SOLAR ACTIVITY

Press, Volume LXXVI, Issue 22909, 4 January 1940, Page 10

SOLAR ACTIVITY

SUNSPOT OBSERVATIONS IN 1939 - During the year just ended the sun was observed in Wellington on i6t> days, andon none of these occasions was the disk entirely clear of spots: reports Mr G. V. Hudson, Karon. On December 6, however, only one small spot was visible, this being the lowest number for any observation taken during the year. One hundred and eightyfive - distinct groups of sunsppts were recorded, compared with '2,06 in i-»a a - A few-•sunsppts persist for more than a single rotation of the sun (about 26 days)," and ih such cases the same group may sometimes be counted twice ° V Sunspots more than 100,000 miles in length, which are usually, visible to the naked eve through smoked glass, were observed on the following dates: — April 22-May 1: July 4-14, two large groups in view simultaneously: August 29-September 5; September 5-16; and November 14-20. Since-November 20 there has been a very marked decline m solar activity. . ■ ■ Many astronomers estimate that sun.spot activity was at its maximum about the middle; of 1937, but the fact

remains that the year 1938 was also a period of very intense activity. It is generally considered that the last maximum is the greatest since 1870, or six solar cycles ago.' ~ As anticipated, a moderate reduction in sunspois 'has. taken place during 1939, but a greater decline may be expected in 1940. The next solar minimum is due about 1944.