Naming of moons

Last updated

The naming of moons has been the responsibility of the International Astronomical Union's committee for Planetary System Nomenclature since 1973. That committee is known today as the Working Group for Planetary System Nomenclature (WGPSN).

Contents

Prior to its formation, the names of satellites 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 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. [1] Since then, names have been given to 137 additional planetary and dwarf planetary satellites: 52 satellites of Jupiter, 43 of Saturn, 22 of Uranus, 12 of Neptune, 5 of Pluto, 2 of Haumea, and 1 each of Eris, Gonggong, Quaoar, and Orcus. Names have also been given to some satellites of minor planets, including the dwarf planet candidates Salacia and Varda 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, [2] the WGPSN suggested it may become advisable to not name small satellites, as CCD technology makes it possible to discover satellites as small as 1 km in diameter. Until 2013, names were applied to all planetary moons discovered, regardless of size. Since then, 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, 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-fictional contexts, the Moon has been called by the Latin name Luna, presumably on the analogy of the Latin names of the planets, or by association with the adjectival form lunar. In technical terminology, the word-stems seleno- (from Greek selēnē "moon") and cynthi- (from Cynthia, an epithet of the goddess Artemis) are sometimes used to refer to the Moon, as in selenography, selenology, and pericynthion.

Mars

The moons of Mars (Phobos and Deimos) were named by Asaph Hall in 1878, soon after he discovered them. They are named after the sons of the god Ares (the Greek equivalent of the Roman god Mars).

Jupiter

The Galilean moons of Jupiter (Io, Europa, Ganymede and Callisto) 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. [3] [ dubious ] By a popular though unofficial convention,[ citation needed ] Jupiter V, discovered in 1892, was given the name Amalthea, [4] first used by the French astronomer Camille Flammarion. [5]

The other irregular satellites (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. [6] Although the 1955 names met with immediate acceptance in some quarters (e.g. in science fiction [7] and popular science articles [8] ), they were still rarely if ever met in astronomical literature until the 1970s. [9]

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). [10] [11] These met no particularly enthusiastic reception.

In 1975, following Charles Kowal's discovery of the satellite Jupiter XIII in 1974 the IAU 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 where prograde moons received names ending in 'a' and retrograde moons received names ending in 'e'. [12]

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. [13] Carl Sagan noted that the names chosen were extraordinarily obscure (a fact that Tobias Owen, chair of the Task Group, admitted was intentional in a response to Sagan [10] ) and suggested his own names in 1976; [14] 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. [15]

The proposals are summarized in the table below (data from Icarus unless specified otherwise [10] [14] ):

Number1955 Proposal
Brian Marsden [6]
1962 Proposal
E. I. Nesterovich [16]
1973 Proposal
Yu. A. Karpenko [11]
1975 Proposal
IAU Committee [10]
1976 Proposal
Carl Sagan [14]
Jupiter VI Hestia Atlas Adrastea Himalia Maia
Jupiter VII Hera Hercules Danae Elara Hera
Jupiter VIII Poseidon Persephone Helen Pasiphae Alcmene
Jupiter IX Hades Cerberus Ida Sinope Leto
Jupiter X Demeter Prometheus Latona Lysithea Demeter
Jupiter XI Pan Dedalus Leda Carme Semele
Jupiter XII Adrastea Hephaestus Semele Ananke Danae

Current practice is that newly discovered moons of Jupiter must be named after lovers or descendants of the mythological Jupiter (Zeus). 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, [2] the WGPSN allowed Jovian satellites to be named for Zeus' 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) 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 were named by John Herschel. Herschel named Saturn's two innermost moons (Mimas and Enceladus) after the mythological Greek Giants, and the outer five after the Titans (Titan, Iapetus) and Titanesses (Tethys, Dione, Rhea) of the same mythology. Until then, Titan 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 was suggested by its discoverer, Audouin Dollfus.

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, [2] 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 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' 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. [17] 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). [18] With the confirmation of Ariel and Umbriel, Lassell numbered the moons I through IV from Uranus outward, and this finally stuck. [19]

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

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, after a thoroughly mortal character in Shakespeare's The Tempest . 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, is named from Much Ado About Nothing .

Neptune

The one known moon (at the time) of Neptune was not named for many decades. Although the name Triton was suggested in 1880 by Camille Flammarion, 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, was named by its discoverer in 1949, Gerard P. Kuiper, 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. [20]

Pluto

Pluto and its five moons. Pluto and its five moons.jpg
Pluto and its five moons.

The name of Pluto's moon Charon was suggested by James W. Christy, its discoverer, soon after its discovery.

The other four moons are named Hydra, Nix, Kerberos, and Styx.

Charon, Hydra, Nix, and Kerberos are all characters in Greek mythology, with ties to Hades (the Greek equivalent of Pluto). Charon ferries the dead across the River Acheron, Hydra guards the waters of the underworld, and Nix (a respelling of Nyx), 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 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, 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 who plays the character Xena. 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. [22] 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 and its moons were suggested by David L. Rabinowitz of Caltech 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. [23] Xiangliu's name was chosen by its discovery team led by Csaba Kiss, who had the privilege of naming the satellite. [24]

Quaoar

Quaoar was named after the creator god of the Tongva 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, son of Quaoar. [25]

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 (IAU) on 5 April. [26] The name Vanth, the winged Etruscan psychopomp 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. [27]

The Etruscan Vanth is frequently portrayed in the company of Charun (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 Pluto. 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. [27]

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:

Name of moonName of primaryRoman numeral
Dactyl 243 Ida I
Echidna 42355 Typhon I
Linus 22 Kalliope I
Menoetius 617 Patroclus I
Petit-Prince 45 Eugenia I
Phorcys 65489 Ceto I
Remus 87 Sylvia II
Romulus 87 Sylvia I
Sawiskera 88611 Teharonhiawako I
Zoe 58534 Logos I

Roman numeral designations

The Roman numbering system for satellites arose with the very first discovery of natural satellites other than Earth's Moon: Galileo referred to the Galilean moons 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., [28] 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); 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.

Roman numerals are usually not assigned to satellites until they are named, so many satellites that have been discovered but only have provisional designations do not usually have Roman numerals assigned to them. (An exception is Saturn's moon Helene, which received the Roman numeral XII in 1982, but was not named until 1988.) While the International Astronomical Union was assigning names to all satellites from 1975 to 2013, the use of Roman numeral designations diminished, and some are very rarely used; Phobos and Deimos are rarely referred to as Mars I and Mars II, and the Moon is never referred to as "Earth I". However, some of the more recently discovered moons have not been named even after their orbital elements were known well enough to receive Roman numerals, and as such the only possible nomenclature for them is their Roman numeral designations; the first of these unnamed but numbered moons was Jupiter LI.

The thirteen named satellites of Saturn from Aegir to Surtur were named in alphabetical order corresponding to their Roman numerals.

Provisional designations

When satellites are first discovered, they are given provisional designations such as "S/2010 J 2" (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 comets. 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 was designated by P prior to its recategorization as a dwarf planet. 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, 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, [29] though the New Horizons team, who maintained that dwarf planets were planets, used the latter.

Note: The assignation of "H" for Mercury is specified by the 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. Ceres (no moons), Orcus, Pluto, Haumea, Quaoar, Makemake, Gonggong, Eris, and Sedna (no moons) are generally agreed among astronomers to be dwarf planets. Salacia and Varda are more controversial.

Pre-IAU names

The following names were adopted by informal processes preceding the assumption by the IAU of control over the assignment of satellite nomenclature in 1973.

Pre-IAU Names
DateNamerNameImagePlanet/Number DesignationDiscovery dateReferences/Notes
17th century
1614 Simon Marius Io
Io highest resolution true color.jpg
Jupiter I1610Marius (Simon Mayr), in his book Mundus Iovialis anno M.DC.IX Detectus Ope Perspicilli Belgici, names the Galilean moons, and attributes the suggestion to Johannes Kepler.
Europa
Europa-moon.jpg
Jupiter II
Ganymede
Ganymede - Perijove 34 Composite.png
Jupiter III
Callisto
Callisto.jpg
Jupiter IV
19th century
1847 John Herschel Mimas
Mimas Cassini.jpg
Saturn I1789Herschel named the seven known satellites of Saturn in his book Results of Astronomical Observations made at the Cape of Good Hope, as reported by William Lassell, Monthly Notices of the Royal Astronomical Society, Vol. 8, No. 3, pp. 42–43 January 14, 1848
Enceladus
PIA17202 - Approaching Enceladus.jpg
Saturn II
Tethys
PIA18317-SaturnMoon-Tethys-Cassini-20150411.jpg
Saturn III1684
Dione
Dione in natural light.jpg
Saturn IV
Rhea
PIA07763 Rhea full globe5.jpg
Saturn V1672
Titan
Titan in true color.jpg
Saturn VI1655
Iapetus
Iapetus as seen by the Cassini probe - 20071008.jpg
Saturn VIII1671
1848 William Lassell Hyperion
Hyperion true.jpg
Saturn VII1847Lassell, following John Herschel's suggested scheme, names Hyperion Discovery of a New Satellite of Saturn, Monthly Notices of the Royal Astronomical Society, Vol. 8, No. 9, pp. 195–197.
1852 John Herschel Ariel
Ariel (moon).jpg
Uranus I1851Herschel named the four known satellites of Uranus in Astronomische Nachrichten , Vol. 34, No. 812, pp. 325/326, 21 June 1852 (communication dated 26 May 1852.)
Umbriel
PIA00040 Umbrielx2.47.jpg
Uranus II
Titania
Titania (moon) color cropped.jpg
Uranus III1787
Oberon
Voyager 2 picture of Oberon.jpg
Uranus IV
1878 Asaph Hall Phobos
Phobos colour 2008.jpg
Mars I1877Hall named his two newly discovered satellites of Mars Phobus and Deimus: Astronomische Nachrichten, Vol. 92, No. 2187, pp. 47/48 14 March 1878 (signed 7 February 1878). The names were subsequently amended to Phobos and Deimos.
Deimos
Deimos-MRO.jpg
Mars II
1880 Camille Flammarion Triton
Triton moon mosaic Voyager 2 (large).jpg
Neptune I1846Flammarion suggested the name Triton in his 1880 book Astronomie populaire, p. 591. The name was considered unofficial for decades afterwards.
c. 1893 Camille Flammarion Amalthea
Amalthea.gif
Jupiter V1892Flammarion suggested the name Amalthea in correspondence with discoverer E. E. Barnard. Barnard declined to propose any name, however, and Amalthea remained an unofficial name until its adoption by the IAU in 1975.
April 1899 William Henry Pickering Phoebe
Phoebe cassini.jpg
Saturn IX1899Pickering suggested the name Phoebe in A New Satellite of Saturn, Astrophysical Journal, Vol. 9, No. 4, pp. 274–276, April 1899, by his brother Edward C. Pickering.
20th century
April 1939 Seth Barnes Nicholson declines to name satellites of Jupiter he has discovered (Publications of the Astronomical Society of the Pacific, Vol. 51, No. 300, pp. 85–94, signed March 1939)
June 1949 Gerard P. Kuiper Miranda
Miranda.jpg
Uranus V1948Kuiper proposed the name Miranda in his report of the discovery, The Fifth Satellite of Uranus, Publications of the Astronomical Society of the Pacific, Vol. 61, No. 360, p. 129, June 1949.
August 1949 Gerard P. Kuiper Nereid
Nereid-Voyager2.jpg
Neptune II1949Kuiper proposed the name Nereid in his report of the discovery, The second satellite of Neptune, Publications of the Astronomical Society of the Pacific, Vol. 61, No. 361, pp. 175–176, August 1949.
1 February 1967 Audouin Dollfus Janus
PIA12714 Janus crop.jpg
Saturn X1966Dollfus named Janus in a report of 1 February 1967 relating to its discovery (IAUC 1995: Saturn X (Janus)).

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

IAU Names - 20th century
DateNameImagePlanet/Number DesignationDiscovery dateReferences/Notes
7 October 1975 Himalia Cassini-Huygens Image of Himalia.png Jupiter VI1904 IAUC 2846: Satellites of Jupiter. Also confirmed the name Amalthea.
Elara Elara - New Horizons.png Jupiter VII1905
Pasiphaë Pasiphae.jpg Jupiter VIII1908
Sinope Sinope.jpg Jupiter IX1914
Lysithea Lysithea2.jpg Jupiter X1938
Carme Carme.jpg Jupiter XI
Ananke Ananke.jpg Jupiter XII1951
Leda Leda WISE-W3.jpg Jupiter XIII1974
1982 Thebe
Thebe.jpg
Jupiter XIV1979 Transactions of the International Astronomical Union, Vol. XVIIIA, 1982. Mentioned in IAUC 3872 (in 1983). Also confirmed the name Janus. Saturn XII was also numbered at this time, but left unnamed as "Dione B". In the 1982 announcement Thebe and Adrastea were mistakenly swapped.
Adrastea
Adrastea.jpg
Jupiter XV
Metis
Metis.jpg
Jupiter XVI
Epimetheus PIA09813 Epimetheus S. polar region.jpg Saturn XI1980
Telesto
Telesto cassini closeup.jpg
Saturn XIII
Calypso
N00151485 Calypso crop.jpg
Saturn XIV
30 September 1983 Atlas
Atlas 2017-04-12 raw preview.jpg
Saturn XV1980 IAUC 3872: Satellites of Jupiter and Saturn
3 January 1986 Prometheus
Prometheus 12-26-09a.jpg
Saturn XVI IAUC 4157: Satellites of Saturn and Pluto
Pandora
PIA21055 - Pandora Up Close.jpg
Saturn XVII
3 January 1986 Charon
Charon in True Color - High-Res.jpg
Pluto I1978 IAUC 4157: Satellites of Saturn and Pluto. James W. Christy announced the name Charon shortly after his discovery of the satellite in 1978, but the name remained unofficial until its adoption by the IAU in 1986.
8 June 1988
(numbered 1982)
Helene
PIA12758 Helene crop.jpg
Saturn XII1980 IAUC 4609: Satellites of Saturn and Uranus
8 June 1988 Cordelia
Cordeliamoon.png
Uranus VI1986 IAUC 4609: Satellites of Saturn and Uranus
Ophelia
Opheliamoon.png
Uranus VII
Bianca
Biancamoon.png
Uranus VIII
Cressida
Cressida.png
Uranus IX
Desdemona
Desdemonamoon.png
Uranus X
Juliet
Julietmoon.png
Uranus XI
Portia
Portia1.jpg
Uranus XII
Rosalind
Rosalindmoon.png
Uranus XIII
Belinda
Belinda.gif
Uranus XIV
Puck
Puck.png
Uranus XV1985
16 September 1991 Pan
Pan by Cassini, March 2017.jpg
Saturn XVIII1990 IAUC 5347: Satellites of Saturn and Neptune
16 September 1991 Naiad
Naiad Voyager.png
Neptune III1989 IAUC 5347: Satellites of Saturn and Neptune
Thalassa
Neptune Trio.jpg
Neptune IV
Despina
Despina.jpg
Neptune V
Galatea
Galatea moon.jpg
Neptune VI
Larissa
Larissa 1.jpg
Neptune VII
Proteus
Proteus (Voyager 2).jpg
Neptune VIII
30 April 1998 Caliban
Caliban discovery.jpg
Uranus XVI1997B. J. Gladman, P. D. Nicholson, J. A. Burns, J. J. Kavelaars, B. G. Marsden, G. V. Williams and W. B. Offutt propose the names Caliban and Sycorax in their account of the discovery: Gladman, B. J.; Nicholson, P. D.; Burns, J. A.; Kavelaars, J. J.; Marsden, B. G.; Williams, G. V.; Offutt, W. B. (1998). "Discovery of two distant irregular moons of Uranus". Nature. 392 (6679): 897–899. Bibcode:1998Natur.392..897G. doi:10.1038/31890. S2CID   4315601.. IAUC 7132: Satellites of Uranus (The IAU appears to have adopted these names prior to those reported in IAUC 7479.)
Sycorax
Uranus-sycorax2.gif
Uranus XVII
21 August 2000 Prospero
Prospero - Uranus moon.jpg
Uranus XVIII1999 IAUC 7479: Satellites of Uranus
Setebos
Uranus - Setebos image.jpg
Uranus XIX
Stephano
Stephano - Uranus moon.jpg
Uranus XX

21st century

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

IAU Names - 21st century
DateNameImagePlanet/Number DesignationDiscovery dateReferences/Notes
22 October 2002 Callirrhoe
Callirrhoe - New Horizons.gif
Jupiter XVII1999 IAUC 7998: Satellites of Jupiter
Themisto
S 2000 J 1.jpg
Jupiter XVIII2000
Megaclite
Megaclite-Jewitt-CFHT-annotated.gif
Jupiter XIX2001Spelled "Magaclite" in IAUC 7998; corrected 29 November 2002 in IAUC 8023: Satellites of Jupiter.
Taygete
Taygete-Jewitt-CFHT-annotated.gif
Jupiter XX IAUC 7998: Satellites of Jupiter
Chaldene
Chaldene-Jewitt-CFHT-annotated.gif
Jupiter XXI
Harpalyke
Harpalyke-Jewitt-CFHT-annotated.gif
Jupiter XXII2000
Kalyke
Kalyke-Jewitt-CFHT-annotated.gif
Jupiter XXIII2001
Iocaste
Iocaste-Jewitt-CFHT-annotated.gif
Jupiter XXIV
Erinome
Erinome-Jewitt-CFHT-annotated.gif
Jupiter XXV
Isonoe
Isonoe-Jewitt-CFHT-annotated.gif
Jupiter XXVI
Praxidike
Praxidike-Jewitt-CFHT-annotated.gif
Jupiter XXVII
8 August 2003 Autonoe
Autonoe-discovery-CFHT-annotated.gif
Jupiter XXVIII2002 IAUC 8177: Satellites of Jupiter, Saturn, Uranus
Thyone
Thyone-discovery-CFHT-annotated.gif
Jupiter XXIX
Hermippe
Hermippe-discovery.gif
Jupiter XXX
Aitne
Aitne-discovery-CFHT-annotated.gif
Jupiter XXXI
Eurydome
Eurydome-discovery-CFHT-annotated.gif
Jupiter XXXII
Euanthe
Euanthe-discovery-CFHT-annotated.gif
Jupiter XXXIII
Euporie
Euporie-discovery-CFHT-annotated.gif
Jupiter XXXIV
Orthosie
Orthosie-discovery-CFHT-annotated.gif
Jupiter XXXV
Sponde
Sponde-discovery-CFHT-annotated.gif
Jupiter XXXVI
Kale
Kale-discovery-CFHT-annotated.gif
Jupiter XXXVII
Pasithee
Pasithee-discovery-CFHT-annotated.gif
Jupiter XXXVIII
8 August 2003 Ymir
Ymir-CFHT.gif
Saturn XIX2000 IAUC 8177: Satellites of Jupiter, Saturn, Uranus
Paaliaq
Paaliaq-CFHT.gif
Saturn XX
Tarvos
Tarvos discovery.gif
Saturn XXI
Ijiraq
Ijiraq-discovery-CFHT.gif
Saturn XXII
Suttungr
Suttungr-discovery-CFHT.gif
Saturn XXIIISpelled "Suttung" in IAUC 8177; emended on 21 January 2005 in IAUC 8471: Satellites of Saturn.
Kiviuq
Kiviuq-CFHT.gif
Saturn XXIV IAUC 8177: Satellites of Jupiter, Saturn, Uranus
Mundilfari
Mundilfari-discovery-CFHT.gif
Saturn XXV
Albiorix
Albiorix WISE-W4.jpg
Saturn XXVI
Skathi
Skathi-discovery-CFHT.gif
Saturn XXVIISpelled "Skadi" in IAUC 8177; emended on 21 January 2005 in IAUC 8471: Satellites of Saturn.
Erriapus
Erriapus-discovery-CFHT.gif
Saturn XXVIIISpelled "Erriapo" in IAUC 8177; corrected on 14 December 2007 (USGS)
Siarnaq
Siarnaq-discovery-CFHT.gif
Saturn XXIX IAUC 8177: Satellites of Jupiter, Saturn, Uranus
Thrymr
Thrymr-discovery-CFHT.gif
Saturn XXXSpelled "Thrym" in IAUC 8177; emended on 21 January 2005 in IAUC 8471: Satellites of Saturn.
8 August 2003 Trinculo Uranus XXI2002 IAUC 8177: Satellites of Jupiter, Saturn, Uranus
21 January 2005 Narvi
Narvi.jpg
Saturn XXXI2003 IAUC 8471: Satellites of Saturn
Methone
Methone PIA14633.jpg
Saturn XXXII2004
Pallene
Pallene N1665945513 1.jpg
Saturn XXXIII
Polydeuces
Polydeuces.jpg
Saturn XXXIV
30 March 2005 Hegemone Jupiter XXXIX2003 IAUC 8502: Satellites of Jupiter
Mneme
Mneme Discovery Image.jpg
Jupiter XL
Aoede Jupiter XLI
Thelxinoe Jupiter XLII
Arche
Bigs2002j1barrow.png
Jupiter XLIII2002
Kallichore Jupiter XLIV2003
Helike
Helike CFHT 2003-02-25 annotated.gif
Jupiter XLV
Carpo
Carpo CFHT 2003-02-25.gif
Jupiter XLVI
Eukelade
Eukelade s2003j1movie arrow.gif
Jupiter XLVII
Cyllene Jupiter XLVIII
29 December 2005 Francisco Uranus XXII2006 IAUC 8648: Satellites of Uranus
Margaret
S2003u3acircle.gif
Uranus XXIII
Ferdinand
Uranus moon 021002 02.jpg
Uranus XXIV
Perdita
Perditamoon.png
Uranus XXV
Mab
Mabmoon.png
Uranus XXVI
Cupid
Cupidmoon.png
Uranus XXVII
21 June 2006 Nix
Nix best view.jpg
Pluto II2005 IAUC 8723: Satellites of Pluto
Hydra
Hydra Enhanced Color.jpg
Pluto III
17 July 2006 Daphnis
Daphnis (Saturn's Moon).jpg
Saturn XXXV2005 IAUC 8730: Saturn XXXV (Daphnis) = S/2005 S 1
13 September 2006 Dysnomia
Eris and dysnomia2.jpg
Eris I2005 IAUC 8747: (134340) Pluto, (136199) Eris, and (136199) Eris I (Dysnomia)
3 February 2007 Halimede
N2002n1b.jpg
Neptune IX2002 IAUC 8802: Satellites of Neptune
Psamathe
S2003n1c.jpg
Neptune X2003
Sao
Sao VLT-FORS1 2002-09-03 annotated.gif
Neptune XI2002
Laomedeia
Laomedeia VLT-FORS1 2002-09-03.gif
Neptune XII
Neso
Neso VLT-FORS1 2002-09-03.gif
Neptune XIII
5 April 2007 Kore
Kore s2003j14movie circled.gif
Jupiter XLIX2003 IAUC 8826: Satellites of Jupiter and Saturn
5 April 2007 Aegir Saturn XXXVI2004 IAUC 8826: Satellites of Jupiter and Saturn
Bebhionn
Bebhionn-cassini.png
Saturn XXXVII
Bergelmir
Bergelmir.png
Saturn XXXVIII
Bestla
Bestla-cassini.png
Saturn XXXIX
Farbauti Saturn XL
Fenrir Saturn XLI
Fornjot
Fornjot-cassini.png
Saturn XLII
Hati
Hati-cassini.png
Saturn XLIII
Hyrrokkin
Hyrrokkin-cassini.png
Saturn XLIVSpelled "Hyrokkin" in IAUC 8826; corrected on 31 July 2007 in IAUC 8860: Saturn XLIV (Hyrrokkin)
Kari
Kari-cassini.png
Saturn XLV2006 IAUC 8826: Satellites of Jupiter and Saturn
Loge
Loge N00177425.jpg
Saturn XLVI
Skoll Saturn XLVII
Surtur Saturn XLVIII
20 September 2007 Anthe
Anthe crop.jpg
Saturn XLIX2007 IAUC 8873: Satellites of Saturn
Jarnsaxa Saturn L2006
Greip
Greip-cassini.png
Saturn LI
Tarqeq
Tarqeq-cassini.png
Saturn LII2007
17 September 2008 Hiʻiaka
Haumea Hubble.png
Haumea I2005
Namaka
Haumea Hubble.png
Haumea II2005
5 May 2009 Aegaeon
N1643264379 1.jpg
Saturn LIII2009 IAUC 9041: New name/designation of satellite of Saturn (LIII), S/2008 S 1. (subscription only)
4 October 2009 Weywot
Quaoar-weywot hst.jpg
Quaoar I2006 MPC 67220: New Names of Minor Planets
11 November 2009 Herse Jupiter L2003 IAUC 9094: Designation and name assigned to S/2003 J 17 (the 50th satellite of Jupiter to be so designated and named): Jupiter L (Herse). (subscription only)
30 March 2010 Vanth
Orcus-Vanth 10801.jpg
Orcus I2005 MPC 69496: New Names of Minor Planets
18 February 2011 Actaea
Salacia Hubble.png
Salacia I2006 MPC 73984: New Names of Minor Planets
2 July 2013 Kerberos
Kerberos (moon).jpg
Pluto IV2011 IAU1303 News Release
Styx
Styx (moon).jpg
Pluto V2012
16 January 2014 Ilmarë
Varda-ilmare hst.jpg
Varda I2009 MPC 86715: New Names of Minor Planets
7 March 2015(unnamed)
2010 J 1 CFHT image.gif
Jupiter LI 2010 CBET (Central Bureau Electronic Telegram) 4075: 20150307: Satellites of Jupiter, March 7, 2015 (subscription only)
2010 J 2 CFHT discovery full.gif
Jupiter LII 2010
Dia
Dia-Jewitt-CFHT image-crop.png
Jupiter LIII2000
9 June 2017 (numbered)
19 August 2019 (named)
(unnamed)
2016 J 1 CFHT 2003-02-26 annotated.gif
Jupiter LIV 2016 MPC 105280: Numbering of Natural Satellites
Names Approved for Five Jovian Satellites
2003 J 18 CFHT recovery full.gif
Jupiter LV 2003
Jupiter LVI 2011
Eirene Jupiter LVII2003
Philophrosyne Jupiter LVIII2003
(unnamed)
2017 J 1 CFHT precovery full.gif
Jupiter LIX 2017
5 October 2017 (numbered)
19 August 2019 (named)
Eupheme
Eupheme CFHT 2003-02-25 annotated.gif
Jupiter LX2003 MPC 106505: Numbering of a Natural Satellite
Names Approved for Five Jovian Satellites
25 September 2018 (numbered)
3 October 2018 (named)
(unnamed) Jupiter LXI 2003 MPC 111804: Numbering of Natural Satellites
Name Approved for Jovian Satellite: Valetudo
Names Approved for Five Jovian Satellites
Name Approved for Neptunian Satellite: Hippocamp
Valetudo
Valetudo CFHT precovery 2003-02-28 annotated.gif
Jupiter LXII2016
25 September 2018 (numbered)
19 August 2019 (named)
(unnamed)
2017 J 2 CFHT 2003-02-26 annotated.gif
Jupiter LXIII 2017
2017 J 3 CFHT 2003-12-25 annotated.gif
Jupiter LXIV
Pandia
Pandia CFHT precovery 2003-02-28.png
Jupiter LXV
(unnamed) Jupiter LXVI
Jupiter LXVII
Jupiter LXVIII
2017 J 8 CFHT precovery full.gif
Jupiter LXIX
Jupiter LXX
Ersa
Ersa CFHT precovery 2003-02-24.png
Jupiter LXXI2018
(unnamed) Jupiter LXXII 2011
25 September 2018 (numbered)
20 February 2019 (named)
Hippocamp
Hippocamp-heic1904b.jpg
Neptune XIV2013
5 February 2020 Xiangliu
Xiangliu orbiting 225088 Gonggong (2010, cropped).jpg
Gonggong I2016 MPC 121135: New Names of Minor Planets
1 June 2021 (numbered)(unnamed) Saturn LIV 2019 MPC 132212: Numbering of a Natural Satellite
10 August 2021 (numbered) Saturn LV MPC 133821: Numbering of Natural Satellites
Saturn LVI
Saturn LVII
Saturn LVIII
Saturn LIX
Saturn LX
Saturn LXI
Saturn LXII
Saturn LXIII
Saturn LXIV
Saturn LXV
Saturn LXVI

Other references

See also

Notes

  1. The Moon; Phobos and Deimos; Io, Europa, Ganymede, Callisto, and Amalthea; Mimas, Enceladus, Tethys, Dione, Rhea, Titan, Hyperion, Iapetus, Phoebe and Janus; Ariel, Umbriel, Titania, Oberon and Miranda; Triton and Nereid.
  2. 1 2 3 Archived October 9, 2004, at the Wayback Machine
  3. Nicholson, Seth Barnes (April 1939). "The Satellites of Jupiter". Publications of the Astronomical Society of the Pacific. 51 (300): 85–94. Bibcode:1939PASP...51...85N. doi: 10.1086/125010 .
  4. Barnard, E. E. (1893). "Jupiter's fifth satellite". Popular Astronomy (1): 76–82.
  5. USGS Astrogeology Research Program, Gazetteer of Planetary Nomenclature
  6. 1 2 Marsden, Brian (1955). "Satellite Nomenclature". Journal of the British Astronomical Association. 65: 308–310.
  7. Asimov, Isaac (1957). Lucky Starr and the Moons of Jupiter . Doubleday & Co. ISBN   0-553-29682-5.
  8. Asimov, Isaac (December 1963). "Roll Call". The Magazine of Fantasy and Science Fiction .
  9. Payne-Gaposchkin, Cecilia; Katherine Haramundanis (1970). Introduction to Astronomy. Englewood Cliffs, N.J.: Prentice-Hall. ISBN   0-13-478107-4.
  10. 1 2 3 4 Owen, Tobias (September 1976). "Jovian Satellite Nomenclature". Icarus. 29 (1): 159–163. Bibcode:1976Icar...29..159O. doi:10.1016/0019-1035(76)90113-5.
  11. 1 2 Журнал "Земля и Вселенная" №6 1973 г
  12. "IAUC 2846: N Mon 1975 (= A0620-00); N Cyg 1975; 1975h; 1975g; 1975i; Sats OF JUPITER". Cbat.eps.harvard.edu. Retrieved 2011-11-06.
  13. Kowal, Charles T. (December 1976). "The Case Against Names". Icarus. 29 (4): 513. Bibcode:1976Icar...29..513K. doi:10.1016/0019-1035(76)90071-3.
  14. 1 2 3 Sagan, Carl (April 1976). "On Solar System Nomenclature". Icarus. 27 (4): 575–576. Bibcode:1976Icar...27..575S. doi:10.1016/0019-1035(76)90175-5.
  15. Ю. А. Карпенко, "Названия звёздного неба", 1981. pp. 94-96
  16. Nesterovich, E. I. (1962). "On some regularities in structure of systems of planetary satellites". Bulletin of VAGO (Astronomical-Geodetical Society of the U.S.S.R.). 31 (38): 51–56.
  17. Herschel, J.; On the Satellites of Uranus, Monthly Notices of the Royal Astronomical Society, Vol. 3, No. 5 (March 14, 1834) pp. 35–36
  18. Lassell, W.; Observations of Satellites of Uranus, Monthly Notices of the Royal Astronomical Society, Vol. 8, No. 3 (January 14, 1848), pp. 43–44
  19. Lassell, W.; Letter from William Lassell, Esq., to the Editor, Astronomical Journal, Vol. 2, No. 33 (signed November 11, 1851), p. 70
  20. M. Antonietta Barucci; Hermann Boehnhardt; Dale P. Cruikshank; Alessandro Morbidelli, eds. (2008). "Irregular Satellites of the Giant Planets" (PDF). The Solar System Beyond Neptune. p. 414. ISBN   9780816527557. Archived from the original (PDF) on 2017-08-10. Retrieved 2017-07-22.
  21. "Names for New Pluto Moons Accepted by the IAU After Public Vote". IAU Press Release. Retrieved 7 July 2013.
  22. Tytell, David (2006-09-14). "Tytell, David: All hail Eris and Dysnomia". Skyandtelescope.com. Archived from the original on 2012-05-27. Retrieved 2011-11-06.
  23. "Astronomers Invite the Public to Help Name Kuiper Belt Object". International Astronomical Union. 10 April 2019. Retrieved 12 May 2019.
  24. Schwamb, M. (29 May 2019). "The People Have Voted on 2007 OR10's Future Name!". The Planetary Society. Retrieved 29 May 2019.
  25. "Heavenly Bodies and the People of the Earth", Nick Street, Search Magazine, July/August 2008
  26. Michael E. Brown (23 March 2009). "S/1 90482 (2005) needs your help". Mike Brown's Planets (blog). Archived from the original on 28 March 2009. Retrieved 25 March 2009.
  27. 1 2 Michael E. Brown (6 April 2009). "Orcus Porcus". Mike Brown's Planets (blog). Archived from the original on 14 April 2009. Retrieved 6 April 2009.
  28. Herschel, William (1 January 1790). "Account of the Discovery of a Sixth and Seventh Satellite of the Planet Saturn; With Remarks on the Construction of Its Ring, Its Atmosphere, Its Rotation on an Axis, and Its Spheroidical Figure. By William Herschel, LL.D. F. R. S". Philosophical Transactions of the Royal Society of London. 80: 1–20. Bibcode:1790RSPT...80....1H. doi: 10.1098/rstl.1790.0001 . JSTOR   106823.
  29. http://www.cbat.eps.harvard.edu/cbet/cbet002769.txt

Related Research Articles

Double planet A binary system where two planetary-mass objects share an orbital axis external to both

In astronomy, a double planet is a binary satellite system where both objects are planets, or planetary-mass objects, that share an orbital axis external to both planetary bodies.

Planet Class of astronomical body directly orbiting a star or stellar remnant

A planet is an astronomical body orbiting a star or stellar remnant that is massive enough to be rounded by its own gravity, is not massive enough to cause thermonuclear fusion, and – according to the International Astronomical Union but not all planetary scientists – has cleared its neighbouring region of planetesimals.

Solar System The Sun, its planets and their moons

The Solar System is the gravitationally bound system of the Sun and the objects that orbit it, either directly or indirectly. Of the objects that orbit the Sun directly, the largest are the eight planets, with the remainder being smaller objects, the dwarf planets and small Solar System bodies. Of the objects that orbit the Sun indirectly—the natural satellites—two are larger than the smallest planet, Mercury, and one more almost equals it in size.

Natural satellite Astronomical body that orbits a planet

A natural satellite is in the most common usage, an astronomical body that orbits a planet, dwarf planet, or small solar system body. While natural satellites are often colloquially referred to as moons, there is only the Moon of Earth.

Timeline of Solar System astronomy Timeline of the history of Solar System astronomy

The following is a timeline of Solar System astronomy.

90482 Orcus Trans-Neptunian object and dwarf planet

Orcus is a trans-Neptunian dwarf planet with a large moon, Vanth. It has a diameter of 910 km (570 mi). The surface of Orcus is relatively bright with albedo reaching 23 percent, neutral in color and rich in water ice. The ice is predominantly in crystalline form, which may be related to past cryovolcanic activity. Other compounds like methane or ammonia may also be present on its surface. Orcus was discovered by American astronomers Michael Brown, Chad Trujillo, and David Rabinowitz on 17 February 2004.

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, identified through its various designations, and the discoverer(s) listed. Historically the naming of moons did not always match the times of their discovery. Traditionally, the discoverer enjoys the privilege of naming the new object; however, some neglected to do so or actively declined. The issue arose nearly as soon as planetary satellites were discovered: Galileo referred to the four main satellites of Jupiter using numbers while the names suggested by his rival Simon Marius gradually gained universal acceptance. The International Astronomical Union (IAU) eventually started officially approving names in the late 1970s.

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 every year. Astronomers need to be able to assign systematic designations to unambiguously identify all of these objects, and at the same time give names to the most interesting objects, and where relevant, features of those objects.

Definition of <i>planet</i> History of the word "planet" and its definition

The definition of planet, since the word was coined by the ancient Greeks, has included within its scope a wide range of celestial bodies. Greek astronomers employed the term asteres planetai, "wandering stars", for star-like objects which apparently moved over the sky. Over the millennia, the term has included a variety of different objects, from the Sun and the Moon to satellites and asteroids.

Dysnomia (moon) Moon of Eris

Dysnomia (formally (136199) Eris I Dysnomia) is the only known moon of the dwarf planet Eris and likely the second-largest known moon of a dwarf planet, after Pluto I Charon. It was discovered in 2005 by Mike Brown and the laser guide star adaptive optics team at the W. M. Keck Observatory, and carried the provisional designation of S/2005 (2003 UB313) 1 until officially named Dysnomia (from the Ancient Greek word Δυσνομία meaning anarchy/lawlessness) after the daughter of the Greek goddess Eris.

Dwarf planet Planetary-mass object

A dwarf planet is a small planetary-mass object that is in direct orbit of the Sun – something smaller than any of the eight classical planets, but still a world in its own right. The prototypical dwarf planet is Pluto. The interest of dwarf planets to planetary geologists is that, being possibly differentiated and geologically active bodies, they may display planetary geology, an expectation borne out by the Dawn mission to Ceres and the New Horizons mission to Pluto in 2015.

IAU definition of <i>planet</i> Formal definition of a planet in the context of the Solar System as ratified by the IAU in 2006

The International Astronomical Union (IAU) defined in August 2006 that, in the Solar System, a planet is a celestial body that:

  1. is in orbit around the Sun,
  2. has sufficient mass to assume hydrostatic equilibrium, and
  3. has "cleared the neighbourhood" around its orbit.
Astrological symbols Symbols denoting astrological concepts

Symbols used in astrology overlap with those used in astronomy because of the historical overlap between the two subjects. Frequently used symbols include signs of the zodiac and for the classical planets. These have their origin in medieval Byzantine codices, but in their current form are a product of the European Renaissance. Other symbols for astrological aspects are used in various astrological traditions.

A planet symbol is a graphical symbol used in astrology and astronomy to represent a classical planet or one of the eight modern planets. The symbols are also used in alchemy to represent the metals that are associated with the planets. The use of these symbols is based in ancient Greco-Roman astronomy, although their current shapes are a development of the 16th century.

Vanth (moon) Moon of 90482 Orcus

Vanth, full designation (90482) Orcus I Vanth, is the single known natural satellite of the plutino and likely dwarf planet 90482 Orcus. With a diameter of about 440 km, it is half the size of Orcus and probably the third-largest known moon of a known trans-Neptunian object, after Pluto I Charon and Eris I Dysnomia, though it is possible that the poorly resolved Varda I Ilmarë or Haumea I Hiʻiaka might be comparable in size. Vanth was discovered by Michael Brown and T.-A. Suer using discovery images taken by the Hubble Space Telescope on 13 November 2005. The discovery was announced in an IAU Circular notice published on 22 February 2007.

Planetary-mass moon Moons comparable in size to small planets

A planetary-mass moon is a planetary-mass object that is also a natural satellite. They are large and ellipsoidal in shape. Two moons in the Solar System are larger than the planet Mercury : Ganymede and Titan, and seven are larger and more massive than the dwarf planet Pluto.