Meaning of Wolf number

Wolf' num"ber

Pronunciation: (woolf Fr. vôlf&hasp), [key]
— Astron. Astron.
  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. Also called
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.