- Other bodies
- Basic Definitions
Uranus was discovered in 1781 by astronomer William Herschel. Uranus is located at a mean distance of 2.8709722 x 109 km from the Sun and takes 84 years to complete one full orbit around the Sun.
Uranus is the third largest planet by diameter and the fourth largest by mass. Its name comes from the Greek mythology as Ouranos, the Greek God of the sky.
Uranus gets its characteristic blue-green color from methane gas which is present in its atmosphere. The clouds atop Uranus in the upper atmosphere are covered by a layer of methane gas. Sunlight is reflected by the clouds, but the methane gas layer absorbs the red portion of the sunlight allowing the blue portion to escape. This results in the formation of a blue-green color of the planet.
Missions to Uranus
On Jan 24 1986, Voyager 2 became the only spacecraft to reach Uranus. It flew by Uranus at a distance of 107,000 kilometers (66,500 miles) from the planet's center. The spacecraft imaged ten new moons in addition to the five moons already known. Following its historic run intoUranus , Voyager 2 continued its voyage on to Neptune, and today continues its journey toward interstellar space, diving below the ecliptic plane.
Like Jupiter and Saturn, Uranus is also composed primarily of hydrogen and helium. A small amount of methane with traces of ammonia and water can also be found.
Uranus does not have a solid rocky core as Jupiter and Saturn. A major portion of the mass of Uranus (80% or more) is concentrated in an extended liquid core consisting primarily of water, methane, and ammonia and with higher-density materials at further depths.
Uranus’ rotational axis is almost horizontal to the ecliptic plane (plane containing the orbit of Earth) and therefore it is difficult to determine the North & South Pole of the planet. Also, due to the unusual orientation ofUranus about the ecliptic plane, the Polar Regions of the planet get more sunlight than its equatorial regions (invariably hotter at its equator than its poles).
Uranus in the Night Sky
Uranus can be viewed in the dark night sky as a faint star. It can be easily located with the help of common binoculars.
Rings of Uranus
|Uranus 9 Rings|
So far, astronomers have identified 11 known rings around Uranus. In order of increasing distance from the planet, they are names 1986-U2R, Ring 6, Ring 5, Ring 4, Alpha Ring, Beta Ring, Eta Ring, Gamma Ring, Delta Ring, Lambda Ring and Epsilon Ring.
The Uranian Rings are very dark and are composed of fairly large particles ranging up to 10 meters in diameter in addition to fine dust. Epsilon ring is the brightest of all Uranian rings.
|Name||Distance from Uranus's center (km)|
In 1787 William Herschel observed the two largest moons of Uranus namely Titania and Oberon. The next two moons i.e. Ariel and Umbriel were discovered by William Lassell in 1851. In 1948 Gerard Kuiper discovered the Uranian moon Miranda.
The Voyager 2 spacecraft neared the Uranian system in 1986 and discovered another 10 new moons namely Juliet, Puck, Cordelia, Ophelia, Bianca, Desdemona, Portia, Rosalind, Cressida and Belinda.
Since then, the Hubble Space Telescope has discovered another 12 moons orbiting Uranus taking the total number of Uranian moons to 27.
All the Uranian moons have been named after characters from the works of Shakespeare and Alexander Pope.
The complete list of the Uranian moons is as follows: