Worlds of David Darling
Encyclopedia of Science
Home > Encyclopedia of Science

relative sunspot number

A number devised by Rudolf Wolf of Zurich in 1849 to describe sunspot activity. Sometimes called the Wolf number, it is defined as:

R = k (10g + f)

where R is the sunspot number, k is a constant depending on the instrument used, g is the number of disturbed regions, and f is the total number of sunspots.

Related category