Credit: NASA/JPL-Caltech/Space Science Institute Public Domain — NASA Media Usage Guidelines

MOON

Tethys

Low-density icy moon with the giant crater Odysseus and the enormous rift Ithaca Chasma.

Orbits Saturn

Almost pure water ice (density just below that of water).
Odysseus crater spans 450 km u2014 40% of the moon's diameter.
Ithaca Chasma is a 2,000 km long rift, thought to have formed as the interior water froze and expanded.

About Tethys

Tethys is Saturn’s fifth-largest moon and one of the icy satellites observed by Cassini. Its density of 0.984 g/cm³ is just below water’s, implying it is composed almost entirely of water ice. Its surface is dominated by Odysseus, a giant multi-ring impact basin 450 km across, and by Ithaca Chasma, a 2,000 km long canyon system believed to have formed when Tethys’s global subsurface ocean froze and expanded the crust.

Live · 3DSee Tethys in the Live 3D Solar SystemFly to Tethys and explore its orbit among the planets, moons & spacecraft in a full-screen interactive view.Launch 3D view

Physical Properties

Mean radius531 km

Mass6.17449e20 kg

Density0.984 g/cm³

Surface gravity0.146 m/s²

Rotation period45.31 h

Bond albedo0.8

Mean temp86 K

Orbit

OrbitsSaturn

Semi-major axis294,672 km

Eccentricity0.0001

Inclination1.12°

Orbital period1.888 d

Gallery

Hand-picked mission imagery of Tethys sourced from NASA and partner archives. Click any photo for full resolution and source attribution.

Saturn's icy moon Tethys, from Cassini. NASA/JPL-Caltech/Space Science Institute · Public Domain u2014 NASA Media Usage Guidelines

Tethys and its large Odysseus impact basin. NASA/JPL-Caltech/Space Science Institute

Imagery on this page is provided by the original mission teams. Full attribution terms: Image Rights & Credits.

Sources & Further Reading

Numerical values (radius, mass, orbital elements, temperatures) are drawn from NASA NSSDC Planetary Fact Sheets, JPL Horizons, and the JPL Small-Body Database. Last refreshed: 2026-06-08 01:37:02.