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Lederman, Leon Max

(Encyclopedia)Lederman, Leon Max lĕdˈərmən [key], 1922–2018, American physicist, Ph.D. Columbia, 1951. He was a professor at Columbia until he became director of the Fermi National Accelerator Laboratory in B...

Orion Nebula

(Encyclopedia)Orion Nebula, bright diffuse nebula in the constellation Orion; also known as the Great Nebula of Orion and cataloged as M42 or NGC 1976. It is located near the middle of the “sword” hanging from ...

prism

(Encyclopedia)prism, in optics, a piece of translucent glass or crystal used to form a spectrum of light separated according to colors. Its cross section is usually triangular. The light becomes separated because d...

seasonal affective disorder

(Encyclopedia)seasonal affective disorder (SAD), recurrent fall or winter depression characterized by excessive sleeping, social withdrawal, depression, overeating, and pronounced weight gain. SAD effects an estima...

aberration

(Encyclopedia)CE5 A. Spherical aberration: Light rays near the edge of the lens are bent more and brought to focus nearer to the lens. B. Chromatic aberration: Shorter wavelengths (higher frequencies) are bent m...

air navigation

(Encyclopedia)air navigation, science and technology of determining the position of an aircraft with respect to the surface of the earth and accurately maintaining a desired course (see navigation). Basic to air ...

chiaroscuro

(Encyclopedia)chiaroscuro kyärōsko͞oˈrō [key] [Ital.,=light and dark], term once applied to an early method of printing woodcuts from several blocks and also to works in black and white or monotone. Today it i...

Finsen, Niels Ryberg

(Encyclopedia)Finsen, Niels Ryberg nēls rüˈbĕr fĭnˈsən [key], 1860–1904, Danish physician. He established in Copenhagen an institute of light therapy and wrote several books on his work. He received the 19...

Grimaldi, Francesco Maria

(Encyclopedia)Grimaldi, Francesco Maria fränchāsˈkō märēˈä grēmälˈdē [key], 1618?–1663, Italian physicist and mathematician. A Jesuit and professor at Bologna, he studied in detail and named the dark ...

zinc oxide

(Encyclopedia)zinc oxide, chemical compound, ZnO, that is nearly insoluble in water but soluble in acids or alkalies. It occurs as white hexagonal crystals or a white powder commonly known as zinc white. Zinc white...