Editing Exoplanet (section)

=== IAU ===
The official [[Definition of planet|definition of the term ''planet'']] used by the [[International Astronomical Union]] (IAU) only covers the [[Solar System]] and thus does not apply to exoplanets.<ref>{{cite web
|title=IAU 2006 General Assembly: Result of the IAU Resolution votes
|date=2006
|url=https://www.iau.org/news/pressreleases/detail/iau0603/
|archive-url=https://web.archive.org/web/20241225044449/https://www.iau.org/news/pressreleases/detail/iau0603/
|access-date=31 March 2025
|archive-date=25 December 2024
}}</ref><ref>{{cite web
|author=Brit, R. R.
|date=2006
|title=Why Planets Will Never Be Defined
|url=http://www.space.com/3142-planets-defined.html
|work=[[Space.com]]
|access-date=13 February 2008
}}</ref> The IAU Working Group on Extrasolar Planets issued a position statement containing a working definition of "planet" in 2001 and which was modified in 2003.<ref>{{cite web
|date=28 February 2003
|title=Working Group on Extrasolar Planets: Definition of a "Planet"
|url=http://w.astro.berkeley.edu/~basri/defineplanet/IAU-WGExSP.htm
|work=IAU position statement
|archive-url=https://web.archive.org/web/20210419012736/http://w.astro.berkeley.edu/~basri/defineplanet/IAU-WGExSP.htm
|access-date=31 March 2025
|archive-date=19 April 2021
}}</ref> An ''exoplanet'' was defined by the following criteria:

{{blockquote|
* Objects with [[true mass]]es below the limiting mass for thermonuclear fusion of deuterium (currently calculated to be 13 Jupiter masses for objects of solar [[metallicity]]) that orbit stars or stellar remnants are "planets" (no matter how they formed). The minimum mass/size required for an extrasolar object to be considered a planet should be the same as that used in the Solar System.
* Substellar objects with true masses above the limiting mass for thermonuclear fusion of deuterium are "[[brown dwarfs]]", no matter how they formed or where they are located.
* Free-floating objects in young star clusters with masses below the limiting mass for thermonuclear fusion of deuterium are not "planets", but are "sub-brown dwarfs" (or whatever name is most appropriate).
}}

This working definition was amended by the IAU's Commission F2: Exoplanets and the Solar System in August 2018.<ref>{{cite web
|title=Official Working Definition of an Exoplanet
|url=https://www.iau.org/science/scientific_bodies/commissions/F2/info/documents/
|work=IAU position statement
|archive-url=https://web.archive.org/web/20250212195344/https://www.iau.org/science/scientific_bodies/commissions/F2/info/documents/
|access-date=31 March 2025
|archive-date=12 February 2025
}}</ref><ref>{{Cite journal |last1=Lecavelier des Etangs |first1=A. |last2=Lissauer |first2=Jack J. |date=June 2022 |title=The IAU working definition of an exoplanet |url=https://linkinghub.elsevier.com/retrieve/pii/S138764732200001X |journal=New Astronomy Reviews |language=en |volume=94 |pages=101641 |doi=10.1016/j.newar.2022.101641|arxiv=2203.09520 |bibcode=2022NewAR..9401641L |s2cid=247065421 }}</ref> The official working definition of an ''exoplanet'' is now as follows:

{{blockquote|
* Objects with true masses below the limiting mass for thermonuclear fusion of deuterium (currently calculated to be 13 Jupiter masses for objects of solar metallicity) that orbit stars, brown dwarfs or stellar remnants and that have a mass ratio with the central object below the [[Lagrange point#Stability|L4/L5 instability]] (M/M<sub>central</sub> < 2/(25+{{math|{{radical|621}}}})) are "planets" (no matter how they formed).
* The minimum mass/size required for an extrasolar object to be considered a planet should be the same as that used in our Solar System.
}}