The Sunspot Cycle before the Maunder Minimum
Abstract
Summary. Several hundred observations of giant sunspots have been recorded during the pre-telescopic era, especially in ancient China. The clustering of observations reveals approximately 50 activity maxima during this era, which-in combination with the modern record of sunspot be used to trace the phase of the 11-year sunspot cycle back to the 5th century B.C. Although long-term modulations exist, it is highly likely that the sunspot cycle persisted without interruption throughout this time span. The mean period is equal to 11.135 yr. Key words: solar activity - sunspot periodicity - pretelescopic sunspot observations - solar-terrestrial relations.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- May 1978
- Bibcode:
- 1978A&A....66...93W