Callisto

Callisto

. Jupiter’s outermost large moon Callisto exhibits more craters and older terrain than seen on any of the Galilean satellites. It is a battered world, pockmarked with impact craters dating back to the final stages of planetary formation over 4 billion years ago. Because Callisto’s icy surface is as rigid as steel, it retains the scars of an ancient bombardment similar to the one that created the heavily cratered terrain on the Moon and Mercury. The bright regions probably contain fresh crustal ice thrown out from relatively young impact craters, and splashed upon the older, dirtier surface ice. This image was acquired in May 2001 from the Galileo spacecraft. (Courtesy of NASA, JPL and DLR – the German Aerospace Center.)

Copyright 2010, Professor Kenneth R. Lang, Tufts University