How Does the Moon's Tidal Locking Affect Earth's Rotation?

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Discussion Overview

The discussion revolves around the effects of the Moon's tidal locking on Earth's rotation, exploring hypothetical scenarios such as the Moon's sudden disappearance or explosion. Participants consider the implications for Earth's spin rate, the stability of its axial tilt, and the long-term evolution of day length.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • Some participants speculate on the chaotic effects on Earth's spin if the Moon were to suddenly explode, questioning how long it would take for Earth to stop spinning and whether one side would eventually face the Sun.
  • It is proposed that the Moon is currently slowing Earth's spin rate, and if the Moon were to disappear, the rate of slowing would be less than it is now.
  • One participant mentions that the Earth's day might become twice as long in about 5 billion years, although they express uncertainty about the exact timeline.
  • There is a discussion about the difference in tidal drag caused by solar and lunar tides, with some suggesting that without the Moon, Earth's axial wobble would increase, similar to issues observed on Mars.
  • Questions are raised about why the Moon is tidally locked to the Earth, with an explanation involving gravitational interactions and tidal forces affecting both bodies.
  • Participants express skepticism about the ability to predict the long-term effects of the Moon's absence on Earth's rotation and day length.

Areas of Agreement / Disagreement

Participants express various hypotheses and uncertainties regarding the Moon's influence on Earth's rotation and the consequences of its absence. No consensus is reached on the exact effects or timelines.

Contextual Notes

Limitations include the speculative nature of hypothetical scenarios, dependence on assumptions about tidal forces, and unresolved questions about the long-term stability of Earth's rotation without the Moon.

scifi5
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Hypothetically if the moon suddenly explodes (reason irrelevant) how would that affect the Earth's spin (chaotic spin until zero spin?) and my main question is how long would it take for the planet to stop spinning?

Would one side constantly face the sun in the end?
 
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The moon is slowing Earth's spin rate. If the moon disappeared, the Earth's spin rate would slow slower.
 
scifi5 said:
Hypothetically if the moon suddenly explodes (reason irrelevant) how would that affect the Earth's spin (chaotic spin until zero spin?) and my main question is how long would it take for the planet to stop spinning?

Would one side constantly face the sun in the end?

How long? Doubt anybody really knows, although the theory is that the Earth's day will be twice as long as it is now, in about 5 thousand million years time.

It's safe to say, you won't be here when it happens.
 
You're looking at the difference in drag between solar and lunar tides...

FWIW, without the Moon to stabilise it by Earth-tides, the Earth's axis is likely to wobble a lot more than the current precession rate etc. IIRC, that's one of the problems Mars has...
 
How much is the moon slowing the Earth's rotation by?
 
Why is the moon constantly facing the Earth with the same side? Wouldn't the same thing happen to the Earth orbitting around the sun if the moon was absent? Much like Mercury?
 
Gaius Baltar said:
How long? Doubt anybody really knows, although the theory is that the Earth's day will be twice as long as it is now, in about 5 thousand million years time.

Which will be right around the time the swollen sun is turning the Earth into a cinder.
 
Phobos said:
Which will be right around the time the swollen sun is turning the Earth into a cinder.

On the plus side, we won't be here to perish in that era.
 
scifi5 said:
Why is the moon constantly facing the Earth with the same side?

Gravitational interaction between the Earth and Moon raises tides, not just in the Earth's oceans, but also in the rock of the Earth and Moon. As that raised section of the Earth/Moon moves out of alignment (due to the rotating Earth/Moon), gravity pulls back on it and brakes the rotation. Over time, the Moon became tidally locked with the Earth.

And as noted above, the effect is still slowing the Earth's rotation. It just takes a LONG time.
 

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