The Practical Astronomers

Much of astronomy is an abstract science, as remote from life as the farthest star. But astronomers can sometimes be as practical as bricklayers. Last week, under programs sponsored by the Navy and the Air Force, the practical astronomers were busy building two giant coronagraphs--telescopes that can make their own solar eclipse (TIME, Nov. 18, 1946). With their new gadgets, the stargazers will use the sun as a vast atomic laboratory. Shielded from the blinding light of the sun itself, they will be able to study the fireworks that sparkle continuously in the thin atmosphere around the sun's outer edges.

Cameras will record the movements of the ghostly corona. And by watching the waving filaments weave their patterns in space, astronomers hope to learn how to forecast the sun-caused atmospheric disturbances that can cripple the world's communication systems and block the best radar instruments.

In their solar laboratory, astrophysicists will watch the turbulent prominences that erupt from the sun's surface to stream out in high, graceful arcs. Moving at speeds up to 500 miles a second, the glowing gas may give clues to some of the problems of rocket research and supersonic flight.

In the past, scientists could observe these lively goings-on for only two or three minutes a year, when the sun was in total eclipse. Not until 1930, when French Astronomer Bernard Lyot built the first coronagraph, did anyone succeed in imitating the natural event. Astronomer Lyot put a small brass disk between the lenses of a simple telescope, cutting off direct sunlight and permitting him to focus the dim radiance of the corona and solar prominences upon a sheet of photographic film. It was a simple enough trick, but one that could not be carried off without superfine lenses, free of any imperfections and kept scrupulously clean. Even the scattered light from a few grains of dust would have ruined the pictures.

Almost ten times as powerful as any of their predecessors, the new American eyes will be installed in high-altitude observatories at Climax, Colo. and on Sacramento Peak near High Rolls, N. Mex. Their cameras will soon be tracing the progress of the sun across the southwestern U.S., helping practical astronomers to study the origin of cosmic rays, to work out new methods of long-range weather prediction, perhaps to uncover atomic secrets from the sun's hot heart.

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