Saturn, the sixth planet from the Sun, is one of the five planets known to the ancients. Saturn is most famous for its ring system (although Jupiter, Uranus, and Neptune also have rings). The telescopic appearance of Saturn with its magnificent set of rings is breathtaking in a modest telescope. The planet itself has bands, weather patterns similar to Jupiter's, but much fainter. It is the rings that grip the attention. One moon, Titan, can be seen shining at magnitude 8.8 about 4.5 ring diameters from Saturn at eastern or western elongation (see tables in Brisbane Skies). And Iapetus is a strange two-faced moon like soot on the leading hemisphere and snow on the trailing hemisphere, with the sharp division between dark leading and bright trailing sides always facing Saturn. Shining at brightest magnitude 11.1 Cassini, the moon's discoverer, noted that he could see Iapetus on one side of Saturn but not the other! Iapetus is three times farther out than Titan

A giant, gaseous planet, Saturn has an intriguing atmosphere. Alternate jet streams of east-west and west-east circulation can be traced in the motions of the cloud tops; the speeds of these jet streams reach as much as 500 m/s and are responsible for the banded appearance of the clouds. The atmosphere consists mostly of hydrogen and helium, but also includes trace amounts of other elements. Electrical processes and heat from internal planetary sources enrich the layered chemical mix of the atmosphere, which probably transitions from superheated water near the core to the ammonia ice clouds that are observed at the cloudtop. The planet's atmosphere also features storm structures similar to Jupiter's famous Great Red Spot.

Although Galileo was the first to see Saturn's rings (in 1610), it wasn't until 1659 that the Dutch astronomer Christiaan Huygens, using an improved telescope, observed that the are actually separate from the planet. In 1676, the French-Italian astronomer Jean Dominique Cassini first observed what appeared to be a division between the rings now known as the Cassini division. Improvements in telescopy over the next three centuries revealed much about the mysterious planet: the banded atmosphere, the storm "spots," and a very apparent "flattening" at the poles, three features Saturn was observed to share with Jupiter.

Over the past two decades, a series of spacecraft have flown by Saturn, giving us our first close-up looks of the planet, and revealing information about Saturn's magnetic field and previously unobserved rings and moons. Some moons were found to be covered with very smooth ice. Also, visible and infrared observations of Saturn showed us a surprising mix of thermal patterns among the cloud bands, suggesting internal processes yet to be understood.

The Voyager spacecraft discovered hundreds of ringlets within Saturn's major rings. Some have small moons flanking them (called "shepherding" moons. The "F ring" appears to have regularly spaced "knots" due to gravitational interaction with the tiny moons Prometheus and Pandora. Shadowy "spokes" were seen to develop and dissipate in the rings. Ring particles were found to be composed mostly of water ice, and to range in size from dust motes to houses. The rings may be the remnants of moons destroyed by tidal interaction with Saturn's gravity. They may include remnants of comets that passed too close to Saturn and were likewise destroyed.

Today we know Saturn to have 7 major ring divisions and 18 moons. Titan the largest Saturnian moon has held the attention of scientists most. A bit larger than the planet Mercury, Titan is shrouded by a thick nitrogen atmosphere that might be similar to what Earth's was like long ago.