Uranus, the seventh planet of the Solar System, has 27 known moons,[1] all of which are named after characters from the works of William Shakespeare and Alexander Pope.[2] William Herschel discovered the first two moons, Titania and Oberon, in 1787, and the other spherical moons were discovered in 1851 by William Lassell (Ariel and Umbriel) and in 1948 by Gerard Kuiper (Miranda).[2] The remaining moons were discovered after 1985, either during the Voyager 2 flyby mission or with the aid of advanced Earth-based telescopes.[1][3]

Uranian moons are divided into three groups: thirteen inner moons, five major moons, and nine irregular moons. The inner moons are small dark bodies that share common properties and origins with the planet's rings. The five major moons are massive enough to have achieved hydrostatic equilibrium, and four of them show signs of internally driven processes such as canyon formation and volcanism on their surfaces.[3] The largest of these five, Titania, is 1,578 km in diameter and the eighth-largest moon in the Solar System, and about 20 times less massive than Earth's Moon. Uranus's irregular moons have elliptical and strongly inclined (mostly retrograde) orbits at great distances from the planet.[1]

Discovery

The first two moons to be discovered, Titania and Oberon, were spotted by Sir William Herschel on January 11, 1787, six years after he had discovered the planet itself. Later, Herschel thought he had discovered up to six moons (see below) and perhaps even a ring. For nearly 50 years, Herschel's instrument was the only one with which the moons had been seen.[4] In the 1840s, better instruments and a more favorable position of Uranus in the sky led to sporadic indications of satellites additional to Titania and Oberon. Eventually, the next two moons, Ariel and Umbriel, were discovered by William Lassell in 1851.[5] The Roman numbering scheme of Uranus's moons was in a state of flux for a considerable time and publications hesitated between Herschel's designations (where Titania and Oberon are Uranus II and IV) and William Lassell's (where they are sometimes I and II).[6] With the confirmation of Ariel and Umbriel, Lassell numbered the moons I through IV from Uranus outward, and this finally stuck.[7] In 1852, Herschel's son John Herschel gave the four then-known moons their names.[8]

No other discoveries were made for almost another century. In 1948, Gerard Kuiper at the McDonald Observatory discovered the smallest and the last of the five large, spherical moons, Miranda.[8][9] Decades later, the flyby of the Voyager 2 space probe in January 1986 led to the discovery of ten further inner moons.[3] Another satellite, Perdita, was retroactively discovered in 1999[10] after studying old Voyager photographs.[11]

Uranus was the last giant planet without any known irregular satellites, but since 1997 nine distant irregular moons have been identified using ground-based telescopes.[1] Two more small inner moons, Cupid and Mab, were discovered using the Hubble Space Telescope in 2003.[12] The moon Margaret was the last Uranian moon discovered as of 2008, and its findings were published in October 2003.[13]

Spurious moons

After Herschel discovered Titania and Oberon on January 11, 1787, he subsequently believed that he observed four other moons; two on January 18 and February 9, 1790, and two more on February 28 and March 26, 1794. It was thus believed for many decades thereafter that Uranus had a system of six satellites, though the four latter moons were never confirmed by any other astronomer. Lassell's observations of 1851, in which he discovered Ariel and Umbriel, however, failed to support Herschel's observations; Ariel and Umbriel, which Herschel certainly ought to have seen if he had seen any satellites beside Titania and Oberon, did not correspond to any of Herschel's four additional satellites in orbital characteristics. Herschel's four spurious satellites were thought to have sidereal periods of 5.89 days (interior to Titania), 10.96 days (between Titania and Oberon), 38.08 and 107.69 days (exterior to Oberon).[14] It was therefore concluded that Herschel's four satellites were spurious, probably arising from the misidentification of small stars in the vicinity of Uranus as satellites, and the credit for the discovery of Ariel and Umbriel was given to Lassell.[15]

Names
Main article: Naming of moons
See also: Name conflicts of solar system objects

The first two Uranian moons, discovered in 1787, did not receive names until 1852, a year after two more moons had been discovered. The responsibility for naming was taken by John Herschel, son of the discoverer of Uranus. Herschel, instead of assigning names from Greek mythology, named the moons after magical spirits in English literature: the fairies Oberon and Titania from William Shakespeare's A Midsummer Night's Dream, and the sylphs Ariel and Umbriel from Alexander Pope's The Rape of the Lock (Ariel is also a sprite in Shakespeare's The Tempest). The reasoning was presumably that Uranus, as god of the sky and air, would be attended by spirits of the air.[16]

Subsequent names, rather than continuing the airy spirits theme (only Puck and Mab continued the trend), have focused on Herschel's source material. In 1949, the fifth moon, Miranda, was named by its discoverer Gerard Kuiper after a thoroughly mortal character in Shakespeare's The Tempest. The current IAU practice is to name moons after characters from Shakespeare's plays and The Rape of the Lock (although at present only Ariel, Umbriel, and Belinda have names drawn from the latter poem; all the rest are from Shakespeare). At first, the outermost moons were all named after characters from one play, The Tempest; but with Margaret being named from Much Ado About Nothing that trend has ended.[8]
The relative masses of the Uranian moons. The five rounded moons vary from Miranda at 0.7% to Titania at almost 40% of the total mass. The other moons collectively constitute 0.1%, and are barely visible at this scale.

* The Rape of the Lock (a poem by Alexander Pope):
o Ariel, Umbriel, Belinda
* Plays by William Shakespeare:
o A Midsummer Night's Dream: Titania, Oberon, Puck
o The Tempest: (Ariel), Miranda, Caliban, Sycorax, Prospero, Setebos, Stephano, Trinculo, Francisco, Ferdinand
o King Lear: Cordelia
o Hamlet: Ophelia
o The Taming of the Shrew: Bianca
o Troilus and Cressida: Cressida
o Othello: Desdemona
o Romeo and Juliet: Juliet, Mab
o The Merchant of Venice: Portia
o As You Like It: Rosalind
o Much Ado About Nothing: Margaret
o The Winter's Tale: Perdita
o Timon of Athens: Cupid

Some asteroids share names with moons of Uranus: 171 Ophelia, 218 Bianca, 593 Titania, 666 Desdemona, 763 Cupido and 2758 Cordelia.

Characteristics and groups
Schematic of the Uranian moon-ring system

The Uranian satellite system is the least massive among those of the gas giants; indeed, the combined mass of the five major satellites would be less than half that of Triton (the seventh-largest moon in the Solar System) alone.[note 1] The largest of the satellites, Titania, has a radius of 788.9 km,[18] or less than half that of the Moon, but slightly more than half that of Rhea, the second largest moon of Saturn, making Titania the eighth-largest moon in the Solar System. Uranus is about 10,000 times more massive than its moons.[note 2]

Inner moons
See also: Inner moon and Rings of Uranus

As of 2008, Uranus is known to possess 13 inner moons.[12] Their orbits lie inside that of Miranda. All inner moons are intimately connected to the rings of Uranus, which probably resulted from the fragmentation of one or several small inner moons.[19] The two innermost moons (Cordelia and Ophelia) serve as shepherds of Uranus's ε ring, while small moon Mab is a source of Uranus's outermost μ ring.[12]

Puck, at 162 km, is the largest of the inner moons of Uranus and the only one imaged by Voyager 2 in any detail. Puck and Mab are the 2 outermost inner satellites of Uranus. All inner moons are dark objects; their geometrical albedo does not exceed 10%.[20] They are made of water ice contaminated with a dark material—probably radiation processed organics.[21]

The small inner moons constantly perturb each other. The system is chaotic and apparently unstable. Simulations show that the moons may perturb each other into crossing orbits, which may eventually result in collisions between the moons.[12] Desdemona may collide with either Cressida or Juliet within the next 100 million years.[22]
The five largest moons of Uranus compared at their proper relative sizes and brightnesses. From left to right (in order of increasing distance from Uranus): Miranda, Ariel, Umbriel, Titania and Oberon.

Large moons

Uranus has five major moons: Miranda, Ariel, Umbriel, Titania and Oberon. They range in diameter from 472 km for Miranda to 1578 km for Titania.[18] All large moons are relatively dark objects: their geometrical albedo varies in the range of 30–50%, while bond albedo is within the range of 10–23%.[20] Umbriel is the darkest moon and Ariel is the brightest. The masses of the moons range from 6.7 × 1019 kg (Miranda) to 3.5 × 1021 kg (Titania)—for comparison, Earth's Moon has mass of 7.5 × 1022 kg.[23] The major moons of Uranus are believed to have formed in the accretion disc, which existed around Uranus for some time after its formation or resulted from the large impact suffered by Uranus early in its history.[24][25]
Artist's conception of the Sun's path in the summer sky of a major moon of Uranus (which shares Uranus' axial tilt)

All major moons comprise approximately equal amounts rock and ice, except Miranda, which is made primarily of ice.[26] The ice component may include ammonia and carbon dioxide.[27] Their surfaces are heavily cratered, though all of them (except Umbriel) show signs of endogenic resurfacing in the form of lineaments (canyons) and, in the case of Miranda, ovoid race-track like structures called coronae.[3] Extensional processes associated with upwelling diapirs are likely responsible for the origin of the coronae.[28] Ariel appears to have the youngest surface with the fewest impact craters, while Umbriel's appears oldest.[3] A past 3:1 orbital resonance between Miranda and Umbriel and a past 4:1 resonance between Ariel and Titania are thought to be responsible for the heating that caused substantial endogenic activity on Miranda and Ariel.[29][30] One piece of evidence for such a past resonance is Miranda's unusually high orbital inclination (4.34°) for a body so close to the planet.[31][32] The largest Uranian moons may be internally differentiated, with rocky cores at their centers surrounded by ice mantles.[26] Titania and Oberon may harbor liquid water oceans at the core/mantle boundary.[26] The major moons of Uranus are airless bodies. For instance, Titania was shown to possess no atmosphere at a pressure larger than 10–20 nanobar.[33]

The path of the Sun in the local sky over the course of a local day during Uranus' and its major moons' solstice is quite different from that seen on most other Solar System worlds. The major moons have almost exactly the same rotational axial tilt as Uranus' (their axes are parallel to that of Uranus).[3] The Sun would appear to follow a circular path around Uranus' celestial pole in the sky, at the closest about 7 degrees away from it.[note 3] Near the equator, it would be seen nearly due north or due south (depending on the season). At latitudes higher than 7°, the Sun would trace a circular path about 15 degrees diameter in the sky, and never set.
Irregular moons of Uranus. The X axis is labeled in Gm (million km) and in the fraction of the Hill sphere's radius. The eccentricity is represented by the yellow segments (extending from the pericentre to the apocentre) with the inclination represented on the Y axis.

Irregular moons
See also: Irregular moon

As of 2005 Uranus is known to have nine irregular moons, which circle the planet at a distance much greater than that of Oberon, the furthest of the large moons. All the irregular moons are probably captured objects that were trapped by Uranus soon after its formation.[1] The diagram illustrates the orbits of those irregular moons discovered so far. The moons above the X axis are prograde, those beneath are retrograde. The radius of the Uranus' Hill sphere is approximately 73 million km.[1]

Uranus's irregular moons range in size from about 150 km (Sycorax) to 18 km (Trinculo).[1] Unlike Jupiter's irregulars, Uranus's show no correlation axis versus inclination. Instead, the retrograde moons can be divided into two groups based on axis/orbital eccentricity. The inner group includes those satellites closer to Uranus (a < 0.15 rH) and moderately eccentric (~0.2), namely Francisco, Caliban, Stephano and Trinculo.[1] The outer group (a > 0.15 rH) includes satellites with high eccentricity (~0.5): Sycorax, Prospero, Setebos and Ferdinand.[1]

The intermediate inclinations 60° < i < 140° are devoid of known moons due to the Kozai instability.[1] In this instability region, solar perturbations at apoapse cause the moons to acquire large eccentricities that lead to collisions with inner satellites or ejection. The lifetime of moons in the instability region is from 10 million to a billion years.[1]

Margaret is the only known irregular prograde moon of Uranus, and it currently has the most eccentric orbit of any moon in the solar system, though Neptune's moon Nereid has a higher mean eccentricity. As of 2008, Margaret's eccentricity is 0.7979.[34]

Table
Key
‡
Major moons ♠
Retrograde moons

The Uranian moons are listed here by orbital period, from shortest to longest. Moons massive enough for their surfaces to have collapsed into a spheroid are highlighted in light blue and bolded. Irregular moons with prograde orbits are shown in light grey, those with retrograde orbits in dark grey.

Order [note 4]	Label [note 5]	Name	Pronunciation (key)	Diameter (km)[note 6]	Mass ( × 1018 kg)[note 7]	Semi-major axis (km)[35]	Orbital period (d)[35][note 8]	Inclination (°)[35]	Eccentricity [36]	Discovery year[2]	Discoverer [2]
1	06 !VI	Cordelia	kɔrˈdiːliə	0040 !40 ± 6 (50 × 36)	000004 !0.044	00049000 !49,751	0000.33 !0.335034	000.084 !0.08479°	0.00026	1986	Terrile (Voyager 2)
2	07 !VII	Ophelia	ɵˈfiːliə	0043 !43 ± 8 (54 × 38)	000005 !0.053	00053000 !53,764	0000.37 !0.376400	000.103 !0.1036°	0.00992	1986	Terrile (Voyager 2)
3	08 !VIII	Bianca	biːˈɒŋkə	0051 !51 ± 4 (64 × 46)	000009 !0.092	00059000 !59,165	0000.43 !0.434579	000.193 !0.193°	0.00092	1986	Smith (Voyager 2)
4	09 !IX	Cressida	ˈkrɛsɨdə	0080 !80 ± 4 (92 × 74)	000034 !0.34	00061000 !61,766	0000.46 !0.463570	000.006 !0.006°	0.00036	1986	Synnott (Voyager 2)
5	10 !X	Desdemona	ˌdɛzdɨˈmoʊnə	0064 !64 ± 8 (90 × 54)	000018 !0.18	00062000 !62,658	0000.47 !0.473650	000.111 !0.11125°	0.00013	1986	Synnott (Voyager 2)
6	11 !XI	Juliet	ˈdʒuːli.ɨt	0094 !94 ± 8 (150 × 74)	000056 !0.56	00064000 !64,360	0000.49 !0.493065	000.065 !0.065°	0.00066	1986	Synnott (Voyager 2)
7	12 !XII	Portia	ˈpɔrʃə	0135 !135 ± 8 (156 × 126)	000170 !1.70	00066000 !66,097	0000.51 !0.513196	000.059 !0.059°	0.00005	1986	Synnott (Voyager 2)
8	13 !XIII	Rosalind	ˈrɒzəlɨnd	0072 !72 ± 12	000025 !0.25	00069000 !69,927	0000.55 !0.558460	000.279 !0.279°	0.00011	1986	Synnott (Voyager 2)
9	27 !XXVII	Cupid	ˈkjuːpɨd	0018 !~18	000000.38 !0.0038	00074000 !74,800	0000.61 !0.618	000.1 !0.1°	0.0013	2003	Showalter and Lissauer
10	14 !XIV	Belinda	bɨˈlɪndə	0090 !90 ± 16 (128 × 64)	000049 !0.49	00075000 !75,255	0000.62 !0.623527	000.031 !0.031°	0.00007	1986	Synnott (Voyager 2)
11	25 !XXV	Perdita	ˈpɜrdɨtə	0030 !30 ± 6	000002 !0.018	00076000 !76,420	0000.63 !0.638	000 !0.0°	0.0012	1999	Karkoschaka (Voyager 2)
12	15 !XV	Puck	ˈpʌk	0162 !162 ± 4	000290 !2.90	00086000 !86,004	0000.76 !0.761833	000.319 !0.3192°	0.00012	1985	Synnott (Voyager 2)
13	26 !XXVI	Mab	ˈmæb	0025 !~25	000001 !0.01	00097000 !97,734	0000.92 !0.923	000.133 !0.1335°	0.0025	2003	Showalter and Lissauer
14	05 !V	‡Miranda	mɨˈrændə	0470 !471.6 ± 1.4 (481 × 468 × 466)	006600 !65.9 ± 7.5	00129000 !129,390	0001.4 !1.413479	004 !4.232°	0.0013	1948	Kuiper
15	01 !I	‡Ariel	ˈɛəriəl	1157 !1,157.8 ± 1.2 (1162 × 1156 × 1155)	135000 !1,353 ± 120	00191000 !191,020	0002.5 !2.520379	000.260 !0.260°	0.0012	1851	Lassell
16	02 !II	‡Umbriel	ˈʌmbriəl	1169 !1,169.4 ± 5.6	117000 !1,172 ± 135	00266000 !266,300	0004.1 !4.144177	000.205 !0.205°	0.?	1851	Lassell
17	03 !III	‡Titania	tɨˈtɑːnjə	1577 !1,576.8 ± 1.2	353000 !3,527 ± 90	00435000 !435,910	0008.7 !8.705872	000.340 !0.340°	0.0011	1787	Herschel
18	04 !IV	‡Oberon	ˈoʊbərɒn	1522 !1,522.8 ± 5.2	301000 !3,014 ± 75	00583000 !583,520	0013 !13.463239	000.058 !0.058°	0.0014	1787	Herschel
19	22 !XXII	♠Francisco	frænˈsɪskoʊ	0022 !~22	000000.72 !0.0072	04000000 !4,276,000	0266 !−266.56	147.459°	0.1459	2003[note 9]	Holman et al.
20	16 !XVI	♠Caliban	ˈkælɨbæn	0072 !~72	000025 !0.25	07000000 !7,231,000	0579 !−579.73	139.885°	0.1587	1997	Gladman et al.
21	20 !XX	♠Stephano	ˈstɛfənoʊ	0032 !~32	000002.2 !0.022	08000000 !8,004,000	0677 !−677.37	141.873°	0.2292	1999	Gladman et al.
22	21 !XXI	♠Trinculo	ˈtrɪŋkjʊloʊ	0018 !~18	000000.39 !0.0039	08000000 !8,504,000	0749 !−749.24	166.252°	0.2200	2001	Holman et al.
23	17 !XVII	♠Sycorax	ˈsɪkəræks	0150 !~150	000230 !2.30	12,179,000	1288 !−1288.28	152.456°	0.5224	1997	Nicholson et al.
24	23 !XXIII	Margaret	ˈmɑrɡərɨt	0020 !~20	000000.54 !0.0054	14,345,000	1687 !1687.01	051 !51.455°	0.6608	2003	Sheppard and Jewitt
25	18 !XVIII	♠Prospero	ˈprɒspəroʊ	0050 !~50	000008.5 !0.085	16,256,000	1978 !−1978.29	146.017°	0.4448	1999	Holman et al.
26	19 !XIX	♠Setebos	ˈsɛtɨbʌs	0048 !~48	000007.5 !0.075	17,418,000	2225 !−2225.21	145.883°	0.5914	1999	Kavelaars et al.
27	24 !XXIV	♠Ferdinand	ˈfɜrdɨnænd	0020 !~20	000000.54 !0.0054	20,901,000	2805 !−2805.51	167.346°	0.3682	2003[note 9]	Holman et al.

Sources: NASA/NSSDC,[35] Sheppard, et al. 2005.[1] For the recently discovered outer irregular moons (Francisco through Ferdinand) the most accurate orbital data can be generated with the Natural Satellites Ephemeris Service.[34] The irregulars are significantly perturbed by the Sun.[1]

Notes

1. ^ The mass of Triton is about 2.14 × 1022 kg,[17] whereas the combined mass of the Uranian moons is about 0.92 × 1022 kg.
2. ^ Uranus mass of 8.681 × 1025 kg / Mass of Uranian moons of 0.93 × 1022 kg
3. ^ The axial tilt of Uranus is 97°.[3]
4. ^ Order refers to the position among other moons with respect to their average distance from Uranus.
5. ^ Label refers to the Roman numeral attributed to each moon in order of their discovery.[2]
6. ^ Diameters with multiple entries such as "60 × 40 × 34" reflect that the body is not a perfect spheroid and that each of its dimensions have been measured well enough. The diameters and dimensions of Miranda, Ariel, Umbriel and Oberon were taken from Thomas, 1988.[18] The diameter of Titania is from Widemann, 2008.[33] The dimensions and radii of the inner moons are from Karkoschka, 2001,[11] except for Cupid and Mab, which were taken from Showalter, 2006.[12] The radii of outer moons were taken from Sheppard, 2005.[1]
7. ^ Masses of Miranda, Ariel, Umbriel, Titania and Oberon were taken from Jacobson, 1992.[23] Masses of all other moons were calculated assuming a density of 1.3 g/cm3 and using given radii.
8. ^ Negative orbital periods indicate a retrograde orbit around Uranus (opposite to the planet's rotation).
9. ^ a b Detected in 2001, published in 2003.

References

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2. ^ a b c d e "Planet and Satellite Names and Discoverers". Gazetteer of Planetary Nomenclature. USGS Astrogeology. July 21 2006. http://planetarynames.wr.usgs.gov/append7.html. Retrieved 2006-08-06.
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4. ^ Herschel, John (1834). "On the Satellites of Uranus". Monthly Notices of the Royal Astronomical Society 3 (5): 35–36. http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1834MNRAS...3Q..35H&db_key=AST&data_type=HTML&format=&high=45eb6e10af10464.
5. ^ Lassell, W. (1851). "On the interior satellites of Uranus". Monthly Notices of the Royal Astronomical Society 12: 15–17. http://adsabs.harvard.edu/abs/1851MNRAS..12...15L.
6. ^ Lassell, W. (1848). "Observations of Satellites of Uranus". Monthly Notices of the Royal Astronomical Society 8 (3): 43–44. http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1848MNRAS...8...43.&db_key=AST&data_type=HTML&format=&high=45eb6e10af10464.
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8. ^ a b c Kuiper, Gerard P. (1949). "The Fifth Satellite of Uranus". Publications of the Astronomical Society of the Pacific 61 (360): 129. doi:10.1086/126146. http://adsabs.harvard.edu/abs/1949PASP...61..129K. edit
9. ^ Kaempffert, Waldemar (December 26, 1948). "Science in Review: Research Work in Astronomy and Cancer Lead Year's List of Scientific Developments". The New York Times: p. 87. ISSN 1494850. http://select.nytimes.com/gst/abstract.html?res=F00F1EFE3F5E167B93C4AB1789D95F4C8485F9.
10. ^ Karkoschka, E. (1999-05-18). "IAUC 7171: S/1986 U 10; C/1999 J2; V1333 Aql". IAU Circular. http://cfa-www.harvard.edu/iauc/07100/07171.html. Retrieved 2009-10-31.
11. ^ a b Karkoschka, Erich (2001). "Voyager's Eleventh Discovery of a Satellite of Uranus and Photometry and the First Size Measurements of Nine Satellites". Icarus 151: 69–77. doi:10.1006/icar.2001.6597. http://adsabs.harvard.edu/abs/2001Icar..151...69K. edit
12. ^ a b c d e Showalter, Mark R.; Lissauer, Jack J. (2006). "The Second Ring-Moon System of Uranus: Discovery and Dynamics". Science 311: 973–977. doi:10.1126/science.1122882. PMID 16373533. http://adsabs.harvard.edu/abs/2006Sci...311..973S. edit
13. ^ Green, Daniel W. E. (2003-10-09). "IAUC 8217: S/2003 U 3; 157P; AG Dra". IAU Circular. http://www.cfa.harvard.edu/iauc/08200/08217.html. Retrieved 2008-12-21.
14. ^ Hughes, D. W. (1994). "The Historical Unravelling of the Diameters of the First Four Asteroids". R.A.S. Quarterly Journal 35 (3): 334–344. http://articles.adsabs.harvard.edu//full/1994QJRAS..35..331H/0000334.000.html.
15. ^ Denning, W.F. (October 22, 1881). "The centenary of the discovery of Uranus". Scientific American Supplement (303). http://www.infomotions.com/etexts/gutenberg/dirs/etext05/7030310.htm.
16. ^ William Lassell (1852). "Beobachtungen der Uranus-Satelliten". Astronomische Nachrichten 34: 325. http://adsabs.harvard.edu//full/seri/AN.../0034//0000169.000.html. Retrieved 2008-12-18.
17. ^ Tyler, G.L.; Sweetnam, D.L.; Anderson, J.D. et al. (1989). "Voyager radio science observations of Neptune and Triton". Science 246 (4936): 1466–73. doi:10.1126/science.246.4936.1466. PMID 17756001. http://adsabs.harvard.edu/abs/1989Sci...246.1466T.
18. ^ a b c Thomas, P.C. (1988). "Radii, shapes, and topography of the satellites of Uranus from limb coordinates". Icarus 73: 427–441. doi:10.1016/0019-1035(88)90054-1. http://adsabs.harvard.edu/abs/1988Icar...73..427T. edit
19. ^ Esposito, L. W. (2002). "Planetary rings" (pdf). Reports On Progress In Physics 65: 1741–1783. doi:10.1088/0034-4885/65/12/201. http://www.iop.org/EJ/article/0034-4885/65/12/201/r21201.pdf. edit
20. ^ a b Karkoschka, Erich (2001). "Comprehensive Photometry of the Rings and 16 Satellites of Uranus with the Hubble Space Telescope". Icarus 151: 51–68. doi:10.1006/icar.2001.6596. http://adsabs.harvard.edu/abs/2001Icar..151...51K. edit
21. ^ Dumas, Christophe (2003). "Hubble Space Telescope NICMOS Multiband Photometry of Proteus and Puck". The Astronomical Journal 126: 1080–1085. doi:10.1086/375909. http://adsabs.harvard.edu/abs/2003AJ....126.1080D. edit
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External links

* Simulation Showing the location of Uranus' Moons
* "Uranus: Moons". NASA's Solar System Exploration. http://solarsystem.nasa.gov/planets/profile.cfm?Object=Uranus&Display=Moons. Retrieved 20 December 2008.
* "NASA's Hubble Discovers New Rings and Moons Around Uranus". Space Telescope Science Institute. 22 December 2005. http://hubblesite.org/newscenter/newsdesk/archive/releases/2005/33/. Retrieved 20 December 2008.
* Sheppard, Scott. "Uranus' Known Satellites". http://www.dtm.ciw.edu/users/sheppard/satellites/urasatdata.html.
* Gazeteer of Planetary Nomenclature - Uranus (USGS)