Columbia Encyclopedia

(Encyclopedia) Enceladus ĕnsĕlˈədəs [key], in astronomy, one of the named moons, or natural satellites, of Saturn. Also known as Saturn II (or S2), Enceladus is 310 mi (500 km) in diameter, orbits Saturn at a m...

(Encyclopedia) Copernican system, first modern European theory of planetary motion that was heliocentric, i.e., that placed the sun motionless at the center of the solar system with all the planets, including the ea...

(Encyclopedia) solstice sŏlˈstĭs [key] [Lat.,=sun stands still], in astronomy, either of the two points on the ecliptic that lie midway between the equinoxes (separated from them by an angular distance of 90°). ...

(Encyclopedia) radar, system or technique for detecting the position, movement, and nature of a remote object by means of radio waves reflected from its surface. Although most radar units use microwave frequencies, ...

(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...

(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...

(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...

(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...

(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...

(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...