For months, that thought gnawed at Celestia.  Luna, if she wanted, could take a night off—that she wouldn’t was beside the point: she could.  Celestia was easily able to send the moon through its track; a thousand years of practice and she was pretty good at it.  Luna, however, was simply not powerful enough to control the sun, and likely wouldn’t be for centuries.  The more she thought about it, the more it irked her.  Very nearly all-powerful, yet there was just one little thing she could not do. 