Andromeda is visible from 2.5 million light-years because the light of hundreds of billions of stars blends together. But an Earth-like planet there would be roughly ten billion times fainter than its own star and separated from it by only about 1.3 microarcseconds—far beyond the direct-imaging ability of any existing telescope.
Andromeda can be found without a telescope under a sufficiently dark sky, even though its light has travelled…
