Harbinger of Sunspot Cycle 24 (December 21, 2007)
Hi-res TIF image (3.3M)
SOHO has observed (Dec. 13, 2007) what may be the first indication of a "reversed" magnetic polarity region when compared to the current solar cycle, something scientists consider to be a crucial indicator that the new sunspot cycle is about upon us. This so-called plage region did not have a strong enough magnetic field to form a sunspot, but scientists believe that it may nevertheless stand as an icon that the old cycle is ending and a new one, Cycle 24, is about to begin. Sunspots appear in groups with north and south polarities just like a magnet. In magnetic images of the Sun taken (by SOHO's MDI instrument) during the last solar cycle, sunspots in the northern hemisphere of the Sun have had white areas preceding the black; in this new spot, we can clearly see that black precedes white. (This orientation is reversed in the southern hemisphere.)
Solar cycles (in which the general level of solar activity is measured by numbers of sunspots) last from 9.5 to 13.5 years and have been recorded since the 1700's. The video clip fades from an extreme ultraviolet image of the Sun to zoom in on a magnetic image of the active region to show the correlation between the two.
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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