Solar System: Outer Planets - Saturn

The Ringed Planet

Known for its beautiful rings, Saturn is the second largest planet in the solar system. While it is not the only planet to have a ring system, Saturn’s rings are more extensive and visible than those of Neptune, Uranus, and Jupiter. Saturn’s rings were first noticed by Galileo in 1610, but through his weak telescope they looked like ears on either side of the planet. It was not until 1655 that Dutch astronomer Christian Huygens used a better telescope to figure out that the “ears” Galileo saw were actually rings.

Courtesy of NASA JPL

In 1979, Pioneer 11 became the first space probe to take pictures of Saturn and its rings. In 1980 and 1981, Voyager 1 and Voyager 2 provided a wealth of images and data, which gave astronomers new insights into Saturn, its rings, and its moons. Saturn’s atmosphere, which was first studied closely by the Voyager probes, is composed mainly of hydrogen and helium. Like the other Jovian planets, Saturn has light and dark bands of atmospheric disturbances, as well as a red spot and white cloud that were first seen by the Hubble Space Telescope in the early 1990’s.

The Cassini spacecraft was launched in 1997, and will reach Saturn in July 2004. It will spend at least four years orbiting the planet, collecting data and taking photographs. Additionally it will launch a probe (named Huygens) to gather data about Saturn’s largest satellite, Titan, which is larger than both Mercury and Pluto

Saturn is easily visible to the unaided eye, but you’ll need a small telescope to catch a glimpse of the prominent rings or larger moons.

Saturn is in Gemini in early 2004, visible in the late night sky through March. It sets earlier each night until late May, when it disappears into the sunset. In August you can find Saturn rising in the early morning twilight, and it will rise earlier each night until it rises in the evening in December.