Bright moon of SaturnA crack across an icy world
Tethys
Tethys is a brilliant ice moon scarred by a canyon that runs most of the way around its circumference.
- Host
- Saturn
- Type
- Bright icy moon
- Mean diameter
- 1,062 km
- Mean orbital radius
- 294,660 km
- Orbital period
- 1.89 days
- Surface gravity
- 0.145 m/s²
- Key feature
- Ithaca Chasma
- Discovered
- 1684 · Giovanni Cassini
Tethys up close
NASA imagery
An ice world in full light
Tethys reflects most of the sunlight that reaches it. Its surface is dominated by water ice, with impact craters and broad smooth plains that record a long history of collisions.
The 450-kilometre Odysseus crater is one of the largest relative to its host world. The impact may have fractured the lithosphere and influenced the formation of nearby tectonic features.
Ithaca Chasma
Ithaca Chasma is a vast canyon system roughly 2,000 kilometres long, up to 100 kilometres wide and several kilometres deep. It wraps around much of Tethys like a seam.
Its origin may involve cooling and expansion of the moon's interior after the impact that formed Odysseus. Tethys has little visible volcanic activity now, but its scars reveal a geologically active past.
Worth knowing
Tethys shares its orbit with two much smaller Trojan moons, Telesto and Calypso.
Ithaca Chasma is longer than the distance from Paris to Cairo.
Giovanni Cassini discovered Tethys in 1684, along with Saturn's moon Dione.
Watch and explore
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A Canyon Around an Entire Moon SpaceAtlas
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Research & further reading
Mission imagery and measurements are interpreted alongside orbital data. Follow the source links for the current NASA overview and precise satellite parameters.