Charon is Pluto's largest moon, discovered in 1978 by James Christy at the United States Naval Observatory. It is about 750 miles in diameter, having more than half the diameter of Pluto causing the center of gravity of the two bodies to lie outside of Pluto. Charon and Pluto revolve around their center of mass every 6.4 days.
The New Horizons spacecraft provided the first highly detailed look at Charon during its flyby in 2015 and this map is constructed from images returned from the spacecraft. Charon's density is about 1.6 times that of water, suggesting a nearly even composition of rock and ice.
Charon has a bright coating of water ice (including ice crystals mixed with ammonia hydrates) near the equator and darker areas near the poles.
This with the occurrence of relatively few craters suggests Charon has been and may still be geologically active.
Due to the rotation of Charon and the position of the spacecraft, the image of Charon is not complete and is partially high resolution. This image has enhanced color.