This wavelength highlights the outer atmosphere of the Sun (corona) as well as flare plasma. Hot active regions, solar flares, and coronal mass ejections will appear bright here. The dark areas are coronal holes—places where there is very little radiation emitted. Despite the low radiation, coronal holes are the primary source of solar wind particles.
Sun region: Corona and hot flare plasma
Wavelength: 193 angstroms / 0.0000000193 m (Extreme Ultraviolet)
Primary ions observed: 11 times ionized iron (Fe XII)
Characteristic temperature: 1.25 million K (2.25 million F)