Young craters and deposits of volcanic rock highlight this enhanced-color view of Caloris Basin, the largest feature on the planet Mercury. The basin is an impact crater that's about a thousand miles (1,600 km) wide. The collision that created it may have created seismic waves that raced all the way around the planet, creating a region of jumbled terrain on the opposite side of Mercury. In this image, which is a mosaic of many images from the Messenger spacecraft, young craters (blue) show material excavated from deep below the surface. The bright orange regions around the basin appear to be recently deposited lava. [NASA/JHUAPL/Carnegie Inst. of Washington]