Like 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. As a result, the lunar surface is pockmarked with impact craters dating back billions of years. The largest impacts created basins which then filled with molten lava creating areas known as maria, or seas, which appear darker to observers than the rest of the surface. This view was taken from the Lunar Module, whose shadow can be seen in the foreground. The Lunar Rover, used by NASA on its last three manned misions to the Moon, Apollo 15, 16 and 17, is parked near the left edge of the crater, giving some indication of its size.
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