Abstract
SOLAR ACTIVITY IN 1888.—The behaviour of the various orders of solar phenomena, spots, faculæ, and prominences, during the past year has shown most conclusively that the minimum must now be very near at hand, and it may with confidence be expected to fall either towards the end of the current year or else, early in 1890. The spots especially have shown unmistakable signs that the trough of the eleven-year curve is nearly reached, for they have been few in number, small in size, and low in latitude, and there have frequently been considerable intervals in which no spots have been seen at all. The remarkable depression of October 31 to December 9, 1886 (see NATURE, vol. xxxv. p. 445) has in some respects indeed not been equalled during 1888, but there has been no such long period of unbroken quiescence since the minimum of 1879 as that recorded in last October, when in the three weeks October 4—24 not a single spot was seen, whilst there were but three days showing spots in the thirty-seven from September 29 to November 5. Other spotless or nearly spotless periods in 1888 were January 23—30, February 4—17, March 1—8, March 24—31, April 6—15, April 30 to May 10, May 24 to June 8, June 30 to July 12, July 18 to August 7, and December 22—31. And not only were there these long and numerous breaks in the spot manifestations, but when spots were seen they were almost always small in size and few in number. On not a single day in the year did the total spotted area amount to 1/1200 of the surface of the visible hemisphere; on only eight days did it exceed 1/2000. The mean daily spotted area for the year amounted only to about 9 parts in 100,000, or almost precisely the same as in 1877. In January there was a feeble but fairly sustained display of activity up to the 22nd; there was a similar but less lasting manifestation at the end of February, and again about the middle of March. April was very quiet, but May 11—23 yielded a fair show of spots, May 14 giving the largest area of the year. August 28 to September 9 was also a fairly active time; but the most prolific month as to entire spotted area, though not as to number of spots, was November, following immediately after the longest period of entire quiescence. The last ten days of last year, and the first two months of the present, have been exceedingly barren.
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Our Astronomical Column . Nature 39, 448–449 (1889). https://doi.org/10.1038/039448a0
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DOI: https://doi.org/10.1038/039448a0