Uranus' natural satellites - AbsoluteAstronomy.com

Uranus is the seventh planet from the Sun. It has the third-largest planetary radius and fourth-largest planetary mass in the Solar System. It is named after the ancient Greek deity of the sky Uranus , the father of Cronus and grandfather of Zeus...

, the seventh planet of the Solar System

Solar System

The Solar System consists of the Sun and the astronomical objects gravitationally bound in orbit around it, all of which formed from the collapse of a giant molecular cloud approximately 4.6 billion years ago. The vast majority of the system's mass is in the Sun...

, has 27 known moons

Natural satellite

A natural satellite or moon is a celestial body that orbits a planet or smaller body, which is called its primary. The two terms are used synonymously for non-artificial satellites of planets, of dwarf planets, and of minor planets....

, all of which are named after characters from the works of William Shakespeare

William Shakespeare

William Shakespeare was an English poet and playwright, widely regarded as the greatest writer in the English language and the world's pre-eminent dramatist. He is often called England's national poet and the "Bard of Avon"...

and Alexander Pope

Alexander Pope

Alexander Pope was an 18th-century English poet, best known for his satirical verse and for his translation of Homer. He is the third-most frequently quoted writer in The Oxford Dictionary of Quotations, after Shakespeare and Tennyson...

. William Herschel

William Herschel

Sir Frederick William Herschel, KH, FRS, German: Friedrich Wilhelm Herschel was a German-born British astronomer, technical expert, and composer. Born in Hanover, Wilhelm first followed his father into the Military Band of Hanover, but emigrated to Britain at age 19...

discovered the first two moons, Titania

Titania (moon)

Titania is the largest of the moons of Uranus and the eighth largest moon in the Solar System at a diameter of 1578 km. Discovered by William Herschel in 1787, Titania is named after the queen of the fairies in Shakespeare's A Midsummer Night's Dream...

and Oberon

Oberon (moon)

Oberon , also designated ', is the outermost major moon of the planet Uranus. It is the second largest and second most massive of the Uranian moons, and the ninth most massive moon in the Solar System. Discovered by William Herschel in 1787, Oberon is named after the mythical king of the fairies...

, in 1787, and the other spherical

Hydrostatic equilibrium

Hydrostatic equilibrium or hydrostatic balance is the condition in fluid mechanics where a volume of a fluid is at rest or at constant velocity. This occurs when compression due to gravity is balanced by a pressure gradient force...

moons were discovered in 1851 by William Lassell

William Lassell

William Lassell FRS was an English merchant and astronomer.Born in Bolton and educated in Rochdale after the death of his father, he was apprenticed from 1814 to 1821 to a merchant in Liverpool. He then made his fortune as a beer brewer, which enabled him to indulge his interest in astronomy...

(Ariel

Ariel (moon)

Ariel is the brightest and fourth-largest of the 27 known moons of Uranus. Ariel orbits and rotates in the equatorial plane of Uranus, which is almost perpendicular to the orbit of Uranus, and so has an extreme seasonal cycle....

and Umbriel

Umbriel (moon)

Umbriel is a moon of Uranus discovered on October 24, 1851, by William Lassell. It was discovered at the same time as Ariel and named after a character in Alexander Pope's poem The Rape of the Lock. Umbriel consists mainly of ice with a substantial fraction of rock, and may be differentiated into a...

) and in 1948 by Gerard Kuiper

Gerard Kuiper

Gerard Peter Kuiper , Netherlands – December 24, 1973, Mexico City) was a Dutch-American astronomer after whom the Kuiper belt was named.-Early life:...

(Miranda

Miranda (moon)

-External links:* at * at The Nine8 Planets* at Views of the Solar System* * from the...

). The remaining moons were discovered after 1985, either during the Voyager 2
Voyager 2
The Voyager 2 spacecraft is a 722-kilogram space probe launched by NASA on August 20, 1977 to study the outer Solar System and eventually interstellar space...

flyby mission or with the aid of advanced Earth

Earth

Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...

-based telescopes.

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

Rings of Uranus

The planet Uranus has a system of rings intermediate in complexity between the more extensive set around Saturn and the simpler systems around Jupiter and Neptune. The rings of Uranus were discovered on March 10, 1977, by James L. Elliot, Edward W. Dunham, and Douglas J. Mink...

. The five major moons are massive enough to have achieved hydrostatic equilibrium

Hydrostatic equilibrium

, and four of them show signs of internally driven processes such as canyon formation and volcanism on their surfaces. The largest of these five, Titania

Titania (moon)

, 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

Moon

The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...

. Uranus's irregular moons have elliptical and strongly inclined (mostly retrograde

Retrograde and direct motion

Apparent retrograde motion is the motion of a planetary body in a direction opposite to that of other bodies within its system as observed from a particular vantage point...

) orbits at great distances from the planet.

Discovery

The first two moons to be discovered, Titania

Titania (moon)

and Oberon

Oberon (moon)

, were spotted by Sir William Herschel

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. 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

Ariel (moon)

and Umbriel

Umbriel (moon)

, were discovered by William Lassell

William Lassell

in 1851. 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). With the confirmation of Ariel and Umbriel, Lassell numbered the moons I through IV from Uranus outward, and this finally stuck. In 1852, Herschel's son John Herschel

John Herschel

Sir John Frederick William Herschel, 1st Baronet KH, FRS ,was an English mathematician, astronomer, chemist, and experimental photographer/inventor, who in some years also did valuable botanical work...

gave the four then-known moons their names.

No other discoveries were made for almost another century. In 1948, Gerard Kuiper

Gerard Kuiper

Gerard Peter Kuiper , Netherlands – December 24, 1973, Mexico City) was a Dutch-American astronomer after whom the Kuiper belt was named.-Early life:...

at the McDonald Observatory

McDonald Observatory

The McDonald Observatory is an astronomical observatory located near the unincorporated community of Fort Davis in Jeff Davis County, Texas, United States. The facility is located on Mount Fowlkes and Mount Locke in the Davis Mountains of West Texas...

discovered the smallest and the last of the five large, spherical moons, Miranda

Miranda (moon)

-External links:* at * at The Nine8 Planets* at Views of the Solar System* * from the...

. Decades later, the flyby of the Voyager 2
Voyager 2
The Voyager 2 spacecraft is a 722-kilogram space probe launched by NASA on August 20, 1977 to study the outer Solar System and eventually interstellar space...

space probe in January 1986 led to the discovery of ten further inner moons. Another satellite, Perdita

Perdita (moon)

Perdita is an inner satellite of Uranus. Perdita's discovery was complicated. The first photographs of Perdita were taken by the Voyager 2 spacecraft in 1986, but it was not recognized from the photographs for more than a decade. In 1999, the moon was noticed by Erich Karkoschka and reported...

, was retroactively discovered in 1999 after studying old Voyager photographs.

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. Two more small inner moons, Cupid

Cupid (moon)

Cupid is an inner satellite of Uranus. It was discovered by Mark 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....

and Mab

Mab (moon)

Mab , or Uranus XXVI , is an inner satellite of Uranus. It was discovered by Mark R. Showalter and Jack J. Lissauer in 2003 using the Hubble Space Telescope...

, were discovered using the Hubble Space Telescope

Hubble Space Telescope

The Hubble Space Telescope is a space telescope that was carried into orbit by a Space Shuttle in 1990 and remains in operation. A 2.4 meter aperture telescope in low Earth orbit, Hubble's four main instruments observe in the near ultraviolet, visible, and near infrared...

in 2003. The moon Margaret

Margaret (moon)

Margaret 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....

was the last Uranian moon discovered as of 2008, and its findings were published in October 2003.

Spurious moons

After Herschel discovered Titania

Titania (moon)

and Oberon

Oberon (moon)

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

William Lassell

's observations of 1851, in which he discovered Ariel

Ariel (moon)

and Umbriel

Umbriel (moon)

, 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). 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.

Names

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

John Herschel

, son of the discoverer of Uranus. Herschel, instead of assigning names from Greek mythology

Greek mythology

Greek mythology is the body of myths and legends belonging to the ancient Greeks, concerning their gods and heroes, the nature of the world, and the origins and significance of their own cult and ritual practices. They were a part of religion in ancient Greece...

, named the moons after magical spirits in English literature

English literature

English literature is the literature written in the English language, including literature composed in English by writers not necessarily from England; for example, Robert Burns was Scottish, James Joyce was Irish, Joseph Conrad was Polish, Dylan Thomas was Welsh, Edgar Allan Poe was American, J....

: the fairies Oberon and Titania from William Shakespeare

William Shakespeare

's A Midsummer Night's Dream
A Midsummer Night's Dream
A Midsummer Night's Dream is a play that was written by William Shakespeare. It is believed to have been written between 1590 and 1596. It portrays the events surrounding the marriage of the Duke of Athens, Theseus, and the Queen of the Amazons, Hippolyta...

, and the sylphs Ariel and Umbriel from Alexander Pope

Alexander Pope

's The Rape of the Lock
The Rape of the Lock
The Rape of the Lock is a mock-heroic narrative poem written by Alexander Pope, first published anonymously in Lintot's Miscellany in May 1712 in two cantos , but then revised, expanded and reissued under Pope's name on March 2, 1714, in a much-expanded 5-canto version...

(Ariel is also a sprite in Shakespeare's The Tempest
The Tempest
The Tempest is a play by William Shakespeare, believed to have been written in 1610–11, and thought by many critics to be the last play that Shakespeare wrote alone. It is set on a remote island, where Prospero, the exiled Duke of Milan, plots to restore his daughter Miranda to her rightful place,...

). The reasoning was presumably that Uranus, as god of the sky and air, would be attended by spirits of the air.

Subsequent names, rather than continuing the airy spirits theme (only Puck

Puck (moon)

Puck is an inner moon of Uranus. It was discovered in December 1985 by the Voyager 2 spacecraft. The name Puck comes from Celtic mythology and English folklore. The orbit of Puck lies between the rings of Uranus and the first of Uranus' large moons, Miranda. Puck is approximately spherical in...

and Mab

Mab (moon)

Mab , or Uranus XXVI , is an inner satellite of Uranus. It was discovered by Mark R. Showalter and Jack J. Lissauer in 2003 using the Hubble Space Telescope...

continued the trend), have focused on Herschel's source material. In 1949, the fifth moon, Miranda

Miranda (moon)

-External links:* at * at The Nine8 Planets* at Views of the Solar System* * from the...

, was named by its discoverer Gerard Kuiper

Gerard Kuiper

Gerard Peter Kuiper , Netherlands – December 24, 1973, Mexico City) was a Dutch-American astronomer after whom the Kuiper belt was named.-Early life:...

after a thoroughly mortal character in Shakespeare's The Tempest. The current IAU

International Astronomical Union

The International Astronomical Union IAU is a collection of professional astronomers, at the Ph.D. level and beyond, active in professional research and education in astronomy...

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

Margaret (moon)

Margaret 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....

being named from Much Ado About Nothing
Much Ado About Nothing
Much Ado About Nothing is a comedy written by William Shakespeare about two pairs of lovers, Benedick and Beatrice, and Claudio and Hero....

that trend has ended.

The Rape of the Lock
The Rape of the Lock
The Rape of the Lock is a mock-heroic narrative poem written by Alexander Pope, first published anonymously in Lintot's Miscellany in May 1712 in two cantos , but then revised, expanded and reissued under Pope's name on March 2, 1714, in a much-expanded 5-canto version...

(a poem by Alexander Pope
Alexander Pope
Alexander Pope was an 18th-century English poet, best known for his satirical verse and for his translation of Homer. He is the third-most frequently quoted writer in The Oxford Dictionary of Quotations, after Shakespeare and Tennyson...

):
- Ariel, Umbriel, Belinda
Plays by William Shakespeare
William Shakespeare
William Shakespeare was an English poet and playwright, widely regarded as the greatest writer in the English language and the world's pre-eminent dramatist. He is often called England's national poet and the "Bard of Avon"...

:
- A Midsummer Night's Dream
  A Midsummer Night's Dream
  A Midsummer Night's Dream is a play that was written by William Shakespeare. It is believed to have been written between 1590 and 1596. It portrays the events surrounding the marriage of the Duke of Athens, Theseus, and the Queen of the Amazons, Hippolyta...
  
  : Titania, Oberon, Puck
- The Tempest
  The Tempest
  The Tempest is a play by William Shakespeare, believed to have been written in 1610–11, and thought by many critics to be the last play that Shakespeare wrote alone. It is set on a remote island, where Prospero, the exiled Duke of Milan, plots to restore his daughter Miranda to her rightful place,...
  
  : (Ariel), Miranda, Caliban, Sycorax, Prospero, Setebos, Stephano, Trinculo, Francisco, Ferdinand
- King Lear
  King Lear
  King Lear is a tragedy by William Shakespeare. The title character descends into madness after foolishly disposing of his estate between two of his three daughters based on their flattery, bringing tragic consequences for all. The play is based on the legend of Leir of Britain, a mythological...
  
  : Cordelia
- Hamlet
  Hamlet
  The Tragical History of Hamlet, Prince of Denmark, or more simply Hamlet, is a tragedy by William Shakespeare, believed to have been written between 1599 and 1601...
  
  : Ophelia
- The Taming of the Shrew
  The Taming of the Shrew
  The Taming of the Shrew is a comedy by William Shakespeare, believed to have been written between 1590 and 1591.The play begins with a framing device, often referred to as the Induction, in which a mischievous nobleman tricks a drunken tinker named Sly into believing he is actually a nobleman himself...
  
  : Bianca
- Troilus and Cressida
  Troilus and Cressida
  Troilus and Cressida is a tragedy by William Shakespeare, believed to have been written in 1602. It was also described by Frederick S. Boas as one of Shakespeare's problem plays. The play ends on a very bleak note with the death of the noble Trojan Hector and destruction of the love between Troilus...
  
  : Cressida
- Othello
  Othello
  The Tragedy of Othello, the Moor of Venice is a tragedy by William Shakespeare, believed to have been written in approximately 1603, and based on the Italian short story "Un Capitano Moro" by Cinthio, a disciple of Boccaccio, first published in 1565...
  
  : Desdemona
- Romeo and Juliet
  Romeo and Juliet
  Romeo and Juliet is a tragedy written early in the career of playwright William Shakespeare about two young star-crossed lovers whose deaths ultimately unite their feuding families. It was among Shakespeare's most popular archetypal stories of young, teenage lovers.Romeo and Juliet belongs to a...
  
  : Juliet, Mab
- The Merchant of Venice
  The Merchant of Venice
  The Merchant of Venice is a tragic comedy by William Shakespeare, believed to have been written between 1596 and 1598. Though classified as a comedy in the First Folio and sharing certain aspects with Shakespeare's other romantic comedies, the play is perhaps most remembered for its dramatic...
  
  : Portia
- As You Like It
  As You Like It
  As You Like It is a pastoral comedy by William Shakespeare believed to have been written in 1599 or early 1600 and first published in the folio of 1623. The play's first performance is uncertain, though a performance at Wilton House in 1603 has been suggested as a possibility...
  
  : Rosalind
- Much Ado About Nothing
  Much Ado About Nothing
  Much Ado About Nothing is a comedy written by William Shakespeare about two pairs of lovers, Benedick and Beatrice, and Claudio and Hero....
  
  : Margaret
- The Winter's Tale
  The Winter's Tale
  The Winter's Tale is a play by William Shakespeare, originally published in the First Folio of 1623. Although it was grouped among the comedies, some modern editors have relabelled the play as one of Shakespeare's late romances. Some critics, among them W. W...
  
  : Perdita
- Timon of Athens
  Timon of Athens
  The Life of Timon of Athens is a play by William Shakespeare about the fortunes of an Athenian named Timon , generally regarded as one of his most obscure and difficult works...
  
  : Cupid

Some asteroid

Asteroid

Asteroids are a class of small Solar System bodies in orbit around the Sun. They have also been called planetoids, especially the larger ones...

s share names with moons of Uranus: 171 Ophelia

171 Ophelia

171 Ophelia is a large, dark Themistian asteroid. It probably has a primitive composition, similar to that of the carbonaceous chondrite meteorites....

, 218 Bianca

218 Bianca

218 Bianca is a sizeable Main belt asteroid. It is an S-type asteroid.It was discovered by Johann Palisa on September 4, 1880, in Pola and was named after the Austro-Hungarian opera singer Bianca Bianchi...

, 593 Titania

593 Titania

593 Titania is a minor planet orbiting the Sun.Not to be confused with Titania the largest moon of Uranus.-External links:*...

, 666 Desdemona

666 Desdemona

666 Desdemona is a minor planet orbiting the Sun.It may often be confused with Desdemona, a moon of the planet Uranus.-External links:*...

, 763 Cupido

763 Cupido

-External links:*...

and 2758 Cordelia

2758 Cordelia

2758 Cordelia is a main-belt asteroid discovered on 1 September 1978 by Chernykh, N. at Nauchnyj.- External links :*...

Characteristics and groups

The Uranian satellite system is the least massive among those of the gas giant

Gas giant

A gas giant is a large planet that is not primarily composed of rock or other solid matter. There are four gas giants in the Solar System: Jupiter, Saturn, Uranus, and Neptune...

s; indeed, the combined mass of the five major satellites would be less than half that of Triton

Triton (moon)

Triton is the largest moon of the planet Neptune, discovered on October 10, 1846, by English astronomer William Lassell. It is the only large moon in the Solar System with a retrograde orbit, which is an orbit in the opposite direction to its planet's rotation. At 2,700 km in diameter, it is...

(the seventh-largest moon in the Solar System) alone. The largest of the satellites, Titania, has a radius of 788.9 km, or less than half that of the Earth's Moon

Moon

, but slightly more than that of Rhea

Rhea (moon)

Rhea is the second-largest moon of Saturn and the ninth largest moon in the Solar System. It was discovered in 1672 by Giovanni Domenico Cassini.-Name:Rhea is named after the Titan Rhea of Greek mythology, "mother of the gods"...

, the second largest moon of Saturn

Saturn

Saturn is the sixth planet from the Sun and the second largest planet in the Solar System, after Jupiter. Saturn is named after the Roman god Saturn, equated to the Greek Cronus , the Babylonian Ninurta and the Hindu Shani. Saturn's astronomical symbol represents the Roman god's sickle.Saturn,...

, making Titania the eighth-largest moon in the Solar System

Solar System

. Uranus is about 10,000 times more massive than its moons.

Inner moons

As of 2008, Uranus is known to possess 13 inner moons. Their orbits lie inside that of Miranda

Miranda (moon)

-External links:* at * at The Nine8 Planets* at Views of the Solar System* * from the...

. All inner moons are intimately connected to the rings of Uranus

Rings of Uranus

, which probably resulted from the fragmentation of one or several small inner moons. The two innermost moons (Cordelia

Cordelia (moon)

Cordelia is the innermost 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...

and Ophelia

Ophelia (moon)

Ophelia 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...

) serve as shepherds of Uranus's ε ring, while small moon Mab

Mab (moon)

Mab , or Uranus XXVI , is an inner satellite of Uranus. It was discovered by Mark R. Showalter and Jack J. Lissauer in 2003 using the Hubble Space Telescope...

is a source of Uranus's outermost μ ring.

Puck

Puck (moon)

, 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

Albedo

Albedo , or reflection coefficient, is the diffuse reflectivity or reflecting power of a surface. It is defined as the ratio of reflected radiation from the surface to incident radiation upon it...

does not exceed 10%. They are made of water ice contaminated with a dark material—probably radiation processed organics.

The small inner moons constantly perturb

Perturbation (astronomy)

Perturbation is a term used in astronomy in connection with descriptions of the complex motion of a massive body which is subject to appreciable gravitational effects from more than one other massive body....

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. Desdemona

Desdemona (moon)

Desdemona 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...

may collide with either Cressida

Cressida (moon)

Cressida is an inner satellite of Uranus. It was discovered from the images taken by Voyager 2 on 9 January 1986, and was given the temporary designation S/1986 U 3. It was named after the Trojan daughter of Calchas, a tragic heroine who appears in William Shakespeare's play Troilus and...

or Juliet

Juliet (moon)

Juliet 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...

within the next 100 million years.

Large moons

Uranus has five major moons: Miranda

Miranda (moon)

-External links:* at * at The Nine8 Planets* at Views of the Solar System* * from the...

, Ariel

Ariel (moon)

, Umbriel

Umbriel (moon)

, Titania

Titania (moon)

and Oberon

Oberon (moon)

. They range in diameter from 472 km for Miranda to 1578 km for Titania. 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%. Umbriel is the darkest moon and Ariel is the brightest. The masses of the moons range from 6.7 kg (Miranda) to 3.5 kg (Titania)—for comparison, Earth's Moon

Moon

has mass of 7.5 kg. The major moons of Uranus are believed to have formed in the accretion disc

Accretion disc

An accretion disc is a structure formed by diffuse material in orbital motion around a central body. The central body is typically a star. Gravity causes material in the disc to spiral inward towards the central body. Gravitational forces compress the material causing the emission of...

, which existed around Uranus for some time after its formation or resulted from the large impact suffered by Uranus

Uranus

early in its history.

All major moons comprise approximately equal amounts rock and ice, except Miranda, which is made primarily of ice. The ice component may include ammonia

Ammonia

Ammonia is a compound of nitrogen and hydrogen with the formula . It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or...

and carbon dioxide

Carbon dioxide

Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...

. 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

Corona (planetary geology)

In planetary geology, a corona is an oval-shaped feature. Coronae appear on both the planet Venus and Uranus's moon Miranda and may be formed by upwellings of warm material below the surface.-Coronae on Venus:...

. Extensional processes associated with upwelling diapir

Diapir

A diapir is a type of intrusion in which a more mobile and ductily-deformable material is forced into brittle overlying rocks. Depending on the tectonic environment, diapirs can range from idealized mushroom-shaped Rayleigh-Taylor instability-type structures in regions with low tectonic stress...

s are likely responsible for the origin of the coronae. Ariel appears to have the youngest surface with the fewest impact craters, while Umbriel's appears oldest. A past 3:1 orbital resonance

Orbital resonance

In celestial mechanics, an orbital resonance occurs when two orbiting bodies exert a regular, periodic gravitational influence on each other, usually due to their orbital periods being related by a ratio of two small integers. Orbital resonances greatly enhance the mutual gravitational influence of...

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.
One piece of evidence for such a past resonance is Miranda's unusually high orbital inclination

Inclination

Inclination in general is the angle between a reference plane and another plane or axis of direction.-Orbits:The inclination is one of the six orbital parameters describing the shape and orientation of a celestial orbit...

(4.34°) for a body so close to the planet. The largest Uranian moons may be internally differentiated, with rocky cores at their centers surrounded by ice mantle

Mantle (geology)

The mantle is a part of a terrestrial planet or other rocky body large enough to have differentiation by density. The interior of the Earth, similar to the other terrestrial planets, is chemically divided into layers. The mantle is a highly viscous layer between the crust and the outer core....

s. Titania and Oberon may harbor liquid water oceans at the core/mantle boundary. 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.

The path of the Sun in the local sky over the course of a local day during Uranus' and its major moons' summer solstice is quite different from that seen on most other Solar System

Solar System

worlds. The major moons have almost exactly the same rotational axial tilt as Uranus' (their axes are parallel to that of Uranus). 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. 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

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. The diagram illustrates the orbits of those irregular moons discovered so far. The moons above the X axis are prograde

Retrograde and direct motion

Apparent retrograde motion is the motion of a planetary body in a direction opposite to that of other bodies within its system as observed from a particular vantage point...

, those beneath are retrograde

Retrograde and direct motion

Apparent retrograde motion is the motion of a planetary body in a direction opposite to that of other bodies within its system as observed from a particular vantage point...

. The radius of the Uranus' Hill sphere

Hill sphere

An astronomical body's Hill sphere is the region in which it dominates the attraction of satellites. To be retained by a planet, a moon must have an orbit that lies within the planet's Hill sphere. That moon would, in turn, have a Hill sphere of its own...

is approximately 73 million km.

Uranus's irregular moons range in size from about 150 km (Sycorax

Sycorax (moon)

Sycorax is the largest retrograde irregular satellite of Uranus. Sycorax was discovered on 6 September 1997 by Brett J. Gladman, Philip D. Nicholson, Joseph A. Burns, and John J...

) to 18 km (Trinculo

Trinculo (moon)

Trinculo is a retrograde irregular satellite of Uranus. It was discovered by Holman, et al. on 13 August 2001, and given the temporary designation S/2001 U 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

Orbital eccentricity

The orbital eccentricity of an astronomical body is the amount by which its orbit deviates from a perfect circle, where 0 is perfectly circular, and 1.0 is a parabola, and no longer a closed orbit...

. The inner group includes those satellites closer to Uranus (a < 0.15 r_H) and moderately eccentric (~0.2), namely Francisco

Francisco (moon)

Francisco 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....

, Caliban

Caliban (moon)

Caliban is the second largest retrograde irregular moon of Uranus. It was discovered on 6 September 1997 by Brett J. Gladman, Philip D. Nicholson, Joseph A. Burns, and John J...

, Stephano

Stephano (moon)

Stephano 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....

and Trinculo. The outer group (a > 0.15 r_H) includes satellites with high eccentricity (~0.5): Sycorax, Prospero

Prospero (moon)

Prospero 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...

, Setebos

Setebos (moon)

Setebos is one of the outermost retrograde irregular satellites of Uranus. It was discovered on 18 July 1999 by John J. Kavelaars et al. and provisionally designated S/1999 U 1....

and Ferdinand

Ferdinand (moon)

Ferdinand is the outermost retrograde irregular satellite of Uranus. It was discovered by Matthew J. Holman, John J. Kavelaars, Dan Milisavljevic, and Brett J. Gladman on August 13, 2001, and given the provisional designation S/2001 U 2....

.

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

Kozai mechanism

In celestial mechanics, the Kozai mechanism, or the Lidov-Kozai mechanism, causes a periodic exchange between the inclination and eccentricity of an orbit...

. In this instability region, solar perturbations

Perturbation (astronomy)

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.

Margaret

Margaret (moon)

Margaret 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....

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

Nereid (moon)

Nereid , also known as Neptune II, is the third-largest moon of Neptune. It has a highly eccentric orbit. Nereid was discovered by Gerard Kuiper in 1949 and was the second moon of Neptune to be discovered.- Discovery and naming :...

has a higher mean eccentricity. As of 2008, Margaret's eccentricity is 0.7979.

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

Gravitational collapse

Gravitational collapse is the inward fall of a body due to the influence of its own gravity. In any stable body, this gravitational force is counterbalanced by the internal pressure of the body, in the opposite direction to the force of gravity...

into a spheroid

Spheroid

A spheroid, or ellipsoid of revolution is a quadric surface obtained by rotating an ellipse about one of its principal axes; in other words, an ellipsoid with two equal semi-diameters....

are highlighted in light blue and bolded. Irregular moons with prograde orbits are shown in light grey, those with retrograde orbits in dark grey.

Uranian moons
Order Order refers to the position among other moons with respect to their average distance from Uranus.	Name	Pronunciation (key)	Semi-major axis Semi-major axis The major axis of an ellipse is its longest diameter, a line that runs through the centre and both foci, its ends being at the widest points of the shape... (km)	Inclination Inclination Inclination in general is the angle between a reference plane and another plane or axis of direction.-Orbits:The inclination is one of the six orbital parameters describing the shape and orientation of a celestial orbit... (° Degree (angle) A degree , usually denoted by ° , is a measurement of plane angle, representing 1⁄360 of a full rotation; one degree is equivalent to π/180 radians... )	Eccentricity Orbital eccentricity The orbital eccentricity of an astronomical body is the amount by which its orbit deviates from a perfect circle, where 0 is perfectly circular, and 1.0 is a parabola, and no longer a closed orbit...	Discovery year	Discoverer
1	Cordelia Cordelia (moon) Cordelia is the innermost 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...	kɔrˈdiːliə			0.00026	1986	Terrile Richard J. Terrile Richard John Terrile is a Voyager scientist who discovered several moons of Saturn, Uranus, and Neptune. He works for NASA's Jet Propulsion Laboratory.-References:... (Voyager 2 Voyager 2 The Voyager 2 spacecraft is a 722-kilogram space probe launched by NASA on August 20, 1977 to study the outer Solar System and eventually interstellar space... )
2	Ophelia Ophelia (moon) Ophelia 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...	ɵˈfiːliə			0.00992	1986	Terrile Richard J. Terrile Richard John Terrile is a Voyager scientist who discovered several moons of Saturn, Uranus, and Neptune. He works for NASA's Jet Propulsion Laboratory.-References:... (Voyager 2 Voyager 2 The Voyager 2 spacecraft is a 722-kilogram space probe launched by NASA on August 20, 1977 to study the outer Solar System and eventually interstellar space... )
3	Bianca Bianca (moon) Bianca 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...	biːˈɒŋkə			0.00092	1986	Smith (Voyager 2 Voyager 2 The Voyager 2 spacecraft is a 722-kilogram space probe launched by NASA on August 20, 1977 to study the outer Solar System and eventually interstellar space... )
4	Cressida Cressida (moon) Cressida is an inner satellite of Uranus. It was discovered from the images taken by Voyager 2 on 9 January 1986, and was given the temporary designation S/1986 U 3. It was named after the Trojan daughter of Calchas, a tragic heroine who appears in William Shakespeare's play Troilus and...	ˈkrɛsɨdə			0.00036	1986	Synnott Stephen P. Synnott Stephen P. Synnott is an American astronomer Voyager scientist who discovered several moons of Jupiter, Saturn, Uranus, and Neptune.He discovered Metis, Puck, Larissa , Proteus, and Thebe.-References:... (Voyager 2 Voyager 2 The Voyager 2 spacecraft is a 722-kilogram space probe launched by NASA on August 20, 1977 to study the outer Solar System and eventually interstellar space... )
5	Desdemona Desdemona (moon) Desdemona 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...	ˌdɛzdɨˈmoʊnə			0.00013	1986	Synnott Stephen P. Synnott Stephen P. Synnott is an American astronomer Voyager scientist who discovered several moons of Jupiter, Saturn, Uranus, and Neptune.He discovered Metis, Puck, Larissa , Proteus, and Thebe.-References:... (Voyager 2 Voyager 2 The Voyager 2 spacecraft is a 722-kilogram space probe launched by NASA on August 20, 1977 to study the outer Solar System and eventually interstellar space... )
6	Juliet Juliet (moon) Juliet 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...	ˈdʒuːli.ɨt			0.00066	1986	Synnott Stephen P. Synnott Stephen P. Synnott is an American astronomer Voyager scientist who discovered several moons of Jupiter, Saturn, Uranus, and Neptune.He discovered Metis, Puck, Larissa , Proteus, and Thebe.-References:... (Voyager 2 Voyager 2 The Voyager 2 spacecraft is a 722-kilogram space probe launched by NASA on August 20, 1977 to study the outer Solar System and eventually interstellar space... )
7	Portia Portia (moon) Portia 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 1. The moon is named after Portia, the heroine of William Shakespeare's play The Merchant of Venice...	ˈpɔrʃə			0.00005	1986	Synnott Stephen P. Synnott Stephen P. Synnott is an American astronomer Voyager scientist who discovered several moons of Jupiter, Saturn, Uranus, and Neptune.He discovered Metis, Puck, Larissa , Proteus, and Thebe.-References:... (Voyager 2 Voyager 2 The Voyager 2 spacecraft is a 722-kilogram space probe launched by NASA on August 20, 1977 to study the outer Solar System and eventually interstellar space... )
8	Rosalind Rosalind (moon) Rosalind 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...	ˈrɒzəlɨnd			0.00011	1986	Synnott Stephen P. Synnott Stephen P. Synnott is an American astronomer Voyager scientist who discovered several moons of Jupiter, Saturn, Uranus, and Neptune.He discovered Metis, Puck, Larissa , Proteus, and Thebe.-References:... (Voyager 2 Voyager 2 The Voyager 2 spacecraft is a 722-kilogram space probe launched by NASA on August 20, 1977 to study the outer Solar System and eventually interstellar space... )
9	Cupid Cupid (moon) Cupid is an inner satellite of Uranus. It was discovered by Mark 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....	ˈkjuːpɨd			0.0013	2003	Showalter and Lissauer Jack J. Lissauer Jack Jonathan Lissauer is an American research scientist who has worked for the NASA's Ames Research Center since 1996. He is a science co-investigator on the Kepler space telescope mission.-Biography:...
10	Belinda Belinda (moon) - External links :* by *...	bɨˈlɪndə			0.00007	1986	Synnott Stephen P. Synnott Stephen P. Synnott is an American astronomer Voyager scientist who discovered several moons of Jupiter, Saturn, Uranus, and Neptune.He discovered Metis, Puck, Larissa , Proteus, and Thebe.-References:... (Voyager 2 Voyager 2 The Voyager 2 spacecraft is a 722-kilogram space probe launched by NASA on August 20, 1977 to study the outer Solar System and eventually interstellar space... )
11	Perdita Perdita (moon) Perdita is an inner satellite of Uranus. Perdita's discovery was complicated. The first photographs of Perdita were taken by the Voyager 2 spacecraft in 1986, but it was not recognized from the photographs for more than a decade. In 1999, the moon was noticed by Erich Karkoschka and reported...	ˈpɜrdɨtə			0.0012	1999	Karkoschaka Erich Karkoschka Erich Karkoschka is a planetary researcher at the Lunar and Planetary Lab of the University of Arizona. He discovered a satellite of Uranus, S/1986 U 10 on photographs taken by the Voyager 2 spacecraft... (Voyager 2 Voyager 2 The Voyager 2 spacecraft is a 722-kilogram space probe launched by NASA on August 20, 1977 to study the outer Solar System and eventually interstellar space... )
12	Puck Puck (moon) Puck is an inner moon of Uranus. It was discovered in December 1985 by the Voyager 2 spacecraft. The name Puck comes from Celtic mythology and English folklore. The orbit of Puck lies between the rings of Uranus and the first of Uranus' large moons, Miranda. Puck is approximately spherical in...	ˈpʌk			0.00012	1985	Synnott Stephen P. Synnott Stephen P. Synnott is an American astronomer Voyager scientist who discovered several moons of Jupiter, Saturn, Uranus, and Neptune.He discovered Metis, Puck, Larissa , Proteus, and Thebe.-References:... (Voyager 2 Voyager 2 The Voyager 2 spacecraft is a 722-kilogram space probe launched by NASA on August 20, 1977 to study the outer Solar System and eventually interstellar space... )
13	Mab Mab (moon) Mab , or Uranus XXVI , is an inner satellite of Uranus. It was discovered by Mark R. Showalter and Jack J. Lissauer in 2003 using the Hubble Space Telescope...	ˈmæb			0.0025	2003	Showalter and Lissauer
14	^‡Miranda Miranda (moon) -External links:* at * at The Nine8 Planets* at Views of the Solar System* * from the...	mɨˈrændə			0.0013	1948	Kuiper
15	^‡Ariel Ariel (moon) Ariel is the brightest and fourth-largest of the 27 known moons of Uranus. Ariel orbits and rotates in the equatorial plane of Uranus, which is almost perpendicular to the orbit of Uranus, and so has an extreme seasonal cycle....	ˈɛəriəl			0.0012	1851	Lassell William Lassell William Lassell FRS was an English merchant and astronomer.Born in Bolton and educated in Rochdale after the death of his father, he was apprenticed from 1814 to 1821 to a merchant in Liverpool. He then made his fortune as a beer brewer, which enabled him to indulge his interest in astronomy...
16	^‡Umbriel Umbriel (moon) Umbriel is a moon of Uranus discovered on October 24, 1851, by William Lassell. It was discovered at the same time as Ariel and named after a character in Alexander Pope's poem The Rape of the Lock. Umbriel consists mainly of ice with a substantial fraction of rock, and may be differentiated into a...	ˈʌmbriəl			0.?	1851	Lassell William Lassell William Lassell FRS was an English merchant and astronomer.Born in Bolton and educated in Rochdale after the death of his father, he was apprenticed from 1814 to 1821 to a merchant in Liverpool. He then made his fortune as a beer brewer, which enabled him to indulge his interest in astronomy...
17	^‡Titania Titania (moon) Titania is the largest of the moons of Uranus and the eighth largest moon in the Solar System at a diameter of 1578 km. Discovered by William Herschel in 1787, Titania is named after the queen of the fairies in Shakespeare's A Midsummer Night's Dream...	tɨˈtɑːnjə			0.0011	1787	Herschel William Herschel Sir Frederick William Herschel, KH, FRS, German: Friedrich Wilhelm Herschel was a German-born British astronomer, technical expert, and composer. Born in Hanover, Wilhelm first followed his father into the Military Band of Hanover, but emigrated to Britain at age 19...
18	^‡Oberon Oberon (moon) Oberon , also designated ', is the outermost major moon of the planet Uranus. It is the second largest and second most massive of the Uranian moons, and the ninth most massive moon in the Solar System. Discovered by William Herschel in 1787, Oberon is named after the mythical king of the fairies...	ˈoʊbərɒn			0.0014	1787	Herschel William Herschel Sir Frederick William Herschel, KH, FRS, German: Friedrich Wilhelm Herschel was a German-born British astronomer, technical expert, and composer. Born in Hanover, Wilhelm first followed his father into the Military Band of Hanover, but emigrated to Britain at age 19...
19	^♠Francisco Francisco (moon) Francisco 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....	frænˈsɪskoʊ		147.459°	0.1459	2003Detected in 2001, published in 2003.	Holman Matthew J. Holman Matthew J. Holman is a Smithsonian Astrophysicist and lecturer at Harvard University. Holman studied at MIT, where he received his bachelor's degree in mathematics in 1989 and his PhD in planetary science in 1994.... et al.
20	^♠Caliban Caliban (moon) Caliban is the second largest retrograde irregular moon of Uranus. It was discovered on 6 September 1997 by Brett J. Gladman, Philip D. Nicholson, Joseph A. Burns, and John J...	ˈkælɨbæn		139.885°	0.1587	1997	Gladman Brett J. Gladman Brett J. Gladman is a Canadian astronomer and a full professor at the University of British Columbia's Department of Physics and Astronomy in Vancouver, British Columbia. He holds the Canada Research Chair in Planetary Astronomy.-Career:... et al.
21	^♠Stephano Stephano (moon) Stephano 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....	ˈstɛfənoʊ		141.873°	0.2292	1999	Gladman Brett J. Gladman Brett J. Gladman is a Canadian astronomer and a full professor at the University of British Columbia's Department of Physics and Astronomy in Vancouver, British Columbia. He holds the Canada Research Chair in Planetary Astronomy.-Career:... et al.
22	^♠Trinculo Trinculo (moon) Trinculo is a retrograde irregular satellite of Uranus. It was discovered by Holman, et al. on 13 August 2001, and given the temporary designation S/2001 U 1....	ˈtrɪŋkjʊloʊ		166.252°	0.2200	2001	Holman Matthew J. Holman Matthew J. Holman is a Smithsonian Astrophysicist and lecturer at Harvard University. Holman studied at MIT, where he received his bachelor's degree in mathematics in 1989 and his PhD in planetary science in 1994.... et al.
23	^♠Sycorax Sycorax (moon) Sycorax is the largest retrograde irregular satellite of Uranus. Sycorax was discovered on 6 September 1997 by Brett J. Gladman, Philip D. Nicholson, Joseph A. Burns, and John J...	ˈsɪkəræks	12,179,000	152.456°	0.5224	1997	Nicholson et al.
24	Margaret Margaret (moon) Margaret 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....	ˈmɑrɡərɨt	14,345,000		0.6608	2003	Sheppard Scott S. Sheppard Scott S. Sheppard is an astronomer in the Department of Terrestrial Magnetism at the Carnegie Institution for Science. Starting as a graduate student at the Institute for Astronomy at the University of Hawaii, he was credited with the discovery of many small moons of Jupiter, Saturn, Uranus, and... and Jewitt David C. Jewitt David C. Jewitt is a professor of astronomy formerly at the University of Hawaii Institute for Astronomy, now at UCLA. He was born in 1958 in England, and is a 1979 graduate of the University of London. Jewitt received an M.Sc. and a Ph.D. in astronomy at the California Institute of Technology in...
25	^♠Prospero Prospero (moon) Prospero 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...	ˈprɒspəroʊ	16,256,000	146.017°	0.4448	1999	Holman Matthew J. Holman Matthew J. Holman is a Smithsonian Astrophysicist and lecturer at Harvard University. Holman studied at MIT, where he received his bachelor's degree in mathematics in 1989 and his PhD in planetary science in 1994.... et al.
26	^♠Setebos Setebos (moon) Setebos is one of the outermost retrograde irregular satellites of Uranus. It was discovered on 18 July 1999 by John J. Kavelaars et al. and provisionally designated S/1999 U 1....	ˈsɛtɨbʌs	17,418,000	145.883°	0.5914	1999	Kavelaars John J. Kavelaars John J. Kavelaars, better known as JJ Kavelaars, is a Canadian astronomer who was part of a team that discovered several moons of Jupiter, Saturn, Uranus, and Neptune.... et al.
27	^♠Ferdinand Ferdinand (moon) Ferdinand is the outermost retrograde irregular satellite of Uranus. It was discovered by Matthew J. Holman, John J. Kavelaars, Dan Milisavljevic, and Brett J. Gladman on August 13, 2001, and given the provisional designation S/2001 U 2....	ˈfɜrdɨnænd	20,901,000	167.346°	0.3682	2003	Holman Matthew J. Holman Matthew J. Holman is a Smithsonian Astrophysicist and lecturer at Harvard University. Holman studied at MIT, where he received his bachelor's degree in mathematics in 1989 and his PhD in planetary science in 1994.... et al.

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

External links

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