It's been over a decade since my last astrophysics class, but I appreciate you being charitable about my assumed knowledge! I think if anything this thread shows:

1) how absolutely mindblowingly big space is

2) how bad humans really are at intuiting things at the scale of space

It seems like they are going for the "the easiest way to get a right answer is give the wrong answer on the internet" approach.

Cunningham's Law

https://en.wikipedia.org/wiki/Ward_Cunningham#%22Cunningham'...

To be fair, for someone who is not well-versed in either optics or space physics, calculating the answer is not that straight-forward.

You can do pretty well just comparing the ratios of the size to the distance, right? Or is it more than that?

That's a start, for sure, but to do a super accurate calculation (the kind I feel unqualified to carry out), you need to take into account apparent size, redshift, whether or not there's gravitational lensing, interstellar dust in the way, etc etc.

But I want to reiterate that what's meaningful about this discussion is in part how unintuitive things at the far edges of our scales of perception really are. It's a muscle that, left untrained, will lead you to make incorrect characterizations like the one I made.