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| Solar activity goes in a roughly 11-year cycle. Sunspots are the visible signs of that activity, and they are the sites from which massive solar storms lift off. The past two years have marked the lowest low in the cycle since 1913, and for a while scientists were wondering if activity would ever pick back up.
During 2009 so far, the sun has been completely free of spots about 77 percent of the time. NASA researchers last month said quiet jet streams inside the sun were responsible, and that activity would soon return to normal.
Prior to the low-activity period, astronomers had been predicting that the next peak in solar activity, expected in 2013, might be one of the most active in many decades. That forecast was recently revised, however, and scientists now expect the next peak to be modest.
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