Ganymede

Ganymede

. The surface of Ganymede, Jupiterís largest satellite, includes impact craters that suggest an age of a few billion years. The bright rays that surround many craters (lower left) probably consist of icy material thrown out by the impacts. Sinuous ridges and grooves traverse the surface (lower right) most likely caused by deformation of the thick ice crust from below. The Voyager 1 spacecraft took this image, about one thousands kilometers wide, on 5 March 1979. (Courtesy of NASA and JPL.)

Copyright 2010, Professor Kenneth R. Lang, Tufts University