Word: spectrum
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Dates: during 1940-1949
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...Spectrum...
...corona is bright, but the sun itself outdazzles it except when blacked out by the moon (or by synthetic eclipses created by the device called a coronagraph). Since each of the 92 standard elements, when hot, glows with distinctive spectrum colors, astronomers can analyze the corona's chemical content with spectroscopes during eclipses. They have found in it about two dozen unidentifiable spectrum bands...
...Physicist Edlen demonstrated that the corona probably consists mostly of heavier elements like iron, calcium, nickel. This was a big surprise to astronomers. Surprise No. 2 was Edlen's calculation that this high excitation which causes such heavy atoms to give off new spectrum lines must indicate coronal temperatures...
...Mars comes through the earth's air blanket, which contains water vapor, so Dr. Adams had to separate the terrestrial vapor pattern from the Martian (if any). This he did with the help of a phenomenon called the Doppler effect: when a source of light approaches earth, its spectrum lines are shifted to the right, and when it is receding they are shifted to the left. At times when Mars is fast approaching or retreating, the Doppler effect should pull the Martian vapor lines away from the earth lines enough to make them visible in Dr. Adams' delicate...
Down to Earth. Many an astronomer believes that the glow of the aurora borealis ("northern lights") is due to bombardments of electric particles from the sun, which agitate atoms in the upper air to the glow point. For a long time the spectrum lines corresponding to the auroral colors were called "forbidden lines'' because they could not be reproduced in the laboratory. Last week Drs. Joseph Kaplan and S. M. Ruben of U. C. L. A. told how they brought the auroral colors down to earth. They put gas molecules in a tube, stirred them up with...