This topographic map from NASA's Dawn mission shows the two large impact basins in the southern hemisphere of the giant asteroid Vesta. Rheasilvia, the largest impact basin, is 310 miles (500 ... more 
This topographic map from NASA's Dawn mission shows the two large impact basins in the southern hemisphere of the giant asteroid Vesta. Rheasilvia, the largest impact basin, is 310 miles (500 kilometers) wide. The other giant basin, Venenia, is less 
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SPACE.com | Photo By NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/PSI
Wed, Feb 13, 2013 1:24 PM EST