More about our sun

At According to Hoyt Stephanie Osborn continues her discussion of Solar, Space, and Geomagnetic Weather.

At the end of every 11-year cycle, the magnetic orientation of the spots…flips. Yeah, you heard right — this is one of the few times when the old trope about “reversing the polarity” is actually the correct answer. The end that was North becomes South, and the end that was South becomes North. MORE, the ENTIRE solar magnetic field ALSO flips! (This got very complex this last time; it wasn’t as fast and simple. It took nearly six months, and for a time our Sun had something like FOUR South poles, and NO North poles. Yeah, stellar magnetics gets crazy.) It takes a whole ‘nother cycle to get back to the way it started out. So that’s a second solar cycle, the 22-year cycle.

Now, sunspots look dark not because they’re cold, but because they’re just a bit cooler than the surrounding plasma of the photosphere (which is the visible “surface” of the Sun). If the photosphere is about 5,800°K (~10,500°F), then the sunspots are about 3,000-4,500°K (4,900-7,600°F). Still plenty hot enough to fry your bacon, but still several thousand degrees cooler than their surroundings. They can be teeny-tiny (relatively speaking, of course) or they can be huge things (80,000km/50,000mi — not too shabby when you consider the Earth is about 13,000km/8,000mi diameter), big enough to be seen by the naked eye. (But don’t do that — we like having eyesight. If you really want to observe the Sun, the best way is to get a telescope, aim it at the Sun, and hold a sheet of white cardboard behind the eyepiece. Adjust the distance until you get an image of the Sun projected on the cardboard. This is a cool way to watch solar eclipses, too. If you don’t have a telescope, grab a shoebox, punch a small hole in one end, turn it upside down and point the hole at the Sun, then tilt the thing around until you get a small image inside the opposite end of the box.) Sunspots aren’t really dark at all; they just APPEAR dark because of the contrast with the surrounding hotter, brighter photosphere.

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