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Uranus

the seventh planet from the Sun and the third largest (by diameter)

Uranus as seen by the Hubble Space Telescope
Uranus as seen by the Hubble Space Telescope

common symbol for Uranus
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.

Facts and Figures
Mean distance from Sun 1,785,000,000 miles
Distance from Earth  
  Least 1,700,000,000 miles
  Greatest 1,960,000,000 miles
Equatorial diameter approximately 29,000 miles
Period of rotation (day) 10 earth hours and 49 minutes
Period of revolution (year) about 84 earth years
Orbital speed  
Mass (Earth=1)  
Mean density (water=1)  
Surface gravity (Earth=1)  
Atmospheric pressure at surface (Earth=1 bar)  
Mean surface temperature  
Natural satellites 27

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.

Exploration

Uranus has been visited by only one spacecraft, Voyager 2, on January 24, 1986.

Composition

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.

Atmosphere

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.

Rings

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.

Satellites

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.

Satellite Distance from Uranus Radius Mass Discoverer Date
Cordelia
Ophelia
Bianca
Cressida
Desdemona
Juliet
Portia
Rosalind
2003U2
Belinda
1986U10
Puck
2003U1
Miranda
Ariel
Umbriel
Titania
Oberon
2001U3
Caliban
Stephano
Trinculo
Sycorax
2003U3
Prospero
Setebos
2002U2
50,000 km
54,000 km
59,000 km
62,000 km
63,000 km
64,000 km
66,000 km
70,000 km
75,000 km
75,000 km
76,000 km
86,000 km
98,000 km
130,000 km
191,000 km
266,000 km
436,000 km
583,000 km
4,281,000 km
7,169,000 km
7,948,000 km
8,578,000 km
12,213,000 km
14,689,000 km
16,568,000 km
17,681,000 km
21,000,000 km
13 km
16 km
22 km
33 km
29 km
42 km
55 km
27 km
6 km
34 km
40 km
77 km
8 km
236 km
579 km
585 km
789 km
761 km
6 km
40 km
15 km
5 km
80 km
6 km
20 km
20 km
6 km
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6.30e19 kg
1.27e21 kg
1.27e21 kg
3.49e21 kg
3.03e21 kg
Voyager 2
Voyager 2
Voyager 2
Voyager 2
Voyager 2
Voyager 2
Voyager 2
Voyager 2
Showalter
Voyager 2
Voyager 2
Voyager 2
Showalter
Kuiper
Lassell
Lassell
Herschel
Herschel
Sheppard
Gladman
Gladman

Nicholson
Sheppard
Holman
Kavelaars
Sheppard
1986
1986
1986
1986
1986
1986
1986
1986
2003
1986
1986
1985
2003
1948
1851
1851
1787
1787
2003
1997
1999

1997
2003
1999
1999
2003

SEE ALSO
William Herschel
Voyager
Titania
Oberon

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The Robinson Library >> Science >> Astronomy >> Solar System

This page was last updated on 04/21/2017.