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The naming of moons has been the responsibility of the
International Astronomical Union The International Astronomical Union (IAU; , UAI) is an international non-governmental organization (INGO) with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach, education, and developmen ...
's committee for Planetary System Nomenclature since 1973. That committee is known today as the
Working Group for Planetary System Nomenclature The International Astronomical Union (IAU; , UAI) is an international non-governmental organization (INGO) with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach, education, and developmen ...
(WGPSN). Prior to its formation, the names of
satellites A satellite or an artificial satellite is an object, typically a spacecraft, placed into orbit around a celestial body. They have a variety of uses, including communication relay, weather forecasting, navigation ( GPS), broadcasting, scientif ...
have had varying histories. The choice of names is often determined by a satellite's discoverer; however, historically some satellites were not given names for many years after their discovery; for instance,
Titan Titan most often refers to: * Titan (moon), the largest moon of Saturn * Titans, a race of deities in Greek mythology Titan or Titans may also refer to: Arts and entertainment Fictional entities Fictional locations * Titan in fiction, fictiona ...
was discovered by Huygens in 1655, but was not named until 1847, almost two centuries later. Before the IAU assumed responsibility for astronomical nomenclature, only twenty-five satellites had been given names that were in wide use and are still used: 1 of Earth, 2 of Mars, 5 of Jupiter, 10 of Saturn, 5 of Uranus, and 2 of Neptune. Since then, names have been given to 137 additional planetary and dwarf planetary satellites: 52 satellites of
Jupiter Jupiter is the fifth planet from the Sun and the List of Solar System objects by size, largest in the Solar System. It is a gas giant with a Jupiter mass, mass more than 2.5 times that of all the other planets in the Solar System combined a ...
, 53 of
Saturn Saturn is the sixth planet from the Sun and the second largest in the Solar System, after Jupiter. It is a gas giant, with an average radius of about 9 times that of Earth. It has an eighth the average density of Earth, but is over 95 tim ...
, 22 of
Uranus Uranus is the seventh planet from the Sun. It is a gaseous cyan-coloured ice giant. Most of the planet is made of water, ammonia, and methane in a Supercritical fluid, supercritical phase of matter, which astronomy calls "ice" or Volatile ( ...
, 12 of
Neptune Neptune is the eighth and farthest known planet from the Sun. It is the List of Solar System objects by size, fourth-largest planet in the Solar System by diameter, the third-most-massive planet, and the densest giant planet. It is 17 t ...
, 5 of
Pluto Pluto (minor-planet designation: 134340 Pluto) is a dwarf planet in the Kuiper belt, a ring of Trans-Neptunian object, bodies beyond the orbit of Neptune. It is the ninth-largest and tenth-most-massive known object to directly orbit the Su ...
, 2 of
Haumea Haumea ( minor-planet designation: 136108 Haumea) is a dwarf planet located beyond Neptune's orbit. It was discovered in 2004 by a team headed by Mike Brown of Caltech at the Palomar Observatory, and formally announced in 2005 by a team heade ...
, and 1 each of , , , and . Names have also been given to some satellites of minor planets, including the dwarf planet candidates and which have one satellite each. The number will continue to rise as current satellite discoveries are documented and new satellites are discovered. At the IAU General Assembly in July 2004,
the WGPSN suggested it may become advisable to not name small satellites, as
CCD CCD may refer to: Science and technology * Charge-coupled device, an electronic light sensor used in various devices including digital cameras * .ccd, the filename extension for CloneCD's CD image file * Carbonate compensation depth, a property ...
technology makes it possible to discover satellites as small as 1 km in diameter. Until 2014, names were applied to all planetary moons discovered, regardless of size. From 2015, some small moons have not received names.


Naming of moons by Solar System object


Earth

Every human language has its own word for the Earth's
Moon The Moon is Earth's only natural satellite. It Orbit of the Moon, orbits around Earth at Lunar distance, an average distance of (; about 30 times Earth diameter, Earth's diameter). The Moon rotation, rotates, with a rotation period (lunar ...
, and these words are the ones normally used in astronomical contexts. However, a number of fanciful or mythological names for the Moon have been used in the context of astronomy (an even larger number of lunar epithets have been used in non-astronomical contexts). In the 17th century, the Moon was sometimes referred to as ''Proserpina''. More recently, especially in science-fiction content, the Moon has been called by the
Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...
name ''Luna'', presumably on the analogy of the Latin names of the planets, or by association with the adjectival form ''lunar'', or a need to differentiate it from other moons that may be present in a fictional setting. In technical terminology, the word-stems ''seleno-'' (from
Greek Greek may refer to: Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group *Greek language, a branch of the Indo-European language family **Proto-Greek language, the assumed last common ancestor of all kno ...
''selēnē'' "moon") and ''cynthi-'' (from ''Cynthia'', an epithet of the goddess
Artemis In ancient Greek religion and Greek mythology, mythology, Artemis (; ) is the goddess of the hunting, hunt, the wilderness, wild animals, transitions, nature, vegetation, childbirth, Kourotrophos, care of children, and chastity. In later tim ...
) are sometimes used to refer to the Moon, as in ''selenography, selenology,'' and ''pericynthion.''


Mars

The moons of
Mars Mars is the fourth planet from the Sun. It is also known as the "Red Planet", because of its orange-red appearance. Mars is a desert-like rocky planet with a tenuous carbon dioxide () atmosphere. At the average surface level the atmosph ...
( Phobos and
Deimos Deimos, a Greek word for ''dread'', may refer to: In general * Deimos (deity), one of the sons of Ares and Aphrodite in Greek mythology * Deimos (moon), the smaller and outermost of Mars' two natural satellites Fictional characters * Deimos (comi ...
) were named by
Asaph Hall Asaph Hall III (October 15, 1829 – November 22, 1907) was an American astronomer who is best known for having discovered the two moons of Mars, Deimos and Phobos, in 1877. He determined the orbits of satellites of other planets and of doubl ...
in 1878, soon after he discovered them. They are named after the sons of the god
Ares Ares (; , ''Árēs'' ) is the List of Greek deities, Greek god of war god, war and courage. He is one of the Twelve Olympians, and the son of Zeus and Hera. The Greeks were ambivalent towards him. He embodies the physical valor necessary for ...
(the Greek equivalent of the Roman god
Mars Mars is the fourth planet from the Sun. It is also known as the "Red Planet", because of its orange-red appearance. Mars is a desert-like rocky planet with a tenuous carbon dioxide () atmosphere. At the average surface level the atmosph ...
).


Jupiter

The
Galilean moons The Galilean moons (), or Galilean satellites, are the four largest moons of Jupiter. They are, in descending-size order, Ganymede (moon), Ganymede, Callisto (moon), Callisto, Io (moon), Io, and Europa (moon), Europa. They are the most apparent m ...
of Jupiter ( Io,
Europa Europa may refer to: Places * Europa (Roman province), a province within the Diocese of Thrace * Europa (Seville Metro), Seville, Spain; a station on the Seville Metro * Europa City, Paris, France; a planned development * Europa Cliffs, Alexan ...
, Ganymede and
Callisto CALLISTO (''Cooperative Action Leading to Launcher Innovation in Stage Toss-back Operations'') is a reusable VTVL Prototype, demonstrator propelled by a small 40 kN Japanese LOX-LH2 rocket engine. It is being developed jointly by the CNES, French ...
) were named by Simon Marius soon after their discovery in 1610. However, by the late 19th century these names had fallen out of favor, and for a long time it was most common to refer to them in the astronomical literature simply as "Jupiter I", "Jupiter II", etc., or as "the first satellite of Jupiter", "Jupiter's second satellite", etc. By the first decade of the 20th century, the names Io, Europa, Ganymede, and Callisto had once again recovered popularity, but the later-discovered moons, numbered, usually in Roman numerals V (5) through XII (12), remained unnamed. By a popular though unofficial convention, Jupiter V, discovered in 1892, was given the name ''Amalthea'', first used by the French astronomer
Camille Flammarion Nicolas Camille Flammarion FRAS (; 26 February 1842 – 3 June 1925) was a French astronomer and author. He was a prolific author of more than fifty titles, including popular science works about astronomy, several notable early science fiction ...
. The other
irregular satellite In astronomy, an irregular moon, irregular satellite, or irregular natural satellite is a natural satellite following an orbit that is irregular in some of the following ways: Distant; inclined; highly elliptical; retrograde. They have often be ...
s (discovered 1904 to 1951) were, in the overwhelming majority of astronomical literature, simply left nameless. No names were proposed until Brian G. Marsden suggested a nomenclature for these satellites in 1955. Although the 1955 names met with immediate acceptance in some quarters (e.g. in science fiction and popular science articles), they were still rarely if ever met in astronomical literature until the 1970s. Two other proposals for naming the satellites were made between 1955 and 1975, both by Soviet astronomers, E. I. Nesterovich (in 1962) and Yu. A. Karpenko (in 1973).Журнал "Земля и Вселенная" №6 1973 г
/ref> These met no particularly enthusiastic reception. In 1975, following Charles Kowal's discovery of the satellite Jupiter XIII in 1974, the
IAU The International Astronomical Union (IAU; , UAI) is an international non-governmental organization (INGO) with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach, education, and developmen ...
Task Group for Outer Solar System Nomenclature granted names to satellites V-XIII, and provided for a formal naming process for future satellites to be discovered. Under the new process, Jupiter V continued as Amalthea, Jupiter XIII was named Leda in accordance with a suggestion of Kowal's, and all previous proposals for the seven satellites VI-XII were abandoned in favor of new names, in accordance with a scheme suggested by the German philologist
Jürgen Blunck Jürgen or Jurgen is a popular masculine given name in Germany, Estonia, Belgium and the Netherlands. Notable people named Jürgen include: A * Jürgen Ahrend (1930–2024), German organ builder *Jürgen Alzen (born 1962), German race car driv ...
where prograde moons received names ending in 'a' and
retrograde Retrograde may refer to: Film and television * Retrograde (2004 film), ''Retrograde'' (2004 film), a film by Christopher Kulikowski * Retrograde (2022 American film), ''Retrograde'' (2022 American film), a documentary film by Matthew Heineman * ...
moons received names ending in 'e'. The new names met considerable protest from some quarters. Kowal, despite suggesting a name for Jupiter XIII, was of the opinion that Jupiter's irregular satellites should not be named at all.
Carl Sagan Carl Edward Sagan (; ; November 9, 1934December 20, 1996) was an American astronomer, planetary scientist and science communicator. His best known scientific contribution is his research on the possibility of extraterrestrial life, including e ...
noted that the names chosen were extraordinarily obscure (a fact that
Tobias Owen Tobias is the transliteration of the , which is a Graecisation of the Hebrew biblical name . With the biblical Book of Tobit being present in the Deuterocanonical books and Biblical apocrypha, Tobias is a popular male given name for both Christi ...
, chair of the Task Group, admitted was intentional in a response to Sagan) and suggested his own names in 1976; these preserved some of the names from the 1955 proposal. Karpenko had noted the same in his 1981 book "The Names of the Starry Sky", along with stating that the names chosen for retrograde moons, and therefore the "e" ending, were not always the ones for which it was the more common one. The proposals are summarized in the table below (data from ''Icarus'' unless specified otherwise): Current practice is that newly discovered moons of Jupiter must be named after lovers or descendants of the mythological
Jupiter Jupiter is the fifth planet from the Sun and the List of Solar System objects by size, largest in the Solar System. It is a gas giant with a Jupiter mass, mass more than 2.5 times that of all the other planets in the Solar System combined a ...
(
Zeus Zeus (, ) is the chief deity of the List of Greek deities, Greek pantheon. He is a sky father, sky and thunder god in ancient Greek religion and Greek mythology, mythology, who rules as king of the gods on Mount Olympus. Zeus is the child ...
). Blunck's scheme for the outer moons was retained, with the addition that names ending in 'o' could also be used for prograde moons. At the IAU General Assembly in July 2004, the WGPSN allowed Jovian satellites to be named for
Zeus Zeus (, ) is the chief deity of the List of Greek deities, Greek pantheon. He is a sky father, sky and thunder god in ancient Greek religion and Greek mythology, mythology, who rules as king of the gods on Mount Olympus. Zeus is the child ...
' descendants in addition to his lovers and favorites which were the previous source of names, due to the large number of new Jovian satellites that had then recently been discovered. All of Jupiter's satellites from XXXIV (
Euporie In Greek mythology, the Horae (), Horai () or Hours (, ) were the goddesses of the seasons and the natural portions of time. Etymology The term ''hora'' comes from the Proto-Indo-European ("year"). Function The Horae were originally the p ...
) on were named for descendants of Zeus, until Jupiter LIII ( Dia), named after another one of his lovers.


Saturn

In 1847, the seven then known moons of
Saturn Saturn is the sixth planet from the Sun and the second largest in the Solar System, after Jupiter. It is a gas giant, with an average radius of about 9 times that of Earth. It has an eighth the average density of Earth, but is over 95 tim ...
were named by
John Herschel Sir John Frederick William Herschel, 1st Baronet (; 7 March 1792 – 11 May 1871) was an English polymath active as a mathematician, astronomer, chemist, inventor and experimental photographer who invented the blueprint and did botanical work. ...
. Herschel named Saturn's two innermost moons (Mimas and Enceladus) after the mythological Greek
Giants A giant is a being of human appearance, sometimes of prodigious size and strength, common in folklore. Giant(s) or The Giant(s) may also refer to: Mythology and religion *Giants (Greek mythology) * Jötunn, a Germanic term often translated as 'g ...
, and the outer five after the
Titan Titan most often refers to: * Titan (moon), the largest moon of Saturn * Titans, a race of deities in Greek mythology Titan or Titans may also refer to: Arts and entertainment Fictional entities Fictional locations * Titan in fiction, fictiona ...
s (Titan, Iapetus) and Titanesses (Tethys, Dione, Rhea) of the same mythology. Until then,
Titan Titan most often refers to: * Titan (moon), the largest moon of Saturn * Titans, a race of deities in Greek mythology Titan or Titans may also refer to: Arts and entertainment Fictional entities Fictional locations * Titan in fiction, fictiona ...
was known as the "Huygenian (or Huyghenian) satellite of Saturn" and the other moons had Roman numeral designations in order of their distance from Saturn. Subsequent discoverers of Saturnian moons followed Herschel's scheme: Hyperion was discovered soon after in 1848, and the ninth moon, Phoebe, was named by its discoverer in 1899 soon after its discovery; they were named for a Titan and a Titaness respectively. The name of
Janus In ancient Roman religion and myth, Janus ( ; ) is the god of beginnings, gates, transitions, time, duality, doorways, passages, frames, and endings. He is usually depicted as having two faces. The month of January is named for Janus (''Ianu ...
was suggested by its discoverer,
Audouin Dollfus Audouin Charles Dollfus (12 November 1924 – 1 October 2010) was a French astronomer and aeronaut, specialist in studies of the Solar System and discoverer of Janus, a moon of Saturn. Life and career Dollfus was born in Paris to aeronaut Charle ...
. Current IAU practice for newly discovered inner moons is to continue with Herschel's system, naming them after Titans or their descendants. However, the increasing number of moons that were being discovered in the 21st century caused the IAU to draw up a new scheme for the outer moons. At the IAU General Assembly in July 2004, the WGPSN allowed satellites of Saturn to have names of giants and monsters in mythologies other than the Greco-Roman. Since the outer moons fall naturally into three groups, one group is named after Norse giants, one after Gallic giants, and one after
Inuit Inuit (singular: Inuk) are a group of culturally and historically similar Indigenous peoples traditionally inhabiting the Arctic and Subarctic regions of North America and Russia, including Greenland, Labrador, Quebec, Nunavut, the Northwe ...
giants. The only moon that fails to fit this scheme is the Greek-named Phoebe, which is in the Norse group.


Uranus

The Roman numbering scheme of
Uranus Uranus is the seventh planet from the Sun. It is a gaseous cyan-coloured ice giant. Most of the planet is made of water, ammonia, and methane in a Supercritical fluid, supercritical phase of matter, which astronomy calls "ice" or Volatile ( ...
' moons was in a state of flux for a considerable time. Sir William Herschel thought he had discovered up to six moons and maybe even a ring. For nearly fifty years, Herschel's instrument was the only one the moons had been seen with. In the 1840s, better instruments and a more favourable position of Uranus in the sky led to sporadic indications of satellites additional to Titania and Oberon. Publications hesitated between William 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. 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 Sir John Frederick William Herschel, 1st Baronet (; 7 March 1792 – 11 May 1871) was an English polymath active as a mathematician, astronomer, chemist, inventor and experimental photographer who invented the blueprint and did botanical work. ...
, son of the discoverer of Uranus. Herschel, instead of assigning names from
Greek mythology Greek mythology is the body of myths originally told by the Ancient Greece, ancient Greeks, and a genre of ancient Greek folklore, today absorbed alongside Roman mythology into the broader designation of classical mythology. These stories conc ...
, named the moons after magical spirits in
English literature English literature is literature written in the English language from the English-speaking world. The English language has developed over more than 1,400 years. The earliest forms of English, a set of Anglo-Frisian languages, Anglo-Frisian d ...
: the fairies
Oberon Oberon () is a king of the fairy, fairies in Middle Ages, medieval and Renaissance literature. He is best known as a character in William Shakespeare's play ''A Midsummer Night's Dream'', in which he is King of the Fairies and spouse of Titania ...
and Titania from
William Shakespeare William Shakespeare ( 23 April 1564 – 23 April 1616) was an English playwright, poet and actor. He is widely regarded as the greatest writer in the English language and the world's pre-eminent dramatist. He is often called England's nation ...
's ''
A Midsummer Night's Dream ''A Midsummer Night's Dream'' is a Comedy (drama), comedy play written by William Shakespeare in about 1595 or 1596. The play is set in Athens, and consists of several subplots that revolve around the marriage of Theseus and Hippolyta. One s ...
'', and the sylphs Ariel and Umbriel from
Alexander Pope Alexander Pope (21 May 1688 Old Style and New Style dates, O.S. – 30 May 1744) was an English poet, translator, and satirist of the Age of Enlightenment, Enlightenment era who is considered one of the most prominent English poets of the early ...
's ''
The Rape of the Lock ''The Rape of the Lock'' is a mock-heroic narrative poem written by Alexander Pope. One of the most commonly cited examples of high burlesque, it was first published anonymously in Lintot's ''Miscellaneous Poems and Translations'' (May 1712) ...
'' (
Ariel Ariel may refer to: Film and television *Ariel Award, a Mexican Academy of Film award * ''Ariel'' (film), a 1988 Finnish film by Aki Kaurismäki *, a Russian film directed by Yevgeni Kotov * ''ARIEL Visual'' and ''ARIEL Deluxe'', a 1989 and 1991 ...
is also a sprite in Shakespeare's ''
The Tempest ''The Tempest'' is a Shakespeare's plays, play by William Shakespeare, probably written in 1610–1611, and thought to be one of the last plays that he wrote alone. After the first scene, which takes place on a ship at sea during a tempest, th ...
''). 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 and Mab continuing the trend), have focused on Herschel's source material. In 1949, the fifth moon, Miranda, was named by its discoverer,
Gerard Kuiper Gerard Peter Kuiper ( ; born Gerrit Pieter Kuiper, ; 7 December 1905 – 23 December 1973) was a Dutch-American astronomer, planetary scientist, selenographer, author and professor. The Kuiper belt is named after him. Kuiper is consi ...
, after a thoroughly mortal character in Shakespeare's ''
The Tempest ''The Tempest'' is a Shakespeare's plays, play by William Shakespeare, probably written in 1610–1611, and thought to be one of the last plays that he wrote alone. After the first scene, which takes place on a ship at sea during a tempest, th ...
''. 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 being from Shakespeare). All the retrograde irregular moons are named after characters from one play, ''The Tempest''; the only prograde irregular moon,
Margaret Margaret is a feminine given name, which means "pearl". It is of Latin origin, via Ancient Greek and ultimately from Iranian languages, Old Iranian. It has been an English language, English name since the 11th century, and remained popular thro ...
, is named from ''
Much Ado About Nothing ''Much Ado About Nothing'' is a Shakespearean comedy, comedy by William Shakespeare thought to have been written in 1598 and 1599.See textual notes to ''Much Ado About Nothing'' in ''The Norton Shakespeare'' (W. W. Norton & Company, 1997 ) p. ...
''.


Neptune

The one known moon (at the time) of
Neptune Neptune is the eighth and farthest known planet from the Sun. It is the List of Solar System objects by size, fourth-largest planet in the Solar System by diameter, the third-most-massive planet, and the densest giant planet. It is 17 t ...
was not named for many decades. Although the name
Triton Triton commonly refers to: * Triton (mythology), a Greek god * Triton (moon), a satellite of Neptune Triton may also refer to: Biology * Triton cockatoo, a parrot * Triton (gastropod), a group of sea snails * ''Triton'', a synonym of ''Triturus' ...
was suggested in 1880 by
Camille Flammarion Nicolas Camille Flammarion FRAS (; 26 February 1842 – 3 June 1925) was a French astronomer and author. He was a prolific author of more than fifty titles, including popular science works about astronomy, several notable early science fiction ...
, it did not come into general use until the mid 20th-century, and for many years was considered "unofficial". In the astronomical literature it was simply referred to as "the satellite of Neptune". Later, the second known moon,
Nereid In Greek mythology, the Nereids or Nereides ( ; ; , also Νημερτές) are sea nymphs (female spirits of sea waters), the 50 daughters of the ' Old Man of the Sea' Nereus and the Oceanid Doris, sisters to their brother Nerites. They ofte ...
, was named by its discoverer in 1949,
Gerard P. Kuiper Gerard Peter Kuiper ( ; born Gerrit Pieter Kuiper, ; 7 December 1905 – 23 December 1973) was a Dutch-American astronomer, planetary scientist, selenographer, author and professor. The Kuiper belt is named after him. Kuiper is consi ...
, soon after its discovery. Current IAU practice for newly discovered Neptunian moons is to accord with these first two choices by naming them after Greek sea deities. For the "normal" irregular satellites, the general convention is to use names ending in "a" for prograde satellites, names ending in "e" for retrograde satellites, and names ending in "o" for exceptionally inclined satellites, exactly like the convention for the
moons of Jupiter There are 97 Natural satellite, moons of Jupiter with confirmed orbits . This number does not include a number of meter-sized moonlets thought to be shed from the inner moons, nor hundreds of possible kilometer-sized outer irregular moons that ...
.


Pluto

The name of
Pluto Pluto (minor-planet designation: 134340 Pluto) is a dwarf planet in the Kuiper belt, a ring of Trans-Neptunian object, bodies beyond the orbit of Neptune. It is the ninth-largest and tenth-most-massive known object to directly orbit the Su ...
's moon
Charon In Greek mythology, Charon or Kharon ( ; ) is a psychopomp, the ferryman of the Greek underworld. He carries the souls of those who have been given funeral rites across the rivers Acheron and Styx, which separate the worlds of the living and ...
was suggested by
James W. Christy James Walter "Jim" Christy (born September 15, 1938) is an American astronomer known for discovering Charon, the largest moon of the dwarf planet Pluto. Early years Christy was born in 1938 in Milwaukee, Wisconsin. He attended the University of ...
, its discoverer, soon after its discovery. The other four moons are named Hydra, Nix, Kerberos, and
Styx In Greek mythology, Styx (; ; lit. "Shuddering"), also called the River Styx, is a goddess and one of the rivers of the Greek Underworld. Her parents were the Titans Oceanus and Tethys, and she was the wife of the Titan Pallas and the moth ...
. Charon, Hydra, Nix, and Kerberos are all characters in Greek mythology, with ties to Hades (the Greek equivalent of Pluto).
Charon In Greek mythology, Charon or Kharon ( ; ) is a psychopomp, the ferryman of the Greek underworld. He carries the souls of those who have been given funeral rites across the rivers Acheron and Styx, which separate the worlds of the living and ...
ferries the dead across the River Acheron, Hydra guards the waters of the underworld, and Nix (a respelling of
Nyx In Greek mythology, Nyx (; ) is the goddess and personification of the night. In Hesiod's ''Theogony'', she is the offspring of Chaos, and the mother of Aether and Hemera (Day) by Erebus (Darkness). By herself, she produces a brood of children ...
), mother of Charon, is the goddess of darkness and the night. Kerberos is a giant three-headed dog who guards the entrance to the underworld. The fifth moon is named for the river
Styx In Greek mythology, Styx (; ; lit. "Shuddering"), also called the River Styx, is a goddess and one of the rivers of the Greek Underworld. Her parents were the Titans Oceanus and Tethys, and she was the wife of the Titan Pallas and the moth ...
that forms the boundary between the worlds of the living and the dead.


Eris

The name of Eris's moon Dysnomia was suggested by its discoverer
Michael E. Brown Michael E. "Mike" Brown (born June 5, 1965) is an American astronomer, who has been professor of planetary astronomy at the California Institute of Technology (Caltech) since 2003. His team has discovered many trans-Neptunian objects (TNOs), ...
, who also suggested the name of the dwarf planet. The name has two meanings: in mythology Dysnomia (lawlessness) is the daughter of Eris (chaos). However, the name is also an intentional reference to the actor
Lucy Lawless Lucille Frances Lawless (; born 29 March 1968) is a New Zealand actress and director. She is best known for her roles as Xena in the television series ''Xena: Warrior Princess'', as Number Three (Battlestar Galactica), D'Anna Biers on the re-im ...
who plays the character
Xena Xena is a fictional character from the '' Xena: Warrior Princess'' franchise, portrayed by New Zealand actress Lucy Lawless and co-created by Robert Tapert and John Schulian. She first appeared as a villain in the 1995–1999 television serie ...
. The background for this is that during the long period when Eris had no formal name, the name 'Xena' – originally Brown's nickname for his discovery – spread and became popular. When the name 'Eris' was chosen, Brown suggested Dysnomia (which until then had been referred to as Gabrielle) as a reference to this. Hence, Dysnomia is the only moon which could be said to be named after an actor. The names Eris and Dysnomia were accepted by the IAU on 14 September 2006.


Haumea

The name of
Haumea Haumea ( minor-planet designation: 136108 Haumea) is a dwarf planet located beyond Neptune's orbit. It was discovered in 2004 by a team headed by Mike Brown of Caltech at the Palomar Observatory, and formally announced in 2005 by a team heade ...
and its
moons A natural satellite is, in the most common usage, an astronomical body that orbits a planet, dwarf planet, or small Solar System body (or sometimes another natural satellite). Natural satellites are colloquially referred to as moons, a deriva ...
were suggested by David L. Rabinowitz of
Caltech The California Institute of Technology (branded as Caltech) is a private university, private research university in Pasadena, California, United States. The university is responsible for many modern scientific advancements and is among a small g ...
and refer to the mother goddess and her daughters in Hawaiian mythology.


Gonggong

When the discoverers of Gonggong proposed choices for a public vote on its name, they chose figures that had associates that could provide a name for the satellite. Xiangliu's name was chosen by its discovery team led by Csaba Kiss.


Quaoar

Quaoar was named after the creator god of the
Tongva The Tongva ( ) are an Indigenous peoples of California, Indigenous people of California from the Los Angeles Basin and the Channel Islands of California, Southern Channel Islands, an area covering approximately . In the precolonial era, the peop ...
tribe. Brown, who had co-discovered both Quaoar and its moon, left the name of the moon up to the Tongva. The Tongva chose the sky god
Weywot Weywot (formal designation (50000) Quaoar I; provisional designation S/2006 (50000) 1) is a natural satellite or moon of the trans-Neptunian dwarf planet Quaoar. It was discovered by Michael Brown and Terry-Ann Suer using images taken by th ...
, son of Quaoar."Heavenly Bodies and the People of the Earth"
, Nick Street, ''Search Magazine,'' July/August 2008


Orcus

On 23 March 2009, Brown asked readers of his weekly column to suggest possible names for the satellite of Orcus which he had codiscovered, with the best one to be submitted to the
International Astronomical Union The International Astronomical Union (IAU; , UAI) is an international non-governmental organization (INGO) with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach, education, and developmen ...
(IAU) on 5 April. The name
Vanth Vanth is a chthonic figure in Etruscan mythology shown in a variety of forms of funerary art, such as in tomb paintings and on sarcophagi. Background Vanth is a female entity in the Etruscan underworld that is often accompanied either by additio ...
, the winged
Etruscan __NOTOC__ Etruscan may refer to: Ancient civilization *Etruscan civilization (1st millennium BC) and related things: **Etruscan language ** Etruscan architecture **Etruscan art **Etruscan cities **Etruscan coins **Etruscan history **Etruscan myt ...
psychopomp Psychopomps (from the Greek word , , literally meaning the 'guide of souls') are creatures, spirits, angels, demons, or deities in many religions whose responsibility is to escort newly deceased souls from Earth to the afterlife. Their role is ...
who guides the souls of the dead to the underworld, was chosen from among a large pool of submissions. Vanth was the only suggestion that was purely Etruscan in origin. It was the most popular submission, first suggested by
Sonya Taaffe Sonya Taaffe is an American author of short fiction and poetry based out of Massachusetts. She grew up in Arlington and Lexington, Massachusetts and graduated from Brandeis University in 2003 where she received a B.A. and M.A. in Classical Stu ...
. The Etruscan Vanth is frequently portrayed in the company of
Charun In Etruscan mythology, Charun (also spelled Charu, or Karun) acted as one of the psychopompoi of the underworld (not to be confused with the god of the underworld, known to the Etruscans as Aita). He is often portrayed with Vanth, a winged fig ...
(Charon), and so as the name of the moon of Orcus (nicknamed the "anti-Pluto" because resonance with Neptune keeps it on the opposite side of the Sun from Pluto), it is an allusion to the parallels between Orcus and . Brown quoted Taaffe as saying that if Vanth "accompanies dead souls from the moment of death to the underworld itself, then of course her face is turned always toward Orcus", a reference to the likely synchronous orbit of Vanth about Orcus.


Asteroids and other trans-Neptunian objects

Unlike the planets and dwarf planets, relatively few moons orbiting asteroids have been named. Among them are the following:


Roman numeral designations

The Roman numbering system for satellites arose with the very first discovery of natural satellites other than Earth's Moon:
Galileo Galileo di Vincenzo Bonaiuti de' Galilei (15 February 1564 – 8 January 1642), commonly referred to as Galileo Galilei ( , , ) or mononymously as Galileo, was an Italian astronomer, physicist and engineer, sometimes described as a poly ...
referred to the
Galilean moons The Galilean moons (), or Galilean satellites, are the four largest moons of Jupiter. They are, in descending-size order, Ganymede (moon), Ganymede, Callisto (moon), Callisto, Io (moon), Io, and Europa (moon), Europa. They are the most apparent m ...
as I through IV (counting from Jupiter outward), refusing to adopt the names proposed by his rival Simon Marius. Similar numbering schemes naturally arose with the discovery of multiple moons around Saturn, Uranus, and Mars. The numbers initially designated the moons in orbital sequence, and were re-numbered after each new discovery; for instance, before the discovery of Mimas and Enceladus in 1789, Tethys was Saturn I, Dione Saturn II, etc., but after the new moons were discovered, Mimas became Saturn I, Enceladus Saturn II, Tethys Saturn III and Dione Saturn IV. In the middle of the 19th century, however, the numeration became fixed, and later discoveries failed to conform with the orbital sequence scheme. Amalthea, discovered in 1892, was labelled "Jupiter V" although it orbits more closely to Jupiter than does Io (Jupiter I). The unstated convention then became, at the close of the 19th century, that the numbers more or less reflected the order of discovery, except for prior historical exceptions (see
Timeline of discovery of Solar System planets and their natural satellites The timeline of discovery of Solar System planets and their natural satellites charts the progress of the discovery of new bodies over history. Each object is listed in chronological order of its discovery (multiple dates occur when the moments o ...
); though if a large number of satellites were discovered in a short span of time, the group could be numbered in orbital sequence, or according to other principles than strictly by order of discovery. The convention has been extended to natural satellites of minor planets, such as (87) Sylvia I Romulus. The outer irregular satellites of Jupiter (VI through XII) were left officially unnamed throughout this period, although as stated above some unofficial names were used in some contexts. From 1975 to 2009, the
International Astronomical Union The International Astronomical Union (IAU; , UAI) is an international non-governmental organization (INGO) with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach, education, and developmen ...
was assigning names to all planetary satellites, and Roman numerals were usually not assigned to satellites until they are named. (An exception is Saturn's moon Helene, which received the Roman numeral XII in 1982, but was not named until 1988.) During this period, the use of Roman numeral designations diminished, and some are very rarely used; Phobos and
Deimos Deimos, a Greek word for ''dread'', may refer to: In general * Deimos (deity), one of the sons of Ares and Aphrodite in Greek mythology * Deimos (moon), the smaller and outermost of Mars' two natural satellites Fictional characters * Deimos (comi ...
are rarely referred to as Mars I and Mars II, and the
Moon The Moon is Earth's only natural satellite. It Orbit of the Moon, orbits around Earth at Lunar distance, an average distance of (; about 30 times Earth diameter, Earth's diameter). The Moon rotation, rotates, with a rotation period (lunar ...
is never referred to as "Earth I". However, since 2015 some moons have again been numbered without being named, starting from Jupiter LI. The thirteen named satellites of Saturn from Aegir to Surtur were named in
alphabetical order Alphabetical order is a system whereby character strings are placed in order based on the position of the characters in the conventional ordering of an alphabet. It is one of the methods of collation. In mathematics, a lexicographical order is ...
corresponding to their Roman numerals.


Provisional designations

When satellites are first discovered, they are given provisional designations such as "
S/2010 J 2 Jupiter LII, originally known as , is a natural satellite of Jupiter. It was discovered by Christian Veillet in 2010. It received its permanent number in March 2015. CBET "4075: 20150307: Satellites of Jupiter", March 7, 2015. It takes 1.69 yea ...
" (the 2nd new satellite of Jupiter discovered in 2010) or " S/2003 S 1" (the 1st new satellite of Saturn discovered in 2003). The initial "S/" stands for "satellite", and distinguishes from such prefixes as "D/", "C/", and "P/", used for
comet A comet is an icy, small Solar System body that warms and begins to release gases when passing close to the Sun, a process called outgassing. This produces an extended, gravitationally unbound atmosphere or Coma (cometary), coma surrounding ...
s. The designation "R/" is used for planetary rings. These designations are sometimes written like "S/2003 S1", dropping the second space. The letter following the category and year identifies the planet (Jupiter, Saturn, Uranus, Neptune; although no occurrence of the other planets is expected, Mars and Mercury are disambiguated through the use of Hermes for the latter).
Pluto Pluto (minor-planet designation: 134340 Pluto) is a dwarf planet in the Kuiper belt, a ring of Trans-Neptunian object, bodies beyond the orbit of Neptune. It is the ninth-largest and tenth-most-massive known object to directly orbit the Su ...
was designated by P prior to its
recategorization In social psychology, recategorization is a change in the conceptual representation of a Social group, group or groups. When deliberate, recategorization is often encouraged in order to mitigate bias by making salient a common ingroup identity tha ...
as a
dwarf planet A dwarf planet is a small planetary-mass object that is in direct orbit around the Sun, massive enough to be hydrostatic equilibrium, gravitationally rounded, but insufficient to achieve clearing the neighbourhood, orbital dominance like the ...
. When the object is found around a minor planet, the identifier used is the latter's number in parentheses. Thus, Dactyl, the moon of
243 Ida 243 Ida is an asteroid in the Koronis family of the asteroid belt. It was discovered on 29 September 1884 by Austrian astronomer Johann Palisa at Vienna Observatory and named after Ida (nurse of Zeus), a nymph from Greek mythology. Later telesc ...
, was at first designated " S/1993 (243) 1". Once confirmed and named, it became (243) Ida I Dactyl. Similarly, the fourth satellite of Pluto, Kerberos, discovered after Pluto was categorized as a dwarf planet and assigned a minor planet number, was designated S/2011 (134340) 1 rather than S/2011 P 1, though the ''
New Horizons ''New Horizons'' is an Interplanetary spaceflight, interplanetary space probe launched as a part of NASA's New Frontiers program. Engineered by the Johns Hopkins University Applied Physics Laboratory (APL) and the Southwest Research Institut ...
'' team, who maintained that dwarf planets were planets, used the latter. * H = Mercury (Hermes) * V =
Venus Venus is the second planet from the Sun. It is often called Earth's "twin" or "sister" planet for having almost the same size and mass, and the closest orbit to Earth's. While both are rocky planets, Venus has an atmosphere much thicker ...
* E =
Earth Earth is the third planet from the Sun and the only astronomical object known to Planetary habitability, harbor life. This is enabled by Earth being an ocean world, the only one in the Solar System sustaining liquid surface water. Almost all ...
* M =
Mars Mars is the fourth planet from the Sun. It is also known as the "Red Planet", because of its orange-red appearance. Mars is a desert-like rocky planet with a tenuous carbon dioxide () atmosphere. At the average surface level the atmosph ...
* J =
Jupiter Jupiter is the fifth planet from the Sun and the List of Solar System objects by size, largest in the Solar System. It is a gas giant with a Jupiter mass, mass more than 2.5 times that of all the other planets in the Solar System combined a ...
* S =
Saturn Saturn is the sixth planet from the Sun and the second largest in the Solar System, after Jupiter. It is a gas giant, with an average radius of about 9 times that of Earth. It has an eighth the average density of Earth, but is over 95 tim ...
* U =
Uranus Uranus is the seventh planet from the Sun. It is a gaseous cyan-coloured ice giant. Most of the planet is made of water, ammonia, and methane in a Supercritical fluid, supercritical phase of matter, which astronomy calls "ice" or Volatile ( ...
* N =
Neptune Neptune is the eighth and farthest known planet from the Sun. It is the List of Solar System objects by size, fourth-largest planet in the Solar System by diameter, the third-most-massive planet, and the densest giant planet. It is 17 t ...
Note: The assignation of "H" for Mercury is specified by th
USGS Gazetteer of Planetary Nomenclature
since they usually follow IAU guidelines closely, this is very likely the IAU convention, but confirmation is needed: there have been no moons found to be orbiting Mercury as of yet.
After a few months or years, when a newly discovered satellite's existence has been confirmed and its orbit computed, a permanent name is chosen, which replaces the "S/" provisional designation. However, in the past, some satellites remained unnamed for surprisingly long periods after their discovery.


Timeline

The timeline only includes moons of the planets and the more likely dwarf planets. (no moons), , , , , , , , and (no moons) are generally agreed among astronomers to be dwarf planets. and are more controversial.


Pre-IAU names

The following names were adopted by informal processes preceding the assumption by the
IAU The International Astronomical Union (IAU; , UAI) is an international non-governmental organization (INGO) with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach, education, and developmen ...
of control over the assignment of satellite nomenclature in 1973.


IAU names

The following names were selected through a formal process controlled by the IAU. Only in a few cases is the person who chose the name identified.


20th century


21st century

For completeness, moons that were left unnamed upon their official numbering have also been included.


Other references


Astronomical Headlines





See also

*
Timeline of discovery of Solar System planets and their moons The timeline of discovery of Solar System planets and their natural satellites charts the progress of the discovery of new bodies over history. Each object is listed in chronological order of its discovery (multiple dates occur when the moments o ...
*
Astronomical naming conventions In ancient times, only the Sun and Moon, a few stars, and the most easily visible planets had names. Over the last few hundred years, the number of identified astronomical objects has risen from hundreds to over a billion, and more are discovered ...
*
Provisional designation in astronomy Provisional designation in astronomy is the astronomical naming conventions, naming convention applied to astronomical objects immediately following their discovery. The provisional designation is usually superseded by a permanent designation onc ...
*
Planetary nomenclature Planetary nomenclature, like terrestrial nomenclature, is a system of uniquely identifying features on the surface of a planet or natural satellite so that the features can be easily located, described, and discussed. Since the invention of the ...
*
Name conflicts of solar system objects There are several real or apparent name conflicts between different Solar System bodies, in spite of efforts to give every named body a distinct name. Most of these conflicts are between asteroids and natural satellites of planets, which are named ...


Notes

{{DEFAULTSORT:Naming Of Moons Moons *
Moons A natural satellite is, in the most common usage, an astronomical body that orbits a planet, dwarf planet, or small Solar System body (or sometimes another natural satellite). Natural satellites are colloquially referred to as moons, a deriva ...