Saturn is similar to Jupiter, although about one-third the mass. A day on Saturn is only 10 hours and 39 minutes long; it spins so fast that its diameter at the equator is 10 percent larger than its diameter from pole to pole. However, its day is longer than that of Jupiter.
Saturn has a solid core likely made of rock and ice, which is thought to be many times the mass of Earth. Covering this core is a layer of liquid metallic hydrogen, and on top of that are layers of liquid hydrogen and helium. These layers conduct strong electric currents that, in turn, generate Saturn’s powerful magnetic field.
Saturn’s Moons
Saturn has 62 confirmed moons, and its largest moon is Titan, which is larger than Earth’s own moon and has a thick, opaque atmosphere.
Saturn’s Ring System
The most spectacular part of Saturn is its magnificent system of planetary rings, which stretch some 300,000 kilometers across. The ring system is divided into three main parts: the bright A and B rings and the dimmer C ring. There are many other fainter rings as well.
- The A and B rings are divided by a large gap called the Cassini Division, named after Gian Domenico Cassini.
- Within the A ring itself is another division, called the Encke Gap after Johann Encke, who first found it in 1837.
- Although these gaps appear to be completely empty, they are nonetheless filled with tiny particles, and, in the case of the Cassini Division, dozens of tiny ringlets.
- Although Saturn’s rings measure more than 100,000 miles across, they are only about a mile or so (one or two kilometers) thick. That is why they sometimes seem to disappear from view on Earth. When the orbit of Saturn is such that we see the rings edge-on, the rings look like a thin line and can be nearly invisible.
One idea about formation of Rings is that the rings were once larger moons that were destroyed, either by collisions, or by tidal interactions with Saturn’s gravity tearing them apart. The bits of moons then settled into orbit around Saturn.
Moons of Saturn
Saturn has 62 confirmed moons. Also like Jupiter, many of these are small moons that are likely to be asteroids captured in Saturn’s gravitational field.
Mimas
- Mimas, the victim of a huge cratering collision long ago, looks almost exactly like the fictional “Death Star” space station from the movies.
- Mimas has a diameter of 396 kilometers. It is the smallest known body in the solar system that became round because of its own gravitation.
Enceladus
- Enceladus was recently (2005) detected as having geysers of water shooting out from its surface, suggesting the presence of liquid water deep in its core.
- Enceladus is one of only three outer Solar System bodies (along with Jupiter’s moon Io and Neptune’s moon Triton) where active eruptions have been observed.
- The craters of Enceladus have been named Alibaba and Alladin.
Titan
- Titan is largest moon of Saturn and perhaps the most complex moon in the entire solar system. This is the only moon in solar system with a dense atmosphere.