Boulders on an otherwise smooth floor are seen on the Mare Tranquillitatis pit crater on the surface of the Moon in this NASA image taken by the NASA's Lunar Reconnaissance Orbiter and released September 14, 2010. When the Sun is well overhead, the floor of the Mare Tranquillitatis pit is illuminated. Scientists estimate the depth to be a bit over 100 meters. REUTERS
The surface of the moon
A surprising new view of the moon comes from detailed gravity mapping by twin spacecraft, which slipped into orbit around the celestial body earlier this year.