Apparently, when the Moon was very young, it was also much closer to the Earth. This means that, since the Earth's gravitational tide upon the Moon varies as the third power of the distance, the young, molten Moon was tidally deformed. It may have been spinning quite rapidly then, and not 'locked' to its orbital period at all. But as the Moon drifted away from the Earth and the Moon solidifed, it apparently froze-in a memory of this deformed initial state, and Apollo astronaut radar altimetry showed this in the early 1970's. The reason the Moon is now synchronously locked, is probably because it inherited a non-spherical shape from its close tidal phase, and this fossilized tidal bulge has been used by the Earth as 'handles' to slowly lock the Moon into its synchronous state during the last few billion years. In the future, the orbital period of the Moon will increase to over 50 days, and its rotation period will also decease to the same period.
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