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Retiredmech t1_is3m02s wrote

If a alien civilization, say 10 to 50 million light years away developed a JWST and pointed it at our solar system. What and how much information they would they discover about us? I ask this because the JWST is promising to find exoplanets and their composition. I was wondering what it would look like from the opposite side to hopefully understand better on how the telescope works. (this is hypothetical, so imagine the the civilization is 10 to 50 million years in the future and looking at present day)

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Wooden_Ad_3096 t1_is4y60d wrote

10 to 50 million light years away, they could see the milky way, and that’s about it.

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Retiredmech t1_is7uvms wrote

I guess my question was a bit vague. How about, at the distance the telescope could detect exoplanets, what they would find out about our solar system?

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DoctorWho984 t1_isauirw wrote

This article may interest you: It's what the Earth would look like through JWST at 40 light years away.

However, none of the planets in our solar system are particularly amenable to being detected by an instrument like JWST, see here and here. JWST is best at finding exoplanets via transit light curves, and these mostly find "Hot Jupiters" or "Warm Neptunes", planets with larger masses that are much closer to their star than any of the giants in our solar system are to the sun. JWST can also do direct imaging of planets, but that works best for planets that are very far out like Neptune, but also massive, ~10x the mass of Jupiter. So our solar system is not a very good candidate for finding anything at all with just JWST. They'd be most likely to find Jupiter through radial velocity measurements using a optical telescope with better spectral resolution, for example the Keck observatory has likely detected a Jupiter twin.

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