It appears in the sky during the Blue Sea Moon, and disappears during the Ethereal Moon. It is believed that it is the home of the Goddess, and that it was from there that Saint Seiros descended...

[flayn realizes, as she's explaining, that there is a lot of knowledge she just sort of takes for granted that other people will know. even more than a month away from fódlan, old habits are hard to break.

her voice trails off.]

...ah, I have not really explained about the Goddess, Seiros, and the Four Saints, have I?