CAUSE OF SUNSPOTS

Bay of Plenty Beacon, Volume 11, Issue 80, 15 September 1947, Page 6

CAUSE OF SUNSPOTS

INTERESTING SIDELIGHTS THEORY OF ORIGIN UNCERTAIN Sidelights on sunspots, a large group of which is at present near the centre of the sun, were obtained from Mr I. L. Thomsen, director of the Carter Observatory at Kelburn, by a contemporary recently. The theory of their origin, he said, was uncertain, but it was believed that sunspots were the result of a cyclonic storm in the outer layer of the sun’s atmosphere. This storm, however, could be the direct result of some internal atomic transformation of the sun itself.

Reliable records, kept since 1755, showed that the average frequency of peak occurrence of sunspots was 11 years. The present manifestation, said Mr Thomsen, was probably a peak one, but this could not be confirmed for several months. He emphasised that, although it was a very active group, it contained no extremely large spots. The largest sunspots ever seen appeared at the beginning of last year. Its area was approximately nine times that of the earth. The largest spot at the moment was about 20,000 miles in diameter and the smallest about 1000 miles. Their lives varied from a few hours in the small variety, to upwards of 100 days in the giants. Sunspots were visible because their temperature was about 4000 degrees compared with the sun’s general surface temperature of 6000 degrees. Consequently they appeared as small, dark smudges, with heavy black centres, or nuclei, against the incandescent background of the sun. Helium Nuclei The sunspots, said Mr Thomsen, ejected particles, which were probably the nuclei of helium atoms, and when these hit the upper atmosphere of ■ the earth, about 100 miles upward, they upset the earth’s currents of electricity and often promoted vivid displays of the Aurora Australis. When a sunspot group became very active its manifestations were also transmitted to the outer layers of the sun’s atmosphere and angry, red hydrogen flares were visible through an instrument called the spectrohiliscope. These flare disturbances had a sudden effect on the earth’s upper atmosphere and were responsible for. radio fade-outs such as had been experienced during the past few weeks.

Mr Thomsen said the disturbances created by sunspot activity were entirely divorced from the effects of electrical storms. Several people had asked him whether thunder and lightning could be expected as a result of the sunspots. Radio trouble and possible auroral displays were themnly effects likely to be noticed.