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Secchi, Pietro Angelo

(Encyclopedia)Secchi, Pietro Angelo pyĕˈtrō änˈjālō sĕkˈkē [key], 1818–78, Italian astronomer, a Jesuit priest. He was director of the observatory of the Gregorian Univ., Rome, from 1849. He is known es...

comet

(Encyclopedia)CE5 Comet: Whatever the direction of a comet's flight, its “tail” always points away from the sun. The tail disappears when the comet is far from the sun. comet [Gr.,=longhaired], a small cele...

transducer

(Encyclopedia)transducer, device that accepts an input of energy in one form and produces an output of energy in some other form, with a known, fixed relationship between the input and output. One widely used class...

Raman effect

(Encyclopedia)Raman effect räˈmən [key], appearance of additional lines in the spectrum of monochromatic light that has been scattered by a transparent material medium. The effect was discovered by C. V. Raman i...

heterotroph

(Encyclopedia)heterotroph hĕtˈərətrōfˌ [key], living organism that obtains its energy from carbohydrates and other organic material. All animals and most bacteria and fungi are heterotrophic. In contrast, aut...

saprophyte

(Encyclopedia)saprophyte săpˈrəfītˌ [key], any plant that depends on dead plant or animal tissue for a source of nutrition and metabolic energy, e.g., most fungi (molds) and a few flowering plants, such as Ind...

calorie

(Encyclopedia)calorie, abbr. cal, unit of heat energy in the metric system. The measurement of heat is called calorimetry. The calorie, or gram calorie, is the quantity of heat required to raise the temperature of ...

Io, in astronomy

(Encyclopedia)Io īˈō [key], in astronomy, one of the 39 known moons, or natural satellites, of Jupiter. Io is subject to Jupiter's enormous tidal forces and is, as a result, the most volcanically active body in ...

Kerrville

(Encyclopedia)Kerrville kûrˈvĭl [key], city (1990 pop. 17,384), seat of Kerr co., S central Tex., on the Guadalupe River; settled 1846, inc. 1942. Kerrville has an active livestock industry (cattle, sheep, goats...

dwarf planet

(Encyclopedia)dwarf planet, a nonluminous body of rock or gas that orbits the sun and has a rounded shape due to its gravity. Unlike a planet, a dwarf planet is not capable of clearing its orbit of smaller objects ...