Saturn is the sixth planet from the Sun and the second largest: Orbit: Diameter: Mass: 1,429,400,000 km (9.54 AU) from the Sun 120,536 km (equatorial) 5.68e26 kg

Astronomy

Saturn has been known since antiquity. Galileo was the first to observe it with a telescope in 1610. He was confused by its odd appearance. Early observations of Saturn were complicated by the fact that the Earth passes through the plane of Saturn's rings every few years as Saturn moves in its orbit. A low resolution image of Saturn therefore shows marked changes. It was not until 1659 that Christian Huygens correctly inferred the geometry of the rings. Saturn's rings remained unique in the known solar system until 1977 when very faint rings were discovered around Uranus, and not long afterwards, around Jupiter and Neptune. The three main bands of rings, which are no thicker than a six-storey building, are thought to be icy smithereens, millions of icy chunks the size of hailstones and snowballs.

Saturn is visibly flattened (oblate) when viewed through a small telescope; its equatorial and polar diameters vary by almost 10% (120,536 km vs. 108,728 km). This is the result of its rapid rotation and fluid state. The other gaseous planets are also oblate, but less so.

Saturn is the least dense of the planets, with a specific gravity (0.7), less than that of water. Like Jupiter, Saturn is about 75% hydrogen and 25% helium with traces of water, methane, ammonia and "rock", similar in composition to the primordial Solar Nebula from which the solar system was formed. Saturn's interior is similar to Jupiter's and consists of a rocky core, a liquid metallic hydrogen layer and a molecular hydrogen layer. Traces of various ices are also present. Saturn's interior is hot (12000 K at the core) and it radiates more energy into space than it receives from the Sun. Most of the extra energy is generated by the Kelvin-Helmholtz effect as in Jupiter. But this may not be sufficient to explain Saturn's luminosity and there has been speculation that some additional mechanism may be at work, perhaps the "raining out" of helium deep in Saturn's interior. Saturn's winds blow even more strongly than those on Jupiter. In some places they roar at 1,300 kilometers (800 miles) per hour, which is 11 times faster than hurricanes here on Earth. The temperatures in Saturn's clouds of ammonia ice crystals are about -135 degrees Centigrade (-210F)

Saturn has 18 moons including Titan, the second largest moon in the solar system and the only one with a thick atmosphere, which consists of dense orange clouds. Like the other Jovian planets (Jupiter, Uranus and Neptune), Saturn has a significant magnetic field.

If you would like to know more about the solar system, Starscine suggests the following websites:

www.nineplanets.org
www.nasa.gov