I know this is like 9 months old but YES! Finally someone else thinks that. People always assume that the sun and the moon in Equestrian work like ours but obviously they don't. The fact that the sun rises and falls EVERYWHERE at the same time shows that Equestrian might be flat or that the sun is projected further via magic. And from the apocalypse episode, we can see that all life isn't dead in Nightmare Moon's world so that proves the moon, Luna's moon, is actually giving off it's own light, not just reflecting. Not only that but assuming the sun and moon work likes ours is ludicrous because if they did there would be NO reason for Luna and Celestial to move them since, ya know, gravity. My best guess is that Celestial and Luna can actually summon these two Celestial objects at will or are doing something far beyond our grasp of understanding……..then again it's a cartoon.