sunspot cycle

Their work indicates that the maximum intensity of solar cycle 25, the ongoing sunspot cycle, is imminent and likely to occur within a year.

In 1935, Swiss astronomer Max Waldmeier discovered that the faster the rate of rise of a sunspot cycle the stronger its strength, so stronger cycles take less time to rise to their peak intensity.

This relationship has often been utilised to forecast the strength of a sunspot cycle based on observations of its early rising phase.

The 11-year sunspot cycle, they say, based on an analysis of 140 years of solar measurements, belies a more fundamental 22-year Hale cycle, named after its discoverer, George Ellery Hale.

“Sunspot Cycle 25 could have a magnitude that rivals the top few since records began,” Dr. McIntosh said in late April.