When will the earth act like the moon with regard to one side of the moon always facing the earth. Will the earth one day get locked in a rotational orbit that has one side of the planet facing the the sun at all times?


1 Answer 1


Well, yes it is possible. Earth's rotational speed is decreasing. But the decrease rate is very small. The time period is increasing at a rate of nearly 2.2 seconds/ 100,000 years. So to increase the time period from 1 day to 365 days, it will require almost 1.4x10^12 years. This is calculated assuming that the rate of increase remains same which may not be the case. But then various factors come in. Like after 5 billion years Sun will become a red giant and would ultimately absorb earth. So, that day when earth will have a rotating speed of 365 days won't be happening.

  • $\begingroup$ Isn't this mostly due to tidal drag from the Moon, so the Earth will become locked to the Moon? $\endgroup$ Commented Sep 29, 2015 at 6:50
  • $\begingroup$ by "locked to the moon" do you mean it's rotation will be similar with that of moon? Then No. $\endgroup$
    – Ari
    Commented Sep 29, 2015 at 7:55
  • $\begingroup$ The sun applies tidal forces of about 45% of that of the moon to the earth. So, both together slow down the earth, but once earth is locked to the moon, the slow down rate of the earth should decrease. Still, the sun would explode before. It would be interesting what would happen when it does not. $\endgroup$
    – sweber
    Commented Sep 29, 2015 at 10:24

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.