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Monday, November 11, 2013

oddly out of sync

Normally, the sun's magnetic north and south poles change polarity every 11 years or so. During a magnetic-field reversal, the sun's polar magnetic fields weaken, drop to zero, and then emerge again with the opposite polarity. As far as scientists know, the magnetic shift is notable only because it signals the peak of the solar maximum, said Douglas Biesecker at NASA's Space Environment Center.
But in this cycle, the sun's magnetic poles are out of sync, solar scientists said. The sun's north magnetic pole reversed polarity more than a year ago, so it has the same polarity as the south pole.
"The delay between the two reversals is unusually long," said solar physicist Karel Schrijver at the Lockheed Martin Advanced Technology Center in Palo Alto, Calif.
Scientists said they are puzzled, but not concerned, by the unusual delay. They expect the sun's south pole to change polarity next month, based on current satellite measurements of its shifting magnetic fields.