AN: I don't own Fallout, MLP:FIM, nor am I KKAT.
Turning the celestial wheel is a difficult thing to do.
The first thing necessary is to have the raw magical power and talent of a unicorn.
The next thing needed is the spatial understanding and high speed mental alacrity gifted only to the pegasi.
The final, and perhaps most important requirement, is the pure strength, stamina, and resolve that only an earth pony can have.
An Alicorn has all three of these, because an Alicorn is all three of these: earth pony, pegasus, and unicorn.
Celestia and Luna were the Alicorns of Equestria. They had raised the sun and moon from time immemorial.
It was approaching the time designated for sunrise, and for the first time ever, there were no Alicorns to raise the sun.