Hades three-headed guard dog Cerberus. The Etruscan god Aita and the Roman gods Dis Pater and Orcus were eventually taken as equivalent to Hades and merged into Pluto, a Latinization of Plouton (", Ploútōn"), itself a euphemistic title often given to Hades. The origin of Hades' name is uncertain, but has generally been seen as meaning "the unseen one" since antiquity. An extensive section of Plato's dialogue "Cratylus" is devoted to the etymology of the god's name, in which Socrates is arguing for a folk etymology not from "unseen" but from "his knowledge ("eidenai") of all noble things". Modern linguists have
90482 Orcus with the normal object naming procedures. Vanth was found at 0.25 arcsec from Orcus with magnitude difference of . Estimates made in 2009 by Mike Brown show that the apparent magnitude of Vanth is which is magnitudes fainter than Orcus. Assuming equal albedos this would mean a diameter of 280 km, or 2.9 times smaller than the primary. However, the dissimilar colors of Orcus (neutral) and Vanth (red) suggest that Vanth could have an albedo a factor of two lower than Orcus. Should Vanth have an albedo of only 0.12, Vanth could be as large as 380 km with Orcus