90482 Orcus This means that Orcus is currently viewed pole-on, which could explain the near absence of any rotational modulation of its brightness. If, however, the primary is tidally locked with the satellite, the rotational period will coincide with the 9.7-day orbital period of Vanth. This minor planet was named after one of the Roman gods of the underworld, Orcus. While Pluto was the ruler of the underworld, Orcus was a punisher of the damned. The approved naming citation was published by the Minor Planet Center on 26 November 2004 (). Under the guidelines of the International Astronomical Union's (IAU) naming conventions,
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