Editing Infrared (section)

=== Astronomy ===

{{Main|Infrared astronomy|far-infrared astronomy}}
[[File:ESO - Beta Pictoris planet finally imaged (by).jpg|thumb|[[Beta Pictoris]] with its planet Beta Pictoris b, the light-blue dot off-center, as seen in infrared. It combines two images, the inner disc is at 3.6&nbsp;μm.]]
Astronomers observe objects in the infrared portion of the electromagnetic spectrum using optical components, including mirrors, lenses and solid state digital detectors. For this reason it is classified as part of [[optical astronomy]]. To form an image, the components of an infrared telescope need to be carefully shielded from heat sources, and the detectors are chilled using liquid [[helium]].

The sensitivity of Earth-based infrared telescopes is significantly limited by water vapor in the atmosphere, which absorbs a portion of the infrared radiation arriving from space outside of selected [[Infrared window|atmospheric windows]]. This limitation can be partially alleviated by placing the telescope observatory at a high altitude, or by carrying the telescope aloft with a balloon or an aircraft. Space telescopes do not suffer from this handicap, and so outer space is considered the ideal location for infrared astronomy.

The infrared portion of the spectrum has several useful benefits for astronomers. Cold, dark [[molecular cloud]]s of gas and dust in our galaxy will glow with radiated heat as they are irradiated by imbedded stars. Infrared can also be used to detect [[protostar]]s before they begin to emit visible light. Stars emit a smaller portion of their energy in the infrared spectrum, so nearby cool objects such as [[planet]]s can be more readily detected. (In the visible light spectrum, the glare from the star will drown out the reflected light from a planet.)

Infrared light is also useful for observing the cores of [[active galaxies]], which are often cloaked in gas and dust. Distant galaxies with a high [[redshift]] will have the peak portion of their spectrum shifted toward longer wavelengths, so they are more readily observed in the infrared.<ref name="ir_astronomy" />