New Horizons was about 3.7 million miles (6 million kilometers) from Pluto and Charon when it snapped this portrait late on July 8, 2015. Charon is about 750 miles (1200 kilometers) across (about half the diameter of Pluto) making it the solar system's largest moon relative to its planet. NASA's unmanned New Horizons spacecraft is closing in on the Pluto system after a more than nine-year, three-billion-mile journey. On July 14 it will zip past Pluto at 30,800 miles per hour, with a suite of seven science instruments busily gathering data. The mission will complete the initial reconnaissance of the solar system with the first-ever look at the icy dwarf planet.