Ignore the Sun's expansion.

From my understanding, tidal locking happens from torque as a result of tidal bulges being offset from the line between the two planets. So when the Earth and Moon tidally lock, will there still be tides since they shouldn't be moving apart anymore?


1 Answer 1


There won't be significant lunar tides. The moon will become fixed at one location above the Earth. The tidal forces that drive the resonant water flows that we call "tides" will be fixed. The moon will no longer drive the tides.

But the Earth won't be tidally locked to the sun, so solar tides will still occur. These are smaller in range, and by this point the Earth will be rotating much more slowly, each day would be well over a month long. There would be tidal forces from the sun, but the tides would be much slower.

This won't happen for 50 billion years or so, so it isn't something that will actually occur. The real Earth will continue to have tides until the oceans dry up under the effect of a brightening and expanding sun.

  • $\begingroup$ And by that time Earth itself may be gone. Many scientists predict the Sun will eat Earth in its dying stages. $\endgroup$ Jul 7, 2023 at 0:00
  • $\begingroup$ And certainly all the water and atmosphere will be gone, so "tide" won't have its everyday meaning. $\endgroup$
    – nigel222
    Jul 7, 2023 at 10:48

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