Dione and Tethys

Description

Cassini image of two of Saturn’s moons Dione (upper) and Tethys (lower). The planet’s rings are seen across the lower frame. Dione has a diameter of 1130 kilometres and is the densest of Saturn’s moons. Tethys has a diameter of 1060 kilometres and is composed almost entirely of pure water ice. The Cassini-Huygens spacecraft was launched in 1997 to investigate Saturn, its rings and its moons. This image was taken by Cassini’s narrow-angle camera on the 22nd September 2005 at a distance of 860,000 kilometres from Dione and 1.5 million kilometres from Tehtys. (Photo by Science Photo Library)