What is the name of the scale used to count sunspots, developed by Rudolf Wolf? It is the Wolf number.
The Wolf number, also called the relative sunspot number or Zürich number, measures solar activity using both the number of individual sunspots and the number of sunspot groups. Its traditional form is written as R = k(10g + s), where g is the number of groups, s is the number of spots, and k adjusts for an observer's equipment and conditions.
Swiss astronomer Rudolf Wolf developed the method in 1848 while studying historical observations. He also reconstructed sunspot records reaching back to the early telescopic era, helping establish the approximately 11-year solar cycle. The index made observations from different astronomers more comparable.
The name can cause confusion because modern institutions often use “sunspot number” or “international sunspot number” for updated versions of the series. These are continuations and revisions of the Wolf system, not entirely different scales. The Beaufort, Fujita, and Richter scales measure wind, tornado intensity, and earthquakes respectively.