Nice try, human, but no pony that doesn’t already know the answer to that would ever think to ask.

Our planet does revolve around our sun, and I heard a long time ago it used to rotate too. But as time went on it slowed down. If nothing was done, eventually it would have tidal locked, like both our and your human Earth’s moon.

What we call the raising and lowering of the sun and moon is really our princess(es) magically grabbing hold of the celestial body in question and using it to flick us into proper rotation. That’s why it doesn’t have to be sustained all day long; it’s just one spell.