This picture was taken by the Apollo 11 astronauts on their way back to Earth after their historic succesful first lunar landing. The Moon is believed to have formed over 4 billion years ago from material ejected from the Earth as the result of a huge collision between Earth and another Mars-sized planetary body. In common with all the other planetary bodies in the Solar System, the Moon has been subjected to a continuous bombardment from space by meteorites and asteroids of various sizes. The darker areas, known as maria (seas), are basins created by huge impacts, which then flooded with molten lava. They are more recent features than the lighter coloured heavily cratered highlands.
© National Aeronautics & Space Administration / Science & Society