The Sun’s Long-Lived Active Regions Are Massive Flare Factories—But We Don’t Know Why
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Space weather is a fascinating subject, but one we still have a lot to learn about. One of the main components of it is the active regions (ARs) of the Sun. These huge concentrations of magnetic fields show up throughout the Sun’s photosphere and are the primary source of solar flares and coronal mass ejections (CMEs). They can be simple pairings of magnetic flux or huge, magnetically complex tangles that spend weeks creating massive solar storms before dissipating. But tracking the longest live
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The Sun’s Long-Lived Active Regions Are Massive Flare Factories—But We Don’t Know Why By Andy Tomaswick - March 20, 2026 12:18 PM UTC | Solar Astronomy Space weather is a fascinating subject, but one we still have a lot to learn about. One of the main components of it is the active regions of the Sun. These huge concentrations of magnetic fields show up throughout the Sun’s photosphere and are the primary source of solar flares and coronal mass ejections . They can be simple pairings of magnetic flux or huge, magnetically complex tangles that spend weeks creating massive solar storms before dissipating. But tracking the longest lived of these ARs has been a headache for solar physicists, and a recent paper by Emily Mason and Kara Kniezewski, published in The Astrophysical Journal, both dives into this tracking problem and uncovers some interesting features of the Sun’s most persistent ARs. To understand the problem of tracking ARs, we have to understand the system of how it's currently done. Since 1972, the National Oceanic and Atmospheric Administration has assigned a sequential, five-digit number to each sunspot traveling the face of the Sun. But the Sun rotates, and not in a typical way that the Earth does. Since it's made of plasma, its equator rotates faster than its poles in a process known as Carrington rotation. Astronomers have known this for years, and they also have known that some active regions are robust enough to rotate off the western side of the Sun, transit across its far side, and then reappear on the eastern side weeks later. While it's transiting across the far side, it can be tracked using a series of extreme ultraviolet maps and farside helioseismic data to make sure they were tracking the same AR. Fraser talks about the Carrington Event - the most powerful solar storm ever recorded. But when it appears back on the side of the Sun facing us, the NOAA number system assigns it a completely new number again. As any computer scientist will tell yo...
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