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The Moons of Uranus

The image at right is a composite of four images acquried 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 5 moons of Uranus were known. Voyager 2 discovered 10 more moons in 1986, bringing the total to 15.

Uranus image
12k JPEG
NASA Press Release image #P-29313
In the past few years, five new moons have been discovered orbiting Uranus, but not all of their names have been officially accepted by the International Astronomical Union. 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: Uranus XVIII (1986U10) was discovered while comparing images from Voyager 2 and the Hubble Space Telescope, and Uranus XIX(1999U1) and XX(1999U2) were discovered by astronomers using the Canada-France-Hawaii Telescope at Mauna Kea. For the latest information on the acceptance of names for Uranian satellites, see the International Astronomical Union web site.


Uranian Satellites
(in order by distance from planet)

Name Discoverer Diameter Distance From
Uranus		 Orbital
Period
(days)
Cordelia Voyager 2, 1986 25 km/16 mi 49,750 km/30,910 mi .34
Ophelia Voyager 2, 1986 25 km/16 mi 53,760 km/33,400 mi .38
Bianca Voyager 2, 1986 45 km/28 mi 59,160 km/36,760 mi .44
Cressida Voyager 2, 1986 65 km/40 mi 61,770 km/38,400 mi .46
Desdemona Voyager 2, 1986 60 km/37 mi 62,660 km/38,940 mi .47
Juliet Voyager 2, 1986 85 km/53 mi 64,360 km/40,000 mi .49
Portia Voyager 2, 1986 110 km/68 mi 66,100 km/41,070 mi .51
Rosalind Voyager 2, 1986 60 km/37 mi 69,930 km/43,500 mi .56
Belinda Voyager 2, 1986 68 km/42 mi 72,260 km/46,800 mi .62
Puck Voyager 2, 1986 155 km/96 mi 86,010 km/53,440 mi .76
Miranda Kuiper, 1948 485 km/301 mi 129,780 km/80,640 mi 1.41
Ariel Lassell, 1851 1,160 km/721 mi 191,240 km/118,800 mi 2.52
Umbriel Lassell, 1851 1,190 km/739 mi 265,970 km/165,300 mi 4.14
Titania Herschel, 1787 1,610 km/1,000 mi 435,840 km/270,800 mi 8.71
Oberon Herschel, 1787 1,550 km/963 mi 582,600 km/362,000 mi 13.46
1997U1
(Caliban*) 		Gladman, Nicholson,
Burns & Kavelaars, 1997		 approx. 80km/49.6mi 7,164,647km/4,442,081mi 579.4
1999U1 Gladman, Petie, Scholl, Kavelaars, Holman, 1999 20 km/12.4 mi 10,000,000 km/6,200,000mi n/a
1997U2
(Sycorax*) 		Gladman, Nicholson,
Burns & Kavelaars, 1997		 approx. 160km/99.2mi 12,174,687km/7,548,305mi 1284
1999U2 Gladman, Petie, Scholl, Kavelaars, Holman, 1999 20km/12.4 mi 25,000,000 km/15,500,000mi n/a
1999U3 Gladman, Petie, Scholl, Kavelaars, Holman, 1999 20km/12.4 mi 10-25,000,000 km/6,200,000-15,500,000 mi n/a
2001U1 Holman, Kavelaars, Gladman, Petie, 2001 n/a n/a n/a
2003U1 Showalter and Lissauer, 2003 16 km/10 mi 97,700 km
60,700 mi		 .92
2003U2 Showalter and Lissauer, 2003 12 km/8 mi 74,800 km
46,500 mi		 .62
1986U10 Voyager 2, 1986
Karkoschka, 1999		 40 km/25 mi 75,000 km
46,600 mi		 .62

*Name has been provisionally approved by the IAU.

 

Uranus & Satellites


108k GIF
NASA/JPL press
release photo #P31143. 		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

163k GIF - 39k JPEG -- NASA Press Release #P29524
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.

Ariel 226k GIF - 57k JPEG-- NASA Press Release #29515
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

160k GIF - 160k JPEG--NASA Press Release #29522
Titania is the largest satellite of Uranus. This high-resolution 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

Ariel185k GIF - 47k JPEG-- NASA Press Release #29520
The next moon out from Miranda, Ariel, is the brightest of the Uranian moons, and has the highest density (1.65 g/cm³ ).




Umbriel

Umbriel185k GIF - 38k JPEG-- NASA Press Release #29520
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

Oberon163k GIF - 35k JPEG-- NASA Press Release #29520
The outermost of Uranus' five major satellites, Oberon, appears much like the satellites of Jupiter and Saturn. 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 77 kilometers (48 miles) across, and is the largest of the ten. These ten minor satellites all circle Uranus inside the orbit of Miranda.

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