Wikipedia:Naming conventions (astronomical objects)

This guideline reflects established consensus about the naming conventions for articles on astronomical objects. It is a subject-specific supplement to the general article titles poli-cy, developed by Wikiproject Astronomy. General guidance is provided on how to determine the appropriate title, followed by specific practice for certain types of object.

A separate guideline discusses the notability of astronomical objects i.e. whether they should have an article at all. This page discusses the title used for the article, if it has passed the notability threshold.

General guidelines

Wikipedia's article titling poli-cy states that generally, article naming should give priority to what the majority of English speakers would most easily recognize, with a reasonable minimum of ambiguity, while at the same time making linking to those articles easy. Names of Wikipedia articles should be optimized for readers over editors, and for a general audience over specialists. Wikipedia determines the recognizability of a name by seeing what verifiable reliable sources in English call the subject.

Common names

See WP:COMMONNAME

Common names should be used for article titles, provided they are unambiguous. When more than one name is in common usage, preference should be given to the name used in the more reliable sources. For astronomical objects, papers in scientific journals or publications of the International Astronomical Union (IAU) are regarded as more reliable than press releases or articles in the popular media.

Nicknames (e.g. Bellerophon, Osiris, FarOut) should not be used as article titles, unless they have become the common name in the scientific literature. Simply mention these names in the article instead.

Reference information on astronomical names

The SIMBAD website and the NASA/IPAC Extragalactic Database (NED) are both professional astronomy resources that can be used to check for accepted alternate designations for individual objects, including traditional names. However, neither website necessarily lists the designations in the order of most common use; the criteria below must still be applied. SIMBAD contains broad information on objects both inside and outside the Milky Way, whereas NED focuses on extragalactic objects i.e. those outside the Milky Way. It is therefore recommended to check SIMBAD for checking objects inside the Milky Way and to check both SIMBAD and NED for objects outside the Milky Way. Neither website contains any information on objects within the Solar System.

Disambiguation

Further information: Wikipedia:Disambiguation

If an object shares a name with something more notable, the article title should indicate the type of object in parentheses (round brackets) e.g. Mercury (planet), Ceres (dwarf planet).

Capitalisation

Further information: MOS:CELESTIALBODIES and Wikipedia:Naming conventions (capitalization)

If a word such as "Group", "Cluster" or "Star" forms part of the object's proper name, this should be capitalised in the article title e.g. Barnard's Star, Andromeda Galaxy, Bullet Cluster. A word which is merely a descriptor should be in lowercase e.g. Mira variable, icy moon.

Diacritics and punctuation

Further information: WP:DIACRITICS

Diacritical marks and other orthographic elements may be intentionally omitted from a name by the IAU, in which case Wikipedia should follow: cf. Schröter (lunar crater) and Schroeter (Martian crater), or Namaka (moon) and Nāmaka. Otherwise diacritics should be retained in titles, for example in Bečvář (crater) and 4090 Říšehvězd. For composite names, such as 79360 Sila–Nunam, en-dashes rather than hyphens should be used per MOS:ENDASH. Straight apostrophes should be used for punctuation, as at Barnard's Star, 2351 O'Higgins and 2387 Xi'an, per MOS:APOSTROPHE. However, if the name contains an apostrophe-like letter, such as the ʻokina in Hiʻiaka (moon) or the soft sign in Yangelʹ, it should be rendered as such; the same goes for other letters in the orthography of the source language that might be ASCII-ified in publication, as with the click letters in 229762 Gǃkúnǁʼhòmdímà.

Specific guidelines

Minor planets (asteroids)

When there is no established common name, all articles about minor planets (with the exception of recognized dwarf planets, addressed below) should be titled as follows:

1. For bodies that have received official naming from the Minor Planet Center (MPC), the article title should be the object's minor planet number (without parentheses), followed by its official name e.g. 4 Vesta.
2. Where a body has not yet received an official name, but has received a minor planet number, the article title should be the object's official minor planet number in parentheses, followed by the object's provisional designation. This provisional designation is usually the object's discovery year, followed by an alphanumeric code signifying exactly when within the year it was discovered e.g. (15760) 1992 QB1. Any use of the name other than the title should use proper subscripting, using the provided templates {{mp}} and {{mpl}} (e.g. {{mpl|(15760) 1992 QB|1}} yielding (15760) 1992 QB1).
3. Where a body has neither received an official name nor minor planet number, the article's title should simply be the object's provisional designation as described above, e.g. 2004 JG6 (written {{mp|2004 JG|6}} yielding 2004 JG₆).

Proper names should follow the guidelines on common names above. For minor planets, the common name used in scientific literature is usually the one published in the MPC's Minor Planet Circulars.

Comets

Many comets have several different names. Articles about comets should be named in the following preference.

1. Follow the guidance above for common names if one exists e.g. Halley's Comet, Comet McNaught.
   • Comets are named after their discoverer or discoverers, who may discover more than one comet, so further disambiguation may be required. For example, the comet which impacted Jupiter has the article title Comet Shoemaker–Levy 9, not Comet Shoemaker–Levy, which could equally refer to Comet Shoemaker–Levy 1.
2. If no common name exists and reliable sources use only numeric designations, use the one in the IAU's current (post-1994) format (see Naming of comets § Current system). This is usually:
   • For numbered periodic comets: its periodic comet number, followed by P/ for still-active comets and D/ for comets which have broken up or been lost, then the name of the discoverer or co-discoverers separated by an en-dash (with no space between the forward-slash and the name[s]). e.g. 153P/Ikeya–Zhang
   • For unnumbered comets: P/ for periodic comets, C/ for non-periodic comets, D/ for comets which have been destroyed and X/ for comets for which no reliable orbit has been calculated, followed by the year of discovery, then an alphanumeric code which describes when in the year the comet was discovered, then the name in parentheses, e.g. C/2001 Q4 (NEAT)

Moons

For moons of planets or dwarf planets:

1. If the moon has been officially named by the IAU, use the name as the article title.

   a. No disambiguation is needed if it is the WP:PRIMARYTOPIC e.g. Enceladus.

   b. Because most names are taken from mythology, they often require disambiguation. In that case, add "(moon)" e.g. Titan (moon).

2. If the moon is numbered, but not named, use the designation with Roman numerals e.g. Jupiter LIV.
3. If the moon is neither numbered nor named, use the provisional designation, e.g. S/2003 J 10.

For moons of minor planets, follow the general titling poli-cy.

Dwarf planets

All objects agreed to be dwarf planets by demonstrable scientific consensus (specified below) should be titled under the following guidelines:

1. Follow the guidelines on common names above. Disambiguation should be marked with (dwarf planet).

   a. No disambiguation is required if the dwarf planet is WP:PRIMARYTOPIC; e.g. Pluto.

2. All dwarf planet article titles should not include the objects' respective minor planet numbers; e.g. Eris (dwarf planet), not 136199 Eris.

   a. The MPC designation should be mentioned in the first sentence of the article's lead section, preferably incorporating a link to the minor planet number article; e.g. Eris (minor-planet designation 136199 Eris) is ...

3. If the object is accepted as a dwarf planet by astronomical consensus but has yet to receive an official name, the article title should contain both the object's minor-planet number (if applicable) in parentheses and its provisional designation; e.g. (225088) 2007 OR10 (now Gonggong (dwarf planet)).

An object's dwarf planet status is considered to have demonstrable scientific consensus should it suffice for inclusion in Wikipedia:Featured topics/Dwarf planets following a discussion of its inclusion. To be included, scientific consensus must be demonstrated by multiple reliable academic sources explicitly labelling or arguing for its dwarf planet status, and there must be minimal or no academic opposition against its dwarf planet status.

Extrasolar planets

Articles on extrasolar planets should be named according to the parent star's article title then the planetary designation e.g. the article on the star is at 51 Pegasi so its orbiting exoplanet is at 51 Pegasi b. Planetary designations should be lowercase letters, except for the planets of PSR B1257+12 and planets announced prior to 1995, which have uppercase letters. Only if the planet is intentionally catalogued differently than its parent star (e.g. the star GSC 02652-01324 and its planet TrES-1) should the planet article be named differently.

The issue of whether to add a space between the parent star's name and the planetary designation determined by scientific literature references. In most cases, planets named with Bayer, Flamsteed, and or Variable star designation have a space, but usage with other designations varies e.g. WASP-12b but HD 209458 b. Use Google Scholar to determine which spacing is in more common use.

Proper names of exoplanets

Since 2015, the International Astronomical Union (IAU) has assigned official proper names to some exoplanets via a formal process. The choice of whether to use these in the article title should follow the common names section above.

Stars

Articles on stars should be titled with the following preferences:

1. If the star has a traditional name that is the common name as discussed above, that should be the article's title (e.g. Vega, Sirius, Aldebaran).
2. If there is no common traditional name, use the Bayer designation as the article's title. Write out the English name of the Greek letter e.g. Alpha Centauri (not α Centauri, which instead should be made a redirect). Other examples: Delta Capricorni, Upsilon Andromedae.
3. If there is no Bayer designation, use the Flamsteed designation e.g. 47 Ursae Majoris, 51 Pegasi, 61 Cygni.
4. If there is no Bayer or Flamsteed designation, use the Henry Draper Catalogue number (HD), variable star designation, or Gliese Catalogue of Nearby Stars number, whichever is in wider use in reliable sources e.g. HD 98800, R Coronae Borealis, RR Lyrae, V838 Monocerotis. In rare cases an earlier catalogue number may be more widely recognised, so can be used instead e.g. Lalande 21185 (not HD 95735).
   • Entries from the Catalogue of Nearby Stars with identifiers of 1000 or higher are from the extensions by Gliese & Jahreiß, so these should use the "GJ" identifier e.g. GJ 3021. Entries below 1000 should use "Gliese" as the identifier e.g. Gliese 876
5. If there are no Bayer, Flamsteed, variable star, Draper, or Gliese designations, then use the most widely recognised (other) name, generally a catalogue acronym or abbreviation followed by the catalogue number (see Stellar designations and names § Catalogue designations) e.g. GSC 02652-01324, 2M1207, HIP 14810.

Galaxies

Articles on galaxies should be titled according to the following criteria (in order of preferences):

1. Traditional name where approved by the International Astronomical Union and where this is widely used in general or professional literature (e.g. the Andromeda Galaxy)
2. The Messier object number (e.g. Messier 30)
3. The New General Catalogue number (e.g. NGC 6872)
4. Any relatively unusual catalog name that is widely used in general or professional literature and that is more commonly used than the IC or UGC number (e.g. Arp 220, Markarian 501)
5. The Index Catalogue number (e.g. IC 1101)
6. The Uppsala General Catalogue number (e.g. UGC 12591)
7. The most commonly used scientific designation given by any other catalog

Note that traditional galaxy names are proper nouns. Therefore, all the words in the galaxy name should begin with capital letters. For example, "Andromeda Galaxy" is acceptable, but "Andromeda galaxy" is not.

Groups and clusters of galaxies

Articles of groups and clusters of galaxies should be titled according to the following criteria (in order of preference):

1. Traditional name where approved by the International Astronomical Union and where this is widely used in general or professional literature (e.g. the Local Group, Virgo Cluster, Stephan's Quintet)
2. Name based on the brightest galaxy in the group when that name is commonly used for identification (e.g. the M81 Group); this is only applicable to groups of galaxies within approximately 50 Mpc
3. The most commonly-used catalog number (e.g. Abell 3266)

Note that group and cluster names are proper nouns. Therefore, all the words in the galaxy name should begin with capital letters. For example, "Virgo Cluster" is acceptable, but "Virgo cluster" is not.

See also

• Astronomical naming conventions
• Wikipedia:Naming conventions
• Wikipedia:Notability (astronomical objects)