Okay, I was studying (read as: skimming a packet for a minute and a half) for English class, and since it was about the Greek gods, I decided to make Greek-themed descriptions of the royal sisters.
Celestia: Goddess of friendship, the sky, and the sun. Symbols include the sun, rainbow, and phoenix. Sister of Luna, whom she used the Elements of Harmony on to seal into the moon once she was transformed into Nightmare Moon.
Luna: Goddess of the night, youth, and the moon. Symbols include the abacus, flower necklace, moon, and stars. Sister of Celestia, whom helped redeem her from her transformation into Nightmare Moon.
Luna
, the "two-horned queen of the stars", is already a Roman Goddess. As for Celestia, apparently she decided for a gender reassignment: you can pick your choice between Sol Indiges , ancient and mostly agriculture-focused sun deity, Caelus, the deity of the sky, and
Sol Invictus
, from the later period (it's not clear how distinct it was from Sol Indiges, and no, he did not
lead the rebellion against the Primordials 
).
Actually, judging by how heavily the Romans were into syncretisation, I wouldn't put it past them to decide that Celestia and Luna are the female, horsey aspects of Sol and Luna respectively
edited 10th Sep '12 1:10:28 PM by Carciofus
But they seem to
know where they are going, the ones who walk away from Omelas.