Pluto -- which is smaller than Earth’s Moon -- has a heart-shaped glacier that’s the size of Texas and Oklahoma. Fascinating Pluto also has blue skies, spinning moons, mountains as high as the Rockies, and it snows—but the snow is red! In this episode of Gravity Assist, Jim Green talks with New Horizons Principal Investigator Alan Stern of the Southwest Research Institute about what the July 2015 flyby of Pluto revealed about this mysterious and diverse world.