Credits: SILSO Data - Royal Observatory of Belgium, Brussels |
Yet, this important change to one of science’s most fundamental measurements went literally unnoticed (HERE & HERE) Two sunspot record time series were recalibrated: The first is the traditional International Sunspot Number (ISN) record most people are familiar with. The second is the more physically meaningful group number. Groups have always been counted as part of the ISN. The newly released group number update redefines and corrects defects in the original 1998 version. The newly rebuilt group number time series shows that solar activity is considerably more ‘even’ over its 405-year history than previously thought. Formerly, it looked as though sunspot activity in the past was much weaker than at present, especially prior to 1890. Counting inconsistencies artificially created that non-existent effect. The rebuilt record contains four distinctive dips in solar activity that occur roughly every 100 years.