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Nine of Saturn's moons are in this image. Can you find them? Credit: NASA/JPL/Space Science Institute
With 62 moons, Saturn is only second in our Solar System to Jupiter, which has 63 satellites. Saturn also has the second largest moon in the Solar System, Titan, although up until the 1980’s scientists believed that Titan was actually the largest moon in the Solar System. This was because Titan is the only satellite in our Solar System to have such a dense atmosphere, which is mostly nitrogen. It was this dense atmosphere which made the moon appear larger than it really was. Christiaan Huygens discovered the first of Saturn’s moons, Titan, in 1655. The next four moons were discovered by Giovanni Domenico Cassini. He found Iapetus in 1671, Rhea in 1672, and Dione and Tethys in 1684. Another moon was not discovered around Saturn until more than a century later.
You can also check out these cool telescopes that will help you see the beauty of planet Saturn.
Despite having so many moons, most of the mass of the moons is accounted for by the seven largest – Titan, Tethys, Rhea, Mimas, Enceladus, Dione, and Iapetus. Titan alone makes up over 96% of the moons’ mass, the other six major moons make up about four percent, and the other 55 moons only account for 0.04% of the moons’ collective mass.
Iapetus is an odd moon with one half dark and the other half white; this is believed to be due to the ice melting on one half and leaving bare the darker organic material underneath. Tiny Mimas has a large crater on one side due to impact with another celestial body. Enceladus is one of the few volcanically active moons in the Solar System. Dione is comprised of a large percentage of water ice. Rhea is composed of an even higher percentage of water ice than Dione and is only approximately 25% rock. There is an impact crater on Tethys, Odysseus, which has a diameter of 400 kilometers, almost 40% of the moon’s diameter.
Saturn has many different categories of moons due in part to the planet’s ring system. Some of the categories include ring shepherds, irregular moons, Trojan moons, and co-orbitals. Ring shepherds are moons that orbit in or near planetary rings. Only Saturn has Trojan moons, which are moons that orbit at the Lagrange points. This means they are moons positioned at the right spot between two larger celestial bodies, so they actually remain stationary relative to the two objects – they move exactly in unison with the larger objects. Saturn has four Trojan moons – Telesto, Calypso, Helene, and Polydeuces. Co-orbitals are moons that orbit at the same or nearly the same distance from a planet. Janus and Epimetheus are two co-orbital moons of Saturn that appear as if they are going to collide, but instead switch orbits approximately every four years.
Universe Today has articles on how many moons does Saturn have and Iapetus.
You should also consider Titan’s rivers and lakes and Saturn’s moon.
Astronomy Cast has an episode on Saturn’s moons.
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