Columbia Encyclopedia

Search results

500 results found

ecliptic coordinate system

(Encyclopedia)ecliptic coordinate system, an astronomical coordinate system in which the principal coordinate axis is the ecliptic, the apparent path of the sun through the heavens. The ecliptic poles are the two p...

Brahmagupta

(Encyclopedia)Brahmagupta bräˌməgo͝opˈtə [key], c.598–c.660, Indian mathematician and astronomer. He was among the first to meaningfully discuss the concepts of zero and of negative numbers. He wrote in ver...

Mauna Kea Observatories

(Encyclopedia)Mauna Kea Observatories mouˈnə kāˈə [key], astronomical observatory complex located on Mauna Kea peak, the “white mountain” on the island of Hawaii, at an altitude of more than 13,600 ft (4,1...

tesla

(Encyclopedia)tesla tĕsˈlə [key], unit of magnetic flux density: see under weber. ...

meter, in music

(Encyclopedia)meter, in music, the division of a composition into units of equal time value called measures, and the subdivision of those measures into an underlying pattern of stresses or accents (see measure). Me...

dimension, in physics

(Encyclopedia)dimension, in physics, an expression of the character of a derived quantity in relation to fundamental quantities, without regard for its numerical value. In any system of measurement, such as the met...

electron-volt

(Encyclopedia)electron-volt, abbr. eV, unit of energy used in atomic and nuclear physics; 1 electron-volt is the energy transferred in moving a unit charge, positive or negative and equal to that charge on the elec...

heat

(Encyclopedia)heat, nonmechanical energy in transit, associated with differences in temperature between a system and its surroundings or between parts of the same system. The study of heat and its relationship ...

Mysia

(Encyclopedia)Mysia mĭshˈēə [key], ancient region, NW Asia Minor. It was N of Lydia and its coast faced Lesbos. Mysia was not a political unit, and it passed successively to Lydia, Persia, Macedon, Syria, Perga...

Clark, Alvan

(Encyclopedia)Clark, Alvan, 1804–87, American astronomer and maker of astronomical lenses, b. Ashfield, Mass. In 1846 the firm of Alvan Clark & Sons was established at Cambridgeport, Mass.; it became famous a...