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Pholus is the inner moon of Chiron, with about 1/5 the diameter and 1% the mass of Earth ' s moon. Its orbit is almost a perfect circle, with a radius of about 60,000 miles. Its synodic month (the period from one full moon to the next) is 3.7 local days, and there are 144 such months in the course of Chiron's year. Pholus is a battered-looking moon, gray and cratered, which moves visibly against the background stars.

The orbits of Nessus and Pholus fall in the same plane, and the orbital radius of Nessus is almost exactly twice that of Pholus. As a result, the two moons appear to be roughly the same size from the surface of Chiron, each a little smaller than the Moon once appeared in Earth's sky. Each moon partially eclipses Alpha Centauri A from time to time (they are too small to cover the sun's disk entirely). Far more frequent are lunar eclipses, in which one or the other moon moves through Chiron's shadow. Even more frequent are the occasions on which Pholus passes in front of Nessus from the point of view of observers on Chiron.

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