The primary goal of the Interface Region Imaging Spectrograph (IRIS) explorer is to understand how the solar atmosphere is energized. The IRIS investigation combines advanced numerical modeling with a high resolution UV imaging spectrograph.

IRIS will obtain UV spectra and images with high resolution in space (0.33-0.4 arcsec) and time (1-2s) focused on the chromosphere and transition region of the Sun, a complex interface region between the photosphere and corona. In this region, all but a few percent of the non-radiative energy leaving the Sun is converted into heat and radiation. Here, magnetic field and plasma exert comparable forces, resulting in a dynamic region whose understanding remains a challenge.

IRIS fills a crucial gap in our ability to advance Sun-Earth connection studies by tracing the flow of energy and plasma through this foundation of the corona and heliosphere.