The largest satellite of Pluto. It is about 1,040 km across, roughly half Pluto's diameter. Charon is unusual in that it is the largest moon with respect to its primary planet in the Solar System. Moreover, the Pluto-Charon system is extraordinary because the center of mass lies in open space between the two, a characteristic of a double planet system. Pluto and Charon are also tidally locked in a synchronous orbit. Pluto's rotational period is 6.39 Earth days. It takes 6.39 days for Charon to make one revolution around Pluto. Thus, the two bodies continuously face each other. Also called Pluto I.
In Gk. mythology, Xαρον (Charon) was a figure who ferried the dead across the river Styx into Hades (the underworld).