I've searched around with various variations of "distance light can travel through air" and so forth, and all I'm coming up with is the speed of light and how it is slightly slower in air. Thanks, I passed third grade science. I have found this but I'm not even sure if that's what I want and if it is I don't understand. It's been awhile since I had to think about this sort of thing.
To make a rather complicated situation plain. In a completely perfectly straight shot, how far does light travel through air? Let's say, for the sake again of simplification, if the atmosphere extended way higher than it does, forever forever forever, up and up at the same thickness as it is at the ground, how far into space would I be able to even detect a large city?
It's, yeah. NaNo. If this ends up being a really stupid question, feel free to shame me to the depths of the internet.
EDIT: Ok, yes. redcoast helped me make this not sound so stupid, so here I go. All I want to know, really, is if light will make it even in a vague blurry form through 6,000 miles of Earth-like atmosphere. And if it won't, about how far would it go?