Robot Explorers: US Unmanned Space Missions: page 12 |
The yellow, red and orange colored belts around Jupiter contained roiling, almost fluid-like storms. Gigantic cyclones raged through the upper atmosphere. The Great Red Spot, a hurricane-like storm three times the size of Earth, is estimated to be up to a million years old. The color of the spot is probably due to traces of sulfur or phosphorus compounds. |
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No discovery was more unexpected than that of active volcanoes on Io, the innermost Gallilean moon. It was the first time volcanoes had been spotted on any object in the solar system besides Earth. Voyager 1's cameras spotted nine volcanoes, spraying sulfurous ejecta as high as 175 miles above the surface. Volcanic activity on this satellite is due to tidal flexing caused by the gravitational tug-of-war between Io, Jupiter and the other three Gallilean moons. |
| The next moon out, Europa, is approximately the same size as our own moon. It has a thin icy crust that is just slightly warmed by tidal flexing. It is believed that a tidally heated ocean may exist beneath the icy surface. Europa's face is extremely smooth and uncratered, yet marked with lines that are most likely fractures in the ice surface. |  |
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Ganymede and Callisto, both about the size of Mercury, are each half rock and half ice. Ganymede is actually the largest moon in the solar system. Tectonic processes are responsible for creating the huge, crisscrossing ridges seen on this satellite. Callisto has the lowest density of any of Jupiter's satellites, indicating that it contains large amounts of water. It is the most heavily cratered satellite in the Jovian system, and possesses the oldest surface of all of the objects in the solar system. |
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Copyright ©2004 Colleen Gino |
Images courtesy JPL and NASA. |
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