If Earth and the Moon were to continue orbiting around one another undisturbed for an indefinite period of time, their mutual tidal action would continue to dissipate their angular momentum. Eventually, Earth will be tidally locked to the Moon, so the same face of Earth will always face the same face of the Moon. Even now, the Moon’s tidal action is slowing down the rate of Earth’s spin; a million years from now, a day on Earth will be about sixteen seconds longer than it is today.