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Astronomy: Jupiter
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Jupiter is the largest planet in our solar system and like Saturn, Uranus and Neptune it is a gas giant. Because the planet isn't solid and it rotates very quickly in less than ten hours you can clearly see that the planet hasn't got a perfect ball shape form, both poles are flatened. This planet is also known because of the coloured horizontal stripes of atmosphere. These stripes are also caused by the fast rotation and are seperate layers of gas. The lighter coloured zones seem to be higher and cooler than the darker stripes. From atmosphere to interiorWhile its clouds are Jupiter's most striking feature to the eye, they are thought only to exist at the very top of Jupiter's atmosphere, in a layer about 50 km (30 miles) thick. In this region, the pressure in the atmosphere is comparable to that on Earth.Below the clouds, there is a 21000 km (13000 miles) thick layer of hydrogen and helium. This layer gradually changes from gas to liquid as the pressure increases. Beneath the liquid hydrogen layer is a 25000 miles (40000 km) deep sea of liquid metallic hydrogen. At this depth, the pressure is more than three million times Earth's atmospheric pressure at the surface. Hydrogen molecules are so tightly packed that they break up and become electrically conductive. Scientists believe it is this electrically conductive liquid that causes Jupiter's intense magnetic field. The temperature at the core of Jupiter is estimated to be 30.000 degrees Celsius (55.000 degrees Fahrenheit). This heat makes its way up through Jupiter and shines through cloud-free holes in the clouds, which are referred to as hot spots. |
 Color image data taken by Galileo between 1995 and 1998 mapped the surface of Jupiter's moon Europa.  The moon Io orbiting low around Jupiter. This photo was taken by the spacecraft Cassini. < JPG image 999 X 959 pixels > |
MagnetosphereJupiter is also one of a kind because it emits strong radio waves. It's believed that these radio waves are caused by the planet's high speed electrones that are trapped in the huge magnetic field (the magnetosphere). Look at the image on the right of this page to see a computer drawn impression of the magnetosphere.The magnetosphere is tear drop shaped, away from the Sun due to the solar wind. If you could see this magnetic field with the naked eye from our planet, it would be several times bigger than our full Moon (!). The Pioneer and Voyager spacecrafts have also observed a giant doughnut shaped form of charged parcticles surrounding Jupiter at about the distance of the orbit of Io. This ring is called the Io plasma torus. Some of the material from the volcanoes on Io gets caught up in the rotating field and forms the torus. The low orbiting Io is proved to be a trigger for strong radio wave emittings on the Jupiter surface. |
 Jupiter's magnetosphere streching over a great distance  The Io Plasma Torus around Jupiter |
The Great Red SpotThe Great Red Spot is an astronomers attraction and has been spotted since 1664. It is a giant storm and one of the trademarks of Jupiter.Because of the fact that Jupiter is a gas planet this storm (and others) can exist for centuries. The spot has its red colour because it consists of chemicals that absorb violet and blue light and reflect the red light. This red light is the light we see. The spot extends a range of 23.000 km (14.300 miles) to 12.400 km (7.700 miles). The clouds in the storm are trapped in the rotating hurricane which seems to have an ascending flow. |
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Jupiter in ultravioletJupiter's auroral displays are caused by the energetic solar wind from the Sun that sweeps over the planet. The solar wind particles light up in the atmosphere, much like Earth's aurorae, which are occasionally seen in the nighttime sky.Click here to see the same phenomenon at Saturn or Earth. |
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Io, the strange moonThe strangest moon in the Solar System is bright yellow. This picture, showing Io's true colors, was taken in 1999 July by the Galileo spacecraft currently orbiting Jupiter. Io's colors derive from sulfur and molten silicate rock.The unusual surface of Io is kept very young by its system of active volcanoes. The intense tidal gravity of Jupiter stretches Io and damps wobbles caused by Jupiter's other Galilean moons. The resulting friction greatly heats Io's interior, causing molten rock to explode through the surface. Io's volcanoes are so active that they are effectively turning the whole moon inside out. Some of Io's volcanic lava is so hot, it glows in the dark. Related subjects>> Comet Shoemaker-Levy 9 impacts into Jupiter>> Galileo >> Voyager >> Pioneer >> Cassini-Huygens >> Neptune's Great Dark Spot |
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