Glossary term: Infrared Astronomy

Description: Infrared astronomy is a branch of astronomy that looks at infrared light. It is more sensitive to cool objects than optical astronomy and can observe very distant galaxies whose light has been redshifted a lot. Infrared observations are less affected by extinction and can thus see deeper into interstellar clouds of gas and dust. Molecules in Earth's atmosphere absorb much of the infrared light coming from space and thus infrared astronomy on the ground is done mostly in wavelength ranges where this absorption is lower. Both Earth and its atmosphere radiate in the infrared so special techniques are required to remove this background radiation. For infrared radiation with longer wavelengths, this background plus atmospheric absorption makes observing on the ground almost impossible. However for the longest infrared wavelengths ground-based observations are possible from very dry sites. This is typically called submillimeter astronomy.

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The OAE Multilingual Glossary is a project of the IAU Office of Astronomy for Education (OAE) in collaboration with the IAU Office of Astronomy Outreach (OAO). The terms and definitions were chosen, written and reviewed by a collective effort from the OAE, the OAE Centers and Nodes, the OAE National Astronomy Education Coordinators (NAECs) and other volunteers. You can find a full list of credits here. All glossary terms and their definitions are released under a Creative Commons CC BY-4.0 license and should be credited to "IAU OAE".

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Credit: NASA/ESA credit link
License: CC-BY-4.0 Creative Comments Attribution 4.0 International (CC BY 4.0) icons
The two Keck telescopes seen from above. The domes are open and the telescopes' mirrors can be seen inside.

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Caption: The two Keck telescopes on Mauna Kea on the island of Hawai`i. These two telescopes are reflecting telescopes with primary mirrors 10m across.
Credit: NASA/JPL credit link
License: PD Public Domain icons