(c) Anthony K. Grafton 2003

Our Solar System, Part 6: Saturn: A Ringed Giant

Like Jupiter, the planet Saturn is known as a gas giant since it is made of most hydrogen, helium, and methane gas. But the real reason that people remember Saturn is for its spectacular rings.

Around three hundred years ago, an astronomer named Giovanni Cassini was the first person to study Saturn in detail. He was also the first person to discover that the apparently solid ring system around Saturn had a noticeable gap in it.

Modern observations by the Voyager and Pioneer space probes have shown us that Saturn actually has many rings, but the separation is hard to see with simple ground-based telescopes. Each ring is made up of many small particles orbiting around the giant planet. Some of the rings contain chunks of rock and debris up to a few meters in size, but most of the rings are made up of bits of material no larger than sand and dust.

In 1997, NASA launched a probe named after the astronomer Cassini. This probe will arrive at Saturn in July, 2004, and study the planet, its rings, and its moons for four years. Six months after it arrives the gas giant, the probe will release a smaller craft that will dive into the atmosphere of Titan, Saturn’s largest moon, and land on its surface. Titan is one of the largest moons in our solar system (it is even larger than the planet Mercury), but it is covered by a thick, cloudy atmosphere, so scientists are eager to learn what lies beneath.

Because Saturn is tilted, its rings seem to change orientation (as viewed from the Earth) as it orbits around the sun. Sometimes the rings become almost invisible to us when they appear “edge-on”. This variation in our view of the rings occurs on a 15-year cycle, with the next “greatest” view of the rings coming up in 2003.

Can you find the location of Saturn in the night sky? If you can, and you have a small telescope, write to Science Corner and report how many of its moons you can make out.