Why Is The Sun Getting So Lazy?

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An intensitygram of the sun as imaged by NASA's Solar Dynamics Observory (SDO) on July 17, 2013. Note the sunspots to the far left of the image.
NASA/SDO

If you missed the peak of the current solar cycle, you’re not alone. Solar maximum -- the period of time when solar magnetic storms rage -- is apparently a no-show this time around, and likely to be even milder in the next 11-year cycle to come.

A solar eruption sends a wave of plasma hurtling towards Earth on August 1st, 2010.
NASA

That forecast is welcome news for owners and operators of satellites, power plants and polar-flying aircraft, all of which can be impacted by solar storms. Even scientists see a silver lining in this year’s mini solar max.

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“You might think that having a small cycle is a bit of a disappointment to us, but it’s quite the contrary,” said solar physicist David Hathaway, with NASA’s Marshall Space Flight Center in Huntsville, Ala.

“The small cycle -- the smallest that any of us have seen -- puts us in a new regime that allows us to test our theories and our knowledge of how the sun works and reveals new things that the sun is doing,” he said.

The current solar max is the quietest cycle in 100 years. Scientists suspect it may be part of a longer-term, poorly understood secondary cycle that puts the sun in a relative stupor about once every 100 years or so.

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“We had a very long minimum at the beginning of the 1900s, which looks very much like the minimum that we just had,” said Giuliana DeToma, with the High Altitude Observatory, based in Boulder, Colo.

Similar small cycles occurred at the beginning of the 1800s and at beginning of the 1700s, which is as far back as the historical record goes.

“A big question for us as scientists is what causes all of this,” Hathaway said during an American Astronomical Society meeting last week.

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Scientists suspect magnetic fields at the sun’s poles play a key role in determining how many sunspots appear on the surface of the sun during any given cycle. The spots, which are actually regions of twisted magnetic fields, are related to solar flares and solar storms, known as coronal mass ejections.

“It’s the strength of the polar fields that produces the size of the next cycle. Those polar fields are the seeds that produce the sunspots for the next cycle,” Hathaway said.

Scientists are seeing signs that the sun’s polar fields are not strengthening, an indication that the next solar cycle will be even smaller than the current one, known as Cycle 24.

“Time will tell. We haven’t seen the polar fields for Cycle 25 yet. It’s just the trend,” Hathaway said.

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