The Greatest Saturn Portrait...yet: While cruising around Saturn in early October 2004, Cassini captured a series of images that have been composed into the largest, most detailed, global natural color view of Saturn and its rings ever made.
Source: Courtesy NASA/JPL-Caltech
Average Distance from the Sun: 1.427 billion km (9.555 AU)
Size (Equatorial Diameter): 119 300 km (9.35 x that of Earth)
Mass: 5.688 x 1026 kg (95.18 x that of Earth)
Length of Day (Solar Rotation Period): 10.66 Earth hours
Length of Year (Sidereal Orbital Period): 29.46 Earth years
Temperature: -180°C (clouds)
Gravity: 11.4m/s2 (1.16 x that of Earth)
Saturn is one of the Gas Giants of the outer Solar System, most famous for its spectacular ring system. Though not the only planet to have rings, it has a much larger and more impressive ring system than the other Gas Giants. It is the second largest planet in the Solar System, with only Jupiter larger than it. Saturn is visible to the naked eye from Earth and was known to early humans.
Surface and Atmosphere
Saturn is mostly made of gases, hence there is no solid surface.
The outer layers of Saturn are mostly made of hydrogen and helium. These gases whirl around the planet at very high speeds. They are swept around by winds of 800 km per hour. Deep inside the outer clouds of gas is a layer of hydrogen which is like a liquid, below that is a layer where the hydrogen behaves like molten metal and at the very centre we would find a solid core about the size of Earth, but with a mass ten times that of the Earth.
Saturn has 18 named moons and another 12 moons that were discovered in 2000 but have not yet been named. The largest moon is:
Titan (diameter: 5 140 km)
Titan is the second largest moon in the Solar System and is larger than the planets Mercury and Pluto. It has a nitrogen based atmosphere, also containing methane and argon, which appears as a thick orange haze around the moon. This haze is produced by sunlight converting the methane into other hydrocarbons which form a thick smog, completely obscuring the surface. These conditions may be similar to those on Earth before life evolved, but the low temperature (-179°C) prevents progress beyond simple organic molecules.
Some of Saturn's smaller moons were discovered by the Voyager spacecraft, which passed the planet in 1980 and 1981. Two more were discovered by the Hubble Space Telescope through images taken in May 1995, when the Earth crossed Saturn's ring-plane. Several of these smaller satellites share the same orbit. There are also some shepherding moons, which orbit within the ring system and help maintain the structure of the rings.
A spectacular ring system extends around Saturn and up to 400000 km above its cloud tops. It is made up of countless particles and chunks of rock and ice, which form thousands of ringlets. The particles closer to the planet move more quickly around it than those farther away.
The images from the Voyager spacecraft revealed the incredible complexity of Saturn's ring system, showing narrow gaps and thin rings not visible from Earth. They also showed strange 'spokes' of fine particles orbiting above the rings for a few hours.
Saturn was a Roman god, associated with the Greek Cronos, son of Uranus and Gaia (Greek earth goddess). In Roman mythology he was also god of workers and vine growers and this association was celebrated at the Saturnalia (17-23 December).