Charon (moon) Charon (moon) Charon, also known as (134340) Pluto I, is the largest of the five known natural satellites of the dwarf planet Pluto. It has a mean radius of 606 km. It was discovered in 1978 at the United States Naval Observatory in Washington, D.C., using photographic plates taken at the United States Naval Observatory Flagstaff Station (NOFS). 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 Plutonian system lies outside Pluto. The reddish-brown cap of
Definition of planet storms [Titan] shouldn't be put into the same category, whatever you call it. However, he goes on to say that, "For most people, considering round satellites (including our Moon) "planets" violates the idea of what a planet is." Alan Stern has argued that location should not matter and that only geophysical attributes should be taken into account in the definition of a planet, and proposes the term "satellite planet" for a planet-sized satellite. In 2017, Stern, K. D. Runyon et al. proposed a new geophysical definition of planet that defined a planet simply as an object large enough to be