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

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 • Nov. 28, 2023

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 • May 28, 2021

Assuming an average sunspot cycle of 11 years, how many revolutions does the equator of the Sun make during that one cycle?

From Textbooks • Oct. 13, 2016

Then there is the sun's variability, mostly in the form of the 11-year sunspot cycle.

From Slate • Sep. 9, 2012

In general the nature of the 33-year periods seems to be identical with that of the 11- or 12- year sunspot cycle, on the one hand, and of historic pulsations on the other.

From Climatic Changes Their Nature and Causes by Huntington, Ellsworth