Introductory Astronomy: The Planet SATURN

Basic Facts:
Average distance from Sun: 9.54 AU
Period of revolution about Sun: 29.5 years
Period of rotation: 10.67 hours
Radius: 9.4 Earth radii
Mass: 95 Earth masses
Average Density: 0.7 g/cm^3
Magnetic Field: 1000 times Earth's
Surface features: Extensive ring system, methane clouds
Atmosphere: 92.4% H2, 7.4% He, 0.2% Methane, 0.02% ammonia
Temperature: -285 degrees Fahrenheit

Like Jupiter, Saturn has high and low pressure zones in its atmosphere. The winds in the zones actually have speeds up to three times faster than Jupiter's zones. However, because these zones are buried deep in the atmosphere beneath a layer of methane haze, they are not as noticeable as on Jupiter. In addition, Saturn (like Jupiter) has a hot interior and radiates more energy than it receives from the Sun.

Saturn is the most oblate of the gaseous planets. This means that it is the least spherical; its equatorial diameter is larger than its polar diameter. This occurs because of its rapid rotational period: Saturn (which is about 9.5 times larger than Earth) rotates more than twice as fast as the Earth.

The most spectacular feature of Saturn is the ring system. The rings are made of billions of small icy particles. They are not continuous but contain gaps and ringlets (tiny rings), making them appear much like the grooves on a record. The major gaps are caused by gravity from the moons; at these places, the particles in the rings feel strong gravitational pulls from BOTH Saturn and one of its moons, causing the particles to move either closer to Saturn or closer to the moon. As the particles move, a gap forms at this position (which is called a resonance). The largest of these gaps is visible from Earth and is known as Cassini's division. The origin of the rings is not well known; however, many scientists believe that they may be the remains of an icy moon which was shattered by the impact of a comet. The rings also have spokes (which extend radially from Saturn, just like spokes on a bicycle). The spokes are caused by Saturn's magnetic field.

Saturn has at least 18 satellites, all of which contain large amounts of ices mixed with rock. A view of Saturn with some of its moons. The largest is Titan , which is actually larger than the planet Mercury. Recent studies show that the greenhouse effect is present on Titan (like on Venus and the Earth). It is caused by the methane and hydrogen gas in Titan's atmosphere.

To learn more about Saturn, its moons, and rings, click here.