Correlation between Solar Activity and Brightness of Jupiter's Great Red Spot

Abstract

THE “pronounced correlation” claimed by Graf, Smith and McDevitt1 between Zurich sunspot numbers and the relative brightness of the Jovian red spot is not readily apparent in their Fig. 1. It is therefore worthwhile to calculate r, the actual correlation coefficient between the two functions plotted. Using values scaled from Fig. 1, the result is r=0.27. This value of r implies2 that only 7.5 per cent of the variation of the red spot can possibly be attributed to the solar activity responsible for the Zurich sunspot number. For the fifty values of the two functions compared, however, a correlation coefficient of 0.27 is not significant at the 5 per cent confidence level usually adopted in studies of this kind. In view of these considerations the relationship between the two phenomena will remain unestablished until better correlations can be obtained.