moons of Uranus

Oberon, outermost of the five major moons of UranusOberon, outermost of the five major moons of Uranus, as recorded by Voyager 2 on January 24, 1986. The image, which is the best taken of the moon, shows several large impact craters surrounded by bright rays of ejecta. The most prominent crater, situated just below the center of Oberon's disk, has a bright central peak and a floor partially covered with dark material. Rising on the lower left limb against the dark background is a mountain estimated to be 6 km (4 miles) high.

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.
The Editors of Encyclopaedia Britannica This article was most recently revised and updated by Erik Gregersen.
Citation Information
Article Title: moons of Uranus
Website Name: Encyclopaedia Britannica
Publisher: Encyclopaedia Britannica, Inc.
Date Published: 01 December 2023
URL: https://www.britannica.comhttps://www.britannica.com/topic/moons-of-Uranus-2237295
Access Date: November 23, 2024