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.
A lone sunspot
Credit: IRIS, LMSAL/NASA, Milan Gosic
On Dec 25th, 2020, IRIS observed a nice, fully formed sunspot. The sunspot is visible as a dark area called umbra, surrounded by a brighter penumbra. Sunspots are caused by intense magnetic fields, which inhibit convection in the umbra, forming areas of reduced surface temperature. This region is surrounded by a hotter penumbra, which is organized in radial bright and dark filaments. Away from the sunspot, convection is visible as a rapidly evolving granular pattern that reveals bubbles of hot gas going up and colder gas moving down.