Columbia Encyclopedia

Search results

238 results found

Tian Shan

(Encyclopedia)Tian Shan or Tien Shan both: tēĕn shän [key] [Chin.,=celestial mountains], mountain system of central Asia, extending c.1,500 mi (2,410 km) from the Pamir Mts., Tajikistan, NE through the Xinjiang ...

Dionysius the Areopagite, Saint

(Encyclopedia)Dionysius the Areopagite, Saint ârēŏpˈəjīt [key], fl. 1st cent. a.d., Athenian Christian, converted by St. Paul. Acts 17.34. Tradition has made him a martyr and the first bishop of Athens. He ha...

horology

(Encyclopedia)horology hōrŏlˈəjē [key], science of measuring time and technology of constructing instruments for its measurement or recording. Early measurements of the passage of time were based on observatio...

longitude

(Encyclopedia)longitude lŏnˈjĭto͞odˌ [key], angular distance on the earth's surface measured along any latitude line such as the equator east or west of the prime meridian. A meridian of longitude is an imagin...

space law

(Encyclopedia)space law, agreements governing the exploration and use of outer space, developed since the first launching (1957) by humans of a satellite into space. Space law, an aspect of international law, has g...

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...

synchrotron radiation

(Encyclopedia)synchrotron radiation, in physics, electromagnetic radiation emitted by high-speed electrons spiraling along the lines of force of a magnetic field (see magnetism). Depending on the electron's energy ...

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...

radar astronomy

(Encyclopedia)radar astronomy, application of radar to the determination of distances and planetary features within the solar system, such as rotation rates. A short burst of radio waves is transmitted in the direc...

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...