Tethys (moon)

Tethys (pronounced TEE-this)^[1][2] is a large moon of the planet Saturn.

Photo taken by Cassini-Huygens.

Discovery

It was discovered by Giovanni Domenico Cassini in 1684.^[1][2] It was one of the first Saturnian moons discovered.

Physical characteristics

Mass, density and volume

Tethys' mass is 617,551,805,221,061,000,000 kg, its density is 0.973 g/cm³ and its volume is 634,264,255 km³.^[3]

Craters and valleys

It has a very large crater on its surface, called Odysseus.^[1] It is named after a Greek warrior king in Homer's two great works, The Iliad and The Odyssey.^[1] There is also a very long valley called Ithaca Chasma. It is 100 km wide and 2000 km long.^[1][2]

Orbit and rotation

Tethys takes 45.3 hours to orbit (go around) Saturn^[2] and orbits Saturn 294,660 km away.^[2] Tethys is tidally locked in phase with its parent planet - one side always faces toward Saturn.^[1]