Mountains tower up to two miles above the surface of Pluto in this July 14 image from New Horizons, taken from a distance of 478,000 miles (770,000 km). The mountains probably formed within the last 100 million years, according to mission scientists, making this some of the youngest terrain in the solar system. Scientists aren't sure what could power the creation of such young features on Pluto. The mountains probably are made of water ice, which is frozen as hard as granite on Pluto's frigid surface. [NASA/JHUAPL/SWRI]