Infrared Astronomy

Synonyms

Far infrared (far IR); Near infrared (near IR)

Definition

Infrared astronomy is the branch of observational astronomy which studies celestial objects through their infrared radiation, that is, at wavelengths longer than 0.75 μm and shorter than 400 μm. The domain is not strictly defined, and some astronomers consider that it begins at 1 μm where CCDs, the most universally used detectors in the visible domain, are no longer sensitive. Infrared astronomy is considered as part of optical astronomy because technologies and methods (incoherent detection, classical optics, solid-state digital detectors) are globally the same as in the visible domain. One peculiarity of infrared astronomy is the strong background emission of the environment (atmosphere, telescope) that requires dedicated differential techniques. Another one is the absorption by the atmosphere (see Fig. 1) in a large fraction of the wavelength domain: this explains why balloons, airplanes, and satellites are often...