NASA’s New Horizons space probe, which will do a close flyby of the Pluto system on July 14, has sent back a new image of Charon, the largest of Pluto’s five moons. New Horizons was about 3.7 million miles (6 million km) from Charon when it snapped this image on July 8, 2015. Image credit: NASA / Johns Hopkins University Applied Physics Laboratory / Southwest Research Institute. Charon was discovered on April 13, 1978 by American astronomer James...