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SOFIA was an infrared telescope in an aircraft, allowing high altitude observations

An infrared telescope is a telescope that uses infrared light to detect celestial bodies. Infrared light is one of several types of radiation present in the electromagnetic spectrum.

All celestial objects with a temperature above absolute zero emit some form of electromagnetic radiation.[1] 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, x-ray, ultra-violet, regular visible light (optical), as well as infrared telescopes.

Leading discoveries

There were several key developments that led to the invention of the infrared telescope:

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 cryogenic temperatures.[3]

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 25 miles (40 kilometres) up. In 1967, infrared telescopes were placed on rockets.[2] 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.[4]

Placing infrared telescopes in space 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.[2] 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.[5]

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.

Selected infrared space telescopes[6]
Name Year Wavelength
IRAS 1983 5–100 μm
ISO 1996 2.5–240 μm
Spitzer 2003 3–180 μm
Akari 2006 2–200 μm
Herschel 2009 55–672 μm
WISE 2010 3–25 μm
JWST 2021 0.6–28.5 μm

Infrared telescopes

Ground based :


Space based:

See also


  2. ^ a b c Timeline Archived 2010-06-18 at the Wayback Machine Caltech
  3. ^ "Ask An Infrared Astronomer: Infrared Telescopes". Archived from the original on 2003-11-25.
  4. ^ Hamilton, J. (2010, July 2) NASA's flying telescope sees early success. National Public Radio. Retrieved from
  5. ^ "NASA launches infrared telescope to scan entire sky". Retrieved 2023-11-14.
  6. ^ JPL: Herschel Space Observatory: Related Missions