for National Geographic News
After a perplexing quiet spell, the sun appears to be stirring—but astrophysicists remain divided about what our star is going to do next.
The sun was expected to hit a low in 2008 as part of its normal 11-year cycle of activity.
But it stayed quiet until very recently, confounding scientists and sparking speculation of a sun-triggered "little ice age."
Solar physicists have denied that potential, saying that today's greenhouse gases have much more influence on global temperatures than the sun. (Watch video about how greenhouse gases are affecting Earth.)
Now the sun appears to be waking up, and the latest prediction from a panel convened by NASA and the National Oceanic and Atmospheric Administration says that the sun is simply a year late.
Solar activity will peak in 2013, the experts say, with 90 sunspots predicted that year.
Still, this would be the lowest peak recorded since the 1920s, and the experts are cautious about their own predictions.
"Go ahead and mark your calendar for [a peak in] May 2013," panel member Dean Pesnell of the Goddard Space Flight Center said in a press statement.
"But use a pencil."
Back to Normal?
Sunspots, solar flares, and so-called zonal flows—streams of plasma akin to Earth's jet streams—are all tracked as signs of magnetic activity on the sun. (See solar activity pictures.)
When the sun is very active, solar storms can disrupt satellites, endanger astronauts, and knock out power grids on Earth.
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