Crater on Mercury. View of a 14-kilometre diameter crater on the surface of the planet Mercury. This crater is relatively young, as indicated by the bright rays that cross the neighbouring features. A dark 'tongue' of impact melt, which has a bluer colour than the nearby surface, appears to have flowed out of the crater. Imaged by NASA's MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) spacecraft, on 16th May 2011.