An odd question on orbital dynamics

Click For Summary

Discussion Overview

The discussion revolves around the possibility of a celestial event that could lead to the Earth becoming tidally locked to the Sun, similar to the Moon's relationship with Earth. Participants explore various scenarios involving gravitational interactions with other celestial bodies and the implications of such events on Earth's rotation.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • Some participants suggest that over a very long timescale, the Earth's rotation could naturally become tidally locked to the Sun.
  • Others argue that significant external forces, such as impacts from asteroids or the gravitational influence of massive objects passing nearby, could alter Earth's rotation, but require substantial mass for any notable effect.
  • A participant questions whether a foreign body entering the solar system could shorten the timescale for tidal locking to days or months, expressing uncertainty about the feasibility of such scenarios.
  • There is a discussion about the potential for massive flybys to induce changes in Earth's rotation, with some suggesting that a close passage of a planet greater than Earth could cause significant perturbations.
  • Some participants assert that achieving tidal locking through flybys would require multiple events and that a single flyby would not suffice, emphasizing the need for a net torque without net force.
  • Concerns are raised about the catastrophic consequences of such interactions, including potential geological upheaval and changes to Earth's orbit.

Areas of Agreement / Disagreement

Participants express differing views on the feasibility of tidal locking through external gravitational influences, with no consensus on whether such scenarios are possible or realistic. The discussion remains unresolved regarding the specific conditions required for tidal locking to occur.

Contextual Notes

Participants note the complexity of calculating the necessary conditions for tidal locking, including the mass, position, and velocity of foreign bodies, as well as the potential for catastrophic effects on Earth’s environment and orbit.

parsec
Messages
112
Reaction score
1
Is there any kind of celestial event that could occur that could completely lock the Earth's rotation such that it is constantly facing the sun, in the same way the moon is tidally locked to the earth?

What would it take? Could it be caused by the passage or entrance of a new gravitational body into the solar system?
 
Physics news on Phys.org
Yes. It's called time. Give it a few tens or hundreds of billion years, and it will happen on its own.
 
The Earth will fall into the (expanding) sun long before that would happen.
Impacts of asteroids, fly-bys of very massive objects or stuff launched into space can modify the rotation of earth. You need a lot of mass for any significant change, however.
 
Okay, let me rephrase.

Is there any mass, position, linear and rotational velocity configuration of a foreign planet or body entering the solar system that could reduce that timescale for the Earth's tidal locking to something in the order of days, weeks or months?

Sorry if this is an absurd question, I don't know much about this sort of thing.
 
Is it possible without impact?
 
mfb said:
fly-bys of very massive objects

Ah yes, this sort of thing. I wouldn't know where to begin calculating what kind of regime is plausible, but I'm guessing the nearby passage of a planet with mass greater than the Earth could cause such a dramatic perturbation of the Earth's rotation?

Would the more distant passage of a star be equally plausible?
 
parsec said:
Is there any mass, position, linear and rotational velocity configuration of a foreign planet or body entering the solar system that could reduce that timescale for the Earth's tidal locking to something in the order of days, weeks or months?
No. Not without ripping Earth apart. You would need many fly-bys or a very close orbit (which is tricky to achieve with a massive object) - in any case, I think the timescale would be at least millenia or more, but I did not check the numbers. It would produce serious, probably periodic floods everywhere apart from some mountains and increase volcano activity a lot.

More distance and more mass can increase the timescale of the influence a bit, but if the numbers get too large you ruin the orbit of Earth as well (long before you see a slowed rotation).
 
It can't be done with a flyby. You need a net torque with no net force.
 
A flyby would induce tides, which give a torque (similar to the earth/moon system). You get a net force and change the orbit, too, of course. As you need multiple flybys, those could cancel in the long run. Not very realistic, but it might be possible to do that in a planned way.
 
  • #10
Maybe I should have said "you can't do it with one flyby".

The most realistic way to handle multiple flybys is an orbit.
 

Similar threads

Replies
9
Views
4K
  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 4 ·
Replies
4
Views
3K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 30 ·
2
Replies
30
Views
5K
  • · Replies 11 ·
Replies
11
Views
2K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 8 ·
Replies
8
Views
2K
  • · Replies 58 ·
2
Replies
58
Views
6K
Replies
18
Views
3K