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Ibn al-Haytham

(Encyclopedia)Ibn al-Haytham ălhəzĕnˈ [key], 965–c.1040, Arab mathematician. Ibn al-Haytham was born in Basra, but made his career in Cairo, where he supported himself copying scientific manuscripts. Among hi...

Sylvester II

(Encyclopedia)Sylvester II, c.945–1003, pope (999–1003), a Frenchman (b. Auvergne) named Gerbert; successor of Gregory V. In his youth he studied at Muslim schools in Spain and became learned in mathematics and...

observatory, orbiting

(Encyclopedia)observatory, orbiting, research satellite designed to study solar radiation, electromagnetic radiation from distant stars, the earth's atmosphere, or the like. Because the atmosphere and other aspects...

observatory

(Encyclopedia)observatory, scientific facility especially equipped to detect and record naturally occurring scientific phenomena. Although geological and meteorological observatories exist, the term is generally ap...

luminosity

(Encyclopedia)luminosity, in astronomy, the rate at which energy of all types is radiated by an object in all directions. A star's luminosity depends on its size and its temperature, varying as the square of the ra...

Mitchell, Maria

(Encyclopedia)Mitchell, Maria, 1818–89, American astronomer and educator, b. Nantucket, Mass. Mitchell taught school in Nantucket, and later became a librarian. On Oct. 1, 1847, Mitchell discovered a comet (1847 ...

Orbiting Astronomical Observatory

(Encyclopedia)Orbiting Astronomical Observatory (OAO), series of four orbiting observatories (see observatory, orbiting) launched between 1966 and 1972 by the National Aeronautics and Space Administration (NASA) to...

horizon

(Encyclopedia)horizon, in astronomy, roughly circular line bounding an observer's view of the surface of the earth where the sky and earth seem to meet. This is the visible horizon. At sea the visible horizon is a ...

Jansky, Karl Guthe

(Encyclopedia)Jansky, Karl Guthe, 1905–50, American radio engineer; b. Norman, Okla. After graduating (1927) from the Univ. of Wisconson, he joined the Bell Telephone Laboratories. While trying to determine the c...

Hamilton, Sir William Rowan

(Encyclopedia)Hamilton, Sir William Rowan, 1805–65, Irish mathematician and astronomer, b. Dublin. A child prodigy, he had mastered 13 languages by the age of 13 and was still an undergraduate when he became prof...