Infrared rays are long, heat-intensive wavelengths that we cannot see.
Telescopes outfitted with heat-sensitive reflectors, instead of mirrors or lenses, gather infrared rays, which are reproduced visually by special photographic equipment.
The infrared image of an object is similar to what you see if you put your hand against a very cold window.
An outline of your hand appears as a result of the condensation of the warm air from your hand meeting the cold glass.
Infrared rays are absorbed in Earth’s atmosphere by water vapor and carbon dioxide, so infrared telescopes are most useful in high, dry locations.
Infrared telescopes mainly help identify the existence of relatively cool objects in the universe: protostars, cosmic dust clouds, certain types of galaxies, quasars, stars in general, and comets.
The largest infrared telescope in the world sits on top of Mauna Kea, an extinct volcano in Hawaii.