moons of Uranus
The planet Uranus has 27 known moons. Uranus’s five largest moons—Miranda, Ariel, Umbriel, Oberon, and Titania—range from about 240 to 800 km (150 to 500 miles) in radius. All were discovered telescopically from Earth, four of them before the 20th century. Ten small inner moons were found by Voyager 2 in 1985–86. An 11th tiny inner moon, Perdita, photographed by Voyager near the orbit of Belinda, remained unnoticed in the images until 1999 and was not confirmed until 2003. The other small moons were discovered from Earth beginning in 1997.
The moons are named for characters in the plays of William Shakespeare or in Alexander Pope’s The Rape of the Lock. The moons are listed in order of increasing distance from Uranus, with the year of their discovery, orbital period in days, and diameter in kilometers.
| name | year discovered | distance from Uranus (km) | orbital period (days)* | diameter (km) |
|---|---|---|---|---|
| Cordelia | 1986 | 49,800 | 0.335 | 40 |
| Ophelia | 1986 | 53,800 | 0.376 | 42 |
| Bianca | 1986 | 59,200 | 0.435 | 52 |
| Cressida | 1986 | 61,800 | 0.464 | 80 |
| Desdemona | 1986 | 62,700 | 0.474 | 64 |
| Juliet | 1986 | 64,400 | 0.493 | 94 |
| Portia | 1986 | 66,100 | 0.513 | 136 |
| Rosalind | 1986 | 69,900 | 0.558 | 72 |
| Cupid | 2003 | 74,392 | 0.613 | 10 |
| Belinda | 1986 | 75,300 | 0.624 | 80 |
| Perdita | 1986 | 76,417 | 0.638 | 20 |
| Puck | 1985 | 86,000 | 0.762 | 162 |
| Mab | 2003 | 97,736 | 0.923 | 10 |
| Miranda | 1948 | 129,900 | 1.413 | 471.4 |
| Ariel | 1851 | 190,900 | 2.52 | 1,157.8 |
| Umbriel | 1851 | 266,000 | 4.144 | 1,169.4 |
| Titania | 1787 | 436,300 | 8.706 | 1,577.8 |
| Oberon | 1787 | 583,500 | 13.46 | 1,522.8 |
| Francisco | 2001 | 4,276,000 | 266.56 R | 22 |
| Caliban | 1997 | 7,231,000 | 579.73 R | 72 |
| Stephano | 1999 | 8,004,000 | 677.36 R | 32 |
| Trinculo | 2001 | 8,504,000 | 749.24 R | 18 |
| Sycorax | 1997 | 12,179,000 | 1,288.3 R | 150 |
| Margaret | 2003 | 14,345,000 | 1,687.01 | 20 |
| Prospero | 1999 | 16,256,000 | 1,978.29 R | 50 |
| Setebos | 1999 | 17,418,000 | 2,225.21 R | 48 |
| Ferdinand | 2001 | 20,901,000 | 2,887.21 R | 20 |
| *The “R” following the orbital period means the orbit of that satellite is retrograde. | ||||