Astronomy Picture of the Day . ... 17.07.2015 . ... Credit Copyright: NASA , Johns Hopkins Univ./ ... Explanation: Icy world Charon is 1,200 kilometers across. That makes Pluto's largest moon only about 1/10th the size of planet Earth but a whopping 1/2 the diameter of Pluto itself . ... The image was captured late July 13 during the spacecraft's flight through the Plutonian system from a range of less than 500,000 kilometers. ... July 2015 . ... Publications with keywords: Charon - Moon . ...