Saturn, the sixth planet from the Sun, is the second largest planet in the solar system. It is ninety five times more massive than the Earth, and about nine times the size. Saturn is ten times further from the Sun than the Earth is. Like Jupiter it is a gas giant world, with a huge and thick atmosphere of mainly hydrogen and helium. This means that you could fly around the planet in an airplane and never see any solid ground underneath!
If you were diving into Saturn then for 600 miles you would pass through this gassy mix, which would slowly start thickening until became a huge ocean of liquid. Deeper still and this liquid becomes a type of metallic hydrogen, with temperatures reaching a roasting 20,000 F at Saturn’s core. There is possibly a ball of rocky material ten times the mass of the Earth sitting 37,000 miles below the planet’s surface, but scientists are still trying to find ways to find this out once and for all.
Saturn’s most amazing feature is the great system of rings that surround it. Although they look almost solid they are really made up of trillions and trillions of small icy particles, most the size of a speck of dust, some about the size of a small car. They are mainly made of water ice, a great glistening ring extending 50,000 miles out. If you look edge-on the rings seem to almost vanish because although they’re huge in diameter they’re only about thirty feet thick!
Image of Saturn’s rings, with some of its moons orbiting nearby.
Notice how thin the rings look when you look at them edge on.
Think about it
Where did Saturn’s rings come from? We don’t know all the answers yet, but they could be very old and perhaps from icy moons that smashed together and were torn apart by Saturn’s gravity. Some parts of the rings look much brighter than other parts, and just like snow on Earth, bright clean ice is probably young, dark and dirty ice is probably old. The bright, young ice in Saturn’s rings may come from new collisions and the breaking up of clumps of material. The rings orbit around Saturn at speeds as fast as fifteen miles a second – so they are incredibly busy places.
Image taken by the Cassini spacecraft in orbit around Saturn, looking down on part of the rings. All the gaps and different ring colors are clearly visible.
Saturn, like all the giant planets, has a lot of moons, about 62 in total. Some are small, barely a mile across. The largest is Titan, as big as the planet Mercury and the only moon in the solar system with a thick atmosphere. This far from the center of the solar system then sunlight is a hundred times fainter, only as bright as a cloudy day on Earth. For a moon like Titan that means the temperature is a bone-chilling -290 F on the surface. Titan’s thick atmosphere is made mostly of the gas nitrogen, together with some of the gas methane – the same stuff that we burn in our gas cookers here on Earth . It’s so cold though that methane turns into a liquid on the surface of Titan and there are lakes and seas of liquid methane sloshing around!
One of Saturn’s other moons, Enceladus, is causing a great deal of excitement. It is only about 300 miles across, but its surface is almost pure water ice. Little Enceladus is the most reflective natural object in the Solar System. It is also one of the most amazing places because there are jets of water shooting up from deep crevices on its surface. We think this means that there could be great caverns of liquid water hiding underneath the icy crust, and liquid water is something that all living things need to survive.
Because Saturn is so far away from the Earth it is incredibly difficult to explore. Only robotic spacecraft have ever been there. Most, like the Voyager spacecraft, just flew by taking pictures. The Cassini spacecraft went into orbit around Saturn, providing some of the stunning images like the ones on this page. It also sent a robot probe to Titan, where it floated down on a big parachute, sending back pictures all the time, until it reached the surface and sent back just a few pictures of the strange landscape of Titan. Cassini has also discovered the jets of water shooting out of the moon Enceladus.
On the left is an image of Titan taken by the Cassini spacecraft using its special infrared cameras. On the right is an image from the surface of Titan, sent back by the Huygens probe after landing. Lumps of frozen water and other chemicals look like rocks. If you stop to think about it, it is pretty amazing that we have a real life picture from the surface of a moon on the other side of the solar system!