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Hubble Space Telescope

(Encyclopedia)Hubble Space Telescope (HST), the first large optical orbiting observatory. Built from 1978 to 1990 at a cost of $1.5 billion, the HST (named for astronomer E. P. Hubble) was expected to provide the c...

Ritchey, George Willis

(Encyclopedia)Ritchey, George Willis, 1864–1945, American astronomer, b. Meigs co., Ohio, studied at the Univ. of Cincinnati (1883–84, 1886–87). He was superintendent of instrument construction (1899–1904) ...

Eratosthenes

(Encyclopedia)Eratosthenes ĕrətŏsˈthənēz [key], c.275–c.195 b.c., Greek scholar, b. Cyrene. A pupil of Callimachus in Athens, he became (c.240 b.c.) head of the library at Alexandria. Known for his versatil...

proper motion

(Encyclopedia)proper motion, in astronomy, apparent movement of a star on the celestial sphere, usually measured as seconds of arc per year; it is due both to the actual relative motions of the sun and the star thr...

Painlevé, Paul

(Encyclopedia)Painlevé, Paul pōl păNləvāˈ [key], 1863–1933, French statesman and mathematician. A mathematical prodigy when a child, he entered on a career devoted to science. He was a professor at the Sorb...

zenith

(Encyclopedia)zenith, in astronomy, the point in the sky directly overhead; more precisely, it is the point at which the celestial sphere is intersected by an upward extension of a plumb line from the observer's lo...

Biot, Jean Baptiste

(Encyclopedia)Biot, Jean Baptiste zhäN bätēstˈ byō [key], 1774–1862, French physicist, grad. École Polytechnique (1797). He taught mathematics at Beauvais before becoming (1800) professor of mathematical ph...

atlas, in geography

(Encyclopedia)atlas, in geography, collection of maps or charts. It usually includes data on various features of a country, e.g., its topography, natural resources, climate, and population, as well as its agricultu...

Banneker, Benjamin

(Encyclopedia)Banneker, Benjamin, 1731–1806, African-American inventor, astronomer, and mathematician, b. Baltimore co., Md., at what is now Ellicott's Mills. A free black, Banneker was essentially self-taught. H...

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...