Tuesday, June 22, 2010
Sunspot numbers flow in cycles lasting about 11 years. But for the past two years, the sunspots have been missing. Their absence, the most prolonged in nearly 100 years, has taken seasoned sun watchers by surprise. The sun is under scrutiny with an armada of space telescopes. Sunspots and other clues indicate that the sun's magnetic activity is diminishing and that the sun may even be shrinking. Together, the results hint that something profound is happening inside the sun.
Groups of sunspots forewarn of gigantic solar storms that can unleash a billion times more energy than an atomic bomb. Fears that these giant eruptions could create havoc on Earth and disputes over the sun's role in climate change are adding urgency to these studies.
They form where giant loops of magnetism, generated deep inside the sun, well up and burst through the surface, leading to a localized drop in temperature that we see as a dark patch. When sunspot numbers drop at the end of each 11-year cycle, solar storms die down and all becomes much calmer.
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