During flares, a large amount of magnetic energy is released, heating the sun’s atmosphere and releasing energized particles out into space. ![]() Solar flares are powerful explosions of radiation. On July 24, 2016, NASA’s Interface Region Imaging Spectrograph, or IRIS, captured a mid-level solar flare: a sudden flash of bright light on the solar limb – the horizon of the sun – as seen at the beginning of this video. NASA’s IRIS Spots Plasma Rain on the Sun’s Surface The more we know about what drives this activity – activity that can include giant eruptions of solar material and radiation that can create hazards for satellites and astronauts – the better we may someday predict its onset. HMI tracks variations in the solar limb over time to help us understand how the shape of the sun changes with respect to the solar cycle, the sun’s 11-year pattern of solar activity. HMI’s biannual roll lets each part of the camera look at the entire perimeter of the sun, helping it map the sun’s shape much more precisely. This makes it hard for HMI to find the sun’s edge when it’s perfectly still. But the solar surface is dynamic, leading to occasional distortions. ![]() ![]() Were the sun perfectly spherical, this would be a much simpler task. This maneuver happens twice a year to help SDO’s Helioseismic and Magnetic Imager, or HMI, instrument take precise measurements of the solar limb, the outer edge of the sun as seen by SDO. This video was taken by SDO’s Atmospheric Imaging Assembly instrument in extreme ultraviolet wavelengths that are typically invisible to our eyes, but was colorized here in gold for easy viewing. SDO dutifully performed the seven-hour maneuver, while producing some dizzying data: For this period of time, SDO images – taken every 12 seconds – appeared to show the sun spinning, as if stuck on a pinwheel. On July 6, 2016, engineers instructed NASA’s Solar Dynamics Observatory, or SDO, to roll 360 degrees on one axis.
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