text: Eclipses only occur in the eclipse season, when the Sun is close to either the ascending or descending node of the Moon. Each eclipse is separated by one, five or six lunations (synodic months), and the midpoint of each season is separated by 173.3 days, which is the mean time for the Sun to travel from one node to the next. The period is a little less than half a calendar year because the lunar nodes slowly regress. Because 223 synodic months is roughly equal to 239 anomalistic months and 242 draconic months, eclipses with similar geometry recur 223 synodic months (about 6,585.3 days) apart. This period (18 years 11.3 days) is a saros. Because 223 synodic months is not identical to 239 anomalistic months or 242 draconic months, saros cycles do not endlessly repeat. Each cycle begins with the Moon's shadow crossing the earth near the north or south pole, and subsequent events progress toward the other pole until the Moon's shadow misses the earth and the series ends. Saros cycles are numbered; currently, cycles 117 to 156 are active.

text: Eclipses only occur in the

entity_name: Eclipse season

text: eclipse season

text: , when the Sun is close to either the ascending or descending

entity_name: Lunar node

text: node of the Moon

text: . Each eclipse is separated by one, five or six

entity_name: New moon

text: lunation

text: s (

entity_name: Lunar month

text: synodic month

text: s), and the midpoint of each season is separated by 173.3 days, which is the mean time for the Sun to travel from one node to the next. The period is a little less than half a calendar year because the lunar nodes slowly regress. Because 223 synodic months is roughly equal to 239

text: anomalistic month

text: s and 242

text: draconic month

text: s, eclipses with similar geometry recur 223 synodic months (about 6,585.3 days) apart. This period (18 years 11.3 days) is a

entity_name: Saros (astronomy)

text: saros

text: . Because 223 synodic months is not identical to 239 anomalistic months or 242 draconic months, saros cycles do not endlessly repeat. Each cycle begins with the Moon's shadow crossing the earth near the north or south pole, and subsequent events progress toward the other pole until the Moon's shadow misses the earth and the series ends. Saros cycles are numbered; currently, cycles 117 to 156 are active.

text: People in eastern and southern Serbia believed that ale, in their voracity, attacked the Sun and the Moon. They gradually ate more and more of those celestial bodies, thereby causing an eclipse. During an eclipse, the Sun turned red because it was covered with its own blood as a result of the ale’s bites; when it shone brightly again, that meant it had defeated the ale. The spots on the Moon were seen as scars from the ale’s bites. While ale devoured the Sun or the Moon, many elderly people became depressed and even wept in fear. If ale succeeded in devouring the Sun, the world would end. To prevent that, men shot their guns toward the eclipse or rang bells, and women cast spells incessantly. There was a notion in the Homolje region that, if ale succeeded in devouring the Moon, the Sun would die from sorrow, and darkness would overwhelm the world.

text: People in eastern and southern Serbia believed that ale, in their voracity, attacked the

entity_name: Sun

text: Sun

text: and the

entity_name: Moon

text: Moon

text: . They gradually ate more and more of those celestial bodies, thereby causing an

entity_name: Eclipse

text: eclipse

text: . During an eclipse, the Sun turned red because it was covered with its own blood as a result of the ale’s bites; when it shone brightly again, that meant it had defeated the ale. The spots on the Moon were seen as scars from the ale’s bites. While ale devoured the Sun or the Moon, many elderly people became

entity_name: Depression (mood)

text: depressed

text: and even wept in fear. If ale succeeded in devouring the Sun, the world would end. To prevent that, men shot their guns toward the eclipse or rang bells, and women cast spells incessantly. There was a notion in the Homolje region that, if ale succeeded in devouring the Moon, the Sun would die from sorrow, and darkness would overwhelm the world.

text: There were 12 solar eclipses observed from 2137 BC to 424 BC. all have a historical basis, because some old historical scriptures provide us details of these solar eclipses. Firstly, in writing sources of ancient China, we found a solar eclipse of 22 October, 2137 BC, but mostly Chinese ancient records shows details about comets, constellations, and fixed stars.

text: There were 12 solar eclipses observed from 2137 BC to 424 BC. all have a historical basis, because some old historical scriptures provide us details of these

entity_name: Solar eclipse

text: solar eclipses

text: . Firstly, in writing sources of

entity_name: History of China

entity_section: Ancient China

text: ancient China

text: , we found a solar eclipse of 22 October, 2137 BC, but mostly Chinese ancient records shows details about

entity_name: Comet

text: comets

entity_name: Constellation

text: constellations

text: , and

entity_name: Fixed stars

text: fixed stars

method: dangnt-nlp

text: A partial solar eclipse occurred on June 10, 1964. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: occurred on June 10, 1964. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

entity_name: Earth

text: Earth

text: and the

text: Sun

text: , thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

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

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

entity_name: Roche limit

text: Roche limit

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

entity_name: Ablation

text: ablation

text: and

entity_name: Vaporization

text: vaporization

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

entity_name: Crust (geology)

text: crust

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

entity_name: Metallicity

text: metallicity

text: 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.

text: A partial lunar eclipse took place on June 4, 2012. It was the first of two lunar eclipses occurring in 2012, the second eclipse set to happen on November 28. The moon was about one third covered by the Earth's northern umbral shadow at maximum eclipse. The portion of the moon inside the umbral shadow was illuminated by sunlight refracted through the Earth's atmosphere, thus much dimmer, and having a reddish hue.

text: A partial

entity_name: Lunar eclipse

text: lunar eclipse

text: took place on June 4, 2012. It was the first of two lunar eclipses occurring in 2012, the second eclipse set to happen on November 28. The moon was about one third covered by the Earth's northern umbral shadow at maximum eclipse. The portion of the moon inside the umbral shadow was illuminated by sunlight refracted through the Earth's atmosphere, thus much dimmer, and having a reddish hue.

text: The appearance, or phase, of the Moon is due to its motion with respect to the Sun.  It varies in a period of  time called a lunation, also called synodic month; its duration is about 2 days longer than an anomalistic month.  The age is the number of days since new moon.

text: The appearance, or

entity_name: Lunar phase

text: phase

text: , of the Moon is due to its motion with respect to the Sun.  It varies in a period of  time called a lunation, also called

text: synodic month

text: ; its duration is about 2 days longer than an anomalistic month.  The age is the number of days since

text: new moon

text: For terrestrial observations, "Sun–object–Earth" is often nearly the same thing as "Sun–object–observer", since the difference depends on the parallax, which in the case of observations of the Moon can be as much as 1°, or two full Moon diameters. With the development of space travel, as well as in hypothetical observations from other points in space, the notion of phase angle became independent of Sun and Earth.

text: For terrestrial observations, "Sun–object–Earth" is often nearly the same thing as "Sun–object–observer", since the difference depends on the

entity_name: Parallax

text: parallax

text: , which in the case of observations of the

text: Moon

text: can be as much as 1°, or two full Moon diameters. With the development of

entity_name: Spaceflight

text: space travel

text: , as well as in hypothetical observations from other points in space, the notion of phase angle became independent of Sun and Earth.

text: There were two other eclipses that year. The first was a partial lunar eclipse, during which the shadow of the earth can be seen on the moon, and another solar eclipse that took place on December 3 over South America. The other solar eclipse however was an annular eclipse which occurs when the moon has a smaller apparent diameter and therefore never fully obscures the sun.

text: There were two other eclipses that year. The first was a partial lunar eclipse, during which the shadow of the earth can be seen on the moon, and another solar eclipse that took place on

entity_name: Solar eclipse of December 3, 1918

text: December 3 over South America

text: . The other solar eclipse however was an annular eclipse which occurs when the moon has a smaller apparent diameter and therefore never fully obscures the sun.

text: A partial solar eclipse occurred on November 10, 1920. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: occurred on November 10, 1920. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: An annular solar eclipse will occur on June 21, 2039. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.This eclipse will start only a few hours after the northern solstice and most of the path will go across areas with midnight sun.  For mainland Norway and Sweden it will be the first central solar eclipse since June 1954.

text: An annular

text: solar eclipse

text: will occur on June 21, 2039. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: , thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's

entity_name: Angular diameter

text: apparent diameter

text: is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an

entity_name: Annulus (mathematics)

text: annulus

text: (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.This eclipse will start only a few hours after the

entity_name: June solstice

text: northern solstice

text: and most of the path will go across areas with

entity_name: Midnight sun

text: midnight sun

text: .  For mainland

entity_name: Norway

text: Norway

text: and

entity_name: Sweden

text: Sweden

text: it will be the first central solar eclipse since

entity_name: Solar eclipse of June 30, 1954

text: June 1954

text: Photographing the Moon's phase every day for a month, starting in the evening after sunset, and repeating approximately fifty minutes later each successive day, ending in the morning before sunrise, would create a composite image like the example calendar from May 8, 2005, to June 6, 2005 here in the left. There is no picture on May 20 since a picture would be taken before midnight on May 19, and after midnight on May 21. Similarly, on a calendar listing moon rise or set times, some days will appear to be skipped. When the Moon rises just before midnight one night it will rise just after midnight the next (so too with setting). The 'skipped day' is just a feature of the moon's eastward movement in relation to the sun, which at most latitudes causes the moon to rise later each day. The moon has a predictable orbit every month.

text: Section D: MOON contains detailed positional information on the Moon including phases, mean elements of the orbit and rotation, lengths of mean months, ecliptic and equatorial coordinates, librations, and physical ephemerides.

text: A synodic month is longer than a sidereal month because the Earth-Moon system is orbiting the Sun in the same direction as the Moon is orbiting the Earth.   The Sun moves eastward with respect to the stars (as does the Moon) and it takes about 2.2 days longer for the Moon to return to the same apparent position with respect to the Sun.

method: UvABottomUpChangeOrder

text: The main characters of the series are Jab get the back to the moon and Skills Vertigo, Montana, Emo, Jummpa, Panzer, Bommba, Juanito, Mole, Bubble, Missile, Tornado, Sharky and Quaka. They can’t live without each other but they also can’t help being selfish and playing pranks on each other constantly. The different phases of the moon change their personality for better or worse. These three friends don’t speak but they can communicate through noises, gestures and actions.

text: Also many moons, even those that do not orbit the Sun directly, often exhibit features in common with true planets. There are 19 moons in the Solar System that have achieved hydrostatic equilibrium and would be considered planets if only the physical parameters are considered.  Both Jupiter's moon Ganymede and Saturn's moon Titan are larger than Mercury, and Titan even has a substantial atmosphere, thicker than the Earth's. Moons such as Io and Triton demonstrate obvious and ongoing geological activity, and Ganymede has a magnetic field. Just as stars in orbit around other stars are still referred to as stars, some astronomers argue that objects in orbit around planets that share all their characteristics could also be called planets. Indeed, Mike Brown makes just such a claim in his dissection of the issue, saying:

text: Also many moons, even those that do not orbit the Sun directly, often exhibit features in common with true planets. There are 19 moons in the Solar System that have achieved hydrostatic equilibrium and would be considered planets if only the physical parameters are considered.  Both Jupiter's moon

entity_name: Ganymede (moon)

text: Ganymede

text: and Saturn's moon

entity_name: Titan (moon)

text: Titan

text: are larger than Mercury, and Titan even has a substantial atmosphere, thicker than the Earth's. Moons such as

entity_name: Io (moon)

text: Io

text: and

entity_name: Triton (moon)

text: Triton

text: demonstrate obvious and ongoing geological activity, and Ganymede has a

entity_name: Magnetic field

text: magnetic field

text: . Just as

entity_name: Star

text: star

text: s in orbit around other stars are still referred to as stars, some astronomers argue that objects in orbit around planets that share all their characteristics could also be called planets. Indeed, Mike Brown makes just such a claim in his dissection of the issue, saying:

text: An eclipse can only occur when the Moon is close to the plane of the orbit of the Earth, i.e. when its ecliptic latitude is small.  This happens when the Moon is near one of the two nodes of its orbit on the ecliptic at the time of the syzygy.  Of course, to produce an eclipse, the Sun must also be near a node at that time: the same node for a solar eclipse, or the opposite node for a lunar eclipse.

text: An eclipse can only occur when the Moon is close to the plane of the orbit of the Earth, i.e. when its

entity_name: Ecliptic coordinate system

text: ecliptic latitude

text: is small.  This happens when the Moon is near one of the two

text: node

text: s of its orbit on the ecliptic at the time of the

entity_name: Syzygy (astronomy)

text: syzygy

text: .  Of course, to produce an eclipse, the Sun must also be near a node at that time: the same node for a solar eclipse, or the opposite node for a lunar eclipse.

text: One of her experiments to study a lunar eclipse included placing a round table in a garden pavilion, acting as a globe; she hung a crystal lamp on a cord from the ceiling beams, representing the sun. Then on one side of the table she had a round mirror as the moon. She moved these three objects as if they were the sun, earth, and moon according to astronomical principles. Her findings and observations were very accurate and recorded in her article, "The Explanation of a Solar Eclipse."

text: A total solar eclipse took place on 13–15 November 2012 (UTC). Because it crossed the International Date Line it began in local time on November 14 west of the  date line over northern Australia, and ended in local time on November 13 east of the date line near the west coast of South America. Its greatest magnitude was 1.0500, occurring only 12 hours before perigee, with greatest eclipse totality lasting just over four minutes. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A total solar eclipse occurs when the Moon's apparent diameter is larger than the Sun's, blocking all direct sunlight, turning day into darkness. Totality occurs in a narrow path across Earth's surface, with the partial solar eclipse visible over a surrounding region thousands of kilometres wide.

text: A total

text: solar eclipse

text: took place on 13–15 November 2012 (

entity_name: Coordinated Universal Time

text: UTC

text: ). Because it crossed the

entity_name: International Date Line

text: International Date Line

text: it began in

entity_name: Time zone

text: local time

text: on November 14 west of the  date line over northern

entity_name: Australia

text: Australia

text: , and ended in local time on November 13 east of the date line near the west coast of

entity_name: South America

text: South America

text: . Its greatest

entity_name: Magnitude of eclipse

text: magnitude

text: was 1.0500, occurring only 12 hours before

entity_name: Apsis

text: perigee

text: , with greatest eclipse totality lasting just over four minutes. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: , thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A total solar eclipse occurs when the Moon's

text: apparent diameter

text: is larger than the Sun's, blocking all direct sunlight, turning day into darkness. Totality occurs in a narrow path across Earth's surface, with the partial solar eclipse visible over a surrounding region thousands of kilometres wide.

text: The moon's orbit isn't in the same plane as the Earth's orbit around the sun, but crosses it in two places. The moon crosses the ecliptic plane twice a month, once when it goes up above the plane, and again 15 or so days later when it goes back down below the ecliptic. These two locations are the ascending and descending lunar nodes. Solar and lunar eclipses will occur only when the moon is positioned near one of these nodes, because at other times the moon is either too high or too low for an eclipse to be noticed from earth. Some astronomical clocks keep track of the position of the lunar nodes with a long pointer that crosses the dial. This so-called dragon hand makes one complete rotation around the ecliptic dial every 19 years. When the dragon hand and the new moon coincide, the moon is on the same plane as the earth and sun, and so there is every chance that an eclipse will be visible from somewhere on earth.

text: The moon's orbit isn't in the same plane as the Earth's orbit around the sun, but crosses it in two places. The moon crosses the ecliptic plane twice a month, once when it goes up above the plane, and again 15 or so days later when it goes back down below the ecliptic. These two locations are the ascending and descending

text: lunar nodes

text: . Solar and lunar eclipses will occur only when the moon is positioned near one of these nodes, because at other times the moon is either too high or too low for an eclipse to be noticed from earth. Some astronomical clocks keep track of the position of the lunar nodes with a long pointer that crosses the dial. This so-called dragon hand makes one complete rotation around the ecliptic dial every 19 years. When the dragon hand and the new moon coincide, the moon is on the same plane as the earth and sun, and so there is every chance that an eclipse will be visible from somewhere on earth.

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

entity_name: Tide

text: tide

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

entity_name: Tidal locking

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

entity_name: Terminator (solar)

text: solar terminator

text: At the beginning of day three, the spacecraft was about  away from the Earth. The velocity of the craft steadily decreased, as it had not yet reached the lunar sphere of gravitational influence. The early part of day three was largely housekeeping, spacecraft maintenance and exchanging status reports with Mission Control in Houston. The crew performed the Apollo light flash experiment, or ALFMED, to investigate "light flashes" that were seen by the astronauts when the spacecraft was dark, regardless of whether or not their eyes were open, on Apollo lunar flights. This was thought to be caused by the penetration of the eye by cosmic ray particles. During the second half of the day, Young and Duke again entered the Lunar Module to power it up and check its systems, and perform housekeeping tasks in preparation for lunar landing. The systems were found to be functioning as expected. Following this, the crew donned their space suits and rehearsed procedures that would be used on landing day. Just before the end of flight day three at 59 hours, 19 minutes, 45 seconds after liftoff, while  from the Earth and  from the Moon, the spacecraft's velocity began increasing as it accelerated towards the Moon after entering the lunar sphere of influence.

text: At the beginning of day three, the spacecraft was about  away from the Earth. The velocity of the craft steadily decreased, as it had not yet reached the lunar sphere of gravitational influence. The early part of day three was largely housekeeping, spacecraft maintenance and exchanging status reports with Mission Control in Houston. The crew performed the Apollo light flash experiment, or ALFMED, to investigate "light flashes" that were seen by the astronauts when the spacecraft was dark, regardless of whether or not their eyes were open, on Apollo lunar flights. This was thought to be caused by the penetration of the

entity_name: Human eye

text: eye

text: by

entity_name: Cosmic ray

text: cosmic ray

text: particles. During the second half of the day, Young and Duke again entered the Lunar Module to power it up and check its systems, and perform housekeeping tasks in preparation for lunar landing. The systems were found to be functioning as expected. Following this, the crew donned their space suits and rehearsed procedures that would be used on landing day. Just before the end of flight day three at 59 hours, 19 minutes, 45 seconds after liftoff, while  from the Earth and  from the Moon, the spacecraft's velocity began increasing as it accelerated towards the Moon after entering the lunar sphere of influence.

text: Zhang applied his extensive knowledge of mechanics and gears in several of his inventions. He invented the world's first water-powered armillary sphere to assist astronomical observation; improved the inflow water clock by adding another tank; and invented the world's first seismoscope, which discerned the cardinal direction of an earthquake  away. He improved previous Chinese calculations for pi. In addition to documenting about 2,500 stars in his extensive star catalog, Zhang also posited theories about the Moon and its relationship to the Sun: specifically, he discussed the Moon's sphericity, its illumination by reflected sunlight on one side and the hidden nature of the other, and the nature of solar and lunar eclipses. His fu (rhapsody) and shi poetry were renowned in his time and studied and analyzed by later Chinese writers. Zhang received many posthumous honors for his scholarship and ingenuity; some modern scholars have compared his work in astronomy to that of the Greco-Roman Ptolemy (AD 86–161).

text: Zhang applied his extensive knowledge of mechanics and gears in several of his inventions. He invented the world's first

entity_name: Hydraulics

text: water-powered

entity_name: Armillary sphere

text: armillary sphere

text: to assist astronomical observation; improved the inflow

text: water clock

text: by adding another tank; and invented the world's first seismoscope, which discerned the

text: cardinal direction

text: of an

text: earthquake

text: away. He improved previous Chinese calculations for

text: pi

text: . In addition to documenting about 2,500 stars in his extensive

text: star catalog

text: , Zhang also posited theories about the

text: Moon

text: and its relationship to the

text: Sun

text: : specifically, he discussed the Moon's sphericity, its illumination by reflected sunlight on one side and the

text: hidden nature

text: of the other, and the nature of

text: solar

text: and

text: lunar

text: eclipse

text: s. His

text: fu

text: (rhapsody) and

text: shi

text: poetry were renowned in his time and studied and analyzed by later Chinese writers. Zhang received many posthumous honors for his scholarship and ingenuity; some modern scholars have compared his work in astronomy to that of the Greco-Roman

text: Ptolemy

text: (AD 86–161).

text: A separate category of solar eclipses is that of the Sun being occluded by a body other than the Earth's moon, as can be observed at points in space away from the Earth's surface. Two examples are when the crew of Apollo 12 observed the Earth eclipse the Sun in 1969 and when the Cassini probe observed Saturn eclipsing the Sun in 2006.

text: A separate category of solar eclipses is that of the Sun being occluded by a body other than the Earth's moon, as can be observed at points in space away from the Earth's surface. Two examples are when the crew of

text: Apollo 12

text: observed the

text: Earth eclipse the Sun

text: in 1969 and when the

text: Cassini

text: probe

text: observed

text: Saturn eclipsing the Sun

text: in 2006.

text: In 1918, Butler's association with Carnegie led to him being invited to witness and record the 1918 Solar eclipse that was observed from Baker City in Oregon. The expedition was organised by the U.S. Naval Observatory and included Samuel Alfred Mitchell as its expert on eclipses. Butler noted later that he used a system of taking notes of the colours using skills he had learnt for transient effects. Usually a sitting for a portrait took two hours but an eclipse would take just over 112 seconds. It has been noted that he had painted Carnegie thirteen times and like the eclipse he could never keep still to allow Butler to make considered notes. His revived interest in physics led to his 1923 book of Painter and Space which coincided with his second visit to a solar eclipse. He also created pictures of planets that were as seen from one of their moons. His last known eclipse visit was in 1932.

text: In 1918, Butler's association with Carnegie led to him being invited to witness and record the

text: 1918 Solar eclipse

text: that was observed from

text: Baker City

text: in

text: Oregon

text: . The expedition was organised by the

text: U.S. Naval Observatory

text: and included

text: Samuel Alfred Mitchell

text: as its expert on eclipses. Butler noted later that he used a system of taking notes of the colours using skills he had learnt for transient effects. Usually a sitting for a portrait took two hours but an eclipse would take just over 112 seconds. It has been noted that he had painted Carnegie thirteen times and like the eclipse he could never keep still to allow Butler to make considered notes. His revived interest in physics led to his 1923 book of Painter and Space which coincided with his second visit to a solar eclipse. He also created pictures of planets that were as seen from one of their moons. His last known eclipse visit was in 1932.

text: A partial solar eclipse will occur on March 29, 2025. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: will occur on March 29, 2025. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: This is a list of solar eclipses in the 20th century BC. During the period 2000 to 1901 BC there were 239 solar eclipses of which 84 were partial, 71 were annular (one non-central), 62 were total, and 22 were hybrids. The greatest number of eclipses in one year was four, occurring in 10 different years: 1998 BC, 1983 BC, 1980 BC, 1958 BC, 1940 BC, 1926 BC, 1922 BC, 1918 BC, 1911 BC, and 1904 BC. One month, March 1958 BC, had two eclipses.

text: This is a list of

text: solar eclipse

text: s in the

text: 20th century BC

text: . During the period 2000 to 1901 BC there were 239 solar eclipses of which 84 were partial, 71 were annular (one

text: non-central

text: ), 62 were total, and 22 were hybrids. The greatest number of eclipses in one year was four, occurring in 10 different years: 1998 BC, 1983 BC, 1980 BC, 1958 BC, 1940 BC, 1926 BC, 1922 BC, 1918 BC, 1911 BC, and 1904 BC. One month, March 1958 BC, had two eclipses.

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: However, if two celestial bodies attain the same declination at the time of a conjunction in right ascension (or the same ecliptic latitude at a conjunction in ecliptic longitude), the one that is closer to the Earth will pass in front of the other. In such a case, a syzygy takes place. If one object moves into the shadow of another, the event is an eclipse. For example, if the Moon passes into the shadow of Earth and disappears from view, this event is called a lunar eclipse. If the visible disk of the nearer object is considerably smaller than that of the farther object, the event is called a transit. When Mercury passes in front of the Sun, it is a transit of Mercury, and when Venus passes in front of the Sun, it is a transit of Venus. When the nearer object appears larger than the farther one, it will completely obscure its smaller companion; this is called an occultation. An example of an occultation is when the Moon passes between Earth and the Sun, causing the Sun to disappear either entirely or partially. This phenomenon is commonly known as a solar eclipse. Occultations in which the larger body is neither the Sun nor the Moon are very rare. More frequent, however, is an occultation of a planet by the Moon. Several such events are visible every year from various places on Earth.

text: However, if two celestial bodies attain the same

text: declination

text: at the time of a conjunction in

text: right ascension

text: (or the same ecliptic latitude at a conjunction in ecliptic longitude), the one that is closer to the Earth will pass in front of the other. In such a case, a

text: syzygy

text: takes place. If one object moves into the shadow of another, the event is an

text: eclipse

text: . For example, if the Moon passes into the shadow of Earth and disappears from view, this event is called a

text: lunar eclipse

text: . If the visible disk of the nearer object is considerably smaller than that of the farther object, the event is called a

text: transit

text: . When Mercury passes in front of the Sun, it is a

text: transit of Mercury

text: , and when Venus passes in front of the Sun, it is a

text: transit of Venus

text: . When the nearer object appears larger than the farther one, it will completely obscure its smaller companion; this is called an

text: occultation

text: . An example of an occultation is when the Moon passes between Earth and the Sun, causing the Sun to disappear either entirely or partially. This phenomenon is commonly known as a

text: solar eclipse

text: . Occultations in which the larger body is neither the Sun nor the Moon are very rare. More frequent, however, is an occultation of a planet by the

text: Moon

text: . Several such events are visible every year from various places on Earth.

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

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

text: ellipse

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

text: center of mass

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

text: foci

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

text: similar

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

text: geocentric systems

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

text: Earth–Moon barycenter

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

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

text: Aryabhata described a

text: geocentric

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

text: epicycle

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

text: Moon

text: Mercury

text: Venus

text: , the

text: Sun

text: Mars

text: Jupiter

text: Saturn

text: , and the

text: asterisms

text: Fred Espanak of NASA lists 50 phases of the moon within year 0, showing that it is a full year, not an instant in time. Jean Meeus gives the following explanation:

text: Fred Espanak of

text: NASA

text: lists 50 phases of the moon within year 0, showing that it is a full year, not an instant in time. Jean Meeus gives the following explanation:

text: There were 240 lunar eclipse events between -199 and -100 (200 BCE to 101 BCE)

text: Saturn's rings would be seen from an angle of only 0.019° and be almost invisible, but their shadow on Saturn's disk would be clearly distinguishable. Like our own Moon from Earth, Saturn itself would show regular phases. From Enceladus, the Sun would have a diameter of only 3.5 minutes of arc, one-ninth that of the Moon as seen from Earth.

text: Saturn's rings would be seen from an angle of only 0.019° and be almost invisible, but their shadow on Saturn's disk would be clearly distinguishable. Like our own Moon from Earth, Saturn itself would show regular

text: phase

text: s. From Enceladus, the Sun would have a diameter of only 3.5 minutes of arc, one-ninth that of the Moon as seen from Earth.

text: It is a narrow path for the moon to pass within the penumbra and outside the umbra. It can happen on the Earth's northern or southern penumbral edges. In addition, the size of the penumbra is sometimes too small where the moon enters it to contain the moon. The width of the Earth's penumbra is determined by the sun's angular diameter at the time of the eclipse, and the moon's angular diameter is larger than the sun over part of its elliptical orbit, depending on whether the eclipse occurs at its nearest (perigee) or farthest point (apogee) in its orbit around the earth.  The majority of the time, the size of the moon and the size of the Earth's penumbra where the moon crosses it mean that most eclipses will not be total penumbral in nature.

text: It is a narrow path for the moon to pass within the penumbra and outside the umbra. It can happen on the Earth's northern or southern penumbral edges. In addition, the size of the penumbra is sometimes too small where the moon enters it to contain the moon. The width of the Earth's penumbra is determined by the sun's

text: angular diameter

text: at the time of the eclipse, and the moon's angular diameter is larger than the sun over part of its

text: elliptical orbit

text: , depending on whether the eclipse occurs at its nearest (

text: perigee

text: ) or farthest point (apogee) in its orbit around the earth.  The majority of the time, the size of the moon and the size of the Earth's penumbra where the moon crosses it mean that most eclipses will not be total penumbral in nature.

text: The word is often used in reference to the Sun, Earth, and either the Moon or a planet, where the latter is in conjunction or opposition. Solar and lunar eclipses occur at times of syzygy, as do transits and occultations. The term is often applied when the Sun and Moon are in conjunction (new moon) or opposition (full moon).

text: The word is often used in reference to the

text: Sun

text: Earth

text: , and either the

text: Moon

text: or a

text: planet

text: , where the latter is in

text: conjunction

text: or

text: opposition

text: Solar

text: and

text: lunar

text: eclipse

text: s occur at times of syzygy, as do

text: transits

text: and

text: occultation

text: s. The term is often applied when the Sun and Moon are in conjunction (

text: new moon

text: ) or opposition (

text: full moon

text: In the future, a near feudal colony has risen up around the industrialisation of the Moon, and though technology keeps the deadly natural environment at bay, the four basic essentials of life—air, water, carbon and data—come at a price. Tiny "chibs" placed in the eye to meter usage of these Four Elementals serve as a constant reminder of this. Everyone also has a "familiar": a personalized, holographic avatar that hovers over one shoulder and serves as an interface with the Moon's network, other familiars and even one's physical surroundings. The Moon is controlled by five families, dubbed the Five Dragons: the Australian Mackenzies dominate mineral extraction, the Asamoahs of Ghana control a vast underground agricultural industry, the Russian Vorontsovs run the transportation systems, the Suns of China are masters of technology and the upstart Brazilian Cortas mine helium-3 to power Earth's fusion reactors. These families, and all citizens of the Moon, operate under contracts granted by the Lunar Development Corporation (LDC), the Moon's governing body. The Mackenzies and the Cortas—the oldest and the newest lunar families, respectively—are bitter rivals, and as the novel begins, the long-simmering animosity between them seems reignited.

text: In the future, a near feudal colony has risen up around the industrialisation of the Moon, and though technology keeps the deadly natural environment at bay, the four basic essentials of life—air, water, carbon and data—come at a price. Tiny "chibs" placed in the eye to meter usage of these Four Elementals serve as a constant reminder of this. Everyone also has a "familiar": a personalized, holographic

text: avatar

text: that hovers over one shoulder and serves as an interface with the Moon's network, other familiars and even one's physical surroundings. The Moon is controlled by five families, dubbed the Five Dragons: the Australian Mackenzies dominate mineral extraction, the Asamoahs of Ghana control a vast underground agricultural industry, the Russian Vorontsovs run the transportation systems, the Suns of China are masters of technology and the upstart Brazilian Cortas mine

text: to power Earth's

text: fusion reactor

text: s. These families, and all citizens of the Moon, operate under contracts granted by the Lunar Development Corporation (LDC), the Moon's governing body. The Mackenzies and the Cortas—the oldest and the newest lunar families, respectively—are bitter rivals, and as the novel begins, the long-simmering animosity between them seems reignited.

text: The Moon and Earth orbit a common barycenter every 27.32 days relative to the background stars. When combined with the Earth–Moon system's common orbit around the Sun, the period of the synodic month, from new moon to new moon, is 29.53 days. Viewed from the celestial north pole, the motion of Earth, the Moon, and their axial rotations are all counterclockwise. Viewed from a vantage point above the north poles of both the Sun and Earth, Earth orbits in a counterclockwise direction about the Sun. The orbital and axial planes are not precisely aligned: Earth's axis is tilted some 23.44 degrees from the perpendicular to the Earth–Sun plane (the ecliptic), and the Earth–Moon plane is tilted up to ±5.1 degrees against the Earth–Sun plane. Without this tilt, there would be an eclipse every two weeks, alternating between lunar eclipses and solar eclipses.

text: The Moon and Earth orbit a common

text: barycenter

text: every 27.32 days relative to the background stars. When combined with the Earth–Moon system's common orbit around the Sun, the period of the

text: synodic month

text: , from new moon to new moon, is 29.53 days. Viewed from the

text: celestial north pole

text: , the motion of Earth, the Moon, and their axial rotations are all

text: counterclockwise

text: . Viewed from a vantage point above the north poles of both the Sun and Earth, Earth orbits in a counterclockwise direction about the Sun. The orbital and axial planes are not precisely aligned: Earth's

text: axis is tilted

text: some 23.44 degrees from the perpendicular to the Earth–Sun plane (the

text: ecliptic

text: ), and the Earth–Moon plane is tilted up to ±5.1 degrees against the Earth–Sun plane. Without this tilt, there would be an eclipse every two weeks, alternating between

text: lunar eclipse

text: s and

text: solar eclipse

text: s.

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 saros, a period of 6585.3211 days (14 common years + 4 leap years + 11.321 days, or 13 common years + 5 leap years + 10.321 days), is useful for predicting the times at which nearly identical eclipses will occur. Three periodicities related to lunar orbit, the synodic month, the draconic month, and the anomalistic month coincide almost perfectly each saros cycle. For an eclipse to occur, either the Moon must be located between the Earth and Sun (for a solar eclipse) or the Earth must be located between the Sun and Moon (for a lunar eclipse). This can happen only when the Moon is new or full, respectively, and repeat occurrences of these lunar phases result from solar and lunar orbits producing the Moon's synodic period of 29.53059 days. During most full and new moons, however, the shadow of the Earth or Moon falls to the north or south of the other body. Eclipses occur when the three bodies form a nearly straight line.  Because the plane of the lunar orbit is inclined to that of the earth, this condition occurs only when a full or new Moon is near or in the ecliptic plane, that is when the moon is at one of the two nodes (the ascending or descending node). The period of time for two successive lunar passes through the ecliptic plane (returning to the same node) is termed the draconic month, a 27.21222 day period.  The three-dimensional geometry of an eclipse, when the new or full moon is near one of the nodes, occurs every 5 or 6 months when the Sun is in conjunction or opposition to the Moon and coincidentally also near a node of the Moon's orbit at that time, or twice per eclipse year. Two Saros eclipses have the same appearance and duration due to the distance between the Earth and Moon being nearly the same for each event because the Saros eclipse cycle is also an integer of the anomalistic month, the period of the eccentricity of lunar orbit, 27.5545 days.

text: The saros, a period of 6585.3211 days (14 common years + 4 leap years + 11.321 days, or 13 common years + 5 leap years + 10.321 days), is useful for predicting the times at which nearly identical eclipses will occur. Three periodicities related to lunar orbit, the

text: synodic month

text: , the

text: draconic month

text: , and the

text: anomalistic month

text: coincide almost perfectly each saros cycle. For an eclipse to occur, either the Moon must be located between the Earth and Sun (for a

text: solar eclipse

text: ) or the Earth must be located between the Sun and Moon (for a

text: lunar eclipse

text: ). This can happen only when the Moon is

text: new

text: or

text: full

text: , respectively, and repeat occurrences of these

text: lunar phase

text: s result from solar and lunar orbits producing the Moon's synodic period of 29.53059 days. During most full and new moons, however, the shadow of the Earth or Moon falls to the north or south of the other body. Eclipses occur when the three bodies form a nearly straight line.  Because the plane of the lunar orbit is inclined to that of the earth, this condition occurs only when a full or new Moon is near or in the

text: ecliptic plane

text: , that is when the moon is at one of the two

text: nodes

text: (the ascending or descending node). The period of time for two successive lunar passes through the ecliptic plane (returning to the same node) is termed the draconic month, a 27.21222 day period.  The three-dimensional geometry of an eclipse, when the new or full moon is near one of the nodes, occurs every 5 or 6 months when the Sun is in conjunction or opposition to the Moon and coincidentally also near a node of the Moon's orbit at that time, or twice per

text: eclipse year

text: . Two Saros eclipses have the same appearance and duration due to the distance between the Earth and Moon being nearly the same for each event because the Saros eclipse cycle is also an integer of the anomalistic month, the period of the eccentricity of lunar orbit, 27.5545 days.

text: An annular solar eclipse will occur on June 22, 2085. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.

text: An annular

text: solar eclipse

text: will occur on June 22, 2085. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: annulus

text: (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.

text: An eclipse involving the Sun, Earth, and Moon can occur only when they are nearly in a straight line, allowing one to be hidden behind another, viewed from the third. Because the orbital plane of the Moon is tilted with respect to the orbital plane of the Earth (the ecliptic), eclipses can occur only when the Moon is close to the intersection of these two planes (the nodes). The Sun, Earth and nodes are aligned twice a year (during an eclipse season), and eclipses can occur during a period of about two months around these times. There can be from four to seven eclipses in a calendar year, which repeat according to various eclipse cycles, such as a saros.

text: An eclipse involving the Sun, Earth, and Moon can occur only when they are nearly in a straight line, allowing one to be hidden behind another, viewed from the third. Because the

text: orbital plane of the Moon

text: is tilted with respect to the orbital plane of the Earth (the

text: ecliptic

text: ), eclipses can occur only when the Moon is close to the intersection of these two planes (the

text: node

text: s). The Sun, Earth and nodes are aligned twice a year (during an

text: eclipse season

text: ), and eclipses can occur during a period of about two months around these times. There can be from four to seven eclipses in a calendar year, which repeat according to various

text: eclipse cycle

text: s, such as a

text: saros

text: In the climax of the story, several of Earth's heroes were possessed by Eclipso and transported to the moon during an eclipse. He then absorbed these heroes into his own body, gaining their mass and also their inherent powers. Gordon led a group of heroes armed with solar weapons to the moon in an attempt to defeat Eclipso once and for all. The absorbed heroes were freed in the end, but only after Will Payton destroyed Eclipso's moon base by detonating his own solar-powered body. Eclipso's diamond shards remained on Earth.

text: In the climax of the story, several of Earth's heroes were possessed by Eclipso and transported to the moon during an eclipse. He then absorbed these heroes into his own body, gaining their mass and also their inherent powers. Gordon led a group of heroes armed with solar weapons to the moon in an attempt to defeat Eclipso once and for all. The absorbed heroes were freed in the end, but only after

text: Will Payton

text: destroyed Eclipso's moon base by detonating his own solar-powered body. Eclipso's diamond shards remained on Earth.

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: The phases of the moon are shown in the oculus of the upper part of the dial. It completes a full rotation in 29 days. The week days are shown in an opening at the base of the dial with allegorical subjects for each day of the week.

text: The phases of the moon are shown in the

text: oculus

text: of the upper part of the dial. It completes a full rotation in 29 days. The week days are shown in an opening at the base of the dial with allegorical subjects for each day of the week.

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: On the horizon refraction is slightly greater than the apparent diameter of the Sun, so when the bottom of the sun's disc appears to touch the horizon, the sun's true altitude is negative. If the atmosphere suddenly vanished, the sun would too. By convention, sunrise and sunset refer to times at which the Sun’s upper limb appears on or disappears from the horizon and the standard value for the Sun’s true altitude is −50′: −34′ for the refraction and −16′ for the Sun’s semi-diameter. The altitude of a celestial body is normally given for the center of the body’s disc. In the case of the Moon, additional corrections are needed for the Moon’s horizontal parallax and its apparent semi-diameter; both vary with the Earth–Moon distance.

text: On the horizon refraction is slightly greater than the apparent diameter of the Sun, so when the bottom of the sun's disc appears to touch the horizon, the sun's true altitude is negative. If the atmosphere suddenly vanished, the sun would too. By convention,

text: sunrise

text: and

text: sunset

text: refer to times at which the Sun’s upper limb appears on or disappears from the horizon and the standard value for the Sun’s true altitude is −50′: −34′ for the refraction and −16′ for the Sun’s

text: semi-diameter

text: . The altitude of a celestial body is normally given for the center of the body’s disc. In the case of the

text: Moon

text: , additional corrections are needed for the Moon’s

text: horizontal parallax

text: and its apparent semi-diameter; both vary with the Earth–Moon distance.

text: Earth's Moon is a gray disc in the sky with cratering visible to the naked eye.  It spans, depending on its exact location, 29-33 arcminutes - which is about the size of a thumbnail at arm's length, and is readily identified.  Over 28 days, the moon goes through a full cycle of lunar phases.  People can generally identify phases within a few days by looking at the moon.  Unlike stars and most planets, the light reflected from the moon is bright enough to be seen during the day. (Venus can sometimes be seen even after sunrise.)

text: Earth's

text: Moon

text: is a gray disc in the sky with cratering visible to the naked eye.  It spans, depending on its exact location, 29-33

text: arcminutes

text: - which is about the size of a thumbnail at arm's length, and is readily identified.  Over 28 days, the moon goes through a full cycle of

text: lunar phase

text: s.  People can generally identify phases within a few days by looking at the moon.  Unlike stars and most planets, the light reflected from the moon is bright enough to be seen during the day. (Venus can sometimes be seen even after sunrise.)

text: There are two reasons why the north pole and south pole of the Moon might be attractive locations for a human colony. First, there is evidence that water may be present in some continuously shaded areas near the poles. Second, the Moon's axis of rotation is sufficiently close to being perpendicular to the ecliptic plane that the radius of the Moon's polar circles is less than 50 km. Power collection stations could therefore be plausibly located so that at least one is exposed to sunlight at all times, thus making it possible to power polar colonies almost exclusively with solar energy. Solar power would be unavailable only during a lunar eclipse, but these events are relatively brief and absolutely predictable. Any such colony would therefore require a reserve energy supply that could temporarily sustain a colony during lunar eclipses or in the event of any incident or malfunction affecting solar power collection. Hydrogen fuel cells would be ideal for this purpose, since the hydrogen needed could be sourced locally using the Moon's polar water and surplus solar power. Moreover, due to the Moon's uneven surface some sites have nearly continuous sunlight. For example, Malapert mountain, located near the Shackleton crater at the Lunar south pole, offers several advantages as a site:

text: There are two reasons why the

text: north pole

text: and

text: south pole

text: of the Moon might be attractive locations for a human colony. First, there is evidence that water may be present in some continuously shaded areas near the poles. Second, the Moon's

text: axis of rotation

text: is sufficiently close to being perpendicular to the

text: ecliptic plane

text: that the radius of the Moon's

text: polar circle

text: s is less than 50 km. Power collection stations could therefore be plausibly located so that at least one is exposed to sunlight at all times, thus making it possible to power polar colonies almost exclusively with solar energy. Solar power would be unavailable only during a

text: lunar eclipse

text: , but these events are relatively brief and absolutely predictable. Any such colony would therefore require a reserve energy supply that could temporarily sustain a colony during lunar eclipses or in the event of any incident or malfunction affecting solar power collection. Hydrogen

text: fuel cells

text: would be ideal for this purpose, since the hydrogen needed could be sourced locally using the Moon's polar water and surplus solar power. Moreover, due to the Moon's uneven surface some sites have nearly continuous sunlight. For example,

text: Malapert mountain

text: , located near the

text: Shackleton crater

text: at the Lunar south pole, offers several advantages as a site:

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: Partial melting within the mantle of the Moon gave rise to the eruption of mare basalts on the lunar surface. Analyses of these basalts indicate that the mantle is composed predominantly of the minerals olivine, orthopyroxene and clinopyroxene, and that the lunar mantle is more iron rich than that of the Earth. Some lunar basalts contain high abundances of titanium (present in the mineral ilmenite), suggesting that the mantle is highly heterogeneous in composition. Moonquakes have been found to occur deep within the mantle of the Moon about 1,000 km below the surface. These occur with monthly periodicities and are related to tidal stresses caused by the eccentric orbit of the Moon about the Earth. A few shallow moonquakes with hypocenters located about 100 km below the surface have also been detected, but these occur more infrequently and appear to be unrelated to the lunar tides.

text: Partial melting within the mantle of the Moon gave rise to the eruption of mare basalts on the lunar surface. Analyses of these basalts indicate that the mantle is composed predominantly of the minerals

text: olivine

text: orthopyroxene

text: and

text: clinopyroxene

text: , and that the lunar mantle is more iron rich than that of the Earth. Some lunar basalts contain high abundances of titanium (present in the mineral

text: ilmenite

text: ), suggesting that the mantle is highly heterogeneous in composition.

text: Moonquake

text: s have been found to occur deep within the mantle of the Moon about 1,000 km below the surface. These occur with monthly periodicities and are related to tidal stresses caused by the eccentric orbit of the Moon about the Earth. A few shallow moonquakes with hypocenters located about 100 km below the surface have also been detected, but these occur more infrequently and appear to be unrelated to the lunar tides.

text: A total solar eclipse occurred on March 28-29, 2006. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A total solar eclipse occurs when the Moon's apparent diameter is larger than the Sun's, blocking all direct sunlight, turning day into darkness. Totality occurs in a narrow path across Earth's surface, with the partial solar eclipse visible over a surrounding region thousands of kilometres wide.It was visible from a narrow corridor which traversed half the Earth. The magnitude, that is, the ratio between the apparent sizes of the Moon and that of the Sun, was 1.052, and it was part of Saros 139.

text: A total

text: solar eclipse

text: occurred on March 28-29, 2006. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: is larger than the Sun's, blocking all direct sunlight, turning day into darkness. Totality occurs in a narrow path across Earth's surface, with the partial solar eclipse visible over a surrounding region thousands of kilometres wide.It was visible from a narrow corridor which traversed half the

text: Earth

text: . The

text: magnitude

text: , that is, the ratio between the apparent sizes of the Moon and that of the Sun, was 1.052, and it was part of Saros 139.

text: An annular solar eclipse will occur on January 27, 2074. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.

text: An annular

text: solar eclipse

text: will occur on January 27, 2074. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: annulus

text: Stationed at NASA Goddard Space Flight Center in Maryland for over 20 years, Rodríguez-Arroyo was the Communications System Lead Engineer for the Lunar Reconnaissance Orbiter Mission (LRO), launched in June 2009 and currently orbiting the moon. Currently, Rodriguez-Arroyo is the Communications System Lead Engineer for the Magnetospheric MultiScale Mission (MMS) to be launched in 2015 and will study the electromagnetic iteration between the Sun and Earth.

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

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

text: Sun

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

text: small Solar System bodies

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

text: Hipparchus was born in Nicaea, Bithynia (now Iznik, Turkey), and probably died on the island of Rhodes. He is known to have been a working astronomer at least from 162 to 127 . Hipparchus is considered the greatest ancient astronomical observer and, by some, the greatest overall astronomer of antiquity. He was the first whose quantitative and accurate models for the motion of the Sun and Moon survive. For this he certainly made use of the observations and perhaps the mathematical techniques accumulated over centuries by the Babylonians and other people from Mesopotamia. He developed trigonometry and constructed trigonometric tables, and he solved several problems of spherical trigonometry. With his solar and lunar theories and his trigonometry, he may have been the first to develop a reliable method to predict solar eclipses. His other reputed achievements include the discovery and measurement of Earth's precession, the compilation of the first comprehensive star catalog of the western world, and possibly the invention of the astrolabe, also of the armillary sphere, which he used during the creation of much of the star catalogue.

text: Hipparchus was born in

text: Nicaea

text: Bithynia

text: (now

text: Iznik

text: Turkey

text: ), and probably died on the island of

text: Rhodes

text: . He is known to have been a working astronomer at least from 162 to 127 . Hipparchus is considered the greatest ancient astronomical observer and, by some, the greatest overall astronomer of

text: antiquity

text: . He was the first whose quantitative and accurate models for the motion of the

text: Sun

text: and

text: Moon

text: survive. For this he certainly made use of the observations and perhaps the mathematical techniques accumulated over centuries by the

text: Babylonia

text: ns and other people from

text: Mesopotamia

text: . He developed trigonometry and constructed trigonometric tables, and he solved several problems of

text: spherical trigonometry

text: . With his solar and

text: lunar

text: theories and his trigonometry, he may have been the first to develop a reliable method to predict

text: solar eclipse

text: s. His other reputed achievements include the discovery and measurement of Earth's precession, the compilation of the first comprehensive

text: star catalog

text: of the western world, and possibly the invention of the

text: astrolabe

text: , also of the

text: armillary sphere

text: , which he used during the creation of much of the star catalogue.

text: The Moon's orbit around the Earth is inclined at an angle of just over 5 degrees to the plane of the Earth's orbit around the Sun (the ecliptic). Because of this, at the time of a new moon, the Moon will usually pass to the north or south of the Sun. A solar eclipse can occur only when new moon occurs close to one of the points (known as nodes) where the Moon's orbit crosses the ecliptic.

text: The

text: Moon's orbit

text: around the Earth is inclined at an angle of just over 5 degrees to the plane of the Earth's orbit around the Sun (the

text: ecliptic

text: ). Because of this, at the time of a new moon, the Moon will usually pass to the north or south of the Sun. A solar eclipse can occur only when new moon occurs close to one of the points (known as

text: node

text: s) where the Moon's orbit crosses the ecliptic.

text: The phases of the moon are also followed closely, but in practice rarely celebrated in a liturgical manner, except by modern groves with a neopagan focus or women's mysteries. Projects are started on a waxing moon and completed on a waning moon. The night of the full moon is considered a time of rejoicing; while the night of the new moon is a solemn occasion, calling for vigils and meditation.

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

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

text: counterclockwise

text: when viewed from above the Sun's

text: north pole

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

text: Venus

text: and

text: Uranus

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

text: protoplanet

text: collided with Uranus, causing the skewed orientation.

text: An annular solar eclipse occurred on October 3, 2005 with a magnitude of 0.958. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.It was visible from a narrow corridor through the Iberian peninsula and Africa. A partial eclipse was seen from the much broader path of the Moon's penumbra, including all of Europe, Africa and southwestern Asia.

text: An annular

text: solar eclipse

text: occurred on October 3, 2005 with a magnitude of 0.958. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: annulus

text: (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.It was visible from a narrow corridor through the

text: Iberian peninsula

text: and

text: Africa

text: . A

text: partial eclipse

text: was seen from the much broader path of the

text: Moon

text: 's

text: penumbra

text: , including all of

text: Europe

text: Africa

text: and southwestern

text: Asia

text: An annular solar eclipse will occur on November 15, 2077. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.

text: An annular

text: solar eclipse

text: will occur on November 15, 2077. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: annulus

text: 7194 Susanrose (provisional designation: 1993 SR) is a main-belt minor planet.  It was discovered by Henry E. Holt at the Palomar Observatory in San Diego County, California, on September 18, 1993.  It is named after Susan Rose, an American amateur astronomer and astronomy enthusiast. Susan Rose, born Susan F. Campbell, née Brown, Farrell, Aug 9, 1952, Brooklyn, NY, US James Madison HS 1970, Brooklyn College 1974; BS Geology, minor Oceanography and Physics. An avid amateur astronomer since the age of 2, called a moonagazer by her great grandmother who chastised her mother for allowing her to stare at the moon. Member Amateur Observers' Society of NY, AOS, (http://www.aosny.org) 1973–present, Recording Secretary 1989-1992, President 1992-2009, President Emeritus 2009–presentAOS Observatory in Southold, NY, renamed Susan F. Rose Observatory Aug 8, 2009, http://www.skyandtelescope.com/news/home/52891802.htmlRecipient NERAL, Northeast Region of the Astronomical League, 2002 Walter Scott Houston Award, http://www.neral.org/pastawards.htmCaldwell Club Administrator for the Astronomical League, 2001–presentTotal Solar Eclipse, Feb 26, 1979 from Lewistown, Montana, USAnnular Solar Eclipse, May 30, 1984, from Atlanta, Georgia, USTotal Solar Eclipse, July 11, 1991, from Ruiz, MexicoAnnular Solar Eclipse, Jan 4, 1992, from San Francisco, California, USAnnular Solar Eclipse, May 10, 1994, Rochester, New York, USTotal Solar Eclipse, Feb 26, 1998, from SS Veendam in the CaribbeanAnnular Solar Eclipse, June 10, 2002, MexicoHalley's Comet, Galapagos Islands, March 1985Transit of Venus, June 8, 2004, Jones Beach, Long Island, NY, USHall of Science, Queens, NY, Planet Earth Lab Instructor, Planetarium Assistant Director, 1974-1981Air Traffic Controller, JFK Airport, 1981-2008, retired

text: 7194 Susanrose (provisional designation: 1993 SR) is a

text: main-belt

text: minor planet

text: .  It was discovered by

text: Henry E. Holt

text: at the

text: Palomar Observatory

text: in

text: San Diego County

text: California

text: A partial lunar eclipse occurs when only a portion of the moon enters the umbra. When the moon travels completely into the Earth's umbra, one observes a total lunar eclipse. The moon's speed through the shadow is about one kilometer per second (2,300 mph), and totality may last up to nearly 107 minutes. Nevertheless, the total time between the moon's first and last contact with the shadow is much longer and could last up to four hours. The relative distance of the moon from the Earth at the time of an eclipse can affect the eclipse's duration. In particular, when the moon is near its apogee, the farthest point from the Earth in its orbit, its orbital speed is the slowest. The diameter of the umbra does not decrease appreciably within the changes in the orbital distance of the moon. Thus, a totally eclipsed moon occurring near apogee will lengthen the duration of totality.

text: A partial lunar eclipse occurs when only a portion of the moon enters the umbra. When the moon travels completely into the Earth's umbra, one observes a total lunar eclipse. The moon's speed through the shadow is about one kilometer per second (2,300 mph), and totality may last up to nearly 107 minutes. Nevertheless, the total time between the moon's first and last contact with the shadow is much longer and could last up to four hours. The relative distance of the moon from the Earth at the time of an eclipse can affect the eclipse's duration. In particular, when the moon is near its

text: apogee

text: , the farthest point from the Earth in its orbit, its orbital speed is the slowest. The diameter of the umbra does not decrease appreciably within the changes in the orbital distance of the moon. Thus, a totally eclipsed moon occurring near apogee will lengthen the duration of totality.

text: A partial solar eclipse occurred on July 1, 2011. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.This is the first solar eclipse of saros series 156, only visible as a partial solar eclipse in a small area south of South Africa and north of Antarctica. At greatest eclipse, the magnitude is just 0.097. It is the first new saros series to begin since saros 155 began with the partial solar eclipse of June 17, 1928.

text: A partial

text: solar eclipse

text: occurred on July 1, 2011. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: , thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.This is the first solar eclipse of

text: saros series 156

text: , only visible as a partial solar eclipse in a small area south of

text: South Africa

text: and north of

text: Antarctica

text: . At greatest eclipse, the

text: magnitude

text: is just 0.097. It is the first new saros series to begin since

text: saros 155

text: began with the partial

text: solar eclipse of June 17, 1928

text: Tidal flow occurs due to the moving mass of water with speed and direction as caused by the gravitational forces of the sun and the moon, and centrifugal and inertial forces on the Earth's waters. Due to its proximity to the earth, the moon exerts roughly twice the tide raising force of the sun. The gravitational forces of the sun and moon and the centrifugal/inertial forces caused by the rotation of the earth around the center of mass of the earth-moon system create two "bulges" in the Earth's oceans: one closest to the moon, and the other on the opposite side of the globe.(CNW Group, 2008). This kind of energy is unique and different from traditional hydropower that has been around for centuries. There is no need to build a dam. Essentially a turbine is stuck in naturally flowing water. As the water flows, it turns a turbine. That is converted to electricity.

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

entity_name: Philosophiæ Naturalis Principia Mathematica

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: An annular solar eclipse occurred on January 26, 2009. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.It had a magnitude of 0.92 and was visible from a narrow corridor beginning in the south Atlantic Ocean and sweep eastward 900 km south of Africa, slowly curving northeast through the Indian Ocean.  Its first landfall was in the Cocos Islands followed by southern Sumatra and western Java.  It continued somewhat more easterly across central Borneo, across the northwestern edge of Celebes, then ending just before Mindanao, Philippines.

text: An annular

text: solar eclipse

text: occurred on January 26, 2009. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: annulus

text: (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.It had a

text: magnitude

text: of 0.92 and was visible from a narrow corridor beginning in the south

text: Atlantic Ocean

text: and sweep eastward 900 km south of Africa, slowly curving northeast through the

text: Indian Ocean

text: .  Its first landfall was in the

text: Cocos Islands

text: followed by southern

text: Sumatra

text: and western

text: Java

text: .  It continued somewhat more easterly across central

text: Borneo

text: , across the northwestern edge of

text: Celebes

text: , then ending just before

text: Mindanao

text: Philippines

text: According to Lucio Russo, Seleucus' arguments for a heliocentric theory were probably related to the phenomenon of tides. The annual cycle of tides (which was studied by Seleucus) can indeed hardly be explained in a geocentric system. Seleucus correctly theorized that tides were caused by the Moon, explaining that the interaction was mediated by the pneuma. He noted that the tides varied in time and strength in different parts of the world. According to Lucio Russo, Seleucus ascribed tides both to the Moon and to a whirling motion of the Earth, which could be interpreted as the motion of the Earth around the Earth-Moon center of mass.

text: According to

text: Lucio Russo

text: , Seleucus' arguments for a heliocentric theory were probably related to the phenomenon of

text: tide

text: s. The annual cycle of tides (which was studied by Seleucus) can indeed hardly be explained in a geocentric system. Seleucus correctly theorized that

text: tide

text: s were caused by the

text: Moon

text: , explaining that the interaction was mediated by the

text: pneuma

text: . He noted that the tides varied in time and strength in different parts of the world. According to

text: Lucio Russo

text: , Seleucus ascribed

text: tide

text: s both to the

text: Moon

text: and to a whirling motion of the

text: Earth

text: , which could be interpreted as the motion of the

text: Earth

text: around the

text: Earth

text: Moon

text: center of mass

text: The Jovilabe is certainly connected to Galileo's efforts to determine the orbital periods of Jupiter's moons, whose discovery he announced in 1610 in Sidereus Nuncius, and to compute the times of their eclipses. Galileo immediately realized that eclipses of Jupiter's moons could provide a precise method to determine longitude. The instrument is engraved with tables showing the mean motions of each of the four moons. Two connected disks of different diameters are rotated by means of a movable rod. They are used to create a "view from the Sun" of the movements of Jupiter's moons observed from the Earth (movements that seem irregular because of the heliocentric motions of the Earth and Jupiter). Galileo began the systematic study of the periods of Jupiter's moons in 1611, developing a micrometer for the purpose. He compiled tables of the periods that he offered, with his telescopes, first to the King of Spain (1611, 1612, 1616, and 1627-1628), then to the States General of Holland (1637-1641). To convince his Spanish interlocutors that Jupiter and its moons could be observed on unstable ground, such as a ship's deck, Galileo designed a special helmet carrying a small telescope on a hinged mount. The device was named the celatone (celata = "helmet" in Italian). In this second proposal, he also described the advantages of applying the pendulum to the clock. Despite the interest they aroused, neither of his proposals were accepted.

text: The Jovilabe is certainly connected to

text: Galileo

text: 's efforts to determine the

text: orbital period

text: s of

text: Jupiter's moons

text: , whose discovery he announced in 1610 in

text: Sidereus Nuncius

text: , and to compute the times of their

text: eclipse

text: s. Galileo immediately realized that

text: eclipse

text: s of

text: Jupiter

text: 's moons could provide a precise method to determine

text: longitude

text: . The instrument is engraved with tables showing the mean motions of each of the four moons. Two connected disks of different diameters are rotated by means of a movable rod. They are used to create a "view from the

text: Sun

text: " of the movements of Jupiter's moons observed from the

text: Earth

text: (movements that seem irregular because of the

text: heliocentric

text: motions of the Earth and Jupiter). Galileo began the systematic study of the periods of Jupiter's moons in 1611, developing a

text: micrometer

text: for the purpose. He compiled tables of the periods that he offered, with his

text: telescope

text: s, first to the King of Spain (1611, 1612, 1616, and 1627-1628), then to the States General of Holland (1637-1641). To convince his Spanish interlocutors that Jupiter and its moons could be observed on unstable ground, such as a ship's deck, Galileo designed a special helmet carrying a small telescope on a hinged mount. The device was named the

text: celatone

text: (celata = "helmet" in Italian). In this second proposal, he also described the advantages of applying the

text: pendulum

text: to the

text: clock

text: . Despite the interest they aroused, neither of his proposals were accepted.

text: When the Moon, as seen from Earth, is a narrow crescent, the Earth as seen from the Moon is almost fully lit by the Sun. Often, the part of the Moon that is not directly lit by the Sun is sufficiently brightly lit by light reflected from the Earth to be easily visible from Earth. This phenomenon is called "earthshine", and is sometimes picturesquely described as "the old moon in the new moon's arms" or, as pictured here, "the new moon in the old moon's arms".

text: When the Moon, as seen from Earth, is a narrow crescent, the Earth as seen from the Moon is almost fully lit by the Sun. Often, the part of the Moon that is not directly lit by the Sun is sufficiently brightly lit by light reflected from the Earth to be easily visible from Earth. This phenomenon is called "

text: earthshine

text: ", and is sometimes picturesquely described as "the old moon in the new moon's arms" or, as pictured here, "the new moon in the old moon's arms".

text: An annular solar eclipse will occur on October 3, 2043. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.

text: An annular

text: solar eclipse

text: will occur on October 3, 2043. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: annulus

text: This is a list of solar eclipses in the 20th century. During the period 1901 to 2000 there were 228 solar eclipses of which 78 were partial, 73 were annular (two non-central), 71 were total (three non-central) and 6 were hybrids. The greatest number of eclipses in one year was five, in 1935, and one month, July 2000, had two eclipses.

text: This is a list of solar eclipses in the 20th century. During the period 1901 to 2000 there were 228 solar eclipses of which 78 were partial, 73 were annular (two

text: non-central

text: ), 71 were total (three non-central) and 6 were hybrids. The greatest number of eclipses in one year was five, in 1935, and one month, July 2000, had two eclipses.

text: A total solar eclipse will occur on April 9, 2043. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A total solar eclipse occurs when the Moon's apparent diameter is larger than the Sun's, blocking all direct sunlight, turning day into darkness. Totality occurs in a narrow path across Earth's surface, with the partial solar eclipse visible over a surrounding region thousands of kilometres wide.It will be unusual in that while it is a total solar eclipse, it is not a central solar eclipse.

text: A total

text: solar eclipse

text: will occur on April 9, 2043. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: is larger than the Sun's, blocking all direct sunlight, turning day into darkness. Totality occurs in a narrow path across Earth's surface, with the partial solar eclipse visible over a surrounding region thousands of kilometres wide.It will be unusual in that while it is a total solar eclipse, it is not a central solar eclipse.

text: The approximate age of the moon, and hence the approximate phase, can be calculated for any date by calculating the number of days since a known new moon (such as January 1, 1900 or August 11, 1999) and reducing this modulo 29.530588853 (the length of a synodic month). The difference between two dates can be calculated by subtracting the Julian Day Number of one from that of the other, or there are simpler formulae giving (for instance) the number of days since December 31, 1899. However, this calculation assumes a perfectly circular orbit and makes no allowance for the time of day at which the new moon happened, therefore may be incorrect by several hours (it also becomes less accurate the larger the difference between the required date and the reference date); it is accurate enough to use in a novelty clock application showing moon phase, but specialist usage taking account of lunar apogee and perigee requires a more elaborate calculation.

text: The approximate age of the moon, and hence the approximate phase, can be calculated for any date by calculating the number of days since a known new moon (such as January 1, 1900 or August 11, 1999) and reducing this

text: modulo

text: 29.530588853 (the length of a synodic month). The difference between two dates can be calculated by subtracting the

text: Julian Day Number

text: of one from that of the other, or there are simpler formulae giving (for instance) the number of days since December 31, 1899. However, this calculation assumes a perfectly circular orbit and makes no allowance for the time of day at which the new moon happened, therefore may be incorrect by several hours (it also becomes less accurate the larger the difference between the required date and the reference date); it is accurate enough to use in a novelty clock application showing moon phase, but specialist usage taking account of lunar apogee and perigee requires a more elaborate calculation.

text: The Warlpiri people explain a solar eclipse as being the Sun-woman being hidden by the Moon-man as he makes love to her. This explanation is shared by other groups, such as the Wirangu.

text: The

text: Warlpiri people

text: explain a

text: solar eclipse

text: as being the Sun-woman being hidden by the Moon-man as he makes love to her. This explanation is shared by other groups, such as the

text: Wirangu

text: A partial solar eclipse occurred on March 28, 1968. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: occurred on March 28, 1968. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: While amateur observers were unable to detect transmissions from the lander, Chinese officials reported that the craft was still operating its UV Camera and Telescope as it entered its 14th lunar night on 14 January 2015. On 18 April 2014, Wang Jianyu, deputy secretary general of the Chinese Society of Space Research stated that the failure was not mechanical, but electrical, and they were looking to bypass it. He also explained, "The temperature on the Moon is considerably lower than our previous estimation, adding that "certain components may be suffering from "frostbite". During 15 April, the Chang'e 3 mission, including its Yutu rover, witnessed a total eclipse of the Sun by the Earth from surface of the Moon.

text: While amateur observers were unable to detect transmissions from the lander, Chinese officials reported that the craft was still operating its UV Camera and Telescope as it entered its 14th lunar night on 14 January 2015. On 18 April 2014, Wang Jianyu, deputy secretary general of the Chinese Society of Space Research stated that the failure was not mechanical, but electrical, and they were looking to bypass it. He also explained, "The temperature on the Moon is considerably lower than our previous estimation, adding that "certain components may be suffering from "frostbite". During 15 April, the Chang'e 3 mission, including its Yutu rover, witnessed a

text: total eclipse of the Sun

text: by the Earth from surface of the Moon.

text: In representations of the Solar System, it is common to draw the trajectory of Earth from the point of view of the Sun, and the trajectory of the Moon from the point of view of Earth. This could give the impression that the Moon orbits Earth in such a way that sometimes it goes backwards when viewed from the Sun's perspective. Because the orbital velocity of the Moon around Earth (1 km/s) is small compared to the orbital velocity of Earth about the Sun (30 km/s), this never happens. There are no rearward loops in the Moon's solar orbit.

text: In representations of the

text: Solar System

text: , it is common to draw the trajectory of Earth from the point of view of the Sun, and the trajectory of the Moon from the point of view of Earth. This could give the impression that the Moon orbits Earth in such a way that sometimes it goes backwards when viewed from the Sun's perspective. Because the orbital velocity of the Moon around Earth (1 km/s) is small compared to the orbital velocity of Earth about the Sun (30 km/s), this never happens. There are no rearward loops in the Moon's solar orbit.

text: None of Jupiter's moons have more than traces of atmosphere, so their skies are black or very nearly so. For an observer on one of the moons, the most prominent feature of the sky by far would be Jupiter. For an observer on Io, the closest large moon to the planet, Jupiter's apparent diameter would be about 20° (38 times the visible diameter of the Moon, covering 1% of Io's sky). An observer on Metis, the innermost moon, would see Jupiter's apparent diameter increased to 68° (130 times the visible diameter of the Moon, covering 18% of Metis's sky). A "full Jupiter" over Metis shines with about 4% of the Sun's brightness (light on Earth from a full moon is 400 thousand times dimmer than sunlight).

text: None of Jupiter's moons have more than traces of atmosphere, so their skies are black or very nearly so. For an observer on one of the moons, the most prominent feature of the sky by far would be Jupiter. For an observer on

text: Io

text: , the closest large moon to the planet, Jupiter's apparent diameter would be about 20° (38 times the visible diameter of the Moon, covering 1% of Io's sky). An observer on

text: Metis

text: , the innermost moon, would see Jupiter's apparent diameter increased to 68° (130 times the visible diameter of the Moon, covering 18% of Metis's sky). A "full Jupiter" over Metis shines with about 4% of the Sun's brightness (light on Earth from a full moon is 400 thousand times dimmer than sunlight).

text: The Moon makes a complete orbit around Earth with respect to the fixed stars about once every 27.3 days (its sidereal period). However, because Earth is moving in its orbit around the Sun at the same time, it takes slightly longer for the Moon to show the same phase to Earth, which is about 29.5 days (its synodic period). Unlike most satellites of other planets, the Moon orbits closer to the ecliptic plane than to the planet's equatorial plane. The Moon's orbit is subtly perturbed by the Sun and Earth in many small, complex and interacting ways. For example, the plane of the Moon's orbital motion gradually rotates, which affects other aspects of lunar motion. These follow-on effects are mathematically described by Cassini's laws.

text: The Moon makes a complete orbit around Earth with respect to the fixed stars about once every 27.3 days (its

text: sidereal period

text: ). However, because Earth is moving in its orbit around the Sun at the same time, it takes slightly longer for the Moon to show the same

text: phase

text: to Earth, which is about 29.5 days (its

text: synodic period

text: ). Unlike most satellites of other planets, the Moon orbits closer to the

text: ecliptic plane

text: than to the planet's

text: equatorial plane

text: . The Moon's orbit is subtly

text: perturbed

text: by the Sun and Earth in many small, complex and interacting ways. For example, the plane of the Moon's orbital motion

text: gradually rotates

text: , which affects other aspects of lunar motion. These follow-on effects are mathematically described by

text: Cassini's laws

text: Constructions like those in Newton's diagram can be repeated for many different positions of the Moon in its orbit. For each position, the result is a perturbation vector like LS1 or LS2 in the second diagram. Shown here is an often-presented form of the diagram that summarises sizes and directions of the perturbation vectors for many different positions of the Moon in its orbit. Each small arrow is a perturbation vector like LS, applicable to the Moon in the particular position around the orbit from which the arrow begins. The perturbations on the Moon when it is nearly in line along the Earth-Sun axis, i.e. near new or full moon, point outwards, away from the Earth. When the Moon-Earth line is 90° from the Earth-Sun axis they point inwards, towards the Earth, with a size that is only half the maximum size of the axial (outwards) perturbations. (Newton gave a rather good quantitative estimate for the size of the solar perturbing force: at quadrature where it adds to the Earth's attraction he put it at 1/178.725 of the mean terrestrial attraction, and twice as much as that at the new and full moons where it opposes and diminishes the Earth's attraction.)

text: Constructions like those in Newton's diagram can be repeated for many different positions of the Moon in its orbit. For each position, the result is a perturbation vector like LS1 or LS2 in the second diagram. Shown here is an often-presented form of the diagram that summarises sizes and directions of the perturbation vectors for many different positions of the Moon in its orbit. Each small arrow is a perturbation vector like LS, applicable to the Moon in the particular position around the orbit from which the arrow begins. The perturbations on the Moon when it is nearly in line along the Earth-Sun axis, i.e. near new or full moon, point outwards, away from the Earth. When the Moon-Earth line is 90° from the Earth-Sun axis they point inwards, towards the Earth, with a size that is only half the maximum size of the axial (outwards) perturbations. (Newton gave a rather good quantitative estimate for the size of the solar perturbing force: at

text: quadrature

text: where it adds to the Earth's attraction he put it at 1/178.725 of the mean terrestrial attraction, and twice as much as that at the new and full moons where it opposes and diminishes the Earth's attraction.)

text: The astronomical phenomena of the solar eclipse and lunar eclipse had been observed in the 4th century BC by astronomers Gan De and Shi Shen; the latter gave instructions on predicting the eclipses based on the relative position of the Moon to the Sun. The philosopher Wang Chong argued against the 'radiating influence' theory of Jing Fang's writing in the 1st century BC and that of Zhang Heng (78–139); the latter two correctly hypothesized that the brightness of the Moon was merely light reflected from the Sun. Jing Fang had written in the 1st century BC of how it was long accepted in China that the Sun and Moon were spherical in shape ('like a crossbow bullet'), not flat. Shen Kuo also wrote of solar and lunar eclipses in this manner, yet expanded upon this to explain why the celestial bodies were spherical, going against the 'flat earth' theory for celestial bodies. However, there is no evidence to suggest that Shen Kuo supported a round earth theory, which was introduced into Chinese science by Matteo Ricci and Xu Guangqi in the 17th century. When the Director of the Astronomical Observatory asked Shen Kuo if the shapes of the Sun and Moon were round like balls or flat like fans, Shen Kuo explained that celestial bodies were spherical because of knowledge of waxing and waning of the Moon. Much like what Zhang Heng had said, Shen Kuo likened the Moon to a ball of silver, which does not produce light, but simply reflects light if provided from another source (the Sun). He explained that when the Sun's light is slanting, the Moon appears full. He then explained if one were to cover any sort of sphere with white powder, and then viewed from the side it would appear to be a crescent, hence he reasoned that celestial bodies were spherical. He also wrote that, although the Sun and Moon were in conjunction and opposition with each other once a month, this did not mean the Sun would be eclipsed every time their paths met, because of the small obliquity of their orbital paths.

text: The astronomical phenomena of the

text: solar eclipse

text: and

text: lunar eclipse

text: had been observed in the 4th century BC by astronomers

text: Gan De

text: and

text: Shi Shen

text: ; the latter gave instructions on predicting the eclipses based on the relative position of the Moon to the Sun. The philosopher Wang Chong argued against the 'radiating influence' theory of

text: Jing Fang

text: 's writing in the 1st century BC and that of

text: Zhang Heng

text: (78–139); the latter two correctly hypothesized that the brightness of the Moon was merely light reflected from the Sun. Jing Fang had written in the 1st century BC of how it was long accepted in China that the Sun and Moon were

text: spherical

text: in shape ('like a

text: crossbow

text: bullet'), not flat. Shen Kuo also wrote of solar and lunar eclipses in this manner, yet expanded upon this to explain why the celestial bodies were spherical, going against the '

text: flat earth

text: ' theory for celestial bodies. However, there is no evidence to suggest that Shen Kuo supported a round earth theory, which was introduced into Chinese science by

text: Matteo Ricci

text: and

text: Xu Guangqi

text: in the 17th century. When the Director of the Astronomical

text: Observatory

text: asked Shen Kuo if the shapes of the Sun and Moon were round like balls or flat like fans, Shen Kuo explained that celestial bodies were spherical because of knowledge of waxing and waning of the Moon. Much like what Zhang Heng had said, Shen Kuo likened the Moon to a ball of silver, which does not produce light, but simply reflects light if provided from another source (the Sun). He explained that when the Sun's light is slanting, the Moon appears full. He then explained if one were to cover any sort of sphere with white powder, and then viewed from the side it would appear to be a crescent, hence he reasoned that celestial bodies were spherical. He also wrote that, although the Sun and Moon were in conjunction and opposition with each other once a month, this did not mean the Sun would be eclipsed every time their paths met, because of the small obliquity of their orbital paths.

text: A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.This was the first of four partial solar eclipses in 2011, with the others occurring on June 1, 2011, July 1, 2011, and November 25, 2011.

text: A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: , thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.This was the first of four partial solar eclipses in 2011, with the others occurring on

text: June 1, 2011

text: July 1, 2011

text: , and

text: November 25, 2011

text: Book III covers the mediaeval Quadrivium, the four subjects which supplemented the Trivium being mathematics, geometry, music and astronomy. He argues that there are infinitely many numbers, as you can always add one (or any other number) to whatever number you think is the limit. He attributes geometry to Ancient Egypt, arguing that because the River Nile flooded and covered the land with mud, geometry was needed to mark out people's land "with lines and measures". Isidore distinguishes astronomy from astrology, and covers the world, the sky and the celestial sphere, the zodiac, the sun, moon, stars, Milky Way, planets and the names of the stars. He derives the curved (curvus) vault of the heavens from the Latin word for "upside-down" (conversus). He explains eclipses of the sun as the moon coming between the earth and the sun, and eclipses of the moon as happening when it runs into the shadow of the earth. He condemns the Roman naming of the planets after their gods: Jupiter, Saturn, Mars, Venus, and Mercury.

text: Book III covers the mediaeval

text: Quadrivium

text: , the four subjects which supplemented the Trivium being

text: mathematics

text: geometry

text: music

text: and

text: astronomy

text: . He argues that there are infinitely many numbers, as you can always add one (or any other number) to whatever number you think is the limit. He attributes geometry to

text: Ancient Egypt

text: , arguing that because the

text: River Nile

text: flooded and covered the land with mud, geometry was needed to mark out people's land "with lines and measures". Isidore distinguishes astronomy from

text: astrology

text: , and covers the world, the sky and the celestial sphere, the

text: zodiac

text: , the sun, moon, stars,

text: Milky Way

text: , planets and the names of the stars. He derives the curved (curvus) vault of the heavens from the Latin word for "upside-down" (conversus). He explains eclipses of the sun as the moon coming between the earth and the sun, and eclipses of the moon as happening when it runs into the shadow of the earth. He condemns the Roman naming of the planets after their gods: Jupiter, Saturn, Mars, Venus, and Mercury.

text: In the photograph of the Brescia clock above, the triangle, square, and star in the center of the dial show these aspects (the third, fourth, and sixth phases) of (presumably) the moon.

text: The Blue Moon is covered in life-giving water and an atmosphere so dense that enormous creatures hypothetically can take flight. The Blue Moon orbits a Water Cloud Jovian planet (a Jupiter-like planet that is cool enough to have visible rain clouds in its atmosphere) orbiting a close binary star system. The Blue Moon itself is roughly an earth mass but has an air pressure around three times that of Earth's at sea level.

text: The Blue Moon is covered in life-giving water and an

text: atmosphere

text: so dense that enormous creatures hypothetically can take flight. The Blue Moon orbits a

text: Water Cloud Jovian planet

text: (a Jupiter-like planet that is cool enough to have visible rain clouds in its atmosphere) orbiting a close binary star system. The Blue Moon itself is roughly an earth mass but has an air pressure around three times that of Earth's at sea level.

text: When the Italian physicist Galileo Galilei first observed the planet in the early 17th century, he found it showed phases like the Moon, varying from crescent to gibbous to full and vice versa. When Venus is furthest from the Sun in the sky, it shows a half-lit phase, and when it is closest to the Sun in the sky, it shows as a crescent or full phase. This could be possible only if Venus orbited the Sun, and this was among the first observations to clearly contradict the Ptolemaic geocentric model that the Solar System was concentric and centred on Earth.

text: When the Italian physicist

text: Galileo Galilei

text: first observed the planet in the early 17th century, he found it showed

text: phases

text: like the Moon, varying from crescent to gibbous to full and vice versa. When Venus is furthest from the Sun in the sky, it shows a

text: half-lit phase

text: , and when it is closest to the Sun in the sky, it shows as a crescent or full phase. This could be possible only if Venus orbited the Sun, and this was among the first observations to clearly contradict the

text: Ptolemaic

text: geocentric model

text: that the Solar System was concentric and centred on Earth.

text: "sky, day, god"| Tues-day (< OE Tīwes-dæġ lit. "day of Tīw")| ON tīvar "gods", Týr "Tīw" (the war god)| Iuppiter (Iovis), Old Latin Diū-piter (Diovis) "Jupiter"; diēs "day", deus, dīvus "god"| Zdeús (Di(w)ós) "Zeus"| d(i)yāúḥ (diváḥ, dyōḥ) "heaven", dēváḥ "god"| Av daēva- "demon"| (OCS dĭnĭ (dĭne) "day" < ), Russian divo "miracle"| OPrus deina "day", deiws "god", Lith diena "day", dievas "god"| OIr dīe, W dydd "day"; OIr dia (dē), OW duiu- "God"| tiv "day" Asdovadz  Astwadz "God"  | (gdhinj "I make day"(? mache Tag) < )|||-|  "sun"| sun (< OE sunne)| sauil, sunnō "sun"| sōl "sun"| Homeric hēélios "sun" < *sāwélios| súvar (súraḥ) "sun, light, heavens", sūra-, sūrya "sun"| Av hvarǝ (hūrō) "sun, light, heavens"| OCS slĭnŭce "sun" < *sulnika-, Russian po-solon' "sunwise"| OPrus sauli "sun", sawaiti "week", Lith saulė "sun", savaitė "week"| OIr sūil "eye"; W haul "sun"| Armenian, arev Sun, tsolk reflection, shoghal shine, glare; shogh շող "gleen."| ylli "star" < *sūlo- or *sūli-|||-|  "moon, month"| moon (< OE mōna), month (< OE mōnaþ)| mēna "moon", mēnoþs "month"| mēnsis "month"| Att mḗn, Ion meis, Dor mḗs "month", mḗnē "moon"| mā́s "moon"; mā́sa "month"| Av mā̊ (mā̊ŋhō) "moon"; NPers māh "moon, month"| OCS měsęcĭ "moon, month" < | OPrus miniks "moon", mins "month", Lith mėnulis "moon", mėnesis "month"| OIr mī (mīs) "month" < ;; W mis "month"| amis (amsoy) "month" < | muai "month"| A mañ B meñe "month"; A mañ ñkät B meṃ "moon"||-|  "earth"||| humus "earth"| kʰtʰṓn (kʰtʰonós) "earth", kʰamaí "on the earth"| kṣā́ḥ (acc. kṣā́m, gen. jmáḥ) "earth"| Av zā̊ (acc. ząm, gen. zǝmō) "earth"| OCS zemĭ, zemlja "earth"| OPrus zemê "earth", Lith žemė " earth"| OIr dū "place"; Welsh dyn "man"| degh "place", hogh "earth, soil, land", tsekh "mud, wet soil"| dhe "earth"| A tkaṃ (tkanis), B keṃ "earth"| tēkan (tagnās) "earth"|-|  pl.  "water"| water (< OE wæter)| watō (watins) "water"| Umbrian utur "water", Latin unda "wave"| húdōr (húdatos) "water"| udakám (loc. udán(i), pl. udá), udra "water"| Av aoδa- "spring", vaiδi- "stream"| OCS voda "water", Russian vedro "bucket", | OPrus undan "water", Lith vanduo "water"| OIr u(i)sce "water" < *udeskyo-| get "river" < *wedō, tchur water; terchel to wet| ujë "water"| A wär, B war "water"| wātar (wetenas) "water"|-|  "wood, tree"| tree (< OE trēo)| triu "tree, wood"|| dóru "spear"| dā́ru (drṓs) "wood"| Av dāru- "tree, wood"| OCS drěvo "tree"| OPrus drawê "hole in a tree, hollow tree", Lith drevė "hole in a tree", dirva "soil"| OIr daur "oak", W derwen "oak"| tram "firm",  Western Armenian dzar "tree"| dru "tree"| AB or "wood"| taru "tree"|-|  "wind",  "to blow"| wind (< OE wind); OE wāwan "to blow"| winds "wind"; waian "to blow"| ventus "wind"| áenta (acc.) "wind", áēsi "(he) blows"| vā́taḥ (vānt-) "wind", vāti "(he) blows"| Av vātō "wind", vāiti "(he) blows"| OCS vějǫ (vějetŭ) "to blow"| OPrus witra "wind", Lith vėjas "wind", vėtra "heavy wind"| W gwynt "wind"|  Armenian hov wind|| A want, B yente "wind"| ḫūwanz "wind"|-|  "to snow"| snow (< OE snāw < , snīwan "to snow" < )| snáiws "snow"| nix (nivis) "snow", ninguō (ninguere) "to snow"| nípʰa (acc.) "snow", neípʰei "it snows"| sneha- "snow"| Av snaēža- "to snow"; Shughni žǝnij "snow" < *snaiga-| OCS sněgŭ "snow"| OPrus snaigs "snow", Lith snigti "to snow"| OIr snecht(a)e, W nyf "snow"; OIr snigid "it rains"| W. Armenian, tseun or tsouyn "snow"||||-|  "bonfire"| fire (< OE fȳr < *fuïr)| fōn (funins) "fire"; OHG fuïr (two syllables) < | Umbrian pir "fire" < *pūr, acc. purom-e "into the fire" < *pur-| pũr (purós) "fire"| pāru (pēru) "sun, fire"|| Czech pýř "glowing ash"| OPrus pannu "fire"|| hur (hroy) "fire" < *pū̆r-, hn-oc̣ "furnace" < *pū̆n-|| A por, B puwar, puwār, pwār "fire"| paḫḫur "fire"|-|  "warm"| ?warm (< OE wearm); OE ġierwan "to prepare, cook" < PGerm *garwjan| ?warmjan "to warm"| formus "warm"| tʰermós "warm"| gʰarmáḥ "heat"| Av garǝma- "hot, heat"; OPers Garma-pada-, name of the fourth month, corresponding to June/July, orig. (?) "entrance of the heat"| Russian žar "heat", goret' "to warm" < | OPrus garmê "heat, glowing", Lith žarijos "cinders", žėrėti "to glow"| OIr gorn "fire" < | ǰerm "warm"| Gheg zjarm "fire, heat"| A śärme "heat (of summer)"||-|  "light, brightness"| light (< OE lēoht)| liuhaþ (liuhadis) "light"| lūceō (lūcēre) "to shine", lūx "light"| leukós "bright, shining, white"| rócate "(he) shines", roká- "light", loka- "world, place"| Av raočant- "shining", raočah "light"; OPers raučah "light"| OCS luča "ray, flash" < *loukyā| OPrus lauk "bright", lauksna "star", laukas "field", Lith laukas "outside, field"| OIr luchair "shine"; W llachar "bright", llug "shimmer"| lois (lusoi) "light"|| AB lyuk/luk- "to shine"| luk(k)- "to shine"|-|}

text: "sky, day, god"| Tues-day (<

text: OE

text: Tīwes-dæġ lit. "day of Tīw")|

text: ON

text: tīvar "gods",

text: Týr

text: "Tīw" (the war god)| Iuppiter (Iovis),

text: Old Latin

text: Diū-piter (Diovis) "Jupiter"; diēs "day", deus, dīvus "god"| Zdeús (Di(w)ós) "Zeus"| d(i)yāúḥ (diváḥ, dyōḥ) "heaven", dēváḥ "god"|

text: Av

text: daēva- "demon"| (

text: OCS

text: dĭnĭ (dĭne) "day" < ), Russian divo "miracle"|

text: OPrus

text: deina "day", deiws "god",

text: Lith

text: diena "day", dievas "god"|

text: OIr

text: dīe,

text: W

text: dydd "day";

text: OIr

text: dia (dē),

text: OW

text: duiu- "God"| tiv "day" Asdovadz  Astwadz "God"  | (gdhinj "I make day"(? mache Tag) < )|||-|  "sun"| sun (<

text: OE

text: sunne)| sauil, sunnō "sun"| sōl "sun"|

text: Homeric

text: hēélios "sun" < *sāwélios| súvar (súraḥ) "sun, light, heavens", sūra-, sūrya "sun"|

text: Av

text: hvarǝ (hūrō) "sun, light, heavens"|

text: OCS

text: slĭnŭce "sun" < *sulnika-, Russian po-solon' "sunwise"|

text: OPrus

text: sauli "sun", sawaiti "week",

text: Lith

text: saulė "sun", savaitė "week"|

text: OIr

text: sūil "eye";

text: W

text: haul "sun"| Armenian, arev Sun, tsolk reflection, shoghal shine, glare; shogh շող "gleen."| ylli "star" < *sūlo- or *sūli-|||-|  "moon, month"| moon (<

text: OE

text: mōna), month (<

text: OE

text: mōnaþ)| mēna "moon", mēnoþs "month"| mēnsis "month"|

text: Att

text: mḗn,

text: Ion

text: meis,

text: Dor

text: mḗs "month", mḗnē "moon"| mā́s "moon"; mā́sa "month"|

text: Av

text: mā̊ (mā̊ŋhō) "moon";

text: NPers

text: māh "moon, month"|

text: OCS

text: měsęcĭ "moon, month" < |

text: OPrus

text: miniks "moon", mins "month",

text: Lith

text: mėnulis "moon", mėnesis "month"|

text: OIr

text: mī (mīs) "month" < ;;

text: W

text: mis "month"| amis (amsoy) "month" < | muai "month"| A mañ B meñe "month"; A mañ ñkät B meṃ "moon"||-|  "earth"||| humus "earth"| kʰtʰṓn (kʰtʰonós) "earth", kʰamaí "on the earth"| kṣā́ḥ (acc. kṣā́m, gen. jmáḥ) "earth"|

text: Av

text: zā̊ (acc. ząm, gen. zǝmō) "earth"|

text: OCS

text: zemĭ, zemlja "earth"|

text: OPrus

text: zemê "earth",

text: Lith

text: žemė " earth"|

text: OIr

text: dū "place";

text: Welsh

text: dyn "man"| degh "place", hogh "earth, soil, land", tsekh "mud, wet soil"| dhe "earth"| A tkaṃ (tkanis), B keṃ "earth"| tēkan (tagnās) "earth"|-|  pl.  "water"| water (<

text: OE

text: wæter)| watō (watins) "water"|

text: Umbrian

text: utur "water", Latin unda "wave"| húdōr (húdatos) "water"| udakám (loc. udán(i), pl. udá), udra "water"|

text: Av

text: aoδa- "spring", vaiδi- "stream"|

text: OCS

text: voda "water", Russian vedro "bucket", |

text: OPrus

text: undan "water",

text: Lith

text: vanduo "water"|

text: OIr

text: u(i)sce "water" < *udeskyo-| get "river" < *wedō, tchur water; terchel to wet| ujë "water"| A wär, B war "water"| wātar (wetenas) "water"|-|  "wood, tree"| tree (<

text: OE

text: trēo)| triu "tree, wood"|| dóru "spear"| dā́ru (drṓs) "wood"|

text: Av

text: dāru- "tree, wood"|

text: OCS

text: drěvo "tree"|

text: OPrus

text: drawê "hole in a tree, hollow tree",

text: Lith

text: drevė "hole in a tree", dirva "soil"|

text: OIr

text: daur "oak",

text: W

text: derwen "oak"| tram "firm",  Western Armenian dzar "tree"| dru "tree"| AB or "wood"| taru "tree"|-|  "wind",  "to blow"| wind (<

text: OE

text: wind);

text: OE

text: wāwan "to blow"| winds "wind"; waian "to blow"| ventus "wind"| áenta (acc.) "wind", áēsi "(he) blows"| vā́taḥ (vānt-) "wind", vāti "(he) blows"|

text: Av

text: vātō "wind", vāiti "(he) blows"|

text: OCS

text: vějǫ (vějetŭ) "to blow"|

text: OPrus

text: witra "wind",

text: Lith

text: vėjas "wind", vėtra "heavy wind"|

text: W

text: gwynt "wind"|  Armenian hov wind|| A want, B yente "wind"| ḫūwanz "wind"|-|  "to snow"| snow (<

text: OE

text: snāw < , snīwan "to snow" < )| snáiws "snow"| nix (nivis) "snow", ninguō (ninguere) "to snow"| nípʰa (acc.) "snow", neípʰei "it snows"| sneha- "snow"|

text: Av

text: snaēža- "to snow";

text: Shughni

text: žǝnij "snow" < *snaiga-|

text: OCS

text: sněgŭ "snow"|

text: OPrus

text: snaigs "snow",

text: Lith

text: snigti "to snow"|

text: OIr

text: snecht(a)e,

text: W

text: nyf "snow";

text: OIr

text: snigid "it rains"| W. Armenian, tseun or tsouyn "snow"||||-|  "bonfire"| fire (<

text: OE

text: fȳr < *fuïr)| fōn (funins) "fire";

text: OHG

text: fuïr (two syllables) < |

text: Umbrian

text: pir "fire" < *pūr, acc. purom-e "into the fire" < *pur-| pũr (purós) "fire"| pāru (pēru) "sun, fire"||

text: Czech

text: pýř "glowing ash"|

text: OPrus

text: pannu "fire"|| hur (hroy) "fire" < *pū̆r-, hn-oc̣ "furnace" < *pū̆n-|| A por, B puwar, puwār, pwār "fire"| paḫḫur "fire"|-|  "warm"| ?warm (<

text: OE

text: wearm);

text: OE

text: ġierwan "to prepare, cook" <

text: PGerm

text: *garwjan| ?warmjan "to warm"| formus "warm"| tʰermós "warm"| gʰarmáḥ "heat"|

text: Av

text: garǝma- "hot, heat";

text: OPers

text: Garma-pada-, name of the fourth month, corresponding to June/July, orig. (?) "entrance of the heat"| Russian žar "heat", goret' "to warm" < |

text: OPrus

text: garmê "heat, glowing",

text: Lith

text: žarijos "cinders", žėrėti "to glow"|

text: OIr

text: gorn "fire" < | ǰerm "warm"|

text: Gheg

text: zjarm "fire, heat"| A śärme "heat (of summer)"||-|  "light, brightness"| light (<

text: OE

text: lēoht)| liuhaþ (liuhadis) "light"| lūceō (lūcēre) "to shine", lūx "light"| leukós "bright, shining, white"| rócate "(he) shines", roká- "light", loka- "world, place"|

text: Av

text: raočant- "shining", raočah "light";

text: OPers

text: raučah "light"|

text: OCS

text: luča "ray, flash" < *loukyā|

text: OPrus

text: lauk "bright", lauksna "star", laukas "field",

text: Lith

text: laukas "outside, field"|

text: OIr

text: luchair "shine";

text: W

text: llachar "bright", llug "shimmer"| lois (lusoi) "light"|| AB lyuk/luk- "to shine"| luk(k)- "to shine"|-|}

text: The Moon is in synchronous rotation with Earth, always showing the same face, with its near side marked by dark volcanic maria that fill the spaces between the bright ancient crustal highlands and the prominent impact craters. It is the second-brightest regularly visible celestial object in Earth's sky, after the Sun, as measured by illuminance on Earth's surface. Its surface is actually dark, although compared to the night sky it appears very bright, with a reflectance just slightly higher than that of worn asphalt. Its prominence in the sky and its regular cycle of phases have made the Moon an important cultural influence since ancient times on language, calendars, art, mythology, and, it is often speculated, the menstrual cycles of the female of the human species.

text: The Moon is in

text: synchronous rotation

text: with Earth, always showing the same face, with its

text: near side

text: marked by dark volcanic

text: maria

text: that fill the spaces between the bright ancient crustal highlands and the prominent

text: impact crater

text: s. It is the second-brightest regularly visible

text: celestial object

text: in Earth's sky, after the Sun, as measured by

text: illuminance

text: on Earth's surface. Its surface is actually dark, although compared to the night sky it appears very bright, with a

text: reflectance

text: just slightly higher than that of worn

text: asphalt

text: . Its prominence in the sky and its regular cycle of

text: phases

text: have made the Moon an important cultural influence since ancient times on

text: language

text: calendar

text: s,

text: art

text: mythology

text: , and, it is often speculated, the menstrual cycles of the female of the human species.

text: An annular solar eclipse will occur on February 16, 2045. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.

text: An annular

text: solar eclipse

text: will occur on February 16, 2045. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: annulus

text: An annular solar eclipse will occur on October 2, 2024. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.

text: An annular

text: solar eclipse

text: will occur on October 2, 2024. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: annulus

text: As seen from the Earth, the time it takes for the Moon to return to a node, the draconic month, is less than the time it takes for the Moon to return to the same ecliptic longitude as the Sun: the synodic month. The main reason is that during the time that the Moon has completed an orbit around the Earth, the Earth (and Moon) have completed about  of their orbit around the Sun: the Moon has to make up for this in order to come again into conjunction or opposition with the Sun. Secondly, the orbital nodes of the Moon precess westward in ecliptic longitude, completing a full circle in about  18.60 years, so a draconic month is shorter than a sidereal month. In all, the difference in period between synodic and draconic month is nearly  days. Likewise, as seen from the Earth, the Sun passes both nodes as it moves along its ecliptic path. The period for the Sun to return to a node is called the eclipse or draconic year: about 346.6201 d, which is about  year shorter than a sidereal year because of the precession of the nodes.

text: As seen from the Earth, the time it takes for the Moon to return to a node, the

text: draconic month

text: , is less than the time it takes for the Moon to return to the same ecliptic longitude as the Sun: the

text: synodic month

text: . The main reason is that during the time that the Moon has completed an orbit around the Earth, the Earth (and Moon) have completed about  of their orbit around the Sun: the Moon has to make up for this in order to come again into conjunction or opposition with the Sun. Secondly, the orbital nodes of the Moon

text: precess

text: westward in ecliptic longitude, completing a full circle in about  18.60 years, so a draconic month is shorter than a

text: sidereal month

text: . In all, the difference in period between synodic and draconic month is nearly  days. Likewise, as seen from the Earth, the Sun passes both nodes as it moves along its ecliptic path. The period for the Sun to return to a node is called the

text: eclipse or draconic year

text: : about 346.6201 d, which is about  year shorter than a

text: sidereal year

text: because of the precession of the nodes.

text: This is a list of solar eclipses in the 10th century BC. During the period 1000 to 901 BC there were 226 solar eclipses of which 84 were Partial, 75 were Annular (one non-central), 61 were Total (three non-central), and 6 were hybrids. The greatest number of eclipses in one year was four, occurring in 5 different years: 996 BC, 960 BC, 949 BC, 931 BC, and 913 BC.

text: This is a list of

text: solar eclipses

text: in the 10th century BC. During the period 1000 to 901 BC there were 226 solar eclipses of which 84 were

text: Partial

text: , 75 were

text: Annular

text: (one

text: non-central

text: ), 61 were

text: Total

text: (three non-central), and 6 were hybrids. The greatest number of eclipses in one year was four, occurring in 5 different years: 996 BC, 960 BC, 949 BC, 931 BC, and 913 BC.

text: Set in the year AD 2225, mankind has spread from Earth to inhabit nearly all the planets or nearby moons in colonies and settlements. Space travel has grown and improved to the point of being commonplace. For the inhabitants of the solar system, an astronaut career isn't out of the question, and one of the schools set up to train future space voyagers is the Liebe Delta, a space station positioned somewhere in Earth's orbit. This growth is despite the mysterious phenomenon known as the Geduld, a sea of plasma that suddenly erupted from the sun along the Earth's orbital plane in AD 2137. Stretching from the sun to the edge of the solar system, this area of high temperatures and gravity pressures has never been explained.

text: Set in the year AD 2225, mankind has spread from Earth to inhabit nearly all the planets or nearby moons in colonies and settlements. Space travel has grown and improved to the point of being commonplace. For the inhabitants of the solar system, an astronaut career isn't out of the question, and one of the schools set up to train future space voyagers is the Liebe Delta, a space station positioned somewhere in Earth's orbit. This growth is despite the mysterious phenomenon known as the Geduld, a sea of plasma that suddenly erupted from the sun along the Earth's

text: orbital plane

text: in AD 2137. Stretching from the sun to the edge of the solar system, this area of high temperatures and gravity pressures has never been explained.

text: Although there are two Avestan hymns dedicated to the Moon, she is not a prominent divinity. In both the third Nyaish as well as in the seventh Yasht, the 'moon' more commonly spoken of is the physical moon. In these hymns, the phases of the moon are described at length. Ahura Mazda is described to be the cause of the moon's waxing and waning, and the Amesha Spentas evenly distribute the light of the moon over the earth  (Yasht 7.3, Nyaish 3.5). In Yasht 13.14-16, the Fravashis are said to be responsible for keeping the moon and stars on its appointed course. The sun, moon, and stars revolve around the peak of Hara Berezaiti (Yasht 12.25).

text: Although there are two Avestan hymns dedicated to the Moon, she is not a prominent divinity. In both the third Nyaish as well as in the seventh

text: Yasht

text: , the 'moon' more commonly spoken of is the physical moon. In these hymns, the phases of the moon are described at length.

text: Ahura Mazda

text: is described to be the cause of the moon's waxing and waning, and the

text: Amesha Spenta

text: s evenly distribute the light of the moon over the earth  (Yasht 7.3, Nyaish 3.5). In Yasht 13.14-16, the

text: Fravashi

text: s are said to be responsible for keeping the moon and stars on its appointed course. The sun, moon, and stars revolve around the peak of

text: Hara Berezaiti

text: (Yasht 12.25).

text: An annular solar eclipse will occur on December 16, 2085. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.

text: An annular

text: solar eclipse

text: will occur on December 16, 2085. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: annulus

text: The key difference between a satellite and a quasi-satellite is that the orbit of a satellite of Earth fundamentally depends on the gravity of the Earth–Moon system, whereas the orbit of a quasi-satellite would negligibly change if Earth and the Moon were suddenly removed because a quasi-satellite is orbiting the Sun on an Earth-like orbit in the vicinity of Earth.

text: A partial solar eclipse will occur on February 27, 2036. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: will occur on February 27, 2036. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: In effect, this means that the "tropical year" on the moon is only 347 days long. This is called the draconic year or eclipse year. The "seasons" on the moon fit into this period. For about half of this draconic year, the sun is north of the lunar equator (but at most 1.543°), and for the other half it is south of the lunar equator. Obviously the effect of these seasons is very minor compared to the difference between lunar night and lunar day. At the poles, there are not days and nights of about 15 earth days, but rather the sun will be "up" for 173 days at a time. "Up" here means that the centre of the sun is above the horizon. The sunrise and sunset at the poles each take about 18 days. These polar sunrises and sunsets occur around the time of eclipses (solar or lunar). For example, at the Solar eclipse of March 9, 2016, the moon was near its descending node, and the sun was near the point in the sky where the equator of the moon crosses the ecliptic. When the sun reached that point, the centre of the sun set at the north pole and rose at the south pole.

text: In effect, this means that the "

text: tropical year

text: " on the moon is only 347 days long. This is called the

text: draconic year

text: or eclipse year. The "seasons" on the moon fit into this period. For about half of this draconic year, the sun is north of the lunar equator (but at most 1.543°), and for the other half it is south of the lunar equator. Obviously the effect of these seasons is very minor compared to the difference between lunar night and lunar day. At the poles, there are not days and nights of about 15 earth days, but rather the sun will be "up" for 173 days at a time. "Up" here means that the centre of the sun is above the horizon. The sunrise and sunset at the poles each take about 18 days. These polar sunrises and sunsets occur around the time of eclipses (solar or lunar). For example, at the

text: Solar eclipse of March 9, 2016

text: , the moon was near its descending node, and the sun was near the point in the sky where the equator of the moon crosses the ecliptic. When the sun reached that point, the centre of the sun set at the north pole and rose at the south pole.

text: Space elevator designs for Earth typically have a taper of the tether that provides a uniform stress profile rather than a uniform cross-section. Because the strength requirement of a lunar space elevator is much lower than that of an Earth space elevator, a uniform cross-section is possible for the lunar space elevator. The study done for NASA's Institute of Advanced Concepts states "Current composites have characteristic heights of a few hundred kilometers, which would require taper ratios of about 6 for Mars, 4 for the Moon, and about 6000 for the Earth. The mass of the Moon is small enough that a uniform cross-section lunar space elevator could be constructed, without any taper at all." A uniform cross-section could make it possible for a lunar space elevator to be built in a double-tether pulley configuration. This configuration would greatly simplify repairs of a space elevator compared to a tapered elevator configuration. However a pulley configuration would require a strut at the counterweight hundreds of kilometers long to separate the up-tether from the down-tether and keep them from tangling. A pulley configuration might also allow the system capacity to be gradually expanded by stitching new tether material on at the Lagrange point as the tether rotated.

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: In astronomy,  new moon is the first phase of the Moon, when it orbits as seen from the Earth, the moment when the Moon and the Sun have the same ecliptical longitude.The Moon is not visible at this time except when it is seen in silhouette during a solar eclipse when it is illuminated by earthshine. See the article on phases of the Moon for further details.

text: In astronomy,  new moon is the first

text: phase of the Moon

text: , when it orbits as seen from the Earth, the moment when the

text: Moon

text: and the

text: Sun

text: have the same

text: ecliptical longitude

text: .The Moon is not visible at this time except when it is seen in silhouette during a

text: solar eclipse

text: when it is illuminated by

text: earthshine

text: . See the article on

text: phases of the Moon

text: for further details.

text: There were 242 lunar eclipse events between -1999 and -1900 (2000 BCE to 1901 BCE)

text: Lunar eclipses can occur only at full moon, where the Moon's orbit allows it to pass through Earth's shadow. Lunar eclipses do not occur every month because the Moon usually passes above or below Earth's shadow (which is mostly restricted to the ecliptic plane). Lunar eclipses can occur only when the full moon occurs near the two nodes of the orbit, either the ascending or descending node. This causes eclipses to only occur about every 6 months, and often 2 weeks before or after a solar eclipse at new moon at the opposite node.

text: Lunar eclipse

text: s can occur only at full moon, where the Moon's orbit allows it to pass through Earth's shadow. Lunar eclipses do not occur every month because the Moon usually passes above or below Earth's shadow (which is mostly restricted to the

text: ecliptic plane

text: ). Lunar eclipses can occur only when the full moon occurs near the two

text: nodes of the orbit

text: , either the ascending or descending node. This causes eclipses to only occur about every 6 months, and often 2 weeks before or after a

text: solar eclipse

text: at

text: new moon

text: at the opposite node.

text: The outermost disc is decorated with a fleur-de-lis which represents the sun, and which orbits the dial once every 24 hours. This indicates the hour of the day, counted from I to XII in Roman numerals in first the right and then the left hemispheres of the clockface. This is an example of a 24-hour analog dial. The tail of the sun's fleur-de-lis points to the day in the lunar month on the inner ring.  The half-black, half-silver moon inside the lunar month ring rotates on its axis to show the correct phase of the moon. The earth is represented as a fixed golden ball in the centre of the dial. The Latin inscription "Pereunt et imputantur" below the main dial may be translated as "The hours pass and are reckoned to our account".

text: The outermost disc is decorated with a

text: fleur-de-lis

text: which represents the sun, and which orbits the dial once every 24 hours. This indicates the hour of the day, counted from I to XII in

text: Roman numerals

text: in first the right and then the left hemispheres of the clockface. This is an example of a

text: 24-hour analog dial

text: . The tail of the sun's fleur-de-lis points to the day in the

text: lunar month

text: on the inner ring.  The half-black, half-silver moon inside the lunar month ring rotates on its axis to show the correct

text: phase of the moon

text: . The earth is represented as a fixed golden ball in the centre of the dial. The Latin inscription "Pereunt et imputantur" below the main dial may be translated as "The hours pass and are reckoned to our account".

text: Comet Holmes not only became brighter, but it also swelled in size as its coma expanded. In late October 2007 the coma's apparent diameter increased from 3.3 arcminutes to over 13 arcminutes, about half the diameter of the Moon in the sky. At a distance of around 2 AU, this means that the true diameter of the coma had swelled to over 1 million km, or about 70% of the diameter of the Sun.  By comparison, the Moon is 380,000 km from Earth.   Therefore, during the 2007 outburst of Comet Holmes the coma was a sphere wider than the diameter of the Moon's orbit around Earth.  On 2007  November, the coma had dispersed to a volume larger than the Sun, briefly giving it the largest extended atmosphere in the Solar System.

text: Comet Holmes not only became brighter, but it also swelled in size as its coma expanded. In late October 2007 the

text: coma

text: 's

text: apparent diameter

text: increased from 3.3 arcminutes to over 13 arcminutes, about half the diameter of the Moon in the sky. At a distance of around 2

text: AU

text: , this means that the true diameter of the coma had swelled to over 1 million km, or about 70% of the diameter of the

text: Sun

text: .  By comparison, the

text: Moon

text: is 380,000 km from

text: Earth

text: .   Therefore, during the 2007 outburst of Comet Holmes the coma was a sphere wider than the diameter of the

text: Moon

text: 's orbit around

text: Earth

text: .  On 2007  November, the coma had dispersed to a volume larger than the Sun, briefly giving it the largest extended atmosphere in the Solar System.

text: An annular solar eclipse occurred on June 10, 2002. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.

text: An annular

text: solar eclipse

text: occurred on June 10, 2002. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: annulus

text: There is often confusion between a solar and lunar eclipse. While both involve interactions between the sun, Earth, and moon, they are very different in their interactions.

text: Sunrise occurs at the prime meridian when the Lunar phase reaches First Quarter, after one fourth of a lunar day. At this location the selenographic colongitude at sunrise is defined as 0°. Thus, by the time of the Full Moon the colongitude increases to 90°; at Last Quarter it is 180°, and at the New Moon the colongitude reaches 270°.  Note that the Moon is nearly invisible from the Earth at New Moon phase except during a solar eclipse.

text: Sunrise occurs at the prime meridian when the

text: Lunar phase

text: reaches First Quarter, after one fourth of a

text: lunar day

text: . At this location the selenographic colongitude at sunrise is defined as 0°. Thus, by the time of the

text: Full Moon

text: the colongitude increases to 90°; at Last Quarter it is 180°, and at the

text: New Moon

text: the colongitude reaches 270°.  Note that the Moon is nearly invisible from the Earth at New Moon phase except during a

text: solar eclipse

text: Several missions have used Lissajous orbits: ACE at Sun–Earth , DSCOVR at Sun–Earth , WMAP at Sun–Earth , and also the Genesis mission collecting solar particles at .On 14 May 2009, the European Space Agency (ESA) launched into space the Herschel and Planck observatories, both of which use Lissajous orbits at Sun–Earth .ESA's current  Gaia mission also uses a Lissajous orbit at Sun–Earth .In 2011, NASA transferred two of its THEMIS spacecraft from Earth orbit to Lunar orbit by way of Earth-Moon  and  Lissajous orbits.China's lunar orbiter Chang'e 2 left lunar orbit on June 8, 2011 and was placed in a Lissajous orbit at Earth-Sun  until mid-2012 prior to leaving Earth orbit entirely to fly by the asteroid Toutatis.

text: Several missions have used Lissajous orbits:

text: ACE

text: at Sun–Earth ,

text: DSCOVR

text: at Sun–Earth ,

text: WMAP

text: at Sun–Earth , and also the

text: Genesis

text: mission collecting solar particles at .On 14 May 2009, the

text: European Space Agency

text: (ESA) launched into space the

text: Herschel

text: and

text: Planck

text: observatories, both of which use Lissajous orbits at Sun–Earth .ESA's current

text: Gaia mission

text: also uses a Lissajous orbit at Sun–Earth .In 2011, NASA transferred two of its

text: THEMIS

text: spacecraft from Earth orbit to Lunar orbit by way of Earth-Moon  and  Lissajous orbits.China's lunar orbiter

text: Chang'e 2

text: left lunar orbit on June 8, 2011 and was placed in a Lissajous orbit at Earth-Sun  until mid-2012 prior to leaving Earth orbit entirely to fly by the asteroid Toutatis.

text:
Planetary exploration missions have often turned to Radio-Isotope devices, whether RHUs or RTGs, to support thermal control and power generation in what are often extreme temperature and energy poor environments. However, for Europe, where these technologies are currently unavailable, employing such devices have important technical and programmatic impacts. While activities investigating the development of RHUs and ultimately RTGs are proceeding within Europe, it is not expected that European devices would be available in the 2018 timeframe of the Lunar Lander mission.
Instead, the Lunar Lander is powered by solar arrays which are wrapped around the body tube. Once landed, the vehicles axis of symmetry will be almost perpendicular to the direction of the Sun ensuring continuously good illumination of the solar cells as the lander rotates with respect to the Sun (due to the rotation of the Moon).
Batteries are used to bridge short periods without solar power. Solar power is unavailable in LLO when the lander goes into lunar eclipse and on the ground, when mountain peaks at the horizon cover the Sun. Landing operations will also be conducted relying solely on battery power.

text: Planetary exploration missions have often turned to Radio-Isotope devices, whether RHUs or RTGs, to support thermal control and power generation in what are often extreme temperature and energy poor environments. However, for Europe, where these technologies are currently unavailable, employing such devices have important technical and programmatic impacts. While activities investigating the development of RHUs and ultimately RTGs are proceeding within Europe, it is not expected that European devices would be available in the 2018 timeframe of the Lunar Lander mission.<br>Instead, the Lunar Lander is powered by solar arrays which are wrapped around the body tube. Once landed, the vehicles axis of symmetry will be almost perpendicular to the direction of the

text: Sun

text: ensuring continuously good illumination of the solar cells as the lander rotates with respect to the Sun (due to the rotation of the Moon). <br>Batteries are used to bridge short periods without solar power. Solar power is unavailable in LLO when the lander goes into lunar

text: eclipse

text: and on the ground, when mountain peaks at the horizon cover the Sun. Landing operations will also be conducted relying solely on battery power.

text: In the Southern Hemisphere the sun passes from east to west through the north, although north of the Tropic of Capricorn the mean sun can be directly overhead or due south at midday. The Sun rotating through the north causes an apparent right-left trajectory through the sky unlike the left-right motion of the Sun when seen from the Northern Hemisphere as it passes through the southern sky. Sun-cast shadows turn anticlockwise throughout the day and sundials have the hours increasing in the anticlockwise direction. During solar eclipses viewed from a point to the south of the Tropic of Capricorn, the Moon moves from left to right on the disc of the Sun (see, for example, photos with timings of the solar eclipse of November 13, 2012), while viewed from a point to the north of the Tropic of Cancer (i.e., in the Northern Hemisphere), the Moon moves from right to left during solar eclipses.

text: In the Southern Hemisphere the sun passes from east to west through the north, although north of the

text: Tropic of Capricorn

text: the

text: mean sun

text: can be directly overhead or due south at midday. The Sun rotating through the north causes an apparent right-left trajectory through the sky unlike the left-right motion of the Sun when seen from the Northern Hemisphere as it passes through the southern sky. Sun-cast shadows turn anticlockwise throughout the day and

text: sundial

text: s have the hours increasing in the anticlockwise direction. During

text: solar eclipse

text: s viewed from a point to the south of the Tropic of Capricorn, the Moon moves from left to right on the disc of the Sun (see, for example, photos with timings of the

text: solar eclipse of November 13, 2012

text: ), while viewed from a point to the north of the Tropic of Cancer (i.e., in the Northern Hemisphere), the Moon moves from right to left during solar eclipses.

text: The Moon's regular phases make it a very convenient timepiece, and the periods of its waxing and waning form the basis of many of the oldest calendars. Tally sticks, notched bones dating as far back as 20–30,000 years ago, are believed by some to mark the phases of the Moon.The ~30-day month is an approximation of the lunar cycle.The English noun month and its cognates in other Germanic languages stem from Proto-Germanic *mǣnṓth-, which is connected to the above-mentioned Proto-Germanic *mǣnōn, indicating the usage of a lunar calendar among the Germanic peoples (Germanic calendar) prior to the adoption of a solar calendar. The PIE root of moon, *méhnōt, derives from the PIE verbal root *meh-, "to measure", "indicat[ing] a functional conception of the moon, i.e. marker of the month" (cf. the English words measure and menstrual), and echoing the Moon's importance to many ancient cultures in measuring time (see Latin ''mensis'' and Ancient Greek ''μείς'' (meis) or  (mēn), meaning "month").Most historical calendars are lunisolar. The 7th-century Islamic calendar is an exceptional example of a purely lunar calendar. Months are traditionally determined by the visual sighting of the hilal, or earliest crescent moon, over the horizon.

text: The Moon's regular phases make it a very convenient timepiece, and the periods of its waxing and waning form the basis of many of the oldest calendars.

text: Tally stick

text: s, notched bones dating as far back as 20–30,000 years ago, are believed by some to mark the phases of the Moon.The ~30-day month is an approximation of the

text: lunar cycle

text: .The English noun month and its cognates in other Germanic languages stem from Proto-Germanic *mǣnṓth-, which is connected to the above-mentioned Proto-Germanic *mǣnōn, indicating the usage of a

text: lunar calendar

text: among the

text: Germanic peoples

text: Germanic calendar

text: ) prior to the adoption of a

text: solar calendar

text: . The

text: PIE root

text: of moon, *méhnōt, derives from the PIE verbal root *meh-, "to measure", "indicat[ing] a functional conception of the moon, i.e. marker of the month" (

text: cf.

text: the English words measure and menstrual), and echoing the Moon's importance to many ancient cultures in measuring time (see

text: Latin

text: ''mensis'' and

text: Ancient Greek

text: ''μείς'' (meis) or  (mēn), meaning "month").Most historical calendars are

text: lunisolar

text: . The 7th-century

text: Islamic calendar

text: is an exceptional example of a purely

text: lunar calendar

text: . Months are traditionally determined by the visual sighting of the

text: hilal

text: , or earliest crescent moon, over the horizon.

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: are tag-team bosses first appearing in Kirby's Adventure. Mr. Shine appears as a crescent moon with a face and limbs, while Mr. Bright is a sun with similar features. They are the Sun and the Moon in Dreamland. One always stays in the air, raining down projectiles, while the other attacks from the ground. One of their most lethal attacks is when they create a solar eclipse: Mr. Bright will blast the area with flames while Mr. Shine creates a patch of shadow, which is the only safe spot. They return in Kirby's Dream Land 2, Kirby's Dream Land 3, and Kirby: Nightmare in Dreamland. In Kirby Super Star, they literally fought day and night due to a misunderstanding caused by Marx. In the anime, a monster named Slice and Splice in the English dub and Kittari Hattari in the Japanese version uses moon- and sun-shaped staffs to split and paste his enemies. Presumably, this was an ode to Mr, Shine and Mr, Bright. They also appear in Kirby Mass Attack on Strato Patrol EOS mode.

text: are tag-team bosses first appearing in

text: Kirby's Adventure

text: . Mr. Shine appears as a crescent

text: moon

text: with a face and limbs, while Mr. Bright is a

text: sun

text: with similar features. They are the Sun and the Moon in Dreamland. One always stays in the air, raining down projectiles, while the other attacks from the ground. One of their most lethal attacks is when they create a solar eclipse: Mr. Bright will blast the area with flames while Mr. Shine creates a patch of shadow, which is the only safe spot. They return in

text: Kirby's Dream Land 2

text: Kirby's Dream Land 3

text: , and

text: Kirby: Nightmare in Dreamland

text: . In

text: Kirby Super Star

text: , they literally fought day and night due to a misunderstanding caused by Marx. In the anime, a monster named Slice and Splice in the English dub and Kittari Hattari in the Japanese version uses moon- and sun-shaped staffs to split and paste his enemies. Presumably, this was an ode to Mr, Shine and Mr, Bright. They also appear in Kirby Mass Attack on Strato Patrol EOS mode.

text: This is the average period of the Moon's revolution with respect to the line joining the Sun and Earth. The synodic month is the period of the Moon's phases, because the Moon's appearance depends on the position of the Moon with respect to the Sun as seen from the Earth.

text: This is the average period of the Moon's revolution with respect to the line joining the Sun and Earth. The synodic month is the period of the Moon's

text: phases

text: , because the Moon's appearance depends on the position of the Moon with respect to the Sun as seen from the Earth.

text: During a lunar eclipse, a very small amount of light from the sun does however still reach the Moon, even when the lunar eclipse is total; this is light which has been refracted or bent as it passes through the Earth's atmosphere. This sunlight has been scattered by the dust in the Earth's atmosphere, and thus that light is red, in the same way that sunset and sunrise light is red. This weak red illumination is what causes the eclipsed Moon to be dimly reddish or copper-colored in appearance.

text: During a lunar eclipse, a very small amount of light from the sun does however still reach the Moon, even when the lunar eclipse is total; this is light which has been

text: refracted

text: or bent as it passes through the Earth's atmosphere. This sunlight has been

text: scattered

text: by the dust in the Earth's atmosphere, and thus that light is red, in the same way that sunset and sunrise light is red. This weak red illumination is what causes the eclipsed Moon to be dimly reddish or

text: copper

text: -colored in appearance.

text: The above descriptions of the lunar phases apply for observers at temperate or high latitudes on the Earth. Observers in tropical latitudes see the Moon with its terminator apparently horizontal during the morning and evening. The crescent Moon can open upward or downward, with the "horns" of the crescent pointing up or down, respectively. When the Sun appears above the Moon in the sky, the crescent opens downward; when the Moon is above the Sun, the crescent opens upward. The crescent Moon is most clearly and brightly visible when the Sun is below the horizon, which implies that the Moon must be above the Sun, and the crescent must open upward. This is therefore the orientation in which the crescent Moon is most often seen from the Earth's tropics. The waxing and waning crescents look very similar. The waxing crescent appears in the western sky in the evening, and the waning crescent in the east, in the morning.

text: A fourth influence occurs because the orbit of the moon around the earth and the orbit the of the earth around the sun are elliptical rather than circular. The effect of this is that the time between high tides changes a little from day to day. The moon takes about 24.8 hours to orbit around the earth, so it takes half this time, 12.4 hours, for the M2 tides to occur. The tides can be predicted far in advance, because the moon and earth have orbits that are predictable. The National Institute of Water and Atmospheric Research (NIWA) run a tidal computer model specific to New Zealand.

text: A fourth influence occurs because the orbit of the moon around the earth and the orbit the of the earth around the sun are

text: elliptical

text: rather than circular. The effect of this is that the time between high tides changes a little from day to day. The moon takes about 24.8 hours to orbit around the earth, so it takes half this time, 12.4 hours, for the M2 tides to occur. The tides can be predicted far in advance, because the moon and earth have orbits that are predictable. The

entity_name: National Institute of Water and Atmospheric Research

text: National Institute of Water and Atmospheric Research

text: (NIWA) run a tidal computer model specific to New Zealand.

text: TRSSCOMM (Technical Research Ship Special COMMunications), an early U.S. Navy earth-moon-earth satellite communication system that relayed ("bounced") messages directly from intelligence-gathering ship to Washington DC by bouncing a microwave signal off the moon, used first on the USS Oxford (15 December 1961). This system consisted of a 16-foot, dish-shaped antenna mounted on a movable platform and capable of bouncing a 10,000 watt microwave signal off a particular spot on the moon and down either to the receiving station at the National Security Agency, Fort Meade, Maryland, or to one of the other Navy SIGINT ships. TRSSCOMM had the advantage of being able to transmit large quantities of intelligence information very rapidly without giving away the ship's location to hostile direction-finding equipment or interfering with incoming signals. Its major disadvantage is that it could only work if the moon was visible and the shipboard hydraulic stabilization system worked properly. This system was replaced by creation of a network of artificial military satellites.

text: TRSSCOMM (Technical Research Ship Special COMMunications), an early

text: U.S. Navy

text: earth-moon-earth

text: satellite communication system that relayed ("bounced") messages directly from intelligence-gathering ship to

text: Washington DC

text: by bouncing a

text: microwave

text: signal off the

text: moon

text: , used first on the

text: USS Oxford

text: (15 December 1961). This system consisted of a 16-foot, dish-shaped

text: antenna

text: mounted on a movable platform and capable of bouncing a 10,000

text: watt

text: microwave

text: signal off a particular spot on the moon and down either to the receiving station at the

text: National Security Agency

text: Fort Meade, Maryland

text: , or to one of the other Navy

text: SIGINT

text: ships. TRSSCOMM had the advantage of being able to transmit large quantities of intelligence information very rapidly without giving away the ship's location to hostile

text: direction-finding

text: equipment or interfering with incoming signals. Its major disadvantage is that it could only work if the moon was visible and the

text: shipboard hydraulic stabilization

text: system worked properly. This system was replaced by creation of a network of artificial

text: military satellite

text: s.

text: Many factors can affect the appearance of the Moon during a lunar eclipse.  The Moon's path through the Earth's umbra is important, but so too are the current conditions of the Earth's atmosphere.  While the Earth's shadow blocks any direct light from striking the Moon during a lunar eclipse, some light is refracted through the Earth's atmosphere giving a Moon a red hue.

text: Many factors can affect the appearance of the Moon during a lunar eclipse.  The Moon's path through the Earth's

text: umbra

text: is important, but so too are the current conditions of the

text: Earth's atmosphere

text: .  While the Earth's shadow blocks any direct light from striking the Moon during a lunar eclipse, some light is refracted through the Earth's atmosphere giving a Moon a red hue.

text: Nineteen moons are known to be massive enough to have relaxed into a rounded shape under their own gravity, and seven of them are more massive than either Eris or Pluto. They are not physically distinct from the dwarf planets, but are not dwarf planets because they do not directly orbit the Sun. The seven that are more massive than Eris are the Moon, the four Galilean moons of Jupiter (Io, Europa, Ganymede, and Callisto), one moon of Saturn (Titan), and one moon of Neptune (Triton). The others are six moons of Saturn (Mimas, Enceladus, Tethys, Dione, Rhea, and Iapetus), five moons of Uranus (Miranda, Ariel, Umbriel, Titania, and Oberon), and one moon of Pluto (Charon). There are additional possibilities among TNOs, including Dysnomia orbiting Eris. Alan Stern calls these moons "satellite planets", one of three categories of planet together with dwarf planets and classical planets. The term planemo ("planetary-mass object") covers all three.

text: Nineteen

text: moons

text: are known to be massive enough to have relaxed into a rounded shape under their own gravity, and seven of them are more massive than either Eris or Pluto. They are not physically distinct from the dwarf planets, but are not dwarf planets because they do not directly orbit the Sun. The seven that are more massive than Eris are the

text: Moon

text: , the four

text: Galilean moons

text: of Jupiter (

text: Io

text: Europa

text: Ganymede

text: , and

text: Callisto

text: ), one moon of Saturn (

text: Titan

text: ), and one moon of Neptune (

text: Triton

text: ). The others are six moons of Saturn (

text: Mimas

text: Enceladus

text: Tethys

text: Dione

text: Rhea

text: , and

text: Iapetus

text: ), five moons of Uranus (

text: Miranda

text: Ariel

text: Umbriel

text: Titania

text: , and

text: Oberon

text: ), and one moon of Pluto (

text: Charon

text: ). There are additional possibilities among TNOs, including

text: Dysnomia

text: orbiting Eris. Alan Stern calls these moons "satellite planets", one of three categories of planet together with dwarf planets and classical planets. The term

text: planemo

text: ("planetary-mass object") covers all three.

text: Because the orbit of the Moon is inclined only about 5.145° to the ecliptic and the Sun is always very near the ecliptic, eclipses always occur on or near it. Because of the inclination of the Moon's orbit, eclipses do not occur at every conjunction and opposition of the Sun and Moon, but only when the Moon is near an ascending or descending node at the same time it is at conjunction or opposition. The ecliptic is so named because the ancients noted that eclipses only occurred when the Moon crossed it.

text: Because the

text: orbit of the Moon

text: is inclined only about 5.145° to the ecliptic and the

text: Sun

text: is always very near the ecliptic,

text: eclipse

text: s always occur on or near it. Because of the inclination of the

text: Moon

text: 's

text: orbit

text: , eclipses do not occur at every

text: conjunction

text: and

text: opposition

text: of the Sun and Moon, but only when the Moon is near an

text: ascending or descending node

text: at the same time it is at conjunction or opposition. The ecliptic is so named because the ancients noted that eclipses only occurred when the Moon crossed it.

text: Lunar eclipses are grouped by their saros number, each series lasts between 1200 and 1600 years and contains from 69 to 89 lunar eclipses. Lunar eclipses in even series exist at the ascending node of the moon's orbit, and odd series occur at the descending nodes.

text: Lunar eclipses

text: are grouped by their

text: saros number

text: , each series lasts between 1200 and 1600 years and contains from 69 to 89 lunar eclipses. Lunar eclipses in even series exist at the ascending node of the moon's orbit, and odd series occur at the descending nodes.

text: When the Earth, moon, and sun are in line (sun–Earth–moon, or sun–moon–Earth) the two main influences combine to produce spring tides; when the two forces are opposing each other as when the angle moon–Earth–sun is close to ninety degrees, neap tides result. As the moon moves around its orbit it changes from north of the equator to south of the equator. The alternation in high tide heights becomes smaller, until they are the same (at the lunar equinox, the moon is above the equator), then redevelop but with the other polarity, waxing to a maximum difference and then waning again.

text: Moon: Development work was done on Sonne (sun) to remove the night time errors, this system was called moon. Work was never completed.

text: The Moon, which orbits Earth rather than the Sun, is in opposition to the Sun at full moon. When it is in exact opposition, a lunar eclipse occurs.

text: The

text: Moon

text: , which orbits Earth rather than the Sun, is in opposition to the Sun at

text: full moon

text: . When it is in exact opposition, a

text: lunar eclipse

text: occurs.

text: Sahadeva was very good in Astrology. Duryodhana, on the advice of Shakuni approached Sahadeva in order to seek the right time (muhurta) to start the Mahabharata war so that the Kauravas will be victorious. Sahadeva disclosed the same for the Kauravas in spite of knowing that Kauravas were their enemy, as Sahadeva was known to be very honest. Then, Krishna planned to create an eclipse much before the beginning of the war. In the mean time, both Sun and Moon got shocked by Krishna's thought and appeared before Krishna stating that this will create a huge imbalance in the entire Universe. Then, Krishna declared that as Earth, Moon and Sun are together in one place, this in itself was an eclipse.

text: Due to tidal acceleration, the orbit of the Moon around the Earth becomes about 2.2 cm more distant each year. It is estimated that, in slightly less than 1.4 billion years, the distance from the Earth to the Moon will have increased by 30,400 km. During that period, the apparent angular diameter of the Moon will decrease in size, meaning that it will no longer be able to completely cover the Sun's disk as seen from the Earth. This will be true even when the Moon is at perigee, and the Earth at aphelion. Moreover, the Sun is increasing in diameter by about 5% per billion years. Therefore, the last total solar eclipse on Earth will occur about six hundred million years from now.

text: Due to

text: tidal acceleration

text: , the orbit of the Moon around the Earth becomes about 2.2 cm more distant each year. It is estimated that, in slightly less than 1.4 billion years, the distance from the Earth to the Moon will have increased by 30,400 km. During that period, the apparent angular diameter of the Moon will decrease in size, meaning that it will no longer be able to completely cover the Sun's disk as seen from the Earth. This will be true even when the Moon is at

text: perigee

text: , and the Earth at

text: aphelion

text: . Moreover, the Sun is increasing in diameter by about 5% per billion years. Therefore, the last total solar eclipse on Earth will occur about six hundred million years from now.

text: A partial solar eclipse occurred on June 19, 1917.  A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: occurred on June 19, 1917.  A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: A lunar eclipse is potentially alluded to in Acts of the Apostles 2:14-21 ("The sun shall be turned into darkness, And the moon into blood, Before the day of the Lord come"), as pointed out by physicist Colin Humphreys and astronomer Graeme Waddington. There was in fact a lunar eclipse on 3 April AD 33, a date which coincides with one of Newton's astronomically possible crucifixion dates (see above). Humphreys and Waddington have calculated that in ancient Jerusulem this eclipse would have been visible at moonrise at 6.20pm as a 20% partial eclipse (a full moon with a potentially red "bite" missing at the top left of the moon's disc). They propose that a large proportion of the Jewish population would have witnessed this eclipse as they would have been waiting for sunset in the west and immediately afterwards the rise of the anticipated full moon in the east as the prescribed signal to start their household Passover meals. Humphreys and Waddington therefore suggest a scenario where Jesus was crucified and died at 3pm on 3 April AD 33, followed by a red partial lunar eclipse at moonrise at 6.20pm observed by the Jewish population, and that Peter recalls this event when preaching the resurrection to the Jews (Acts of the Apostles 2:14-21). Astronomer Bradley Schaefer agrees with the eclipse date but disputes that the eclipsed moon would have been visible by the time the moon had risen in Jerusalem.

text: A

text: lunar eclipse

text: is potentially alluded to in

text: Acts of the Apostles 2:14-21

text: ("The sun shall be turned into darkness, And the moon into blood, Before the day of the Lord come"), as pointed out by physicist

text: Colin Humphreys

text: and astronomer Graeme Waddington. There was in fact a lunar eclipse on 3 April AD 33, a date which coincides with one of Newton's astronomically possible crucifixion dates (see above). Humphreys and Waddington have calculated that in ancient Jerusulem this eclipse would have been visible at moonrise at 6.20pm as a 20% partial eclipse (a full moon with a potentially red "bite" missing at the top left of the moon's disc). They propose that a large proportion of the Jewish population would have witnessed this eclipse as they would have been waiting for sunset in the west and immediately afterwards the rise of the anticipated full moon in the east as the prescribed signal to start their household Passover meals. Humphreys and Waddington therefore suggest a scenario where Jesus was crucified and died at 3pm on 3 April AD 33, followed by a red partial lunar eclipse at moonrise at 6.20pm observed by the Jewish population, and that

text: Peter

text: recalls this event when preaching the resurrection to the Jews (

text: Acts of the Apostles 2:14-21

text: ). Astronomer Bradley Schaefer agrees with the eclipse date but disputes that the eclipsed moon would have been visible by the time the moon had risen in Jerusalem.

text: On the Sizes and Distances (of the Sun and Moon) (Περὶ μεγεθῶν καὶ ἀποστημάτων [ἡλίου καὶ σελήνης], Peri megethon kai apostematon) is widely accepted as the only extant work written by Aristarchus of Samos, an ancient Greek astronomer who lived circa 310–230 BC. This work calculates the sizes of the Sun and Moon, as well as their distances from the Earth in terms of Earth's radius.

text: On the Sizes and Distances (of the Sun and Moon) (Περὶ μεγεθῶν καὶ ἀποστημάτων [ἡλίου καὶ σελήνης], Peri megethon kai apostematon) is widely accepted as the only extant work written by

text: Aristarchus of Samos

text: , an ancient Greek astronomer who lived circa 310–230 BC. This work calculates the sizes of the

text: Sun

text: and

text: Moon

text: , as well as their distances from the

text: Earth

text: in terms of Earth's radius.

text: An eclipse does not happen at every new or full moon, because the plane of the orbit of the Moon around the Earth is tilted with respect to the plane of the orbit of the Earth around the Sun (the ecliptic): so as seen from the Earth, when the Moon is nearest to the Sun (new moon) or at largest distance (full moon), the three bodies usually are not exactly on the same line.

text: An eclipse does not happen at every new or full moon, because the plane of the

text: orbit of the Moon

text: around the Earth is tilted with respect to the plane of the orbit of the Earth around the Sun (the

text: ecliptic

text: ): so as seen from the Earth, when the Moon is nearest to the Sun (new moon) or at largest distance (full moon), the three bodies usually are not exactly on the same line.

text: An eclipse is a natural phenomenon. Nevertheless, in some ancient and modern cultures, solar eclipses have been attributed to supernatural causes or regarded as bad omens. A total solar eclipse can be frightening to people who are unaware of its astronomical explanation, as the Sun seems to disappear during the day and the sky darkens in a matter of minutes.

text: An eclipse is a

text: natural phenomenon

text: . Nevertheless, in some ancient and modern cultures, solar eclipses have been attributed to

text: supernatural

text: causes or regarded as bad

text: omen

text: s. A total solar eclipse can be frightening to people who are unaware of its

text: astronomical

text: explanation, as the Sun seems to disappear during the day and the sky darkens in a matter of minutes.

text: At the time of Thales' purported prediction it was not yet known that eclipses were caused by the Moon coming between the Earth and the Sun, a fact that would not be discovered until over a century later by either Anaxagoras or Empedocles.

text: At the time of

text: Thales

text: ' purported prediction it was not yet known that eclipses were caused by the Moon coming between the Earth and the Sun, a fact that would not be discovered until over a century later by either

text: Anaxagoras

text: or

text: Empedocles

text: A partial solar eclipse occurred on December 24, 1927. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: occurred on December 24, 1927. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: Viewed from Earth, the Moon is just far enough away to have almost the same apparent-sized disk as the Sun. The angular size (or solid angle) of these two bodies match because, although the Sun's diameter is about 400 times as large as the Moon's, it is also 400 times more distant. This allows total and annular solar eclipses to occur on Earth.

text: Viewed from Earth, the Moon is just far enough away to have almost the same apparent-sized disk as the Sun. The

text: angular size

text: (or

text: solid angle

text: ) of these two bodies match because, although the Sun's diameter is about 400 times as large as the Moon's, it is also 400 times more distant. This allows total and annular solar eclipses to occur on Earth.

text: The shadow axis passes between the Earth's center and the north pole, the minimum distance from the center of the Earth to the Moon's shadow cone axis is 3,357 kilometers. The average length of the Moon's shadow is 373,320 kilometers. The distance from the Earth to the Moon on 1 May 1185 is 347,727 kilometers. The apparent diameter of the Moon in 1.0736 times more apparent than the sun. The shadow had a maximum width of 280 kilometers. It began on the west coast of Central America and crossed the Atlantic Ocean in a northeasterly direction. The shadow passed through present-day Nicaragua and the island of Haiti. The maximum duration of the eclipse was in the middle of the North Atlantic at coordinates 46 ° N, 37.2 ° W longitude.The solar eclipse is a long total eclipse that lasted for 5 minutes and 10 seconds. The eclipse magnitude is 1.0736. The eclipse was preceded two weeks earlier by a partial lunar eclipse that happened on April 16.

text: The shadow axis passes between the Earth's center and the north pole, the minimum distance from the center of the Earth to the Moon's shadow cone axis is 3,357 kilometers. The average length of the Moon's shadow is 373,320 kilometers. The distance from the Earth to the Moon on 1 May 1185 is 347,727 kilometers. The apparent diameter of the Moon in 1.0736 times more apparent than the sun. The shadow had a maximum width of 280 kilometers. It began on the west coast of Central America and crossed the Atlantic Ocean in a northeasterly direction. The shadow passed through present-day

text: Nicaragua

text: and the island of

text: Haiti

text: . The maximum duration of the eclipse was in the middle of the North Atlantic at coordinates 46 ° N, 37.2 ° W longitude.The solar eclipse is a long total eclipse that lasted for 5 minutes and 10 seconds. The eclipse magnitude is 1.0736. The eclipse was preceded two weeks earlier by a partial lunar eclipse that happened on April 16.

text: The full moon cycle is the period between alignments of the lunar perigee with the sun and the earth, which is about 13.9443 synodic months (about 411.8 days).  Thus approximately every 14th full moon will be a supermoon. However, halfway through the cycle the full moon will be close to apogee, and the new moons immediately before and after can be supermoons.  Thus there may be as many as three supermoons per full moon cycle.

text: The

text: full moon cycle

text: is the period between alignments of the lunar perigee with the sun and the earth, which is about 13.9443 synodic months (about 411.8 days).  Thus approximately every 14th full moon will be a supermoon. However, halfway through the cycle the full moon will be close to apogee, and the new moons immediately before and after can be supermoons.  Thus there may be as many as three supermoons per full moon cycle.

text: An annular solar eclipse will occur on October 14, 2088. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.

text: An annular

text: solar eclipse

text: will occur on October 14, 2088. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: annulus

text: Writing for Earth & Sky Bruce McClure and Deborah Byrd point out that the referenced verse also says the "sun will be turned into darkness", an apparent reference to a solar eclipse. They note that since the Jewish Calendar is lunar, one sixth of all eclipses will occur during Passover or Sukkot.  Furthermore, there have been 62 tetrads since the first century AD, though only eight of them have coincided with both feasts. Thus, the event is not as unusual as Hagee and Biltz imply. Additionally, three of the four eclipses in the tetrad were not even visible in the biblical homeland of Israel, casting further doubt on Hagee and Biltz's interpretation; even then, only the very end of the last eclipse was visible in Israel. Writing for Space.com, Geoff Gaherty said he was saddened that 'prophets of doom' ... view these life-enriching events as portents of disaster" and said the eclipse was "hardly something to be concerned about".

text: Writing for Earth & Sky Bruce McClure and

text: Deborah Byrd

text: point out that the referenced verse also says the "sun will be turned into darkness", an apparent reference to a

text: solar eclipse

text: . They note that since the

text: Jewish Calendar

text: is lunar, one sixth of all eclipses will occur during Passover or Sukkot.  Furthermore, there have been 62

text: tetrads

text: since the first century AD, though only eight of them have coincided with both feasts. Thus, the event is not as unusual as Hagee and Biltz imply. Additionally, three of the four eclipses in the tetrad were not even visible in the biblical homeland of

text: Israel

text: , casting further doubt on Hagee and Biltz's interpretation; even then, only the very end of the last eclipse was visible in Israel. Writing for

text: Space.com

text: , Geoff Gaherty said he was saddened that 'prophets of doom' ... view these life-enriching events as portents of disaster" and said the eclipse was "hardly something to be concerned about".

text: A full moon is the lunar phase that occurs when the Moon is completely illuminated as seen from Earth. This occurs when Earth is located directly between the Sun and the Moon (more exactly, when the ecliptic longitudes of the Sun and Moon differ by 180 degrees). This means that the hemisphere of the Moon that is facing Earth (the near side) is almost fully illuminated by the Sun and appears round (while the far side is almost completely unilluminated). On some occasions at the time of full moon there is also a lunar eclipse so the moon's face appears reddish due to the rayleigh scattering of blue light in Earth's atmosphere.

text: A full moon is the

text: lunar phase

text: that occurs when the

text: Moon

text: is completely illuminated as seen from

text: Earth

text: . This occurs when Earth is located directly between the

text: Sun

text: and the Moon (more exactly, when the

text: ecliptic longitude

text: s of the Sun and Moon differ by 180 degrees). This means that the hemisphere of the Moon that is facing Earth (the

text: near side

text: ) is almost fully illuminated by the Sun and appears round (while the

text: far side

text: is almost completely unilluminated). On some occasions at the time of full moon there is also a

text: lunar eclipse

text: so the moon's face appears reddish due to the

text: rayleigh scattering

text: of blue light in Earth's

text: atmosphere

text: In Western culture, the four principal lunar phases are new moon, first quarter, full moon, and third quarter (also known as last quarter). These are the instants when the Moon's apparent geocentric celestial longitude minus the Sun's apparent geocentric celestial longitude is 0°, 90°, 180° and 270°, respectively. Each of these phases is instantaneous, lasting theoretically zero time, although they occur at slightly different times when viewed from different points on the Earth. During the intervals between principal phases, the Moon appears either crescent-shaped or gibbous. These shapes, and the periods of time when the Moon shows them, are called the intermediate phases. They last, on average, one-quarter of a synodic month, roughly 7.38 days, but their durations vary slightly because the Moon's orbit is slightly elliptical, and thus its speed in orbit is not constant. The descriptor waxing is used for an intermediate phase when the Moon's apparent size is increasing, from new moon toward full moon, and waning when the size is decreasing.

text: In

text: Western culture

text: , the four principal lunar phases are new moon, first quarter, full moon, and third quarter (also known as last quarter). These are the instants when the Moon's apparent geocentric

text: celestial longitude

text: minus the Sun's apparent geocentric celestial longitude is 0°, 90°, 180° and 270°, respectively. Each of these phases is instantaneous, lasting theoretically zero time, although they occur at slightly different times when viewed from different points on the Earth. During the intervals between principal phases, the Moon appears either

text: crescent

text: -shaped or

text: gibbous

text: . These shapes, and the periods of time when the Moon shows them, are called the intermediate phases. They last, on average, one-quarter of a

text: synodic month

text: , roughly 7.38 days, but their durations vary slightly because the Moon's orbit is slightly

text: elliptical

text: , and thus its speed in orbit is not constant. The descriptor waxing is used for an intermediate phase when the Moon's apparent size is increasing, from new moon toward full moon, and waning when the size is decreasing.

text: A primitive way to determine the distance to the Sun in terms of the distance to the Moon was already proposed by Aristarchus of Samos in his book On the Sizes and Distances of the Sun and Moon. He noted that the Sun, Moon, and Earth form a right triangle (right angle at the Moon) at the moment of first or last quarter moon. He then estimated that the Moon, Earth, Sun angle was 87°. Using correct geometry but inaccurate observational data, Aristarchus concluded that the Sun was slightly less than 20 times farther away than the Moon. The true value of this angle is close to 89° 50', and the Sun is actually about 390 times farther away. He pointed out that the Moon and Sun have nearly equal apparent angular sizes and therefore their diameters must be in proportion to their distances from Earth. He thus concluded that the Sun was around 20 times larger than the Moon; this conclusion, although incorrect, follows logically from his incorrect data. It does suggest that the Sun is clearly larger than the Earth, which could be taken to support the heliocentric model.

text: A primitive way to determine the distance to the Sun in terms of the distance to the Moon was already proposed by

text: Aristarchus of Samos

text: in his book

entity_name: On the Sizes and Distances (Aristarchus)

text: On the Sizes and Distances of the Sun and Moon

text: . He noted that the Sun, Moon, and Earth form a right triangle (right angle at the Moon) at the moment of

text: first or last quarter moon

text: . He then estimated that the Moon, Earth, Sun angle was 87°. Using correct

text: geometry

text: but inaccurate observational data, Aristarchus concluded that the Sun was slightly less than 20 times farther away than the Moon. The true value of this angle is close to 89° 50', and the Sun is actually about 390 times farther away. He pointed out that the Moon and Sun have nearly equal

text: apparent angular sizes

text: and therefore their diameters must be in proportion to their distances from Earth. He thus concluded that the Sun was around 20 times larger than the Moon; this conclusion, although incorrect, follows logically from his incorrect data. It does suggest that the Sun is clearly larger than the Earth, which could be taken to support the heliocentric model.

text: The only close-up images of Ariel were obtained by the Voyager 2 probe, which photographed the moon during its flyby of Uranus in January 1986. The closest approach of Voyager 2 to Ariel was —significantly less than the distances to all other Uranian moons except Miranda. The best images of Ariel have a spatial resolution of about 2 km. They cover about 40% of the surface, but only 35% was photographed with the quality required for geological mapping and crater counting. At the time of the flyby the southern hemisphere of Ariel (like those of the other moons) was pointed towards the Sun, so the northern (dark) hemisphere could not be studied. No other spacecraft has ever visited the Uranian system, and no mission to Uranus and its moons is planned. The possibility of sending the Cassini spacecraft to Uranus was evaluated during its mission extension planning phase. It would take about twenty years to get to the Uranian system after departing Saturn.

text: The only close-up images of Ariel were obtained by the

text: Voyager 2

text: probe, which photographed the moon during its flyby of Uranus in January 1986. The closest approach of Voyager 2 to Ariel was —significantly less than the distances to all other Uranian moons except Miranda. The best images of Ariel have a spatial resolution of about 2 km. They cover about 40% of the surface, but only 35% was photographed with the quality required for

text: geological mapping

text: and crater counting. At the time of the flyby the southern hemisphere of Ariel (like those of the other moons) was pointed towards the Sun, so the northern (dark) hemisphere could not be studied. No other spacecraft has ever visited the Uranian system, and no mission to Uranus and its moons is planned. The possibility of sending the

text: Cassini spacecraft

text: to Uranus was evaluated during its mission extension planning phase. It would take about twenty years to get to the Uranian system after departing Saturn.

text: An annual solar eclipse occurred on November 12, 1947. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.

text: An annual

text: solar eclipse

text: occurred on November 12, 1947. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: annulus

text: The physical problem was addressed by Amerigo Vespucci and subsequently by Galileo Galilei; in 1499 Vespucci used knowledge of the position of the moon to determine his position in Brazil. It became of technical importance in the 1720s, as an accurate solution would be applicable to navigation, specifically for the determination of longitude at sea, solved in practice by John Harrison's invention of the Marine chronometer. However the accuracy of the lunar theory was low, due to the perturbing effect of the Sun and planets on the motion of the Moon around the Earth.

text: The physical problem was addressed by

text: Amerigo Vespucci

text: and subsequently by

text: Galileo Galilei

text: ; in 1499 Vespucci used knowledge of the position of the moon to determine his position in Brazil. It became of technical importance in the 1720s, as an accurate solution would be applicable to navigation, specifically for the

text: determination of longitude at sea

text: , solved in practice by

text: John Harrison

text: 's invention of the

text: Marine chronometer

text: . However the accuracy of the

text: lunar theory

text: was low, due to the perturbing effect of the Sun and planets on the motion of the Moon around the Earth.

text: A supermoon is the coincidence of a full moon or a new moon with the closest approach the Moon makes to the Earth on its elliptical orbit, resulting in the largest apparent size of the lunar disk as seen from Earth. The technical name is the perigee-syzygy of the Earth–Moon–Sun system. The term supermoon is not astronomical, but originated in modern astrology. The association of the Moon with both oceanic and crustal tides has led to claims that the supermoon phenomenon may be associated with increased risk of events such as earthquakes and volcanic eruptions, but there is no evidence of such a link.

text: A supermoon is the coincidence of a

text: full moon

text: or a

text: new moon

text: with the closest approach the

text: Moon

text: makes to the Earth on its elliptical orbit, resulting in the largest apparent size of the lunar disk as seen from Earth. The technical name is the perigee-syzygy of the Earth–Moon–Sun system. The term supermoon is not

text: astronomical

text: , but originated in modern

text: astrology

text: . The association of the Moon with both oceanic and

text: crustal tide

text: s has led to claims that the supermoon phenomenon may be associated with increased risk of events such as earthquakes and volcanic eruptions, but there is no evidence of such a link.

text: This is a list of solar eclipses in the 11th century BC. During the period 1100 to 1001 BC there were 238 solar eclipses of which 79 were partial, 91 were annular (two non-central), 68 were total (one non-central), and none were hybrids. The greatest number of eclipses in one year was five, in 1090 BC, and three months, August 1036 BC, July 1025 BC, and June 1014 BC, had two eclipses.

text: This is a list of

text: solar eclipses

text: in the

text: 11th century BC

text: . During the period 1100 to 1001 BC there were 238 solar eclipses of which 79 were

text: partial

text: , 91 were

text: annular

text: (two

text: non-central

text: ), 68 were

text: total

text: (one non-central), and none were

text: hybrids

text: . The greatest number of eclipses in one year was five, in 1090 BC, and three months, August 1036 BC, July 1025 BC, and June 1014 BC, had two eclipses.

text: Because its orbit takes it between the Earth and the Sun, Venus as seen from Earth exhibits visible phases in much the same manner as the Earth's Moon. Galileo Galilei was the first person to observe the phases of Venus in December 1610, an observation which supported Copernicus's then contentious heliocentric description of the Solar System. He also noted changes in the size of Venus's visible diameter when it was in different phases, suggesting that it was farther from Earth when it was full and nearer when it was a crescent. This observation strongly supported the heliocentric model. Venus (and also Mercury) is not visible from Earth when it is full, since at that time it is at superior conjunction, rising and setting concomitantly with the Sun and hence lost in the Sun's glare.

text: Because its

text: orbit

text: takes it between the Earth and the Sun, Venus as seen from Earth exhibits visible

text: phases

text: in much the same manner as the Earth's Moon.

text: Galileo Galilei

text: was the first person to observe the phases of Venus in December 1610, an observation which supported

text: Copernicus

text: 's then contentious

text: heliocentric

text: description of the Solar System. He also noted changes in the size of Venus's visible diameter when it was in different phases, suggesting that it was farther from Earth when it was full and nearer when it was a crescent. This observation strongly supported the heliocentric model. Venus (and also Mercury) is not visible from Earth when it is full, since at that time it is at

text: superior conjunction

text: , rising and setting concomitantly with the Sun and hence lost in the Sun's glare.

text: The gravitational force between the Sun and moon induces the precession in Earth's orbit, which is the major cause of the climate oscillation of Earth that has a period of 19,000 to 23,000 years. It follows that changes in Earth's orbital parameters (e.g., orbital inclination, the angle between Earth's rotation axis and its plane of orbit) is important to the study of Earth's climate, in particular to the study of past ice ages. (See also nodal precession. For precession of the lunar orbit see lunar precession).

text: The gravitational force between the Sun and moon induces the precession in Earth's orbit, which is the major cause of the climate oscillation of Earth that has a period of 19,000 to 23,000 years. It follows that changes in Earth's orbital parameters (e.g., orbital inclination, the angle between Earth's rotation axis and its plane of orbit) is important to the study of Earth's climate, in particular to the study of past ice ages. (See also

text: nodal precession

text: . For precession of the lunar orbit see

text: lunar precession

text: An annular solar eclipse occurred on December 4, 1983. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.

text: An annular

text: solar eclipse

text: occurred on December 4, 1983. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: annulus

text: Tidal forces arise when the gravitational field is not uniform and gravitation gradients exist. Such indeed is the norm and strictly speaking any object of finite size even in free-fall is subject to tidal effects. These are impossible to remove by inertial motion, except at one single nominated point of the body.The Earth is in free fall but the presence of tides indicates that it is in a non-uniform gravitational field. This non-uniformity is more due to the moon than the sun. The total gravitational field due to the sun is much stronger than that of the moon but it has a minor tidal effect compared with that of the moon because of the relative distances involved. Weight of the earth is essentially due to the sun's gravity. But its state of stress and deformation, represented by the tides, is more due to non uniformity in the gravitational field of the nearby moon.When the size of a region being considered is small relative to its distance from the gravitating mass the assumption of uniform gravitational field holds to a good approximation. Thus a person is small relative to the radius of Earth and the field for a person at the surface of the earth is approximately uniform. The field is strictly not uniform and is responsible for the phenomenon of microgravity. Objects near a black hole are subject to a highly non-uniform gravitational field.

text: Tidal forces

text: microgravity

text: . Objects near a

text: black hole

text: are subject to a highly non-uniform gravitational field.

text: The Earth's shadow or umbra is as curved as the planet Earth is, and it extends 1.4 million kilometers into space (the antumbra, however, extends indefinitely). When the Sun, the Earth and the Moon are aligned perfectly (or almost perfectly), with the Earth in between the Sun and the Moon, the Earth's shadow falls onto the surface of the Moon which is facing the night side of the Earth, such that observers see the shadow gradually turn the bright full Moon dark, and then light again, creating a lunar eclipse.

text: The Earth's shadow or

text: umbra

text: is as curved as the planet Earth is, and it extends 1.4 million kilometers into space (the

text: antumbra

text: , however, extends indefinitely). When the

text: Sun

text: , the Earth and the

text: Moon

text: are aligned perfectly (or almost perfectly), with the Earth in between the Sun and the Moon, the Earth's shadow falls onto the surface of the Moon which is facing the night side of the Earth, such that observers see the shadow gradually turn the bright full Moon dark, and then light again, creating a

text: lunar eclipse

text: A partial solar eclipse occurred on July 21, 1906. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: occurred on July 21, 1906. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: During a total solar eclipse, the Moon's shadow covers only a small fraction of the Earth. The Earth continues to receive at least 92 percent of the amount of sunlight it receives without an eclipse – more if the penumbra of the Moon's shadow partly misses the Earth. Seen from the Moon, the Earth during a total solar eclipse is mostly brilliantly illuminated, with only a small dark patch showing the Moon's shadow. The brilliantly-lit Earth reflects a lot of light to the Moon. If the corona of the eclipsed Sun were not present, the Moon, illuminated by earthlight, would be easily visible from Earth. This would be essentially the same as the earthshine which can frequently be seen when the Moon's phase is a narrow crescent. In reality, the corona, though much less brilliant than the Sun's photosphere, is much brighter than the Moon illuminated by earthlight. Therefore, by contrast, the Moon during a total solar eclipse appears to be black, with the corona surrounding it.

text: During a total solar eclipse, the Moon's shadow covers only a small fraction of the Earth. The Earth continues to receive at least 92 percent of the amount of sunlight it receives without an eclipse – more if the

text: penumbra

text: of the Moon's shadow partly misses the Earth. Seen from the Moon, the Earth during a total solar eclipse is mostly brilliantly illuminated, with only a small dark patch showing the Moon's shadow. The brilliantly-lit Earth reflects a lot of light to the Moon. If the

text: corona

text: of the eclipsed Sun were not present, the Moon, illuminated by earthlight, would be easily visible from Earth. This would be essentially the same as the

text: earthshine

text: which can frequently be seen when the Moon's

text: phase

text: is a narrow crescent. In reality, the corona, though much less brilliant than the Sun's

text: photosphere

text: , is much brighter than the Moon illuminated by earthlight. Therefore, by contrast, the Moon during a total solar eclipse appears to be black, with the corona surrounding it.

text: Although she only lived to be twenty-nine, Wang Zhenyi was very accomplished in the academic world. She excelled in astronomy and mathematics. One of her contributions was being able to describe her views of celestial phenomena in her article, "Dispute of the Procession of the Equinoxes." She was able to explain and simply prove how equinoxes move and then how to calculate their movement. She wrote many other articles such as "Dispute of Longitude and Stars" as well as "The Explanation of a Lunar Eclipse." She commented on the number of stars; the revolving direction of the sun, the moon, and the planets Venus, Jupiter, Mars, Mercury, and Saturn; as well as describing the relationship between lunar and solar eclipses. Not only did she study the research of other astronomers, but she was also able to do her own original research.

text: This eclipse occurred at the descending node of the moon's orbit. Lunar eclipses are always paired with a solar eclipse either 2 weeks before or after at new moon in the opposite node. In this case, it was followed by a partial solar eclipse at the ascending node on January 4, 2011, visible from Europe, northern Africa, and western Asia.

text: This eclipse occurred at the descending node of the moon's orbit. Lunar eclipses are always paired with a solar eclipse either 2 weeks before or after at

text: new moon

text: in the opposite node. In this case, it was followed by a partial

text: solar eclipse

text: at the ascending node on

text: January 4, 2011

text: , visible from Europe, northern Africa, and western Asia.

text: The display on the clock is based upon the geocentric model, which was not superseded until the advent of heliocentrism in the late 16th century.  The earth is represented by a green sphere positioned in the centre of the clock face.  The sun points to the hour of day. The gold/black orb represents the moon, and shows the lunar phases.  At full moon, it is golden and at new moon it is black.  For intermediate phases it is partially black and gold in proportion to the phase.

text: The display on the clock is based upon the

text: geocentric model

text: , which was not superseded until the advent of

text: heliocentrism

text: in the late 16th century.  The earth is represented by a green sphere positioned in the centre of the clock face.  The sun points to the hour of day. The gold/black orb represents the moon, and shows the lunar phases.  At full moon, it is golden and at new moon it is black.  For intermediate phases it is partially black and gold in proportion to the phase.

text: The major activities of predicting the phases of moon take place in the Pakistan Naval Observatory, Department of Mathematics of the Karachi University and the Institute of Space and Planetary Astrophysics (ISPA), where the institutes provide scientific background of the motion of lunar phases and appearances to the ministry of religious affairs.

text: The major activities of predicting the phases of moon take place in the

text: Pakistan Naval Observatory

text: , Department of Mathematics of the

text: Karachi University

text: and the

entity_name: Institute of Space and Planetary Astrophysics

text: Institute of Space and Planetary Astrophysics

text: (ISPA), where the institutes provide scientific background of the motion of lunar phases and appearances to the ministry of religious affairs.

text: Schyrleus was a determined anticopernican.  In the foreword of its book, which includes a dedication to Jesus Christ and Ferdinand III, Schyrleus boldly declared that after having meditated for a long time on the systems of Ptolemy, Copernicus, Tycho Brahe, and other astronomers, he was convinced that all of these scientists had advanced superfluous theories.  He dedicated the moons of Jupiter to Pope Urban VIII, calling them Astres Urbanoctavianes.  He also wrote that Saturn had two "companions," and that they were periodically eclipsed by the planet. He deduced that they had their own independent orbits, and that they illuminated Saturn, which needed light as it was a hundred times less lit by the sun than the Earth.  He tells us that in 1642, in Cologne, he saw pass in front of the Sun a troop (turnam) of shooting stars that followed one another during a period fourteen days, and that the glare of the Sun was considerably weakened by it.

text: Schyrleus was a determined

text: anticopernican

text: .  In the foreword of its book, which includes a dedication to

text: Jesus Christ

text: and

text: Ferdinand III

text: , Schyrleus boldly declared that after having meditated for a long time on the systems of

text: Ptolemy

text: Copernicus

text: Tycho Brahe

text: , and other astronomers, he was convinced that all of these scientists had advanced superfluous theories.  He dedicated the

text: moons of Jupiter

text: to Pope

text: Urban VIII

text: , calling them Astres Urbanoctavianes.  He also wrote that

text: Saturn

text: had two "companions," and that they were periodically eclipsed by the planet. He deduced that they had their own independent

text: orbit

text: s, and that they illuminated Saturn, which needed light as it was a hundred times less lit by the sun than the

text: Earth

text: .  He tells us that in 1642, in

text: Cologne

text: , he saw pass in front of the Sun a troop (turnam) of shooting stars that followed one another during a period fourteen days, and that the glare of the Sun was considerably weakened by it.

text: Lunar eclipses are related by many different eclipse cycles. The Saros cycle (18 years and 10 days) repeats the most consistently due three coinciding periods, and continue over 70 events (1200+ years). Eclipses are identified by a Saros number and a member index within each series.

text: Lunar eclipses are related by many different

text: eclipse cycle

text: s. The

text: Saros cycle

text: (18 years and 10 days) repeats the most consistently due three coinciding periods, and continue over 70 events (1200+ years). Eclipses are identified by a Saros number and a member index within each series.

text: Graha (from Sanskrit ग्रह gráha—seizing, laying hold of, holding) is a 'cosmic influencer' on the living beings of mother Bhumidevi (Earth). In Hindu astrology, the Navagraha (Sanskrit: नवग्रह, nine seizers or nine influencers) are some of these major influencers.  All the navagraha have relative movement with respect to the background of fixed stars in the zodiac. This includes the planets:  Mars, Mercury, Jupiter, Venus, and Saturn, the Sun, the Moon, as well as positions in the sky, Rahu (north or ascending lunar node) and Ketu (south or descending lunar node).

text: Graha (from Sanskrit ग्रह gráha—seizing, laying hold of, holding) is a 'cosmic influencer' on the living beings of mother

text: Bhumidevi

text: (Earth). In

text: Hindu astrology

text: , the

text: Navagraha

text: (Sanskrit: नवग्रह, nine seizers or nine influencers) are some of these major influencers.  All the navagraha have relative movement with respect to the background of fixed stars in the

text: zodiac

text: . This includes the planets:

text: Mars

text: Mercury

text: Jupiter

text: Venus

text: , and

text: Saturn

text: , the

text: Sun

text: , the

text: Moon

text: , as well as positions in the sky,

text: Rahu

text: (north or ascending

text: lunar node

text: ) and

text: Ketu

text: (south or descending lunar node).

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: While the Moon is orbiting the Earth, the Earth is progressing in its orbit around the Sun. After completing a sidereal month the Moon must move a little further to reach the new position having the same angular distance from the Sun. This longer period is called the synodic month (, sunodikos, meaning "pertaining to a synod, i.e., a meeting" [in this case of the Sun and the Moon]).

text: Solar and lunar eclipses were scientifically explained by Aryabhata. He states that the Moon and planets shine by reflected sunlight. Instead of the prevailing cosmogony in which eclipses were caused by Rahu and Ketu (identified as the pseudo-planetary lunar nodes), he explains eclipses in terms of shadows cast by and falling on Earth. Thus, the lunar eclipse occurs when the moon enters into the Earth's shadow (verse gola.37). He discusses at length the size and extent of the Earth's shadow (verses gola.38–48) and then provides the computation and the size of the eclipsed part during an eclipse. Later Indian astronomers improved on the calculations, but Aryabhata's methods provided the core. His computational paradigm was so accurate that 18th-century scientist Guillaume Le Gentil, during a visit to Pondicherry, India, found the Indian computations of the duration of the lunar eclipse of 30 August 1765 to be short by 41 seconds, whereas his charts (by Tobias Mayer, 1752) were long by 68 seconds.

text: Solar and lunar eclipses were scientifically explained by Aryabhata. He states that the

text: Moon

text: and planets shine by reflected sunlight. Instead of the prevailing cosmogony in which eclipses were caused by

text: Rahu

text: and

text: Ketu

text: (identified as the pseudo-planetary

text: lunar nodes

text: ), he explains eclipses in terms of shadows cast by and falling on Earth. Thus, the lunar eclipse occurs when the moon enters into the Earth's shadow (verse gola.37). He discusses at length the size and extent of the Earth's shadow (verses gola.38–48) and then provides the computation and the size of the eclipsed part during an eclipse. Later Indian astronomers improved on the calculations, but Aryabhata's methods provided the core. His computational paradigm was so accurate that 18th-century scientist

text: Guillaume Le Gentil

text: , during a visit to Pondicherry, India, found the Indian computations of the duration of the

text: lunar eclipse

text: of 30 August 1765 to be short by 41 seconds, whereas his charts (by Tobias Mayer, 1752) were long by 68 seconds.

text: Newton, by calculating from Kepler's laws, and supposing the orbits of the planets to be circles round the sun in the centre, had already proved that the force of the sun acting upon the different planets must vary as the inverse square of the distances of the planets from the sun. He therefore was led to inquire whether, if the Earth's attraction extended to the moon, the force at that distance would be of the exact magnitude necessary to retain the moon in its orbit. He found that the moon by her motion in her orbit was deflected from the tangent in every minute of time through a space of thirteen feet. But by observing the distance through which a body would fall in one second of time at the Earth's surface, and by calculating from that on the supposition of the force diminishing in the ratio of the inverse square of the distance, he found that the Earth's attraction at the distance of the moon would draw a body through 15 ft. (4.57 metres) in one minute. Newton regarded the discrepancy between the results as a proof of the inaccuracy of his conjecture, and "laid aside at that time any further thoughts of this matter."  (See Newton's cannonball.)

text: Newton, by calculating from

text: Kepler's laws

text: Newton's cannonball

text: The far side of the Moon is often improperly called the dark side of the Moon. The first scene of the show had a caption stating the location of the nuclear waste disposal storage being on the dark side of the Moon, although the caption also stated it was September 9, 1999, so the caption meant it was the dark side of the Moon on September  9.  It was also referred to as "the far side" by the character Ouma during the episode. The far side of the Moon, while always away from Earth, will still be illuminated by the sun, thus there is no area of the Moon that is permanently dark. This error was noted by Isaac Asimov, who wrote two articles on the scientific inaccuracies of the show. Unfortunately there was a new moon on September 9, 1999 so the far side was illuminated and the near side was the "dark side" on that date. (This can be seen on a moon-phase calculator, e.g. StarDate.)

text: The

text: far side of the Moon

text: is often improperly called the dark side of the Moon. The first scene of the show had a caption stating the location of the nuclear waste disposal storage being on the dark side of the Moon, although the caption also stated it was September 9, 1999, so the caption meant it was the dark side of the Moon on September  9.  It was also referred to as "the far side" by the character Ouma during the episode. The far side of the Moon, while always away from

text: Earth

text: , will still be illuminated by the

text: sun

text: , thus there is no area of the Moon that is permanently dark. This error was noted by

text: Isaac Asimov

text: , who wrote two articles on the scientific inaccuracies of the show. Unfortunately there was a new moon on September 9, 1999 so the far side was illuminated and the near side was the "dark side" on that date. (This can be seen on a moon-phase calculator, e.g. StarDate.)

text: Sedna has the longest orbital period of any known object in the Solar System of comparable size or larger, calculated at around 11,400 years. Its orbit is extremely eccentric, with an aphelion estimated at 937 AU and a perihelion at about 76 AU. This perihelion was the largest of that of any known Solar System object until the discovery of . When Sedna was discovered it was 89.6 AU from the Sun approaching perihelion, and was the most distant object in the Solar System observed. Eris was later detected by the same survey near aphelion at 97 AU. Only the orbits of some long-period comets extend farther than that of Sedna; they are too dim to be discovered except when approaching perihelion in the inner Solar System. Even as Sedna nears its perihelion in mid 2076, the Sun would appear merely as an extremely bright star-like pinpoint in its sky, 100 times brighter than a full moon on Earth (for comparison, the Sun appears from Earth to be roughly 400,000 times brighter than the full Moon), and too far away to be visible as a disc to the naked eye.

text: Sedna has the longest

text: orbital period

text: of any known object in the Solar System of comparable size or larger, calculated at around 11,400 years. Its

text: orbit

text: is extremely

text: eccentric

text: , with an

text: aphelion

text: estimated at 937 AU and a

text: perihelion

text: at about 76 AU. This perihelion was the largest of that of any known Solar System object until the discovery of . When Sedna was discovered it was 89.6 AU from the Sun approaching perihelion, and was the most distant object in the Solar System observed.

text: Eris

text: was later detected by the same survey near aphelion at 97 AU. Only the orbits of some long-period comets extend farther than that of Sedna; they are too dim to be discovered except when approaching perihelion in the inner Solar System. Even as Sedna nears its perihelion in mid 2076, the Sun would appear merely as an extremely bright star-like pinpoint in its sky, 100 times brighter than a full moon on Earth (for comparison, the Sun appears from Earth to be roughly 400,000 times brighter than the full Moon), and too far away to be visible as a disc to the naked eye.

text: There are several different periods associated with the lunar orbit. The sidereal month is the time it takes to make one complete orbit around Earth with respect to the fixed stars. It is about 27.32 days. The synodic month is the time it takes the Moon to reach the same visual phase. This varies notably throughout the year, but averages around 29.53 days. The synodic period is longer than the sidereal period because the Earth–Moon system moves in its orbit around the Sun during each sidereal month, hence a longer period is required to achieve a similar alignment of Earth, the Sun, and the Moon. The anomalistic month is the time between perigees and is about 27.55 days. The Earth–Moon separation determines the strength of the lunar tide raising force.

text: There are several different periods associated with the lunar orbit. The

text: sidereal month

text: is the time it takes to make one complete orbit around Earth with respect to the fixed stars. It is about 27.32 days. The

text: synodic month

text: is the time it takes the Moon to reach the same visual

text: phase

text: . This varies notably throughout the year, but averages around 29.53 days. The synodic period is longer than the sidereal period because the Earth–Moon system moves in its orbit around the

text: Sun

text: during each sidereal month, hence a longer period is required to achieve a similar alignment of Earth, the Sun, and the Moon. The

text: anomalistic month

text: is the time between perigees and is about 27.55 days. The Earth–Moon separation determines the strength of the lunar tide raising force.

text: Eclipses occur only near the lunar nodes:Solar eclipses occur when the passage of the Moon through a node coincides with the new moon; lunar eclipses occur when passage coincides with the full moon. A lunar eclipse may occur if there is a full moon within 11° 38' (Celestial Longitude), of a node, and a solar eclipse may occur if there is a new moon within 17° 25' of a node.

text: Eclipse

text: s occur only near the lunar nodes:

text: Solar eclipse

text: s occur when the passage of the Moon through a node coincides with the

text: new moon

text: lunar eclipse

text: s occur when passage coincides with the

text: full moon

text: . A lunar eclipse may occur if there is a full moon within 11° 38' (Celestial Longitude), of a node, and a solar eclipse may occur if there is a new moon within 17° 25' of a node.

text: A partial solar eclipse occurred on October 2, 1978. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: occurred on October 2, 1978. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: Solar sailing, an experimental method of spacecraft propulsion, uses radiation pressure from the Sun as a motive force. The idea of interplanetary travel by light was mentioned by Jules Verne in From the Earth to the Moon.

text: Solar sailing, an experimental method of

text: spacecraft propulsion

text: , uses radiation pressure from the Sun as a motive force. The idea of interplanetary travel by light was mentioned by

text: Jules Verne

text: in From the Earth to the Moon.

text: The lunar phase or phase of the moon is the shape of the illuminated (sunlit) portion of the Moon as seen by an observer on Earth.  The lunar phases change cyclically as the Moon orbits the Earth, according to the changing positions of the  Moon and Sun relative to the Earth. The Moon's rotation is tidally locked by the Earth's gravity, therefore the same lunar surface always faces Earth. This face is variously sunlit depending on the position of the Moon in its orbit. Therefore, the portion of this hemisphere that is visible to an observer on Earth can vary from about 100% (full moon) to 0% (new moon). The lunar terminator is the boundary between the illuminated and darkened hemispheres. Each of the four "intermediate" lunar phases (see below) is roughly seven days (~7.4 days) but this varies slightly due to the elliptical shape of the Moon's orbit. Aside from some craters near the lunar poles such as Shoemaker, all parts of the Moon see around 14.77 days of sunlight, followed by 14.77 days of "night". (The side of the Moon facing away from the Earth is sometimes called the "dark side", which is a misnomer.

text: The lunar phase or phase of the moon is the shape of the illuminated (sunlit) portion of the

text: Moon

text: as seen by an observer on

text: Earth

text: .  The lunar phases change cyclically as the Moon

text: orbit

text: s the Earth, according to the changing positions of the

text: Moon

text: and

text: Sun

text: relative to the

text: Earth

text: . The Moon's rotation is

text: tidally locked

text: by the Earth's gravity, therefore the same lunar surface always faces Earth. This face is variously sunlit depending on the position of the Moon in its orbit. Therefore, the portion of this hemisphere that is visible to an observer on Earth can vary from about 100% (

text: full moon

text: ) to 0% (

text: new moon

text: ). The

text: lunar terminator

text: is the boundary between the illuminated and darkened hemispheres. Each of the four "intermediate" lunar phases (see below) is roughly seven days (~7.4 days) but this varies slightly due to the elliptical shape of the Moon's orbit. Aside from some craters near the lunar poles such as

text: Shoemaker

text: , all parts of the Moon see around 14.77 days of sunlight, followed by 14.77 days of "night". (The side of the Moon facing away from the Earth is sometimes called the "dark side", which is a misnomer.

text: Lunar Eclipse is the second solo album by David Bryan from the band Bon Jovi. Released in 2000, it features all the songs from his first album "On a Full Moon", released in 1995, except for "Awakening" and "Midnight Voodoo". Instead of those two tracks it features two brand new tracks, "Second Chance" and "I Can Love". Also, this version of the Bon Jovi song In These Arms has David on vocals, in contrast to the instrumental version from the first album.

text: Lunar Eclipse is the second solo album by

text: David Bryan

text: from the band

text: Bon Jovi

text: . Released in 2000, it features all the songs from his first album "

text: On a Full Moon

text: ", released in 1995, except for "Awakening" and "Midnight Voodoo". Instead of those two tracks it features two brand new tracks, "Second Chance" and "I Can Love". Also, this version of the

text: Bon Jovi

text: song

text: In These Arms

text: has David on vocals, in contrast to the instrumental version from the first album.

text: A total lunar eclipse will take place on July 27, 2018. The moon will pass through the center of the Earth's shadow. This will be the first central lunar eclipse since the June 15, 2011 lunar eclipse.

text: A total

text: lunar eclipse

text: will take place on July 27, 2018. The moon will pass through the

text: center of the Earth's shadow

text: . This will be the first central lunar eclipse since the

text: June 15, 2011 lunar eclipse

text: As it moves around its orbit, Venus displays phases like those of the Moon in a telescopic view. The planet presents a small "full" image when it is on the opposite side of the Sun. It shows a larger "quarter phase" when it is at its maximum elongations from the Sun, and is at its brightest in the night sky, and presents a much larger "thin crescent" in telescopic views as it comes around to the near side between Earth and the Sun. Venus is at its largest and presents its "new phase" when it is between Earth and the Sun. Its atmosphere can be seen in a telescope by the halo of light refracted around it.

text: As it moves around its orbit,

text: Venus displays phases

text: like those of the

text: Moon

text: in a

text: telescopic

text: view. The planet presents a small "full" image when it is on the opposite side of the Sun. It shows a larger "quarter phase" when it is at its maximum elongations from the Sun, and is at its brightest in the night sky, and presents a much larger "thin crescent" in telescopic views as it comes around to the near side between Earth and the Sun. Venus is at its largest and presents its "new phase" when it is between Earth and the Sun. Its atmosphere can be seen in a telescope by the halo of light refracted around it.

text: A total solar eclipse will occur on September 23, 2090. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A total solar eclipse occurs when the Moon's apparent diameter is larger than the Sun's, blocking all direct sunlight, turning day into darkness. Totality occurs in a narrow path across Earth's surface, with the partial solar eclipse visible over a surrounding region thousands of kilometres wide.This solar eclipse will be the first total solar eclipse visible from the United Kingdom mainland since August 11, 1999.

text: A total

text: solar eclipse

text: will occur on September 23, 2090. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: is larger than the Sun's, blocking all direct sunlight, turning day into darkness. Totality occurs in a narrow path across Earth's surface, with the partial solar eclipse visible over a surrounding region thousands of kilometres wide.This solar eclipse will be the first total solar eclipse visible from the

text: United Kingdom

text: mainland since

text: August 11, 1999

text: Note that there are three main moving points: the Sun, the Moon, and the (ascending) node; and that there are three main periods, when each of the three possible pairs of moving points meet one another: the synodic month when the Moon returns to the Sun, the draconic month when the Moon returns to the node, and the eclipse year when the Sun returns to the node.  These three 2-way relations are not independent (i.e. both the synodic month and eclipse year are dependent on the apparent motion of the Sun, both the draconic month and eclipse year are dependent on the motion of the nodes), and indeed the eclipse year can be described as the beat period of the synodic and draconic months (i.e. the period of the difference between the synodic and draconic months); in formula:

text: Note that there are three main moving points: the Sun, the Moon, and the (ascending) node; and that there are three main periods, when each of the three possible pairs of moving points meet one another: the synodic month when the Moon returns to the Sun, the draconic month when the Moon returns to the node, and the eclipse year when the Sun returns to the node.  These three 2-way relations are not independent (i.e. both the synodic month and eclipse year are dependent on the apparent motion of the Sun, both the draconic month and eclipse year are dependent on the motion of the nodes), and indeed the eclipse year can be described as the

text: beat period

text: of the synodic and draconic months (i.e. the period of the difference between the synodic and draconic months); in formula:

text: A partial solar eclipse occurred on February 14, 1953. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: occurred on February 14, 1953. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: An annular solar eclipse will occur on July 3, 2084. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.

text: An annular

text: solar eclipse

text: will occur on July 3, 2084. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: annulus

text: An annular solar eclipse occurred on December 25, 1935. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.This was the 5th solar eclipse in 1935, the maximum possible. The next time this will occur is 2206.

text: An annular

text: solar eclipse

text: occurred on December 25, 1935. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: annulus

text: (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.This was the 5th solar eclipse in 1935, the maximum possible. The next time this will occur is 2206.

text: In 1979, Freitas and Valdes conducted a photographic search of the vicinity of the Earth-Moon triangular libration points  and , and of the solar-synchronized positions in the associated halo orbits, seeking possible orbiting extraterrestrial interstellar probes, but found nothing to a detection limit of about 14th magnitude. The authors conducted a second, more comprehensive photographic search for probes in 1982 that examined the five Earth-Moon Lagrangian positions and included the solar-synchronized positions in the stable L4/L5 libration orbits, the potentially stable nonplanar orbits near L1/L2, Earth-Moon , and also  in the Sun-Earth system. Again no extraterrestrial probes were found to limiting magnitudes of 17–19th magnitude near L3/L4/L5, 10–18th magnitude for /, and 14–16th magnitude for Sun-Earth .

text: In 1979, Freitas and Valdes conducted a photographic search of the vicinity of the Earth-Moon triangular libration points  and , and of the solar-synchronized positions in the associated halo orbits, seeking possible orbiting extraterrestrial interstellar probes, but found nothing to a detection limit of about 14th magnitude. The authors conducted a second, more comprehensive photographic search for probes in 1982 that examined the five Earth-Moon

text: Lagrangian positions

text: and included the solar-synchronized positions in the stable L4/L5 libration orbits, the potentially stable nonplanar orbits near L1/L2, Earth-Moon , and also  in the Sun-Earth system. Again no extraterrestrial probes were found to limiting magnitudes of 17–19th magnitude near L3/L4/L5, 10–18th magnitude for /, and 14–16th magnitude for Sun-Earth .

text: An annular solar eclipse will occur on July 2, 2038. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.

text: An annular

text: solar eclipse

text: will occur on July 2, 2038. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: annulus

text: Gamma (denoted as γ) of an eclipse describes how centrally the shadow of the Moon or Earth strikes the other. The distance, when the axis of the shadow cone passes closest to Earth or Moon's center, is stated as a fraction of the equatorial radius of the Earth. The sign of gamma defines, for a solar eclipse, if the axis of the shadow passes north or south of the center of the Earth; a positive value means north. For a lunar eclipse it defines whether the axis of the Earth's shadow passes north or south of the Moon; a positive value means south. For solar eclipses the Earth is defined as that half which is exposed to the Sun (this changes with the seasons and is not related directly to the Earth's poles or equator, thus the Earth's center is wherever the Sun is directly overhead).

text: Gamma (denoted as

text: γ

text: ) of an

text: eclipse

text: describes how centrally the

text: shadow

text: of the

text: Moon

text: or

text: Earth

text: strikes the other. The distance, when the axis of the shadow cone passes closest to Earth or Moon's center, is stated as a fraction of the

text: equatorial radius

text: of the Earth. The sign of gamma defines, for a solar eclipse, if the axis of the shadow passes north or south of the center of the Earth; a positive value means north. For a lunar eclipse it defines whether the axis of the Earth's shadow passes north or south of the Moon; a positive value means south. For solar eclipses the Earth is defined as that half which is exposed to the Sun (this changes with the seasons and is not related directly to the Earth's poles or equator, thus the Earth's center is wherever the

text: Sun

text: is

text: directly overhead

text: There were 255 lunar eclipse events between -1899 and -1800 (1900 BCE to 1801 BCE)

text: When the inclination of the moon's orbit to the earth's equator is at its minimum of 18°20′, the centre of the moon's disk will be above the horizon every day as far north and as far south as 90°−18°20' or 71°40' latitude, whereas when the inclination is at its maximum of 28°36' the centre of the moon's disk will only be above the horizon every day for latitudes less than 90°−28°36' or 61°24'. At higher latitudes there will be a period of at least a day each month when the moon does not rise, but there will also be a period of at least a day each month during which the moon does not set. This is similar to the behaviour of the sun, but with a period of 27.3 days instead of 365 days. Note that a point on the moon can actually be visible when it is below the horizon by about 34 arc minutes, due to refraction (see Sunrise).

text: When the inclination of the moon's orbit to the earth's equator is at its minimum of 18°20′, the centre of the moon's disk will be above the horizon every day as far north and as far south as 90°−18°20' or 71°40' latitude, whereas when the inclination is at its maximum of 28°36' the centre of the moon's disk will only be above the horizon every day for latitudes less than 90°−28°36' or 61°24'. At higher latitudes there will be a period of at least a day each month when the moon does not rise, but there will also be a period of at least a day each month during which the moon does not set. This is similar to the behaviour of the sun, but with a period of 27.3 days instead of 365 days. Note that a point on the moon can actually be visible when it is below the horizon by about 34 arc minutes, due to refraction (see

text: Sunrise

text: Before the battle in Babylon, Alexander states that the lunar eclipse which some of his men thought was a bad omen means that "the Persian moon will be eclipsed by the Macedonian Sun" with which Aristander the seer agrees. After victory in Babylon, Darius III flees to the Caspian Gates to build and gather up an army; the dispirited commanders of Darius III kill him. In his will, Darius tells Alexander, "Take my daughter, Roxane, for your wife...that our worlds may become as one." Alexander then orders the lords of Persia that had committed regicide to be impaled upon stakes for their betrayal against their former kings.

text: Before the battle in Babylon, Alexander states that the

text: lunar eclipse

text: which some of his men thought was a bad omen means that "the Persian moon will be eclipsed by the Macedonian Sun" with which

text: Aristander

text: the seer agrees. After victory in Babylon, Darius III flees to the Caspian Gates to build and gather up an army; the dispirited commanders of Darius III kill him. In his will, Darius tells Alexander, "Take my daughter,

text: Roxane

text: , for your wife...that

text: our worlds may become as one

text: ." Alexander then orders the lords of Persia that had committed

text: regicide

text: to be impaled upon stakes for their betrayal against their former kings.

text: Eclipses can only occur when the Sun, Earth, and Moon are all in a straight line (termed "syzygy"). Solar eclipses occur at new moon, when the Moon is between the Sun and Earth. In contrast, lunar eclipses occur at full moon, when Earth is between the Sun and Moon. The apparent size of the Moon is roughly the same as that of the Sun, with both being viewed at close to one-half a degree wide. The Sun is much larger than the Moon but it is the precise vastly greater distance that gives it the same apparent size as the much closer and much smaller Moon from the perspective of Earth. The variations in apparent size, due to the non-circular orbits, are nearly the same as well, though occurring in different cycles. This makes possible both total (with the Moon appearing larger than the Sun) and annular (with the Moon appearing smaller than the Sun) solar eclipses. In a total eclipse, the Moon completely covers the disc of the Sun and the solar corona becomes visible to the naked eye. Because the distance between the Moon and Earth is very slowly increasing over time, the angular diameter of the Moon is decreasing. Also, as it evolves toward becoming a red giant, the size of the Sun, and its apparent diameter in the sky, are slowly increasing. The combination of these two changes means that hundreds of millions of years ago, the Moon would always completely cover the Sun on solar eclipses, and no annular eclipses were possible. Likewise, hundreds of millions of years in the future, the Moon will no longer cover the Sun completely, and total solar eclipses will not occur.

text: Eclipses can only occur when the Sun, Earth, and Moon are all in a straight line (termed "

text: syzygy

text: Solar eclipse

text: s occur at

text: new moon

text: , when the Moon is between the Sun and Earth. In contrast,

text: lunar eclipse

text: s occur at

text: full moon

text: , when Earth is between the Sun and Moon. The apparent size of the Moon is roughly the same as that of the Sun, with both being viewed at close to one-half a degree wide. The Sun is much larger than the Moon but it is the precise vastly greater distance that gives it the same apparent size as the much closer and much smaller Moon from the perspective of Earth. The variations in apparent size, due to the non-circular orbits, are nearly the same as well, though occurring in different cycles. This makes possible both

text: total

text: (with the Moon appearing larger than the Sun) and

text: annular

text: (with the Moon appearing smaller than the Sun) solar eclipses. In a total eclipse, the Moon completely covers the disc of the Sun and the solar

text: corona

text: becomes visible to the

text: naked eye

text: . Because the distance between the Moon and Earth is very slowly increasing over time, the angular diameter of the Moon is decreasing. Also, as it evolves toward becoming a

text: red giant

text: , the size of the Sun, and its apparent diameter in the sky, are slowly increasing. The combination of these two changes means that hundreds of millions of years ago, the Moon would always completely cover the Sun on solar eclipses, and no annular eclipses were possible. Likewise, hundreds of millions of years in the future, the Moon will no longer cover the Sun completely, and total solar eclipses will not occur.

text: The context of the essay was to reply to the treatise Libra astronomica ac philosophica of 1619 by Orazio Grassi, a Jesuit mathematician at the Collegio Romano, which used the pseudonym of Lotario Sarsi Sigensano. The debate between Galileo and Grassi started in 1618, when the latter published Disputatio astronomica de tribus cometis anni MDCXVIII, in which he asserted that comets are celestial bodies. Grassi adopted Tycho Brahe's Tychonic system, in which the other planets of the solar system orbit around the sun, which, in turn, orbits around the earth. In his Disputatio Grassi referenced many of Galileo's observations, such as the surface of the moon and the phases of Venus, without mentioning him.Grassi argued from the apparent absence of observable parallax that comets move beyond the moon. Galileo mistakenly believed that comets are an optical illusion.

text: The context of the essay was to reply to the treatise Libra astronomica ac philosophica of 1619 by

text: Orazio Grassi

text: , a

text: Jesuit

text: mathematician at the

text: Collegio Romano

text: , which used the

text: pseudonym

text: of Lotario Sarsi Sigensano. The debate between Galileo and Grassi started in 1618, when the latter published Disputatio astronomica de tribus cometis anni MDCXVIII, in which he asserted that comets are celestial bodies. Grassi adopted

text: Tycho Brahe

text: 's

text: Tychonic system

text: , in which the other planets of the

text: solar system

text: orbit around the

text: sun

text: , which, in turn, orbits around the

text: earth

text: . In his Disputatio Grassi referenced many of Galileo's observations, such as the surface of the

text: moon

text: and the phases of

text: Venus

text: , without mentioning him.Grassi argued from the apparent absence of observable

text: parallax

text: that comets move beyond the moon. Galileo mistakenly believed that comets are an optical illusion.

text: Though life is confirmed only on Earth, many think that extraterrestrial life is not only plausible, but probable or inevitable. Other planets and moons in the Solar System and other planetary systems are being examined for evidence of having once supported simple life, and projects such as SETI are trying to detect radio transmissions from possible alien civilizations. Other locations within the Solar System that may host microbial life include the subsurface of Mars, the upper atmosphere of Venus, and subsurface oceans on some of the moons of the giant planets.Beyond the Solar System, the region around another main-sequence star that could support Earth-like life on an Earth-like planet is known as the habitable zone. The inner and outer radii of this zone vary with the luminosity of the star, as does the time interval during which the zone survives. Stars more massive than the Sun have a larger habitable zone, but remain on the main sequence for a shorter time interval. Small red dwarfs have the opposite problem, with a smaller habitable zone that is subject to higher levels of magnetic activity and the effects of tidal locking from close orbits. Hence, stars in the intermediate mass range such as the Sun may have a greater likelihood for Earth-like life to develop. The location of the star within a galaxy may also affect the likelihood of life forming. Stars in regions with a greater abundance of heavier elements that can form planets, in combination with a low rate of potentially habitat-damaging supernova events, are predicted to have a higher probability of hosting planets with complex life. The variables of the Drake equation are used to discuss the conditions in planetary systems where civilization is most likely to exist. Use of the equation to predict the amount of extraterrestrial life, however, is difficult; because many of the variables are unknown, the equation functions as more of a mirror to what its user already thinks. As a result, the number of civilizations in the galaxy can be estimated as low as 9.1 x 10^-11 or as high as 156 million; for the calculations, see Drake equation.

text: Though life is confirmed only on Earth, many think that

text: extraterrestrial life

text: is not only plausible, but probable or inevitable. Other planets and

text: moons

text: in the

text: Solar System

text: and other

text: planetary system

text: s are being examined for evidence of having once supported simple life, and projects such as

text: SETI

text: are trying to detect radio transmissions from possible alien civilizations. Other locations within the

text: Solar System

text: that may host

text: microbial

text: life include the subsurface of

text: Mars

text: , the upper atmosphere of

text: Venus

text: , and subsurface oceans on some of the

text: moons

text: of the

text: giant planet

text: s.Beyond the Solar System, the region around another

text: main-sequence star

text: that could support Earth-like life on an Earth-like planet is known as the

text: habitable zone

text: . The inner and outer radii of this zone vary with the luminosity of the star, as does the time interval during which the zone survives. Stars more massive than the Sun have a larger habitable zone, but remain on the main sequence for a shorter time interval. Small

text: red dwarf

text: s have the opposite problem, with a smaller habitable zone that is subject to higher levels of magnetic activity and the effects of

text: tidal locking

text: from close orbits. Hence, stars in the intermediate mass range such as the Sun may have a greater likelihood for Earth-like life to develop. The location of the star within a galaxy may also affect the likelihood of life forming. Stars in regions with a greater abundance of heavier elements that can form planets, in combination with a low rate of potentially

text: habitat

text: -damaging

text: supernova

text: events, are predicted to have a higher probability of hosting planets with complex life. The variables of the

text: Drake equation

text: are used to discuss the conditions in planetary systems where civilization is most likely to exist. Use of the equation to predict the amount of extraterrestrial life, however, is difficult; because many of the variables are unknown, the equation functions as more of a mirror to what its user already thinks. As a result, the number of civilizations in the galaxy can be estimated as low as 9.1 x 10^-11 or as high as 156 million; for the calculations, see

text: Drake equation

text: A lunar eclipse occurs when the Moon passes within Earth's umbra (shadow). As the eclipse begins, the Earth's shadow first darkens the Moon slightly.  Then, the shadow begins to "cover" part of the Moon, turning it a dark red-brown color (typically - the color can vary based on atmospheric conditions).  The Moon appears to be reddish because of Rayleigh scattering (the same effect that causes sunsets to appear reddish) and the refraction of that light by the Earth's atmosphere into its umbra.The following simulation shows the approximate appearance of the Moon passing through the earth's shadow. The Moon's brightness is exaggerated within the umbral shadow. The southern portion of the Moon was closest to the center of the shadow, making it darkest, and most red in appearance.

text: A lunar eclipse occurs when the Moon passes within Earth's

text: umbra

text: (shadow). As the eclipse begins, the Earth's shadow first darkens the Moon slightly.  Then, the shadow begins to "cover" part of the Moon, turning it a dark red-brown color (typically - the color can vary based on atmospheric conditions).  The Moon appears to be reddish because of

text: Rayleigh scattering

text: (the same effect that causes sunsets to appear reddish) and the refraction of that light by the Earth's atmosphere into its umbra.The following simulation shows the approximate appearance of the Moon passing through the earth's shadow. The Moon's brightness is exaggerated within the umbral shadow. The southern portion of the Moon was closest to the center of the shadow, making it darkest, and most red in appearance.

text: According to Bunun legend, in times long past, two suns shone down upon the earth and made it unbearably hot. A father and a son endured numerous hardships and finally shot down one of the suns, which then became the moon. In its wrath, the moon demanded that father and son would return to their own people to tell them that they henceforth had to obey three commandments or face annihilation. The first was that they had to constantly observe the waxing and waning of the moon and conduct all rituals and work according to its rhythm. The second commandment stated that all Bunun had to conduct rituals throughout their lives to honor the spirits of heaven and earth. The third commandment told them of forbidden behaviours, and forced them to become an orderly and peaceful tribe.

text: A total lunar eclipse has the direct sunlight completely blocked by the earth's shadow. The only light seen is refracted through the earth's shadow. This light looks red for the same reason that the sunset looks red, due to rayleigh scattering of the more blue light. Because of its reddish color, a total lunar eclipse is sometimes called a blood moon.

text: A total lunar eclipse has the direct sunlight completely blocked by the earth's shadow. The only light seen is refracted through the earth's shadow. This light looks red for the same reason that the sunset looks red, due to

text: rayleigh scattering

text: of the more blue light. Because of its reddish color, a total lunar eclipse is sometimes called a blood moon.

text: Authorized by Congress in 1849, the American Nautical Almanac Office was founded and attached to the Department of the Navy with Charles Henry Davis as the first superintendent.  The American Ephemeris and Nautical Almanac was first published in 1852, containing data for the year 1855. Its data was originally calculated by human "computers", such as Chauncey Wright and Joseph Winlock. Between 1855 and 1881 it had two parts, the first for the meridian of Greenwich contained data on the Sun, Moon, lunar distances, Venus, Mars, Jupiter, and Saturn, which was published separately as The American Nautical Almanac. The second part contained data for the meridian of Washington on the Sun, Moon, planets, principal stars, eclipses, occultations, and other phenomena. Beginning in 1882, data for Mercury, Uranus, and Neptune was added to the first part, with eclipses, occultations, and other phenomena forming a separate third part. In 1916, The American Nautical Almanac ceased to be a reprint of the first part of the American Ephemeris and Nautical Almanac, becoming a separately prepared volume for the navigator. In 1937, the American Ephemeris and Nautical Almanac was divided into seven parts, with data for the meridian of Washington substantially reduced, then eliminated beginning in 1951. Data for Pluto was added in 1950.

text: Authorized by Congress in 1849, the American Nautical Almanac Office was founded and attached to the

text: Department of the Navy

text: with

text: Charles Henry Davis

text: as the first superintendent.  The American Ephemeris and Nautical Almanac was first published in 1852, containing data for the year 1855. Its data was originally calculated by human "computers", such as

text: Chauncey Wright

text: and

text: Joseph Winlock

text: . Between 1855 and 1881 it had two parts, the first for the

text: meridian of Greenwich

text: contained data on the

text: Sun

text: Moon

text: lunar distances

text: Venus

text: Mars

text: Jupiter

text: , and

text: Saturn

text: , which was published separately as The American Nautical Almanac. The second part contained data for the

text: meridian of Washington

text: on the Sun, Moon, planets, principal stars,

text: eclipse

text: s,

text: occultation

text: s, and other phenomena. Beginning in 1882, data for

text: Mercury

text: Uranus

text: , and

text: Neptune

text: was added to the first part, with eclipses, occultations, and other phenomena forming a separate third part. In 1916, The American Nautical Almanac ceased to be a reprint of the first part of the American Ephemeris and Nautical Almanac, becoming a separately prepared volume for the navigator. In 1937, the American Ephemeris and Nautical Almanac was divided into seven parts, with data for the meridian of Washington substantially reduced, then eliminated beginning in 1951. Data for

text: Pluto

text: was added in 1950.

text: The Moon's appearance is considerably more complex. Its motion, like the Sun, is between two limits — known as lunistices rather than solstices. However, its travel between lunistices is considerably faster. It takes a sidereal month to complete its cycle rather than the year-long trek of the Sun. This is further complicated as the lunistices marking the limits of the Moon's movement move on an 18.6 year cycle. For slightly over nine years the extreme limits of the moon are outside the range of sunrise. For the remaining half of the cycle the Moon never exceeds the limits of the range of sunrise. However, much lunar observation was concerned with the phase of the Moon. The cycle from one New Moon to the next runs on an entirely different cycle, the Synodic month. Thus when examining sites for lunar significance the data can appear sparse due the extremely variable nature of the moon. See Moon for more details.

text: The Moon's appearance is considerably more complex. Its motion, like the Sun, is between two limits — known as

text: lunistices

text: rather than solstices. However, its travel between lunistices is considerably faster. It takes a

text: sidereal month

text: to complete its cycle rather than the year-long trek of the Sun. This is further complicated as the lunistices marking the limits of the Moon's movement move on

text: an 18.6 year cycle

text: . For slightly over nine years the extreme limits of the moon are outside the range of sunrise. For the remaining half of the cycle the Moon never exceeds the limits of the range of sunrise. However, much lunar observation was concerned with the

text: phase

text: of the Moon. The cycle from one

text: New Moon

text: to the next runs on an entirely different cycle, the

text: Synodic month

text: . Thus when examining sites for lunar significance the data can appear sparse due the extremely variable nature of the moon. See

text: Moon

text: for more details.

text: The Moon's orbit around the Earth is an ellipse, as is the Earth's orbit around the Sun. The apparent sizes of the Sun and Moon therefore vary. The magnitude of an eclipse is the ratio of the apparent size of the Moon to the apparent size of the Sun during an eclipse. An eclipse that occurs when the Moon is near its closest distance to Earth (i.e., near its perigee) can be a total eclipse because the Moon will appear to be large enough to completely cover the Sun's bright disk or photosphere; a total eclipse has a magnitude greater than 1. Conversely, an eclipse that occurs when the Moon is near its farthest distance from Earth (i.e., near its apogee) can only be an annular eclipse because the Moon will appear to be slightly smaller than the Sun; the magnitude of an annular eclipse is less than 1. Slightly more solar eclipses are annular than total because, on average, the Moon lies too far from Earth to cover the Sun completely. A hybrid eclipse occurs when the magnitude of an eclipse changes during the event from less to greater than one, so the eclipse appears to be total at some locations on Earth and annular at other locations.

text: The Moon's orbit around the Earth is an

text: ellipse

text: , as is the Earth's orbit around the Sun. The apparent sizes of the Sun and Moon therefore vary. The

text: magnitude of an eclipse

text: is the ratio of the apparent size of the Moon to the apparent size of the Sun during an eclipse. An eclipse that occurs when the Moon is near its closest distance to Earth (i.e., near its

text: perigee

text: ) can be a total eclipse because the Moon will appear to be large enough to completely cover the Sun's bright disk or

text: photosphere

text: ; a total eclipse has a magnitude greater than 1. Conversely, an eclipse that occurs when the Moon is near its farthest distance from Earth (i.e., near its

text: apogee

text: ) can only be an annular eclipse because the Moon will appear to be slightly smaller than the Sun; the magnitude of an annular eclipse is less than 1. Slightly more solar eclipses are annular than total because, on average, the Moon lies too far from Earth to cover the Sun completely. A hybrid eclipse occurs when the magnitude of an eclipse changes during the event from less to greater than one, so the eclipse appears to be total at some locations on Earth and annular at other locations.

text: Solar eclipses occur when one of at least three of Pluto's moons passes between Pluto and the Sun, casting a shadow on Pluto. This occurs when one of the satellites' orbital nodes (the points where their orbits cross Pluto's ecliptic) lines up with Pluto and the Sun. Due to Pluto's large axial tilt, this can only occur at two points in Pluto's orbit, at perihelion and aphelion.

text: Solar eclipses

text: occur when one of at least three of Pluto's moons passes between Pluto and the Sun, casting a shadow on Pluto. This occurs when one of the satellites'

text: orbital node

text: s (the points where their orbits cross Pluto's

text: ecliptic

text: ) lines up with Pluto and the Sun. Due to Pluto's large axial tilt, this can only occur at two points in Pluto's orbit, at perihelion and aphelion.

text: Lunar Eclipse is a 1999 Chinese film and the directorial debut from Sixth Generation director Wang Quan'an. It is also the feature film debut of Wang's most frequent collaborator/muse Yu Nan. Unlike his next two films, which focus on rural communities, Lunar Eclipse is an urban drama following the wife of a newlywed couple (Yu Nan) who becomes mesmerized by an amateur photographer (Wu Chao) who claims to have once been in love with a woman who looked just like her. The film was produced by the Beijing Film Studio.

text: Lunar Eclipse is a

text: 1999 Chinese film

text: and the

text: directorial debut

text: from Sixth Generation director

text: Wang Quan'an

text: . It is also the feature film debut of Wang's most frequent collaborator/muse

text: Yu Nan

text: . Unlike his next two films, which focus on rural communities, Lunar Eclipse is an urban drama following the wife of a newlywed couple (Yu Nan) who becomes mesmerized by an amateur photographer (Wu Chao) who claims to have once been in love with a woman who looked just like her. The film was produced by the

text: Beijing Film Studio

text: A partial solar eclipse occurred on August 30, 1924. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: occurred on August 30, 1924. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: Former U.S. President George W. Bush, in an address about his Vision for Space Exploration, suggested that the Moon may serve as a cost-effective construction, launching and fueling site for future space exploration missions. As President Bush noted, "(Lunar) soil contains raw materials that might be harvested and processed into rocket fuel or breathable air."  For example, the proposed Ares V heavy-lift rocket system could cost-effectively deliver raw materials from Earth to a docking station, (connected to the lunar elevator as a counterweight,) where future spacecraft could be built and launched, while extracted lunar resources could be shipped up from a base on the Moon's surface, near the elevator's anchoring point. If the elevator was connected somehow to a lunar base built near the Moon's north pole, then workers could also mine the water ice which is known to exist there, providing an ample source of readily accessible water for the crew at the elevator's docking station. Also, since the total energy needed for transit between the Moon and Mars is considerably less than for between Earth and Mars, this concept could lower some of the engineering obstacles to sending humans to Mars.

text: Former

text: U.S. President

text: George W. Bush

text: , in an address about his

text: Vision for Space Exploration

text: , suggested that the Moon may serve as a cost-effective construction, launching and fueling

text: site

text: for future space exploration missions. As President Bush noted, "(Lunar) soil contains raw materials that might be harvested and processed into rocket fuel or breathable air."  For example, the proposed

text: Ares V

text: heavy-lift rocket system could cost-effectively deliver

text: raw material

text: s from Earth to a

text: docking station

text: , (connected to the lunar elevator as a counterweight,) where future spacecraft could be built and launched, while extracted lunar resources could be shipped up from a base on the Moon's surface, near the elevator's anchoring point. If the elevator was connected somehow to a lunar base built near the Moon's north pole, then workers could also mine the water ice which is known to exist there, providing an ample source of readily accessible water for the crew at the elevator's docking station. Also, since the total energy needed for transit between the Moon and Mars is considerably less than for between Earth and Mars, this concept could lower some of the engineering obstacles to sending humans to Mars.

text: Unlike a solar eclipse, which can be viewed only from a certain relatively small area of the world, a lunar eclipse may be viewed from anywhere on the night side of the Earth. A lunar eclipse lasts for a few hours, whereas a total solar eclipse lasts for only a few minutes at any given place, due to the smaller size of the Moon's shadow. Also unlike solar eclipses, lunar eclipses are safe to view without any eye protection or special precautions, as they are dimmer than the full moon.

text: Unlike a

text: solar eclipse

text: , which can be viewed only from a certain relatively small area of the world, a lunar eclipse may be viewed from anywhere on the night side of the Earth. A lunar eclipse lasts for a few hours, whereas a total solar eclipse lasts for only a few minutes at any given place, due to the smaller size of the Moon's shadow. Also unlike solar eclipses, lunar eclipses are safe to view without any eye protection or special precautions, as they are dimmer than the full moon.

text: The proximity of the Moon in relation to Earth and Earth in relation to the Sun also has an effect on tidal ranges.  The Moon moves around Earth in an elliptic orbit that takes about 29 days to complete.  The gravitational force is greatest when the Moon is at perigee — closest to Earth — and least when it is at apogee — farthest from Earth — about two weeks after perigee.  The Moon has a larger effect on the tides than the Sun, but the Sun’s position also has an influence on the tides.  Earth moves around the Sun in an elliptic orbit that takes a little over 365 days to complete.  Its gravitational force is greatest when the Earth is at perihelion — closest to the Sun in early January — and least when the Earth is at aphelion — farthest from the Sun in early July.

text: The proximity of the Moon in relation to Earth and Earth in relation to the Sun also has an effect on tidal ranges.  The Moon moves around Earth in an elliptic orbit that takes about 29 days to complete.  The gravitational force is greatest when the Moon is at

text: perigee

text: — closest to Earth — and least when it is at

text: apogee

text: — farthest from Earth — about two weeks after perigee.  The Moon has a larger effect on the tides than the Sun, but the Sun’s position also has an influence on the tides.  Earth moves around the Sun in an

text: elliptic orbit

text: that takes a little over 365 days to complete.  Its

text: gravitational force

text: is greatest when the Earth is at perihelion — closest to the Sun in early January — and least when the Earth is at aphelion — farthest from the Sun in early July.

text: The Moon's phases do not repeat very regularly: the time between two similar syzygies may vary between 29.272 and 29.833 days (see new moon for a detailed account). The reason is that the orbit of the Moon is elliptic, its velocity is not constant, so the time of the true syzygy will differ from the mean syzygy.

text: The Moon's

text: phases

text: do not repeat very regularly: the time between two similar syzygies may vary between 29.272 and 29.833 days (see

text: new moon

text: for a detailed account). The reason is that the orbit of the Moon is elliptic, its velocity is not constant, so the time of the true syzygy will differ from the mean syzygy.

text: A partial solar eclipse occurred on May 9, 1967. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: occurred on May 9, 1967. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: The only natural satellite of earth i.e.moon takes about 27.3 days to make one complete orbit around the earth. The earth orbits around the sun once every 365.2422 days (= earth’s orbital speed of 29.79 km per second). The earth and the moon in 27.3 days have moved as a system about 1/12 of the ways around the sun. This means that from one full moon to the next full moon, the moon must travel 2.2 extra days before it appears full moon. This is due to the curve of the earth’s orbit around the sun. The moon is still making one complete orbit (circle) in 27.3 days. But to line up with the earth and sun to become a full moon again it takes 29.531 days which means 354.372 days per lunar year. This makes a variance of 10.87 days a year between a lunar year and a solar year of 365.2422 days per year. To compensate this difference, the additional mass is been added after every 32.5 months on an average.

text: The only natural satellite of

text: earth

text: i.e.

text: moon

text: takes about 27.3 days to make one complete orbit around the earth. The earth orbits around the sun once every 365.2422 days (= earth’s orbital speed of 29.79 km per second). The earth and the moon in 27.3 days have moved as a system about 1/12 of the ways around the sun. This means that from one full moon to the next full moon, the moon must travel 2.2 extra days before it appears full moon. This is due to the curve of the earth’s orbit around the sun. The moon is still making one complete orbit (circle) in 27.3 days. But to line up with the earth and sun to become a full moon again it takes 29.531 days which means 354.372 days per lunar year. This makes a variance of 10.87 days a year between a lunar year and a solar year of 365.2422 days per year. To compensate this difference, the additional mass is been added after every 32.5 months on an average.

text: The system also models the phases of the moon. The moon pointer holds a shaft along its length, on which is mounted a small gear named r, which meshes to the sun pointer at B0 (the connection between B0 and the rest of B is not visible in the original mechanism, so whether b0 is the current date/mean sun pointer or a hypothetical true sun pointer is not known). The gear rides around the dial with the moon, but is also geared to the sun — the effect is to perform a differential gear operation, so the gear turns at the synodic month period, measuring in effect, the angle of the difference between the sun and moon pointers.  The gear drives a small ball that appears through an opening in the moon pointer's face, painted longitudinally half white and half black, displaying the phases pictorially. It turns with a modelled rotational period of 29.53 days; the modern value for the synodic month is 29.530589 days.

text: The system also models the

text: phases of the moon

text: . The moon pointer holds a shaft along its length, on which is mounted a small gear named r, which meshes to the sun pointer at B0 (the connection between B0 and the rest of B is not visible in the original mechanism, so whether b0 is the current date/mean sun pointer or a hypothetical true sun pointer is not known). The gear rides around the dial with the moon, but is also geared to the sun — the effect is to perform a

text: differential gear

text: operation, so the gear turns at the synodic month period, measuring in effect, the angle of the difference between the sun and moon pointers.  The gear drives a small ball that appears through an opening in the moon pointer's face, painted longitudinally half white and half black, displaying the phases pictorially. It turns with a modelled rotational period of 29.53 days; the modern value for the synodic month is 29.530589 days.

text: An annular solar eclipse occurred on April 7, 1940. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.

text: An annular

text: solar eclipse

text: occurred on April 7, 1940. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: annulus

text: V1191 Cygni is the variable star designation for an overcontact binary star system in the constellation Cygnus. First found to be variable in 1965, it is a W Ursae Majoris variable with a maximum apparent magnitude 10.82. It drops by 0.33 magnitudes during primary eclipses with a period of 0.3134 days, while dropping by 0.29 magnitudes during secondary eclipses. The primary star, which is also the cooler star, appears to have a spectral type of F6V, while the secondary is slightly cooler with a spectral type of G5V. With a mass of 1.29 solar masses and a luminosity of 2.71 solar luminosities, it is slightly more massive and luminous than the sun, while the secondary is only around 1/10 as massive and less than half as luminous. With a separation of 2.20 solar radii, the mass transfer of about 2×10 solar masses per year from the secondary to the primary is one of the highest known for a system of its type.

text: V1191 Cygni is the

text: variable star designation

text: for an

text: overcontact binary

text: star system

text: in the constellation

text: Cygnus

text: . First found to be variable in 1965, it is a

text: W Ursae Majoris variable

text: with a maximum

text: apparent magnitude

text: 10.82. It drops by 0.33 magnitudes during primary eclipses with a period of 0.3134 days, while dropping by 0.29 magnitudes during secondary eclipses. The primary star, which is also the cooler star, appears to have a

text: spectral type

text: of F6V, while the secondary is slightly cooler with a spectral type of G5V. With a mass of 1.29

text: solar mass

text: es and a luminosity of 2.71

text: solar luminosities

text: , it is slightly more massive and luminous than the sun, while the secondary is only around 1/10 as massive and less than half as luminous. With a separation of 2.20

text: solar radii

text: , the

text: mass transfer

text: of about 2×10 solar masses per year from the secondary to the primary is one of the highest known for a system of its type.

text: A solar eclipse occurs when the moon passes between the Earth and the sun, casting a shadow on Earth that temporarily obscures part or all of the sun's disc.  Eclipses can occur only when all three bodies are properly aligned.  Partial eclipses, in which only a portion of the sun's surface is obscured, are relatively common due to the width of the moon's outer shadow, or penumbra, which may be several hundred miles wide.  Total eclipses occur when the moon's inner shadow, or umbra, reaches the surface of the earth, completely obscuring the sun over a much narrower portion of the ground.  If the moon is too far away at the time of an eclipse, its umbra may not reach the Earth's surface, and only a partial eclipse will be visible.

text: A

text: solar eclipse

text: occurs when the

text: moon

text: passes between the

text: Earth

text: and the

text: sun

text: , casting a shadow on Earth that temporarily obscures part or all of the sun's disc.  Eclipses can occur only when all three bodies are properly aligned.  Partial eclipses, in which only a portion of the sun's surface is obscured, are relatively common due to the width of the moon's outer shadow, or penumbra, which may be several hundred miles wide.  Total eclipses occur when the moon's inner shadow, or umbra, reaches the surface of the earth, completely obscuring the sun over a much narrower portion of the ground.  If the moon is too far away at the time of an eclipse, its umbra may not reach the Earth's surface, and only a partial eclipse will be visible.

text: Tau Canis Majoris is a Beta Lyrae-type eclipsing multiple star system that varies from magnitude 4.32 to 4.37 over 1.28 days. Its four main component stars are hot O-type stars, with a combined mass 80 times that of the Sun and shining with 500,000 times its luminosity, but little is known of their individual properties. A fifth component, a magnitude 10 star, lies at a distance of . The system is only 5 million years old. UW Canis Majoris is another Beta Lyrae-type star 3000 light-years from Earth; it is an eclipsing binary that ranges in magnitude from a minimum of 5.3 to a maximum of 4.8. It has a period of 4.4 days; its components are two massive hot blue stars, one a blue supergiant of spectral type O7.5-8 Iab, while its companion is a slightly cooler, less evolved and less luminous supergiant of spectral type O9.7Ib. The stars are 200,000 and 63,000 times as luminous as the Sun. However the fainter star is the more massive at 19 solar masses to the primary's 16. R Canis Majoris is another eclipsing binary that varies from magnitude 5.7 to 6.34 over 1.13 days, with a third star orbiting these two every 93 years. The shortness of the orbital period and the low ratio between the two main components make this an unusual Algol-type system.

text: Tau Canis Majoris

text: is a

text: Beta Lyrae-type

text: eclipsing multiple star system that varies from magnitude 4.32 to 4.37 over 1.28 days. Its four main component stars are hot O-type stars, with a combined mass 80 times that of the Sun and shining with 500,000 times its luminosity, but little is known of their individual properties. A fifth component, a magnitude 10 star, lies at a distance of . The system is only 5 million years old.

text: UW Canis Majoris

text: is another Beta Lyrae-type star 3000 light-years from Earth; it is an

text: eclipsing binary

text: that ranges in magnitude from a minimum of 5.3 to a maximum of 4.8. It has a period of 4.4 days; its components are two massive hot blue stars, one a

text: blue supergiant

text: of spectral type O7.5-8 Iab, while its companion is a slightly cooler, less evolved and less luminous supergiant of spectral type O9.7Ib. The stars are 200,000 and 63,000 times as luminous as the Sun. However the fainter star is the more massive at 19

text: solar mass

text: es to the primary's 16.

text: R Canis Majoris

text: is another eclipsing binary that varies from magnitude 5.7 to 6.34 over 1.13 days, with a third star orbiting these two every 93 years. The shortness of the orbital period and the low ratio between the two main components make this an unusual Algol-type system.

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: An annular solar eclipse occurred on July 31, 1962. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.

text: An annular

text: solar eclipse

text: occurred on July 31, 1962. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: annulus

text: The combined effect of the Sun and Moon on the Earth's oceans, the tide, is greatest when the Moon is either new or full. At a lunar perigee, the tidal force is somewhat stronger, resulting in perigean spring tides.  But, even at its most powerful, this force is still relatively weak, causing tidal differences of inches at most.

text: The combined effect of the Sun and Moon on the Earth's oceans, the

text: tide

text: , is

text: greatest

text: when the Moon is either

text: new

text: or

text: full

text: . At a lunar perigee, the tidal force is somewhat stronger, resulting in

text: perigean spring tide

text: s.  But, even at its most powerful, this force is still relatively weak, causing tidal differences of inches at most.

text: This eclipse at the moon's ascending node was the second of two lunar eclipses to occur in 2007. The first at the descending node was on March 3, 2007.

text: This eclipse at the moon's

text: ascending node

text: was the second of two lunar eclipses to occur in 2007. The

text: first at the descending node

text: was on March 3, 2007.

text: After one saros, the Moon will have completed roughly an integer number of lunar orbit cycles and synodic, draconic, and anomalistic periods (241, 223, 242, and 239) and the Earth-Sun-Moon geometry will be nearly identical: the Moon will have the same phase and be at the same node and the same distance from the Earth. In addition, because the saros is close to 18 years in length (about 11 days longer), the earth will be nearly the same distance from the sun, and tilted to it in nearly the same orientation (same season). Given the date of an eclipse, one saros later a nearly identical eclipse can be predicted. During this 18-year period, about 40 other solar and lunar eclipses take place, but with a somewhat different geometry. One saros equaling 18.03 years is not equal to a perfect integer number of lunar orbits (earth revolutions with respect to the fixed stars of 27.32166 days sidereal month), therefore, even though the relative geometry of the Earth-Sun-Moon system will be nearly identical after a saros, the Moon will be in a slightly different position with respect to the stars for each eclipse in a Saros series.  The axis of rotation of the Earth-Moon system exhibits a precession period of 18.59992 years).

text: After one saros, the Moon will have completed roughly an integer number of lunar orbit cycles and synodic, draconic, and anomalistic periods (241, 223, 242, and 239) and the Earth-Sun-Moon geometry will be nearly identical: the Moon will have the same phase and be at the same node and the same distance from the Earth. In addition, because the saros is close to 18 years in length (about 11 days longer), the earth will be nearly the same distance from the sun, and tilted to it in nearly the same orientation (same season). Given the date of an eclipse, one saros later a nearly identical eclipse can be predicted. During this 18-year period, about 40 other solar and lunar eclipses take place, but with a somewhat different geometry. One saros equaling 18.03 years is not equal to a perfect integer number of lunar orbits (earth revolutions with respect to the fixed stars of 27.32166 days

text: sidereal month

text: ), therefore, even though the relative geometry of the Earth-Sun-Moon system will be nearly identical after a saros, the Moon will be in a slightly different position with respect to the stars for each eclipse in a Saros series.  The axis of rotation of the Earth-Moon system exhibits a

text: precession

text: period of 18.59992 years).

text: It is a relatively rare central eclipse where the moon passes in front of the center of the Earth's shadow. It was the "longest and deepest lunar eclipse to be seen in 7 years". In the total lunar eclipse of July 16, 2000 the moon passed within two arc minutes of the center of the Earth's shadow. In comparison, this still very deep eclipse was off-center by over 12 minutes of arc. The next total lunar eclipse of a longer duration was on June 15, 2011.

text: It is a relatively rare

text: central

text: eclipse where the moon passes in front of the center of the Earth's shadow. It was the "longest and deepest lunar eclipse to be seen in 7 years". In the

text: total lunar eclipse of July 16, 2000

text: the moon passed within two arc minutes of the center of the Earth's shadow. In comparison, this still very deep eclipse was off-center by over 12 minutes of arc. The next total lunar eclipse of a longer duration was on

text: June 15, 2011

text: A partial solar eclipse will occur on July 12, 2094. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: will occur on July 12, 2094. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: A full moon is often thought of as an event of a full night's duration. This is somewhat misleading because the Moon seen from Earth is continuously becoming larger and/or smaller (though much too slowly to notice with the naked eye). Its absolute maximum size occurs at the moment expansion has stopped. For any given location, about half of these absolute maximum full moons will be potentially visible, as the other half occur during the day, when the full moon is below the horizon. Many almanacs list full moons not just by date, but by their exact time as well, usually in Coordinated Universal Time (UTC). Typical monthly calendars that include phases of the Moon may be offset by one day if intended for use in a different time zone.

text: A full moon is often thought of as an event of a full night's duration. This is somewhat misleading because the Moon seen from Earth is continuously becoming larger and/or smaller (though much too slowly to notice with the

text: naked eye

text: ). Its absolute maximum size occurs at the moment expansion has stopped. For any given location, about half of these absolute maximum full moons will be potentially visible, as the other half occur during the day, when the full moon is below the horizon. Many

text: almanac

text: s list full moons not just by date, but by their exact time as well, usually in

text: Coordinated Universal Time

text: (UTC). Typical monthly

text: calendars

text: that include phases of the Moon may be offset by one day if intended for use in a different

text: time zone

text: The eclipse was part of Saros series 136, as was the solar eclipse of July 11, 1991, which was slightly longer, lasting up to 6 minutes 53 seconds (previous eclipses of the same saros series on June 30, 1973 and June 20, 1955, were longer, lasting 7 min 04 and 7 min 08, respectively). The next event from this series will be on August 2, 2027. The exceptional duration was a result of the Moon being near perigee, with the apparent diameter of the Moon 8% larger than the Sun (magnitude 1.080) and the Earth being near aphelion where the Sun appeared slightly smaller.

text: The eclipse was part of

text: Saros series

text: 136, as was the

text: solar eclipse of July 11, 1991

text: , which was slightly longer, lasting up to 6 minutes 53 seconds (previous eclipses of the same saros series on June 30, 1973 and June 20, 1955, were longer, lasting 7 min 04 and 7 min 08, respectively). The next event from this series will be on August 2, 2027. The exceptional duration was a result of the

text: Moon

text: being near

text: perigee

text: , with the apparent diameter of the Moon 8% larger than the

text: Sun

text: magnitude

text: 1.080) and the Earth being near

text: aphelion

text: where the Sun appeared slightly smaller.

text: The WMAP spacecraft arrived at the Kennedy Space Center on April 20, 2001. After being tested for two months, it was launched via Delta II 7425 rocket on June 30, 2001. It began operating on its internal power five minutes before its launching, and so continued operating until the solar panel array deployed. The WMAP was activated and monitored while it cooled. On July 2, it began working, first with in-flight testing (from launching until August 17), then began constant, formal work. Afterwards, it effected three Earth-Moon phase loops, measuring its sidelobes, then flew by the Moon on July 30, en route to the Sun-Earth  Lagrangian point, arriving there on October 1, 2001, becoming the first CMB observation mission posted there.

text: The WMAP spacecraft arrived at the Kennedy Space Center on April 20, 2001. After being tested for two months, it was launched via Delta II 7425 rocket on June 30, 2001. It began operating on its internal power five minutes before its launching, and so continued operating until the solar panel array deployed. The WMAP was activated and monitored while it cooled. On July 2, it began working, first with in-flight testing (from launching until August 17), then began constant, formal work. Afterwards, it effected three Earth-Moon phase loops, measuring its

text: sidelobe

text: s, then flew by the Moon on July 30, en route to the Sun-Earth

text: Lagrangian point

text: , arriving there on October 1, 2001, becoming the first CMB observation mission posted there.

text: An annular solar eclipse will occur on March 20, 2053. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.

text: An annular

text: solar eclipse

text: will occur on March 20, 2053. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: annulus

text: A partial solar eclipse will occur on September 23, 2033. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: will occur on September 23, 2033. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: , thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's

text: shadow

text: misses the Earth.

text: Minokawa is a giant bird that belongs to the dragon family. Early people believed this creature is so big that it can swallow (or cover) the sun to explain the occurrence of eclipses.  It is even described as a giant bird named Minokawa that lives in outer space which can devour the sun and the moon, and would try to do the same with the earth.

text: Minokawa is a giant bird that belongs to the

text: dragon

text: family. Early people believed this creature is so big that it can swallow (or cover) the sun to explain the occurrence of eclipses.  It is even described as a giant bird named Minokawa that lives in outer space which can devour the sun and the moon, and would try to do the same with the earth.

text: A partial solar eclipse occurred on July 19, 1917. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: occurred on July 19, 1917. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: The solar eclipse of October 25, 2022, is a partial solar eclipse that will be visible from Europe, the Middle East, and Western Asia. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: The solar eclipse of October 25, 2022, is a partial

text: solar eclipse

text: that will be visible from Europe, the Middle East, and Western Asia. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: Regardless of the culture, all lunar months approximate the mean length of the synodic month, or how long it takes on average to pass through each phase (new, half, full moon) and back again. It takes 29–30  days. The moon completes its orbit around the earth in 27.3 days (the sidereal month), but due to the Earth's motion around the sun it has not finished a full (synodic) cycle until it reaches the point in its orbit where the sun is in the same position.

text: Regardless of the culture, all lunar months approximate the mean length of the synodic month, or how long it takes on average to pass through each phase (

text: new

text: half

text: full moon

text: ) and back again. It takes 29–30

text: day

text: s. The moon completes its orbit around the earth in 27.3 days (the sidereal month), but due to the Earth's motion around the sun it has not finished a full (synodic) cycle until it reaches the point in its orbit where the sun is in the same position.

text: An annular solar eclipse occurred on July 10, 1907. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.

text: An annular

text: solar eclipse

text: occurred on July 10, 1907. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: annulus

text: A partial solar eclipse occurred on August 9, 1953. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: occurred on August 9, 1953. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: If the Moon just revolved around the Earth, there would be no way to tell what fraction of the Moon's or the Earth's gravity was caused by each form of mass, since only the total can be measured. However, the orbit of the Moon is also strongly affected by the gravity of the sun—in essence, Earth and Moon are in freefall around the sun. If the energy portion of mass behaves differently from the conventional portion, then the Earth and the Moon will fall differently toward the Sun, and the orbit of the Moon around the Earth will be affected. For example, suppose the energy part of the mass does affect gravity, but does not affect inertia. Then:

text: China has pursued an ambitious program of lunar exploration, beginning with Chang'e 1, which successfully orbited the Moon from 5 November 2007 until its controlled lunar impact on 1 March 2009. In its sixteen-month mission, it obtained a full image map of the Moon. China followed up this success with Chang'e 2 beginning in October 2010, which reached the Moon over twice as fast as Chang'e 1, mapped the Moon at a higher resolution over an eight-month period, then left lunar orbit in favor of an extended stay at the Earth–Sun L2 Lagrangian point, before finally performing a flyby of asteroid 4179 Toutatis on 13 December 2012, and then heading off into deep space. On 14 December 2013, Chang'e 3 improved upon its orbital mission predecessors by landing a lunar lander onto the Moon's surface, which in turn deployed a lunar rover, named Yutu (Chinese: 玉兔; literally "Jade Rabbit"). In so doing, Chang'e 3 made the first lunar soft landing since Luna 24 in 1976, and the first lunar rover mission since Lunokhod 2 in 1973. China intends to launch another rover mission (Chang'e 4) before 2020, followed by a sample return mission (Chang'e 5) soon after.

text: China has pursued an ambitious

text: program of lunar exploration

text: , beginning with

text: Chang'e 1

text: , which successfully orbited the Moon from 5 November 2007 until its controlled lunar impact on 1 March 2009. In its sixteen-month mission, it obtained a full image map of the Moon. China followed up this success with

text: Chang'e 2

text: beginning in October 2010, which reached the Moon over twice as fast as Chang'e 1, mapped the Moon at a higher resolution over an eight-month period, then left lunar orbit in favor of an extended stay at the Earth–Sun L2

text: Lagrangian point

text: , before finally performing a flyby of asteroid

text: 4179 Toutatis

text: on 13 December 2012, and then heading off into deep space. On 14 December 2013,

text: Chang'e 3

text: improved upon its orbital mission predecessors by landing a lunar

text: lander

text: onto the Moon's surface, which in turn deployed a

text: lunar rover

text: , named Yutu (Chinese: 玉兔; literally "Jade Rabbit"). In so doing, Chang'e 3 made the first lunar

text: soft landing

text: since

text: Luna 24

text: in 1976, and the first lunar rover mission since

text: Lunokhod 2

text: in 1973. China intends to launch another rover mission (

text: Chang'e 4

text: ) before 2020, followed by a

text: sample return mission

text: Chang'e 5

text: ) soon after.

text: From one day to the next, the view of the Moon would change very differently for an observer on Mars than for an observer on Earth. The phase of the Moon as seen from Mars would not change much from day to day; it would match the phase of the Earth, and would only gradually change as both Earth and Moon move in their orbits around the Sun. On the other hand, an observer on Mars would see the Moon rotate, with the same period as its orbital period, and would see far side features that can never be seen from Earth.

text: From one day to the next, the view of the Moon would change very differently for an observer on Mars than for an observer on Earth. The

text: phase of the Moon

text: as seen from Mars would not change much from day to day; it would match the phase of the Earth, and would only gradually change as both Earth and Moon move in their orbits around the Sun. On the other hand, an observer on Mars would see the Moon rotate, with the same period as its orbital period, and would see far side features that can never be seen from Earth.

text: As observed from the Earth, a solar eclipse occurs when the Moon passes in front of the Sun. The type of solar eclipse event depends on the distance of the Moon from the Earth during the event. A total solar eclipse occurs when the Earth intersects the umbra portion of the Moon's shadow. When the umbra does not reach the surface of the Earth, the Sun is only partially occulted, resulting in an annular eclipse. Partial solar eclipses occur when the viewer is inside the penumbra.

text: As observed from the Earth, a

text: solar eclipse

text: occurs when the Moon passes in front of the Sun. The type of solar eclipse event depends on the distance of the Moon from the Earth during the event. A total solar eclipse occurs when the Earth intersects the umbra portion of the Moon's shadow. When the umbra does not reach the surface of the Earth, the Sun is only partially occulted, resulting in an annular eclipse. Partial solar eclipses occur when the viewer is inside the penumbra.

text: A partial solar eclipse occurred on December 13, 1974. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: occurred on December 13, 1974. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: A lunar eclipse occurs when the Moon passes within Earth's umbra (shadow). As the eclipse begins, Earth's shadow first darkens the Moon slightly.  Then, the shadow begins to "cover" part of the Moon, turning it a dark red-brown color (typically – the color can vary based on atmospheric conditions). The Moon appears to be reddish because of Rayleigh scattering (the same effect that causes sunsets to appear reddish) and the refraction of that light by Earth's atmosphere into its umbra.

text: umbra

text: (shadow). As the eclipse begins, Earth's shadow first darkens the Moon slightly.  Then, the shadow begins to "cover" part of the Moon, turning it a dark red-brown color (typically – the color can vary based on atmospheric conditions). The Moon appears to be reddish because of

text: Rayleigh scattering

text: (the same effect that causes sunsets to appear reddish) and the refraction of that light by Earth's atmosphere into its umbra.

text: A partial solar eclipse occurred on June 1, 2011. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.This eclipse is the second of four partial solar eclipses in 2011, with the others occurring on January 4, 2011, July 1, 2011, and November 25, 2011.

text: A

text: partial solar eclipse

text: occurred on June 1, 2011. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: , thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.This eclipse is the second of four partial solar eclipses in 2011, with the others occurring on

text: January 4, 2011

text: July 1, 2011

text: , and

text: November 25, 2011

text: A total solar eclipse occurred on 11 August 1999 with an eclipse magnitude of 1.029. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A total solar eclipse occurs when the Moon's apparent diameter is larger than the Sun's, blocking all direct sunlight, turning day into darkness. Totality occurs in a narrow path across Earth's surface, with the partial solar eclipse visible over a surrounding region thousands of kilometres wide.The path of the Moon's shadow began in the Atlantic Ocean and, before noon, was traversing the southern United Kingdom, northern France, Belgium, Luxembourg, southern Germany, Austria, Slovenia, Croatia, Hungary, and northern FR Yugoslavia (Vojvodina). Its maximum was at 11:03 UTC at  in Romania (next to a town called Ocnele Mari near Râmnicu Vâlcea); and it continued across Bulgaria, the Black Sea, Turkey, Iran, southern Pakistan and Srikakulam in India and ended in the Bay of Bengal.

text: A total

text: solar eclipse

text: occurred on 11 August 1999 with an

text: eclipse magnitude

text: of 1.029. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: is larger than the Sun's, blocking all direct sunlight, turning day into darkness. Totality occurs in a narrow path across Earth's surface, with the partial solar eclipse visible over a surrounding region thousands of kilometres wide.The path of the

text: Moon

text: 's shadow began in the

text: Atlantic Ocean

text: and, before noon, was traversing the southern

text: United Kingdom

text: , northern

text: France

text: Belgium

text: Luxembourg

text: , southern

text: Germany

text: Austria

text: Slovenia

text: Croatia

text: Hungary

text: , and northern

text: FR Yugoslavia

text: Vojvodina

text: ). Its maximum was at 11:03 UTC at  in

text: Romania

text: (next to a town called

text: Ocnele Mari

text: near

text: Râmnicu Vâlcea

text: ); and it continued across

text: Bulgaria

text: , the

text: Black Sea

text: Turkey

text: Iran

text: , southern

text: Pakistan

text: and

text: Srikakulam

text: in

text: India

text: and ended in the

text: Bay of Bengal

text: In the 2nd century CE, Ptolemy estimated the mean distance of the Sun as  times Earth's radius. To determine this value, Ptolemy started by measuring the Moon's parallax, finding what amounted to a horizontal lunar parallax of 1° 26′, which was much too large. He then derived a maximum lunar distance of 64 Earth radii. Because of cancelling errors in his parallax figure, his theory of the Moon's orbit, and other factors, this figure was approximately correct. He then measured the apparent sizes of the Sun and the Moon and concluded that the apparent diameter of the Sun was equal to the apparent diameter of the Moon at the Moon's greatest distance, and from records of lunar eclipses, he estimated this apparent diameter, as well as the apparent diameter of the shadow cone of Earth traversed by the Moon during a lunar eclipse. Given these data, the distance of the Sun from Earth can be trigonometrically computed to be  Earth radii. This gives a ratio of solar to lunar distance of approximately 19, matching Aristarchus's figure. Although Ptolemy's procedure is theoretically workable, it is very sensitive to small changes in the data, so much so that changing a measurement by a few percent can make the solar distance infinite.

text: In the 2nd century CE,

text: Ptolemy

text: estimated the mean distance of the Sun as  times

text: Earth's radius

text: A partial solar eclipse will occur on July 22, 2047. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: will occur on July 22, 2047. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: A shadow cast by the Earth on the Moon is a lunar eclipse. Conversely, a shadow cast by the Moon on the Earth is a solar eclipse.

text: A shadow cast by the

text: Earth

text: on the

text: Moon

text: is a

text: lunar eclipse

text: . Conversely, a shadow cast by the Moon on the Earth is a

text: solar eclipse

text: This is a directory of lists of geological features on planets excepting Earth, moons and asteroids ordered by increasing distance from the Sun.

text: This is a directory of lists of geological features on

text: planet

text: s excepting

text: Earth

text: moon

text: s and

text: asteroid

text: s ordered by increasing distance from the

text: Sun

text: A wet moon (also called a Cheshire moon) is a lunar phase when the "horns" of the crescent moon point up at an angle, away from the horizon, so the moon's crescent takes on the appearance of a bowl or a smile. A wet moon occurs when the crescent moon is near the horizon at a point more or less directly above the sun's (invisible) position below the horizon.  This in turn is determined by the earth's and moon's positions in their orbits, the inclination of these orbits relative to one another and to the earth's axis, and observer's latitude on the earth.  Wet moons occur routinely in the tropics (where the sun and moon rise and set nearly vertically), and rarely in polar regions (where the sun and moon rise and set at a glancing angle or not at all).

text: A wet moon (also called a Cheshire moon) is a

text: lunar phase

text: when the "horns" of the

text: crescent moon

text: point up at an angle, away from the

text: horizon

text: , so the moon's crescent takes on the appearance of a

text: bowl

text: or a

text: smile

text: . A wet moon occurs when the crescent moon is near the horizon at a point more or less directly above the sun's (invisible) position below the horizon.  This in turn is determined by the earth's and moon's positions in their orbits, the inclination of these orbits relative to one another and to the earth's axis, and observer's latitude on the earth.  Wet moons occur routinely in the tropics (where the sun and moon rise and set nearly vertically), and rarely in polar regions (where the sun and moon rise and set at a glancing angle or not at all).

text: A partial solar eclipse occurred on June 21, 1982. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: occurred on June 21, 1982. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: An annular solar eclipse will occur on April 10, 2089. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.

text: An

text: annular

text: solar eclipse

text: will occur on April 10,

text: . A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: annulus

text: An annular solar eclipse will occur on October 25, 2041. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.

text: An annular

text: solar eclipse

text: will occur on October 25, 2041. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: annulus

text: Spaceports have been proposed for locations on the Moon, Mars, orbiting the Earth, at Sun-Earth and Earth-Moon Lagrange points, and at other locations in the solar system.  Human-tended outposts on the Moon or Mars, for example, will be spaceports by definition. The 2012 Space Studies Program of the International Space University studied the economic benefit of a network of spaceports throughout the solar system beginning from Earth and expanding outwardly in phases, within its team project Operations And Service Infrastructure for Space (OASIS). Its analysis claimed that the first phase, placing the "Node 1" spaceport with space tug services in Low Earth Orbit (LEO), would be commercially profitable and reduce transportation costs to geosynchronous orbit by as much as 44% (depending on the launch vehicle).  The second phase would add a Node 2 spaceport on the lunar surface to provide services including lunar ice mining and delivery of rocket propellants back to Node 1.  This would enable lunar surface activities and further reduce transportation costs within and out from cislunar space.  The third phase would add a Node 3 spaceport on the Martian moon Phobos to enable refueling and resupply prior to Mars surface landings, missions beyond Mars, and return trips to Earth.  In addition to propellant mining and refueling, the network of spaceports could provide services such as power storage and distribution, in-space assembly and repair of spacecraft, communications relay, shelter, construction and leasing of infrastructure, maintaining spacecraft positioned for future use, and logistics.

text: Spaceports have been proposed for locations on the

text: Moon

text: Mars

text: , orbiting the Earth, at Sun-Earth and Earth-Moon

text: Lagrange point

text: s, and at other locations in the

text: solar system

text: .  Human-tended outposts on the Moon or Mars, for example, will be spaceports by definition. The 2012 Space Studies Program of the

text: International Space University

text: studied the economic benefit of a network of spaceports throughout the solar system beginning from Earth and expanding outwardly in phases, within its team project Operations And Service Infrastructure for Space (OASIS). Its analysis claimed that the first phase, placing the "Node 1" spaceport with space tug services in

text: Low Earth Orbit

text: (LEO), would be commercially profitable and reduce transportation costs to

text: geosynchronous orbit

text: by as much as 44% (depending on the launch vehicle).  The second phase would add a Node 2 spaceport on the lunar surface to provide services including

text: lunar ice

text: mining and delivery of rocket

text: propellant

text: s back to Node 1.  This would enable lunar surface activities and further reduce transportation costs within and out from

text: cislunar

text: space.  The third phase would add a Node 3 spaceport on the Martian moon

text: Phobos

text: to enable refueling and resupply prior to Mars surface landings, missions beyond Mars, and return trips to Earth.  In addition to propellant mining and refueling, the network of spaceports could provide services such as power storage and distribution, in-space assembly and repair of spacecraft, communications relay, shelter, construction and leasing of infrastructure, maintaining spacecraft positioned for future use, and logistics.

text: Dunthorne is particularly remembered for his study of the phenomenon of the changing apparent speed of the Moon in its orbit. Edmond Halley in about 1695 had already suggested on the basis of comparison between contemporary observations and on the other hand ancient records for the timing of ancient eclipses, that the Moon was very gradually accelerating in its orbit.  (It was not yet known in Halley's or in Dunthorne's time that what is actually happening is a slowing-down of the Earth's rate of rotation – see Ephemeris time.) Dunthorne's computations, based in part on records of ancient accounts of eclipses, confirmed the apparent acceleration; and he was the first to quantify the effect, which he put at +10" (arcseconds/century^2) in terms of the difference of lunar longitude.  Dunthorne's estimate is not far from those assessed later, e.g. in 1786 by de Lalande and still not very far away from the values from about 10" to nearly 13" being derived about a century later.

text: Dunthorne is particularly remembered for his study of the phenomenon of the changing apparent speed of the

text: Moon

text: in its

text: orbit

text: Edmond Halley

text: in about 1695 had already suggested on the basis of comparison between contemporary observations and on the other hand ancient records for the timing of ancient eclipses, that the Moon was very gradually accelerating in its orbit.  (It was not yet known in Halley's or in Dunthorne's time that what is actually happening is a slowing-down of the Earth's rate of rotation – see

text: Ephemeris time

text: .) Dunthorne's computations, based in part on records of ancient accounts of eclipses, confirmed the apparent acceleration; and he was the first to quantify the effect, which he put at +10" (arcseconds/century^2) in terms of the difference of lunar longitude.  Dunthorne's estimate is not far from those assessed later, e.g. in 1786 by de Lalande and still not very far away from the values from about 10" to nearly 13" being derived about a century later.

text: In Aristotle's (384–322 BC) description of the universe, the Moon marked the boundary between the spheres of the mutable elements (earth, water, air and fire), and the imperishable stars of aether, an influential philosophy that would dominate for centuries. However, in the , Seleucus of Seleucia correctly theorized that tides were due to the attraction of the Moon, and that their height depends on the Moon's position relative to the Sun. In the same century, Aristarchus computed the size and distance of the Moon from Earth, obtaining a value of about twenty times the radius of Earth for the distance. These figures were greatly improved by Ptolemy (90–168 AD): his values of a mean distance of 59 times Earth's radius and a diameter of 0.292 Earth diameters were close to the correct values of about 60 and 0.273 respectively. Archimedes (287–212 BC) designed a planetarium that could calculate the motions of the Moon and other objects in the Solar System.

text: In

text: Aristotle

text: 's (384–322 BC)

text: description of the universe

text: , the Moon marked the boundary between the spheres of the mutable elements (earth, water, air and fire), and the imperishable stars of

text: aether

text: , an

text: influential philosophy

text: that would dominate for centuries. However, in the ,

text: Seleucus of Seleucia

text: correctly theorized that

text: tide

text: s were due to the attraction of the Moon, and that their height depends on the Moon's position relative to the

text: Sun

text: . In the same century,

text: Aristarchus

text: computed the size and distance

text: of the Moon from Earth, obtaining a value of about twenty times the

text: radius of Earth

text: for the distance. These figures were greatly improved by

text: Ptolemy

text: (90–168 AD): his values of a mean distance of 59 times Earth's radius and a diameter of 0.292 Earth diameters were close to the correct values of about 60 and 0.273 respectively.

text: Archimedes

text: (287–212 BC) designed a planetarium that could calculate the motions of the Moon and other objects in the Solar System.

text: The effect on a lunar eclipse is quite similar, with a few differences. First, the eclipsed body is the Moon and the eclipsing 'body' is the Earth's shadow. Second, since the Earth's shadow at the Moon's distance always is considerably larger than the Moon, a lunar eclipse can never be annular but is always partial or total. Third, the Earth's shadow has two components: the dark umbra and the much brighter penumbra. A lunar eclipse will have two geometric magnitudes: the umbral magnitude and the penumbral magnitude. If the three bodies are not aligned enough, the Moon does not reach into the Earth's umbra - it may still pass through the Earth's penumbra though, and such an eclipse is called a penumbral eclipse.

text: The effect on a lunar eclipse is quite similar, with a few differences. First, the eclipsed body is the Moon and the eclipsing 'body' is the Earth's shadow. Second, since the Earth's shadow at the Moon's distance always is considerably larger than the Moon, a lunar eclipse can never be annular but is always partial or total. Third, the Earth's shadow has two components: the dark

text: umbra

text: and the much brighter

text: penumbra

text: . A lunar eclipse will have two geometric magnitudes: the umbral magnitude and the penumbral magnitude. If the three bodies are not aligned enough, the Moon does not reach into the Earth's umbra - it may still pass through the Earth's penumbra though, and such an eclipse is called a

text: penumbral eclipse

text: An annular solar eclipse will occur on November 5, 2059. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.

text: An annular

text: solar eclipse

text: will occur on November 5, 2059. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: annulus

text: Sun paths at any latitude and any time of the year can be determined from basic geometry. The Earth's axis of rotation tilts about 23.5 degrees, relative to the plane of Earth's solar system orbit around the Sun. As the Earth orbits the Sun, this creates the 47-degree peak-to-peak solar altitude angle difference, and the hemisphere-specific difference between summer and winter.

text: Sun paths at any latitude and any time of the year can be determined from basic geometry. The

text: Earth's axis of rotation

text: tilts about 23.5 degrees, relative to the plane of Earth's

text: solar system

text: orbit

text: around the

text: Sun

text: . As the Earth orbits the Sun, this creates the 47-degree peak-to-peak solar altitude angle difference, and the

text: hemisphere

text: -specific difference between summer and winter.

text: There are three types of lunar eclipses: penumbral, when the Moon crosses only the Earth's penumbra; partial, when the Moon crosses partially into the Earth's umbra; and total, when the Moon crosses entirely into the Earth's umbra. Total lunar eclipses pass through all three phases. Even during a total lunar eclipse, however, the Moon is not completely dark. Sunlight refracted through the Earth's atmosphere enters the umbra and provides a faint illumination. Much as in a sunset, the atmosphere tends to more strongly scatter light with shorter wavelengths, so the illumination of the Moon by refracted light has a red hue, thus the phrase 'Blood Moon' is often found in descriptions of such lunar events as far back as eclipses are recorded.

text: There are three types of lunar eclipses: penumbral, when the Moon crosses only the Earth's penumbra; partial, when the Moon crosses partially into the Earth's

text: umbra

text: ; and total, when the Moon crosses entirely into the Earth's umbra. Total lunar eclipses pass through all three phases. Even during a total lunar eclipse, however, the Moon is not completely dark. Sunlight refracted through the Earth's atmosphere enters the umbra and provides a faint illumination. Much as in a sunset, the atmosphere tends to more strongly scatter light with shorter wavelengths, so the illumination of the Moon by refracted light has a red hue, thus the phrase 'Blood Moon' is often found in descriptions of such lunar events as far back as eclipses are recorded.

text: The town also has other reminders of its long history. The Piedra Máscara (Stone Mask) monument is located on the old road to San Juan Vallarta. It represents the old gods of the pre Hispanic population. The Piedra del Sol y la Luna (Stone of the Sun and Moon) is located on the old road to Xonaca, and depicts a lunar eclipse. The Piedra del Coyote (Coyote Stone) is near the river that leads to Xonaca. It represents the death of a coyote. A cross was later erected over this stone.

text: Al-Ghazali expresses his support for a scientific methodology based on demonstration and mathematics, while discussing astronomy. After describing the scientific facts of the solar eclipse resulting from the Moon coming between the Sun and Earth and the lunar eclipse from the Earth coming between the Sun and Moon, he writes:

text: Al-Ghazali expresses his support for a

text: scientific method

text: ology based on

text: demonstration

text: and

text: mathematics

text: , while

text: discussing astronomy

text: . After describing the

text: scientific

text: facts of the

text: solar eclipse

text: resulting from the Moon coming between the Sun and Earth and the

text: lunar eclipse

text: from the Earth coming between the Sun and Moon, he writes:

text: The tidal accelerations at the surfaces of planets in the Solar System are generally very small. For example, the lunar tidal acceleration at the Earth's surface along the Moon-Earth axis is about 1.1 × 10 g, while the solar tidal acceleration at the Earth's surface along the Sun-Earth axis is about 0.52 × 10 g, where g is the gravitational acceleration at the Earth's surface. Hence the tide-raising force (acceleration) due to the Sun is about 45% of that due to the Moon. The solar tidal acceleration at the Earth's surface was first given by Newton in the Principia.

text: The tidal accelerations at the surfaces of planets in the Solar System are generally very small. For example, the lunar tidal acceleration at the Earth's surface along the Moon-Earth axis is about 1.1 × 10 g, while the solar tidal acceleration at the Earth's surface along the Sun-Earth axis is about 0.52 × 10 g, where g is the

text: gravitational acceleration

text: at the Earth's surface. Hence the tide-raising force (acceleration) due to the Sun is about 45% of that due to the Moon. The solar tidal acceleration at the Earth's surface was first given by Newton in the

text: Principia

text: When the Sun and Moon are aligned on the same side of the Earth, the moon is "new", and the side of the Moon facing Earth is not illuminated by the Sun. As the moon waxes (the amount of illuminated surface as seen from Earth is increasing), the lunar phases progress through new moon, crescent moon, first-quarter moon, gibbous moon, and full moon. The moon is then said to wane as it passes through the gibbous moon, third-quarter moon, crescent moon and back to new moon. The terms "old moon" and "new moon" are not interchangeable. The "old moon" is a waning sliver (which eventually becomes undetectable to the naked eye) until the moment it aligns with the sun and begins to wax, at which point it becomes new again. Half moon is often used to mean the first- and third-quarter moons, while the term 'quarter' refers to the extent of the moon's cycle around the Earth, not its shape.

text: When the Sun and Moon are aligned on the same side of the Earth, the moon is "new", and the side of the Moon facing Earth is not illuminated by the Sun. As the moon waxes (the amount of illuminated surface as seen from Earth is increasing), the lunar phases progress through new moon, crescent moon, first-quarter moon,

text: gibbous

text: moon, and full moon. The moon is then said to wane as it passes through the gibbous moon, third-quarter moon, crescent moon and back to new moon. The terms "old moon" and "new moon" are not interchangeable. The "old moon" is a waning sliver (which eventually becomes undetectable to the naked eye) until the moment it aligns with the sun and begins to wax, at which point it becomes new again. Half moon is often used to mean the first- and third-quarter moons, while the term 'quarter' refers to the extent of the moon's cycle around the Earth, not its shape.

text: The Earth and its Moon are one example of this configuration. Today, the Moon is tidally locked to the Earth; one of its revolutions around the Earth (currently about 29 days) is equal to one of its rotations about its axis, so it always shows one face to the Earth. The Moon will continue to recede from Earth, and Earth's spin will continue to slow gradually. In about 50 billion years, if they survive the Sun's expansion, the Earth and Moon will become tidally locked to each other; each will be caught up in what is called a "spin–orbit resonance" in which the Moon will circle the Earth in about 47 days and both Moon and Earth will rotate around their axes in the same time, each only visible from one hemisphere of the other. Other examples are the Galilean moons of Jupiter (as well as many of Jupiter's smaller moons) and most of the larger moons of Saturn.

text: The Earth and its Moon are one example of this configuration. Today, the Moon is

text: tidally locked

text: to the Earth; one of its revolutions around the Earth (currently about 29 days) is equal to one of its rotations about its axis, so it always shows one face to the Earth. The Moon will continue to recede from Earth, and Earth's spin will continue to slow gradually. In about 50 billion years, if they survive

entity_name: Formation and evolution of the Solar System

text: the Sun's expansion

text: , the Earth and Moon will become tidally locked to each other; each will be caught up in what is called a "spin–orbit resonance" in which the Moon will circle the Earth in about 47 days and both Moon and Earth will rotate around their axes in the same time, each only visible from one hemisphere of the other. Other examples are the

text: Galilean moons

text: of

text: Jupiter

text: (as well as many of Jupiter's smaller moons) and most of the larger moons of

text: Saturn

text: An annular solar eclipse occurred on April 30, 1957. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.

text: An annular

text: solar eclipse

text: occurred on April 30, 1957. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: annulus

text: The Earth, Moon, and some other bodies have, to some extent, the property of retroreflection. Light which strikes them is reflected preferentially back in the direction from which it has come, rather than in other directions. If the light comes from the Sun, it is reflected back toward the Sun and in nearby directions. For example, when its phase is full, the Moon reflects light preferentially toward the Sun, and toward the Earth, which is in almost the same direction. The full Moon therefore appears brighter, when seen from Earth, than it would if it diffused light uniformly in all directions. Similarly, near new moon, earthshine which has been retroreflected by the Earth toward the Sun, or toward the Moon which is in almost the same direction, and then retroreflected again by the Moon toward the Earth appears much brighter, seen from Earth, than it would without the retroreflective effects. The retroreflection is produced by spheres of transparent material on the reflecting surface. When it encounters a transparent sphere, light is preferentially reflected and refracted in a path, within the sphere, which exits it in the direction from which it entered. On the Earth, the spheres are droplets of water in clouds. On the Moon, large numbers of solid glassy spheres are found on the surface. They are thought to have been formed from drops of molten rock, produced by impacts, which cooled and solidified before falling back to the surface.

text: The

text: Earth

text: Moon

text: , and some other bodies have, to some extent, the property of

text: retroreflection

text: . Light which strikes them is reflected preferentially back in the direction from which it has come, rather than in other directions. If the light comes from the Sun, it is reflected back toward the Sun and in nearby directions. For example, when its

text: phase

text: A partial solar eclipse occurred on July 30, 1935. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: occurred on July 30, 1935. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: A partial solar eclipse occurred on September 10, 1942. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: occurred on September 10, 1942. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: Early attempts to measure the distance to the Moon exploited observations of a lunar eclipse combined with knowledge of Earth's radius and an understanding that the Sun is much further than the Moon. By observing the geometry of a lunar eclipse, the lunar distance can be calculated using trigonometry.

text: Early attempts to measure the distance to the Moon exploited observations of a

text: lunar eclipse

text: combined with knowledge of Earth's radius and an understanding that the Sun is much further than the Moon. By observing the geometry of a

text: lunar eclipse

text: , the lunar distance can be calculated using

text: trigonometry

text: Because the Moon's orbit around Earth is inclined by about 5° to the orbit of Earth around the Sun, eclipses do not occur at every full and new moon. For an eclipse to occur, the Moon must be near the intersection of the two orbital planes. The periodicity and recurrence of eclipses of the Sun by the Moon, and of the Moon by Earth, is described by the saros, which has a period of approximately 18 years.

text: Because the Moon's orbit around Earth is inclined by about 5° to the

text: orbit of Earth around the Sun

text: , eclipses do not occur at every full and new moon. For an eclipse to occur, the Moon must be near the intersection of the two orbital planes. The periodicity and recurrence of eclipses of the Sun by the Moon, and of the Moon by Earth, is described by the

text: saros

text: , which has a period of approximately 18 years.

text: A day and night is around 30 Earth days. A day on Subvolva represents the Phases of the Moon on Earth. Subvolva sees the Earth as its moon. The Earth goes through phases just as our Moon does during their night. Kepler notes that Subvolva is inhabited by serpent-like creatures. The Subvolvan terrain is full of fields and towns just like our world. At night on Privolva all of the water is pumped to Subvolva to submerge the land so only a small portion of land remains above the waves. The Subvolvans are protected from the Sun by almost constant cloud cover and rain.

text: Once at Earth-Moon L, Skylab II could be a "stepping stone" for further human exploration in the Solar System, for example by being a docking site for a crewed lunar lander before the trip to the Moon. The second use would be to add a servicing capability for the astrophysics missions located near Earth-Sun L, extending the cryogenic mission lifetime of such missions by continually refilling their liquid helium and enabling some astrophysics missions which may otherwise have not been possible or would have been launched in a less-capable state.

text: Once at Earth-Moon L, Skylab II could be a "

text: stepping stone

text: " for further human exploration in the Solar System, for example by being a docking site for a crewed lunar lander before the trip to the Moon. The second use would be to add a servicing capability for the astrophysics missions located near Earth-Sun L, extending the

text: cryogenic

text: mission lifetime of such missions by continually refilling their

text: liquid helium

text: and enabling some astrophysics missions which may otherwise have not been possible or would have been launched in a less-capable state.

text: Han-era astronomers adopted a geocentric model of the universe, theorizing that it was shaped like a sphere surrounding the earth in the center. They assumed that the Sun, Moon, and planets were spherical and not disc-shaped. They also thought that the illumination of the Moon and planets was caused by sunlight, that lunar eclipses occurred when the Earth obstructed sunlight falling onto the Moon, and that a solar eclipse occurred when the Moon obstructed sunlight from reaching the Earth. Although others disagreed with his model, Wang Chong accurately described the water cycle of the evaporation of water into clouds.

text: Han-era astronomers adopted a

text: geocentric model

text: of the universe, theorizing that it was

text: shaped like a sphere

text: surrounding the earth in the center. They assumed that the Sun, Moon, and planets were spherical and not disc-shaped. They also thought that the illumination of the Moon and planets was caused by

text: sunlight

text: , that

text: lunar eclipse

text: s occurred when the Earth obstructed sunlight falling onto the Moon, and that a

text: solar eclipse

text: occurred when the Moon obstructed sunlight from reaching the Earth. Although others disagreed with his model, Wang Chong accurately described the

text: water cycle

text: of the

text: evaporation

text: of water into clouds.

text: A partial solar eclipse will occur on January 6, 2019. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: will occur on January 6, 2019. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: A partial solar eclipse will occur on April 21, 2069. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: will occur on April 21, 2069. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: Baltimore, in the northern portion of the Bay, experiences a noticeable modulation to form its mixed tidal nature during spring vs. neap tides.  Spring tides, when the sun-earth-moon system forms a line, cause the largest tidal amplitudes during lunar monthly tidal variations.  In contrast, neap tides, when the sun-earth-moon system forms a right angle, are muted, and in a semi-diurnal tidal system (such as that seen at the CBBT site) this can be seen as a lowest intertidal range.

text: A partial solar eclipse occurred on December 4, 1964. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: occurred on December 4, 1964. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: An annular solar eclipse occurred on June 28, 1889. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.

text: An annular

text: solar eclipse

text: occurred on June 28, 1889. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: annulus

text: Tides have an inherent lead or lag, known as the lunitidal interval, that is different at every location, so tidal clocks are set for the time when the local lunar high tide occurs. This is often complicated because the lead or lag varies during the course of the lunar month, as the lunar and solar tides fall into and out of synchronization.  The lunar tide and solar tide are synchronized (ebb and flow at the same time) near the full moon and the new moon. The two tides are unsynchronized near the first and last quarter moon (or "half moon"). Also, in addition to the relative position of the moon and the elliptical pattern of the sun, the tide can be affected to some degree by wind and atmospheric pressure. All of these variables have less impact on the tide at the time of the full moon, so this is usually the best time to set a tide clock.  If the tide clock is mounted on a moving boat, it will need to be reset more frequently. The best time to set the clock is at the new moon or the full moon, which is also when the clock can most reliably indicate the actual combined tide. A simple tide clock will always be least reliable near the quarter moon.

text: Tides have an inherent lead or lag, known as the

text: lunitidal interval

text: , that is different at every location, so tidal clocks are set for the time when the local lunar high tide occurs. This is often complicated because the lead or lag varies during the course of the

text: lunar month

text: , as the lunar and solar tides fall into and out of synchronization.  The lunar tide and solar tide are synchronized (ebb and flow at the same time) near the

text: full moon

text: and the

text: new moon

text: . The two tides are unsynchronized near the first and last

text: quarter moon

text: (or "half moon"). Also, in addition to the relative position of the moon and the elliptical pattern of the sun, the tide can be affected to some degree by wind and atmospheric pressure. All of these variables have less impact on the tide at the time of the full moon, so this is usually the best time to set a tide clock.  If the tide clock is mounted on a moving boat, it will need to be reset more frequently. The best time to set the clock is at the new moon or the full moon, which is also when the clock can most reliably indicate the actual combined tide. A simple tide clock will always be least reliable near the quarter moon.

text: An annular solar eclipse will occur on October 4, 2070.  A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.

text: An annular

text: solar eclipse

text: will occur on October 4, 2070.  A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: annulus

text: If the Moon were in a perfectly circular orbit, a little closer to the Earth, and in the same orbital plane, there would be total solar eclipses every month. However, the Moon's orbit is inclined (tilted) at more than 5 degrees to the Earth's orbit around the Sun (see ecliptic), so its shadow at new moon usually misses Earth. Earth's orbit is called the ecliptic plane as the Moon's orbit must cross this plane in order for an eclipse (both solar as well as lunar) to occur. In addition, the Moon's actual orbit is elliptical, often taking it far enough away from Earth that its apparent size is not large enough to block the Sun totally. The orbital planes cross each other at a line of nodes resulting in at least two, and up to five, solar eclipses occurring each year; no more than two of which can be total eclipses. However, total solar eclipses are rare at any particular location because totality exists only along a narrow path on the Earth's surface traced by the Moon's shadow or umbra.

text: If the Moon were in a perfectly circular orbit, a little closer to the Earth, and in the same

text: orbital plane

text: , there would be total solar eclipses every month. However, the Moon's orbit is

text: inclined

text: (tilted) at more than 5 degrees to the Earth's orbit around the Sun (see

text: ecliptic

text: ), so its shadow at new moon usually misses Earth. Earth's orbit is called the ecliptic plane as the Moon's orbit must cross this plane in order for an eclipse (both solar as well as

text: lunar

text: ) to occur. In addition, the Moon's actual orbit is elliptical, often taking it far enough away from Earth that its

text: apparent size

text: is not large enough to block the Sun totally. The orbital planes cross each other at a

text: line of nodes

text: resulting in at least two, and up to five, solar eclipses occurring each year; no more than two of which can be total eclipses. However, total solar eclipses are rare at any particular location because totality exists only along a narrow path on the Earth's surface traced by the Moon's shadow or

text: umbra

text: An annular solar eclipse occurred on January 26, 1990. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.

text: An

text: annular

text: solar eclipse

text: occurred on January 26,

text: . A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: annulus

text: An annular solar eclipse occurred on December 25, 1954. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.

text: An annular

text: solar eclipse

text: occurred on December 25, 1954. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: annulus

text: Not all deformations originate within the Earth. The gravity of the Moon and Sun cause the Earth's surface at a given point to undulate by tenths of meters over a nearly 12-hour period (see Earth tide).

text: Not all deformations originate within the Earth. The gravity of the Moon and Sun cause the Earth's surface at a given point to undulate by tenths of meters over a nearly 12-hour period (see

text: Earth tide

text: Although Tycho admired Copernicus and was the first to teach his theory in Denmark, he was unable to reconcile Copernican theory with the basic laws of Aristotelian physics, that he considered to be foundational. He was also critical of the observational data that Copernicus built his theory on, which he correctly considered to have a high margin of error. Instead Tycho Brahe proposed a "geo-heliocentric" system in which the Sun and Moon orbited the Earth, while the other planets orbited the Sun. Brahe's system had many of the same observational and computational advantages that Copernicus' system had, and both systems also could accommodate the phases of Venus, although Galilei had yet to discover them. His system provided a safe position for astronomers who were dissatisfied with older models but were reluctant to accept the heliocentrism and the Earth's motion. It gained a considerable following after 1616 when Rome decided officially that the heliocentric model was contrary to both philosophy and Scripture, and could be discussed only as a computational convenience that had no connection to fact. His system also offered a major innovation: while both the purely geocentric model and the heliocentric model as set forth by Copernicus relied on the idea of transparent rotating crystalline spheres to carry the planets in their orbits, Tycho eliminated the spheres entirely.

text: Although Tycho admired Copernicus and was the first to teach his theory in Denmark, he was unable to reconcile Copernican theory with the basic laws of

text: Aristotelian physics

text: , that he considered to be foundational. He was also critical of the observational data that Copernicus built his theory on, which he correctly considered to have a high margin of error. Instead Tycho Brahe proposed a "geo-heliocentric" system in which the

text: Sun

text: and Moon orbited the

text: Earth

text: , while the other planets orbited the

text: Sun

text: . Brahe's system had many of the same observational and computational advantages that Copernicus' system had, and both systems also could accommodate the phases of Venus, although Galilei had yet to discover them. His system provided a safe position for astronomers who were dissatisfied with older models but were reluctant to accept the heliocentrism and the Earth's motion. It gained a considerable following after 1616 when Rome decided officially that the heliocentric model was contrary to both philosophy and Scripture, and could be discussed only as a computational convenience that had no connection to fact. His system also offered a major innovation: while both the purely

text: geocentric model

text: and the heliocentric model as set forth by Copernicus relied on the idea of transparent rotating crystalline spheres to carry the planets in their orbits, Tycho eliminated the spheres entirely.

text: Among the remaining irregular moons, Sao and Laomedeia follow prograde orbits, whereas Halimede, Psamathe and Neso follow retrograde orbits. Given the similarity of their orbits, it was suggested that Neso and Psamathe could have a common origin in the break-up of a larger moon. Psamathe and Neso have the largest orbits of any natural satellites discovered in the Solar system to date. They take 25 years to orbit Neptune at an average of 125 times the distance between Earth and the Moon. Neptune has the largest Hill sphere in the Solar System, owing primarily to its large distance from the Sun; this allows it to retain control of such distant moons. Nevertheless, Jupiter's S/2003 J 2 orbits at the greatest percentage of the primary's Hill radius of all the moons in the Solar System on average, and the Jovian moons in the Carme and Pasiphae groups orbit at a greater percentage of their primary's Hill radius than Psamathe and Neso.

text: Among the remaining irregular moons, Sao and Laomedeia follow prograde orbits, whereas Halimede, Psamathe and Neso follow retrograde orbits. Given the similarity of their orbits, it was suggested that Neso and Psamathe could have a common origin in the break-up of a larger moon. Psamathe and Neso have the largest orbits of any natural satellites discovered in the Solar system to date. They take 25 years to orbit Neptune at an average of 125 times the distance between Earth and the Moon. Neptune has the largest

text: Hill sphere

text: in the Solar System, owing primarily to its large distance from the Sun; this allows it to retain control of such distant moons. Nevertheless, Jupiter's

text: S/2003 J 2

text: orbits at the greatest percentage of the primary's Hill radius of all the moons in the Solar System on average, and the Jovian moons in the

text: Carme

text: and

text: Pasiphae group

text: s orbit at a greater percentage of their primary's Hill radius than Psamathe and Neso.

text: A total solar eclipse occurred on June 20, 1955. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A total solar eclipse occurs when the Moon's apparent diameter is larger than the Sun's, blocking all direct sunlight, turning day into darkness. Totality occurs in a narrow path across Earth's surface, with the partial solar eclipse visible over a surrounding region thousands of kilometres wide.With a maximum duration of 7 minutes 8 seconds, this is the longest solar eclipse of saros series 136, as well as the longest total solar eclipse since the 11th century, and until the 22nd century. Totality beginning over the Indian Ocean and Maldives, crossing southern tip of India and Sri Lanka, moving across Indochina and the Philippines (near the greatest eclipse), towards Solomon Islands ending over Southwestern Pacific Ocean.

text: A total

text: solar eclipse

text: occurred on June 20, 1955. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: is larger than the Sun's, blocking all direct sunlight, turning day into darkness. Totality occurs in a narrow path across Earth's surface, with the partial solar eclipse visible over a surrounding region thousands of kilometres wide.With a maximum duration of 7 minutes 8 seconds, this is the longest solar eclipse of saros series 136, as well as the longest total solar eclipse since the 11th century, and until the

text: 22nd century

text: . Totality beginning over the Indian Ocean and Maldives, crossing southern tip of India and Sri Lanka, moving across Indochina and the Philippines (near the greatest eclipse), towards Solomon Islands ending over Southwestern Pacific Ocean.

text: Mars Global Surveyor imaged the Earth and Moon on May 8, 2003 13:00 UTC, very close to maximum angular elongation from the Sun and at a distance of 0.930 AU from Mars. The apparent magnitudes were given as −2.5 and +0.9. At different times the actual magnitudes will vary considerably depending on distance and the phases of the Earth and Moon.

text: Mars Global Surveyor

text: imaged the Earth and Moon on May 8, 2003 13:00 UTC, very close to maximum angular

text: elongation

text: from the

text: Sun

text: and at a distance of 0.930 AU from Mars. The

text: apparent magnitude

text: s were given as −2.5 and +0.9. At different times the actual magnitudes will vary considerably depending on distance and the phases of the Earth and Moon.

text: From September 1610, Galileo observed that Venus exhibited a full set of phases similar to that of the Moon. The heliocentric model of the solar system developed by Nicolaus Copernicus predicted that all phases would be visible since the orbit of Venus around the Sun would cause its illuminated hemisphere to face the Earth when it was on the opposite side of the Sun and to face away from the Earth when it was on the Earth-side of the Sun. On the other hand, in Ptolemy's geocentric model it was impossible for any of the planets' orbits to intersect the spherical shell carrying the Sun. Traditionally the orbit of Venus was placed entirely on the near side of the Sun, where it could exhibit only crescent and new phases. It was, however, also possible to place it entirely on the far side of the Sun, where it could exhibit only gibbous and full phases. After Galileo's telescopic observations of the crescent, gibbous and full phases of Venus, therefore, this Ptolemaic model became untenable. Thus in the early 17th century as a result of his discovery the great majority of astronomers converted to one of the various geo-heliocentric planetary models, such as the Tychonic, Capellan and Extended Capellan models, each either with or without a daily rotating Earth. These all had the virtue of explaining the phases of Venus without the vice of the 'refutation' of full heliocentrism's prediction of stellar parallax. Galileo's discovery of the phases of Venus was thus arguably his most empirically practically influential contribution to the two-stage transition from full geocentrism to full heliocentrism via geo-heliocentrism.

text: From September 1610, Galileo observed that

text: Venus

text: exhibited a full set of

text: phases

text: similar to that of the

text: Moon

text: . The

text: heliocentric model

text: of the solar system developed by Nicolaus Copernicus predicted that all phases would be visible since the orbit of Venus around the

text: Sun

text: would cause its illuminated hemisphere to face the Earth when it was on the opposite side of the Sun and to face away from the Earth when it was on the Earth-side of the Sun. On the other hand, in

text: Ptolemy's geocentric model

text: Note that this definition of double planet depends on the pair's distance from the Sun. If the Earth–Moon system happened to orbit farther away from the Sun than it does now, then Earth would win the tug of war.  For example, at the orbit of Mars, the Moon's tug-of-war value would be 1.05. Also, several tiny moons discovered since Asimov's proposal would qualify as double planets by this argument. Neptune's small outer moons Neso and Psamathe, for example, have tug-of-war values of 0.42 and 0.44, less than that of Earth's Moon. Yet their masses are tiny compared to Neptune's, with an estimated ratio of 1.5 () and 0.4 ().

text: Note that this definition of double planet depends on the pair's distance from the Sun. If the Earth–Moon system happened to orbit farther away from the Sun than it does now, then Earth would win the tug of war.  For example, at the orbit of Mars, the Moon's tug-of-war value would be 1.05. Also, several tiny moons discovered since Asimov's proposal would qualify as double planets by this argument. Neptune's small outer moons

text: Neso

text: and

text: Psamathe

text: , for example, have tug-of-war values of 0.42 and 0.44, less than that of Earth's Moon. Yet their masses are tiny compared to Neptune's, with an estimated ratio of 1.5 () and 0.4 ().

text: A dial or ring indicating the numbers 1 to 29 or 30 indicates the moon's age: a new moon is 0, waxes and become full around day 15, and then wanes up to 29 or 30. The phase is sometimes shown by a rotating globe or black hemisphere, or a window that reveals part of a wavy black shape beneath.

text: The ancient Mesopotamians believed that a lunar eclipse was when the moon was being attacked by seven demons.  This attack was more than just one on the moon, however, for the Mesopotamians linked what happened in the sky with what happened on the land, and because the king of Mesopotamia represented the land, the seven demons were thought to be also attacking the king.  In order to prevent this attack on the king, the Mesopotamians made someone pretend to be the king so they would be attacked instead of the true king. After the lunar eclipse was over, the substitute king was made to disappear (possibly by poisoning).

text: An annular solar eclipse occurred on September 11, 1969. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.

text: An annular

text: solar eclipse

text: occurred on September 11, 1969. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: annulus

text: An annular solar eclipse will occur on February 27, 2082. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.

text: An annular

text: solar eclipse

text: will occur on February 27, 2082. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: annulus

text: Moreover, the Pluto-Charon system moves in an ellipse around its barycenter with the Sun, as does the Earth-Moon system (and every other planet-moon system or moonless planet in the solar system). In both cases the barycenter is well within the body of the Sun.

text: Moreover, the Pluto-Charon system moves in an ellipse around its barycenter with the

text: Sun

text: , as does the Earth-Moon system (and every other planet-moon system or moonless planet in the solar system). In both cases the barycenter is well within the body of the Sun.

text: From these estimates of the orbital periods of Io and the other Galilean moons, astronomers hoped to generate ephemeris tables predicting the positions of each moon with respect to Jupiter, as well as when each moon would transit the face of Jupiter or be eclipsed by it. One benefit of such predictions, particularly those of satellite eclipses by Jupiter since they were subject to less observer error, would be determining an observer's longitude on Earth with respect to the prime meridian. By observing an eclipse of a Jovian satellite, an observer could determine the current time at the prime meridian by looking up the eclipse in an ephemeris table. Io was particularly useful for this purpose since its shorter orbital period and closer distance to Jupiter made eclipses more frequent and less affected by Jupiter's axial tilt. Knowing the time at the prime meridian and the local time, the observer's longitude could then be calculated. Galileo attempted to produce a table predicting the positions of the Jovian satellites and eclipse timings after he negotiated first with Spain and then with The Netherlands to create a system for measuring longitude at sea using eclipse timings. However, he was never able to generate accurate predictions far enough ahead in time to be useful so he never published his tables. This left the tables published by Simon Marius in Mundus Iovialis and Giovanni Battista Hodierna in 1654 as the most accurate ephemeris tables available, even though they too were unable to predict the moons' positions with sufficient accuracy.

text: From these estimates of the orbital periods of Io and the other Galilean moons, astronomers hoped to generate

text: ephemeris

text: tables predicting the positions of each moon with respect to Jupiter, as well as when each moon would

text: transit

text: the face of Jupiter or be

text: eclipse

text: d by it. One benefit of such predictions, particularly those of satellite eclipses by Jupiter since they were subject to less observer error, would be determining an observer's

text: longitude

text: on Earth with respect to the

text: prime meridian

text: . By observing an eclipse of a Jovian satellite, an observer could determine the current time at the prime meridian by looking up the eclipse in an ephemeris table. Io was particularly useful for this purpose since its shorter orbital period and closer distance to Jupiter made eclipses more frequent and less affected by Jupiter's axial tilt. Knowing the time at the prime meridian and the local time, the observer's longitude could then be calculated. Galileo attempted to produce a table predicting the positions of the Jovian satellites and eclipse timings after he negotiated first with Spain and then with The Netherlands to create a system for measuring longitude at sea using eclipse timings. However, he was never able to generate accurate predictions far enough ahead in time to be useful so he never published his tables. This left the tables published by Simon Marius in Mundus Iovialis and

text: Giovanni Battista Hodierna

text: in 1654 as the most accurate ephemeris tables available, even though they too were unable to predict the moons' positions with sufficient accuracy.

text: Solar eclipses are relatively brief events that can only be viewed in totality along a relatively narrow track. Under the most favorable circumstances, a total solar eclipse can last for 7 minutes, 31 seconds, and can be viewed along a track that is up to 250 km wide. However, the region where a partial eclipse can be observed is much larger. The Moon's umbra will advance eastward at a rate of 1,700 km/h, until it no longer intersects the Earth's surface.

text: If other effects were ignored, tidal acceleration would continue until the rotational period of Earth matched the orbital period of the Moon.  At that time, the Moon would always be overhead of a single fixed place on Earth. Such a situation already exists in the Pluto–Charon system. However, the slowdown of Earth's rotation is not occurring fast enough for the rotation to lengthen to a month before other effects make this irrelevant: About 2.1 billion years from now, the continual increase of the Sun's radiation will likely cause Earth's oceans to vaporize, removing the bulk of the tidal friction and acceleration. Even without this, the slowdown to a month-long day would still not have been completed by 4.5 billion years from now when the Sun will probably evolve into a red giant and likely destroy both Earth and the Moon.

text: If other effects were ignored, tidal acceleration would continue until the rotational period of Earth matched the orbital period of the Moon.  At that time, the Moon would always be overhead of a single fixed place on Earth. Such a situation already exists in the

text: Pluto

text: Charon

text: system. However, the slowdown of Earth's rotation is not occurring fast enough for the rotation to lengthen to a month before other effects make this irrelevant: About 2.1 billion years from now, the continual increase of the Sun's

text: radiation

text: will likely cause Earth's oceans to vaporize, removing the bulk of the tidal friction and acceleration. Even without this, the slowdown to a month-long day would still not have been completed by 4.5 billion years from now when the Sun will probably evolve into a

text: red giant

text: and likely destroy both Earth and the Moon.

text: The clock has its original medieval face. As well as showing the time on a 24-hour dial, it reflects the motion of the Sun and Moon, the phases of the Moon, and the time since the last new Moon. The astronomical dial represents a geocentric or pre-Copernican view of the universe, with the Sun and Moon revolving round a central fixed Earth, like that of the clock at Ottery St Mary. The quarters are chimed by a quarter jack in the form of a small automaton known as Jack Blandifers, who hits two bells with hammers and two with his heels. At the striking of the clock, jousting knights appear above the clock face.

text: The clock has its original medieval face. As well as showing the time on a 24-hour dial, it reflects the motion of the Sun and Moon, the

text: phases of the Moon

text: , and the time since the last new Moon. The astronomical dial represents a

text: geocentric

text: or pre-

text: Copernican

text: view of the universe, with the Sun and Moon revolving round a central fixed Earth, like that of the clock at

text: Ottery St Mary

text: . The quarters are chimed by a

text: quarter jack

text: in the form of a small

text: automaton

text: known as Jack Blandifers, who hits two bells with hammers and two with his heels. At the striking of the clock,

text: jousting

text: knights appear above the clock face.

text: Aside from the Sun, the most prominent objects in Jupiter's sky are the four Galilean moons. Io, the nearest to the planet, would be slightly larger than the full moon in Earth's sky, though less bright, and would be the largest moon in the Solar System as seen from its parent planet. The higher albedo of Europa would not overcome its greater distance from Jupiter, so it would not outshine Io. In fact, the low solar constant at Jupiter's distance (3.7% Earth's) ensures that none of the Galilean satellites would be as bright as the full moon is on Earth; from Io to Callisto their apparent magnitudes would be: −11.2, −9.7, −9.4, and −7.0.

text: Aside from the Sun, the most prominent objects in Jupiter's sky are the four

text: Galilean moon

text: s.

text: Io

text: , the nearest to the planet, would be slightly larger than the full moon in Earth's sky, though less bright, and would be the largest moon in the Solar System as seen from its parent planet. The higher

text: albedo

text: of

text: Europa

text: would not overcome its greater distance from Jupiter, so it would not outshine Io. In fact, the low

text: solar constant

text: at Jupiter's distance (3.7% Earth's) ensures that none of the Galilean satellites would be as bright as the full moon is on Earth; from Io to Callisto their

text: apparent magnitude

text: s would be: −11.2, −9.7, −9.4, and −7.0.

text: A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby obscuring Earth's view of the Sun. Eclipses can be total, annular, or partial.  The zone of a total eclipse where the sky appears dark is often just a few miles wide.  This is known as the path of totality.

text: A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby obscuring Earth's view of the Sun. Eclipses can be

text: total

text: annular

text: , or

text: partial

text: .  The zone of a total eclipse where the sky appears dark is often just a few miles wide.  This is known as the path of totality.

text: Non-western cultures may use a different number of Moon phases, for example traditional Hawaiian culture has a total of 30 different Moon phases (one per day).

text: Non-western cultures may use a different number of Moon phases, for example traditional

text: Hawaii

text: an culture has a total of 30 different Moon phases (one per day).

text: The mean apparent size of the Sun from Jupiter is 372 arcseconds, varying slightly from 381" to 357" between perihelion and aphelion. Unlike the near-coincidence of lunar and solar apparent diameters on Earth, exaggerates the size of all the Galilean satellites in comparison to the Sun; even distant Callisto is over 50 percent larger, and Io is nearly six times larger. This disparity in angular size makes the moons' shadows sharper and more well-defined on Jupiter than the lunar shadow on Earth during total solar eclipses, as it narrows the penumbra for a given distance.

text: The mean

text: apparent size

text: of the Sun from Jupiter is 372

text: arcseconds

text: , varying slightly from 381" to 357" between

text: perihelion

text: and

text: aphelion

text: . Unlike the near-coincidence of lunar and solar apparent diameters on Earth, exaggerates the size of all the Galilean satellites in comparison to the Sun; even distant Callisto is over 50 percent larger, and Io is nearly six times larger. This disparity in angular size makes the moons' shadows sharper and more well-defined on Jupiter than the lunar shadow on Earth during total solar eclipses, as it narrows the

text: penumbra

text: for a given distance.

text: Eclipses may occur when the Earth and the Moon are equal in value weight and mass with the Sun, and the shadow of one body cast by the Sun falls on the other.  So at new moon, when the Moon is in conjunction with the Sun, the Moon may pass in front of the Sun as seen from a narrow region on the surface of the Earth and cause a solar eclipse.  At full moon, when the Moon is in opposition to the Sun, the Moon may pass through the shadow of the Earth, and a lunar eclipse is visible from the night half of the Earth. Conjunction and opposition of the Moon together have a special name: syzygy (from Greek for "junction"), because of the importance of these lunar phases.

text: Eclipse

text: s may occur when the

text: Earth

text: and the

text: Moon

text: are equal in value weight and mass with the

text: Sun

text: , and the shadow of one body cast by the Sun falls on the other.  So at

text: new moon

text: , when the Moon is in

text: conjunction

text: with the Sun, the Moon may pass in front of the Sun as seen from a narrow region on the surface of the Earth and cause a

text: solar eclipse

text: .  At

text: full moon

text: , when the Moon is in

text: opposition

text: to the Sun, the Moon may pass through the shadow of the Earth, and a

text: lunar eclipse

text: is visible from the night half of the Earth. Conjunction and opposition of the Moon together have a special name:

text: syzygy

text: (from

text: Greek

text: for "junction"), because of the importance of these

text: lunar phase

text: s.

text: In 1868, he invited high-ranking European and Siamese officials to accompany him to Wakor village in Prachuap Khiri Khan Province, south of Hua Hin, where the solar eclipse that was to occur on 18 August could be best viewed as a total eclipse. Sir Harry Ord, the British Governor of Straits Settlements from Singapore, was among those who were invited. King Mongkut predicted the solar eclipse, at (in his own words) "East Greenwich longitude 99 degrees 42' and latitude North 11 degrees 39'." King Mongkut's calculations proved accurate. When he made calculations on the Wakor solar eclipse that was to occur, he used the Thai system of measuring time ("mong" and "baht"), but he implemented the Western method of longitude and latitude when he determined where on earth the eclipse would best be viewed. Upon returning from his journey to Wakor, he condemned the court astrologers "for their...stupid statements because of their negligence of his detailed prediction and their inattention to measurement and calculation by modern instruments."

text: In 1868, he invited high-ranking European and Siamese officials to accompany him to Wakor village in

text: Prachuap Khiri Khan Province

text: , south of

text: Hua Hin

text: , where the solar eclipse that was to occur on 18 August could be best viewed as a total eclipse. Sir

text: Harry Ord

text: , the British Governor of

text: Straits Settlements

text: from

text: Singapore

text: , was among those who were invited. King Mongkut predicted the solar eclipse, at (in his own words) "East Greenwich

text: longitude

text: 99 degrees 42' and

text: latitude

text: North 11 degrees 39'." King Mongkut's calculations proved accurate. When he made calculations on the Wakor solar eclipse that was to occur, he used the Thai system of measuring time ("mong" and "baht"), but he implemented the Western method of longitude and latitude when he determined where on earth the eclipse would best be viewed. Upon returning from his journey to Wakor, he condemned the court astrologers "for their...stupid statements because of their negligence of his detailed prediction and their inattention to measurement and calculation by modern instruments."

text: Each saros series starts with a partial eclipse (Sun first enters the end of the node), and each successive saros the path of the Moon is shifted either northward (when near the descending node) or southward (when near the ascending node) due to the fact that the saros is not an exact integer of draconic months (about one hour short). At some point, eclipses are no longer possible and the series terminates (Sun leaves the beginning of the node). Arbitrary dates were established by compilers of eclipse statistics. These extreme dates are 2000 BCE and 3000 CE. Saros series, of course, went on before and will continue after these dates. Since the first eclipse of 2000 BCE was not the first in its saros, it is necessary to extend the saros series numbers backwards beyond 0 to negative numbers to accommodate eclipses occurring in the years following 2000 BCE. The saros -13 is the first saros to appear in these data. For solar eclipses the statistics for the complete saros series within the era between 2000 BCE and 3000 CE are given in this article's references. It takes between 1226 and 1550 years for the members of a saros series to traverse the Earth's surface from north to south (or vice versa). These extremes allow from 69 to 87 eclipses in each series (most series have 71 or 72 eclipses). From 39 to 59 (mostly about 43) eclipses in a given series will be central (that is, total, annular, or hybrid annular-total). At any given time, approximately 40 different saros series will be in progress.

text: In the second episode, Brian considers the nature of motion and explores how the celestial clockwork of the Sun and the Earth-Moon system account for a wide range of natural phenomena observed on Earth, from tropical cyclones and tidal waves to sunrises and seasonal changes. The episode begins in Warton Aerodrome in England with Brian taking to the air in a Eurofighter Typhoon, in an attempt to "beat the Earth's rotation and reverse the passage of the day." In Tacloban, Philippines, Brian narrates how the Coriolis force (caused by the Earth's spin) and the warmth of the tropical waters conspire to give rise to some of the deadliest storms in the world, like Typhoon Haiyan that hit the country in 2013.  Then, in Amapá, Brazil, he relates how the complex gravitational interaction between the Sun and the Moon are not just responsive for the gentle and familiar rise and fall of tides, but also for monstrous tidal bores, like the Pororoca on the waters of the Amazon. Towards the end, he lays out photographs from different points in his life – as a baby, getting married, with his own son, etc. – and concludes by stating that "if Einstein is right, then the past events we remember and our unforeseen future are all out there, somewhere in spacetime."

text: In the second episode, Brian considers the nature of motion and explores how the celestial clockwork of the Sun and the Earth-Moon system account for a wide range of natural phenomena observed on Earth, from

text: tropical cyclones

text: and

text: tidal waves

text: to

text: sunrises

text: and

text: seasonal changes

text: . The episode begins in

text: Warton Aerodrome

text: in

text: England

text: with Brian taking to the air in a

text: Eurofighter Typhoon

text: , in an attempt to "beat the Earth's rotation and reverse the passage of the day." In

text: Tacloban

text: Philippines

text: , Brian narrates how the

text: Coriolis force

text: (caused by the Earth's spin) and the warmth of the tropical waters conspire to give rise to some of the deadliest storms in the world, like

text: Typhoon Haiyan

text: that hit the country in 2013.  Then, in

text: Amapá

text: Brazil

text: , he relates how the complex gravitational interaction between the Sun and the Moon are not just responsive for the gentle and familiar rise and fall of tides, but also for monstrous tidal bores, like the

text: Pororoca

text: on the waters of the

text: Amazon

text: . Towards the end, he lays out photographs from different points in his life – as a baby, getting married, with his own son, etc. – and concludes by stating that "if

text: Einstein

text: is right, then the past events we remember and our unforeseen future are all out there, somewhere in

text: spacetime

text: A tide clock is a specially designed clock that keeps track of the Moon's apparent motion around the Earth. Along many coastlines the Moon contributes the major part (67 percent) of the combined lunar and solar tides. The exact interval between tides is influenced by the position of the Moon and Sun relative to the Earth as well as the specific location on earth where the tide is being measured. Owing to the Moon's orbital progress, it takes a particular point on the Earth (on average) 24 hours, 50.5 minutes to rotate under the Moon, so the time between high lunar tides fluctuates between 12 and 13 hours. A tide clock is divided into two six-hour-long tidal periods that shows the average length of time between high and low tide in a semi-diurnal tide region such as most areas of the Atlantic Ocean.  Therefore, compared with the actual time between the high lunar tides, tide clocks gain approximately 15 minutes per month and must be reset periodically.

text: A tide clock is a specially designed

text: clock

text: that keeps track of the Moon's apparent motion around the

text: Earth

text: . Along many coastlines the Moon contributes the major part (67 percent) of the combined lunar and solar

text: tide

text: s. The exact interval between tides is influenced by the position of the Moon and Sun relative to the Earth as well as the specific location on earth where the tide is being measured. Owing to the Moon's orbital progress, it takes a particular point on the Earth (on average) 24 hours, 50.5 minutes to rotate under the Moon, so the time between high lunar tides fluctuates between 12 and 13 hours. A tide clock is divided into two six-hour-long tidal periods that shows the average length of time between high and low tide in a

text: semi-diurnal

text: tide region such as most areas of the Atlantic Ocean.  Therefore, compared with the actual time between the high lunar tides, tide clocks gain approximately 15 minutes per month and must be reset periodically.

text: An annular solar eclipse will occur on February 17, 2026. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.

text: An annular

text: solar eclipse

text: will occur on February 17, 2026. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: annulus

text: Wikipedia contains the following lists of lunar eclipses:

text: One such claim is based on an interpretation of the passage in the Quran which states: "Have not those who disbelieve known that the heavens and the earth were of one piece, then We parted them and we made every living thing of water? Will they not then believe?" Muslims claim that the first part of the verse is referring to the Big Bang and the second part of the verse refers to the fact that all living things are made of water since and water being a necessary component for life. The notion of "separation of heaven and earth" is common in several other creation stories, some of which preceded the Quran, such as Egyptian mythology, Sumerian mythology, Greek mythology, Hindu mythology, Japanese mythology and Maori mythology. Muslims also believe that the Quran also refers to the protective properties of the atmosphere when it says, "We made the sky a preserved and protected roof yet still they turn away from Our Signs." However, another verse of the Quran says that god withholds the sky from falling on the earth, "Seest thou not that God has made subject to you (men) all that is on the earth, and the ships that sail through the sea by His Command? He withholds the sky from falling on the earth except by His leave: for God is Most Kind and Most Merciful to man." Muslims also believe the Quran mentions the rotation and orbit of the Sun and the Moon when one of its verse states, "It is He who created the night and the day, and the sun, and the moon; each of them swim along in its rounded course." However, others claim that this Quran verse describes the sun and the moon in parallel orbits, as Quran verse 36:40 says, "It is not allowable for the sun to reach the moon, nor does the night overtake the day, but each, in an orbit, is swimming." However, understanding of the rotation and orbit of the Sun and the Moon, called Geocentrism, existed long before the Quran was written.

text: One such claim is based on an interpretation of the passage in the Quran which states: "Have not those who disbelieve known that the heavens and the earth were of one piece, then We parted them and we made every living thing of water? Will they not then believe?" Muslims claim that the first part of the verse is referring to the

text: Big Bang

text: and the second part of the verse refers to the fact that all living things are made of water since and water being a necessary component for life. The notion of "separation of heaven and earth" is common in several other creation stories, some of which preceded the Quran, such as

text: Egyptian mythology

text: Sumerian mythology

text: Greek mythology

text: Hindu mythology

text: Japanese mythology

text: and

text: Maori mythology

text: . Muslims also believe that the Quran also refers to the protective properties of the

text: atmosphere

text: when it says, "We made the sky a preserved and protected roof yet still they turn away from Our Signs." However, another verse of the Quran says that god withholds the sky from falling on the earth, "Seest thou not that God has made subject to you (men) all that is on the earth, and the ships that sail through the sea by His Command? He withholds the sky from falling on the earth except by His leave: for God is Most Kind and Most Merciful to man." Muslims also believe the Quran mentions the rotation and orbit of the

text: Sun

text: and the

text: Moon

text: when one of its verse states, "It is He who created the night and the day, and the sun, and the moon; each of them swim along in its rounded course." However, others claim that this Quran verse describes the sun and the moon in parallel orbits, as Quran verse 36:40 says, "It is not allowable for the sun to reach the moon, nor does the night overtake the day, but each, in an orbit, is swimming." However, understanding of the rotation and orbit of the

text: Sun

text: and the

text: Moon

text: , called

text: Geocentrism

text: , existed long before the Quran was written.

text: One way to determine the lunar parallax from one location is by using a lunar eclipse. A full shadow of the Earth on the Moon has an apparent radius of curvature equal to the difference between the apparent radii of the Earth and the Sun as seen from the Moon. This radius can be seen to be equal to 0.75 degree, from which (with the solar apparent radius 0.25 degree) we get an Earth apparent radius of 1 degree. This yields for the Earth–Moon distance 60.27 Earth radii or  This procedure was first used by Aristarchus of Samos and Hipparchus, and later found its way into the work of Ptolemy. The diagram at right shows how daily lunar parallax arises on the geocentric and geostatic planetary model in which the Earth is at the centre of the planetary system and does not rotate. It also illustrates the important point that parallax need not be caused by any motion of the observer, contrary to some definitions of parallax that say it is, but may arise purely from motion of the observed.

text: One way to determine the lunar parallax from one location is by using a lunar eclipse. A full shadow of the Earth on the Moon has an apparent radius of curvature equal to the difference between the apparent radii of the Earth and the Sun as seen from the Moon. This radius can be seen to be equal to 0.75 degree, from which (with the solar apparent radius 0.25 degree) we get an Earth apparent radius of 1 degree. This yields for the Earth–Moon distance 60.27 Earth radii or  This procedure was first used by

text: Aristarchus of Samos

text: and

text: Hipparchus

text: , and later found its way into the work of

text: Ptolemy

text: . The diagram at right shows how daily lunar parallax arises on the geocentric and geostatic planetary model in which the Earth is at the centre of the planetary system and does not rotate. It also illustrates the important point that parallax need not be caused by any motion of the observer, contrary to some definitions of parallax that say it is, but may arise purely from motion of the observed.

text: An annular solar eclipse occurred on January 4, 1973. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.

text: An annular

text: solar eclipse

text: occurred on January 4, 1973. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: annulus

text: A lunar eclipse occurs when the Moon passes directly behind the Earth into its umbra (shadow). This can occur only when the sun, Earth, and moon are aligned (in "syzygy") exactly, or very closely so, with the Earth in the middle. Hence, a lunar eclipse can occur only the night of a full moon. The type and length of an eclipse depend upon the Moon's location relative to its orbital nodes.

text: A lunar eclipse occurs when the

text: Moon

text: passes directly behind the

text: Earth

text: into its

text: umbra

text: (shadow). This can occur only when the sun, Earth, and moon are aligned (in "

text: syzygy

text: ") exactly, or very closely so, with the Earth in the middle. Hence, a lunar eclipse can occur only the night of a

text: full moon

text: . The type and length of an

text: eclipse

text: depend upon the Moon's location relative to its

text: orbital node

text: s.

text: A lunar eclipse occurs when the Moon passes directly behind the Earth into its umbra (shadow). This can occur only when the Sun, Earth, and Moon are aligned (in "syzygy") exactly, or very closely so, with the Earth in the middle. Hence, a lunar eclipse can only occur the night of a full moon. The type and length of an eclipse depend upon the Moon's location relative to its orbital nodes.

text: A

text: lunar eclipse

text: occurs when the

text: Moon

text: passes directly behind the

text: Earth

text: into its

text: umbra

text: (shadow). This can occur only when the Sun, Earth, and Moon are aligned (in "

text: syzygy

text: ") exactly, or very closely so, with the Earth in the middle. Hence, a lunar eclipse can only occur the night of a

text: full moon

text: . The type and length of an

text: eclipse

text: orbital node

text: s.

text: As seen from the Earth, a solar eclipse is a type of eclipse that occurs when the Moon passes between the Sun and Earth, and the Moon fully or partially blocks ("occults") the Sun. This can happen only at new moon when the Sun and the Moon are in conjunction as seen from Earth in an alignment referred to as syzygy. In a total eclipse, the disk of the Sun is fully obscured by the Moon. In partial and annular eclipses, only part of the Sun is obscured.

text: As seen from the

text: Earth

text: , a solar eclipse is a type of

text: eclipse

text: that occurs when the

text: Moon

text: passes between the

text: Sun

text: and Earth, and the Moon fully or partially blocks ("

text: occults

text: ") the Sun. This can happen only at

text: new moon

text: when the Sun and the Moon are in

text: conjunction

text: as seen from Earth in an alignment referred to as

text: syzygy

text: . In a total

text: eclipse

text: , the disk of the Sun is fully obscured by the Moon. In

text: partial and annular eclipses

text: , only part of the Sun is obscured.

text: In 1868 Janssen discovered how to observe solar prominences without an eclipse. While observing the solar eclipse of August 18, 1868, at Guntur, Madras State (now in Andhra Pradesh), British India, he noticed bright lines in the spectrum of the chromosphere, showing that the chromosphere is gaseous.  Present in the spectrum of the Sun, though not immediately noticed or commented upon, was a bright yellow line later measured to have a wavelength of 587.49 nm. This was the first observation of this particular spectral line, and one possible source for it was an element not yet discovered on the earth.  From the brightness of the spectral lines, Janssen realized that the chromospheric spectrum could be observed even without an eclipse, and he proceeded to do so.

text: In 1868 Janssen discovered how to observe

text: solar prominence

text: s without an

text: eclipse

text: . While observing the

text: solar eclipse of August 18, 1868

text: , at

text: Guntur

text: Madras State

text: (now in

text: Andhra Pradesh

text: ), British India, he noticed bright lines in the spectrum of the chromosphere, showing that the chromosphere is gaseous.  Present in the

text: spectrum

text: of the Sun, though not immediately noticed or commented upon, was a bright yellow line later measured to have a

text: wavelength

text: of 587.49 nm. This was the first observation of this particular spectral line, and one possible source for it was an element not yet discovered on the earth.  From the brightness of the spectral lines, Janssen realized that the chromospheric spectrum could be observed even without an eclipse, and he proceeded to do so.

text: California Grunion fish have an unusual mating and spawning ritual during the spring and summer months.  The egg laying takes place on four consecutive nights, beginning on the nights of the full and new Moons, when tides are highest.  However, this is a well understood reproductive strategy that is more related to tides than it is to lunar phase.  It happens to correlate with the lunar phase because tides are highest when the Sun, Earth, and Moon are aligned, i.e., at new Moon or full Moon.

text: California Grunion

text: fish have an unusual mating and spawning ritual during the spring and summer months.  The egg laying takes place on four consecutive nights, beginning on the nights of the full and new Moons, when tides are highest.  However, this is a well understood reproductive strategy that is more related to tides than it is to lunar phase.  It happens to correlate with the lunar phase because tides are highest when the Sun, Earth, and Moon are aligned, i.e., at new Moon or full Moon.

text: It might be expected that once every month, when the Moon passes between Earth and the Sun during a new moon, its shadow would fall on Earth causing a solar eclipse, but this does not happen every month. Nor is it true that during every full moon, the Earth's shadow falls on the Moon, causing a lunar eclipse. Solar and lunar eclipses are not observed every month because the plane of the Moon's orbit around the Earth is tilted by about five degrees with respect to the plane of Earth's orbit around the Sun (the plane of the ecliptic). Thus, when new and full moons occur, the Moon usually lies to the north or south of a direct line through the Earth and Sun.  Although an eclipse can only occur when the Moon is either new (solar) or full (lunar), it must also be positioned very near the intersection of Earth's orbit plane about the Sun and the Moon's orbit plane about the Earth (that is, at one of its nodes).  This happens about twice per year, and so there are between four and seven eclipses in a calendar year. Most of these events are quite insignificant; major eclipses of the Moon or Sun are less frequent.

text: It might be expected that once every month, when the Moon passes between Earth and the Sun during a new moon, its shadow would fall on Earth causing a

text: solar eclipse

text: , but this does not happen every month. Nor is it true that during every full moon, the Earth's shadow falls on the Moon, causing a

text: lunar eclipse

text: . Solar and lunar eclipses are not observed every month because the plane of the Moon's orbit around the Earth is tilted by about five degrees with respect to the plane of Earth's orbit around the Sun (the

text: plane of the ecliptic

text: ). Thus, when new and full moons occur, the Moon usually lies to the north or south of a direct line through the Earth and Sun.  Although an

text: eclipse

text: can only occur when the Moon is either new (solar) or full (lunar), it must also be positioned very near the intersection of Earth's orbit plane about the Sun and the Moon's orbit plane about the Earth (that is, at one of its

text: node

text: s).  This happens about twice per year, and so there are between four and seven eclipses in a calendar year. Most of these events are quite insignificant; major eclipses of the Moon or Sun are less frequent.

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: In astronomy, solar eclipses on the Moon are caused when its mother planet (Earth) passes in front of the Sun, blocking its light. Viewers on Earth will see a lunar eclipse.

text: In

text: astronomy

text: solar eclipses

text: on the

text: Moon

text: are caused when its mother planet (

text: Earth

text: ) passes in front of the

text: Sun

text: , blocking its light. Viewers on Earth will see a

text: lunar eclipse

text: Theon of Smyrna wrote that according to Hipparchus, the Sun is 1,880 times the size of the Earth, and the Earth twenty-seven times the size of the Moon; apparently this refers to volumes, not diameters. From the geometry of book 2 it follows that the Sun is at 2,550 Earth radii, and the mean distance of the Moon is 60½ radii. Similarly, Cleomedes quotes Hipparchus for the sizes of the Sun and Earth as 1050:1; this leads to a mean lunar distance of 61 radii. Apparently Hipparchus later refined his computations, and derived accurate single values that he could use for predictions of solar eclipses.

text: Theon of Smyrna

text: wrote that according to Hipparchus, the Sun is 1,880 times the size of the Earth, and the Earth twenty-seven times the size of the Moon; apparently this refers to

text: volume

text: s, not

text: diameter

text: s. From the geometry of book 2 it follows that the Sun is at 2,550 Earth radii, and the mean distance of the Moon is 60½ radii. Similarly,

text: Cleomedes

text: quotes Hipparchus for the sizes of the Sun and Earth as 1050:1; this leads to a mean lunar distance of 61 radii. Apparently Hipparchus later refined his computations, and derived accurate single values that he could use for predictions of solar eclipses.

text: The triangular points ( and ) are stable equilibria, provided that the ratio of  is greater than 24.96. This is the case for the Sun–Earth system, the Sun–Jupiter system, and, by a smaller margin, the Earth–Moon system. When a body at these points is perturbed, it moves away from the point, but the factor opposite of that which is increased or decreased by the perturbation (either gravity or angular momentum-induced speed) will also increase or decrease, bending the object's path into a stable, kidney-bean-shaped orbit around the point (as seen in the corotating frame of reference).

text: The triangular points ( and ) are stable equilibria, provided that the ratio of  is greater than 24.96. This is the case for the Sun–Earth system, the Sun–Jupiter system, and, by a

text: smaller margin

text: , the Earth–Moon system. When a body at these points is perturbed, it moves away from the point, but the factor opposite of that which is increased or decreased by the perturbation (either gravity or angular momentum-induced speed) will also increase or decrease, bending the object's path into a stable,

text: kidney-bean

text: -shaped orbit around the point (as seen in the corotating frame of reference).

text: An annular solar eclipse occurred on November 22, 1919. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.

text: An annular

text: solar eclipse

text: occurred on November 22, 1919. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: annulus

text: The Earth subtends an angle of about two degrees, when seen from the Moon. This means that an observer on Earth who sees the Moon when it is close to the eastern horizon sees it from an angle that is about two degrees different from the line of sight of an observer who sees the Moon on the western horizon. The Moon moves about 12 degrees around its orbit per day, so, if these observers were stationary, they would see the phases of the Moon at times that differ by about one-sixth of a day, or four hours. But in reality the observers are on the surface of the rotating Earth, so someone who sees the Moon on the eastern horizon at one moment sees it on the western horizon about 12 hours later. This adds an oscillation to the apparent progression of the lunar phases. They appear to occur more slowly when the Moon is high in the sky than when it is below the horizon. The Moon appears to move jerkily, and the phases do the same. The amplitude of this oscillation is never more than about four hours, which is a small fraction of a month. It does not have any obvious effect on the appearance of the Moon. However, it does affect accurate calculations of the times of lunar phases.

text: An annular solar eclipse occurred on January 15–16, 1991. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.It was visible over Australia as a partial solar eclipse at sunrise on January 16.

text: An annular

text: solar eclipse

text: occurred on January 15–16, 1991. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: annulus

text: (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.It was visible over

text: Australia

text: as a partial solar eclipse at sunrise on January 16.

text: A lunar day is the period of time it takes for the Earth's Moon to complete one full rotation on its axis with respect to the Sun. Equivalently, it is the time it takes the Moon to make one complete orbit around the Earth and come back to the same phase. It is marked from a new moon to the next new moon.

text: A lunar day is the period of time it takes for the

text: Earth's Moon

text: to complete one full rotation on its

text: axis

text: with respect to the

text: Sun

text: . Equivalently, it is the time it takes the Moon to make one complete

text: orbit

text: around the

text: Earth

text: and come back to the same

text: phase

text: . It is marked from a

text: new moon

text: to the next new moon.

text: An eclipse season is the only time during which the Sun (from the perspective of the Earth) is close enough to one of the Moon's nodes to allow for an eclipse to occur. During the season, whenever there is a full moon a lunar eclipse will occur and whenever there is a new moon a solar eclipse will occur. If the Sun is close enough to a node, then a total eclipse will occur. Each season lasts from 31 to 37 days, recurring about every 6 months. At least two (one solar and one lunar, in any order), and at most three eclipses (solar, lunar, then solar again, or vice versa), will occur during every eclipse season. This is because it is about 15 days (a fortnight) between full moon and new moon and vice versa. If there is an eclipse at the very beginning of the season, then there is enough time (30 days) for two more eclipses.

text: An eclipse season is the only time during which the Sun (from the perspective of the Earth) is close enough to one of the

text: Moon's nodes

text: to allow for an

text: eclipse

text: to occur. During the season, whenever there is a full moon a

text: lunar

text: eclipse will occur and whenever there is a new moon a

text: solar eclipse

text: will occur. If the Sun is close enough to a node, then a

text: total eclipse

text: will occur. Each season lasts from 31 to 37 days, recurring about every 6 months. At least two (one solar and one lunar, in any order), and at most three eclipses (solar, lunar, then solar again, or vice versa), will occur during every eclipse season. This is because it is about 15 days (a

text: fortnight

text: ) between full moon and new moon and vice versa. If there is an eclipse at the very beginning of the season, then there is enough time (30 days) for two more eclipses.

text: Like the Moon and Venus, Mercury exhibits phases as seen from Earth. It is "new" at inferior conjunction and "full" at superior conjunction. The planet is rendered invisible from Earth on both of these occasions because of its being obscured by the Sun, except its new phase during a transit.

text: Like the Moon and Venus, Mercury exhibits

text: phases

text: as seen from Earth. It is "new" at

text: inferior conjunction

text: and "full" at

text: superior conjunction

text: . The planet is rendered invisible from Earth on both of these occasions because of its being obscured by the Sun, except its new phase during a

text: transit

text: This is a list of solar eclipses in the 14th century BC. During the period 1400 to 1301 BC there were 234 solar eclipses of which 76 were partial, 84 were annular (one non-central), 68 were total, and 6 were hybrids. The greatest number of eclipses in one year was four, occurring in 6 different years: 1372 BC, 1354 BC, 1336 BC, 1332 BC, 1318 BC, and 1307 BC.

text: This is a list of solar eclipses in the 14th century BC. During the period 1400 to 1301 BC there were 234 solar eclipses of which 76 were partial, 84 were annular (one

text: non-central

text: ), 68 were total, and 6 were hybrids. The greatest number of eclipses in one year was four, occurring in 6 different years: 1372 BC, 1354 BC, 1336 BC, 1332 BC, 1318 BC, and 1307 BC.

text: An annual solar eclipse occurred on November 1, 1929. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.

text: An annual

text: solar eclipse

text: occurred on November 1, 1929. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: annulus

text: An annular solar eclipse will occur on July 1, 2057. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.

text: An annular

text: solar eclipse

text: will occur on July 1, 2057. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: annulus

text: Gravitational Tides are caused by changes in the relative location of the Earth, sun, and moon, whose orbits are perturbed slightly by Jupiter.  Newton's law of universal gravitation states that the gravitational force between a mass at a reference point on the surface of the Earth and another object such as the Moon is inversely proportional to the square of the distance between them.  The declination of the Moon relative to the Earth means that as the Moon orbits the Earth during half the lunar cycle the Moon is closer to the Northern Hemisphere and during the other half the Moon is closer to the Southern Hemisphere.  This periodic shift in distance gives rise to the lunar fortnightly tidal constituent.  The ellipticity of the lunar orbit gives rise to a lunar monthly tidal constituent.  Because of the nonlinear dependence of the force on distance additional tidal constituents exist with frequencies which are the sum and differences of these fundamental frequencies.  Additional fundamental frequencies are introduced by the motion of the Sun and Jupiter, thus tidal constituents exist at all of these frequencies as well as all of the sums and differences of these frequencies, etc.  The mathematical description of the tidal forces is greatly simplified by expressing the forces in terms of gravitational potentials.  Because of the fact that the Earth is approximately a sphere and the orbits are approximately circular it also turns out to be very convenient to describe these gravitational potentials in spherical coordinates using spherical harmonic expansions.

text: Gravitational

text: Tides

text: are caused by changes in the relative location of the Earth, sun, and moon, whose orbits are perturbed slightly by Jupiter.

text: Newton's law of universal gravitation

text: states that the gravitational force between a mass at a reference point on the surface of the Earth and another object such as the Moon is inversely proportional to the square of the distance between them.  The

text: declination

text: The Islamic calendar is not to be confused with a lunar calendar that is based on astronomical calculations. The latter is based on a year of 12 months adding up to 354.37 days. Each lunar month begins at the time of the monthly "conjunction", when the Moon is located on a straight line between the Earth and the Sun. The month is defined as the average duration of a revolution of the Moon around the Earth (29.53 days). By convention, months of 30 days and 29 days succeed each other, adding up over two successive months to 59 full days. This leaves only a small monthly variation of 44 minutes to account for, which adds up to a total of 24 hours (i.e., the equivalent of one full day) in 2.73 years. To settle accounts, it is sufficient to add one day every three years to the lunar calendar, in the same way that one adds one day to the Gregorian calendar every four years. The technical details of the adjustment are described in Tabular Islamic calendar.

text: The Islamic calendar is not to be confused with a

text: lunar calendar

text: that is based on astronomical calculations. The latter is based on a year of 12 months adding up to 354.37 days. Each lunar month begins at the time of the monthly "conjunction", when the Moon is located on a straight line between the Earth and the Sun. The month is defined as the average duration of a revolution of the Moon around the Earth (29.53 days). By convention, months of 30 days and 29 days succeed each other, adding up over two successive months to 59 full days. This leaves only a small monthly variation of 44 minutes to account for, which adds up to a total of 24 hours (i.e., the equivalent of one full day) in 2.73 years. To settle accounts, it is sufficient to add one day every three years to the lunar calendar, in the same way that one adds one day to the Gregorian calendar every four years. The technical details of the adjustment are described in

text: Tabular Islamic calendar

text: In 1610, Galileo observed that Venus had a full set of phases, similar to the phases of the moon we can observe from Earth. This was explainable by the Copernican system which said that all phases of Venus would be visible due to the nature of its orbit around the Sun, unlike the Ptolemaic system which stated only some of Venus’s phases would be visible. Due to Galileo’s observations of Venus, Ptolemy’s system became highly suspect and the majority of leading astronomers subsequently converted to various heliocentric models, making his discovery one of the most influential in the transition from geocentrism to heliocentrism.

text: In 1610, Galileo observed that

text: Venus

text: had a full set of phases, similar to the phases of the moon we can observe from Earth. This was explainable by the Copernican system which said that all phases of Venus would be visible due to the nature of its

text: orbit

text: around the Sun, unlike the Ptolemaic system which stated only some of Venus’s phases would be visible. Due to Galileo’s observations of Venus, Ptolemy’s system became highly suspect and the majority of leading astronomers subsequently converted to various heliocentric models, making his discovery one of the most influential in the transition from geocentrism to heliocentrism.

text: Knowledge of the spherical shape of the Earth was received in scholarship of Late Antiquity as a matter of course, in both Neoplatonism and Early Christianity. Calcidius's fourth-century Latin commentary on and translation of Plato's Timaeus, which was one of the few examples of Greek scientific thought that was known in the Early Middle Ages, discussed Hipparchus's use of the geometrical circumstances of eclipses to compute the relative diameters of the Sun, Earth, and Moon.

text: Knowledge of the spherical shape of the Earth was received in scholarship of

text: Late Antiquity

text: as a matter of course, in both

text: Neoplatonism

text: and

text: Early Christianity

text: Calcidius

text: 's fourth-century

text: Latin

text: commentary on and translation of Plato's Timaeus, which was one of the few examples of Greek scientific thought that was known in the Early Middle Ages, discussed

text: Hipparchus

text: 's use of the geometrical circumstances of eclipses to compute the

text: relative diameters

text: of the Sun, Earth, and Moon.

text: A partial solar eclipse occurred on April 6, 1913. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: occurred on April 6, 1913. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: The Sun's gravitational effect on the Moon is more than twice that of Earth's on the Moon; consequently, the Moon's trajectory is always convex (as seen when looking Sunward at the entire Sun–Earth–Moon system from a great distance outside Earth–Moon solar orbit), and is nowhere concave (from the same perspective) or looped. That is, the region enclosed by the Moon's orbit of the Sun is a convex set.

text: The Sun's gravitational effect on the Moon is more than twice that of Earth's on the Moon; consequently, the Moon's trajectory is always convex (as seen when looking Sunward at the entire Sun–Earth–Moon system from a great distance outside Earth–Moon solar orbit), and is nowhere concave (from the same perspective) or looped. That is, the region enclosed by the Moon's orbit of the Sun is a

text: convex set

text: An annular solar eclipse will occur on July 24, 2074. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.

text: An annular

text: solar eclipse

text: will occur on July 24, 2074. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: annulus

text: Shown here is Newton's diagram from the first (1687) Latin edition of the Principia (Book 3, Proposition 25, at p. 434). Here he introduced his analysis of perturbing accelerations on the Moon in the Sun-Earth-Moon system. Q represents the Sun, S the Earth, and P the Moon.

text: A partial solar eclipse occurred on March 7, 1989. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: occurred on March 7, 1989. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: A total solar eclipse will occur on December 26, 2038. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A total solar eclipse occurs when the Moon's apparent diameter is larger than the Sun's, blocking all direct sunlight, turning day into darkness. Totality occurs in a narrow path across Earth's surface, with the partial solar eclipse visible over a surrounding region thousands of kilometres wide.

text: A total

text: solar eclipse

text: will occur on December 26, 2038. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: Gravity is the weakest of the four fundamental interactions of nature. The gravitational attraction is approximately 10 times weaker than the strong force, 10 times weaker than the electromagnetic force and 10 times weaker than the weak force. As a consequence, gravity has a negligible influence on the behavior of subatomic particles, and plays no role in determining the internal properties of everyday matter (but see quantum gravity). On the other hand, gravity is the dominant interaction at the macroscopic scale, and is the cause of the formation, shape and trajectory (orbit) of astronomical bodies. It is responsible for various phenomena observed on Earth and throughout the Universe; for example, it causes the Earth and the other planets to orbit the Sun, the Moon to orbit the Earth, the formation of tides, the formation and evolution of the Solar System, stars and galaxies.

text: Gravity is the weakest of the four

text: fundamental interaction

text: s of nature. The gravitational attraction is approximately 10 times weaker than the

text: strong force

text: , 10 times weaker than the

text: electromagnetic force

text: and 10 times weaker than the

text: weak force

text: . As a consequence, gravity has a negligible influence on the behavior of subatomic particles, and plays no role in determining the internal properties of everyday matter (but see

text: quantum gravity

text: ). On the other hand, gravity is the dominant interaction at the

text: macroscopic scale

text: , and is the cause of the formation, shape and

text: trajectory

text: orbit

text: ) of astronomical bodies. It is responsible for various phenomena observed on Earth and throughout the Universe; for example, it causes the Earth and the other planets to orbit the Sun, the

text: Moon

text: to orbit the Earth, the formation of

text: tide

text: s, the

text: formation and evolution of the Solar System

text: stars

text: and

text: galaxies

text: An annular solar eclipse occurred on March 18, 1969. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.

text: An

text: annular solar eclipse

text: occurred on March 18, 1969. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: annulus

text: An orrery should properly include the Sun, the Earth and the Moon (plus optionally other planets). A model that only includes the Earth, the Moon and the Sun is called a tellurion or tellurium, and one which only includes the Earth and the Moon is a lunarium. A jovilabe is a model of Jupiter and its moons.

text: An orrery should properly include the Sun, the Earth and the Moon (plus optionally other planets). A model that only includes the Earth, the Moon and the Sun is called a

text: tellurion

text: or tellurium, and one which only includes the Earth and the Moon is a

text: lunarium

text: . A

text: jovilabe

text: is a model of

text: Jupiter

text: and its moons.

text: Observations over the decades have shown that its colour slightly changes and it exhibits variation in light that indicate the star is actually an ellipsoidal binary with a period of seven days. The system is more luminous than expected, given the spectrum and distance of the primary star, indicating that the companion star must be contributing a good proportion of its light. Stellar evolution modelling has concluded that the system likely begun as a binary system, with one star about double the Sun's mass and the other roughly equivalent to that of the sun. The larger star eventually aged and expanded as it used up its core hydrogen, and begun having its mass siphoned off by the smaller star; the system is likely to have been an Algol-type eclipsing binary at this stage. This star appears now to be an aged star composed mostly of helium with very little hydrogen and with a mass of 0.2 solar masses and around 37 times the luminosity of the Sun and surface temperature of 7000 K, while the once-smaller star is the Delta Scuti variable that is now around two solar masses. Around 0.8 solar masses has been lost from the system over time.

text: Observations over the decades have shown that its colour slightly changes and it exhibits variation in light that indicate the star is actually an ellipsoidal binary with a period of seven days. The system is more luminous than expected, given the spectrum and distance of the primary star, indicating that the companion star must be contributing a good proportion of its light. Stellar evolution modelling has concluded that the system likely begun as a

text: binary system

text: , with one star about double the

text: Sun's mass

text: and the other roughly equivalent to that of the sun. The larger star eventually aged and expanded as it used up its core hydrogen, and begun having its mass siphoned off by the smaller star; the system is likely to have been an

text: Algol-type eclipsing binary

text: at this stage. This star appears now to be an aged star composed mostly of helium with very little hydrogen and with a mass of 0.2

text: solar mass

text: es and around 37 times the luminosity of the

text: Sun

text: and surface temperature of 7000 K, while the once-smaller star is the Delta Scuti variable that is now around two solar masses. Around 0.8 solar masses has been lost from the system over time.

text: Lunar eclipses occur when the Moon passes through the Earth's shadow. This happens only during a full moon, when the Moon is on the far side of the Earth from the Sun. Unlike a solar eclipse, an eclipse of the Moon can be observed from nearly an entire hemisphere. For this reason it is much more common to observe a lunar eclipse from a given location. A lunar eclipse lasts longer, taking several hours to complete, with totality itself usually averaging anywhere from about 30 minutes to over an hour.

text: Lunar eclipses occur when the Moon passes through the Earth's shadow. This happens only during a

text: full moon

text: , when the Moon is on the far side of the Earth from the Sun. Unlike a solar eclipse, an eclipse of the Moon can be observed from nearly an entire hemisphere. For this reason it is much more common to observe a lunar eclipse from a given location. A lunar eclipse lasts longer, taking several hours to complete, with totality itself usually averaging anywhere from about 30 minutes to over an hour.

text: Most places experience two high tides each day, occurring at intervals of about 12 hours and 25 minutes, half the period that it takes for the Earth to make a complete revolution and return the Moon to its previous position relative to an observer. The Moon's mass is some 27 million times smaller than the Sun, but it is 400 times closer to the Earth. Tidal force or tide-raising force decreases rapidly with distance, so the moon has more than twice as great an effect on tides as the Sun. A bulge is formed in the ocean at the place where the Earth is closest to the Moon, because it is also where the effect of the Moon's gravity is stronger. On the opposite side of the Earth, the lunar force is at its weakest and this causes another bulge to form. These bulges rotate around the Earth as the moon does. The Sun's effect is less powerful but, when the Sun, Moon and Earth are all aligned at the full and new moons, the combined effect results in the high "spring tides". In contrast, when the Sun is at 90° from the Moon as viewed from Earth, the combined gravitational effect on tides is correspondingly reduced, causing the lower "neap tides".

text: Most places experience two high tides each day, occurring at intervals of about 12 hours and 25 minutes, half the period that it takes for the Earth to make a complete revolution and return the Moon to its previous position relative to an observer. The Moon's mass is some 27 million times smaller than the Sun, but it is 400 times closer to the Earth.

text: Tidal force

text: or tide-raising force decreases rapidly with distance, so the moon has more than twice as great an effect on tides as the Sun. A bulge is formed in the ocean at the place where the Earth is closest to the Moon, because it is also where the effect of the Moon's gravity is stronger. On the opposite side of the Earth, the lunar force is at its weakest and this causes another bulge to form. These bulges rotate around the Earth as the moon does. The Sun's effect is less powerful but, when the Sun, Moon and Earth are all aligned at the

text: full

text: and

text: new moon

text: s, the combined effect results in the high "spring tides". In contrast, when the Sun is at 90° from the Moon as viewed from Earth, the combined gravitational effect on tides is correspondingly reduced, causing the lower "neap tides".

text: An annular solar eclipse will occur on June 1, 2030. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.

text: An annular

text: solar eclipse

text: will occur on June 1, 2030. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: annulus

text: The distance between the Moon and Earth varies from around  to  at perigees (closest) and apogees (farthest), respectively. On 14 November 2016, it was closer to Earth when at full phase than it has been since 1948, 14% closer than its farthest position in apogee. Reported as a "super moon", this closest point coincides within an hour of a full moon, and it was 30% more luminous than when at its greatest distance due to its angular diameter being 14% greater, because

text: The distance between the Moon and Earth varies from around  to  at

text: perigees

text: (closest) and apogees (farthest), respectively. On 14 November 2016, it was closer to Earth when at full phase than it has been since 1948, 14% closer than its farthest position in apogee. Reported as a "

text: super moon

text: ", this closest point coincides within an hour of a

text: full moon

text: , and it was 30% more luminous than when at its greatest distance due to its angular diameter being 14% greater, because

text: An annular solar eclipse will occur on February 5, 2046. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.

text: An annular

text: solar eclipse

text: will occur on February 5, 2046. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: annulus

text: In the early 17th century, Johannes Kepler believed that the speed of light was infinite, since empty space presents no obstacle to it. René Descartes argued that if the speed of light were to be finite, the Sun, Earth, and Moon would be noticeably out of alignment during a lunar eclipse. Since such misalignment had not been observed, Descartes concluded the speed of light was infinite. Descartes speculated that if the speed of light were found to be finite, his whole system of philosophy might be demolished. In  Descartes' derivation of Snell's law, he assumed that even though the speed of light was instantaneous, the more dense the medium, the faster was light's speed. Pierre de Fermat derived Snell's law using the opposing assumption, the more dense the medium the slower light traveled. Fermat also argued in support of  a finite speed of light.

text: In the early 17th century,

text: Johannes Kepler

text: believed that the speed of light was infinite, since empty space presents no obstacle to it.

text: René Descartes

text: argued that if the speed of light were to be finite, the Sun, Earth, and Moon would be noticeably out of alignment during a

text: lunar eclipse

text: . Since such misalignment had not been observed, Descartes concluded the speed of light was infinite. Descartes speculated that if the speed of light were found to be finite, his whole system of philosophy might be demolished. In  Descartes' derivation of

text: Snell's law

text: , he assumed that even though the speed of light was instantaneous, the more dense the medium, the faster was light's speed.

text: Pierre de Fermat

text: derived Snell's law using the opposing assumption, the more dense the medium the slower light traveled. Fermat also argued in support of  a finite speed of light.

text: A synodic month is longer than a sidereal month because the Earth-Moon system is orbiting the Sun in the same direction as the Moon is orbiting the Earth.  Therefore, the Sun appears to move with respect to the stars, and it takes about 2.2 days longer for the Moon to return to the same apparent position with respect to the Sun.

text: An annular solar eclipse will occur on February 6, 2027. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.

text: An annular

text: solar eclipse

text: will occur on February 6, 2027. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: annulus

text: In summary, whenever an eclipse of some sort is occurring on the Earth, an eclipse of another sort is occurring on the Moon. Eclipses occur for both Earth and Lunar observers whenever the two bodies and the Sun align in a straight line.

text: The Han-era Chinese discussed the illumination and shapes of heavenly bodies: were they flat and circular, or were they rounded and spherical? Jing Fang wrote in the 1st century BCE that Han astronomers believed the Sun, Moon, and planets were spherical like balls or crossbow bullets. He also wrote that the Moon and planets produce no light of their own, are viewable to people on Earth only because they are illuminated by the Sun, and those parts not illuminated by the Sun would be dark on the other side. For this, Jing compared the Moon to a mirror illuminating light. In the 2nd century CE, Zhang Heng drew a similar comparison to Jing's by stating that the Sun is like fire and the Moon and planets are like water, since fire produces light and water reflects it. He also repeated Jing's comment that the side of the moon not illuminated by the Sun was left in darkness. However, Zhang noted that sunlight did not always reach the Moon since the Earth obstructs the rays during a lunar eclipse. He also noted that a solar eclipse occurred when the Moon and Sun crossed paths to block sunlight from reaching earth.

text: The Han-era Chinese discussed the illumination and shapes of heavenly bodies: were they flat and circular, or were they rounded and spherical? Jing Fang wrote in the 1st century BCE that Han astronomers believed the Sun, Moon, and planets were spherical like balls or

text: crossbow

text: bullets. He also wrote that the Moon and planets produce no light of their own, are viewable to people on Earth only because they are illuminated by the Sun, and those parts not illuminated by the Sun would be dark on the other side. For this, Jing compared the Moon to a mirror illuminating light. In the 2nd century CE, Zhang Heng drew a similar comparison to Jing's by stating that the Sun is like fire and the Moon and planets are like water, since fire produces light and water reflects it. He also repeated Jing's comment that the side of the moon not illuminated by the Sun was left in darkness. However, Zhang noted that

text: sunlight

text: did not always reach the Moon since the Earth obstructs the rays during a

text: lunar eclipse

text: . He also noted that a

text: solar eclipse

text: occurred when the Moon and Sun crossed paths to block sunlight from reaching earth.

text: A partial solar eclipse occurred on December 2, 1956. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: occurred on December 2, 1956. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: An annular solar eclipse will occur on July 13, 2075. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.

text: An annular

text: solar eclipse

text: will occur on July 13, 2075. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: annulus

text: A partial solar eclipse occurred on May 11, 1975. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: occurred on May 11, 1975. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: A total solar eclipse occurred on 3 November 2013. It was a hybrid eclipse of the Sun with a magnitude of 1.0159, with a small portion over the western atlantic ocean at sunrise as an annular eclipse, and the rest is a narrow total solar eclipse.

text: A total

text: solar eclipse

text: occurred on 3 November 2013. It was a

text: hybrid eclipse

text: of the

text: Sun

text: with a

text: magnitude

text: of 1.0159, with a small portion over the western atlantic ocean at sunrise as an annular eclipse, and the rest is a narrow total solar eclipse.

text: The solar eclipse of January 15, 2010 was an annular eclipse of the Sun with a magnitude of 0.9190. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.It was the longest annular solar eclipse of the millennium, and the longest until December 23, 3043, with a maximum length of 11 minutes, 7.8 seconds. This is about 4 minutes longer than total solar eclipses could ever get. (The solar eclipse of January 4, 1992, was longer, at 11 minutes, 41 seconds, occurring in the middle of the Pacific Ocean.)

text: The solar eclipse of January 15, 2010 was an

text: annular eclipse

text: of the

text: Sun

text: with a

text: magnitude

text: of 0.9190. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: annulus

text: (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.It was the longest annular

text: solar eclipse

text: of the millennium, and the longest until December 23, 3043, with a maximum length of 11 minutes, 7.8 seconds. This is about 4 minutes longer than total solar eclipses could ever get. (The

text: solar eclipse of January 4, 1992

text: , was longer, at 11 minutes, 41 seconds, occurring in the middle of the Pacific Ocean.)

text: A partial solar eclipse occurred on April 17, 1996. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: occurred on April 17, 1996. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: A partial solar eclipse occurred on January 5, 1935. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.It was the last eclipse of solar saros 111 with the moon's penumbra touching the earth for just 10 minutes.

text: A partial

text: solar eclipse

text: occurred on January 5, 1935. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: , thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.It was the last eclipse of

text: solar saros 111

text: with the moon's penumbra touching the earth for just 10 minutes.

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: With respect to the stars, the Moon takes 27 Earth days, 7 hours and 43 minutes 12 seconds to complete its orbit; but since the Earth-Moon system advances around the Sun in the meantime, the Moon must travel further to get back to the same phase. On average(mean), this synodic period lasts 29 days, 12 hours, 44 minutes and 3 seconds. This is an average figure, since the speed of the Earth-Moon system around the Sun varies slightly during a year, due to an imperfect circularity of its orbit, variances in orbital velocity, and a number of other periodic and evolving variations about its observed, relative, mean values, due to the gravitational perturbations of the Sun and other bodies in the Solar System.

text: With respect to the stars, the Moon takes 27

text: Earth day

text: s, 7 hours and 43 minutes 12 seconds to complete its orbit; but since the Earth-Moon system advances around the Sun in the meantime, the Moon must travel further to get back to the same phase. On average(mean), this

text: synodic period

text: lasts 29 days, 12 hours, 44 minutes and 3 seconds. This is an average figure, since the speed of the Earth-Moon system around the Sun varies slightly during a year, due to an imperfect circularity of its orbit, variances in orbital velocity, and a number of other periodic and evolving variations about its observed, relative, mean values, due to the gravitational perturbations of the Sun and other bodies in the Solar System.

text: On the Moon, the electromagnetic machine is assembled.  Roland and the astronaut, Courtney, travel in a rover to locate a fissure in the lunar surface.  The rover crashes deep inside the fissure and Courtney falls to her death.  Roland is unharmed but trapped inside the fissure and unable to rejoin the spacecraft.  He demands that the cosmonaut, Sergei, launch the module so that he and Alex can be saved.  The device is activated, causing a large explosion on the Moon, which kills Roland.  The Moon splits in two as the brown dwarf fragment flies into the Sun.  The orbit of the lunar debris is stable.  Sergei and Alex make radio contact, revealing that they escaped the Moon before the explosion.  Back on Earth, Alex is reunited with his children and with Maddie.

text: Before the advent of modern science, solar eclipses were often viewed with superstitious dread.  However, eclipses are also of interest to science due to the various phenomena that can be observed when they occur.  The sun's outer atmosphere, or corona, is normally invisible due to the brightness of the solar disc, but becomes visible from earth during a total eclipse.  Until the twentieth century, solar eclipses provided the only opportunity for scientists to observe and study the sun's corona.  With the development of photography during the first half of the nineteenth century, it became theoretically possible to record a still image of the sun during a total eclipse.  A variety of processes were used for early photographs, of which the most successful was the Daguerreotype.

text: Before the advent of modern science, solar eclipses were often viewed with superstitious dread.  However, eclipses are also of interest to science due to the various phenomena that can be observed when they occur.  The sun's outer atmosphere, or

text: corona

text: , is normally invisible due to the brightness of the solar disc, but becomes visible from earth during a total eclipse.  Until the twentieth century, solar eclipses provided the only opportunity for scientists to observe and study the sun's corona.  With the development of photography during the first half of the nineteenth century, it became theoretically possible to record a still image of the sun during a total eclipse.  A variety of processes were used for early photographs, of which the most successful was the

text: Daguerreotype

text: A partial solar eclipse will occur on June 21, 2058. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: will occur on June 21, 2058. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: A partial solar eclipse occurred on October 23, 2014. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: occurred on October 23, 2014. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: An early attempt to analyse the positions of the Aubrey holes was undertaken by Gerald Hawkins a professor of astronomy at Boston University in the 1960s using an IBM 7090 computer. In his book Stonehenge Decoded, Hawkins argued that the various features at the Stonehenge monument were arranged in such a way to predict a variety of astronomical events. He believed that the key to the holes' purpose was the lunar eclipse, which occurs on average about once a year on a 346.62-day cycle. Lunar eclipses are not always visible as the moon may be below the horizon as it moves across the sky, but over 18 to 19 years (18.61 years to be precise) the date and position of a visible eclipse will return to its beginning point on the horizon again. As the motion of the moon's orbit also causes it to work its way across the sky on an 18.61-year cycle in what is known as the journey between major and minor standstill and back, the theory that this period was both measurable and useful to Neolithic peoples seemed attractive. Lunar movements may have had calendrical significance to early peoples, especially farmers who would have benefited from the division of the year into periods which indicated the best times for planting. 18.61 is not a whole number and so it cannot be used to predict an eclipse without precision equipment and using only crude stones or timber posts in a circle instead. Hawkins' theory was that three 18.61-year cycles multiply out to 55.83 however, which is much closer to an integer and therefore easier to mark using 56 holes. Hawkins argued that the Aubrey Holes were used to keep track of this long time period and could accurately predict the recurrence of a lunar eclipse on the same azimuth, that which aligned with the Heel Stone, every 56 years. Going further, by placing marker stones at the ninth, eighteenth, twenty-eighth, thirty-seventh, forty-sixth and fifty sixth holes, Hawkins deduced that other intermediate lunar eclipses could also be predicted.

text: An early attempt to analyse the positions of the Aubrey holes was undertaken by

text: Gerald Hawkins

text: a professor of astronomy at

text: Boston University

text: in the 1960s using an

text: IBM 7090

text: computer. In his book

text: Stonehenge Decoded

text: , Hawkins argued that the various features at the Stonehenge monument were arranged in such a way to predict a variety of astronomical events. He believed that the key to the holes' purpose was the

text: lunar eclipse

text: , which occurs on average about once a year on a 346.62-day cycle. Lunar eclipses are not always visible as the moon may be below the horizon as it moves across the sky, but over 18 to 19 years (18.61 years to be precise) the date and position of a visible eclipse will return to its beginning point on the horizon again. As the motion of the moon's orbit also causes it to work its way across the sky on an 18.61-year cycle in what is known as the journey between

text: major

text: and

text: minor standstill

text: and back, the theory that this period was both measurable and useful to Neolithic peoples seemed attractive. Lunar movements may have had calendrical significance to early peoples, especially farmers who would have benefited from the division of the year into periods which indicated the best times for planting. 18.61 is not a whole number and so it cannot be used to predict an eclipse without precision equipment and using only crude stones or timber posts in a circle instead. Hawkins' theory was that three 18.61-year cycles multiply out to 55.83 however, which is much closer to an

text: integer

text: and therefore easier to mark using 56 holes. Hawkins argued that the Aubrey Holes were used to keep track of this long time period and could accurately predict the recurrence of a lunar eclipse on the same

text: azimuth

text: , that which aligned with the Heel Stone, every 56 years. Going further, by placing marker stones at the ninth, eighteenth, twenty-eighth, thirty-seventh, forty-sixth and fifty sixth holes, Hawkins deduced that other intermediate lunar eclipses could also be predicted.

text: Because the Earth's orbit around the Sun is also elliptical, the Earth's distance from the Sun similarly varies throughout the year. This affects the apparent size of the Sun in the same way, but not as much as does the Moon's varying distance from Earth. When Earth approaches its farthest distance from the Sun in July, a total eclipse is somewhat more likely, whereas conditions favour an annular eclipse when Earth approaches its closest distance to the Sun in January.

text: Because the Earth's orbit around the Sun is also elliptical, the Earth's distance from the Sun similarly varies throughout the year. This affects the apparent size of the Sun in the same way, but not as much as does the Moon's varying distance from Earth. When Earth approaches its

text: farthest distance from the Sun

text: in July, a total eclipse is somewhat more likely, whereas conditions favour an annular eclipse when Earth approaches its

text: closest distance to the Sun

text: in January.

text: The phase curve of the Moon approximately resembles that of Mercury due to the similarities of the surfaces and the lack of an atmosphere on either body. Clementine spacecraft data analyzed by J. Hillier, B. Buratti and K. Hill indicate a lunar opposition surge. The Moon's apparent magnitude at full phase is −12.7 while at quarter phase it is less than 10 percent as bright.

text: The phase curve of the

text: Moon

text: approximately resembles that of Mercury due to the similarities of the surfaces and the lack of an atmosphere on either body.

text: Clementine

text: spacecraft data analyzed by J. Hillier, B. Buratti and K. Hill indicate a lunar opposition surge. The Moon's apparent magnitude at full phase is −12.7 while at quarter phase it is less than 10 percent as bright.

text: Most of the major bodies of the Solar System orbit the Sun in nearly the same plane. This is likely due to the way in which the Solar System formed from a protoplanetary disk. Probably the closest current representation of the disk is known as the invariable plane of the Solar System. Earth's orbit, and hence, the ecliptic, is inclined a little more than 1° to the invariable plane, and the other major planets are also within about 6° of it. Because of this, most Solar System bodies appear very close to the ecliptic in the sky. The ecliptic is well defined by the motion of the Sun. The invariable plane is defined by the angular momentum of the entire Solar System, essentially the summation of all of the orbital motions and rotations of all the bodies of the system, a somewhat uncertain value that requires precise knowledge of every object in the system. For these reasons, the ecliptic is used as the reference plane of the Solar System out of convenience.

text: Most of the major bodies of the

text: Solar System

text: orbit the

text: Sun

text: in nearly the same plane. This is likely due to the way in which the Solar System formed from a

text: protoplanetary disk

text: . Probably the closest current representation of the disk is known as the

text: invariable plane

text: of the Solar System. Earth's orbit, and hence, the ecliptic, is inclined a little more than 1° to the invariable plane, and the other major planets are also within about 6° of it. Because of this, most Solar System bodies appear very close to the ecliptic in the sky. The ecliptic is well defined by the motion of the

text: Sun

text: . The invariable plane is defined by the

text: angular momentum

text: of the entire Solar System, essentially the

text: summation

text: of all of the

text: orbit

text: al motions and

text: rotations

text: of all the bodies of the system, a somewhat uncertain value that requires precise knowledge of every object in the system. For these reasons, the ecliptic is used as the reference plane of the Solar System out of convenience.

text: Why did Hipparchus need a lunar eclipse to measure the position of a star? The equinoctial points are not marked in the sky, so he needed the Moon as a reference point. Hipparchus already had developed a way to calculate the longitude of the Sun at any moment. A lunar eclipse happens during Full moon, when the Moon is in opposition. At the midpoint of the eclipse, the Moon is precisely 180° from the Sun. Hipparchus is thought to have measured the longitudinal arc separating Spica from the Moon. To this value, he added the calculated longitude of the Sun, plus 180° for the longitude of the Moon. He did the same procedure with Timocharis' data (Evans 1998, p. 251). Observations such as these eclipses, incidentally, are the main source of data about when Hipparchus worked, since other biographical information about him is minimal. The lunar eclipses he observed, for instance, took place on April 21, 146 BC, and March 21, 135 BC (Toomer 1984, p. 135 n. 14).

text: Why did Hipparchus need a

text: lunar eclipse

text: to measure the position of a star? The equinoctial points are not marked in the sky, so he needed the Moon as a reference point. Hipparchus already had developed a way to calculate the longitude of the Sun at any moment. A lunar eclipse happens during

text: Full moon

text: , when the Moon is in

text: opposition

text: . At the midpoint of the eclipse, the Moon is precisely 180° from the Sun. Hipparchus is thought to have measured the longitudinal arc separating Spica from the Moon. To this value, he added the calculated longitude of the Sun, plus 180° for the longitude of the Moon. He did the same procedure with Timocharis' data (Evans 1998, p. 251). Observations such as these eclipses, incidentally, are the main source of data about when Hipparchus worked, since other biographical information about him is minimal. The lunar eclipses he observed, for instance, took place on April 21, 146 BC, and March 21, 135 BC (Toomer 1984, p. 135 n. 14).

text: A partial solar eclipse occurred on December 15, 1982. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: occurred on December 15, 1982. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: A total solar eclipse occurred on August 1, 2008. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A total solar eclipse occurs when the Moon's apparent diameter is larger than the Sun's, blocking all direct sunlight, turning day into darkness. Totality occurs in a narrow path across Earth's surface, with the partial solar eclipse visible over a surrounding region thousands of kilometres wide.It had a magnitude of 1.0394 that was visible from a narrow corridor through northern Canada (Nunavut), Greenland, central Russia, eastern Kazakhstan, western Mongolia and China. Occurring north of the arctic circle, it belonged to the so-called midnight sun eclipses. The largest city on the path of the eclipse was Novosibirsk in Russia.

text: A total

text: solar eclipse

text: occurred on August 1, 2008. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: is larger than the Sun's, blocking all direct sunlight, turning day into darkness. Totality occurs in a narrow path across Earth's surface, with the partial solar eclipse visible over a surrounding region thousands of kilometres wide.It had a

text: magnitude

text: of 1.0394 that was visible from a narrow corridor through northern

text: Canada

text: Nunavut

text: Greenland

text: , central

text: Russia

text: , eastern

text: Kazakhstan

text: , western

text: Mongolia

text: and China. Occurring north of the

text: arctic circle

text: , it belonged to the so-called

text: midnight sun

text: eclipses. The largest city on the path of the eclipse was

text: Novosibirsk

text: in Russia.

text: This is a list of solar eclipses in the 13th century BC. During the period 1300 to 1201 BC there were 250 solar eclipses of which 93 were partial, 86 were annular, 64 were total, and 7 were hybrids. The greatest number of eclipses in one year was four, occurring in 16 different years: 1300 BC, 1289 BC, 1285 BC, 1282 BC, 1278 BC, 1271 BC, 1260 BC, 1253 BC, 1249 BC, 1242 BC, 1231 BC, 1224 BC, 1220 BC, 1213 BC, 1210 BC, and 1202 BC. One month, December 1210 BC, had two eclipses.

text: This is a list of solar eclipses in the 13th century BC. During the period 1300 to 1201 BC there were 250

text: solar eclipse

text: s of which 93 were

text: partial

text: , 86 were annular, 64 were total, and 7 were hybrids. The greatest number of eclipses in one year was four, occurring in 16 different years: 1300 BC, 1289 BC, 1285 BC, 1282 BC, 1278 BC, 1271 BC, 1260 BC, 1253 BC, 1249 BC, 1242 BC, 1231 BC, 1224 BC, 1220 BC, 1213 BC, 1210 BC, and 1202 BC. One month, December 1210 BC, had two eclipses.

text: The trip to Lorraine in 1564 was a set back for his health but he soon recovered and embarked on his greatest project yet, a project which would extend far beyond his cartographic interests. The first element was the Chronologia, a list of all significant events since the beginning of the world compiled from his literal reading of the bible and no less than 123 other authors of genealogies and histories of every empire that had ever existed. Mercator was the first to link historical dates of solar and lunar eclipses to Julian dates calculated mathematically from his knowledge of the motions of the sun, moon and Earth. He then fixed the dates of other events in Babylonian, Greek, Hebrew and Roman calendars relative to the eclipses that they recorded. The time origin was fixed from the genealogies of the Bible as 3965 years before the birth of Christ. This huge volume (400 pages) was greeted with acclaim by scholars throughout Europe and Mercator himself considered it to be his greatest achievement up to that time. On the other hand, the Catholic Church placed the work on the Index Librorum Prohibitorum (List of Prohibited Books) because Mercator included the deeds of Martin Luther. Had he published such a work in Louvain he would again be laying himself open to charges of heresy.

text: The trip to Lorraine in 1564 was a set back for his health but he soon recovered and embarked on his greatest project yet, a project which would extend far beyond his cartographic interests. The first element was the Chronologia, a list of all significant events since the beginning of the world compiled from his literal reading of the bible and no less than 123 other authors of genealogies and histories of every empire that had ever existed. Mercator was the first to link historical dates of solar and lunar eclipses to

text: Julian dates

text: calculated mathematically from his knowledge of the motions of the sun, moon and Earth. He then fixed the dates of other events in Babylonian, Greek, Hebrew and Roman calendars relative to the eclipses that they recorded. The time origin was fixed from the genealogies of the Bible as 3965 years before the birth of Christ. This huge volume (400 pages) was greeted with acclaim by scholars throughout Europe and Mercator himself considered it to be his greatest achievement up to that time. On the other hand, the

text: Catholic Church

text: placed the work on the

text: Index Librorum Prohibitorum

text: (List of Prohibited Books) because Mercator included the deeds of

text: Martin Luther

text: . Had he published such a work in Louvain he would again be laying himself open to charges of heresy.

text: An annular solar eclipse occurred on May 30, 1984. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.

text: An

text: annular

text: solar eclipse

text: occurred on May 30, 1984. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: annulus

text: An annular solar eclipse occurred on July 20, 1925. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.

text: An annular

text: solar eclipse

text: occurred on July 20, 1925. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: annulus

text: In the case of a planet's moon, the synodic period usually means the Sun-synodic period, namely, the time it takes the moon to complete its illumination phases, completing the solar phases for an astronomer on the planet's surface. The Earth's motion does not determine this value for other planets because an Earth observer is not orbited by the moons in question. For example, Deimos's synodic period is 1.2648 days, 0.18% longer than Deimos's sidereal period of 1.2624 d.

text: In the case of a planet's

text: moon

text: , the synodic period usually means the Sun-synodic period, namely, the time it takes the moon to complete its illumination phases, completing the solar phases for an astronomer on the planet's surface. The Earth's motion does not determine this value for other planets because an Earth observer is not orbited by the moons in question. For example,

text: Deimos

text: 's synodic period is 1.2648 days, 0.18% longer than Deimos's sidereal period of 1.2624 d.

text: In the following year the visual description of music was still on Thompson's mind. A solo exhibition titled Concatenation at Agnes Scott College contained a wooden sculpture titled Mass whose six parts were titled Kyrie, Gloria, Credo, Sanctus, Benedictus, and Gloria Dei. But other influences, including astronomy, spiritualism and metaphysics were starting to appear in her work.  Included in Concatenations was a series of prints titled Five Mysteries. Their abstract compositions, printed in black ink on white paper, were schematic representations of earth, atmosphere and sun, the latter a flat disc set in a sky filled with energetic marks and scratches. Thompson's series of watercolors, titled Lemurian Wanderings, were described by critic Lorena Gay-Griffin as “…the time at the dawn of the world before the first ray of sun shone through the atmosphere.” A series of colored pencil drawings, “The Phases of Cynthia”, was reported by the same writer to refer to Galileo’s study of the phases of the moon. The drawings featured “…the same sun/moon image as the prints. The circles are layered with other geometric shapes and surrounded by fragments and rays emitting from the center.” In 1990 Thompson told Essence magazine that “My work has to do with the cosmos and how it affects us.” Such references continued in her printmaking. In 1993, as an artist-in-residence at Littleton Studios in North Carolina, Thompson created prints in vitreography titled Helio Centric, Particles and Wave Function.

text: In the following year the visual description of music was still on Thompson's mind. A solo exhibition titled Concatenation at

text: Agnes Scott College

text: contained a wooden sculpture titled Mass whose six parts were titled Kyrie, Gloria, Credo, Sanctus, Benedictus, and Gloria Dei. But other influences, including

text: astronomy

text: spiritualism

text: and

text: metaphysics

text: were starting to appear in her work.  Included in Concatenations was a series of prints titled Five Mysteries. Their abstract compositions, printed in black ink on white paper, were schematic representations of earth, atmosphere and sun, the latter a flat disc set in a sky filled with energetic marks and scratches. Thompson's series of watercolors, titled Lemurian Wanderings, were described by critic Lorena Gay-Griffin as “…the time at the dawn of the world before the first ray of sun shone through the atmosphere.” A series of colored pencil drawings, “The Phases of Cynthia”, was reported by the same writer to refer to

text: Galileo

text: ’s study of the phases of the moon. The drawings featured “…the same sun/moon image as the prints. The circles are layered with other geometric shapes and surrounded by fragments and rays emitting from the center.” In 1990 Thompson told

text: Essence

text: magazine that “My work has to do with the cosmos and how it affects us.” Such references continued in her printmaking. In 1993, as an artist-in-residence at Littleton Studios in North Carolina, Thompson created prints in

text: vitreography

text: titled Helio Centric, Particles and Wave Function.

text: An annular solar eclipse occurred on March 7, 1932. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.

text: An annular

text: solar eclipse

text: occurred on March 7, 1932. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: annulus

text: A partial solar eclipse occurred on January 14, 1964. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. Partial solar eclipses occur in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A

text: partial solar eclipse

text: occurred on January 14, 1964. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: , thereby totally or partly obscuring the image of the Sun for a viewer on Earth. Partial solar eclipses occur in the

text: polar regions

text: of the Earth when the center of the Moon's shadow misses the Earth.

text: An annular solar eclipse will occur on March 31, 2071. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.

text: An annular

text: solar eclipse

text: will occur on March 31, 2071. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: annulus

text: An annular solar eclipse will occur on August 3, 2092. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.

text: An annular

text: solar eclipse

text: will occur on August 3, 2092. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: annulus

text: An annular solar eclipse occurred on September 1, 1951. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.

text: An annular

text: solar eclipse

text: occurred on September 1, 1951. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: annulus

text: Transits and occultations of the Sun by Earth's Moon are called solar eclipses regardless of whether the Sun is completely or partially covered. By extension, transits of the Sun by a satellite of a planet may also be called eclipses, as with the transits of Phobos and Deimos shown on NASA's JPL photojournal, as may the passage of a satellite into the planet's shadow, as with this eclipse of Phobos. The term eclipse is also used more generally for bodies passing in front of one another. For example, a NASA Astronomy Picture of the Day refers to the Moon eclipsing and occulting Saturn interchangeably.

text: Transits and occultations of the Sun by Earth's Moon are called

text: solar eclipse

text: s regardless of whether the Sun is completely or partially covered. By extension, transits of the Sun by a

text: satellite

text: of a planet may also be called eclipses, as with the transits of Phobos and Deimos shown on NASA's JPL photojournal, as may the passage of a satellite into the planet's shadow, as with this eclipse of Phobos. The term eclipse is also used more generally for bodies passing in front of one another. For example, a NASA Astronomy Picture of the Day refers to the Moon eclipsing and occulting Saturn interchangeably.

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: An annular solar eclipse occurred on April 19, 1939. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.

text: An annular

text: solar eclipse

text: occurred on April 19, 1939. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: annulus

text: In the second book, Hipparchus starts from the opposite extreme assumption: he assigns a (minimum) distance to the Sun of 490 Earth radii. This would correspond to a parallax of 7', which is apparently the greatest parallax that Hipparchus thought would not be noticed (for comparison: the typical resolution of the human eye is about 2'; Tycho Brahe made naked eye observation with an accuracy down to 1'). In this case, the shadow of the Earth is a cone rather than a cylinder as under the first assumption. Hipparchus observed (at lunar eclipses) that at the mean distance of the Moon, the diameter of the shadow cone is 2+½ lunar diameters. That apparent diameter is, as he had observed, 360/650 degrees. With these values and simple geometry, Hipparchus could determine the mean distance; because it was computed for a minimum distance of the Sun, it is the maximum mean distance possible for the Moon. With his value for the eccentricity of the orbit, he could compute the least and greatest distances of the Moon too. According to Pappus, he found a least distance of 62, a mean of 67+1/3, and consequently a greatest distance of 72+2/3 Earth radii. With this method, as the parallax of the Sun decreases (i.e., its distance increases), the minimum limit for the mean distance is 59 Earth radii – exactly the mean distance that Ptolemy later derived.

text: In the second book, Hipparchus starts from the opposite extreme assumption: he assigns a (minimum) distance to the Sun of 490 Earth radii. This would correspond to a parallax of 7', which is apparently the greatest parallax that Hipparchus thought would not be noticed (for comparison: the typical resolution of the human eye is about 2';

text: Tycho Brahe

text: made naked eye observation with an accuracy down to 1'). In this case, the shadow of the Earth is a

text: cone

text: rather than a

text: cylinder

text: as under the first assumption. Hipparchus observed (at lunar eclipses) that at the mean distance of the Moon, the diameter of the shadow cone is 2+½ lunar diameters. That apparent diameter is, as he had observed, 360/650 degrees. With these values and simple geometry, Hipparchus could determine the mean distance; because it was computed for a minimum distance of the Sun, it is the maximum mean distance possible for the Moon. With his value for the eccentricity of the orbit, he could compute the least and greatest distances of the Moon too. According to Pappus, he found a least distance of 62, a mean of 67+1/3, and consequently a greatest distance of 72+2/3 Earth radii. With this method, as the parallax of the Sun decreases (i.e., its distance increases), the minimum limit for the mean distance is 59 Earth radii – exactly the mean distance that Ptolemy later derived.

text: An annular solar eclipse occurred on April 29, 2014. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.The center of the moon's shadow misses the south Pole of the Earth, but the partial eclipse was visible from parts of Antarctica and Australia.

text: An annular

text: solar eclipse

text: occurred on April 29, 2014. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: annulus

text: (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.The center of the

text: moon

text: 's shadow misses the

text: south Pole

text: of the

text: Earth

text: , but the partial eclipse was visible from parts of

text: Antarctica

text: and

text: Australia

text: It is believed by their fans that Hexagon Sun has held parties in the past, which may be how the collective originally formed. These get-togethers were soon known as "Redmoon" events, after the occurrence during one such party of a lunar eclipse which colors the moon red..

text: With an albedo of 0.09, Ceres's surface is quite dark compared to the moons in the outer Solar System. This might be a result of the relatively high temperature of Ceres's surface, the maximum temperature with the Sun overhead was estimated from measurements to be 235 K (approximately −38 °C, −36 °F) on 5 May 1991. In a vacuum, ice is unstable at this temperature. Material left behind by the sublimation of surface ice could explain the dark surface of Ceres compared to the icy moons of the outer Solar System.

text: With an

text: albedo

text: of 0.09, Ceres's surface is quite dark compared to the

text: moons

text: in the outer

text: Solar System

text: . This might be a result of the relatively high temperature of Ceres's surface, the maximum temperature with the Sun overhead was estimated from measurements to be 235 K (approximately −38 °C, −36 °F) on 5 May 1991. In a vacuum, ice is unstable at this temperature. Material left behind by the sublimation of surface ice could explain the dark surface of Ceres compared to the icy moons of the outer Solar System.

text: An annular solar eclipse will occur on October 24, 2060. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.

text: An annular

text: solar eclipse

text: will occur on October 24, 2060. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: annulus

text: An annular solar eclipse occurred on July 9, 1926. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.

text: An annular

text: solar eclipse

text: occurred on July 9, 1926. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: annulus

text: Delan - The moon, usually he and Elag are congenial and take turns giving light; but sometimes they quarrel and Elag covers Delan more or less with a great, huge winnowing biga-o (basket). Thus we have the different phases of the moon.

text: An annular solar eclipse will occur on June 10, 2021. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.This eclipse will be unusual as the path of the total eclipse will move to the north east, then north, north west, west, south west, south, and finally south east across the Arctic, while most eclipse paths move west to east.  This reversal is only possible in polar regions.This eclipse is also notable for the fact that the path of annularity passes over the North Pole.

text: An annular

text: solar eclipse

text: will occur on June 10, 2021. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: annulus

text: (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.This eclipse will be unusual as the path of the total eclipse will move to the north east, then north, north west, west, south west, south, and finally south east across the

text: Arctic

text: , while most eclipse paths move west to east.  This reversal is only possible in polar regions.This eclipse is also notable for the fact that the path of annularity passes over the

text: North Pole

text: The near side of the Moon is the lunar hemisphere that is permanently turned towards the Earth, whereas the opposite side is the far side of the Moon. Only one side of the Moon is visible from Earth because the Moon rotates about its spin axis at the same rate that the Moon orbits the Earth, a situation known as synchronous rotation or tidal locking. The Moon is directly illuminated by the Sun, and the cyclically varying viewing conditions cause the lunar phases. The unilluminated portions of the Moon can sometimes be dimly seen as a result of earthshine, which is sunlight reflected off the surface of the Earth and onto the Moon. Since the Moon's orbit is both somewhat elliptical, and inclined to its equatorial plane, libration allows up to 59% of the Moon's surface to be viewed from Earth (but only half at any instant from any point).

text: The near side of the Moon is the

text: lunar

text: hemisphere that is permanently turned towards the

text: Earth

text: , whereas the opposite side is the

text: far side of the Moon

text: . Only one side of the

text: Moon

text: is visible from Earth because the Moon rotates about its spin axis at the same rate that the Moon orbits the Earth, a situation known as

text: synchronous rotation

text: or

text: tidal locking

text: . The Moon is directly illuminated by the

text: Sun

text: , and the cyclically varying viewing conditions cause the

text: lunar phase

text: s. The unilluminated portions of the Moon can sometimes be dimly seen as a result of

text: earthshine

text: , which is sunlight reflected off the surface of the Earth and onto the Moon. Since the

text: Moon's orbit

text: is both somewhat elliptical, and inclined to its

text: equatorial plane

text: libration

text: allows up to 59% of the Moon's surface to be viewed from Earth (but only half at any instant from any point).

text: Despite this, Chinese thinkers of the Middle Ages proposed some hypotheses which are in accordance with modern principles of science. Yang Hui provided theoretical proof for the proposition that the complements of the parallelograms which are about the diameter of any given parallelogram are equal to one another. Sun Sikong (1015–1076) proposed the idea that rainbows were the result of the contact between sunlight and moisture in the air, while Shen Kuo (1031–1095) expanded upon this with description of atmospheric refraction. Shen believed that rays of sunlight refracted before reaching the surface of the earth, hence the appearance of the observed sun from earth did not match its exact location. Coinciding with the astronomical work of his colleague Wei Pu, Shen and Wei realized that the old calculation technique for the mean sun was inaccurate compared to the apparent sun, since the latter was ahead of it in the accelerated phase of motion, and behind it in the retarded phase. Shen supported and expanded upon beliefs earlier proposed by Han Dynasty (202 BCE–202 CE) scholars such as Jing Fang (78–37 BCE) and Zhang Heng (78–139 CE) that lunar eclipse occurs when the earth obstructs the sunlight traveling towards the moon, a solar eclipse is the moon's obstruction of sunlight reaching earth, the moon is spherical like a ball and not flat like a disc, and moonlight is merely sunlight reflected from the moon's surface. Shen also explained that the observance of a full moon occurred when the sun's light was slanting at a certain degree and that crescent phases of the moon proved that the moon was spherical, using a metaphor of observing different angles of a silver ball with white powder thrown onto one side. It should be noted that, although the Chinese accepted the idea of spherical-shaped heavenly bodies, the concept of a spherical earth (as opposed to a flat earth) was not accepted in Chinese thought until the works of Italian Jesuit Matteo Ricci (1552–1610) and Chinese astronomer Xu Guangqi (1562–1633) in the early 17th century.

text: Despite this, Chinese thinkers of the Middle Ages proposed some hypotheses which are in accordance with modern principles of science. Yang Hui provided theoretical proof for the proposition that the complements of the

text: parallelogram

text: s which are about the diameter of any given parallelogram are equal to one another. Sun Sikong (1015–1076) proposed the idea that

text: rainbow

text: s were the result of the contact between sunlight and moisture in the air, while

text: Shen Kuo

text: (1031–1095) expanded upon this with description of

text: atmospheric refraction

text: . Shen believed that rays of sunlight refracted before reaching the surface of the earth, hence the appearance of the observed sun from earth did not match its exact location. Coinciding with the astronomical work of his colleague

text: Wei Pu

text: , Shen and Wei realized that the old calculation technique for the mean sun was inaccurate compared to the apparent sun, since the latter was ahead of it in the accelerated phase of motion, and

text: behind it in the retarded phase

text: . Shen supported and expanded upon beliefs earlier proposed by

text: Han Dynasty

text: (202 BCE–202 CE) scholars such as

text: Jing Fang

text: (78–37 BCE) and

text: Zhang Heng

text: (78–139 CE) that

text: lunar eclipse

text: occurs when the earth obstructs the sunlight traveling towards the moon, a

text: solar eclipse

text: is the moon's obstruction of sunlight reaching earth, the moon is spherical like a ball and not flat like a disc, and moonlight is merely sunlight reflected from the moon's surface. Shen also explained that the observance of a full moon occurred when the sun's light was slanting at a certain degree and that crescent

text: phases of the moon

text: proved that the moon was spherical, using a metaphor of observing different angles of a silver ball with white powder thrown onto one side. It should be noted that, although the Chinese accepted the idea of spherical-shaped heavenly bodies, the concept of a

text: spherical earth

text: (as opposed to a

text: flat earth

text: ) was not accepted in Chinese thought until the works of Italian Jesuit

text: Matteo Ricci

text: (1552–1610) and Chinese astronomer

text: Xu Guangqi

text: (1562–1633) in the early 17th century.

text: A partial solar eclipse occurred on February 3, 1935. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: occurred on February 3, 1935. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: The bodies of the sun and moon were both formed out of water (7.45). Sun, moon and stars each possess only their own light (7.35). How, then may eclipses be explained? Reeve says "whatever men have long declared concerning the eclipse of the sun, through the near appearance of the moon, you may understand that the true occasion of the sun eclipsed, whether in part or whole, is according to their appearing at a further or nearer distance unto each other." (7.49). "harken no more unto vain astronomers or star-gazers, concerning the bulk of the sun, moon and stars, for I positively affirm from the God that made them that the compass of their bodies are not much bigger than they appear to our natural sight" (7.33).

text: A partial solar eclipse occurred on August 12, 1942. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: occurred on August 12, 1942. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: An annular solar eclipse will occur on September 12, 2034. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.

text: An annular

text: solar eclipse

text: will occur on September 12, 2034. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: annulus

text: The nodes are points at which the Moon's orbit crosses the ecliptic. The Moon crosses the same node every 27.2122 days, an interval called the draconic or draconitic month. The line of nodes, the intersection between the two respective planes, has a retrograde motion: for an observer on Earth it rotates westward along the ecliptic with a period of 18.60 years, or 19.3549° per year. When viewed from celestial north, the nodes move clockwise around Earth, opposite to Earth's own spin and its revolution around the Sun. Lunar and solar eclipses can occur when the nodes align with the Sun, roughly every 173.3 days. Lunar orbit inclination also determines eclipses; shadows cross when nodes coincide with full and new moon, when the Sun, Earth, and Moon align in three dimensions.

text: The nodes are points at which the Moon's orbit crosses the ecliptic. The Moon crosses the same node every 27.2122 days, an interval called the

text: draconic

text: or draconitic month. The line of nodes, the intersection between the two respective planes, has a

text: retrograde motion

text: : for an observer on Earth it rotates westward along the ecliptic with a period of 18.60 years, or 19.3549° per year. When viewed from celestial north, the nodes move clockwise around Earth, opposite to Earth's own spin and its revolution around the Sun. Lunar and solar eclipses can occur when the nodes align with the Sun, roughly every 173.3 days. Lunar orbit inclination also determines eclipses; shadows cross when nodes coincide with full and new moon, when the Sun, Earth, and Moon align in three dimensions.

text: An annular solar eclipse occurred on March 28, 1922. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.

text: An annular

text: solar eclipse

text: occurred on March 28, 1922. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: annulus

text: A partial solar eclipse will occur on March 11, 2062. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: will occur on March 11, 2062. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: The path which the sun takes among the stars is known as the ecliptic.   The moon's orbit is inclined at five degrees to the ecliptic, so it will always be within five degrees either side of it.   For  half the sidereal month (relative to the stars) the moon is below the ecliptic and for half it is above.   The point where the moon's orbit cuts that of the earth is the "node" – at the "ascending node" the moon moves from south to north and at the "descending node" it moves from north to south.   These points are where eclipses occur – hence the name.   The nodes move around the ecliptic at the rate of one circuit every 18.6 years.   The ecliptic makes the steepest angle with the horizon at the equinoxes.   The crescent moon is near the sun so it is at those times it will be seen lying on its  back.

text: The path which the sun takes among the stars is known as the

text: ecliptic

text: .   The moon's orbit is inclined at five degrees to the ecliptic, so it will always be within five degrees either side of it.   For  half the

text: sidereal month

text: (relative to the stars) the moon is below the ecliptic and for half it is above.   The point where the moon's orbit cuts that of the earth is the "node" – at the "ascending node" the moon moves from south to north and at the "descending node" it moves from north to south.   These points are where eclipses occur – hence the name.   The nodes move around the ecliptic at the rate of one circuit every 18.6 years.   The ecliptic makes the steepest angle with the horizon at the equinoxes.   The crescent moon is near the sun so it is at those times it will be seen lying on its  back.

text: A total solar eclipse will occur on December 6, 2067. It is a hybrid event, beginning and ending as an annular eclipse. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.

text: A total

text: solar eclipse

text: will occur on December 6, 2067. It is a hybrid event, beginning and ending as an annular eclipse. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: annulus

text: Pliny also remarks that "he also discovered for what exact reason, although the shadow causing the eclipse must from sunrise onward be below the earth, it happened once in the past that the moon was eclipsed in the west while both luminaries were visible above the earth" (translation H. Rackham (1938), Loeb Classical Library 330 p. 207). Toomer (1980) argued that this must refer to the large total lunar eclipse of 26 November 139 , when over a clean sea horizon as seen from Rhodes, the Moon was eclipsed in the northwest just after the Sun rose in the southeast. This would be the second eclipse of the 345-year interval that Hipparchus used to verify the traditional Babylonian periods: this puts a late date to the development of Hipparchus's lunar theory. We do not know what "exact reason" Hipparchus found for seeing the Moon eclipsed while apparently it was not in exact opposition to the Sun. Parallax lowers the altitude of the luminaries; refraction raises them, and from a high point of view the horizon is lowered.

text: Pliny also remarks that "he also discovered for what exact reason, although the shadow causing the eclipse must from sunrise onward be below the earth, it happened once in the past that the moon was eclipsed in the west while both luminaries were visible above the earth" (translation H. Rackham (1938),

text: Loeb Classical Library

text: 330 p. 207). Toomer (1980) argued that this must refer to the large total lunar eclipse of 26 November 139 , when over a clean sea horizon as seen from Rhodes, the Moon was eclipsed in the northwest just after the Sun rose in the southeast. This would be the second eclipse of the 345-year interval that Hipparchus used to verify the traditional Babylonian periods: this puts a late date to the development of Hipparchus's lunar theory. We do not know what "exact reason" Hipparchus found for seeing the Moon eclipsed while apparently it was not in exact

text: opposition

text: to the Sun. Parallax lowers the altitude of the luminaries; refraction raises them, and from a high point of view the horizon is lowered.

text: A partial solar eclipse occurred on November 2, 1910. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: occurred on November 2, 1910. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: Arguably the most complicated of its kind ever constructed, the last of a total of four astronomical clocks designed and made by Norwegian Rasmus Sørnes (1893–1967), is characterized by its superior complexity compactly housed in a casing with the modest measurements of 0.70 x 0.60 x 2.10 m. Features include locations of the sun and moon in the zodiac, Julian calendar, Gregorian calendar, sidereal time, GMT, local time with daylight saving time and leap year, solar and lunar cycle corrections, eclipses, local sunset and sunrise, moonphase, tides, sunspot cycles and a planetarium including Pluto's 248 year orbit and the 25 800-year period of the polar ecliptics (precession of the Earth's axis). All wheels are in brass and gold-plated. Dials are silver-plated.

text: Arguably the most complicated of its kind ever constructed, the last of a total of four astronomical clocks designed and made by Norwegian

text: Rasmus Sørnes

text: (1893–1967), is characterized by its superior complexity compactly housed in a casing with the modest measurements of 0.70 x 0.60 x 2.10 m. Features include locations of the sun and moon in the zodiac,

text: Julian calendar

text: Gregorian calendar

text: sidereal time

text: , GMT, local time with daylight saving time and leap year, solar and lunar cycle corrections, eclipses, local sunset and sunrise, moonphase, tides,

text: sunspot

text: cycles and a

text: planetarium

text: including

text: Pluto

text: 's 248 year orbit and the 25 800-year period of the polar ecliptics (

text: precession

text: of the Earth's axis). All wheels are in brass and gold-plated. Dials are silver-plated.

text: The term eclipse is most often used to describe either a solar eclipse, when the Moon's shadow crosses the Earth's surface, or a lunar eclipse, when the Moon moves into the Earth's shadow. However, it can also refer to such events beyond the Earth–Moon system: for example, a planet moving into the shadow cast by one of its moons, a moon passing into the shadow cast by its host planet, or a moon passing into the shadow of another moon. A binary star system can also produce eclipses if the plane of the orbit of its constituent stars intersects the observer's position.

text: The term eclipse is most often used to describe either a

text: solar eclipse

text: , when the Moon's shadow crosses the Earth's surface, or a

text: lunar eclipse

text: , when the Moon moves into the Earth's shadow. However, it can also refer to such events beyond the Earth–Moon system: for example, a planet moving into the shadow cast by one of its moons, a moon passing into the shadow cast by its host planet, or a moon passing into the shadow of another moon. A

text: binary star

text: system can also produce eclipses if the plane of the orbit of its constituent stars intersects the observer's position.

text: The Earth and the Sun sometimes meet in the lunar sky, causing an eclipse. On the Earth, one then sees a lunar eclipse, in which the Moon passes through the Earth's shadow, but on the Moon, one would see the Sun go behind the Earth—causing a solar eclipse. As the apparent diameter of the Earth is four times as large as that of the Sun, the Sun would be hidden behind the Earth for hours. The Earth's atmosphere would be visible as a reddish ring. An attempt was made to use the Apollo 15 Lunar rover TV camera to view such an eclipse, but the camera or its power source failed after the astronauts left for Earth.

text: The Earth and the Sun sometimes meet in the lunar sky, causing an

text: eclipse

text: . On the Earth, one then sees a

text: lunar eclipse

text: , in which the Moon passes through the Earth's shadow, but on the Moon, one would see the Sun go behind the Earth—causing a

text: solar eclipse

text: . As the apparent diameter of the Earth is four times as large as that of the Sun, the Sun would be hidden behind the Earth for hours. The

text: Earth's atmosphere

text: would be visible as a reddish ring. An attempt was made to use the

text: Apollo 15

text: Lunar rover

text: TV camera to view such an eclipse, but the camera or its power source failed after the astronauts left for Earth.

text: A partial solar eclipse will occur on January 14, 2029. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: will occur on January 14, 2029. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: The House Un-American Activities Committee, with young Congressman Richard M. Nixon playing a central role, accused Alger Hiss, a top Roosevelt aide, of being a Communist spy, using testimony and documents provided by Whittaker Chambers. Hiss was convicted and sent to prison, with the anti-Communists gaining a powerful political weapon.  It launched Nixon's meteoric rise to the Senate (1950) and the vice presidency (1952).

text: The

text: House Un-American Activities Committee

text: , with young Congressman

text: Richard M. Nixon

text: playing a central role, accused

text: Alger Hiss

text: , a top Roosevelt aide, of being a Communist spy, using testimony and documents provided by

text: Whittaker Chambers

text: . Hiss was convicted and sent to prison, with the anti-Communists gaining a powerful political weapon.  It launched Nixon's meteoric rise to the Senate (1950) and the vice presidency (1952).

text: The larvae feed on Cercocarpus ledifolius and probably other Cercocarpus species.

text: The larvae feed on

text: Cercocarpus ledifolius

text: and probably other

text: Cercocarpus

text: species.

text: A partial solar eclipse occurred on August 20, 1906. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: occurred on August 20, 1906. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: where R is the radius of the star, R is the occulting object's radius, and r is the distance from the star to the occulting object. For Earth, on average L is equal to 1.384 km, which is much larger than the Moon's semimajor axis of 3.844 km. Hence the umbral cone of the Earth can completely envelop the Moon during a lunar eclipse. If the occulting object has an atmosphere, however, some of the luminosity of the star can be refracted into the volume of the umbra. This occurs, for example, during an eclipse of the Moon by the Earth—producing a faint, ruddy illumination of the Moon even at totality.

text: where R is the radius of the star, R is the occulting object's radius, and r is the distance from the star to the occulting object. For

text: Earth

text: , on average L is equal to 1.384

text: km

text: , which is much larger than the Moon's

text: semimajor axis

text: of 3.844 km. Hence the umbral cone of the Earth can completely envelop the Moon during a

text: lunar eclipse

text: . If the occulting object has an atmosphere, however, some of the luminosity of the star can be

text: refracted

text: into the volume of the umbra. This occurs, for example, during an eclipse of the Moon by the Earth—producing a faint,

text: ruddy

text: illumination of the Moon even at totality.

text: An annular solar eclipse will occur on November 28, 2095. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.

text: An annular

text: solar eclipse

text: will occur on November 28, 2095. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: annulus

text: With the high visibility KMA operated on a slogan of "Keep Millions Advised."  KFNF was to operate on "Keep Friendly, Never Frown."

text: Astronomy is a science that lends itself to the recording and study of observations: the vigorous notings of the motions of the stars, planets, and the moon are left on thousands of clay tablets created by scribes.  Even today, astronomical periods identified by Mesopotamian scientists are still widely used in Western calendars: the solar year, the lunar month, the seven-day week. Using these data they developed arithmetical methods to compute the changing length of daylight in the course of the year and to predict the appearances and disappearances of the Moon and planets and eclipses of the Sun and Moon.  Only a few astronomers' names are known, such as that of Kidinnu, a Chaldean astronomer and mathematician who was contemporary with the Greek astronomers. Kiddinu's value for the solar year is in use for today's calendars. Astronomy and astrology were considered to be the same thing, as evidenced by the practice of this science in Babylonia by priests. Indeed, rather than following the modern trend towards rational science, moving away from superstition and belief, the Mesopotamian astronomy conversely became more astrology-based later in the civilisation - studying the stars in terms of horoscopes and omens, which might explain the popularity of the clay tablets. Hipparchus was to use this data to calculate the precession of the Earth's axis.  Fifteen hundred years after Kiddinu, Al-Batani, born in what is now Turkey, would use the collected data and improve Hipparchus' value for the precession of the Earth's axis. Al-Batani's value, 54.5 arc-seconds per year, compares well to the current value of 49.8 arc-seconds per year (26,000 years for Earth's axis to round the circle of nutation).

text: Astronomy

text: is a science that lends itself to the recording and study of observations: the vigorous notings of the motions of the

text: star

text: s,

text: planet

text: s, and the

text: moon

text: are left on thousands of

text: clay tablet

text: s created by

text: scribe

text: s.  Even today, astronomical periods identified by Mesopotamian scientists are still widely used in Western calendars: the

text: solar year

text: , the

text: lunar month

text: , the

text: seven-day week

text: . Using these data they developed arithmetical methods to compute the changing length of daylight in the course of the year and to predict the appearances and disappearances of the Moon and planets and eclipses of the

text: Sun

text: and

text: Moon

text: .  Only a few astronomers' names are known, such as that of

text: Kidinnu

text: , a

text: Chaldea

text: n astronomer and mathematician who was contemporary with the Greek astronomers. Kiddinu's value for the solar year is in use for today's calendars. Astronomy and

text: astrology

text: were considered to be the same thing, as evidenced by the practice of this science in

text: Babylonia

text: by priests. Indeed, rather than following the modern trend towards

text: rational

text: science, moving away from

text: superstition

text: and

text: belief

text: , the Mesopotamian

text: astronomy

text: conversely became more astrology-based later in the civilisation - studying the stars in terms of

text: horoscope

text: s and

text: omen

text: s, which might explain the popularity of the clay tablets.

text: Hipparchus

text: was to use this data to calculate the

text: precession

text: of the

text: Earth

text: 's axis.  Fifteen hundred years after Kiddinu,

text: Al-Batani

text: , born in what is now Turkey, would use the collected data and improve Hipparchus' value for the

text: precession of the Earth's axis

text: . Al-Batani's value, 54.5 arc-seconds per year, compares well to the current value of 49.8 arc-seconds per year (26,000 years for Earth's axis to round the circle of

text: nutation

text: An annular solar eclipse occurred on May 9, 1948. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.

text: An annular

text: solar eclipse

text: occurred on May 9, 1948. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: annulus

text: Between two and five solar eclipses occur every year, with at least one per eclipse season. Since the Gregorian calendar was instituted in 1582, years that have had five solar eclipses were 1693, 1758, 1805, 1823, 1870, and 1935. The next occurrence will be 2206. On average, there are about 240 solar eclipses each century.

text: Between two and five solar eclipses occur every year, with at least one per

text: eclipse season

text: . Since the

text: Gregorian calendar

text: was instituted in 1582, years that have had five solar eclipses were 1693, 1758, 1805, 1823, 1870, and 1935. The next occurrence will be 2206. On average, there are about 240 solar eclipses each century.

text: The Solar Physics Laboratory works to understand the Sun as a star and as the primary driver of activity throughout the solar system. Their research expands knowledge of the Earth-Sun system and helps to enable robotic and human exploration.

text: Historically significant lunar eclipses are eclipses of the Moon that are mentioned in historical accounts in connection with a significant event. Lunar eclipses are somewhat rare events, although not as rare as solar eclipses, because unlike solar eclipses they can be viewed from anywhere on the dark side of the Earth. Throughout history lunar eclipses have been held to be responsible for such circumstances as lost battles, and have helped make possible extraordinary escapes.

text: Historically significant lunar eclipses are

text: eclipses of the Moon

text: that are mentioned in historical accounts in connection with a significant event. Lunar eclipses are somewhat rare events, although not as rare as solar eclipses, because unlike solar eclipses they can be viewed from anywhere on the dark side of the Earth. Throughout history lunar eclipses have been held to be responsible for such circumstances as lost battles, and have helped make possible extraordinary escapes.

text: An annular solar eclipse will occur on May 21, 2031. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.

text: An annular

text: solar eclipse

text: will occur on May 21, 2031. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: annulus

text: A partial solar eclipse occurred on October 12, 1996. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: occurred on October 12, 1996. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun