theme for Faculae. No nomenclature currently exists for this class of features on Titan. Planitiae Planitiae (low plains) on Titan are named after planets from the fictional Dune universe created by Frank Herbert. Regiones Regiones (regions distinctly different from their surroundings) are named after deities of peace and happiness. Sinūs Sinus (bays) within seas or lakes are named after terrestrial bays, coves, fjords or inlets. Terrae Terrae are extensive landmasses. As with the albedo features, they are named after sacred and enchanted locations from cultures across the world. Undae Undae are dune fields. On Titan they are named after Greek deities of wind. Virgae Virgae (streaks of colour) are named after rain gods in world mythologies. Informal names for previously unnamed features Because the exact nature of many surface features remain mysterious, a number of features took time to receive formal names and are known by nicknames. In most cases, indications of brightness and darkness refer not to visible light, but to the infrared images used to look through Titan's obscuring haze. 'The Sickle': a large, dark, sickle-shaped region identified by the Hubble Space Telescope. 'Throat of Kraken': unofficial name for the strait that separates the north and south basins of Kraken Mare, before officially being named Seldon Fretum. It was used in early publications that hypothesized about its role with tidal dissipation and surface currents between the two basins of Kraken Mare. See also Lakes of Titan Notes References External links USGS: Titan nomenclature USGS links to PDF maps with nomenclature Titan Titan, geological features