How I see is that the normal everyday reality works roughly like in the real world, to match the players' intuitive expectations. The underlying unobservable reality on the level of atoms or celestial bodies don't necessarily need to work the same, nor it really matters one bit whether it does or does not. The characters simply would never know anyway.
Overall, I really hate 'it is fantasy, so nothing needs to make sense' credo. No, fantasy can make sense and probably also should! This doesn't necessarily mean matching the real world, it means internal consistency.