Sunspots Erupt Suddenly
By Robert Roy Britt
Senior Science Writer
posted: 26 March 2008
11:54 am ET After months of relative quietude, a trio of new sunspot groups appeared this week and they are all growing rapidly.
But there's something strange about these spots.
Sunspots are cool regions of intense, twisted magnetic activity at the solar surface. They act like caps on the upwelling of energy, and when the caps pop, flares of radiation and ejections of charged particles are unleashed. Major solar storms can disrupt communications on Earth and even disable satellites.
The sun goes through an 11-year cycle of activity. The last peak, when sunspots were common and flares frequent, was in 2001 and 2002. The new cycle, Solar Cycle 24, began recently, scientists figure, based on a sunspot with reversed polarity appearing. But pinning down exactly when the shift occurred has proven challenging — it might have been in 2006, sun-watching scientists reported initially, or perhaps 2007, they later said.
Adding to the tangle of understanding, the new sunspots have a magnetic polarity consistent with Solar Cycle 23 rather than the new cycle, proving yet again that much remains to be learned about the temperamental sun.
One of the new sunspots, No. 989, kicked up a moderate solar flare Tuesday. NOAA forecasters put the odds at 50-50 for additional moderate flares today.
Solar storms sometimes generate colorful auroras above Earth's polar regions. No significant auroral displays are expected this week, however.
Though forecasts vary wildly, some scientists predict Solar Cycle 24 will be intense. If so, "it could have significant impacts on telecommunications, air traffic, power grids and GPS systems," according to a NASA statement issued in December.