AskDefine | Define telescopy

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Noun

telescopy
  1. the manufacture and use of telescopes

Extensive Definition

A telescope is an instrument designed for the observation of remote objects and the collection of electromagnetic radiation. The first known practically functioning telescope is credited to the German-Dutch lensmaker Hans Lippershey in 1608. The name "Telescope" (from the Greek tele = 'far' and skopein = 'to look or see'; teleskopos = 'far-seeing') was a name given to Galileo Galilei's instrument for viewing distant objects. The name was invented by an unidentified Greek poet/theologian, present at a banquet held in 1611 by Prince Federico Cesi to make Galileo Galilei a member of the Accademia dei Lincei. "Telescope" can refer to a whole range of instruments operating in most regions of the electromagnetic spectrum.

Types of telescopes

The name "telescope" covers a wide range of instruments and is difficult to define. They all have the attribute of collecting electromagnetic radiation so it can be studied or analyzed in some manner. The most common type is the optical telescope. Other types also exist and are listed below.

Optical telescopes

An optical telescope gathers and focuses light mainly from the visible part of the Electromagnetic spectrum (although some work in the infrared and ultraviolet). Optical telescopes increase the apparent angular size of distant objects, as well as their apparent brightness. Telescopes work by employing one or more curved optical elements - usually made from glass - lenses or mirrors - to gather light or other electromagnetic radiation and bring that light or radiation to a focus, where the image can be observed, photographed, studied, or sent to a computer. Optical telescopes are used for astronomy and in many non-astronomical instruments, including: theodolites (including transits), spotting scopes, monoculars, binoculars, camera lenses, and spyglasses. There are three main types:

Radio telescopes

Radio telescopes are directional radio antennae that often have a parabolic shape. The dishes are sometimes constructed of a conductive wire mesh whose openings are smaller than the wavelength being observed. Multi-element Radio telescopes are constructed from pairs or larger groups of these dishes to synthesize large "virtual" apertures that are similar in size to the separation between the telescopes: see aperture synthesis. As of 2005, the current record array size is many times the width of the Earth, utilizing space-based Very Long Baseline Interferometry (VLBI) telescopes such as the Japanese HALCA (Highly Advanced Laboratory for Communications and Astronomy) VSOP (VLBI Space Observatory Program) satellite. Aperture synthesis is now also being applied to optical telescopes using optical interferometers (arrays of optical telescopes) and Aperture Masking Interferometry at single reflecting telescopes. Radio telescopes are also used to collect microwave radiation, often used to help study the leftover Big Bang radiation, and also can be used to collect radiation when visible light is obstructed or faint, such as from quasars. Some radio telescopes are used by programs such as SETI and the Arecibo Observatory to search for exterrestrial life. (see also: Wow! Signal)

X-ray and gamma-ray telescopes

X-ray and gamma-ray radiation go through most metals and glasses, some X-ray telescopes use Wolter telescopes composed of ring-shaped "glancing" mirrors, made of heavy metals, that reflect the rays just a few degrees. The mirrors are usually a section of a rotated parabola and a hyperbola or ellipse. Gamma-ray telescopes refrain from focusing completely, and use coded aperture masks; the pattern of shadows the mask creates can be reconstructed to form an image.
These types of telescopes are usually on Earth-orbiting satellites or high-flying balloons, since the Earth's atmosphere is opaque to this part of the electromagnetic spectrum.

Notes

References

  • Contemporary Astronomy - Second Edition, Jay M. Pasachoff, Saunders Colleges Publishing - 1981, ISBN 0-03-057861-2
telescopy in Tosk Albanian: Teleskop
telescopy in Arabic: مقراب
telescopy in Asturian: Telescopiu
telescopy in Bosnian: Teleskop
telescopy in Bulgarian: Телескоп
telescopy in Catalan: Telescopi
telescopy in Czech: Dalekohled
telescopy in Corsican: Telescopiu
telescopy in Danish: Kikkert
telescopy in German: Teleskop
telescopy in Estonian: Teleskoop
telescopy in Modern Greek (1453-): Τηλεσκόπιο
telescopy in Spanish: Telescopio
telescopy in Esperanto: Teleskopo
telescopy in Basque: Teleskopio
telescopy in Persian: تلسکوپ
telescopy in French: Télescope
telescopy in Galician: Telescopio
telescopy in Korean: 망원경
telescopy in Hindi: दूरदर्शी
telescopy in Croatian: Teleskop
telescopy in Indonesian: Teleskop
telescopy in Italian: Telescopio
telescopy in Hebrew: טלסקופ
telescopy in Georgian: ტელესკოპი
telescopy in Swahili (macrolanguage): Darubini
telescopy in Latin: Telescopium
telescopy in Latvian: Teleskops
telescopy in Luxembourgish: Teleskop
telescopy in Lithuanian: Teleskopas
telescopy in Hungarian: Távcső
telescopy in Malayalam: ദൂരദര്‍ശിനി
telescopy in Dutch: Telescoop (optica)
telescopy in Japanese: 望遠鏡
telescopy in Neapolitan: Ucchiarone
telescopy in Norwegian: Teleskop
telescopy in Polish: Teleskop
telescopy in Portuguese: Telescópio
telescopy in Romanian: Telescop
telescopy in Russian: Телескоп
telescopy in Albanian: Teleskopi
telescopy in Sicilian: Telescopiu
telescopy in Simple English: Telescope
telescopy in Slovak: Teleskop
telescopy in Slovenian: Daljnogled
telescopy in Serbian: Телескоп
telescopy in Serbo-Croatian: Teleskop
telescopy in Finnish: Kaukoputki
telescopy in Swedish: Teleskop
telescopy in Telugu: టెలీస్కోపు
telescopy in Thai: กล้องโทรทรรศน์
telescopy in Vietnamese: Kính viễn vọng
telescopy in Cherokee: ᎠᎧᏔᏘ
telescopy in Turkish: Teleskop
telescopy in Ukrainian: Телескоп
telescopy in Yiddish: טעלעסקאפ
telescopy in Chinese: 望远镜
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