The Earth's moon. Galileo observed the moon through a telescope and thought that the dark areas were seas. This is why some areas of the Moon are named as seas.

A view of the Apollo 11 lunar module "Eagle" as it returned from the surface of the moon to dock with the command module "Columbia". 21 July 1969

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Mass 7.3483E+22 kgClip
Equatorial diameter 3474800 mClip
Mean orbital radius 384400000 mClip
Orbital period 27.32166d y=Earth year, d=Earth dayClip
Gravity at equator 1.62 ms-2Clip
Mean orbital velocity 1030 ms-1Clip
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Waning Moon
The moon between full and new when its visible part is decreasing.
Historical Notes
470BC Anaxagoras suggests that the Sun, Moon and stars are composed from the same matter as Earth.
450BC Anaxagoras proposes that the Moon shines with the light of the Sun and from this was able to explain the eclipses.
330BC Pytheas proposed that tides are caused by the Moon.
1504 Christopher Columbus correctly predicts the total eclipse of the moon.
1964 Unmanned U.S. spacecraft transmitted television pictures of the moon before hitting the surface.
1966 The first unmanned soft landing on the moon (Soviet Union).
1968 First manned flight around the moon is made by Frank Borman, James Lovell and William Anders in Apollo 8.
1969 Apollo 11 crew make the first human landing on the moon. Neil Armstrong steps on the moon.
1972 Eugene Cernan and Jack Schmitt in Appolo 17 are the last to land on the Moon.

See also: Earth, Earthlight, Halo, Lunar Gravity, Metonic Calendar, Pericynthian, Selenoid, Selenology, Sun.

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Subjects: Astronomy Physics

NASA Photographic Library Photographs from NASA available for viewing and download.
Phases of the Moon US Naval Observatory Astronomical Applications Department.
Apollo Image Archive A digital archive of all the original Apollo flight films.
The Nine Planets A Multimedia Tour of the Solar System: one star, eight planets, and more.