Saturn is the sixth planet from the sun and its diameter is about 85% of Jupiter, the largest planet. Saturn is visible without a telescope and its existence was known by ancients. In 1610, Galileo peered at it through a telescope, but he was puzzled by its rings because he could not explain their geometry. Because of the resolution provided by his old-fashioned apparatus he could not explain what they were. Saturn's motion through our sky presents different angles of the rings, from an invisible edge-on appearance, to a much broader oval appearance when the rings are at maximum obliqueness. Saturn moves through these geometries every few years. It was Christiana Huygens who inferred in 1659 that a flat disc-shaped object would account for and explain the observations made by Galileo. The ring system of Saturn was considered unique until 1977 when rings were discovered to exist around Uranus and later around all of the solar gas giants.

Saturn is the most oblate planet in our solar system. Its polar diameter is only about 90% of its equatorial diameter. This is caused by its high speed of rotation and centrifugal forces causing the equator to pull away from the axis of rotation. Saturn is also the least dense of the planets being only 70% the density of water.

The interior of Saturn is similar to Jupiter's. At the center is a rocky core surrounded by a thick layer of liquid metallic hydrogen. Beyond that are liquid molecules of hydrogen and helium.

Saturn is the most oblate planet in our solar system. Its polar diameter is only about 90% of its equatorial diameter. This is caused by its high speed of rotation and centrifugal forces causing the equator to pull away from the axis of rotation. Saturn is also the least dense of the planets being only 70% the density of water.

The interior of Saturn is similar to Jupiter's. At the center is a rocky core surrounded by a thick layer of liquid metallic hydrogen. Beyond that are liquid molecules of hydrogen and helium.

Saturn's nearest moons orbit amongst the rings. Pan, the innermost, sweeps the gap called the Encke division in Saturn's A ring. Atlas, the next moon, orbits at the edge of ring A, and Prometheus and Pandora orbit Saturn on either side of ring F. These are called shepherding satellites, because it is believed that they are responsible for distributing the matter in the rings.

Titan, the largest of Saturn's moons, is the second largest moon in the solar system. It is larger than our own moon and is 40% the diameter of our planet Earth. Titan is the only moon with a substantial atmosphere and can be spotted through a small telescope. Medium sized amateur telescopes will reveal four or five other moons. Iapetus has hemispheres with greatly varying brightnesses, being four times brighter when on one side of Saturn than when on the opposite side.

Perhaps the most distinctive feature in the Solar System, Saturn's rings are mostly empty. Measuring more than 250,000 km in diameter they are only 1.5 km thick. The rings are made up of numerous small particles ranging in size from a centimeter to several meters. A few objects may exist which measure as much as a few kilometers. Each of these is composed of water ice or rock with an icy covering. If all of the ring components were compressed into a single object, it would measure only about 100 km across.

It has recently been noticed that Saturn's rings exhibit "spokes"; radial inconsistencies that appear as darker regions. These are probably influenced by Saturn's strong magnetic field. The moons Atlas, Prometheus and Pandora are believed to be "shepherding satellites", because they are responsible for keeping the rings in place, although the mechanics of how they do so is not clearly understood.