This image of Saturn's moon Dione was taken by NASA's Cassini spacecraft. It shows the moon's heavily cratered surface as well as the bright, wispy features that stand out prominently. Dione is 698 miles (1,123 km) in diameter, making it Saturn's fourth largest moon. Some of the craters on Dione are as large as 62 miles (100 km) in diameter. The bright, wispy areas were recently discovered to be bright ice cliffs created by tectonic fractures. Dione is composed mostly of water ice just like its sister moon, Rhea.