|A sun without any sunspots, photo taken on July 17, 2014|
Photo from here.
Here is the reference for the press release.
The sun's activity varies over a solar cycle of roughly 11 years (22 years if the polarity of sunspots is considered). To date, the cycle has been analyzed the phenomenon in terms of a dynamo driven by fluids convecting deep within the sun. A dynamo is a fluid dynamic condition of convection within a body that moves a convecting, rotating, and electrically charged fluid around within a body. Traditionally, solar physicists attempt to explain the measured properties of the sun and their variability with a single dynamo within the sun. We had a prolonged drought of sunspots over the past two years, but there are a few now and they emit strong enough particles to cause some concerns about telecommunications.
|Sun configuration on July 13, 2015|
From space weather.com
Valentina Zharkova is presenting a paper at the National Astronomy Meeting in Llandudno that proposes two dynamos: the traditional one deep in the sun, and another close to the surface. Each dynamo gives a periodicity of about 11 years, but they are slightly different and offset in time. The idea is that if they coincide appropriately, the effects will be large. The data are based on observations from 1976-2008. Running the model into the future, the model predicts that during Cycle 25, which peaks in 2022, and into cycle 26 (2030-2040) the waves due to the two dynamos will become exactly out of synch. This would result in a reduction in solar activity equivalent to the Maunder minimum of the 1600's, 370 years ago.
It will be interesting to follow this because the implications are enormous for global stability and economics. I recommend the great website space weather.com to follow solar events.
For a bit of prehistory, and my interest in the sun, my first published paper was a documentation of the evolution of sunspot groups, in the inaugural edition of a new journal Solar Physics: Zirin, Harold and Werner, Susan, Detailed analysis of flares, magnetic fields and activity in the sunspot group of Sept. 13-26, 1963, Solar Physics, 1, pp. 66-100, 1967,