It's "commonly known" how distant are our solar system planets from Sun. But we can't easily say that about planets, which distances can differ greatly, without some observations (or simulations, ...
If we were to see the Sun with our naked eyes from the Orion belt, would all planets be encompassed inside the star? Is this calculable?
When we see a star it looks much bigger in diameter to us than it really is, this picture (extracted from here) explains what I mean: Notice that the point we see in the skynight, represented by ...
We can often read in the scientific and also more casual reader literature and articles about the angular resolution of various telescopes and other optical equipment, be it ground based or onboard ...