Pluto Spray Paints its Moon Red

The red color near the north pole of Charon, Pluto’s largest moon, originates on Pluto. Once a mystery, it now appears that the red color of “Mordor Macula” arises as methane gas escapes from Pluto’s atmosphere and freezes onto the icy surface of Charon’s north pole. UV light from the Sun then transforms the methane into reddish organic materials. The New Horizons team that reported this result includes NOAO astronomer Tod Lauer.