 Day time gods and night time gods are frequently deities of an "upper world" or "celestial world" opposed to the "netherworld" and earth ruled by other gods (underworld and earth gods are collectively known as chthonic deities).For example, sky gods Zeus and Hera rule the celestial realm in ancient Greece while the chthonic realm is ruled by Hades and Persephone.The tripartite division of the world into sky/heaven/upper, earth/middle, and under/nether/lower seems to be a universal feature of all human religions.