Tethys

Tethys is one of the seven regular moons of Saturn. This moon contains two other irregular moons within its orbit. Learn all about Tethys here!

Formation

Tethys is believed to have formed within the context of the early Saturnian system's evolution. Current theories suggest that Tethys, like other moons and planets, emerged from the protoplanetary disk of gas and dust encircling the young Sun. Particles within this disk collided and aggregated under the influence of gravity, forming progressively larger objects. Tethys likely developed within Saturn's circumplanetary disk, closer to the planet. Its composition, predominantly comprising water ice and rocky material, was influenced by conditions specific to its location within the disk. Following its formation, Tethys is thought to have undergone internal differentiation, with denser materials settling into its core and lighter materials forming its icy mantle.

Surface

Tethys exhibits a diverse and intriguing surface. Its most notable feature is the enormous impact crater known as Odysseus, spanning approximately 400 kilometers (250 miles) across and nearly 5 kilometers (3 miles) deep. The crater's size relative to the moon has led to a spherical appearance for Tethys. Besides Odysseus, the moon's surface showcases a mixture of terrains including smooth plains, icy ridges, and numerous smaller craters, providing insights into its geological history. One such ridge, called Ithaca Chasma, stretches across Tethys' surface, suggesting tectonic activity and possibly linked to the moon's internal processes.

Structure

Tethys is believed to possess an internal structure consisting of a rocky core surrounded by an icy mantle. This internal differentiation is inferred from its overall composition and the behavior of its gravitational field. The presence of the huge impact crater Odysseus suggests that Tethys was heated and partially melted in its past, contributing to the differentiation process. Tethys is thought to have undergone limited geological activity in comparison to some of Saturn's other moons, and its relatively smooth surface could be the result of resurfacing by internal processes.

Satellites

Tethys was visited by the Cassini spacecraft during its mission, providing a wealth of observations and data. Cassini conducted close flybys of Tethys, revealing its diverse surface features including the massive impact crater Odysseus, icy ridges, plains, and craters. Notably, the prominent Ithaca Chasma, a lengthy canyon-like structure, was also observed, indicating potential tectonic activity. The spacecraft's instruments analyzed Tethys' composition, temperature variations, and gravitational field, yielding insights into its internal structure and geological evolution. Cassini's observations enriched our understanding of Tethys' role within Saturn's moon system and its interactions with other moons and the planet's rings.