Saturn is the famous "ringed planet." Only Jupiter is larger than this gas giant. Although Saturn is the sixth planet from the Sun, it is clearly visible to the unaided eye as a bright golden "star." Its rings are visible through a small telescope.

Measured from edge to edge, Saturn's rings span about 600,000 miles (one million km), or two-and-a-half times the distance from Earth to the Moon.

Saturn's rings are made of ice and rock. They are not solid, but consist of small bits of frozen material in a layer just a few thousand feet thick. The rings may have formed with Saturn itself, or they may have formed much later, when a small moon or even a large comet passed too near Saturn and was pulled apart by the planet's powerful gravity.

In fact, astronomers may have discovered several new rings in the making in 1995, when the rings were turned edge-on to Earth. Hubble Space Telescope found several dense "clumps" of material near the outer edge of the rings. These clumps may be former moons that were shattered by recent impacts and are in the process of spreading out to form new rings.

Like the other gas giants ? Jupiter, Uranus, and Neptune ? it probably consists of a dense, solid core surrounded by an envelope of hydrogen and helium.

Although the cloud features on Saturn are not as striking as those on Jupiter, they do change. Winds caused by Saturn's rotation stretch the clouds into horizontal bands circling the planet. At the equator, these winds reach speeds of 1,100 miles (1,770 km) per hour.

Like all the gas giants, Saturn is not a very hospitable destination. The hydrogen atmosphere is not breathable, and the strong winds that stir the atmosphere would certainly tear apart any living thing.

If you could get through Saturn's clouds and survive the crushing atmospheric pressure, you would find a world without any solid land. An ocean of liquid hydrogen, thousands of miles deep, completely covers the planet's solid core. As you dropped deeper into the atmosphere, clouds would blot out the view of the Sun and Saturn's beautiful rings.

Saturn's moons, while very cold, would be a little more hospitable. Though none has a breatheable atmosphere, they are solid, like Earth. From Saturn's moons, you could see the Sun as a tiny, bright disk. And depending on where you stood, Saturn itself might loom overhead -- a giant, bejeweled neighbor in the sky.

Saturn has more moons than any other planet in the solar system. The largest is Titan, which is larger than the planet Mercury. Titan has a thick atmosphere of , and may be covered by vast lakes or oceans of liquid methane.

This frigid moon is enveloped by a thick layer of orange "smog" ? mostly nitrogen mixed with organix compunds ? which blocks visible light. As a result, Titan's surface has remained hidden.

Until recently, scientists thought that Titan might be completely covered by an ocean of liquid methane. But since 1992, observations made with forms of energy that are invisible to human eyes have suggested otherwise. Instead of a global ocean, Titan's surface appears to consist of several large lakes or seas separated by continents.

The Cassini spacecraft will drop a sophisticated probe into Titan's atmosphere when it arrives at Saturn in 2004. The probe will photograph Titan's surface and measure the composition of its atmosphere.

With binoculars, you can just make out Titan as a tiny star-like point of light near bright golden Saturn.

Another of Saturn's moons, Iapetus, is bright and icy on one side and dark and dusty on the other. And one small moon, Mimas, was once hit by an asteroid that almost broke the moon apart. Enceladus, the moon next out after Mimas, has a bright icy coating. Volcanoes may periodically belch ice and water from its interior. Cassini will study all of these moons when it arrives at Saturn.