In recent months astronomical observatories have frequently reported huge, black spots marching across the face of the sun, seriously disturbing some kinds of radio transmission on Earth. Sunspot activity this year has been more intense than at any time since 1870. This year bitter warfare is being waged in Spain and China; in 1870 bitter warfare was being waged by Germany and France.
The question of how much effect sunspots have on human affairs has long occupied speculative minds. It is now known that sunspots influence some terrestrial phenomena, including the earth's weather and magnetic field, but beyond that not many scientists have ventured. Thus it means more when one scientist with impeccable credentials declares that sunspots may have a physiological and emotional influence on mankind than when a thousand astrologers and other cultists affirm flatly that they do.
Born 52 years ago in Haverhill, Mass., brisk, self-assured Harlan True Stetson was once a physics instructor at Dartmouth, an assistant professor of astronomy at Harvard, director of the Perkins Observatory at Ohio Wesleyan. He has traveled on five solar eclipse expeditions, belongs to a dozen reputable scientific bodies, including astronomical, physical, optical, geophysical and radio engineering societies. His colleagues have voted him an asterisk in American Men of Science for distinguished research. At present a research associate at Massachusetts Institute of Technology, he has actively developed the new science of cosmic-terrestrial relations, ably popularized his specialty in Man and the Stars, and in Earth, Radio and the Stars. Last week he published Sunspots and Their Effects,* a simply written summary of what is known and what may be ventured on an admittedly speculative basis.
Sunspots appear to be gigantic whirlpools of gas erupting at the solar surface. Many are big enough to engulf dozens of planets the size of Earth. They wax and wane in cycles averaging a little over eleven years, although some intervals have been as short as eight years, others as long as 16. The cause of sunspots is not known, but it is suspected that periodic shifts in the gravitational pulls of the planets may have something to do with it. The whole sun seems to be disturbed by active spots; more heat is radiated by the sun at such times, though the spots themselves are cooler than the surrounding surface.
On Earth, the effect of excess radiation received during sunspot maxima is to evaporate more water, bring on heavier rainfall, and thus paradoxically make the average temperature slightly cooler than during sunspot minima. The eleven-year sunspot cycle has been traced in the growth rings of trees. Stronger ultraviolet radiation accompanies sunspot activity and the aurora borealis displays are more numerous and brilliant, probably due to an increased bombardment of electrified particles. Such influences are now generally accepted as proved. It is the problem of sunspot correlation with such human affairs as stockmarket trends that leads out on the limb of speculation.
The correspondence between sunspots and business activity for the past decade is remarkably close. The boom years of 1928-29 were accompanied by sunspot peaks. Sunspots were at a low ebb in the Depression bottom of 1932, but climbed into 1937 along with Recovery.*