Abstract
Prediction of the Sunspot Curve.—Prof. Dinsmore Alter gave an address at the meeting on Jan. 1 of the British Astronomical Association, in which he described researches on the effects of the different planets on sunspot activity. The method adopted was that described by Prof. E. Brown in vol. 69 of Mon. Not. Roy. Ast. Soc. Prof. Brown noted that the sunspot period was not very different from the period of Jupiter; he found that by combining the tidal influences of Jupiter and Saturn he could get a curve that followed that of the observed sunspot activity very closely. His prediction of a late maximum in 1907 was fulfilled; since then the curve has been carried on to 1955, and its agreement up-to-date with the observed curve is fairly close, though the 1917 maximum is predicted too early. Later, the inner planets were introduced; since tidal action varies as the inverse cube, this partially compensates for their smaller masses; the fact of the tidal influence being appreciable is explained by the approximate equilibrium between gravitation and light-pressure at the sun's surface.
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Our Astronomical Column. Nature 125, 251 (1930). https://doi.org/10.1038/125251a0
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DOI: https://doi.org/10.1038/125251a0