Pluto and Charon are a fine example of how bodies orbit the center of mass (barycenter)

Here the barycenter is completely outside of Pluto all the time, so you could say this is a (dwarf-)double planet system. Charon is 12% the mass of Pluto, and they’re BOTH tidally locked! About tidal lock: here each body sees the same face of the other body all the time. That means the rotation periods AND orbit periods (around Barycenter) of BOTH bodies are the same; in this case days. How convenient that we only have to remember 1 number for 4 parameters. It’s worth noting that tidal locking doesn’t