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Astronomy: Saturn
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Saturn is the second largest planet in our solar system after Jupiter. But many people think of it as the most beautiful, because of its glorious rings which can even be seen with a simple telescope. Just like its neighbour Jupiter, it's a giant gas planet, composed of hydrogen and helium and with a simular structure like Jupiter. Saturn orbits the Sun in 29,46 Earth years, but rotates on its axis in only 10,66 hours. Because of the fast rotation both poles are flattened. Also, giant fast storms and winds are present on the surface. In 2006, Cassini made a video clip of a giant storm on the South pole of Saturn. This storm is bigger than the entire Earth (MPEG, 3 sec, 564 KB). And has wind speeds of 550 kilometers per hour (twice as fast as a category 5 hurricane). The rings of Saturn extend from 4.000 miles above the cloud tops to 46.250 miles. They are made of dark ice and rocks which range in size from a few kilometres to tiny ashes. The rings are tilted nearly 27o. The waxing and waning of the rings in a 15 year cycle were first observed by Galileo Galilei in 1610, but only until 1659 Christiaan Huygens first realized that the observations were related to a ring around Saturn's equator. Cassini discovered a gap in the ring in 1675 which is called the Cassini division. And as technology advanced over time, more and more rings were discovered. The rings have also been subject of study by the Pioneer 10, the Voyager 1 and Voyager 2 spacecraft. Voyager 2 launched in 1977, flew past Saturn in 1981 and showed scientists that the gaps are not empty but filled with small ringlets that are held together by tiny asteriod moons called shepherd moons. The moon TitanSaturn has 30 known moons. But Saturn has the only natural satelite in our solar system that possess a thick atmosphere, its moon Titan.Titan rotates around Saturn in 16 days at an altitude of 625.000 miles. The distorting forces are small and do not have a big influence on atmospheric conditions. Titan has a nitrogen-rich atmosphere which has a surface pressure 50% greater than Earth's atmosphere. Other gasses like hydrogen and helium have escaped the atmosphere. Solar ultraviolet radition has reacted with gasses in the upper atmosphere, forming thick smog. Scientists believe that the composition of Titan's atmosphere is similar to Earth's atmosphere when our planet was just formed. By measuring the atmosphere scientists hope to discover how life has evolved on Earth. Titan has a prehistoric atmosphere without conditions to form life as we know it (too cold and to dark). By comparing our atmosphere with Titan's we hope to learn the steps how life starts. On 14 January 2005 the Huygens probe descended to Titan, took measurements of its atmosphere and made the first close-up surface pictures. The views of Titan's surface suggest a similarity to eroded surfaces on Earth and Mars. |
  The rings of Saturn (colors are enhanced)  Saturn and Titan, picture from the approaching Cassini-Huygens in 2003.  Saturn approached by Cassini-Huygens in 2004 < JPG image 1024 X 1024 pixels >  Titan from an altitude of 16 km.  The two rocks below center are only about 15 centimeters and 4 centimeters across and lie 85 centimeters from the Huygens probe |
Saturn in ultravioletHere is a picture of Saturn taken by the Hubble Space Telescope in ultraviolet light. The glowing, swirling material at Saturn's poles are its auroral "curtains," rising more than a thousand miles above the cloud tops.Saturn's auroral displays are caused by the solar wind, which sweeps over the planet, much like Earth's aurorae, which is occasionally seen in the nighttime sky. The process that triggers these auroras is similar to the phenomenon that causes fluorescent lamps to glow. Click here to see the same phenomenon at Jupiter or Earth. Related subjects>> Saturn seen from Earth>> Cassini-Huygens >> Voyager >> Pioneer >> Galileo Galilei |
 Aurorae at the pole regions of Saturn |
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