Ar Ciel アルシエル, arushieru?, lit. "Ar Ciel") is the planet that is used as the setting for the Ar tonelico series and all of its related works. Its name means "This World" in Hymmnos language. It seems to be mostly similar to Earth, though with various differences, the main one being that it has two moons instead of one. Said moons are called the Viola Moon and the Cello Moon. Ar Ciel is located in a still unnamed galaxy and orbits around a mother star called Sol.