Arecibo Observatory, radio-astronomy radio astronomy, study of celestial bodies by means of the electromagnetic radio frequency waves they emit and absorb naturally.

Radio Telescopes

..... Click the link for more information. facility located at Arecibo, Puerto Rico, that includes the world's largest single-dish radio telescope. It was completed in 1963 and is operated by Cornell Univ. under contract with the U.S. National Science Foundation. The principal instrument is a fixed antenna of spherical section, 1,000 ft (305 m) in diameter, that is built into a natural limestone bowl. Although the antenna is too large and heavy to be moved, it can be pointed as much as 20° from the zenith by moving the line feeds to the antenna's focus. As a result of the resurfacing of the antenna, which was completed in 1974, observations are possible up to a frequency of 4,000 MHz. A 100-ft (30-m) satellite antenna can be used in conjunction with the large antenna for interferometer observations. In addition there is a wide range of instrumentation for measuring ionospheric conditions. Principal research programs include studies of radio emissions from many types of objects, especially the cores of supernovas called pulsars; radar studies of comets and asteroids; and ionospheric studies.

Arecibo Observatory

Astronomical observatory near Arecibo, P.R., site of the world's largest single-unit radio telescope (as opposed to multiple telescope interferometers such as the Very Large Array). The telescope dish, 1,000 ft (300 m) across, is built into a valley; celestial sources are tracked across the sky by moving secondary structures suspended about 500 ft (150 m) above the dish. The observatory has produced detailed radar maps of the surface of Venus and near-Earth asteroids (see Earth-crossing asteroid), made detailed studies of Earth's ionosphere, and made major contributions to studies of pulsars and hydrogen gas in galaxies.