90482 Orcus Etruscan equivalent of the Roman Pluto, and later became an alternate name for Pluto. The surface of Orcus is relatively bright with albedo reaching 23%, grey in color and water-rich. The ice is predominantly in crystalline form, which may be related to past cryovolcanic activity. Other compounds like methane or ammonia may also be present. The existence of a satellite allowed astronomers to determine the mass of the system, which is approximately equal to that of the Saturnian moon Tethys. The ratio of masses of Orcus and Vanth is uncertain, possibly anywhere from 1:33 to 1:12. The diameter of Orcus
Orcus Orcus Orcus () was a god of the underworld, punisher of broken oaths in Italic and Roman mythology. As with Hades, the name of the god was also used for the underworld itself. In the later tradition, he was conflated with Dis Pater. Orcus was portrayed in paintings in Etruscan tombs as a hairy, bearded giant. A temple to Orcus may have existed on the Palatine Hill in Rome. It is likely that he was transliterated from the Greek daemon Horkos, the personification of Oaths and a son of Eris. The origins of Orcus may have lain in Etruscan religion.