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The Moon

Diameter3476 km, 0.27 x Earth's
Mass0.012 ME
Volume0.02 VE
Average Distance from Earth384400 km = 0.0025 AU
Night: -233°C
Time to orbit Earth27.322 days
Time to spin once27.322 days
Gravity1/6 (0.16) of Earth's

Buzz Aldrin in the Command Module

The Moon is the only object orbiting the Earth that is not man-made. It is also the only other place in the Solar System that has been visited by humans. Neil Armstrong Gene Cernan salutes the American flag and Buzz Aldrin became the first men on the Moon on 20th July 1969. A total of twelve men walked on its surface, and the last to leave was Gene Cernan on December 19th 1972.

The Moon lots of craters caused by meteorites crashing into the surface. Craters on the Moon It also has large flat areas called maria. Scientists think that they are made by huge lava flows filling up massive impact craters then solidifying.

Rocks on the surface of the Moon The types of chemicals found in Moon rocks are very similar to those in Earth rocks. This means that Moon and Earth rocks probably came from the same place. Scientists now think that that the Moon used to be part of the Earth, but a huge Mars-sized rock smashed into the Earth and blew a big chunk of it off into space. This chunk formed into the Moon.

There is no life on the Moon, and up until a few years ago we thought there was no water either. Then the Moon was visited by two NASA spacecraft: Clementine and Lunar Prospector. Both spacecraft seem to have found ice in the shadowy craters at the north and south poles.

Earthrise, as seen by the Apollo 11 astronauts

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Extra-Solar Planets

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Authors: Carolyn Brinkworth and Claire Thomas

Last updated: July 2001