Saturn's moon Enceladus, Cassini image. Enceladus, the sixth-largest moon of Saturn, is 500 kilometres in diameter. It is a frozen world with a surface consisting mostly of water ice. This is the trailing hemisphere of Enceladus, the side that always faces away from its direction of orbit. The icy landscape includes impact craters, deep canyons, and numerous ridges and troughs caused by internal pressures and tectonic activity. The area at centre right is Sarandib Planitia, and is a younger, more active region than the cratered area at upper left. This image is a mosaic of 16 separate images obtained by the Cassini spacecraft on 17 February 2005.