An enhanced-color image of Charon, the largest moon of Pluto, snapped in 2015 by the New Horizons probe, reveals a reddish cap at its north pole. The material at the pole probably contains methane from the surface of Pluto that has been altered by exposure to sunlight and other processes. Charon is about 750 miles (1,250 km) in diameter. [NASA/JHUAPL/SWRI]