Can a planet have different levels of gravitational pull

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Discussion Overview

The discussion revolves around the concept of varying gravitational pull on planets, particularly focusing on how gravitational forces can differ based on local mass distribution and density variations. Participants explore theoretical implications and specific examples, including Earth and the Moon.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • Some participants suggest that gravitational pull can vary based on the distribution of mass on a planet, with more mass on one side potentially leading to different gravitational forces.
  • It is noted that the acceleration due to gravity on Earth varies slightly due to altitude and local density differences, with a maximum variation of about 0.7% reported.
  • One participant mentions that the barycenter of mass affects gravitational variation, indicating that while some variation is possible, it is unlikely to exceed 1 or 2% for a planet as defined by the IAU.
  • There is a comparison made between mountains of different densities, suggesting that a mountain with a higher density (like one with an iron core) would exert a stronger gravitational pull than one made of regular rock, assuming similar sizes.
  • Concerns are raised regarding the Moon, with one participant referencing difficulties in maintaining a stable low orbit due to local gravity variations, although specific data on these variations is not provided.

Areas of Agreement / Disagreement

Participants express varying views on the extent and implications of gravitational variation on planets. While some agree on the existence of such variations, the degree and significance of these variations remain contested.

Contextual Notes

Limitations include the lack of specific data on gravitational variations on the Moon and the assumptions made regarding the density and mass distribution of planetary bodies.

!Jon Snow!
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when you approach it from different directions?
 
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Sure, if it had more mass on one side than another...
 
The acceleration due to gravity varies (slightly) on the surface of the earth. Primarily from very low areas to high altitude areas.
 
Yes, to a degree. It depends where the barycenter of mass lies, but you can have variations in gravitational forces at different points on the sphere.

The Earth has some variation due to different local densities in the Earth's crust. The Earth's gravity can vary as much as .7%, which is not very much.

I don't think it is likely that a planet, as defined by the IAU, would have a large degree of gravitational variation beyond 1 or 2%.
 
Thank you all.
 
This is like when there is a mountain with a huge iron core vs a mountain of just regular rock right? whereas the density of the first mountain would increase the gravitational pull?
 
!Jon Snow! said:
This is like when there is a mountain with a huge iron core vs a mountain of just regular rock right? whereas the density of the first mountain would increase the gravitational pull?

Indirectly, yes. Gravitation is the result of mass, so assuming the two mountains are of similar sizes, the one with the greater density has more mass and therefore more gravitational pull.
 
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I don't know what the specific variation on the moon is but I've read that it is such that it is difficult to have a stable low orbit there due to local gravity variations.
 
QuantumPion said:
I don't know what the specific variation on the moon is but I've read that it is such that it is difficult to have a stable low orbit there due to local gravity variations.
One of my favorite articles on this topic: Bizarre Lunar Orbits.
 
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