During its approach to the solar system's innermost planet, NASA's Messenger probe took this image of a crescent Mercury. The spacecraft was still an hour and a half from its closest encounter when it imaged this terrain, which hadn't been seen on Messenger's first flyby or by the Mariner 10 spacecraft, which flew by Mercury in 1974 and 1975. The image is one of a set of 11 taken through different filters to study the colors of the surface.

Photo: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington