Moons of Uranus

Uranus, the seventh planet of the Solar System, has 27 known moons, all of which are named after characters from the works of William Shakespeare and Alexander Pope.[1] Uranus's 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 Uranus's rings. The five major moons are massive enough to have reached hydrostatic equilibrium, and four of them show signs of internally driven processes such as canyon formation and volcanism on their surfaces.[2] The largest of these five, Titania, is 1,578 km in diameter and the eighth-largest moon in the Solar System, and about one-twentieth the mass the Earth's Moon. The orbits of the regular moons are nearly coplanar with Uranus's equator, which is tilted 97.77° to its orbit. Uranus's irregular moons have elliptical and strongly inclined (mostly retrograde) orbits at large distances from the planet.[3]

William Herschel discovered the first two moons, Titania and Oberon, in 1787, and the other three ellipsoidal moons were discovered in 1851 by William Lassell (Ariel and Umbriel) and in 1948 by Gerard Kuiper (Miranda).[1] These five have planetary mass, and so would be considered (dwarf) planets if they were in direct orbit about the Sun. The remaining moons were discovered after 1985, either during the Voyager 2 flyby mission or with the aid of advanced Earth-based telescopes.[2][3]

Uranus moons
Uranus and its six largest moons compared at their proper relative sizes and relative positions. From left to right: Puck, Miranda, Ariel, Umbriel, Titania, and Oberon

Discovery

The first two moons to be discovered were Titania and Oberon, which 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.[2] Another satellite, Perdita, was discovered in 1999[10] after studying old Voyager photographs.[11]

Uranus was the last giant planet without any known irregular moons, but since 1997 nine distant irregular moons have been identified using ground-based telescopes.[3] Two more small inner moons, Cupid and Mab, were discovered using the Hubble Space Telescope in 2003.[12] As of 2016, the moon Margaret was the last Uranian moon discovered, and its characteristics were published in October 2003.[13]

Outer planet moons
The number of moons known for each of the four outer planets up to July 2018. Uranus currently has 27 known satellites.

Spurious moons

After Herschel discovered Titania and Oberon on January 11, 1787, he subsequently believed that he had 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 days, 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 faint stars in the vicinity of Uranus as satellites, and the credit for the discovery of Ariel and Umbriel was given to Lassell.[15]

Names

Although the first two Uranian moons were discovered in 1787, they were not named 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 sylph Ariel and gnome 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; 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]

Masses of Uranian moons-en
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.

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

Characteristics and groups

Uranian rings scheme
Schematic of the Uranian moon–ring system

The Uranian satellite system is the least massive among those of the giant planets. Indeed, the combined mass of the five major satellites is less than half that of Triton (the seventh-largest moon in the Solar System) alone.[a] 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 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.[b]

Inner moons

As of 2016, Uranus is known to have 13 inner moons.[12] Their orbits lie inside that of Miranda. All inner moons are intimately connected with 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) are shepherds of Uranus's ε ring, whereas the small moon Mab is a source of Uranus's outermost μ ring.[12] There may be two additional small (2–7 km in radius) undiscovered shepherd moons located about 100 km exterior to Uranus' α and β rings.[20]

At 162 km, Puck 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 two outermost inner satellites of Uranus. All inner moons are dark objects; their geometrical albedo is less than 10%.[21] They are composed of water ice contaminated with a dark material, probably radiation-processed organics.[22]

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.[23]

Uranian moon montage
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 these moons are relatively dark objects: their geometrical albedo varies between 30 and 50%, whereas their Bond albedo is between 10 and 23%.[21] Umbriel is the darkest moon and Ariel the brightest. The masses of the moons range from 6.7 × 1019 kg (Miranda) to 3.5 × 1021 kg (Titania). For comparison, the Moon has a mass of 7.5 × 1022 kg.[24] The major moons of Uranus are thought to have formed in the accretion disc, which existed around Uranus for some time after its formation or resulted from a large impact suffered by Uranus early in its history.[25][26]

Uranusmoonsummer
Artist's conception of the Sun's path in the summer sky of a major moon of Uranus (which shares Uranus's axial tilt)

All major moons comprise approximately equal amounts rock and ice, except Miranda, which is made primarily of ice.[27] The ice component may include ammonia and carbon dioxide.[28] 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.[2] Extensional processes associated with upwelling diapirs are likely responsible for the origin of the coronae.[29] Ariel appears to have the youngest surface with the fewest impact craters, while Umbriel's appears oldest.[2] 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.[30][31] 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.[32][33] The largest Uranian moons may be internally differentiated, with rocky cores at their centers surrounded by ice mantles.[27] Titania and Oberon may harbor liquid water oceans at the core/mantle boundary.[27] 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.[34]

The path of the Sun in the local sky over the course of a local day during Uranus's and its major moons' summer 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).[2] The Sun would appear to follow a circular path around Uranus's celestial pole in the sky, at the closest about 7 degrees from it.[c] 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 in diameter in the sky, and never set.

TheIrregulars URANUS
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

As of 2005 Uranus is known to have nine irregular moons, which orbit it 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.[3] 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 Uranian Hill sphere is approximately 73 million km.[3]

Uranus's irregular moons range in size from 120–200 km (Sycorax) to about 20 km (Trinculo).[3] Unlike Jupiter's irregulars, Uranus's show no correlation of axis with 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.[3] The outer group (a > 0.15 rH) includes satellites with high eccentricity (~0.5): Sycorax, Prospero, Setebos, and Ferdinand.[3]

The intermediate inclinations 60° < i < 140° are devoid of known moons due to the Kozai instability.[3] 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.[3]

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.[35]

List

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 retrograde orbits are shown in dark grey. Margaret, the only known irregular moon of Uranus with a prograde orbit, is shown in light grey.

Uranian moons
Order
[d]
Label
[e]
Name Pronunciation
(key)
Image Diameter
(km)[f]
Mass
(×1018 kg)[g]
Semi-major axis
(km)[37]
Orbital period
(d)[37][h]
Inclination
(°)[37][i]
Eccentricity
[38]
Discovery
year
[1]
Discoverer
[1]
1 VI ¡Cordelia /kɔːrˈdiːliə/ Cordeliamoon.png 40 ± 6
(50 × 36)
0.044 49770 0.335034 0.08479° 0.00026 1986 Terrile
(Voyager 2)
2 VII ¡Ophelia /oʊˈfiːliə/ Opheliamoon.png 43 ± 8
(54 × 38)
0.053 53790 0.376400 0.1036° 0.00992 1986 Terrile
(Voyager 2)
3 VIII ¡Bianca /biˈɑːŋkə/ Biancamoon.png 51 ± 4
(64 × 46)
0.092 59170 0.434579 0.193° 0.00092 1986 Smith
(Voyager 2)
4 IX ¡Cressida /ˈkrɛsɪdə/ Cressida.png 80 ± 4
(92 × 74)
0.34 61780 0.463570 0.006° 0.00036 1986 Synnott
(Voyager 2)
5 X ¡Desdemona /ˌdɛzdɪˈmoʊnə/ Desdemonamoon.png 64 ± 8
(90 × 54)
0.18 62680 0.473650 0.11125° 0.00013 1986 Synnott
(Voyager 2)
6 XI ¡Juliet /ˈdʒuːliət/ Julietmoon.png 94 ± 8
(150 × 74)
0.56 64350 0.493065 0.065° 0.00066 1986 Synnott
(Voyager 2)
7 XII ¡Portia /ˈpɔːrʃə/ Uranus-Portia-Cressida-Ophelia-NASA.gif 135 ± 8
(156 × 126)
1.70 66090 0.513196 0.059° 0.00005 1986 Synnott
(Voyager 2)
8 XIII ¡Rosalind /ˈrɒzəlɪnd/ Rosalindmoon.png 72 ± 12 0.25 69940 0.558460 0.279° 0.00011 1986 Synnott
(Voyager 2)
9 XXVII ¡Cupid /ˈkjuːpɪd/ Cupidmoon.png ≈ 18 0.0038 74800 0.618 0.1° 0.0013 2003 Showalter and
Lissauer
10 XIV ¡Belinda /bɪˈlɪndə/
Belinda.gif
90 ± 16
(128 × 64)
0.49 75260 0.623527 0.031° 0.00007 1986 Synnott
(Voyager 2)
11 XXV ¡Perdita /ˈpɜːrdɪtə/ Perditamoon.png 30 ± 6 0.018 76400 0.638 0.0° 0.0012 1999 Karkoschka
(Voyager 2)
12 XV ¡Puck /ˈpʌk/
Puck.png
162 ± 4 2.90 86010 0.761833 0.3192° 0.00012 1985 Synnott
(Voyager 2)
13 XXVI ¡Mab /ˈmæb/
Mabmoon.png
≈ 25 0.01 97700 0.923 0.1335° 0.0025 2003 Showalter and
Lissauer
14 V Miranda /mɪˈrændə/
PIA18185 Miranda's Icy Face.jpg
471.6 ± 1.4
(481 × 468 × 466)
65.9±7.5 129390 1.413479 4.232° 0.0013 1948 Kuiper
15 I Ariel /ˈɛəriəl/
Ariel (moon).jpg
1157.8±1.2
(1162 × 1156 × 1155)
1353±120 191020 2.520379 0.260° 0.0012 1851 Lassell
16 II Umbriel /ˈʌmbriəl/
PIA00040 Umbrielx2.47.jpg
1169.4±5.6 1172±135 266300 4.144177 0.205° 0.0039 1851 Lassell
17 III Titania /tɪˈteɪniə/
Titania (moon) color, edited.jpg
1576.8±1.2 3527±90 435910 8.705872 0.340° 0.0011 1787 Herschel
18 IV Oberon /ˈoʊbərɒn/
Voyager 2 picture of Oberon.jpg
1522.8±5.2 3014±75 583520 13.463239 0.058° 0.0014 1787 Herschel
19 XXII Francisco /frænˈsɪskoʊ/ Uranus moon 021002 02.jpg ≈ 22 0.0072 4276000 −266.56 147.459° 0.1459 2003[j] Holman et al.
20 XVI Caliban /ˈkælɪbæn/ Caliban feat.png ≈ 72 0.25 7230000 −579.50 139.885° 0.1587 1997 Gladman et al.
21 XX Stephano /ˈstɛfənoʊ/ Stephano - Uranus moon.jpg ≈ 32 0.022 8002000 −676.50 141.873° 0.2292 1999 Gladman et al.
22 XXI Trinculo /ˈtrɪŋkjʊloʊ/ ≈ 18 0.0039 8571000 −758.10 166.252° 0.2200 2001 Holman et al.
23 XVII Sycorax /ˈsɪkəræks/ Sycorax.jpg 165+36
−42
2.30 12179000 −1283.4 152.456° 0.5224 1997 Nicholson et al.
24 XXIII ±Margaret /ˈmɑːrɡərɪt/ ≈ 20 0.0054 14345000 1694.8 51.455° 0.6608 2003 Sheppard and
Jewitt
25 XVIII Prospero /ˈprɒspəroʊ/ Prospero discovery image.gif ≈ 50 0.085 16418000 −1992.8 146.017° 0.4448 1999 Holman et al.
26 XIX Setebos /ˈsɛtɪbʌs/ Uranus - Setebos image.jpg ≈ 48 0.075 17459000 −2202.3 145.883° 0.5914 1999 Kavelaars et al.
27 XXIV Ferdinand /ˈfɜːrdɪnænd/ Ferdinand - Uranus moon.gif ≈ 20 0.0054 20900000 −2823.4 167.346° 0.3682 2003[j] Holman et al.
Key
¡
Inner moons
 

Major moons
 

Irregular moons (retrograde)
±
Irregular moon (prograde)

Sources: NASA/NSSDC,[37] Sheppard, et al. 2005.[3] For the recently discovered outer irregular moons (Francisco through Ferdinand) the most accurate orbital data can be generated with the Natural Satellites Ephemeris Service.[35] The irregulars are significantly perturbed by the Sun.[3]

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°.[2]
  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.[1]
  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, 2009.[34] 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 except Sycorax were taken from Sheppard, 2005.[3] The diameter of Sycorax is from Lellouch, 2013.[36]
  7. ^ Masses of Miranda, Ariel, Umbriel, Titania, and Oberon were taken from Jacobson, 1992.[24] 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. ^ Inclination measures the angle between the moon's orbital plane and the plane defined by Uranus's equator.
  10. ^ a b Detected in 2001, published in 2003.

References

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External links

Belinda (moon)

Belinda ( bə-LIN-də) is an inner satellite of the planet Uranus. Belinda was discovered from the images taken by Voyager 2 on 13 January 1986 and was given the temporary designation S/1986 U 5. It is named after the heroine of Alexander Pope's The Rape of the Lock. It is also designated Uranus XIV.Belinda belongs to the Portia group of satellites, which also includes Bianca, Cressida, Desdemona, Portia, Juliet, Cupid, Rosalind and Perdita. These satellites have similar orbits and photometric properties. Other than its orbit, radius of 45 km and geometric albedo of 0.08 virtually nothing is known about it.

The Voyager 2 images show Belinda as an elongated object with its major axis pointing towards Uranus. The moon is very elongated, with its short axis 0.5 ± 0.1 times the long axis. Its surface is grey in color.

Bianca (moon)

There is also an asteroid called 218 Bianca.Bianca ( bee-AHNG-kə) is an inner satellite of Uranus. It was discovered from the images taken by Voyager 2 on January 23, 1986, and was given the temporary designation S/1986 U 9. It was named after the sister of Katherine in Shakespeare's play The Taming of the Shrew. It is also designated Uranus VIII.Bianca belongs to Portia Group of satellites, which also includes Cressida, Desdemona, Juliet, Portia, Rosalind, Cupid, Belinda and Perdita. These satellites have similar orbits and photometric properties. Other than its orbit, radius of 27 km, and geometric albedo of 0.08 virtually nothing is known about it.

At the Voyager 2 images Bianca appears as an elongated object, the major axis pointing towards Uranus. The ratio of axes of the Bianca's prolate spheroid is 0.7 ± 0.2. Its surface is grey in color.

Caliban (moon)

Caliban ( KAL-i-ban or KAL-i-bən) is the second-largest retrograde irregular satellite of Uranus. It was discovered on 6 September 1997 by Brett J. Gladman, Philip D. Nicholson, Joseph A. Burns, and John J. Kavelaars using the 200-inch Hale telescope together with Sycorax and given the temporary designation S/1997 U 1.Designated Uranus XVI, it was named after the monster character in William Shakespeare's play The Tempest.

Cordelia (moon)

Cordelia ( kor-DEE-lee-ə) is the innermost known moon of Uranus. It was discovered from the images taken by Voyager 2 on January 20, 1986, and was given the temporary designation S/1986 U 7. It was not detected again until the Hubble Space Telescope observed it in 1997. Cordelia takes its name from the youngest daughter of Lear in William Shakespeare's King Lear. It is also designated Uranus VI.Other than its orbit, radius of 20 km and geometric albedo of 0.08 virtually nothing is known about it. In the Voyager 2 images Cordelia appears as an elongated object with its major axis pointing towards Uranus. The ratio of axes of Cordelia's prolate spheroid is 0.7 ± 0.2.Cordelia acts as the inner shepherd satellite for Uranus' ε ring. Cordelia's orbit is within Uranus' synchronous orbit radius, and is therefore slowly decaying due to tidal deceleration.Cordelia is very close to a 5:3 orbital resonance with Rosalind.

Cupid (moon)

Cupid ( KEW-pid) is an inner satellite of Uranus. It was discovered by Mark R. Showalter and Jack J. Lissauer in 2003 using the Hubble Space Telescope. It was named after a character in William Shakespeare's play Timon of Athens.It is the smallest of inner Uranian satellites, crudely estimated to be only about 18 km in diameter. This and the dark surface made it too dim to be detected by the Voyager 2 cameras during its Uranus flyby in 1986.

The orbit of Cupid differs only by 863 km from the orbit of the larger moon Belinda. Unlike Mab and Perdita, Uranian satellites also discovered in 2003, it does not seem to be perturbed.Following its discovery, Cupid was given the temporary designation S/2003 U 2. It is also designated Uranus XXVII.It should not be confused with the asteroid 763 Cupido.

Desdemona (moon)

There is also a minor planet called 666 Desdemona.Desdemona ( DEZ-di-MOH-nə) is an inner satellite of Uranus. It was discovered from the images taken by Voyager 2 on 13 January 1986, and was given the temporary designation S/1986 U 6. Desdemona is named after the wife of Othello in William Shakespeare's play Othello. It is also designated Uranus X.Desdemona belongs to Portia Group of satellites, which also includes Bianca, Cressida, Juliet, Portia, Rosalind, Cupid, Belinda and Perdita. These satellites have similar orbits and photometric properties. Other than its orbit, radius of 32 km and geometric albedo of 0.08 virtually nothing is known about Desdemona.

At the Voyager 2 images Desdemona appears as an elongated object, the major axis pointing towards Uranus. The ratio of axes of Desdemona's prolate spheroid is 0.6 ± 0.3. Its surface is grey in color.Desdemona may collide with one of its neighboring moons Cressida or Juliet within the next 100 million years.

Ferdinand (moon)

Ferdinand is the outermost retrograde irregular satellite of Uranus. It was first seen near Uranus by Matthew J. Holman, John J. Kavelaars, Dan Milisavljevic, and Brett J. Gladman on August 13, 2001 and reobserved on September 21, 2001. The object was then lost with no confirmation it was actually orbiting around Uranus. On August 29 and 30, 2003 a team led by Scott S. Sheppard surveyed the sky around Uranus with the Subaru telescope and detected two unknown objects near Uranus. These two new objects were reobserved by Sheppard et al. with the Gemini telescope on September 20, 2003 and reported to the minor planet center as possible new moons of Uranus. On September 24, 2003, Brian Marsden, at the minor planet center, linked one of the unknown objects reported by Sheppard et al. to the lost object observed by Holman et al. in 2001. Holman was then able to confirm the linkage between the 2001 and 2003 objects on September 30, 2003 by observing its location with the Magellan telescope. The linked 2001 and 2003 object was then given the provisional designation S/2001 U 2 on October 1, 2003, officially identifying it as a new moon of Uranus. Now designated Uranus XXIV, Ferdinand is named after the son of the King of Naples in William Shakespeare's play The Tempest.

The second new object observed by Sheppard et al. in 2003 was also a new moon of Uranus, now named Margaret.

Francisco (moon)

Francisco ( fran-SIS-koh) is the innermost irregular satellite of Uranus.

Francisco was discovered by Matthew J. Holman, et al. and Brett J. Gladman, et al. in 2003 from pictures taken in 2001 and given the provisional designation S/2001 U 3.

Confirmed as Uranus XXII, it was named after a lord in William Shakespeare's play The Tempest.

Juliet (moon)

There is also an asteroid called 1285 Julietta.Juliet ( JOO-lee-ət, JOO-lee-ET) is an inner satellite of Uranus. It was discovered from the images taken by Voyager 2 on 3 January 1986, and was given the temporary designation S/1986 U 2. It is named after the heroine of William Shakespeare's play Romeo and Juliet. It is also designated Uranus XI.Juliet belongs to Portia Group of satellites, which also includes Bianca, Cressida, Desdemona, Portia, Rosalind, Cupid, Belinda and Perdita. These satellites have similar orbits and photometric properties. Unfortunately, other than its orbit, radius of 53 km and geometric albedo of 0.08 virtually nothing is known about Juliet.

At the Voyager 2 images Juliet appears as an elongated object, the major axis pointing towards Uranus. The ratio of axes of Juliet's prolate spheroid is 0.5 ± 0.3, which is rather an extreme value. Its surface is grey in color.Juliet may collide with Desdemona within the next 100 million years.

List of geological features on Oberon

This is a list of named geological features (mostly craters) on Oberon.

List of geological features on Puck

This is a list of named craters on Puck. Puckian craters are named after mischievous spirits in European mythology.

List of geological features on Titania

This is a list of named geological features on Titania.

Margaret (moon)

Margaret ( MAR-grit) is the only prograde irregular satellite of Uranus. It was discovered by Scott S. Sheppard, et al. in 2003 and given the provisional designation S/2003 U 3.Confirmed as Uranus XXIII, it was named after the servant of Hero in William Shakespeare's play Much Ado About Nothing.

Ophelia (moon)

Ophelia ( o-FEE-lee-ə) is a moon of Uranus. It was discovered from the images taken by Voyager 2 on January 20, 1986, and was given the temporary designation S/1986 U 8. It was not seen until the Hubble Space Telescope recovered it in 2003. Ophelia was named after the daughter of Polonius, Ophelia, in William Shakespeare's play Hamlet. It is also designated Uranus VII.Other than its orbit, radius of 21 km and geometric albedo of 0.08 virtually nothing is known about it. At the Voyager 2 images Ophelia appears as an elongated object, the major axis pointing towards Uranus. The ratio of axes of the Ophelia's prolate spheroid is 0.7 ± 0.3.Ophelia acts as the outer shepherd satellite for Uranus' ε ring. The orbit of Ophelia is within the synchronous orbit radius of Uranus, and is therefore slowly decaying due to tidal forces.

Outline of Uranus

The following outline is provided as an overview of and topical guide to Uranus:

Uranus – seventh planet from the Sun. It has the third-largest planetary radius and fourth-largest planetary mass in the Solar System. Uranus is similar in composition to Neptune, and both have different bulk chemical composition from that of the larger gas giants Jupiter and Saturn. For this reason, scientists often classify Uranus and Neptune as "ice giants" to distinguish them from the gas giants. Uranus's atmosphere is similar to Jupiter's and Saturn's in its primary composition of hydrogen and helium, but it contains more "ices" such as water, ammonia, and methane, along with traces of other hydrocarbons. It is the coldest planetary atmosphere in the Solar System, with a minimum temperature of 49 K (−224.2 °C), and has a complex, layered cloud structure with water thought to make up the lowest clouds and methane the uppermost layer of clouds. The interior of Uranus is mainly composed of ice and rock.

Prospero (moon)

Prospero ( PROS-pər-oh) is a relatively small retrograde irregular satellite of Uranus discovered on 18 July 1999 by the astrophysicist Matthew Holman and his team, and given the provisional designation S/1999 U 3. Confirmed as Uranus XVIII it was named after the sorcerer Prospero in William Shakespeare's play The Tempest.

The orbital parameters suggest that it may belong to the same dynamic cluster as Sycorax and Setebos, suggesting common origin. However, this suggestion does not appear to be supported by the observed colours. The satellite appears neutral (grey) in visible light (colour indices B-V=0.80, R-V=0.39), similar to Setebos but different from Sycorax (which is light red).

Rosalind (moon)

There is also an asteroid called 900 Rosalinde.Rosalind ( ROZ-əl-ind) is an inner satellite of Uranus. It was discovered from the images taken by Voyager 2 on 13 January 1986, and was given the temporary designation S/1986 U 4. It was named after the daughter of the banished Duke in William Shakespeare's play As You Like It. It is also designated Uranus XIII.Rosalind belongs to Portia group of satellites, which also includes Bianca, Cressida, Desdemona, Portia, Juliet, Cupid, Belinda and Perdita. These satellites have similar orbits and photometric properties. Other than its orbit, radius of 36 km and geometric albedo of 0.08 virtually nothing is known about Rosalind.

In the Voyager 2 images Rosalind appears as an almost spherical object. The ratio of axes of Rosalind's prolate spheroid is 0.8-1.0. Its surface is grey in color.Rosalind is very close to a 3:5 orbital resonance with Cordelia.

Stephano (moon)

Stephano ( STEF-ə-noh or stə-FAH-noh) is a retrograde irregular satellite of Uranus. It was discovered by Brett J. Gladman, et al. in 1999, and given the provisional designation S/1999 U 2.Confirmed as Uranus XX, it was named after the drunken butler in William Shakespeare's play The Tempest in August 2000.The orbital parameters suggest that it may belong to the same dynamic cluster as Caliban, suggesting common origin.

Trinculo (moon)

Trinculo ( TRING-kew-loh) is a retrograde irregular satellite of Uranus. It was discovered by a group of astronomers led by Holman, et al. on 13 August 2001, and given the temporary designation S/2001 U 1.Confirmed as Uranus XXI, it was named after the drunken jester Trinculo in William Shakespeare's play The Tempest.

Moons of Uranus
Inner
Major (spheroid)
Outer (irregular)
Geological features
Geography
Moons
Astronomy
Exploration
Related
Planetary
satellites
Dwarf-planet
satellites
Minor-planet moons
Ranked by size

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