Sole satellite of Pluto, Charon is named after the Greek mythological figure who ferried the dead across the river Styx in to the underworld. Not coincidentally, the name of the ruler of the underworld was Pluto.
Charon’s diameter is 1,172 kilometers (728 miles), just over half the size of Pluto. It has 1/7th the mass of Pluto. It has a surface area of 4,400,000 km2.
Due to the unusually small difference in size between it and Pluto, Pluto and Charon are sometimes considered to be a double planet. They are also sometimes thought of as not a planet and a satellite, but as the first two Trans-Neptunian objects.
See also: Greek Mythology