What Are Love Numbers and How Do They Impact Tidal Deformations?

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In summary, the Earth's rotation is slowing down due to the Moon's gravity pulling on the tidal bulge, which in turn pulls on the rest of the Earth. This also causes the Moon to slowly recede from the Earth. Tidal interactions can occur with the atmosphere and mantle, but they are much smaller than the effects on the oceans. The extent of these interactions depends on the composition of the body, with the atmosphere, oceans, crust, and deeper regions all responding differently.
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Hoophy
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So I THINK I understand that the tidal bulge is resting slightly in front of the moon because of the Earths rotation and the moons gravity, it pulls the moon 'forward' a little adding energy to the moons orbit and expanding it, what I do not understand is why the Earths rotation is slowing. I think I understand that it the energy of the tides (And also tidal electricity generation) has to come from somewhere. Could somebody please explain to me why mechanically the Earth's orbit slows down? Also do these tidal interactions occur with the atmosphere and mantle? Can these tidal interactions occur between hypothetical 100% solid bodies, if so to what extent? Also if my original assumptions are wrong please let me know, as I know you will. Thank you for your time. :)
 
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Last I heard, the Earth's rotation was speeding up. This was due to dams holding large bodies of water at high latitudes, thus bringing more of the Earth's mass towards the center.
 
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  • #3
The moon has a braking effect on Earth's rotation due to tidal friction. This also causes the moon to slowly recede from the earth. It will eventually become tidally locked with earth, but, probably not before the sun incinerates it.
 
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Algr said:
Last I heard, the Earth's rotation was speeding up. This was due to dams holding large bodies of water at high latitudes, thus bringing more of the Earth's mass towards the center.

dunno where you heard that, but it is incorrect

if what you said was true, we would be taking away leap seconds, not adding them periodicallyDave
 
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  • #5
Hoophy said:
Could somebody please explain to me why mechanically the Earth's orbit slows down?

The Moon's gravity pulls on the bulges, and the bulges pull on the rest of the Earth. So as the Moon is pulled forward by the leading bulge, the Earth is pulled in the opposite direction, which slows its rotation down.

Hoophy said:
Also do these tidal interactions occur with the atmosphere and mantle?

I'm sure the atmosphere is pulled just like the tides are, it's just that any effect would be much smaller than the tides. As for the mantle, I don't know.

Hoophy said:
Can these tidal interactions occur between hypothetical 100% solid bodies, if so to what extent?

If you mean 100% rigid bodies, then I don't believe so.
 
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There are also tides in the solid part of Earth. The LHC at CERN has to adjust their magnets frequently because the ring geometry changes due to those tides. On a global scale, the Earth is not that solid.
LHC and tides
 
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  • #7
Here's a pic from a random website showing the interaction Drakkith described:
tidalbraking.jpe


Regarding effects of rigidity on tidal deformations, you might want to look at 'Love numbers'. Googling for the phrase is slightly problematic, for obvious reasons - just make sure you add the keyword 'tides' to your search query.
In short, you don't get tidal braking from a 100% rigid solid, as the tidal potential can't produce a tidal bulge. Since such a thing doesn't exists in reality, you end up with varying degrees of tidal interactions depending on composition - the atmosphere responds differently than the oceans, which differ from the crust, which differ from deeper, denser regions of the planet.
 
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Related to What Are Love Numbers and How Do They Impact Tidal Deformations?

1. How do scientists measure the slowing of Earth's rotation?

Scientists use a technique called Very Long Baseline Interferometry (VLBI) to measure the Earth's rotation. This method involves using a network of radio telescopes around the world to track the movements of distant quasars, which appear to be stationary in the sky. By comparing the positions of these quasars over time, scientists can determine the exact length of a day on Earth and track any changes in its rotation.

2. What causes the Earth's rotation to slow down?

The Earth's rotation is primarily affected by the gravitational pull of the Moon and Sun. As the Earth rotates, the tidal forces from these celestial bodies cause a slight bulging of the Earth's surface, which creates a drag on its rotation. This drag gradually slows down the Earth's rotation over time.

3. How much is the Earth's rotation slowing down?

The Earth's rotation is currently slowing down at a rate of approximately 1.4 milliseconds per day, or about 1.4 seconds every 1 million years. This may not seem significant, but over millions of years, it can have a significant impact on our planet's climate and geological processes.

4. Will the Earth eventually stop rotating?

No, the Earth will not stop rotating. The laws of physics dictate that the Earth will always rotate, as long as there are no external forces acting on it. However, the rate of rotation may continue to slow down until it becomes synchronized with the Moon's orbit, which would result in the same side of the Earth always facing the Moon.

5. What are the potential consequences of a slower Earth rotation?

A slower Earth rotation can have various consequences, including changes in climate and weather patterns, shifts in the Earth's magnetic field, and changes in the length of a day. It can also affect the Earth's orbit and potentially lead to changes in the tilt of its axis, which could have a significant impact on the planet's seasons and ecosystems.

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