Sept. 26, 2008 -- Our sun has attracted a bit more attention than usual lately, not because it needs a government bailout, but because its usual 11-year cycle seems a bit off.
This may not seem so important, but the sun's behavior directly impacts what happens on Earth, particularly our satellite-enabled, digital-dependent corner of the planet. Solar storms can and have shut down GPS receivers and knocked out power girds. Solar energy, or what is called irradiance, even affects Earth's climate.
So when a patch of dark spots broke out on the sun's face this week -- the first true sunspots in two months -- scientists got an inkling of what to expect during the upcoming solar cycle.
"We really won't know for sure until we are a couple of years into the new cycle," NASA solar physicist David Hathaway told Discovery News. "But the appearance of this spot might very well herald that we have passed through solar minimum."
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The sun's quiescent stage has been a long one, at least compared to its most recent cycles. Still, it's nothing like the minimum period that began in 1645, when the sun stopped making spots for 70 years. So far, Solar Cycle 23, which is ending, has lasted 142 months -- about a year longer than average, but still well within statistical norms.
The late start to Solar Cycle 24 may indicate the solar maximum won't be as intense as some physicists expect. A scientific panel tasked last year to make a prediction ended up split.
Half the scientists expect the upcoming cycle will be a doozy, with frequent and strong geomagnetic storms that will reach a peak in October 2011 with an average of 140 spots appearing during the month of maximum activity.
The other half expects the sun to take a bit of a breather, with roughly 90 spots on average during the month of August in 2012, representing solar maximum.
"We're all pretty entrenched in our position," said Douglas Biesecker, the NOAA scientist chairing the panel. "One camp will clearly have egg on its face when this is over."
The prediction is far from mere sport. Heightened solar activity, which is tied to the number of sunspots, increases risks to power grids, military, civilian and airline communications, GPS signals, cell phones and even ATM transactions.
"A big cycle certainly costs money in terms of damaged goods, damaged satellites, the impact on airlines that fly routes over the poles," Hathaway said.
And it's still a bit early to say for sure Cycle 24 has begun, he added.
"It's starting off with such a whimper. We need three or four months behind us before we know if the old cycle has died off and the new one has begun."
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Irene Klotz's blog: Free Space
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