Word: spectroheliograph
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Dates: during 1946-1946
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This difference allows astronomers to photograph the brighter parts of the sun's atmosphere with a "spectroheliograph," a prism spectroscope which casts sunlight of only one color on a photographic plate. The light from the solar atmosphere, glowing in that color, shows in the picture. Most of the dazzling light from the surface, being of other colors, is excluded by the spectroscope...
Another approach is the "coronagraph," developed by Dr. Bernard Lyot of France in 1930. It is a telescope with an internal disc hiding the face of the sun, and specially designed to eliminate glare. Though tricky, it works even better than the spectroheliograph, showing the corona, the faintly glowing halo which surrounds...
...Most recent gadget is the "birefringent filter," designed in 1940 by Dr. John W. Evans of Chabot Observatory, Oakland, Calif. It is a multi-decker sandwich of thin quartz plates and sheets of polaroid, which passes only light of a single pure color. Accomplishing the same object as the spectroheliograph, it is much more effective and easier for astronomers to use. When built into a coronagraph, it lets the complexities of the sun's atmosphere be seen in all their terrifying glory...
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