Tethys

Tethys , in astronomy, one of the named moons, or natural satellites, of Saturn . Also known as Saturn III (or S3), Tethys is 659 mi (1060 km) in diameter, orbits Saturn at a mean distance of 183,093 mi (294,660 km), and has equal orbital and rotational periods of 1.8878 earth days. Tethys was discovered by the Italian-French astronomer Gian Domenico Cassini in 1684. Tethys's low density (1.2) implies that is composed primarily of water ice. The heavily cratered satellite has two dominant surface features: one is an impact crater—called Odysseus—about 250 mi (400 km) in diameter that is quite flat and without the high wall and central peak common on the moon; the other a huge valley—called Ithaca Chasma—that is 63 mi (100 km) wide, 2.5 mi (4 km) deep, and 1,250 mi (2,000 km) long, stretching three quarters of the way around Tethys's circumference. Tethys is co-orbital with two other moons; that is, they orbit Saturn at the same distance as Tethys but precede ( Telesto ) and follow ( Calypso ) Tethys by about 60°.

Tethys in Greek mythology, a goddess of the sea, daughter of Uranus (Heaven) and Gaia (Earth), and consort of Oceanus.

In astronomy, Tethys was the name given to a satellite of Saturn, the ninth closest to the planet and probably composed mainly of ice, discovered by Cassini in 1684. In geology, it is the name of an ocean formerly separating the supercontinents of Gondwana and Laurasia, the forerunner of the present-day Mediterranean.

Tethys The fifth-largest satellite of Saturn, average diameter 1060 km, sharing the same orbit as the much smaller moons Calypso and Telesto; also known as Saturn III. Its orbital distance is 294 700 km, and its orbital period 1.888 days, the same as its period of axial rotation. Tethys was discovered in 1684 by G. D.Cassini. It is densely covered with impact craters; one of these, Odysseus, is 440 km across, nearly half the satellite's diameter. Another prominent feature is Ithaca Chasma, a valley over 1000 km long, upto 100 km wide, and up to 3 km deep. Tethys has a density close to that of water, suggesting that it is composed largely of ice.