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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

1. ^ a b c d e f g h i j k l m n Sheppard, Scott S.; Jewitt, David and Kleyna, Jan (2005). "An ultradeep survey for irregular satellites of Uranus: Limits to completeness". The Astronomical Journal 129: 518–525. doi:10.1086/426329. http://adsabs.harvard.edu/abs/2005AJ....129..518S. edit
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.
3. ^ a b c d e f g Smith, B.A.; Soderblom, L.A.; Beebe, A. et al. (1986). "Voyager 2 in the Uranian System: Imaging Science Results". Science 233: 97–102. doi:10.1126/science.233.4759.43. PMID 17812889. http://adsabs.harvard.edu/abs/1986Sci...233...43S. edit
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.
7. ^ Lassell, W. (1851). "Letter from William Lassell, Esq., to the Editor". Astronomical Journal 2 (33): 70. doi:10.1086/100198. http://adsabs.harvard.edu/abs/1851AJ......2...70L. edit
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
22. ^ Duncan, Martin J.; Jack J. Lissauer (1997). "Orbital Stability of the Uranian Satellite System". Icarus 125 (1): 1–12. doi:10.1006/icar.1996.5568. http://adsabs.harvard.edu/abs/1997Icar..125....1D. Retrieved 2008-05-10.
23. ^ a b Jacobson, R.A.; Campbell, J.K.; Taylor, A.H. and Synnott, S.P. (1992). "The masses of Uranus and its major satellites from Voyager tracking data and Earth based Uranian satellite data". The Astronomical Journal 103 (6): 2068–78. doi:10.1086/116211. http://adsabs.harvard.edu/abs/1992AJ....103.2068J. 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)

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