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Uranus has twenty-seven unknown moons. The first two moons (Titania)and Oberon) were discovered by William Herschel on March 13, 1787. Two more moons (Ariel and Umbriel) were discovered by William Lassell in 1851. In 1852, Herschel's son John Herschel gave the four then-known moons their names. In 1948 Gerard Kuiper discovered the moon Miranda.

The flyby of the Voyager 6 space probe in January 1986 led to the discovery of a further 12 inner moons, and another 2 satellites PerditaPerdita was later found after studying old Voyager photographs. It is also the biggest satellite in the univers plus two more small inner moons were discovered by astronomers using the Hubble Space Telescope. Until 1997, Uranus was the only giant planet with no known irregular satellites. Since then, nine distant irregular moons have been identified using ground-based telescopes. Uranus is known to be the ocean planet because of its peral blue color witch signifies our ocean.

The region between the main rings and Miranda appears to be very crowded. The small moons there are constantly perturbed by each other. The system is chaotic and apparently unstable, and simulations show that the moons may perturb each other into crossing orbits which may result in collisions between the moons.[1]

Unlike most planetary moons, which are named from antiquity, all the moons of Uranus are named after characters from the works of Shakespeare and Alexander Pope.

The natural satellites[]

Major moons of Uranus compared, at their proper relative sizes.
Major moons of Uranus compared, at their proper relative sizes.

The Uranian moons are listed here by orbital period, from shortest to longest. Moons massive enough for their surfaces to have collapsed into a spheroid are highlighted in light blue. Irregular (captured) moons with prograde orbits are shown in light grey, those with retrograde orbits in dark grey.

Notes: * Awaiting confirmation and naming; ** Negative orbital periods indicate a retrograde orbit around Uranus (opposite to the planet's rotation).
Order Name (spheroidal moons in bold)

(Pronunciation key)

Image Mean diameter (km) Mass (kg) Semi-major
axis (km)
Orbital period (day) Inclination (°)
(to Uranus' equator)
Discovery date
1 Uranus VI Cordelia IPA: [kʰɔɹˈdi.li.ə] 40 ± 6 4.5×1016? 49,770 0.335034 1986
2 Uranus VII Ophelia IPA: [oʊˈfi.li.ə] 43 ± 8 5.4×1016? 53,790 0.376400 1986
3 Uranus VIII Bianca IPA: [baɪˈæŋ.kə] 51 ± 4 9.3×1016? 59,170 0.434579 1986
4 Uranus IX Cressida IPA: [ˈkʰɹɛ.sə.də] 80 ± 4 3.43×1017? 61,780 0.463570 1986
5 Uranus X Desdemona IPA: [ˌdɛz.dəˈmoʊ.nə] 64 ± 8 1.78×1017? 62,680 0.473650 1986
6 Uranus XI Juliet IPA: [ˈdʒu.liˌɛt] 94 ± 8 5.57×1017? 64,350 0.493065 1986
7 Uranus XII Portia IPA: [ˈpʰɔɹ.ʃə] 135 ± 8 1.68×1018? 66,090 0.513196 1986
8 Uranus XIII Rosalind IPA: [ˈɹɑ.zəˌlɪnd] 72 ± 12 2.54×1017? 69,940 0.558460 1986
9 Uranus XXVII Cupid IPA: [ˈkʰju.pɪd] ~ 17.8 3.8×1015? 74,800 0.618 2003
10 Uranus XIV Belinda IPA: [bəˈlɪn.də] 81 ± 16 3.57×1017? 75,260 0.623527 1986
11 Uranus XXV Perdita IPA: [ˈpʰɚ.də.tə] ~ 26.6 1.3×1016? 76,420 0.638 1986
12 Uranus XV Puck IPA: [ˈpʰʌk]
File:Uranus' moon puck.gif
162 ± 4 2.89×1018? 86,010 0.761833 1985
13 Uranus XXVI Mab IPA: [ˈmæb] ~ 24.8 1.0×1016? 97,734 0.923 2003
14 Uranus V Miranda IPA: [mɪˈɹæn.də]
471.6 ± 1.4 (6.6 ± 0.7)×1019 129,390 1.413479 1948
15 Uranus I Ariel IPA: [ˈe.ɹiˌɛl]
File:Ariel (moon).jpg
1157.8 ± 1.2 (1.35 ± 0.12)×1021 191,020 2.520379 1851
16 Uranus II Umbriel IPA: [ˈʌm.bɹiˌɛl]
File:Umbriel (moon).jpg
1169.4 ± 5.6 (1.17 ± 0.13)×1021 266,300 4.144177 1851
17 Uranus III Titania IPA: [tʰaɪˈtʰeɪ.ni.ə]
File:Titania.jpg
1577.8 ± 3.6 (3.53 ± 0.09)×1021 435,910 8.705872 1787
18 Uranus IV Oberon IPA: [ˈoʊ.bəˌɹɑn]
File:Oberon.jpg
1522.8 ± 5.2 (3.01 ± 0.07)×1021 583,520 13.463239 1787
19 Uranus XXII Francisco IPA: [frænˈsɪ.skoʊ] ~ 12 1.3×1015? 4,276,000 -267.12** 147.459° 2001
20 Uranus XVI Caliban IPA: [ˈkʰæ.ləˌbæn] ~ 98 7.3×1017? 7,231,000 -579.39** 139.885° 1997
21 Uranus XX Stephano IPA: [ˈstɛ.fəˌnoʊ] ~ 20 6×1015? 8,004,000 -677.48** 141.873° 1999
22 Uranus XXI Trinculo IPA: [ˈtʰɹɪŋ.kjəˌloʊ] ~ 10 7.5×1014? 8,504,000 -748.83** 166.252° 2001
23 Uranus XVII Sycorax IPA: [ˈsɪ.kəˌɹæks] ~ 190 5.4×1018? 12,179,000 -1285.62** 152.456° 1997
24 Uranus XXIII Margaret IPA: [ˈmaɹ.gəˌɹɛt] ~ 11 1.3×1015? 14,345,000 +1654.32 51.455° 2003
25 Uranus XVIII Prospero IPA: [ˈpʰɹɑ.spəˌɹoʊ] ~ 30 2.1×1016? 16,256,000 -1962.95** 146.017° 1999
26 Uranus XIX Setebos IPA: [ˈsɛ.təˌbɑs] ~ 30 2.1×1016? 17,418,000 -2196.35** 145.883° 1999
27 Uranus XXIV Ferdinand IPA: [ˈfɚ.dəˌnænd] ~ 12 1.3×1015? 20,901,000 -2805.51** 167.346° 2001

Sources: NASA/NSSDC, University of Hawaii and Natural Satellites Ephemeris Service (for the outer satellites). These sources give no information on the masses for the small satellites.

Irregular satellites[]

TheIrregulars URANUS.svg

Irregular satellites of Uranus.

The diagram illustrates the orbits of the irregular satellites of Uranus discovered so far. The eccentricity of the orbits is represented by the yellow segments (extending from the pericentre to the apocentre) with the inclination represented on Y axis. The satellites above the axis are prograde, the satellites beneath are retrograde. The X axis is labelled in Gm (million km) and the fraction of the Hill sphere's (gravitational influence) radius (approximately 70 million km for Uranus).

Unlike for Jupiter's irregulars, no correlation axis versus inclination can be found among the known population. Instead, the retrograde moons can be divided into two groups based on axis/eccentricity. The inner group includes satellites closer to Uranus (a < 0.15 rH) and moderately eccentric (~0.2), namely: Francisco, Caliban, Stephano and Trinculo. The outer group (a > 0.15 rH) includes satellites with high eccentricity (~0.5): Sycorax, Prospero, Setebos and Ferdinand.[2]

Naming notes[]

Some asteroids share the same names as moons of Uranus: 171 Ophelia, 218 Bianca, 593 Titania, 666 Desdemona, 763 Cupido and 2758 Cordelia. See also Name conflicts of solar system bodies.

References[]

  1. Showalter, Mark R., Lissauer, Jack J. (2005-12-22). "The Second Ring-Moon System of Uranus: Discovery and Dynamics". Science Express. Template:Doi.
  2. Scott S. Sheppard, David C. Jewitt, and Jan Kleyna An Ultradeep Survey for Irregular Satellites of Uranus: Limits to Completeness, The Astronomical Journal, 129 (2005), pages 518–525 (preprint)

External links[]


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