The image on the right is a composite of four images acquired by Voyager 2 in 1985 showing three moons of Uranus: Umbriel, lower left; Miranda, bottom right; Ariel, top right. At the time when this image was collected, only five moons of Uranus were known. Voyager 2 discovered 10 more moons in 1986, bringing the total to 15.
Since then scientists using the Hubble Space Telescope and powerful Earth-based telescopes have continued to discover more moons orbiting Uranus. In 1997, two moons [Uranus XVI (Caliban) and XVII (Sycorax)] were discovered using the 200-inch Hale telescope at the Palomar Observatory in California, USA. In 1999, another three moons were discovered: one was discovered while comparing images from Voyager 2 and two more were discovered by astronomers using the Canada-France-Hawaii Telescope at Mauna Kea. As of 2014, 27 moons are known to orbit Uranus.
(in order by distance from planet)
| Name | Discoverer | Diameter | Distance From Uranus |
Orbital Period (days) |
| Cordelia | Voyager 2, 1986 | 40 km/25 mi | 49,800 km/30,944 mi | .34 |
| Ophelia | Voyager 2, 1986 | 43 km/27 mi | 53,800 km/33,430 mi | .38 |
| Bianca | Voyager 2, 1986 | 51 km/32 mi | 59,200 km/36,785 mi | .44 |
| Cressida | Voyager 2, 1986 | 80 km/50 mi | 61,800 km/38,401 mi | .46 |
| Desdemona | Voyager 2, 1986 | 64 km/40 mi | 62,700 km/38,960 mi | .47 |
| Juliet | Voyager 2, 1986 | 94 km/59 mi | 64,400 km/40,016 mi | .49 |
| Portia | Voyager 2, 1986 | 135 km/84 mi | 66,100 km/41,073 mi | .51 |
| Rosalind | Voyager 2, 1986 | 72 km/45 mi | 69,900 km/43,434 mi | .56 |
| Cupid | Showalter & Lissauer, 2003 | 36 km/22 mi | 74,392 km/46,225 mi | .61 |
| Belinda | Voyager 2, 1986 | 81 km/50 mi | 75,300 km/46,789 mi | .62 |
| Perdita | Voyager 2, 1986 | 30 km/18 mi | 76,417 km/47,483 mi | .64 |
| Puck | Voyager 2, 1986 | 162 km/101 mi | 86,000 km/53,438 mi | .76 |
| Mab | Showalter & Lissauer, 2003 | 48 km/30 mi | 97,736 km/60,760 mi | .92 |
| Miranda | Kuiper, 1948 | 472 km/293 mi | 129,900 km/80,716 mi | 1.41 |
| Ariel | Lassell, 1851 | 1,158 km/720 mi | 190,900 km/118,600 mi | 2.52 |
| Umbriel | Lassell, 1851 | 1,169 km/726 mi | 266,000 km/165,285 mi | 4.14 |
| Titania | Herschel, 1787 | 1,578 km/981 mi | 436,300 km/271,104 mi | 8.71 |
| Oberon | Herschel, 1787 | 1,523 km/946 mi | 583,500 km/362,570 mi | 13.46 |
| Francisco | Kavalaars, Holman, Milisavljevic & Grav, 2001 | 22 km/14 mi | 4,282,900 km/2,661,271 mi | 267.09 |
| Caliban | Gladman, Nicholson, Burns & Kavelaars, 1997 |
72 km/44.8 mi | 7,231,100km/4,493,197 mi | 579.73 |
| Stephano | Gladman, Holman, Kavelaars, Petit & Scholl, 1999 | 32 km/20 mi | 8,007,400 km/4,975,568 mi | 677.47 |
| Trinculo | Holman, Kavelaars & Milisavljevic, 2001 |
18 km/11 mi | 8,505,200 km/5,284,886 mi | 749.4 |
| Sycorax | Nicholson, Gladman, Burns & Kavelaars, 1997 | 150 km/93 mi | 12,179,400 km/7,567,928 mi | 1288.38 |
| Margaret | Sheppard & Jewitt, 2003 | 20 km/12 mi | 14,146,700 km/8,790,352 mi | 1661 |
Prospero |
Gladman, Petie, Scholl, Kavelaars, Holman, 1999 | 50km/31 mi | 16,276,800 km/10,113,935 mi | 1978.37 |
| Setebos | Kavelaars, Gladman, Holman, Petit & Scholl, 1999 | 48 km/30 mi | 17,420,400 km/10,824,535 mi | 2225.08 |
| Ferdinand | Milisavljevic, Holman, Kavelaars & Grav, 2001 | 20 km/12 mi | 20,430,000 km/12,694,613 mi | 2,970.03 |
Uranus & Satellites
Uranus and its five major moons are depicted in this montage of images acquired by the Voyager 2 spacecraft during its January 1986 flyby of the planet. The moons, counterclockwise from bottom right, are Ariel, Miranda, Titania, Oberon and Umbriel.
Miranda
Miranda is the smallest of the five major satellites of Uranus, measuring just 480 kilometers (300 miles) in diameter. Voyager 2 passed between Miranda and Uranus during 1986, and returned this color composite of the moon.
The carved dark streaks on the surface of this icy moon turned out to be ridges and valleys in higher resolution images.
This high resolution image of Miranda was taken from a distance of 31,000 kilometers (19,000 miles), and shows a cratered surface broken by cliffs up to 20 kilometers (12 miles) high. Such fractures and grooves in the satellite's surface indicate a complex geologic history.
Titania
Titania is the largest satellite of Uranus. This image of Titania is a composite of 2 images taken by Voyager 2 on January 24, 1986.
More Moons:
Before the 1986 Voyager encounter, Uranus was known to have five moons. Those farthest from the planet have the highest density, and may consist of a silicate core covered by a thin, ice-rich crust. The moons show increasingly complex surface features closer to the planet.
Ariel
The next moon out from Miranda, Ariel, is the brightest of the Uranian moons, and has the highest density (1.65 g/cm3).
Umbriel
Umbriel is the darkest of the Uranian moons, and has an icy crust pockmarked by craters. The surface is uniform in reflectivity, with the exception of a bright ring (top), which may be an impact crater.
Oberon
The outermost of the five major satellites, Oberon, appears much like the satellites. Oberon orbits Uranus at more than twice the distance of our own Moon from Earth.
Puck
Ten new moons of Uranus were discovered by Voyager in 1985 and 1986. Puck is only 150 kilometers (93 miles) across, and is the largest of the ten. These ten minor satellites all circle Uranus inside the orbit of Miranda.
