A lesser-known moon, Calypso orbits Saturn in the same path as Tethys and another miniature moon called Telesto. Known as the “Tethys Trojans”, these two oblong-shaped moons were discovered in 1980 by Earth-based telescopes and eventually photographed by Cassini.

The moniker “trojan” in astronomy is reserved for satellites that orbit a planet in the same orbit as another larger moon. The smaller moons are held in place by the gravitational pull of the larger moon and the planet itself, in a position known as a Lagrange point. Tethys’ Lagrange points, where the moons Calypso and Telesto lie, are 60º before and behind it respectively.

Calypso is approximately 19 miles long by 10 miles wide.

Image credit: NASA/JPL/SSI