James Walter "Jim" Christy is an American astronomer known for discovering Charon, the largest moon of the dwarf planet Pluto.
James Christy (left) and Robert Harrington in 1978.
Charon, taken by New Horizons late on 13 July 2015. This color photograph made using Adobe Photoshop CS5.
Charon, 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 (377 mi). Charon is the sixth-largest known trans-Neptunian object after Pluto, Eris, Haumea, Makemake, and Gonggong. 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).
Charon as imaged by the New Horizons spacecraft, July 2015. A massive fault system involving Serenity Chasma and Mandjet Chasma crosses Charon's equator, while Charon's north pole is covered by the dark Mordor Macula
Charon's discovery at the Naval Observatory Flagstaff Station as a time-varying bulge on the image of Pluto (seen near the top at left, but absent on the right). Negative image.
Size comparisons: Earth, the Moon, and Charon
Comparison between Pluto's Sputnik Planitia and Charon's informally named Vulcan Planitia
