From the February 2008 issue

The observer’s personal equation

Add precision to your sunspot counts.
By | Published: February 21, 2008 | Last updated on May 18, 2023
In “How to observe the Sun,” which appeared in the April 2008 issue of Astronomy, I described the Wolf Number, which is the way most astronomers count sunspots. Apart from being fun, sunspot counts provide a gauge of solar activity. Astronomers have kept track of sunspot numbers on a daily basis since the middle of the 18th century.