Saturn

planet Saturn

Because of Saturn's rings it is considered one of the most interesting and beautiful of all of the planets in our solar system.

Saturn is the sixth furthest planet from our Sun and is a gas planet like Jupiter, Uranus, and Neptune. Saturn is also comparable in size to Jupiter, but slightly smaller. However, despite Saturn's large size, its density is very low - even lower than the density of water. In fact, Saturn would float if you could find a large enough body of water to set it in.

Saturn takes 29.6 Earth years to make one complete orbit around the Sun, and makes one complete rotation on its axis every 10 hours and 39 minutes (Spinrad, 2004), which is much faster than Earth's 24 hour rotation.

Saturn's Moons

Saturn has 31 moons, four of which you can see as the very small objects in the image of Saturn. The three moons that appear lighter against the dark background of space are Tethys, Dione, and Rhea. You can see Saturn's small moon Mimas as a small dark spot against the background of the planet itself.

One of Saturn's most interesting moons is Titan. Scientists find Titan interesting because they believe that it has an atmosphere of hydrocarbons and that there may be significant amounts of frozen water ice on its surface. The reason this is interesting is because the presence of water is thought to be a necessary component of life. Scientists also look for the presence of carbon containing compounds when searching for conditions that may be conducive to supporting life. Also see the article Is There Life on Other Planets?.

Saturn's Atmosphere and Internal Structure

Saturn's atmosphere is similar to Jupiter's, consisting of mostly hydrogen and helium and a few other trace gases. Saturn has much less helium in its atmosphere than Jupiter does, however.

Saturn's clouds are arranged in three layers. The outer layer is composed of ammonia ice, the middle layer consists of ammonium hydrosulfide, and the inner layer consists of water ice. This is identical to the cloud layers on Jupiter, however, the cloud layers on Saturn are much thicker than those of Jupiter (Chaisson and McMillan, 2005).

Also like Jupiter, Saturn radiates more heat than it absorbs from the Sun.

Saturn is thought to have a rocky core, surrounded by molecular hydrogen, which is surrounded by the gaseous atmosphere. Saturn has a stronger magnetic field than Earth, but less strong than Jupiter's.

Saturn's Rings

Saturn's rings

There are two theories about why Saturn has rings. One is that the rings consists of particles from moons that were broken off when they were hit by space debris such as asteroids or meteors.

The other theory is that the rings consist of material that formed from moons or other large objects that were destroyed when they came too near to the planet because of the planet's tidal force. The theory is that the tidal force is greater than the forces holding the moon together. This means that a moon that comes too close to the planet would break up into pieces and then these pieces would orbit the planet (Chaisson and McMillan, 2005).

It is also possible that because of the tidal force the debris that makes up Saturn's rings never formed a moon at all, but remained as rock and ice particles in orbit around Saturn and may be left over particles from when Saturn was formed (Chaisson and McMillan, 2005).

It is interesting to note that all of the gas planets (Jupiter, Neptune, and Uranus) have rings around them, but not to the extent that Saturn does.

Despite their huge diameter, the rings are very thin. They consist of rocky particles covered in ice, or ice balls. Both of these particle types reflect sunlight. These particles range in size from very small to large boulder-sized rocks. The rings are named by letters of the alphabet in order of their discovery with A being the first ring discovered.

Starting from the outer edge of the rings (furthest from the planet), the rings are known as E, G, F, A, B, C, and D.

As you can see by the names of the rings, they weren't discovered in their order of distance from the planet.

Saturn also has lots of very large storms. When they occur, these storms appear as white spots on the planet's surface.

REFERENCES

Chaisson, E. and McMillan, S. (2005). Astronomy Today. Pearson Prentice Hall: Upper Saddle River, NJ.

Spinrad, Hyron. "Saturn." World Book Online Reference Center. 2004. World Book, Inc. http://www.worldbookonline.com/wb/Article?id=ar492440

Image of Saturn and 4 moons: NASA/JPL-Caltech.
Image of Saturn rings: Courtesy of NASA Marshall Space Flight Center (NASA-MSFC).