Because neither object truly orbits the other .
Charon has 12.2 % the mass of Pluto , it has been argued that Charon should be considered to be part of a binary system with Pluto .
Because neither object truly orbits the other , and Charon has 12.2 % the mass of Pluto , it has been argued that Charon should be considered to be part of a binary system with Pluto .