SUN’S MYSTERY

Evening Star, Issue 22883, 15 February 1938, Page 4

SUN’S MYSTERY

HEW METHODS OF PHOTOGRAPHY An aeroplane flying over Peru at a height of nearly 30,000 ft during the time a total eclipse of the siin was in progress took some photographs which have revolutionised the astronomer’s conception of the atmosphere surrounding the sun. Hitherto all photographs have been taken from the ground during the brief times of the sun’s total eclipse, and these have shown the sun’s disc to be surrounded by a chaplet of pale bluish light shooting shafts of paler light tens of thousands of miles out into solar space. This phenomenon, known as. the corona, was supposed to be the limit of the sun’s atmosphere. But these Peruvian photographs, taken in the clear upper air, undimmed by the dust-laden atmosphere close to the earth, show that the sun is surrounded by a globular halo of pale golden light extending far beyond the corona. Indeed, the size of this newlydiscovered envelope is computed to be 27 times as large as the sun and its corona; in other words, to have a volume of at least 20,000,000 miles! We know pretty accurately the composition of the sun, says an authority, the spectroscope showing it to possess every element found on earth; but we have not yet discovered the composition of tlje corona, and it is to learn this that most of the efforts of the scientific expeditions that take observations at successive total eclipses are directed. Scientists’ theories about the effect of sunspots upon this earth have been based upon the theory that the corona was the ultimate atmosphere surrounding the sun. The new knowledge thatthe sun’s atmosphere extends millions and millions of miles farther than was suspected upsets a whole lot of calculations—even that of the age of the sun itself, since we have no idea of the cooling effect upon the sun of this unsuspected enveloping shell. Einstein’s theory of relativity, too, may have to be revised, -since his calculations also were made without taking into account this super-gigantic mass of vapour. It is clear that these startling pictures will change the methods to be adopted by future photographers of an eclipse. Instead of taking photographs from the ground, they will take them from aeroplanes, even from unmanned balloons floating high in the stratosphere. By these means not photographs only, but spectrographs also could be taken that might reveal facts of incomparable value to astronomers and scientists. Before the sun’s radiation reaches the earth it suffers absorption in the ultraviolet and infra-red ends of the spectrum, due to certain gaseous constituents of the earth’s upper air. - Photographs and -spectrographs taken above the influence of these absorbing gases should lay bare secrets hitherto locked away from the eyes of science. As man progresses with his subjection of the air giant liners equipped with every device of science for observing and "recording an eclipse, will float high up in the stratosphere wresting from the sun knowledge which may revolutionise our present puny methods of utilising its-heat-giving, health-giving, and life-giving rays.