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The Elusive Rings of Uranus
Uranus is, unquestionably, far away: an average 1,783,939,400 miles from the sun. It is so far away from the sun, it takes 84 earth years for the blue-green planet to complete an orbit, not to mention that it is -357 degrees Fahrenheit. Regardless, Uranus can be observed through binoculars as a fuzzy blob, similar to a star. William Herschel discovered the planet, which currently has twenty-seven moons, in 1781. Uranus is significantly different from the other planets in that it is tilted 98 degrees--almost completely on its side.
The most distinctive feature of Uranus is its system of rings. It is thought that Herschel observed the rings at the time he discovered Uranus, but no other astronomers made note of the rings until two centuries later, when the rings were officially discovered in 1977 by three astronomers. There are nine main rings, two dusty rings, and two outer rings, all made mostly of dust, as opposed to Saturn's icy rings. Since the planet has a unique axial tilt, its rings are perpendicular to the orbital path. The first images of the rings were provided by Voyager 2 in 1986--the only spacecraft that has ever visited Uranus.
Uranus's brightest ring is the e (epsilon) ring. This ring has two personal satellites, called shepherd moons: Cordelia and Ophelia. Cordelia orbits on the inside of the e ring, while Ophelia orbits on the outside.
On August 14, 2007, astronomers witnessed a special treat when Uranus's rings were viewable edge-on. This phenomenon only occurs every 42 years in the 84 year orbit, and astronomers had never previously seen the view because they did not know the rings existed. The Hubble Space Telescope captured pictures of the event.
For the next several years Uranus will be best viewed in September and October when it is at opposition, directly opposite the sun.
* Fun Fact: Uranus's moons are named after characters from the works of William Shakespeare and Alexander Pope.
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