Astronomers working in the years 1645 to 1715 observed many fewer sunspots than they were accustomed to seeing. The lower-than-expected rate of sunspots has since come to be known as the “Maunder Minimum” and a new theory suggests we're about to get another one.

So says Professor Valentina Zharkova of Northumbria University, who presented the theory of the Sun's activity cycle at last week's Royal Astronomical Society National Astronomy Meeting in Llandudno, Wales.

Using data gathered by Stanford University's Wilcox Solar Observatory, Zharkova and co-researchers found what's been described as “magnetic wave components appearing in pairs, originating in two different layers in the Sun’s interior.”

The two waves move around the Sun over a cycle lasting about 11 years. And starting in the year 2030, Zharkova thinks “the two waves [will] exactly mirror each other – peaking at the same time but in opposite hemispheres of the Sun. Their interaction will be disruptive, or they will nearly cancel each other.”

She's predicting the result will be a new Maunder minimum.

“Effectively, when the waves are approximately in phase, they can show strong interaction, or resonance, and we have strong solar activity. When they are out of phase, we have solar minimums. When there is full phase separation, we have the conditions last seen during the Maunder minimum, 370 years ago.”

Maunder minimums are of great interest to those who debate anthropogenic global warming, as many feel that the Sun's influence on climate variability does not get sufficient attention and/or isn't well-modelled. By 2040, if Zharkova and her colleagues are correct, they'll have plenty more data with which to advance such arguments. ®