This image of Pluto’s largest moon Charon was derived from data taken by New Horizons during its 2015 flyby. The small bump around the 1 o’clock position in the pixelated image of Pluto in the upper left was used by James Christy and Robert Harrington at the U.S. Naval Observatory in Flagstaff to discover Charon in 1978,

Image Credits: NASA / APL / SWRI / U.S. Naval Observatory