aat Acta Astrophys. Tau. Acta Astrophysica Taurica 2712-925X Kiselev Nikolai Nikolaevich, Mosсow, settlement Moskovskii, Tat'yanin Park Str., 12, Moscow, Russia. RU 58 10.34898/aat.vol4.iss3.pp16-20 To the 80th anniversary of V.A. Kotov Magnetic cycles of the Sun inferred from its mean magnetic field Kotov Valery Crimean Astrophysical Observatory, Nauchny, 298409 19 11 2023 4 3 16 20 27 01 2023 Copyright (c) 2026 Kotov V. 2026 Valery Kotov The metadata for this submission is licensed under a Creative Commons Attribution 4.0 International License. Copyright and publishing rights for texts published in Acta Astrophysica Taurica is retained by the authors, with first publication rights granted to the journal.Texts are free to use with proper attribution and link to the licensing (Creative Commons Attribution 4.0 International).

Over the past 55 years, the Crimean Astrophysical Observatory, the Wilcox Solar Observatory, and five other observatories of the world registered the mean magnetic field of the Sun observed as a star (in all, about 29 thousand daily values of the longitudinal field strength of the visible solar hemisphere were acquired from 1968 through 2022). This field varies with two periods: 21.5(7) years, corresponding to the Hale cycle P H   = 22 . 14 ( 8 ) years; and a period of 7.08(10) years, which is about three times shorter than P H   (the precise ratio, 3.13(5), reminds of the Archimedes approximation, 22:7, of the π number). A special analysis of the solar polar fields (Stanford data for 1976-2022) proves the reality of the magnetic 7-year cycle of the Sun, whose nature is unknown

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