Pluto’s mass. In 1978, it was discovered that Pluto had a moon of its own. The moon was...

Pluto’s mass. In 1978, it was discovered that Pluto had a moon of its own. The moon was given the name Charon (now known to be one of three; see Fig. Q5.19). After the discovery of this moon, the hitherto unknown mass of Pluto was calculated to a precision of less than 1%. How did the discovery of Charon allow the mass to be determined?