IRIS

Explorer 94, Interface Region Imaging Spectrograph

Mission Profile

IRIS (Interface Region Imaging Spectrograph, Explorer 94) is a NASA solar observatory launched on 28 June 2013 from Vandenberg Air Force Base aboard a Pegasus XL air-launch rocket, designed to study the little-understood chromosphere and transition region between the Sun's visible surface and its million-degree corona. IRIS provides ultraviolet spectra and images at the highest resolution ever achieved in this spectral range, resolving features just 240 km across on the solar surface to observe the fine-scale dynamics of plasma heating, wave propagation, and magnetic reconnection. Key discoveries include observations of jets, waves, and explosive energy release events that help explain why the corona is hundreds of times hotter than the underlying solar surface. IRIS has operated continuously for over a decade, providing an irreplaceable window into the Sun's atmospheric heating processes.