New Horizons Captures Pluto’s Heart

This is Pluto as no one had ever seen it before. On July 14, 2015, NASA's New Horizons spacecraft flew past the distant dwarf planet after a journey of more than nine years and three billion miles. The large pale region near the center, shaped a bit like a heart, is officially named Tombaugh Regio, after Clyde Tombaugh, the American astronomer who first spotted Pluto back in 1930. His ashes were actually carried aboard the spacecraft, so in a sense the man who discovered Pluto finally got to visit it.

The colors here are gently enhanced to bring out the differences in surface material. The rusty brown patches come from tholins, sticky compounds that form when sunlight and cosmic rays break apart methane and nitrogen in Pluto's thin atmosphere. The smooth heart itself is a vast plain of frozen nitrogen ice, remarkably free of craters, which tells scientists the surface there is young and still changing. For something so small and so far from the Sun, Pluto turned out to be surprisingly alive with geology, a reminder that the edges of our solar system still hold plenty of surprises.