Saturn is the sixth planet from the sun, and the second largest gas giant in the solar system. It takes twenty-nine and a half years to orbit the sun. Its name comes from Saturn (Kronos), the father of Jupiter.
One of the original five planets known in the ancient world, Saturn was included on all early astrological charts, along with the sun and the moon. Galileo Galilei discovered Saturn’s rings, although he did not recognise them for what they were, and was puzzled when they seemed to disappear at times. Christian Huygens was able to resolve them through greater telescopic magnification, through which he also discovered Titan, the largest of Saturn’s moons. Domenico Cassini added four more moons to the count. He also discovered the gap in the rings today known as the Cassini Division, which turned out not to be nearly as empty as previously thought. Fortunately for Voyager 1, the early plans to fly the probe through the Cassini Division were scrapped in favour of a more cautious approach.
Saturn’s ring systems were the first to be discovered in the entire solar system. Rhea, Saturn’s second largest moon, may even have a ring system of its own.
Thanks to the water ice of its rings, Saturn is one of the most brilliant objects in the night sky, with an albedo of 0.342. Pure water ice can have as high an albedo as 0.1.
This gas giant is approximately 95 times as massive as Earth, and 9.4 times as large as Earth at the equator. Yet for all its size, Saturn only has about a tenth the density of the Earth: and only about 2/3 that of water. If you could immerse Saturn into a large enough bowl of water, it would float.
The low density also affects the amount of gravity that Saturn is able to exert. A 100 kilogram object would weigh 107 kg on the surface of Saturn – if you could find that surface. Current measurements suggest that the atmosphere becomes denser and denser until it effectively becomes liquid.
That atmosphere consists of 96.3% hydrogen and 3.25% helium: not all that much different from the composition of a protostar. By comparison, the sun is made up of 73.46% hydrogen and 24.85% helium.
The winds on Saturn can reach over 2000 kilometres per hour at the equators: higher than atmospheric movement on any other planet of the solar system. The storms of Saturn are something to behold.
Although Saturn has at least 62 natural satellites (not counting the millions of particles making up the rings), Saturn’s largest moon, Titan, by itself makes up about 90 percent of the mass in orbit around Saturn. Titan, which is larger than both Mercury and Pluto, is the only natural satellite in the entire solar system which is known to have a dense atmosphere, and the only solar system object other than the earth itself on which there are stable bodies of surface liquid.
Speculation is high that Titan may support a form of previously unknown life. If such life did exist, it would have a methane-based metabolism in place of the familiar water-based metabolism of all terrestial life.