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
Tomb of Orcus belonged to the Murina family, an offshoot of the Etruscan Spurinnae. The foundation is inscribed with the following enigmatic phrase: Orcus I was built between 470 and 450 BC (perhaps by a man named Leive; see below); a separate hypogeum, Orcus II, was built c. 325 BC. At some point in antiquity the wall between the two was removed, creating a large tomb with two dromes (entrances). The tomb was excavated in 1868 by an officer of the French Army. Upon its discovery, the excavator mistook the painting of a cyclops for the Roman god Orcus (see below), hence the