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Because it is an infrared telescope, and in earth orbit there are three very bright infrared sources that would mess up the instruments or heat up the telescope
by Tuna-Fish 3y ago
Because it is an infrared telescope, and in earth orbit there are three very bright infrared sources that would mess up the instruments or heat up the telescope too much if they ever shone on the sensitive parts. (Sun, Moon and Earth.) When the telescope is placed in the Sun-Earth L2, all three sources are always very close to each other in the sky, and you can shield against all three with a single directional sunshield.
- cubefox 3y agoI always thought L2 was chosen for Earth to cover up the sun. But apparently Earth covers it only to 84%. https://www.quora.com/Is-the-L2-point-of-Earth-in-a-permanent-shadow-of-the-Earth https://www.quora.com/Is-the-L2-point-of-Earth-in-a-permanen...
- sjburt 3y agoIt’s so the sun and the earth will always be in the same direction and both can be hidden behind the sun shield.
- Tuna-Fish 3y agoBecause the JWST is not at the L2, but in a halo orbit around it, Earth in fact never covers the Sun at all from its point of view. They are just always fairly close to each other.
- cubefox 3y agoInteresting!
- deleted 3y ago[deleted]
- bagels 3y agoIt needs solar power