Rather than try to construct a detailed definition of a planet which is designed to cover all future possibilities, the WGESP (Working Group On Extrasolar Planets) of the International Astronomical Union has agreed to restrict itself to developing a working definition applicable to the cases where there already are claimed detections.

Emphasizing again that this is only a working definition the WGESP has agreed to the following statements:

1) 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 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 our Solar System.

2) Substellar objects with true masses above the limiting mass for thermonuclear fusion of deuterium are 'brown dwarfs', no matter how they formed nor where they are located.

3) 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). >from *Working Group on Extrasolar Planets. Definition of a 'Planet'*. february 28, 2003

related context
> defining 'planet' by gibor basri draft of march 20, 2003
> quaoar: a new world in the solar system. october 14, 2002
> planetary systems in the universe. august 7, 2000

imago
> looking at celestial wanderers