- An image of the planet Saturn shows an Earth-sized storm in its northern hemisphere. Such large …
The second largest planet in the solar system is Saturn. It is almost as big as Jupiter and much larger than the Earth. Saturn is known for its beautiful rings, the most impressive in the solar system. The famous rings can be seen through even a small telescope. The planet was named after the ancient Roman god of agriculture. Saturn is the sixth planet from the sun. The average distance between the sun and Saturn is about 885 million miles (1.4 billion kilometers). It is considered an outer planet. Physical featuresSaturn is a huge planet. The diameter of Saturn at the equator is about 75,000 miles (121,000 kilometers)—nine times that of the Earth. Even though Saturn is large in size, it is the least dense of all the planets. In fact, Saturn would float if placed in water. Saturn has many properties in common with its neighbors, Jupiter, Uranus, and Neptune. These four planets are large worlds made up mostly of gases. They are known as the gas giants. As with all of these planets, it is difficult to distinguish between Saturn's atmosphere and its interior. What looks like a solid surface in photographs of Saturn is actually a layer of clouds. Saturn is thought to have a hot, rocky core surrounded by layers of gases that make up its atmosphere. The gases consist mostly of hydrogen and helium. Near the core, the great heat and pressure cause the hydrogen to behave like a liquid metal. Farther outward is a layer of hydrogen gas thousands of miles thick. However, there is no clear border between the layers of gas and liquid. Weather and temperatureLike Jupiter, Saturn has storm systems that last a long time. When viewed through a telescope, the storms appear as red, white, and brown ovals. However, Saturn is generally less stormy than Jupiter. The temperature near the cloud tops of Saturn is cold, about –218° F (–139° C). RingsSaturn is surrounded by a spectacular system of very thin rings. The rings extend as far out as 110,000 miles (180,000 kilometers) from the center of the planet. They are made of chunks of water ice and ice-covered particles that range in size from a few inches to a few feet. Moons - An image of Mimas, a moon of Saturn, shows the craters on the moon's surface.
- Dione, a moon of Saturn, was photographed by the Voyager 1 spacecraft in November 1980. The large …
Saturn has at least 30 satellites, or moons. The largest of these is Titan. Titan is probably half rock and half ice. It has thick layers of clouds. Titan's surface is very cold and may be covered by oceans of liquid methane. Other major satellites include Dione, Tethys, Rhea, and Mimas. Orbit and spinLike all planets, Saturn has two types of motion, known as orbit and spin. Saturn orbits (travels around) the sun completely in about 29 Earth years. However, the planet spins very quickly. It takes Saturn less than 11 hours to complete one rotation. The force of this fast rotation changes the planet's shape. It is not perfectly round. (For more information on orbit and spin, see planets.) Observation and explorationSaturn has been observed since ancient times because it can be seen from the Earth without a telescope. Saturn looks like a bright orange-yellow star in the night sky. In 1610 the Italian astronomer Galileo became the first to observe the rings around Saturn, with the help of a telescope. However, he did not identify them as rings. Eventually other astronomers realized that Saturn had rings. The greatest advances in knowledge of Saturn have come from the unmanned space probes of the United States National Aeronautics and Space Administration (NASA). From 1979 to 1981, Pioneer 11 and Voyagers 1 and 2 flew past Saturn. The craft sent back close-up photographs that helped scientists identify additional groups of rings as well as previously unknown moons. In 1997 NASA sent the unmanned Cassini spacecraft on a journey to Saturn. On board Cassini is a probe made by the European Space Agency. The probe is designed to survey the clouds, atmosphere, and surface of the moon Titan while Cassini orbits Saturn. Cassini was scheduled to arrive at Saturn in 2004. |