The largest moon of the dwarf planet Pluto.
The other known moons of Pluto are Nix, Hydra and S/2011 P 1.
Charon has a diameter of 790 miles and orbits Pluto at a
distance of 12,200 miles in approximately 6.4 days.
Charon was discovered in 1978 by James Christy
and is named after [1]
but also because the first syllable is the nickname of his wife, Charlene.
To an observer (in the appropriate hemisphere) on the surface of Pluto,
Charon would remain fixed in the sky.