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Hansen, James Edward

(Encyclopedia)Hansen, James Edward, 1941–, American astrophysicist and climatologist, b. Denison, Iowa, Ph.D. Univ. of Iowa, 1967. In 1967 he joined the Goddard Institute for Space Studies, and served as director...

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...

Richardson, Robert Coleman

(Encyclopedia)Richardson, Robert Coleman, 1937–2013, American physicist, b. Washington, D.C. Ph.D. Duke Univ., 1966. Richardson was a professor at Cornell from 1968 until his death; he was the university's first ...

gallium

(Encyclopedia)gallium gălˈēəm [key], metallic chemical element; symbol Ga; at. no. 31; at. wt. 69.723; m.p. 29.78℃; b.p. 2,403℃; sp. gr. 5.904 at 29.6℃ (solid), 6.095 at 29.8℃ (liquid); valence +2 or +3...

interval

(Encyclopedia)interval, in music, the difference in pitch between two tones. Intervals may be measured acoustically in terms of their vibration numbers. They are more generally named according to the number of step...

micrometer

(Encyclopedia)micrometer mīkrŏmˈətər, mīˈkrōmēˌtər [key]. 1 Instrument used for measuring extremely small distances. Typical examples are devices used in astronomical telescopes to measure the apparent d...

Bunsen burner

(Encyclopedia)Bunsen burner, gas burner, commonly used in scientific laboratories, consisting essentially of a hollow tube which is fitted vertically around the flame and which has an opening at the base to admit a...

Carnot, Nicolas Léonard Sadi

(Encyclopedia)Carnot, Nicolas Léonard Sadi kärnōˈ [key], 1796–1832, French physicist, a founder of modern thermodynamics; son of Lazare N. M. Carnot. His famous work on the motive power of heat (Réflexions ...

Osheroff, Douglas Dean

(Encyclopedia)Osheroff, Douglas Dean, 1945–, American physicist, b. Aberdeen, Wash., Ph.D. Cornell, 1973. He was a professor at Cornell from 1973 to 1987, when he joined the faculty at Stanford. Osheroff was also...

hibernation

(Encyclopedia)hibernation hīˌbərnāˈshən [key] [Lat.,= wintering], practice, among certain animals, of spending part of the cold season in a more or less dormant state, apparently as protection from cold when ...