English: n this photo, NASA's Interface Region Imaging Spectrograph (IRIS) spacecraft captured several large solar prominences on the edge of the sun last week. On May 6, 2015, IRIS completed its 10,000th orbit of the Earth. IRIS, part of the agency’s Heliophysics System Observatory of missions, was launched in 2013 to track how energy and heat courses through a little understood region of the solar atmosphere called the interface region.