“"It has long been though that the sun is a constant star of regular and repeatable behavior. Measurements of the radiative output, or solar constant, seem to justify the first assumption, and the record of periodicity in sunspot numbers is taken as evidence of the second. Both records, however, sample only the most recent history of the sun."Eddy, J.A., "The Maunder Minimum", Science 18 June 1976: Vol. 192. no. 4245, pp. 1189 - 1202, PDF Copy”