What would happen to Earth without the moon?

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In summary: There's a documentary with this title, haven't seen it yet but would like to see it. Its premise 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. It's a difficult thing to be sure about - surprisingly it's very hard to model what looks like very simple classical mechanics! But if the axis did change, it would cause many different effects, some of which we are currently experiencing. There's no mention of the axis changing in the film, but the claim that the axis is kept fixed by the moon is false.
  • #1
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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  • #2
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.
 
  • #3
So no mention of the axis changing? The claim that the axis is kept fixed by the moon is false?
 
  • #4
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.
 
  • #5
didnt the Earth effect the rotation of the moon as it slowly got farther away,then finaly the moon no longer has a rotation?
 
  • #6
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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  • #7
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.
 
  • #8
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?
 
  • #9
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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1. What would happen to the Earth's tides if the moon did not exist?

If the moon did not exist, the tides on Earth would be significantly lower. The moon's gravitational pull is responsible for creating the tides by pulling on the Earth's oceans.

2. How would the absence of the moon affect the Earth's climate?

The moon plays an important role in stabilizing the Earth's tilt, which helps regulate the planet's climate. Without the moon, the Earth's tilt would vary much more, leading to extreme and unpredictable weather patterns.

3. Would there still be lunar eclipses if the moon did not exist?

No, lunar eclipses occur when the Earth passes between the sun and the moon, casting a shadow on the moon. Without the moon, there would be no object for the Earth to cast a shadow on, so lunar eclipses would not occur.

4. How would the absence of the moon affect life on Earth?

The moon has played a crucial role in the development and evolution of life on Earth. Without the moon, the Earth's rotation would be much faster, resulting in shorter days and potentially harsher climate conditions. This could greatly impact the survival of certain species.

5. Could the Earth's orbit be affected if the moon did not exist?

Yes, the moon's gravity helps stabilize the Earth's orbit around the sun. Without the moon, the Earth's orbit would likely be more elliptical, leading to more extreme and unpredictable changes in distance from the sun. This would have a major impact on the Earth's climate and potentially make it difficult for life to thrive.

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