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 (EMR) with s longer than those of . It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from around 1 (300 ) to the nominal edge of the ...
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
A unit of time is any particular time
Time is the indefinite continued sequence, progress of existe ...
.
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. ...
. 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, also known as gamma radiation (symbol γ or \gamma), is a penetrating form of electromagnetic radiation
In physics
Physics is the natural science that studies matter, its Elementary particle, fundamental constituents, it ...
, 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 ...
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
A bolometer is a device for measuring the power of incident electromagnetic radiation
In physics
Physics is the natural science that studies matter, its Elementary particle, fundamental constituents, its Motion (physics), motion and be ...
. 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 tasimeterImage:Tasimetro-Tasimeter 1 Edison.jpg, 250px, Tasimeter
The tasimeter, or microtasimeter, or ''measurer of infinitesimal pressure'', is a device designed by Thomas Edison to measure infrared radiation. In 1878, Samuel Langley, Henry Draper, and o ...
, to measure heat in the sun's corona
Corona (from the Latin for 'crown') most commonly refers to:
* Stellar corona, the outer atmosphere of the Sun or another star
* Coronavirus, a group of RNA viruses
** Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a coronavirus r ...
during the solar eclipse of July 29, 1878
A total solar eclipse occurred on July 29, 1878, over much of North America including the region of the Rocky Mountains. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun ...
.
* In the 1950s, scientists used lead-sulfide detectors to detect the infrared radiation from space. These detectors were cooled with liquid nitrogen
Students preparing homemade dewar of liquid nitrogen.">Cryogenic_storage_dewar.html" ;"title="ice cream with a Cryogenic storage dewar">dewar of liquid nitrogen.
Liquid nitrogen—LN2—is nitrogen in a liquid state at low temperature. Liquid ...
.
* Between 1959 and 1961, Harold Johnson created near-infrared photometer
A photometer is an instrument that measures the strength of electromagnetic radiation
In physics
Physics (from grc, φυσική (ἐπιστήμη), physikḗ (epistḗmē), knowledge of nature, from ''phýsis'' 'nature'), , is t ...
s which allowed scientists to measure thousands of stars.
* In 1961, Frank Low
Frank James Low (November 23, 1933 – June 11, 2009) was a Solid-state physics, solid state physicist who became a leader in the new field of infrared astronomy, after inventing the gallium doped germanium bolometer in 1961. This detector ex ...
invented the first germanium bolometer. This invention, cooled by liquid helium, led the way for current infrared telescope development.TimelineCaltech 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 http://www.cnn.com/2009/TECH/space/12/14/wise.spacecraft.launch/index.html
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 typesNotes
{{Portal bar, Astronomy, Stars, Spaceflight, Outer space, Solar System Infrared telescopes, Telescope types Infrared imaging