How do space telescopes keep their mirrors so cold?
Quick Answer
Many space telescopes use sunshields, radiators, and orbit choices to dump heat into space. Infrared observatories often have to stay extremely cold because their own heat would drown out faint cosmic signals.
The Full Story
Space telescopes are cooled by preventing sunlight and heat from reaching sensitive instruments, then letting excess warmth radiate away into deep space. The James Webb Space Telescope, launched in 2021, uses a tennis-court-sized sunshield with five layers to keep its telescope and instruments in shade. Its mirrors operate at around 40 kelvin (about -233 °C), while some detectors are even colder. Infrared astronomy depends on this because a warm telescope would emit infrared light and overwhelm the objects it is trying to observe.
Key Facts
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