Astronomy & Astrophysics 101: Infrared Astronomy

Infrared astronomy refers to an area of astronomy where astronomers observe and analyze light from planets, exoplanets, and the clouds of dust found between stars and galaxies. Credit: ESA/Hubble, JPL/Caltech

What Is Infrared Astronomy?

Infrared astronomy is a branch of astronomy in which astronomers observe and analyze light from the Universe with wavelengths in the infrared range.

Astronomers analyze light (electromagnetic radiation) in order to study the Universe. Telescopes collect light, and the data gathered by telescopes enables astronomers to learn about specific celestial objects and develop better theories about the Universe’s history, present, and future.

The nature of the light that an object emits depends on its temperature. Whereas hot stars predominantly emit visible light, infrared radiation is emitted by slightly cooler objects, such as exoplanets and cool clouds of cosmic dust. Furthermore, infrared radiation passes more freely through cosmic dust than visible light does, because visible light is scattered by cosmic dust. This means that infrared astronomy allows astronomers to observe regions of space that are otherwise obscured by cosmic dust, and images captured in the infrared also typically reveal more stars than images taken in visible light (since stars radiate infrared as well as visible light).

By combining observations at multiple wavelengths, we can construct a more complete picture of the structure, composition, and behavior of celestial objects than the visible wavelengths alone could ever show.


Infrared astronomy refers to an area of astronomy where astronomers observe and analyze light from planets, exoplanets, and the clouds of dust found between stars and galaxies. Credit: ESA/Hubble, JPL/Caltech

Hubble’s high resolving power has been crucial in the investigation of regions of star formation, both in the Milky Way and in other galaxies, and its infrared capabilities have allowed it to peer through the thick clouds of dust and gas present in those regions. To celebrate its 23rd anniversary, Hubble released a stunning new image of one of the most distinctive objects in our skies, the Horsehead Nebula. By capturing the object in infrared radiation, the image quite literally shows the nebula in a whole new light, capturing plumes of gas and revealing a beautiful, delicate structure that is normally obscured by dust.

NASA’s James Webb Space Telescope is designed to observe infrared light—wavelengths of light that are beyond the rainbow visible to human eyes. Infrared light’s longer wavelengths provide information that other wavelengths cannot, including star formation and other processes that take place behind thick veils of dust, which block the shorter wavelengths of visible light. Webb will detect a range of infrared light that overlaps with those observed by other NASA missions, but will also cover a significant portion of the infrared spectrum that they do not. This infographic highlights Webb’s overlapping and complementary spectrum coverage with two NASA missions: the Hubble Space Telescope and Spitzer Space Telescope. Webb features a combination of Hubble’s imaging power and sensitivity with Spitzer’s infrared coverage, and goes beyond both to provide a wealth of new infrared data on the universe that is hidden beyond visible red light. Credit: NASA and J. Olmstead (STScI)

We also invite you to watch this Hubblecast video that explores how Hubble’s observations differ across different wavelengths of the electromagnetic spectrum, and how these observations will be complemented by those of the James Webb Space Telescope.

AstronomyAstrophysicsEuropean Space AgencyHubble Space Telescope