Infrared Astronomy

Infrared light penetrates dust much more easily than optical light. For this reason infrared astronomy is most useful for learning about dusty regions of the universe.

One example is star-forming regions. A star forms from a collapsing cloud of gas and dust. Forming and newly formed stars are still enshrouded by a cocoon of dust that blocks optical light. Infrared astronomers can more easily probe these stellar nurseries than optical astronomers can. The view of the center of our galaxy is also blocked by large amounts of interstellar dust. The galactic center is more easily seen by infrared than by optical astronomers.

Many molecules emit primarily in the infrared and radio regions of the spectrum. One example is the hydrogen molecule (H₂) which emits in the infrared. Infrared astronomers can study the distribution of these different kinds of molecules to learn about the processes forming molecules in interstellar space and the clouds in which these molecules form.

In 1998, using data from the Cosmic Background Explorer (COBE), astronomers discovered a background infrared glow across the sky. Radiated by dust that absorbed heat from all the stars that have ever existed, the background glow puts a limit on the total amount of energy released by all the stars in the universe.

Astronomers began with data acquired by COBE, then modeled and subtracted the infrared glow from foreground objects in our solar system, our galaxy's stars, and vast clouds of cold dust between the stars of our Milky Way. What remained was a smooth background of residual infrared light in the 240 and 140 micrometer wavelength bands in "windows" near the north and south poles of the Milky Way, which provide a relatively clear view across billions of light years.

The above examples are just a few of the observations made by infrared astronomers. In the past few decades, the new vistas opened in the infrared and other spectral regions have revolutionized astronomy.