Coronal Hole Déjà vu? (March 7, 2008)
Hi-res TIF image (1.4M)
SOHO has spotted an expansive coronal that has apparently returned for a repeat performance right on schedule. This darker area (as seen in extreme UV light) has just crossed the centerline of the Sun and will be streaming solar wind towards Earth. This same area was featured on this site as seen by STEREO one month ago when it was just crossing the centerline. Here it is shown as taken by SOHO on Feb. 13, 2008 and again on Mar. 12, 2008. Since the Sun rotates about every 27 days on average and its position stretched across the lower half of the Sun has remained virtually unchanged, we can be fairly sure that this is the same coronal hole as last time around. They have been known to last several months at times. It should be noted that the darker area reaching out to the right and up is probably a filament channel and not part of the coronal hole.
Since coronal holes are 'open' magnetically, strong solar wind gusts escape from them and carry solar particles out to our magnetosphere and beyond. Solar wind streams take several days to travel from the Sun to Earth. 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. This hole is almost certainly the reason people living at higher latitudes have been treated to some colorful aurora displays the past 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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