The goal of NASA’s Interface Region Imaging Spectrograph, or IRIS, is to understand how the energy travels through the interface region of the sun– energy that helps heat the upper layer of the atmosphere, the corona, to temperatures of 1 million kelvins (about 1.8 million F), some thousand times hotter than the sun’s surface itself. IRIS is scheduled to launch from California’s Vandenberg Air Force Base on June 26, 2013.