IRIS Movie of the Day
At least once a week a movie of the Sun taken by NASA's Interface Region Imaging Spectrograph (IRIS) is posted by one of the scientists operating the instrument.
Shadow flashes and a light bridge
Credit: IRIS, LMSAL/NASA
Sunspots are dark regions on the Sun that are formed when strong magnetic fields erupt through the photosphere (the visible surface of the Sun). In this IRIS observation of a sunspot, a band of bright plasma (called a light bridge) can be seen running through the middle of the spot. Light bridges are often seen when sunspots begin to break up and disappear. Meanwhile, quick flashes of light can be seen in the dark umbra (from Latin "shade") of the spot, and penumbral waves can also be tracked rippling outward from the edge of the sunspot.