Origin of the Moon

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What's the latest about the origin of the moon?

Is it true the moon is older than the earth? how?
 

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  • #2
phinds
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What's the latest about the origin of the moon?

Is it true the moon is older than the earth? how?
What has your research discovered so far?
 
  • #4
PeterDonis
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Moderator's note: moving thread to Astronomy & Astrophysics as it seems more likely to get useful responses there.
 
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Is there possibility the moon was a separate planet before and it decayed now with earth being younger and exist after the moon?

Where can I get all theories and model of the moon origin?
 
  • #6
PeterDonis
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Where can I get all theories and model of the moon origin?
Where have you looked already?
 
  • #7
davenn
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What have we really found out when we did carbon dating on the moon?
you cannot do carbon dating on moon rocks as there is no organic carbon ( living/dead plant life) with which to do carbon dating on


Where can I get all theories and model of the moon origin?
google for them, BUT make sure you are reading peer reviewed research papers and not inaccurate media reports :smile:

Dave
 
  • #8
Drakkith
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Is it true the moon is older than the earth? how?
Possible, but unlikely. Earth's tectonic activity has buried the oldest rocks, so we may measure Moon rocks as being slightly older (I'm not sure if they've done this). But the Earth is likely to be just as old as the Moon, if not slightly older. Isotope ratios of various elements from the Moon are extremely close to those of the Earth, which is evidence that the Moon and the Earth were formed from the same material. If we look at samples from other planets or bodies in the solar system, we find that they all have unique isotope ratios. If the Moon had formed from a different body of material than the Earth then there should be no reason for these isotope ratios to be so similar.
 
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Possible, but unlikely. Earth's tectonic activity has buried the oldest rocks, so we may measure Moon rocks as being slightly older (I'm not sure if they've done this). But the Earth is likely to be just as old as the Moon, if not slightly older. Isotope ratios of various elements from the Moon are extremely close to those of the Earth, which is evidence that the Moon and the Earth were formed from the same material. If we look at samples from other planets or bodies in the solar system, we find that they all have unique isotope ratios. If the Moon had formed from a different body of material than the Earth then there should be no reason for these isotope ratios to be so similar.
Is it possible the material of the earth came from the moon? The moon being much larger before and was a planet.. then something happened to the moon maybe a collision that created the earth (being ejected from the material of the moon)? What tectonic, observational data refutes this?
 
  • #10
davenn
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Is it possible the material of the earth came from the moon? The moon being much larger before and was a planet.. then something happened to the moon maybe a collision that created the earth (being ejected from the material of the moon)?

not likely. as the Moon orbiting the Earth pretty much discounts that

What tectonic, observational data refutes this?
probably none .... it's more the physics of collisions and the results thereof that most likely wouldn't allow the results we see today
Moon orbiting Earth (small body orbiting a larger body)
 
  • #11
Drakkith
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Is it possible the material of the earth came from the moon? The moon being much larger before and was a planet.. then something happened to the moon maybe a collision that created the earth (being ejected from the material of the moon)?
I believe davenn's explanation is correct. The physics of the collision probably don't allow for such a thing.

What tectonic, observational data refutes this?
The fact that the Earth contains a substantial amount of iron in its core while the Moon does not is pretty strong evidence that the Moon came from the Earth and not vice versa. A collision shouldn't eject most of the heavy elements from an object while leaving behind mostly lighter elements. However, the opposite is certainly possible. The heavy elements sink towards the core (because of their density) while the lighter elements remain near the outside and eventually form most of the crust. A glancing collision then ejects a large amount of this outer material, which gives us a moon made up of light elements with very little heavier elements. And that's exactly what observations tell us the Moon is composed of.
 
  • #12
davenn
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The fact that the Earth contains a substantial amount of iron in its core while the Moon does not is pretty strong evidence that the Moon came from the Earth and not vice versa. A collision shouldn't eject most of the heavy elements from an object while leaving behind mostly lighter elements. However, the opposite is certainly possible. The heavy elements sink towards the core (because of their density) while the lighter elements remain near the outside and eventually form most of the crust. A glancing collision then ejects a large amount of this outer material, which gives us a moon made up of light elements with very little heavier elements. And that's exactly what observations tell us the Moon is composed of.
nice explanation ... :smile:
I should have thought of that haha :rolleyes:
 
  • #13
Chronos
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The age of the moon has been pegged at 4.51 billion years [re: http://advances.sciencemag.org/content/3/1/e1602365.full] making it slightly younger than earth, which is generally accepted to be 4.54 billion years. It is still generally believed the moon formed from debris ejected during a collision between earth and a planet called Theia in the infant solar system. This is known as the giant impactor theory. The age of the moon was determined radiometrically through isotopes extracted from zircon crystals in rocks retrieved during the Apollo 14 mission
 
  • #14
russ_watters
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Is it possible the material of the earth came from the moon? The moon being much larger before and was a planet.. then something happened to the moon maybe a collision that created the earth (being ejected from the material of the moon)? What tectonic, observational data refutes this?
not likely. as the Moon orbiting the Earth pretty much discounts that
How is this *actually* different? If we swap the words "Earth" and "Moon" in the descriptions, has anything actually changed?

[edit] The only thing I see is that "Moon" isnt just a proper name, it is a type of object. So despite the descriptions of the event being the same, it wouldn't be correct terminology to label an object alone in its orbit to be a "moon".
 
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  • #15
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Is it possible the material of the earth came from the moon? The moon being much larger before and was a planet.. then something happened to the moon maybe a collision that created the earth (being ejected from the material of the moon)? What tectonic, observational data refutes this?
One of the most well supported models is similar to this but the other way around.
A quite large protoplanet, about Mars sized; collided with proto Earth.
This ejected a very substantial amount of Earth's crust (if had a crust as such at that time). along with remnants of the smaller planet.
The orbiting debris then coalesced to become our Moon.
 
  • #16
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The age of the moon has been pegged at 4.51 billion years [re: http://advances.sciencemag.org/content/3/1/e1602365.full] making it slightly younger than earth, which is generally accepted to be 4.54 billion years. It is still generally believed the moon formed from debris ejected during a collision between earth and a planet called Theia in the infant solar system. This is known as the giant impactor theory. The age of the moon was determined radiometrically through isotopes extracted from zircon crystals in rocks retrieved during the Apollo 14 mission
If moon came from earth debris.. they should be same age or near

now ignoring for the moment the core concentration data... is it possible the moon has existed for the first 4.51 billion year and then the earth came from the debris of the moon 2.5 billion years ago.. however, since it came from the moon, then the carbon dating of the materials of the earth would still be 4.51 billion years or so (remember we only have one sample to determine the age of the moon so let's assume moon and earth age was identical for sake of this discussion)..

so the theory is living things first evolved in the moon. Then 2.5 billion years ago.. something happened where the moon decayed (accidental or on purpose) and the materials were ejected to form a new planet (earth). Here since the material of the earth came from the moon, the age would be identical although the earth just formed 2.5 billion years ago.. is there any carbon dating argument that can refute this possibility (again ignoring core concentration data and others for sake of discussion)?
 
  • #17
Drakkith
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If moon came from earth debris.. they should be same age or near
Both the Earth and the Moon have been measured as being very close to the same age. Note that these measurements are measuring the age of certain formations of rocks. The material making up the rocks existed as molten lava/magma prior to solidifying into the rocks we see today, and our measurements only date this solidification. Just because we measure a rock as being a certain age does not mean that a body isn't a bit older.

now ignoring for the moment the core concentration data... is it possible the moon has existed for the first 4.51 billion year and then the earth came from the debris of the moon 2.5 billion years ago.. however, since it came from the moon, then the carbon dating of the materials of the earth would still be 4.51 billion years or so (remember we only have one sample to determine the age of the moon so let's assume moon and earth age was identical for sake of this discussion)..
No. That's not possible. The melting of the material as it was ejected and then coalesced again would end up giving us an entirely different date for the formation of the Earth.

so the theory is living things first evolved in the moon. Then 2.5 billion years ago.. something happened where the moon decayed (accidental or on purpose) and the materials were ejected to form a new planet (earth). Here since the material of the earth came from the moon, the age would be identical although the earth just formed 2.5 billion years ago.. is there any carbon dating argument that can refute this possibility (again ignoring core concentration data and others for sake of discussion)?
Yes. All radioactive dating giving us an age past 2.5 billion years ago refutes this.
 
  • #18
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Both the Earth and the Moon have been measured as being very close to the same age. Note that these measurements are measuring the age of certain formations of rocks. The material making up the rocks existed as molten lava/magma prior to solidifying into the rocks we see today, and our measurements only date this solidification. Just because we measure a rock as being a certain age does not mean that a body isn't a bit older.



No. That's not possible. The melting of the material as it was ejected and then coalesced again would end up giving us an entirely different date for the formation of the Earth.



Yes. All radioactive dating giving us an age past 2.5 billion years ago refutes this.
why.. if the earth formed 2.5 billion years ago from 4.51 billion years old material from the moon.. why would carbon dating show 2.5 billion years instead of 4.51?
 
  • #19
Drakkith
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why.. if the earth formed 2.5 billion years ago from 4.51 billion years old material from the moon.. why would carbon dating show 2.5 billion years instead of 4.51?
Because radioactive dating relies on measuring the proportion of different isotopes of an element, or the proportion of two elements linked by radioactive decay, in a rock/mineral. For example, uranium is incorporated into the mineral zircon and decays into lead over time. However, zircon strongly rejects lead when it initially forms, so all of the lead we find inside the mineral must be from the decay of uranium. By measuring the proportion of uranium to lead we can calculate the age of the zircon.

But if I melt the zircon down and let it reform, then the lead is once again rejected, so measuring the uranium-lead ratio would give a much younger date.
 
  • #20
davenn
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why.. if the earth formed 2.5 billion years ago from 4.51 billion years old material from the moon.. why would carbon dating show 2.5 billion years instead of 4.51?
I have already told you ... THERE IS NOTHING TO CARBON DATE from the moon

please understand that

and we know the earth is older than 2.5 billion years
 
  • #21
PeterDonis
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Thread closed as the OP question has been addressed and personal speculation is out of bounds for PF.
 

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