sunspot cycle

American  

noun

Astronomy.

1. the cycle, averaging in duration slightly more than 11 years, in which the frequency of sunspots varies from a maximum to a minimum and back to a maximum again.

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Example Sentences

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

From Science Daily

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.

From Science Daily

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

From Science Daily

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.

From New York Times

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

From New York Times