Naming of moons underworld, and Nix (a respelling of Nyx), mother of Charon, is the goddess of darkness and the night. Kerberos is a giant three-headed dog who guards the entrance to the underworld. The fifth moon is named for the river Styx that forms the boundary between the worlds of the living and the dead. The name of Eris's moon Dysnomia was suggested by its discoverer Michael E. Brown, who also suggested the name of the dwarf planet. The name has two meanings: in mythology Dysnomia (lawlessness) is the daughter of Eris (chaos). However, the name is also an intentional reference to
Gate deities of the underworld only to the souls capable of pronouncing the secret name of the god himself, as a sort of "password". The walls of many Pharaonic tombs in the Valley of the Kings are decorated with the texts of the Book of Gates, which describes the twelve gates or pylons of the underworld: in spite of being imagined as architectural barriers to all intents and purposes, the gates were individually named as goddesses. Chapter 144 of the Book of the Dead mentions seven gates, each with its own God, a Doorkeeper and a Herald: for example, the 7th gate is guarded by