Saturn's Moons

Saturn has 18 known moons. It is possible that Cassini will discover more. Saturn's moons range in size from smaller than an asteroid to larger than the planet Mercury. More moons of greater variety orbit Saturn than any other planet. They are listed first is Atlas, Calypso, Dione, Enceladus, Epimetheus, Helene, Hyperion, Iapetus, Janus, Mimas, Pan, Pandora, Phoebe, Prometheus, Rhea, Telesto, Tethys, and Titan.

All these moons (plus any new ones found) will be studied by Cassini, but the most extensive study will be the Huygens probe on Titan.

Titan: The only Saturn moon that has ever had a probe land on it: Huygens, a lander carried to the hazy world by the spacecraft Cassini. Titan’s “Earth-like processes” and thick atmosphere are among the things that make this world stand out to scientists. Ethane and methane rains from the atmosphere and flows on the surface.

A fish-eye view of Titan’s surface from the European Space Agency’s Huygens lander in January 2005. Credit: ESA/NASA/JPL/University of Arizona

Enceladus: An extremely reflective moon because it is made up of water ice. It’s also quite cold at minus 330 degrees Fahrenheit (minus 201 degrees Celsius). The moon has at least five different kinds of terrain, a “young” geological surface of less than 100 million years, and a possible liquid interior. The moon is also known for its ice plumes. 

Rhea: Rhea has at least two major sections: bright craters with craters larger than 25 miles (40 kilometers), and a second section with smaller craters. “This difference may indicate there was a major resurfacing event some time in Rhea’s history,” NASA stated. 

Mimas: Some people jokingly call it a “Death Star” because of the crater in its surface that resembles the machine from the Star Wars universe. The 88-mile (140-kilometer) Herschel Crater is about a third the diameter of the moon itself. The huge impact also could have created fractures (chasmata) on the moon’s opposing side. There are in fact craters throughout the moon’s small surface, making it among the most pockmarked in the Solar System. 

A view of Saturn’s moon Mimas from the Cassini spacecraft. Credit: NASA/JPL/Space Science Institute

Pan: Considered a “shepherd satellite” as it orbits within the Encke Gap of Saturn’s A ring and keeps the gap from being filled in with ring material. Its motions also make stripes (“wakes”) in the rings on either side of it. Pictures obtained at a distance show it looks something like a walnut.

Tethys: An airless moon that has a huge impact crater (called Odyssey Crater, 250 miles or 400 kilometers in diameter) — about two-fifths of Tethys’ diameter. It also has a large valley called Ithaca Chasma, which is 62 miles (100 kilometers) wide.

Dione: A moon that appears to have spun about 180 degrees, perhaps due to a large impact. It’s covered in canyons, cracking and craters and is coated from dust in the E-ring that originally came from Enceladus.