 According to the surveys carried out by the NEOWISE mission of NASA's WISE telescope, the Infrared Astronomical Satellite IRAS, and the Japanese Akari satellite, "Sphinx" measures (), () and () kilometers in diameter and its surface has an albedo of (), () and (), respectively.The "Collaborative Asteroid Lightcurve Link" derives an albedo of 0.2332 and a diameter of 13.17 kilometers based on an absolute magnitude of 11.6.Alternative mean-diameter measurements published by the WISE team include (), () and () with corresponding albedos of (), () and ().