Added 1 new A* page:Thanks to webcomics.biz (and the reader(s) who submitted my comic?) for listing A*, even giving it a little capsule review, and making a custom banner thingy for it. Neat! And they've also got an entry for my weekend fairy tale comic, The Princess and the Giant, so double-yay! :D
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Well I talked up the current wave of fancy solar probes like STEREO, SOHO, and the SDO yesterday, but it was actually the old Skylab space station that verified the existence of coronal holes back in the '70s with orbital X-ray telescopes; Skylab's studies of the Sun in X-ray and ultraviolet frequencies, as well as others, provided a real breakthrough in solar research. Skylab didn't do so bad getting its own photos of those plumes from polar coronal holes, for instance:
image by NASA (source)
One of the largest and most famous coronal holes found and studied by Skylab was the "Boot of Italy," so-named for its distinctive shape, and seen here by Skylab over a 6-day period:
image by NASA (source)
Here's another Skylab sequence, showing the evolution of what begins as a single huge coronal hole (the "Boot" again, I think), over a period of three months, again in X-rays:
image by NASA (source)
Skylab studied plenty of active regions, too; here's a nice X-ray photo from Skylab showing emissions from magnetic loops in the corona: "the seat of intense magnetic fields, where X-rays escape from heated gas trapped in magnetic loops that connect points of opposite polarity":
image by NASA (source)
And check out the second movie (mpeg format) down on this page for some nicely retro-looking Skylab video footage of a large coronal hole.
It is worth mentioning though that Skylab's weren't the very first X-ray photos of the solar corona; here's a composite of photos taken from rocket flights between 1963 and 1969:
image by NASA (source)
All of those Skylab photos came from NASA's history site, which is well worth checking out for oodles more neat Skylab research results.
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