Something made to be a screensaver (or just some kind of relax video, after all).

V. 2: http://www.youtube.com/watch?v=OYPs7ezjJTE
Updated, Luna's mane moving the good way, and had to reduce some settings for a smoother screensaver run:
Screensaver (with sound): https://www.dropbox.com/s/1yepk8caarvrx8s/Nightsky%20-%20Luna%20screensaver.exe
Screensaver (no sound): https://www.dropbox.com/s/riaj5agf45qnz96/Nightsky%20-%20Luna%20screensaver%20%28no%20sound%29.exe

Music: 'The Ballad of the Space Babies' by Jim Guthrie ('Sword & Sworcery LP' OST)

Vectors used (@Deviantart):
Princess Luna by regolithx
Background by risingmoondragon
The moon by misteraibo

"My Little Pony: Friendship is magic" and all trademarks are courtesy of Hasbro, HUB & DHX Media. No infringements upon the rights of Hasbro, HUB or DHX Media intended.