Waiting for solar fireworks to reach a grand finale next year ? Um, sorry, looks like you already missed them. Structures in the sun's corona indicate that the peak in our star's latest cycle of activity has been and gone, at least in its northern hemisphere. The southern hemisphere, meanwhile, is on a sluggish rise to solar maximum and may not hit its peak until 2014.
Such a large asymmetry between hemispheres could be a sign of big changes ahead, says Steven Tobias, a mathematician at the University of Leeds, UK, who models what drives the sun's magnetic field. According to his models, such a situation precedes an extended quiet phase called a grand minimum. "Changes in symmetry are more indicative of going into a grand minimum than the strength of the cycle," he says.
Grand minima can last for decades. The previous one took place between 1645 and 1715, and has been linked to the little ice age in Europe. A new one might also cause localised cold periods, but many climate scientists see a silver lining to such a turn of events: a grand minimum offers ideal conditions for testing the effects of solar variability on Earth's climate...
But Michael Proctor, a solar physicist at the University of Cambridge, is not convinced that this will happen. "This present cycle is similar to the weak one that ended in 1913, and that was followed by a strong cycle," he says.
Only time will tell.
Full New Scientist Sept. 26, 2012 article (linked from the National Solar Observatory):
Sunspot cycle and double peak graphics sourced from nasa.gov: