A High Wind in the Heliosphere? (September 5, 2008)
Hi-res TIF image (2.6M)
An elongated coronal hole can be seen (diagonally across the Sun's center) in this September 3, 2008 image by SOHO. Coronal holes appear as darker areas when viewed in this extreme UV wavelength (195 Angstroms). Solar wind from coronal holes that are observed to the right of the Sun's central line connects best with Earth. Since coronal holes are 'open' magnetically, strong solar wind gusts, faster than other solar wind, escape from them and carry solar particles out to our magnetosphere and beyond. Winds from this hole are streaming through space at 450 km per second. Talk about hurricanes!
The solar wind streams take several days to travel from the Sun to Earth. Holes like this appear fairly regularly, though this one is probably larger than most. The magnetic field lines in a coronal hole open out into the solar wind rather than connecting to a nearby part of the Sun's surface. High-speed solar wind can have a direct effect on "space weather" near Earth so that aurora may appear in higher latitudes in a few days.
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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