In contrast to an "ordinary" telescope, which produces visible light images, a radio telescope "sees" radio waves emitted by radio sources, typically by means of a large parabolic ("dish") antenna, or arrays of them.
The Parkes 64 metre radio telescope in New South Wales, Australia (the bigger of the two shown)
The largest radio telescope is the RATAN-600 http://www.sao.ru/ratan/ (Russia) with 576m diameter of circular antenna (RATAN-600 description http://www.sao.ru/ratan/technic/desc.html.en ).
The best-known (although non-steerable) radio telescope is the Arecibo radio telescope located in Arecibo, Puerto Rico. Another well-known radio telescope is the Very Large Array (VLA), in Socorro, New Mexico. The largest radio telescope in Europe is the 100 metre diameter antenna in Effelsberg, Germany, which also was the largest fully steerable telecope for 30 years until the Green Bank Telescope was opened in 2000. A typical size of the single antenna of a radio telescope is 25 metre, dozens of radio telescopes with comparable sizes are operated in radio observatories all over the world.
The sub-field of astronomy related to observations made through radio telescopes is known as radio astronomy.
Many celestial objects, such as pulsars or active galaxies (like quasars), produce radio-frequency radiation and so are best "visible" or even only visible in the radio region of electromagnetic spectrum. By examining the frequency, power and timing of radio emissions from these objects, astronomers can improve our understanding of the Universe
Radio telescopes are also occasionally involved in SETI and tracking space probes (see Deep Space Network).
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Last updated: 02-07-2005 14:10:49
