> I know our eyes have a certain resolution limitation and
> a regular dot the size of a LED would surely not be visible
> at great distances (1-3 miles for example), but I'm not
> sure the same principle applies if the dot irradiates light.

Obviously it does not apply. You can place you point light source in
the farthest nebula, and still it will be visible here provided the
nubber of fotons per second reaching your eye is big enough. Just wait
the fotons to make their path.
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