>>13433307>Say, /sci/, can anyone here tell me—what are the theoretical limits of astronomical imaging?The diffraction limit is probably more important than the problem with interstellar dust. This should be pretty obvious so I guess you are not a physicist.
>With a large and powerful enough imaging apparatus, could you see individual rocky planets orbiting around distant suns? How about their moons, the clouds in their atmosphere, the patterns on the surface of their crust?Let's try the number, OK? Assuming an alien city 300 km across (really big by our standards) , 4 light years away. 300 km is 1 light milliseconds. Ratio width/distance is roughly the ratio wavelength/aperture.
4 light years is 126144000 light seconds, for a ratio of 1/126144000000.
Assuming wavelength of 1 um (infrared), we need an aperture of 126144 m. That is 126 km. It is considerable outside what we have today, probably what we can put on the moon (problems with sagging in gravity). So this behemot will have to be built and operated in space. And this is for the nearest star.
OK; so let us think BIG. We place an annular reflector in Earth-Sun L3 (the night side) with the periphery in sunlight (for positioning and station keeping). That gives us an aperture of 12,000 km, nearly 100x of above. And with that we can only see 400 lightyears out to see an oversized city.
>Or is this level of imaging forever locked out to us? In other words, what's the resolution on the light coming in to us?We sure need something better.
