The real facts about Saturn

Saturn is the sixth planet from the Sun and the second biggest. Saturn has been identified from the time when prehistoric times. Galileo was the first to analysis it with a telescope in 1610; he noted its odd look but was confused by it. Early observations of Saturn were complex by the fact that the Earth passes through the plane of Saturn's rings all few years as Saturn moves in its orbit. A low resolution image of Saturn therefore changes considerably. It was not in anticipation of 1659 that Christian Huygens properly inferred the geometry of the rings. Saturn's rings remained exclusive in the known solar system until 1977 when extremely faint rings were discovered around Uranus.

Saturn is clearly flattened (oblate) when viewed through a small telescope; its equatorial and polar diameters differ by almost 10% (120,536 km vs. 108,728 km). This is the end result of its rapid rotary motion and fluid state. The other gas planets are also oblate, but not so a lot so. Saturn's rings are very thin: though they're 250,000 km or more in thickness they're less than one kilometer thick. In spite of their impressive appearance, there's actually very little material in the rings -- if the rings were compressed into a single body it would be no more than 100 km across.

Saturn's outermost ring, the F-ring, is a difficult structure made up of number of smaller rings along which "knots" are visible. Scientists guess that the knots may be clumps of ring material, or mini moons. The odd braided appearance visible in the Voyager 1 images (right) is not visible in the Voyager 2 images perhaps for the reason that Voyager 2 imaged regions where the part rings are generally parallel. They are well-known in the Cassini images which as well show some as yet unexplained wispy spiral structures. The source of the rings of Saturn (and the other Jovian planets) is unidentified. Though they may have had rings since their formation, the ring systems are not firm and must be regenerated by continuing processes, perhaps the breakup of bigger satellites. The present set of rings may be only a few hundred million years old.