Uranus has 27 known 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 2 space probe in January 1986 led to the discovery of a further 10 moons, and another satellite S/1986 U 10 was later found after studying old Voyager photographs. Eleven additional moons have since been identified using telescopes.
All moons of Uranus are named after characters from the works of Shakespeare and Alexander Pope.
The natural satellites
Notes: * Awaiting confirmation and naming; ** Negative orbital periods indicate a retrograde orbit around Uranus (opposite to the planet's rotation).
Name
(Pronunciation key)
| Diameter (km)
| Mass (kg)
| Mean orbital
radius (km)
| Orbital period
| Discovery date
|
| Uranus VI | Cordelia | kor-dee'-lee-a | 40 | 4.5 × 1016 ? | 49,770 | 0.335034 days | 1986
|
| Uranus VII | Ophelia | oh-fee'-lee-a | 42 | 5.4 × 1016 ? | 53,790 | 0.376400 days | 1986
|
| Uranus VIII | Bianca | bee-ahng'-ka | 51 | 9.3 × 1016 ? | 59,170 | 0.434579 days | 1986
|
| Uranus IX | Cressida | kres'-i-da | 80 | 3.43 × 1017 ? | 61,780 | 0.463570 days | 1986
|
| Uranus X | Desdemona | dez'-di-moh'-na | 64 | 1.78 × 1017 ? | 62,680 | 0.473650 days | 1986
|
| Uranus XI | Juliet | jew'-lee-et' | 93 | 5.57 × 1017 ? | 64,350 | 0.493065 days | 1986
|
| Uranus XII | Portia | por'-sha | 135 | 1.68 × 1018 ? | 66,090 | 0.513196 days | 1986
|
| Uranus XIII | Rosalind | roz'-a-lind | 72 | 2.54 × 1017 ? | 69,940 | 0.558460 days | 1986
|
| S/2003 U 2* | 10 | Unknown | 74,800 | 0.618 days | 2003
|
| Uranus XIV | Belinda | be-lin'-da | 80 | 3.57 × 1017 ? | 75,260 | 0.623527 days | 1986
|
| S/1986 U 10* | 20 | Unknown | 76,420 | 0.638 days | 1986
|
| Uranus XV | Puck | puk' | 162 | 2.89 × 1018 ? | 86,010 | 0.761833 days | 1986
|
| S/2003 U 1* | 10 | Unknown | 97,734 | 0.923 days | 2003
|
| Uranus V | Miranda | mi-ran'-da | 472 | 6.6 × 1019 | 129,390 | 1.413479 days | 1948
|
| Uranus I | Ariel | air'-ee-ul | 1158 | 1.35 × 1021 | 191,020 | 2.520379 days | 1851
|
| Uranus II | Umbriel | um'-bree-ul | 1170 | 1.17 × 1021 | 266,300 | 4.144177 days | 1851
|
| Uranus III | Titania | ti-tahn'-ya | 1578 | 3.52 × 1021 | 435,910 | 8.705872 days | 1787
|
| Uranus IV | Oberon | oh'-bur-on | 1523 | 3.01 × 1021 | 583,520 | 13.463239 days | 1787
|
| S/2001 U 3* | 12 | Unknown | 4,276,000 | -266.6 days** | 2001
|
| Uranus XVI | Caliban | kal'-i-ban | 98 | 7.3 × 1017 ? | 7,231,000 | -579.7 days** | 1997
|
| Uranus XX | Stephano | stef'-a-noh | 20 | 6 × 1015 ? | 8,004,000 | -677.4 days** | 1999
|
| Uranus XXI | Trinculo | tring'-kew-loh | 10 | Unknown | 8,504,000 | -759.0 days** | 2001
|
| Uranus XVII | Sycorax | sik'-or-aks | 190 | 5.4 × 1018 ? | 12,179,000 | -1288.3 days** | 1997
|
| S/2003 U 3* | 11 | Unknown | 14,345,000 | 1694.8 days | 2003
|
| Uranus XVIII | Prospero | pros'-pur-oh | 30 | 2.1 × 1016 ? | 16,256,000 | -1977.3 days** | 1999
|
| Uranus XIX | Setebos | set'-e-bus | 30 | 2.1 × 1016 ? | 17,418,000 | -2234.8 days** | 1999
|
| S/2001 U 2* | 12 | Unknown | 20,901,000 | -2823.4 days** | 2001
|
Sources: NASA/NSSDC and University of Hawaii. These sources give no information on the masses for the small satellites; some data have changed greatly so it is unlikely that these old values are correct. Pronunciations are from the Royal Shakespeare Company.
Naming notes
Some asteroids share the same names as moons of Uranus: 171 Ophelia, 218 Bianca, 593 Titania , 666 Desdemona and 2758 Cordelia .
See also