An infrared telescope is a

telescope A telescope is a device used to observe distant objects by their emission, Absorption (electromagnetic radiation), absorption, or Reflection (physics), reflection of electromagnetic radiation. Originally, it was an optical instrument using len ...

that uses

infrared Infrared (IR; sometimes called infrared light) is electromagnetic radiation (EMR) with wavelengths longer than that of visible light but shorter than microwaves. The infrared spectral band begins with the waves that are just longer than those ...

light to detect celestial bodies. Infrared light is one of several types of radiation present in the

electromagnetic spectrum The electromagnetic spectrum is the full range of electromagnetic radiation, organized by frequency or wavelength. The spectrum is divided into separate bands, with different names for the electromagnetic waves within each band. From low to high ...

. All celestial objects with a temperature above

absolute zero Absolute zero is the lowest possible temperature, a state at which a system's internal energy, and in ideal cases entropy, reach their minimum values. The absolute zero is defined as 0 K on the Kelvin scale, equivalent to −273.15 ° ...

emit some form of

electromagnetic radiation In physics, electromagnetic radiation (EMR) is a self-propagating wave of the electromagnetic field that carries momentum and radiant energy through space. It encompasses a broad spectrum, classified by frequency or its inverse, wavelength ...

. 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 ), is a penetrating form of electromagnetic radiation arising from high energy interactions like the radioactive decay of atomic nuclei or astronomical events like solar flares. It consists o ...

x-ray An X-ray (also known in many languages as Röntgen radiation) is a form of high-energy electromagnetic radiation with a wavelength shorter than those of ultraviolet rays and longer than those of gamma rays. Roughly, X-rays have a wavelength ran ...

, 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: * In 1800,

William Herschel Frederick William Herschel ( ; ; 15 November 1738 – 25 August 1822) was a German-British astronomer and composer. He frequently collaborated with his younger sister and fellow astronomer Caroline Herschel. Born in the Electorate of Hanover ...

discovered infrared radiation. * In 1878, Samuel Pierpoint Langley 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 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 Liquid nitrogen (LN2) is nitrogen in a liquid state at cryogenics, low temperature. Liquid nitrogen has a boiling point of about . It is produced industrially by fractional distillation of liquid air. It is a colorless, mobile liquid whose vis ...

. * Between 1959 and 1961, Harold Johnson created near-infrared photometers which allowed scientists to measure thousands of stars. * In 1961, Frank Low invented the first

germanium Germanium is a chemical element; it has Symbol (chemistry), symbol Ge and atomic number 32. It is lustrous, hard-brittle, grayish-white and similar in appearance to silicon. It is a metalloid or a nonmetal in the carbon group that is chemically ...

bolometer. This invention, cooled by liquid helium, led the way for current infrared telescope development.Timeline
Caltech 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. 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 Water vapor, water vapour, or aqueous vapor is the gaseous phase of Properties of water, water. It is one Phase (matter), state of water within the hydrosphere. Water vapor can be produced from the evaporation or boiling of liquid water or from th ...

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 The Boeing 747 is a long-range wide-body aircraft, wide-body airliner designed and manufactured by Boeing Commercial Airplanes in the United States between 1968 and 2023. After the introduction of the Boeing 707, 707 in October 1958, Pan Am ...

jet airplane. 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. NASA presently has solar-powered spacecraft in space with an infrared telescope called the

James Webb Space Telescope The James Webb Space Telescope (JWST) is a space telescope designed to conduct infrared astronomy. As the largest telescope in space, it is equipped with high-resolution and high-sensitivity instruments, allowing it to view objects too old, Lis ...

(JWST). It was launched on December 25, 2021.

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 Infrared astronomy is a sub-discipline of astronomy which specializes in the astronomical observation, observation and analysis of astronomical objects using infrared (IR) radiation. The wavelength of infrared light ranges from 0.75 to 300 microm ...

, 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), 2010-2022 Space based: * Infrared Astronomical Satellite, 1983 * Spitzer Space Telescope, 2003-2020 * Herschel Space Observatory, 2009-2013 * Wide-field Infrared Survey Explorer (WISE), 2009-2024 * Nancy Grace Roman Space Telescope (formerly WFIRST) *

(JWST), 2021- *

Euclid Euclid (; ; BC) was an ancient Greek mathematician active as a geometer and logician. Considered the "father of geometry", he is chiefly known for the '' Elements'' treatise, which established the foundations of geometry that largely domina ...

, 2023-

Notes

{{Portal bar, Astronomy, Stars, Spaceflight, Outer space, Solar System Telescope types Infrared imaging

Leading discoveries

Selective comparison

Infrared telescopes

See also

Notes