Where did the moon get its orbiting energy?

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Discussion Overview

The discussion revolves around the origins of the moon's orbital energy and the mechanisms behind the formation of orbits in general, including the moon's specific case and broader concepts applicable to other celestial bodies in the Solar System.

Discussion Character

  • Exploratory
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant questions where the moon initially acquired the energy necessary for its tangential velocity to maintain its orbit around Earth.
  • Another participant suggests that the leading theory for the moon's formation involves an impact that separated it from Earth, though they note the lack of conclusive evidence for this theory.
  • Some participants assert that the prevailing theory involves a Mars-sized planetoid impacting Earth, but they also highlight that understanding the moon's origin does not necessarily clarify the orbital velocities of other moons in the Solar System.
  • A participant expands the discussion to include how orbits are formed generally, mentioning that the Solar System formed from a rotating disc of dust and gas, which provided the initial orbital velocities for the planets.
  • It is noted that the energy for these celestial objects originates from the Big Bang and is retained through gravitational interactions, with angular momentum being a key factor in maintaining orbits.

Areas of Agreement / Disagreement

Participants express uncertainty regarding the moon's formation and its orbital energy, with multiple competing theories presented. The discussion remains unresolved as participants explore various aspects of orbital mechanics and formation.

Contextual Notes

There are assumptions regarding the nature of orbital formation and the initial conditions of celestial bodies that are not fully explored or agreed upon. The discussion includes references to specific theories without consensus on their validity.

Red_CCF
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For the moon to stay in orbit and not crash down into Earth, it must have sufficient tangential velocity. I'm wondering where/how it initially got the energy to reach this tangential velocity.

Thanks.
 
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Nobody's really sure how the moon formed or exactly why it got put into the orbit it did. The leading theory, I think, is that there was some kind of impact that split it off from the Earth, but there's no conclusive evidence.

What we do know is that the moon does have sufficient tangential velocity to stay in orbit. So no crashing is in the foreseeable future.
 
Yes, I believe an impact from a Mars-sized planetoid is the prevailing theory.

Note to the OP: are you only interested in the Moon specifically? The Moon's origin does not help you understand the orbital veolcities of any other moons in the Solar System.
 
DaveC426913 said:
Yes, I believe an impact from a Mars-sized planetoid is the prevailing theory.

Note to the OP: are you only interested in the Moon specifically? The Moon's origin does not help you understand the orbital veolcities of any other moons in the Solar System.

Actually I'm interested generally on how orbits are formed, for instance how is Earth's orbit around the sun formed? Generally what is giving energy to extra-terrestrial objects to allow them to move at enough velocity to gain an orbit.
 
Red_CCF said:
Actually I'm interested generally on how orbits are formed, for instance how is Earth's orbit around the sun formed?
The Solar System including Sun and Earth formed as a unit, coalescing from a disc of dust and gas. The orbital velocity of almost all the planets in the SS was intrinsic to that initial rotating disc.

Pluto, being an exception, was possibly captured after the SS was formed.

Red_CCF said:
Generally what is giving energy to extra-terrestrial objects to allow them to move at enough velocity to gain an orbit.
There are lots of assumptions here. They don't gain an orbit - they start as a rotating discs of dust and gas. They got their initial energy ultimately from the Big Bang, then later as they gathered under gravity, they retained their angular momentum (like an ice skater pulling in her arms).
 

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