Sunspots come and go, but recently they have mostly gone. For centuries, astronomers have recorded when these dark blemishes on the solar surface emerge, only to fade away after a few days, weeks or months. Thanks to their efforts, we know that sunspot numbers ebb and flow in cycles lasting about 11 years.
THIS STORY
Why is the sun losing its spots?
Scientists find a big drop in the strength of solar magnetic fields
But for the past two years, the sunspots have mostly been missing. Their absence, the most prolonged in nearly 100 years, has taken even seasoned sun watchers by surprise. "This is solar behavior we haven't seen in living memory," says David Hathaway, a physicist at NASA's Marshall Space Flight Center in Huntsville, Ala.
The sun is under scrutiny as never before, thanks to an armada of space telescopes. The results they beam back are portraying our nearest star, and its influence on Earth, in a new light. 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. The big question is: What?
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. When NASA and the European Space Agency launched the Solar and Heliospheric Observatory almost 15 years ago, "understanding the solar cycle was not one of its scientific objectives," says Bernhard Fleck, the mission's project scientist. "Now it is one of the key questions."
Sunspots are windows into the sun's magnetic soul. 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. Any changes in sunspot numbers reflect changes inside the sun. "During this transition, the sun is giving us a real glimpse into its interior," says Hathaway.
When sunspot numbers drop at the end of each 11-year cycle, solar storms die down and all becomes much calmer. This "solar minimum" doesn't last long. Within a year, the spots and storms begin to build toward a new crescendo, the next solar maximum.
What's special about this latest dip is that the sun is having trouble starting the next solar cycle. The sun began to calm down in late 2007, so no one expected many sunspots in 2008. But computer models predicted that when the spots did return, they would do so in force. Hathaway was reported as thinking the next solar cycle would be a doozy: more sunspots, more solar storms and more energy blasted into space. Others predicted that it would be the most active solar cycle on record.
The trouble was, no one told the sun.
The first sign that the prediction was wrong came when 2008 turned out to be even calmer than expected. That year, the sun was spot-free 73 percent of the time, an extreme dip even for a solar minimum. Only the minimum of 1913 was more pronounced, with 85 percent of that year clear.
As 2009 arrived, solar physicists looked for some action. They didn't get it. The sun continued to languish until mid-December, when the largest group of sunspots to emerge in several years appeared. Even with the solar cycle finally underway again, the number of sunspots has so far been well below expectations. Something appears to have changed inside the sun, something the models did not predict. But what?
The flood of observations from space- and ground-based telescopes suggests that the answer lies in the behavior of two vast conveyor belts of gas that endlessly cycle material and magnetism through the sun's interior and out across its surface. On average it takes 40 years for the conveyor belts to complete a circuit.
When Hathaway's NASA team looked over the observations to find out where their models had gone wrong, they noticed that the conveyor-belt flows of gas across the sun's surface have been speeding up since 2004.
SCARY...DO YOU THINK THIS HAS ANYTHING TO DO WITH ACIENT MAYAN PREDICTIONS OF 2012??
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