|Diameter||3476 km, 0.27 x Earth's|
|Average Distance from Earth||384400 km = 0.0025 AU|
|Time to orbit Earth||27.322 days|
|Time to spin once||27.322 days|
|Gravity||1/6 (0.16) of Earth's|
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
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. 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.
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.
Authors: Carolyn Brinkworth and Claire Thomas
Last updated: July 2001