Word: spectroheliograph
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White Worms. One instrument, the spectroheliograph, takes pictures of the sun in the light that comes from single elements, such as hydrogen or calcium. The instrument has recently been improved to the point where it can take motion pictures (spectroheliokinemato-grams) which show the sun covered with patches, streaks and mottlings, most of them in motion. The pattern of the mottled background often changes completely in 15 minutes. "Motion pictures of the surface," says Dr. Menzel, "present a sort of 'crawly' appearance-like white worms in a pile of carrion...
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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