STUDY OF SUNSPOTS

Evening Post, Volume CXXXI, Issue 97, 26 April 1941, Page 7

STUDY OF SUNSPOTS

THEIR EFFECT ON THE EARTH

The nature of sunspots and their effect on the earth were discussed by "VEr. M. Geddes, director of the Carter Observatory, during a popular astronomical lecture which he gave on Thursday evening in the City Library lecture hall. Since they were first observed some 300 years ago sunspots, he said, had been the subject of in- | tensive study by astronomers. Very ' much has been discovered about them, I but much remained to be found out, I particularly with regard to the effect they have on conditions on the eartn. A sunspot was really a form of cyclonic storm in the gaseous surface of the sun. from which there is an outpouring of material from the interior. Study of spots showed that they followed an eleven-year period of activity, with definite maxima ~nd minima. The last maximum period was in 1937; the next would be about 1948.

Associated with the spots were v-ari-ous other types of disturbances which could be observed only by spectroscopic means. Those mostly occurred in the atmosphere of the sun, and nearly always, in conjunction with spots. They were mostly in the form of eruptions of gas, which ejected material to great heights above the surface. All types of disturbance followed the eleven-year cycle of activity.

During the period of maximum solar activity there was greater radiation from the sun, so that they should ex pect to have variations in climatic conditions en the earth as the activity varied. Such variations would have to Nc world-wide and there was no support for the idea that purely local weather conditions were affected by sunspots. World climate, however, probably was, and there was evidence that rainfall was gi'eater in a maximum than in a minimum year. The growth of trees seems also to be atfected, the tree putting on more growth when sunspots were most numerous. That was shown by •■* study of tree rings. Other correlations were not so certain; attempts had been made to connect world depressions, the trapping of rabbits and other furbearing animals, wine vintages, etc., with the sunspot cycle, but none of those connections had been established with any certainty.

There was, however, a very definite connection between conditions on the sun and such things as the occurrence of auroral displays, interference with wireless transmission, magnetic storms, etc. That, was due to. the radiation from sunspots and other storms of streams of electrified particles and large amounts of ultra-violet light, affecting conditions in the upper atmosphere.

The lecture, which was given under the auspices of the Carter Observa. Tory Board, was illustrated with lantern slides.