At this kind of distance and zoom, the lights would've been antialiased out.
Actually not - since they're point sprites, we can freely set the pixel size based on distance (that's kind of the point of point sprites - pun intended).
So usually the only reason you don't see a light is that the equations say you should not see it - but we are technically able to show it from 1000 miles out.
So both disc size and disc color in combianation are supposed to represent the light intensity, and since the Airy disc is rendered there's what you'd call 'bloom' aplenty (I don't like the term 'bloom' - the eye doesn't do that kind of thing - to the part that it's Airy disc we render it, but to the part that's what CCD chips do, I don't think we need it).