Moon, Mare Imbrium, March 16, 2008. The Mare Imbrium, or "Sea of Rains" is a vast structure over a 1,000 km across, and easily visible from Earth without any optical aid. It shows a complex history of lunar geology with colossal impacts, lava flows, mountain building and flooded craters. This photograph was taken when the Moon phase was waxing gibbous, ten days after the new Moon.
The large crater to the lower left is Copernicus. It is about 93 km across, and its crater rays spread out 800 km over the lunar landscape. Mountain peaks separated by valleys rise from its floor. On the other side of Mare Imbrium, near the top of the photograph is the crater Plato. It is about 109 km across, and about four times older than Copernicus.
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