NASA’s New Horizons probe performed the first-ever flyby of Pluto in July 2015. Washington University’s William McKinnon is one of the scientists involved in the mission. After studying the data, McKinnon published remarkable findings that surpassed everyone’s expectations about the dwarf planet. McKinnon explains how Pluto’s surface is surprisingly young and geologically active. A large section of Pluto’s nitrogen ice surface is renewed by a process called convection. Photo courtesy of NASA.