Editing Charon (moon) (section)

== Classification ==

The [[centre of mass#Barycenter|center of mass]] (barycenter) of the Pluto–Charon system lies outside either body. Because neither object truly orbits the other, and Charon has 12.2% of the mass of Pluto, it has been argued that Charon should be considered to be part of a [[binary planet]] with Pluto. The [[International Astronomical Union]] (IAU) states that Charon is a satellite of Pluto, but the idea that Charon might be classified as a dwarf planet in its own right may be considered at a later date.<ref name="IAU_DP"/>

In a draft proposal for the [[IAU definition of planet|2006 redefinition]] of the term, the IAU proposed that a planet is defined as a body that orbits the Sun that is large enough for gravitational forces to render the object (nearly) spherical. Under this proposal, Charon would have been classified as a planet, because the draft explicitly defined a planetary satellite as one in which the barycenter lies within the major body. In the final definition, Pluto was reclassified as a [[dwarf planet]], but a formal definition of a planetary satellite was not decided upon. Charon is not in the list of dwarf planets currently recognized by the IAU.<ref name="IAU_DP"/> Had the draft proposal been accepted, even the [[Moon]] would hypothetically be classified as a planet in billions of years when the [[tidal acceleration]] that is gradually moving the Moon away from Earth takes it far enough away that the center of mass of the system no longer lies within Earth.<ref name="moonplanet" />

The other moons of Pluto{{snd}} [[Nix (moon)|Nix]], [[Hydra (moon)|Hydra]], [[Kerberos (moon)|Kerberos]], and [[Styx (moon)|Styx]]{{snd}} orbit the same barycenter but they are not large enough to be spherical and they are simply considered to be satellites of Pluto (or of Pluto–Charon).<ref name="NixHydra"/>