Tethys is one of the midsized icy satellites of Saturn. Discovered by Giovanni Domenico Cassini in 1684, it orbits at a distance of 294,700 km (or 4.9 Saturnian radii) from Saturn. Its diameter is 1,060 km. Images taken by the Voyager 2 spacecraft in 1981 show a variety of terrains, with some ancient, heavily cratered regions including the large Odysseus basin that is over 400 km in diameter and a more recent, remodeled surface with a large canyon, Ithaca Chasma, which is about 1,000 km long and 100 km wide. The density of Tethys is 1.0 g/cm3, which indicates a rather pure water-ice satellite. Two other small satellites, Calypso and Telesto, are located on the same orbit as Tethys.