Charon

Charon, is the largest of the five moons of Pluto in this minor planetary system. It was discovered in 1978 by the United States Naval Observatory in Washington, D.C., using photographic plates taken at the United States Naval Observatory Flagstaff Station (NOFS). 
==Pluto planetary system==
With half the diameter and one eighth the mass of Pluto, Charon is a very large moon in comparison to its parent body. Its gravitational influence is such that the barycenter of the Pluto–Charon system lies outside Pluto. In September 2016, astronomers announced that the reddish-brown cap of the north pole of Charon is composed of tholins, organic macromolecules that may be essential ingredients of life, and produced from methane, nitrogen and related gases released from the atmosphere of Pluto and transferred over about distance to the orbiting moon. 
==New Horizons==
The New Horizons spacecraft is the only probe that has visited the Pluto system. It approached Charon within 27,000 km (17,000 mi) in 2015.
==References==
Category:Pluto