The Sun's angry red spot

Bad Astronomy
By Phil Plait
Mar 15, 2012 4:00 PMNov 20, 2019 5:39 AM


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The Sun has been in a bit of a mood lately, spitting out some pretty big flares (including the second largest one of the current magnetic cycle). Alan Friedman, one of my favorite astrophotographers, caught the culprit sunspot, Active Region 1429, as it was nearing the edge of the Sun on Monday:

Doesn't look like your normal shot of the Sun, does it? [Click to ensolarnate.] Alan uses an Hα filter, which cuts out almost all the light from the Sun except for a narrow slice of color emitted by warm hydrogen. This reduces the glare hugely, and reveals delicate structures in the Sun's plasma. He then inverts the image, so bright things appear dark, and vice-versa. That's an old astronomer's trick that makes fainter things easier to see. He also used a false color palette to make it appear reddish. That's actually a good idea, since the color of light emitted by the hydrogen is at 6563 Angstroms, right in the middle of the red part of the spectrum! In this case, doing all this makes the Sun look like a 1970s shag rug. It's a technique he uses to great effect. Just click on the Related Posts links below to see how! Andf you're wondering what the whole Sun looked like instead of just this closeup, then feast your eyes on this:

Yegads [click to embiggen]. Magnificent. Note all the prominences -- giant towers of gas at the edge of the Sun -- and the simply enormous filament of plasma at the top of the Sun's disk. It's about 400,000 km (240,000 miles) across: the distance from the Earth to the Moon! Holy solar phenomena. I'll add that Mexican astrophotographer César Cantú also took a nice image of the active region, and caught a loop of material arcing from one spot to another (marked with arrows):

Beautiful! And obviously, both Alan and César do a far better job of taking pictures of the Sun than I do.

Related Posts: - The face of our star - Giant sunspots are giant - For your viewing pleasure: Active Region 1302 - The boiling, erupting Sun

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