In this mosaic of what NASA calls the "eastern limb" of Mercury, from the January 2008 flyby (the first of the three by Messenger), the large gold-hued circular area is the Caloris basin, notable for its volcanic plains. The basin is about 960 miles in diameter, and Messenger was passing by at a distance of about 8,000 miles.
March 17, 2011 4:00 AM PDT
Photo by: NASA/Johns Hopkins University Applied Physics Laboratory/Arizona State University/Carnegie Institution of Washington
| Caption by: Jonathan Skillings
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