Saturn, the second most massive planet, and the most distant planet known to the ancients, is one of the most beautiful sites in the Solar System, as witnessed by the adjacent image. The most striking feature of Saturn is the spectacular ring system. Although this feature is no longer unique, since we now know that all the Gas Giant planets have rings, the rings of Saturn are much more elaborate than those of any of the other planets. Saturn shares many features with its even larger Gas Giant neighbor Jupiter, but has various unique features in its own right.