Discovery of Polydeuces

Polydeuces is a tiny moon of Saturn, only a few kilometers across, found in images from the Cassini spacecraft in October 2004. It is a Trojan moon of Dione: it shares Dione's orbit but stays about sixty degrees behind it, near a stable gravitational point known as L5. Unlike most Trojan bodies it moves back and forth, wandering widely around that point in a pattern called libration. It is named after Polydeuces, the Greek form of Pollux, one of the twin Dioscuri of Greek mythology. Its discovery showed that Saturn's moons include small companions locked into the orbits of larger neighbors.

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