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Baade, Walter

(Encyclopedia)Baade, Walter välˈtər bäˈdə [key], 1893–1960, German-born American astronomer. From 1919 to 1931 he was on the staff of the Hamburg observatory; from 1931 to 1958, at the Mt. Wilson observator...

altitude

(Encyclopedia)altitude, vertical distance of an object above some datum plane, such as mean sea level or a reference point on the earth's surface. It is usually measured by the reduction in atmospheric pressure wit...

seeing

(Encyclopedia)seeing, in astronomy, the clarity with which stars and other celestial objects can be observed. It is primarily determined by the atmosphere of the earth. The most obvious phenomenon is twinkling, whe...

United States Naval Observatory

(Encyclopedia)United States Naval Observatory, a federal astronomical observatory, located in Washington, D. C. It evolved from the Navy's oldest scientific institution, the Depot of Charts and Instruments, founded...

Uranus , in astronomy

(Encyclopedia)Uranus yo͝orāˈnəs, yo͝orˈə– [key], in astronomy, 7th planet from the sun, at a mean distance of 1.78 billion mi (2.87 billion km), with an orbit lying between those of Saturn and Neptune; its...

planetary system

(Encyclopedia)planetary system, a star and all the celestial bodies bound to it by gravity, especially planets and their natural satellites. Until the last decade of the 20th cent., the only planetary system known ...

National Radio Astronomy Observatory

(Encyclopedia)National Radio Astronomy Observatory (NRAO), federal observatory for radio astronomy, founded in 1956 and operated under contract with the National Science Foundation by Associated Universities, Inc.,...

kaleidoscope

(Encyclopedia)kaleidoscope kəlīˈdəskōp [key], optical instrument that uses mirrors to produce changing symmetrical patterns. Invented by the Scottish physicist Sir David Brewster in 1816, the device is usually...

Death Valley

(Encyclopedia)Death Valley, SE Calif. and SW Nev., a deep, arid basin, 140 mi (225 km) long, bordered on the W by the Panamint Range and on the E by the Amargosa Range. In summer the valley has recorded some of the...

gamma-ray astronomy

(Encyclopedia)gamma-ray astronomy, study of astronomical objects by analysis of the most energetic electromagnetic radiation they emit. Gamma rays are shorter in wavelength and hence more energetic than X rays (see...