Editing Astronomical naming conventions (section)

=== Natural satellites ===
{{Further|Naming of moons}}

Earth's natural satellite is simply known as the [[Moon]], or the equivalent in the language being spoken (for instance, two astronomers speaking [[French language|French]] would call it ''la Lune''). English-language science fiction often adopts the Latin name "Luna" while using the English "Moon" as a term for natural satellites in general in order to better distinguish the wider concept from any specific example. Natural satellites of other planets are generally named after mythological figures related to their parent body's namesake, such as [[Phobos (moon)|Phobos]] and [[Deimos (moon)|Deimos]], the twin sons of [[Ares]] (Mars), or the [[Galilean moons]] of [[Io (moon)|Io]], [[Europa (moon)|Europa]], [[Ganymede (moon)|Ganymede]], and [[Callisto (moon)|Callisto]], four consorts of [[Zeus]] (Jupiter). Satellites of Uranus are instead named after characters from works by [[William Shakespeare]] or [[Alexander Pope]], such as [[Umbriel]] or [[Titania (moon)|Titania]].

When [[natural satellite]]s are first discovered, they are given provisional designations such as "[[Jupiter LII|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 [[comet]]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 ('''J'''upiter, '''S'''aturn, '''U'''ranus, '''N'''eptune; although no occurrence of the other planets is expected, Mars and Mercury are disambiguated through the use of '''H'''ermes 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 (asteroid)|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 (moon)|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,<ref>{{cite web|url=http://www.cbat.eps.harvard.edu/cbet/cbet002769.txt |title=New Satellite of (134340) Pluto: S/2011 (134340) 1|access-date=2011-07-20 |url-status=dead |archive-url=https://web.archive.org/web/20120526133147/http://www.cbat.eps.harvard.edu/cbet/cbet002769.txt |archive-date=2012-05-26 }}</ref> though the ''[[New Horizons]]'' team, who disagreed with the dwarf planet classification, used the latter.
* '''H''' = [[Mercury (planet)|Mercury]] (Hermes){{efn|The assignment of "H" for Mercury is specified by the {{cite web |url=http://planetarynames.wr.usgs.gov/specifics.html |title=USGS Gazetteer of Planetary Nomenclature}}; since the USGS usually closely follows IAU guidelines, this is very likely the IAU convention, but confirmation is needed.}}
* '''V''' = [[Venus]]
* '''E''' = [[Earth]]
* '''M''' = [[Mars]]
* '''J''' = [[Jupiter]]
* '''S''' = [[Saturn]]
* '''U''' = [[Uranus]]
* '''N''' = [[Neptune]]

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. See [[Naming of moons]] for a history of how some of the major satellites got their current names.

The Roman numbering system arose with the very first discovery of natural satellites other than Earth's: [[Galileo Galilei|Galileo]] referred to the [[Galilean moons]] as '''I''' through '''IV''' (counting from Jupiter outward), in part to spite his rival [[Simon Marius]], who had proposed the names now adopted, after his own proposal to name the bodies after members of the [[House of Medici|Medici family]] failed to win currency. Similar numbering schemes naturally arose with the discovery of moons around Saturn and Mars. Although the numbers initially designated the moons in orbital sequence, new discoveries soon failed to conform with this scheme (e.g. "Jupiter&nbsp;V" is [[Amalthea (moon)|Amalthea]], which orbits closer to Jupiter than does [[Io (moon)|Io]]). The unstated convention then became, at the close of the 19th&nbsp;century, that the numbers more or less reflected the order of discovery, except for prior historical exceptions (see the [[Timeline of discovery of Solar System planets and their moons]]).