Charon compared with Eris, Pluto, Makemake, Haumea, Sedna, Orcus, 2007 OR10, Quaoar, their moons and Earth. All to scale.
The center of mass (barycenter) of the Pluto–Charon system lies outside either body. Because neither object truly orbits the other, and Charon has 11.6% the mass of Pluto, it has been argued that Charon should be considered to be part of a binary system. The International Astronomical Union (IAU) states that Charon is considered to be just a satellite of Pluto, but the idea that Charon might be classified a dwarf planet in its own right may be considered at a later date.
Excerpted from Wikipedia’s entry about Charon. https://en.wikipedia.org/wiki/Charon_%28moon%29
