Spurting Spicules (Aug 8, 2008)
By zooming in on the sun's north pole area with STEREO (Behind) Extreme UV Imager, we see quite clearly hundreds (if not thousands) of very brief spurts of plasma called spicules over about a day and a half (August 2-3, 2008). In the full disk images these are too small to be easily discerned. And they are easier to observe when the sun is near its minimum level of activity as it is now. They shoot up at speeds up to 50,000 miles per hour (81,000 kilometers per hour), reaching heights of 3,000 miles (5,000 km). These are like supersonic jets with relatively small diameters of just 300 miles (500 km), lasting a few minutes. At any one time there are around 100,000 active spicules on the Sun. Here we are observing them in light produced by ionized Helium not far above the solar surface at about 60,000 degrees K. These features are not visible in the other wavelengths in which STEREO observes. Towards the end of the clip, you can see a much larger spicule burst upwards.
SOHO began its Weekly Pick some time after sending a weekly image or video clip to the American Museum of Natural History (Rose Center) in New York City. There, the SOHO Weekly Pick is displayed with some annotations on a large plasma display.
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