Scientists Crack the Mystery of the Missing Sunspots.
Scientists Crack the Mystery of the Missing Sunspots.
Presented by Science@NASA
Back in 2008, something funny happened to the sun. All of its spots disappeared!
For nearly two years, in '08 and '09, sunspots were extremely rare; the face of
the sun was utterly blank for weeks and months on end.
Astronomers call such an event "solar minimum," and this was a big one. Solar
activity dropped to hundred-year lows. Earth's upper atmosphere cooled and
collapsed. The sun’s magnetic field weakened, allowing cosmic rays to penetrate
the Solar System in record numbers. Solar physicists openly wondered, where have
all the sunspots gone?
The answer was published in the March 3rd edition of Nature. Lead author,
Dibyendu Nandi, of the Indian Institute of Science Education and Research
explains what happened: "Rivers of the fire on the sun disrupted the formation
of sunspots."
Just as the oceans of the Earth have vast and powerful currents that straddle
the globe, so does the sun. Except the sun's great currents are made of hot
plasma instead of cold water. Sometimes we call them "rivers of fire." And these
rivers play an important role in the life cycle of sunspots. "The 'rivers of
fire' drag old decaying sunspots down into the sun's interior where they are
re-animated by the sun's magnetic dynamo," explains Nandi.
"These reborn sunspots pop-up to the surface for the next solar cycle."
According to the groups computer models, the sun's current system sped up and
started dragging old sunspots through the dynamo so fast, they didn't have time
to be fully re-animated. And that's what caused the deep solar minimum of
'08-'09.
Now things are getting back to normal, and solar activity is picking up. Big
sunspots and solar flares have returned. But when will they disappear again? The
answer lies in a river of fire.
For more information about sunspots and other NASA heliophysics research, please
visit science.nasa.gov
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