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UmbralRaptor t1_jdxh24v wrote

1 arcsecond angular resolution implies a linear resolution of 1 au at a distance of 1 parsec. We're deep within small angle approximation land, so can easily show what 0.1" gets you at varying distances:

distance resolution comment
1 ly 0.03 au Barring clever lightcurve reconstruction, you would not be able to tell that the moon exists
10 ly 0.3 au I'm unsure that you could find Earth. (I mean, JWST's coronagraph doesn't have the contrast for this, but I'm also concerned about the inner working angle)
100 ly 3 au This would be beyond the capabilities of even proposed telescopes like the HabEx starshade

FWIW, HST has a comparable angular resolution to JWST, as do some spy satellites. (notably the ones that took the image that Trump leaked)

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jd-sutton OP t1_jdxl2s2 wrote

Just a quick note - the JWST is 0.1 not 1.. Not sure if you used 0.1 in your calcs but typed 1 in the comment or your calcs are incorrect. Can you clarify? Thanks

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UmbralRaptor t1_jdxlc9h wrote

The 1 is just a rule of thumb thing that comes out from how the parsec is (well, was) defined.

so 0.1 arcsec * 1/3.26 pc ~= 0.03 au

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