Prediction of the Dates and Intensities of the Next Two Sunspot Maxima

Abstract

THERE is still no satisfactory method of predicting sunspot activity beyond the current cycle, but two recent papers have provided new evidence that sunspot activity may be controlled by the positions of the planets. This possibility was discussed more than 50 years ago by Brown¹, and later by Schuster², and was adopted as a basis for prediction by others. The recent evidence has been provided by Jose³ and by Wood and Wood⁴. Jose³ has shown that the rate of change of the angular momentum of the Sun about the centre of mass of the solar system exhibits a 178-year periodicity which can plausibly be correlated with sunspot activity. Jupiter and Saturn are the planets mainly responsible. Wood and Wood⁴ have suggested that the rate of change of angular acceleration of the Sun, which is controlled mainly by the inner planets, shows resemblances in detail to the sunspot numbers. These new results, although not immediately useful in predicting solar activity, do point towards the conclusion that variations in solar activity have a causal basis. If so, an empirical law for the variation of sunspot numbers should eventually be found.