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Abbot, Charles Greeley

(Encyclopedia)Abbot, Charles Greeley, 1872–1973, American astrophysicist, b. Wilton, N.H. He was acting director in 1896 and director in 1907 of the astrophysical observatory of the Smithsonian Institution; he wa...

Young, Charles Augustus

(Encyclopedia)Young, Charles Augustus, 1834–1908, American astronomer, b. Hanover, N.H., grad. Dartmouth, 1853. He discovered the reversing layer of the solar atmosphere and proved the gaseous nature of the sun's...

chromosphere

(Encyclopedia)chromosphere krōˈməsfērˌ [key] [Gr.,=color sphere], layer of rarefied, transparent gases in the solar atmosphere; it measures 6,000 mi (9,700 km) in thickness and lies between the photosphere (th...

neomycin

(Encyclopedia)neomycin nēˌōmīˈsĭn [key], broad spectrum antibiotic effective against both gram positive and gram negative bacteria (see Gram's stain). It interferes with protein synthesis in sensitive bacteri...

sideband

(Encyclopedia)sideband, any frequency component of a modulated carrier wave other than the frequency of the carrier wave itself, i.e., any frequency added to the carrier as a result of modulation; sidebands carry t...

Wald, George

(Encyclopedia)Wald, George, 1906–97, American biochemist, b. New York City, Ph.D. Columbia, 1932. He spent most of his career on the faculty at Harvard. In 1967 Wald, Haldan K. Hartline, and Ragnar Granit receive...

diffraction

(Encyclopedia)diffraction, bending of waves around the edge of an obstacle. When light strikes an opaque body, for instance, a shadow forms on the side of the body that is shielded from the light source. Ordinarily...

spectral class

(Encyclopedia)CE5 spectral class, in astronomy, a classification of the stars by their spectrum and luminosity. In 1885, E. C. Pickering began the first extensive attempt to classify the stars spectroscopically....

Planck, Max

(Encyclopedia)Planck, Max mäks plängk [key], 1858–1947, German physicist. Seeking to explain the experimental spectrum (distribution of electromagnetic energy according to wavelength) of blackbody radiation, he...

color index

(Encyclopedia)color index, in astronomy, difference in an object's brightness as recorded between any two well-defined bands of the electromagnetic spectrum by using optical filters of different colors. If blue and...