Saturn is the sixth planet from the sun, and the second largest in the solar system. Its equatorial diameter is 119,300km (74,130 miles). Much is known about Saturn because of the voyager explorations, which were in 1980-1981. A day on Saturn is 10 hours and 39 minutes long. A year on this planet lasts 29.5 Earth years. The atmosphere is composed of hydrogen with small amounts of helium, and also methane. Saturn is the only planet that is less dense than water, (by 30%). In fact, if a large enough ocean were found, Saturn would float in it.
Saturn has a hazy yellow colour, which is similar to, but fainter than that found on Jupiter. From Earth, we can see Saturn looking flatter at the poles. This is a result of fast rotation; it spins very quickly on its axis. It rotates faster than the Earth and most of the other planets. Wind speeds are incredibly high. Near the equator, where the wind is strongest, it can reach speeds of up to 500 metres a second, (1,100 miles an hour!)
Saturn's rings make it one of the most attractive objects in the solar system. It has many more rings than any other planet. The rings are made up of different parts. The rings are lettered in order of their discovery. There are bright A and B rings, and fainter C rings. Space probes have found that the main rings are actually made up of a large number of narrow ringlets. There are various gaps in between all the different rings. It is thought that the rings could be made from larger moons, which were shattered from the impacts of many comets and meteoroids.
The composition of the rings is not known for sure, but they contain large amounts of water. They are mostly made up of icebergs and snowballs that range in size from just a few centimetres to a few metres.
Using the first telescope, Galileo was the first person to discover Saturn's rings, in 1610. The gap between the A and B rings was discovered in 1675. The division that splits the A ring was discovered in 1837. Spokes have been found by the voyager on the B ring. They are thought to be made of fine dust particles.
The interior of Saturn is similar to that of Jupiter. It is made up of a rocky core inside, a layer consisting of mostly ice, a liquid hydrogen layer, and a molecular hydrogen layer. There are also traces of various ices present in the interior. The further you go into Saturn, the higher the pressure is. The ice layer is a soupy liquid made up of water, methane and ammonia at high temperatures, and under alot of pressure.
It is very hot inside the interior of Saturn. It is 12,000K (which is approximately 12,276C), at the core. Saturn radiates more energy out into space, than it receives from the sun. The energy that it radiates comes from Saturn's interior, where it was stored energy.
Saturn has 18 named moons. Saturn also has quite a large number of unconfirmed moons. They are unconfirmed because they have only been seen in one sighting. Most of them were sighted in 2000, by the voyagers. The names of Saturn's officially recognised and known moons are: Atlas, Calypso, Dione, Enceladus, Epimetheus, Helene, Hyperion, Iapetus, Janus, Mimas, Pan, Pandora, Phoebe, Prometheus, Rhea, Telesto, Tethys and Titana.
Saturn has a regular system of moons. Most of them orbit round the equatorial plane, and most of them are very similar to each other. Lots of them are composed of around 30-40% rock, and 60-90% water ice.
There have been many recent voyages to Saturn, to discover new moons, find temperatures, wind speeds, and learn many other new things. For example, voyager 1 discovered that Saturn's winds are ten times faster than the most vicious hurricane ever experienced on Earth round the equator. Voyager 2 helped scientists a great amount. It discovered that Saturn's rings are made up of tens of thousands of tiny ringlets. Scientists realised that this observation could help them learn alot more about the universe, and to understand the things going on inside it.
The Cassini mission to Saturn launched on October 15th 1997. It is the most ambitious effort in planetary space exploration to ever be mounted. It has a mass of 5,712kg. It consists of a space probe, a vehicle adapter, a 2,125kg orbiter, and 3,132kg propellants. The latest technology is being used. There are special camera systems in the orbiter, an imaging radar, instruments to measure the wind speed, and lots more inside the space probe. Saturn's largest moon, Titan has been studied in particular detail. Scientists think that the conditions on Titan are similar to those on Earth before life began.
Since its launch in Florida, Cassini has flown past other planets on its way to Saturn, to borrow gravitational energy. This is how it works: The planet pulls the Cassini round itself, due to gravitational effects, and accelerates it fast around the other side, to speed it on its way. The Cassini does not aim directly for the planet; otherwise it would be pulled in by the planet's gravity. The Cassini mission entered Saturn's orbit in July 2004, and descended onto the surface of Titan later that year.