Varied terrain on Ganymede

Varied terrain on Ganymede

. The surface of Jupiterís largest moon, Ganymede, contains old, dark polygonal blocks frozen within its icy surface. They resemble brown, frozen-over continents floating on a background of translucent ice. The ancient blocks have apparently separated like the moving pieces of a huge mosaic or giant jigsaw puzzle, perhaps because of satelliteís crust has expanded. The brilliant, relatively young white material that surrounds some craters is probably fresh, clean water ice that splashed out from inside the satellite. The rays extending from the bright crater in the northern (top) part of this picture are up to 500 kilometers long. This image was acquired from the Voyager 1 spacecraft on 5 March 1979 (Courtesy of NASA and JPL.)

Copyright 2010, Professor Kenneth R. Lang, Tufts University