Ok, Luna fans, If you really think Celestia and Luna hate eachother, you clearly haven't been watching the show.
"Celestia imprisoned Luna on the moon because Celestia hates her younger sister. Poor Luna, Celestia is such a bitch, I hate her so much!"
No, she imprisoned Nightmare Moon IN the moon, not on, in. Luna was Nightmare Moon. It states at the beginning that she tried to reason with her sister, and she defeated her to imprison her the moon. What was she supposed to do? Let eternal night rain down upon Equestria?