Not huge, but new-cycle sunspot group 1007 emerged on Halloween and marched across the face of the sun over a four-day period in early November 2008.
Credit: the Solar and Heliospheric Observatory (SOHO)
After more than two years of very low sunspot activity and hardly any flares, the sun is ramping up activity now.
The sun's activity ebbs and flows on a roughly 11-year cycle. It can range from very quiet to violent space storms that knock out power grids on Earth and disrupt radio and satellite communications. The last peak was in 2000, and scientists have in recent months figured the low point was occurring. Fresh sunspots during October suggest the corner has been turned.
"I think solar minimum is behind us," said David Hathaway of NASA's Marshall Space Flight Center in Huntsville, Ala. "Last month we counted five sunspot groups." he says.
Sunspots are cool areas on the solar surface where magnetic energy is bottled up. While five groups is not extraordinary, it is significant in comparison to the months of virtually no spots.
"This represents a real increase in solar activity," Hathaway said in a statement today.
The next cycle of activity, which we are presumably now in, is called Solar Cycle 24. The transition, however, is gradual. Hints of it started last year. But the sun holds many secrets that prevent scientists from knowing exactly when, why or how the transition occurs. Spots from the old and new cycles differ in their latitude and magnetic polarity.
From January to September, the sun produced 22 sunspot groups, and 82 percent of them belonged to old Cycle 23. Four of the five cycles in October belonged to Cycle 24.
On Nov. 3 and again on Nov. 4, a sunspot numbered 1007 unleashed a series of B-class solar flares. These relatively minor events were strong enough to cause fades and surges in ham radio transmissions on Earth. Bigger flares, which could happen any time but will be more likely when the next peak comes in a few years, can disable satellites.
"We're still years away from solar maximum and, in the meantime, the sun is going to have some more quiet stretches," Hathaway said.
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