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[[File:lighterstill.jpg]][[File:Moon.jpg|right|frame]]

[[File:lighterstill.jpg]][[File:Moon.jpg|right|frame]]

The '''Moon''' is [[Earth]]'s only [[natural]] [[satellite]] and is the fifth largest [[satellite]] in the [[Solar System]]. It is the largest [[natural]] [[satellite]] in the [[Solar System]] [[relative]] to the size of its ''planet'', a quarter the [[diameter]] of [[Earth]] and 1/81 its [[mass]], and is the second densest satellite after Io. It is in [[synchronous]] [[rotation]] with [[Earth]], always showing the same face; the near side is marked with dark volcanic [http://en.wikipedia.org/wiki/Lunar_mare maria] among the bright ancient crustal [[highlands]] and prominent [http://en.wikipedia.org/wiki/Impact_crater impact craters]. Despite being the brightest object in the sky after the [[Sun]], its [[surface]] is actually very [[dark]], with a similar reflectance to coal. Its prominence in the sky and its regular [[cycle]] of [[phases]] have since ancient times made the Moon an important [[cultural]] [[influence]] on [[language]], the [[calendar]], [[art]] and [[mythology]]. The Moon's [[gravitational]] [[influence]] produces the [http://en.wikipedia.org/wiki/Ocean_tides ocean tides] and the [http://en.wikipedia.org/wiki/Tidal_acceleration minute lengthening] of the day. The Moon's current [[orbital]] distance, about thirty times the [[diameter]] of the [[Earth]], [[causes]] it to be the same size in the sky as the [[Sun]] – allowing the Moon to cover the Sun precisely in total solar [[eclipses]].

The '''Moon''' is [[Earth]]'s only [[natural]] [[satellite]] and is the fifth largest [[satellite]] in the [[Solar System]]. It is the largest [[natural]] [[satellite]] in the [[Solar System]] [[relative]] to the size of its ''planet'', a quarter the [[diameter]] of [[Earth]] and 1/81 its [[mass]], and is the second densest satellite after Io. It is in [[synchronous]] [[rotation]] with [[Earth]], always showing the same face; the near side is marked with dark volcanic [https://en.wikipedia.org/wiki/Lunar_mare maria] among the bright ancient crustal [[highlands]] and prominent [https://en.wikipedia.org/wiki/Impact_crater impact craters]. Despite being the brightest object in the sky after the [[Sun]], its [[surface]] is actually very [[dark]], with a similar reflectance to coal. Its prominence in the sky and its regular [[cycle]] of [[phases]] have since ancient times made the Moon an important [[cultural]] [[influence]] on [[language]], the [[calendar]], [[art]] and [[mythology]]. The Moon's [[gravitational]] [[influence]] produces the [https://en.wikipedia.org/wiki/Ocean_tides ocean tides] and the [https://en.wikipedia.org/wiki/Tidal_acceleration minute lengthening] of the day. The Moon's current [[orbital]] distance, about thirty times the [[diameter]] of the [[Earth]], [[causes]] it to be the same size in the sky as the [[Sun]] – allowing the Moon to cover the Sun precisely in total solar [[eclipses]].

The Moon is the only [[celestial]] [[body]] on which humans have made a manned landing. While the Soviet Union's [http://en.wikipedia.org/wiki/Luna_programme Luna programme] was the first to reach the Moon with unmanned spacecraft, the United States' NASA [http://en.wikipedia.org/wiki/Apollo_program Apollo program] achieved the only manned missions to date, beginning with the first manned lunar orbiting mission by [http://en.wikipedia.org/wiki/Apollo_8 Apollo 8] in 1968, and six manned lunar landings between 1969 and 1972 – the first being Apollo 11 in 1969. These missions returned over 380 kg of lunar rocks, which have been used to [[develop]] a detailed [[geological]] [[understanding]] of the Moon's [[origins]] (it is thought to have formed some 4.5 billion years ago in a giant impact), the [[formation]] of its internal [[structure]], and its subsequent [[history]].

The Moon is the only [[celestial]] [[body]] on which humans have made a manned landing. While the Soviet Union's [https://en.wikipedia.org/wiki/Luna_programme Luna programme] was the first to reach the Moon with unmanned spacecraft, the United States' NASA [https://en.wikipedia.org/wiki/Apollo_program Apollo program] achieved the only manned missions to date, beginning with the first manned lunar orbiting mission by [https://en.wikipedia.org/wiki/Apollo_8 Apollo 8] in 1968, and six manned lunar landings between 1969 and 1972 – the first being Apollo 11 in 1969. These missions returned over 380 kg of lunar rocks, which have been used to [[develop]] a detailed [[geological]] [[understanding]] of the Moon's [[origins]] (it is thought to have formed some 4.5 billion years ago in a giant impact), the [[formation]] of its internal [[structure]], and its subsequent [[history]].

Since the [http://en.wikipedia.org/wiki/Apollo_17 Apollo 17] mission in 1972, the Moon has been visited only by unmanned spacecraft, notably by Soviet [http://en.wikipedia.org/wiki/Lunokhod Lunokhod] rovers. Since 2004, Japan, China, India, the United States, and the [http://en.wikipedia.org/wiki/European_Space_Agency European Space Agency] have each sent lunar orbiters. These spacecraft have [[confirmed]] the [[discovery]] of lunar [[water]] ice in [[permanently]] [[shadow]]ed craters at the poles and bound into the lunar [http://en.wikipedia.org/wiki/Regolith regolith]. [[Future]] manned missions to the Moon are [[planned]] but not yet underway; the Moon remains, under the [http://en.wikipedia.org/wiki/Outer_Space_Treaty Outer Space Treaty], [[free]] to all nations to [[explore]] for [[peace]]ful [[purposes]].[http://en.wikipedia.org/wiki/Moon]

Since the [https://en.wikipedia.org/wiki/Apollo_17 Apollo 17] mission in 1972, the Moon has been visited only by unmanned spacecraft, notably by Soviet [https://en.wikipedia.org/wiki/Lunokhod Lunokhod] rovers. Since 2004, Japan, China, India, the United States, and the [https://en.wikipedia.org/wiki/European_Space_Agency European Space Agency] have each sent lunar orbiters. These spacecraft have [[confirmed]] the [[discovery]] of lunar [[water]] ice in [[permanently]] [[shadow]]ed craters at the poles and bound into the lunar [https://en.wikipedia.org/wiki/Regolith regolith]. [[Future]] manned missions to the Moon are [[planned]] but not yet underway; the Moon remains, under the [https://en.wikipedia.org/wiki/Outer_Space_Treaty Outer Space Treaty], [[free]] to all nations to [[explore]] for [[peace]]ful [[purposes]].[https://en.wikipedia.org/wiki/Moon]

==See also==

==See also==

*'''''[[Waning]]'''''

*'''''[[Waning]]'''''

[[Category: Astronomy]]

[[Category: Astronomy]]