Physics, Astronomy & Cosmology / Re: What radius to a human observer does light fail to give an observation?« on: 15/02/2016 19:11:14 »
Can you or anybody please describe in your own words what (A) observes of (B) as (B) moves way?
B subtends a smaller angle at A as he moves away. At some distance the angle will be less than the angular resolution of A's equipment so A will not be able to determine the size or shape of B (by direct observation, but there are indirect methods of estimating the mass of B at any distance) but if he is emitting or reflecting light he will always appear at least as a point source of photons.
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