90482 Orcus given the designation S/2005 (90482) 1 before later being named "Vanth". It orbits Orcus in a nearly face-on circular orbit with an eccentricity of about 0.007, and an orbital period of 9.54 days. Vanth orbits only from Orcus and is too close to Orcus for ground-based spectroscopy to determine the surface composition of the satellite. Mike Brown suspects that like the Pluto–Charon system, Orcus and Vanth are tidally locked. Vanth does not resemble known collisional satellites because its spectrum is very different from that of its primary, and it may be a captured KBO. Vanth could also have originated as
90482 Orcus of death, and frequently acted as a guide of the deceased to the underworld. The absolute magnitude of Orcus is approximately 2.3 (comparable with the 2.6 of cubewano 50000 Quaoar). The detection of Orcus by the Spitzer Space Telescope in the far infrared and by Herschel Space Telescope in submillimeter constrains its diameter to . Orcus appears to have an albedo of about 21% to 25%, which may be typical of trans-Neptunian objects approaching the 1000 km diameter range. In the magnitude and size estimates reported above it was assumed that Orcus is a singular object. The presence of a