Far-infrared telescopes have to be cooled,but visible-light telescopes do not.Why not?
A)Far-infrared radiation is absorbed by the Earth's atmosphere.
B)Visible-light telescopes detect light from cool objects.
C)Far-infrared telescopes can only work in space.
D)Telescopes are not hot enough to emit visible light.

Question

Quizplus · Accepted Answer

Far-infrared telescopes need to be cooled because they detect infrared radiation, which can be emitted by the telescope itself if it is not cooled. Visible-light telescopes do not have this issue because they do not emit visible light.

Far-Infrared Telescopes Have to Be Cooled,but Visible-Light Telescopes Do Not