major moon · moon of Saturn
Tethys
An icy moon of Saturn made almost entirely of water ice, marked by the huge crater Odysseus and the vast canyon Ithaca Chasma.
- Distance from Earth today
- 1.28 billion km8.573 AU · light: 1 h 11 min
- Distance from the Sun today
- 1.41 billion km9.425 AU
- As of
- 4 November 2026position from NASA/JPL orbital elements
Where it is today
Top view of the plane of Earth’s orbit, compressed distance scale. Open on the big map with the time slider →
Facts
- Diameter
- 1,062 km
- Mass
- 617 × 10¹⁸ kg
- Density
- 984 kg/m³
- Mean distance from the planet
- 295,000 km
- Orbital period
- 45.3 h
- Orbital eccentricity
- 0.0010
- Orbital inclination
- 1.1°
Source of the figures: JPL SSD – Planetary Satellites (public domain).
Discovery: 1684 – Giovanni Domenico Cassini
Description
Tethys is a mid-sized moon of Saturn discovered by Giovanni Domenico Cassini in 1684. Its low density means it is made mostly of water ice with very little rock. Two features stand out: Odysseus, an enormous impact crater, and Ithaca Chasma, a canyon system that runs across a large part of the globe. Tethys shares its orbit with two tiny Trojan moons, Telesto and Calypso, which travel ahead of and behind it. It was imaged by Voyager 1 and 2 and studied in detail by Cassini.