Oberon

Oberon, taken by Voyager 2
Date of discovery |  January 11, 1787[1]
Name of discoverer |  William Herschel[1][2]
Name origin |  King of the fairies in the play A Midsummer Night's Dream by William Shakespeare[2][3]
Orbital characteristics
Primary | Uranus
Order from primary |  18
Periuranion | 583,053 km[4]
Apuranion | 583,987 km[4]
Semi-major axis | 583,520 km[5]
Orbital eccentricity | 0.0008[5]
Sidereal month | 13.463239 da[5]
Avg. orbital speed | 3.15 km/s[2]
Inclination | 0.10°[5] to Uranus's equator
Rotational characteristics
Sidereal day |  13.463239 da[5]
Rotational speed |  0.00411 km/s[4]
Axial tilt |  0°[5]
Physical characteristics
Mass |  3.01 * 1021 kg[5]
Density |  1630 kg/m³[5]
Mean radius |  761.4 km[5]
Surface gravity |  0.3469 m/s²[4]
Escape speed |  0.7268 km/s[4]
Surface area |  7,285,102 km²[4]
Mean temperature |  61 K
Composition |  Water ice and rock[3]
Color |  Light brown-gray
Albedo |  0.25[5]
Oberon or Uranus IV is the eighteenth moon of Uranus, and the outermost of the major moons of Uranus. It is also the second largest moon of Uranus.[3][6]

## Contents

* 1 Discovery and naming
* 2 Orbital characteristics
* 3 Rotational characteristics
* 4 Physical characteristics
* 4.1 Surface
* 5 Problems for uniformitarian theories posed by Oberon
* 6 Observation and Exploration
* 7 References

## Discovery and naming[edit]

William Herschel discovered Oberon and its inner companion, Titania, on January 11, 1787.[1]

Sir John Herschel, his son, named the planet after the king of the fairies in William Shakespeare's comedy, A Midsummer Night's Dream.[1][7]

## Orbital characteristics[edit]

Oberon is in a slightly eccentric orbit around Uranus, at an average distance of 583,520 km. Its sidereal month is about 13.46 Earth days.[5][6]

## Rotational characteristics[edit]

Oberon is in tidal lock with Uranus.[5][6]

## Physical characteristics[edit]

Oberon is the second largest of the moons of Uranus. It is probably composed of water ice and rock.[3][6]

### Surface[edit]

The surface of Oberon has many impact craters. Many of these have bright rays that radiate from them, similar to those found on Callisto.[2][3][6]

The surface, including many of the crater floors, is partially covered with a dark material of unknown origin. Some astronomers speculate that this material is an aqueous solution that upwelled from the interior.[2][6]

## Problems for uniformitarian theories posed by Oberon[edit]

Oberon poses the same problem for uniformitarian astronomy as do all the other moons of Uranus: its orbit is inclined severely to the ecliptic, though not to Uranus' own equator. How the Uranian system came to have such an inclination has never been explained.

## Observation and Exploration[edit]

Oberon is visible on a dark sky through a telescope having an aperture of 30 cm or more.[3]

The only spacecraft to explore Oberon has been Voyager 2. It approached to within 470,600 km of Oberon on January 24, 1986, and took a small number of images.[8][9] No other detailed images are available.

## References[edit]

1. ↑ 1.0 1.1 1.2 1.3 "Gazetteer of Planetary Nomenclature: Planetary Body Names and Discoverers." US Geological Survey, Jennifer Blue, ed. March 31, 2008. Accessed April 17, 2008.
2. ↑ 2.0 2.1 2.2 2.3 2.4 Hamilton, Calvin J. "Entry for Oberon." Views of the Solar System, 2001. Accessed June 16, 2008.
3. ↑ 3.0 3.1 3.2 3.3 3.4 3.5 Arnett, Bill. "Entry for Oberon." The ~~Nine~~ 8 Planets, December 22, 2004. Accessed June 16, 2008.
4. ↑ 4.0 4.1 4.2 4.3 4.4 4.5 Calculated
5. ↑ 5.00 5.01 5.02 5.03 5.04 5.05 5.06 5.07 5.08 5.09 5.10 5.11 Williams, David R. "Uranian Satellite Fact Sheet." National Space Science Data Center, NASA, November 23, 2007. Accessed June 16, 2008.
6. ↑ 6.0 6.1 6.2 6.3 6.4 6.5 Ingersoll, Andrew P. "Oberon." Encyclopædia Britannica. 2008. Encyclopædia Britannica Online. 16 June 2008.
7. ↑ Lassell, William. "Beobachtungen der Uranus-Satelliten." Astronomische Nachrichten 34:325-328, 1852. Accessed June 16, 2008.
8. ↑ "Voyager Mission Description: Voyager 2 Uranus Encounter." February 19, 1997. Accessed June 13, 2008.
9. ↑ Smith, B.A., Soderblom, L.A., Beebe, R., et al. "Voyager 2 in the Uranian system - Imaging science results." Science 233:43-64, July 4, 1986. Accessed June 13, 2008.

v • d • e

The Solar System

Star|

Sol

Terrestrial Planets|

Mercury · Venus · Earth · Mars

Gas Giants|

Jupiter · Saturn · Uranus · Neptune

Dwarf Planets|

Ceres · Haumea · Makemake · Pluto · Eris

Asteroid Belt|

Major asteroids · C-type asteroids · S-type asteroids · M-type asteroids

Trans-Neptunian Objects|

Kuiper belt · Scattered disk · Oort Cloud · Nemesis

Satellites|

Moon · Phobos · Deimos · Io · Europa · Ganymede · Callisto · Mimas · Enceladus · Tethys · Dione · Rhea · Titan · Hyperion · Iapetus · Miranda · Ariel · Umbriel · Titania · Oberon · Triton · Nereid · Charon · Nix · Hydra · Dysnomia

Categories