Change in orbit due to moment of inertia change?

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Discussion Overview

The discussion revolves around the implications of changes in the Earth's moment of inertia, specifically due to the construction of the Three Gorges Dam, and how this might affect the Earth's orbit around the Sun. Participants explore the relationship between changes in rotational dynamics and orbital mechanics.

Discussion Character

  • Exploratory, Debate/contested, Conceptual clarification

Main Points Raised

  • One participant notes that the increase in the length of the day by 60 nanoseconds raises questions about its impact on the Earth's orbit around the Sun.
  • Another participant expresses skepticism about any significant orbital changes, arguing that the Earth's mass has not changed and the distance to the Sun remains constant.
  • A third participant introduces the concept of tidal locking effects between the Earth and the Sun, suggesting that these effects are likely negligible due to the relative sizes of the Earth and Sun compared to their distance.

Areas of Agreement / Disagreement

Participants generally disagree on the potential effects of the moment of inertia change on the Earth's orbit, with some asserting no significant impact while others raise additional considerations regarding tidal locking.

Contextual Notes

The discussion does not resolve the relationship between moment of inertia changes and orbital mechanics, leaving open questions about the assumptions involved in the arguments presented.

DrBwts
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Hi,

So recently I read about the massive 3 gorges dam changing the mass moment of inertia of the Earth to such an extent that the days will now be 60ns longer.

Then I thought, how will this effect the orbit of the Earth about the Sun?

Any thoughts?
 
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Wow! A whole 60 ns longer each day! Man, I can catch some additional zzzs every morning!

I wouldn't worry about any orbital changes w.r.t. the Earth's movement about the sun.

BTW, in 60 ns, a beam of light travels about 18 meters.

It would also take over 160 million years to add an additional HOUR to each day.
 
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DrBwts said:
Then I thought, how will this effect the orbit of the Earth about the Sun?
It won't. It hasn't changed the Earth's mass one iota, nor has it changed the distance between the Earth's center of mass and the Sun.
 
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what about tidal locking effects between the Earth and the sun? I guess it is negligibly small, since the size of the Earth and sun is very small compared to the distance between them.
 

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