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.
An Undulating Sunspot
Credit: IRIS, LMSAL/NASA, Chad Madsen (SAO)
In the far ultraviolet, sunspots aren't the dark, innocuous splotches we usually imagine them to be. Instead, they can appear quite bright and host a number of dynamic phenomena. In this video, we see a great example of running sunspot waves. The sunspot is located in the right-center portion of the field of view and is continuously generating an undulating ripple pattern. These are signatures of what are called magneto-acoustic waves, which are effectively sound waves modified by the sunspot's intense magnetic field. They travel upward through the funnel-like sunspot where the wavefront emerge through the center first before the surrounding region, producing the concentric ripple pattern we see here.