infrared telescopes


An infrared telescope is a
telescope A telescope is an optical instrument An optical instrument (or "optic" for short) is a device that processes light waves (or photon The photon (Greek: φῶς, phōs, light) is a type of elementary particle. It is the quantum of the ele ...

that uses
infrared Infrared (IR), sometimes called infrared light, is electromagnetic radiation In physics Physics (from grc, φυσική (ἐπιστήμη), physikḗ (epistḗmē), knowledge of nature, from ''phýsis'' 'nature'), , is the natur ...

light to detect celestial bodies. Infrared light is one of several types of radiation present in the
electromagnetic spectrum The electromagnetic spectrum is the range of frequencies Frequency is the number of occurrences of a repeating event per unit of time. It is also referred to as temporal frequency, which emphasizes the contrast to spatial frequency and angula ...

electromagnetic spectrum
. All celestial objects with a temperature above
absolute zero Absolute zero is the lowest limit of the thermodynamic temperature Thermodynamic temperature is the measure of ''absolute temperature'' and is one of the principal parameters of thermodynamics. A thermodynamic temperature reading of zero deno ...
emit some form of
electromagnetic radiation In physics Physics is the natural science that studies matter, its Elementary particle, fundamental constituents, its Motion (physics), motion and behavior through Spacetime, space and time, and the related entities of energy and force. ...

electromagnetic radiation
. In order to study the universe, scientists use several different types of telescopes to detect these different types of emitted radiation in the electromagnetic spectrum. Some of these are
gamma ray A gamma ray, or gamma radiation (symbol γ or \gamma), is a penetrating form of electromagnetic radiation arising from the radioactive decay of atomic nuclei. It consists of the shortest wavelength electromagnetic waves and so imparts the hi ...
x-ray An X-ray, or, much less commonly, X-radiation, is a penetrating form of high-energy electromagnetic radiation In physics Physics is the natural science that studies matter, its Elementary particle, fundamental constituents, its Motio ...

ultra-violet Ultraviolet (UV) is a form of electromagnetic radiation In physics Physics (from grc, φυσική (ἐπιστήμη), physikḗ (epistḗmē), knowledge of nature, from ''phýsis'' 'nature'), , is the natural science that stud ...
, regular
visible light Light or visible light is electromagnetic radiation within the portion of the electromagnetic spectrum that is visual perception, perceived by the human eye. Visible light is usually defined as having wavelengths in the range of 400–700 nano ...
(optical), as well as infrared telescopes.

Leading discoveries

There were several key developments that led to the invention of the infrared telescope: * In 1800,
William Herschel Frederick William Herschel (; german: Friedrich Wilhelm Herschel; 15 November 1738 – 25 August 1822) was a German-born British astronomer and composer of music. He frequently collaborated with his younger sister and fellow astronomer Ca ...

William Herschel
discovered infrared radiation. * In 1878,
Samuel Pierpoint Langley Samuel Pierpont Langley (August 22, 1834 – February 27, 1906) was an American astronomer, physicist, inventor of the bolometer and aviation pioneer. In addition to becoming the third Secretary of the Smithsonian Institution, he was also a pro ...
created the first bolometer. This was a very sensitive instrument that could electrically detect incredibly small changes in temperature in the infrared spectrum. * Thomas Edison used an alternative technology, his tasimeter, to measure heat in the sun's solar corona, corona during the solar eclipse of July 29, 1878. * In the 1950s, scientists used lead-sulfide detectors to detect the infrared radiation from space. These detectors were cooled with liquid nitrogen. * Between 1959 and 1961, Harold Johnson (astronomer), Harold Johnson created near-infrared photometers which allowed scientists to measure thousands of stars. * In 1961, Frank Low invented the first germanium bolometer. This invention, cooled by liquid helium, led the way for current infrared telescope development.Timeline
Infrared telescopes may be ground-based, air-borne, or space telescopes. They contain an infrared camera with a special solid-state infrared detector which must be cooled to cryogenics, cryogenic temperatures. Ground-based telescopes were the first to be used to observe outer space in infrared. Their popularity increased in the mid-1960s. Ground-based telescopes have limitations because water vapor in the Earth's atmosphere absorbs infrared radiation. Ground-based infrared telescopes tend to be placed on high mountains and in very dry climates to improve visibility. In the 1960s, scientists used balloons to lift infrared telescopes to higher altitudes. With balloons, they were able to reach about up. In 1967, infrared telescopes were placed on rockets. These were the first air-borne infrared telescopes. Since then, aircraft like the Kuiper Airborne Observatory (KAO) have been adapted to carry infrared telescopes. A more recent air-borne infrared telescope to reach the stratosphere was NASA's Stratospheric Observatory for Infrared Astronomy (SOFIA) in May 2010. Together, United States scientists and the German Aerospace Center scientists placed a 17-ton infrared telescope on a Boeing 747 jet airplane. Placing infrared telescopes in space completely eliminates the interference from the Earth's atmosphere. One of the most significant infrared telescope projects was the Infrared Astronomical Satellite (IRAS) that launched in 1983. It revealed information about other galaxies, as well as information about the center of our galaxy the Milky Way. NASA presently has solar-powered spacecraft in space with an infrared telescope called the Wide-field Infrared Survey Explorer (WISE). It was launched on December 14, 2009.Griggs, B. (2009, December 14) NASA launches infrared telescope to scan entire sky. ''Cable News Network''. Retrieved from

Selective comparison

The wavelength of visible light is about 0.4 μm to 0.7 μm, and 0.75 μm to 1000 μm (1 mm) is a typical range for infrared astronomy, far-infrared astronomy, to submillimetre astronomy.

Infrared telescopes

Ground based : * Infrared Telescope Facility, Hawaii, 1979– * Gornergrat Infrared Telescope, 1979–2005 * Infrared Optical Telescope Array, 1988–2006 * United Kingdom Infrared Telescope, 1979– * Wyoming Infrared Observatory, 1977- Airborne: * Kuiper Airborne Observatory (KAO), 1974-1995 *Stratospheric Observatory for Infrared Astronomy (SOFIA), 2010- Space based: * IRAS, Infrared Astronomical Satellite, 1983 * Spitzer Space Telescope, 2003-2020 * Herschel Space Observatory, 2009-2013 * Wide-field Infrared Survey Explorer (WISE), 2009- * Roman Space Telescope (formerly WFIRST) * James Webb Space Telescope (JWST), 2021-

See also

* Infrared astronomy * List of largest infrared telescopes * List of telescope types


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