Why do infared telescopes have to worry about thermal radiation from there surroundings?
Why do infared telescopes have to worry about thermal radiation from there surroundings?
Last Updated on Friday, 23 July 2010 12:04 Written by Administrator Friday, 23 July 2010 12:04
Question by xxfoundthewayxx: Why do infared telescopes have to worry about thermal radiation from there surroundings?
Telescopes functioning at visible wavelenfths don’t have to worry a bout thermal radiation from their surroundings, but infared telescopes do; infared detectors are usually cooled by liquid nitrogen or liquid helium. Why?
Best answer:
Answer by Jason T
Thermal radiation *is* infrared radiation, that’s why. Not cooling an infrared telescope would be like having an optical telescope made of luminescent materials in a floodlit football field! You’d never see anything through the light already pouring into your eyepiece.
The body of the infrared telescope itself can absorb the infrared radiation and then re-emit it as it warms up. The detector would be overwhelmed by its own infrared emissions and would be unable to detect distant sources. By cooling it with liquid nitrogen or helium you prevent the telescope itself from emitting infrared, and so it can distinguish distant sources.
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because they collect it