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the seventh planet from the Sun and the third largest (by diameter)
Uranus as seen by the Hubble Space
common symbol for Uranus
The first planet discovered in modern times, Uranus was discovered by William Herschel while systematically searching the sky with his telescope on March 13, 1781. Herschel named it "the Georgium Sidus" (the Georgian Planet) in honor of his patron, King George III of England. The name "Uranus" was first proposed by Bode in conformity with the other planetary names from classical mythology but didn't come into common use until 1850. Uranus is the ancient Greek deity of the Heavens, the earliest supreme god.
Uranus' axis is almost parallel to the ecliptic, which means that its polar regions receive more energy input from the Sun than do its equatorial regions.
View From Earth
Uranus is sometimes just barely visible with the unaided eye on a very clear night, but you must know exactly where to look. A small astronomical telescope will show a small disk.
Uranus has been visited by only one spacecraft, Voyager 2, on January 24, 1986.
Uranus appears to be composed primarily of rock and various ices, with about 15% hydrogen and a little helium. It does not appear to have a rocky core, but rather that its material is uniformly distributed.
The planet's atmosphere is about 83% hydrogen, 15% helium, and 2% methane. The blue color seen in the photograph at top is the result of absorption of red light by methane in the upper atmosphere.
Like the other gas planets, Uranus has rings. They are composed of fairly large particles ranging up to 10 meters in diameter in addition to fine dust. There are 11 known rings.
Uranus has 21 named moons and six unnamed ones. Most of them have nearly circular orbits in the plane of Uranus' equator; the outer four, however, are much more elliptical. Unlike the other bodies in the solar system which have names from classical mythology, Uranus' moons take their names from the writings of Shakespeare and Pope.
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This page was last updated on 04/21/2017.