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Stardate: 09:06:97
Saturn, the jewel of the solar system Saturn and arguably the most beautiful object in the solar system for amateur astronomers, offers us a view of it's magnificent ring system this week, and throughout the end of the year.
Ever since their discovery by Galileo in 1609, the rings of Saturn have delighted astronomers, amateur and professional alike.
Saturn has a mass over 95 times that of Earth, and orbits the Sun at a distance 9.5 times greater than the distance between the Earth and the Sun. Saturn also has a diameter 9.4 times that of the Earth, and rotates once every 10 hours, and 39 minutes, similar to the rotational period of Jupiter.
One surprising aspect
of Saturn is it's very low density. In fact, the density of Saturn is only
70% that of water. What this means is, that if you could find a pool of
water large enough, Saturn would float! This is the only planet in our solar
system which fits this description. Saturn is composed of a rocky/ice core,
surrounded by a layer of metallic hydrogen. Of course, the pressure inside
of Saturn is so great, that the rocky/ice core is very different from the
rock and ice we are familiar with here on Earth! Although the great pressures
towards the core of Saturn create very high temperatures, the temperature
at the cloud tops of this giant world is only -180 degrees c (-292 degrees
f).
The rings of Saturn are designated by letters, A-F for the major rings, but observations done by the Voyager spacecraft revealed Saturn's rings are, in fact, composed of hundreds of tiny ringlets, similar to a phonograph record. These ringlets seem to be held together by what are known as shepherd moons - sets of tiny moonlets which, by their gravity, keep these ringlets in a tight, orderly form.
There are gaps in the rings, caused by resonance, the largest of which was discovered by an astronomer named Giovanni Cassini, and the gap is named the Cassini division in his honor. The ring system, including the Cassini division, is visible with even a small telescope, or a pair of binoculars. Also named in Cassini's honor is the Cassini probe, the next major planetary probe to visit the most brightly ringed planet.
Saturn's largest moon, Titan, is the largest moon in the solar system, surpassing even the planet Mercury in diameter. Titan will be the focus of next weeks article, and will be the target of the Huygen's probe, which will be launched from the Cassini spacecraft when that craft reaches the planet. Look for Saturn to rise about 8:30 pm in the southeast, and be due south by 3 am. By 10 pm, Saturn will be found 14.5 degrees above the southeast horizon.
Clear skies, and good viewing.
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