Scientists have found that slow, eastward-moving "jet streams" (depicted in yellow) move about 7000 kilometres below the sun's surface. As this plot shows, over time they migrate from near the sun's poles toward its equator. The ones corresponding to Cycle 24 took their time reaching 22° in latitude, matching the prolonged solar minimum seen in recent years. (Illustration: Frank Hill and Rachel Howe/NSO)From New Scientist:
For the past couple of years, our sun has been at the minimum of its 11-year activity cycle. Its face has been virtually spotless for months on end, and there've been no dire alerts of titanic solar storms about to slam into Earth.
The problem is that this "quiet sun" has continued far too long – two years ago, a special task force predicted that the transition from the just-ended Cycle 23 to the upcoming Cycle 24 would come around March 2008. It didn't. (To be fair, there was sharp disagreement within the group at that time.)
Much fanfare accompanied the appearance of a tiny high-latitude sunspot in early 2008, supposedly heralding Cycle 24's arrival. Yet for months and months afterward the sun's face remained spotless.
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