Saturn is the second biggest planet in the Solar System – 815 times as big in volume as the Earth, and measuring 120,000 km around its equator.
Saturn takes 29 and a half years to travel round the Sun, so Saturn’s year is 29.46 Earth years. The planet’s complete orbit is a journey of more than 4.5 billion km.
Winds ten times stronger than a hurricane on Earth swirl around Saturn’s equator, reaching up to 1,100 km/h – and they never let up, even for a moment.
Saturn is named after Saturnus, the Ancient Roman god of seed-time and harvest. He was celebrated in the Roman’s wild, Christmas-time festival of Saturnalia.
Saturn is not solid, but is made almost entirely of gas – mostly liquid hydrogen and helium. Only in the planet’s very small core is there any solid rock.
Because Saturn is so massive, the pressure at its heart is enough to turn hydrogen solid. That is why there is a layer of metallic hydrogen around the planet’s inner core of rock.
Saturn is one of the fastest spinning of all the planets. Despite its size, it rotates in just 11.5 hours – which means it turns round at over 10,000 km/h.
Saturn’s surface appears to be almost completely smooth, though Voyager 1 and 2 did photograph a few small, swirling storms when they flew past.
Saturn has a very powerful magnetic field (see magnetism) and sends out strong radio signals. Saturn’s rings are made of many millions of tiny, ice-coated rock fragments Saturn is almost as big as Jupiter.
Saturn’s rings are sets of thin rings of ice, dust and tiny rocks, which orbit the planet around its equator.
The rings shimmer as their ice is caught by sunlight.
The rings may be fragments of a moon that was torn apart by Saturn’s gravity before it formed properly.
Galileo was first to see Saturn’s rings, in 1610. But it was Dutch scientist Christian Huygens (1629-95) who first realized they were rings, in 1659.
There are two main sets of rings – the A and the B rings.
The A and B rings are separated by a gap called the Cassini division, after Italian astronomer Jean Cassini (1625-1712), who spotted it in 1675.
A third large ring called the C or crepe ring was spotted closer to the planet in 1850.
In the 1980s, space probes revealed many other rings and 10,000 or more ringlets, some just 10 m wide.
The rings are (in order out from the planet) D, C, B, Cassini division, A, F, G and E. The A ring has its own gap called the Encke division.