57 Mnemosyne
Mnemosyne is a large main belt asteroid. It is an S-type asteroid in composition. It was discovered by Robert Luther on 22 September 1859 from Düsseldorf. Its name was chosen by Martin Hoek, director of the Utrecht Observatory, in reference to Mnemosyne, a Titaness in Greek mythology. The orbital period of this asteroid is close to a 2:1 commensurability with Jupiter, which made it useful for perturbation measurements to derive the mass of the planet.
Photometry measurements made at the Oakley Observatory during 2006 produced a lightcurve with a rotation period of and an amplitude of in magnitude. It has an estimated span of and a mass of.
