We were stunned last week when the Pluto flyby revealed that the dwarf planet has mountains that are up to 11,000 feet tall. Now it turns out they're not alone. Sixty-eight miles to the northwest of the Norgay Mountains, across the vast plains of Sputnik Planum, lies a second icy mountain range. These peaks are smaller, reaching up to about half a mile to a mile high--or about the height of the Appalachian Mountains. On the range's western side is a dark, heavily cratered terrain that scientists think must be older than the plains and mountains.