... APL , Southwest Research Institute Explanation: A darkened and mysterious north polar region informally known as Mordor Macula caps this premier high-resolution portrait of Charon, Pluto's largest moon . Captured by New Horizons near its closest approach on July 14, the image data was transmitted to Earth on September 21. The combined blue, red, and infrared data is processed to enhance colors, following variations in surface properties with a resolution of about 2.9 kilometers (1.8 miles). ...