What would happen to Earth without the moon?

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Discussion Overview

The discussion centers on the potential consequences for Earth if the Moon did not exist, exploring various theoretical implications on Earth's rotation, axial stability, and the development of life. Participants examine both the physical mechanics involved and the broader ecological impacts.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants question the claim that the Moon stabilizes Earth's axial tilt, suggesting that the wobble of the axis occurs independently of the Moon.
  • Others propose that without the Moon, the length of a day would be significantly shorter, potentially around eight hours.
  • There are assertions that the absence of the Moon could lead to stronger winds and a different biological evolution of life on Earth.
  • Some participants express uncertainty about the extent of the Moon's influence on Earth's rotation and axial precession, noting the complexity of modeling these effects.
  • Concerns are raised about the Moon's role in shielding Earth from meteors and its impact on the early atmosphere.
  • Discussion includes the idea that tidal effects from the Sun would still exist, but would result in fewer tidal bulges compared to the current situation with the Moon.
  • Some participants speculate about the potential effects of external forces, such as solar wind, on Earth's rotation, while others argue that significant momentum transfer is required for such changes.
  • There are discussions about the torque needed to alter Earth's rotation over geological timescales, with some participants suggesting that the Moon's tidal effects have been correlated with observed changes in Earth's rotation.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the Moon's role in stabilizing Earth's axial tilt or its overall impact on Earth's rotation and biological evolution. Multiple competing views and uncertainties remain throughout the discussion.

Contextual Notes

The discussion highlights the challenges in modeling the dynamics of Earth's rotation and axial stability, as well as the dependence on various assumptions regarding the Moon's influence and external forces.

Ulysees
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There's a documentary with this title, haven't seen it yet but would like to see it. The premise of the film is, among others, that the Earth's axis would wobble (therefore unstable seasons) causing many other things to happen if the moon did not exist, but it does not seem obvious to me at all.

Why would the axis wobble? It wobbles already for sure, giving rise to the Age of the pisces and the Age of aquarius etc as the axis passes through constellations. But why would the moon make a difference?

Any dynamic simulation of this effect? Any youtube video or software to demonstrate it?
 
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If that is an effect, it is a minor one. From http://www.astrosociety.org/education/publications/tnl/33/33.html (third page), the primary effects of an Earth sans the Moon would be
  1. The day would be eight hours long.
  2. The winds would be much stronger.
  3. Complex life might not exist yet.
  4. When life did arrive, it would have a different biology.
 
So no mention of the axis changing? The claim that the axis is kept fixed by the moon is false?
 
It's a difficult thing to be sure about - surprisingly it's very hard to model what looks like very simple classical mechanics!
The moon will definitely have an effect on the Earth's rotation but quite how much the precession would be without it I'm not sure.

There are also theories that it swept up elements from the early atmosphere and sheilds the Earth from meteors which would also have a big effect on life.
 
didnt the Earth effect the rotation of the moon as it slowly got farther away,then finaly the moon no longer has a rotation?
 
so if it did, couldn't you say that the moon effected the rotation of the Earth in some way? maybe a slower rotational speed? but began faster as the moon moved away in after time?
 
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List's of effect's

mgb_phys said:
It's a difficult thing to be sure about - surprisingly it's very hard to model what looks like very simple classical mechanics!
The moon will definitely have an effect on the Earth's rotation but quite how much the precession would be without it I'm not sure.

There are also theories that it swept up elements from the early atmosphere and sheilds the Earth from meteors which would also have a big effect on life.

Yes it would, there are a lot of effects that would take place that would range from mild to extreme, Make's me wonder what would happen if somthing big hit the moon and alterd its path and tilt.
 
D H said:
[*]The day would be eight hours long.

Is it possible that something else also slows down the Earth's self-rotation? Like the solar wind?
 
Ulysees said:
Is it possible that something else also slows down the Earth's self-rotation? Like the solar wind?
Nope - you need something that can transfer momentum ( and quite a lot of it)
Tidal friction with the sun would eventually slow the Earht's rotation (as it has for mercury) but the effect is smaller because of the distance to the sun and so it would take longer to slow us down.
 
  • #10
well if the moon did not exist the tides would be very minimal do to the fact that the sun still has its affects. the lunar bulge affect on the Earth would no longer exists therefore there would be 2 bulges left instead of the standard 4 that we are used to.
 
  • #11
there should be no inflictions of the rotation velocity. well not that i can see. the moon does not add momentum but i understand the bobbling affect. can u explain its momentum given off please? i am in the dark on the subject of momentum
 
  • #12
mgb_phys said:
Nope - you need something that can transfer momentum ( and quite a lot of it)

How much do you think? In other words, how much torque is required to slow the self-rotation of the Earth from an 8-hour day to a 24-hour day over 4.000.000.000 years?

That's a change of about 1 second per 70000 years. Maybe the necessary torque for this is comparable to the torque exerted by the solar wind as it is diverted by the Van Allen belts!
 
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  • #13
In fact I suspect they have forced the moon's tidal effect to match the observed change in the self-rotation of the earth. In other words, if the corral reefs showed a day duration of 12 hours instead of 8 hours at a given time, then they would still say the change from then to now was caused by the moon.
 
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