SOLAR ACTIVITY

Dominion, Volume 34, Issue 84, 3 January 1941, Page 6

SOLAR ACTIVITY

Sunspot Observations In 1940 151 DISTINCT GROUPS A report on sunspot observations in 1940 has been forwarded by Mr. G. V. Hudson, Karori, who writes:— During the year just ended, the sun was observed at Karori on 152 days, and on none of these occasions was the disc completely clear of spots, though on May 3 only one extremely small triple spot was visible. One hundred and fifty-one distinct groups of sunspots were recorded in 1940 as compared with 185 in 1939, representing a decrease of 3-1. Further decreases in solar activity may be expected as we approach the next minimum phase due about 1944. A few sunspots persist for more than a single rotation of the sun (about 26 days), and in such cases the same group may sometimes be counted twice over. On the other hand, spots must, at times, be missed altogether, owing to the prevalence of cloudy weather. Sunspots more than 100,060 miles in length, which are usually visible to the miked eye through smoked glass, were observed on the following dates: January 5-9, March 3-7, March 23-30, August 16-21, and October 9-14, but no very large sunspot has been recorded since that date.