Purple shag Sun

The great astrophotographer Andre van der Hoeven sent me a shot he took of the Sun a few days ago. Looks like either Barney or the Grape Nehi folks paid it a visit:

[Click to envioletenate.]

Pretty cool. First, of course, the purple color is not real. It's just the color Andre chose for this picture when he processed it. Second, he used an Hα filter, which lets through a very narrow slice of light (actually in the red part of the spectrum). This color is emitted by warm hydrogen, and is preferentially under the influence of the Sun's magnetism. You can see arching prominences - huge towers of gas - off the edge of the Sun. The long stringy bits on the face of the Sun are called filaments, and are actually the exact same thing as prominences! Prominences are filaments we see from the side, instead of looking down on them. The terminology is a holdover from when astronomers first started observing the Sun, and we're kinda stuck with it.

Also, Andre inverted the picture, so what looks black is actually very bright, and what looks bright is very dark. Those bright white blotches? Sunspots. For some reason, our brains can pick out detail better that way, and it also gives an eerie 3D sense to the image. He made a close-up mosaic of his pictures, too, which is actually a bit creepy. It'll keep the Halloween spirit going for another day, at least!

Image credit: Andre van der Hoeven, used by permission.

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