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Astronomy: Uranus
In March 1781 William Herschel, an amateur astronomer who lived in Bath, England, used a small telescope to search for double stars and found a curious object.
First he thought it was a nebula or a comet, but additional observations revealed it to be a planet, Uranus was discovered. In 1787 he discovered its two largest sattelites, Titania and Oberon.  the Moons Titania and Oberon In 1851 the moons Umbriel and Ariel were discovered by the British amateur astronomer William Lassel. The fifth moon Miranda was discovered by Dutch astronomer Gerard Kuiper. Voyager 2 observed that all five sattelites have experienced impact cratering, tectonic movements and resurfacing. And by Voyager data and other data analysis ten new moons were discovered. But note that we now know that Uranus has 21 moons. Planet compositionPictures have shown brown spots in the south pole region. The north pole region has not been seen yet. The brown spots could be some complex organic compound.The atmosphere consists mainly of hydrogen and 12 percent of helium. The thick atmosphere shows not much for the human eye. Voyager's pictures show a few white clouds in the upper atmosphere in band shapes which suggest wind patterns. Axis and magnetic fieldThe axis of rotation for Uranus is tipped 98o, so it lies nearly horizontal. At present the south pole is pointed towards the Sun. It is thought that in the past a large object with the size of Earth struck Uranus and tilted the axis.The magnetic field is caused by a hydrogen ocean thought to be thousands kilometers thick. Such pressure creates temperatures above 1000oC, which breaks down hydrogen into ions that conduct electricity. This big tilded field can't be explained with the current information we have (just like with Uranus). RingsIn 1977 a team of astronomers was observing stars blocked by Uranus, which is called a star occulation. They observed several brief occulations before and after the passage of Uranus in front of the star. And by accident 9 rings were discovered.While flying by at 20 kilometers per second Voyager 2 discovered 2 new rings at Uranus. Related subject>> Voyager 2 spacecraft |
 The thick clouds of Uranus reveal nothing of its surface  Composed image of Uranus and the moon Miranda  the moon Ariel  the moon Umbriel |
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