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Sagan, Carl Edward

(Encyclopedia)Sagan, Carl Edward sāˈgən [key], 1934–96, American astronomer and popularizer of science, b. New York City. Early in his career he investigated radio emissions from Venus and concluded that the c...

Struve

(Encyclopedia)Struve shtro͞oˈvə [key], family of astronomers. Friedrich Georg Wilhelm von Struve, 1793–1864, was born in Germany but later lived in Russia. While director (1817–39) of Dorpat Observatory he w...

revolution

(Encyclopedia)revolution, in a political sense, fundamental and violent change in the values, political institutions, social structure, leadership, and policies of a society. The totality of change implicit in this...

zero

(Encyclopedia)zero, that number which, when added to any number, leaves the latter unchanged; its symbol is 0. The introduction of zero into the decimal system was the most significant achievement in the developmen...

Barnard, Frederick Augustus Porter

(Encyclopedia)Barnard, Frederick Augustus Porter, 1809–89, American educator and mathematician, b. Sheffield, Mass., grad. Yale, 1828. After tutoring at Yale and teaching in institutions for the deaf and mute, he...

gamma radiation

(Encyclopedia)gamma radiation, high-energy photons emitted as one of the three types of radiation resulting from natural radioactivity. It is the most energetic form of electromagnetic radiation, with a very short ...

Wisconsin, University of

(Encyclopedia)Wisconsin, University of, main campus at Madison; land-grant and state supported; coeducational; chartered 1848, opened 1849. Its history was disturbed by storms over the policies of Glenn Frank and o...

Lagrange, Joseph Louis, Comte

(Encyclopedia)Lagrange, Joseph Louis, Comte zhôzĕfˈ lwē kôNt lägräNzhˈ [key], 1736–1813, French mathematician and astronomer, b. Turin, of French and Italian descent. Before the age of 20 he was professor...

white dwarf

(Encyclopedia)white dwarf, in astronomy, a type of star that is abnormally faint for its white-hot temperature (see mass-luminosity relation). Typically, a white dwarf star has the mass of the sun and the radius of...

magnitude

(Encyclopedia)magnitude, in astronomy, measure of the brightness of a star or other celestial object. The stars cataloged by Ptolemy (2d cent. a.d.), all visible with the unaided eye, were ranked on a brightness sc...
 

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