With the sun striking Mercury’s landscape at a low angle, MESSENGER got a great look at the hilly topography of a region along the southwestern rim of the Caloris Basin. This particular area had only previously been imaged by MESSENGER under direct sunlight, and thus the relief in the terrain was not nearly as evident.
Mercury’s Caloris Basin, measuring at 963 miles (1550 km) across, is one of the largest known impact sites in our solar system. It is estimated to be about 4 billion years old.
NASA’s MESSENGER spacecraft acquired this image on July 29, 2011. It shows an area 17 miles (28 km) across.
Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington