. In addition, accelerating the spacecraft early in the flight will reduce the travel time.

text: The ancient Greeks initially did not attach as much significance to the planets as the Babylonians. The Pythagoreans, in the 6th and 5th centuries BC appear to have developed their own independent planetary theory, which consisted of the Earth, Sun, Moon, and planets revolving around a "Central Fire" at the center of the Universe. Pythagoras or Parmenides is said to have been the first to identify the evening star (Hesperos) and morning star (Phosphoros) as one and the same (Aphrodite, Greek corresponding to Latin Venus). In the 3rd century BC, Aristarchus of Samos proposed a heliocentric system, according to which Earth and the planets revolved around the Sun. The geocentric system remained dominant until the Scientific Revolution.

text: The ancient Greeks initially did not attach as much significance to the planets as the Babylonians. The

text: Pythagoreans

text: , in the 6th and 5th centuries BC appear to have developed their own independent planetary theory, which consisted of the Earth, Sun, Moon, and planets revolving around a "Central Fire" at the center of the Universe.

text: Pythagoras

text: or

text: Parmenides

text: is said to have been the first to identify the evening star (

text: Hesperos

text: ) and morning star (

text: Phosphoros

text: ) as one and the same (

text: Aphrodite

text: , Greek corresponding to Latin

text: Venus

text: ). In the 3rd century BC,

text: Aristarchus of Samos

text: proposed a

text: heliocentric

text: system, according to which Earth and the planets revolved around the Sun. The geocentric system remained dominant until the

text: Scientific Revolution

text: Arriving at the very end of the final episode of season 2, Volm are a race which claim to have been at war with the Espheni for longer than most Volm have been alive.  The Espheni took their planet long ago.  In Season 3, the Volm set up a base by Charleston, South Carolina, and are building a weapon to take down the Espheni defense grid for reinforcements to fight the Espheni. They succeed in taking down the defense grid by destroying the mothership in Boston and Volm reinforcements arrive led by the father of Cochise, the humans' main Volm ally. The Volm force the Espheni into retreating to the northern areas of the planet and plan to force the humans into safety in camps in Brazil, but Tom Mason is able to convince the Volm leader to let them stay and fight which the Volm never allow on planets they help. In Season 4 the greater Volm forces leave Earth to engage the Espheni who in the meantime attacked their young and brood mates. Its later revealed that the Volm gave up on Earth after the attack on their young and the devastating counterattack on humanity, but Cochise, the Volm leader who had aided the humans since the end of season 2, refuses to give up and remains behind on Earth with a small group of soldiers to continue the fight. During the attack on the Espheni power core at the end of season 4, the Volm mothership returns in time to aid in the destruction of the power core by destroying an attacking Beamer squadron. However, the Volm are not able to find Tom Mason's Beamer after it is blown into deep space. Tom is eventually rescued by the Dornia and continues working with Cochise and his men to fight the now-weakened Espheni. While Cochise nearly dies due to a failing organ, his father saves him with an organ transplant at the cost of his own life as he believes that Cochise's survival is more important to the Volm battle plan than his own. Cochise aids the human resistance in their war with the Espheni and takes part in the assault on Washington, D.C.. The Espheni are destroyed by Tom Mason in the series finalie Reborn with a Dornia bioweapon and the Volm war with them ends. A Volm delegation, including Cochise attends a united humanity's gathering to choose a new leader months after the invasion ends.

text: Arriving at the very end of the final episode of season 2, Volm are a race which claim to have been at war with the Espheni for longer than most Volm have been alive.  The Espheni took their planet long ago.  In Season 3, the Volm set up a base by Charleston, South Carolina, and are building a weapon to take down the Espheni defense grid for reinforcements to fight the Espheni. They succeed in taking down the defense grid by destroying the mothership in Boston and Volm reinforcements arrive led by the father of Cochise, the humans' main Volm ally. The Volm force the Espheni into retreating to the northern areas of the planet and plan to force the humans into safety in camps in

text: Brazil

text: , but Tom Mason is able to convince the Volm leader to let them stay and fight which the Volm never allow on planets they help. In Season 4 the greater Volm forces leave Earth to engage the Espheni who in the meantime attacked their young and brood mates. Its later revealed that the Volm gave up on Earth after the attack on their young and the devastating counterattack on humanity, but Cochise, the Volm leader who had aided the humans since the end of season 2, refuses to give up and remains behind on Earth with a small group of soldiers to continue the fight. During the attack on the Espheni power core at the end of season 4, the Volm mothership returns in time to aid in the destruction of the power core by destroying an attacking Beamer squadron. However, the Volm are not able to find Tom Mason's Beamer after it is blown into deep space. Tom is eventually rescued by the Dornia and continues working with Cochise and his men to fight the now-weakened Espheni. While Cochise nearly dies due to a failing organ, his father saves him with an organ transplant at the cost of his own life as he believes that Cochise's survival is more important to the Volm battle plan than his own. Cochise aids the human resistance in their war with the Espheni and takes part in the assault on

text: Washington, D.C.

text: . The Espheni are destroyed by Tom Mason in the series finalie Reborn with a Dornia

text: bioweapon

text: and the Volm war with them ends. A Volm delegation, including Cochise attends a united humanity's gathering to choose a new leader months after the invasion ends.

text: There are 7 different elements in the game (light, darkness, fire, water, wood, earth, and wind) which each correspond to a planet in the game's solar system. The Astrolog tracks the movement of these planets, which move clockwise around a central point as time passes within the game. The orbital velocity of each planet varies according to their size and location. Magic spells of certain elements are twice as effective while a planet is orbiting within the area assigned to its corresponding element. This bonus applies for both the player's magic spells and enemy spells. The light and dark elements are instead affected by solar activity: light magic is more powerful during the daytime, and dark magic is more powerful during the night (in-game time is viewable as an animated hourglass). A certain spell acquired later in the game allows the player to move the planets to an advantageous position; or potentially align the 5 planets in a straight line (as indicated in the Japanese version's subtitle), which causes far more damage than the standard elemental bonus. The planets may also happen to align without using the spell, but this causes damage to both the player and the enemy.

text: For Earth satellite orbital parameters, the mean motion is typically measured in revolutions per day. In that case,

text: For Earth satellite orbital parameters, the mean motion is typically measured in revolutions per

text: day

text: . In that case,

text: Earth science – all-embracing term for the sciences related to the planet Earth. It is also known as geoscience, the geosciences or the Earth sciences, and is arguably a special case in planetary science, the Earth being the only known life-bearing planet.

text: Earth science

text: – all-embracing term for the

text: science

text: s related to the

text: planet

text: Earth

text: . It is also known as geoscience, the geosciences or the Earth sciences, and is arguably a special case in

text: planetary science

text: , the Earth being the only known

text: life

text: -bearing planet.

text: The Mars Global Surveyor (MGS) discovered magnetic stripes in the crust of Mars, especially in the Phaethontis and Eridania quadrangles  (Terra Cimmeria and Terra Sirenum). The magnetometer on MGS discovered 100 km wide stripes of magnetized crust running roughly parallel for up to 2000 km. These stripes alternate in polarity with the north magnetic pole of one pointing up from the surface and the north magnetic pole of the next pointing down. When similar stripes were discovered on Earth in the 1960s, they were taken as evidence of plate tectonics.  Researchers believe these magnetic stripes on Mars are evidence for a short, early period of plate tectonic activity.  When the rocks became solid they retained the magnetism that existed at the time.  A magnetic field of a planet is believed to be caused by fluid motions under the surface. However, there are some differences, between the magnetic stripes on Earth and those on Mars. The Martian stripes are wider, much more strongly magnetized, and do not appear to spread out from a middle crustal spreading zone. Because the area containing the magnetic stripes is about 4 billion years old, it is believed that the global magnetic field probably lasted for only the first few hundred million years of Mars' life, when the temperature of the molten iron in the planet's core might have been high enough to mix it into a magnetic dynamo.  There are no magnetic fields near large impact basins like Hellas.  The shock of the impact may have erased the remnant magnetization in the rock.  So, magnetism produced by early fluid motion in the core would not have existed after the impacts.

text: The

text: Mars Global Surveyor

text: (MGS) discovered magnetic stripes in the crust of Mars, especially in the Phaethontis and

text: Eridania quadrangle

text: s  (

text: Terra Cimmeria

text: and Terra Sirenum). The magnetometer on MGS discovered 100 km wide stripes of magnetized crust running roughly parallel for up to 2000 km. These stripes alternate in polarity with the north magnetic pole of one pointing up from the surface and the north magnetic pole of the next pointing down. When similar stripes were discovered on Earth in the 1960s, they were taken as evidence of

text: plate tectonics

text: .  Researchers believe these magnetic stripes on Mars are evidence for a short, early period of plate tectonic activity.  When the rocks became solid they retained the magnetism that existed at the time.  A magnetic field of a planet is believed to be caused by fluid motions under the surface. However, there are some differences, between the magnetic stripes on Earth and those on Mars. The Martian stripes are wider, much more strongly magnetized, and do not appear to spread out from a middle crustal spreading zone. Because the area containing the magnetic stripes is about 4 billion years old, it is believed that the global magnetic field probably lasted for only the first few hundred million years of Mars' life, when the temperature of the molten iron in the planet's core might have been high enough to mix it into a magnetic dynamo.  There are no magnetic fields near large impact basins like Hellas.  The shock of the impact may have erased the remnant magnetization in the rock.  So, magnetism produced by early fluid motion in the core would not have existed after the impacts.

text: An area of active discussion in the Maragheh school, and later the Samarkand and Istanbul observatories, was the possibility of the Earth's rotation. Supporters of this theory included Nasīr al-Dīn al-Tūsī, Nizam al-Din al-Nisaburi (c. 1311), al-Sayyid al-Sharif al-Jurjani (1339–1413), Ali Qushji (d. 1474), and Abd al-Ali al-Birjandi (d. 1525). Al-Tusi was the first to present empirical observational evidence of the Earth's rotation, using the location of comets relevant to the Earth as evidence, which Qushji elaborated on with further empirical observations while rejecting Aristotelian natural philosophy altogether. Both of their arguments were similar to the arguments later used by Nicolaus Copernicus in 1543 to explain the Earth's rotation (see Astronomical physics and Earth's motion section below).

text: An area of active discussion in the Maragheh school, and later the

text: Samarkand

text: and

text: Istanbul

text: observatories, was the possibility of the

text: Earth's rotation

text: . Supporters of this theory included

text: Nasīr al-Dīn al-Tūsī

text: , Nizam al-Din al-Nisaburi (c. 1311), al-Sayyid al-Sharif al-Jurjani (1339–1413), Ali Qushji (d. 1474), and Abd al-Ali

text: al-Birjandi

text: (d. 1525). Al-Tusi was the first to present empirical observational evidence of the Earth's rotation, using the location of

text: comet

text: s relevant to the Earth as evidence, which Qushji elaborated on with further empirical observations while rejecting Aristotelian

text: natural philosophy

text: altogether. Both of their arguments were similar to the arguments later used by

text: Nicolaus Copernicus

text: in 1543 to explain the Earth's rotation (see

text: Astronomical physics and Earth's motion

text: section below).

text: The probability of finding an Earth analog depends mostly on the attributes that are expected to be similar, and these vary greatly. Generally it is considered that it would be a terrestrial planet and there have been several scientific studies aimed at finding such planets. Often implied but not limited to are such criteria as planet size, surface gravity, star size and type (i.e. Solar analog), orbital distance and stability, axial tilt and rotation, similar geography, oceans, air and weather conditions, strong magnetosphere and even the presence of Earth-like complex life. If there is complex life, there could be some forests covering much of the land. If there is intelligent life, some parts of land could be covered in cities. Some factors that are assumed of such a planet may be unlikely due to Earth's own history. For instance the Earth's atmosphere was not always oxygen-rich and this is a biosignature from the emergence of photosynthetic life. The formation, presence, influence on these characteristics of the Moon (such as tidal forces) may also pose a problem in finding an Earth analog.

text: The probability of finding an Earth analog depends mostly on the attributes that are expected to be similar, and these vary greatly. Generally it is considered that it would be a

text: terrestrial planet

text: and there have been several scientific studies aimed at finding such planets. Often implied but not limited to are such criteria as planet size, surface gravity, star size and type (i.e.

text: Solar analog

text: ), orbital distance and stability, axial tilt and rotation, similar

text: geography

text: ocean

text: s,

text: air

text: and

text: weather

text: conditions, strong

text: magnetosphere

text: and even the presence of Earth-like complex

text: life

text: . If there is complex life, there could be some

text: forest

text: s covering much of the land. If there is intelligent life, some parts of land could be covered in

text: cities

text: . Some factors that are assumed of such a planet may be unlikely due to Earth's own history. For instance the Earth's atmosphere was not always oxygen-rich and this is a

text: biosignature

text: from the emergence of

text: photosynthetic

text: life. The formation, presence, influence on these characteristics of the

text: Moon

text: (such as

text: tidal forces

text: ) may also pose a problem in finding an Earth analog.

text: In theory, it is possible for a magnetic sail to launch directly from the surface of a planet near one of its magnetic poles, repelling itself from the planet's magnetic field. However, this requires the magnetic sail to be maintained in its "unstable" orientation.  A launch from Earth requires superconductors with 80 times the current density of the best known high-temperature superconductors.

text: The Year’s research themes are: Groundwater: reservoir for a thirsty planet?; Hazards: minimizing risk, maximizing awareness; Earth and Health: building a safer environment; Climate change: the ‘stone tape’; Resource Issues: towards sustainable use; Megacities: going deeper, building safer; Deep Earth: from crust to core; Ocean: abyss of time; Soil: Earth’s living skin; Earth and Life: origins of diversity. Each is described within an accessibly-written prospectus available on the Web site. In addition, Planet Earth in our Hands, states the rationale for the Year, and Outreach: bringing Earth sciences to everyone, describes how the Outreach programme will work.  All these can be downloaded from www.yearofplanetearth.org

text: The Year’s research themes are:

text: Groundwater

text: : reservoir for a thirsty planet?;

text: Hazard

text: s: minimizing risk, maximizing awareness; Earth and

text: Health

text: : building a safer environment;

text: Climate change

text: : the ‘stone tape’;

text: Resource

text: Issues: towards sustainable use;

text: Megacities

text: : going deeper, building safer; Deep

text: Earth

text: : from

text: crust

text: to

text: core

text: Ocean

text: : abyss of time;

text: Soil

text: : Earth’s living skin; Earth and

text: Life

text: : origins of diversity. Each is described within an accessibly-written prospectus available on the Web site. In addition, Planet Earth in our Hands, states the rationale for the Year, and Outreach: bringing

text: Earth sciences

text: to everyone, describes how the Outreach programme will work.  All these can be downloaded from www.yearofplanetearth.org

text: HD 40307 c is the third-most massive planet in the system, with a lower mass bound 6.8 times the mass of the Earth. The planet orbits HD 40307 at about 0.08 astronomical units (AU), as compared to the Earth's distance from the Sun at 1 AU; as a result, one year on the planet constitutes approximately 9.6 Earth days. Analysis of the radial velocity data used to detect the planet does not yield a statistically significant deviation from a circular orbit.

text: HD 40307 c is the third-most massive planet in the system, with a lower mass bound 6.8 times the mass of the Earth. The planet orbits HD 40307 at about 0.08

text: astronomical unit

text: s (AU), as compared to the

text: Earth

text: 's distance from the

text: Sun

text: at 1 AU; as a result, one year on the planet constitutes approximately 9.6 Earth days. Analysis of the radial velocity data used to detect the planet does not yield a statistically significant deviation from a circular orbit.

text: A sub-Earth  is a planet "substantially less massive" than Earth and Venus. In the Solar System, this category includes Mercury and Mars. Sub-Earth exoplanets are among the most difficult type to detect because their small sizes and masses produce the weakest signal. Despite the difficulty, one of the first exoplanets found was a sub-Earth around a millisecond pulsar PSR B1257+12.

text: A sub-Earth  is a

text: planet

text: "substantially less massive" than

text: Earth

text: and

text: Venus

text: . In the

text: Solar System

text: , this category includes

text: Mercury

text: and

text: Mars

text: . Sub-Earth

text: exoplanet

text: s are among the most difficult type to detect because their small sizes and masses produce the weakest signal. Despite the difficulty, one of the first

text: exoplanet

text: s found was a sub-Earth around a

text: millisecond pulsar

text: PSR B1257+12

text: A planet around either α Centauri A or B would see the other star as a very bright secondary. For example, an Earth-like planet at 1.25 astronomical units from α Cen A (with a revolution period of 1.34 years) would get Sun-like illumination from its primary, and α Cen B would appear 5.7 to 8.6 magnitudes dimmer (−21.0 to −18.2), 190 to 2,700 times dimmer than α Cen A but still 150 to 2,100 times brighter than the full Moon. Conversely, an Earth-like planet at 0.71 AU from α Cen B (with a revolution period of 0.63 years) would get Sun-like illumination from its primary, and α Cen A would appear 4.6 to 7.3 magnitudes dimmer (−22.1 to −19.4), 70 to 840 times dimmer than α Cen B but still 470 to 5,700 times brighter than the full Moon. In both cases the secondary sun would, in the course of the planet's year, appear to circle the sky. It would start off right beside the primary and end up, half a period later, opposite it in the sky (at "full"). After another half period, it would complete the cycle. Other planets orbiting one member of a binary system would enjoy similar skies. The angular separation between the two stars would not be exactly the same after one orbit of the planet however, because during that time the parent star will have completed part of its orbit around the other star in the system.

text: A planet around either α Centauri A or B would see the other star as a very bright secondary. For example, an Earth-like planet at 1.25

text: astronomical unit

text: s from α Cen A (with a revolution period of 1.34 years) would get Sun-like illumination from its primary, and α Cen B would appear 5.7 to 8.6 magnitudes dimmer (−21.0 to −18.2), 190 to 2,700 times dimmer than α Cen A but still 150 to 2,100 times brighter than the full Moon. Conversely, an Earth-like planet at 0.71 AU from α Cen B (with a revolution period of 0.63 years) would get Sun-like illumination from its primary, and α Cen A would appear 4.6 to 7.3 magnitudes dimmer (−22.1 to −19.4), 70 to 840 times dimmer than α Cen B but still 470 to 5,700 times brighter than the full Moon. In both cases the secondary sun would, in the course of the planet's year, appear to circle the sky. It would start off right beside the primary and end up, half a period later, opposite it in the sky (at "full"). After another half period, it would complete the cycle. Other planets orbiting one member of a binary system would enjoy similar skies. The angular separation between the two stars would not be exactly the same after one orbit of the planet however, because during that time the parent star will have completed part of its orbit around the other star in the system.

text: Mercury's magnetic field is strong enough to deflect the solar wind around the planet, creating a magnetosphere. The planet's magnetosphere, though small enough to fit within Earth, is strong enough to trap solar wind plasma. This contributes to the space weathering of the planet's surface. Observations taken by the  spacecraft detected this low energy plasma in the magnetosphere of the planet's nightside.  Bursts of energetic particles in the planet's magnetotail indicate a dynamic quality to the planet's magnetosphere.

text: Mercury's magnetic field is strong enough to deflect the

text: solar wind

text: around the planet, creating a

text: magnetosphere

text: . The planet's magnetosphere, though small enough to fit within Earth, is strong enough to trap solar wind

text: plasma

text: . This contributes to the

text: space weathering

text: of the planet's surface. Observations taken by the  spacecraft detected this low energy plasma in the magnetosphere of the planet's nightside.  Bursts of energetic particles in the planet's magnetotail indicate a dynamic quality to the planet's magnetosphere.

text: The main goal of CHEOPS will be to accurately measure the radii of the exoplanets for which ground-based spectroscopic surveys have already provided mass estimates. Knowing both the mass and the size of the exoplanets will allow scientists to determine the planets' approximate composition, such as whether they are gaseous or rocky. CHEOPS will be the most efficient instrument to search for shallow transits and to determine accurate radii for known exoplanets in the super-Earth to Neptune mass range (1-6 Earth radius).

text: The main goal of CHEOPS will be to accurately measure the radii of the exoplanets for which ground-based spectroscopic surveys have already provided mass estimates. Knowing both the mass and the size of the exoplanets will allow scientists to determine the planets' approximate composition, such as whether they are gaseous or

text: rocky

text: . CHEOPS will be the most efficient instrument to search for shallow transits and to determine accurate radii for known exoplanets in the

text: super-Earth

text: to Neptune mass range (1-6 Earth radius).

text: Kepler-19b is a planet orbiting around the star Kepler-19. The planet has an orbital period of 9.3 days, with an estimated radius of roughly 2.2 Earth radii, and mass less than 20.3 Earth masses. It is one of two planets orbiting Kepler 19.

text: Kepler-19b is a planet orbiting around the star

text: . The planet has an orbital period of 9.3 days, with an estimated radius of roughly 2.2 Earth radii, and mass less than 20.3 Earth masses. It is one of two planets orbiting Kepler 19.

text: A sizeable quantity of water would have been in the material that formed the Earth. Water molecules would have escaped Earth's gravity more easily when it was less massive during its formation. Hydrogen and helium are expected to continually escape (even to the present day) due to atmospheric escape.Part of the ancient planet is theorized to have been disrupted by the impact that created the Moon, which should have caused melting of one or two large areas.  Earth's present composition suggests that there was not complete remelting as it is difficult to completely melt and mix huge rock masses. However, a fair fraction of material should have been vaporized by this impact, creating a rock vapor atmosphere around the young planet. The rock vapor would have condensed within two thousand years, leaving behind hot volatiles which probably resulted in a heavy  atmosphere with hydrogen and water vapor. Liquid water oceans existed despite the surface temperature of  because at an atmospheric pressure of above 27 atmospheres, caused by the heavy  atmosphere, water is still liquid. As cooling continued, subduction and dissolving in ocean water removed most  from the atmosphere but levels oscillated wildly as new surface and mantle cycles appeared.

text: A sizeable quantity of

text: water

text: would have been in the material that formed the Earth. Water molecules would have escaped Earth's gravity more easily when it was less massive during its formation. Hydrogen and helium are expected to continually escape (even to the present day) due to

text: atmospheric escape

text: .Part of the ancient planet is theorized to have been disrupted by the

text: impact that created the Moon

text: , which should have caused melting of one or two large areas.  Earth's present composition suggests that there was not complete remelting as it is difficult to completely melt and mix huge rock masses. However, a fair fraction of material should have been vaporized by this impact, creating a rock vapor atmosphere around the young planet. The rock vapor would have condensed within two thousand years, leaving behind hot volatiles which probably resulted in a heavy  atmosphere with

text: hydrogen

text: and

text: water vapor

text: . Liquid water oceans existed despite the surface temperature of  because at an atmospheric pressure of above 27 atmospheres, caused by the heavy  atmosphere, water is still liquid. As cooling continued, subduction and dissolving in ocean water removed most  from the atmosphere but levels oscillated wildly as new surface and mantle cycles appeared.

text: The bulk of Jupiter's magnetic field, like Earth's, is generated by an internal dynamo supported by the circulation of a conducting fluid in its outer core. But whereas Earth's core is made of molten iron and nickel, Jupiter's is composed of metallic hydrogen. As with Earth's, Jupiter's magnetic field is mostly a dipole, with north and south magnetic poles at the ends of a single magnetic axis. However, on Jupiter the north pole of the dipole is located in the planet's northern hemisphere and the south pole of the dipole lies in its southern hemisphere, opposite to the Earth, whose north pole lies in the southern hemisphere and south pole lies in the northern hemisphere. Jupiter's field also has quadrupole, octupole and higher components, though they are less than one tenth as strong as the dipole component.

text: The bulk of Jupiter's magnetic field, like

text: Earth

text: 's, is generated by an internal

text: dynamo

text: supported by the circulation of a conducting fluid in its

text: outer core

text: . But whereas Earth's core is made of molten

text: iron

text: and

text: nickel

text: , Jupiter's is composed of

text: metallic hydrogen

text: . As with Earth's, Jupiter's magnetic field is mostly a

text: dipole

text: , with north and south magnetic poles at the ends of a single magnetic axis. However, on Jupiter the north pole of the dipole is located in the planet's northern hemisphere and the south pole of the dipole lies in its southern hemisphere, opposite to the Earth, whose north pole lies in the southern hemisphere and south pole lies in the northern hemisphere. Jupiter's field also has

text: quadrupole

text: octupole

text: and higher components, though they are less than one tenth as strong as the dipole component.

text:
Season 1, Episode 1: Roads
Season 1, Episode 2: Rubber
Season 1, Episode 3: Explosives
Season 1, Episode 4: Coal
Season 1, Episode 5: Trucks
Season 1, Episode 6: Oil Rigs
Season 1, Episode 7: Glass
Season 1, Episode 8: Paint
Season 1, Episode 9: Packaging
Season 1, Episode 10: Steel

text: Because of a planet's rotation around its own axis, the gravitational acceleration is less at the equator than at the poles. In the 17th century, following the invention of the pendulum clock, French scientists found that clocks sent to French Guiana, on the northern coast of South America, ran slower than their exact counterparts in Paris. Measurements of the acceleration due to gravity at the equator must also take into account the planet's rotation. Any object that is stationary with respect to the surface of the Earth is actually following a circular trajectory, circumnavigating the Earth's axis. Pulling an object into such a circular trajectory requires a force. The acceleration that is required to circumnavigate the Earth's axis along the equator at one revolution per sidereal day is 0.0339 m/s². Providing this acceleration decreases the effective gravitational acceleration. At the equator, the effective gravitational acceleration is 9.7805 m/s. This means that the true gravitational acceleration at the equator must be 9.8144 m/s (9.7805 + 0.0339 = 9.8144).

text: Because of a planet's rotation around its own axis, the gravitational acceleration is less at the equator than at the poles. In the 17th century, following the invention of the

text: pendulum clock

text: , French scientists found that clocks sent to

text: French Guiana

text: , on the northern coast of

text: South America

text: , ran slower than their exact counterparts in Paris. Measurements of the acceleration due to gravity at the equator must also take into account the planet's rotation. Any object that is stationary with respect to the surface of the Earth is actually following a circular trajectory, circumnavigating the Earth's axis. Pulling an object into such a circular trajectory requires a force. The acceleration that is required to circumnavigate the Earth's axis along the equator at one revolution per

text: sidereal day

text: is 0.0339 m/s². Providing this acceleration decreases the effective gravitational acceleration. At the equator, the effective gravitational acceleration is 9.7805 m/s. This means that the true gravitational acceleration at the equator must be 9.8144 m/s (9.7805 + 0.0339 = 9.8144).

text: Tauck has also entered into a partnership with BBC Earth, the award-winning filmmakers behind acclaimed nature documentaries including Life, The Blue Planet, Frozen Planet and Planet Earth. Through the Earth Journeys partnership with BBC Earth, Tauck is enhancing its journeys that explore the natural world by adding a series of original films that Tauck guests will view on location.  Produced by BBC Earth exclusively for Tauck, these brief documentaries utilize BBC Earth’s resources, including its vast archive of nature film footage, to highlight the animal life and places that Tauck guests are experiencing during their travels.

text: Tauck has also entered into a partnership with

text: BBC Earth

text: , the award-winning filmmakers behind acclaimed nature documentaries including

text: Life

text: The Blue Planet

text: Frozen Planet

text: and

text: Planet Earth

text: . Through the Earth Journeys partnership with BBC Earth, Tauck is enhancing its journeys that explore the natural world by adding a series of original films that Tauck guests will view on location.  Produced by BBC Earth exclusively for Tauck, these brief documentaries utilize BBC Earth’s resources, including its vast archive of nature film footage, to highlight the animal life and places that Tauck guests are experiencing during their travels.

text: Planetary magnetic poles are defined analogously to the Earth's North and South magnetic poles: they are the locations on the planet's surface at which the planet's magnetic field lines are vertical. The direction of the field determines whether the pole is a magnetic north or south pole, exactly as on Earth. The Earth's magnetic axis is approximately aligned with its rotational axis, meaning that the magnetic poles are relatively close to the geographic poles. However, this is not necessarily the case for other planets; the magnetic axis of Uranus, for example, is inclined by as much as 60°.

text: Planetary magnetic poles are defined analogously to the Earth's

text: North

text: and

text: South magnetic pole

text: s: they are the locations on the planet's surface at which the planet's

text: magnetic field

text: lines are vertical. The direction of the field determines whether the pole is a magnetic north or south pole, exactly as on Earth. The Earth's magnetic axis is approximately aligned with its rotational axis, meaning that the magnetic poles are relatively close to the geographic poles. However, this is not necessarily the case for other planets; the magnetic axis of

text: Uranus

text: , for example, is inclined by as much as 60°.

text: Magneta is the "Mistress of Magnetism". She was a mutant who idolized Magneto, and used her own magnetic powers to emulate him. She offered J2 the chance to stand by her side against the forces of evil, a force they would attack proactively (as long as he pledged his blind obedience to her). When he refused, she attacked him. However, she ended her battle when J2's team A-Next came to find him. Later, Magneta tried to form a team of female mutants. Magneta stated that she wished to form the greatest team of heroes in the world. Magneta possesses the power to generate and manipulate magnetic fields, and ability that enables her to move, levitate, and reshape ferrous metals without any physical contact. Magneta can focus her magnetic energies into blasts of pure force. She can also fly via magnetic levitation, by generating a magnetic field of equal polarity to the Earth's geomagnetic field, causing the planet itself to repel her upwards

text: Magneta is the "Mistress of Magnetism". She was a

text: mutant

text: who idolized

text: Magneto

text: , and used her own

text: magnetic

text: powers to emulate him. She offered J2 the chance to stand by her side against the forces of evil, a force they would attack proactively (as long as he pledged his blind obedience to her). When he refused, she attacked him. However, she ended her battle when J2's team

text: A-Next

text: came to find him. Later, Magneta tried to form a team of female mutants. Magneta stated that she wished to form the greatest team of heroes in the world. Magneta possesses the power to generate and manipulate magnetic fields, and ability that enables her to move, levitate, and reshape ferrous metals without any physical contact. Magneta can focus her magnetic energies into blasts of pure force. She can also fly via

text: magnetic levitation

text: , by generating a magnetic field of equal polarity to the Earth's

text: geomagnetic

text: field, causing the planet itself to repel her upwards

text: Pluto's rotation period, its day, is equal to 6.39 Earth days. Like Uranus, Pluto rotates on its "side" in its orbital plane, with an axial tilt of 120°, and so its seasonal variation is extreme; at its solstices, one-fourth of its surface is in continuous daylight, whereas another fourth is in continuous darkness. The reason for this unusual orientation has been debated. Research from University of Arizona has suggested that it may be due to the way that a body's spin will always adjust to minimise energy. This could mean a body reorienting itself to put extraneous mass near the equator and regions lacking mass tend towards the poles. This is called polar wander. According to a paper released from the University of Arizona, this could be caused by masses of frozen nitrogen building up in shadowed areas of the dwarf planet. These masses would cause the body to reorientate itself, leading to its unusual axial tilt of 120°. The buildup of Nitrogen is due to Pluto's vast distance from the Sun. At the equator, temperatures can drop to , causing nitrogen to freeze as water would freeze on Earth. The same effect seen on Pluto would be observed on Earth if the Antarctic ice sheet was several times larger.

text: Pluto's

text: rotation period

text: , its day, is equal to 6.39

text: Earth

text: days. Like

text: Uranus

text: , Pluto rotates on its "side" in its orbital plane, with an axial tilt of 120°, and so its seasonal variation is extreme; at its

text: solstice

text: s, one-fourth of its surface is in continuous daylight, whereas another fourth is in continuous darkness. The reason for this unusual orientation has been debated. Research from

text: University of Arizona

text: has suggested that it may be due to the way that a body's spin will always adjust to minimise energy. This could mean a body reorienting itself to put extraneous mass near the equator and regions lacking mass tend towards the poles. This is called

text: polar wander

text: . According to a paper released from the University of Arizona, this could be caused by masses of frozen nitrogen building up in shadowed areas of the dwarf planet. These masses would cause the body to reorientate itself, leading to its unusual axial tilt of 120°. The buildup of Nitrogen is due to Pluto's vast distance from the Sun. At the equator, temperatures can drop to , causing nitrogen to freeze as water would freeze on Earth. The same effect seen on Pluto would be observed on Earth if the

text: Antarctic ice sheet

text: was several times larger.

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 superhabitable planet is a hypothetical type of exoplanet or exomoon that may be better suited than Earth for the emergence and evolution of  life. The concept was introduced in 2014 by René Heller and John Armstrong, who have criticized the language used in the search for habitable planets, so they propose clarifications because a circumstellar habitable zone (HZ) is not enough to define a planet's habitability. Heller and  Armstrong state that it is not clear why Earth should offer the most suitable physicochemical parameters to living organisms, because "planets could be non-Earth-like, yet offer more suitable conditions for the emergence and evolution of life than Earth did or does."  While still assuming that life requires water, they hypothesize that Earth may not represent the optimal planetary habitability conditions for maximum biodiversity; in other words, they define a superhabitable world as a terrestrial planet or moon that could support more diverse flora and fauna than there are on Earth, as it would empirically show that its environment is more hospitable to life.

text: A superhabitable planet is a hypothetical type of

text: exoplanet

text: or

text: exomoon

text: that may be better suited than

text: Earth

text: for the

text: emergence

text: and

text: evolution

text: of

text: life

text: . The concept was introduced in 2014 by René Heller and John Armstrong, who have criticized the language used in the search for

text: habitable planets

text: , so they propose clarifications because a

text: circumstellar habitable zone

text: (HZ) is not enough to define a planet's habitability. Heller and  Armstrong state that it is not clear why Earth should offer the most suitable physicochemical parameters to living organisms, because "planets could be non-Earth-like, yet offer more suitable conditions for the emergence and evolution of life than Earth did or does."  While still assuming that life requires water, they hypothesize that Earth may not represent the optimal

text: planetary habitability

text: conditions for maximum

text: biodiversity

text: ; in other words, they define a superhabitable world as a

text: terrestrial planet

text: or moon that could support more diverse

text: flora

text: and

text: fauna

text: than there are on Earth, as it would empirically show that its

text: environment

text: is more hospitable to life.

text: Other planets that rotate in relation to a luminous primary, such as a local star, also experience daytime of a sort, but this article primarily discusses daytime on Earth.

text: Other planets that rotate in relation to a luminous primary, such as a local

text: star

text: , also experience daytime of a sort, but this article primarily discusses daytime on Earth.

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: ) is the ruling planet of Leo and is exalted in Aries. In Greek mythology, the Sun was represented by the Titans Hyperion and Helios (Roman Sol, and later by Apollo, the god of light). The Sun is the star at the center of our solar system, around which the Earth and other planets revolve and provides us with heat and light. The arc that the Sun travels in every year, rising and setting in a slightly different place each day, is therefore in reality a reflection of the Earth's own orbit around the Sun. This arc is larger the farther north or south from the equator latitude, giving a more extreme difference between day and night and between seasons during the year. The Sun travels through the twelve signs of the zodiac on its annual journey, spending about a month in each. The Sun's position on a person's birthday therefore determines what is usually called his or her "sun" sign. However, the sun sign allotment varies between Western (sign change around 22-23 of every month) and Hindu astrology (sign change around 14-15 of every month) due the different systems of planetary calculations, following the tropical and sidereal definitions respectively.

text: ) is the ruling planet of

text: Leo

text: and is exalted in

text: Aries

text: . In Greek mythology, the Sun was represented by the

text: Titans

text: Hyperion

text: and

text: Helios

text: (Roman

text: Sol

text: , and later by

text: Apollo

text: , the god of light). The Sun is the star at the center of our solar system, around which the Earth and other planets revolve and provides us with heat and light. The arc that the Sun travels in every year, rising and setting in a slightly different place each day, is therefore in reality a reflection of the Earth's own orbit around the Sun. This arc is larger the farther north or south from the equator latitude, giving a more extreme difference between day and night and between seasons during the year. The Sun travels through the twelve signs of the zodiac on its annual journey, spending about a month in each. The Sun's position on a person's birthday therefore determines what is usually called his or her "sun" sign. However, the sun sign allotment varies between Western (sign change around 22-23 of every month) and Hindu astrology (sign change around 14-15 of every month) due the different systems of planetary calculations, following the

text: tropical

text: and

text: sidereal

text: definitions respectively.

text: Planet Earth premiered on BBC One on 5 March 2006 in the United Kingdom. On the same day or in the subsequent weeks or months, the series also began airing in several other countries.

text: Kepler-442b is a super-Earth, an exoplanet with a mass and radius bigger than that of Earth, but smaller than that of the ice giants Uranus and Neptune. It has an equilibrium temperature of . It has a radius of 1.34 . Because of its radius, it is likely to be a rocky planet with a solid surface. The mass of the exoplanet is estimated to be 2.34 . The surface gravity on Kepler-442b would be 30% stronger than that of Earth, assuming a rocky composition similar to that of Earth.

text: Kepler-442b is a

text: super-Earth

text: , an exoplanet with a mass and radius bigger than that of Earth, but smaller than that of the ice giants

text: Uranus

text: and

text: Neptune

text: . It has an

text: equilibrium temperature

text: of . It has a radius of 1.34 . Because of its radius, it is likely to be a

text: rocky planet

text: with a solid surface. The mass of the exoplanet is estimated to be 2.34 . The surface

text: gravity

text: on Kepler-442b would be 30% stronger than that of Earth, assuming a rocky composition similar to that of Earth.

text: The problem is that in September the Sun takes less time (as measured by an accurate clock) to make an apparent revolution than it does in December; 24 "hours" of solar time can be 21 seconds less or 29 seconds more than 24 hours of clock time. As explained in the equation of time article, this is due to the eccentricity of the Earth's orbit (i.e. the Earth's orbit is not perfectly circular, meaning that the Earth-Sun distance varies throughout the year), and the fact that the Earth's axis is not perpendicular to the plane of its orbit (the so-called obliquity of the ecliptic).

text: The problem is that in September the Sun takes less time (as measured by an accurate clock) to make an apparent revolution than it does in December; 24 "hours" of solar time can be 21 seconds less or 29 seconds more than 24 hours of clock time. As explained in the

text: equation of time

text: article, this is due to the

text: eccentricity

text: of the Earth's orbit (i.e. the Earth's orbit is not perfectly circular, meaning that the Earth-Sun distance varies throughout the year), and the fact that the Earth's axis is not perpendicular to the plane of its orbit (the so-called

text: obliquity of the ecliptic

text: Basing his calculations on Hohmann’s orbit, the sci-fi writer Arthur C. Clarke had stated once that an Earth to Mars flight with a minimum fuel consumption would require at least 259 days. Then another 425 days should elapse on the Red Planet to re-align the planets so as to travel back again in 259 days. Crocco deemed this period too long and drew his own calculations exploiting Mars gravity pull to fly over the planet without landing. Mars gravity would deflect the spaceship’s trajectory towards the Earth cutting the flight’s overall length to less than a year, the only objection being the poor quality of data gathered passing over Mars at an altitude of more than a million miles. But, Crocco added, should the spaceship be re-directed towards Venus and not the Earth, it would fly over Mars at a very closer range: observation by the astronauts would be much more satisfactory, and moreover they could observe Venus as well, still keeping the trip’s time under a year. He calculated 113 days from Earth to Mars, 154 to reach Venus from Mars and 98 days from Venus back to Earth and affirmed that the first occasion for this ‘Crocco Grand Tour’ would be occurring in 1971. Gravity assist manoeuvres as envisaged by him are used extensively in all interplanetary missions today.

text: Basing his calculations on Hohmann’s orbit, the sci-fi writer

text: Arthur C. Clarke

text: had stated once that an Earth to Mars flight with a minimum fuel consumption would require at least 259 days. Then another 425 days should elapse on the Red Planet to re-align the planets so as to travel back again in 259 days. Crocco deemed this period too long and drew his own calculations exploiting Mars gravity pull to fly over the planet without landing. Mars gravity would deflect the spaceship’s trajectory towards the Earth cutting the flight’s overall length to less than a year, the only objection being the poor quality of data gathered passing over Mars at an altitude of more than a million miles. But, Crocco added, should the spaceship be re-directed towards Venus and not the Earth, it would fly over Mars at a very closer range: observation by the astronauts would be much more satisfactory, and moreover they could observe Venus as well, still keeping the trip’s time under a year. He calculated 113 days from Earth to Mars, 154 to reach Venus from Mars and 98 days from Venus back to Earth and affirmed that the first occasion for this ‘Crocco Grand Tour’ would be occurring in 1971. Gravity assist manoeuvres as envisaged by him are used extensively in all interplanetary missions today.

text: The four innermost planets are probably tidally locked, but Kepler-186f is further out, where the star's tidal effects are much weaker, so there may not have been enough time for its spin to slow down that much. Because of the very slow evolution of red dwarf stars, the age of the Kepler-186 system is poorly constrained, although it is likely to be greater than a few billion years. There is a roughly 50-50 chance it is tidally locked. Since it is closer to its star than Earth is to the Sun, it will probably rotate much more slowly than Earth; its day could be weeks or months long (see Tidal effects on rotation rate, axial tilt and orbit).

text: The four innermost planets are probably

text: tidally locked

text: , but Kepler-186f is further out, where the star's

text: tidal effects

text: are much weaker, so there may not have been enough time for its spin to slow down that much. Because of the very slow evolution of red dwarf stars, the age of the Kepler-186 system is poorly constrained, although it is likely to be greater than a few billion years. There is a roughly 50-50 chance it is tidally locked. Since it is closer to its star than Earth is to the Sun, it will probably rotate much more slowly than Earth; its day could be weeks or months long (see

text: where T and T are Earth's and the planet's years (i.e. periods of revolution around the Sun, called sidereal periods).

text: where T and T are Earth's and the planet's years (i.e.

text: period

text: s of revolution around the Sun, called

text: sidereal period

text: s).

text: The first Ultraa was introduced in Justice League of America #153. Like Superman, Ultraa was the sole survivor of a destroyed alien world, rocketed to Earth-Prime as a baby. After his first encounter with the Justice League, Ultraa decided Earth-Prime was not ready for superheroes and relocated to Earth-One. Post-Crisis, when there was no longer an Earth-Prime or greater multiverse, Ultraa was retconned into being from the planet Almerac, homeworld of Maxima. In Multiversity: Ultraa Comics, a version similar to the original is set to be introduced on Earth-33 of the New 52 DC Multiverse.

text: The first Ultraa was introduced in Justice League of America #153. Like Superman, Ultraa was the sole survivor of a destroyed alien world, rocketed to Earth-Prime as a baby. After his first encounter with the Justice League, Ultraa decided Earth-Prime was not ready for superheroes and relocated to Earth-One. Post-Crisis, when there was no longer an Earth-Prime or greater multiverse, Ultraa was retconned into being from the planet Almerac, homeworld of

text: Maxima

text: . In

text: Multiversity

text: : Ultraa Comics, a version similar to the original is set to be introduced on Earth-33 of the

text: New 52

text: DC Multiverse

text: While spending time in the WayneTech Labs in Pre-Crisis Gotham City, Supergirl of Earth-One notices a device which Lucius Fox of Earth-One explains is designed to read her subconscious physical reactions. With it, he hopes that she can help Superman of Earth-One rebuild the Phantom Zone Projector by sensing the correct placements of the parts that she subconsciously remembers from when her father Zor-El and uncle Jor-El built it when she was a girl. Superman of Earth-One hopes that by opening a way to the Phantom Zone, they'll be opening a way out of the dome that fell over Gotham City of Earth-One a year ago. However, the Phantom Zone is filled with Krypton's worst criminals. After the device that would provide a one-way trip to the Phantom Zone is created, Superman of Earth-One and Supergirl of Earth-One enter only to have the device blow up sealing them there. Suddenly from beyond the dome, Lucius Fox of Earth-One hears a voice warning that the dome will soon fall, and champions will be forced to rise from each of the cities on the planet Telos and to fight for the survival of their people. Superman of Earth-One and Supergirl of Earth-One wonder what the purpose of the dome was. Perhaps it was to protect Gotham City from a catastrophe. Perhaps it has made them features in a zoo or prisoners. Suddenly, they are overcome by shockwaves from nearby and decide to investigate the source. En route, Superman of Earth-One explains that he admires Supergirl of Earth-One for her proactive behavior. She uses her powers for good, but he always uses his to react. Without warning, the pair are attacked by Phantom Zone prisoners who are eager for revenge. Superman of Earth-One urges Kara of Earth-One to go on without him, but in so doing is overcome. Supergirl of Earth-One spots geysers of gas coming from the ground. In the gas, she sees visions of her own past, future, and inevitable death at the hands of the Anti-Monitor. Angrily, she dispels the gas as she doesn't want to see any further parts of her future. She worries that if she doesn't go back to Earth, her loved ones will die. If she does go back, she will die. Determinedly, she decides that if she is to die, it is necessary that she save others doing it. Supergirl of Earth-One gets lost in the gas, losing track of time. Eventually, Supergirl of Earth-One realizes that Superman of Earth-One should have been back by now, and searches for him. Supergirl of Earth-One discovers that Superman of Earth-One is surrounded by Phantom Zone prisoners. She takes out several of them leaving only two of them who are guarding Superman of Earth-One. After taking out the guards, Supergirl of Earth-One grabs Superman of Earth-One and they get away. While looking for a way out of the Phantom Zone and evading the gases, Superman of Earth-One and Supergirl of Earth-One are attacked by the Phantom Zone prisoners. Back at Gotham City of Earth-One, Lucius Fox of Earth-One is horrified when the dome goes down and the man-hating Apes from Earth-AD march into Gotham City of Earth-One.

text: While spending time in the WayneTech Labs in Pre-Crisis Gotham City, Supergirl of Earth-One notices a device which

text: Lucius Fox

text: of Earth-One explains is designed to read her subconscious physical reactions. With it, he hopes that she can help Superman of Earth-One rebuild the

text: Phantom Zone

text: Projector by sensing the correct placements of the parts that she subconsciously remembers from when her father

text: Zor-El

text: and uncle

text: Jor-El

text: Anti-Monitor

text: . Angrily, she dispels the gas as she doesn't want to see any further parts of her future. She worries that if she doesn't go back to Earth, her loved ones will die. If she does go back, she will die. Determinedly, she decides that if she is to die, it is necessary that she save others doing it. Supergirl of Earth-One gets lost in the gas, losing track of time. Eventually, Supergirl of Earth-One realizes that Superman of Earth-One should have been back by now, and searches for him. Supergirl of Earth-One discovers that Superman of Earth-One is surrounded by Phantom Zone prisoners. She takes out several of them leaving only two of them who are guarding Superman of Earth-One. After taking out the guards, Supergirl of Earth-One grabs Superman of Earth-One and they get away. While looking for a way out of the Phantom Zone and evading the gases, Superman of Earth-One and Supergirl of Earth-One are attacked by the Phantom Zone prisoners. Back at Gotham City of Earth-One, Lucius Fox of Earth-One is horrified when the dome goes down and the man-hating Apes from Earth-AD march into Gotham City of Earth-One.

text: The Mars Global Surveyor (MGS) discovered magnetic stripes in the crust of Mars, especially in the Phaethontis and Eridania quadrangles  (Terra Cimmeria and Terra Sirenum). The magnetometer on MGS discovered  wide stripes of magnetized crust running roughly parallel for up to . These stripes alternate in polarity with the north magnetic pole of one pointing up from the surface and the north magnetic pole of the next pointing down.  When similar stripes were discovered on Earth in the 1960s, they were taken as evidence of plate tectonics.  Researchers believe these magnetic stripes on Mars are evidence for a short, early period of plate tectonic activity. When the rocks became solid they retained the magnetism that existed at the time.  A magnetic field of a planet is believed to be caused by fluid motions under the surface.  The initial data was obtained when MGS traveled close to the planet during aerobraking.  However, later measurements, collected over a 2-year period from an altitude of , revealed that the magnetic features even matched up with known features on the surface. However, there are some differences, between the magnetic stripes on Earth and those on Mars. The Martian stripes are wider, much more strongly magnetized, and do not appear to spread out from a middle crustal spreading zone. Because the area containing the magnetic stripes is about 4 billion years old, it is believed that the global magnetic field probably lasted for only the first few hundred million years of Mars' life, when the temperature of the molten iron in the planet's core might have been high enough to mix it into a magnetic dynamo.  There are no magnetic fields near large impact basins like Hellas.  The shock of the impact may have erased the remnant magnetization in the rock.  So, magnetism produced by early fluid motion in the core would not have existed after the impacts.

text: The

text: Mars Global Surveyor

text: Eridania quadrangle

text: s  (Terra Cimmeria and

text: Terra Sirenum

text: ). The magnetometer on MGS discovered  wide stripes of magnetized crust running roughly parallel for up to . These stripes alternate in polarity with the north magnetic pole of one pointing up from the surface and the north magnetic pole of the next pointing down.  When similar stripes were discovered on Earth in the 1960s, they were taken as evidence of

text: plate tectonics

text: .  Researchers believe these magnetic stripes on Mars are evidence for a short, early period of plate tectonic activity. When the rocks became solid they retained the magnetism that existed at the time.  A magnetic field of a planet is believed to be caused by fluid motions under the surface.  The initial data was obtained when MGS traveled close to the planet during aerobraking.  However, later measurements, collected over a 2-year period from an altitude of , revealed that the magnetic features even matched up with known features on the surface. However, there are some differences, between the magnetic stripes on Earth and those on Mars. The Martian stripes are wider, much more strongly magnetized, and do not appear to spread out from a middle crustal spreading zone. Because the area containing the magnetic stripes is about 4 billion years old, it is believed that the global magnetic field probably lasted for only the first few hundred million years of Mars' life, when the temperature of the molten iron in the planet's core might have been high enough to mix it into a magnetic dynamo.  There are no magnetic fields near large impact basins like Hellas.  The shock of the impact may have erased the remnant magnetization in the rock.  So, magnetism produced by early fluid motion in the core would not have existed after the impacts.

text: The circadian rhythms of humans can be entrained to slightly shorter and longer periods than the Earth's 24 hours. Researchers at Harvard have shown that human subjects can at least be entrained to a 23.5-hour cycle and a 24.65-hour cycle (the latter being the natural solar day-night cycle on the planet Mars).

text: The circadian rhythms of humans can be entrained to slightly shorter and longer periods than the Earth's 24 hours. Researchers at Harvard have shown that human subjects can at least be entrained to a 23.5-hour cycle and a 24.65-hour cycle (the latter being the natural solar day-night cycle on the planet

text: Mars

text: Including the two-part pilot episode, the first season comprised 24 episodes, with four of the stories being two-parters. The tone of the series was lighter than the pilot movie, and showed a more positive picture of future Earth. The Inner City was now known as New Chicago, and it was established that human civilization had spread once again across the planet, and also to the stars. After the movie pilot, no reference to barren radioactive wastelands was made, and in several episodes, the world outside is shown as lush and green. The mutants seen in the pilot film were no longer seen, and Buck sometimes ventured outside New Chicago with no hazards encountered. As opposed to the isolationist planet seen in the film, Earth no longer has an invisible defense shield surrounding it and is shown to be the center of an interstellar human-dominated government, sometimes called "the Federation" of "the Alliance", with its capital at New Chicago. During the first season, references were also made to other "new" Earth cities such as New Detroit, New Manhattan, New Phoenix, New Tulsa, Boston Complex, and New London. A "City-on-the-Sea" was also seen, mentioned as being the former New Orleans.

text: Although 70.8% of all Earth's surface is covered in water, water accounts for just some 0.05% of Earth’s mass. There are worlds where more than 10% of the mass may be water. This may be the case, for example, for all the six innermost planets orbiting the star Kepler-11. These planets may have oceans hundreds of kilometres deep.Their abyssal depths would be so deep and dense that even at high temperatures the pressure would turn the water into ice. The immense pressures in the lower regions of these oceans could lead to the formation of a mantle of exotic forms of ice. This ice would not necessarily be as cold as conventional ice. If the planet is close enough to its star that the water reaches its boiling point, the water will become supercritical and lack a well-defined surface. Even on cooler water-dominated planets, the atmosphere can be much thicker than that of Earth, and composed largely of water vapor, producing a very strong greenhouse effect. Such planets would have to be small enough not to be able to retain a thick envelope of hydrogen and helium, otherwise they would form a warmer version of an ice giant instead, like Uranus and Neptune.

text: Although 70.8% of all

text: Earth

text: 's surface is covered in water, water accounts for just some 0.05% of Earth’s mass. There are worlds where more than 10% of the mass may be water. This may be the case, for example, for all the six innermost planets orbiting the star

text: . These planets may have oceans hundreds of kilometres deep.Their abyssal depths would be so deep and dense that even at high temperatures the pressure would turn the water into ice. The immense pressures in the lower regions of these oceans could lead to the formation of a mantle of exotic forms of

text: ice

text: . This ice would not necessarily be as cold as conventional ice. If the planet is close enough to its star that the water reaches its boiling point, the water will become

text: supercritical

text: and lack a well-defined surface. Even on cooler water-dominated planets, the atmosphere can be much thicker than that of Earth, and composed largely of water vapor, producing a very strong

text: greenhouse effect

text: . Such planets would have to be small enough not to be able to retain a thick envelope of hydrogen and helium, otherwise they would form a

text: warmer version

text: of an

text: ice giant

text: instead, like

text: Uranus

text: and

text: Neptune

text: The mantle of a planet with plate tectonics has driving forces that exceed the yield strength of the brittle lithosphere, causing the lithosphere to fracture into plates that move relative to each other. A critical element of the plate tectonic system is these lithospheric plates become negatively buoyant at some point in their evolution, sinking into the mantle. The surface mass deficit is balanced by new plate being formed elsewhere through upwelling mantle plumes. Plate tectonics is an efficient method of heat transfer from the interior of the planet to the surface. Earth is the only planet plate tectonics is known to occur on, although evidence has been presented for Jupiter's moon Europa undergoing a form of plate tectonics analogous to Earth's.

text: The mantle of a planet with plate tectonics has driving forces that exceed the

text: yield strength

text: of the brittle lithosphere, causing the lithosphere to fracture into plates that move relative to each other. A critical element of the plate tectonic system is these lithospheric plates become negatively buoyant at some point in their evolution, sinking into the mantle. The surface mass deficit is balanced by new plate being formed elsewhere through upwelling

text: mantle plumes

text: . Plate tectonics is an efficient method of heat transfer from the interior of the planet to the surface. Earth is the only planet plate tectonics is known to occur on, although evidence has been presented for

text: Jupiter's

text: moon

text: Europa

text: undergoing a form of plate tectonics analogous to Earth's.

text: The gravitational field of the earth is neither perfect nor uniform. A flattened ellipsoid is typically used as the idealized earth, but even if the earth were perfectly spherical, the strength of gravity would not be the same everywhere, because density (and therefore mass) varies throughout the planet. This is due to magma distributions, mountain ranges, deep sea trenches, and so on.

text: Magnetism has been known since prehistory, but knowledge of the Earth's field developed slowly. The horizontal direction of the Earth's field was first measured in the fourth century BC but the vertical direction was not measured until 1544 AD and the intensity was first measured in 1791. At first, compasses were thought to point towards locations in the heavens, then towards magnetic mountains. A modern experimental approach to understanding the Earth's field began with de Magnete, a book published by William Gilbert in 1600. His experiments with a magnetic model of the Earth convinced him that the Earth itself is a large magnet.

text: Magnetism has been known since prehistory, but knowledge of the Earth's field developed slowly. The horizontal direction of the Earth's field was first measured in the fourth century BC but the vertical direction was not measured until 1544 AD and the intensity was first measured in 1791. At first, compasses were thought to point towards locations in the heavens, then towards magnetic mountains. A modern experimental approach to understanding the Earth's field began with

text: de Magnete

text: , a book published by

text: William Gilbert

text: in 1600. His experiments with a magnetic model of the Earth convinced him that the Earth itself is a large magnet.

text: The first two serials were produced in the programme's first production block, but were held back until the beginning of the second season. Verity Lambert began lobbying for a second season in August 1964, and was initially only guaranteed 13 episodes. Nine were already planned as Planet of Giants and The Dalek Invasion of Earth, and with only four episodes after that Lambert felt it was too short a time to retain the regular actors and it would be then pointless to write Susan out at the end of The Dalek Invasion of Earth. In best interest of the actors and their agents, a deal was struck of an additional 13 episodes, and the commitment of 26 episodes in the second production block was accepted the day The Dalek Invasion of Earth finished filming.

text: The first two serials were produced in the programme's first production block, but were held back until the beginning of the second season.

text: Verity Lambert

text: began lobbying for a second season in August 1964, and was initially only guaranteed 13 episodes. Nine were already planned as Planet of Giants and The Dalek Invasion of Earth, and with only four episodes after that Lambert felt it was too short a time to retain the regular actors and it would be then pointless to write Susan out at the end of The Dalek Invasion of Earth. In best interest of the actors and their agents, a deal was struck of an additional 13 episodes, and the commitment of 26 episodes in the second production block was accepted the day The Dalek Invasion of Earth finished filming.

text: Kepler-22b's size is roughly twice that of Earth. Its mass and surface composition are unknown. An Earth-like composition for the planet has been ruled out. It is likely to have a volatile-rich composition with a liquid or gaseous outer shell. The only parameters of the planet's orbit that are currently available are its orbital period, which is about , and its inclination, which is approximately 90°. Evidence suggests that the planet has a moderate surface temperature, assuming that the surface is not subject to extreme greenhouse heating. In the absence of an atmosphere, its equilibrium temperature (assuming an Earth-like albedo) would be approximately .

text: Kepler-22b's size is roughly twice that of Earth. Its

text: mass

text: and surface composition are unknown. An

text: Earth-like composition

text: for the planet has been ruled out. It is likely to have a

text: volatile-rich composition

text: with a liquid or gaseous outer shell. The only parameters of the planet's

text: orbit

text: that are currently available are its

text: orbital period

text: , which is about , and its

text: inclination

text: , which is approximately 90°. Evidence suggests that the planet has a moderate surface temperature, assuming that the surface is not subject to extreme

text: greenhouse heating

text: . In the absence of an atmosphere, its

text: equilibrium temperature

text: (assuming an Earth-like

text: albedo

text: ) would be approximately .

text: Planet Earth Attack is the follow up album by Blackburner to Feel the Burn.  It features William Shatner on "Planet Earth Attack"

text: Planet Earth Attack is the follow up

text: album

text: by

text: Blackburner

text: to

text: Feel the Burn

text: .  It features

text: William Shatner

text: on "Planet Earth Attack"

text: Nyaru Menteng has been featured on Animal Planet's award-winning series Orangutan Island,  the BBC's Orangutan diary, Saving Planet Earth and Growing Up... Orangutan (BBC/Discovery Channel). Drøscher Nielsen starred in the 2008 Australian documentary-drama, The Burning Season.

text: Nyaru Menteng has been featured on

text: Animal Planet

text: 's award-winning series

text: Orangutan Island

text: ,  the

text: BBC

text: 's

text: Orangutan diary

text: Saving Planet Earth

text: and

text: Growing Up... Orangutan

text: (BBC/

text: Discovery Channel

text: ). Drøscher Nielsen starred in the 2008 Australian documentary-drama,

text: The Burning Season

text: Besides its other qualities, a Temple reveals the galactic coordinates of all planets with Temples. Therefore, any interstellar civilization can contact all others, excluding Earth. Earth does not have a Temple, and its coordinates are unknown. That is why Earth is often contemptiously called "the planet which doesn't exist." Most believe that the Seeders, by not leaving a Temple on the planet, displayed their contempt for Earth. One religious sect even believes that the Seeders consider Earth to be their enemy; as such, the sect believes that Earth must be destroyed. Fortunately, the same lack of coordinates prevents the planet's destruction. However, there have been rumors of people reaching Earth by making a blind jump.

text: A radiation belt is a zone of energetic charged particles, most of which originate from the solar wind that is captured by and held around a planet by that planet's magnetic field. The Earth has two such belts and sometimes others may be temporarily created. The discovery of the belts is credited to James Van Allen, and as a result the Earth's belts are known as the Van Allen belts. Earth's two main belts extend from an altitude of about 1,000 to 60,000 kilometers above the surface in which region radiation levels vary. Most of the particles that form the belts are thought to come from solar wind and other particles by cosmic rays. By trapping the solar wind, the magnetic field deflects those energetic particles and protects the Earth's atmosphere from destruction.

text: A radiation belt is a zone of

text: energetic

text: charged particle

text: s, most of which originate from the solar wind that is captured by and held around a planet by that planet's

text: magnetic field

text: . The Earth has two such belts and sometimes others may be temporarily created. The discovery of the belts is credited to

text: James Van Allen

text: , and as a result the Earth's belts are known as the Van Allen belts. Earth's two main belts extend from an altitude of about 1,000 to 60,000 kilometers above the surface in which region

text: radiation

text: levels vary. Most of the particles that form the belts are thought to come from

text: solar wind

text: and other particles by

text: cosmic ray

text: s. By trapping the solar wind, the magnetic field deflects those energetic particles and protects the Earth's atmosphere from destruction.

text: Earlier efforts (after 1798) to determine Earth's mass involved measuring G directly as in the Cavendish experiment. Earth's mass could be then found by combining two equations; Newton's second law, and Newton's law of universal gravitation:

text: Earlier efforts (after 1798) to determine Earth's mass involved measuring G directly as in the

text: Cavendish experiment

text: . Earth's mass could be then found by combining two equations;

text: Newton's second law

text: , and

text: Newton's law of universal gravitation

text: The great orbits of the planets take longer than the shorter: Saturn and Jupiter take many years, Mars two, whereas the moon takes only a month. Jupiter's moons take even less. This is not changed if the earth rotates every day, but if the earth is stationary then we suddenly find that the sphere of the fixed stars rotates in 24 hours. Given the distances, that would more reasonably be thousands of years.

text: Trevize never intends to go to Trantor, believing that, once at the library, Pelorat will never leave. Trevize and Pelorat discuss Pelorat's interest in Earth and its legends, and Trevize realizes that Seldon's phrase "at the other end of the Galaxy" (the phrase he used to describe the Second Foundation's location) could mean Earth. His logic being that Terminus (at the time of Hari Seldon) was the last planet to be inhabited (one end of the metaphorical galaxy) and, by definition, Earth was the first (the other end of the metaphorical galaxy). However, there is no planet named Earth in the galactic table of planets. Pelorat, through his previous research, established characteristics that Earth must have: a 24-hour day, a 365-day year, and a large satellite. Once again no planet on file has these characteristics, but the galactic table of planets is missing a lot of information about a lot of planets. Nonetheless, Pelorat has a guess. The table mentions a planet called Gaia, which Pelorat discovered, previously, to mean Earth. Its exact coordinates are unknown but it is listed as being in the Sayshell Sector. Trevize decides that they must go to the Sayshell Sector to follow up on this lead.

text: Trevize never intends to go to Trantor, believing that, once at the

text: library

text: , Pelorat will never leave. Trevize and Pelorat discuss Pelorat's interest in Earth and its legends, and Trevize realizes that Seldon's phrase "at the other end of the Galaxy" (the phrase he used to describe the Second Foundation's location) could mean Earth. His logic being that Terminus (at the time of Hari Seldon) was the last planet to be inhabited (one end of the metaphorical galaxy) and, by definition, Earth was the first (the other end of the metaphorical galaxy). However, there is no planet named Earth in the galactic table of planets. Pelorat, through his previous research, established characteristics that Earth must have: a 24-hour day, a 365-day year, and a large satellite. Once again no planet on file has these characteristics, but the galactic table of planets is missing a lot of information about a lot of planets. Nonetheless, Pelorat has a guess. The table mentions a planet called Gaia, which Pelorat discovered, previously, to mean Earth. Its exact coordinates are unknown but it is listed as being in the Sayshell Sector. Trevize decides that they must go to the Sayshell Sector to follow up on this lead.

text: Speculation about the cosmos was common in Pre-Socratic philosophy in the 6th and 5th centuries BC. Anaximander (c. 610 BC–c. 546 BC) described a cylindrical earth suspended in the center of the cosmos, surrounded by rings of fire. Philolaus (c.  480 BC–c. 405 BC) the Pythagorean described a cosmos with the stars, planets, Sun, Moon, Earth, and a counter-Earth (Antichthon)—ten bodies in all—circling an unseen central fire. Such reports show that Greeks of the 6th and 5th centuries BC were aware of the planets and speculated about the structure of the cosmos.Also, a more detailed description about the cosmos, Stars, Sun, Moon and the Earth can be found in the Orphism, which dates back to the end of the 5th century BC, and it is probably even older. Within the lyrics of the Orphic poems we can find remarkable information such as that the Earth is round, it has an axis and it moves around it in one day, it has three climate zones and that the Sun magnetizes the Stars and planets.

text: Speculation about the

text: cosmos

text: was common in

text: Pre-Socratic philosophy

text: in the 6th and 5th centuries BC.

text: Anaximander

text: (c. 610 BC–c. 546 BC) described a cylindrical earth suspended in the center of the cosmos, surrounded by rings of fire.

text: Philolaus

text: (c.  480 BC–c. 405 BC) the

text: Pythagorean

text: described

text: a cosmos

text: with the stars, planets,

text: Sun

text: Moon

text: Earth

text: , and a counter-Earth (

text: Antichthon

text: )—ten bodies in all—circling an unseen central fire. Such reports show that Greeks of the 6th and 5th centuries BC were aware of the planets and speculated about the structure of the cosmos.Also, a more detailed description about the cosmos, Stars, Sun, Moon and the Earth can be found in the

text: Orphism

text: , which dates back to the end of the 5th century BC, and it is probably even older. Within the lyrics of the Orphic poems we can find remarkable information such as that the Earth is round, it has an axis and it moves around it in one day, it has three climate zones and that the Sun magnetizes the Stars and planets.

text: In graphical terms, the Earth behaves like a spinning top, and tops tend to wobble as they spin. The spin of the Earth is its daily (diurnal) rotation. The spinning Earth slowly wobbles over a period slightly less than 26,000 years. From our perspective on Earth, the stars are ever so slightly 'moving' from west to east at the rate of one degree approximately every 72 years. One degree is about twice the diameter of the Sun or Moon as viewed from Earth. The easiest way to notice this slow movement of the stars is at any fixed time each year. The most common fixed time is at the vernal equinox around 21 March each year.

text: Although Jupiter is very massive, it is also very far away. When at its closest distance to Earth of about 600 million kilometers, Jupiter has a gravitational pull of 0.00013 newtons on a person with a mass of 100 kg, according to Newton's law of gravity. About 7.5 million times weaker than the Earth's gravity, this is roughly equivalent to the gravitational attraction of a compact car from half a meter away. Similarly, the gravitational pull of the dwarf planet Pluto on a person on Earth is roughly equal to that of a marble 100 meters away. Thus, the gravitational impact of the planets is far too small to be able to cause a person to weigh noticeably less, or stay in the air noticeably longer when jumping.

text: Although Jupiter is very massive, it is also very far away. When at its closest distance to Earth of about 600 million kilometers, Jupiter has a gravitational pull of 0.00013

text: newtons

text: on a person with a mass of 100 kg, according to

text: Newton's law of gravity.

text: About 7.5 million times weaker than the Earth's gravity, this is roughly equivalent to the gravitational attraction of a compact car from half a meter away. Similarly, the gravitational pull of the dwarf planet Pluto on a person on Earth is roughly equal to that of a marble 100 meters away. Thus, the gravitational impact of the planets is far too small to be able to cause a person to weigh noticeably less, or stay in the air noticeably longer when jumping.

text: Earth was co-directed by Alastair Fothergill, the executive producer of the television series, and Mark Linfield, the producer of Planet Earths "From Pole to Pole" and "Seasonal Forests" episodes. It was co-produced by BBC Natural History Unit and Greenlight Media, with Discovery providing some of the funding. It was also the first film released under the Disneynature label. The same organisations collaborated on Fothergill's previous film, Deep Blue (2003), itself a companion to his 2001 television series on the natural history of the world's oceans, The Blue Planet. The British version of Earth was narrated by Patrick Stewart and the US version was narrated by James Earl Jones.

text: Earth was co-directed by

text: Alastair Fothergill

text: , the executive producer of the television series, and

text: Mark Linfield

text: , the producer of Planet Earths "From Pole to Pole" and "Seasonal Forests" episodes. It was co-produced by

text: BBC Natural History Unit

text: and Greenlight Media, with Discovery providing some of the funding. It was also the first film released under the

text: Disneynature

text: label. The same organisations collaborated on Fothergill's previous film, Deep Blue (2003), itself a companion to his 2001 television series on the natural history of the world's oceans,

text: The Blue Planet

text: . The British version of Earth was narrated by

text: Patrick Stewart

text: and the US version was narrated by

text: James Earl Jones

text: The rotation rate of the Earth (Ω = 7.2921 × 10 rad/s) can be calculated as 2π / T radians per second, where T is the rotation period of the Earth which is one sidereal day (23 hr 56 m 4.1 s). In the midlatitudes, the typical value for

text: The

text: rotation rate of the Earth

text: (Ω = 7.2921 × 10 rad/s) can be calculated as 2π / T radians per second, where T is the rotation

text: period

text: of the Earth which is one

text: sidereal day

text: (23 hr 56 m 4.1 s). In the midlatitudes, the typical value for

text: Pi Mensae (π Men) is a yellow subgiant star in the constellation of Mensa. This star has a high proper motion. The apparent magnitude is 5.67, which can be visible to the naked eye in exceptionally dark, clear skies. It is nearly 60 ly away. The star dwarfs the Sun in terms of mass, size, luminosity, temperature, and metallicity and is about 730 million years younger. It ranks 100th on the list of top 100 target stars for the planned Terrestrial Planet Finder mission to search for Earth-like planets.

text: Pi Mensae (π Men) is a

text: yellow subgiant

text: star

text: in the

text: constellation

text: of

text: Mensa

text: . This star has a high

text: proper motion

text: . The

text: apparent magnitude

text: is 5.67, which can be visible to the

text: naked eye

text: in exceptionally dark, clear skies. It is nearly 60

text: ly

text: away. The star dwarfs the

text: Sun

text: in terms of

text: mass

text: , size,

text: luminosity

text: temperature

text: , and

text: metallicity

text: and is about 730 million years younger. It ranks 100th on the list of top 100 target stars for the planned

text: Terrestrial Planet Finder

text: mission to search for Earth-like planets.

text: Nowadays, the mass as a property of an object and its weight, which depends on the gravity of the earth at its position are strictly distinguished. However historically, the kilopond was also called kilogram, and only later the kilogram-mass (today's kilogram) was separated from the kilogram-force (today's kilopond). A kilopond originally referred to the weight of a mass of one kilogram. Since the gravitational acceleration on the surface of the earth can differ, one gets different values for the unit kilopond and its derived units at different locations. To avoid this, the kilopond was first defined at sea-level and a latitude of 45 degrees, since 1902 via the Standard gravity of 9.80665 m/s.

text: Nowadays, the mass as a property of an object and its weight, which depends on the gravity of the earth at its position are strictly distinguished. However historically, the kilopond was also called kilogram, and only later the kilogram-mass (today's kilogram) was separated from the kilogram-force (today's kilopond). A kilopond originally referred to the weight of a mass of one kilogram. Since the gravitational acceleration on the surface of the earth can differ, one gets different values for the unit kilopond and its derived units at different locations. To avoid this, the kilopond was first defined at sea-level and a

text: latitude

text: of 45 degrees, since 1902 via the

text: Standard gravity

text: of 9.80665 m/s.

text: Counter-Earth is the name of a fictional planet in Marvel Comics. There have been four versions of the hypothetical planet known as Counter-Earth, each one a near-duplicate of Earth.

text: Counter-Earth is the name of a fictional planet in

text: Marvel Comics

text: . There have been four versions of the hypothetical planet known as

text: Counter-Earth

text: , each one a near-duplicate of Earth.

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: The spacecraft has a mass of  and contains a Schmidt camera with a  front corrector plate (lens) feeding a  primary mirror – at the time of its launch this was the largest mirror on any telescope outside Earth orbit, though the Herschel Space Observatory took this title a few months later. The spacecraft has a 115 deg (about 12-degree diameter) field of view (FOV), roughly equivalent to the size of one's fist held at arm's length. Of this, 105 deg is of science quality, with less than 11% vignetting. The photometer has a soft focus to provide excellent photometry, rather than sharp images. The mission goal is a combined differential photometric precision (CDPP) of 20 ppm for a m(V)=12 Sun-like star for a 6.5-hour integration, though the observations so far have fallen short of this objective (see mission status). An Earth-size planet transit produces a brightness change of 84 ppm and lasts for thirteen hours when it crosses the midline of the star.

text: The spacecraft has a mass of  and contains a

text: Schmidt camera

text: with a  front corrector plate (lens) feeding a

text: primary mirror

text: – at the time of its launch this was the largest mirror on any telescope outside Earth orbit, though the

text: Herschel Space Observatory

text: took this title a few months later. The spacecraft has a 115 deg (about 12-degree diameter)

text: field of view

text: (FOV), roughly equivalent to the size of one's fist held at arm's length. Of this, 105 deg is of science quality, with less than 11%

text: vignetting

text: . The photometer has a

text: soft focus

text: to provide excellent

text: photometry

text: , rather than sharp images. The mission goal is a combined differential photometric precision (CDPP) of 20 ppm for a m(V)=12 Sun-like star for a 6.5-hour integration, though the observations so far have fallen short of this objective (see

text: mission status

text: ). An Earth-size planet transit produces a brightness change of 84 ppm and lasts for thirteen hours when it crosses the midline of the star.

text: Tolosani may have criticized the Copernican theory as scientifically unproven and unfounded, but the theory also conflicted with the theology of the time, as can be seen in a sample of the works of John Calvin. In his Commentary on Genesis he said that "We indeed are not ignorant that the circuit of the heavens is finite, and that the earth, like a little globe, is placed in the centre."  In his commentary on Psalms 93:1 he states that "The heavens revolve daily, and, immense as is their fabric and inconceivable the rapidity of their revolutions, we experience no concussion.... How could the earth hang suspended in the air were it not upheld by God's hand? By what means could it maintain itself unmoved, while the heavens above are in constant rapid motion, did not its Divine Maker fix and establish it."  One sharp point of conflict between Copernicus's theory and the Bible concerned the story of the Battle of Gibeon in the Book of Joshua where the Hebrew forces were winning but whose opponents were likely to escape once night fell. This is averted by Joshua's prayers causing the sun and the moon to stand still. Martin Luther once made a remark about Copernicus, although without mentioning his name. According to Anthony Lauterbach, while eating with Martin Luther the topic of Copernicus arose during dinner on 4 June 1539 (in the same year as professor George Joachim Rheticus of the local University had been granted leave to visit him). Luther is said to have remarked "So it goes now. Whoever wants to be clever must agree with nothing others esteem. He must do something of his own. This is what that fellow does who wishes to turn the whole of astronomy upside down. Even in these things that are thrown into disorder I believe the Holy Scriptures, for Joshua commanded the sun to stand still and not the earth." These remarks were made four years before the publication of On the Revolutions of the Heavenly Spheres and a year before Rheticus' Narratio Prima. In John Aurifaber's account of the conversation Luther calls Copernicus "that fool" rather than "that fellow", this version is viewed by historians as less reliably sourced.

text: Tolosani may have criticized the Copernican theory as scientifically unproven and unfounded, but the theory also conflicted with the theology of the time, as can be seen in a sample of the works of

text: John Calvin

text: . In his Commentary on Genesis he said that "We indeed are not ignorant that the circuit of the heavens is finite, and that the earth, like a little globe, is placed in the centre."  In his commentary on Psalms 93:1 he states that "The heavens revolve daily, and, immense as is their fabric and inconceivable the rapidity of their revolutions, we experience no concussion.... How could the earth hang suspended in the air were it not upheld by God's hand? By what means could it maintain itself unmoved, while the heavens above are in constant rapid motion, did not its Divine Maker fix and establish it."  One sharp point of conflict between Copernicus's theory and the Bible concerned the story of the Battle of

text: Gibeon

text: in the Book of Joshua where the Hebrew forces were winning but whose opponents were likely to escape once night fell. This is averted by Joshua's prayers causing the sun and the moon to stand still.

text: Martin Luther

text: once made a remark about Copernicus, although without mentioning his name. According to Anthony Lauterbach, while eating with Martin Luther the topic of Copernicus arose during dinner on 4 June 1539 (in the same year as professor George Joachim Rheticus of the local University had been granted leave to visit him). Luther is said to have remarked "So it goes now. Whoever wants to be clever must agree with nothing others esteem. He must do something of his own. This is what that fellow does who wishes to turn the whole of astronomy upside down. Even in these things that are thrown into disorder I believe the Holy Scriptures, for Joshua commanded the sun to stand still and not the earth." These remarks were made four years before the publication of On the Revolutions of the Heavenly Spheres and a year before Rheticus' Narratio Prima. In

text: John Aurifaber's

text: account of the conversation Luther calls Copernicus "that fool" rather than "that fellow", this version is viewed by historians as less reliably sourced.

text: Earth's rotation is not a simple rotation around an axis that would always remain parallel to itself. Earth's rotational axis itself rotates about a second axis, orthogonal to Earth's orbit, taking about 25,800 years to perform a complete rotation. This phenomenon is called the precession of the equinoxes. Because of this precession, the stars appear to move around Earth in a manner more complicated than a simple constant rotation.

text: Earth's rotation is not a simple rotation around an axis that would always remain parallel to itself. Earth's rotational axis itself rotates about a second axis,

text: orthogonal

text: to Earth's orbit, taking about 25,800 years to perform a complete rotation. This phenomenon is called the

text: precession of the equinoxes

text: . Because of this precession, the stars appear to move around Earth in a manner more complicated than a simple constant rotation.

text: After an unnamed war ended on Earth, the remnants of America and Britain quickly took control of the Americas, Western Europe and parts of Africa to create a new country and proceeded to promote peace and stability on Earth. They then proceeded to colonise other planets, forming the "Souther Confederacy" and when Nu-Earth was discovered, they built Fort Neuropa as a base of operations. When it was discovered that the black hole near the planet led to other parts of the Galaxy, tensions mounted between both sides. Eventually, the Norts attacked Fort Neuropa so the Southers were forced to retaliate. By the time of Rogue Trooper, Souther Gene-Scientists had created the G.I. Project in a desperate struggle to win the Nu-Earth Future War.

text: After an unnamed war ended on Earth, the remnants of America and Britain quickly took control of the Americas, Western Europe and parts of

text: Africa

text: to create a new country and proceeded to promote peace and stability on Earth. They then proceeded to colonise other planets, forming the "Souther Confederacy" and when Nu-Earth was discovered, they built Fort Neuropa as a base of operations. When it was discovered that the black hole near the planet led to other parts of the Galaxy, tensions mounted between both sides. Eventually, the Norts attacked Fort Neuropa so the Southers were forced to retaliate. By the time of Rogue Trooper, Souther Gene-Scientists had created the G.I. Project in a desperate struggle to win the Nu-Earth Future War.

text: It is sometimes more convenient to express the magnetic field in terms of magnetic latitude and distance in earth radii.  The magnetic latitude

text: The Earth's magnetic field lines arc high above the Earth until they reach the magnetic conjugate area in the opposite hemisphere.

text: Indian mathematician-astronomer Aryabhata, in his Aryabhatiya first identifies the force gravity to explain why objects do not fall when the earth rotates. propounds a geocentric solar system of gravitation, and an eccentric elliptical model of the planets, where the planets spin on their axes and follow elliptical orbits,the Sun and the moon revolve around the earth in epicycles. He also writes that the planets and the Moon do not have their own light but reflect the light of the Sun, and that the Earth rotates on its axis causing day and night and also sun around the earth causing years.

text: Indian mathematician-astronomer

text: Aryabhata

text: , in his

text: Aryabhatiya

text: first identifies the force gravity to explain why objects do not fall when the earth rotates. propounds a geocentric solar system of

text: gravitation

text: , and an

text: eccentric

text: elliptical

text: model of the planets, where the planets spin on their

text: axes

text: and follow elliptical orbits,the Sun and the moon revolve around the earth in

text: epicycles

text: . He also writes that the planets and the Moon do not have their own light but reflect the light of the Sun, and that the Earth rotates on its axis causing day and night and also sun around the earth causing years.

text: Though the dome came down some time ago, Metropolis is in a state of relative peace and the married Lois Lane of Earth-Two and the Superman of Earth-Two are looked up to by many. Even without his powers, Superman is still the hero of Metropolis and Lois is sure no one can take that away from him - not even this dome. Still, he feels a bit guilty that he can't do anything to get through the dome and free the city. He and his cousin Kara have been robbed of their identities in being robbed of their powers, and neither is feeling especially heroic as a result. Meanwhile, in Moscow of Earth-30, Joseph Stalin is concerned that his people are losing faith in the indestructibility of his regime after the dome has robbed his Superman of his powers. Lex Luthor of Earth-30 takes advantage of this as his genius-level intellect is not diminished by the dome where he claims that the dome is the alien's version of a zoo. Wonder Woman of Earth-30 states that the alien's intention is preservation and that there's a chance that every other city on their world was destroyed. Back in Metropolis of Earth-Two, Kara Zor-El of Earth-Two returns to her boyfriend Andrew Vinson where she complains that he is making pasta again and reminding that she hasn't got the Kryptonian metabolism anymore to protect her from gaining weight on all those carbs. Taking a shower after her gym workout, Kara Zor-El of Earth-Two becomes further disappointed with how her body is becoming more and more worn by being reduced to a human physiology. More than anything, she'd like things to go back to how they were, though she wouldn't like to tell Andrew so. Back in Moscow of Earth-30, Lex Luthor of Earth-30 and his wife Lois Lane of Earth-30 are walking by the Kremlin and she shouts at him again for becoming too involved in his work. He apologizes admitting that he's thinking very far ahead in the scheme of things. Despite that, Lex Luthor of Earth-30 still doesn't know how to bring down the dome. He has determined that it's not a dome, but a sphere. He hasn't yet given up on his allegiance to the United States, even after a year and wonders if Russia is hiding secrets in the hidden half of that sphere. Despite the fact that he is a secret CIA agent, Lex Luthor of Earth-30 has used his intellect to help the Russians perfect an invisible jet. Superman of Earth-30 grimly interrupts Lex Luthor of Earth 30's conversation with Lois Lane of Earth-30 to remind him that he is sure Lex Luthor of Earth-30 intended to steal the technology. He warns Lex to stop antagonizing Joseph Stalin. Lex Luthor of Earth-30 warns that Stalin should be more concerned about the machinations of his own son Pyotr. Even so, Superman informs him that Stalin will not tolerate any further disrespect, and he will not be able to intervene on his behalf. Back in Metropolis of Earth-Two, Lois Lane of Earth-Two gets frustrated that Superman of Earth-Two and Supergirl of Earth-Two are still focusing on the dome surrounding their Metropolis. Superman of Earth-Two agrees to take her home, but Andrew is concerned. Moments after Superman of Earth-Two and Lois of Earth-Two are gone, Kara Zor-El of Earth-Two and Andrew Vinson are startled by a voice coming from beyond the dome. It warns that the dome will soon fall and champions will be chosen from each of the cities on the planet Telos to fight for their city's survival. In Moscow, Wonder Woman of Earth-30 has heard the same message.

text: Though the dome came down some time ago, Metropolis is in a state of relative peace and the married Lois Lane of Earth-Two and the

text: Superman of Earth-Two

text: are looked up to by many. Even without his powers, Superman is still the hero of Metropolis and Lois is sure no one can take that away from him - not even this dome. Still, he feels a bit guilty that he can't do anything to get through the dome and free the city. He and his cousin Kara have been robbed of their identities in being robbed of their powers, and neither is feeling especially heroic as a result. Meanwhile, in Moscow of

text: Joseph Stalin

text: is concerned that his people are losing faith in the indestructibility of his regime after the dome has robbed his Superman of his powers.

text: Lex Luthor

text: of Earth-30 takes advantage of this as his genius-level intellect is not diminished by the dome where he claims that the dome is the alien's version of a zoo. Wonder Woman of Earth-30 states that the alien's intention is preservation and that there's a chance that every other city on their world was destroyed. Back in Metropolis of Earth-Two, Kara Zor-El of Earth-Two returns to her boyfriend Andrew Vinson where she complains that he is making pasta again and reminding that she hasn't got the Kryptonian metabolism anymore to protect her from gaining weight on all those carbs. Taking a shower after her gym workout, Kara Zor-El of Earth-Two becomes further disappointed with how her body is becoming more and more worn by being reduced to a human physiology. More than anything, she'd like things to go back to how they were, though she wouldn't like to tell Andrew so. Back in Moscow of Earth-30, Lex Luthor of Earth-30 and his wife Lois Lane of Earth-30 are walking by the

text: Kremlin

text: Astronomers had long been aware that there would be an alignment of the planets on that date, when Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto would be on the same side of the Sun, within an arc 95 degrees wide. But no effect could be expected as the gravitational effect of the other planets on the Earth's crust is minimal even at their closest approach. In this book, the authors sought to partially sidestep these objections by considering the effect of the alignment on the Sun, and hence on the solar wind, which in turn is known to affect weather on the Earth.  Atmospheric conditions on the Earth can alter the speed of its rotation. The effect on the Sun would also be quite small, however, and in fact there had been an even closer alignment in the year 1128 without any incident.

text: Astronomers had long been aware that there would be an

text: alignment

text: of the

text: planet

text: s on that date, when

text: Mercury

text: Venus

text: Earth

text: Mars

text: Jupiter

text: Saturn

text: Uranus

text: Neptune

text: and

text: Pluto

text: would be on the same side of the

text: Sun

text: , within an arc 95 degrees wide. But no effect could be expected as the gravitational effect of the other planets on the Earth's crust is minimal even at their closest approach. In this book, the authors sought to partially sidestep these objections by considering the effect of the alignment on the Sun, and hence on the solar wind, which in turn is known to affect weather on the Earth.  Atmospheric conditions on the Earth can alter the

text: speed of its rotation

text: . The effect on the Sun would also be quite small, however, and in fact there had been an even closer alignment in the year 1128 without any incident.

text: Earth’s magnetic fields are used for migration for a wide variety of species including  bacteria, mollusks, arthropods, mammals, birds, reptiles, and amphibians. In order to understand the Earth’s magnetic fields, the earth can be viewed as a large magnet. As a typical magnet has a north and south end, so does the earth. The north pole magnet is located at the Earth’s north pole and the south pole magnet is located at the Earth’s south pole. From this north and south pole span magnetic fields. The magnetic field leaves the poles and curves around the earth until it reaches the opposite pole.

text: In Starworld, the final novel in the trilogy, an interstellar rebellion has overthrown the Earth Empire's control over the interstellar colonies. Kulozik returns to Earth from exile to attempt to spread the revolution to the mother planet itself.

text: "Revolution Earth" is one of many songs with lyrics co-written with Robert Waldrop, a friend of the band.

text: The Epistola de magnete is divided into two parts. Part One (10 chapters): This is a section that serves as a model of inductive reasoning based on definite experiences, and setting forth the fundamental laws of magnetism. He did not discover these laws, but presented them in logical order. Part One discusses the physical (but not the occult) properties of the lodestone and provides the first extant written account of the polarity of magnets. He was thus the first to use the word “pole” in this context. He provides methods for determining the north and south poles of a magnet, and he describes the effects magnets have upon one another, showing that like poles repel each other and unlike poles attract each other. He also treats the attraction of iron by lodestones, the magnetization of iron by lodestones, and the ability to reverse the polarity in such an induced magnet. Peregrinus attributed the Earth's magnetism to the action of celestial poles, rather than to the terrestrial poles of the planet itself.

text: The Epistola de magnete is divided into two parts. Part One (10 chapters): This is a section that serves as a model of

text: inductive reasoning

text: based on definite experiences, and setting forth the fundamental laws of magnetism. He did not discover these laws, but presented them in logical order. Part One discusses the physical (but not the occult) properties of the

text: lodestone

text: and provides the first extant written account of the

text: polarity

text: of magnets. He was thus the first to use the word “

text: pole

text: ” in this context. He provides methods for determining the north and south poles of a magnet, and he describes the effects magnets have upon one another, showing that like poles repel each other and unlike poles attract each other. He also treats the attraction of iron by lodestones, the magnetization of iron by lodestones, and the ability to reverse the polarity in such an induced magnet. Peregrinus attributed the Earth's magnetism to the action of celestial poles, rather than to the terrestrial poles of the planet itself.

text: Although the size of an object may be reflected in its mass or its weight, each of these is a different concept. In scientific contexts, mass refers loosely to the amount of "matter" in an object (though "matter" may be difficult to define), whereas weight refers to the force experienced by an object due to gravity. An object with a mass of 1.0 kilogram will weigh approximately 9.81 newtons (newton is the unit of force, while kilogram is the unit of mass) on the surface of the Earth (its mass multiplied by the gravitational field strength). Its weight will be less on Mars (where gravity is weaker), more on Saturn, and negligible in space when far from any significant source of gravity, but it will always have the same mass. Two objects of equal size, however, may have very different mass and weight, depending on the composition and density of the objects. By contrast, if two objects are known to have roughly the same composition, then some information about the size of one can be determined by measuring the size of the other, and determining the difference in weight between the two. For example, if two blocks of wood are equally dense, and it is known that one weighs ten kilograms and the other weighs twenty kilograms, and that the ten kilogram block has a volume of one cubic foot, then it can be estimated that the twenty kilogram block has a volume of two cubic feet.

text: Although the size of an object may be reflected in its

text: mass

text: or its

text: weight

text: , each of these is a different concept. In scientific contexts, mass refers loosely to the amount of "

text: matter

text: " in an object (though "matter" may be difficult to define), whereas weight refers to the

text: force

text: experienced by an object due to

text: gravity

text: . An object with a mass of 1.0 kilogram will weigh approximately 9.81 newtons (

text: newton

text: is the unit of force, while

text: kilogram

text: is the unit of mass) on the surface of the

text: Earth

text: (its mass multiplied by the

text: gravitational field strength

text: ). Its weight will be less on

text: Mars

text: (where gravity is weaker), more on

text: Saturn

text: , and negligible in space when far from any significant source of gravity, but it will always have the same mass. Two objects of equal size, however, may have very different mass and weight, depending on the

text: composition

text: and

text: density

text: of the objects. By contrast, if two objects are known to have roughly the same composition, then some information about the size of one can be determined by measuring the size of the other, and determining the difference in weight between the two. For example, if two blocks of wood are equally dense, and it is known that one weighs ten kilograms and the other weighs twenty kilograms, and that the ten kilogram block has a volume of one cubic foot, then it can be estimated that the twenty kilogram block has a volume of two cubic feet.

text: Most planets in our solar system, including Earth, spin in the same direction as they orbit the Sun. The exceptions are Venus and Uranus. Uranus rotates nearly on its side relative to its orbit. Current speculation is that Uranus started off with a typical prograde orientation and was knocked on its side by a large impact early in its history. Venus may be thought of as rotating slowly backwards (or being "upside down"). The dwarf planet Pluto (formerly considered a planet) is anomalous in this and other ways.

text: Most

text: planet

text: s in our

text: solar system

text: , including

text: Earth

text: , spin in the same direction as they orbit the

text: Sun

text: . The exceptions are

text: Venus

text: and

text: Uranus

text: . Uranus rotates nearly on its side relative to its orbit. Current speculation is that Uranus started off with a typical prograde orientation and was knocked on its side by a large impact early in its history. Venus may be thought of as rotating slowly backwards (or being "upside down"). The

text: dwarf planet

text: Pluto

text: (formerly considered a planet) is anomalous in this and other ways.

text: A secret planet used as a penal colony where day and night last 181 days each and the planet is marked by extreme weather patterns. Plants dominate the planet's ecosystem.  Their varied defensive adaptions as well as carnivorous varieties are a constant hazard to the people of Chimaera. The violent seasonal bloom of muses, where the plants erupt from deep below the surface to spread their canopies to the sun, are the main source of water for Chimerans; most of the water lies deep in the planet's crust. Sap from a calypto plant is highly useful, but harvesting it is dangerous. The calypto sap erupts from punctures and inhalation can cause death. Of all the plants a verasoma is the most ferocious and formidable, a mobile carnivorous plant. It usually attacks from underground keeping its small weak point well away from any threat. Even when mortally wounded its death throes are likely to kill anything around it.

text: Due to varying degrees of success during the terraforming processes, each planet has a distinct environment type: Jupiter and Venus are temperate planets, the former of which has many drought-stricken areas; Earth is  lush and filled with wildlife; Uranus is locked in a permanent winter of snowy environments; and Neptune, in total contrast to the others, is a dull, murky world, of mutant plant life (constituting the game's only organic in-game enemies), and toxic atmospheres. The environmental effects encountered in each level can vary wildly, changing as the player progresses through the level, and includes weather effects, such as rain; a day-night cycle; and lethal meteor showers. The planets' environments also contain a number of human- built sculptures and structures, including pyramids, moai, obelisks, and dolmen. Along with wildlife, early hominids also inhabit the planets, and appear to have been responsible for building the aforementioned structures.

text: In 2003 the California and Carnegie Planet Search team announced the discovery of a planet orbiting the star. This planet orbits twice as far away from the star as Earth to the Sun and orbits very eccentrically. It has mass 95% (0.840) that of Jupiter and 267 times the mass of Earth.

text: In 2003 the

text: California and Carnegie Planet Search

text: team announced the discovery of a

text: planet

text: orbiting the star. This planet orbits twice as far away from the star as Earth to the Sun and orbits very eccentrically. It has

text: mass

text: 95% (0.840) that of

text: Jupiter

text: and 267 times the mass of

text: Earth

text: The Earth's rotation rate is still slowing down, though gradually, by about two thousandths of a second per rotation every 100 years. Estimates of how fast the Earth was rotating in the past vary, because it is not known exactly how the moon was formed. Estimates of the Earth's rotation 500 million years ago are around 20 modern hours per "day".

text: During the "Last Days" part of the Secret Wars storyline,  Magneto had to make a choice during the incursion between Earth-616 and Earth-1610. To save the mutant race, he must attempt to destroy the world colliding with his own. To save the mutant race, he must also protect the humans, who are currently celebrating him as a hero and look on with fascination at what he attempts to do when Earth-1610 throws Sentinels against him. As the energies of Earth-616 and Earth-1610 inched closer to impact cascade and send chaos through the streets, Magneto (aided by his daughter Polaris) are taking the fight to this "other" Earth, battling the parallel Sentinels sent after them. Polaris is shocked to see the energy levels her father is exhibiting, all the while trying to protect the people caught in the crossfire of Magneto and the Sentinels. Magneto clearly has one goal in mind, as he rips a building to pieces to use against the killer robots, not caring much for the collateral damage, or the human lives at risk, as people in the building fall to the ground below. Polaris chides him for so reckless an action as she goes to the rescue while Magneto reminisces the reason he's currently exhibiting this level of power. Magneto and his current right hand Briar worked with a chemist under Magneto's employ to pump him up with a new cocktail of various drugs to amplify his powers, but Magneto needed further assistance. Months before the final Incursion happened, Briar established at least initial contact with several scientists which included Doctor Doom, Mister Fantastic, the High Evolutionary, Mister Sinister, Doctor Nemesis, and Dark Beast. However, Magneto instead picked out of the lineup the Sugar Man. From him, Magneto acquires the means to initiate his plan, and thanks him in true Magneto style where he leaves Sugar Man barely alive. In the present time, Magneto continues to use the very magnetic forces of the planet to aid him, yet that's more power than he could ever channel and very quickly began taking a deadly toll on him. As Polaris tries getting him to take a break because his plan is killing him too quickly, Magneto began thinking that he doesn't believe in resting even for a minute in his eternal war to protect everything he cares about. He recalls picking up the Sugar Man's power amplifiers and his powers go into hyper-drive and he starts having brain aneurysms. Flip to present day, Magneto sees the S.H.I.E.L.D. coming to his aid and grins. Magneto tells Polaris that their help won't be needed for much longer and she says she doesn't understand but quickly figures it out what her father meant as Magneto absorbs her power and says that it is his responsibility alone and that he couldn't let her die alongside him and that she still has something to offer the world. Magneto's powers then go nova as all the powers of the Earth's North and South Magnetic poles and all the bio-electric energies of the Earth are channeled through him and he reflects on his life role.

text: During the "Last Days" part of the

text: Secret Wars

text: storyline,  Magneto had to make a choice during the incursion between Earth-616 and Earth-1610. To save the mutant race, he must attempt to destroy the world colliding with his own. To save the mutant race, he must also protect the humans, who are currently celebrating him as a hero and look on with fascination at what he attempts to do when Earth-1610 throws Sentinels against him. As the energies of Earth-616 and Earth-1610 inched closer to impact cascade and send chaos through the streets, Magneto (aided by his daughter Polaris) are taking the fight to this "other" Earth, battling the parallel Sentinels sent after them. Polaris is shocked to see the energy levels her father is exhibiting, all the while trying to protect the people caught in the crossfire of Magneto and the Sentinels. Magneto clearly has one goal in mind, as he rips a building to pieces to use against the killer robots, not caring much for the collateral damage, or the human lives at risk, as people in the building fall to the ground below. Polaris chides him for so reckless an action as she goes to the rescue while Magneto reminisces the reason he's currently exhibiting this level of power. Magneto and his current right hand Briar worked with a

text: chemist

text: under Magneto's employ to pump him up with a new cocktail of various drugs to amplify his powers, but Magneto needed further assistance. Months before the final Incursion happened, Briar established at least initial contact with several scientists which included Doctor Doom, Mister Fantastic, the High Evolutionary, Mister Sinister,

text: Doctor Nemesis

text: , and Dark Beast. However, Magneto instead picked out of the lineup the Sugar Man. From him, Magneto acquires the means to initiate his plan, and thanks him in true Magneto style where he leaves Sugar Man barely alive. In the present time, Magneto continues to use the very magnetic forces of the planet to aid him, yet that's more power than he could ever channel and very quickly began taking a deadly toll on him. As Polaris tries getting him to take a break because his plan is killing him too quickly, Magneto began thinking that he doesn't believe in resting even for a minute in his eternal war to protect everything he cares about. He recalls picking up the Sugar Man's power amplifiers and his powers go into hyper-drive and he starts having brain aneurysms. Flip to present day, Magneto sees the S.H.I.E.L.D. coming to his aid and grins. Magneto tells Polaris that their help won't be needed for much longer and she says she doesn't understand but quickly figures it out what her father meant as Magneto absorbs her power and says that it is his responsibility alone and that he couldn't let her die alongside him and that she still has something to offer the world. Magneto's powers then go nova as all the powers of the Earth's North and South Magnetic poles and all the bio-electric energies of the Earth are channeled through him and he reflects on his life role.

text: Raw data frequently contain hidden frequencies. Combinations of a few fixed frequency waves can complicate the recognition of the mixture of signals, but still remain predictable over time. Publications  show that atmospheric pressure contains hidden periodicities resulting from the gravitational force of the moon and the daily period of the sun. The reconstruction of these periodic signals of atmospheric tidal waves allows for an explanation and prediction of many anomalies present in extreme weather. Similar tidal waves must exist on the sun resulting from the gravitational force of planets. The rotation of the sun around its axes will cause a current, similar to the equatorial current on the earth. Perturbations or eddies around the current will cause anomalies on the surface of the sun. Horizontal rotational eddies in highly magnetic plasma will create a vertical explosion which will transport deeper, hotter plasma to above the surface of the sun. Each planet creates a tidal wave with a specific frequency on the sun. At times any two of the waves will occur in phase and other times will be out of phase. The resulting amplitude will oscillate with a difference frequency. The estimation of the spectra of sunspot data using the DZ algorithm provides two sharp frequency lines with periodicities close to 9.9 and 11.7 years. These frequency lines can be considered as difference frequencies caused by Jupiter and Saturn (9.9) and Venus and Earth (11.7). The difference frequency between 9.9 and 11.7 yields a frequency with a 64-year period. All of these periods are identifiable in sunspot data. The 64-year period component is currently in a declining mode. This decline may cause a cooling effect on the earth in the near future. An examination of the joint effect of multiple planets may reveal some long periods in sun activity and help explain climate fluctuations on earth.

text: Kepler uses a daemon to describe the island of Levania in many scientific ways. The fixed stars are in the same position as the Earth's fixed stars. The planets appear larger from Levania than from Earth due to the distance Levania is from Earth. Levania also sees planetary motions in a different way. For instance, Levania does not seem to move while the Earth is seen to move just as Earth does not seem to move when on Earth but the Moon is seen to move. This is an example of Kepler defending Copernicus' diurnal rotation. The inhabitants at the divisor see the planets different from the rest of the Moon. Mercury and Venus specifically seem bigger to them.

text: Near the surface of the Earth, its magnetic field can be closely approximated by the field of a magnetic dipole positioned at the center of the Earth and tilted at an angle of about 11° with respect to the rotational axis of the Earth. The dipole is roughly equivalent to a powerful bar magnet, with its south pole pointing towards the geomagnetic North Pole. This may seem surprising, but the north pole of a magnet is so defined because, if allowed to rotate freely, it points roughly northward (in the geographic sense). Since the north pole of a magnet attracts the south poles of other magnets and repels the north poles, it must be attracted to the south pole of Earth's magnet. The dipolar field accounts for 80–90% of the field in most locations.

text: Near the surface of the Earth, its magnetic field can be closely approximated by the field of a

text: magnetic dipole

text: positioned at the center of the Earth and tilted at an angle of about 11° with respect to the

text: rotational axis

text: of the Earth. The dipole is roughly equivalent to a powerful bar

text: magnet

text: , with its south pole pointing towards the

text: geomagnetic North Pole

text: . This may seem surprising, but the north pole of a magnet is so defined because, if allowed to rotate freely, it points roughly northward (in the geographic sense). Since the north pole of a magnet attracts the south poles of other magnets and repels the north poles, it must be attracted to the south pole of Earth's magnet. The dipolar field accounts for 80–90% of the field in most locations.

text: In 2004, German record company Drizzly Records released a rare 12" vinyl containing seven remixes of "Surround Me With Your Love". The cosmetic firm Rimmel used the remix "Surround Me With Your Love" in a 2005 commercial starring Kate Moss, which was shown in 63 countries. "Surround Me With Your Love", the original song and the remix, has also been used by many international TV companies worldwide, including the BBC, TV Globo (Brazil), TV2 Norway, Discovery Channel and Animal Planet. The German label Stereo Deluxe signed 3–11 Porter in 2007 and released their second album,  Surround Me, in 2008. Guest performers on the album Surround Me included David M on "Sunglasses", "There Is A Place Where I Go" and "The Sleep That I’ll Bring You"; Helge Kvam on marimba on "The Mood of the Scene"; Ole Jørn Myklebust on trumpet on "On A Dead Sunday Afternoon", "Vintage" and "Sunglasses"; Javid Afsari Rad on santour on "The Loneliest Night on Earth"; Pejman Hadadi on percussion on "The Loneliest Night on Earth"; Vida Afsari Rad on "The Loneliest Night on Earth"; Maud Forsgren on "The Loneliest Night on Earth"; and Cristina Latini on "The Loneliest Night on Earth".

text: In 2004, German record company Drizzly Records released a rare 12" vinyl containing seven remixes of "Surround Me With Your Love". The cosmetic firm

text: Rimmel

text: used the remix "Surround Me With Your Love" in a 2005 commercial starring Kate Moss, which was shown in 63 countries. "Surround Me With Your Love", the original song and the remix, has also been used by many international TV companies worldwide, including the BBC, TV Globo (Brazil), TV2 Norway, Discovery Channel and Animal Planet. The German label Stereo Deluxe signed 3–11 Porter in 2007 and released their second album,  Surround Me, in 2008. Guest performers on the album Surround Me included David M on "Sunglasses", "There Is A Place Where I Go" and "The Sleep That I’ll Bring You"; Helge Kvam on marimba on "The Mood of the Scene"; Ole Jørn Myklebust on trumpet on "On A Dead Sunday Afternoon", "Vintage" and "Sunglasses"; Javid Afsari Rad on santour on "The Loneliest Night on Earth"; Pejman Hadadi on percussion on "The Loneliest Night on Earth"; Vida Afsari Rad on "The Loneliest Night on Earth"; Maud Forsgren on "The Loneliest Night on Earth"; and Cristina Latini on "The Loneliest Night on Earth".

text: The Moon is exceptionally large relative to Earth: a quarter its diameter and 1/81 its mass. It is the largest moon in the Solar System relative to the size of its planet, though Charon is larger relative to the dwarf planet Pluto, at 1/9 Pluto's mass. Earth and the Moon are nevertheless still considered a planet–satellite system, rather than a double planet, because their barycentre, the common centre of mass, is located  (about a quarter of Earth's radius) beneath Earth's surface.

text: The Moon is exceptionally large relative to Earth: a quarter its diameter and 1/81 its mass. It is the largest moon in the Solar System relative to the size of its planet, though

text: Charon

text: is larger relative to the dwarf planet

text: Pluto

text: , at 1/9 Pluto's mass. Earth and the Moon are nevertheless still considered a planet–satellite system, rather than a

text: double planet

text: , because their

text: barycentre

text: , the common centre of mass, is located  (about a quarter of Earth's radius) beneath Earth's surface.

text: A full season is sometimes split into two separate units with a hiatus around the end of the calendar year, such as the first season of Jericho on CBS. When this split occurs, the last half of the episodes sometimes are referred to with the letter B as in "The last nine episodes (of The Sopranos) will be part of what is being called either "Season 6, Part 2" or "Season 6B", or in "Futurama is splitting its seasons similar to how South Park does, doing half a season at a time, so this is season 6B for them." Since the 1990s, these shorter seasons also have been referred to as ".5" or half seasons, where the run of shows between September and December is labeled "Season X", and the second run between January and May labeled "Season X.5". Examples of this include the 2004 incarnation of Battlestar Galactica, ABC's FlashForward, and ABC Family's Make It or Break It.

text: A full season is sometimes split into two separate units with a hiatus around the end of the calendar year, such as the first season of

text: Jericho

text: on CBS. When this split occurs, the last half of the episodes sometimes are referred to with the letter B as in "The last nine episodes (of

text: The Sopranos

text: ) will be part of what is being called either "Season 6, Part 2" or "Season 6B", or in "

text: Futurama

text: is splitting its seasons similar to how

text: South Park

text: does, doing half a season at a time, so this is season 6B for them." Since the 1990s, these shorter seasons also have been referred to as ".5" or half seasons, where the run of shows between September and December is labeled "Season X", and the second run between January and May labeled "Season X.5". Examples of this include the 2004 incarnation of

text: Battlestar Galactica

text: , ABC's

text: FlashForward

text: , and ABC Family's

text: Make It or Break It

text: A second theory, more complicated than triaxiality, proposed that observed long periodic orbital variations of the first Earth satellites indicate an additional depression at the south pole accompanied by a bulge of the same degree at the north pole. It is also contended that the northern middle latitudes were slightly flattened and the southern middle latitudes bulged in a similar amount. This concept suggested a slightly pear-shaped Earth and was the subject of much public discussion. Modern geodesy tends to retain the ellipsoid of revolution and treat triaxiality and pear shape as a part of the geoid figure: they are represented by the spherical harmonic coefficients

text: A second theory, more complicated than triaxiality, proposed that observed long periodic orbital variations of the first Earth satellites indicate an additional depression at the south pole accompanied by a bulge of the same degree at the north pole. It is also contended that the northern middle latitudes were slightly flattened and the southern middle latitudes bulged in a similar amount. This concept suggested a slightly pear-shaped Earth and was the subject of much public discussion. Modern geodesy tends to retain the ellipsoid of revolution and treat triaxiality and pear shape as a part of the

text: geoid

text: figure: they are represented by the spherical harmonic coefficients

text: At the end of the season both planets, Fire and Water, are destroyed. Stan's soul is set free, and is able to return into his body, though he cannot remember what happened to him on Fire. The souls of all inhabitants of Fire and Water are also released, then travel to a planet that looks like Earth.

text: Although the inner most planet has a size similar to Mars, Kepler-138c and d both have a radius of 1.2 Earth radii. All of the planets are too close to their star to be considered within the habitable zone. Although Kepler-138c and d have the same size, their masses and densities vary greatly. Of these two, the inner planet is consistent with a rocky super-Earth, whereas the outer planet is thought to have a significant gas envelope and low density, resembling a miniaturized gas giant (a Gas dwarf). The striking differences between these two planets have been hypothesized to be due photoevaporation.

text: Although the inner most planet has a size similar to

text: Mars

text: , Kepler-138c and d both have a radius of 1.2

text: Earth radii

text: . All of the planets are too close to their star to be considered within the

text: habitable zone

text: . Although Kepler-138c and d have the same size, their masses and densities vary greatly. Of these two, the inner planet is consistent with a rocky

text: super-Earth

text: , whereas the outer planet is thought to have a significant gas envelope and low density, resembling a miniaturized

text: gas giant

text: (a

text: Gas dwarf

text: ). The striking differences between these two planets have been hypothesized to be due

text: photoevaporation

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

entity_name: Search for extraterrestrial intelligence

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: The Earth is roughly spherical, but it bulges towards the Equator, so it is roughly in the shape of an ellipsoid (see Earth ellipsoid). This bulge is due to its rotation and is nearly consistent with an Earth in hydrostatic equilibrium. The detailed shape of the Earth, however, is also affected by the distribution of continents and ocean basins, and to some extent by the dynamics of the plates.

text: The Earth is roughly spherical, but it bulges towards the

text: Equator

text: , so it is roughly in the shape of an ellipsoid (see

text: Earth ellipsoid

text: ). This bulge is due to its rotation and is nearly consistent with an Earth in

text: hydrostatic

text: equilibrium. The detailed shape of the Earth, however, is also affected by the distribution of

text: continents

text: and

text: ocean basins

text: , and to some extent by the dynamics of the plates.

text: Over Earth's equator, the magnetic field lines become almost horizontal, then return to reconnect at high latitudes. However, at high altitudes, the magnetic field is significantly distorted by the solar wind and its solar magnetic field. On the dayside of Earth, the magnetic field is significantly compressed by the solar wind to a distance of approximately . Earth's bow shock is about  thick and located about  from Earth. The magnetopause exists at a distance of several hundred kilometers above Earth's surface. Earth's magnetopause has been compared to a sieve because it allows solar wind particles to enter. Kelvin–Helmholtz instabilities occur when large swirls of plasma travel along the edge of the magnetosphere at a different velocity from the magnetosphere, causing the plasma to slip past. This results in magnetic reconnection, and as the magnetic field lines break and reconnect, solar wind particles are able to enter the magnetosphere. On Earth's nightside, the magnetic field extends in the magnetotail, which lengthwise exceeds . Earth's magnetotail is the primary source of the polar aurora. Also, NASA scientists have suggested that Earth's magnetotail might cause "dust storms" on the Moon by creating a potential difference between the day side and the night side.

text: Over Earth's

text: equator

text: , the magnetic field lines become almost horizontal, then return to reconnect at high latitudes. However, at high altitudes, the magnetic field is significantly distorted by the solar wind and its solar magnetic field. On the dayside of Earth, the magnetic field is significantly compressed by the solar wind to a distance of approximately . Earth's bow shock is about  thick and located about  from Earth. The magnetopause exists at a distance of several hundred kilometers above Earth's surface. Earth's magnetopause has been compared to a

text: sieve

text: because it allows solar wind particles to enter.

text: Kelvin–Helmholtz instabilities

text: occur when large swirls of plasma travel along the edge of the magnetosphere at a different velocity from the magnetosphere, causing the plasma to slip past. This results in

text: magnetic reconnection

text: , and as the magnetic field lines break and reconnect, solar wind particles are able to enter the magnetosphere. On Earth's nightside, the magnetic field extends in the magnetotail, which lengthwise exceeds . Earth's magnetotail is the primary source of the

text: polar aurora

text: . Also, NASA scientists have suggested that Earth's magnetotail might cause "dust storms" on the Moon by creating a potential difference between the day side and the night side.

text: The camera view then pulls back up in to the air, showing all the houses in the town also have "For Sale" signs. The view continues up show all of North America "For Sale", and finally the whole Earth is for sale. The Earth goes up for auction with the Moon serving as auctioneer and the planets start bidding, singing to the tune of "London Bridge Is Falling Down". Mars and Venus bid first, but Saturn is the eventual buyer. He pulls a large horse-shoe magnet out from the Earth, eliminating the planet's gravity, just to see what happens. Buildings, trees, animals, and people including Betty start floating into the air with humorous effect. Finally a hand reaches out from the Earth and grabs the magnet back from Saturn. Gravity is restored, and everything and everybody return to the ground. A series of buildings fall atop Betty, but she avoids injury as she emerges from the top of the pile of buildings singing "Any old place upon this Earth is home sweet home to me".

text: The camera view then pulls back up in to the air, showing all the houses in the town also have "For Sale" signs. The view continues up show all of North America "For Sale", and finally the whole Earth is for sale. The Earth goes up for auction with the Moon serving as auctioneer and the planets start bidding, singing to the tune of "

text: London Bridge Is Falling Down

text: Mars

text: and

text: Venus

text: bid first, but

text: Saturn

text: is the eventual buyer. He pulls a large horse-shoe

text: magnet

text: out from the Earth, eliminating the planet's

text: gravity

text: , just to see what happens. Buildings, trees, animals, and people including Betty start floating into the air with humorous effect. Finally a hand reaches out from the Earth and grabs the magnet back from Saturn. Gravity is restored, and everything and everybody return to the ground. A series of buildings fall atop Betty, but she avoids injury as she emerges from the top of the pile of buildings singing "Any old place upon this Earth is home sweet home to me".

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: Asimov calculated tug-of-war values for several satellites of the planets. He showed that even the largest gas giant, Jupiter, had only a slightly better hold than the Sun on its outer captured satellites, some with tug-of-war values not much higher than one. In nearly every one of Asimov's calculations the tug-of-war value was found to be greater than one, so in those cases the Sun loses the tug-of-war with the planets. The one exception was Earth's Moon, where the Sun wins the tug-of-war with a value of 0.46, which means that Earth's hold on the Moon is less than half that of the Sun's. Asimov included this with his other arguments that Earth and the Moon should be considered a binary planet.

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: Notorious examples are the great Venus term and the Jupiter-Saturn great inequality. Looking up the revolution periods of these planets, one may notice that 8×(period of Earth) is almost equal to 13×(period of Venus) and 5×(period of Jupiter) is about 2×(period of Saturn).

text: Notorious examples are the great

text: Venus

text: term and the Jupiter-

text: Saturn

text: great inequality. Looking up the revolution periods of these planets, one may notice that 8×(period of Earth) is almost equal to 13×(period of Venus) and 5×(period of Jupiter) is about 2×(period of Saturn).

text: An Earth analog (also referred to as a Twin Earth, Earth Twin,  or Earth-like planet, though this latter term may refer to any terrestrial planet) is a planet or moon with environmental conditions similar to those found on the planet Earth.

text: An Earth analog (also referred to as a Twin Earth, Earth Twin,  or Earth-like planet, though this latter term may refer to any

text: terrestrial planet

text: ) is a

text: planet

text: or

text: moon

text: with environmental conditions similar to those found on the planet

text: Earth

text: The Solar System has four terrestrial planets: Mercury, Venus, Earth, and Mars. Only one terrestrial planet, Earth, is known to have an active hydrosphere.

text: The

text: Solar System

text: has four terrestrial planets:

text: Mercury

text: Venus

text: Earth

text: , and

text: Mars

text: . Only one terrestrial planet, Earth, is known to have an active

text: hydrosphere

text: Guardian could cause the battle-suit computers to trigger and release gravitons, canceling the Earth's rotation relative to himself, propelling himself forwards at up to about 1000 miles per hour (at the equator). This effect will suspend his positioning relative to the Earth's electromagnetic field while the planet rotated, allowing him to travel West at high speed depending on his latitude positioning.

text: Guardian could cause the battle-suit computers to trigger and release gravitons, canceling the Earth's rotation relative to himself, propelling himself forwards at up to about 1000 miles per hour (at the equator). This effect will suspend his positioning relative to the Earth's electromagnetic field while the planet rotated, allowing him to travel West at high speed depending on his

text: latitude

text: positioning.

text: In the first season, Earth is attacked by Gamilon, a distant planet. The radiation from Gamilon's planet bombs forces everyone on Earth underground. With no way to remove the radiation, all life on Earth will be wiped out in one year. The Earth then receives unexpected help from Queen Starsha of the planet Iscandar, who offers a device called "Cosmo DNA" which will remove the radiation. However, since Iscandar is 148,000 light years away, Starsha also sends plans for the experimental Wave Motion Engine that, when constructed, will aid whoever can travel to Iscandar. On Earth, a crew is recruited, headed by Captain Avatar, and an old sunken battleship (the Yamato) is transformed into a spaceship (the Argo), outfitted with the Wave Motion Engine, and sent to Iscandar.

text: In the first season, Earth is attacked by Gamilon, a distant planet. The radiation from Gamilon's planet bombs forces everyone on Earth underground. With no way to remove the radiation, all life on Earth will be wiped out in one year. The Earth then receives unexpected help from Queen Starsha of the planet Iscandar, who offers a device called "Cosmo DNA" which will remove the radiation. However, since Iscandar is 148,000 light years away, Starsha also sends plans for the experimental Wave Motion Engine that, when constructed, will aid whoever can travel to Iscandar. On Earth, a crew is recruited, headed by Captain Avatar, and an old sunken battleship (the

text: Yamato

text: ) is transformed into a spaceship (the Argo), outfitted with the Wave Motion Engine, and sent to Iscandar.

text: The shape of Earth is approximately oblate spheroidal. Due to rotation, the Earth is flattened along the geographic axis and bulging around the equator. The diameter of the Earth at the equator is  larger than the pole-to-pole diameter. Thus the point on the surface farthest from Earth's center of mass is the summit of the equatorial Chimborazo volcano in Ecuador. The average diameter of the reference spheroid is . Local topography deviates from this idealized spheroid, although on a global scale these deviations are small compared to Earth's radius: The maximum deviation of only 0.17% is at the Mariana Trench ( below local sea level), whereas Mount Everest ( above local sea level) represents a deviation of 0.14%.

text: The shape of Earth is approximately

text: oblate spheroid

text: al. Due to

text: rotation

text: , the Earth is flattened along the geographic axis and

text: bulging

text: around the

text: equator

text: . The diameter of the Earth at the equator is  larger than the

text: pole

text: -to-pole diameter. Thus the point on the surface farthest from Earth's

text: center of mass

text: is the summit of the equatorial

text: Chimborazo

text: volcano in

text: Ecuador

text: . The average diameter of the reference spheroid is . Local

text: topography

text: deviates from this idealized spheroid, although on a global scale these deviations are small compared to Earth's radius: The maximum deviation of only 0.17% is at the

text: Mariana Trench

text: ( below local sea level), whereas

text: Mount Everest

text: ( above local sea level) represents a deviation of 0.14%.

text: The expression figure of the Earth has various meanings in geodesy according to the way it is used and the precision with which the Earth's size and shape is to be defined. While the sphere is a close approximation of the true figure of the Earth and satisfactory for many purposes, geodesists have developed a number of models to represent a closer approximation to the shape of the Earth.

text: The expression figure of the Earth has various meanings in

text: geodesy

text: according to the way it is used and the precision with which the

text: Earth

text: 's size and shape is to be defined. While the

text: sphere

text: is a close approximation of the true figure of the Earth and satisfactory for many purposes,

text: geodesist

text: s have developed a number of models to represent a closer approximation to the shape of the Earth.

text: In The CW's The Flash, Earth-3 is the home planet of Jay Garrick (John Wesley Shipp). In the season 3 episode "The Present", Barry Allen (Grant Gustin) visits Garrick on Earth-3 to seek advice on stopping Savitar.

text: In

text: The CW

text: 's

text: The Flash

text: , Earth-3 is the home planet of

text: Jay Garrick

text: John Wesley Shipp

text: ). In the season 3 episode "The Present", Barry Allen (

text: Grant Gustin

text: ) visits Garrick on Earth-3 to seek advice on stopping

text: Savitar

text: Strange Days on Planet Earth

text: Strange Days on Planet Earth

text: Revolving around the Central Fire above Earth were the Moon, the Sun, the planets, and finally—perhaps fixed and not rotating at all—were the stars. Revolving around the Central Fire below Earth was another hypothetical astronomical object, the Counter-Earth. Whether Philolaus believed Earth to be round or flat—there is "no explicit statement about the shape of the earth in Philolaus' system"—he did not believe the earth rotated, so that the Counter-Earth and the Central Fire were both not visible from Earth's surface—or at least not from the hemisphere where Greece was located.

text: Revolving around the Central Fire above Earth were the Moon, the Sun, the planets, and finally—perhaps fixed and not rotating at all—were the stars. Revolving around the Central Fire below Earth was another hypothetical astronomical object, the

text: Counter-Earth

text: . Whether Philolaus believed Earth to be round or flat—there is "no explicit statement about the shape of the earth in Philolaus' system"—he did not believe the earth rotated, so that the Counter-Earth and the Central Fire were both not visible from Earth's surface—or at least not from the hemisphere where Greece was located.

text: A normal mechanical clock could be used to produce an extremely simple orrery with the Sun in the centre, Earth on the minute hand and Jupiter on the hour hand; Earth would make 12 revolutions around the Sun for every 1 revolution of Jupiter. Note however that Jupiter's actual year is 11.86 Earth years long, so this particular example would lose accuracy rapidly. A real orrery would be more accurate and include more planets, and would perhaps make the planets rotate as well.

text: A normal mechanical clock could be used to produce an extremely simple orrery with the Sun in the centre,

text: Earth

text: on the minute hand and

text: Jupiter

text: on the hour hand; Earth would make 12 revolutions around the Sun for every 1 revolution of Jupiter. Note however that Jupiter's actual year is 11.86 Earth years long, so this particular example would lose accuracy rapidly. A real orrery would be more accurate and include more planets, and would perhaps make the planets rotate as well.

text: Terra Nova – also known as Eta Cassiopeia III, was one of the first Earth-colonized planets. Terra Nova was Earth's "great experiment," and was an early human colonization mission, which set its sights on the closest habitable planet from Earth. The world was 20 light-years from Earth, and the early warp drive colony ship heading there took 9 years to reach it. All adults from the original colony were killed after a radioactive asteroid struck the planet. The children survived by going underground and living in caves.

text: Terra Nova – also known as

text: Eta Cassiopeia

text: III, was one of the first Earth-colonized planets. Terra Nova was Earth's "great experiment," and was an early human colonization mission, which set its sights on the closest

text: habitable planet

text: from Earth. The world was 20

text: light-year

text: s from Earth, and the early

text: warp drive

text: colony ship heading there took 9 years to reach it. All adults from the original colony were killed after a radioactive asteroid struck the planet. The children survived by going underground and living in caves.

text: To get to the sun, it is actually not necessary to use a Δv of 24 km/s. One can use 8.8 km/s to go very far away from the sun, then use a negligible Δv to bring the angular momentum to zero, and then fall into the sun. This can be considered a sequence of two Hohmann transfers, one up and one down. Also, the table does not give the values that would apply when using the moon for a gravity assist. There are also possibilities of using one planet, like Venus which is the easiest to get to, to assist getting to other planets or the sun. The Galileo spacecraft used Venus once and Earth twice in order to reach Jupiter.

text: To get to the sun, it is actually not necessary to use a Δv of 24 km/s. One can use 8.8 km/s to go very far away from the sun, then use a negligible Δv to bring the angular momentum to zero, and then fall into the sun. This can be considered a sequence of two Hohmann transfers, one up and one down. Also, the table does not give the values that would apply when using the moon for a

text: gravity assist

text: . There are also possibilities of using one planet, like Venus which is the easiest to get to, to assist getting to other planets or the sun. The

text: Galileo spacecraft

text: used Venus once and Earth twice in order to reach Jupiter.

text: COROT-7b (previously named COROT-Exo-7b) is an exoplanet orbiting around the star COROT-7, in the constellation Monoceros, at 489 light years from Earth. It was first detected photometrically by the French-led COROT mission and reported in February 2009. Until the announcement of Kepler-10b in January 2011, it was the smallest exoplanet to have its diameter measured, at 1.58 times that of the Earth (which would give it a volume 3.95 times Earth's), and the first potential extrasolar terrestrial planet to be found. The planet is also notable for its very short orbital period, revolving around its host star in about 20 hours.

text: COROT-7b (previously named COROT-Exo-7b) is an

text: exoplanet

text: orbiting around the

text: star

text: , in the

text: constellation

text: Monoceros

text: , at 489

text: light years

text: from

text: Earth

text: . It was first detected

text: photometrically

text: by the French-led

text: COROT

text: mission and reported in February 2009. Until the announcement of

text: in January 2011, it was the smallest exoplanet to have its diameter measured, at 1.58 times that of the

text: Earth

text: (which would give it a volume 3.95 times Earth's), and the first potential extrasolar

text: terrestrial planet

text: to be found. The planet is also notable for its very short

text: orbital period

text: , revolving around its host star in about 20 hours.

text: Scientific findings since the 1990s have greatly influenced the scope of the fields of astrobiology, models of planetary habitability and the search for extraterrestrial intelligence (SETI). NASA and the SETI Institute have proposed categorising the increasing number of planets found using a measure called the Earth Similarity Index (ESI) based on mass, radius and temperature. According to this measure, as of 23 July 2015, the confirmed planet currently thought to be most similar to Earth on mass, radius and temperature is Kepler-438b. Scientists estimate that there may be billions of Earth-size planets within the Milky Way galaxy alone.

text: Scientific findings since the 1990s have greatly influenced the scope of the fields of

text: astrobiology

text: , models of

text: planetary habitability

text: and the

text: search for extraterrestrial intelligence

text: (SETI).

text: NASA

text: and the

text: SETI Institute

text: have proposed categorising the increasing number of planets found using a measure called the

text: Earth Similarity Index

text: (ESI) based on mass, radius and temperature. According to this measure, as of 23 July 2015, the confirmed planet currently thought to be

entity_name: List of potentially habitable exoplanets

text: most similar to Earth

text: on mass, radius and temperature is

text: . Scientists estimate that there may be billions of Earth-size planets within the

text: Milky Way

text: galaxy alone.

text: There are a number of songs about the planet which could be regarded as anthems, reflecting rising planetary consciousness among people across the world. One is "World Anthem" by the Mindshare Institute and Foundation. Other songs on the same theme include "Earth Anthem" by The Turtles, "Earth Anthem" by Dan Fogelberg, "Mother Earth (Natural Anthem)" by Neil Young, "Earth Song" by Michael Jackson, "Earth Hour Anthem" by Andrew Huang and "Earth Anthem" by Abhay Kumar. The "Earth Day Anthem" lyrics by William Wallace (and sometimes the original lyrics by Barbara George) is widely sung to the tune of "ode to Joy' by Ludwig van Beethoven, to celebrate Earth Day.

text: There are a number of songs about the planet which could be regarded as anthems, reflecting rising

text: planetary consciousness

text: among people across the world. One is "World Anthem" by the Mindshare Institute and Foundation. Other songs on the same theme include "Earth Anthem" by

text: The Turtles

text: , "Earth Anthem" by

text: Dan Fogelberg

text: , "Mother Earth (Natural Anthem)" by

text: Neil Young

text: Earth Song

text: " by

text: Michael Jackson

text: Earth Hour

text: Anthem" by Andrew Huang and "

text: Earth Anthem

text: " by

text: Abhay Kumar

text: . The "Earth Day Anthem" lyrics by William Wallace (and sometimes the original lyrics by Barbara George) is widely sung to the tune of "ode to Joy' by Ludwig van Beethoven, to celebrate

text: Earth Day

text: In the comic book series In Valen's Name, which is considered canonical, the ancient, decaying Babylon 4 is found in orbit of an uninhabited planet. It is drawn into the gravity well and burns up, but not before Delenn is able to view accounts of Valen's life by his three most trusted friends. The last message on the crystals is a message by Sinclair to the B5 crew, in which he apologizes for his decision not to prevent the Earth-Minbari War, stating that it was the only way for a greater good, the Babylon stations, to come to pass.

text: In the comic book series

text: In Valen's Name

text: , which is considered

text: canonical

text: , the ancient, decaying Babylon 4 is found in orbit of an uninhabited planet. It is drawn into the gravity well and burns up, but not before Delenn is able to view accounts of Valen's life by his three most trusted friends. The last message on the crystals is a message by Sinclair to the B5 crew, in which he apologizes for his decision not to prevent the

text: Earth-Minbari War

text: , stating that it was the only way for a greater good, the Babylon stations, to come to pass.

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: Magnetic declination should not be confused with magnetic inclination, also known as magnetic dip, which is the angle that the Earth's magnetic field lines make with the downward side of the horizontal plane.

text: Magnetic declination should not be confused with

text: magnetic inclination

text: , also known as magnetic dip, which is the angle that the Earth's magnetic field lines make with the downward side of the horizontal plane.

text: The game's plot describes a journey through a child's emotions and anxieties. After befriending the monster, the boy leaves Earth on the creature's back to look for life elsewhere in the galaxy. He hopes to find someone to relate to. The hollow planet Gravida's surface is patrolled by a creature that complains of stomach pains. This larger creature is followed by several tiny creatures, some of which ride on its back. One of these smaller inhabitants has fallen into the core of Gravida. Though it is isolated and lonely, the creature consoles itself that nobody can harm it. The planet Malaisus is composed of water, with a monster identical to the player's swimming around with a shoal of fish. The monster tells the player to leave. Planet Bibulon has two faces on opposite sides, one angry and one happy. A two-faced creature travels across the surface; one is happy and the other morose. Bibulon is orbited by four moons, each of which has differing opinions on an unnamed man or boy. When players find the planet Debasa, they discover that it is surrounded by a green fog. Gravity is very intense within the fog. Four orbiting satellites produce the fog, which has trapped two boys. Earth shrinks slightly after each planet has been completed. After restoring color to all the surrounding planets, the game is completed by returning to Earth. The Earth has shrunk until it is only slightly larger than the monster; it is destroyed when the boy and his monster land. Both fly upwards and land on the moon, where the boy is free to craft a future of his choosing.

text: The Earth's axis shifted by estimates of between  and . This deviation led to a number of small planetary changes, including the length of a day, the tilt of the Earth, and the Chandler wobble. The speed of the Earth's rotation increased, shortening the day by 1.8 microseconds due to the redistribution of Earth's mass. The axial shift was caused by the redistribution of mass on the Earth's surface, which changed the planet's moment of inertia. Because of conservation of angular momentum, such changes of inertia result in small changes to the Earth's rate of rotation. These are expected changes for an earthquake of this magnitude. The earthquake also generated infrasound waves detected by perturbations in the orbit of the GOCE satellite, which thus serendipitously became the first seismograph in orbit.

text: The Earth's

text: axis

text: shifted by estimates of between  and . This deviation led to a number of small planetary changes, including the

text: length of a day

text: , the

text: tilt of the Earth

text: , and the

text: Chandler wobble

text: . The speed of the Earth's rotation increased, shortening the day by 1.8

text: microsecond

text: s due to the redistribution of Earth's mass. The axial shift was caused by the redistribution of mass on the Earth's surface, which changed the planet's

text: moment of inertia

text: . Because of

text: conservation of angular momentum

text: , such changes of

text: inertia

text: result in small changes to the Earth's rate of rotation. These are expected changes for an earthquake of this magnitude. The earthquake also generated infrasound waves detected by perturbations in the orbit of the

entity_name: Gravity Field and Steady-State Ocean Circulation Explorer

text: GOCE

text: satellite, which thus

entity_name: Role of chance in scientific discoveries

text: serendipitously

text: became the first seismograph in orbit.

text: Towards the end of the series, Darkseid launches a second invasion of Earth, which is depicted in both Earth 2 and the weekly series Earth 2: World's End. Another weekly series, The New 52: Futures End, depicts a possible future in which refugees from a destroyed Earth 2 come to Earth 0 and prompt society to fracture. Over the course of the series, several new characters are introduced, such as Yolanda Montez, an Avatar of the Red who is a counterpart of Alan Scott; a second Red Arrow, an Earth 2 equivalent of Oliver Queen; and Dick Grayson, a journalist who goes on a mission to find his son after his wife Barbara Gordon is killed during the invasion. Others change alignment; Wonder Woman and Steppenwolf's daughter Fury sides with Mister Miracle and the other heroes after Big Barda reveals her loyalty to Darkseid. Huntress and Power Girl return to Earth 2 as well to take part in a mad scramble to save the Earth and then later, to save its people along with a computerised record of human culture and life on Earth created by Bruce Wayne. In Earth 2: World's End #11, it is revealed that Highfather made a deal with Darkseid that he would not interfere with Darkseid's plans for conquest so long as Darkseid only preyed upon one Earth of the Multiverse, which was Earth 2, explaining the recurrent tragedies faced by this world in comparison to others. In the end, Darkseid is successful, and the Earth is destroyed, and attempts to take Earth 2's refugees to Earth 0 are prevented by a time travelling Tim Drake in Futures End. Just as the world ends, several of the Wonders are sent to the planet Telos by Brainiac, where they confront their counterparts from various parallel worlds, both present and extinct, in the Convergence miniseries. Over the course of the series, Batman dies and Dick Grayson, inspired by his Batman counterparts from other worlds, takes up the mantle from Thomas Wayne. Ultimately, the planet Telos is terraformed into a new Earth-like planet and sent to the Earth 2 dimension as a new home for its refugees. The heroes' fraught attempts at forming a new society, rapidly augmented by Terry Sloan's technology, is depicted in the follow-on series Earth 2: Society (Aug. 2015 - Feb. 2017).

text: Towards the end of the series, Darkseid launches a second invasion of Earth, which is depicted in both Earth 2 and the weekly series Earth 2: World's End. Another weekly series,

text: The New 52: Futures End

text: , depicts a possible future in which refugees from a destroyed Earth 2 come to Earth 0 and prompt society to fracture. Over the course of the series, several new characters are introduced, such as

text: Yolanda Montez

text: , an Avatar of the Red who is a counterpart of Alan Scott; a second Red Arrow, an Earth 2 equivalent of

text: Oliver Queen

text: ; and

text: Dick Grayson

text: , a journalist who goes on a mission to find his son after his wife

text: Barbara Gordon

text: is killed during the invasion. Others change alignment; Wonder Woman and Steppenwolf's daughter

text: Fury

text: sides with Mister Miracle and the other heroes after Big Barda reveals her loyalty to Darkseid. Huntress and Power Girl return to Earth 2 as well to take part in a mad scramble to save the Earth and then later, to save its people along with a computerised record of human culture and life on Earth created by Bruce Wayne. In Earth 2: World's End #11, it is revealed that

text: Highfather

text: made a deal with

text: Darkseid

text: that he would not interfere with Darkseid's plans for conquest so long as Darkseid only preyed upon one Earth of the Multiverse, which was Earth 2, explaining the recurrent tragedies faced by this world in comparison to others. In the end, Darkseid is successful, and the Earth is destroyed, and attempts to take Earth 2's refugees to Earth 0 are prevented by a time travelling

text: Tim Drake

text: in Futures End. Just as the world ends, several of the Wonders are sent to the planet Telos by

text: Brainiac

text: , where they confront their counterparts from various parallel worlds, both present and extinct, in the

text: Convergence

text: miniseries. Over the course of the series, Batman dies and Dick Grayson, inspired by his Batman counterparts from other worlds, takes up the mantle from Thomas Wayne. Ultimately, the planet Telos is terraformed into a new Earth-like planet and sent to the Earth 2 dimension as a new home for its refugees. The heroes' fraught attempts at forming a new society, rapidly augmented by Terry Sloan's technology, is depicted in the follow-on series Earth 2: Society (Aug. 2015 - Feb. 2017).

text: Eventually, when Copernicus's heliocentric model was accepted over the geocentric, Earth was placed among the planets and the Sun and Moon were reclassified, necessitating a conceptual revolution in the understanding of planets. As the historian of science Thomas Kuhn noted in his book, The Structure of Scientific Revolutions:

text: Eventually, when Copernicus's

text: heliocentric model

text: was accepted over the

text: geocentric

text: Earth

text: was placed among the planets and the Sun and Moon were reclassified, necessitating a conceptual revolution in the understanding of planets. As the

text: historian of science

text: Thomas Kuhn

text: noted in his book,

text: The Structure of Scientific Revolutions

text: "Revolution Earth" is the fourth single released by The B-52's from their 1992 album Good Stuff.

text: "Revolution Earth" is the fourth single released by

text: The B-52's

text: from their 1992 album

text: Good Stuff

text: All magnets have two poles, where the lines of magnetic flux enter and emerge. By analogy with the Earth's magnetic field, these are called the magnet's "north" and "south" poles. The convention in early compasses was to call the end of the needle pointing to the Earth's North Magnetic Pole the "north pole" (or "north-seeking pole") and the other end the "south pole" (the names are often abbreviated to "N" and "S"). Because opposite poles attract, this definition means that the Earth's North Magnetic Pole is actually a magnetic south pole and the Earth's South Magnetic Pole is a magnetic north pole.

text: All

text: magnet

text: s have two poles, where the lines of

text: magnetic flux

text: enter and emerge. By analogy with the Earth's magnetic field, these are called the magnet's "north" and "south" poles. The convention in early

text: compass

text: es was to call the end of the needle pointing to the Earth's North Magnetic Pole the "north pole" (or "north-seeking pole") and the other end the "south pole" (the names are often abbreviated to "N" and "S"). Because opposite poles attract, this definition means that the Earth's North Magnetic Pole is actually a magnetic south pole and the Earth's South Magnetic Pole is a magnetic north pole.

text: In the Robot series, the inhabitants of these planets are still aware that their ancestors came from Earth, but this does not make them fond of the place. Rather, they develop a racist theory by which "the best strains" had left Earth to colonize the other planets and left "the inferior strains" behind. However, they have no choice but to ask the help of the protagonist, a detective from the despised Earth, to solve murder mysteries which baffle their own police. Afterwards, Earth embarks on a major new campaign of space colonization, with the hope that the new colonists will prove more faithful to the Mother Planet than the earlier ones. However, in the end of the series, the Earth is doomed to a slow radioactive process that will leave the planet uninhabitable, causing a more rapid expansion of colonization from Earth.

text: In the

text: Robot series

text: , the inhabitants of these planets are still aware that their ancestors came from Earth, but this does not make them fond of the place. Rather, they develop a racist theory by which "the best strains" had left Earth to colonize the other planets and left "the inferior strains" behind. However, they have no choice but to ask the help of the protagonist, a detective from the despised Earth, to solve murder mysteries which baffle their own police. Afterwards, Earth embarks on a major new campaign of space colonization, with the hope that the new colonists will prove more faithful to the Mother Planet than the earlier ones. However, in the end of the series, the Earth is doomed to a slow radioactive process that will leave the planet uninhabitable, causing a more rapid expansion of colonization from Earth.

text: Whether a body is in the circumstellar habitable zone of its host star is dependent on the radius of the planet's orbit (for natural satellites, the host planet's orbit), the mass of the body itself, and the radiative flux of the host star. Given the large spread in the masses of planets within a circumstellar habitable zone, coupled with the discovery of super-Earth planets which can sustain thicker atmospheres and stronger magnetic fields than Earth, circumstellar habitable zones are now split into two separate regions—a "conservative habitable zone" in which lower-mass planets like Earth or Venus can remain habitable, complemented by a larger "extended habitable zone" in which super-Earth planets, with stronger greenhouse effects, can have the right temperature for liquid water to exist at the surface.

text: Whether a body is in the circumstellar habitable zone of its host star is dependent on the radius of the planet's orbit (for natural satellites, the host planet's orbit), the mass of the body itself, and the radiative flux of the host star. Given the large spread in the masses of planets within a circumstellar habitable zone, coupled with the discovery of super-Earth planets which can sustain thicker atmospheres and stronger magnetic fields than Earth, circumstellar habitable zones are now split into two separate regions—a "conservative habitable zone" in which lower-mass planets like Earth or Venus can remain habitable, complemented by a larger "extended habitable zone" in which super-Earth planets, with stronger

text: greenhouse effect

text: s, can have the right temperature for liquid water to exist at the surface.

text: Earth's surface is situated fairly deep in a gravity well. The escape velocity required to get out of it is 11.2 kilometers/second. As human beings evolved in a gravitational field of 1g (9.8 m/s²), an ideal propulsion system would be one that provides a continuous acceleration of 1g (though human bodies can tolerate much larger accelerations over short periods). The occupants of a rocket or spaceship having such a propulsion system would be free from all the ill effects of free fall, such as nausea, muscular weakness, reduced sense of taste, or leaching of calcium from their bones.

text: Earth's surface is situated fairly deep in a

text: gravity well

text: . The

text: escape velocity

text: required to get out of it is 11.2 kilometers/second. As human beings evolved in a gravitational field of 1g (9.8 m/s²), an ideal propulsion system would be one that provides a continuous acceleration of 1g (though human bodies can tolerate much larger accelerations over short periods). The occupants of a rocket or spaceship having such a propulsion system would be free from all the ill effects of

text: free fall

text: , such as nausea, muscular weakness, reduced sense of taste, or

text: leaching

text: of calcium from their bones.

text: If a straight line were drawn from the rising sun to the setting sun, and from the sun at noon and at midnight, both of these lines would pass through the Earth's center and the equator would intersect these lines. This is not so when the sun has north or south declination because its apparent motion will have an angle to the above described plane or lines, with the Earth's center, equal to the amount of the sun's declination north or south. Then it will be seen, that when the sun has north or south declination, and the earth is regarded as the center of its revolutions the plane just mentioned becomes conical.

text: The Earth's magnetic field strength was measured by Carl Friedrich Gauss in 1835 and has been repeatedly measured since then, showing a relative decay of about 10% over the last 150 years. The Magsat satellite and later satellites have used 3-axis vector magnetometers to probe the 3-D structure of the Earth's magnetic field. The later Ørsted satellite allowed a comparison indicating a dynamic geodynamo in action that appears to be giving rise to an alternate pole under the Atlantic Ocean west of S. Africa.

text: The Earth's magnetic field strength was measured by

text: Carl Friedrich Gauss

text: in 1835 and has been repeatedly measured since then, showing a relative decay of about 10% over the last 150 years. The

text: Magsat

text: satellite and later satellites have used 3-axis vector magnetometers to probe the 3-D structure of the Earth's magnetic field. The later

text: Ørsted satellite

text: allowed a comparison indicating a dynamic geodynamo in action that appears to be giving rise to an alternate pole under the Atlantic Ocean west of S. Africa.

text: Many tropical areas have a dry and wet season.  The wet season, rainy season or green season, is the time of year, ranging from one or more months, when most of the average annual rainfall in a region falls.  Areas with wet seasons are disseminated across portions of the tropics and subtropics.  Under the Köppen climate classification, for tropical climates, a wet season month is defined as a month where average precipitation is  or more.  Tropical rainforests technically do not have dry or wet seasons, since their rainfall is equally distributed through the year.  Some areas with pronounced rainy seasons see a break in rainfall during mid-season when the intertropical convergence zone or monsoon trough moves poleward of their location during the middle of the warm season.

text: Many tropical areas have a dry and wet season.  The

text: wet season

text: , rainy season or green season, is the time of year, ranging from one or more months, when most of the average annual

text: rainfall

text: in a region falls.  Areas with wet seasons are disseminated across portions of the tropics and

text: subtropics

text: .  Under the

text: Köppen climate classification

text: , for

text: tropical climate

text: s, a wet season month is defined as a month where average precipitation is  or more.

text: Tropical rainforest

text: s technically do not have dry or wet seasons, since their rainfall is equally distributed through the year.  Some areas with pronounced rainy seasons see a break in rainfall during mid-season when the

text: intertropical convergence zone

text: or

text: monsoon trough

text: moves poleward of their location during the middle of the warm season.

text: Some of the earliest recorded observations ever made through a telescope, Galileo's drawings on 28 December 1612 and 27 January 1613, contain plotted points that match up with what is now known to be the position of Neptune. On both occasions, Galileo seems to have mistaken Neptune for a fixed star when it appeared close—in conjunction—to Jupiter in the night sky; hence, he is not credited with Neptune's discovery. At his first observation in December 1612, Neptune was almost stationary in the sky because it had just turned retrograde that day. This apparent backward motion is created when Earth's orbit takes it past an outer planet. Because Neptune was only beginning its yearly retrograde cycle, the motion of the planet was far too slight to be detected with Galileo's small telescope. In July 2009, University of Melbourne physicist David Jamieson announced new evidence suggesting that Galileo was at least aware that the 'star' he had observed had moved relative to the fixed stars.

text: Some of the earliest recorded observations ever made through a

text: telescope

text: Galileo's

text: drawings on 28 December 1612 and 27 January 1613, contain plotted points that match up with what is now known to be the position of Neptune. On both occasions, Galileo seems to have mistaken Neptune for a

text: fixed star

text: when it appeared close—in

text: conjunction

text: —to Jupiter in the

text: night sky

text: ; hence, he is not credited with Neptune's discovery. At his first observation in December 1612, Neptune was almost stationary in the sky because it had just turned

text: retrograde

text: that day. This apparent backward motion is created when Earth's orbit takes it past an outer planet. Because Neptune was only beginning its yearly retrograde cycle, the motion of the planet was far too slight to be detected with Galileo's small

text: telescope

text: . In July 2009,

text: University of Melbourne

text: physicist David Jamieson announced new evidence suggesting that Galileo was at least aware that the 'star' he had observed had moved relative to the

text: fixed stars

text: As noted by Copernicus himself, the notion that the Earth rotates is very old, dating at least to Philolaus (c. 450 BC), Heraclides Ponticus (c. 350 BC) and Ecphantus the Pythagorean. Roughly a century before Copernicus, the Christian scholar Nicholas of Cusa also proposed that the Earth rotates on its axis in his book, On Learned Ignorance (1440). Al-Sijzi also proposed that the Earth rotates on its axis. Empirical evidence for the Earth's rotation on its axis, using the phenomenon of comets, was given by Tusi (1201–1274) and Ali Qushji (1403–1474).

text: As noted by Copernicus himself, the notion that the

text: Earth rotates

text: is very old, dating at least to

text: Philolaus

text: (c. 450 BC),

text: Heraclides Ponticus

text: (c. 350 BC) and

text: Ecphantus the Pythagorean

text: . Roughly a century before Copernicus, the Christian scholar

text: Nicholas of Cusa

text: also proposed that the Earth rotates on its axis in his book, On Learned Ignorance (1440). Al-Sijzi also proposed that the Earth rotates on its axis.

text: Empirical evidence

text: for the Earth's rotation on its axis, using the phenomenon of

text: comet

text: s, was given by

text: Tusi

text: (1201–1274) and

text: Ali Qushji

text: Events of the novels take place on several planets: Earth; the Concilium Orb, an artificial planet constructed by the Lylmik, and the seat of the galactic Council; Hibernia, an Irish-dominated human colony; Caledonia, a Scottish-dominated human colony; Denali, a snow-covered planet popular as a holiday destination; and the cosmopolitan human colony planet of Okanagon.  Apart from the home planets and colonies of the alien races, a number of other planets are also mentioned in passing.

text: In its yearly trek around the sun, asteroid  spends about half of the time closer to the sun than Earth is (that is, the asteroid is inside the Earth's orbit) and passes ahead of our planet, and about half of the time farther away (crosses outside Earth's orbit), causing it to fall behind. Its orbit is also tilted a little, causing it to bob up and then down once each year through Earth's orbital plane. In effect, this small asteroid is caught in a game of leap frog with Earth that will last for hundreds of years.

text: In its yearly trek around the sun, asteroid  spends about half of the time closer to the sun than Earth is (that is, the asteroid is inside the

text: Earth's orbit

text: ) and passes ahead of our planet, and about half of the time farther away (crosses outside Earth's orbit), causing it to fall behind. Its orbit is also tilted a little, causing it to bob up and then down once each year through Earth's orbital plane. In effect, this small asteroid is caught in a game of leap frog with Earth that will last for hundreds of years.

text: The planet orbits the star in a so-called "torch orbit". One revolution around the star takes only a little less than three Earth days to complete. The planet is less massive than Jupiter (0.36 times Jupiter's mass, or 114 times Earth's mass) but more massive than Saturn. The temperature of the planet was initially estimated on the basis of 0.3 Bond albedo to be about 1540 K, above the predicted temperature of HD 209458 b (1400K), which had inaugurated the category of Chthonian "hell planet". Its day-side brightness temperature was subsequently directly measured as 2,300 ± 200 K by comparing the combined emissions of star and planet at 8 μm wavelength before and during a transit event. This is around the boiling point of silicon and well above the melting point of iron.

text: The planet orbits the star in a so-called "torch orbit". One revolution around the star takes only a little less than three Earth

text: day

text: s to complete. The planet is less massive than

text: Jupiter

text: (0.36 times Jupiter's mass, or 114 times Earth's mass) but more massive than

text: Saturn

text: . The temperature of the planet was initially estimated on the basis of 0.3 Bond

text: albedo

text: to be about 1540

text: K

text: , above the predicted temperature of

text: HD 209458 b

text: (1400K), which had inaugurated the category of

text: Chthonian

text: "hell planet". Its day-side brightness temperature was subsequently directly measured as 2,300 ± 200 K by comparing the combined emissions of star and planet at 8 μm wavelength before and during a transit event. This is around the boiling point of silicon and well above the melting point of iron.

text: Twenty-seven-year-old Howard the Duck lives on Duckworld, a planet similar to Earth, but inhabited by anthropomorphic ducks and orbited by twin moons. As he is reading the latest issue of Playduck magazine, his armchair begins to quake violently and propels him out of his apartment building and into outer space; Howard eventually lands on Earth, in Cleveland, Ohio. Upon arriving, Howard encounters a woman being attacked by thugs. He defeats them using a unique style of martial arts. After the thugs flee, the woman introduces herself as Beverly Switzler, and decides to take Howard to her apartment and let him spend the night. The following day, Beverly takes Howard to Phil Blumbertt, a scientist who Beverly hopes can help Howard return to his world. After Phil is revealed to be only a janitor, Howard resigns himself to life on Earth and rejects Beverly's aid. He soon applies for a job as a janitor at a local romance spa. Howard soon quits and rejoins Beverly, who plays in a band called Cherry Bomb. At the club where Cherry Bomb is performing, Howard comes across their manager, and confronts him when he insults the band. A fight breaks out, in which Howard is victorious.

text: Twenty-seven-year-old

text: Howard the Duck

text: lives on Duckworld, a planet similar to Earth, but inhabited by

text: anthropomorphic

text: ducks and orbited by twin moons. As he is reading the latest issue of Playduck magazine, his armchair begins to quake violently and propels him out of his apartment building and into outer space; Howard eventually lands on

text: Earth

text: , in

text: Cleveland

text: , Ohio. Upon arriving, Howard encounters a woman being attacked by thugs. He defeats them using a unique style of martial arts. After the thugs flee, the woman introduces herself as

text: Beverly Switzler

text: , and decides to take Howard to her apartment and let him spend the night. The following day, Beverly takes Howard to Phil Blumbertt, a scientist who Beverly hopes can help Howard return to his world. After Phil is revealed to be only a janitor, Howard resigns himself to life on Earth and rejects Beverly's aid. He soon applies for a job as a janitor at a local romance spa. Howard soon quits and rejoins Beverly, who plays in a band called Cherry Bomb. At the club where Cherry Bomb is performing, Howard comes across their manager, and confronts him when he insults the band. A fight breaks out, in which Howard is victorious.

text: The Earth rotates once in about 24 hours with respect to the sun and once every 23 hours, 56 minutes and 4 seconds with respect to the stars (see below). Earth's rotation is slowing slightly with time; thus, a day was shorter in the past. This is due to the tidal effects the Moon has on Earth's rotation. Atomic clocks show that a modern-day is longer by about 1.7 milliseconds than a century ago, slowly increasing the rate at which UTC is adjusted by leap seconds. Analysis of historical astronomical records shows a slowing trend of 2.3 milliseconds per century since the 8th century BCE.

text: The Earth rotates once in about 24 hours with respect to the sun and once every 23 hours, 56 minutes and 4 seconds with respect to the stars (

text: see below

text: ). Earth's rotation is slowing slightly with time; thus, a day was shorter in the past. This is due to the

text: tidal effects

text: the

text: Moon

text: has on Earth's rotation.

text: Atomic clock

text: s show that a modern-day is longer by about 1.7

text: millisecond

text: s than a century ago, slowly increasing the rate at which

text: UTC

text: is adjusted by

text: leap second

text: s. Analysis of historical astronomical records shows a slowing trend of 2.3 milliseconds per century since the 8th century BCE.

text: In addition to the 12", the night version of "Planet Earth" was included on the EPs Nite Romantics and Carnival.

text: In addition to the 12", the night version of "Planet Earth" was included on the

text: EP

text: s Nite Romantics and

text: Carnival

text: New Rome tells Zerchi to proceed with Quo Peregrinatur and plan for departure within three days.  He appoints Brother Joshua as mission leader, telling him that this is an emergency plan for perpetuating the Church on the colony planets in the event of a nuclear war on Earth. The Order's Memorabilia will also accompany the mission. That night the Atlantic Confederacy launches an assault against Asian Coalition space platforms. The Asian Coalition responds by using a nuclear weapon against the Confederacy capital city of Texarkana. A ten-day cease-fire is issued by the World Court. Brother Joshua and the space-trained monks and priests depart on a secret, chartered flight for New Rome, hoping to leave Earth on the starship before the cease-fire ends.

text: Earth's rotation period relative to the Sun (true noon to true noon) is its true solar day or apparent solar day. It depends on the Earth's orbital motion and is thus affected by changes in the eccentricity and inclination of Earth's orbit. Both vary over thousands of years so the annual variation of the true solar day also varies. Generally, it is longer than the mean solar day during two periods of the year and shorter during another two. The true solar day tends to be longer near perihelion when the Sun apparently moves along the ecliptic through a greater angle than usual, taking about  longer to do so. Conversely, it is about  shorter near aphelion. It is about  longer near a solstice when the projection of the Sun's apparent movement along the ecliptic onto the celestial equator causes the Sun to move through a greater angle than usual. Conversely, near an equinox the projection onto the equator is shorter by about . Currently, the perihelion and solstice effects combine to lengthen the true solar day near  by  solar seconds, but the solstice effect is partially cancelled by the aphelion effect near  when it is only  longer. The effects of the equinoxes shorten it near  and  by  and , respectively.

text: Earth's

text: rotation period

text: relative to the Sun (true noon to true noon) is its true solar day or apparent solar day. It depends on the Earth's orbital motion and is thus affected by changes in the

text: eccentricity

text: and

text: inclination

text: of Earth's orbit. Both vary over thousands of years so the annual variation of the true solar day also varies. Generally, it is longer than the mean solar day during two periods of the year and shorter during another two. The true solar day tends to be longer near

text: perihelion

text: when the Sun apparently moves along the

text: ecliptic

text: through a greater angle than usual, taking about  longer to do so. Conversely, it is about  shorter near

text: aphelion

text: . It is about  longer near a

text: solstice

text: when the projection of the Sun's apparent movement along the ecliptic onto the

text: celestial equator

text: causes the Sun to move through a greater angle than usual. Conversely, near an

text: equinox

text: the projection onto the equator is shorter by about . Currently, the perihelion and solstice effects combine to lengthen the true solar day near  by  solar seconds, but the solstice effect is partially cancelled by the aphelion effect near  when it is only  longer. The effects of the equinoxes shorten it near  and  by  and , respectively.

text: The planet is a typical "hot Jupiter", a planet with a mass half that of Jupiter and orbital distance only 1/24th that of Earth from the Sun. One revolution around the star takes a little over three days to complete. The planet is slightly larger than Jupiter, probably due to the heat from the star.

text: The planet is a typical "

text: hot Jupiter

text: ", a planet with a mass half that of

text: Jupiter

text: and orbital distance only 1/24th that of Earth from the Sun. One revolution around the star takes a little over three

text: day

text: s to complete. The planet is slightly larger than

text: Jupiter

text: , probably due to the heat from the star.

text: Pendor is a fictional ringworld from the Pendorwright stories written by Elf Sternberg. It rotates around a center star Pin, its day-night cycle simulated by a ring of shadow blocks rotating between Pendor and Pin, creating 292 day/night cycles per earth year. The system also includes a planet called Pandora, its moon Pindam and a space station called Parma.

text: Pendor is a fictional

text: ringworld

text: from the Pendorwright stories written by Elf Sternberg. It rotates around a center star Pin, its day-night cycle simulated by a ring of shadow blocks rotating between Pendor and Pin, creating 292 day/night cycles per earth year. The system also includes a planet called Pandora, its moon Pindam and a space station called Parma.

text: Once G has been found, the attraction of an object at the Earth's surface to the Earth itself can be used to calculate the Earth's mass and density:

text: Once G has been found, the attraction of an object at the Earth's surface to the Earth itself can be used to calculate the

text: Earth's mass

text: and density:

text: During their last days on the planet, the team on the planet see the obelisk sending a beam of light into the night sky. By the time Destiny is back in range, Young learns that several of them wish to stay on the planet, including Robert Caine (Tygh Runyan) who believes that a higher power is responsible for creating the planet as a "lifeline" for the expedition, as well as believing that the race responsible will find them and return them to Earth. Young goes down to the planet with the partially repaired shuttle, and offers it to those who wish to stay, so long as all the military personnel return to Destiny, otherwise everyone will be returned by force. With the military personnel back on Destiny, a few civilians remain on the planet while Destiny jumps back to FTL. In the end, the expedition enjoy a feast from the food they brought from the planet.

text: During their last days on the planet, the team on the planet see the obelisk sending a beam of light into the night sky. By the time Destiny is back in range, Young learns that several of them wish to stay on the planet, including Robert Caine (

text: Tygh Runyan

text: ) who believes that a higher power is responsible for creating the planet as a "lifeline" for the expedition, as well as believing that the race responsible will find them and return them to Earth. Young goes down to the planet with the partially repaired shuttle, and offers it to those who wish to stay, so long as all the military personnel return to Destiny, otherwise everyone will be returned by force. With the military personnel back on Destiny, a few civilians remain on the planet while Destiny jumps back to FTL. In the end, the expedition enjoy a feast from the food they brought from the planet.

text: Earth is the only known planet with seas of liquid water on its surface, although Mars possesses ice caps and similar planets in other solar systems may have oceans. It is still unclear where Earth's water came from, but, seen from space, our planet appears as a "blue marble" of its various forms: oceans, ice caps, clouds. Earth's  of sea contain about 97.2 percent of its known water and cover more than 70 percent of its surface. Another 2.15% of Earth's water is frozen, found in the sea ice covering the Arctic Ocean, the ice cap covering Antarctica and its adjacent seas, and various glaciers and surface deposits around the world. The remainder (about 0.65% of the whole) form underground reservoirs or various stages of the water cycle, containing the freshwater encountered and used by most terrestrial life: vapor in the air, the clouds it slowly forms, the rain falling from them, and the lakes and rivers spontaneously formed as its waters flow again and again to the sea. The sea's dominance of the planet is such that the British author Arthur C. Clarke once noted that "Earth" would have been better named "Ocean".

text: Earth

text: is the only known

text: planet

text: with seas of liquid

text: water

text: on its surface, although

text: Mars

text: possesses

text: ice caps

text: and

text: similar planets

text: in

text: other solar systems

text: may have oceans. It is still unclear

text: where Earth's water came from

text: , but, seen from

text: space

text: , our planet appears as a "

text: blue marble

text: " of its various forms: oceans, ice caps, clouds. Earth's  of sea contain

text: about 97.2 percent of its known water

text: and cover more than 70 percent of its surface. Another 2.15% of Earth's water is frozen, found in the sea ice covering the

text: Arctic Ocean

text: , the ice cap covering

text: Antarctica

text: and its

text: adjacent seas

text: , and various

text: glacier

text: s and surface deposits around the world. The remainder (about 0.65% of the whole) form

text: underground reservoirs

text: or various stages of the

text: water cycle

text: , containing the

text: freshwater

text: encountered and used by most

text: terrestrial life

text: vapor

text: in the

text: air

text: , the

text: cloud

text: s it slowly forms, the

text: rain

text: falling from them, and the

text: lake

text: s and

text: river

text: s spontaneously formed as its waters flow again and again to the sea. The sea's dominance of the planet is such that the British author

text: Arthur C. Clarke

text: once noted that "Earth" would have been better named "Ocean".

text: The concept underlying the album is, according to Graham, a tale of "one possible future of human failure [involving] the collapse of society due to overpopulation and pollution".  He further detailed the concept as a story humanity "realiz[ing] too late that the importance of their government, their nationalism, and their religions meant nothing in relation to the damage we are inflicting on our planet."  The concept extends to the album cover art, which portrays what Graham describes as "a small surviving group of revolutionaries [who] are biding time until their own demise. The body and the flag represent humanity, and are being ironically sacrificed to the earth...more fire, more smoke, more pollution. They know now that their revolution/realization happened too late, and that the earth will soon be on its own."

text: In an announcement on June 28, 2004, Cassini program scientists described the measurement of the rotational period of Saturn. Because there are no fixed features on the surface that can be used to obtain this period, the repetition of radio emissions was used. These new data agree with the latest values measured from Earth, and constitute a puzzle to the scientists. It turns out that the radio rotational period has changed since it was first measured in 1980 by Voyager 1, and that it is now 6 minutes longer. This does not indicate a change in the overall spin of the planet, but is thought to be due to movement of the source of the radio emissions to a different latitude, at which the rotation rate is different.

text: In an announcement on June 28, 2004, Cassini program scientists described the measurement of the rotational period of Saturn. Because there are no fixed features on the surface that can be used to obtain this period, the repetition of radio emissions was used. These new data agree with the latest values measured from Earth, and constitute a puzzle to the scientists. It turns out that the radio rotational period has changed since it was first measured in 1980 by

text: Voyager 1

text: , and that it is now 6 minutes longer. This does not indicate a change in the overall spin of the planet, but is thought to be due to movement of the source of the radio emissions to a different latitude, at which the rotation rate is different.

text: Kepler-11g is an exoplanet discovered in the orbit of the sunlike star Kepler-11 by the Kepler spacecraft, a NASA satellite tasked with searching for terrestrial planets. Kepler-11g is the outermost of the star's six planets. The planet orbits at a distance of nearly half the mean distance between Earth and the Sun. It completes an orbit every 118 days, placing it much further from its star than the system's inner five planets. Its estimated radius is a little over three times that of Earth, i.e. comparable to Neptune's size.  Kepler-11g's distance from the inner planets made its confirmation more difficult than that of the inner planets, as scientists had to work to exhaustively disprove all reasonable alternatives before Kepler-11g could be confirmed. The planet's discovery, along with that of the other Kepler-11 planets, was announced on February 2, 2011. According to NASA, the Kepler-11 planets form the flattest and most compact system yet discovered.

text: Kepler-11g is an

text: exoplanet

text: discovered in the orbit of the sunlike star

text: by the

text: Kepler spacecraft

text: , a

text: NASA

text: satellite tasked with searching for

text: terrestrial planet

text: s. Kepler-11g is the outermost of the star's six planets. The planet orbits at a distance of nearly half the

text: mean distance

text: between Earth and the

text: Sun

text: . It completes an orbit every 118 days, placing it much further from its star than the system's inner five planets. Its estimated radius is a little over three times that of

text: Earth

text: , i.e. comparable to Neptune's size.  Kepler-11g's distance from the inner planets made its confirmation more difficult than that of the inner planets, as scientists had to work to exhaustively disprove all reasonable alternatives before Kepler-11g could be confirmed. The planet's discovery, along with that of the other Kepler-11 planets, was announced on February 2, 2011. According to NASA, the Kepler-11 planets form the flattest and most compact system yet discovered.

text: The Martian year is treated as beginning near the equinox marking spring in the northern hemisphere of the planet.  Mars currently has an axial inclination similar to that of the Earth, so the Martian seasons are perceptible, though the greater eccentricity of Mars' orbit about the Sun compared with that of the Earth means that their significance is strongly amplified in the southern hemisphere and masked in the northern hemisphere.

text: The Martian year is treated as beginning near the

text: equinox

text: marking spring in the northern hemisphere of the planet.  Mars currently has an

text: axial inclination

text: similar to that of the

text: Earth

text: , so the Martian seasons are perceptible, though the greater

text: eccentricity

text: of Mars' orbit about the

text: Sun

text: compared with that of the Earth means that their significance is strongly amplified in the southern hemisphere and masked in the northern hemisphere.

text: An open question is why Bacon was moved to give a unified account of the motion of magnets and other natural movers. Graham Rees tentatively suggested (2006, p. liii) that Bacon tended to conceive related occurrences as part of a spectrum. It might have seemed to Bacon that magnets are part of a continuum encompassing the unturning Earth as well as the rotation-prone magnets on Earth's surface and the westward-hurtling planets above.

text: An open question is why Bacon was moved to give a unified account of the motion of magnets and other natural movers.

text: Graham Rees

text: tentatively suggested (2006, p. liii) that Bacon tended to conceive related occurrences as part of a spectrum. It might have seemed to Bacon that magnets are part of a continuum encompassing the unturning Earth as well as the rotation-prone magnets on Earth's surface and the westward-hurtling planets above.

text: On August 24, 2016, astronomers announced the discovery of a rocky planet in the habitable zone of Proxima Centauri, the closest star to Earth. Called Proxima b, the planet is 1.3 times the mass of Earth and has an orbital period of roughly 11.2 Earth days. However Proxima Centauri’s classification as a red dwarf casts doubts on the habitability of any exoplanets in its orbit due to low stellar flux, high probability of tidal locking, small circumstellar habitable zones and high stellar variation. Another likely candidate is Alpha Centauri, Earth’s nearest Sun-like star system 4.37 light years away. Estimates place the probability of finding a habitable planet around Alpha Centauri A or B at roughly 85%. Alpha Centauri is the target of several exoplanet-finding missions, including Breakthrough Starshot and Mission Centaur, the latter of which is chronicled in the 2016 documentary film, "The Search for Earth Proxima."

text: On August 24, 2016, astronomers announced the discovery of a rocky planet in the habitable zone of

text: Proxima Centauri

text: , the closest star to Earth. Called

text: Proxima b

text: , the planet is 1.3 times the mass of Earth and has an orbital period of roughly 11.2 Earth days. However Proxima Centauri’s classification as a red dwarf casts doubts on the habitability of any exoplanets in its orbit due to low stellar flux, high probability of tidal locking, small circumstellar habitable zones and high stellar variation. Another likely candidate is

text: Alpha Centauri

text: , Earth’s nearest Sun-like star system 4.37 light years away. Estimates place the probability of finding a habitable planet around Alpha Centauri A or B at roughly 85%. Alpha Centauri is the target of several exoplanet-finding missions, including

text: Breakthrough Starshot

text: and Mission Centaur, the latter of which is chronicled in the 2016 documentary film, "The Search for

text: Earth Proxima

text: Planet Earth examines the relationship between life and the physical planet throughout geologic history. The objectives range from recognizing cause and effect relationships to collecting and analyzing data for a long-term research project and then presenting the results. The students participate in two large projects during Planet Earth: The KT (Cretaceous-Tertiary) Debate and the Biodiversity Project. The KT Debate covers the various theories discussing the mass extinction of dinosaurs at the boundary between the Cretaceous and Tertiary periods and the possibility that the cause of the dinosaurs' mass extinction poses a threat to humanity today. The debate takes place over a week with students taking the role of senators, lobbyists, reporters and witnesses. The Biodiversity Project consists of students designing and completing a field study in which the relationship between the physical environment and the biodiversity of the Austin area is analyzed. Students working in pairs, trios, or solo select an organism and a city park to study.

text: The KMT, Korean Microlensing Telescope, is a 1.6m operated by KASI.The KMTNet aims primarily to discover extrasolar planets based on the analyses of gravitational microlensing phenomena, especially the detection of earth-mass planets in the habitable zone. The KMTNet system has a very competitive power for wide-field photometric survey sciences  that study supernovae, asteroids and external galaxies, for instance. Because the observation period of the Galactic bulge focuses on the primary science on extrasolar planets, the other science programs are performed in the season when the Galactic bulge is not observable.

text: In 499 CE, the Indian astronomer Aryabhata propounded a planetary model that explicitly incorporated Earth's rotation about its axis, which he explains as the cause of what appears to be an apparent westward motion of the stars. He also believed that the orbits of planets are elliptical.Aryabhata's followers were particularly strong in South India, where his principles of the diurnal rotation of Earth, among others, were followed and a number of secondary works were based on them.

text: In 499 CE, the Indian astronomer

text: Aryabhata

text: propounded a planetary model that explicitly incorporated

text: Earth's rotation

text: about its axis, which he explains as the cause of what appears to be an apparent westward motion of the stars. He also believed that the orbits of planets are

text: elliptical

text: .Aryabhata's followers were particularly strong in

text: South India

text: , where his principles of the diurnal rotation of Earth, among others, were followed and a number of secondary works were based on them.

text: Earth's magnetic field is not constant—the strength of the field and the location of its poles vary. Moreover, the poles periodically reverse their orientation in a process called geomagnetic reversal. The most recent reversal occurred 780,000 years ago.

text: Earth's magnetic field is not constant—the strength of the field and the location of its poles vary. Moreover, the poles periodically reverse their orientation in a process called

text: geomagnetic reversal

text: . The

text: most recent reversal

text: occurred 780,000 years ago.

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: The Earth and most of the planets in the Solar System, as well as the Sun and other stars, all generate magnetic fields through the motion of electrically conducting fluids. The Earth's field originates in its core. This is a region of iron alloys extending to about 3400 km (the radius of the Earth is 6370 km). It is divided into a solid inner core, with a radius of 1220 km, and a liquid outer core. The motion of the liquid in the outer core is driven by heat flow from the inner core, which is about , to the core-mantle boundary, which is about . The pattern of flow is organized by the rotation of the Earth and the presence of the solid inner core.

text: The Earth and most of the planets in the Solar System, as well as the Sun and other stars, all generate magnetic fields through the motion of electrically

text: conducting

text: fluids. The Earth's field originates in its core. This is a region of iron alloys extending to about 3400 km (the radius of the Earth is 6370 km). It is divided into a solid

text: inner core

text: , with a radius of 1220 km, and a liquid

text: outer core

text: . The motion of the liquid in the outer core is driven by heat flow from the inner core, which is about , to the

text: core-mantle boundary

text: , which is about . The pattern of flow is organized by the rotation of the Earth and the presence of the solid inner core.

text: Placet is composed of both ordinary and heavy matter. The core is made of the collapsed, heavy matter, giving the planet a gravity three-fourths that of Earth. Bird-like animals made of heavy matter fly through the earth above the heavy matter core.

text: Placet is composed of both ordinary and heavy matter. The core is made of the collapsed, heavy matter, giving the planet a

text: gravity

text: three-fourths that of

text: Earth

text: . Bird-like animals made of heavy matter fly through the earth above the heavy matter core.

text: Linus is an alien from the planet Linoleum who crashed into the legendary planet Earth. After returning home and expecting a hero's welcome, Linus soon found his fellow Linomen were skeptical of the existence of the so-called "planet Earth" and decides to return to it, this time with a camera. However, he is flat on the planets' currency, Linobucks, and must deal across the planet to get a new cosmic car and a camera. In his adventures, Linus deals himself out of Linoleum (including using a fake ID for Larry Flynt to compete in a bumper car contest), quash a robot revolution in Detroitica and gets gas from an abandoned space station.

text: Linus is an

text: alien

text: from the planet Linoleum who crashed into the legendary

text: planet Earth

text: . After returning home and expecting a hero's welcome, Linus soon found his fellow Linomen were skeptical of the existence of the so-called "planet Earth" and decides to return to it, this time with a camera. However, he is flat on the planets' currency, Linobucks, and must deal across the planet to get a new cosmic car and a camera. In his adventures, Linus deals himself out of Linoleum (including using a fake ID for

text: Larry Flynt

text: to compete in a bumper car contest), quash a robot revolution in Detroitica and gets gas from an abandoned space station.

text: Falkenberg's Mercenary Legion departs Tanith for a contract on the planet New Washington. This is one of a pair of planets, orbiting a common center which itself orbits a red dwarf star. The two planets are tidally locked, so they always present the same face to each other. As day progresses to night on New Washington, the side of the sister planet Franklin facing it goes from night to day. One revolution takes 40 hours. The pair revolve around their star in 52 days.It is one of the farthest colonies from Earth, being over a hundred parsecs away.

text: Falkenberg's Mercenary Legion departs Tanith for a contract on the planet New Washington. This is one of a pair of planets, orbiting a common center which itself orbits a

text: red dwarf

text: star. The two planets are

text: tidally locked

text: , so they always present the same face to each other. As day progresses to night on New Washington, the side of the sister planet Franklin facing it goes from night to day. One revolution takes 40 hours. The pair revolve around their star in 52 days.It is one of the farthest colonies from Earth, being over a hundred

text: parsec

text: s away.

text: In the year 3040, New York medical student Driscoll Rampart (Neal McDonough) is completing his internship on Rusta, a rural planet which due to it being tidally locked to its primary, is divided into contrasting halves of day and night with the halves separated by a wall. The two sides are involved in a civil war: The day side containing a Victorian-styled colony is at odds with the night containing a medieval kingdom. The differences between the two cultures leaves Rampart in a state of wonder. Rampart arrives from Earth for a six-month stint at the Light Side clinic run by Dr. Akada (Paul Winfield).  Rampart's ambition is to eventually set up a private practice in Manhattan on Park Avenue.

text: In the year 3040, New York medical student Driscoll Rampart (

text: Neal McDonough

text: ) is completing his internship on Rusta, a rural planet which due to it being tidally locked to its primary, is divided into contrasting halves of day and night with the halves separated by a wall. The two sides are involved in a civil war: The day side containing a Victorian-styled colony is at odds with the night containing a medieval kingdom. The differences between the two cultures leaves Rampart in a state of wonder. Rampart arrives from Earth for a six-month stint at the Light Side clinic run by Dr. Akada (

text: Paul Winfield

text: ).  Rampart's ambition is to eventually set up a private practice in Manhattan on Park Avenue.

text: Madman Entertainment released the four seasons in six box sets in Australia and New Zealand (Region 4): Season 1, Season 2.1, Season 2.2, Season 3.1, Season 3.2 and Season 4.

text: Madman Entertainment

text: released the four seasons in six box sets in Australia and New Zealand (Region 4): Season 1, Season 2.1, Season 2.2, Season 3.1, Season 3.2 and Season 4.

text: The story is initially set on the planet Nu-Earth, where a stalemated war between the Norts and Southers is being fought. There is some similarity to both the American Civil War and to World War 1, with the Norts resembling Germany, and the Southers the Allied forces. During the conflict, many forms of chemical and biological weapons have been used, poisoning the planet's atmosphere and oceans. As a result, what remains of the population of the planet, including the troops of both sides, live in enclosed - "domed" - military bases and habitats. They wear protective suits, helmets and respiration gear when outside their domes. These suits are known as "chemsuits". Any damage to the helmet or chemsuit is usually fatal to the wearer, due to the toxic atmosphere of the planet. In an attempt to bring an end to the stalemate, The Southern High Command, over a period of years, have produced the GI - "Genetic Infantryman". The GI is a  type of soldier genetically engineered to be immune to the poisonous atmosphere of Nu-Earth, and therefore be able to fight without the clumsy, inhibiting protective gear required by ordinary soldiers. The Southern High Command deploy the entire GI Regiment in a mass spaceborne capsule drop over an area of Nu Earth known as "The Quartz Zone", which resembles one of the Earth's Poles because the surface has an icy, glacier-like nature. The Quartz Zone assault was intended to be a surprise attack, but because a Traitor within the Southern High Command has passed details of it to the Norts, they are expecting the attack. The Norts employ Elite Infantry Regiments known as the Kashan and Kashar Legions to repulse the assault, and the entire GI Regiment - apart from Rogue - is wiped out, since they are virtually defenceless when dropping to the surface of the planet from space. This event is referred to as "The Quartz Zone Massacre".

text: The story is initially set on the planet

text: Nu-Earth

text: , where a stalemated war between the

text: Norts

text: and

text: Southers

text: is being fought. There is some similarity to both the American Civil War and to World War 1, with the Norts resembling Germany, and the Southers the Allied forces. During the conflict, many forms of chemical and biological weapons have been used, poisoning the planet's atmosphere and oceans. As a result, what remains of the population of the planet, including the troops of both sides, live in enclosed - "domed" - military bases and habitats. They wear protective suits, helmets and respiration gear when outside their domes. These suits are known as "

text: chemsuit

text: s". Any damage to the helmet or chemsuit is usually fatal to the wearer, due to the toxic atmosphere of the planet. In an attempt to bring an end to the stalemate, The Southern High Command, over a period of years, have produced the GI - "Genetic Infantryman". The GI is a  type of soldier genetically engineered to be immune to the poisonous atmosphere of Nu-Earth, and therefore be able to fight without the clumsy, inhibiting protective gear required by ordinary soldiers. The Southern High Command deploy the entire GI Regiment in a mass spaceborne capsule drop over an area of Nu Earth known as "The Quartz Zone", which resembles one of the Earth's Poles because the surface has an icy, glacier-like nature. The Quartz Zone assault was intended to be a surprise attack, but because a Traitor within the Southern High Command has passed details of it to the Norts, they are expecting the attack. The Norts employ Elite Infantry Regiments known as the Kashan and Kashar Legions to repulse the assault, and the entire GI Regiment - apart from Rogue - is wiped out, since they are virtually defenceless when dropping to the surface of the planet from space. This event is referred to as "The Quartz Zone Massacre".

text: Transit-timing variation measurements indicate for example that Kepler-52b, Kepler-52c and Kepler-57b have maximum-masses between 30 and 100 times the mass of Earth (although the actual masses could be much lower); with radii about 2 Earth radii, they might have densities larger than that of an iron planet of the same size. As such exoplanets orbit very close to their stars they could be the remnant cores of evaporated gas giants or brown dwarfs. If cores are massive enough they could remain compressed for billions of years despite losing the atmospheric mass.

text: Transit-timing variation

text: measurements indicate for example that

text: and

text: have maximum-masses between 30 and 100 times the

text: mass of Earth

text: (although the actual masses could be much lower); with radii about 2

text: Earth radii

text: , they might have densities larger than that of an

text: iron planet

text: of the same size. As such exoplanets orbit very close to their stars they could be the remnant cores of evaporated

text: gas giant

text: s or

text: brown dwarf

text: In 1831 Gauss developed a fruitful collaboration with the physics professor Wilhelm Weber, leading to new knowledge in magnetism (including finding a representation for the unit of magnetism in terms of mass, charge, and time) and the discovery of Kirchhoff's circuit laws in electricity. It was during this time that he formulated his namesake law. They constructed the first electromechanical telegraph in 1833, which connected the observatory with the institute for physics in Göttingen. Gauss ordered a magnetic observatory to be built in the garden of the observatory, and with Weber founded the "Magnetischer Verein" (magnetic club in German), which supported measurements of Earth's magnetic field in many regions of the world. He developed a method of measuring the horizontal intensity of the magnetic field which was in use well into the second half of the 20th century, and worked out the mathematical theory for separating the inner and outer (magnetospheric) sources of Earth's magnetic field.

text: In 1831 Gauss developed a fruitful collaboration with the physics professor

text: Wilhelm Weber

text: , leading to new knowledge in

text: magnetism

text: (including finding a representation for the unit of magnetism in terms of mass, charge, and time) and the discovery of

text: Kirchhoff's circuit laws

text: in electricity. It was during this time that he formulated his namesake

text: law

text: . They constructed the first

text: electromechanical telegraph

text: in 1833, which connected the observatory with the institute for physics in Göttingen. Gauss ordered a magnetic

text: observatory

text: to be built in the garden of the observatory, and with Weber founded the "Magnetischer Verein" (magnetic club in

text: German

text: ), which supported measurements of Earth's magnetic field in many regions of the world. He developed a method of measuring the horizontal intensity of the magnetic field which was in use well into the second half of the 20th century, and worked out the mathematical theory for separating the inner and outer (

text: magnetospheric

text: ) sources of Earth's magnetic field.

text: Before the 2008 flyby to re-orient for the comet 103P/Hartley encounter, the spacecraft used High Resolution Instrument, the larger of its two telescopes, to perform photometric observations of previously discovered transiting extrasolar planets from January to August 2008. The goal of photometric observations is to measure the quantity of light, not necessarily resolve an image. An aberration in the primary mirror of the HRI  allowed the HRI to spread the light from observations over more pixels without saturating the CCD, effectively obtaining better data. A total of 198,434 images were exposed. EPOCh's goals were to study the physical properties of giant planets and search for rings, moons and planets as small as three Earth masses. It also looked at Earth as though it were an extrasolar planet to provide data that could characterize Earth-type planets for future missions, and it imaged the Earth over 24 hours to capture the Moon passing in front on 2008-05-29.

text: Before the 2008 flyby to re-orient for the comet 103P/Hartley encounter, the spacecraft used High Resolution Instrument, the larger of its two telescopes, to perform photometric observations of previously discovered transiting

text: extrasolar planet

text: s from January to August 2008. The goal of

text: photometric

text: observations is to measure the quantity of light, not necessarily resolve an image. An aberration in the primary mirror of the HRI  allowed the HRI to spread the light from observations over more pixels without saturating the CCD, effectively obtaining better data. A total of 198,434 images were exposed. EPOCh's goals were to study the physical properties of giant planets and search for rings, moons and planets as small as three Earth masses. It also looked at Earth as though it were an extrasolar planet to provide data that could characterize Earth-type planets for future missions, and it imaged the Earth over 24 hours to capture the Moon passing in front on 2008-05-29.

text: Second, atoms of rare earth elements can have high magnetic moments because their orbital electron structure contains many unpaired electrons, in contrast to other elements in which almost all of the electrons exist in pairs with opposite spins, so their magnetic fields cancel out.   This is a consequence of incomplete filling of the f-shell, which can contain up to 7 unpaired electrons.  In a magnet it is the unpaired electrons, aligned so they spin in the same direction, which generate the magnetic field.  This gives the materials high remanence (saturation magnetization J).   The maximum energy density BH is proportional to J so these materials have the potential for storing large amounts of magnetic energy.  The magnetic energy product BH of neodymium magnets is about 18 times greater than "ordinary" magnets by volume.  This allows rare earth magnets to be smaller than other magnets which produce the same field strength.

text: Second, atoms of rare earth elements can have high

text: magnetic moment

text: s because their

text: orbital electron structure

text: contains many

text: unpaired electron

text: s, in contrast to other elements in which almost all of the electrons exist in pairs with opposite spins, so their magnetic fields cancel out.   This is a consequence of incomplete filling of the

text: f-shell

text: , which can contain up to 7 unpaired electrons.  In a magnet it is the unpaired electrons, aligned so they spin in the same direction, which generate the magnetic field.  This gives the materials high

text: remanence

text: saturation magnetization

text: J).   The maximum energy density BH is proportional to J so these materials have the potential for storing large amounts of magnetic energy.  The magnetic energy product BH of neodymium magnets is about 18 times greater than "ordinary" magnets by volume.  This allows rare earth magnets to be smaller than other magnets which produce the same field strength.

text: The planet's mass has been estimated to be 8.65 times that of Jupiter, while its diameter, at , is 0.951 times Jupiter's. Its small size, despite the bloating of the planet's atmosphere, is caused by the strong gravity of the planet. This indicates its mean density is twice that of Earth and its surface gravity approximately 24 times that on Earth, almost equal to the Sun. The orbit is very eccentric, ranging from 4.90 million to 15.36 million miles from the star.

text: The planet's mass has been estimated to be 8.65 times that of

text: Jupiter

text: , while its diameter, at , is 0.951 times Jupiter's. Its small size, despite the bloating of the planet's

text: atmosphere

text: , is caused by the strong gravity of the planet. This indicates its mean density is twice that of Earth and its

text: surface gravity

text: approximately 24 times that on Earth, almost equal to the Sun. The orbit is very eccentric, ranging from 4.90 million to 15.36 million miles from the star.

text: This is a list of seasons completed by the Denver Broncos, an American football franchise based in Denver, Colorado. The Broncos are members of the West division of the American Football Conference (AFC) of the National Football League (NFL). The list documents their season-by-season records from 1960 to the present day, including post-season records, and league awards for individual players and head coaches. As of the end of the 2015 season, the team has completed 56 seasons (playing in nearly 900 combined regular season and playoff games), and concluded the 2015 season with a 24–10 victory over the Carolina Panthers at Super Bowl 50 in Santa Clara, California.

text: This is a list of seasons completed by the

text: Denver Broncos

text: , an

text: American football

text: franchise

text: based in

text: Denver

text: Colorado

text: . The Broncos are members of the

text: West

text: division of the

text: American Football Conference

text: (AFC) of the

text: National Football League

text: (NFL). The list documents their season-by-season records from

text: to the present day, including post-season records, and league awards for individual players and

text: head coach

text: es. As of the end of the 2015 season, the team has completed 56 seasons (playing in nearly 900 combined regular season and playoff games), and concluded the 2015 season with a 24–10 victory over the

text: Carolina Panthers

text: at

text: Super Bowl 50

text: in

text: Santa Clara, California

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: According to a 2014 study by the World Wildlife Fund, the global human population already exceeds planet's biocapacity - it would take the equivalent of 1.5 Earths of biocapacity to meet our current demands. The report further points that if everyone on the planet had the Footprint of the average resident of Qatar, we would need 4.8 Earths and if we lived the lifestyle of a typical resident of the USA, we would need 3.9 Earths.

text: According to a 2014 study by the

text: World Wildlife Fund

text: , the global human population already exceeds planet's

text: biocapacity

text: - it would take the equivalent of 1.5 Earths of biocapacity to meet our current demands. The report further points that if everyone on the planet had the Footprint of the average resident of Qatar, we would need 4.8 Earths and if we lived the lifestyle of a typical resident of the USA, we would need 3.9 Earths.

text: The star hosts three confirmed planets, including the lowest-mass planet with a measured mass and size discovered to date, Kepler-138b, with a mass comparable to that of Mars.  Kepler-138d is remarkable for resembling a miniaturized gas giant with a density too low for a rocky planet, despite being the same mass as the Earth.

text: The star hosts three confirmed planets, including the lowest-mass planet with a measured mass and size discovered to date, Kepler-138b, with a mass comparable to that of

text: Mars

text: .  Kepler-138d is remarkable for resembling a miniaturized

text: gas giant

text: with a density too low for a rocky planet, despite being the same mass as the Earth.

text: Geophysics – the physics of the Earth and its environment in space; also the study of the Earth using quantitative physical methods. The term geophysics sometimes refers only to the geological applications: Earth's shape; its gravitational and magnetic fields; its internal structure and composition; its dynamics and their surface expression in plate tectonics,  the generation of magmas, volcanism and rock formation. However, modern geophysics organizations have a broader definition that includes the hydrological cycle including snow and ice; fluid dynamics of the oceans and the atmosphere; electricity and magnetism in the ionosphere and magnetosphere and solar-terrestrial relations; and analogous problems associated with the Moon and other planets.

text: Geophysics

text: – the physics of the

text: Earth

text: and its environment in space; also the study of the Earth using quantitative physical methods. The term geophysics sometimes refers only to the

text: geological

text: applications: Earth's

text: shape

text: ; its

text: gravitational

text: and

text: magnetic fields

text: ; its

text: internal structure

text: and

text: composition

text: ; its

text: dynamics

text: and their surface expression in

text: plate tectonics

text: ,  the generation of

text: magmas

text: volcanism

text: and rock formation. However, modern geophysics organizations have a broader definition that includes the

text: hydrological cycle

text: including

text: snow

text: and

text: ice

text: fluid dynamics

text: of the

text: oceans

text: and the

text: atmosphere

text: electricity

text: and

text: magnetism

text: in the

text: ionosphere

text: and

text: magnetosphere

text: Moon

text: and other

text: planets

text: It has, however, another key difference from Earth. The entire surface of Erna is wrapped in a powerful energy field known as the Fae. The Fae is a type of energy that comes up to the surface from the core of the planet via the plethora of volcanoes and earthquakes that rock the planet's surface. This is an energy that the native animals of Erna sense, and utilize to a small extent to help them survive (i.e. the Fae is often able to tell a Sensitive individual when an earthquake is coming, or if the tides are about to shift). This energy field that encompasses the planet is likened to Earth's magnetic field. Author C.S. Friedman explains how her idea of the Fae was shaped by Isaac Asimov's essay arguing that if magic existed, it would be a natural force governed by consistent rules. "Like fire, it should be useful when controlled, dangerous if uncontrolled," she says. "The fact that we build windmills does not mean we stop fearing hurricanes."

text: It has, however, another key difference from Earth. The entire surface of Erna is wrapped in a powerful energy field known as the Fae. The Fae is a type of energy that comes up to the surface from the core of the planet via the plethora of volcanoes and earthquakes that rock the planet's surface. This is an energy that the native animals of Erna sense, and utilize to a small extent to help them survive (i.e. the Fae is often able to tell a Sensitive individual when an earthquake is coming, or if the tides are about to shift). This energy field that encompasses the planet is likened to Earth's magnetic field. Author C.S. Friedman explains how her idea of the Fae was shaped by

text: Isaac Asimov

text: 's essay arguing that if magic existed, it would be a natural force governed by consistent rules. "Like fire, it should be useful when controlled, dangerous if uncontrolled," she says. "The fact that we build windmills does not mean we stop fearing hurricanes."

text: Precise ranging to the Moon can test the SEP since the Earth and the Moon have a different fraction of their mass in the energy component. Precision measurements are needed since this component is very small—if m is the self energy of the Earth — the energy needed to spread the atoms of the Earth out to infinity against the attraction of gravity — then the mass of the Earth is decreased by about m/c =  of the Earth’s total mass. The self energy of the Moon is smaller yet, about  of its mass.  (The contribution for any object of laboratory size is negligible, about , so only measurements of planet-sized or bigger objects have any hope of seeing this effect.)

text: In outer space, the magnetopause flows along the boundary between the region around an astronomical object (called the "magnetosphere") and surrounding plasma, in which electric phenomena are dominated or organized by this magnetic field. Earth is surrounded by a magnetosphere, as are the magnetized planets Jupiter, Ganymede, Saturn, Uranus and Neptune. Mercury is magnetized, but too weakly to trap plasma. Mars has patchy surface magnetization. The magnetosphere is the location where the outward magnetic pressure of the Earth's magnetic field is counterbalanced by the solar wind, a plasma. Most of the solar particles are deflected to either side of the magnetopause. However, some particles become trapped within the Earth's magnetic field and form radiation belts. The Van Allen radiation belt is a torus of energetic charged particles (i.e. a plasma) around Earth, trapped by Earth's magnetic field.

text: In outer space, the

text: magnetopause

text: flows along the boundary between the region around an astronomical object (called the "

text: magnetosphere

text: ") and surrounding plasma, in which electric phenomena are dominated or organized by this magnetic field. Earth is surrounded by a magnetosphere, as are the magnetized planets Jupiter, Ganymede, Saturn, Uranus and Neptune. Mercury is magnetized, but too weakly to trap plasma. Mars has patchy surface magnetization. The magnetosphere is the location where the outward magnetic pressure of the Earth's magnetic field is counterbalanced by the

text: solar wind

text: , a plasma. Most of the solar particles are deflected to either side of the magnetopause. However, some particles become trapped within the Earth's magnetic field and form

text: radiation belts

text: . The

text: Van Allen radiation belt

text: is a torus of energetic charged particles (i.e. a plasma) around Earth, trapped by Earth's magnetic field.

text: This apparent conical motion of the sun may be further explained by the spoked wheels of a covered wagon. The rim representing the sun's apparent path, the hub, the earth, and the spokes, lines drawn from the sun's path. Then it may be seen that a line drawn from the sun to the Earth's center would pass north or south of the equator, equal in degree to its declination north or south. These apply to the apparent revolutions of the planets and fixed stars as well.

text: Cybertron, as presented in the original The Transformers animated series, was considerably smaller than the planet Earth, though how much smaller it was presented as was inconsistent, as were many other things in the series. Entirely metallic on the surface, some of the lowest levels of Cybertron consist of rock and dirt, suggesting a natural beginning to the planet. Its gravity is light enough that humans are able to traverse the surface without any trouble, and it possesses a breathable atmosphere. Water is not uncommon on the planet – lake and rivers have been shown to exist, albeit sparingly. Cybertron is orbited by at least two unnamed moons, but its own place in the cosmos appears unfixed – in 1984, it was clearly shown to exist outside of the Milky Way galaxy; however, nine million years prior, Starscream and Skyfire had been able to fly from the planet to Earth under their own power, suggesting that it may drift freely through space, and had been passing through the Solar system at that point, going on to drift out of the galaxy over the ensuing millennia. Cybertron's moons did not appear until the animated feature The Transformers: The Movie, and no explanation for their existence was given. The moons were also depicted as being mechanical in nature much like Cybertron with metallic surfaces. Unlike Cybertron however, the moons do not appear to have any detectable atmosphere, as Daniel Witwicky, a longtime ally of the Autobots, was required to wear a mechanical "exo suit" that presumably included its own air supply and means to keep organic life forms pressurized against the vacuum of space, something that is not required by humans on Cybetron.

text: Cybertron, as presented in the original

text: The Transformers

text: animated series, was considerably smaller than the planet Earth, though how much smaller it was presented as was inconsistent, as were many other things in the series. Entirely metallic on the surface, some of the lowest levels of Cybertron consist of rock and dirt, suggesting a natural beginning to the planet. Its gravity is light enough that humans are able to traverse the surface without any trouble, and it possesses a breathable atmosphere. Water is not uncommon on the planet – lake and rivers have been shown to exist, albeit sparingly. Cybertron is orbited by at least two unnamed moons, but its own place in the cosmos appears unfixed – in 1984, it was clearly shown to exist outside of the

text: Milky Way

text: galaxy; however, nine million years prior,

text: Starscream

text: and

text: Skyfire

text: had been able to fly from the planet to Earth under their own power, suggesting that it may drift freely through space, and had been passing through the Solar system at that point, going on to drift out of the galaxy over the ensuing millennia. Cybertron's moons did not appear until the animated feature

text: The Transformers: The Movie

text: , and no explanation for their existence was given. The moons were also depicted as being mechanical in nature much like Cybertron with metallic surfaces. Unlike Cybertron however, the moons do not appear to have any detectable atmosphere, as Daniel Witwicky, a longtime ally of the Autobots, was required to wear a mechanical "exo suit" that presumably included its own air supply and means to keep organic life forms pressurized against the vacuum of space, something that is not required by humans on Cybetron.

text: Only the first planet is known transit the star; this means that the planet's orbit appear to cross in front of their star as viewed from the Earth's perspective. Its inclination relative to Earth's line of sight, or how far above or below the plane of sight it is, vary by less than one degree. This allows direct measurements of the planet's periods and relative diameters (compared to the host star) by monitoring the planet's transit of the star.

text: Only the first planet is known

text: transit

text: the star; this means that the planet's orbit appear to cross in front of their star as viewed from the Earth's perspective. Its

text: inclination

text: relative to Earth's line of sight, or how far above or below the plane of sight it is, vary by less than one degree. This allows direct measurements of the planet's periods and relative diameters (compared to the host star) by monitoring the planet's transit of the star.

text: The United Planets (abbreviated as the "UP") is composed of Earth and other planets within the Milky Way galaxy. The capital of the United Planets is Superman's hometown of Metropolis on the North American continent on Earth. The population of the United Planets is about 300 billion. The UP's official law enforcement agency is the Science Police, which is based on Earth in Metropolis. The UP also maintains a militia, which is based on the planet Xolnar.

text: The United Planets (abbreviated as the "UP") is composed of Earth and other

text: planet

text: s within the

text: Milky Way

text: galaxy. The capital of the United Planets is

text: Superman

text: 's hometown of

text: Metropolis

text: on the North American continent on Earth. The population of the United Planets is about 300 billion. The UP's official law enforcement agency is the

text: Science Police

text: , which is based on Earth in Metropolis. The UP also maintains a militia, which is based on the planet

text: Xolnar

text: " describes the set of the Earth's magnetic field lines which cross the Earth's magnetic equator two earth radii from the center of the Earth.  L-shell parameters can also describe the magnetic fields of other planets.  In such cases, the parameter is renormalized for that planet's radius and magnetic field model.

text: " describes the set of the

text: Earth's magnetic field

text: lines which cross the Earth's magnetic equator two earth radii from the center of the Earth.  L-shell parameters can also describe the magnetic fields of other planets.  In such cases, the parameter is renormalized for that planet's radius and magnetic field model.

text: This comparison indicates that size alone is a poor measure, particularly in terms of habitability. Temperature must also be considered as Venus and the planets of Alpha Centauri B (discovered in 2012), Kepler-20 (discovered in 2011), COROT-7 (discovered in 2009) and the three planets of Kepler-42 (all discovered in 2011) are very hot, and Mars, Ganymede and Titan are frigid worlds, resulting also in wide variety of surface and atmospheric conditions. The mass of the Solar System's moons are a tiny fraction of that of Earth whereas the mass of extrasolar planets are very difficult to accurately measure. However discoveries of Earth-sized terrestrial planets are important as they may indicate the probable frequency and distribution of Earth-like planets.

text: This comparison indicates that size alone is a poor measure, particularly in terms of

text: habitability

text: . Temperature must also be considered as Venus and the planets of Alpha Centauri B (discovered in 2012),

text: (discovered in 2011), COROT-7 (discovered in 2009) and the three planets of Kepler-42 (all discovered in 2011) are very hot, and

text: Mars

text: Ganymede

text: and

text: Titan

text: are frigid worlds, resulting also in wide variety of surface and atmospheric conditions. The mass of the

text: Solar System's moons

text: are a tiny fraction of that of Earth whereas the mass of

text: extrasolar planets

text: are very difficult to accurately measure. However discoveries of Earth-sized

text: terrestrial planet

text: s are important as they may indicate the probable frequency and distribution of Earth-like planets.

text: Kepler-186e's axial tilt (obliquity) is likely very small, in which case it would not have tilt-induced seasons as Earth and Mars do. Its orbit is probably close to circular, so it will also lack eccentricity-induced seasonal changes like those of Mars. However, the axial tilt could be larger (about 23 degrees) if another undetected nontransiting planet orbits between it and Kepler-186f; planetary formation simulations have shown that the presence of at least one additional planet in this region is likely. If such a planet exists, it cannot be much more massive than Earth as it would then cause orbital instabilities.

text: axial tilt

text: Mars

text: . However, the axial tilt could be larger (about 23 degrees) if another undetected nontransiting planet orbits between it and Kepler-186f; planetary formation simulations have shown that the presence of at least one additional planet in this region is likely. If such a planet exists, it cannot be much more massive than Earth as it would then cause orbital instabilities.

text: It is not known if Kepler-452b is a rocky planet but based on its small radius, Kepler-452b is likely rocky. It is not clear if Kepler-452b offers habitable environments. It orbits a G2V-type star, like the Sun, with nearly the same temperature and mass and 20% more luminous. However, the star is six billion years old, making it 1.5 billion years older than the Sun. At this point in its star's evolution, Kepler-452b is receiving 10% more energy from its parent star than Earth is currently receiving from the Sun. If Kepler-452b is a rocky planet, it may be subject to a runaway greenhouse effect similar to that seen on Venus. However, due to the planet being 50% bigger than Earth, it is likely to have an estimated mass of 5 , which could prevent Kepler-452b from succumbing to the runaway greenhouse effect for another 500 million years, thus holding on to any oceans it may have for a longer period time compared to when Earth's oceans dry up. This in turn would be accompanied with the carbonate–silicate cycle being "buffed" in duration due to increased volcanic activity on Kepler-452b.  This could allow any potential life on the surface to continue to evolve for another 500–900 million years before the habitable zone is pushed out of Kepler-452b's orbit.

text: It is not known if Kepler-452b is a

text: rocky planet

text: but based on its small radius, Kepler-452b is likely rocky. It is not clear if Kepler-452b offers habitable environments. It orbits a G2V-type star, like the Sun, with nearly the same temperature and mass and 20% more luminous. However, the star is six billion years old, making it 1.5 billion years older than the Sun. At this point in its star's

text: evolution

text: , Kepler-452b is receiving 10% more energy from its parent star than Earth is currently receiving from the Sun. If Kepler-452b is a rocky planet, it may be subject to a

text: runaway greenhouse effect

text: similar to that seen on

text: Venus

text: . However, due to the planet being 50% bigger than Earth, it is likely to have an estimated mass of 5 , which could prevent Kepler-452b from succumbing to the runaway greenhouse effect for another 500 million years, thus holding on to any oceans it may have for a longer period time compared to when

text: Earth's oceans dry up

text: . This in turn would be accompanied with the

text: carbonate–silicate cycle

text: being "buffed" in duration due to increased volcanic activity on Kepler-452b.  This could allow any potential life on the surface to continue to evolve for another 500–900 million years before the habitable zone is pushed out of Kepler-452b's orbit.

text: The song is an upbeat, folk influenced song, a radical stylistic departure for the B-52's.  Featuring Kate Pierson on lead vocals, "Revolution Earth" remains a fan favourite despite the fact that it is from an album featuring only three of the original five members of the band.  With founding member Cindy Wilson absent from the recording, Pierson sings in harmony with herself - multi-tracking different vocal lines.  Fred Schneider sings a brief backing vocal.  As with many of the tracks from the Good Stuff album, "Revolution Earth" has a long and resounding intro and outro, as opposed to the band's earlier songs which always had a definite beginning and ending.

text: The song is an upbeat, folk influenced song, a radical stylistic departure for the B-52's.  Featuring

text: Kate Pierson

text: on lead vocals, "Revolution Earth" remains a fan favourite despite the fact that it is from an album featuring only three of the original five members of the band.  With founding member

text: Cindy Wilson

text: absent from the recording, Pierson sings in harmony with herself - multi-tracking different vocal lines.

text: Fred Schneider

text: sings a brief backing vocal.  As with many of the tracks from the Good Stuff album, "Revolution Earth" has a long and resounding intro and outro, as opposed to the band's earlier songs which always had a definite beginning and ending.

text: The magnetic field is about 1.1% as strong as Earth's. At the Hermean equator, the relative strength of the magnetic field is around 300 nT, which is weaker than that of Jupiter's moon Ganymede. Mercury's magnetic field is weaker than Earth's because its core had cooled and solidified more quickly than Earth's. Although Mercury's magnetic field is much weaker than Earth's magnetic field, it is still strong enough to deflect the solar wind, inducing a magnetosphere. Because Mercury's magnetic field is weak while the interplanetary magnetic field it interacts with in its orbit is relatively strong, the solar wind dynamic pressure at Mercury′s orbit is also three times larger than at Earth.

text: The magnetic field is about 1.1% as strong as

text: Earth's

text: . At the Hermean equator, the relative strength of the magnetic field is around 300

text: nT

text: , which is weaker than that of

text: Jupiter

text: 's moon

text: Ganymede

text: . Mercury's magnetic field is weaker than Earth's because its core had cooled and solidified more quickly than Earth's. Although Mercury's magnetic field is much weaker than Earth's magnetic field, it is still strong enough to deflect the

text: solar wind

text: , inducing a

text: magnetosphere

text: . Because Mercury's magnetic field is weak while the

text: interplanetary magnetic field

text: it interacts with in its orbit is relatively strong, the solar wind dynamic pressure at Mercury′s orbit is also three times larger than at Earth.

text: For a Counter-Earth orbiting the same path as Earth to always stay 180 degrees from Earth, the two planets would have to have circular orbits, but Earth's orbit is elliptical.    According to Kepler's second law, a planet revolves faster when it is close to the star, so a Counter-Earth following the Earth on the same orbit with half a year of delay would sometimes not be exactly 180 degrees from Earth. To remain hidden from Earth, the Counter-Earth would require an orbit symmetrical to Earth's, not sharing the second focus or orbit path.

text: For a Counter-Earth orbiting the same path as Earth to always stay 180 degrees from Earth, the two planets would have to have circular orbits, but Earth's orbit is

text: elliptical

text: .    According to

text: Kepler's second law

text: , a planet revolves faster when it is close to the star, so a Counter-Earth following the Earth on the same orbit with half a year of delay would sometimes not be exactly 180 degrees from Earth. To remain hidden from Earth, the Counter-Earth would require an orbit symmetrical to Earth's, not sharing the second focus or orbit path.

text: "The team has discovered the most Earthlike planet yet", said Michael Turner, assistant director for the mathematical and physical sciences directorate at the National Science Foundation, which supported the work. At 5.5 Earth masses, the planet was less massive than the previous candidate for lowest-mass exoplanet around a main-sequence star, the 7.5 Earth mass Gliese 876 d. Since 2013, many Earth-sized or smaller planets around main-sequence stars have been detected by the Kepler spacecraft and others.

text: "The team has discovered the most Earthlike planet yet", said Michael Turner, assistant director for the mathematical and physical sciences directorate at the

text: National Science Foundation

text: , which supported the work. At 5.5 Earth masses, the planet was less massive than the previous candidate for lowest-mass exoplanet around a main-sequence star, the 7.5 Earth mass Gliese 876 d. Since 2013, many Earth-sized or smaller planets around main-sequence stars have been detected by the

text: Kepler spacecraft

text: and others.

text: Parts of this diagram represent distances, other parts gravitational accelerations (attractive forces per unit mass). In a dual significance, SQ represents the Earth-Sun distance, and then it also represents the size and direction of the Earth-Sun gravitational acceleration. Other distances in the diagram are then in proportion to distance SQ. Other attractions are in proportion to attraction SQ.

text: Some studies indicate that there is a natural limit, set at 1.6R, below which nearly all planets are terrestrial, composed primarily of rock-iron-water mixtures. Generally, objects with a mass below 6 M are very likely to be of similar composition as Earth. Above this limit, the density of the planets decreases with increasing size, the planet will become a "water world" and finally a gas giant. In addition, most super-Earths' high mass may cause them to lack plate tectonics.  Thus, it is expected that any exoplanet similar to Earth's density and with a radius under 1.6 R may be suitable for life. However, other studies indicate that water worlds represent a transitional stage between mini-Neptunes and the terrestrial planets, especially if they belong to red dwarfs or K dwarfs. Although water planets may be habitable, the average depth of the water and the absence of land area would not make them superhabitable as defied by Heller and Armstrong. From a geological perspective, the optimal mass of a planet is about 2 M, so it must have a radius that keeps the density of the Earth among 1.2 and 1.3R.

text: Some studies indicate that there is a natural limit, set at 1.6R, below which nearly all planets are

text: terrestrial

text: , composed primarily of rock-iron-water mixtures. Generally, objects with a mass below 6

text: M

text: are very likely to be of similar composition as Earth. Above this limit, the density of the planets decreases with increasing size, the planet will become a

text: "water world"

text: and finally a

text: gas giant

text: . In addition, most

text: super-Earth

text: s' high mass may cause them to lack

text: plate tectonics

text: .  Thus, it is expected that any exoplanet similar to Earth's density and with a radius under 1.6 R may be suitable for life. However, other studies indicate that water worlds represent a transitional stage between

text: mini-Neptune

text: s and the terrestrial planets, especially if they belong to

text: red dwarf

text: s or

text: K dwarfs

text: . Although water planets may be habitable, the average depth of the water and the absence of land area would not make them superhabitable as defied by Heller and Armstrong. From a geological perspective, the optimal mass of a planet is about 2 M, so it must have a

text: radius

text: that keeps the density of the

text: Earth

text: among 1.2 and 1.3R.

text: In astronomy, a planet's elongation is the angle between the Sun and the planet, with Earth as the reference point. The greatest elongation of a given planet occurs when this inner planet’s position, in its orbital path to the Sun, is at tangent to the observer on Earth. Given the planets able to elongate are well within the area of Earth's orbit of the Sun, observation of such a phenomenon should not pose that much a challenge, compared to deep sky objects, for example. When a planet is at its greatest elongation, it is farthest from the Sun as viewed from Earth, so its view is also best at that point.

text: In

text: astronomy

text: , a planet's elongation is the angle between the

text: Sun

text: and the planet, with

text: Earth

text: as the reference point. The greatest elongation of a given planet occurs when this inner planet’s position, in its orbital path to the Sun, is at tangent to the observer on Earth. Given the planets able to elongate are well within the area of Earth's orbit of the Sun, observation of such a phenomenon should not pose that much a challenge, compared to deep sky objects, for example. When a planet is at its greatest elongation, it is farthest from the Sun as viewed from Earth, so its view is also best at that point.

text: Based upon the size of the Earth and the force of gravity on its surface, the average density of the planet Earth is 5.515 g/cm, yet typical densities of surface rocks are only half that (about 2.75 g/cm). If any significant portion of the Earth were hollow, the average density would be much lower than that of surface rocks. The only way for Earth to have the force of gravity that it does is for much more dense material to make up a large part of the interior. Nickel-iron alloy under the conditions expected in a non-hollow Earth would have densities ranging from about 10 to 13 g/cm, which brings the average density of Earth to its observed value.

text: Ole Christensen Rømer used an astronomical measurement to make the first quantitative estimate of the speed of light. When measured from Earth, the periods of moons orbiting a distant planet are shorter when the Earth is approaching the planet than when the Earth is receding from it. The distance travelled by light from the planet (or its moon) to Earth is shorter when the Earth is at the point in its orbit that is closest to its planet than when the Earth is at the farthest point in its orbit, the difference in distance being the diameter of the Earth's orbit around the Sun. The observed change in the moon's orbital period is caused by the difference in the time it takes light to traverse the shorter or longer distance. Rømer observed this effect for Jupiter's innermost moon Io and deduced that light takes 22 minutes to cross the diameter of the Earth's orbit.

text: Ole Christensen Rømer

text: used an astronomical measurement to make

entity_name: Rømer's determination of the speed of light

text: the first quantitative estimate of the speed of light

text: . When measured from Earth, the periods of moons orbiting a distant planet are shorter when the Earth is approaching the planet than when the Earth is receding from it. The distance travelled by light from the planet (or its moon) to Earth is shorter when the Earth is at the point in its orbit that is closest to its planet than when the Earth is at the farthest point in its orbit, the difference in distance being the

text: diameter

text: of the Earth's orbit around the Sun. The observed change in the moon's orbital period is caused by the difference in the time it takes light to traverse the shorter or longer distance. Rømer observed this effect for

text: Jupiter

text: 's innermost moon

text: Io

text: and deduced that light takes 22 minutes to cross the diameter of the Earth's orbit.

text: The signal produced by the planet is very weak and the eccentricity was originally supposed to be very circular which led to speculations of a very Jupiter-like planet, with a system of several large moons like Jupiter itself. Fortunately, the inner system should be stable for Earth-like planets despite a known, smaller inner Neptune-like planet which is known to orbit the star at distance of 0.12 AU every 17 Earth days.

text: The signal produced by the planet is very weak and the eccentricity was originally supposed to be very circular which led to speculations of a very Jupiter-like planet, with a system of several large moons like Jupiter itself. Fortunately, the inner system should be stable for

text: Earth

text: -like planets despite a known, smaller inner

text: Neptune

text: -like planet which is known to orbit the star at distance of 0.12 AU every 17 Earth days.

text: On average, the light that Gliese 581 d receives from its star has about 30% of the intensity of light the Earth receives from the Sun. By comparison, sunlight on Mars has about 40% of the intensity of that on Earth. That might seem to suggest that Gliese 581 d is too cold to support liquid water and hence is inhospitable to life. However, an atmospheric greenhouse effect can significantly raise planetary temperatures. For example, Earth's own mean temperature would be about −18 °C without any greenhouse gases, ranging from around 100 °C on the day side to −150 °C at night, much like that found on the Moon. If the atmosphere of Gliese 581 d produces a sufficiently large greenhouse effect, and the planet's geophysics stabilize the CO levels (as Earth's does via plate tectonics), then the surface temperature might permit a liquid water cycle, conceivably allowing the planet to support life. Calculations by Barnes et al. suggest, however, that tidal heating is too low to keep plate tectonics active on the planet, unless radiogenic heating is somewhat higher than expected.

text: On average, the light that Gliese 581 d receives from its star has about 30% of the intensity of light the Earth receives from the Sun. By comparison, sunlight on Mars has about 40% of the intensity of that on Earth. That might seem to suggest that Gliese 581 d is too cold to support liquid water and hence is inhospitable to life. However, an atmospheric greenhouse effect can significantly raise planetary temperatures. For example, Earth's own mean temperature would be about −18 °C without any greenhouse gases, ranging from around 100 °C on the day side to −150 °C at night, much like that found on the

text: Moon

text: . If the atmosphere of Gliese 581 d produces a sufficiently large

text: greenhouse effect

text: , and the planet's geophysics stabilize the CO levels (as Earth's does via plate tectonics), then the surface

text: temperature

text: might permit a liquid water cycle, conceivably allowing the planet to support life. Calculations by Barnes et al. suggest, however, that

text: tidal heating

text: is too low to keep

text: plate tectonics

text: active on the planet, unless radiogenic heating is somewhat higher than expected.

text: Copernicus argued that the universe comprised eight spheres. The outermost consisted of motionless, fixed stars, with the Sun motionless at the center. The known planets revolved about the Sun, each in its own sphere, in the order: Mercury, Venus, Earth, Mars, Jupiter, Saturn. The Moon, however, revolved in its sphere around the Earth. What appeared to be the daily revolution of the Sun and fixed stars around the Earth was actually the Earth's daily rotation on its own axis.

text: Kepler-10b is the first confirmed terrestrial planet to have been discovered outside the Solar System. Discovered after several months of data collection during the course of the NASA-directed Kepler Mission, which aims to discover Earth-like planets crossing in front of their host stars, the planet's discovery was announced on January 10, 2011. Kepler-10b has a mass of 3.33±0.49 Earth masses and a radius of 1.4 Earth radii. However, it lies extremely close to its star, Kepler-10, and as a result is too hot to support life. Its existence was confirmed using measurements from the W.M. Keck Observatory in Hawaii.

text: Kepler-10b is the first confirmed

text: terrestrial planet

text: to have been discovered outside the

text: Solar System

text: . Discovered after several months of data collection during the course of the

text: NASA

text: -directed

text: Kepler Mission

text: , which aims to discover

text: Earth

text: -like planets

text: crossing in front of

text: their host stars, the planet's discovery was announced on January 10, 2011. Kepler-10b has a mass of 3.33±0.49

text: Earth mass

text: es and a radius of 1.4

text: Earth radii

text: . However, it lies extremely close to its star,

text: , and as a result is too hot to support life. Its existence was confirmed using measurements from the

text: W.M. Keck Observatory

text: in Hawaii.

text: In general relativity, if the star collapses to a size smaller than its Schwarzschild radius, an event horizon will exist at that radius and the star will become a black hole. Thus, the size of a preon star may vary from around 1 metre with an absolute mass of 100 earths to the size of a pea with a mass roughly equal to the Moon.

text: In general relativity, if the star collapses to a size smaller than its

text: Schwarzschild radius

text: , an

text: event horizon

text: will exist at that radius and the star will become a

text: black hole

text: . Thus, the size of a preon star may vary from around 1 metre with an absolute mass of 100 earths to the size of a pea with a mass roughly equal to the Moon.

text: The Legion of Substitute Heroes was founded by Polar Boy, Night Girl, Stone Boy, Fire Lad, and Chlorophyll Kid, five young heroes whose powers were not sufficient to earn them membership in the Legion of Super-Heroes — Night Girl for example could only use her powers in the dark. After receiving a Legion flight belt as a consolation prize, the five disconsolate teenagers decided to form a group that could pinch hit for the Legion. After several failures as a team, the Subs managed to save the Earth from an invasion by Plant Men while the Legion was off planet fighting a decoy armada of robot spaceships.

text: The Legion of Substitute Heroes was founded by Polar Boy,

text: Night Girl

text: Stone Boy

text: Fire Lad

text: , and

text: Chlorophyll Kid

text: , five young heroes whose powers were not sufficient to earn them membership in the Legion of Super-Heroes — Night Girl for example could only use her powers in the dark. After receiving a Legion flight belt as a consolation prize, the five disconsolate teenagers decided to form a group that could

text: pinch hit

text: for the Legion. After several failures as a team, the Subs managed to save the Earth from an invasion by Plant Men while the Legion was off planet fighting a decoy armada of robot spaceships.

text: Although no other moons of Earth have been found to date, there are various types of near-Earth objects in 1:1 resonance with it, which are known as quasi-satellites. Quasi-satellites orbit the Sun from the same distance as a planet, rather than the planet itself. Their orbits are unstable, and will fall into other resonances or be kicked into other orbits over thousands of years. Quasi-satellites of Earth include , ,, , , , and 3753 Cruithne. Cruithne, discovered in 1986, orbits the Sun in an elliptical orbit but appears to have a horseshoe orbit when viewed from Earth. Some went as far to nickname Cruithne "Earth's second moon".

text: Although no other moons of Earth have been found to date, there are various types of

text: near-Earth objects

text: in 1:1 resonance with it, which are known as

text: quasi-satellite

text: s. Quasi-satellites orbit the Sun from the same distance as a planet, rather than the planet itself. Their orbits are unstable, and will fall into other resonances or be kicked into other orbits over thousands of years. Quasi-satellites of Earth include , ,, , , , and

text: 3753 Cruithne

text: . Cruithne, discovered in 1986, orbits the

text: Sun

text: in an elliptical orbit but appears to have a

text: horseshoe orbit

text: when viewed from Earth. Some went as far to nickname Cruithne "Earth's second moon".

text: The Earth, among other planets, orbits the Sun because the Sun exerts a gravitational pull that acts as a centripetal force, holding the Earth to it, which would otherwise go shooting off into space. If the Sun's pull is considered an action, then Earth simultaneously exerts a reaction as a gravitational pull on the Sun. Earth's pull has the same amplitude as the Sun but in the opposite direction. Since the Sun's mass is so much larger than Earth's, the Sun does not generally appear to react to the pull of Earth, but in fact it does, as demonstrated in the animation (not to precise scale). A correct way of describing the combined motion of both objects (ignoring all other celestial bodies for the moment) is to say that they both orbit around the center of mass, referred to in astronomy as the barycenter, of the combined system.

text: The

text: Earth

text: , among other

text: planet

text: s, orbits the

text: Sun

text: because the Sun exerts a gravitational pull that acts as a

text: centripetal force

text: , holding the Earth to it, which would otherwise go shooting off into space. If the Sun's pull is considered an action, then Earth simultaneously exerts a reaction as a gravitational pull on the Sun. Earth's pull has the same amplitude as the Sun but in the opposite direction. Since the Sun's

text: mass

text: is so much larger than Earth's, the Sun does not generally appear to react to the pull of Earth, but in fact it does, as demonstrated in the animation (not to precise scale). A correct way of describing the combined motion of both objects (ignoring all other celestial bodies for the moment) is to say that they both orbit around the

text: center of mass

text: , referred to in astronomy as the

text: barycenter

text: , of the combined system.

text: The extent of Earth's magnetic field in space defines the magnetosphere. Ions and electrons of the solar wind are deflected by the magnetosphere; solar wind pressure compresses the dayside of the magnetosphere, to about 10 Earth radii, and extends the nightside magnetosphere into a long tail. Because the velocity of the solar wind is greater than the speed at which wave propagate through the solar wind, a supersonic bowshock precedes the dayside magnetosphere within the solar wind. Charged particles are contained within the magnetosphere; the plasmasphere is defined by low-energy particles that essentially follow magnetic field lines as Earth rotates; the ring current is defined by medium-energy particles that drift relative to the geomagnetic field, but with paths that are still dominated by the magnetic field, and the Van Allen radiation belt are formed by high-energy particles whose motion is essentially random, but otherwise contained by the magnetosphere.

text: The extent of Earth's magnetic field in space defines the magnetosphere. Ions and electrons of the solar wind are deflected by the magnetosphere; solar wind pressure compresses the dayside of the magnetosphere, to about 10 Earth radii, and extends the nightside magnetosphere into a long tail. Because the velocity of the solar wind is greater than the speed at which wave propagate through the solar wind, a supersonic bowshock precedes the dayside magnetosphere within the solar wind.

text: Charged particles

text: are contained within the magnetosphere; the plasmasphere is defined by low-energy particles that essentially follow magnetic field lines as Earth rotates; the ring current is defined by medium-energy particles that drift relative to the geomagnetic field, but with paths that are still dominated by the magnetic field, and the

text: Van Allen radiation belt

text: are formed by high-energy particles whose motion is essentially random, but otherwise contained by the magnetosphere.

text: The gravitational effects of the Moon and the Sun (also the cause of the tides) have a very small effect on the apparent strength of Earth's gravity, depending on their relative positions; typical variations are 2 µm/s (0.2 mGal) over the course of a day.

text: The gravitational effects of the

text: Moon

text: and the

text: Sun

text: (also the cause of the

text: tide

text: s) have a very small effect on the apparent strength of Earth's gravity, depending on their relative positions; typical variations are 2 µm/s (0.2

text: mGal

text: ) over the course of a day.

text: The forests around Homme have their own segment in David Attenborough's documentary, Planet Earth, in episode 11, Seasonal Forest.

text: The forests around Homme have their own segment in

text: David Attenborough

text: 's documentary,

text: Planet Earth

text: , in episode 11, Seasonal Forest.

text: The male also manages to escape as the robots begin a systemic attack on the planet, first with an EMP (which aids in Josh rescuing Skye).  It's also discovered that the robots are slowing down the Earth's core and stopping the planet's rotation.

text: Earth's magnetic field, also known as the geomagnetic field, is the magnetic field that extends from the Earth's interior out into space, where it meets the solar wind, a stream of charged particles emanating from the Sun. Its magnitude at the Earth's surface ranges from 25 to 65 microteslas (0.25 to 0.65 gauss). Roughly speaking it is the field of a magnetic dipole currently tilted at an angle of about 10 degrees with respect to Earth's rotational axis, as if there were a bar magnet placed at that angle at the center of the Earth. The North geomagnetic pole, located near Greenland in the northern hemisphere, is actually the south pole of the Earth's magnetic field, and the South geomagnetic pole is the north pole. Unlike a bar magnet, Earth's magnetic field changes over time because it is generated by a geodynamo (in Earth's case, the motion of molten iron alloys in its outer core).

text: Earth's magnetic field, also known as the geomagnetic field, is the

text: magnetic field

text: that extends from the

text: Earth

text: 's interior out into space, where it meets the

text: solar wind

text: , a stream of

text: charged particle

text: s emanating from the

text: Sun

text: . Its magnitude at the Earth's surface ranges from 25 to 65

text: microteslas

text: (0.25 to 0.65

text: gauss

text: ). Roughly speaking it is the field of a

text: magnetic dipole

text: currently tilted at an angle of about 10 degrees with respect to

text: Earth's rotational axis

text: , as if there were a

text: bar magnet

text: placed at that angle at the center of the Earth. The

text: North geomagnetic pole

text: , located near Greenland in the northern hemisphere, is actually the south pole of the Earth's magnetic field, and the

text: South geomagnetic pole

text: is the north pole. Unlike a bar magnet, Earth's magnetic field changes over time because it is generated by a

text: geodynamo

text: (in Earth's case, the motion of molten iron alloys in its

text: outer core

text: Despite its small size and slow 59-day-long rotation, Mercury has a significant, and apparently global, magnetic field. According to measurements taken by , it is about 1.1% the strength of Earth's. The magnetic-field strength at Mercury's equator is about . Like that of Earth, Mercury's magnetic field is dipolar. Unlike Earth, Mercury's poles are nearly aligned with the planet's spin axis. Measurements from both the  and MESSENGER space probes have indicated that the strength and shape of the magnetic field are stable.

text: Despite its small size and slow 59-day-long rotation, Mercury has a significant, and apparently global,

text: magnetic field

text: . According to measurements taken by , it is about 1.1% the strength of Earth's. The magnetic-field strength at Mercury's equator is about . Like that of Earth, Mercury's magnetic field is

text: dipolar

text: . Unlike Earth, Mercury's poles are nearly aligned with the planet's spin axis. Measurements from both the  and MESSENGER space probes have indicated that the strength and shape of the magnetic field are stable.

text: The interior structure of the Earth is layered in spherical shells, like an onion. These layers can be defined by their chemical and their rheological properties.  Earth has an outer silicate solid crust, a highly viscous mantle, a liquid outer core that is much less viscous than the mantle, and a solid inner core. Scientific understanding of the internal structure of the Earth is based on observations of topography and bathymetry, observations of rock in outcrop, samples brought to the surface from greater depths by volcanoes or volcanic activity, analysis of the seismic waves that pass through the Earth, measurements of the gravitational and magnetic fields of the  Earth, and experiments with crystalline solids at pressures and temperatures characteristic of the Earth's deep interior.

text: The interior structure of the Earth is layered in spherical shells, like an

text: onion

text: . These layers can be defined by their

text: chemical

text: and their

text: rheological

text: properties.

text: Earth

text: has an outer

text: silicate

text: solid

text: crust

text: , a highly

text: viscous

text: mantle

text: , a liquid

text: outer core

text: that is much less viscous than the mantle, and a solid

text: inner core

text: . Scientific understanding of the internal structure of the Earth is based on observations of

text: topography

text: and

text: bathymetry

text: , observations of

text: rock

text: in

text: outcrop

text: , samples brought to the surface from greater depths by

text: volcanoes

text: or

text: volcanic activity

text: , analysis of the

text: seismic wave

text: s that pass through the Earth, measurements of the

text: gravitational

text: and

text: magnetic fields

text: of the  Earth, and experiments with crystalline solids at pressures and temperatures characteristic of the Earth's deep interior.

text: Ultron is Thermoman's home planet and Superheroes are their greatest export. Ultron is never seen, apart from a few shots of the planet from space (although George once described the gravity and atmospheric pressure to be much greater than Earth), but many references are made to the planet and its unique culture throughout the series.

text: Theoretical models predict that volatile compounds such as water and carbon dioxide, if present, might evaporate in the scorching heat of the sunward side, migrate to the cooler night side, and condense to form ice caps. Over time, the entire atmosphere might freeze into ice caps on the night side of the planet. However, it remains unknown if water and/or carbon dioxide are even present on the surface of Gliese 581c. Alternatively, an atmosphere large enough to be stable would circulate the heat more evenly, allowing for a wider habitable area on the surface. For example, although Venus has a small axial inclination, very little sunlight reaches the surface at the poles. A slow rotation rate approximately 117 times slower than Earth's produces prolonged days and nights. Despite the uneven distribution of sunlight cast on Venus at any given time, polar areas and the night side of Venus are kept almost as hot as on the day side by globally circulating winds.

text: Theoretical models predict that volatile

text: compounds

text: such as

text: water

text: and

text: carbon dioxide

text: , if present, might evaporate in the scorching heat of the sunward side, migrate to the cooler night side, and condense to form

text: ice cap

text: s. Over time, the entire atmosphere might freeze into ice caps on the night side of the planet. However, it remains unknown if water and/or carbon dioxide are even present on the surface of Gliese 581c. Alternatively, an atmosphere large enough to be stable would circulate the heat more evenly, allowing for a wider habitable area on the surface. For example, although

text: Venus

text: has a small axial inclination, very little sunlight reaches the surface at the poles. A slow rotation rate approximately 117 times slower than Earth's produces prolonged days and nights. Despite the uneven distribution of sunlight cast on Venus at any given time, polar areas and the night side of Venus are kept almost as hot as on the day side by globally circulating winds.

text: "Low mass" is partly a relative label: the Earth is low mass when compared to the Solar System's gas giants, but it is the largest, by diameter and mass, and the densest of all terrestrial bodies. It is large enough to retain an atmosphere through gravity alone and large enough that its molten core remains a heat engine, driving the diverse geology of the surface (the decay of radioactive elements within a planet's core is the other significant component of planetary heating). Mars, by contrast, is nearly (or perhaps totally) geologically dead and has lost much of its atmosphere. Thus it would be fair to infer that the lower mass limit for habitability lies somewhere between that of Mars and that of Earth or Venus: 0.3 Earth masses has been offered as a rough dividing line for habitable planets. However, a 2008 study by the Harvard-Smithsonian Center for Astrophysics suggests that the dividing line may be higher. Earth may in fact lie on the lower boundary of habitability: if it were any smaller, plate tectonics would be impossible. Venus, which has 85% of Earth's mass, shows no signs of tectonic activity. Conversely, "super-Earths", terrestrial planets with higher masses than Earth, would have higher levels of plate tectonics and thus be firmly placed in the habitable range.

text: "Low mass" is partly a relative label: the Earth is low mass when compared to the Solar System's

text: gas giant

text: s, but it is the largest, by diameter and mass, and the densest of all terrestrial bodies. It is large enough to retain an atmosphere through gravity alone and large enough that its molten core remains a heat engine, driving the diverse geology of the surface (the decay of

text: radioactive

text: elements within a planet's core is the other significant component of planetary heating). Mars, by contrast, is nearly (or perhaps totally) geologically dead and has lost much of its atmosphere. Thus it would be fair to infer that the lower mass limit for habitability lies somewhere between that of Mars and that of Earth or Venus: 0.3 Earth masses has been offered as a rough dividing line for habitable planets. However, a 2008 study by the Harvard-Smithsonian Center for Astrophysics suggests that the dividing line may be higher. Earth may in fact lie on the lower boundary of habitability: if it were any smaller, plate tectonics would be impossible. Venus, which has 85% of Earth's mass, shows no signs of tectonic activity. Conversely, "

text: super-Earth

text: s", terrestrial planets with higher masses than Earth, would have higher levels of plate tectonics and thus be firmly placed in the habitable range.

text: Earth's rotation is the rotation of the planet Earth around its own axis. The Earth rotates from the west towards east. As viewed from North Star or polestar Polaris, the Earth turns counter-clockwise.

text: Earth's rotation is the

text: rotation

text: of the planet

text: Earth

text: around its own

text: axis

text: . The Earth rotates from the west towards

text: east

text: . As viewed from North Star or polestar

text: Polaris

text: , the Earth turns counter-clockwise.

text: Three decades later, when Earth's magnetic field was better understood, theories were advanced suggesting that the Earth's field might have reversed in the remote past. Most paleomagnetic research in the late 1950s included an examination of the wandering of the poles and continental drift. Although it was discovered that some rocks would reverse their magnetic field while cooling, it became apparent that most magnetized volcanic rocks preserved traces of the Earth's magnetic field at the time the rocks had cooled. In the absence of reliable methods for obtaining absolute ages for rocks, it was thought that reversals occurred approximately every million years.

text: Three decades later, when Earth's magnetic field was better understood, theories were advanced suggesting that the Earth's field might have reversed in the remote past. Most paleomagnetic research in the late 1950s included an examination of the wandering of the poles and

text: continental drift

text: . Although it was discovered that some rocks would reverse their magnetic field while cooling, it became apparent that most magnetized volcanic rocks preserved traces of the Earth's magnetic field at the time the rocks had cooled. In the absence of reliable methods for obtaining absolute ages for rocks, it was thought that reversals occurred approximately every million years.

text: The planet's discovery was announced on August 25, 2004. At the time, its minimum mass was reported at just 14 times that of Earth, although later work established a value of 10.5 Earth masses. It orbits very close to Mu Arae, completing one revolution every 9.6 days.  The discovery was made with the aid of the High Accuracy Radial Velocity Planet Searcher (HARPS) spectrograph, at the European Southern Observatory's La Silla Observatory in Chile.  The data that revealed the presence of this planet was gathered on 8 nights of observations in June 2004.

text: The planet's discovery was announced on August 25, 2004. At the time, its minimum mass was reported at just 14 times that of

text: Earth

text: , although later work established a value of 10.5 Earth masses. It orbits very close to

text: Mu Arae

text: , completing one revolution every 9.6 days.  The discovery was made with the aid of the

text: (HARPS)

text: spectrograph

text: , at the

text: European Southern Observatory

text: 's

text: La Silla Observatory

text: in

text: Chile

text: .  The data that revealed the presence of this planet was gathered on 8 nights of observations in June 2004.

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: The song, 'The Proving Ground', was used during an episode of acclaimed television show China Beach and Wall's cover of The Zombies hit 'Time Of The Season' was included on the internationally released soundtrack for China Beach. Videos from the debut CD were in regular rotation on VH1 and Wendy Wall appeared as the musical guest star on Late Night with David Letterman, The Joan Lunden Show and was the musical guest star on the 1/2 hour music and talk show Nile Rodger's Inner Visions on VH1. The first single "Postcard to the Stars", a commentary on planet earth and the humans that inhabit it was featured on VH1's Earth Day Special Event.

text: The most celebrated test of Earth's rotation is the Foucault pendulum first built by physicist Léon Foucault in 1851, which consisted of a lead-filled brass sphere suspended  from the top of the Panthéon in Paris. Because of the Earth's rotation under the swinging pendulum, the pendulum's plane of oscillation appears to rotate at a rate depending on latitude. At the latitude of Paris the predicted and observed shift was about  clockwise per hour. Foucault pendulums now swing in museums around the world.

text: The most celebrated test of Earth's rotation is the

text: Foucault pendulum

text: first built by physicist

text: Léon Foucault

text: in 1851, which consisted of a lead-filled brass sphere suspended  from the top of the

text: Panthéon

text: in Paris. Because of the Earth's rotation under the swinging pendulum, the pendulum's plane of oscillation appears to rotate at a rate depending on latitude. At the latitude of Paris the predicted and observed shift was about

text: clockwise

text: per hour. Foucault pendulums now swing in

text: museums around the world

text: The Earth–Moon system is unique in that the ratio of the mass of the Moon to the mass of Earth is much greater than that of any other natural-satellite–planet ratio in the Solar System (although there are minor-planet systems with even greater ratios, notably the Pluto–Charon system). At 3,474 km (2,158 miles) across, Earth's Moon is 0.27 times the diameter of Earth.

text: The Earth–Moon system is unique in that the ratio of the mass of the Moon to the mass of Earth is much greater than that of any other natural-satellite–planet ratio in the

text: Solar System

text: (although there are minor-planet systems with even greater ratios, notably the

text: Pluto

text: Charon

text: system). At 3,474 km (2,158 miles) across, Earth's Moon is 0.27 times the diameter of Earth.

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: The discovery of the low-density Earth-mass planet Kepler-138d shows that there is an overlapping range of masses in which both rocky planets and low-density planets occur. Low-mass low-density planets could be ocean planets or super-Earths with a remnant hydrogen atmosphere, or hot planets with a steam atmosphere, or mini-Neptunes with a hydrogen–helium atmosphere.Other possibilities for low-mass low-density planets are large atmospheres of carbon monoxide, carbon dioxide, methane, or nitrogen.

text: The discovery of the low-density Earth-mass planet

text: d shows that there is an overlapping range of masses in which both rocky planets and low-density planets occur. Low-mass low-density planets could be ocean planets or

text: super-Earth

text: s with a remnant hydrogen atmosphere, or hot planets with a steam atmosphere, or mini-Neptunes with a hydrogen–helium atmosphere.Other possibilities for low-mass low-density planets are large atmospheres of

text: carbon monoxide

text: carbon dioxide

text: methane

text: , or

text: nitrogen

text: Size is often thought to be a significant factor, as planets of Earth's size are thought more likely to be terrestrial in nature and be capable of retaining an Earth-like atmosphere.

text: It is possible that diamonds exist on Saturn and Jupiter on the basis of a different prior theory by Reginald B. Little. In 2000-03, Little previously proposed (2000) and demonstrated (2003). that a strong magnetic field can organize diamonds at lower temperatures and pressures relative to the higher pressure and temperatures formations from amorphous carbon and/or graphite.  In 2005, Little realized that lightning could also provide such a magnetic field to directly transform graphite and elemental carbon to diamond and Reginald Little experimentally observed Nanodiamonds form from terrestrial lightning bolts upon solid carbon in 2009.  Therefore, on the basis of his prior work, Reginald Little reasoned in 2013 that diamond particles can form and exist in the lightning storms and clouds on Saturn and Jupiter but by the direct cloud transformation of carbon to small diamond particles by lightning strikes in such clouds.  As Baines and Delitsky report here in 2013, the lightning striking methane generates elemental carbon in clouds on Saturn and Jupiter, but Little asserts that the diamonds form not from the carbon sinking into the core of these planets but by subsequent lightning strikes on the generated carbon in the clouds.  Therefore, Little suggests that the lightning directly transforms the elemental carbon to small diamond particles in the clouds with such diamonds in the clouds sticking together and falling as diamond hail.  As the diamond hail falls it is chemically etched by the hydrogen in these planets under higher pressure and temperatures to reform methane gas.  The resulting methane gas rises back to reform clouds to create a cycle of hydrogen-methane cloud forming diamond hail at higher elevations (by lightning) and the resulting diamond hail reforming hydrogen methane as it (the diamond) falls to lower elevations by temperatures for a diamond-hydrogen to methane cycle on these planets of similarity and analog to water-steam-ice cycle in thunderstorms on Earth.  Such a cycle is important on these planets of Saturn and Jupiter to explain the prevailing presence of methane in their atmospheres.  If the methane as by Baines and Delitsky is irreversibly converted to elemental carbon and to graphite at lower elevation and irreversibly to diamond at even lower elevations in Saturn and Jupiter then the atmospheres would be completely stripped of methane which is inconsistent with the persisting hydrogen, methane ammonia clouds of these planets.  But unlike Baines and Delitsky prior theory of diamond forming toward the interior of these planets as the carbon falls (2013), Reginald Little asserts that the diamond forms in the clouds directly from frequent lightning striking the elemental carbon in the clouds.  Reginald Little in 2005 also proposed that lightning striking Kimberlites on earth may explain diamond in certain Kimberlitic rocks relative to non producing Kimberlitic rock on Earth.  Reginald Little correlated the most producing Kimberlitic rock with regions on the Earth with the highest yearly frequency cloud to ground lightning central to southern Africa.  Prior to the birth of science, over thousands of years ago some ancient people in India believed that diamonds form by lightning striking rock but this belief was non scientific as there was no elemental basis for diamond and they believed granite would form diamond as well as slates, phyllites, mylonite, jade, marble, soapstone, and serpentine.  The true theory and prediction came with Reginald Little in 2000. As only Carbonaceous rock perhaps with some iron only form diamond when struck by lightning. Extending this theory to other planets of Saturn and Jupiter as inspired by Baines and Delitsky, rather naturally and beautifully reasons direct transformation of elemental carbon to diamond by lightning at high elevation in the clouds of Saturn and Jupiter is not subject to thermodynamics of chemically etching of diamond and mixing in the interior of the planets. As at higher elevations in the clouds of these planets the temperature is very low so such thermodynamic mixing is infeasible but the thermal quenching of the lightning transformed diamond is feasible.  This model and mechanism of Reginald Little is also not subject to the low methane concentration argument. as the carbon is concentrated in from initial low methane concentrations by prior lightning strikes.  So very frequent lightning strikes and severe lightning storms in these planets tend to support. Reginald Little diamond cloud theory in Saturn and Jupiter.!

text: It is possible that diamonds exist on

text: Saturn

text: and

text: Jupiter

text: on the basis of a different prior theory by Reginald B. Little. In 2000-03, Little previously proposed (2000) and demonstrated (2003). that a strong magnetic field can organize diamonds at lower temperatures and pressures relative to the higher

text: pressure and temperatures

text: formations from

text: amorphous carbon

text: and/or

text: graphite

text: .  In 2005, Little realized that

text: lightning

text: could also provide such a

text: magnetic

text: field to directly transform

text: graphite

text: and elemental carbon to diamond and Reginald Little experimentally observed

text: Nanodiamonds

text: form from

text: terrestrial lightning bolts

text: upon solid

text: carbon

text: in 2009.  Therefore, on the basis of his prior work, Reginald Little reasoned in 2013 that diamond particles can form and exist in the

text: lightning storms and clouds

text: on

text: Saturn

text: and

text: Jupiter

text: but by the direct cloud transformation of

text: carbon

text: to small diamond particles by lightning strikes in such clouds.  As Baines and Delitsky report here in 2013, the

text: lightning striking

text: methane

text: generates elemental carbon in clouds on

text: Saturn

text: and

text: Jupiter

text: , but Little asserts that the diamonds form not from the carbon sinking into the core of these planets but by subsequent lightning strikes on the generated carbon in the clouds.  Therefore, Little suggests that the lightning directly transforms the elemental carbon to small diamond particles in the clouds with such diamonds in the clouds sticking together and falling as diamond hail.  As the diamond hail falls it is chemically etched by the

text: hydrogen

text: in these planets under higher

text: pressure and temperatures

text: to reform methane gas.  The resulting

text: methane gas

text: rises back to reform clouds to create a cycle of

text: hydrogen-methane

text: cloud forming diamond hail at higher elevations (by lightning) and the resulting diamond hail reforming

text: hydrogen

text: methane

text: as it (the diamond) falls to lower elevations by

text: temperatures

text: for a diamond-hydrogen to

text: methane

text: cycle on these planets of similarity and analog to water-steam-ice cycle in thunderstorms on Earth.  Such a cycle is important on these planets of

text: Saturn

text: and

text: Jupiter

text: to explain the prevailing presence of

text: methane

text: in their atmospheres.  If the methane as by Baines and Delitsky is irreversibly converted to elemental carbon and to

text: graphite

text: at lower elevation and irreversibly to diamond at even lower elevations in

text: Saturn

text: and

text: Jupiter

text: then the

text: atmospheres

text: would be completely stripped of

text: methane

text: which is inconsistent with the persisting

text: hydrogen

text: , methane

text: ammonia clouds

text: of these planets.  But unlike Baines and Delitsky prior theory of diamond forming toward the interior of these planets as the carbon falls (2013), Reginald Little asserts that the diamond forms in the clouds directly from frequent lightning striking the elemental carbon in the clouds.  Reginald Little in 2005 also proposed that lightning striking

text: Kimberlite

text: s on

text: earth

text: may explain diamond in certain

text: Kimberlitic

text: rocks relative to non producing

text: Kimberlitic

text: rock on Earth.  Reginald Little correlated the most producing

text: Kimberlitic

text: rock with regions on the Earth with the highest yearly frequency cloud to ground lightning central to

text: southern Africa

text: .  Prior to the birth of science, over thousands of years ago some ancient people in India believed that diamonds form by lightning striking rock but this belief was non scientific as there was no elemental basis for diamond and they believed granite would form diamond as well as

text: slate

text: s,

text: phyllite

text: s,

text: mylonite

text: jade

text: marble

text: soapstone

text: , and

text: serpentine

text: .  The true theory and prediction came with Reginald Little in 2000. As only Carbonaceous rock perhaps with some iron only form diamond when struck by lightning. Extending this theory to other planets of

text: Saturn

text: and

text: Jupiter

text: as inspired by Baines and Delitsky, rather naturally and beautifully reasons direct transformation of elemental carbon to diamond by lightning at high elevation in the clouds of

text: Saturn

text: and

text: Jupiter

text: is not subject to

text: thermodynamics

text: of chemically etching of diamond and mixing in the interior of the planets. As at higher elevations in the clouds of these planets the temperature is very low so such

text: thermodynamic

text: mixing is infeasible but the thermal quenching of the lightning transformed diamond is feasible.  This model and mechanism of Reginald Little is also not subject to the low methane concentration argument. as the

text: carbon

text: is concentrated in from initial low

text: methane

text: concentrations by prior lightning strikes.  So very frequent lightning strikes and severe lightning storms in these planets tend to support. Reginald Little diamond cloud theory in

text: Saturn

text: and

text: Jupiter

text: Earth's gravity reaches out far past the Van Allen radiation belt and keeps the Moon in orbit at an average distance of . The region of space where the gravity of a planet tends to dominate the motion of objects in the presence of other perturbing bodies (such as another planet) is known as the Hill sphere. For Earth, this sphere has a radius of about .

text: Earth's gravity reaches out far past the

text: Van Allen radiation belt

text: and keeps the Moon in orbit at an average distance of . The region of space where the gravity of a planet tends to dominate the motion of objects in the presence of other perturbing bodies (such as another planet) is known as the

text: Hill sphere

text: . For Earth, this sphere has a radius of about .

text: While  the astronomical community widely agrees that Planet X, as originally envisioned, does not exist, the concept of an as-yet-unobserved planet has been revived by a number of astronomers to explain other anomalies observed in the outer Solar System.  As of March 2014, observations with the WISE telescope have ruled out the possibility of a Saturn-sized object (95 Earth mass) out to 10,000 AU, and a Jupiter-sized (~318 Earth mass) or larger object out to 26,000 AU.

text: While  the astronomical community widely agrees that Planet X, as originally envisioned, does not exist, the concept of an as-yet-unobserved planet has been revived by a number of astronomers to explain other anomalies observed in the outer

text: Solar System

text: .  As of March 2014, observations with the

text: WISE telescope

text: have ruled out the possibility of a

text: Saturn

text: -sized object (95 Earth mass) out to 10,000

text: AU

text: , and a

text: Jupiter

text: -sized (~318 Earth mass) or larger object out to 26,000 AU.

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: To an observer in an inertial frame of reference, the planet Earth is seen to rotate about an axis and revolve around the Sun in an elliptical path with the Sun at one focus. The Earth's axis is tilted with respect to the plane of the Earth's orbit and this axis maintains a position that changes little with respect to the background of stars. An observer on Earth therefore sees a solar path that is the result of both rotation and revolution.

text: To an observer in an

text: inertial frame of reference

text: , the

text: planet Earth is seen to rotate

text: about an

text: axis

text: and

text: revolve

text: around the Sun in an

text: elliptical

text: path with the Sun at one

text: focus

text: . The Earth's axis is

text: tilted

text: with respect to the

text: plane of the Earth's orbit

text: and this axis maintains a position that changes little with respect to the background of

text: star

text: s. An observer on Earth therefore sees a solar path that is the result of both rotation and revolution.

text: A number of characters, heroes and villains, had counterparts on both Earth-One and Two. Generally speaking, the older Earth-Two versions were phased out or incorporated into their younger, Earth-One versions following Crisis on Infinite Earths. Several others were rebooted almost entirely, with their new versions having nothing in common with the old ones. For instance, Jim Corrigan of Earth-Two was a murdered police detective who served as the human host for the Spectre, while his Earth-One counterpart was a Metropolis police officer who often assisted Daily Planet cub reporter Jimmy Olsen and superhero Black Lightning. Many characters would often travel from one Earth to the other and interact with its natives or even immigrate. For example, Larry Jordan, the first Air Wave and native of Earth-Two, traveled to Earth-One under yet-unexplained circumstances, married Helen (the second Air Wave) and raised a son, Hal (the third Air Wave).

text: A number of characters, heroes and villains, had counterparts on both Earth-One and Two. Generally speaking, the older Earth-Two versions were phased out or incorporated into their younger, Earth-One versions following Crisis on Infinite Earths. Several others were rebooted almost entirely, with their new versions having nothing in common with the old ones. For instance,

text: Jim Corrigan of Earth-Two

text: was a murdered police detective who served as the human host for the

text: Spectre

text: , while his

text: Earth-One counterpart

text: was a

text: Metropolis

text: police officer who often assisted

text: Daily Planet

text: cub reporter

text: Jimmy Olsen

text: and superhero

text: Black Lightning

text: . Many characters would often travel from one Earth to the other and interact with its natives or even immigrate. For example, Larry Jordan, the first

text: Air Wave

text: and native of Earth-Two, traveled to Earth-One under yet-unexplained circumstances, married

text: Helen

text: (the second Air Wave) and raised a son,

text: Hal

text: (the third Air Wave).

text: The giant impact theory hypothesizes that the Moon resulted from the impact of a Mars-sized body, Theia, with the very young Earth. This giant impact also gave the Earth its axial tilt and velocity of rotation. Rapid rotation reduces the daily variation in temperature and makes photosynthesis viable. The Rare Earth hypothesis further argues that the axial tilt cannot be too large or too small (relative to the orbital plane). A planet with a large tilt (inclination) will experience extreme seasonal variations in climate, unfriendly to complex life. A planet with little or no tilt will lack the stimulus to evolution that climate variation provides. In this view, the Earth's tilt is "just right". The gravity of a large satellite also stabilizes the planet's tilt; without this effect the variation in tilt would be chaotic, probably making complex life forms on land impossible.

text: The

text: giant impact theory

text: hypothesizes that the Moon resulted from the impact of a

text: Mars

text: -sized body,

text: Theia

text: , with the very young Earth. This giant impact also gave the Earth its

text: axial tilt

text: and velocity of rotation. Rapid rotation reduces the daily variation in temperature and makes

text: photosynthesis

text: viable. The Rare Earth hypothesis further argues that the axial tilt cannot be too large or too small (relative to the

text: orbital plane

text: ). A planet with a large tilt (inclination) will experience extreme seasonal variations in climate, unfriendly to complex life. A planet with little or no tilt will lack the stimulus to evolution that climate variation provides. In this view, the Earth's tilt is "just right". The gravity of a large satellite also stabilizes the planet's tilt; without this effect the

text: variation in tilt

text: would be

text: chaotic

text: , probably making complex life forms on land impossible.

text: Helliconia is 1.28 Earth masses in size, making it somewhat larger than Earth and with a bigger axial tilt of 35 degrees. This means that small year seasons are harsher but the planet still has huge polar ice caps, capable of surviving even the great summer, and the human-habitable surface area is comparable to that of Earth.

text: Helliconia is 1.28 Earth masses in size, making it somewhat larger than Earth and with a bigger

text: axial tilt

text: of 35 degrees. This means that small year seasons are harsher but the planet still has huge

text: polar ice cap

text: s, capable of surviving even the great summer, and the

text: human-habitable

text: surface area is comparable to that of Earth.

text: Geophysical fluid dynamics is the study of naturally occurring, large-scale flows on Earth and other planets. It is applied to the motion of fluids in the ocean and outer core, and to gases in the atmosphere of Earth and other planets. Two features that are common to many of the phenomena studied in geophysical fluid dynamics are rotation of the fluid due to the planetary rotation and stratification (layering). The applications of geophysical fluid dynamics do not generally include the circulation of the mantle, which is the subject of geodynamics, or fluid phenomena in the magnetosphere. Flows of smaller scale that are relatively unaffected by Earth's rotation or latitude or substantial layering are not part of GFD.

text: Geophysical fluid dynamics is the study of naturally occurring, large-scale flows on

text: Earth

text: and other

text: planet

text: s. It is applied to the motion of

text: fluid

text: s in the

text: ocean

text: and

text: outer core

text: , and to

text: gases

text: in the

text: atmosphere

text: of Earth and other planets. Two features that are common to many of the phenomena studied in geophysical fluid dynamics are

text: rotation of the fluid

text: due to the planetary rotation and

text: stratification

text: (layering). The applications of geophysical fluid dynamics do not generally include the circulation of the

text: mantle

text: , which is the subject of

text: geodynamics

text: , or fluid phenomena in the

text: magnetosphere

text: . Flows of smaller scale that are relatively unaffected by Earth's rotation or

text: latitude

text: or substantial layering are not part of GFD.

text: In 1996, a possible Saturn-like (100 Earth mass) gas giant was announced orbiting the pulsar at a distance of about 40 AU.  The original hypothesis was retracted and a reinterpretation of the data led to a new hypothesis of a dwarf planet one-fifth the size of Pluto orbiting PSR B1257+12 at an average orbital distance of 2.4 AU with an orbital period of approximately 4.6 years. The dwarf planet hypothesis was also retracted because further observations showed that the pulsation anomalies previously thought to reveal a fourth orbital body are "not periodic and can be fully explained in terms of slow changes in the pulsar’s dispersion measure."

text: In 1996, a possible

text: Saturn

text: -like (100 Earth mass)

text: gas giant

text: was announced orbiting the pulsar at a distance of about 40 AU.  The original hypothesis was retracted and a reinterpretation of the data led to a new hypothesis of a

text: dwarf planet

text: one-fifth the size of

text: Pluto

text: orbiting PSR B1257+12 at an average orbital distance of 2.4 AU with an orbital period of approximately 4.6 years. The dwarf planet hypothesis was also retracted because further observations showed that the pulsation anomalies previously thought to reveal a fourth orbital body are "not periodic and can be fully explained in terms of slow changes in the pulsar’s dispersion measure."

text: If a super-Earth is detectable by both the radial-velocity and the transit methods, then both its mass and its radius can be determined; thus its average bulk density can be calculated. The actual empirical observations are giving similar results as theoretical models, as it's found that planets larger than approximately 1.6 Earth-radius (more massive than approximately 6 Earth-masses) contain significant fractions of volatiles or H/He gas (such planets appear to have a diversity of compositions that is not well-explained by a single mass-radius relation as that found in rocky planets). After measuring 65 super-Earths smaller than 4 Earth-radii, the empirical data points out that Gas Dwarves would be the most usual composition: there is a trend where planets with radii up to 1.5 Earth-radii increase in density with increasing radius, but above 1.5 radii 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. Similar results are confirmed by other studies.

text: Tyson continues to note that despite losing some of his mental capacity, Faraday concluded that electricity and magnetism were connected by unseen fields, and postulated that light may also be tied to these forces. Using a sample of the optical glass that Davy had him make, Faraday discovered that an applied magnetic field could affect the polarization of light passing through the glass sample (a dielectric material), leading to what is called the Faraday effect and connecting these three forces. Faraday postulated that these fields existed across the planet, which would later by called Earth's magnetic field generated by the rotating molten iron inner core, as well as the phenomena that caused the planets to rotate around the sun. Faraday's work was initially rejected by the scientific community due to his lack of mathematical support, but James Clerk Maxwell would later come to rework Faraday's theories into the Maxwell's equations that validated Faraday's theories. Their combined efforts created the basis of science that drives the principles of modern communications today.

text: Tyson continues to note that despite losing some of his mental capacity, Faraday concluded that electricity and magnetism were connected by unseen fields, and postulated that light may also be tied to these forces. Using a sample of the optical glass that Davy had him make, Faraday discovered that an applied magnetic field could affect the

text: polarization

text: of light passing through the glass sample (a

text: dielectric material

text: ), leading to what is called the

text: Faraday effect

text: and connecting these three forces. Faraday postulated that these fields existed across the planet, which would later by called

text: Earth's magnetic field

text: generated by the rotating molten iron

text: inner core

text: , as well as the phenomena that caused the planets to rotate around the sun. Faraday's work was initially rejected by the scientific community due to his lack of mathematical support, but

text: James Clerk Maxwell

text: would later come to rework Faraday's theories into the

text: Maxwell's equations

text: that validated Faraday's theories. Their combined efforts created the basis of science that drives the principles of modern communications today.

text: Although planets can sometimes be mistaken for stars as one observes the night sky, the planets actually change position from night to night in relation to the stars. Retrograde (backward) and prograde (forward) are observed as though the stars revolve around the Earth.  Ancient Greek astronomer Ptolemy in 150 AD believed that the Earth was the center of the Solar System and therefore used the terms retrograde and prograde to describe the movement of the planets in relation to the stars.  Although it is known today that the planets revolve around the sun, the same terms continue to be used in order to describe the movement of the planets in relation to the stars as they are observed from Earth.  Like the sun, the planets appear to rise in the East and set in the West.  When a planet travels eastward in relation to the stars, it is called prograde.  When the planet travels westward in relation to the stars (opposite path) it is called retrograde.

text: Although planets can sometimes be mistaken for stars as one observes the night sky, the planets actually change position from night to night in relation to the stars. Retrograde (backward) and prograde (forward) are observed as though the stars revolve around the Earth.  Ancient Greek astronomer Ptolemy in 150 AD believed that the Earth was the center of the

text: Solar System

text: and therefore used the terms retrograde and prograde to describe the movement of the planets in relation to the stars.  Although it is known today that the planets revolve around the sun, the same terms continue to be used in order to describe the movement of the planets in relation to the stars as they are observed from Earth.  Like the sun, the planets appear to rise in the East and set in the West.  When a planet travels eastward in relation to the stars, it is called prograde.  When the planet travels westward in relation to the stars (opposite path) it is called retrograde.

text: The south polar permanent cap is much smaller than the one in the north.  It is 400 km in diameter, as compared to the 1100 km diameter of the northern cap. Each southern winter, the ice cap covers the surface to a latitude of 50°.  Part of the ice cap consists of dry ice, solid carbon dioxide.  Each winter the ice cap grows by adding 1.5 to 2 meters of dry ice from precipitation from a polar-hood of clouds.  In summer, the dry ice sublimates (goes directly from a solid to a gas) into the atmosphere.  During each year on Mars as much as a third of Mars' thin carbon dioxide (CO) atmosphere "freezes out" during the winter in the northern and southern hemispheres. Scientists have even measured tiny changes in the gravity field of Mars due to the movement of carbon dioxide.  In other words, the winter buildup of ice changes the gravity of the planet.  Mars has seasons that are similar to Earth's because its rotational axis has a tilt close to our own Earth's (25.19° for Mars, 23.45° for Earth).  The south polar cap is higher in altitude and colder than the one in the north.

text: The south polar permanent cap is much smaller than the one in the north.  It is 400 km in diameter, as compared to the 1100 km diameter of the northern cap. Each southern winter, the ice cap covers the surface to a latitude of 50°.  Part of the ice cap consists of

text: dry ice

text: , solid

text: carbon dioxide

text: .  Each winter the ice cap grows by adding 1.5 to 2 meters of dry ice from precipitation from a polar-hood of clouds.  In summer, the dry ice sublimates (goes directly from a solid to a gas) into the atmosphere.  During each year on Mars as much as a third of Mars' thin carbon dioxide (CO) atmosphere "freezes out" during the winter in the northern and southern hemispheres. Scientists have even measured tiny changes in the

text: gravity

text: field of Mars due to the movement of carbon dioxide.  In other words, the winter buildup of ice changes the gravity of the planet.  Mars has seasons that are similar to Earth's because its rotational axis has a tilt close to our own Earth's (25.19° for Mars, 23.45° for Earth).  The south polar cap is higher in altitude and colder than the one in the north.

text: Mohan spies the alien Malla one night as Malla is getting ready to return to his planet. They have a brief skirmish and Malla dies. Thinna lands in his spacecraft just then to take Malla home. He sees Malla’s corpse and places it in an ante-chamber inside the craft. Watching all this, Mohan enters the craft quickly, and dragging Malla’s corpse out, he jumps into the ante-chamber. Thinna does not notice this and takes off from the earth. When he nearing his planet, he ejects what he assumes to be Malla’s corpse from his spacecraft, but it is actually Mohan who falls into the alien planet. By happenstance Mohan comes across a kind-hearted jester from another planet who is on the way to the palace. This jester takes Mohan to his house and feeds him. As they step outside, the jester is struck dead by a passing meteor. As luck would have it, the jester had resembled Mohan in facial features, and so Mohan takes his place and goes to the palace. There he meets Vani and manages to make her realize his true identity. They outwit the cunning Thinna and return to the earth. Meanwhile Kannan is caught strangling Valli and is arrested by the police. Mohan and Vani reach home. All is well that ends well.

text: Assuming its true mass is comparable to those of Neptune and Gliese 436 b, 14 Earth masses is theoretically the maximum size for a terrestrial planet. A rocky planet this size could certainly have formed, since Mu Arae has a higher metallicity than our Sun. Also, it is thought to have formed well inside the system's "snow line" at 3.2 AU. However, various models of the system's formation have since converged that the planet attracted large amounts of volatiles before its star had cleared out the ice, and that it now has a core of only 6 Earth masses. Its core is likely enveloped in so much hot-ice and gas that the planet would behave more like Neptune.

text: Assuming its true mass is comparable to those of

text: Neptune

text: and

text: Gliese 436 b

text: , 14 Earth masses is theoretically the maximum size for a terrestrial planet. A rocky planet this size could certainly have formed, since Mu Arae has a higher

text: metallicity

text: than our Sun. Also, it is thought to have formed well inside the system's "snow line" at 3.2 AU. However, various models of the system's formation have since converged that the planet attracted large amounts of volatiles before its star had cleared out the ice, and that it now has a core of only 6 Earth masses. Its core is likely enveloped in so much hot-ice and gas that the planet would behave more like Neptune.

text: Unlike conventional planetariums, which are limited to showing the night sky as it appears from various points on the surface of the Earth at various dates, the STS could show the sky as it would appear from anywhere within about 100 astronomical units of Earth (about three times the radius of Pluto's orbit).  A joystick even allowed the operator to "fly" the theater through space, showing the resulting apparent movement of planets through the sky, though in practice the planetarium presentations were always pre-programmed.

text: Unlike conventional planetariums, which are limited to showing the night sky as it appears from various points on the surface of the Earth at various dates, the STS could show the sky as it would appear from anywhere within about 100

text: astronomical units

text: of Earth (about three times the radius of Pluto's orbit).  A joystick even allowed the operator to "fly" the theater through space, showing the resulting apparent movement of planets through the sky, though in practice the planetarium presentations were always pre-programmed.

text: The standard acceleration due to gravity (or standard acceleration of free fall), sometimes abbreviated as standard gravity, usually denoted by  or , is the nominal gravitational acceleration of an object in a vacuum near the surface of the Earth. It is defined by standard as , which is exactly  (about , or ). This value was established by the 3rd CGPM (1901, CR 70) and used to define the standard weight of an object as the product of its mass and this nominal acceleration. The acceleration of a body near the surface of the Earth is due to the combined effects of gravity and centrifugal acceleration from rotation of the Earth (but which is small enough to be neglected for most purposes); the total (the apparent gravity) is about 0.5 percent greater at the poles than at the equator.

text: The standard acceleration due to gravity (or standard acceleration of free fall), sometimes abbreviated as standard gravity, usually denoted by  or , is the nominal

text: gravitational acceleration

text: of an object in a vacuum near the surface of the Earth. It is

text: defined by standard

text: as , which is exactly  (about , or ). This value was established by the 3rd

entity_name: General Conference on Weights and Measures

text: CGPM

text: (1901, CR 70) and used to define the standard

text: weight

text: of an object as the product of its mass and this nominal acceleration. The acceleration of a body near the surface of the Earth is due to the combined effects of

text: gravity

text: and

text: centrifugal acceleration

text: from rotation of the Earth (but which is small enough to be neglected for most purposes); the total (the apparent gravity) is about 0.5 percent greater at the poles than at the equator.

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: TVLM513-46546 is an ultracool brown dwarf in the constellation Boötes, exhibiting a flare star activity and all the same varying semi-regularly due to dissimilarly bright hemispheres and a rotation period of about two days. The star has a mass as low as 90 times the mass of Jupiter (or 9 percent of Sun's mass) and an estimated radius of 11 percent that of Sun (nearly a Jupiter-sized star). The star also shows hints of an unseen companion with undetermined mass. Future monitoring will be able to confirm or rule out low-mass stellar or even planetary mass companions (down to 2-10 Jupiter masses), with orbital periods spanning between 1 and 15 days. Assuming a stellar luminosity of 0.042 percent that of Sun, the habitable zone where an Earth-like planet may retain liquid water at comfortable temperatures would be located within 0.02 Astronomical Units (roughly 10 times the distance of the Moon from Earth).

text: TVLM513-46546 is an ultracool

text: brown dwarf

text: in the constellation

text: Boötes

text: , exhibiting a

text: flare star

text: activity and all the same varying semi-regularly due to dissimilarly bright hemispheres and a rotation period of about two days. The star has a mass as low as 90 times the mass of

text: Jupiter

text: (or 9 percent of

text: Sun

text: 's mass) and an estimated radius of 11 percent that of

text: Sun

text: (nearly a

text: Jupiter

text: -sized star). The star also shows hints of an unseen companion with undetermined mass. Future monitoring will be able to confirm or rule out low-mass stellar or even planetary mass companions (down to 2-10

text: Jupiter

text: masses), with orbital periods spanning between 1 and 15

text: day

text: s. Assuming a stellar luminosity of 0.042 percent that of

text: Sun

text: , the habitable zone where an

text: Earth-like planet

text: may retain liquid water at comfortable temperatures would be located within 0.02

text: Astronomical Unit

text: s (roughly 10 times the distance of the

text: Moon

text: from

text: Earth

text: In physics, the dynamo theory proposes a mechanism by which a celestial body such as Earth or a star generates a magnetic field. The dynamo theory describes the process through which a rotating, convecting, and electrically conducting fluid can maintain a magnetic field over astronomical time scales.  A dynamo is thought to be the source of the Earth's magnetic field, as well as the magnetic fields of other planets.

text: In

text: physics

text: , the dynamo theory proposes a mechanism by which a celestial body such as

text: Earth

text: or a

text: star

text: generates a

text: magnetic field

text: . The dynamo theory describes the process through which a rotating,

text: convecting

text: , and

text: electric

text: ally conducting fluid can maintain a magnetic field over

text: astronomical

text: time scales.  A dynamo is thought to be the source of the

text: Earth's magnetic field

text: , as well as the magnetic fields of other planets.

text: Venus is one of the four terrestrial planets in the Solar System, meaning that it is a rocky body like Earth. It is similar to Earth in size and mass, and is often described as Earth's "sister" or "twin". The diameter of Venus is 12,092 km (only 650 km less than Earth's) and its mass is 81.5% of Earth's. Conditions on the Venusian surface differ radically from those on Earth because its dense atmosphere is 96.5% carbon dioxide, with most of the remaining 3.5% being nitrogen.

text: Venus is one of the four

text: terrestrial planet

text: s in the Solar System, meaning that it is a rocky body like Earth. It is similar to Earth in size and mass, and is often described as Earth's "sister" or "twin". The diameter of Venus is 12,092 km (only 650 km less than Earth's) and its mass is 81.5% of Earth's. Conditions on the Venusian surface differ radically from those on Earth because its dense

text: atmosphere

text: is 96.5%

text: carbon dioxide

text: , with most of the remaining 3.5% being

text: nitrogen

text: s instruments yielded significant data, including a characterization of Mercury's magnetic field and the discovery of water ice at the planet's north pole, which had long been suspected on the basis of Earth-based radar data.

text: s instruments yielded significant data, including a characterization of Mercury's magnetic field and the discovery of

text: water ice

text: at the planet's north pole, which had long been suspected on the basis of Earth-based radar data.

text: As the Sun expands, it will swallow the planets Mercury and Venus. Earth's fate is less clear; although the Sun will envelop Earth's current orbit, the star's loss of mass (and thus weaker gravity) will cause the planets' orbits to move farther out. If it were only for this, Venus and Earth would probably escape incineration, but a 2008 study suggests that Earth will likely be swallowed up as a result of tidal interactions with the Sun's weakly bound outer envelope.

text: As the Sun expands, it will swallow the planets

text: Mercury

text: and

text: Venus

text: Earth

text: 's fate is less clear; although the Sun will envelop Earth's current orbit, the star's loss of mass (and thus weaker gravity) will cause the planets' orbits to move farther out. If it were only for this, Venus and Earth would probably escape incineration, but a 2008 study suggests that Earth will likely be swallowed up as a result of

text: tidal interactions

text: with the Sun's weakly bound outer envelope.

text: was a science fiction toy line created, manufactured and marketed by Takara Co., Ltd. from 1974 to 1984 as well as from 1998 to 2007. At the core of the Microman line was a series of  action figures with accompanying vehicles, robots, playsets and accessories. Unlike other toylines at the time, Microman figures were marketed as being the “actual” size of the cyborg beings that were replicas of real “Micro” beings that hailed from the fictional planet known as “Micro Earth” and disguised themselves as action figures to hide on planet Earth.

text: was a

text: science fiction

text: toy line created, manufactured and marketed by

text: Takara Co., Ltd.

text: from 1974 to 1984 as well as from 1998 to 2007. At the core of the Microman line was a series of

text: action figures

text: with accompanying vehicles, robots, playsets and accessories. Unlike other toylines at the time, Microman figures were marketed as being the “actual” size of the

text: cyborg

text: beings that were replicas of real “Micro” beings that hailed from the fictional planet known as “Micro Earth” and disguised themselves as action figures to hide on planet

text: Earth

text: His article in Philosophical Transactions created much controversy, as he addressed the problems of Newton's theory, but provided few solutions to how to fix the calculations. After his return, he published his treatise Théorie de la figure de la terre (1743). In this work he promulgated the theorem, known as Clairaut's theorem, which connects the gravity at points on the surface of a rotating ellipsoid with the compression and the centrifugal force at the equator. This hydrostatic model of the shape of the Earth was founded on a paper by Colin Maclaurin, which had shown that a mass of homogeneous fluid set in rotation about a line through its centre of mass would, under the mutual attraction of its particles, take the form of an ellipsoid.  Under the assumption that the Earth was composed of concentric ellipsoidal shells of uniform density, Clairaut's theorem could be applied to it, and allowed the ellipticity of the Earth to be calculated from surface measurements of gravity. This proved Sir Issac Newton's theory that the shape of the Earth was an oblate ellipsoid.  In 1849 Stokes showed that Clairaut's result was true whatever the interior constitution or density of the Earth, provided the surface was a spheroid of equilibrium of small ellipticity.

text: His article in Philosophical Transactions created much controversy, as he addressed the problems of Newton's theory, but provided few solutions to how to fix the calculations. After his return, he published his treatise Théorie de la figure de la terre (1743). In this work he promulgated the theorem, known as

text: Clairaut's theorem

text: , which connects the

text: gravity

text: at points on the surface of a rotating

text: ellipsoid

text: with the compression and the centrifugal force at the

text: equator

text: . This hydrostatic model of the shape of the Earth was founded on a paper by

text: Colin Maclaurin

text: , which had shown that a mass of

text: homogeneous

text: fluid set in rotation about a line through its

text: centre of mass

text: would, under the mutual attraction of its particles, take the form of an

text: ellipsoid

text: .  Under the assumption that the Earth was composed of concentric ellipsoidal shells of uniform density, Clairaut's theorem could be applied to it, and allowed the ellipticity of the Earth to be calculated from surface measurements of gravity. This proved

text: Sir Issac Newton

text: 's theory that the shape of the Earth was an oblate ellipsoid.  In 1849

text: Stokes

text: showed that Clairaut's result was true whatever the interior constitution or density of the Earth, provided the surface was a spheroid of equilibrium of small ellipticity.

text: The first season began airing in Japan on October 6, 1974. Set in the year 2199, an alien race known as the "Gamilas" ("Gamilons" in the English Star Blazers dub) unleash radioactive meteorite bombs on Earth, rendering the planet's surface uninhabitable. Humanity has retreated into deep underground cities, but the radioactivity is slowly affecting them as well, with humanity's extinction estimated in one year. Earth's space fleet is hopelessly outclassed by the Gamilas and all seems lost until a message capsule from a mysterious crashed spaceship is retrieved on Mars. The capsule yields blueprints for a faster-than-light engine and an offering of help from Queen Starsha of the planet Iscandar in the Large Magellanic Cloud. She says that her planet has a device, the Cosmo-Cleaner D (Cosmo DNA), which can cleanse Earth of its radiation damage.

text: The first season began airing in Japan on October 6, 1974. Set in the year 2199, an alien race known as the "

text: Gamilas

text: " ("Gamilons" in the English

text: Star Blazers

text: dub) unleash radioactive

text: meteorite

text: bombs on Earth, rendering the planet's surface uninhabitable. Humanity has retreated into deep underground cities, but the radioactivity is slowly affecting them as well, with humanity's extinction estimated in one year. Earth's space fleet is hopelessly outclassed by the Gamilas and all seems lost until a message capsule from a mysterious crashed spaceship is retrieved on Mars. The capsule yields blueprints for a

text: faster-than-light

text: engine and an offering of help from Queen Starsha of the planet Iscandar in the

text: Large Magellanic Cloud

text: . She says that her planet has a device, the Cosmo-Cleaner D (Cosmo DNA), which can cleanse Earth of its radiation damage.

text: Earth Military Directorate In the year 2015, Earth had only the seasons of summer and winter, causing mass migration to USA, Central Asia and Europe. This caused a massive World War in which military technology became more destructive. At the brink of catastrophe, the alien species known as the Ord attacked, killing 1.5 million people at the first strike and another 2 million at the next invasion. The planet's militaries mobilized and joined together, forming the Earth Military Directorate. They recruited boys and girls into their ranks, training them in the combat of history, strategies and tactics. In 2060, driven for revenge for the lost people in the two invasions, the EMD invaded the Ord colonies at the system of Goe and slaughtered every last Ord by 2080. They colonized one of the system's planets as New Terra.

text: Due to the larger mass of super-Earths, their physical characteristics may differ from Earth's; theoretical models for super-Earths provide four possible main compositions according to their density: low density super-Earths are inferred to be composed mainly of hydrogen and helium (Mini-Neptunes); super-Earths of intermediate density are inferred to either have water as a major constituent (Ocean planets), or have a denser core enshrouded with an extended gaseous envelope (Gas dwarf or sub-Neptune). A super-Earth of high density is believed to be rocky and/or metallic, like Earth and the other terrestrial planets of the Solar System. A super-Earth's interior could be undifferentiated, partially differentiated, or completely differentiated into layers of different composition. Researchers at Harvard Astronomy Department have developed user-friendly online tools to characterize the bulk composition of the super-Earths. A study on Gliese 876 d by a team around Diana Valencia revealed that it would be possible to infer from a radius measured by the transit method of detecting planets and the mass of the relevant planet what the structural composition of a relevant super-Earth is. For Gliese 876 d, calculations range from 9,200 km (1.4 Earth radii) for a rocky planet and very large iron core to 12,500 km (2.0 Earth radii) for a watery and icy planet. Within this range of radii the super-Earth Gliese 876 d would have a surface gravity between 1.9g and 3.3g (19 and 32 m/s). However, this planet is not known to transit its host star.

text: Due to the larger mass of super-Earths, their physical characteristics may differ from Earth's; theoretical models for super-Earths provide four possible main compositions according to their density: low density super-Earths are inferred to be composed mainly of hydrogen and helium (

text: Mini-Neptune

text: s); super-Earths of intermediate density are inferred to either have water as a major constituent (

text: Ocean planet

text: s), or have a denser core enshrouded with an extended gaseous envelope (

text: Gas dwarf

text: or sub-Neptune). A super-Earth of high density is believed to be rocky and/or metallic, like Earth and the other terrestrial planets of the Solar System. A super-Earth's interior could be undifferentiated, partially differentiated, or completely differentiated into layers of different composition. Researchers at Harvard Astronomy Department have developed user-friendly online tools to characterize the bulk composition of the super-Earths. A study on Gliese 876 d by a team around

text: Diana Valencia

text: revealed that it would be possible to infer from a radius measured by the

text: transit method

text: of detecting planets and the mass of the relevant planet what the structural composition of a relevant super-Earth is. For

text: Gliese 876 d

text: , calculations range from 9,200 km (1.4 Earth radii) for a rocky planet and very large iron core to 12,500 km (2.0 Earth radii) for a watery and icy planet. Within this range of radii the super-Earth Gliese 876 d would have a surface

text: gravity

text: between 1.9

text: g

text: and 3.3g (19 and 32 m/s). However, this planet is not known to transit its host star.

text: In general, super-Earths are defined exclusively by their mass, and the term does not imply temperatures, compositions, orbital properties, habitability, or environments are cited in definitions of super-Earths. While sources generally agree on an upper bound of 10 Earth masses, (~69% of the mass of Uranus, which is the Solar System gas giant with the least mass), the lower bound varies from 1 or 1.9 to 5, with various other definitions appearing in the popular media. The term "super-Earth" is also used by astronomers to refer to planets bigger than Earth-like planets (from 0.8 to 1.25 Earth-radii), but smaller than mini-Neptunes (from 2 to 4 Earth-radii). This definition was made by the Kepler Mission. Some authors further suggest that the term be limited to planets without a significant atmosphere, or planets that have not just atmospheres but also solid surfaces or oceans with a sharp boundary between liquid and atmosphere, which the four giant planets in the Solar System do not have. Planets above 10 Earth masses are termed massive solid planets/mega-Earths or gas giant planets depending on whether they are mostly rock and ice or mostly gas.

text: In general, super-Earths are defined exclusively by their

text: mass

text: , and the term does not imply temperatures, compositions, orbital properties, habitability, or environments are cited in definitions of super-Earths. While sources generally agree on an upper bound of 10

text: Earth mass

text: es, (~69% of the mass of

text: Uranus

text: , which is the Solar System gas giant with the least mass), the lower bound varies from 1 or 1.9 to 5, with various other definitions appearing in the popular media. The term "super-Earth" is also used by astronomers to refer to planets bigger than Earth-like planets (from 0.8 to 1.25 Earth-radii), but smaller than

text: mini-Neptune

text: s (from 2 to 4 Earth-radii). This definition was made by the Kepler Mission. Some authors further suggest that the term be limited to planets without a significant atmosphere, or planets that have not just atmospheres but also solid surfaces or oceans with a sharp boundary between liquid and atmosphere, which the four giant planets in the Solar System do not have. Planets above 10 Earth masses are termed

entity_section: Massive solid planets and giant planets with massive cores

text: massive solid planet

text: s/

text: mega-Earth

text: s or

text: gas giant planet

text: s depending on whether they are mostly rock and ice or mostly gas.

text: The Gravity Well has trapped the Earth Fleet in orbit above the planet Stroggos. One of the marines who managed to land must now make his way to the Gravity Well to destroy it and free the fleet above and disable the entire defenses of the planet.

text: As Neri begins her father's mission, she is drawn farther and farther away from her island. Beginning in the middle of the third season, some episodes are primarily based on land. By the fourth season, some episodes are set in Egypt, and her father's quest eventually leads her back to the "Ocean Planet", her home planet. Most of the plots involving the secondary kids on ORCA are reduced in the final season, in order to allow for greater exploration of Neri's homeworld. Several new characters of Neri's species are introduced. Likewise, the threat of UBRI fades, to be replaced by a new organization, PRAXIS (Preventative Response And eXtraterritorial Intelligence Service) and by rebels on the Ocean Planet. This group is dedicated to protecting against any threats posed by extraterrestrial life, and its agents comes to believe Neri and her people are a problem for Earth. They thus chased Neri and the Bates boys around the world. When a mysterious underwater pyramid is discovered in the ocean, Neri and the Bates boys enter it and discover more about the Ocean Planet, and Neri's mission on Earth.

text: As Neri begins her father's mission, she is drawn farther and farther away from her island. Beginning in the middle of the third season, some episodes are primarily based on land. By the fourth season, some episodes are set in

text: Egypt

text: , and her father's quest eventually leads her back to the "Ocean Planet", her home planet. Most of the plots involving the secondary kids on ORCA are reduced in the final season, in order to allow for greater exploration of Neri's homeworld. Several new characters of Neri's species are introduced. Likewise, the threat of UBRI fades, to be replaced by a new organization, PRAXIS (Preventative Response And eXtraterritorial Intelligence Service) and by rebels on the Ocean Planet. This group is dedicated to protecting against any threats posed by

text: extraterrestrial life

text: , and its agents comes to believe Neri and her people are a problem for Earth. They thus chased Neri and the Bates boys around the world. When a mysterious underwater pyramid is discovered in the ocean, Neri and the Bates boys enter it and discover more about the Ocean Planet, and Neri's mission on Earth.

text: The acceleration due to Earth’s gravity (see Standard gravity) at its surface is 976 to 983 Gal, the variation being due mainly to differences in latitude and elevation.  Mountains and masses of lesser density within the Earth's crust typically cause variations in gravitational acceleration of tens to hundreds of milligals (mGal). The gravity gradient (variation with height) above Earth's surface is about 3.1 µGal per centimeter of height (), resulting in a maximal difference of about 2 Gal (0.02 m/s) from the top of Mount Everest to sea level.

text: The acceleration due to Earth’s gravity (see

text: Standard gravity

text: ) at its surface is 976 to 983 Gal, the variation being due mainly to differences in

text: latitude

text: and

text: elevation

text: .  Mountains and masses of lesser density within the Earth's crust typically cause variations in

text: gravitational acceleration

text: of tens to hundreds of milligals (mGal). The gravity

text: gradient

text: (variation with height) above Earth's surface is about 3.1 µGal per centimeter of height (), resulting in a maximal difference of about 2 Gal (0.02 m/s) from the top of

text: Mount Everest

text: to sea level.

text: Like COROT-7b, the mass of COROT-7c is weakly constrained, since the radial velocity data is noisy due to the presence of stellar activity. Published mass measurements range from 8.4 Earth masses to 13.5 Earth masses, passing through 12.4 Earth masses and 13.1 Earth masses. This mass range encompasses the Super-Earths to Neptunes transition, so the nature of COROT-7c, either a rocky planet or an ice giant, remains unclear. However, if the larger mass estimates are correct, COROT-7c is probably a hot Uranus-like planet. Chances are high that planet's rotation is tidally locked to the orbital period, with one side of the planet always facing the star COROT-7 and the other one in permanent darkness.  A possible third planet, COROT-7d, may be present in the system, but pending further observations its status remains unconfirmed. If this planet is confirmed, strong mutual gravitational forces could be exchanged between these planets, leading to powerful tidal forces.

text: Like

text: , the mass of COROT-7c is weakly constrained, since the radial velocity data is noisy due to the presence of stellar activity. Published mass measurements range from 8.4 Earth masses to 13.5 Earth masses, passing through 12.4 Earth masses and 13.1 Earth masses. This mass range encompasses the Super-Earths to Neptunes transition, so the nature of COROT-7c, either a

text: rocky planet

text: or an

text: ice giant

text: , remains unclear. However, if the larger mass estimates are correct, COROT-7c is probably a hot

text: Uranus

text: -like planet. Chances are high that planet's rotation is

text: tidally locked

text: to the orbital period, with one side of the planet always facing the star

text: and the other one in permanent darkness.  A possible third planet,

text: , may be present in the system, but pending further observations its status remains unconfirmed. If this planet is confirmed, strong mutual

text: gravitational forces

text: could be exchanged between these planets, leading to powerful

text: tidal forces

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: Kepler-11f is an exoplanet (extrasolar planet) discovered in the orbit of the sun-like star Kepler-11 by NASA's Kepler spacecraft, which searches for planets that transit (cross in front of) their host stars. Kepler-11f is the fifth planet from its star, orbiting one quarter of the distance (.25 AU) of the Earth from the Sun every 47 days. It is the furthest of the first five planets in the system. Kepler-11f is the least massive of Kepler-11's six planets, at nearly twice the mass of Earth; it is about 2.6 times the radius of Earth. Along with planets d and e and unlike the two inner planets in the system, Kepler-11f has a density lower than that of water and comparable to that of Saturn. This suggests that Kepler-11f has a significant hydrogen–helium atmosphere. The Kepler-11 planets constitute the first system discovered with more than three transiting planets. Kepler-11f was announced to the public on February 2, 2011 after follow-up investigations at several observatories.  Analysis of the planets and study results were published the next day  in the journal Nature.

text: Kepler-11f is an

text: exoplanet

text: (extrasolar planet) discovered in the orbit of the sun-like star

text: by

text: NASA

text: 's

text: Kepler spacecraft

text: , which searches for planets that

text: transit

text: (cross in front of) their host stars. Kepler-11f is the fifth planet from its star, orbiting one quarter of the distance (.25

text: AU

text: ) of the Earth from the Sun every 47 days. It is the furthest of the first five planets in the system. Kepler-11f is the least massive of Kepler-11's six planets, at nearly twice the mass of Earth; it is about 2.6 times the radius of Earth. Along with planets d and e and unlike the two inner planets in the system, Kepler-11f has a density lower than that of water and comparable to that of

text: Saturn

text: . This suggests that Kepler-11f has a significant hydrogen–helium atmosphere. The Kepler-11 planets constitute the first system discovered with more than three transiting planets. Kepler-11f was announced to the public on February 2, 2011 after follow-up investigations at several observatories.  Analysis of the planets and study results were published the next day  in the journal

text: Nature

text: When the rebellion in the Ocean World is growing, Mera escapes to Earth and is reunited with Neri. But PRAXIS sees this pyramid as a danger to the Earth. Much of the final season is thus concerned with PRAXIS' attempt to attack the pyramid, as well as with a "Red Virus" which is spreading in the oceans of Neri's homeworld, the Ocean Planet. Eventually, in the series finale, Jason, Brett, and Neri are able to repulse PRAXIS' efforts and the rebellion, and Earth is saved. Neri remains on Earth as the ambassador of the Ocean Planet, and she and Jason finally become a couple.

text: Still wanting to keep it but not being allowed to grow, Doraemon comes up with the idea of making it come alive with a gadget he uses. Nobita names the little tree "Kibō" because all it can say is "ki". As the days pass, Nobita’s parents also accept Kibō because he was a very smart boy who helped Nobita’s mother whenever he was away. However, aliens from the Planet of Green decides to pass judgement claiming humans were destroying all the green on Earth. Nobita and his friends manage to escape by coincident and arrive at their planet. They are warmly welcomed to their city of Green Pier but also learn of what they are doing to their planet.

text: The concept of Counter-Earth is typically similar to that of parallel universes but is actually a distinct idea. A counter-earth is a planet that shares Earth's orbit but is on the opposite side of the Sun and, therefore, cannot be seen from Earth. There would be no necessity that such a planet would be like Earth in any way though typically in fiction; it is usually nearly identical to Earth. Since Counter-Earth is always within the universe (and the Solar System), travel to it can be accomplished with ordinary space travel.

text: The concept of

text: Counter-Earth

text: is typically similar to that of parallel universes but is actually a distinct idea. A counter-earth is a planet that shares

text: Earth's orbit

text: but is on the opposite side of the Sun and, therefore, cannot be seen from Earth. There would be no necessity that such a planet would be like

text: Earth

text: in any way though typically in fiction; it is usually nearly identical to Earth. Since Counter-Earth is always within the

text: universe

text: (and the

text: Solar System

text: ), travel to it can be accomplished with ordinary space travel.

text: Larger planetesimals, above a transition mass of roughly Ceres mass in the inner solar system and Pluto mass in the outer solar system, accrete pebbles with Stoke's numbers near one from their Hill radii. The Stokes number in this context is the product of stopping time and the keplerian frequency. As with small planetesimals the radius from which pebbles accrete declines for smaller and larger pebble sizes. The optimal pebble size for large planetesimals measures in cm's due to a combination of the accretion radius and the radial drift rates of the pebbles. As objects grow their accretion changes from 3-D, with accretion from part of the thickness of the pebble disk, to 2D with accretion from full thickness of pebble disk. The relative growth rate in 2-D accretion is proportional to mass^(2/3) leading to oligarchical growth and the formation of similar sized bodies. Pebble accretion can result in doubling of mass of an Earth-massed core in as little as 5500 years, reducing the timescales for growth of the cores of giant planets by 2 or 3 orders of magnitude relative to planetesimal accretion. The gravitational influence of these massive bodies can create a partial gap in the gas disk altering the pressure gradient. The velocity of gas then becomes super-keplerian outside the gap stopping the inward drift of pebbles and ending pebble accretion.

text: Larger planetesimals, above a transition mass of roughly

text: Ceres

text: mass in the inner solar system and

text: Pluto

text: mass in the outer solar system, accrete pebbles with Stoke's numbers near one from their Hill radii. The Stokes number in this context is the product of stopping time and the keplerian frequency. As with small planetesimals the radius from which pebbles accrete declines for smaller and larger pebble sizes. The optimal pebble size for large planetesimals measures in cm's due to a combination of the accretion radius and the radial drift rates of the pebbles. As objects grow their accretion changes from 3-D, with accretion from part of the thickness of the pebble disk, to 2D with accretion from full thickness of pebble disk. The relative growth rate in 2-D accretion is proportional to mass^(2/3) leading to oligarchical growth and the formation of similar sized bodies. Pebble accretion can result in doubling of mass of an Earth-massed core in as little as 5500 years, reducing the timescales for growth of the cores of giant planets by 2 or 3 orders of magnitude relative to planetesimal accretion. The gravitational influence of these massive bodies can create a partial gap in the gas disk altering the pressure gradient. The velocity of gas then becomes super-keplerian outside the gap stopping the inward drift of pebbles and ending pebble accretion.

text: Kepler-11b is an exoplanet discovered around the star Kepler-11 by the Kepler spacecraft, a NASA-led mission to discover Earth-like planets. Kepler-11b is less than about three times as massive and twice as large as Earth, but it has a lower density (≤ 3 g/cm), and is thus most likely not of Earth-like composition. Kepler-11b is the hottest of the six planets in the Kepler-11 system, and orbits more closely to Kepler-11 than the other planets in the system. Kepler-11b, along with its five counterparts, form the first discovered planetary system with more than three transiting planets—the most densely packed known planetary system.  The system is also the flattest known planetary system. The discovery of this planet and its five sister planets was announced on February 2, 2011, after follow-up investigations.

text: Kepler-11b is an

text: exoplanet

text: discovered around the star

text: by the

text: Kepler spacecraft

text: , a

text: NASA

text: -led mission to discover

text: Earth-like planets

text: . Kepler-11b is less than about three times as massive and twice as large as Earth, but it has a lower density (≤ 3 g/cm), and is thus most likely not of Earth-like composition. Kepler-11b is the hottest of the six planets in the Kepler-11 system, and orbits more closely to Kepler-11 than the other planets in the system. Kepler-11b, along with its five counterparts, form the first discovered planetary system with more than three transiting planets—the most densely packed known planetary system.  The system is also the flattest known planetary system. The discovery of this planet and its five sister planets was announced on February 2, 2011, after follow-up investigations.

text: To find extra solar planets, CoRoT uses the method of transits detection. The primary transit is the occultation of a fraction of the light from a star when a celestial object, such as a planet, passes between the star and the observer. Its detection is made possible by the sensitivity of CCD to very small changes in light flux. Corot is capable of detecting changes in brightness of about 1/10,000. Scientists can thus hope finding planets with a size of approximately 2 times that of the Earth with this method, a class of planet called Super-Earth; detection of Corot-7b, whose radius is 1.7 times that of the Earth has shown that these predictions were correct. Corot takes an exposure of 32 seconds duration, each 32 seconds, but the image is not fully transmitted to Earth because the data flow would be too large. The onboard computer performs an important work of data reduction: the field around each target star, previously selected by the exoplanets team, is defined on a certain number of pixels described by a particular mask, the sum all pixels within the mask is then performed and several exposures are added (usually 16, which amounts to an integration time of about 8 minutes) before sending this information to the ground. For some stars, considered particularly of interest, data of each exposure is transmitted every 32 seconds. Such a sampling of 32s or 512s is well suited to the detection of a planetary transit that lasts from a little less than an hour to several hours.A feature of this method is that it requires to detect at least three successive transits separated by two equal time intervals before one can consider a target as a serious candidate. A planet of orbital period T should at least be observed for a time interval between 2T and 3T to have a chance to detect three transits. The distance of the planet to the star ( which is characterized by a the semi-major axis of the elliptical orbit ) is linked to its orbital period by the second law of Kepler / Newton a = T M, using respectively as units for a, M and T: the distance from the Earth to the Sun (150 million km), the mass of the Sun, the orbital period of the Earth (1 year); this implies that if the observing time is less a year, for example, the orbits of the detectable planets will be significantly smaller than that of the Earth.So, for Corot, due to the maximum duration of 6 months of observation for each star field, only planets closer to their stars than 0.3 Astronomical Units (less than the distance between the Sun and Mercury) can be detected, therefore generally not in the so-called habitable zone. The Kepler mission (NASA) has continuously observed the same field for many years and thus had the ability to detect Earth sized planets located farther from their stars.

text: The Earth has a magnetic field which is approximately aligned with its axis of rotation. A magnetic compass is a device that uses this field to determine the cardinal directions. Magnetic compasses are widely used, but only moderately accurate.

text: The

text: Earth

text: has a magnetic field which is approximately aligned with its axis of rotation. A

text: magnetic compass

text: is a device that uses this field to determine the cardinal directions. Magnetic compasses are widely used, but only moderately accurate.

text: The astrological order of the days was explained by Vettius Valens and Dio Cassius (and Chaucer gave the same explanation in his Treatise on the Astrolabe). According to these authors, it was a principle of astrology that the heavenly bodies presided, in succession, over the hours of the day. The Ptolemaic system of planetary spheres asserts that the order of the heavenly bodies, from the farthest to the closest to the Earth  is: Saturn, Jupiter, Mars, Sun, Venus, Mercury, Moon (or, objectively, the planets are ordered from slowest to fastest moving as they appear in the night sky).

text: The astrological order of the days was explained by

text: Vettius Valens

text: and

text: Dio Cassius

text: (and

text: Chaucer

text: gave the same explanation in his

text: Treatise on the Astrolabe

text: ). According to these authors, it was a principle of astrology that the heavenly bodies presided, in succession, over the hours of the day. The

text: Ptolemaic system

text: of planetary spheres asserts that the order of the heavenly bodies, from the farthest to the closest to the Earth  is:

text: Saturn

text: Jupiter

text: Mars

text: Sun

text: Venus

text: Mercury

text: Moon

text: (or, objectively, the planets are ordered from slowest to fastest moving as they appear in the night sky).

text: The Justice League of Earth spread their ideals of distrust and hatred against aliens across Earth and were successful to convince the planet's inhabitants into believing them, resulting the planet to fall under the dictatorship of Earth-Man, seceding from the United Planets, and a massive persecution of aliens among Earth's people. The Legion of Super-Heroes were also branded as fugitives for perpetuating the "lies" of Superman's true origins in which the Justice League of Earth was tasked into hunting them down. The Justice League of Earth captured many Legion members and allowing them to have their powers absorbed by Earth-Man, and used the Legionnaire Sun Boy to turn many of the suns in the galaxy red.

text: The Justice League of Earth spread their ideals of distrust and hatred against aliens across Earth and were successful to convince the planet's inhabitants into believing them, resulting the planet to fall under the dictatorship of Earth-Man, seceding from the

text: United Planets

text: , and a massive persecution of aliens among Earth's people. The Legion of Super-Heroes were also branded as fugitives for perpetuating the "lies" of Superman's true origins in which the Justice League of Earth was tasked into hunting them down. The Justice League of Earth captured many Legion members and allowing them to have their powers absorbed by Earth-Man, and used the Legionnaire

text: Sun Boy

text: to turn many of the suns in the galaxy red.

text: A core aspect of the Graphic novel is that the Earth's Magnetic field has cut out, allowing cosmic rays to bombard the planet, and rendering it uninhabitable to humanity. However, an equally important aspect of the graphic novel is Armageddon's ability to come into phase with the Earth's magnetic field and boost his own power output considerably - this is referred to as Pumping Iron and used several times throughout the novel, saving his life at least three times. The discrepancy is never clarified, despite being a potentially large plot hole.

text: The upper atmosphere is in a state of vigorous circulation and super-rotation. The whole atmosphere circles the planet in just four Earth days, much faster than the planet's sidereal day of 243 days. The winds supporting super-rotation blow as fast as 100 m/s (~360 km/h or 220 mph). Winds move at up to 60 times the speed of the planet's rotation, while Earth's fastest winds are only 10% to 20% rotation speed. On the other hand, the wind speed becomes increasingly slower as the elevation from the surface decreases, with the breeze barely reaching the speed of 10 km/h (2.8 m/s) on the surface. Near the poles are anticyclonic structures called polar vortices. Each vortex is double-eyed and shows a characteristic S-shaped pattern of clouds.

text: The upper atmosphere is in a state of vigorous circulation and super-rotation. The whole atmosphere circles the planet in just four Earth days, much faster than the planet's

text: sidereal day

text: of 243 days. The winds supporting super-rotation blow as fast as 100 m/s (~360 km/h or 220 mph). Winds move at up to 60 times the speed of the planet's rotation, while Earth's fastest winds are only 10% to 20% rotation speed. On the other hand, the wind speed becomes increasingly slower as the elevation from the surface decreases, with the breeze barely reaching the speed of 10 km/h (2.8 m/s) on the surface. Near the poles are

text: anticyclonic

text: structures called polar

text: vortices

text: . Each vortex is double-eyed and shows a characteristic S-shaped pattern of clouds.

text: Known or suspected collisional families include numerous asteroid families, most of the irregular moons of the outer planets, the Earth and the Moon, and the dwarf planets Pluto, Eris, and Haumea and their moons.

text: Known or suspected collisional families include numerous

text: asteroid families

text: , most of the

text: irregular moon

text: s of the outer planets, the Earth and the

text: Moon

text: , and the dwarf planets

text: Pluto

text: Eris

text: , and

text: Haumea

text: and their moons.

text: Humanity is spreading rapidly through the galaxy and a planet known as Glade has been identified as suitable for colonization as it has a near-Earth climate (and presumably near-Earth gravity and atmosphere). A colonisation expedition lands on Glade; one rocket contains the potential colonists and their equipment, whilst a second rocket returns to Earth to confirm the suitability of the planet and bring more settlers.

text: Mandi’s rising is got by firstly finding out the duration of day and night; if the duration is equal i.e. of thirty ghatis each (one ghati=24 minutes), Mandi would rise at the end of ghatis 26 on " Sunday ", at the end of ghatis 22 on " Monday ", at the end of ghatis 18 on " Tuesday ", at the end of ghatis 14 on " Wednesday ", at the end of ghatis 10 on " Thursday ", at the end of 6 ghatis on " Friday ", and at the end of 2 ghatis on " Saturday ". In the case of "night-births" the 5th of that particular "weekday" will have to be considered, and if the day and night durations vary then the rising of Mandi will have to be altered proportionately. The rising times of Kala during day-time on weekdays are in order at the end of ghatis 2, 26, 22, 18, 14, 10 and 6; those of Yamakantaka are at the end of ghatis 18, 14, 10, 6, 2, 26 and 22, and those of Ardhaprahar are at the end of ghatis 14, 10, 6, 2, 26, 22, 18. Dhooma is got by adding 4 signs 13 degrees and 20 minutes to the Sun’s latitude; Vyatipata is got by subtracting the figures for Dhooma from 12 signs; Paridhi is obtained by adding six signs to the figures for Vyatipata; Indradhanu or Kodanda is got by subtracting Paridhi from 12 signs; and Upaketu is got by adding 16 degrees 40 minutes to Indradhanu.The simpler method for determining Mandi’s rising sign is - For day born, the duration of the day (Dinamāna) divided by 8 gives eight parts each part governed by a planet; the first part is ruled by the day-lord. For night born, the first part is ruled by the 5th planet in the given order; the sign rising in the east in the part ruled by Saturn is Mandi’s rising sign.

text: Mandi’s rising is got by firstly finding out the duration of day and night; if the duration is equal i.e. of thirty ghatis each (one ghati=24 minutes), Mandi would rise at the end of ghatis 26 on "

text: Sunday

text: ", at the end of ghatis 22 on "

text: Monday

text: ", at the end of ghatis 18 on "

text: Tuesday

text: ", at the end of ghatis 14 on "

text: Wednesday

text: ", at the end of ghatis 10 on "

text: Thursday

text: ", at the end of 6 ghatis on "

text: Friday

text: ", and at the end of 2 ghatis on "

text: Saturday

text: ". In the case of "night-births" the 5th of that particular "weekday" will have to be considered, and if the day and night durations vary then the rising of Mandi will have to be altered proportionately. The rising times of Kala during day-time on weekdays are in order at the end of ghatis 2, 26, 22, 18, 14, 10 and 6; those of Yamakantaka are at the end of ghatis 18, 14, 10, 6, 2, 26 and 22, and those of Ardhaprahar are at the end of ghatis 14, 10, 6, 2, 26, 22, 18. Dhooma is got by adding 4 signs 13 degrees and 20 minutes to the Sun’s latitude; Vyatipata is got by subtracting the figures for Dhooma from 12 signs; Paridhi is obtained by adding six signs to the figures for Vyatipata; Indradhanu or Kodanda is got by subtracting Paridhi from 12 signs; and Upaketu is got by adding 16 degrees 40 minutes to Indradhanu.The simpler method for determining Mandi’s rising sign is - For day born, the duration of the day (Dinamāna) divided by 8 gives eight parts each part governed by a planet; the first part is ruled by the day-lord. For night born, the first part is ruled by the 5th planet in the given order; the sign rising in the east in the part ruled by Saturn is Mandi’s rising sign.

text: Magnetospheres are formed by the solar wind plasma flow around planets with an intrinsic magnetic field (Mercury, Earth, Jupiter, Saturn, Uranus, and Neptune), although planets and moons lacking magnetic fields may sometimes form magnetosphere-like plasma structures. The ionospheres of weakly magnetized planets such as Venus and Mars set up currents that partially deflect the solar wind flow around the planet.

text: Magnetospheres are formed by the solar wind plasma flow around planets with an intrinsic

text: magnetic field

text: Mercury

text: Earth

text: Jupiter

text: Saturn

text: Uranus

text: , and

text: Neptune

text: ), although planets and moons lacking magnetic fields may sometimes form magnetosphere-like plasma structures. The ionospheres of weakly magnetized planets such as

text: Venus

text: and

text: Mars

text: set up currents that partially deflect the solar wind flow around the planet.

text: Many authors define "satellite" or "natural satellite" as orbiting some planet or minor planet, synonymous with "moon"—by such a definition all natural satellites are moons, but Earth and other planets are not satellites.A few recent authors define "moon" as "a satellite of a planet or minor planet", and "planet" as "a satellite of a star"—such authors consider Earth as a "natural satellite of the sun".

text: The basic premise of the film, that the movement of the Earth's magnetic north and south poles to the middle latitude would cause a massive climatic shift, is only partially true. Although such an event (if it were possible) would result in dramatic effects on global weather patterns, it would not reverse the Earth's climate zones as shown in the film, since climate is governed not just by the Earth's magnetic field, but mainly by altitude and proximity to the poles via the tilt of the Earth's axis, which affords lower latitudes more direct sun rays.  Furthermore, the movement of the poles, not the magnetic poles, would move both arctic and temperate regions, but would not necessarily trigger an ice age.  It would not cause an ice age localized to Miami, as the film suggests.

text: The basic premise of the film, that the movement of the Earth's magnetic north and south poles to the middle latitude would cause a massive climatic shift, is only partially true. Although such an event (if it were possible) would result in dramatic effects on global weather patterns, it would not reverse the Earth's climate zones as shown in the film, since climate is governed not just by the Earth's magnetic field, but mainly by altitude and

text: proximity to the poles via the tilt of the Earth's axis

text: , which affords lower latitudes more direct sun rays.  Furthermore, the movement of the poles, not the magnetic poles, would move both arctic and temperate regions, but would not necessarily trigger an ice age.  It would not cause an ice age localized to Miami, as the film suggests.

text: This led into the Sun-Eater's first post-Zero Hour appearance, in the Final Night miniseries (1997) (set in the present day, rather than the Legion's future). A rogue Sun-Eater destroyed several planets, eventually reaching the Solar System and snuffing out the Sun. The heroes of Earth were powerless to stop it, until Parallax sacrificed his powers and life to destroy it and reignite the Sun.

text: This led into the Sun-Eater's first post-Zero Hour appearance, in the

text: Final Night

text: miniseries (1997) (set in the present day, rather than the Legion's future). A rogue Sun-Eater destroyed several planets, eventually reaching the

text: Solar System

text: and snuffing out the Sun. The heroes of Earth were powerless to stop it, until

text: Parallax

text: sacrificed his powers and life to destroy it and reignite the Sun.

text: In a frame rotating with the Earth the train is moving in a circular orbit as it travels round the Earth. In this frame, the upward reaction force from the track and the force of gravity on the train remain the same, as they are real forces. However, in the Earth's (rotating) frame, the train is traveling in a circular path and therefore requires a centripetal (downward) force to keep it on this path. Because we are using a rotating frame, we must, as always, apply the (fictitious) centrifugal force to the train. This is equal in value to the required centripetal force but acts in an upward direction — the opposite direction to that required. It would therefore seem that there is a net upward force on the train and it should therefore accelerate upward.

text: Ancient Greek, ancient Roman and medieval philosophers usually combined the Geocentric model with a spherical Earth. It is not the same as the older flat Earth model implied in some mythology. The ancient Jewish Babylonian uranography pictured a flat Earth with a dome-shaped rigid canopy named firmament placed over it. (רקיע- rāqîa'). However, the ancient Greeks believed that the motions of the planets were circular and not elliptical, a view that was not challenged in Western culture until the 17th century through the synthesis of theories by Copernicus and Kepler.

text: Ancient Greek, ancient Roman and medieval philosophers usually combined the Geocentric model with a

text: spherical Earth

text: . It is not the same as the older

text: flat Earth

text: model implied in some

text: mythology

text: . The ancient Jewish Babylonian

text: uranography

text: pictured a flat Earth with a dome-shaped rigid canopy named firmament placed over it. (רקיע- rāqîa'). However, the ancient Greeks believed that the motions of the planets were circular and not elliptical, a view that was not challenged in

text: Western culture

text: until the 17th century through the synthesis of theories by

text: Copernicus

text: and

text: Kepler

text: As they ate and ate, their luminous body began to be coated by the mud substance, formed a coarser body, then suddenly, the sun and moon were seen, so were the stars, and also Night and Day began on Earth. The logical explanation of this was that the creatures were the self-illuminating, so blinding and luminous that they didn't notice the Sun. The Earth was covered in their light. So, when the materialization took place, the light faded inside their newly conceived 'body' of mud and thus the night and day became apparent to them. Then, as the night and day became apparent, seasons and years also appeared.

text: As they ate and ate, their

text: luminous

text: body began to be coated by the mud substance, formed a coarser body, then suddenly, the sun and moon were seen, so were the stars, and also Night and Day began on Earth. The logical explanation of this was that the creatures were the self-illuminating, so blinding and luminous that they didn't notice the Sun. The Earth was covered in their light. So, when the materialization took place, the light faded inside their newly conceived 'body' of mud and thus the night and day became apparent to them. Then, as the night and day became apparent, seasons and years also appeared.

text: The direct-to-video feature Justice League: Crisis on Two Earths deals with the Multiverse as part of its story. The main story deals with a good Lex Luthor from his Earth (based on the pre-Crisis Earth-Three) coming to the Earth where the Justice League are located to help fight their counterparts, the Crime Syndicate. While the two Earths inhabited by the Justice League and Crime Syndicate are not named, names of other Earths are mentioned. These names are not from the official pre-Crisis nor post-Infinite Crisis Multiverse, but are nods to a degree. Examples include: "Gamma F-1", "Theta-Alpha", "Zeta-Pi", which are all Greek numbers. Earth-Prime is featured in the film, but is not the same Earth-Prime from the comics where it was "our" Earth. In the film, Earth-Prime is shown to be the cornerstone of all reality, and that decisions made by humankind on this world caused alternate Earths where the opposite decision was made to come into being. This world is shown to be a desolate barren wasteland of a planet, with ruins as far as the eye can see. It is unknown what exactly caused its desolation, though Owlman reasons that it was mankind who destroyed itself.

text: The direct-to-video feature Justice League: Crisis on Two Earths deals with the Multiverse as part of its story. The main story deals with a good Lex Luthor from his Earth (based on the pre-Crisis

text: Earth-Three

text: ) coming to the Earth where the Justice League are located to help fight their counterparts, the

text: Crime Syndicate

text: . While the two Earths inhabited by the Justice League and Crime Syndicate are not named, names of other Earths are mentioned. These names are not from the official pre-Crisis nor post-Infinite Crisis Multiverse, but are nods to a degree. Examples include: "Gamma F-1", "Theta-Alpha", "Zeta-Pi", which are all Greek numbers.

text: Earth-Prime

text: is featured in the film, but is not the same Earth-Prime from the comics where it was "our" Earth. In the film, Earth-Prime is shown to be the cornerstone of all reality, and that decisions made by humankind on this world caused alternate Earths where the opposite decision was made to come into being. This world is shown to be a desolate barren wasteland of a planet, with ruins as far as the eye can see. It is unknown what exactly caused its desolation, though Owlman reasons that it was

text: mankind who destroyed itself

text: Earth’s magnetism was a continuous concern of Ștefan Procopiu, For 25 years he studied this phenomenon in Romania and developed the magnetic maps of the country. He also identified the magnetic anomaly located on the Iași-Botoșani line.

text: Earth’s magnetism was a continuous concern of Ștefan Procopiu, For 25 years he studied this

text: phenomenon

text: in Romania and developed the magnetic maps of the country. He also identified the

text: magnetic anomaly

text: located on the

text: Iași

text: Botoșani

text: line.

text: In reality, Earth is not exactly spherical, mainly because of its rotation around the polar axis that makes its shape slightly oblate. If this shape would have been perfectly known together with the exact mass density ρ = ρ(x, y, z) the integrals () and () could have been evaluated with numerical methods to find a more accurate model for Earth's gravitational field, but the situation is in fact the opposite. By observing the orbits of spacecraft and the Moon, Earth's gravitational field can be determined quite accurately and the best estimate of Earth's mass is obtained by dividing the product GM as determined from the analysis of spacecraft orbit with a value for G determined to a lower relative accuracy using other physical methods.

text: HD 38283 b is an extrasolar planet, orbiting the 7th magnitude F-type main-sequence star HD 38283, 123 light years away in the constellation Mensa. It is a Saturn-like planet orbiting at Earth-like distance in the middle of its habitable zone. But its eccentricity is 0.41, much higher than the Earth's eccentricity of 0.017. The planet's distance ranges from about 0.60 AU (closer to its star than Venus is to the Sun) and 1.44 AU (nearly as distant from its star as Mars is to the Sun). This planet takes 363.2 days to orbit the star, just two days shy of the Earth's orbital period of 365.256366 days. Its mass is one-thirds that of Jupiter but its size and density are not known. Since inclination is not known, its actual mass is unknown, either slightly greater or much greater than its lower limit.

text: HD 38283 b is an

text: extrasolar planet

text: , orbiting the 7th

text: magnitude

text: F-type main-sequence star

text: HD 38283

text: , 123 light years away in the constellation

text: Mensa

text: . It is a

text: Saturn

text: -like planet orbiting at Earth-like distance in the middle of its

text: habitable zone

text: . But its eccentricity is 0.41, much higher than the Earth's eccentricity of 0.017. The planet's distance ranges from about 0.60 AU (closer to its star than

text: Venus

text: is to the Sun) and 1.44 AU (nearly as distant from its star as

text: Mars

text: is to the Sun). This planet takes 363.2 days to orbit the star, just two days shy of the Earth's orbital period of 365.256366 days. Its mass is one-thirds that of

text: Jupiter

text: but its size and density are not known. Since inclination is not known, its actual mass is unknown, either slightly greater or much greater than its lower limit.

text: The tidal acceleration of the Moon slows the rotation rate of the Earth and increases the Earth-Moon distance. Friction effects—between the core and mantle and between the atmosphere and surface—can dissipate the Earth's rotational energy. These combined effects are expected to increase the length of the day by more than 1.5 hours over the next 250 million years, and to increase the obliquity by about a half degree. The distance to the Moon will increase by about 1.5 Earth radii during the same period.

text: The

text: tidal acceleration

text: of the Moon slows the rotation rate of the Earth and increases the

text: Earth-Moon distance

text: . Friction effects—between the core and

text: mantle

text: and between the atmosphere and surface—can dissipate the Earth's rotational energy. These combined effects are expected to increase the

text: length of the day

text: by more than 1.5 hours over the next 250 million years, and to increase the

text: obliquity

text: by about a half degree. The distance to the Moon will increase by about 1.5 Earth radii during the same period.

text: The "Night Version" of "Planet Earth" appeared in place of the original on some early US releases of the Duran Duran album.

text: The "Night Version" of "Planet Earth" appeared in place of the original on some early US releases of the

text: Duran Duran

text: album.

text: The planet is estimated to be about five times Earth's mass (5.5 ). Some astronomers have speculated that it may have a rocky core like Earth, with a thin atmosphere. Its distance from the star, and the star's relatively low temperature, means that the planet's likely surface temperature is around , making it one of the coldest known. If it is a rocky world, this temperature would make it likely that the surface would be made of frozen volatiles, substances which would be liquids or gases on Earth: water, ammonia, methane and nitrogen would all be frozen solid. If it is not a rocky planet, it would more closely resemble an icy gas planet like Uranus, although much smaller.

text: The planet is estimated to be about five times Earth's mass (5.5 ). Some astronomers have speculated that it may have a rocky

text: core

text: like Earth, with a thin

text: atmosphere

text: . Its distance from the star, and the star's relatively low temperature, means that the planet's likely surface temperature is around , making it one of the coldest known. If it is a rocky world, this temperature would make it likely that the surface would be made of frozen

text: volatiles

text: , substances which would be liquids or gases on Earth: water,

text: ammonia

text: methane

text: and

text: nitrogen

text: would all be frozen solid. If it is not a rocky planet, it would more closely resemble an icy gas planet like

text: Uranus

text: , although much smaller.

text: The first person to discover that gravity varied over the Earth's surface was French scientist Jean Richer, who in 1671 was sent on an expedition to Cayenne, French Guiana, by the French Académie des Sciences, assigned the task of making measurements with a pendulum clock. Through the observations he made in the following year, Richer determined that the clock was 2½ minutes per day slower than at Paris, or equivalently the length of a pendulum with a swing of one second there was 1¼ Paris lines, or 2.6 mm, shorter than at Paris. It was realized by the scientists of the day, and proven by Isaac Newton in 1687, that this was due to the fact that the Earth was not a perfect sphere but slightly oblate; it was thicker at the equator because of the Earth's rotation. Since the surface was farther from the Earth's center at Cayenne than at Paris, gravity was weaker there. Since that time pendulums began to be used as precision gravimeters, taken on voyages to different parts of the world to measure the local gravitational acceleration. The accumulation of geographical gravity data resulted in more and more accurate models of the overall shape of the Earth.

text: The first person to discover that gravity varied over the Earth's surface was French scientist

text: Jean Richer

text: , who in 1671 was sent on an expedition to

text: Cayenne

text: French Guiana

text: , by the French

text: Académie des Sciences

text: , assigned the task of making measurements with a

text: pendulum clock

text: . Through the observations he made in the following year, Richer determined that the clock was 2½ minutes per day slower than at Paris, or equivalently the length of a pendulum with a swing of one second there was 1¼ Paris lines, or 2.6 mm, shorter than at Paris. It was realized by the scientists of the day, and proven by

text: Isaac Newton

text: in 1687, that this was due to the fact that the Earth was not a perfect sphere but slightly

text: oblate

text: ; it was thicker at the equator because of the Earth's rotation. Since the surface was farther from the Earth's center at Cayenne than at Paris, gravity was weaker there. Since that time pendulums began to be used as precision

text: gravimeter

text: s, taken on voyages to different parts of the world to measure the local gravitational acceleration. The accumulation of geographical gravity data resulted in more and more accurate models of the overall shape of the Earth.

text: Two terrestrial planets (Earth and Mercury) display magnetospheres, and thus have molten metal layers. Similarly, all four gas giants have magnetospheres, which indicate layers of conductive fluids. Ganymede also shows a weak magnetosphere, taken as evidence of a subsurface layer of salt water, while the volume around Rhea shows symmetrical effects which may be rings or a magnetic phenomenon. Of these, Earth's magnetosphere is by far the most accessible, including from the surface. It is therefore the most studied, and extraterrestrial magnetospheres are examined in light of prior Earth studies.

text: Two terrestrial planets (Earth and Mercury) display magnetospheres, and thus have molten metal layers. Similarly, all four gas giants have magnetospheres, which indicate layers of conductive fluids.

text: Ganymede

text: also shows a weak magnetosphere, taken as evidence of a subsurface layer of salt water, while the volume around

text: Rhea

text: shows symmetrical effects which may be rings or a magnetic phenomenon. Of these, Earth's magnetosphere is by far the most accessible, including from the surface. It is therefore the most studied, and extraterrestrial magnetospheres are examined in light of prior Earth studies.

text: The novel follows the ill-fated military campaign by a repressive state, the New Republic, to retaliate for a perceived invasion of one of its colony worlds. In actuality, the planet has been visited by the Festival, a technologically advanced alien or posthuman race that rewards its hosts for "entertaining" them by granting whatever the entertainer wishes, including the Festival's own technology. This causes extensive social, economic and political disruption to the colony, which was generally limited by the New Republic to technology equivalent to that found on Earth during the Industrial Revolution. Aboard the New Republic's flagship, an engineer and intelligence operative from Earth covertly attempt to prevent the use of a forbidden technology—and fall in love along the way.

text: The novel follows the ill-fated military campaign by a repressive state, the New Republic, to retaliate for a perceived invasion of one of its colony worlds. In actuality, the planet has been visited by the Festival, a technologically advanced alien or posthuman race that rewards its hosts for "entertaining" them by granting whatever the entertainer wishes, including the Festival's own technology. This causes extensive social, economic and political disruption to the colony, which was generally limited by the New Republic to technology equivalent to that found on Earth during the

text: Industrial Revolution

text: . Aboard the New Republic's flagship, an engineer and intelligence operative from Earth covertly attempt to prevent the use of a forbidden technology—and fall in love along the way.

text: Cosmism was one of the influences on Proletkult, and after the October Revolution, the term came to be applied to "the poetry of such writers as Mikhail Gerasimov and Vladimir Kirillov...: emotional paeans to physical labor, machines, and the collective of industrial workers ... organized around the image of the universal 'Proletarian,' who strides forth from the earth to conquer planets and stars." This form of cosmism, along with the writings of Nikolai Fyodorov, was a strong influence on Andrei Platonov.

text: Cosmism was one of the influences on

text: Proletkult

text: , and after the

text: October Revolution

text: , the term came to be applied to "the poetry of such writers as

text: Mikhail Gerasimov

text: and

text: Vladimir Kirillov

text: ...: emotional paeans to physical labor, machines, and the collective of industrial workers ... organized around the image of the universal 'Proletarian,' who strides forth from the earth to conquer planets and stars." This form of cosmism, along with the writings of

text: Nikolai Fyodorov

text: , was a strong influence on

text: Andrei Platonov

text: The novel does not seem to take into account that due to the ellipticity of the orbit the planet would be in a near-equinoxe position during most of the orbiting period, which would mean that both poles would enjoy a mild twilight. If the orbit were less elliptic there would be no arctic twilight zone at all but polar nights and days of varying length, like on Earth. So it is hard to imagine the astronomic circumstances needed for Harrison's interesting plot.

text: The geology of solar terrestrial planets mainly deals with the geological aspects of the four terrestrial planets of the Solar System, Mercury, Venus, Earth, and Mars, and one terrestrial dwarf planet, Ceres. Only one terrestrial planet, Earth, is known to have an active hydrosphere.

text: The geology of solar terrestrial planets mainly deals with the geological aspects of the four terrestrial planets of the

text: Solar System

text: Mercury

text: Venus

text: Earth

text: , and

text: Mars

text: , and one terrestrial

text: dwarf planet

text: Ceres

text: hydrosphere

text: After Coulson was promoted to Director of S.H.I.E.L.D., Gregg said "He kind of got his dream job that I don’t even think he would have ever dreamed he would be given ... he’s got a little bit more of an idealistic, big hearted side of him [than Nick Fury does], some of which is going to be extinguished by the hard decisions he has to make." Speaking about the evolving nature of Coulson's relationship with his team, Gregg said "There’s a way he can afford an intimacy with all of them when they’re part of a small, elite squad on the Bus. It’s different than what’s possible for him as Director of S.H.I.E.L.D." Discussing Coulson's character progression through three seasons in relation to him killing Ward on the alien planet, executive producer Jeffrey Bell said, "First season Coulson would have beat Ward up and then thrown him over his shoulder and brought him back to Earth and locked him away. Season two Coulson would have defeated him and left him there on the other planet to fend for himself," while season three Coulson paused while the portal to Earth was already closing to take the time to kill Ward.

text: After Coulson was promoted to Director of S.H.I.E.L.D., Gregg said "He kind of got his dream job that I don’t even think he would have ever dreamed he would be given ... he’s got a little bit more of an idealistic, big hearted side of him [than Nick Fury does], some of which is going to be extinguished by the hard decisions he has to make." Speaking about the evolving nature of Coulson's relationship with his team, Gregg said "There’s a way he can afford an intimacy with all of them when they’re part of a small, elite squad on the Bus. It’s different than what’s possible for him as Director of S.H.I.E.L.D." Discussing Coulson's character progression through three seasons in relation to him killing Ward on the alien planet, executive producer

text: Jeffrey Bell

text: said, "First season Coulson would have beat Ward up and then thrown him over his shoulder and brought him back to Earth and locked him away. Season two Coulson would have defeated him and left him there on the other planet to fend for himself," while season three Coulson paused while the portal to Earth was already closing to take the time to kill Ward.

text: Nebulos is a somewhat Earth-like planet far away from both Earth and Cybertron, and is the home to a humanoid race known as the Nebulans. The planet and its inhabitants were first introduced as the back story for Hasbro's new Headmaster and Targetmaster toys, later expanded by the Powermaster toys. These toys are robots that transform into vehicles or animals, and include Nebulan sidekicks that transform into the robot's head, into a weapon, or into the vehicle's engine. The toys themselves never expanded on Nebulon or its inhabitants, but both the TV series (in its fourth and final season) and the Marvel Comics comic book did, with drastically different, mutually inconsistent versions. In the TV series, the Nebulons were shown to be green-skinned. The planet Nebulos does not exist in the Japanese continuation of the franchise. Thus, with no Nebulos and no Nebulons, a different origin was given for the Headmaster and Targetmaster Transformers.

text: Nebulos is a somewhat

text: Earth

text: -like planet far away from both Earth and

text: Cybertron

text: , and is the home to a

text: human

text: oid race known as the Nebulans. The planet and its inhabitants were first introduced as the back story for

text: Hasbro

text: 's new

text: Headmaster

text: and

text: Targetmaster

text: toys, later expanded by the

text: Powermaster

text: toys. These toys are

text: robot

text: s that transform into

text: vehicle

text: s or

text: animal

text: s, and include Nebulan sidekicks that transform into the robot's head, into a

text: weapon

text: , or into the vehicle's

text: engine

text: . The toys themselves never expanded on Nebulon or its inhabitants, but both the TV series (in its fourth and final season) and the

text: Marvel Comics

text: comic book

text: did, with drastically different, mutually inconsistent versions. In the TV series, the Nebulons were shown to be green-skinned. The planet Nebulos does not exist in the Japanese continuation of the franchise. Thus, with no Nebulos and no Nebulons, a different origin was given for the Headmaster and Targetmaster Transformers.

text: Because the Moon's mass is a considerable fraction of that of Earth (about 1:81), the two bodies can be regarded as a double planet system, rather than as a planet with a satellite.  The plane of the Moon's orbit around Earth lies close to the plane of Earth's orbit around the Sun (the ecliptic), rather than in the plane perpendicular to the axis of rotation of Earth (the equator) as is usually the case with planetary satellites.  The mass of the Moon is sufficiently large, and it is sufficiently close, to raise tides in the matter of Earth. In particular, the water of the oceans bulges out towards and away from the Moon. The average tidal bulge is synchronized with the Moon's orbit, and Earth rotates under this tidal bulge in just over a day. However, Earth's rotation drags the position of the tidal bulge ahead of the position directly under the Moon. As a consequence, there exists a substantial amount of mass in the bulge that is offset from the line through the centers of Earth and the Moon. Because of this offset, a portion of the gravitational pull between Earth's tidal bulges and the Moon is not perpendicular to the Earth–Moon line, i.e. there exists a torque between Earth and the Moon. This boosts the Moon in its orbit, and slows the rotation of Earth.

text: Because the

text: Moon

text: 's mass is a considerable fraction of that of Earth (about 1:81), the two bodies can be regarded as a

text: double planet

text: system, rather than as a planet with a satellite.  The plane of the Moon's

text: orbit

text: around Earth lies close to the plane of Earth's orbit around the Sun (the

text: ecliptic

text: ), rather than in the plane perpendicular to the axis of rotation of Earth (the

text: equator

text: ) as is usually the case with planetary satellites.  The mass of the Moon is sufficiently large, and it is sufficiently close, to raise

text: tide

text: s in the matter of Earth. In particular, the

text: water

text: of the

text: ocean

text: s bulges out towards and away from the Moon. The average tidal bulge is synchronized with the Moon's orbit, and Earth rotates under this tidal bulge in just over a

text: day

text: . However, Earth's rotation drags the position of the tidal bulge ahead of the position directly under the Moon. As a consequence, there exists a substantial amount of mass in the bulge that is offset from the line through the centers of Earth and the Moon. Because of this offset, a portion of the gravitational pull between Earth's tidal bulges and the Moon is not perpendicular to the Earth–Moon line, i.e. there exists a

text: torque

text: between Earth and the Moon. This boosts the Moon in its orbit, and slows the rotation of Earth.

text: The models for the figure of the Earth vary in the way they are used, in their complexity, and in the accuracy with which they represent the size and shape of the Earth.

text: The shape of the Earth is to a large extent the result of its rotation, which causes its equatorial bulge, and the competition of geological processes such as the collision of plates and of volcanism, resisted by the Earth's gravity field. This applies to the solid surface, the liquid surface (dynamic sea surface topography) and the Earth's atmosphere. For this reason, the study of the Earth's gravity field is called physical geodesy by some.

text: The shape of the Earth is to a large extent the result of its rotation, which causes its equatorial bulge, and the competition of geological processes such as the collision of plates and of

text: volcanism

text: , resisted by the Earth's

text: gravity

text: field. This applies to the solid surface, the liquid surface (

text: dynamic sea surface topography

text: ) and the

text: Earth's atmosphere

text: . For this reason, the study of the Earth's

text: gravity field

text: is called

text: physical geodesy

text: by some.

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: Kepler-20e is an exoplanet orbiting Kepler-20. The planet is notable as it is the first planet with a smaller radius than Earth found orbiting a Sun-like star. The planet is second-closest to the star after Kepler-20b, and at , it is far too hot to have liquid water on its surface. Along with the other four planets in the system, Kepler-20e was announced on 20 December 2011.<blockquote>"Kepler-20e is the first planet smaller than the Earth discovered to orbit a star other than the sun. A year on Kepler-20e only lasts 6 days, as it is much closer to its host star than the Earth is to the sun. The temperature at the surface of the planet, around 1400 degrees Fahrenheit, is much to hot to support life, as we know it.<br>Kepler-20e is likely to be entirely rocky and without an atmosphere. The planet is tidally locked, always showing the same side to its host star, as the moon to the Earth, and could have large temperature differences between its permanent night and day sides.

text: Kepler-20e is an

text: exoplanet

text: orbiting

text: . The planet is notable as it is the first planet with a smaller radius than

text: Earth

text: found orbiting a

text: Sun-like star

text: . The planet is second-closest to the star after

text: , and at , it is far too hot to have liquid water on its surface. Along with the other four planets in the system, Kepler-20e was announced on 20 December 2011.<blockquote>"Kepler-20e is the first planet smaller than the Earth discovered to orbit a star other than the sun. A year on Kepler-20e only lasts 6 days, as it is much closer to its host star than the Earth is to the sun. The temperature at the surface of the planet, around 1400 degrees Fahrenheit, is much to hot to support life, as we know it.<br>Kepler-20e is likely to be entirely rocky and without an atmosphere. The planet is tidally locked, always showing the same side to its host star, as the moon to the Earth, and could have large temperature differences between its permanent night and day sides.

text: In the Season Three finale of the re-imagined series, Kara Thrace returns to Galactica after her apparent death, claiming to have been to Earth and intending to lead the fleet there. The camera then pans out from the fleet to view the Milky Way galaxy, and then zooms back in to show Earth, confirming the existence of the planet. In the Season Four mid-season finale episode "Revelations", the fleet finally reaches Earth, only to discover that it is a lifeless, radioactive wasteland.

text: In the Season Three finale of the re-imagined series,

text: Kara Thrace

text: returns to Galactica after her apparent death, claiming to have been to Earth and intending to lead the fleet there. The camera then pans out from the fleet to view the

text: Milky Way

text: galaxy, and then zooms back in to show Earth, confirming the existence of the planet. In the Season Four mid-season finale episode "Revelations", the fleet finally reaches Earth, only to discover that it is a lifeless, radioactive wasteland.

text: Bow shocks form the boundary between a magnetosphere and an ambient magnetized medium. This occurs when the magnetic field of an astrophysical object interacts with the nearby flowing ambient plasma. For example, when the solar wind, flowing with a relative speed of order 400 km/s, encounters the magnetic field of Earth, a bow shape boundary forms. For Earth and other magnetized planets, it is the boundary at which the speed of the stellar wind abruptly drops as a result of its approach to the magnetopause. For stars, this boundary is typically the edge of the astrosphere, where the stellar wind meets the interstellar medium.

text: Bow shocks

text: form the boundary between a

text: magnetosphere

text: and an ambient magnetized medium. This occurs when the magnetic field of an astrophysical object interacts with the nearby flowing ambient

text: plasma

text: . For example, when the

text: solar wind

text: , flowing with a relative speed of order 400 km/s, encounters the magnetic field of Earth, a bow shape boundary forms. For Earth and other magnetized planets, it is the boundary at which the speed of the stellar wind abruptly drops as a result of its approach to the

text: magnetopause

text: . For stars, this boundary is typically the edge of the

text: astrosphere

text: , where the

text: stellar wind

text: meets the

text: interstellar medium

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: The series takes place in the year 2517, on a variety of planets and moons. The TV series does not reveal whether these celestial bodies are within one star system, only saying that Serenitys mode of propulsion is a "gravity-drive". The film Serenity makes clear that all the planets and moons are in one large system, and production documents related to the film indicate that there is no faster-than-light travel in this universe. The characters occasionally refer to "Earth-that-was", and the film establishes that, long before the events in the series, a large population had emigrated from Earth to a new star system in generation ships: "Earth-that-was could no longer sustain our numbers, we were so many". The emigrants established themselves in this new star system, with "dozens of planets and hundreds of moons". Many of these were terraformed, a process in which a planet or moon is altered to resemble Earth. The terraforming process was only the first step in making a planet habitable, however, and the outlying settlements often did not receive any further support in the construction of their civilizations. This resulted in many of the border planets and moons having forbidding, dry environments, well-suited to the Western genre.

text: The series takes place in the year 2517, on a variety of

text: planets and moons

text: . The TV series does not reveal whether these celestial bodies are within one star system, only saying that Serenitys mode of propulsion is a "gravity-drive". The film

text: Serenity

text: makes clear that all the planets and moons are in one large system, and production documents related to the film indicate that there is no

text: faster-than-light

text: travel in this

text: universe

text: . The characters occasionally refer to "Earth-that-was", and the film establishes that, long before the events in the series, a large population had emigrated from

text: Earth

text: to a new

text: star system

text: in

text: generation ship

text: s: "Earth-that-was could no longer sustain our numbers, we were so many". The emigrants established themselves in this new star system, with "dozens of planets and hundreds of moons". Many of these were

text: terraformed

text: , a process in which a planet or moon is altered to resemble Earth. The terraforming process was only the first step in making a planet habitable, however, and the outlying settlements often did not receive any further support in the construction of their civilizations. This resulted in many of the border planets and moons having forbidding, dry environments, well-suited to the Western genre.

text: If a planet's magnetic field is strong enough, its interaction with the solar wind forms a magnetosphere. Early space probes mapped out the gross dimensions of the Earth's magnetic field, which extends about 10 Earth radii towards the Sun. The solar wind, a stream of charged particles, streams out and around the terrestrial magnetic field, and continues behind the magnetic tail, hundreds of Earth radii downstream. Inside the magnetosphere, there are relatively dense regions of solar wind particles called the Van Allen radiation belts.

text: If a planet's

text: magnetic field

text: is strong enough, its interaction with the solar wind forms a

text: magnetosphere

text: . Early

text: space probe

text: s mapped out the gross dimensions of the

text: Earth's magnetic field

text: , which extends about 10

text: Earth radii

text: towards the Sun. The solar wind, a stream of charged particles, streams out and around the terrestrial magnetic field, and continues behind the

text: magnetic tail

text: , hundreds of Earth radii downstream. Inside the magnetosphere, there are relatively dense regions of solar wind particles called the

text: Van Allen radiation belt

text: s.

text: Planet Earth was the second attempt by Roddenberry to create a weekly series set on a post-apocalyptic future Earth. The previous pilot was Genesis II, and it featured many of the concepts and characters later redeveloped in Planet Earth. Sets and props from Genesis II also found their way into Planet Earth.

text: Planet Earth was the second attempt by Roddenberry to create a weekly series set on a

entity_name: Apocalyptic and post-apocalyptic fiction

text: post-apocalyptic

text: future Earth. The previous pilot was

text: Genesis II

text: , and it featured many of the concepts and characters later redeveloped in Planet Earth. Sets and props from Genesis II also found their way into Planet Earth.

text: After much time, believed by Daniel Jackson to be thousands of years, the Ancients discovered a "great belt of stars", which they named "Avalon" (Milky Way Galaxy) where they eventually built an impressive empire. The Ancients built Astria Porta (Stargates), which were spread out throughout the Milky Way. Furthermore, the Ancients sent out "seed ships" to spread Stargates to other galaxies, along with Destiny, which was sent out after the "seed ships" to further investigate a pattern discovered in the Cosmic Background Microwave Radiation (Stargate Universe). Among the planets they settled was Earth, which they called Terra. The status of Earth in the Ancients' empire is currently unknown. However, as the planet's original Stargate, eventually discovered by SG-1 in Antarctica, was the oldest gate ever encountered, and being the eventual birthplace of the second evolution of humanity, Earth was probably one of their oldest, if not the first world, they settled upon arriving in this galaxy.  Also the nine-chevron address that dials the ship Destiny must use Earth as the point of origin, no matter what planet the Stargate is dialing from, so Earth must have been very important, possibly the capitol to their empire.  It was also once the location of one of the Ancients City Ships, Atlantis, before it moved to the Pegasus Galaxy, and it was where their descendants returned to after their defeat by the Wraith. Other important planets they have colonized were Praclarush Teonas, Dakara and Valos Cor.

text: After much time, believed by

text: Daniel Jackson

text: to be thousands of years, the Ancients discovered a "great belt of stars", which they named "Avalon" (Milky Way Galaxy) where they eventually built an impressive empire. The Ancients built Astria Porta (Stargates), which were spread out throughout the Milky Way. Furthermore, the Ancients sent out "seed ships" to spread Stargates to other galaxies, along with Destiny, which was sent out after the "seed ships" to further investigate a pattern discovered in the Cosmic Background Microwave Radiation (

text: Stargate Universe

text: ). Among the planets they settled was Earth, which they called Terra. The status of Earth in the Ancients' empire is currently unknown. However, as the planet's original Stargate, eventually discovered by

text: in

text: Antarctica

text: , was the oldest gate ever encountered, and being the eventual birthplace of the second evolution of humanity, Earth was probably one of their oldest, if not the first world, they settled upon arriving in this galaxy.  Also the nine-chevron address that dials the ship Destiny must use Earth as the point of origin, no matter what planet the Stargate is dialing from, so Earth must have been very important, possibly the capitol to their empire.  It was also once the location of one of the

text: Ancients City Ships

text: Atlantis

text: , before it moved to the

text: Pegasus Galaxy

text: , and it was where their descendants returned to after their defeat by the

text: Wraith

text: . Other important planets they have colonized were Praclarush Teonas,

text: Dakara

text: and Valos Cor.

text: Planet Snoop is an online nature documentary spoof narrated by Snoop Dogg that is produced and hosted by Merry Jane. The series was inspired by a handful of segments Snoop filmed for Jimmy Kimmel Live called, "Plizzanet Earth," in which he reacted to clips from the hit BBC nature documentary Planet Earth. The videos were so popular, a petition to have Snoop narrate an entire season of the show garnered 75,000 signatures, leading to the creation of Planet Snoop.

text: Planet Snoop is an online nature documentary spoof narrated by

text: Snoop Dogg

text: that is produced and hosted by Merry Jane. The series was inspired by a handful of segments

text: Snoop

text: filmed for

text: Jimmy Kimmel Live

text: called, "Plizzanet Earth," in which he reacted to clips from the hit BBC nature documentary

text: Planet Earth

text: . The videos were so popular, a petition to have

text: Snoop

text: narrate an entire season of the show garnered 75,000 signatures, leading to the creation of Planet Snoop.

text: Hermann Bondi named the principle after Copernicus in the mid-20th century, although the principle itself dates back to the 16th-17th century paradigm shift away from the Ptolemaic system, which placed Earth at the center of the universe. Copernicus proposed that the motion of the planets can be explained by reference to an assumption that the Sun and not Earth is centrally located and stationary. He argued that the apparent retrograde motion of the planets is an illusion caused by Earth's movement around the Sun, which the Copernican model placed at the centre of the universe. Copernicus himself was mainly motivated by technical dissatisfaction with the earlier system and not by support for any mediocrity principle. In fact, although the Copernican heliocentric model is often described as "demoting" Earth from its central role it had in the Ptolemaic geocentric model, neither Copernicus nor other 15th- and 16th-century scientists and philosophers viewed it as such.  In the late 20th Century, Carl Sagan asked, "Who are we? We find that we live on an insignificant planet of a humdrum star lost in a galaxy tucked away in some forgotten corner of a universe in which there are far more galaxies than people."

text: Hermann Bondi

text: named the principle after Copernicus in the mid-20th century, although the principle itself dates back to the 16th-17th century

text: paradigm shift

text: away from the

text: Ptolemaic system

text: , which placed

text: Earth

text: at the center of the

text: universe

text: . Copernicus proposed that the motion of the planets can be explained by reference to an assumption that the Sun and not Earth is centrally located and stationary. He argued that the

text: apparent retrograde motion

text: of the planets is an illusion caused by Earth's movement around the

text: Sun

text: , which the

text: Copernican model

text: placed at the centre of the universe. Copernicus himself was mainly motivated by technical dissatisfaction with the earlier system and not by support for any mediocrity principle. In fact, although the Copernican heliocentric model is often described as "demoting" Earth from its central role it had in the Ptolemaic geocentric model, neither Copernicus nor other 15th- and 16th-century scientists and philosophers viewed it as such.  In the late 20th Century, Carl Sagan asked, "Who are we? We find that we live on an insignificant planet of a humdrum star lost in a galaxy tucked away in some forgotten corner of a universe in which there are far more galaxies than people."

text: Direct imaging can give only loose constraints of the planet's mass, which is derived from the age of the star and the temperature of the planet. Mass can vary considerably, as planets can form several million years after the star has formed. The cooler the planet is, the less the planet's mass needs to be. In some cases it is possible to give reasonable constraints to the radius of a planet based on planet's temperature, its apparent brightness, and its distance from Earth. The spectra emitted from planets do not have to be separated from the star, which eases determining the chemical composition of planets.

text: Kepler-20f is very likely (>95% chance) a rocky planet because of its radius, which is notable as being the closet to Earth yet: 1.004 . However, although its radius is almost the same as Earth's, its surface conditions are not Earth-like in any way. The equilibrium temperature of Kepler-20f is approximately , too hot to support liquid water on its surface and hot enough to melt some types of metal. But because of its size, it can be expected to have an atmosphere of water vapor. The mass of the planet can be approximated to around 0.66–3.04 , depending on its composition. An Earth-like composition would have its mass to be around 1.2 .

text: Kepler-20f is very likely (>95% chance) a

text: rocky planet

text: because of its radius, which is notable as being the closet to Earth yet: 1.004 . However, although its radius is almost the same as Earth's, its surface conditions are not

text: Earth-like

text: in any way. The equilibrium temperature of Kepler-20f is approximately , too hot to support liquid water on its surface and hot enough to melt some types of metal. But because of its size, it can be expected to have an atmosphere of

text: water vapor

text: . The mass of the planet can be approximated to around 0.66–3.04 , depending on its composition. An Earth-like composition would have its mass to be around 1.2 .

text: In the alternate timeline of the Flashpoint event, Abin Sur is still the Green Lantern of Sector 2814. As the Blackest Night falls in the universe, Abin Sur is dispatched to Earth by the Guardians of the Universe with the mission to retrieve the White Lantern Entity and bring it back to Oa. While reaching planet Earth, Abin Sur's ship is damaged by a laser and he's forced to crash land on the planet. He survives and is approached by Hal Jordan, but is subsequently taken into custody by Cyborg and the US government to be questioned about his reasons for being on Earth. Although he agrees to work with Earth's heroes, he is subsequently attacked by Sinestro, who reveals that he has learned of the prophecy of the "Flashpoint", the moment when everything changes and the original world that existed before this one, during which it is revealed that Abin's home planet has been destroyed in this reality. Seeking the power of the Flash so that he can restore history according to his own vision rather than another, Sinestro cuts off Abin's hand, severing his connection with his ring. The ring then flies onto Abin's other hand, and he manages to defeat and imprison Sinestro. The Guardians then contact Abin, demanding that he bring the Entity to them, and refusing to listen to Sinestro's talk of "the Flashpoint". They then discharge Abin from the Corps, telling him that the ring will find a new wielder when it runs out of power. Abin joins the battle in Europe, and, when a cataclysmic earthquake starts, dives into the crevice, just before his ring runs out of power. The Entity then bonds with Abin, and he sees a vision of his sister, telling him to truly experience life, rather than just living it. Abin then flies into space, and attempts to heal the damage made to the Earth.This version of Abin appears in the Convergence crossover, incorrectly believing the Flashpoint Gotham is endangered by another Superman.

text: In the alternate timeline of the

text: Flashpoint

text: event, Abin Sur is still the Green Lantern of Sector 2814. As the

text: Blackest Night

text: falls in the universe, Abin Sur is dispatched to Earth by the

text: Guardians of the Universe

text: with the mission to retrieve the

text: White Lantern Entity

text: and bring it back to

text: Oa

text: . While reaching planet Earth, Abin Sur's ship is damaged by a laser and he's forced to crash land on the planet. He survives and is approached by

text: Hal Jordan

text: , but is subsequently taken into custody by

text: Cyborg

text: and the US government to be questioned about his reasons for being on Earth. Although he agrees to work with Earth's heroes, he is subsequently attacked by

text: Sinestro

text: , who reveals that he has learned of the prophecy of the "Flashpoint", the moment when everything changes and the original world that existed before this one, during which it is revealed that Abin's home planet has been destroyed in this reality. Seeking the power of the Flash so that he can restore history according to his own vision rather than another, Sinestro cuts off Abin's hand, severing his connection with his ring. The ring then flies onto Abin's other hand, and he manages to defeat and imprison Sinestro. The Guardians then contact Abin, demanding that he bring the Entity to them, and refusing to listen to Sinestro's talk of "the Flashpoint". They then discharge Abin from the Corps, telling him that the ring will find a new wielder when it runs out of power. Abin joins the battle in Europe, and, when a cataclysmic earthquake starts, dives into the crevice, just before his ring runs out of power. The Entity then bonds with Abin, and he sees a vision of his sister, telling him to truly experience life, rather than just living it. Abin then flies into space, and attempts to heal the damage made to the Earth.This version of Abin appears in the Convergence crossover, incorrectly believing the Flashpoint Gotham is endangered by another Superman.

text: A Satellite placed in the halo orbit around the Lagrangian point L1 of the Sun-Earth system has the major advantage of continuously viewing the Sun without any occultation/ eclipses. The Aditya-L1 mission will be inserted in a halo orbit around the L1, which is 1.5 million km from the Earth.  The satellite carries a total of seven payloads with diverse objectives, including but not limited to, the coronal heating problem, solar wind acceleration, coronal magnetometry, origin and monitoring of near-UV solar radiation (which drives Earth's upper atmospheric dynamics and global climate), coupling of the solar photosphere to chromosphere and corona, in-situ characterizations of the space environment around Earth by measuring energetic particle fluxes and magnetic fields of the solar wind and solar magnetic storms that have adverse effects on space and ground-based technologies.

text: The start of season nine reveals that Clark has begun training with Jor-El, which is shown by his wearing his family crest on his chest when in his superhero persona. After realizing there are other Kryptonians on Earth, lacking special powers and led by Zod (Callum Blue), Clark decides to help them adjust to living as humans. When Zod is shot and killed, Clark uses his own blood to bring him back to life, resulting in Zod regaining his Kryptonian powers. Zod enables the other Kryptonians to regain their powers as well, and unites them to destroy the world in order to turn it into a new Krypton. This season, Lois and Clark begin a romantic relationship, while Lois also assists "The Blur" in his heroic endeavors. Clark kisses Lois while he is "the Blur" in the season nine finale and unknowingly reveals to her the truth. Afterward, he convinces the Kryptonians to leave Earth for a new, uninhabited planet. Clark then sacrifices his own life to send Zod through a portal, far away from Earth.

text: The start of

text: season nine

text: reveals that Clark has begun training with Jor-El, which is shown by his wearing

text: his family crest

text: on his chest when in his superhero persona. After realizing there are other Kryptonians on Earth, lacking special powers and led by Zod (

text: Callum Blue

text: ), Clark decides to help them adjust to living as humans. When Zod is shot and killed, Clark uses his own blood to bring him back to life, resulting in Zod regaining his Kryptonian powers. Zod enables the other Kryptonians to regain their powers as well, and unites them to destroy the world in order to turn it into a new Krypton. This season, Lois and Clark begin a romantic relationship, while Lois also assists "The Blur" in his heroic endeavors. Clark kisses Lois while he is "the Blur" in the season nine finale and unknowingly reveals to her the truth. Afterward, he convinces the Kryptonians to leave Earth for a new, uninhabited planet. Clark then sacrifices his own life to send Zod through a portal, far away from Earth.

text: Saula is the second planet (out of four) of EN-7031 solar system, about one and a half times further from its sun than Earth is from ours. The day and night cycle on Saula lasts 28 hours, its mass is about 1.1 of Earth, which means that acceleration of gravity is roughly equal to 10.8 m/s². It has three (!) moons (natural satellites). There are only two continents on Saula: the bigger one on equator and the smaller one close to a pole (it's not specified which one in the book).

text: Saula is the second planet (out of four) of EN-7031 solar system, about one and a half times further from its sun than Earth is from ours. The day and night cycle on Saula lasts 28 hours, its mass is about 1.1 of Earth, which means that

text: acceleration of gravity

text: is roughly equal to 10.8 m/s². It has three (!) moons (natural satellites). There are only two continents on Saula: the bigger one on

text: equator

text: and the smaller one close to a

text: pole

text: (it's not specified which one in the book).

text: Kepler-11 is a G-type star located in the Cygnus. It has a mass of .95 M and a radius of 1.1 R, and is thus almost the same mass and radius as the Sun. With an effective temperature of 5680 K, it is also almost as hot as the Sun, and with a metallicity of 0, Kepler-11 is almost as metal-rich as the Sun is. Metal-rich stars tend to have easily detectable planets because higher metallicities tend to either facilitate the creation of gas giants or to promote planetary migration, in which the planet orbits more closely to its star. However, Kepler-11 is almost 1.73 times older than the Sun, as it has an estimated age of eight billion years. Kepler-11 is 613 parsecs away from the Earth; its distance contributes to its apparent magnitude of 14.2 (V). It, thus, cannot be seen with the naked eye. Other than Kepler-11e, Kepler-11 is the host star of the planets Kepler-11b, Kepler-11c, Kepler-11d, Kepler-11f, and Kepler-11g. The inner five planets in the system orbit in a tightly knit configuration that would fit within the orbit of planet Mercury, while Kepler-11g, compared to its inner sister planets, orbits at a much further distance.

text: Kepler-11 is a

text: G-type star

text: located in the

text: Cygnus

text: . It has a mass of .95

text: M

text: and a radius of 1.1

text: R

text: , and is thus almost the same mass and radius as the Sun. With an

text: effective temperature

text: of 5680

text: K

text: , it is also almost as hot as the Sun, and with a

text: metallicity

text: of 0, Kepler-11 is almost as metal-rich as the Sun is. Metal-rich stars tend to have easily detectable planets because higher metallicities tend to either facilitate the creation of gas giants or to promote

text: planetary migration

text: , in which the planet orbits more closely to its star. However, Kepler-11 is almost 1.73 times older than the Sun, as it has an estimated age of eight billion years. Kepler-11 is 613

text: parsec

text: s away from the Earth; its distance contributes to its

text: apparent magnitude

text: of 14.2 (V). It, thus, cannot be seen with the

text: naked eye

text: . Other than Kepler-11e, Kepler-11 is the host star of the planets

text: , and

text: . The inner five planets in the system orbit in a tightly knit configuration that would fit within the orbit of planet

text: Mercury

text: , while Kepler-11g, compared to its inner sister planets, orbits at a much further distance.

text: Earth's magnetic field, predominantly dipolar at its surface, is distorted further out by the solar wind. This is a stream of charged particles leaving the Sun's corona and accelerating to a speed of 200 to 1000 kilometres per second. They carry with them a magnetic field, the interplanetary magnetic field (IMF).

text: Earth's magnetic field, predominantly dipolar at its surface, is distorted further out by the

text: solar wind

text: . This is a stream of charged particles leaving the Sun's

text: corona

text: and accelerating to a speed of 200 to 1000 kilometres per second. They carry with them a magnetic field, the

text: interplanetary magnetic field

text: (IMF).

text: In early attempts to understand the Earth's magnetic field, measuring it was only part of the challenge. Understanding the measurements was also difficult because the mathematical and physical concepts had not yet been developed – in particular, the concept of a vector field that associates a vector with each point in space. The Earth's field is generally represented by field lines that run from pole to pole; the field at any point is parallel to a field line but does not have to point at either pole.  As late as the eighteenth century, however, a natural philosopher would believe that a magnet had to be pointing directly at something. Thus, the Earth's magnetic field had to be explained by localized sources, and as more was learned about the Earth's field, these sources became increasingly complex.

text: In early attempts to understand the Earth's magnetic field, measuring it was only part of the challenge. Understanding the measurements was also difficult because the mathematical and physical concepts had not yet been developed – in particular, the concept of a

text: vector field

text: that associates a vector with each point in space. The Earth's field is generally represented by

text: field line

text: s that run from pole to pole; the field at any point is parallel to a field line but does not have to point at either pole.  As late as the eighteenth century, however, a

text: natural philosopher

text: would believe that a magnet had to be pointing directly at something. Thus, the Earth's magnetic field had to be explained by localized sources, and as more was learned about the Earth's field, these sources became increasingly complex.

text: In 2191, Earth made first contact with aliens called Gamilas. First attempt at peaceful contact with the Gamilas failed, resulting in interstellar war. The United Nations Cosmo Navy, even though outmatched by the Gamilas space naval forces, was able to stop their direct assaults on Earth in the second battle for Mars, but suffered heavy losses in the process.The Gamilas, from their military base on Pluto, then started planetary bombardment with modified asteroids called planet bombs. The planet bombs hampered United Nations efforts to rebuild their space fleet and forced Earth to build underground cities to protect humanity. The planet bombs altered the atmosphere and irradiated the planetary surface, causing the complete destruction of the planet's biosphere. The Gamilas then started what is believed to be their first step in terraforming ―preparing the Earth to be inhabited by themselves― by introducing plant life that was lethal to any life on Earth. With mankind facing extinction, the United Nations started planning for a small colony of humans to leave Earth in an attempt at the survival of humanity, called the Isumo Plan.But in early 2198 Starsha, from the planet Iscandar, learned of Earth's situation and dispatched her sister Yurisha to Earth. Yurisha brought with her the designs to what is called the Dimensional Wave Motion Engine, providing for interstellar flight along with other technological assistance to Earth. The Iscandarans revealed that they could reverse the damage done to the Earth with the Cosmo Reverse System. For technical reasons they could not send the system directly and would need Earth to send a ship for it. The United Nations then scrapped the Isumo Plan in order to build a new Cosmo Navy ship to retrieve the Cosmo Reverse System. The new ship was designed as a heavily-armed space battleship. To conceal the ship's construction from the Gamilas, Earth built the new ship at the same site as the sunken World War II Yamato battleship. The new space battleship was also named the Yamato for which the series Space Battleship Yamato 2199 is named.

text: In 2191, Earth made first contact with aliens called Gamilas. First attempt at peaceful contact with the Gamilas failed, resulting in interstellar war. The

text: United Nations

text: Cosmo Navy, even though outmatched by the Gamilas space naval forces, was able to stop their direct assaults on Earth in the second battle for Mars, but suffered heavy losses in the process.The Gamilas, from their military base on Pluto, then started planetary bombardment with modified asteroids called planet bombs. The planet bombs hampered United Nations efforts to rebuild their space fleet and forced Earth to build underground cities to protect humanity. The planet bombs altered the atmosphere and irradiated the planetary surface, causing the complete destruction of the planet's biosphere. The Gamilas then started what is believed to be their first step in

text: terraforming

text: ―preparing the Earth to be inhabited by themselves― by introducing plant life that was lethal to any life on Earth. With mankind facing extinction, the United Nations started planning for a small colony of humans to leave Earth in an attempt at the survival of humanity, called the Isumo Plan.But in early 2198 Starsha, from the planet Iscandar, learned of Earth's situation and dispatched her sister Yurisha to Earth. Yurisha brought with her the designs to what is called the Dimensional Wave Motion Engine, providing for interstellar flight along with other technological assistance to Earth. The Iscandarans revealed that they could reverse the damage done to the Earth with the Cosmo Reverse System. For technical reasons they could not send the system directly and would need Earth to send a ship for it. The United Nations then scrapped the Isumo Plan in order to build a new Cosmo Navy ship to retrieve the Cosmo Reverse System. The new ship was designed as a heavily-armed space battleship. To conceal the ship's construction from the Gamilas, Earth built the new ship at the same site as the sunken World War II

text: Yamato battleship

text: . The new space battleship was also named the Yamato for which the series Space Battleship Yamato 2199 is named.

text: Early uses of petroleum- Earth Charter- Earth Day- Earth First!- Earth from the Air- Earth house- Earth immune system- Earth in the Balance- Earth observation satellite- Earth Rights Institute- Earth science- Earth sheltering- Earth Simulator- Earth Summit- Earth Summit 2002- Earthen dam- Earthjustice- Earthlife Africa- EarthSave- Earthwatch Institute- Earthweek

text: Early uses of petroleum

text: Earth Charter

text: Earth Day

text: Earth First!

text: Earth from the Air

text: Earth house

text: Earth immune system

text: Earth in the Balance

text: Earth observation satellite

text: Earth Rights Institute

text: Earth science

text: Earth sheltering

text: Earth Simulator

text: Earth Summit

text: Earth Summit 2002

text: Earthen dam

text: Earthjustice

text: Earthlife Africa

text: EarthSave

text: Earthwatch Institute

text: Earthweek

text: Earth science (also known as geoscience, the geosciences or the Earth Sciences), is an all-embracing term for the sciences related to the planet Earth. It is arguably a special case in planetary science, the Earth being the only known life-bearing planet. There are both reductionist and holistic approaches to Earth science. There are four major disciplines in earth sciences, namely geography, geology, geophysics and geodesy. These major disciplines use physics, chemistry, biology, chronology and mathematics to build a quantitative understanding of the principal areas or spheres of the Earth system.

text: Earth science

text: science

text: s related to the planet

text: Earth

text: . It is arguably a special case in

text: planetary science

text: , the Earth being the only known

text: life

text: -bearing planet. There are both

text: reductionist

text: and

text: holistic

text: approaches to Earth science. There are four major

text: discipline

text: s in earth sciences, namely

text: geography

text: geology

text: geophysics

text: and

text: geodesy

text: . These major disciplines use

text: physics

text: chemistry

text: biology

text: chronology

text: and

text: mathematics

text: to build a quantitative understanding of the principal areas or

text: spheres

text: of the Earth system.

text: However, planetocentric longitude is always measured positively to the east, regardless of which way the planet rotates. East is defined as the counter-clockwise direction around the planet, as seen from above its north pole, and the north pole is whichever pole more closely aligns with the Earth's north pole. Longitudes traditionally have been written using "E" or "W" instead of "+" or "−" to indicate this polarity. For example, the following all mean the same thing:The reference surfaces for some planets (such as Earth and Mars) are ellipsoids of revolution for which the equatorial radius is larger than the polar radius; in other words, they are oblate spheroids. Smaller bodies (Io, Mimas, etc.) tend to be better approximated by triaxial ellipsoids; however, triaxial ellipsoids would render many computations more complicated, especially those related to map projections. Many projections would lose their elegant and popular properties. For this reason spherical reference surfaces are frequently used in mapping programs.

text: However, planetocentric longitude is always measured positively to the east, regardless of which way the planet rotates. East is defined as the counter-clockwise direction around the planet, as seen from above its north pole, and the north pole is whichever pole more closely aligns with the Earth's north pole. Longitudes traditionally have been written using "E" or "W" instead of "+" or "−" to indicate this polarity. For example, the following all mean the same thing:The reference surfaces for some planets (such as Earth and

text: Mars

text: ) are

text: ellipsoid

text: s of revolution for which the equatorial radius is larger than the polar radius; in other words, they are

text: oblate spheroid

text: s. Smaller bodies (

text: Io

text: Mimas

text: , etc.) tend to be better approximated by

text: triaxial ellipsoids

text: ; however, triaxial ellipsoids would render many computations more complicated, especially those related to

text: map projection

text: s. Many projections would lose their elegant and popular properties. For this reason spherical reference surfaces are frequently used in mapping programs.

text: Gliese 581 c is the third planet orbiting Gliese 581. It was discovered in April 2007. In their 2007 paper, Udry et al. asserted that if Gliese 581 c has an Earth-type composition, it would have a radius of 1.5R, which would have made it at the time "the most Earth-like of all known exoplanets". A direct measurement of the radius cannot be taken because, viewed from Earth, the planet does not transit its star. The minimum mass of the planet is 5.5 times that of Earth. The planet initially attracted attention as being potentially habitable, though this has since been discounted. The mean blackbody surface temperature has been estimated to lie between −3 °C (for a Venus-like albedo) and 40 °C (for an Earth-like albedo), however, the temperatures could be much higher (about 500 degrees Celsius) due to a runaway greenhouse effect akin to that of Venus. Some astronomers believe the system may have undergone planetary migration and Gliese 581 c may have formed beyond the frost line, with a composition similar to icy bodies like Ganymede. Gliese 581 c completes a full orbit in just under 13 days.

text: Gliese 581 c is the third planet orbiting Gliese 581. It was discovered in April 2007. In their 2007 paper, Udry et al. asserted that if Gliese 581 c has an Earth-type composition, it would have a radius of 1.5R, which would have made it at the time "the most Earth-like of all known exoplanets". A direct measurement of the radius cannot be taken because, viewed from Earth, the planet does not

text: transit

text: its star. The minimum mass of the planet is 5.5 times that of Earth. The planet initially attracted attention as being potentially habitable, though this has since been discounted. The mean blackbody surface temperature has been estimated to lie between −3 °C (for a Venus-like

text: albedo

text: ) and 40 °C (for an Earth-like albedo), however, the temperatures could be much higher (about 500 degrees Celsius) due to a runaway greenhouse effect akin to that of

text: Venus

text: . Some astronomers believe the system may have undergone

text: planetary migration

text: and Gliese 581 c may have formed beyond the

text: frost line

text: , with a composition similar to icy bodies like

text: Ganymede

text: . Gliese 581 c completes a full orbit in just under 13 days.

text: Magnetic fields similar to Earth's are common throughout known space and many undergo similar flux transfer events.  During its second flyby of the planet on October 6, 2008, the NASA probe MESSENGER discovered that Mercury’s magnetic field shows a magnetic reconnection rate ten times higher than Earth's. Mercury's proximity to the Sun only accounts for about a third of the reconnection rate observed by MESSENGER and the cause of this discrepancy is not currently known.

text: Magnetic fields similar to Earth's are common throughout known space and many undergo similar flux transfer events.  During its second flyby of the planet on October 6, 2008, the NASA probe

text: MESSENGER

text: discovered that

text: Mercury

text: ’s magnetic field shows a magnetic reconnection rate ten times higher than Earth's. Mercury's proximity to the Sun only accounts for about a third of the reconnection rate observed by MESSENGER and the cause of this discrepancy is not currently known.

text: Galileo's ship refers to two physics experiments, a thought experiment and an actual experiment, by Galileo Galilei, the 16th and 17th century physicist, astronomer, and philosopher. The experiments were created to argue the idea of a rotating Earth as opposed to a stationary Earth around which rotated the Sun and planets and stars.

text: Galileo's ship refers to two physics experiments, a

text: thought experiment

text: and an actual experiment, by

text: Galileo Galilei

text: , the 16th and 17th century physicist, astronomer, and philosopher. The experiments were created to argue the idea of a

text: rotating

text: Earth

text: as opposed to a stationary Earth around which rotated the Sun and planets and stars.

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: On the planet Earth specifically, a gravity train has the following parameters:

text: On the planet

text: Earth

text: specifically, a gravity train has the following parameters:

text: The , named Supreme Kai in the English anime dub, was originally the ruler of the eastern quadrant of the universe but due to his fellow Kaiō-shin's being defeated by Boo is now the de facto ruler of the entire universe. He is the only Kaiō-shin to appear in the original manga, besides very brief appearances of the South Kaiō-shin and Dai Kaiō-shin in single panels. He has purple skin and a white mohawk and is always accompanied by his larger, reddish-pink skinned, loyal bodyguard . He came to Earth, originally under the alias , to meet Goku and his friends and try to help prevent Bobbidi from resurrecting Boo but ends up failing. Kaiō-shin takes Gohan to his own private planet where he has him train using the  (Z Sword in the English anime dub) but instead the sword is broken releasing Kaiō-shin's ancestor, referred to as , who uses his power to increase Gohan's. Kaiō-shin and Kibito later get permanently fused into one being, referred to as , when they each remove one of their  earrings. Kaiō-shin later assists in the final battle with Boo by teleporting Goku and the last survivors on Earth onto his planet and helps take Dende to the new planet Namek to use its Dragon Balls to revive Earth and its people. In Japanese he is voiced by Yūji Mitsuya, and by Kent Williams in Funimation's English dub.

text: The , named Supreme Kai in the English anime dub, was originally the ruler of the eastern quadrant of the universe but due to his fellow Kaiō-shin's being defeated by Boo is now the de facto ruler of the entire universe. He is the only Kaiō-shin to appear in the original manga, besides very brief appearances of the South Kaiō-shin and Dai Kaiō-shin in single panels. He has purple skin and a white mohawk and is always accompanied by his larger, reddish-pink skinned, loyal bodyguard . He came to Earth, originally under the alias , to meet Goku and his friends and try to help prevent Bobbidi from resurrecting Boo but ends up failing. Kaiō-shin takes Gohan to his own private planet where he has him train using the  (Z Sword in the English anime dub) but instead the sword is broken releasing Kaiō-shin's ancestor, referred to as , who uses his power to increase Gohan's. Kaiō-shin and Kibito later get permanently fused into one being, referred to as , when they each remove one of their  earrings. Kaiō-shin later assists in the final battle with Boo by teleporting Goku and the last survivors on Earth onto his planet and helps take Dende to the new planet Namek to use its Dragon Balls to revive Earth and its people. In Japanese he is voiced by

text: Yūji Mitsuya

text: , and by

text: Kent Williams

text: in Funimation's English dub.

text: The UN forces are hampered by the realities of Freehold: 90% of freehold is armed, a large number are military service veterans, the planet has gravity 1.18 times that of Earths', they do not know the terrain, and there is no government infrastructure for them to assimilate. Eventually Naumann calls in the guerillas and organizes a massive counter-offensive in which Kendra is charged with holding an infantry line against a numerically superior force with little support. She is seriously wounded in the effort, but holds her line and the UN forces are defeated. Kendra helps with the systematic urban warfare to clean out the cities, and in the process is raped. Naumann uses captured space materiel to launch orbital strikes on Earth and launches several black operations missions on large cities, causing massive death and destruction.

text: The UN forces are hampered by the realities of Freehold: 90% of freehold is armed, a large number are military service veterans, the planet has gravity 1.18 times that of Earths', they do not know the terrain, and there is no government infrastructure for them to assimilate. Eventually Naumann calls in the guerillas and organizes a massive counter-offensive in which Kendra is charged with holding an infantry line against a numerically superior force with little support. She is seriously wounded in the effort, but holds her line and the UN forces are defeated. Kendra helps with the systematic

text: urban warfare

text: to clean out the cities, and in the process is raped. Naumann uses captured space materiel to launch orbital strikes on Earth and launches several black operations missions on large cities, causing massive death and destruction.

text: The human settlers from Earth have come to Alflolol, which they have named Technorog, attracted by the valuable natural resources it offers. To provide protection, they have placed huge electro-magnetic relay beacons on the asteroids in the belt that rings the planet. When activated these beacons generate an impenetrable shield around the planet. Ingress and egress is only permitted to authorised spacecraft through a narrow channel that can be opened in the asteroid belt. Alflolol's harsh atmospheric conditions are harmful to humans if exposure to them is prolonged so they live under domes and wear protective clothing when working outside. The domes also simulate an Earth-like cycle of day and night. The capital city they have constructed is called Technorogville and it lies on a hill on the ancestral burial site of Algol's family. Nearby is a forest, known as Ananil to the Alflololians, which leads to the shores of the sea, named Magnet Ocean by the humans, where the settlers use floating platforms to extract magnetic salts which fuel the ultra-light motors of Galaxity's spacecraft. In the surrounding mountains, gigantic mines extract rare metals which are processed and used in manufacturing in the colossal factories that lie on the plains near the desert. Great hydroponic plantations are required to feed the workers who keep this vast enterprise going. The planet is administered by a technocrat Governor who reports to a council representing the business interests on the planet.

text: The human settlers from

text: Earth

text: have come to Alflolol, which they have named Technorog, attracted by the valuable natural resources it offers. To provide protection, they have placed huge electro-magnetic relay beacons on the asteroids in the belt that rings the planet. When activated these beacons generate an impenetrable shield around the planet. Ingress and egress is only permitted to authorised spacecraft through a narrow channel that can be opened in the asteroid belt. Alflolol's harsh atmospheric conditions are harmful to humans if exposure to them is prolonged so they live under domes and wear protective clothing when working outside. The domes also simulate an Earth-like cycle of day and night. The capital city they have constructed is called Technorogville and it lies on a hill on the ancestral burial site of Algol's family. Nearby is a forest, known as Ananil to the Alflololians, which leads to the shores of the sea, named Magnet Ocean by the humans, where the settlers use floating platforms to extract magnetic salts which fuel the ultra-light motors of Galaxity's spacecraft. In the surrounding mountains, gigantic mines extract rare metals which are processed and used in manufacturing in the colossal factories that lie on the plains near the desert. Great

text: hydroponic

text: plantations are required to feed the workers who keep this vast enterprise going. The planet is administered by a

text: technocrat

text: Governor who reports to a council representing the business interests on the planet.

text: Vouge BFFs  Season 1 finale aired on 3 December 2016. The Flash Season 3 midseason finale aired on 7 December 2016. Arrow Season 5 midseason finale aired on 8 December 2016. Notorious Season 1  finale aired on 9 December 2016. DC's Legends of Tomorrow Season 2 midseason finale aired on 9 December 2016. Mozart in the Jungle Season 3 premiered back-to-back on 10 December 2016 on Live Binge. Timeless Season 1  midseason finale aired on 12 December 2016. Law & Order: Special Victims Unit Season 16 finale aired on 16 December 2016. It was replaced by Southland Season 1 from 19 January 2016.

text: Vouge BFFs  Season 1 finale aired on 3 December 2016.

text: The Flash

text: Season 3 midseason finale aired on 7 December 2016.

text: Arrow

text: Season 5 midseason finale aired on 8 December 2016.

text: Notorious

text: Season 1  finale aired on 9 December 2016.

text: DC's Legends of Tomorrow

text: Season 2 midseason finale aired on 9 December 2016.

text: Mozart in the Jungle

text: Season 3 premiered back-to-back on 10 December 2016 on Live Binge.

text: Timeless

text: Season 1  midseason finale aired on 12 December 2016.

text: Law & Order: Special Victims Unit

text: Season 16 finale aired on 16 December 2016. It was replaced by

text: Southland

text: Season 1 from 19 January 2016.

text: The surface of the Earth is rotating, so it is not an inertial frame of reference. At latitudes nearer the Equator, the outward centrifugal force produced by Earth's rotation is larger than at polar latitudes. This counteracts the Earth's gravity to a small degree – up to a maximum of 0.3% at the Equator – and reduces the apparent downward acceleration of falling objects.

text: The surface of the Earth is rotating, so it is

text: not an inertial frame of reference

text: . At latitudes nearer the Equator, the outward

text: centrifugal force

text: produced by Earth's rotation is larger than at polar latitudes. This counteracts the Earth's gravity to a small degree – up to a maximum of 0.3% at the Equator – and reduces the apparent downward acceleration of falling objects.

text: Though not confirmed to be a terrestrial planet and significantly more massive than Earth (at 6.98 Earth masses), the Super-Earth is the first exoplanet of terrestrial mass proposed to orbit within the habitable zone of its parent star.

text: Though not confirmed to be a

text: terrestrial planet

text: and significantly more massive than Earth (at 6.98 Earth masses), the

text: Super-Earth

text: is the first exoplanet of terrestrial mass proposed to orbit within the habitable zone of its parent star.

text: An asteroid occultation occurs when an asteroid (also known as a minor planet) passes in front of a star (occults a star), temporarily blocking its light (as seen from Earth). Several events occur nearly every day over the world. From any particular place such events occur almost every night, although most require a telescope to see. Professionals and amateurs around the globe are collaborating over the Internet to exchange their observation for a joint analysis.

text: An asteroid occultation occurs when an

text: asteroid

text: (also known as a

text: minor planet

text: ) passes in front of a

text: star

text: (occults a star), temporarily blocking its light (as seen from

text: Earth

text: ). Several events occur nearly every day over the world. From any particular place such events occur almost every night, although most require a

text: telescope

text: to see. Professionals and amateurs around the globe are collaborating over the Internet to exchange their observation for a joint analysis.

text: In The Hitchhiker's Guide to the Galaxy series by Douglas Adams, the Earth is destroyed by a Vogon Constructor Fleet to make room for a hyperspace bypass.  One of two surviving Earthmen, Arthur Dent, is affronted and dismayed to find that his planet's entry in the Guide consists of one word: "Harmless".  Ford Prefect, a researcher for the Guide attempts (and fails) to placate him by informing him that he has written a more extensive article for the next edition, although the result of merciless editing of his original draft has reduced his version considerably, now reading "Mostly harmless".  Dent also learns that the Earth was originally constructed by the inhabitants of the planet Magrathea, as a giant supercomputer built to find the Question to the Ultimate Answer of Life, The Universe and Everything.  The computer was so large that it was often mistaken for a planet, and that it was destroyed five minutes before the program was due to complete (after ten million years of running).  It also mentions that humans are descended from the passengers of an ark full of unwanted middlemen (hairdressers, telephone sanitizers, advertising executives and the like), tricked into leaving their own planet behind by spurious tales of impending destruction invented by the rest of the planet's civilization (it is mentioned that the population was then wiped out by a disease contracted from a dirty telephone).  The Earth was located in Galactic sector ZZ9 Plural Z Alpha.  An alternate version of Earth is the planet NowWhat, which occupies the same space as Earth, but not the same probability. In the 2005 film adaptation, a new Earth replaces the old one, and everything is restored to the moments leading up to its destruction, except for one thing: Arthur Dent is not part of the planet anymore, at his own request.

text: In

text: The Hitchhiker's Guide to the Galaxy

text: series by

text: Douglas Adams

text: , the

entity_name: Places in The Hitchhiker's Guide to the Galaxy

text: Earth

text: is destroyed by a Vogon Constructor Fleet to make room for a hyperspace bypass.  One of two surviving Earthmen,

text: Arthur Dent

text: , is affronted and dismayed to find that his planet's entry in the Guide consists of one word: "Harmless".

text: Ford Prefect

text: , a researcher for the Guide attempts (and fails) to placate him by informing him that he has written a more extensive article for the next edition, although the result of merciless editing of his original draft has reduced his version considerably, now reading "Mostly harmless".  Dent also learns that the Earth was originally constructed by the inhabitants of the planet

text: Magrathea

text: , as a giant supercomputer built to find the Question to

entity_name: Phrases from The Hitchhiker's Guide to the Galaxy

entity_section: Answer to the Ultimate Question of Life, the Universe, and Everything (42)

text: the Ultimate Answer of Life, The Universe and Everything

text: .  The computer was so large that it was often mistaken for a planet, and that it was destroyed five minutes before the program was due to complete (after ten million years of running).  It also mentions that humans are descended from the passengers of an ark full of unwanted middlemen (hairdressers, telephone sanitizers, advertising executives and the like), tricked into leaving their own planet behind by spurious tales of impending destruction invented by the rest of the planet's civilization (it is mentioned that the population was then wiped out by a disease contracted from a dirty telephone).  The Earth was located in Galactic sector ZZ9 Plural Z Alpha.  An alternate version of Earth is the planet

text: NowWhat

text: , which occupies the same space as Earth, but not the same probability. In the

entity_name: The Hitchhiker's Guide to the Galaxy (film)

text: 2005 film adaptation

text: , a new Earth replaces the old one, and everything is restored to the moments leading up to its destruction, except for one thing: Arthur Dent is not part of the planet anymore, at his own request.

text: Kepler-11f is, at 2.3 times the mass of Earth, the least massive of the six planets discovered in the orbit of Kepler-11, although the planet's mass may range from 1.1 to 4.5, or from approximately that of Earth's mass to that of Kepler-10b, a rather large confidence interval. Its radius is the second smallest of the six planets discovered in the system at 2.61 times the radius of Earth. Kepler-11f has a density of about 0.7 g/cm, comparable to that of the Solar System's least dense planet, Saturn. Kepler-11f is the fifth planet from Kepler-11, orbiting its host star every 46.68876 days at a distance of 0.25 AU. Its orbital eccentricity is unknown. In comparison, Mercury orbits the Sun every 87.97 days at a distance of 0.387 AU. Kepler-11f has an orbital inclination of 89.4°; it can be seen almost edge-on with respect to Earth. Its surface equilibrium temperature is 544 K, over twice the surface equilibrium temperature of Earth and about two-thirds the surface temperature of Venus.

text: Kepler-11f is, at 2.3 times the

text: mass of Earth

text: , the least massive of the six planets discovered in the orbit of Kepler-11, although the planet's mass may range from 1.1 to 4.5, or from approximately that of Earth's mass to that of

text: , a rather large

text: confidence interval

text: . Its

text: radius

text: is the second smallest of the six planets discovered in the system at 2.61 times the radius of Earth. Kepler-11f has a density of about 0.7 g/cm, comparable to that of the Solar System's least dense planet, Saturn. Kepler-11f is the fifth planet from Kepler-11, orbiting its host star every 46.68876 days at a distance of 0.25

text: AU

text: . Its

text: orbital eccentricity

text: is unknown. In comparison,

text: Mercury

text: orbits the Sun every 87.97 days at a distance of 0.387 AU. Kepler-11f has an orbital

text: inclination

text: of 89.4°; it can be seen almost edge-on with respect to Earth. Its surface

text: equilibrium temperature

text: is 544 K, over twice the surface equilibrium temperature of

text: Earth

text: and about two-thirds the surface temperature of

text: Venus

text: The seasons were of variable length: Season 1 through Season 8 were of 26-30 episodes, Season 9 through Season 12 were of 38-39 episodes, Season 13 through Season 17 were of 47-52 episodes, and the final Season 18 was of 22 episodes.

text: The realisation of time has gone through three phases. During both the first and second phases, man used Solar time—during the first phase, realisation of time was by observing the earth's rotation using such devices as the sundial or astrolabe.  During the second phase actual timing devices such as hourglasses or clocks were used. If the user needed to know time-of-day rather than elapsed time, clocks were synchronized with astronomical time.  The third phase made use of clocks that were sufficiently accurate that they could measure variations in the earth's rotation—such clocks taking over from the rotation of the earth as the prime measure of time.

text: The realisation of time has gone through three phases. During both the first and second phases, man used

text: Solar time

text: —during the first phase, realisation of time was by observing the earth's rotation using such devices as the

text: sundial

text: or

text: astrolabe

text: .  During the second phase actual timing devices such as

text: hourglass

text: es or

text: clock

text: s were used. If the user needed to know time-of-day rather than elapsed time, clocks were

text: synchronized

text: with astronomical time.  The third phase made use of clocks that were sufficiently accurate that they could measure variations in the earth's rotation—such clocks taking over from the rotation of the earth as the prime measure of time.

text: Gliese 581 e is the innermost planet and with a minimum mass of 1.7 Earth masses is the least massive of the three. Discovered in 2009, it is also the most recent confirmed planet to have been discovered in this system. It takes 3.15 days to complete an orbit. Initial analyses suggested that the planet's orbit is quite elliptical but after correcting the radial velocity measurements for stellar activity, the data now indicate a circular orbit.

text: Most episodes of Regular Show last 11 minutes; episodes are usually paired together to fill a half-hour program slot. 230 episodes in seven seasons have been completed and broadcast. The first season began on September 6, 2010, with the episode "The Power" and ended on November 22, 2010, with "Mordecai and the Rigbys". The second season began on November 29, 2010, with "Ello Gov'nor" and ended on August 1, 2011, with "Karaoke Video". The third season premiered on September 19, 2011, with the episode "Stick Hockey" and concluded on September 3, 2012, with "Bad Kiss". The fourth season premiered on October 1, 2012, with the half-hour special "Exit 9B" and concluded on August 12, 2013 with "Steak Me Amadeus". The fifth season premiered on September 2, 2013, with the episodes "Laundry Woes" and "Silver Dude" and concluded on August 14, 2014, with "Real Date". The sixth season premiered on October 9, 2014, with "Maxin' and Relaxin'", and ended on June 25, 2015 with "Dumped at the Altar". The seventh season premiered with "Dumptown USA" on June 26, 2015 and ended with the half-hour "Rigby's Graduation Day Special" on June 30, 2016. The eighth and final season is set to air starting on September 26, 2016, and ending in January 2017.

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: "Night and Day" is the second single from Some People's Lives. It was released to adult contemporary radio and stayed on the chart for 15 weeks, peaking at #15. The release to mainstream radio came later. As "Night and Day" was ascending the Billboard Hot 100, the Gulf War broke out, focusing attention back on the first single, "From A Distance". "Night and Day" remained on the Hot 100 for 7 weeks.

text: "Night and Day" is the second single from Some People's Lives. It was released to adult contemporary radio and stayed on the chart for 15 weeks, peaking at #15. The release to mainstream radio came later. As "Night and Day" was ascending the Billboard Hot 100, the

text: Gulf War

text: broke out, focusing attention back on the first single, "From A Distance". "Night and Day" remained on the Hot 100 for 7 weeks.

text: Zillikian is a counter-Earth planet (i.e. located  at the L3 Lagrange point which is opposite the Sun in the same orbit as Earth). The planet is very similar to Earth in climate and wildlife, albeit without the industrialization of Humans  that Earth has.

text: Zillikian is a

text: counter-Earth

text: planet (i.e. located  at the L3

text: Lagrange point

text: which is opposite the Sun in the same orbit as Earth). The planet is very similar to Earth in climate and wildlife, albeit without the industrialization of Humans  that Earth has.

text: The game is loosely based on the "Fatal Attractions" storyline. The main antagonist is Magneto, who plans to unleash an electromagnetic pulse on the Earth that will disrupt the magnetic fields and create havoc on the world's electrical systems ushering in a Dark Age for Earth's non-mutant population. With the promise of a mutant-run planet, the X-Men's most formidable foes join forces with Magneto.

text: The game is loosely based on the "

text: Fatal Attractions

text: " storyline. The main antagonist is

text: Magneto

text: , who plans to unleash an

text: electromagnetic pulse

text: on the Earth that will disrupt the magnetic fields and create havoc on the world's electrical systems ushering in a Dark Age for Earth's non-mutant population. With the promise of a mutant-run planet, the X-Men's most formidable foes join forces with Magneto.

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 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: Planets form within a few tens of millions of years of their star forming, and there are stars that are forming today and other stars that are ten billion years old, so unlike the planets of the Solar System, which can only be observed as they are today, studying exoplanets allows the observation of exoplanets at different stages of evolution. When planets form they have hydrogen envelopes that cool and contract over time and, depending on the mass of the planet, some or all of the hydrogen is eventually lost to space. This means that even terrestrial planets can start off with large radii. An example is Kepler-51b which has only about twice the mass of Earth but is almost the size of Saturn which is a hundred times the mass of Earth. Kepler-51b is quite young at a few hundred million years old.

text: Planets form within a few tens of millions of years of their star forming, and there are stars that are forming today and other stars that are ten billion years old, so unlike the planets of the

text: Solar System

text: , which can only be observed as they are today, studying exoplanets allows the observation of exoplanets at different stages of evolution. When planets form they have

text: hydrogen

text: envelopes that cool and contract over time and, depending on the mass of the planet, some or all of the hydrogen is eventually lost to space. This means that even terrestrial planets can start off with large radii. An example is Kepler-51b which has only about twice the mass of Earth but is almost the size of Saturn which is a hundred times the mass of Earth. Kepler-51b is quite young at a few hundred million years old.

text: A "night version" photo teaser for The Best Man was revealed on May 8. A "day version" was posted on the following day. The music video teaser for "Night and Day", which features cameos by Yura of Girl's Day and C.A.P of Teen Top, was uploaded on the next day. The mini-album and the music video for the lead single were simultaneously released on May 12.

text: A "night version" photo teaser for The Best Man was revealed on May 8. A "day version" was posted on the following day. The music video teaser for "Night and Day", which features cameos by

text: Yura

text: of

text: Girl's Day

text: and C.A.P of

text: Teen Top

text: , was uploaded on the next day. The mini-album and the music video for the

text: lead single

text: were simultaneously released on May 12.

text: It is interesting to note that the axial tilt and eccentricity of Earth (or Mars) are by no means fixed, but rather vary due to gravitational perturbations from other planets in the solar system on a timescale of tens of thousands or hundreds of thousands of years. Thus, for example Earth's eccentricity of about 1% regularly fluctuates and can increase up to 6%, and at some point in the distant future the Earth will also have to deal with the calendrical implications of seasons of widely differing length (and the major climate disruptions that go along with it).

text: It is interesting to note that the axial tilt and eccentricity of Earth (or Mars) are by no means fixed, but rather vary due to gravitational perturbations from other planets in the

text: solar system

text: on a timescale of tens of thousands or hundreds of thousands of years. Thus, for example Earth's eccentricity of about 1% regularly fluctuates and can increase up to 6%, and at some point in the distant future the Earth will also have to deal with the calendrical implications of seasons of widely differing length (and the major climate disruptions that go along with it).

text: Later, a research spaceship from Earth lands on Saybrook's Planet to investigate the report by the earlier colony ship. The crew take no chances and incinerate all life around the landing point, while carefully preventing any life from the planet from coming on board. They confirm Saybrook's report, then set out to return to Earth to recommend that Saybrook's Planet be permanently quarantined. Unknown to the research ship's crew they carry a stowaway — a part of the planet's fauna that crawled aboard when they temporarily dropped their force fields. The small creature has been specially bred to resemble a length of wiring and go undetected. The planetary organism has never before experienced selfishness and violence and is desperate to "help" the "life fragments" (Earthlings) to become "complete", by joining consciousness with it in blissful unity. If the stowaway manages to reach Earth, it will eventually convert all life there into a single organism with a unified consciousness — and green patches of fur instead of eyes.

text: Later, a research spaceship from

text: Earth

text: lands on Saybrook's Planet to investigate the report by the earlier colony ship. The crew take no chances and incinerate all life around the landing point, while carefully preventing any life from the planet from coming on board. They confirm Saybrook's report, then set out to return to Earth to recommend that Saybrook's Planet be permanently

text: quarantine

text: d. Unknown to the research ship's crew they carry a stowaway — a part of the planet's

text: fauna

text: that crawled aboard when they temporarily dropped their force fields. The small creature has been specially bred to resemble a length of wiring and go undetected. The planetary organism has never before experienced selfishness and violence and is desperate to "help" the "life fragments" (Earthlings) to become "complete", by joining consciousness with it in blissful unity. If the stowaway manages to reach Earth, it will eventually convert all life there into a single organism with a unified consciousness — and green patches of fur instead of eyes.

text: Day is usually defined as the period when sunlight reaches the ground in the absence of local obstacles. On the day of the equinox, the center of the Sun spends a roughly equal amount of time above and below the horizon at every location on the Earth, so night and day are about the same length. In reality, the day is longer than the night at an equinox. There are two reasons for this:

text: Planets with their own magnetic field, such as the Earth and Jupiter, are surrounded by a magnetosphere within which their magnetic field is dominant over the Sun's.  This disrupts the flow of the solar wind, which is channelled around the magnetosphere.  Material from the solar wind can 'leak' into the magnetosphere, causing aurorae and also populating the Van Allen Belts with ionised material.

text: Planets with their own magnetic field, such as the Earth and

text: Jupiter

text: , are surrounded by a

text: magnetosphere

text: within which their magnetic field is dominant over the

text: Sun

text: 's.  This disrupts the flow of the solar wind, which is channelled around the magnetosphere.  Material from the solar wind can 'leak' into the magnetosphere, causing

text: aurora

text: e and also populating the

text: Van Allen Belts

text: with ionised material.

text: Iron is a chemical element with symbol Fe (from ) and atomic number 26. It is a metal in the first transition series. It is by mass the most common element on Earth, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust. Its abundance in rocky planets like Earth is due to its abundant production by fusion in high-mass stars, where it is the last element to be produced with release of energy before the violent collapse of a supernova, which scatters the iron into space.

text: Iron is a

text: chemical element

text: with symbol Fe (from ) and

text: atomic number

text: 26. It is a

text: metal

text: in the

text: first transition series

text: . It is by mass the most common element on

text: Earth

text: , forming much of Earth's

text: outer

text: and

text: inner core

text: . It is the fourth most common

text: element in the Earth's crust

text: . Its abundance in

text: rocky planets

text: like Earth is due to its abundant production by

text: fusion

text: in high-mass

text: stars

text: , where it is the last element to be produced with release of energy before the violent collapse of a

text: supernova

text: , which scatters the iron into space.

text: In Akira Toriyama's Dragon Ball series, Earth is the primary setting and one of many planets in the North Galaxy. The planet is inhabited by humans, anthropomorphic animals, and demons, among others. Dragon Balls Earth features heavy science fiction themes, such as humanoid robots and flying cars, as well as heavy magical influence.

text: In

text: Akira Toriyama

text: 's

text: Dragon Ball

text: series, Earth is the primary setting and one of many planets in the North Galaxy. The planet is inhabited by humans,

text: anthropomorphic

text: animals, and demons, among others. Dragon Balls Earth features heavy

text: science fiction themes

text: , such as

text: humanoid robot

text: s and flying cars, as well as heavy magical influence.

text: The limit between rocky planets and planets with a thick gaseous envelope is calculated with theoretical models. Calculating the effect of the active XUV saturation phase of G-type stars over the loss of the primitive nebula-captured hydrogen envelopes in extrasolar planets, it's obtained that planets with a core mass of more than 1.5 Earth-mass (1.15 Earth-radius max.), most likely cannot get rid of their nebula captured hydrogen envelopes during their whole lifetime. Other calculations point out that the limit between envelope-free rocky super-Earths and sub-Neptunes is around 1.75 Earth-radii, as 2 Earth-radii would be the upper limit to be rocky (a planet with 2 Earth-radii and 5 Earth-masses with a mean Earth-like core composition would imply that 1/200 of its mass would be in a H/He envelope, with an atmospheric pressure near to ).  Whether or not the primitive nebula-captured H/He envelope of a super-Earth is entirely lost after formation also depends on the orbital distance. For example, formation and evolution calculations of the Kepler-11 planetary system show that the two innermost planets Kepler-11b and c, whose calculated mass is ≈2 M and between ≈5 and 6 M respectively (which are within measurement errors), are extremely vulnerable to envelope loss.  In particular, the complete removal of the primordial H/He envelope by energetic stellar photons appears almost inevitable in the case of Kepler-11b, regardless of its formation hypothesis.

text: The limit between rocky planets and planets with a thick gaseous envelope is calculated with theoretical models. Calculating the effect of the active XUV saturation phase of G-type stars over the loss of the primitive nebula-captured hydrogen envelopes in extrasolar planets, it's obtained that planets with a core mass of more than 1.5 Earth-mass (1.15 Earth-radius max.), most likely cannot get rid of their nebula captured hydrogen envelopes during their whole lifetime. Other calculations point out that the limit between envelope-free rocky super-Earths and sub-Neptunes is around 1.75 Earth-radii, as 2 Earth-radii would be the upper limit to be rocky (a planet with 2 Earth-radii and 5 Earth-masses with a mean Earth-like core composition would imply that 1/200 of its mass would be in a H/He envelope, with an atmospheric pressure near to ).  Whether or not the primitive nebula-captured H/He envelope of a super-Earth is entirely lost after formation also depends on the orbital distance. For example, formation and evolution calculations of the

text: planetary system show that the two innermost planets Kepler-11b and c, whose calculated mass is ≈2

text: M

text: and between ≈5 and 6 M respectively (which are within measurement errors), are extremely vulnerable to envelope loss.  In particular, the complete removal of the primordial H/He envelope by energetic stellar photons appears almost inevitable in the case of Kepler-11b, regardless of its formation hypothesis.

text: Animals including birds and turtles can detect the Earth's magnetic field, and use the field to navigate during migration. Cows and wild deer tend to align their bodies north-south while relaxing, but not when the animals are under high-voltage power lines, leading researchers to believe magnetism is responsible.<ref name='Nature summary'></ref> In 2011, researchers reported their failed attempt to replicate the finding using different Google Earth images.

text: Animals including birds and turtles can detect the Earth's magnetic field, and use the field to navigate during

text: migration

text: . Cows and wild deer tend to align their bodies north-south while relaxing, but not when the animals are under high-voltage power lines, leading researchers to believe magnetism is responsible.<ref name='Nature summary'></ref> In 2011, researchers reported their failed attempt to replicate the finding using different

text: Google Earth

text: images.

text: The team released a paper of their findings dated April 27, 2007, published in the July 2007 journal Astronomy and Astrophysics. At the time of discovery, it was reported to be the first potentially Earth-like planet in the habitable zone of its star and the smallest known extrasolar planet around a main-sequence star but on April 21, 2009, another planet orbiting Gliese 581, Gliese 581 e, with an approximate mass of 1.9 Earth masses, was announced. In the paper, they also announced the discovery of another planet in the system, Gliese 581 d, with a minimum mass of 7.7 Earth masses and a semi-major axis of 0.25 astronomical units.

text: The team released a paper of their findings dated April 27, 2007, published in the July 2007 journal

text: Astronomy and Astrophysics

text: . At the time of discovery, it was reported to be the first potentially Earth-like planet in the

text: habitable zone

text: of its star and the smallest known

text: extrasolar planet

text: around a

text: main-sequence

text: star but on April 21, 2009, another planet orbiting Gliese 581,

text: Gliese 581 e

text: , with an approximate mass of 1.9 Earth masses, was announced. In the paper, they also announced the discovery of another planet in the system, Gliese 581 d, with a minimum mass of 7.7

text: Earth mass

text: es and a

text: semi-major axis

text: of 0.25

text: astronomical unit

text: s.

text: In the 2012 TV series, Zog is a soldier of the Triceraton Empire who traveled to the Earth in quest of Kraangs and alert to the Triceraton Empire to invade and destroy the planet. Due to having his equipment taken from him by the Kraang, he is left somewhat addled by the lack of nitrogen in Earth's atmosphere, allowing Raphael to pass for a commanding officer named Zoraph. Raph employs his hatred of the Kraang in an effort to take out the Kraang, only to learn that Zog is trying to summon the Triceraton armada in order to defeat the Kraang by annihilating the planet. Despite the Turtles' best efforts, Zog succeeds in sending out a signal, before apparently perishing in a fall from the Statue of Liberty's torch due to refusing to let Raphael help him back up. He is later mentioned again in the following season when-due to the Turtles traveling back in time-the events of his sending the signal are witnessed from the Triceraton side.

text: In the

entity_name: Teenage Mutant Ninja Turtles (2012 TV series)

text: 2012 TV series

text: , Zog is a soldier of the Triceraton Empire who traveled to the Earth in quest of Kraangs and alert to the Triceraton Empire to invade and destroy the planet. Due to having his equipment taken from him by the Kraang, he is left somewhat addled by the lack of nitrogen in Earth's atmosphere, allowing Raphael to pass for a commanding officer named Zoraph. Raph employs his hatred of the Kraang in an effort to take out the Kraang, only to learn that Zog is trying to summon the Triceraton armada in order to defeat the Kraang by annihilating the planet. Despite the Turtles' best efforts, Zog succeeds in sending out a signal, before apparently perishing in a fall from the

text: Statue of Liberty

text: 's torch due to refusing to let Raphael help him back up. He is later mentioned again in the following season when-due to the Turtles traveling back in time-the events of his sending the signal are witnessed from the Triceraton side.

text: The ages of characters, given in years, also imply that either they mature much more quickly than present-day humans, or that the year is much longer than 365 days (which if the planet is Mars will be the case since a Mars year is 687 Earth days).  It is said that people once lived to be twice as long as now, which makes Mars such a good fit.  There are also references to people in the past being similar in size to children; this could indicate that the lower Martian gravity has led all humans to be taller than their Earth-based ancestors.

text: When a CME impacts the Earth's magnetosphere, it temporarily deforms the Earth's magnetic field, changing the direction of compass needles and inducing large electrical ground currents in Earth itself; this is called a geomagnetic storm and it is a global phenomenon. CME impacts can induce magnetic reconnection in Earth's magnetotail (the midnight side of the magnetosphere); this launches protons and electrons downward toward Earth's atmosphere, where they form the aurora.

text: When a CME impacts the Earth's

text: magnetosphere

text: , it temporarily deforms the Earth's

text: magnetic field

text: , changing the direction of

text: compass

text: needles and inducing large electrical ground currents in Earth itself; this is called a

text: geomagnetic storm

text: and it is a global phenomenon. CME impacts can induce

text: magnetic reconnection

text: in Earth's

text: magnetotail

text: (the midnight side of the

text: magnetosphere

text: ); this launches protons and electrons downward toward Earth's atmosphere, where they form the

text: aurora

text: The star hosts one confirmed exoplanet, Kepler-452b, discovered in July 2015 by the Kepler spacecraft. This planet is mostly known for its characteristics similar to Earth, most notably its size, orbit and stellar flux. It is the first potentially rocky super-Earth planet discovered orbiting within the habitable zone of a star very similar to the Sun. It may even have a surface temperature similar to that of Earth (the planet has a equilibrium temperature of ~, and Earth's equilibrium temperature is only 10 K cooler than this). However its star is 6 billion years old (roughly 1.5 billion years older than the Sun). Due to this, Kepler-452b is receiving roughly 10% more stellar radiation than the Earth does today. If Kepler-452b is a rocky planet, it may be subject to a runaway greenhouse effect. However, because of its mass (estimated to be about 5 ), it may be able to prevent succumbing to the runaway greenhouse for a limited amount of time (at most about 500 million years). Nevertheless, the planet is one of the most Earth-like planets discovered so far by the Kepler team.

text: The star hosts one confirmed

text: exoplanet

text: , discovered in July 2015 by the

text: Kepler

text: spacecraft. This planet is mostly known for its characteristics similar to Earth, most notably its size, orbit and stellar flux. It is the first potentially rocky

text: super-Earth

text: planet discovered orbiting within the

text: habitable zone

text: of a star very similar to the

text: Sun

text: . It may even have a surface temperature similar to that of Earth (the planet has a

text: equilibrium temperature

text: of ~, and Earth's equilibrium temperature is only 10

text: K

text: cooler than this). However its star is 6 billion years old (roughly 1.5 billion years older than the Sun). Due to this, Kepler-452b is receiving roughly 10% more stellar radiation than the Earth does today. If Kepler-452b is a rocky planet, it may be subject to a

text: runaway greenhouse effect

text: . However, because of its mass (estimated to be about 5 ), it may be able to prevent succumbing to the runaway greenhouse for a limited amount of time (at most about 500 million years). Nevertheless, the planet is one of the most Earth-like planets discovered so far by the Kepler team.

text: Superior planets, dwarf planets and asteroids undergo a different cycle. After superior conjunction, such an object's elongation continues to increase until it approaches a maximum value larger than 90° (impossible with inferior planets) and typically very near 180°, which is known as opposition and corresponds to a heliocentric conjunction with Earth.  In other words, as seen from an observer on the superior planet at opposition, the Earth appears at inferior conjunction with the Sun.  Technically, the exact moment of opposition is slightly different from the moment of maximum elongation.  Opposition is defined as the moment when the apparent ecliptic longitudes of the superior planet and the Sun differ by 180°, which ignores the fact that the planet is outside the plane of the Earth's orbit.  For example, Pluto, whose orbit is highly inclined to the Earth's orbital plane, can have a maximum elongation significantly less than 180° at opposition.

text: Superior planet

text: s,

text: dwarf planet

text: s and

text: asteroid

text: s undergo a different cycle. After

text: superior conjunction

text: , such an object's elongation continues to increase until it approaches a maximum value larger than 90° (impossible with inferior planets) and typically very near 180°, which is known as

text: opposition

text: and corresponds to a

text: heliocentric

text: conjunction with Earth.  In other words, as seen from an observer on the superior planet at opposition, the Earth appears at inferior conjunction with the Sun.  Technically, the exact moment of opposition is slightly different from the moment of maximum elongation.  Opposition is defined as the moment when the apparent

text: ecliptic longitude

text: s of the superior planet and the Sun differ by 180°, which ignores the fact that the planet is outside the plane of the Earth's orbit.  For example,

text: Pluto

text: , whose orbit is highly inclined to the Earth's orbital plane, can have a maximum elongation significantly less than 180° at opposition.

text: Orbital inclination is the angle between a planet's orbital plane and another plane of reference. For exoplanets, the inclination is usually stated with respect to an observer on Earth: the angle used is that between the normal to the planet's orbital plane and the line of sight from Earth to the star. Therefore, most planets observed by the transit method are close to 90 degrees. Because the word 'inclination' is used in exoplanet studies for this line-of-sight inclination then the angle between the planet's orbit and the star's rotation must use a different word and is termed the spin–orbit angle or spin–orbit alignment. In most cases the orientation of the star's rotational axis is unknown. The Kepler spacecraft has found a few hundred multi-planet systems and in most of these systems the planets all orbit in nearly the same plane, much like the Solar System. However, a combination of astrometric and radial-velocity measurements has shown that some planetary systems contain planets whose orbital planes are significantly tilted relative to each other. More than half of hot Jupiters have orbital planes substantially misaligned with their parent star's rotation. A substantial fraction of hot-Jupiters even have retrograde orbits, meaning that they orbit in the opposite direction from the star's rotation. Rather than a planet's orbit having been disturbed, it may be that the star itself flipped early in their system's formation due to interactions between the star's magnetic field and the planet-forming disk.

text: Orbital inclination

text: is the angle between a planet's

text: orbital plane

text: and another plane of reference. For exoplanets, the inclination is usually stated with respect to an observer on Earth: the angle used is that between the

text: normal

text: to the planet's orbital plane and the line of sight from Earth to the star. Therefore, most planets observed by the

text: transit method

text: are close to 90 degrees. Because the word 'inclination' is used in exoplanet studies for this line-of-sight inclination then the angle between the planet's orbit and the star's rotation must use a different word and is termed the spin–orbit angle or spin–orbit alignment. In most cases the orientation of the star's rotational axis is unknown. The Kepler spacecraft has found a few hundred multi-planet systems and in most of these systems the planets all orbit in nearly the same plane, much like the Solar System. However, a combination of astrometric and radial-velocity measurements has shown that some planetary systems contain planets whose orbital planes are significantly tilted relative to each other. More than half of

text: hot Jupiter

text: s have orbital planes substantially misaligned with their parent star's rotation. A substantial fraction of hot-Jupiters even have

text: retrograde orbit

text: s, meaning that they orbit in the opposite direction from the star's rotation. Rather than a planet's orbit having been disturbed, it may be that the star itself flipped early in their system's formation due to interactions between the star's magnetic field and the planet-forming disk.

text: Jonas Quinn is introduced in the penultimate season 5 episode "Meridian" as a scientist of the human nation of Kelowna on Langara, a planet with an industrial level comparable to Earth of the 1940s, and that is also locked in a cold war with two rival states. He is an exceptionally quick learner, which becomes useful in memorizing SG mission reports and earth culture.  The Kelownans are experimenting with naqahdriah (an unstable but extremely powerful native element related to naqahdah) to build a bomb against their two rival nations, Terrania and the Andari Federation. Jonas is present when SG-1 team member Daniel Jackson gets radiation-poisoned with naqahdriah in an attempt to prevent a catastrophe in Kelowna, but when the Kelownan leaders respond with glee to Daniel's imminent death, Jonas steals a small amount of naqahdriah and offers it to Earth for more peaceful uses. Still wracked by guilt in the season 6 premiere "Redemption" over his hesitation to step in, Jonas helps Major Samantha Carter find a solution to save Earth from an attack by the Goa'uld Anubis. Although Colonel Jack O'Neill is reluctant to add a new fourth member to SG-1, he allows Jonas to join the team, partly to prevent a Russian from being assigned.

text: Jonas Quinn is introduced in the penultimate season 5 episode "

text: Meridian

text: " as a scientist of the human nation of Kelowna on Langara, a planet with an industrial level comparable to Earth of the 1940s, and that is also locked in a cold war with two rival states. He is an exceptionally quick learner, which becomes useful in memorizing SG mission reports and earth culture.  The Kelownans are experimenting with

text: naqahdriah

text: (an unstable but extremely powerful native element related to

text: naqahdah

text: ) to build a bomb against their two rival nations, Terrania and the Andari Federation. Jonas is present when SG-1 team member

text: Daniel Jackson

text: gets radiation-poisoned with naqahdriah in an attempt to prevent a catastrophe in Kelowna, but when the Kelownan leaders respond with glee to Daniel's imminent death, Jonas steals a small amount of naqahdriah and offers it to Earth for more peaceful uses. Still wracked by guilt in the season 6 premiere "

text: Redemption

text: " over his hesitation to step in, Jonas helps Major

text: Samantha Carter

text: find a solution to save Earth from an attack by the

text: Goa'uld

text: Anubis

text: . Although Colonel

text: Jack O'Neill

text: is reluctant to add a new fourth member to SG-1, he allows Jonas to join the team, partly to prevent a Russian from being assigned.

text: The season features a total of nine cast members over the course of the season, as one cast member is evicted and replaced, and another is replaced after he voluntarily leaves the show. It is the only season to be set in the district of Hollywood and the second season to take place in a city that has hosted a previous season, as the show's second season was set in Los Angeles in 1993. This season also makes California the most commonly used state to be used as a setting for the series. Production started from August to December 2007. The season premiered on April 16, 2008 and consisted of 13 episodes.

text: The season features a total of nine cast members over the course of the season, as one cast member is evicted and replaced, and another is replaced after he voluntarily leaves the show. It is the only season to be set in the district of

text: Hollywood

text: and the second season to take place in a city that has hosted a previous season, as the show's

text: second season

text: was set in Los Angeles in 1993. This season also makes California the most commonly used state to be used as a setting for the series. Production started from August to December 2007. The season premiered on April 16, 2008 and consisted of 13 episodes.

text: For an Earthbound observer, objects in the sky complete one revolution around the Earth in 1 day. Proxima Centauri, which is the nearest star outside the solar system, is about 4 light-years away. On a geostationary view, Proxima Centauri has a speed many times greater than c as the rim speed of an object moving in a circle is a product of the radius and angular speed. It is also possible on a geostatic view for objects such as comets to vary their speed from subluminal to superluminal and vice versa simply because the distance from the Earth varies. Comets may have orbits which take them out to more than 1000 AU. The circumference of a circle with a radius of 1000 AU is greater than one light day. In other words, a comet at such a distance is superluminal in a geostatic, and therefore non-inertial, frame.

text: For an Earthbound observer, objects in the sky complete one revolution around the Earth in 1 day.

text: Proxima Centauri

text: , which is the nearest star outside the

text: solar system

text: , is about 4

text: light-year

text: s away. On a

text: geostationary

text: view, Proxima Centauri has a speed many times greater than c as the rim speed of an object moving in a circle is a product of the radius and angular speed. It is also possible on a geostatic view for objects such as comets to vary their speed from subluminal to superluminal and vice versa simply because the distance from the Earth varies. Comets may have orbits which take them out to more than 1000

text: AU

text: . The circumference of a circle with a radius of 1000 AU is greater than one light day. In other words, a comet at such a distance is superluminal in a geostatic, and therefore non-inertial, frame.

text: If a planet's magnetic field is sufficiently strong, its interaction with the solar wind forms a magnetosphere around a planet. Early space probes discovered the gross dimensions of the terrestrial magnetic field, which extends about 10 Earth radii towards the Sun. The solar wind, a stream of charged particles, streams out and around the terrestrial magnetic field, and continues behind the magnetic tail, hundreds of Earth radii downstream. Inside the magnetosphere, there are relatively dense regions of solar wind particles, the Van Allen radiation belts.

text: If a planet's

text: magnetic field

text: is sufficiently strong, its interaction with the solar wind forms a

text: magnetosphere

text: around a planet. Early space probes discovered the gross dimensions of the terrestrial magnetic field, which extends about 10 Earth radii towards the Sun. The

text: solar wind

text: , a stream of charged particles, streams out and around the terrestrial magnetic field, and continues behind the magnetic tail, hundreds of Earth radii downstream. Inside the magnetosphere, there are relatively dense regions of solar wind particles, the

text: Van Allen radiation belt

text: s.

text: Star Blazers Season 1 is a straightforward English language adaption of the Japanese Yamato 1 television season. The plot opens in the year 2199, with planet Earth facing extinction within one year due to radioactive pollution caused by "planet bombs", the weapon of a blue-skinned, humanoid alien race known as the Gamilons. A message arrives from Queen Starsha of planet Iscandar, providing Earth with plans to build a superluminal engine and the promise that, if Earthlings can reach Iscandar, enduring what obstacles the Gamilons might put in their way, the Queen will give them a machine—the Cosmo DNA—that can neutralize the deadly radioactivity and restore the Earth's ecosystem. The challenge borne by the crew of the Yamato is to travel 148,000 light years to Iscandar and back to Earth in one Earth year.

text: Star Blazers Season 1 is a straightforward English language adaption of the Japanese

text: Yamato 1

text: television season. The plot opens in the year 2199, with planet Earth facing extinction within one year due to radioactive pollution caused by "planet bombs", the weapon of a blue-skinned, humanoid alien race known as the Gamilons. A message arrives from Queen Starsha of planet Iscandar, providing Earth with plans to build a

text: superluminal

text: engine and the promise that, if Earthlings can reach Iscandar, enduring what obstacles the Gamilons might put in their way, the Queen will give them a machine—the Cosmo DNA—that can neutralize the deadly radioactivity and restore the Earth's ecosystem. The challenge borne by the crew of the Yamato is to travel 148,000 light years to Iscandar and back to Earth in one Earth year.

text: Big Planet had been colonized hundreds of years prior to the start of the novel by misfits, faddists, cultists and anti-government advocates from Earth. It devolved into a large number of technologically backward societies, many of them ruled by petty tyrants and prey to internecine warfare. The environment is Earthlike, including the surface gravity: even though the planet is much larger than Earth (hence the name), its internal composition is much less dense.

text: The headliners were Morbid Angel and Napalm Death on the 1st night, Gwar and Deicide on the 2nd night, and Manowar and Earth Crisis on the 3rd night. It was originally supposed to be The Misfits instead of Manowar, which is why there was so much hardcore on day 3, but The Misfits canceled and they got Manowar as the replacement headliner.

text: Bonding" is a method by which all electrically conductive materials and metallic surfaces of equipment and structures, not normally intended to be energized, are effectively interconnected together via a low impedance conductive means and path in order to avoid any appreciable potential difference between any separate points. The bonded interconnections of any specific electrically conductive materials, metallic surfaces of enclosures, electrical equipment, pipes, tubes or structures via a low impedance path are completely independent and unrelated to any intended contact or connection to Earth. For example, airplanes do not have any connection to the planet Earth when they are airborne. However, it is extremely important for the safety and welfare of passengers, crew and aircraft that all metallic parts and structures of an airplane be effectively bonded together. The laboratories and satellites orbiting in space above the planet Earth obviously have no direct connection with the surface of our planet. All conductive surfaces of these orbiting laboratories and satellites, though, must be effectively bonded together to avoid differences of potential from being induced across their surfaces from the countless charged particles and magnetic waves traveling through space.

text: Obliquity, otherwise known as tilt, refers to the angle that Earth's axis of rotation makes with a line that is perpendicular to Earth's orbital plane. The current tilt of Earth's axis is roughly 23.5°. However, over long periods of time the tilt of Earth's axis of rotation changes because of the uneven distribution of mass across the planet and gravitational interactions with the Sun, Moon, and planets. Due to these interactions the tilt of Earth's axis of rotation varies between 22.2° and 24.5° on a 41,000 year cycle.

text: Obliquity, otherwise known as tilt, refers to the angle that Earth's axis of rotation makes with a line that is perpendicular to Earth's

text: orbital plane

text: . The current tilt of Earth's axis is roughly 23.5°. However, over long periods of time the tilt of Earth's axis of rotation changes because of the uneven distribution of mass across the planet and gravitational interactions with the

text: Sun

text: Moon

text: , and

text: planets

text: . Due to these interactions the tilt of Earth's axis of rotation varies between 22.2° and 24.5° on a 41,000 year cycle.

text: One of Ryan's generals, Mayo Deftinwolf, creates a plan to rid the Fence of Mariah: Coheed Kilgannon is the unknowing and unwitting carrier of a dormant virus known as the Monstar. When activated, the Monstar endows its host with the ability to destroy star transformers and separate planets from the Keywork's unifying energy beam, resulting in an apocalypse for the inhabitants of the separated planets as they smash into other astronomical bodies. Mayo plans to activate the Monstar and send Coheed and his wife, Cambria, to Paris: Earth, in hopes that the Monstar will only destroy the star transformer at Paris: Earth, thus causing Paris: Earth to break free of the Fence, ridding Wilhem of Mariah.

text: One of Ryan's generals, Mayo Deftinwolf, creates a plan to rid the Fence of Mariah: Coheed Kilgannon is the unknowing and unwitting carrier of a dormant

text: virus

text: known as the Monstar. When activated, the Monstar endows its host with the ability to destroy star transformers and separate planets from the Keywork's unifying energy beam, resulting in an apocalypse for the inhabitants of the separated planets as they smash into other astronomical bodies. Mayo plans to activate the Monstar and send Coheed and his wife, Cambria, to Paris: Earth, in hopes that the Monstar will only destroy the star transformer at Paris: Earth, thus causing Paris: Earth to break free of the Fence, ridding Wilhem of Mariah.

text: Among a handful of anthologies, the thirteen Honor-centered novels, and two subordinate sub-series starring some different characters, the universe first explored in On Basilisk Station has a diasporal historical background for the backstory storyline, in which mankind, over almost two millennia, migrated to systems beyond the Sol system, first in slower-than-light starships, then by increasingly efficient and effective hyperspace drive-propulsion systems. Early daughter colonies also spawned colonies, forming regional networks of related populations. With travel limited to slower-than-light speeds, any marginally habitable nearby planet was of interest, and Earth's scientists went through a period in which they regularly genetically modified the human genome for survival positive adaptations to marginal environments, such as heavy gravity, thin atmosphere, thick atmospheres, or toxic environments (e.g. Grayson). Some corporate entities also began breeding for super soldiers and superior intellects, good looks, sexual prowess, etc., or mixes of such traits, practices that led to a horrific "Final War" on Old Earth. Long-established and advanced daughter colonies like Beowulf mounted a variety of rescue missions and initiated a thousand-year effort to clean up the Earth gene pool. For a time, the cultural centre moved off the Earth as it took about 500 years for the planetary economy to recover its pre-eminence within its shell of highly populated, highly developed planets. Located in the centre of the spherical Solarian League, Earth's Old Chicago eventually re-emerged as the nominal League Capital.

text: Among a handful of anthologies, the thirteen Honor-centered novels, and two subordinate sub-series starring some different characters, the universe first explored in

text: On Basilisk Station

text: has a

text: diaspora

text: l historical background for the backstory

text: storyline

text: , in which mankind, over almost two millennia, migrated to systems beyond the Sol system, first in slower-than-light starships, then by increasingly efficient and effective hyperspace drive-propulsion systems. Early daughter colonies also spawned colonies, forming regional networks of related populations. With travel limited to slower-than-light speeds, any marginally habitable nearby planet was of interest, and Earth's scientists went through a period in which they regularly genetically modified the

text: human genome

text: for survival positive adaptations to marginal environments, such as heavy gravity, thin atmosphere, thick atmospheres, or toxic environments (e.g. Grayson). Some corporate entities also began breeding for super soldiers and superior intellects, good looks, sexual prowess, etc., or mixes of such traits, practices that led to a horrific "Final War" on Old Earth. Long-established and advanced daughter colonies like Beowulf mounted a variety of rescue missions and initiated a thousand-year effort to clean up the Earth gene pool. For a time, the cultural centre moved off the Earth as it took about 500 years for the planetary economy to recover its pre-eminence within its shell of highly populated, highly developed planets. Located in the centre of the spherical Solarian League, Earth's Old Chicago eventually re-emerged as the nominal League Capital.

text: Earth, alone among terrestrial planets, possesses a large moon. This is thought to confer stability to Earth's axial tilt, and thus seasons and climates. The closest analogue is the Pluto-Charon system, though its axial tilt is completely different. Both our Moon and Charon are hypothesized to have formed via giant impacts.

text: Earth, alone among terrestrial planets, possesses a large moon. This is thought to confer stability to Earth's axial tilt, and thus seasons and climates. The closest analogue is the Pluto-Charon system, though its axial tilt is completely different. Both our Moon and Charon are hypothesized to have formed via

text: giant impacts

text: Otherwise, it is suggested that if the planet had a magnetic field, it would deflect the particles from the atmosphere (even the slow rotation of a tidally locked M-dwarf planet—it spins once for every time it orbits its star—would be enough to generate a magnetic field as long as part of the planet's interior remained molten). But actual mathematical models conclude that, even under the highest attainable dynamo-generated magnetic field strengths, exoplanets with masses like that of Earth lose a significant fraction of their atmospheres by the erosion of the exobase's atmosphere by CME bursts and XUV emissions (even those Earth-like planets closer than 0.8 AU—affecting also GK stars— probably lose their atmospheres).

text: Otherwise, it is suggested that if the planet had a magnetic field, it would deflect the particles from the atmosphere (even the slow rotation of a tidally locked M-dwarf planet—it spins once for every time it orbits its star—would be enough to generate a magnetic field as long as part of the planet's interior remained molten). But actual mathematical models conclude that, even under the highest attainable dynamo-generated magnetic field strengths, exoplanets with masses like that of Earth lose a significant fraction of their atmospheres by the erosion of the exobase's atmosphere by

text: CME

text: bursts and

text: XUV

text: emissions (even those Earth-like planets closer than 0.8 AU—affecting also GK stars— probably lose their atmospheres).

text: Although populated mainly with new characters, The Headmasters did continue to feature characters from all previous seasons, including new versions of Soundwave and Blaster, rebuilt after a duel that destroyed them both as Soundblaster and Twincast. Human Daniel Witwicky and his young Autobot friend Wheelie also played major roles in the series, serving as the youthful characters for the audience to identify with. More new characters continued to pour in when Galvatron returned to leadership and the Decepticons embarked on a space voyage, ransacking planets in a chain of stories that introduced the Horrorcons and Autobot and Decepticon Clones. The return to Earth was no less momentous, as the Decepticon ninja six-changer Sixshot killed Ultra Magnus, and the Autobot Headmasters finished off Galvatron. When the Decepticons then returned to Master, refugees from the planet were caught in a plasma bomb accident that fused them to the arms of several Autobots and Decepticons, creating the Targetmasters, and in a final move, Scorponok attempted the destruction of Earth, only to be foiled, thanks in part to a traitorous Sixshot.

text: Although populated mainly with new characters, The Headmasters did continue to feature characters from all previous seasons, including new versions of

text: Soundwave

text: and

text: Blaster

text: , rebuilt after a duel that destroyed them both as Soundblaster and Twincast. Human

entity_name: List of The Transformers (TV series) characters

text: Daniel Witwicky

text: and his young Autobot friend

text: Wheelie

text: also played major roles in the series, serving as the youthful characters for the audience to identify with. More new characters continued to pour in when Galvatron returned to leadership and the Decepticons embarked on a space voyage, ransacking planets in a chain of stories that introduced the

text: Horrorcons

text: and

text: Autobot

text: and Decepticon Clones. The return to Earth was no less momentous, as the Decepticon ninja six-changer

text: Sixshot

text: killed Ultra Magnus, and the Autobot Headmasters finished off Galvatron. When the Decepticons then returned to Master, refugees from the planet were caught in a plasma bomb accident that fused them to the arms of several Autobots and Decepticons, creating the Targetmasters, and in a final move, Scorponok attempted the destruction of Earth, only to be foiled, thanks in part to a traitorous Sixshot.

text: Since definitions of left and right based on the geometry of the natural environment are unwieldy, in practice, the meaning of relative direction words is conveyed through tradition, acculturation, education, and direct reference. One common definition of up and down uses gravity and the planet Earth as a frame of reference. Since there is a very noticeable force of gravity acting between the Earth and any other nearby object, down is defined as that direction which an object moves in reference to the Earth when the object is allowed to fall freely. Up is then defined as the opposite direction of down.  Another common definition uses a human body, standing upright, as a frame of reference. In that case, up is defined as the direction from feet to head, perpendicular to the surface of the Earth. In most cases, up is a directionally oriented position generally opposite to that of the pull of gravity.

text: Since definitions of left and right based on the geometry of the natural environment are unwieldy, in practice, the meaning of relative direction words is conveyed through

text: tradition

text: acculturation

text: education

text: , and direct reference. One common definition of up and down uses

text: gravity

text: and the

text: planet Earth

text: as a frame of reference. Since there is a very noticeable force of gravity acting between the Earth and any other nearby object, down is defined as that direction which an object moves in reference to the Earth when the object is allowed to

text: fall freely

text: . Up is then defined as the opposite direction of down.  Another common definition uses a human body, standing upright, as a frame of reference. In that case, up is defined as the direction from feet to head, perpendicular to the surface of the Earth. In most cases, up is a directionally oriented position generally opposite to that of the pull of gravity.

text: This is a list of geological features on Venus. Venus is the second planet from the Sun. Venus is classified as a terrestrial planet and it is sometimes called Earth's "sister planet" owing to their similar size, gravity, and bulk composition (Venus is both the closest planet to Earth and the planet closest in size to Earth). The surface of Venus is covered by a dense atmosphere and presents clear evidence of former violent volcanic activity. It has shield and composite volcanoes similar to those found on Earth.

text: This is a list of

text: geological features

text: on

text: Venus

text: . Venus is the second planet from the Sun. Venus is classified as a

text: terrestrial planet

text: and it is sometimes called Earth's "sister planet" owing to their similar size, gravity, and bulk composition (Venus is both the closest planet to Earth and the planet closest in size to Earth). The surface of Venus is covered by a dense atmosphere and presents clear evidence of former violent volcanic activity. It has shield and composite volcanoes similar to those found on Earth.

text: Towards the end of the first season of Star Trek: The Next Generation, staff members convinced Gene Roddenberry to drop Gates McFadden as Dr. Beverly Crusher from the show. Executive producer Rick Berman opposed this decision. To allow for McFadden's return in the future, Roddenberry wrote Crusher's character out rather than killing her. McFadden's departure led to an opening for a new cast member.  The producers contacted American actress Diana Muldaur, unaware of her past involvement with  Roddenberry's Star Trek and Planet Earth pilot.  In The Original Series, Muldaur played the role of a doctor in two episodes: as Dr. Ann Mulhall in "Return to Tomorrow", and as Dr. Miranda Jones in "Is There in Truth No Beauty?" Muldaur also worked on the pilot for Planet Earth after getting to know Roddenberry and his wife, Majel Barrett, through their annual Star Trek Christmas parties.

text: Towards the end of the first season of

text: Star Trek: The Next Generation

text: , staff members convinced

text: Gene Roddenberry

text: to drop

text: Gates McFadden

text: as Dr.

text: Beverly Crusher

text: from the show. Executive producer

text: Rick Berman

text: opposed this decision. To allow for McFadden's return in the future, Roddenberry wrote Crusher's character out rather than killing her. McFadden's departure led to an opening for a new cast member.  The producers contacted American actress Diana Muldaur, unaware of her past involvement with  Roddenberry's

text: Star Trek

text: and

text: Planet Earth

text: pilot.  In

text: The Original Series

text: , Muldaur played the role of a doctor in two episodes: as Dr. Ann Mulhall in "

text: Return to Tomorrow

text: ", and as Dr. Miranda Jones in "

text: Is There in Truth No Beauty?

text: " Muldaur also worked on the pilot for Planet Earth after getting to know Roddenberry and his wife,

text: Majel Barrett

text: , through their annual Star Trek Christmas parties.

text: The first season consisted of 20 episodes and premiered on 17 March 2008 and the finale aired on 11 April 2008.The 2nd season premiered on 1 September 2008 with the finale airing on 19 December 2008.The second season consisted of 80 episodes. The 3rd season premiered on 2 March 2009 with the finale airing on 5 June 2009. The third season consisted of 65 episodes. The 4th season premiered on 31 August 2009 with the finale on 13 November 2009.It is not known if a 5th season is being made.

text: Fischer has co-authored over 100 papers on dwarf stars and sub-stellar mass objects in the galactic neighborhood, including many on extrasolar planets. She is a principal investigator with the N2K Consortium searching for exoplanets. She is also a member of the planet search team led by Geoffrey Marcy looking for extrasolar planets.  She was the primary investigator for Chiron, the CTIO High Resolution Spectrometer.  In 2011, she started the Fiber-optic Improved Next-generation Doppler Search for Exo-Earths with the Planetary Society, an instrument that will help planet hunters find Earth-like extrasolar planets.

text: Fischer has co-authored over 100

text: papers

text: on

text: dwarf star

text: s and sub-stellar mass objects in the galactic neighborhood, including many on extrasolar planets. She is a principal investigator with the

text: N2K Consortium

text: searching for

text: exoplanet

text: s. She is also a member of the planet search team led by

text: Geoffrey Marcy

text: looking for

text: extrasolar planet

text: s.  She was the primary investigator for Chiron, the

text: CTIO

text: High Resolution Spectrometer.  In 2011, she started the

entity_name: Fiber-optic Improved Next-generation Doppler Search for Exo-Earths

text: Fiber-optic Improved Next-generation Doppler Search for Exo-Earths

text: with

text: the Planetary Society

text: , an instrument that will help planet hunters find Earth-like extrasolar planets.

text: In fact, a ball falling from such a height wouldn't fall behind but ahead of the vertical because the rotational motion would be in ever-decreasing circles. What makes the earth move is similar to whatever moves Mars or Jupiter and is the same as that which pulls the stone to earth. Calling it gravity doesn't explain what it is.

text: In fact, a ball falling from such a height wouldn't fall behind but ahead of the vertical because the rotational motion would be in ever-decreasing circles. What makes the earth move is similar to whatever moves Mars or Jupiter and is the same as that which pulls the stone to earth. Calling it

text: gravity

text: doesn't explain what it is.

text: Earth science – the science of the planet Earth,  the only identified life-bearing planet. Its studies include the following:

text: Earth science

text: – the

text: science

text: of the planet

text: Earth

text: ,  the only identified

text: life-bearing planet

text: . Its studies include the following:

text: for the dust. This optical depth means that the total cross section of all particles inside the ring is about 5000 km². The particles in the main ring are expected to have aspherical shapes. The total mass of the dust is estimated to be 10−10 kg. The mass of large bodies, excluding Metis and Adrastea, is 10−10 kg. It depends on their maximum size— the upper value corresponds to about 1 km maximum diameter. These masses can be compared with masses of Adrastea, which is about 2 kg, Amalthea, about 2 kg, and Earth's Moon, 7.4 kg.

text: for the dust. This

text: optical depth

text: means that the total cross section of all particles inside the ring is about 5000 km². The particles in the main ring are expected to have aspherical shapes. The total mass of the dust is estimated to be 10−10 kg. The mass of large bodies, excluding Metis and Adrastea, is 10−10 kg. It depends on their maximum size— the upper value corresponds to about 1 km maximum diameter. These masses can be compared with masses of Adrastea, which is about 2 kg, Amalthea, about 2 kg, and Earth's

text: Moon

text: , 7.4 kg.

text: For thousands of years, an alliance has existed between 11 alien planets collectively referred to as "The Quorat". The inhabitants of each planet possess various supernatural abilities. About fifteen years prior to the events of Stirring the Storm, the Quorat felt it was time to integrate a twelfth planet into their alliance, and after surveying many potential worlds, they eventually chose Earth. However, they realized that the human race was still to closed-minded to communicate with them on a proper level, and that if they were to simply arrive on Earth and introduce themselves, they would be greeted with fear and distrust. Therefore, they decided to send ambassadors to Earth, in order to gradually introduce humanity to some of the powers that they possessed, and broaden the minds of their soon-to-be-allies. To this end, several female inhabitants of each Quorat planet were sent to Earth and settled in Britain (chosen for its isolation as an island and because its people were viewed as being among the most tolerant the world had to offer). These women were referred to as "Seeders", and were sent to Earth via an interplanetary 'corridor', activated by a key called a 'cleftonique'. Their arrival resulted in what was referred to as a 'cleftonique aftershock', which disrupted the atmospheric patterns in the vicinity, causing strange weather phenomena. The goal of each Seeder was to find an intelligent human male to marry and mate with, the result of each such union being a COLA child. The birth of these children caused another cleftonique aftershock. However, living on another planet puts one into contact with all sorts of unfamiliar viruses, and prolonged exposure ultimately proves fatal. Females had been chosen because they would be more resistant to such problems, but the physical changes brought about by pregnancy weakened their immune systems. Therefore, all of the Seeder women fell ill and died from various natural illnesses within four years of giving birth. The human father's immunity would be passed on to the child.

text: For thousands of years, an alliance has existed between 11 alien planets collectively referred to as "The Quorat". The inhabitants of each planet possess various supernatural abilities. About fifteen years prior to the events of Stirring the Storm, the Quorat felt it was time to integrate a twelfth planet into their alliance, and after surveying many potential worlds, they eventually chose

text: Earth

text: . However, they realized that the human race was still to closed-minded to communicate with them on a proper level, and that if they were to simply arrive on Earth and introduce themselves, they would be greeted with fear and distrust. Therefore, they decided to send

text: ambassador

text: s to Earth, in order to gradually introduce humanity to some of the powers that they possessed, and broaden the minds of their soon-to-be-allies. To this end, several female inhabitants of each Quorat planet were sent to Earth and settled in

text: Britain

text: (chosen for its isolation as an

text: island

text: and because its people were viewed as being among the most tolerant the world had to offer). These women were referred to as "Seeders", and were sent to Earth via an interplanetary 'corridor', activated by a key called a 'cleftonique'. Their arrival resulted in what was referred to as a 'cleftonique aftershock', which disrupted the atmospheric patterns in the vicinity, causing strange weather phenomena. The goal of each Seeder was to find an intelligent human male to marry and mate with, the result of each such union being a COLA child. The birth of these children caused another cleftonique aftershock. However, living on another planet puts one into contact with all sorts of unfamiliar

text: virus

text: es, and prolonged exposure ultimately proves fatal. Females had been chosen because they would be more resistant to such problems, but the physical changes brought about by

text: pregnancy

text: weakened their

text: immune systems

text: . Therefore, all of the Seeder women fell ill and died from various natural illnesses within four years of giving birth. The human father's immunity would be passed on to the child.

text: Gliese 832 c has a mass of approximately 5.2 times that of Earth. If it had the same density of Earth it would have a radius of around 1.75  or possibly the planet could have a higher density with a smaller radius.  Its temperature is predicted to be relatively similar to Earth's, but is subject to significant swings as it orbits its star. The planet has a relatively high eccentricity, taking it very near to the predicted inner edge of the habitable zone. The planet's average equilibrium temperature is predicted to be , but is estimated to vary from  at apoastron to  at periastron. However, because of its large mass, it may have a dense atmosphere, which could make it much hotter and more like the planet Venus.

text: Gliese 832 c has a mass of approximately 5.2 times that of

text: Earth

text: . If it had the same density of Earth it would have a radius of around 1.75  or possibly the planet could have a higher density with a smaller radius.  Its temperature is predicted to be relatively similar to Earth's, but is subject to significant swings as it orbits its star. The planet has a relatively high

text: eccentricity

text: , taking it very near to the predicted inner edge of the habitable zone. The planet's average equilibrium temperature is predicted to be , but is estimated to vary from  at apoastron to  at periastron. However, because of its large mass, it may have a dense atmosphere, which could make it much hotter and more like the planet

text: Venus

text: However Burch believes Aristotle was having a joke "at the expense of Pythagorean number theory", and that the true purpose of the Counter-Earth was to "balance" Philolaus' cosmos—balance being needed because without a counter there would be only one dense, massive object in the system—Earth.  Although his system had both the Earth and the Planets orbiting a single point, the ancient Greeks did not consider Earth a "planet". In the time before Galileo could observe from his telescope that planets were spheres like Earth, they were thought to be different from stars only in brightness and in their motion, and like stars composed of a fiery or ethereal matter having little or no density. However, the Earth was obviously made of the dense elements of earth and water. According to Burch,

text: However Burch believes Aristotle was having a joke "at the expense of Pythagorean number theory", and that the true purpose of the Counter-Earth was to "balance" Philolaus' cosmos—balance being needed because without a counter there would be only one dense, massive object in the system—Earth.  Although his system had both the Earth and the Planets orbiting a single point, the

text: ancient Greeks

text: did not consider Earth a "planet". In the time before

text: Galileo

text: could observe from his telescope that planets were spheres like Earth, they were thought to be different from stars only in brightness and in their motion, and like stars composed of a fiery or ethereal matter having little or no density. However, the Earth was obviously made of the dense

text: elements

text: of earth and water. According to Burch,

text: Night and Day is a novel by Virginia Woolf first published on 20 October 1919. Set in Edwardian London, Night and Day contrasts the daily lives and romantic attachments of two acquaintances, Katharine Hilbery and Mary Datchet. The novel examines the relationships between love, marriage, happiness, and success.

text: Night and Day is a novel by

text: Virginia Woolf

text: first published on 20 October 1919. Set in

text: Edwardian

text: London, Night and Day contrasts the daily lives and romantic attachments of two acquaintances,

text: Katharine Hilbery

text: and

text: Mary Datchet

text: . The novel examines the relationships between love, marriage, happiness, and success.

text: Humans from Earth colonize the Spacer and, later, Settler planets; an anti-Earth plot causes the planet's crust to become radioactive, greatly reducing its population. Many small empires rise and fall throughout the Milky Way Galaxy as various worlds trade with and fight each other. Over time one planet, Trantor, founds a true Galactic Empire. By then Earth is only one of millions of member worlds, and the radioactivity makes it a quarantined backwater; by 827 G.E. (Galactic Era, the number of years after the empire's founding), the setting of Pebble in the Sky, only 20 million people live on Earth. Most non-Earthlings are skeptical of the scholarly theory that the obscure planet is the original home of all humans, believing that humans evolved on many planets simultaneously. By 12000 G.E., the setting of the Foundation series, although many believe that humanity originated on one planet, Earth is one of several candidates.

text: Humans from Earth colonize the Spacer and, later, Settler planets; an anti-Earth plot causes the planet's crust to become radioactive, greatly reducing its population. Many small empires rise and fall throughout the

text: Milky Way Galaxy

text: as various worlds trade with and fight each other. Over time one planet,

text: Trantor

text: , founds a true

text: Galactic Empire

text: . By then Earth is only one of millions of member worlds, and the radioactivity makes it a quarantined backwater; by 827 G.E. (Galactic Era, the number of years after the empire's founding), the setting of

text: Pebble in the Sky

text: , only 20 million people live on Earth. Most non-Earthlings are skeptical of the scholarly theory that the obscure planet is the original home of all humans, believing that humans

text: evolved on many planets simultaneously

text: . By 12000 G.E., the setting of the Foundation series, although many believe that humanity originated on one planet, Earth is one of several candidates.

text: Frustrated, Jor-El continued his work on space travel on his own, hoping to build a spacecraft to save his own family. This work included launching several smaller test rockets; one of these rockets included the family dog, who responded to the name of "Krypto." However, as time ran short, Jor-El soon found that he would only have enough time to build a spacecraft to save his son Kal-El. He decided to send Kal-El to Earth, realizing he would gain superhuman powers under Earth's more intense yellow sun and lower gravity. As Krypton finally went through its final destructive stages, Jor-El and Lara placed their son in the rocket and launched him toward Earth, before they themselves were killed along with almost all the rest of the planet's population. Lara could have fit inside the rocket as well, but she chose to stay behind to increase Kal-El's chances of reaching Earth.

text: Frustrated, Jor-El continued his work on space travel on his own, hoping to build a spacecraft to save his own family. This work included launching several smaller test rockets; one of these rockets included the family

text: dog

text: , who responded to the name of "

text: Krypto

text: ." However, as time ran short, Jor-El soon found that he would only have enough time to build a spacecraft to save his son Kal-El. He decided to send Kal-El to Earth, realizing he would gain superhuman powers under Earth's more intense yellow

text: sun

text: and lower

text: gravity

text: . As Krypton finally went through its final destructive stages, Jor-El and Lara placed their son in the rocket and launched him toward Earth, before they themselves were killed along with almost all the rest of the planet's population. Lara could have fit inside the rocket as well, but she chose to stay behind to increase Kal-El's chances of reaching Earth.

text: Bellows is known for his first motion picture role as Tommy in The Shawshank Redemption (1994). Also in 1994, he played the lead role Watty Watt in Love and a .45 with Renée Zellweger, as CIA agent Matt Callan in the television series The Agency and as Billy Thomas in the television series Ally McBeal. Bellows also appeared in the psychological thriller Chasing Sleep as Detective Derm, opposite star Jeff Daniels. He appeared in The Weather Man as a perverted rehabilitation counsellor. He was in the films Black Day Blue Night, Snow White: A Tale Of Terror, as Will, and Un amour de sorcière, a French film, as Michael Firth (1997).He has appeared on the Hallmark Channel original film Final Days of Planet Earth and the Canadian television series Terminal City.

text: Bellows is known for his first

text: motion picture

text: role as Tommy in

text: The Shawshank Redemption

text: (1994). Also in 1994, he played the lead role Watty Watt in

text: Love and a .45

text: with

text: Renée Zellweger

text: , as

text: CIA

text: agent Matt Callan in the television series

text: The Agency

text: and as Billy Thomas in the television series

text: Ally McBeal

text: . Bellows also appeared in the

text: psychological thriller

text: Chasing Sleep

text: as Detective Derm, opposite star

text: Jeff Daniels

text: . He appeared in

text: The Weather Man

text: as a perverted rehabilitation counsellor. He was in the films

text: Black Day Blue Night

text: Snow White: A Tale Of Terror

text: , as Will, and Un amour de sorcière, a French film, as Michael Firth (1997).He has appeared on the

text: Hallmark Channel

text: original film

text: Final Days of Planet Earth

text: and the Canadian television series

text: Terminal City

text: Kepler-11c is an exoplanet discovered in the orbit of the Sun-like star Kepler-11 by the Kepler spacecraft, a NASA telescope aiming to discover Earth-like planets. It is the second planet from its star, and is most likely a water planet with a thin hydrogen–helium atmosphere. Kepler-11c orbits Kepler-11 every 10 days, and has an estimated density twice that of pure water. It is estimated to have a mass thirteen times that of Earth and a radius three times that of Earth. Kepler-11c and its five sister planets form the first discovered system with more than three transiting planets. The Kepler-11 system also holds the record of being the most compact and the flattest system discovered. Kepler-11c and the other Kepler-11 planets were announced to the public on February 2, 2011, and was published in Nature a day later.

text: Kepler-11c is an

text: exoplanet

text: discovered in the orbit of the

text: Sun

text: -like

text: star

text: by the

text: Kepler spacecraft

text: , a

text: NASA

text: telescope aiming to discover

text: Earth-like planets

text: . It is the second planet from its star, and is most likely a

text: water planet

text: with a thin hydrogen–helium atmosphere. Kepler-11c orbits Kepler-11 every 10 days, and has an estimated density twice that of pure water. It is estimated to have a mass thirteen times that of Earth and a radius three times that of Earth. Kepler-11c and its five sister planets form the first discovered system with more than three transiting planets. The Kepler-11 system also holds the record of being the most compact and the flattest system discovered. Kepler-11c and the other Kepler-11 planets were announced to the public on February 2, 2011, and was published in

text: Nature

text: a day later.

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: A magnetosphere is produced by the interaction of a stream of charged particles, such as solar wind, with a planet's (or similar body's) magnetic field. All planets with intrinsic magnetic fields, including Earth, are surrounded by a magnetosphere.

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: 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: In the science fiction television series Stargate SG-1 and its sequels, several types of starships are introduced in the later seasons. In the series, they are the product of several years' worth of research into alien technologies discovered on off-world missions to other planets visited via the stargate. The stargate is an alien device discovered on Earth that allows near instantaneous travel to other planets via a controlled wormhole across a network of similar gates. The stargate was created by an extinct race called the Ancients, but are in use by aliens, some of which use both stargate and starship travel. Some of these alien races are hostile to Earth and bent on galaxy-wide domination, so Earth starships are built by the US military through billions of dollars in secret funding to respond to the threat.

text: In the

text: science fiction

text: television series

text: Stargate SG-1

text: and its sequels, several types of

text: starship

text: s are introduced in the later seasons. In the series, they are the product of several years' worth of research into alien technologies discovered on off-world missions to other planets visited via the

text: stargate

text: . The

text: stargate

text: is an alien device discovered on Earth that allows near instantaneous travel to other planets via a controlled

text: wormhole

text: across a network of similar gates. The

text: stargate

text: was created by an extinct race called the Ancients, but are in use by aliens, some of which use both

text: stargate

text: and

text: starship

text: travel. Some of these alien races are hostile to Earth and bent on galaxy-wide domination, so Earth

text: starship

text: s are built by the US military through billions of dollars in secret funding to respond to the threat.

text: The Earth's rotation axis moves with respect to the fixed stars (inertial space); the components of this motion are precession and nutation. It also moves with respect to the Earth's crust; this is called polar motion.

text: The Earth's rotation axis moves with respect to the fixed stars (

text: inertial space

text: ); the components of this motion are

text: precession

text: and

text: nutation

text: . It also moves with respect to the Earth's crust; this is called

text: polar motion

text: Seasons typically run from November to February and include a 12-round regular season and an end-of-season finals series playoff tournament involving the highest-placed teams, culminating in a grand final match. The winner of the regular season tournament is dubbed 'premier' and the winner of the grand final is 'champion'. Since the league's inaugural season, a total of four clubs have been crowned W-League Premiers and four clubs have been crowned W-League Champions.

text: Seasons typically run from November to February and include a 12-round

text: regular season

text: and an end-of-season finals series

text: playoff

text: tournament involving the highest-placed teams, culminating in a grand final match. The winner of the regular season tournament is dubbed 'premier' and the winner of the grand final is 'champion'. Since the league's

text: inaugural season

text: , a total of four clubs have been crowned W-League Premiers and four clubs have been crowned W-League Champions.

text: NGTS is designed to fill the current gap between Earth-sized planets and gas giants. Although other ground-based surveys could only detect larger, Jupiter-sized exoplanets, Keplers Earth-sized planets are often too far away or orbit stars too dim to allow for doppler spectroscopy—a different detection method to determine the planet's mass by the wobble of its host star. NGTS's wider field of view enables it to detect a larger number of more-massive planets around brighter stars. With a detailed follow-up characterization by larger instruments such as HARPS, ESPRESSO and VLT-SPHERE, it will be possible to measure the mass of a large number of targets using this wobble method. This makes it possible to determine the exoplanet's density, and hence whether it is gaseous or rocky.

text: NGTS is designed to fill the current gap between Earth-sized planets and

text: gas giant

text: s. Although other ground-based surveys could only detect larger, Jupiter-sized exoplanets, Keplers Earth-sized planets are often too far away or orbit stars too dim to allow for

text: doppler spectroscopy

text: —a different detection method to determine the planet's mass by the wobble of its host star. NGTS's wider field of view enables it to detect a larger number of more-massive planets around brighter stars. With a detailed follow-up characterization by larger instruments such as

text: HARPS

text: ESPRESSO

text: and

entity_name: Spectro-Polarimetric High-Contrast Exoplanet Research

text: VLT-SPHERE

text: , it will be possible to measure the mass of a large number of targets using this wobble method. This makes it possible to determine the exoplanet's density, and hence whether it is gaseous or rocky.

text: In 2014, new measurements of Kepler-10c found that it is a Neptune-mass planet (17 Earth masses) with a density higher than Earth's, indicating that Kepler-10c is composed mostly of rock with possibly up to 20% high-pressure water ice but without a hydrogen-dominated envelope. Because this is well above the 10-Earth-mass upper limit that is commonly used for the term 'super-Earth', the term mega-Earth has been coined. A similarly massive and dense planet could be Kepler-131b, although its density is not as well measured as that of Kepler 10c. The next most massive known solid planets are half this mass: 55 Cancri e and Kepler-20b.

text: In 2014, new measurements of

text: found that it is a Neptune-mass planet (17 Earth masses) with a density higher than Earth's, indicating that Kepler-10c is composed mostly of rock with possibly up to 20% high-pressure water ice but without a hydrogen-dominated envelope. Because this is well above the 10-Earth-mass upper limit that is commonly used for the term 'super-Earth', the term

text: mega-Earth

text: has been coined. A similarly massive and dense planet could be

text: , although its density is not as well measured as that of Kepler 10c. The next most massive known solid planets are half this mass:

text: 55 Cancri e

text: and

text: Venus and Mars do not have a planetary magnetic field and do not have a magnetopause.  The solar wind interacts with the planet’s atmosphere  and a void is created behind the planet.  In the case of the Earth’s moon and other bodies without a magnetic field or atmosphere, the body’s surface interacts with the solar wind and a void is created behind the body.

text: A day and night camera is a security camera that can see the picture during the day hours, when there is enough sunlight, and during the night in total darkness or minimum illumination. A day and night camera has special lenses that allow infrared emission produced by infrared LEDs and reflected from objects to go through and reach a CCD or CMOS chip inside the camera. As a result, the end user can see picture in total darkness at the distance of infrared emission produced by LEDs. A day and night camera can have infrared LEDs mounted on its housing or can accept the emission, produced by an infrared turret. Day and night cameras often have modifications in their digital signal processor (DSP) that compensates for the difference in illumination between day and night modes. HDR technology may also be used in more expensive models to compensate for the difference in illumination between shaded and lighted areas of surveillance.

text: A day and night camera is a

text: security camera

text: that can see the picture during the day hours, when there is enough sunlight, and during the night in total darkness or minimum

text: illumination

text: . A day and night camera has special lenses that allow

text: infrared

text: emission produced by infrared

text: LED

text: s and reflected from objects to go through and reach a CCD or CMOS chip inside the camera. As a result, the end user can see picture in total darkness at the distance of infrared emission produced by LEDs. A day and night camera can have infrared LEDs mounted on its housing or can accept the emission, produced by an infrared turret. Day and night cameras often have modifications in their

text: digital signal processor

text: (DSP) that compensates for the difference in illumination between day and night modes.

text: HDR

text: technology may also be used in more expensive models to compensate for the difference in illumination between shaded and lighted areas of surveillance.

text: Alisa Seleznyova, her father professor Seleznyov, and the ship's captain Zeleniy are travelling in space on the Pegasus. Zeleniy is unhappy that Alisa has brought a frog on board as he insists on keeping the ship clean, however Alisa insists that the frog is in fact a princess under a curse. They meet their old friend alien archaeologist Gromozeka, who's just discovered an empty space ship called Black Wanderer all inhabitants of which died. Upon investigation of the Black Wanderer they find video evidence that the Black Wanderer was inhabited by Space Pirates, who attacked entire planets at a time to loot their resources. Since they lacked the manpower to physically take over an entire planet they would instead send ahead a scouting ship which would plant a lilac ball on the planet. Lilac balls were storage units for the virus of hate, which would cause all who were infected to attack each other. When the Black Wanderer would get near the planet, the lilac ball would disperse the virus, causing the inhabitants of the planet to wipe themselves out, allowing the space pirates to loot the planet unopposed. At some point, a slave that labored in the Black Wanderer sacrificed himself and broke a lilac ball, which caused the space pirates to wipe themselves out. The deserted ship was left floating on autopilot towards the pirates' next target: Earth. Gromozeka discovers that they had left a lilac ball on Earth 26000 years ago, and that the Black Wanderer will be close enough to Earth to make the lilac ball start dispersing within 10 days. The crew races back towards Earth on the Pegasus at hyperspeed. They enter Earth's orbit and attempt to notify flight control that they've discovered an alien virus, but due to a misunderstanding flight control sends a quarantine ship after them which traps them, leaving them helpless.

text: It is a super-Earth, meaning it is larger than Earth but is significantly smaller (in mass and radius) than the gas giants of the Solar System. After COROT-7b, it was the second super-Earth to be known and is the first of a new class of planets with small size and relatively low density. GJ 1214 b is also significant because its parent star is relatively near the Sun and because it transits (crosses in front of) that parent star, which allows the planet's atmosphere to be studied using spectroscopic methods.

text: It is a

text: super-Earth

text: , meaning it is larger than

text: Earth

text: but is significantly smaller (in mass and radius) than the

text: gas giant

text: s of the

text: Solar System

text: . After

text: , it was the second super-Earth to be known and is the first of a new class of planets with small size and relatively low density. GJ 1214 b is also significant because its parent star is relatively near the

text: Sun

text: and because it

text: transits

text: (crosses in front of) that parent star, which allows the planet's atmosphere to be studied using

text: spectroscopic methods

text: A mega-Earth is a massive terrestrial exoplanet that is at least ten times the mass of Earth. Mega-Earths are substantially more massive than super-Earths (terrestrial and ocean planets with masses around 5–10 Earths). The term "mega-Earth" was first coined in 2014, when Kepler-10c was revealed to be a Neptune-mass planet with a density considerably greater than that of Earth.

text: A mega-Earth is a massive terrestrial exoplanet that is at least ten times the mass of Earth. Mega-Earths are substantially more massive than

text: super-Earth

text: s (terrestrial and ocean planets with masses around 5–10 Earths). The term "mega-Earth" was first coined in 2014, when

text: was revealed to be a Neptune-mass planet with a density considerably greater than that of Earth.

text: Planetary habitability of red dwarf systems is subject to some debate. In spite of their great numbers and long lifespans, there are several factors which may make life difficult on planets around a red dwarf. First, planets in the habitable zone of a red dwarf would be so close to the parent star that they would likely be tidally locked. This would mean that one side would be in perpetual daylight and the other in eternal night. This could create enormous temperature variations from one side of the planet to the other. Such conditions would appear to make it difficult for forms of life similar to those on Earth to evolve. And it appears there is a great problem with the atmosphere of such tidally locked planets: the perpetual night zone would be cold enough to freeze the main gases of their atmospheres, leaving the daylight zone nude and dry. On the other hand, recent theories propose that either a thick atmosphere or planetary ocean could potentially circulate heat around such a planet. Alternatively, a moon in orbit around a gas giant may be habitable. It would circumvent the tidal lock problem with its star by becoming tidally locked to its planet. In this manner there would be a day/night cycle as the moon orbited its primary, and hence a more uniform distribution of heat.

text: Planetary habitability

text: of red dwarf systems is subject to some debate. In spite of their great numbers and long lifespans, there are several factors which may make life difficult on planets around a red dwarf. First, planets in the habitable zone of a red dwarf would be so close to the parent star that they would likely be

text: tidally locked

text: . This would mean that one side would be in perpetual daylight and the other in eternal night. This could create enormous temperature variations from one side of the planet to the other. Such conditions would appear to make it difficult for forms of life similar to those on Earth to evolve. And it appears there is a great problem with the atmosphere of such tidally locked planets: the perpetual night zone would be cold enough to freeze the main gases of their atmospheres, leaving the daylight zone nude and dry. On the other hand, recent theories propose that either a thick atmosphere or planetary ocean could potentially circulate heat around such a planet. Alternatively, a moon in orbit around a gas giant may be habitable. It would circumvent the tidal lock problem with its star by becoming tidally locked to its planet. In this manner there would be a day/night cycle as the moon orbited its primary, and hence a more uniform distribution of heat.

text: In September 2012, astronomers using the HARPS instrument announced the discovery of two planets orbiting Gliese 163. One planet, Gliese 163 c, with an orbital period of 26 days, and a minimum mass of 7.2 Earth masses, was considered potentially in the habitable zone, although hotter than Earth. A second planet, Gliese 163 b, was also announced, with a period of 1 day. It would be too hot to be considered habitable. Evidence was also found for a third planet orbiting further out than c and b. In June 2013, it was concluded that at least 3 planets orbit around the star with fourth planet being a possibility.

text: In September 2012, astronomers using the

text: HARPS

text: instrument announced the discovery of two planets orbiting Gliese 163. One planet,

text: Gliese 163 c

text: , with an orbital period of 26 days, and a minimum mass of 7.2 Earth masses, was considered potentially in the

text: habitable zone

text: , although hotter than Earth. A second planet, Gliese 163 b, was also announced, with a period of 1 day. It would be too hot to be considered habitable. Evidence was also found for a third planet orbiting further out than c and b. In June 2013, it was concluded that at least 3 planets orbit around the star with fourth planet being a possibility.

text: Earth mass (, where ⊕ is the standard astronomical symbol for planet Earth) is the unit of mass equal to that of Earth. This value includes the atmosphere but excludes the moon. The current best estimate for Earth mass is Earth mass is a standard unit of mass in astronomy that is used to indicate the masses of other planets, including rocky terrestrial planets and exoplanets.

text: Earth mass (, where ⊕ is the standard astronomical symbol for planet

text: Earth

text: ) is the unit of

text: mass

text: equal to that of Earth. This value includes the atmosphere but excludes the moon. The current best estimate for Earth mass is Earth mass is a standard

text: unit of mass

text: in

text: astronomy

text: that is used to indicate the masses of other

text: planet

text: s, including rocky

text: terrestrial planet

text: s and

text: exoplanet

text: s.

text: The game takes place primarily on Earth and an alternate version of the planet known as Bizarro Earth. The two planets and their residents are linked in a manner such that when someone on Earth experiences something their Bizarro Earth counterpart experiences a similar event, and vice versa. Floating above Bizarro Earth is a space station called the Hero Training Facility, which is maintained by the World Hero Society. At the Facility, heroes are trained by travelling through dungeons on Bizarro Earth and solving the personal problems of the local residents, thus preventing potential disasters on Earth.

text: Several species of sharks have demonstrated the ability to sense magnetic fields (Kalmijn, 1978; Ryan, 1980; Klimley, 1993; 2002). The Ampullae of Lorenzini organ within sharks is used to detect weak electrical fields at short ranges. The detection range of this organ is effective only within inches, as sharks sense bioelectrical fields in the final stages of prey capture. The  flux per unit area of certain permanent magnets, particularly Neodymium-Iron-Boride and Barium-Ferrite magnets, corresponds closely with the detection range of the Ampullae of Lorenzini. The fields generated by these permanent magnets (ferrite and rare-earth types) decrease at the inverse cube of the distance from the magnet to sharks and rays. Therefore, at distances of a few meters from the magnet, the field exerted is less than the Earth's magnetic field. Animals which lack that Ampullae of Lorenzini organ do not display aversive behavior in close proximity to the magnetic field, making this technology selective.

text: Several species of sharks have demonstrated the ability to sense magnetic fields (Kalmijn, 1978; Ryan, 1980; Klimley, 1993; 2002). The Ampullae of Lorenzini organ within sharks is used to detect weak electrical fields at short ranges. The detection range of this organ is effective only within inches, as sharks sense bioelectrical fields in the final stages of prey capture. The  flux per unit area of certain permanent magnets, particularly Neodymium-Iron-Boride and Barium-Ferrite magnets, corresponds closely with the detection range of the

text: Ampullae of Lorenzini

text: . The fields generated by these permanent magnets (ferrite and rare-earth types) decrease at the inverse cube of the distance from the magnet to sharks and rays. Therefore, at distances of a few meters from the magnet, the field exerted is less than the Earth's magnetic field. Animals which lack that Ampullae of Lorenzini organ do not display aversive behavior in close proximity to the magnetic field, making this technology selective.

text: The Protected Planets Treaty is an armistice between the Goa'uld and the Asgard, first referred to specifically in  when Earth is included. The treaty covers 27 planets including Earth, and ensures that those planets remain free from Goa'uld domination. Other planets in the treaty include Cimmeria, K'Tau, PX3-595, the second planet of the Adara system, and Galar. The System Lords are responsible for enforcing the treaty amongst the lesser Goa'uld. One stipulation of the treaty is that none of the protected planets are allowed to advance to the point of posing a threat to the Goa'uld; the System Lords cite this condition in their original demand that Earth surrender its Stargate to be included in the treaty. Another term of the treaty is that the Asgard are forbidden to artificially advance the civilization of any protected planet, even to save them from a natural disaster. This prevents them from acting to help K'Tau in  and Earth in . Any violation of the treaty will nullify it as a whole, and free the Goa'uld to attack any protected planet.

text: The Protected Planets Treaty is an

text: armistice

text: between the Goa'uld and the Asgard, first referred to specifically in  when Earth is included. The treaty covers 27 planets including Earth, and ensures that those planets remain free from Goa'uld domination. Other planets in the treaty include Cimmeria, K'Tau, PX3-595, the second planet of the Adara system, and Galar. The System Lords are responsible for enforcing the treaty amongst the lesser Goa'uld. One stipulation of the treaty is that none of the protected planets are allowed to advance to the point of posing a threat to the Goa'uld; the System Lords cite this condition in their original demand that Earth surrender its

text: Stargate

text: to be included in the treaty. Another term of the treaty is that the Asgard are forbidden to artificially advance the civilization of any protected planet, even to save them from a natural disaster. This prevents them from acting to help K'Tau in  and Earth in . Any violation of the treaty will nullify it as a whole, and free the Goa'uld to attack any protected planet.

text: Recent evidence has suggested that the inner core of Earth may rotate slightly faster than the rest of the planet; however, more recent studies in 2011 found this hypothesis to be inconclusive. Options remain for the core which may be oscillatory in nature or a chaotic system. In August 2005 a team of geophysicists announced in the journal Science that, according to their estimates, Earth's inner core rotates approximately 0.3 to 0.5 degrees per year faster relative to the rotation of the surface.

text: Recent evidence has suggested that the inner core of Earth may rotate slightly faster than the rest of the planet; however, more recent studies in 2011 found this hypothesis to be inconclusive. Options remain for the core which may be oscillatory in nature or a chaotic system. In August 2005 a team of

text: geophysicist

text: s announced in the journal

text: Science

text: that, according to their estimates, Earth's inner core rotates approximately 0.3 to 0.5 degrees per year faster relative to the rotation of the surface.

text: On average, the visible diameter of the Sun on Mercury is 2.5 times as large as it appears from Earth, and its total brightness is more than 6 times as great. Because of the planet's eccentric orbit, the Sun's apparent size in the sky would vary from 2.2 times that from Earth at aphelion (with total brightness 4.8 times as great), to 3.2 times at perihelion (with total brightness 10.2 times as great).

text: On average, the visible diameter of the Sun on Mercury is 2.5 times as large as it appears from Earth, and its total brightness is more than 6 times as great. Because of the planet's eccentric orbit, the Sun's apparent size in the sky would vary from 2.2 times that from Earth at

text: aphelion

text: (with total brightness 4.8 times as great), to 3.2 times at

text: perihelion

text: (with total brightness 10.2 times as great).

text: Physicist Kevin Grazier posited in a 2006 essay the composition and problems associated with a Halo installation. The complete Halos seen in Halo: Combat Evolved and Halo 2 orbit gas giants similar to Jupiter, though much larger; the bodies exhibit characteristics of both a jovian planet and a small star. In each system, there are five points where a body of negligible mass would remain stationary to the two much larger bodies in the system, the gas giant and its moon. These areas, known as Lagrange points, are classified by stability; while bodies at 60° angles to the gas giant would remain in the same location relative to the other objects in the system, the other three Lagrange points are meta-stable, having the tendency to be unstable in one direction. As the Halos are located at point , the installations must actively correct its orbit. The apparent gravity of the Halo installations is close to Earth normal. A Halo would have to spin with a tangental speed of  per second to match Earth's gravity, translating to 19.25 rotations in a day.

text: Physicist

text: Kevin Grazier

text: posited in a 2006 essay the composition and problems associated with a Halo installation. The complete Halos seen in Halo: Combat Evolved and Halo 2 orbit

text: gas giant

text: s similar to

text: Jupiter

text: , though much larger; the bodies exhibit characteristics of both a jovian planet and a small star. In each system, there are five points where a body of negligible mass would remain stationary to the two much larger bodies in the system, the gas giant and its moon. These areas, known as

text: Lagrange points

text: , are classified by stability; while bodies at 60° angles to the gas giant would remain in the same location relative to the other objects in the system, the other three Lagrange points are meta-stable, having the tendency to be unstable in one direction. As the Halos are located at point , the installations must actively correct its orbit. The apparent gravity of the Halo installations is close to Earth normal. A Halo would have to spin with a tangental speed of  per second to match Earth's gravity, translating to 19.25 rotations in a day.

text: At any stage of the cosmic year, the position of the Earth's axis demonstrates the concurrent relationship between yin and yang. It is generally accepted that in the history of our planet there have been periodic changes in the Earth's poles, magnetism, and orbit.

text: At any stage of the cosmic year, the position of the Earth's axis demonstrates the concurrent relationship between

text: yin and yang

text: . It is generally accepted that in the history of our planet there have been periodic changes in the Earth's poles, magnetism, and orbit.

text: Imprisoned by the space cats, Amy and Nibbler watch helplessly as the device stops the Earth, causing destruction as objects on its surface adhere to the first law of motion. Katz transfers the stored rotational energy to Thuban 9 and departs, leaving the Earth in disarray and freeing the crew of their hypnosis.  Because it has stopped, Earth begins to burn on its sun-exposed face while the opposite face freezes in the darkness of space.  The crew attempt to reverse the machine and restore Earth's natural rotation, but find that it can only turn in one direction. While lamenting that her invention has doomed Earth, Amy realizes that by continuing to turn it in the same direction, they can restart the Earth's rotation, albeit in the opposite direction. Professor Farnsworth assembles the Applied Physics Department faculty of Mars University and Amy explains her idea, demonstrating that the reverse rotation will not be deleterious to Earth. The plan works and the machine reclaims Earth's rotational energy from Thuban 9, now spinning in the opposite direction. In recognition of her achievement, Amy receives her doctorate in applied physics, now "Doctor Wong".  However, she remains with Planet Express because the job market is poor while Nibbler reconciles with Leela, appreciating that she cares for him.

text: Imprisoned by the space cats, Amy and Nibbler watch helplessly as the device stops the Earth, causing destruction as objects on its surface adhere to the

text: first law of motion

text: . Katz transfers the stored rotational energy to Thuban 9 and departs, leaving the Earth in disarray and freeing the crew of their hypnosis.  Because it has stopped, Earth begins to burn on its sun-exposed face while the opposite face freezes in the darkness of space.  The crew attempt to reverse the machine and restore Earth's natural rotation, but find that it can only turn in one direction. While lamenting that her invention has doomed Earth, Amy realizes that by continuing to turn it in the same direction, they can restart the Earth's rotation, albeit in the opposite direction.

text: Professor Farnsworth

text: assembles the Applied Physics Department faculty of Mars University and Amy explains her idea, demonstrating that the reverse rotation will not be deleterious to Earth. The plan works and the machine reclaims Earth's rotational energy from Thuban 9, now spinning in the opposite direction. In recognition of her achievement, Amy receives her doctorate in applied physics, now "Doctor Wong".  However, she remains with Planet Express because the job market is poor while Nibbler reconciles with Leela, appreciating that she cares for him.

text: Twelve exoplanet systems have been found in Aquarius as of 2013. Gliese 876, one of the nearest stars to Earth at a distance of 15 light-years, was the first red dwarf star to be found to possess a planetary system. It is orbited by four planets, including one terrestrial planet 6.6 times the mass of Earth. The planets vary in orbital period from 2 days to 124 days. 91 Aquarii is an orange giant star orbited by one planet, 91 Aquarii b. The planet's mass is 2.9 times the mass of Jupiter, and its orbital period is 182 days. Gliese 849 is a red dwarf star orbited by the first known long-period Jupiter-like planet, Gliese 849 b. The planet's mass is 0.99 times that of Jupiter and its orbital period is 1,852 days.

text: Twelve exoplanet systems have been found in Aquarius as of 2013.

text: Gliese 876

text: , one of the nearest stars to Earth at a distance of 15 light-years, was the first

text: red dwarf

text: star to be found to possess a

text: planetary system

text: . It is orbited by four planets, including one

text: terrestrial planet

text: 6.6 times the mass of Earth. The planets vary in orbital period from 2 days to 124 days.

text: 91 Aquarii

text: is an

text: orange giant

text: star orbited by one planet,

text: 91 Aquarii b

text: . The planet's mass is 2.9 times the mass of Jupiter, and its orbital period is 182 days.

text: Gliese 849

text: is a red dwarf star orbited by the first known long-period Jupiter-like planet,

text: Gliese 849 b

text: . The planet's mass is 0.99 times that of Jupiter and its orbital period is 1,852 days.

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: Geophysicist Dr. Josh Keyes (Aaron Eckhart) and scientists Serge Leveque (Tchéky Karyo) and Conrad Zimsky (Stanley Tucci) become aware of an instability of Earth's magnetic field after a series of incidents across the globe. They determine that the Earth's molten core, which generates this field, has stopped rotating, and within a year the field will collapse exposing the planet's surface directly to devastating solar radiation. Backed by the U.S. Government, Keyes, Leveque, and Zimsky create a plan to bore down to the core and set off several nuclear explosions to restart the rotation. They gain the help of rogue scientist Ed "Braz" Brazzelton (Delroy Lindo) who has devised a vessel made of "Unobtainium" that can withstand the heat and pressure within the Earth's crust and convert it to energy, as well as a laser-driven boring system that will allow them to quickly pass through the crust.  Construction starts immediately on the Virgil, a multi-compartment vessel to be helmed by Space Shuttle pilots Commander Robert Iverson (Bruce Greenwood) and Major Rebecca "Beck" Childs (Hilary Swank) who will join Keyes and the others. To prevent a worldwide panic, Keyes enlists computer hacker Theodore Donald "Rat" Finch (DJ Qualls) to scour the Internet and eliminate all traces of the pending disaster or their plan.

text: Geophysicist Dr. Josh Keyes (

text: Aaron Eckhart

text: ) and scientists Serge Leveque (

text: Tchéky Karyo

text: ) and Conrad Zimsky (

text: Stanley Tucci

text: ) become aware of an instability of

text: Earth's magnetic field

text: after a series of incidents across the globe. They determine that the Earth's molten core, which generates this field, has stopped rotating, and within a year the field will collapse exposing the planet's surface directly to devastating solar radiation. Backed by the U.S. Government, Keyes, Leveque, and Zimsky create a plan to bore down to the core and set off several nuclear explosions to restart the rotation. They gain the help of rogue scientist Ed "Braz" Brazzelton (

text: Delroy Lindo

text: ) who has devised a vessel made of "

text: Unobtainium

text: " that can withstand the heat and pressure within the Earth's crust and convert it to energy, as well as a laser-driven boring system that will allow them to quickly pass through the crust.  Construction starts immediately on the Virgil, a multi-compartment vessel to be helmed by

text: Space Shuttle

text: pilots Commander Robert Iverson (

text: Bruce Greenwood

text: ) and Major Rebecca "Beck" Childs (

text: Hilary Swank

text: ) who will join Keyes and the others. To prevent a worldwide panic, Keyes enlists computer hacker Theodore Donald "Rat" Finch (

text: DJ Qualls

text: ) to scour the Internet and eliminate all traces of the pending disaster or their plan.

text: The Earth's rotational speed is , and a day corresponds to one period . A rotational acceleration  gives a rate of change of the period of , which is usually expressed as .  This has units of 1/time, and is commonly quoted as milliseconds per day per century (ms/day/cy).

text: Nights are shorter than days on average due to two factors. Firstly, the sun is not a point, but has an apparent size of about 32 arc minutes. Secondly, the atmosphere refracts sunlight so that some of it reaches the ground when the sun is below the horizon by about 34 arc minutes. The combination of these two factors means that light reaches the ground when the center of the sun is below the horizon by about 50 arc minutes. Without these effects, day and night would be the same length at the autumnal (autumn/fall) and vernal (spring) equinoxes, the moments when the sun passes over the equator. In reality, around the equinoxes the day is almost 14 minutes longer than the night at the equator, and even more towards the poles. The summer and winter solstices mark the shortest and the longest night, respectively. The closer a location is to either the North Pole or the South Pole, the larger the range of variation in the night's length. Although equinoxes occur with a day and night close to equal length, before and after an equinox the ratio of night to day changes more rapidly in high latitude locations than in low latitude locations. In the Northern Hemisphere, Denmark has shorter nights in June than India. In the Southern Hemisphere, Antarctica has longer nights in June than Chile. The Northern and Southern Hemispheres of the world experience the same patterns of night length at the same latitudes, but the cycles are 6 months apart so that one hemisphere experiences long nights (winter) while the other is experiencing short nights (summer).

text: Nights are shorter than days on average due to two factors. Firstly, the sun is not a point, but has an apparent size of about 32

text: arc minute

text: s. Secondly, the atmosphere

text: refracts

text: sunlight so that some of it reaches the ground when the sun is below the horizon by about 34 arc minutes. The combination of these two factors means that light reaches the ground when the center of the sun is below the horizon by about 50 arc minutes. Without these effects, day and night would be the same length at the

text: autumnal

text: (autumn/fall) and

text: vernal

text: (spring)

text: equinox

text: es, the moments when the sun passes over the

text: equator

text: . In reality, around the equinoxes the day is almost 14 minutes longer than the night at the equator, and even more towards the

text: pole

text: s. The summer and winter

text: solstice

text: s mark the shortest and the longest night, respectively. The closer a location is to either the

text: North Pole

text: or the

text: South Pole

text: , the larger the range of variation in the night's length. Although equinoxes occur with a day and night close to equal length, before and after an equinox the ratio of night to day changes more rapidly in

text: high latitude

text: locations than in

text: low latitude

text: locations. In the

text: Northern Hemisphere

text: Denmark

text: has shorter nights in June than

text: India

text: . In the

text: Southern Hemisphere

text: Antarctica

text: has longer nights in June than

text: Chile

text: . The Northern and Southern Hemispheres of the world experience the same patterns of night length at the same latitudes, but the cycles are 6 months apart so that one hemisphere experiences long nights (winter) while the other is experiencing short nights (summer).

text: In 2005, the first planets around main-sequence stars that may be terrestrial were found: Gliese 876 d, has a mass 7 to 9 times that of Earth and an orbital period of just two Earth days. It orbits the red dwarf Gliese 876, 15 light years from Earth. OGLE-2005-BLG-390Lb, about 5.5 times the mass of Earth, orbits a star about 21,000 light years away in the constellation Scorpius.From 2007 to 2010, three (possibly four) potential terrestrial planets were found orbiting the red dwarf Gliese 581. The smallest, Gliese 581 e, is only about 1.9 Earth mass, but orbits very close to the star. An ideal terrestrial planet would be 2 Earth masses with a 25-day orbital period around a red dwarf. Two others, Gliese 581 c and Gliese 581 d, as well as a disputed planet, Gliese 581 g, are more-massive super-Earths orbiting in or close to the habitable zone of the star, so they could  potentially be habitable, with Earth-like temperatures.

text: In 2005, the first planets around main-sequence stars that may be terrestrial were found:

text: Gliese 876 d

text: , has a mass 7 to 9 times that of Earth and an orbital period of just two Earth days. It orbits the red dwarf

text: Gliese 876

text: , 15

text: light year

text: s from Earth.

text: , about 5.5 times the mass of Earth, orbits a star about 21,000 light years away in the constellation Scorpius.From 2007 to 2010, three (possibly four) potential terrestrial planets were found orbiting the red dwarf

text: Gliese 581

text: . The smallest,

text: Gliese 581 e

text: , is only about 1.9 Earth mass, but orbits very close to the star. An ideal terrestrial planet would be 2 Earth masses with a 25-day orbital period around a red dwarf. Two others,

text: Gliese 581 c

text: and

text: Gliese 581 d

text: , as well as a disputed planet,

text: Gliese 581 g

text: , are more-massive super-Earths orbiting in or close to the habitable zone of the star, so they could  potentially be habitable, with Earth-like temperatures.

text: In "Night and Day" (#63, illustrated by Rafael Albuquerque), Superman is forced to flee Earth when Gorilla Grodd succeeds in filling the planet's atmosphere with Kryptonite. Subsequently, Grodd conquers Earth, having used his mental abilities to control the minds of every remaining inhabitant of the planet except Batman, who resists using his mental discipline. This is broken when Alfred Pennyworth dies enabling Grodd capture him. At Batman's execution Superman returns, now immune to the artificial kryptonite released by Grodd thanks to Batman, and defeats the villain. However this entire scenario is revealad to be a simulation created in the Batcomputer.

text: In "Night and Day" (#63, illustrated by Rafael Albuquerque), Superman is forced to flee Earth when

text: Gorilla Grodd

text: succeeds in filling the planet's atmosphere with Kryptonite. Subsequently, Grodd conquers Earth, having used his mental abilities to control the minds of every remaining inhabitant of the planet except Batman, who resists using his mental discipline. This is broken when

text: Alfred Pennyworth

text: dies enabling Grodd capture him. At Batman's execution Superman returns, now immune to the artificial kryptonite released by Grodd thanks to Batman, and defeats the villain. However this entire scenario is revealad to be a simulation created in the Batcomputer.

text: The list includes planets within the range of 0.8–1.9 Earth masses, below which are generally classed as sub-Earth and above classed as super-Earth. In addition, only planets known to fall within the range of 0.5–2.0 Earth radius (between half and twice the radius of the Earth) are included. In contrast, the Earth Similarity Index uses both mass and radius as criteria.

text: The list includes planets within the range of 0.8–1.9 Earth masses, below which are generally classed as

text: sub-Earth

text: and above classed as

text: super-Earth

text: . In addition, only planets known to fall within the range of 0.5–2.0 Earth radius (between half and twice the radius of the Earth) are included. In contrast, the Earth Similarity Index uses both mass and radius as criteria.

text: Per the usual exoplanet nomenclature, the first planet discovered to be orbiting Kepler-10 is called Kepler-10b.  Announced in 2011, it was the first rocky planet identified outside the Solar system.  The planet has a mass that is 3.33±0.49 times that of Earth's and a radius that is 1.47 times that of Earth. The planet orbits Kepler-10 at a distance of 0.01684 AU every 0.8375 days; this can be compared to the orbit and orbital period of planet Mercury, which circles the Sun at a distance of 0.3871 AU every 87.97 days. Because the planet orbits so closely to its star, its eccentricity is virtually zero. It, thus, has an extremely circular orbit.

text: Per the usual

text: exoplanet nomenclature

text: , the first planet discovered to be orbiting Kepler-10 is called

text: .  Announced in 2011, it was the first

text: rocky planet

text: identified outside the Solar system.  The planet has a mass that is 3.33±0.49 times that of Earth's and a radius that is 1.47 times that of Earth. The planet orbits Kepler-10 at a distance of 0.01684

text: AU

text: every 0.8375 days; this can be compared to the orbit and

text: orbital period

text: of planet

text: Mercury

text: , which circles the Sun at a distance of 0.3871 AU every 87.97 days. Because the planet orbits so closely to its star, its

text: eccentricity

text: is virtually zero. It, thus, has an extremely circular orbit.

text: The Earth's axis of rotation – and hence the position of the North Pole – was commonly believed to be fixed (relative to the surface of the Earth) until, in the 18th century, the mathematician Leonhard Euler predicted that the axis might "wobble" slightly. Around the beginning of the 20th century astronomers noticed a small apparent "variation of latitude," as determined for a fixed point on Earth from the observation of stars. Part of this variation could be attributed to a wandering of the Pole across the Earth's surface, by a range of a few metres. The wandering has several periodic components and an irregular component. The component with a period of about 435 days is identified with the eight-month wandering predicted by Euler and is now called the Chandler wobble after its discoverer. The exact point of intersection of the Earth's axis and the Earth's surface, at any given moment, is called the "instantaneous pole", but because of the "wobble" this cannot be used as a definition of a fixed North Pole (or South Pole) when metre-scale precision is required.

text: The Earth's axis of rotation – and hence the position of the North Pole – was commonly believed to be fixed (relative to the surface of the Earth) until, in the 18th century, the mathematician

text: Leonhard Euler

text: predicted that the axis might "wobble" slightly. Around the beginning of the 20th century astronomers noticed a small apparent "variation of latitude," as determined for a fixed point on Earth from the observation of stars. Part of this variation could be attributed to a wandering of the Pole across the Earth's surface, by a range of a few metres. The wandering has several periodic components and an irregular component. The component with a period of about 435 days is identified with the eight-month wandering predicted by Euler and is now called the

text: Chandler wobble

text: after its discoverer. The exact point of intersection of the Earth's axis and the Earth's surface, at any given moment, is called the "instantaneous pole", but because of the "wobble" this cannot be used as a definition of a fixed North Pole (or South Pole) when metre-scale precision is required.

text: The difference comes from the way in which planetary masses are calculated. It is impossible to "weigh" a planet, and much less the Sun, against the sort of mass standards which are used in the laboratory. On the other hand, the orbits of the planets give a great range of observational data as to the relative positions of each body, and these positions can be compared to their relative masses using Newton's law of universal gravitation (with small corrections for General Relativity where necessary). To convert these relative masses to Earth-based units such as the kilogram, it is necessary to know the value of the Newtonian gravitational constant, G. This constant is remarkably difficult to measure in practice, and its value is only known to a precision of one part in ten-thousand.

text: The difference comes from the way in which planetary masses are calculated. It is impossible to "weigh" a planet, and much less the Sun, against the sort of mass standards which are used in the laboratory. On the other hand, the orbits of the planets give a great range of observational data as to the relative positions of each body, and these positions can be compared to their relative masses using

text: Newton's law of universal gravitation

text: (with small corrections for

text: General Relativity

text: where necessary). To convert these relative masses to Earth-based units such as the kilogram, it is necessary to know the value of the

text: Newtonian gravitational constant

text: , G. This constant is remarkably difficult to measure in practice, and its value is only known to a precision of one part in ten-thousand.

text: Drach'nam appear in the short story "Jade Solitare" in the compilation Tales of The New Republic. They are a very brutal and violent race employing neuronic whips (a whip with a conductive lash which sends hundreds of volts through the victim's body), and long (15") serrated knives. Their home planet is very diverse on the surface ranging from very hot to extremely cold. The planet rotates extremely slowly - one day is about two hundred earth years - so as a result all of the Drach'nam cities are dark and dank tunnels underground.

text: Drach'nam appear in the short story "Jade Solitare" in the compilation

text: Tales of The New Republic

text: . They are a very brutal and violent race employing neuronic whips (a whip with a conductive lash which sends hundreds of volts through the victim's body), and long (15") serrated knives. Their home planet is very diverse on the surface ranging from very hot to extremely cold. The planet rotates extremely slowly - one day is about two hundred earth years - so as a result all of the Drach'nam cities are dark and dank tunnels underground.

text: The original American release included the "Night Version" of "Planet Earth" instead of the original, even if it is not listed as such. "To The Shore" was dropped from the US track listing to accommodate the-now increased length of "Planet Earth". Earlier alternate titles for "Anyone Out There" and "Night Boat" are used.

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: Regardless of the time of year, the northern and southern hemispheres always experience opposite seasons.  This is because during summer or winter, one part of the planet is more directly exposed to the rays of the Sun (see Fig. 1) than the other, and this exposure alternates as the Earth revolves in its orbit.  For approximately half of the year (from around March 20 to around September 22), the northern hemisphere tips toward the Sun, with the maximum amount occurring on about June 21. For the other half of the year, the same happens, but in the southern hemisphere instead of the northern, with the maximum around December 21. The two instants when the Sun is directly overhead at the Equator are the equinoxes. Also at that moment, both the North Pole and the South Pole of the Earth are just on the terminator, and hence day and night are equally divided between the northern and southern hemispheres.  Around the March equinox, the northern hemisphere will be experiencing spring as the hours of daylight increase, and the southern hemisphere is experiencing autumn as daylight hours shorten.

text: Regardless of the time of year, the

text: northern

text: and southern hemispheres always experience opposite seasons.  This is because during summer or winter, one part of the planet is more directly exposed to the rays of the Sun (see Fig. 1) than the other, and this exposure alternates as the Earth revolves in its orbit.  For approximately half of the year (from around March 20 to around September 22), the northern hemisphere tips toward the Sun, with the maximum amount occurring on about June 21. For the other half of the year, the same happens, but in the southern hemisphere instead of the northern, with the maximum around December 21. The two instants when the Sun is directly overhead at the Equator are the equinoxes. Also at that moment, both the

text: North Pole

text: and the

text: South Pole

text: of the Earth are just on the

text: terminator

text: , and hence day and night are equally divided between the northern and southern hemispheres.  Around the March equinox, the northern hemisphere will be experiencing spring as the hours of daylight increase, and the southern hemisphere is experiencing autumn as daylight hours shorten.

text: One way to detect primordial black holes is by their Hawking radiation.  Stephen Hawking theorized in 1974 that large numbers of such smaller primordial black holes might exist in the Milky Way in our galaxy's halo region. All black holes are theorized to emit Hawking radiation at a rate inversely proportional to their mass. Since this emission further decreases their mass, black holes with very small mass would experience runaway evaporation, creating a massive burst of radiation at the final phase, equivalent to a hydrogen bomb yielding millions of megatons of explosive force. A regular black hole (of about 3 solar masses) cannot lose all of its mass within the current age of the universe (they would take about 10 years to do so, even without any matter falling in). However, since primordial black holes are not formed by stellar core collapse, they may be of any size. A black hole with a mass of about 10 kg would have a lifetime about equal to the age of the universe. If such low-mass black holes were created in sufficient number in the Big Bang, we should be able to observe some of those that are relatively nearby in our own Milky Way galaxy exploding today.  NASA's Fermi Gamma-ray Space Telescope satellite, launched in June 2008, is designed in part to search for such evaporating primordial black holes.  However, if theoretical Hawking radiation does not actually exist, such primordial black holes would be extremely difficult, if not impossible, to detect in space due to their small size and lack of large gravitational influence. It has been suggested that a small black hole passing through the Earth would produce a detectable acoustic signal.  Because of its tiny diameter, large mass compared to a nucleon, and relatively high speed, such primordial black holes would simply transit Earth virtually unimpeded with only a few impacts on nucleons, exiting the planet with no ill effects.

text: One way to detect primordial black holes is by their

text: Hawking radiation

text: Stephen Hawking

text: theorized in 1974 that large numbers of such smaller primordial black holes might exist in the

text: Milky Way

text: in our

text: galaxy

text: 's

text: halo

text: region. All black holes are theorized to emit Hawking radiation at a rate inversely proportional to their mass. Since this emission further decreases their mass, black holes with very small mass would experience runaway evaporation, creating a massive burst of radiation at the final phase, equivalent to a hydrogen bomb yielding millions of megatons of explosive force. A regular black hole (of about 3

text: solar mass

text: es) cannot lose all of its mass within the current age of the universe (they would take about 10 years to do so, even without any matter falling in). However, since primordial black holes are not formed by stellar core collapse, they may be of any size. A black hole with a mass of about 10 kg would have a lifetime about equal to the age of the universe. If such low-mass black holes were created in sufficient number in the Big Bang, we should be able to observe some of those that are relatively nearby in our own

text: Milky Way

text: galaxy

text: exploding today.

text: NASA

text: 's

text: Fermi Gamma-ray Space Telescope

text: satellite, launched in June 2008, is designed in part to search for such evaporating primordial black holes.  However, if theoretical Hawking radiation does not actually exist, such primordial black holes would be extremely difficult, if not impossible, to detect in space due to their small size and lack of large gravitational influence. It has been suggested that a small black hole passing through the Earth would produce a detectable acoustic signal.  Because of its tiny diameter, large mass compared to a

text: nucleon

text: , and relatively high speed, such primordial black holes would simply transit Earth virtually unimpeded with only a few impacts on nucleons, exiting the planet with no ill effects.

text: The Moon orbits Earth in the prograde direction and completes one revolution relative to the stars in approximately 27.322 days (a sidereal month). Earth and the Moon orbit about their barycentre (common center of mass), which lies about  from Earth's center (about  of the radius of Earth). On average, the Moon is at a distance of about  from Earth's centre, which corresponds to about 60 Earth radii. With a mean orbital velocity of , the Moon appears to move relative to the stars each hour by an amount roughly equal to its angular diameter, or by about half a degree. The Moon differs from most satellites of other planets in that its orbit is close to the plane of the ecliptic, and not to Earth's equatorial plane. The plane of the lunar orbit is inclined to the ecliptic by about 5°, whereas the Moon's equatorial plane is inclined by only 1.5° to the ecliptic.

text: The

text: Moon

text: orbit

text: s

text: Earth

text: in the

text: prograde

text: direction and completes one revolution relative to the stars in approximately 27.322 days (a

text: sidereal month

text: ). Earth and the Moon orbit about their

text: barycentre

text: (common center of mass), which lies about  from Earth's center (about  of the radius of Earth). On average, the Moon is at a distance of about  from Earth's centre, which corresponds to about 60 Earth radii. With a mean orbital velocity of , the Moon appears to move relative to the

text: star

text: s each hour by an amount roughly equal to its

text: angular diameter

text: , or by about half a degree. The Moon differs from most

text: satellites

text: of other

text: planet

text: s in that its orbit is close to the plane of the

text: ecliptic

text: , and not to Earth's

text: equatorial plane

text: . The plane of the lunar orbit is inclined to the ecliptic by about 5°, whereas the Moon's equatorial plane is inclined by only 1.5° to the ecliptic.

text: The spacecraft passed Venus on February 5, 1974, the closest approach being 5,768 km at 17:01 UT. It was the twelfth spacecraft to reach Venus and the eighth to return data from the planet, as well as the first mission to succeed in broadcasting images of Venus back to Earth. Mariner 10 built upon observations made by Mariner 5 six years earlier; most importantly, Mariner 10 had a camera whereas the prior mission lacked one. As Mariner 10 veered around Venus, from the planet's night side to daylight, the cameras snapped the probe's first image of Venus, showing an illuminated arc of clouds over the north pole emerging from darkness. Engineers initially feared that the star-tracker could mistake the much brighter Venus for Canopus, repeating the mishaps with flaking paint. Fortunately, the star-tracker did not malfunction. Earth occultation occurred between 17:07 UT and 17:11 UT, during which the spacecraft transmitted X-band radio waves through Venus' atmosphere, gathering data on cloud structure and temperature. Although Venus's cloud cover is nearly featureless in visible light, it was discovered that extensive cloud detail could be seen through Mariner's ultraviolet camera filters. Earth-based ultra-violet observation had shown some indistinct blotching even before Mariner 10, but the detail seen by Mariner was a surprise to most researchers. The probe continued photographing Venus until February 13. Among the encounter's 4,165 acquired photographs, one resulting series of images captured a thick and distinctly patterned atmosphere making a full revolution every four days, just as terrestrial observations had suggested.

text:
Mercury attains inferior conjunction (nearest approach to Earth) every 116 Earth days on average, but this interval can range from 105 days to 129 days due to the planet's eccentric orbit. Mercury can come as near as  to Earth, and that is slowly declining: The next approach to within  is in 2679, and to within  in 4487, but it will not be closer to Earth than  until AD 28,622.<ref>Mercury Closest Approaches to Earth generated with:
 1. Solex 10 (Text Output file)
 2. Gravity Simulator charts
 3. JPL Horizons 1950–2200{{Hide in print|

text: The first Earth global gravity model based on GOCE data was presented at ESA’s Living Planet Symposium, in June 2010.

text: The simplest model for the shape of the entire Earth is a sphere. The Earth's radius is the distance from Earth's center to its surface, about . While "radius" normally is a characteristic of perfect spheres, the Earth deviates from a perfect sphere by only a third of a percent, sufficiently close to treat it as a sphere in many contexts and justifying the term "the radius of the Earth".

text: The simplest model for the shape of the entire

text: Earth

text: is a

text: sphere

text: . The Earth's

text: radius

text: is the

text: distance

text: from Earth's center to its surface, about . While "radius" normally is a characteristic of perfect spheres, the Earth deviates from a perfect sphere by only a third of a percent, sufficiently close to treat it as a sphere in many contexts and justifying the term "the radius of the Earth".

text: Gas giants are split into five classes (numbered using Roman numerals) according to their modeled physical atmospheric properties. In the Solar System only Jupiter and Saturn are within the Sudarsky classification, and both are Class I.The appearance of planets that are not gas giants cannot be predicted by the Sudarsky system, for example terrestrial planets such as Earth, HD 85512 b (3.6 Earth masses) and OGLE-2005-BLG-390Lb (5.5 Earth masses), or ice giants such as Uranus (14 Earth masses) and Neptune (17 Earth masses).

text: Gas giants are split into five classes (numbered using

text: Roman numerals

text: ) according to their modeled physical atmospheric properties. In the Solar System only

text: Jupiter

text: and

text: Saturn

text: are within the Sudarsky classification, and both are Class I.The appearance of planets that are not gas giants cannot be predicted by the Sudarsky system, for example

text: terrestrial planet

text: s such as

text: Earth

text: HD 85512 b

text: Earth mass

text: es) and

text: (5.5 Earth masses), or

text: ice giant

text: s such as

text: Uranus

text: (14 Earth masses) and

text: Neptune

text: (17 Earth masses).

text: More than two thousand planets around other stars ("extrasolar planets" or "exoplanets") have been discovered in the Milky Way. As of ,  known extrasolar planets in  planetary systems (including  multiple planetary systems), ranging in size from just above the size of the Moon to gas giants about twice as large as Jupiter have been discovered, out of which more than 100 planets are the same size as Earth, nine of which are at the same relative distance from their star as Earth from the Sun, i.e. in the habitable zone. On December 20, 2011, the Kepler Space Telescope team reported the discovery of the first Earth-sized extrasolar planets, Kepler-20e and Kepler-20f, orbiting a Sun-like star, Kepler-20. A 2012 study, analyzing gravitational microlensing data, estimates an average of at least 1.6 bound planets for every star in the Milky Way.Around one in five Sun-like stars is thought to have an Earth-sized planet in its habitable zone.

text: More than two thousand planets around other stars ("

text: extrasolar planet

text: s" or "exoplanets") have been discovered in the

text: Milky Way

text: . As of ,  known extrasolar planets in

text: planetary systems

text: (including

text: multiple planetary systems

text: ), ranging in size from

text: just above the size of the Moon

text: to

text: gas giant

text: s

text: about twice as large as Jupiter

text: have been discovered, out of which more than 100 planets are the same size as Earth, nine of which are at the same relative distance from their star as Earth from the Sun, i.e. in the habitable zone. On December 20, 2011, the

text: Kepler Space Telescope

text: team reported the discovery of the first

text: Earth-sized

text: extrasolar planets,

text: and

text: , orbiting a

text: Sun-like star

text: . A 2012 study, analyzing

text: gravitational microlensing

text: data, estimates an average of at least 1.6 bound planets for every star in the Milky Way.Around one in five Sun-like stars is thought to have an Earth-sized planet in its habitable zone.

text: Some of the Kepler transiting planets with radii in the range 1–4 Earth radii have had their masses measured by radial-velocity or transit-timing methods. The calculated densities show that up to 1.5 Earth radii, these planets are rocky and that density increases with increasing radius due to gravitational compression. However, between 1.5 and 4 Earth radii the density decreases with increasing radius. This indicates that above 1.5 Earth radii planets tend to have increasing amounts of volatiles and gas. Despite this general trend, there is a wide range of masses at a given radius, which could be because gas planets can have rocky cores of different masses or compositions and could also be due to photoevaporation of volatiles.Thermal evolutionary atmosphere models suggest a radius of 1.75 times that of Earth as a dividing line between rocky and gaseous planets.Excluding close-in planets that have lost their gas envelope due to stellar irradiation, studies of the metallicity of stars suggest a dividing line of 1.7 Earth radii between rocky planets and gas dwarfs; then another dividing line at 3.9 Earth radii between gas dwarfs and gas giants. These dividing lines are statistical trends and do not necessarily apply to specific planets because there are many other factors besides metallicity that affect planet formation, including distance from star – there may be larger rocky planets formed at larger distances.An independent reanalysis of the data suggests that there are no such dividing lines and that there is a continuum of planet formation between 1 and 4 Earth radii and no reason to expect that the amount of solid material in a protoplanetary disk determines whether super-Earths or mini-Neptunes form. Studies made in 2016 based on over 300 planets suggest that most objects over approximately two Earth masses collect significant hydrogen–helium envelopes, which would mean rocky super-Earths may be rare.

text: Some of the Kepler transiting planets with radii in the range 1–4 Earth radii have had their masses measured by radial-velocity or transit-timing methods. The calculated densities show that up to 1.5 Earth radii, these planets are rocky and that density increases with increasing radius due to gravitational compression. However, between 1.5 and 4 Earth radii the density decreases with increasing radius. This indicates that above 1.5 Earth radii planets tend to have increasing amounts of volatiles and gas. Despite this general trend, there is a wide range of masses at a given radius, which could be because gas planets can have rocky cores of different masses or compositions and could also be due to

text: photoevaporation

text: of volatiles.Thermal evolutionary atmosphere models suggest a radius of 1.75 times that of Earth as a dividing line between rocky and gaseous planets.Excluding close-in planets that have lost their gas envelope due to stellar irradiation, studies of the

text: metallicity

text: of stars suggest a dividing line of 1.7 Earth radii between rocky planets and gas dwarfs; then another dividing line at 3.9 Earth radii between gas dwarfs and gas giants. These dividing lines are statistical trends and do not necessarily apply to specific planets because there are many other factors besides metallicity that affect planet formation, including distance from star – there may be larger rocky planets formed at larger distances.An independent reanalysis of the data suggests that there are no such dividing lines and that there is a continuum of planet formation between 1 and 4 Earth radii and no reason to expect that the amount of solid material in a protoplanetary disk determines whether super-Earths or mini-Neptunes form. Studies made in 2016 based on over 300 planets suggest that most objects over approximately two Earth masses collect significant hydrogen–helium envelopes, which would mean rocky super-Earths may be rare.

text: At the top of the clouds the wind speed on Venus reaches up to , circling the planet approximately every four Earth days in a phenomenon known as "super-rotation". Colonies floating in this region could therefore have a much shorter day length by remaining untethered to the ground and moving with the atmosphere, compared to the usual 243 Earth days it takes for the planet to rotate. Allowing a colony to move freely would also reduce structural stress from the wind.

text: The relative importance of each loss process is a function of planet mass, its atmosphere composition, and its distance from its sun. A common erroneous belief is that the primary non-thermal escape mechanism is atmospheric stripping by a solar wind in the absence of a magnetosphere  . Excess kinetic energy from solar winds can impart sufficient energy to the atmospheric particles to allow them to reach escape velocity, causing atmospheric escape. The solar wind, composed of ions, is deflected by magnetic fields because the charged particles within the wind flow along magnetic field lines. The presence of a magnetic field thus deflects solar winds, preventing the loss of atmosphere. On Earth, for instance, the interaction between the solar wind and earth's magnetic field deflects the solar wind about the planet, with near total deflection at a distance of 10 Earth radii. This region of deflection is called a bow shock.

text: The relative importance of each loss process is a function of planet

text: mass

text: , its

text: atmosphere composition

text: , and its distance from its sun. A common erroneous belief is that the primary non-thermal escape mechanism is atmospheric stripping by a

text: solar wind

text: in the absence of a

text: magnetosphere

text: . Excess kinetic energy from solar winds can impart sufficient energy to the atmospheric particles to allow them to reach escape velocity, causing atmospheric escape. The solar wind, composed of

text: ion

text: s, is deflected by

text: magnetic field

text: s because the charged particles within the wind flow along magnetic field lines. The presence of a magnetic field thus deflects solar winds, preventing the loss of atmosphere. On

text: Earth

text: , for instance, the interaction between the solar wind and earth's magnetic field deflects the solar wind about the planet, with near total deflection at a distance of 10 Earth radii. This region of deflection is called a

text: bow shock

text: Bacon rejected much of Gilbert's magnetic theory. He denied that Earth spun, and he denied deep verticity. Earth's core was cold, passive, and unmoving, as Telesio had said. The Earth was not magnetic. To explain verticity of magnets, Bacon argued that we needn't look below the surface of the Earth but should instead look up, to the behavior of winds and celestial bodies. The tendency that magnets have to rotate westward (as Bacon conceived it) was only a special case of a general tendency of things to move westward around Earth's core, a tendency exhibited by all things save the core itself. The Atlantic Ocean rolled westward and ricocheted off the Eastern coast of the New World, creating the tides. The planets, stars, sun and moon moved westward across the sky. The rotation of magnets was simply a weak manifestation of the same kind of westward migration undertaken daily by sundry objects on Earth and in the heavens.

text: Bacon rejected much of Gilbert's magnetic theory. He denied that Earth spun, and he denied deep verticity. Earth's core was cold, passive, and unmoving, as

text: Telesio

text: had said. The Earth was not magnetic. To explain verticity of magnets, Bacon argued that we needn't look below the surface of the Earth but should instead look up, to the behavior of winds and celestial bodies. The tendency that magnets have to rotate westward (as Bacon conceived it) was only a special case of a general tendency of things to move westward around Earth's core, a tendency exhibited by all things save the core itself. The Atlantic Ocean rolled westward and ricocheted off the Eastern coast of the New World, creating the tides. The planets, stars, sun and moon moved westward across the sky. The rotation of magnets was simply a weak manifestation of the same kind of westward migration undertaken daily by sundry objects on Earth and in the heavens.

text: A flexible search strategy tunes SIM Lite's mass sensitivity at each star to a desired level in the habitable planet search.  The value of η (Eta_Earth), the fraction of stars carrying Earth-analog planets, will be estimated by the Kepler Mission some time before SIM Lite launches. One strategy for a habitable planet search is to do a 'deeper' search (i.e. to lower mass sensitivity in the habitable zone) of a smaller number of targets if Earth analogs are common. A 'shallower' search of a larger number of targets could be done if Earth analogs are rarer. For example, assuming that 40% of mission time is allocated for the planet search, SIM Lite could survey:

text: A flexible search strategy tunes SIM Lite's mass sensitivity at each star to a desired level in the habitable planet search.  The value of η (Eta_Earth), the fraction of stars carrying Earth-analog planets, will be estimated by the

text: Kepler Mission

text: some time before SIM Lite launches. One strategy for a habitable planet search is to do a 'deeper' search (i.e. to lower mass sensitivity in the habitable zone) of a smaller number of targets if Earth analogs are common. A 'shallower' search of a larger number of targets could be done if Earth analogs are rarer. For example, assuming that 40% of mission time is allocated for the planet search, SIM Lite could survey:

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: The planet has a minimum Earth mass of 3.6 ± 0.5, minimum surface gravity of about 1.4 g and assuming an atmosphere like Earth's despite its far greater mass, an estimated temperature of 298 K (24.85 °C or 76.73 °F) at the top of its atmosphere. The estimated temperature is noted to be similar to temperatures in Southern France, but various atmospheric conditions prevalent in the planet have to be analyzed to estimate the temperature of the surface.  An estimated radius of 1.3  is possible based on its mass.

text: The planet has a minimum Earth mass of 3.6 ± 0.5, minimum

text: surface gravity

text: of about 1.4 g and assuming an atmosphere like Earth's despite its far greater mass, an estimated temperature of 298 K (24.85 °C or 76.73 °F) at the top of its atmosphere. The estimated temperature is noted to be similar to temperatures in

text: Southern France

text: , but various atmospheric conditions prevalent in the planet have to be analyzed to estimate the temperature of the surface.  An estimated radius of 1.3  is possible based on its mass.

text: The support structure is dependent on the velocity of the surface of the Earth where it is located. The point of connection of the pendulum moves with the surface velocity vectors of the Earth at that latitude. At the equator the support-point moves with the equatorial rotation of the Earth and moves the pendulum swing along with this rotation. At the poles the support-point is located on the axis of the Earth so the support-point rotates but does not have a horizontal velocity component as it does at the equator (and a progressively less horizontal velocity component with increasing latitude). The plane of the pendulum swing, however, is independent of the surface velocity vectors underneath the swing since there is only one point of connection. The point of connection is configured such that the plane of pendulum swing is free to swing in any direction in relation to the structure of the connection point. The pendulum swing at the poles remains aligned toward a star if not forced to rotate with the support. As a result, it is observable that the Earth turns underneath the plane of swing of the pendulum.

text: The Neptune-sized planet has at least 21 times the mass of Earth and 3 to 4 times its diameter.

text: The

text: Neptune

text: -sized planet has at least 21 times the

text: mass of Earth

text: and 3 to 4 times its

text: diameter

text: The Grid also plans for the opposite effect, a co-ordinated mass switch-off of appliances. Boxing Day is consistently, according to one employee, "the lowest of the low" power usage. At midday on 5 January 2005 a three minutes silence in remembrance of the Boxing Day Tsunami resulted in a 1300 MW temporary drop in consumption followed by a sudden 1400 MW rise.  Similar, though smaller, switch-offs occur annually at 11 am on Remembrance Day.  These switch-offs occur during the day time, so they are smaller than pickups seen at night when more electrical appliances are likely to be in use.  National Grid argued against the mass switch-off originally planned for the Live Earth and Planet Aid events as these would have resulted in highly unpredictable demands for electricity and would have generated more carbon dioxide than would have been saved. These events were subsequently cancelled.

text: The Grid also plans for the opposite effect, a co-ordinated mass switch-off of appliances.

text: Boxing Day

text: is consistently, according to one employee, "the lowest of the low" power usage. At midday on 5 January 2005 a three minutes silence in remembrance of the

entity_name: 2004 Indian Ocean earthquake and tsunami

text: Boxing Day Tsunami

text: resulted in a 1300 MW temporary drop in consumption followed by a sudden 1400 MW rise.  Similar, though smaller, switch-offs occur annually at 11 am on

text: Remembrance Day

text: .  These switch-offs occur during the day time, so they are smaller than pickups seen at night when more electrical appliances are likely to be in use.  National Grid argued against the mass switch-off originally planned for the

text: Live Earth

text: and

text: Planet Aid

text: events as these would have resulted in highly unpredictable demands for electricity and would have generated more

text: carbon dioxide

text: than would have been saved. These events were subsequently cancelled.

text: The first season slowly reveals that the Crystal Gems are remnants of a great interstellar civilization. Many places they visit are ruins once important to Gem culture, but now derelict for millennia. The Gems are cut off from their homeworld, and Steven learns that many of the monsters and artifacts they encounter are Gems who, corrupted by a Gem weapon of mass destruction, can no longer maintain rational humanoid forms. In parallel, flashbacks relayed by Greg develop the history of Rose Quartz and her relationships. By the end of the first season, Steven learns that the Homeworld Gems intended to sterilize the Earth to incubate new Gems within it. Now, 5,000 years after Rose led the other Crystal Gems in a violent and apparently successful rebellion against these genocidal plans, the Homeworld's machinations once again extend towards the Earth with the arrival of two hostile envoys, Peridot and Jasper. In the second season, Peridot is forced to ally with the Crystal Gems to prevent Earth's destruction by a Gem abomination growing in the planet's core. In the third season, Peridot and Lapis Lazuli, an errant Homeworld Gem, join the Crystal Gems. Jasper is at length defeated, and Steven learns that his mother killed one of Gem society's four matriarchs, Pink Diamond.

text: The first season slowly reveals that the Crystal Gems are remnants of a great interstellar civilization. Many places they visit are ruins once important to Gem culture, but now derelict for millennia. The Gems are cut off from their homeworld, and Steven learns that many of the monsters and artifacts they encounter are Gems who, corrupted by a Gem weapon of mass destruction, can no longer maintain rational humanoid forms. In parallel, flashbacks relayed by Greg develop the history of Rose Quartz and her relationships. By the end of the first season, Steven learns that the Homeworld Gems intended to sterilize the Earth to incubate new Gems within it. Now, 5,000 years after Rose led the other Crystal Gems in a violent and apparently successful rebellion against these genocidal plans, the Homeworld's machinations once again extend towards the Earth with the arrival of two hostile envoys, Peridot and Jasper. In the second season, Peridot is forced to ally with the Crystal Gems to prevent Earth's destruction by a Gem abomination growing in the planet's core. In the third season, Peridot and Lapis Lazuli, an errant Homeworld Gem, join the Crystal Gems. Jasper is at length defeated, and Steven learns that his mother killed one of Gem society's four

text: matriarchs

text: , Pink Diamond.

text: Lieder described Planet X as roughly four times the size of the Earth, and said that its closest approach would occur on May 27, 2003, resulting in the Earth's rotation ceasing for exactly 5.9 terrestrial days. This would be followed by the Earth's pole destabilising in a pole shift (a physical pole shift, with the Earth's pole physically moving, rather than a geomagnetic reversal) caused by magnetic attraction between the Earth's core and the magnetism of the passing planet. This in turn would disrupt the Earth's magnetic core and lead to subsequent displacement of the Earth's crust.

text: Lieder described Planet X as roughly four times the size of the Earth, and said that its closest approach would occur on May 27, 2003, resulting in the Earth's rotation ceasing for exactly 5.9 terrestrial days. This would be followed by the Earth's pole destabilising in a

text: pole shift

text: (a physical pole shift, with the Earth's pole physically moving, rather than a

text: geomagnetic reversal

text: ) caused by magnetic attraction between the Earth's core and the magnetism of the passing planet. This in turn would disrupt the Earth's magnetic core and lead to subsequent displacement of the Earth's crust.

text: According to Newton's 3rd Law, the Earth itself experiences a force equal in magnitude and opposite in direction to that which it exerts on a falling object.  This means that the Earth also accelerates towards the object until they collide.  Because the mass of the Earth is huge, however, the acceleration imparted to the Earth by this opposite force is negligible in comparison to the object's.  If the object doesn't bounce after it has collided with the Earth, each of them then exerts a repulsive contact force on the other which effectively balances the attractive force of gravity and prevents further acceleration.

text: According to

text: Newton's 3rd Law

text: , the Earth itself experiences a

text: force

text: equal in magnitude and opposite in direction to that which it exerts on a falling object.  This means that the Earth also accelerates towards the object until they collide.  Because the mass of the Earth is huge, however, the acceleration imparted to the Earth by this opposite force is negligible in comparison to the object's.  If the object doesn't bounce after it has collided with the Earth, each of them then exerts a repulsive

text: contact force

text: on the other which effectively balances the attractive force of gravity and prevents further acceleration.

text: Night and Day (AKA La Nuit et le Jour or The Night and the Day) is a "fantastic ballet" in 1 act/3 scenes, with choreography by Marius Petipa and music by Ludwig Minkus.

text: Night and Day (AKA La Nuit et le Jour or The Night and the Day) is a "fantastic

text: ballet

text: " in 1 act/3 scenes, with choreography by

text: Marius Petipa

text: and music by

text: Ludwig Minkus

text: , sometimes written as Dr. Brief, is the father of Bulma and grandfather of Trunks and Bra. He is an elderly, brilliant and eccentric scientist and is one of the smartest and richest men in the world. Dr. Briefs is the founder and President of  (the largest company on Earth) and the man responsible for the invention of the , which can shrink inanimate objects down to pocket sized capsule of namesake. He is responsible for modifying the Namekian spaceship that Bulma, Kuririn and Gohan use on their journey to the Planet Namek, in a search for its Dragon Balls. He also creates Goku his own spaceship to journey to Namek, while allowing him to train in 100x Earth's gravity. Following their return to Earth and in preparation for the battle with the Androids, Vegeta forces him into creating him a ship to allow him to train under 300x Earth's gravity, which he reluctantly complies with. He later is essential in repairing the damaged Android 16 in preparation for the Cell Games, alongside his daughter. Dr. Briefs spends the majority of his time in his large home in , where he lives with his wife and daughter, along with their numerous pets. His favorite pet is a small black cat, named  in the original anime and "Scratch" in the Funimation dub. He is voiced by Joji Yanami in Japanese. In English, he is voiced by Paul Dobson and Scott McNeil in Ocean dubs, and by Chris Forbis in the Funimation dub. Dr. Briefs appears in the final chapter of Toriyama's 2013 manga series Jaco the Galactic Patrolman, which is set before Dragon Ball.

text: , sometimes written as Dr. Brief, is the father of Bulma and grandfather of Trunks and Bra. He is an elderly, brilliant and eccentric scientist and is one of the smartest and richest men in the world. Dr. Briefs is the founder and

text: President

text: of  (the largest company on Earth) and the man responsible for the invention of the , which can shrink inanimate objects down to pocket sized capsule of namesake. He is responsible for modifying the Namekian spaceship that Bulma, Kuririn and Gohan use on their journey to the Planet Namek, in a search for its Dragon Balls. He also creates Goku his own spaceship to journey to Namek, while allowing him to train in 100x Earth's gravity. Following their return to Earth and in preparation for the battle with the Androids, Vegeta forces him into creating him a ship to allow him to train under 300x Earth's gravity, which he reluctantly complies with. He later is essential in repairing the damaged Android 16 in preparation for the Cell Games, alongside his daughter. Dr. Briefs spends the majority of his time in his large home in , where he lives with his wife and daughter, along with their numerous pets. His favorite pet is a small black cat, named  in the original anime and "Scratch" in the Funimation dub. He is voiced by

text: Joji Yanami

text: in Japanese. In English, he is voiced by

text: Paul Dobson

text: and

text: Scott McNeil

text: in Ocean dubs, and by

text: Chris Forbis

text: in the Funimation dub. Dr. Briefs appears in the final chapter of Toriyama's 2013 manga series

text: Jaco the Galactic Patrolman

text: , which is set before Dragon Ball.

text: Kepler-438b is an Earth-sized planet, an exoplanet that has a mass and radius close to that of Earth. It has a radius of 1.12 , and a mass of 1.3 . It has an equilibrium temperature of , close to that of Earth.

text: Kepler-438b is an

text: Earth-sized

text: planet, an exoplanet that has a mass and radius close to that of Earth. It has a radius of 1.12 , and a mass of 1.3 . It has an

text: equilibrium temperature

text: of , close to that of Earth.

text: Finally there is often a need to correct for the apparent movement of the stars. On the timescale of human civilisation the stars have largely maintained the same position relative to each other. Each night they appear to rotate around the celestial poles due to the Earth's rotation about its axis. However, the Earth spins rather like a spinning top. Not only does the Earth rotate, it wobbles. The Earth's axis takes around 25,800 years to complete one full wobble. The effect to the archaeoastronomer is that stars did not rise over the horizon in the past in the same places as they do today. Nor did the stars rotate around Polaris as they do now. In the case of the Egyptian pyramids, it has been shown they were aligned towards Thuban, a faint star in the constellation of Draco. The effect can be substantial over relatively short lengths of time, historically speaking. For instance a person born on 25 December in Roman times would have been born with the sun in the constellation Capricorn. In the modern period a person born on the same date would have the sun in Sagittarius due to the precession of the equinoxes.

text: Finally there is often a need to correct for the apparent movement of the stars. On the timescale of human civilisation the stars have largely maintained the same position relative to each other. Each night they appear to rotate around the celestial poles due to the Earth's rotation about its axis. However, the Earth spins rather like a

text: spinning top

text: . Not only does the Earth rotate, it wobbles. The Earth's axis takes around 25,800 years to complete one full wobble. The effect to the archaeoastronomer is that stars did not rise over the horizon in the past in the same places as they do today. Nor did the stars rotate around

text: Polaris

text: as they do now. In the case of the

text: Egyptian pyramids

text: , it has been shown they were aligned towards

text: Thuban

text: , a faint star in the constellation of

text: Draco

text: . The effect can be substantial over relatively short lengths of time, historically speaking. For instance a person born on 25 December in Roman times would have been born with the sun in the constellation

text: Capricorn

text: . In the modern period a person born on the same date would have the sun in

text: Sagittarius

text: due to the

text: precession of the equinoxes

text: For the orbit of the Earth around the Sun, the time of apsis is often expressed in terms of a time relative to seasons, since this determines the contribution of the elliptical orbit to seasonal variations. The variation of the seasons is primarily controlled by the annual cycle of the elevation angle of the Sun, which is a result of the tilt of the axis of the Earth measured from the plane of the ecliptic. The Earth's eccentricity and other orbital elements are not constant, but vary slowly due to the perturbing effects of the planets and other objects in the solar system. See Milankovitch cycles.

text: For the orbit of the Earth around the Sun, the time of apsis is often expressed in terms of a time relative to seasons, since this determines the contribution of the elliptical orbit to seasonal variations. The variation of the seasons is primarily controlled by the annual cycle of the elevation angle of the Sun, which is a result of the tilt of the axis of the Earth measured from the

text: plane of the ecliptic

text: . The Earth's

text: eccentricity

text: and other orbital elements are not constant, but vary slowly due to the perturbing effects of the planets and other objects in the solar system. See

text: Milankovitch cycles

text: "Night and Day" is a song by Jamaican recording artist Dawn Penn from her debut studio album, No, No, No (1994). The song was originally written by Augustus Pablo as "Baby I Love You So", but on Penn's album it appeared as "Night and Day". It was later re-titled "Night and Day (Baby I Love You So)" for the single release.

text: "Night and Day" is a song by

text: Jamaican

text: recording artist

text: Dawn Penn

text: from her debut studio album,

text: No, No, No

text: (1994). The song was originally written by

text: Augustus Pablo

text: as "Baby I Love You So", but on Penn's album it appeared as "Night and Day". It was later re-titled "Night and Day (Baby I Love You So)" for the single release.

text: On 30 July 2015, NASA confirmed the discovery of the nearest rocky planet outside the Solar System, larger than Earth, 21 light-years away. HD 219134 b is the closest exoplanet to Earth to be detected transiting in front of its star. The planet has a mass 4.5 times that of Earth, a radius about 1.6 times that of Earth, with a three-day orbit around its star. Combining the size and mass gives it a density of 6 g/cm, confirming that it is a rocky planet.

text: On 30 July 2015, NASA confirmed the discovery of the nearest rocky planet outside the Solar System, larger than Earth, 21 light-years away.

text: HD 219134 b

text: is the closest exoplanet to Earth to be detected transiting in front of its star. The planet has a mass 4.5 times that of Earth, a radius about 1.6 times that of Earth, with a three-day orbit around its star. Combining the size and mass gives it a density of 6 g/cm, confirming that it is a rocky planet.

text: In the tenth episode of season 1, , Daniel Jackson speculates on the existence of an advanced, benevolent race in opposition to the Goa'uld by examining Earth mythologies. This leads SG-1 to the planet Cimmeria, which is free from the Goa'uld thanks to an advanced device called "Thor's Hammer". SG-1 makes direct contact with Thor in , sixth episode of season 2, in which his true Asgard form is seen for the first time. The Asgard lend valuable assistance to Earth on several occasions, including providing their technology to Earth ships. In the episode , where Thor mediates Earth's inclusion into the Protected Planets Treaty, he reveals to Jack O'Neill that the Asgard do not have the capability to win a galactic war with the Goa'uld at that time, due to a war with a greater enemy. The Goa'uld Anubis ultimately nullifies the treaty after developing shields resistant to Asgard weapons. After Anubis' defeat in , there is speculation amongst the Goa'uld System Lords that the Asgard are no longer able to exercise power in the Milky Way.

text: In the tenth episode of

text: season 1

text: Daniel Jackson

text: speculates on the existence of an advanced, benevolent race in opposition to the Goa'uld by examining Earth mythologies. This leads

text: to the planet Cimmeria, which is free from the Goa'uld thanks to an advanced device called "Thor's Hammer". SG-1 makes direct contact with Thor in , sixth episode of season 2, in which his true Asgard form is seen for the first time. The Asgard lend valuable assistance to Earth on several occasions, including providing their technology to Earth ships. In the episode , where Thor mediates Earth's inclusion into the Protected Planets Treaty, he reveals to

text: Jack O'Neill

text: that the Asgard do not have the capability to win a galactic war with the Goa'uld at that time, due to a war with a greater enemy. The Goa'uld

text: Anubis

text: ultimately nullifies the treaty after developing shields resistant to Asgard weapons. After Anubis' defeat in , there is speculation amongst the Goa'uld System Lords that the Asgard are no longer able to exercise power in the Milky Way.

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: The radii of the planets fall between 0.54 and 1.95 Earth radii. Of particular interest are the planets e and f, as they are the best candidates for solid planets falling into the habitable zone of their star. Their radii, 1.61 and 1.41 Earth radii respectively, put them in a radius range where they may be solid terrestrial planets. Their positions within the Kepler-62 system mean that they fall within Kepler-62's habitable zone: the distance range where, for a given chemical composition (significant amounts of carbon dioxide for Kepler-62f, and a protective cloud cover for Kepler-62e), these two planets could have liquid water on their surfaces, perhaps completely covering them.   The masses of the planets could not be directly determined using either the radial velocity or the transit timing method; this failure leads to weak upper limits for the planets' masses. For e and f, that upper limit amounts to 36 and 35 Earth masses, respectively; the real masses are expected to be significantly lower. Based on composition models, the real masses of the planets are probably likely to be 2.1, 0.1, 5.5, 4.8, and 2.8 , respectively, taking into the uncertainty in composition and upper mass limits.

text: The radii of the planets fall between 0.54 and 1.95

text: Earth radii

text: . Of particular interest are the planets e and f, as they are the best candidates for solid planets falling into the habitable zone of their star. Their radii, 1.61 and 1.41 Earth radii respectively, put them in a radius range where they may be solid

text: terrestrial planet

text: s. Their positions within the Kepler-62 system mean that they fall within Kepler-62's habitable zone: the distance range where, for a given chemical composition (significant amounts of

text: carbon dioxide

text: for Kepler-62f, and a protective cloud cover for Kepler-62e), these two planets could have liquid water on their surfaces, perhaps completely covering them.   The masses of the planets could not be directly determined using either the radial velocity or the transit timing method; this failure leads to weak upper limits for the planets' masses. For e and f, that upper limit amounts to 36 and 35

text: Earth mass

text: es, respectively; the real masses are expected to be significantly lower. Based on composition models, the real masses of the planets are probably likely to be 2.1, 0.1, 5.5, 4.8, and 2.8 , respectively, taking into the uncertainty in composition and upper mass limits.

text: Based on the size of its light curve, Kepler-9d is assumed to be a Super-Earth, although its exact mass is not known. It is presumed to be at least 1.5 Earth masses. The planet's radius is inferred to be 1.64 R, or approximately 64% larger than Earth's radius. With an equilibrium temperature of 2026 K, it is hotter than all the previous planets discovered by Kepler (not counting the three previously discovered ones located in its field of view). Its density is not known.  With an average distance of .0273 AU (2,537,695.73 miles) from its star, which it orbits every 1.592851 days, Kepler-9d is the closest planet to its star in the Kepler-9 system. To compare, the planet Mercury is .3871 AU away from the Sun, which it orbits every 87.97 days.

text: Based on the size of its light curve, Kepler-9d is assumed to be a

text: Super-Earth

text: , although its exact mass is not known. It is presumed to be at least 1.5

text: Earth mass

text: es. The planet's radius is inferred to be 1.64

text: R

text: , or approximately 64% larger than Earth's radius. With an

text: equilibrium temperature

text: of 2026 K, it is hotter than all the previous planets discovered by Kepler (not counting the three previously discovered ones located in its field of view). Its density is not known.  With an

text: average distance

text: of .0273

text: AU

text: (2,537,695.73 miles) from its star, which it orbits every 1.592851 days, Kepler-9d is the closest planet to its star in the Kepler-9 system. To compare, the planet

text: Mercury

text: is .3871 AU away from the Sun, which it orbits every 87.97 days.

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: Magnetic fields can play a significant role as a source of orbit perturbation as was seen in the Long Duration Exposure Facility. Like gravity, the magnetic field of the Earth can be expressed through spherical harmonics as shown below:

text: Magnetic fields can play a significant role as a source of orbit perturbation as was seen in the

text: Long Duration Exposure Facility

text: . Like gravity, the magnetic field of the Earth can be expressed through spherical harmonics as shown below:

text: Kepler-11, known as KOI-157 when it was first flagged for a transit event, is the planet's host star, and it is included in the planet's name to denote that. Because Kepler-11f was discovered with five other planets, the planets of Kepler-11 were sorted by distance from the host star; thus, since Kepler-11f is the fifth planet  from its star, it was given the letter "f." The name "Kepler" is derived from the Kepler satellite, a NASA Earth-trailing spacecraft that constantly observes a small patch of sky between the constellations Cygnus and Lyra for stars that are transited by, in particular, terrestrial planets. As these planets cross in front of their host stars with respect to Earth, a small and periodic dip in the star's brightness occurs; this dip is noted by the spacecraft and tagged for future study. Scientists then analyze the transit event more carefully to verify if the planet actually exists and to gather information on the planet's orbit and composition (if possible).

text: Kepler-11, known as

text: KOI

text: -157 when it was first flagged for a transit event, is the planet's host star, and it is included in the planet's name to denote that. Because Kepler-11f was discovered with five other planets, the planets of Kepler-11 were sorted by distance from the host star; thus, since Kepler-11f is the fifth planet  from its star, it was given the letter "f." The name "Kepler" is derived from the

text: Kepler satellite

text: , a

text: NASA

text: Earth-trailing spacecraft that constantly observes a small patch of sky between the constellations

text: Cygnus

text: and

text: Lyra

text: for stars that are

text: transited

text: by, in particular,

text: terrestrial planet

text: s. As these planets cross in front of their host stars with respect to Earth, a small and periodic dip in the star's brightness occurs; this dip is noted by the spacecraft and tagged for future study. Scientists then analyze the transit event more carefully to verify if the planet actually exists and to gather information on the planet's orbit and composition (if possible).

text: Geodesy, also called geodetics, deals with the measurement and representation of the planets of the Solar System, their gravitational fields and geodynamic phenomena (polar motion in three-dimensional, time-varying space. The science of geodesy has elements of both astrophysics and planetary sciences. The shape of the Earth is to a large extent the result of its rotation, which causes its equatorial bulge, and the competition of geologic processes such as the collision of plates and of vulcanism, resisted by the Earth's gravity field. These principles can be applied to the solid surface of Earth (orogeny; Few mountains are higher than , few deep sea trenches deeper than that because quite simply, a mountain as tall as, for example, , would develop so much pressure at its base, due to gravity, that the rock there would become plastic, and the mountain would slump back to a height of roughly  in a geologically insignificant time. Some or all of these geologic principles can be applied to other planets besides Earth. For instance on Mars, whose surface gravity is much less, the largest volcano, Olympus Mons, is  high at its peak, a height that could not be maintained on Earth. The Earth geoid is essentially the figure of the Earth abstracted from its topographic features. Therefore, the Mars geoid is essentially the figure of Mars abstracted from its topographic features. Surveying and mapping are two important fields of application of geodesy.

text: Geodesy

text: , also called geodetics, deals with the measurement and representation of the planets of the Solar System, their

text: gravitation

text: al fields and geodynamic phenomena (

text: polar motion

text: in three-dimensional, time-varying space. The science of geodesy has elements of both astrophysics and planetary sciences. The shape of the Earth is to a large extent the result of its rotation, which causes its equatorial bulge, and the competition of geologic processes such as the collision of plates and of

text: vulcanism

text: , resisted by the Earth's

text: gravity

text: field. These principles can be applied to the solid surface of Earth (

text: orogeny

text: ; Few mountains are higher than , few deep sea trenches deeper than that because quite simply, a mountain as tall as, for example, , would develop so much

text: pressure

text: at its base, due to gravity, that the rock there would become

text: plastic

text: , and the mountain would slump back to a height of roughly  in a geologically insignificant time. Some or all of these geologic principles can be applied to other planets besides Earth. For instance on Mars, whose surface gravity is much less, the largest volcano,

text: Olympus Mons

text: , is  high at its peak, a height that could not be maintained on Earth. The Earth

text: geoid

text: is essentially the figure of the Earth abstracted from its topographic features. Therefore, the Mars geoid is essentially the figure of Mars abstracted from its topographic features.

text: Surveying

text: and

text: map

text: ping are two important fields of application of geodesy.

text: The ESA Cluster mission has enabled to find the first direct evidence of cross-scale energy transport between fluid and ion-scale waves, explaining why Earth's magnetic environment is so hot. A Nature Physics paper reveals. The Earth's internal magnetic field creates a giant protective bubble called the magnetosphere, necessary for life to develop. This magnetic bubble helps deflecting more than 99% of the incoming solar wind expelled by the Sun. Due to this interaction, the magnetosphere has a bullet-like shape (see left panel of Figure 1). At its border, the magnetopause, the matter, called plasma, is 50 times hotter inside the Earth's magnetic environment than just outside; a problem that has puzzled scientists since the beginning of the space age. Why is Earth's environment so hot? How plasma gets heated in a medium where no particles collides? One of the few physical processes enabling solar wind plasma to enter the magnetosphere is called the Kelvin-Helmholtz instability. This instability is ubiquitous in space and on Earth. Such K-H waves have been detected in various media including the surface of oceans, in clouds (see bottom right panel of Image 1), in the solar corona (see top right panel) or in the atmosphere of giant planets. Kelvin–Helmholtz (K-H) waves can form at Earth's magnetopause, mainly due to the velocity difference between the plasma flowing outside at higher speed than inside the magnetosphere. Back in 2004, the multi-spacecraft Cluster mission revealed that these waves can roll-up, turning into giant vortices of about 36,000 km size, i.e. about 6 times the Earth's radius (Hasegawa et al., 2004). A new article, published in Nature Physics this month, presents a detailed study of small-scale (ion-scale) wave packets captured by Cluster within such a macroscopic (fluid-scale) Kelvin-Helmholtz vortex. This study reveals for the first time that these wave packets in the eye of the vortex are magnetosonic waves with sufficient energy to account for the observed level of ion heating. In other words, these waves can heat the cooler ions of magnetosheath origin; magnetosheath is the boundary layer located just outside the magnetopause. These observations may be evidence for cross-scale energy transport in space plasmas. It may have universal consequences in understanding the energy transport from fluid to ion scales, and can play a role in a variety of plasma systems with a velocity shear.

text: In the year 2068 the Earth is plagued by typhoons, tsunamis, droughts, and floods. Against this apocalyptic background an Argentine scientist, Carlos Nahuel Goldstein, outlines a theory: knowing that the axis of rotation of our planet is inclined due to the gravitational force exerted by the Moon, if men were able to destroy it, the Earth would be straightened and then climate would become stabilized.

text: In the year 2068 the Earth is plagued by

text: typhoon

text: s,

text: tsunami

text: s,

text: drought

text: s, and

text: flood

text: s. Against this apocalyptic background an Argentine scientist, Carlos Nahuel Goldstein, outlines a theory: knowing that the axis of rotation of our planet is inclined due to the gravitational force exerted by the Moon, if men were able to destroy it, the Earth would be straightened and then climate would become stabilized.

text: In the final memory, the clone Emily reveals that in sixty days, Earth will be destroyed by a meteoroid. Due to the hysteria surrounding the impending apocalypse, humans have resorted to leaving the planet through different and extreme means, depending on what they can afford. Because of the unpredictable nature of physical time travel, millions of humans have transported themselves to the edges of the Earth's atmosphere, dying instantly and creating the effect of "shooting stars" when the corpses burn whilst falling through the atmosphere at night. Despite the horrible fate of humanity at this time, Emily Prime reacts joyfully to the "shooting stars", counting them while her clone describes the bleak fate of the human race.

text: In the final memory, the clone Emily reveals that in sixty days, Earth will be destroyed by a

text: meteoroid

text: . Due to the hysteria surrounding the impending apocalypse, humans have resorted to leaving the planet through different and extreme means, depending on what they can afford. Because of the unpredictable nature of physical time travel, millions of humans have transported themselves to the edges of the Earth's

text: atmosphere

text: , dying instantly and creating the effect of "

text: shooting stars

text: " when the corpses burn whilst falling through the atmosphere at night. Despite the horrible fate of humanity at this time, Emily Prime reacts joyfully to the "shooting stars", counting them while her clone describes the bleak fate of the human race.

text: Music videos for "Planet Earth" and "Careless Memories" were also filmed in December.

text: Music videos for "

text: Planet Earth

text: " and "

text: Careless Memories

text: " were also filmed in December.

text: Doppler surveys around a wide variety of stars indicate about 1 in 6 stars having twice the mass of the Sun are orbited by one or more Jupiter-sized planets, vs. 1 in 16 for Sun-like stars and only 1 in 50 for red dwarfs. On the other hand, microlensing surveys indicate that long-period Neptune-mass planets are found around 1 in 3 red dwarfs.Kepler Space Telescope observations of planets with up to one year periods show that occurrence rates of Earth- to Neptune-sized planets (1 to 4 Earth radii) around M, K, G, and F stars are successively higher towards cooler, less massive stars.

text: Doppler surveys around a wide variety of stars indicate about 1 in 6 stars having twice the mass of the Sun are orbited by one or more Jupiter-sized planets, vs. 1 in 16 for Sun-like stars and only 1 in 50 for

text: red dwarf

text: s. On the other hand,

text: microlensing

text: surveys indicate that long-period

text: Neptune

text: -mass planets are found around 1 in 3 red dwarfs.Kepler Space Telescope observations of planets with up to one year periods show that occurrence rates of Earth- to Neptune-sized planets (1 to 4 Earth radii) around M, K, G, and F stars are successively higher towards cooler, less massive stars.

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: Nicolaus Copernicus had moved the Earth away from the center of the universe with the heliocentric theory for which he presented evidence in his book De revolutionibus orbium coelestium (On the revolutions of the heavenly spheres) published in 1543. The structure was completed when Johannes Kepler wrote the book Astronomia nova (A new astronomy) in 1609, setting out the evidence that planets move in elliptical orbits with the sun at one focus, and that planets do not move with constant speed along this orbit. Rather, their speed varies so that the line joining the centres of the sun and a planet sweeps out equal areas in equal times. To these two laws he added a third a decade later, in his book Harmonices Mundi (Harmonies of the world). This law sets out a proportionality between the third power of the characteristic distance of a planet from the sun and the square of the length of its year.

text: Nicolaus Copernicus

text: had moved the Earth away from the center of the universe with the

text: heliocentric

text: theory for which he presented evidence in his book

text: De revolutionibus orbium coelestium

text: (On the revolutions of the heavenly spheres) published in 1543. The structure was completed when

text: Johannes Kepler

text: wrote the book

text: Astronomia nova

text: (A new astronomy) in 1609, setting out the evidence that planets move in

text: elliptical

text: orbits with the sun at one

text: focus

text: , and that planets do not move with constant speed along this orbit. Rather, their speed varies so that the line joining the centres of the sun and a planet sweeps out equal areas in equal times. To these two laws he added a third a decade later, in his book

text: Harmonices Mundi

text: (Harmonies of the world). This law sets out a proportionality between the third power of the characteristic distance of a planet from the sun and the square of the length of its year.

text: Solar energy and lightning cause natural variations in the earth's magnetic field, inducing electric currents (known as telluric currents) under the Earth's surface. Simultaneous measurements of orthogonal components of the electric and magnetic fields are recorded, with the results calculated as the impedance tensor. A subsurface resistivity model is then created using this tensor.

text: Solar energy

text: and

text: lightning

text: cause natural variations in the

text: earth's magnetic field

text: , inducing electric currents (known as

text: telluric current

text: s) under the Earth's surface. Simultaneous measurements of

text: orthogonal

text: components of the electric and magnetic fields are recorded, with the results calculated as the impedance tensor. A subsurface

text: resistivity

text: model is then created using this

text: tensor

text: The timing of sunrise varies throughout the year and is also affected by the viewer's longitude and latitude, altitude, and time zone. These changes are driven by the axial tilt of Earth, daily rotation of the Earth, the planet's movement in its annual elliptical orbit around the Sun, and the Earth and Moon's paired revolutions around each other. The analemma can be used to make approximate predictions of the time of sunrise.

text: The timing of sunrise varies throughout the year and is also affected by the viewer's longitude and latitude, altitude, and time zone. These changes are driven by the

text: axial tilt

text: of Earth, daily rotation of the Earth, the planet's movement in its annual

text: elliptical

text: orbit around the Sun, and the Earth and Moon's paired revolutions around each other. The

text: analemma

text: can be used to make approximate predictions of the time of sunrise.

text: Current technology limits the testing of important Rare Earth Criteria: surface water, tectonic plates, a large moon and biosignatures are currently undetectable. Though planets the size of Earth are difficult to detect and classify, scientists now think that rocky planets are common around Sun-like stars. The Earth Similarity Index (ESI) of mass, radius and temperature provides a means of measurement, but falls short of the full Rare Earth criteria.

text: Current technology limits the testing of important Rare Earth Criteria: surface water, tectonic plates, a large moon and

text: biosignature

text: s are currently undetectable. Though planets the size of Earth are difficult to detect and classify, scientists now think that rocky planets are common around Sun-like stars. The

text: Earth Similarity Index

text: (ESI) of mass, radius and temperature provides a means of measurement, but falls short of the full Rare Earth criteria.

text: The ploy works, but the Jovians—who live for millions of years and rely on an arcane and tedious system of legal councils—spend too long arguing and contemplating to successfully redirect the comet. The Instrumentality stages a successful coup, but in the end it is Dunsmoore (who has been redeemed by the threat to his home planet) who hijacks the alien gravity technology and pilots Io into a diversionary orbit around the comet itself, barely saving Earth from total annihilation—though millions die as the remnants of the comet and the sulphurous outgassing of ruined Io cascade into Earth.

text: The ploy works, but the Jovians—who live for millions of years and rely on an arcane and tedious system of legal councils—spend too long arguing and contemplating to successfully redirect the comet. The Instrumentality stages a successful coup, but in the end it is Dunsmoore (who has been redeemed by the threat to his home planet) who hijacks the alien gravity technology and pilots

text: Io

text: into a diversionary orbit around the comet itself, barely saving Earth from total annihilation—though millions die as the remnants of the comet and the sulphurous outgassing of ruined Io cascade into Earth.

text: ) is the ruling planet of Cancer and is exalted in Taurus. In Roman mythology, the Moon was Luna, at times identified with Diana. The Moon is large enough for its gravity to affect the Earth, stabilizing its orbit and producing the regular ebb and flow of the tides. The lunar day syncs up with its orbit around Earth in such a manner that the same side of the Moon always faces the Earth and the other side, known as the "far side of the Moon" faces towards space.

text: ) is the ruling planet of

text: Cancer

text: and is exalted in

text: Taurus

text: . In Roman mythology, the Moon was

text: Luna

text: , at times identified with

text: Diana

text: . The Moon is large enough for its gravity to affect the Earth, stabilizing its orbit and producing the regular ebb and flow of the tides. The

text: lunar day

text: syncs up with its orbit around Earth in such a manner that the same side of the Moon always faces the Earth and the other side, known as the "

text: far side of the Moon

text: " faces towards space.

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

entity_section: Barycenter in astrophysics and astronomy

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: Kepler-78b orbits around the parent star in an 8.5-hour orbit. It reflects 20% to 60% of the starlight it receives. Due to its extremely close solar orbit, about 40 times closer to its star than Mercury is to the Sun, the planet's surface is estimated to be at a temperature of  to . This temperature is high enough to have stripped the planet of any stable atmosphere, but the liquid and solid portions of the planet should be stable. According to Francesco Pepe, one of the astronomers involved with the discovery, the planet may be Earth-sized but "it can be imagined like a lava planet rather than an Earth-like planet."

text: Kepler-78b orbits around the parent star in an 8.5-hour orbit. It reflects 20% to 60% of the starlight it receives. Due to its extremely close solar orbit, about 40 times closer to its star than

text: Mercury

text: is to the Sun, the planet's surface is estimated to be at a temperature of  to . This temperature is high enough to have stripped the planet of any stable

text: atmosphere

text: , but the liquid and solid portions of the planet should be stable. According to Francesco Pepe, one of the astronomers involved with the discovery, the planet may be Earth-sized but "it can be imagined like a lava planet rather than an Earth-like planet."

text: Protons are charged particles and are therefore influenced by magnetic fields. When the energetic protons leave the Sun, they preferentially follow (or are guided by) the Sun's powerful magnetic field. When solar protons enter the Earth's magnetosphere where the magnetic fields are stronger than solar magnetic fields, they are guided by the Earth's magnetic field into the polar regions where the majority of the Earth's magnetic field lines enter and exit.

text: Protons are charged particles and are therefore influenced by magnetic fields. When the energetic protons leave the

text: Sun

text: , they preferentially follow (or are guided by) the Sun's powerful magnetic field. When solar protons enter the

text: Earth's magnetosphere

text: where the magnetic fields are stronger than solar magnetic fields, they are guided by the Earth's magnetic field into the polar regions where the majority of the Earth's magnetic field lines enter and exit.

text: The southern highlands display zones of intense crustal magnetization (Fig. 6). The magnetic anomalies are weak or devoid in the vicinity of large impact basins, the northern plains, and in volcanic regions, indicating that magnetization in these areas have been erased by thermal events. The presence of magnetic anomalies on Mars suggests that the planet maintained an intrinsic magnetic field early on in its history.  The anomalies are linear in shape and of alternating polarity, implying a sequence of reversals and a process akin to seafloor spreading.  The stripes are ten times wider than those found on Earth, indicating faster spreading or slower reversal rates. Although no spreading center has been identified, a map of the magnetic anomalies on Mars reveals that the lineations are concentric to the south pole.

text: Terra is a planet wracked by war caused by two large factions, one referred to as the Eastern Alliance, the other the Western Coalition. The planet was similar to the descriptions of Earth in Colonial legends, leading some to believe that Terra was in fact Earth, however the beings from the "Ship of Light" confirmed that Terra is not  Earth. It appears that the planet was settled by a splinter group of the thirteenth tribe. The Terrans use earth like measurements (such as hours and minutes) rather than Colonial measurements of centons and centars. The Terrans (the people of Terra) also use Earth names as compared to Colonial names. "Terra" means "Earth" in Latin and in the Colonial language Gemonese.

text: Terra is a planet wracked by war caused by two large factions, one referred to as the

text: Eastern Alliance

text: , the other the Western Coalition. The planet was similar to the descriptions of Earth in Colonial legends, leading some to believe that Terra was in fact Earth, however the beings from the "

text: Ship of Light

text: " confirmed that Terra is not  Earth. It appears that the planet was settled by a splinter group of the thirteenth tribe. The Terrans use earth like measurements (such as hours and minutes) rather than Colonial measurements of centons and centars. The Terrans (the people of Terra) also use Earth names as compared to Colonial names. "Terra" means "Earth" in

text: Latin

text: and in the Colonial language Gemonese.

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: A classic argument against earth motion is the lack of speed sensations of the earth surface, though it moves, by the earth's rotation, at about 1700 km/h at the equator. In this category there is a thought experiment in which a man is below decks on a ship and cannot tell whether the ship is docked or is moving smoothly through the water: he observes water dripping from a bottle, fish swimming in a tank, butterflies flying, and so on; and their behavior is just the same whether the ship is moving or not.   This is a classic exposition of the Inertial frame of reference and refutes the objection that if we were moving hundreds of kilometres an hour as the Earth rotated, anything that one dropped would rapidly fall behind and drift to the west.

text: A classic argument against earth motion is the lack of speed sensations of the earth surface, though it moves, by the earth's rotation, at about 1700 km/h at the equator. In this category there is a

text: thought experiment

text: in which a man is below decks on a

text: ship

text: and cannot tell whether the ship is docked or is moving smoothly through the water: he observes water dripping from a bottle, fish swimming in a tank, butterflies flying, and so on; and their behavior is just the same whether the ship is moving or not.   This is a classic exposition of the

text: Inertial frame of reference

text: and refutes the objection that if we were moving hundreds of kilometres an hour as the Earth rotated, anything that one dropped would rapidly fall behind and drift to the west.

text: The gravity of Earth, which is denoted by , refers to the acceleration that the Earth imparts to objects on or near its surface due to gravity. In SI units this acceleration is measured in metres per second squared (in symbols, m/s or m·s) or equivalently in newtons per kilogram (N/kg or N·kg). It has an approximate value of 9.8 m/s, which means that, ignoring the effects of air resistance, the speed of an object falling freely near the Earth's surface will increase by about  per second every second, this quantity is sometimes referred to informally as little  (in contrast, the gravitational constant  is referred to as big ).

text: The gravity of Earth, which is denoted by , refers to the

text: acceleration

text: that the

text: Earth

text: imparts to objects on or near its

text: surface

text: due to

text: gravity

text: . In

text: SI units

text: this acceleration is measured in

text: metres per second squared

text: (in symbols,

text: m

text: s

text: or m·s) or equivalently in

text: newtons

text: per

text: kilogram

text: (N/kg or N·kg). It has an approximate value of 9.8 m/s, which means that, ignoring the effects of

text: air resistance

text: , the

text: speed

text: of an object

text: falling freely

text: near the Earth's surface will increase by about  per second every second, this quantity is sometimes referred to informally as little  (in contrast, the

text: gravitational constant

text: is referred to as big ).

text: SIM Lite would have been the most powerful extrasolar planet hunting space telescope ever built. Through the technique of interferometry the spacecraft would be able to detect Earth-sized planets. SIM Lite was to perform its search for nearby, Earth-like planets by looking for the "wobble" in the parent star's apparent motion as the planet orbits. The spacecraft will accomplish this task to an accuracy of one millionth of an arcsecond, or the thickness of a nickel viewed at the distance from Earth to the Moon. Titled the Deep Search, the planet hunting program is intended to search approximately 60 nearby stars for terrestrial planets (like Earth and Venus) in the habitable zone (where liquid water can exist throughout a full revolution (one "year") of the planet around its star). The Deep Search is the most demanding in terms of astrometric accuracy, hence the name, Deep Search. This program will use the full capability of the SIM Lite spacecraft to make its measurements.

text: SIM Lite would have been the most powerful

text: extrasolar planet

text: hunting

text: space telescope

text: ever built. Through the technique of

text: interferometry

text: the spacecraft would be able to detect Earth-sized planets. SIM Lite was to perform its search for nearby, Earth-like planets by looking for the "

text: wobble

text: " in the parent star's apparent motion as the planet orbits. The spacecraft will accomplish this task to an accuracy of one millionth of an

text: arcsecond

text: , or the thickness of a

text: nickel

text: viewed at the distance from Earth to the

text: Moon

text: . Titled the Deep Search, the planet hunting program is intended to search approximately 60 nearby stars for

text: terrestrial planets

text: (like

text: Earth

text: and

text: Venus

text: ) in the habitable zone (where liquid water can exist throughout a full revolution (one "year") of the planet around its star). The Deep Search is the most demanding in terms of

text: astrometric

text: accuracy, hence the name, Deep Search. This program will use the full capability of the SIM Lite spacecraft to make its measurements.

text: Mars has an axial tilt of 25.2°. This means that there are seasons on Mars, just as on Earth. The eccentricity of Mars' orbit is 0.1, much greater than the Earth's present orbital eccentricity of about 0.02. The large eccentricity causes the insolation on Mars to vary as the planet orbits the Sun. (The Martian year lasts 687 days, roughly 2 Earth years.) As on Earth, Mars' obliquity dominates the seasons but, because of the large eccentricity, winters in the southern hemisphere are long and cold while those in the North are short and warm.

text: Mars

text: has an

text: axial tilt

text: of 25.2°. This means that there are seasons on Mars, just as on Earth. The

text: eccentricity

text: of Mars' orbit is 0.1, much greater than the Earth's present orbital eccentricity of about 0.02. The large eccentricity causes the

text: insolation

text: on Mars to vary as the planet orbits the Sun. (The Martian year lasts 687 days, roughly 2 Earth years.) As on Earth, Mars'

text: obliquity

text: dominates the seasons but, because of the large eccentricity, winters in the southern hemisphere are long and cold while those in the North are short and warm.

text: The fact that many large celestial objects are approximately spheres makes it easier to calculate their surface gravity. The gravitational force outside a spherically symmetric body is the same as if its entire mass were concentrated in the center, as was established by Sir Isaac Newton. Therefore, the surface gravity of a planet or star with a given mass will be approximately inversely proportional to the square of its radius, and the surface gravity of a planet or star with a given average density will be approximately  proportional to its radius. For example, the recently discovered planet, Gliese 581 c, has at least 5 times the mass of Earth, but is unlikely to have 5 times its surface gravity. If its mass is no more than 5 times that of the Earth, as is expected, and if it is a rocky planet with a large iron core, it should have a radius approximately 50% larger than that of Earth. Gravity on such a planet's surface would be approximately 2.2 times as strong as on Earth. If it is an icy or watery planet, its radius might be as large as twice the Earth's, in which case its surface gravity might be no more than 1.25 times as strong as the Earth's.

text: The fact that many large celestial objects are approximately spheres makes it easier to calculate their surface gravity. The gravitational force outside a spherically symmetric body is the same as if its entire mass were concentrated in the center, as was established by

text: Sir Isaac Newton

text: . Therefore, the surface gravity of a

text: planet

text: or

text: star

text: with a given mass will be approximately inversely proportional to the square of its

text: radius

text: , and the surface gravity of a planet or star with a given average density will be approximately  proportional to its radius. For example, the recently discovered

text: planet

text: Gliese 581 c

text: , has at least 5 times the mass of Earth, but is unlikely to have 5 times its surface gravity. If its mass is no more than 5 times that of the Earth, as is expected, and if it is a rocky planet with a large iron core, it should have a radius approximately 50% larger than that of Earth. Gravity on such a planet's surface would be approximately 2.2 times as strong as on Earth. If it is an icy or watery planet, its radius might be as large as twice the Earth's, in which case its surface gravity might be no more than 1.25 times as strong as the Earth's.

text: Another recently developed source of rare earths is electronic waste and other wastes that have significant rare earth components. New advances in recycling technology have made extraction of rare earths from these materials more feasible, and recycling plants are currently operating in Japan, where there is an estimated 300,000 tons of rare earths stored in unused electronics. In France, the Rhodia group is setting up two factories, in La Rochelle and Saint-Fons, that will produce 200 tons of rare earths a year from used fluorescent lamps, magnets and batteries.

text: Another recently developed source of rare earths is

text: electronic waste

text: and other

text: waste

text: s that have significant rare earth components. New advances in

text: recycling technology

text: have made extraction of rare earths from these materials more feasible, and recycling plants are currently operating in Japan, where there is an estimated 300,000 tons of rare earths stored in unused electronics. In

text: France

text: , the

text: Rhodia

text: group is setting up two factories, in

text: La Rochelle

text: and

text: Saint-Fons

text: , that will produce 200 tons of rare earths a year from used

text: fluorescent lamp

text: s, magnets and batteries.

text: Earth's average surface temperature due to its albedo and the greenhouse effect is currently about 15 °C. If Earth were frozen entirely (and hence be more reflective) the average temperature of the planet would drop below −40 °C. If only the continental land masses became covered by glaciers, the mean temperature of the planet would drop to about 0 °C. In contrast, if the entire Earth is covered by water—a so-called aquaplanet—the average temperature on the planet would rise to just under 27 °C.

text: Earth's average surface temperature due to its albedo and the

text: greenhouse effect

text: is currently about 15 °C. If Earth were frozen entirely (and hence be more reflective) the average temperature of the planet would drop below −40 °C. If only the continental land masses became covered by glaciers, the mean temperature of the planet would drop to about 0 °C. In contrast, if the entire Earth is covered by water—a so-called aquaplanet—the average temperature on the planet would rise to just under 27 °C.

text: Three confirmed planets and two possible planets are possibly known to orbit Gliese 581, together with a debris disc. Most of the planets are located close to the star and have near-circular orbits. In order of distance from the star, the planets are designated Gliese 581 e, Gliese 581 b and Gliese 581 c and possibly Gliese 581 g and Gliese 581 d. The letters represent the discovery order, with b being the first planet to be discovered around the star (the letter d was used for a planet that was once no longer thought to be real and was an artifact caused by stellar activity, but reanalysis led to the conclusion that d might exist). The planets were all discovered with the radial velocity method which gives only lower limits on the planetary masses and no information about their radii. The minimum mass of the middle planet b is comparable to the solar system ice giants Uranus and Neptune, while the inner and outer planets have minimum masses a few times that of the Earth. The first three planets orbit closer to the star than the inner edge of the habitable zone, with the possibly reconfirmed planets Gliese 581 g and Gliese 581 d orbiting within the habitable zone.

text: Three confirmed planets and two possible planets are possibly known to orbit Gliese 581, together with a debris disc. Most of the planets are located close to the star and have near-circular orbits. In order of distance from the star, the planets are designated

text: Gliese 581 e

text: Gliese 581 b

text: and

text: Gliese 581 c

text: and possibly

text: Gliese 581 g

text: and

text: Gliese 581 d

text: . The letters represent the discovery order, with b being the first planet to be discovered around the star (the letter d was used for a planet that was once no longer thought to be real and was an artifact caused by stellar activity, but reanalysis led to the conclusion that

text: d

text: might exist). The planets were all discovered with the radial velocity method which gives only lower limits on the planetary masses and no information about their radii. The minimum mass of the middle planet b is comparable to the solar system ice giants

text: Uranus

text: and

text: Neptune

text: , while the inner and outer planets have minimum masses a few times that of the Earth. The first three planets orbit closer to the star than the inner edge of the habitable zone, with the possibly reconfirmed planets

text: Gliese 581 g

text: and

text: Gliese 581 d

text: orbiting within the habitable zone.

text: Other planets have different seasonal lags. The gas giants Jupiter, Saturn and Uranus, as well as Saturn's moon Titan, all have substantial seasonal lags corresponding to the equivalent of between two and three months in Earth terms. Mars, on the other hand, has negligible seasonal lag of no more than a few days. For the case of Venus no seasonal lag would be detected, because the planet undergoes no seasons due to very efficient heat transport in its massive atmosphere. This is also the case for Mercury, even for its "anomalistical seasons", since it has negligible atmosphere and so undergoes almost instantaneous heating and cooling.

text: Other planets have different seasonal lags. The gas giants

text: Jupiter

text: Saturn

text: and

text: Uranus

text: , as well as Saturn's moon

text: Titan

text: , all have substantial seasonal lags corresponding to the equivalent of between two and three months in Earth terms.

text: Mars

text: , on the other hand, has negligible seasonal lag of no more than a few days. For the case of

text: Venus

text: no seasonal lag would be detected, because the planet undergoes no seasons due to very efficient heat transport in its massive atmosphere. This is also the case for

text: Mercury

text: , even for its "

text: anomalistical

text: seasons", since it has negligible atmosphere and so undergoes almost instantaneous heating and cooling.

text: In 1973, George W. Moore of the USGS and R. C. Bostrom presented evidence for a general westward drift of the Earth's lithosphere with respect to the mantle.  He concluded that tidal forces (the tidal lag or "friction") caused by the Earth's rotation and the forces acting upon it by the Moon are a driving force for plate tectonics.  As the Earth spins eastward beneath the moon, the moon's gravity ever so slightly pulls the Earth's surface layer back westward, just as proposed by Alfred Wegener (see above). In a more recent 2006 study, scientists reviewed and advocated these earlier proposed ideas. It has also been suggested recently in  that this observation may also explain why Venus and Mars have no plate tectonics, as Venus has no moon and Mars' moons are too small to have significant tidal effects on the planet. In a recent paper, it was suggested that, on the other hand, it can easily be observed that many plates are moving north and eastward, and that the dominantly westward motion of the Pacific Ocean basins derives simply from the eastward bias of the Pacific spreading center (which is not a predicted manifestation of such lunar forces). In the same paper the authors admit, however, that relative to the lower mantle, there is a slight westward component in the motions of all the plates. They demonstrated though that the westward drift, seen only for the past 30 Ma, is attributed to the increased dominance of the steadily growing and accelerating Pacific plate. The debate is still open.

text: In 1973, George W. Moore of the

text: USGS

text: and R. C. Bostrom presented evidence for a general westward drift of the Earth's lithosphere with respect to the mantle.  He concluded that tidal forces (the tidal lag or "friction") caused by the Earth's rotation and the forces acting upon it by the Moon are a driving force for plate tectonics.  As the Earth spins eastward beneath the moon, the moon's gravity ever so slightly pulls the Earth's surface layer back westward, just as proposed by Alfred Wegener (see above). In a more recent 2006 study, scientists reviewed and advocated these earlier proposed ideas. It has also been suggested recently in  that this observation may also explain why

text: Venus

text: and

text: Mars

text: have no plate tectonics, as Venus has no moon and Mars' moons are too small to have significant tidal effects on the planet. In a recent paper, it was suggested that, on the other hand, it can easily be observed that many plates are moving north and eastward, and that the dominantly westward motion of the Pacific Ocean basins derives simply from the eastward bias of the Pacific spreading center (which is not a predicted manifestation of such lunar forces). In the same paper the authors admit, however, that relative to the lower mantle, there is a slight westward component in the motions of all the plates. They demonstrated though that the westward drift, seen only for the past 30 Ma, is attributed to the increased dominance of the steadily growing and accelerating Pacific plate. The debate is still open.

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: On July 17, 2012, five years after his last mix compilation, Sharam released a two-disc set  called Night and Day. Based on the concept that people want to listen to music at different times—a dance party at night; a pool party during the day—the mix compilation took a “big festival” and “small club” approach.

text: On July 17, 2012, five years after his last mix compilation, Sharam released a two-disc set  called

text: Night and Day

text: . Based on the concept that people want to listen to music at different times—a dance party at night; a pool party during the day—the mix compilation took a “big festival” and “small club” approach.

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: While the earth and planets revolved around a central point in Philolaus's system, his could not be called a Heliocentric "solar system", because the central point the Earth and Planets revolved around was not the Sun, but the so-called Central Fire. This Fire was not visible from the surface of Earth—or at least not from the hemisphere Greece was located in.

text: While the earth and planets revolved around a central point in Philolaus's system, his could not be called a

text: Heliocentric

text: "solar system", because the central point the Earth and Planets revolved around was not the Sun, but the so-called Central Fire. This Fire was not visible from the surface of Earth—or at least not from the hemisphere Greece was located in.

text: Reichenbach expanded on the work of previous scientists, such as Galileo Galilei, who believed the Earth's axis was magnetically connected to a universal central force in space, in concluding that Earth's magnetism comes from magnetic iron, which can be found in meteorites. His reasoning was that meteorites and planets are the same, and no matter the size of the meteorite, polar existence can be found in the object. This was deemed conclusive by the scientific community in the 19th century.

text: Reichenbach expanded on the work of previous scientists, such as

text: Galileo Galilei

text: , who believed the Earth's axis was magnetically connected to a universal central force in space, in concluding that Earth's magnetism comes from magnetic iron, which can be found in meteorites. His reasoning was that meteorites and planets are the same, and no matter the size of the meteorite, polar existence can be found in the object. This was deemed conclusive by the scientific community in the 19th century.

text: Cal is an alien from the planet Antar, a servant of that planet's ruler Zan. When Zan, his wife Ava, his sister Vilandra, and Vilandra's betrothed spouse Rath were killed by a revolution brought on by their enemy Kivar, Langley (his Antarian name is unknown) was part of a plan to return the "Royal Four" to the power. The followers of the Royal Four copied their DNA and mixed it with that of inhabitants of the planet Earth. They created two sets of these clones, as a security measure. The embryos of the clones were sent to Earth with Langley and another follower, known later on Earth as Nasedo (his Antarian name is also unknown). Langley and Nasedo would each take their respective set of clone embryos, which would take over fifty years to gestate, to a separate location on Earth, and raise them there. When they reached adulthood, one set of them was to be taken back to Antar to depose Kivar and rule once again.After the ship crashed, Langley took his embryos to New York City, and placed them in a storage locker. But, after years of living on Earth, disguised as a human, he decided to neglect his duty as protector, and did not oversee the hatching of the pods. His clones of the Royal Four therefore grew up on the streets of New York. Langley kept tabs on them, however, as well as the group that grew up in Roswell. He went on to become a wealthy Hollywood producer and four-time Academy Award winner.

text: Cal is an alien from the planet Antar, a servant of that planet's ruler

text: Zan

text: . When Zan, his wife

text: Ava

text: , his sister

text: Vilandra

text: , and Vilandra's betrothed spouse

text: Rath

text: were killed by a revolution brought on by their enemy

text: Kivar

text: , Langley (his Antarian name is unknown) was part of a plan to return the "Royal Four" to the power. The followers of the Royal Four copied their DNA and mixed it with that of inhabitants of the planet Earth. They created two sets of these clones, as a security measure. The embryos of the clones were sent to Earth with Langley and another follower, known later on Earth as Nasedo (his Antarian name is also unknown). Langley and Nasedo would each take their respective set of clone embryos, which would take over fifty years to gestate, to a separate location on Earth, and raise them there. When they reached adulthood, one set of them was to be taken back to Antar to depose Kivar and rule once again.After the ship crashed, Langley took his embryos to New York City, and placed them in a storage locker. But, after years of living on Earth, disguised as a human, he decided to neglect his duty as protector, and did not oversee the hatching of the pods. His clones of the Royal Four therefore grew up on the streets of New York. Langley kept tabs on them, however, as well as the group that grew up in Roswell. He went on to become a wealthy Hollywood producer and four-time

text: Academy Award

text: winner.

text: The end of the Chaotian was marked by the hypothetical collision of the proto-Earth and a planet-sized body named Theia, leading to the formation of the Moon.

text: The end of the Chaotian was marked by the hypothetical

text: collision

text: of the proto-Earth and a planet-sized body named

text: Theia

text: , leading to the formation of the Moon.

text: Telluric currents are phenomena observed in the Earth's crust and mantle. In September 1862, an experiment to specifically address Earth currents was carried out in the Munich Alps (Lamont, 1862). The currents are primarily geomagnetically induced currents, which are induced by changes in the outer part of the Earth's magnetic field, which are usually caused by interactions between the solar wind and the magnetosphere or solar radiation effects on the ionosphere.  Telluric currents flow in the surface layers of the earth. The electric potential on the Earth's surface can be measured at different points, enabling the calculation of the magnitudes and directions of the telluric currents and hence the Earth's conductance. These currents are known to have diurnal characteristics wherein the general direction of flow is towards the sun. Telluric currents continuously move between the sunlit and shadowed sides of the earth, toward the equator on the side of the earth facing the sun (that is, during the day), and toward the poles on the night side of the planet.

text: Telluric currents are phenomena observed in the Earth's

text: crust

text: and

text: mantle

text: . In September 1862, an experiment to specifically address Earth currents was carried out in the Munich Alps (Lamont, 1862). The currents are primarily

text: geomagnetically induced current

text: s, which are induced by changes in the outer part of the

text: Earth's magnetic field

text: , which are usually caused by interactions between the

text: solar wind

text: and the

text: magnetosphere

text: or solar radiation effects on the

text: ionosphere

text: .  Telluric currents flow in the surface layers of the earth. The electric potential on the Earth's surface can be measured at different points, enabling the calculation of the magnitudes and directions of the telluric currents and hence the Earth's

text: conductance

text: . These currents are known to have

text: diurnal

text: characteristics wherein the general direction of flow is towards the sun. Telluric currents continuously move between the sunlit and shadowed sides of the earth, toward the equator on the side of the earth facing the sun (that is, during the day), and toward the poles on the night side of the planet.

text: By citing the previous research of Edward Sabine, which established a correlation between sunspots and magnetic storms, Stewart was able to correctly advance the theory that the event observed by Richard Carrington and the magnetic disturbance that was recorded at the same time were in fact connected. The magnetic phenomena that occurred at about 11:18 GMT on 1 September 1859 are now known as a Solar Flare Effect (SFE) or a Magnetic Crochet, but the connection would not be proven for another 80 years. The SFE is a sudden ionosphere disturbances caused by soft X-rays and Extreme ultraviolet (EUV) driven enhancement of the ionosphere current vortices responsible for the regular daily variation observed on magnetometer traces. SFE are mostly observed in locations close to the sub-solar point (i.e. the point on earth when the sun is overhead) and can only be observed from stations in the sunlit hemisphere at the time of the solar flare. Using Stewart’s times, the magnetic storm associated with the Carrington Super Flare took 17 hours and 45 minutes to reach the Earth.

text: By citing the previous research of

text: Edward Sabine

text: , which established a correlation between

text: sunspots

text: and

text: magnetic storm

text: s, Stewart was able to correctly advance the theory that the event observed by

text: Richard Carrington

text: and the magnetic disturbance that was recorded at the same time were in fact connected. The magnetic phenomena that occurred at about 11:18 GMT on 1 September 1859 are now known as a Solar Flare Effect (SFE) or a Magnetic Crochet, but the connection would not be proven for another 80 years. The SFE is a sudden ionosphere disturbances caused by

text: soft X-rays

text: and

text: Extreme ultraviolet

text: (EUV) driven enhancement of the ionosphere current vortices responsible for the regular daily variation observed on magnetometer traces. SFE are mostly observed in locations close to the sub-solar point (i.e. the point on earth when the sun is overhead) and can only be observed from stations in the sunlit hemisphere at the time of the solar flare. Using Stewart’s times, the

text: magnetic storm

text: associated with the

text: Carrington Super Flare

text: took 17 hours and 45 minutes to reach the Earth.

text: The habitable zone around a star is the region where the temperature is just right to allow liquid water to exist on a planet; that is, not too close to the star for the water to evaporate and not too far away from the star for the water to freeze. The heat produced by stars varies depending on the size and age of the star, so that the habitable zone can be at different distances for different stars. Also, the atmospheric conditions on the planet influence the planet's ability to retain heat so that the location of the habitable zone is also specific to each type of planet: desert planets (also known as dry planets), with very little water, will have less water vapor in the atmosphere than Earth and so have a reduced greenhouse effect, meaning that a desert planet could maintain oases of water closer to its star than Earth is to the Sun. The lack of water also means there is less ice to reflect heat into space, so the outer edge of desert-planet habitable zones is further out. Rocky planets with a thick hydrogen atmosphere could maintain surface water much further out than the Earth–Sun distance. Planets with larger mass have wider habitable zones because the gravity reduces the water cloud column depth which reduces the greenhouse effect of water vapor, thus moving the inner edge of the habitable zone closer to the star.

text: The

text: habitable zone

text: around a star is the region where the temperature is just right to allow liquid water to exist on a planet; that is, not too close to the star for the water to evaporate and not too far away from the star for the water to freeze. The heat produced by stars varies depending on the size and age of the star, so that the habitable zone can be at different distances for different stars. Also, the atmospheric conditions on the planet influence the planet's ability to retain heat so that the location of the habitable zone is also specific to each type of planet:

text: desert planet

text: s (also known as dry planets), with very little water, will have less water vapor in the atmosphere than Earth and so have a reduced greenhouse effect, meaning that a desert planet could maintain oases of water closer to its star than Earth is to the Sun. The lack of water also means there is less ice to reflect heat into space, so the outer edge of desert-planet habitable zones is further out. Rocky planets with a thick hydrogen atmosphere could maintain surface water much further out than the Earth–Sun distance. Planets with larger mass have wider habitable zones because the gravity reduces the water cloud column depth which reduces the greenhouse effect of water vapor, thus moving the inner edge of the habitable zone closer to the star.

text: In the second season of the series, a new set of aliens arrive on Earth, said to be the same race as those from the Mor-Tax. However, these aliens call the planet Morthrai, and themselves Morthren, which is seen exploding in the very first shot of the premiere episode. In the final episode, it is stated that the Morthren were unaware of any other intelligent lifeforms until the discovery of Earth in 1945 and it took sometime less than a year to reach the planet from theirs - statements which both deviate from the information given above.

text: The conclusion: These canons are observed even under the erection of bridges and breeding of cattle. The inhabitant of distant planet, who observed the cataclysms of Russian revolution, could conclude that the cows and bridges are valued more expensively on the Earth than human life.

text: The Earth's rotation is not even. Any motion in/on the Earth causes a slowdown or speedup of the rotation, or a change of rotation axis. Most of them can be ignored, but movements of very large mass, like sea current or tide can produce discernible changes and cause error to very precise astronomical observations.

text: The Earth's rotation is not even. Any motion in/on the Earth causes a slowdown or speedup of the rotation, or a change of rotation axis. Most of them can be ignored, but movements of very large mass, like

text: sea current

text: or

text: tide

text: can produce discernible changes and cause error to very precise astronomical observations.

text: Although the Sun appears to rotate nearly uniformly about the Earth, it is not perfectly uniform. This is due to the ellipticity of the Earth's orbit (the fact that the Earth's orbit about the Sun is not perfectly circular) and the tilt (obliquity) of the Earth's rotational axis relative to the plane of its orbit. Therefore, sundials time varies from standard clock time. On four days of the year, the correction is effectively zero. However, on others, it can be as much as a quarter-hour early or late. The amount of correction is described by the equation of time. This correction is universal; it does not depend on the local latitude of the sundial. It does, however, change over long periods of time, centuries or more, because of slow variations in the Earth's orbital and rotational motions. Therefore, tables and graphs of the equation of time that were made centuries ago are now significantly incorrect. The reading of an old sundial should be corrected by applying the present-day equation of time, not one from the period when the dial was made.

text: Although the Sun appears to rotate nearly uniformly about the Earth, it is not perfectly uniform. This is due to the ellipticity of the Earth's orbit (the fact that the Earth's orbit about the Sun is not perfectly circular) and the tilt (obliquity) of the Earth's rotational axis relative to the plane of its orbit. Therefore, sundials time varies from

text: standard clock time

text: . On four days of the year, the correction is effectively zero. However, on others, it can be as much as a quarter-hour early or late. The amount of correction is described by the

text: equation of time

text: . This correction is universal; it does not depend on the local latitude of the sundial. It does, however, change over long periods of time, centuries or more, because of slow variations in the Earth's orbital and rotational motions. Therefore, tables and graphs of the equation of time that were made centuries ago are now significantly incorrect. The reading of an old sundial should be corrected by applying the present-day equation of time, not one from the period when the dial was made.

text: A companion book to the series written by Jonathan Weiner, also entitled Planet Earth, was published in 1986 by Bantam Books. Both the series and the companion book sometimes are marketed as Our Planet Earth in an attempt to avoid confusion with the 2006 BBC series Planet Earth.

text: A companion book to the series written by

text: Jonathan Weiner

text: , also entitled Planet Earth, was published in 1986 by

text: Bantam Books

text: . Both the series and the companion book sometimes are marketed as Our Planet Earth in an attempt to avoid confusion with the 2006

text: BBC

text: series

text: Planet Earth

text: In the year 2300, the human race created an Earth federation government and spread out into space to begin colonizing the surrounding planets. However, an alien species from the far reaches of outer space began attacking the human forces, putting the very survival of the human race at stake. Though it was only a matter of time before Earth fell to the enormous power of the enemy forces, the Earth's army commander issued an order calling all of the units dispersed around the colonized planets to return to Earth. The player takes the role of a young soldier who was stationed with the Rayieza unit on the planet Mars. The journey begins as he makes his way back to Earth along with the other members of his unit.

text: In the year 2300, the human race created an Earth federation government and spread out into space to begin colonizing the surrounding planets. However, an alien species from the far reaches of outer space began attacking the human forces, putting the very survival of the human race at stake. Though it was only a matter of time before Earth fell to the enormous power of the enemy forces, the Earth's army commander issued an order calling all of the units dispersed around the colonized planets to return to Earth. The player takes the role of a young soldier who was stationed with the Rayieza unit on the planet

text: Mars

text: . The journey begins as he makes his way back to Earth along with the other members of his unit.

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: The acceleration of gravity on the planet surface is estimated to be ~11 m/s, slightly larger than Earth's.

text: The map also incorporates an explanation of parallels and meridians, a proof that the sun is larger than the moon, a table showing the distances of planets from the earth, an explanation of the varying lengths of days and nights, and polar projections of the earth that are unusually consistent with its main map.

text: The book depicts a future where humankind has left the Earth due to global warming, and they have decided to live in the International Space Station. There are 3.2 million residents in this future city in space, called AstroTown. The inhabitants decided to stay in the space station instead of colonizing other planets. We learn from the story that it would be easier to adapt to zero gravity than to send the entire city to a new planet. There is no mention of extraterrestrial life or super powers of any kind. At first, AstroTown is governed by a dictatorship, but the society stages a revolution to overthrow the dictator when a “normal human being,” cloned from the time when the humans lived on Earth, appears on the scene.

text: The book depicts a future where humankind has left the Earth due to

text: global warming

text: , and they have decided to live in the

text: International Space Station

text: . There are 3.2 million residents in this future city in space, called AstroTown. The inhabitants decided to stay in the space station instead of colonizing other planets. We learn from the story that it would be easier to adapt to

text: zero gravity

text: than to send the entire city to a new planet. There is no mention of extraterrestrial life or super powers of any kind. At first, AstroTown is governed by a

text: dictatorship

text: , but the society stages a

text: revolution

text: to overthrow the dictator when a “normal human being,” cloned from the time when the humans lived on

text: Earth

text: , appears on the scene.

text: Rare-earth magnets are strong permanent magnets made from alloys of rare earth elements (elements in the lanthanide series, plus scandium and yttrium).  Developed in the 1970s and '80s, rare-earth magnets are the strongest type of permanent magnets made, producing significantly stronger magnetic fields than other types such as ferrite or alnico magnets. The magnetic field typically produced by rare-earth magnets can exceed 1.4 teslas, whereas ferrite or ceramic magnets typically exhibit fields of 0.5 to 1 tesla.  There are two types: neodymium magnets and samarium-cobalt magnets. Magnetostrictive rare-earth magnets such as Terfenol-D also have applications—e.g. in loudspeakers. Rare earth magnets are extremely brittle and also vulnerable to corrosion, so they are usually plated or coated to protect them from breaking, chipping, or crumbling into powder.

text: Rare-earth magnets are strong

text: permanent magnet

text: s made from

text: alloy

text: s of

text: rare earth element

text: s (elements in the

text: lanthanide

text: series, plus

text: scandium

text: and

text: yttrium

text: ).  Developed in the 1970s and '80s, rare-earth magnets are the strongest type of permanent magnets made, producing significantly stronger magnetic fields than other types such as

text: ferrite

text: or

text: alnico

text: magnets. The

text: magnetic field

text: typically produced by rare-earth magnets can exceed 1.4

text: teslas

text: , whereas ferrite or ceramic magnets typically exhibit fields of 0.5 to 1 tesla.  There are two types:

text: neodymium magnet

text: s and

text: samarium-cobalt magnet

text: s.

text: Magnetostrictive

text: rare-earth magnets such as

text: Terfenol-D

text: also have applications—e.g. in

text: loudspeaker

text: s. Rare earth magnets are extremely

text: brittle

text: and also vulnerable to

text: corrosion

text: , so they are usually

text: plated

text: or

text: coated

text: to protect them from breaking, chipping, or crumbling into powder.

text: Counter-Earth was created by Franklin to greatly resemble his own world, and many elements on Earth-616 have an equivalent of some sort there (For example, although Counter-Earth's Captain America was actually the displaced Steve Rogers of Earth-616, both planets have their own Nick Fury). The Counter-Earth versions of the Young Allies, Lady Dorma, Otto Octavius, the Masters of Evil, and the Master Man have risen to prominence following the departure of the Earth-616 heroes, as well as individuals with no known Earth-616 counterpart, such as Rebel O'Reilly and Lancer. The Rip, a dual entity representing order (as "O") and chaos (as "Kay") emerged to announce its duty to decide the final fate of Counter-Earth.

text: Counter-Earth was created by Franklin to greatly resemble his own world, and many elements on Earth-616 have an equivalent of some sort there (For example, although Counter-Earth's

text: Captain America

text: was actually the displaced Steve Rogers of Earth-616, both planets have their own

text: Nick Fury

text: ). The Counter-Earth versions of the

text: Young Allies

text: Lady Dorma

text: Otto Octavius

text: , the

text: Masters of Evil

text: , and the

text: Master Man

text: have risen to prominence following the departure of the Earth-616 heroes, as well as individuals with no known Earth-616 counterpart, such as Rebel O'Reilly and Lancer. The Rip, a dual entity representing order (as "O") and chaos (as "Kay") emerged to announce its duty to decide the final fate of Counter-Earth.

text: There are a number of puzzling features of this candidate, which have led to a large amount of skepticism. The source is located between the constellations Pisces and Aries, a direction in which no stars are observed within 1000 light years of Earth. It is also a very weak signal. The frequency of the signal has a rapid drift of between 8 and 37 hertz per second, which would correspond to emission from a planet rotating nearly 40 times faster on its axis than the Earth. Each time the signal was detected, it was again at about 1420 MHz, the original frequency before any drift.

text: There are a number of puzzling features of this candidate, which have led to a large amount of skepticism. The source is located between the

text: constellation

text: s

text: Pisces

text: and

text: Aries

text: , a direction in which no

text: star

text: s are observed within 1000

text: light year

text: s of

text: Earth

text: . It is also a very weak signal. The frequency of the signal has a rapid

text: drift

text: of between 8 and 37 hertz per second, which would correspond to emission from a

text: planet

text: rotating nearly 40 times faster on its axis than the Earth. Each time the signal was detected, it was again at about 1420 MHz, the original frequency before any drift.

text: Megatron recruits Orion Pax, who has no memory of the Autobot-Decepticon war, into the Decepticons and manipulates him into believing that the Autobots are evil. Jack and Arcee travel to Cybertron to find the legendary super-computer Vector Sigma, and the Autobots successfully restore Optimus's memories with the information stored inside it. With the departure of Starscream and Airachnid, and the murder of Breakdown, the Decepticons suffer a prolonged period of infighting as Megatron struggles to keep his troops in line. Having been convinced by the events of the first season finale that Megatron is beyond hope of redemption, Optimus has resolved to kill Megatron at any cost, a choice he still struggles with in the season. The main theme for the majority of the second season is the discovery of ancient relics and weaponry from Cybertron buried on Earth, with the Transformers fighting over each new discovery. Among the relics hidden on Earth are the four Omega Keys, which activate the Omega Lock, an ancient machine capable of making Cybertron habitable again. The Decepticons acquire all four keys when Starscream returns to Megatron's command, and plan to terraform Earth into a mechanical planet like Cybertron, which would kill all life on Earth. Optimus Prime destroys the Omega Lock to save Earth, but before its destruction the Lock creates a massive fortress in the Nevada desert, and the Decepticons destroy the Autobot base with Optimus still inside.

text: Megatron recruits Orion Pax, who has no memory of the Autobot-Decepticon war, into the Decepticons and manipulates him into believing that the Autobots are evil. Jack and Arcee travel to Cybertron to find the legendary super-computer Vector Sigma, and the Autobots successfully restore Optimus's memories with the information stored inside it. With the departure of Starscream and Airachnid, and the murder of Breakdown, the Decepticons suffer a prolonged period of infighting as Megatron struggles to keep his troops in line. Having been convinced by the events of the first season finale that Megatron is beyond hope of redemption, Optimus has resolved to kill Megatron at any cost, a choice he still struggles with in the season. The main theme for the majority of the second season is the discovery of

text: ancient relics and weaponry

text: from Cybertron buried on Earth, with the Transformers fighting over each new discovery. Among the relics hidden on Earth are the four Omega Keys, which activate the Omega Lock, an ancient machine capable of making Cybertron habitable again. The Decepticons acquire all four keys when Starscream returns to Megatron's command, and plan to

text: terraform

text: Earth into a mechanical planet like Cybertron, which would kill all life on Earth. Optimus Prime destroys the Omega Lock to save Earth, but before its destruction the Lock creates a massive fortress in the Nevada desert, and the Decepticons destroy the Autobot base with Optimus still inside.

text: This is the smaller world, with 0.76 Earth masses at 94% of its diameter, and 85% of its surface gravity. The mean surface temperature is only +5 °C. Because most of this chilly planet's water is locked in permafrost and glaciers, the atmosphere (which has a sea-level pressure of 0.7 bar, equivalent to about 3,650 m altitude on Earth) is not only thin but also uncomfortably dry. From the hemisphere where the companion world Genji can be seen it hangs in the sky as a globe of 6° 20' diameter, and when full gives over 320 times the light of the full Moon as seen from Earth.

text: This is the smaller world, with 0.76 Earth masses at 94% of its diameter, and 85% of its surface gravity. The mean surface temperature is only +5 °C. Because most of this chilly planet's water is locked in

text: permafrost

text: and glaciers, the atmosphere (which has a sea-level pressure of 0.7 bar, equivalent to about 3,650 m altitude on Earth) is not only thin but also uncomfortably dry. From the hemisphere where the companion world Genji can be seen it hangs in the sky as a globe of 6° 20' diameter, and when full gives over 320 times the light of the full Moon as seen from Earth.

text: Meanwhile, X-51 decides that the inhabitants of alternate Earths should be warned about the Celestial embryos he believes are growing within their planets. He spreads the alarm across the multiverse by recruiting and dispatching Heralds from alternate timelines such as Bloodstorm (Ororo Monroe, Earth-1298), Deathlok (Luther Manning, Earth-7484), Hyperion (Earth-1121), Killraven (Earth-691), Iron Man 2020 (Earth-8410), Spider-Girl (Earth-1122), and Wolverine (Days of Future Past Earth-811).

text: Meanwhile, X-51 decides that the inhabitants of alternate Earths should be warned about the Celestial embryos he believes are growing within their planets. He spreads the alarm across the multiverse by recruiting and dispatching Heralds from alternate timelines such as

text: Bloodstorm

text: (Ororo Monroe, Earth-1298),

text: Deathlok

text: (Luther Manning, Earth-7484),

text: Hyperion

text: Killraven

text: Iron Man 2020

text: Spider-Girl

text: (Earth-1122), and

text: Wolverine

text: Days of Future Past

text: Most auroras occur in a band known as the auroral zone, which is typically 3° to 6° wide in latitude and between 10° and 20° from the geomagnetic poles at all local times (or longitudes), most clearly seen at night against a dark sky. A region that currently displays an aurora is called the auroral oval, a band displaced towards the nightside of the Earth. Day-to-day positions of the auroral ovals are posted on the internet. A geomagnetic storm causes the auroral ovals (north and south) to expand, and bring the aurora to lower latitudes.Early evidence for a geomagnetic connection comes from the statistics of auroral observations. Elias Loomis (1860), and later Hermann Fritz (1881) and S. Tromholt (1882) in more detail, established that the aurora appeared mainly in the "auroral zone", a ring-shaped region with a radius of approximately 2500 km around the Earth's magnetic pole. It was hardly ever seen near the geographic pole, which is about 2000 km away from the magnetic pole. The instantaneous distribution of auroras ("auroral oval") is slightly different, being centered about 3–5 degrees nightward of the magnetic pole, so that auroral arcs reach furthest toward the equator when the magnetic pole in question is in between the observer and the Sun. The aurora can be seen best at this time, which is called magnetic midnight.

text: Most auroras occur in a band known as the auroral zone, which is typically 3° to 6° wide in latitude and between 10° and 20° from the

text: geomagnetic pole

text: s at all local times (or longitudes), most clearly seen at night against a dark sky. A region that currently displays an aurora is called the auroral oval, a band displaced towards the nightside of the Earth. Day-to-day positions of the auroral ovals are posted on the internet. A

text: geomagnetic storm

text: causes the auroral ovals (north and south) to expand, and bring the aurora to lower latitudes.Early evidence for a geomagnetic connection comes from the statistics of auroral observations.

text: Elias Loomis

text: (1860), and later Hermann Fritz (1881) and S. Tromholt (1882) in more detail, established that the aurora appeared mainly in the "auroral zone", a ring-shaped region with a radius of approximately 2500 km around the Earth's magnetic pole. It was hardly ever seen near the geographic pole, which is about 2000 km away from the magnetic pole. The instantaneous distribution of auroras ("auroral oval") is slightly different, being centered about 3–5 degrees nightward of the magnetic pole, so that auroral arcs reach furthest toward the equator when the

text: magnetic pole

text: in question is in between the observer and the

text: Sun

text: . The aurora can be seen best at this time, which is called

text: magnetic midnight

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: The magnetic hysteresis loop of an exchange spring magnet theoretically takes on a shape resembling that of a summation of its hard and soft magnetic components (as seen in Figure 1), meaning its energy product is higher than those of its components. A magnet’s maximum energy product (BH), which is roughly proportional to its coercivity (H) and magnetization saturation (M), is used as a metric of its ability to do magnetic work as (BH) is twice the magnet’s available magnetostatic energy. The exchange spring magnet offers a geometry able to improve upon the previously reported maximum energy products of materials such as Rare Earth/Transition Metal complexes; while both materials have sufficiently large H values and operate at relatively high Curie Temperatures, the exchange spring magnet can achieve much higher M values than the Rare Earth/Transition Metal (RE-TM) complexes.

text: The

text: magnetic hysteresis loop

text: of an exchange spring magnet theoretically takes on a shape resembling that of a summation of its hard and soft magnetic components (as seen in Figure 1), meaning its energy product is higher than those of its components. A magnet’s maximum energy product (BH), which is roughly proportional to its coercivity (H) and magnetization saturation (M), is used as a metric of its ability to do magnetic work as (BH) is twice the magnet’s available magnetostatic energy. The exchange spring magnet offers a geometry able to improve upon the previously reported maximum energy products of materials such as Rare Earth/Transition Metal complexes; while both materials have sufficiently large H values and operate at relatively high

text: Curie Temperatures

text: , the exchange spring magnet can achieve much higher M values than the Rare Earth/Transition Metal (RE-TM) complexes.

text: The acceleration of the plasma into the co-rotation leads to the transfer of energy from the Jovian rotation to the kinetic energy of the plasma. In that sense, the Jovian magnetosphere is powered by the planet's rotation, whereas the Earth's magnetosphere is powered mainly by the solar wind.

text: The acceleration of the plasma into the co-rotation leads to the transfer of energy from the Jovian rotation to the

text: kinetic energy

text: of the plasma. In that sense, the Jovian magnetosphere is powered by the planet's rotation, whereas the Earth's magnetosphere is powered mainly by the solar wind.

text: It is notable that in season six, the opening dialog was replaced by a new rap theme. Also, the Planeteers' clothes were updated to look more modern and the animation improved considerably. Linka's eye colour changed from blue to green and Gi's hair is longer. This season also was not aired in the United States until many years after the show's cancellation. Most of the episodes finally made their U.S. debut on Boomerang in 2006 as part of an Earth Day marathon.

text: It is notable that in season six, the opening dialog was replaced by a new

text: rap

text: theme. Also, the Planeteers' clothes were updated to look more modern and the animation improved considerably. Linka's eye colour changed from blue to green and Gi's hair is longer. This season also was not aired in the

text: United States

text: until many years after the show's cancellation. Most of the episodes finally made their U.S. debut on

text: Boomerang

text: in 2006 as part of an

text: Earth Day

text: marathon.

text: Given the planet's age (7 ± 4 billion years), irradiance (0.41 ± 0.05 times Earth's) and radius (1.41 ± 0.07 times Earth's), a rocky (silicate-iron) composition with the addition of a possibly substantial amount of water is considered plausible. A modeling study indicates it is likely that a great majority of planets in its size range are completely covered by ocean. If its density is the same as Earth's, its mass would be 1.41 or 2.80 times Earth's.   The planet has the potential for hosting a moon according to a study of tidal effects on potentially habitable planets.  The planet may be the only habitable-zone candidate which would avoid desiccation by irradiation from the host star at its current location.

text: Given the planet's age (7 ± 4 billion years), irradiance (0.41 ± 0.05 times Earth's) and radius (1.41 ± 0.07 times Earth's), a rocky (silicate-iron) composition with the addition of a possibly substantial amount of water is considered plausible. A modeling study indicates it is likely that a great majority of planets in its size range are completely covered by ocean. If its density is the same as Earth's, its mass would be 1.41 or 2.80 times Earth's.   The planet has the potential for hosting a

text: moon

text: according to a study of tidal effects on potentially habitable planets.  The planet may be the only habitable-zone candidate which would avoid desiccation by irradiation from the host star at its current location.

text: Kepler-20b is an exoplanet orbiting Kepler-20. Its radius is about twice that of Earth, with a mass around 9.7 Earth masses. It has a higher density compared to earth and is likely made out of a higher percentage of iron. Along with the other four planets in the system, Kepler-20b was announced on 20 December 2011.

text: Kepler-20b is an

text: exoplanet

text: orbiting

text: . Its radius is about twice that of

text: Earth

text: , with a mass around 9.7

text: Earth mass

text: es. It has a higher density compared to earth and is likely made out of a higher percentage of iron. Along with the other four planets in the system, Kepler-20b was announced on 20 December 2011.

text: After relocating the planet, Doom returned to Earth-616 to join forces with the Fantastic Four and defeat the Dreaming Celestial, who retaliated by trapping Mister Fantastic inside Doom's armor and transporting Doom himself back to Counter-Earth. Doom quickly regained his power base and returned to Earth-616 to reclaim Latveria as well.  As opposition forces on Counter-Earth began to mount against him, Doom sought to tap into radiation sources deep inside the planet to use in a contingency plan; however, he instead discovered an artificial construct, which he erroneously concluded to be an electronic "reality engine" that monitored and controlled Counter-Earth.  Seeking to exploit this discovery, Doom was led to believe he could reprogram the planet to any reality he wished, but soon determined that a world he could shape to his desire offered no challenge.  Travelling through the Negative Zone, Doom returned to Latveria, creating a power vacuum that would plunge Counter-Earth into chaos.

text: After relocating the planet, Doom returned to Earth-616 to join forces with the Fantastic Four and defeat the Dreaming Celestial, who retaliated by trapping

text: Mister Fantastic

text: inside Doom's armor and transporting Doom himself back to Counter-Earth. Doom quickly regained his power base and returned to Earth-616 to reclaim

text: Latveria

text: as well.  As opposition forces on Counter-Earth began to mount against him, Doom sought to tap into radiation sources deep inside the planet to use in a contingency plan; however, he instead discovered an artificial construct, which he erroneously concluded to be an electronic "reality engine" that monitored and controlled Counter-Earth.  Seeking to exploit this discovery, Doom was led to believe he could reprogram the planet to any reality he wished, but soon determined that a world he could shape to his desire offered no challenge.  Travelling through the

text: Negative Zone

text: , Doom returned to Latveria, creating a power vacuum that would plunge Counter-Earth into chaos.

text: Gliese 163 c () or Gl 163 c is said to be a potentially habitable exoplanet, on the basis of its distance from its star being compatible with temperatures that would allow liquid water to exist on the surface, orbiting the red dwarf Gliese 163. The parent star is 15.0 parsecs (approximately 49 light-years, or 465 trillion kilometers) from the Sun, in the constellation Dorado.  Gliese 163 c is one of three planets discovered in the system.  With a mass at least 7.2 times that of the Earth, it is classified as a super-Earth (a planet of roughly 1 to 10 Earth masses).

text: Gliese 163 c () or Gl 163 c is said to be a potentially

text: habitable exoplanet

text: , on the basis of its distance from its star being compatible with temperatures that would allow liquid water to exist on the surface, orbiting the

text: red dwarf

text: Gliese 163

text: . The parent star is 15.0 parsecs (approximately 49 light-years, or 465 trillion kilometers) from the Sun, in the constellation

text: Dorado

text: .  Gliese 163 c is one of three planets discovered in the system.  With a mass at least 7.2 times that of the

text: Earth

text: , it is classified as a

text: super-Earth

text: (a planet of roughly 1 to 10 Earth masses).

text: Under this definition, the Earth–Moon system is not currently a double planet; although the Moon is massive enough to cause the Earth to make a noticeable revolution around this center of mass, this point nevertheless lies well within Earth. However, the Moon migrates outward from Earth at a rate of approximately  per year; in a few hundred million years, the Earth–Moon system's center of mass will lie outside Earth, which would make it a double-planet system.

text: "Directorates" are the ministries of the Scottish Government. They serve to execute government policy. Unlike in the British government, cabinet secretaries do not lead the directorates, and have no direct role in their operation. Instead, the directorates are grouped together into six "Directorates General", each run by a senior civil servant who is titled a "Director-General". As of May 2016, there are six Directorates General:

text: "Directorates" are the

text: ministries

text: of the Scottish Government. They serve to execute government policy. Unlike in the

text: British government

text: , cabinet secretaries do not lead the directorates, and have no direct role in their operation. Instead, the directorates are grouped together into six "Directorates General", each run by a senior civil servant who is titled a "Director-General". As of May 2016, there are six Directorates General:

text: As soon as they are back in Spain, however, Mortadelo and Filemon stumble across the two suspects, who talk about the demolition of the statue being imminent, and take up pursuit. Strangely, they end up in a backwater village, where the mystery is finally solved: The statue in question is not the famous New York monument, but a local statue erected in honor of a former village mayor, Libertad Boniquez, and it is meant to be blown up because it was inconveniently placed before the entrance of the village's main pigsty. And as the charge set by the villagers blows up the statue (and half the village with it), Mortadelo is forced to flee from an attempt by Filemon to murderize him for leading them on a wild goose chase.

text: As soon as they are back in Spain, however, Mortadelo and Filemon stumble across the two suspects, who talk about the demolition of the statue being imminent, and take up pursuit. Strangely, they end up in a backwater village, where the mystery is finally solved: The statue in question is not the famous New York monument, but a local statue erected in honor of a former village mayor, Libertad Boniquez, and it is meant to be blown up because it was inconveniently placed before the entrance of the village's main pigsty. And as the charge set by the villagers blows up the statue (and half the village with it), Mortadelo is forced to flee from an attempt by Filemon to murderize him for leading them on a

text: wild goose chase

text: The gameworld is displayed in a 3D view from the skimmer. As well as displaying these 3D graphics, Cooke's game engine renders them with simple shadows in order to simulate the day and night cycle of Tau Ceti III. These days are much shorter than Earth's consisting of one spin of the planet per hour with sixteen "spins" to a Centaurian day.

text: The gameworld is displayed in a

text: 3D view from the skimmer

text: . As well as displaying these 3D graphics, Cooke's game engine renders them with simple shadows in order to simulate the day and night cycle of Tau Ceti III. These days are much shorter than Earth's consisting of one spin of the planet per hour with sixteen "spins" to a Centaurian day.

text: The existence of a permanent day side and night side is not the only potential setback for life around red dwarfs. Tidal heating experienced by planets in the habitable zone of red dwarfs less than 30% of the mass of the Sun may cause them to be "baked out" and become "tidal Venuses." Combined with the other impediments to red dwarf habitability, this may make the probability of many red dwarfs hosting life as we know it very low compared to other star types. There may not even be enough water for habitable planets around many red dwarfs; what little water found on these planets, in particular Earth-sized ones, may be located on the cold night side of the planet. In contrast to the predictions of earlier studies on tidal Venuses, though, this "trapped water" may help to stave off runaway greenhouse effects and improve the habitability of red dwarf systems.

text: Francis Hoyt was born in Lyndon, Vermont, on November 5, 1822. He was the son of Lucinda Hoyt (née Freeman) and Benjamin Ray Hoyt (1789–1872). His father was a minister and a founder of Wesleyan University in Middletown, Connecticut. The younger Hoyt's early education came at Newbury Seminary in Vermont before he attended Wesleyan where he graduated in 1844. Hoyt then served as the principal at Newbury. On December 24, 1848, he married Phebe M. Dyar, and they had six children.

text: Francis Hoyt was born in

text: Lyndon, Vermont

text: , on November 5, 1822. He was the son of Lucinda Hoyt (née Freeman) and Benjamin Ray Hoyt (1789–1872). His father was a minister and a founder of

text: Wesleyan University

text: in

text: Middletown, Connecticut

text: . The younger Hoyt's early education came at

text: Newbury Seminary

text: in

text: Vermont

text: before he attended Wesleyan where he graduated in 1844. Hoyt then served as the principal at Newbury. On December 24, 1848, he married Phebe M. Dyar, and they had six children.

text: Interplanetary space contains the magnetic field generated by the Sun. There are also magnetospheres generated by planets such as Jupiter, Saturn, Mercury and the Earth that have their own magnetic fields. These are shaped by the influence of the solar wind into the approximation of a teardrop shape, with the long tail extending outward behind the planet. These magnetic fields can trap particles from the solar wind and other sources, creating belts of magnetic particles such as the Van Allen radiation belt. Planets without magnetic fields, such as Mars, have their atmospheres gradually eroded by the solar wind.

text: Shannon began to publish a newsletter in 1994, Shannon Knows DEC, which eventually became Shannon Knows Compaq, after the firm's acquisition, and then Shannon Knows HPC.  His insider knowledge constantly frustrated those he wrote about, and HP pursued a love/hate relationship, occasionally citing him in press releases. The newsletter ran until his death in 2005.

text: The Earth’s magnetic field is a potential map cue as the field varies in both strength and direction over the Earth’s surface Manipulations of the ambient magnetic field are rather difficult, although Keeton (1971) and Ioalé (1984) did report that magnets caused disorientation in pigeons when they were released under total overcast.  This first indication for magnetic compass orientation in homing was later supported by other studies, which reversed the field around the head of the pigeon using battery operated coils.  Though the coils had little effect in clear conditions, their effect under overcast conditions was dependent on the direction of the current.  Another observation consistent with the idea of a geomagnetic map is the shift in the initial bearings of pigeons that occurs when the field increases during magnetic storms.  In magnetic anomalies too, pigeons are disoriented, even under sunny conditions.

text: The Earth’s magnetic field is a potential map cue as the field varies in both strength and direction over the Earth’s surface Manipulations of the ambient magnetic field are rather difficult, although

text: Keeton

text: (1971) and Ioalé (1984) did report that magnets caused disorientation in pigeons when they were released under total overcast.  This first indication for magnetic compass orientation in homing was later supported by other studies, which reversed the field around the head of the pigeon using battery operated

text: coils

text: .  Though the coils had little effect in clear conditions, their effect under overcast conditions was dependent on the direction of the current.  Another observation consistent with the idea of a geomagnetic map is the shift in the initial bearings of pigeons that occurs when the field increases during magnetic storms.  In

text: magnetic anomalies

text: too, pigeons are disoriented, even under sunny conditions.

text: Venus, the nearest and most similar planet to Earth, has 100 times denser atmosphere, with little or no geo-magnetic field. Space probes discovered a comet-like tail that extends to Earth's orbit.

text: Venus

text: , the nearest and most similar planet to Earth, has 100 times denser atmosphere, with little or no geo-magnetic field. Space probes discovered a comet-like tail that extends to Earth's orbit.

text: The three small planets orbit the dwarf closely (at 1%, 1.5% and 3% of the distance that the Earth orbits from the Sun). A year on the closest planet passes in only 1.5 Earth days, the second is in 2.4 Earth days and the orbit of the third planet is less certain, with a year passing in 4.5 to 73 Earth days. It is important to note that tidally locked planets likely have very large differences in temperature between their permanently lit daysides and their permanently dark nightsides, which could produce very strong winds circling the planets, while making the best places for life close to the mild twilight regions between the two sides.

text: The three small planets orbit the dwarf closely (at 1%, 1.5% and 3% of the distance that the

text: Earth

text: orbits from the Sun). A year on the closest planet passes in only 1.5 Earth days, the second is in 2.4 Earth days and the orbit of the third planet is less certain, with a year passing in 4.5 to 73 Earth days. It is important to note that tidally locked planets likely have very large differences in temperature between their permanently lit daysides and their permanently dark nightsides, which could produce very strong winds circling the planets, while making the best places for life close to the mild twilight regions between the two sides.

text: The wet, or rainy, season is the time of year, covering one or more months, when most of the average annual rainfall in a region falls.  The term green season is also sometimes used as a euphemism by tourist authorities.  Areas with wet seasons are dispersed across portions of the tropics and subtropics.  Savanna climates and areas with monsoon regimes have wet summers and dry winters.  Tropical rainforests technically do not have dry or wet seasons, since their rainfall is equally distributed through the year.  Some areas with pronounced rainy seasons will see a break in rainfall mid-season when the intertropical convergence zone or monsoon trough move poleward of their location during the middle of the warm season.  When the wet season occurs during the warm season, or summer, rain falls mainly during the late afternoon and early evening hours.  The wet season is a time when air quality improves, freshwater quality improves, and vegetation grows significantly.  Soil nutrients diminish and erosion increases.  Animals have adaptation and survival strategies for the wetter regime.  The previous dry season leads to food shortages into the wet season, as the crops have yet to mature.  Developing countries have noted that their populations show seasonal weight fluctuations due to food shortages seen before the first harvest, which occurs late in the wet season.

text: The wet, or rainy, season is the time of year, covering one or more months, when most of the average annual

text: rainfall

text: in a region falls.  The term green season is also sometimes used as a

text: euphemism

text: by tourist authorities.  Areas with wet seasons are dispersed across portions of the

text: tropics

text: and

text: subtropics

text: Savanna

text: climates and areas with

text: monsoon

text: regimes have wet summers and dry winters.  Tropical rainforests technically do not have dry or wet seasons, since their rainfall is equally distributed through the year.  Some areas with pronounced rainy seasons will see a break in rainfall mid-season when the

text: intertropical convergence zone

text: or

text: monsoon trough

text: move poleward of their location during the middle of the warm season.  When the wet season occurs during the warm season, or

text: summer

text: , rain falls mainly during the late afternoon and early evening hours.  The wet season is a time when

text: air quality

text: improves, freshwater quality improves, and vegetation grows significantly.

text: Soil

text: nutrients diminish and erosion increases.  Animals have adaptation and survival strategies for the wetter regime.  The previous dry season leads to food shortages into the wet season, as the crops have yet to mature.  Developing countries have noted that their populations show seasonal weight fluctuations due to food shortages seen before the first harvest, which occurs late in the wet season.

text: This planet is located approximately  away in the constellation of Cygnus, orbiting the 10th apparent magnitude K-type star HAT-P-11. This planet was the smallest transiting planet known when first discovered, with a radius about 5 times that of Earth; but is more massive than Gliese 436 b at a true mass of 26 times that of Earth. This planet orbits about the same distance from the star as 51 Pegasi b is from 51 Pegasi, typical of transiting planets. However, the orbit of this planet is eccentric, at around 0.198, unusually high for hot Neptunes. HAT-P-11b's orbit is also highly inclined, with a tilt of approximately 103 degrees relative to its star's rotation.

text: This planet is located approximately  away in the

text: constellation

text: of

text: Cygnus

text: , orbiting the 10th

text: apparent magnitude

text: K-type

text: star

text: . This planet was the smallest transiting planet known when first discovered, with a radius about 5 times that of Earth; but is more massive than

text: Gliese 436 b

text: at a

text: true mass

text: of 26 times that of

text: Earth

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

text: 51 Pegasi b

text: is from

text: 51 Pegasi

text: , typical of transiting planets. However, the orbit of this planet is eccentric, at around 0.198, unusually high for

text: hot Neptune

text: s. HAT-P-11b's orbit is also highly inclined, with a tilt of approximately 103 degrees relative to its star's rotation.

text: Early models of rocky exoplanets scaled different factors (namely mantle viscosity, lithospheric yield strength, and planetary size) up and down to predict the geodynamic regime of an exoplanet with given parameters. Two scaling studies of exoplanet size published in 2007 came to fundamentally different conclusions: O’Neill and Lenardic (2007) showed that a planet of 1.1 Earth mass would have Earth-like lithospheric yield stress but reduced mantle driving stresses, resulting in a stagnant lid regime. Conversely, Valencia et al. (2007) concluded the increase in mantle velocity (driving force) is large compared to the gravitationally-forced increase of plate viscosity as planets increase beyond one Earth mass, increasing the likelihood of plate tectonics with planet size.

text: Early models of rocky exoplanets scaled different factors (namely mantle viscosity, lithospheric yield strength, and planetary size) up and down to predict the geodynamic regime of an exoplanet with given parameters. Two scaling studies of exoplanet size published in 2007 came to fundamentally different conclusions: O’Neill and Lenardic (2007) showed that a planet of 1.1

text: Earth mass

text: would have Earth-like lithospheric yield stress but reduced mantle driving stresses, resulting in a stagnant lid regime. Conversely, Valencia et al. (2007) concluded the increase in mantle velocity (driving force) is large compared to the gravitationally-forced increase of plate viscosity as planets increase beyond one Earth mass, increasing the likelihood of plate tectonics with planet size.

text: In the Ptolemaic system the models for each of the planets were different and so it was with Copernicus' initial models. As he worked through the mathematics, however, Copernicus discovered that his models could be combined in a unified system. Furthermore, if they were scaled so that Earth's orbit was the same in all of them, the ordering of the planets we recognize today easily followed from the math. Mercury orbited closest to the Sun and the rest of the planets fell into place in order outward, arranged in distance by their periods of revolution.

text: After releasing several successful tracks and remixes, he collaborated with world-renowned Dutch rock band Eller Van Buuren with Bagga Bownz. The result of this collaboration was the track "Day and Night", included on the 2014 Richard Durand compilation In Search of Sunrise 12: Dubai. "Day and Night". The "Day and Night" became an opening and won the great honor of being chosen as the track to represent the entire compilation in its promotional video.

text: After releasing several successful tracks and remixes, he collaborated with world-renowned Dutch rock band Eller Van Buuren with Bagga Bownz. The result of this collaboration was the track "Day and Night", included on the 2014

text: Richard Durand

text: compilation

text: In Search of Sunrise 12: Dubai

text: . "Day and Night". The "Day and Night" became an opening and won the great honor of being chosen as the track to represent the entire compilation in its promotional video.

text: Immediately after arriving in Budapest, Milanković met the Director of the Library of the Hungarian Academy of Science, Koloman von Szilly who, as a mathematician, eagerly accepted Milanković and enabled him to work undisturbed in the Academy's library and the Central Meteorological Institute. Milanković spent four years in Budapest, almost the entire war. He used mathematical methods to study the current climate of inner planets of the solar system. In 1916 he published a paper entitled "Investigation of the climate of the planet Mars". Milanković calculated that the average temperature in the lower layers the atmosphere on Mars is  and the average surface temperature is . Also, he concluded that: "This large temperature difference between the ground and lower layers of the atmosphere is not unexpected. Great transparency for solar radiation makes that is the climate of Mars very similar to altitudes climate of our Earth." Today it is known that the average temperature is , but that the ground temperatures and air temperatures generally differ. In any case, Milanković theoretically proved that Mars has an extremely harsh climate. In addition to considering Mars, he dealt with the climatic conditions prevailing on Venus and Mercury. His calculations of the temperature conditions on the neighboring Moon are particularly significant. Milanković knew that one day on the Moon lasts 15 Earth days, and this is the amount and length of night. Milanković calculated that the surface temperature on the day side of the moon reaches +100.5 °C. Also, he calculated that the temperature during the early morning on the Moon, or before the rise of the Sun over horizon, was -58 °C. Today it is known that the surface temperature on the day side of the Moon reaches +108 °C and that it falls at night to -153 °C.

text: Immediately after arriving in Budapest, Milanković met the Director of the Library of the

text: Hungarian Academy of Science

text: Koloman von Szilly

text: who, as a mathematician, eagerly accepted Milanković and enabled him to work undisturbed in the Academy's library and the Central Meteorological Institute. Milanković spent four years in Budapest, almost the entire war. He used mathematical methods to study the current climate of inner planets of the solar system. In 1916 he published a paper entitled "Investigation of the climate of the planet Mars". Milanković calculated that the average temperature in the lower layers the atmosphere on

text: Mars

text: is  and the average surface temperature is . Also, he concluded that: "This large temperature difference between the ground and lower layers of the atmosphere is not unexpected. Great transparency for solar radiation makes that is the climate of Mars very similar to altitudes climate of our Earth." Today it is known that the average temperature is , but that the ground temperatures and air temperatures generally differ. In any case, Milanković theoretically proved that Mars has an extremely harsh climate. In addition to considering Mars, he dealt with the climatic conditions prevailing on

text: Venus

text: and

text: Mercury

text: . His calculations of the temperature conditions on the neighboring

text: Moon

text: are particularly significant. Milanković knew that

text: one day on the Moon

text: lasts 15 Earth days, and this is the amount and length of night. Milanković calculated that the surface temperature on the day side of the moon reaches +100.5 °C. Also, he calculated that the temperature during the early morning on the Moon, or before the rise of the Sun over horizon, was -58 °C. Today it is known that the surface temperature on the day side of the Moon reaches +108 °C and that it falls at night to -153 °C.

text: The sixth book of de Magnete was devoted to cosmology. He dismissed the prevailing Ptolemaic model of the universe, in which the planets and stars are organized in a series of concentric shells rotating about the Earth, on the grounds that the speeds involved would be absurdly large ("there cannot be diurnal motion of infinity"). Instead, the Earth was rotating about its own axis. In place of the concentric shells, he proposed that the heavenly bodies interacted with each other and Earth through magnetic forces. Magnetism maintained the Earths position and made it rotate, while the magnetic attraction of the Moon drove the tides. Some obscure reasoning led to the peculiar conclusion that a terella, if freely suspended, would orient itself in the same direction as the Earth and rotate daily.  Both Kepler and Galileo would adopt Gilbert's idea of magnetic attraction between heavenly bodies, but Newton's law of universal gravitation would render it obsolete.

text: The sixth book of de Magnete was devoted to

text: cosmology

text: . He dismissed the prevailing

text: Ptolemaic model

text: of the universe, in which the planets and stars are organized in a series of concentric shells rotating about the Earth, on the grounds that the speeds involved would be absurdly large ("there cannot be

text: diurnal

text: motion of infinity"). Instead, the Earth was rotating about its own axis. In place of the concentric shells, he proposed that the heavenly bodies interacted with each other and Earth through magnetic forces. Magnetism maintained the Earths position and made it rotate, while the magnetic attraction of the

text: Moon

text: drove the

text: tides

text: . Some obscure reasoning led to the peculiar conclusion that a terella, if freely suspended, would orient itself in the same direction as the Earth and rotate daily.  Both

text: Kepler

text: and

text: Galileo

text: would adopt Gilbert's idea of magnetic attraction between heavenly bodies, but

text: Newton's law of universal gravitation

text: would render it obsolete.

text: Mars shows remnants of an earlier, planetary-scale magnetic field, with stripes as on Earth. This is taken as evidence that the planet had a molten metal core in its prior history, allowing both a magnetosphere and tectonic activity (as on Earth). Both of these have since dissipated. Earth's Moon shows localized magnetic fields, indicating some process other than a large, molten metal core. This may be the source of lunar swirls, not seen on Earth.

text: Mars shows remnants of an earlier, planetary-scale magnetic field, with

text: stripes as on Earth

text: . This is taken as evidence that the planet had a molten metal core in its prior history, allowing both a magnetosphere and tectonic activity (as on Earth). Both of these have since dissipated. Earth's Moon shows localized magnetic fields, indicating some process other than a large, molten metal core. This may be the source of

text: lunar swirl

text: s, not seen on Earth.

text: Wolf 1061c is thought to be a rocky planet estimated to be a super-Earth exoplanet as its mass is about 4.3 times that of Earth and radius is over 1.5 which would give it a density either near or possibly higher than Earth. It has an estimated surface gravity of 1.6 times that on Earth.

text: Wolf 1061c is thought to be a

text: rocky planet

text: estimated to be a

text: super-Earth

text: exoplanet

text: as its mass is about 4.3 times that of Earth and radius is over 1.5 which would give it a density either near or possibly higher than Earth. It has an estimated surface gravity of 1.6 times that on Earth.

text: The first episode of the series, "New Earth", was also the first episode since Doctor Who was revived not to be set in the vicinity of Earth, and the first story since The Greatest Show in the Galaxy from Season 25 to be wholly set on an alien world; every episode of Series 1 had taken place either on Earth itself or on a space station in the vicinity of the planet.

text: The first episode of the series, "New Earth", was also the first episode since Doctor Who was revived not to be set in the vicinity of

text: Earth

text: , and the first story since

text: The Greatest Show in the Galaxy

text: from

text: Season 25

text: to be wholly set on an alien world; every episode of

text: Series 1

text: had taken place either on Earth itself or on a

text: space station

text: in the vicinity of the planet.

text: Earth's gravity allows it to hold an atmosphere. Water vapor and carbon dioxide in the atmosphere provide a temperature buffer (greenhouse effect) which helps maintain a relatively steady surface temperature. If Earth were smaller, a thinner atmosphere would allow temperature extremes, thus preventing the accumulation of water except in polar ice caps (as on Mars).

text: Earth's

text: gravity

text: allows it to hold an

text: atmosphere

text: . Water vapor and carbon dioxide in the atmosphere provide a temperature buffer (

text: greenhouse effect

text: ) which helps maintain a relatively steady surface temperature. If Earth were smaller, a thinner atmosphere would allow temperature extremes, thus preventing the accumulation of water except in

text: polar ice cap

text: s (as on

text: Mars

text: Substituting earth's gravity, g for the acceleration term, and combining the two equations gives