What planet is the most interesting to you? Saturn is a puzzling planet and has been since Galileo discovered it had “bumps” on its sides. When he first observed it, he thought he might be seeing three planets! As mysteriouslyas they appeared, these “bumps” disappeared, so he began to wonder if he had ever seen them at all! Later astronomers discovered that the bumps Galileosaw were actually numerous rings, with spaces in between them. Even today, people are still able to watch Saturn's bumps or rings appear to come and go. The reason we see this is Saturn has a tilt just like Earth does, so the rings seem to disappear when you are looking at its equator. Although Saturn is famous for its rings, it isn't the only planet with rings. All of the jovian or gas planets have them, which includes Jupiter, Uranus, and Neptune. One reason no one knew the other planets had rings is because Saturn's could be seen from Earth, but the others weren't seen until space probes found them. The probes also showed that Saturn had many thousands of rings and even more gaps in between them. They also found tiny moons that seem to keep the spaces between the rings open and other moons that appeared to attract the particles and hold them in the rings. You may be wondering what these particles are and how they got into the rings? Many of them appear to be made of ice and some of them appear bigger than boulders. If you remember that the earth and its moon developed bulges as they pulled on each other's surfaces, the same may be true for Saturn's less compact moons. If they are tugged close enough to the planet by its strong gravity, scientists believe the moons could be pulled apart. Others believe the particles are left over from the creation of the solar system. Most people who study astronomy admit they really don't know.

Can You Top This?

Did you ever play a game called “Can You Top This?” You pull an activity to do out of a hat, then others try to top it by adding more details, like hopping on one foot, while rubbing your head and patting your stomach, and so on. Even in space, it seems one thing is trying to out do another. For example, Saturn's moons come close to being even more interesting than its rings. As you study the outer planets it is almost as though Jupiterand Saturn were trying to form their own solar systemsas they orbited around the sun. Only Jupiter's moon Ganymede is larger than Saturn's big moon, Titan, and both of them are bigger than Mars, Mercury, and Pluto. Most moons have little or no atmosphere, but Titan has a thicker atmosphere than Earth's. Have you ever seen a model of Earth, the other planets, and our moon? Imagine what Saturn's model would look like. A planet with thousands of bands of rings made from hundreds of thousands of pieces of rock or ice.

The Big Bucket

Saturn is huge but weighs so littlethat it could float in a bucket of water. Complete the equations to learn how big this bucket would need to be!

AMAZING ASTRONOMY

The main rings of Saturn stretch more than a hundred thousand miles across space, but guess what? They are only 500 feet thick!That's like coveringa soccer field with a singlethickness of newspaper!

Astronomers knew most of the icy moons were there long before space probes sent back the news about the unknown tiny ones. Some of these moons are inside Saturn's rings. Two of them seem to be playing chase, switching orbits as they pass each other, while two or three other moons share the same orbit. Another little, strangely shaped moon speeds up and down as it rotates, while it spins like a child's top on its side! Saturnalso has a medium-sized moon that seems to shine with an ice coating of water possibly due to geysers like Old Faithful, while most of the other moons are covered with craters. Can you imagine what a sight it would be to stand on Saturn and have five moons circling around you? Like here on Earth, Newton's gravity is controllingall of these objects as well, even telling the chasing moons when it is time to switch orbits!