SOLAR ACTIVITY

Timaru Herald, Volume CXLIII, Issue 20929, 7 January 1938, Page 11

SOLAR ACTIVITY

SUNSPOT GROUPS LAST YEAR EXCEPTIONAL NUMBER By Telegraph—Press Association WELLINGTON, January 6. “The year just ended has been an exceptional one as regards solar activity, no less than 265 distinct groups of sunspots having been observed from January 1, 1937, to December 29, the last day of the year, on which an observation was recorded,” states Mr G. V. Hudson, Karori. “At the peak of the last solar maximum, (year 1927) only some 126 groups were observed, but it should be explained that when the spots are very numerous it is impossible for an amateur observer to identify the same group if it appears on the sun’s disc a second time. Sunspots change rapidly f:im day to day, and comparatively speaking few last for more than a single rotation of the sun (approximately 26 days), thus the chances of recording the same spot twice over are small. “Even allowing that 65 spots were observed twice over (an extremely liberal estimate), we still have a total of 200 groups for 1937 as against 126 for '927. On no single day in 1937 was the sun’s disc observed to be entirely clear of spots, although only one minute spot was visible on September 2. "Great sunspots exceeding 100,000 miles in length were observed on the following dates.—January 28-Febru-ary 7, a very large sunspot visible, but no definite particulars recorded; April 21-28, two spots, both about 150,000 miles long and over 40,000 miles in breadth; June 18, a group nearly 400,000 miles long, but spots small and very scattered; July 23-31, a huge spot , fully 200,000 miles long and 85,000 miles in width, visible to naked eye; August 11-August 17, a group about 130,000 miles long; another monster spot 200,000 miles long and 88,000 miles broad was visible from September 28 i-itil October 7, also clearly seen with the naked eye; December 19, a scattered group of spots, mostly of moderate size, extending to a total length of about 200,000 miles.

“The faculae during 1937 have not been so pronounced as is usual during periods of great spot activity.

“Since the middle of October there has been a marked decline in solar activity, but it would be premature to assume that we are entering on the minimum phase, which is not due until about 1944. The last solar minimum occurred in 1933."