Abstract
MAGNETIC STORMS AND SUNSPOTS.—Under the title “Large Magnetic Storms and Large Sunspots,” in Monthly Notices Royal Astron. Soc., May 1928, W. M. H. Greaves and H. W. Newton discuss the occurrence of sunspots at the time of magnetic storms for the 54 years 1874–1927. Magnetic disturbances are included for which the range in declination was at least 1°, or that in H.F. or V.F. at least 3007γ. Sunspots of mean area 500 millionths of the sun's hemisphere or greater are considered significant in a comparison with magnetic storms. The analysis shows that out of 60 magnetic storms, 36 commenced within 4 days of the central meridian passage of a large spot (chance would give about 17 coincidences between spot and storm); 8 other storms commenced within 4 days of the central meridian passage of a region of the sun which had previously been markedly disturbed; in 7 other cases the storm was followed one solar rotation later (about 27 days) by the transit of a large spot which had developed in the interval; the remaining 9 storms occurred when neither spots nor faculse were unusual. When the largest magnetic storms were examined (D>1½° or H.F. or V.F.>5007γ), it was found that 15 out of 17 storms occurred in conjunction with a large spot; the sixteenth storm took place one solar rotation after the central meridian passage of a large spot, while the seventeenth storm preceded by one solar rotation the central meridian passage of another large spot (see NATURE, May 26, p. 842). These figures show that individual storms and individual spots are associated with each other more often than can be ascribed to chance, and that the tendency to association is greater for the largest storms:
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Our Astronomical Column. Nature 122, 183 (1928). https://doi.org/10.1038/122183a0
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DOI: https://doi.org/10.1038/122183a0