After being kept in the moon for some long time, Celestia wasn't able to control moon and sun at once.
She should've never put Luna in the moon. What did she ever do when she was banished in the cold moon?
Nothing. . . . .It was completely blank to her.
No talking, laughing, or moving. It was a cold, dark, deep, un-motion, and silent world.
But what was the one thing that could cheer the desperate spirit, Luna. Only 3 words
came into her head. . . . .
Elements of Harmony