Saturn, the sixth planet from the sun, is the second gaseous giant and, after Jupiter, the second largest planet in our solar system. First observed by Galileo in 1610 with a telescope, the planet is unique because of its very visible rings. You can view Saturn even without a telescope, although it is fainter that Jupiter, and can be distinguished from a star. You can only view the rings and larger moons, however, by using a telescope. It has close to 50 discovered moons, the most of the planets besides Jupiter, and possibly more. A day on Saturn is only about 10.5 hours long, meaning that the planet is rotating extremely fast on its axis. This is the reason why the planet is flattened at its poles, an oblate shape. It takes much longer than Earth; however, for the planet to complete a revolution around the sun. Saturn's year is equivalent to 29.5 years on Earth. It is the only planet less dense than water (its gravity is .7 less than water) meaning that if there was a large enough body of water for the planet to fit inside, it would float! These pages will help you learn all about the history, moons, rings, climate, and missions to the planet Saturn.
Saturn was the name of the god of agriculture from Roman mythology and Cronus was the name of this Greek god. Cronus was the sun of Uranus, the name of the next planet from the sun, and Gaia and the father of Zeus, Jupiter. Clearly, the names of these three planets came from these gods. The English word "Saturday" also comes from the planet's name. Saturn was discovered in prehistoric times, being first observed by Galileo in 1610. He saw the planet had an unusual appearance but these early discoveries were complicated because it was unknown Earth passes through the plane of Saturn's rings every few years as both planets orbit the sun - see picture gallery. Saturn was thought to have been the only planet with rings until 1977. Very faint rings were discovered around Uranus and, soon after, around the other gas giants too. Recently, many discoveries have been made around the moons and rings of Saturn. This is an article on the most recent discovery around Saturn.
Four missions have gone to the planet Saturn: Pioneer 11, Voyager 1, Voyager 2, and Cassini. Pioneer 11 was a mission from the U.S. that left Earth on April 6, 1973 and reached Saturn on September 1, 1979. It flew by the planet taking images and collecting a lot of data. This mission found additional rings and moons, around the planet. Next, the Voyager 1 reached Saturn by November of 1980 after leaving Earth three years earlier. This mission did not land on the planet either but was able to collect hundreds of images of Saturn's moons. It brought back information discovering the atmosphere of Titan, Saturn's largest moon, and showing how complex Saturn's rings are. This is a picture taken 3 million miles from Saturn by the Voyager 1. We can not see this view of Saturn from Earth because only the sunlit side of the planet can be seen since our planet is so close to the Sun. Voyager 2 left Earth on August 20, 1977, right after Voyager 1, and reached Saturn in August of 1981. This mission collected over a thousand pictures of Saturn's moons and achieved its other main goals regardless of a minor malfunction. The last mission to Saturn was Cassini which left Earth on October 13, 1997 and reached the planet on July 1, 2004. Cassini will orbit Saturn for a long time in order to conduct experiments on its moons, rings, and atmosphere. The spacecraft has even traveled through the rings of the planet in order to understand more about them. Cassini brought Huygens, an atmospheric probe, with it so that it can collect information about Titan's atmosphere.
The rings of Saturn are mostly made of ice and rock pieces. The ring system of Saturn is divided into multiple parts including different rings and divisions, as shown above. The A ring and B ring are the brightest and then the C ring, which is a little fainter. The largest gap is the Cassini Division, separating the A and B rings, which gets its name from its discoverer, Giovanni Cassini in 1675. The next gap, the Encke Division, was discovered later in 1837 by Johann Encke. The outermost ring of Saturn is the F-ring and is made up of many smaller rings in which "knots" can be seen, making the ring look "braided". These clumps could be from ring material or very small moons. It is not known how the rings were developed around Saturn but it is speculated that larger moons on Saturn were shattered by comets and meteoroids and then formed rings. The rings around Saturn contain pieces of ice or rock anywhere in size from a few centimeters to over a kilometer. The rings are very thin, only about 1km thick, and are about 250,00km across. The rings are colorful because the ice pieces in them reflect rays from the sun, similar to the way a rainbow is colorful. Rings have different colors based on what it is composed of and how it reflects light. Because of the ice particles, the rings are made mostly of water and are usually white, gray or yellowish in color. Saturn's E-ring, however, is one of only two blue rings known in the solar system. The rings around Saturn do not orbit the planet in one unit but the billions of particles inside the rings circle Saturn independently. The ring system of planets like Saturn is not stable and must be replaced possibly by breaking up bigger moons. The set of rings currently around Saturn could be a few hundred million years old.
There are almost 50 discovered natural satellites of the planet Saturn, 34 of which have been named, and probably more to be discovered within the rings of Saturn. Moons might be hidden in the rings because most are very small. Only five of Saturn's moons are over 600 miles across compared to Earth's moon which has a 2,500 mile diameter. Titan is Saturn's most amazing moon, shown in the upper right-hand corner of this picture, and is also the second largest moon in the solar system. This moon was the first of Saturn's to be discovered, 1655, and has a very thick atmosphere with air consisting primarily of nitrogen gas. Its thick atmosphere means little light can pass through it, as the Voyager showed. At one time, there might have been life on Titan; the Cassini Mission also showed large dark spots on its surface that could be lakes. These lakes, however, would not be filled with water because the environment is too cold but could contain liquid methane which exists on Earth usually as a gas. On January 14th of last year, Hugens, a small spacecraft, reached this moon. It has discovered many rivers and is studying the surface and atmosphere of the moon during the mission. The spacecraft was named after the moon's discoverer, Christiaan Huygens. Enceladus is another moon of Saturn with a shiny, icy surface that reflects a lot of light from the sun. Mimas is known for its huge crater that covers a distance 80 miles wide and 6 miles deep, almost one third of the moon's surface. Tethys, in the bottom right of the picture, has moons of its own called moonlets and also has trenches that are long and deep. Pan, one of Saturn's smallest moons has a diameter of only about 20km. Out of Saturn's moons whose rate of orbit is known, all of Saturn's moons have synchronized rotations except for Phoebe and Hyperion. The moon Phoebe is also unusual because it reflects only about 2% of the light that hits it, compared to about 60 to 90% on the other moons. Six of Saturn's moons make up three pairs that have stable relationships between the rates of their revolutions around Saturn, because of the way they gravitationally interact. An example of this is that Tethys's orbit around the planet is exactly twice as long as that of Mimas'.
The climate on Saturn is very different from our climate on Earth. The temperature is about -180C, way below freezing. The wind is extremely strong on the planet, especially near the equator where the wind reaches speeds of 1,100 miles an hour. These are the highest winds in our solar system. The velocity lessens as you reach higher latitudes. The wind usually blows to the east but above latitudes of 35 degrees, the directions alternate east and west. During a recent lightening storm, earlier this year, the lightening bolts were over 1,000 times stronger than from storms on Earth. This was thought to have been caused by the warm interior of Saturn but the cause is still not completely known.
Definitions
(Click on the term again to return to its original place in the text)
gaseous giant: or gas giant referring to the first four outer planets, which don't have solid surfaces: Jupiter, Saturn, Uranus, and Neptune
atmosphere: the air, type of air, the gases surrounding any star, planet, etc. natural satellite: another word for a moon
moonlet: a tiny moon Click here for my bibliography
