Wolf number

American  

[woolf, vawlf] / wʊlf, vɔlf /

noun

Astronomy.

1. a number indicating the degree of sunspot activity on the sun as a factor of observer idiosyncrasies, the number of sunspot groups, and the number of individual sunspots.

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Etymology

Origin of Wolf number

1975–80; after Rudolf Wolf (1816–93), Swiss astronomer

Example Sentences

“The sharp departure from wolf number increases in past years is cause for serious concern,” said Amaroq Weiss, wolf advocate at the Center for Biological Diversity.

From Washington Times

That began to change when, in 1848, the Swiss astronomer Rudolf Wolf began making systematic observations and developed a formula that is still used today to calculate the international sunspot number, also known as the Wolf number, which gives a measure of how solar activity is changing over time.

From Nature