Strangely, this reminds me of this manga set in a megalopolis, and when the MC reaches what is assumed to be the roof of the super structure, he meets someone who explains that they aren’t looking at a night sky, but rather at a ceiling that’s far enough away to be difficult for human eyes to discern, how far away is that, coincidentally this gap between the “roof” and the “sky” is about the width of the planet Jupiter.
Guy literally has to use a telescope to be able to track stuff happening on the other side.