Question Earth Moon Origin

[Catastrophe]

Inmymind

"One problem is the Moon's iron core is only 1% and Earth's is 13%. If they formed from separate parts of the same cloud they would have the same iron amounts"

Is this not well known? Without checking, I seem to recall that the larger Earth lost only crust and some mantle, whereas the Moon (or precursor) lost also some core to Earth (successor)

Cat

 

[billslugg]

I can see in the videos the interloper's iron core melds with proto-Earth's, then the two bodies mantles mix together and a large amount shoots into space and forms a ring which eventually makes the Moon.

 

[Catastrophe]

Inmymind:

I have had a quick look through my books on the Moon, and those on the Solar System which have appreciable sections on the Moon. The most interesting so far has been one of the older books "Encyclopaedia of the Solar System", Academic Press, 1999.

On page 274, there is a computer simulation of the origin of the Moon by a glancing impact of a body larger than Mars with the early Earth. There are 6 diagrams covering impact plus 1 minute, 10 minutes, 1 hour, 2.3 hours, 4 hours and 24 hours. First contact after 1 minute. After 10 minutes shows impactor mantle just reach ing Earth core, and Earth mantle just reaching impactor core. After 1 hour shows impactor, with greatly reduced core, having separated from Earth. This clearly suggests that some of impactor core transferred to Earth core. Something between 10 minutes and 1 hour would have been interesting. Does anyone else have simulations?

The relevant part of the caption reads "Both the impactor and the Earth have differentiated into a metallic core and rocky silicate mantle. Following the impact, the mantle of the impactor is ejected into orbit. The metallic core* of the impactor clumps together and falls into the Earth within about 4 hours. . . . . . . Most terrestrial mantle material ejected by the impact follows a ballistic trajectory and is reaccreted by the Earth. The metal-poor, low density, Moon is thus derived mainly from the silicate mantle of the impactor" . . . . . . (edit) * and some of the metallic core from the impactor.

Hence the discrepancy.

Cat

 

[Catastrophe]

Here, again, from Wiki "Giant-Impact Hypothesis":

• The Moon has a relatively small iron core, which gives it a much lower density than Earth. Computer models of a giant impact of a Mars-sized body with Earth indicate the impactor's core would likely penetrate deep into Earth and fuse with its own core. This would leave the Moon, which was formed from the ejecta of lighter crust and mantle fragments that went beyond the Roche limit and were not pulled back by gravity to re-fuse with Earth, with less remaining metallic iron than other planetary bodies.

Cat

 

[Inmymind]

Inmymind



Is this not well known? Without checking, I seem to recall that the larger Earth lost only crust and some mantle, whereas the Moon (or precursor) lost also some core to Earth (successor)

Cat

Re ""One problem is the Moon's iron core is only 1% and Earth's is 13%. If they formed from separate parts of the same cloud they would have the same iron amounts"
Billslugg wrote that in post #142, but that is by the by.

(I responded with #145 "You are assuming that the cloud was uniform and they started to form at the same time")

As I recall this discrepancy was one of the main reasons why the third party impact hypothesis was formulated, since at the time co-formation struggled to explain this.

 

[billslugg]

Yes, I understand your objections.
I think things were very well mixed before they started making planets, thus it doesn't really matter when they formed. But in general, things all formed together at the same rates over the same period of time. It was only much later, when large planets could make enough gravity to segregate iron, that differences could show up.
There was one form of separation that is well known, the isotopic differences occurring radially away from the Sun. If the Earth and Moon have the same isotopes, they came from the same distance from the Sun. Maybe there were two bodies formed at Earth orbit distance. Same composition, bumped into each other to form the Moon.

 

[Inmymind]

Inmymind:

I have had a quick look through my books on the Moon, and those on the Solar System which have appreciable sections on the Moon. The most interesting so far has been one of the older books "Encyclopaedia of the Solar System", Academic Press, 1999.

On page 274, there is a computer simulation of the origin of the Moon by a glancing impact of a body larger than Mars with the early Earth. There are 6 diagrams covering impact plus 1 minute, 10 minutes, 1 hour, 2.3 hours, 4 hours and 24 hours. First contact after 1 minute. After 10 minutes shows impactor mantle just reach ing Earth core, and Earth mantle just reaching impactor core. After 1 hour shows impactor, with greatly reduced core, having separated from Earth. This clearly suggests that some of impactor core transferred to Earth core. Something between 10 minutes and 1 hour would have been interesting. Does anyone else have simulations?

The relevant part of the caption reads "Both the impactor and the Earth have differentiated into a metallic core and rocky silicate mantle. Following the impact, the mantle of the impactor is ejected into orbit. The metallic core* of the impactor clumps together and falls into the Earth within about 4 hours. . . . . . . Most terrestrial mantle material ejected by the impact follows a ballistic trajectory and is reaccreted by the Earth. The metal-poor, low density, Moon is thus derived mainly from the silicate mantle of the impactor" . . . . . . (edit) * and some of the metallic core from the impactor.

Hence the discrepancy.

Cat

Maybe the impact hypothesis is correct, but this paper, which was released 2 months ago using data that wasn't available when "Encyclopaedia of the Solar System" was written 25 years go, begs to differ. I would be interested in your and others analysis of this if time can be found :-

Paolo A. Sossia, Miki Nakajimab, Amir Khan

https://arxiv.org/pdf/2408.16840

 

[Harry Costas]

This video may explain one theory. Yet it falls short in calculating orbital speeds to account for the billions of years of stability.

View: https://youtu.be/kRlhlCWplqk

 

[Inmymind]

Yes, I understand your objections.
I think things were very well mixed before they started making planets, thus it doesn't really matter when they formed. But in general, things all formed together at the same rates over the same period of time. It was only much later, when large planets could make enough gravity to segregate iron, that differences could show up.
There was one form of separation that is well known, the isotopic differences occurring radially away from the Sun. If the Earth and Moon have the same isotopes, they came from the same distance from the Sun. Maybe there were two bodies formed at Earth orbit distance. Same composition, bumped into each other to form the Moon.

I get what you and Cat are saying, we might have to wait and see how it plays out as more data comes in. Thanks Bill.

 

[Harry Costas]

Three theories were discussed.

The Origin of the Moon | Astronomy

courses.lumenlearning.com

 

[Harry Costas]

The Sun's Origin may give light to the origin of the moon.

[Submitted on 16 Sep 2024]

The Sun's Birth Environment: Context for Meteoritics​

Steve Desch, Núria Miret-Roig

Meteorites trace planet formation in the Sun's protoplanetary disk, but they also record the influence of the Sun's birth environment. Whether the Sun formed in a region like Taurus-Auriga with ~10^2 stars, or a region like the Carina Nebula with ~10^6 stars, matters for how large the Sun's disk was, for how long and from how far away it accreted gas from the molecular cloud, and how it acquired radionuclides like 26Al. To provide context for the interpretation of meteoritic data, we review what is known about the Sun's birth environment. Based on an inferred gas disk outer radius ~50-90 AU, radial transport in the disk, and the abundances of noble gases in Jupiter's atmosphere, the Sun's molecular cloud and protoplanetary disk were exposed to an ultraviolet flux G0 ~30-3000 during its birth and first ~10 Myr of evolution. Based on the orbits of Kuiper Belt objects, the Solar System was subsequently exposed to a stellar density ~100 Msol/pc^3 for ~100 Myr, strongly implying formation in a bound cluster. These facts suggest formation in a region like the outskirts of the Orion Nebula, perhaps 2 pc from the center. The protoplanetary disk might have accreted gas for many Myr, but a few x10^5 yr seems more likely. It probably inherited radionuclides from its molecular cloud, enriched by inputs from supernovae and especially Wolf-Rayet star winds, and acquired a typical amount of 26Al.

 

[Inmymind]

"The Sun's Origin may give light to the origin of the moon"

How? - impact, co- formation or what?

 

[Inmymind]

"The Sun's Origin may give light to the origin of the moon"

How? - impact, co- formation or what?

Conflation does not help.

 

[Catastrophe]

Re ""One problem is the Moon's iron core is only 1% and Earth's is 13%. If they formed from separate parts of the same cloud they would have the same iron amounts"

We were not discussing formation, we were discussing the results of collision, which was when the differential occurred. There is no "problem".

OK. You do not seem happy with the obvious solution. I am. So I am content to leave you to your conclusions, and hope you will see the logical solution on further deliberation.

I do not have further time to waste on alternatives, but thank you for your obvious interest.

Cat

 

[Harry Costas]

Science always has time.
To accept a theory without evidence is not science.
To talk over the options is science through the ages.

If the MOB says jump.
What do you do?

 

[Inmymind]

We were not discussing formation, we were discussing the results of collision, which was when the differential occurred. There is no "problem".

OK. You do not seem happy with the obvious solution. I am. So I am content to leave you to your conclusions, and hope you will see the logical solution on further deliberation.

I do not have further time to waste on alternatives, but thank you for your obvious interest.

Cat

The post is re "the Earth Moon Origin", for me the obvious solution is co-formation, especially with new data coming through, which I gave you a link to and you do not want to waste your time on. The giant impact theory seems to be able to be modelled to suit any composition. We will see what emerges. Why so condescending?

 

[Harry Costas]

The Hunt for the Origin and evolution of our Solar System is never-ending.
We must be aware of the limitations of drawing theories and conclusions from limited information.


[Submitted on 29 Sep 2024]

A Multi-station Meteor Monitoring (M3) System. I. Design and Testing​

Z. Li, H. Zou, J. Liu, J. Ma, X. Zhao, X. Li, Z. Tu, B. Zhang, R. Wang, S. Wang, Marco Xue

Meteors carry important and indispensable information about the interplanetary environment, which can be used to understand the origin and evolution of our solar system. We have developed a Multi-station Meteor Monitoring (M3) system that can observe almost the entire sky and detect meteors automatically, and it determines their trajectories. They are highly extensible to construct a large-scale network. Each station consists of a waterproof casing, a wide field-of-view lens with a CMOS camera, and a supporting computer. The camera has a built-in GPS module for accurately timing the meteoroid entry into the atmosphere (accurate to 1 μs), which is the most prominent characteristic compared with other existing meteor monitoring devices. We have also developed a software package that can efficiently identify and measure meteors appearing in the real-time video stream and compute the orbits of meteoroids in the solar system via multi-station observations. During the Geminid meteor shower in 2021, the M3 system was tested at two stations (∼55 km apart) in the suburbs of Beijing. The test results show that the astrometric accuracy is about 0.3-0.4 arcmin. About 800 meteors were detected by these two stations. A total of 473 meteors have their orbits calculated by our software, and 377 of them belong to the Geminid meteoroid stream. Our M3 system will be further tested and upgraded, and it will be used to construct a large monitoring network in China in the future.

 

[Harry Costas]

""Why so condescending?""

If I have insulted anybody.
It was not intentional.

 

[Inmymind]

""Why so condescending?""

If I have insulted anybody.
It was not intentional.

Don't worry, my post was not responding to you

 

[Catastrophe]

The post is re "the Earth Moon Origin", for me the obvious solution is co-formation, especially with new data coming through, which I gave you a link to and you do not want to waste your time on. The giant impact theory seems to be able to be modelled to suit any composition. We will see what emerges. Why so condescending?

The post is re "the Earth Moon Origin", for me the obvious solution is co-formation, especially with new data coming through, which I gave you a link to and you do not want to waste your time on. The giant impact theory seems to be able to be modelled to suit any composition. We will see what emerges. Why so condescending?

"The co-formation hypothesis states that the Moon formed in orbit around Earth at the same time as the Earth formed. Their composition should be similar—they should be made of the same materials in the same relative amounts, unless something happened later to change one of them." Google.

 

[Inmymind]

"The co-formation hypothesis states that the Moon formed in orbit around Earth at the same time as the Earth formed. Their composition should be similar—they should be made of the same materials in the same relative amounts, unless something happened later to change one of them." Google.

Unless the Moon started to form slightly later, or elsewhere when/where the iron etc volatile composition of the volume that it was forming within lacked the same proportion of those, compared to the Earth.

Other than that they are similar - too similar it seems for the impact hypothesis to account for. I am no expert, as you can tell, and beyond what I have posted earlier, have nothing more to say, which is why I invited a discussion wrt to this paper which challenges your, and the impact proposition :-

Paolo A. Sossia, Miki Nakajimab, Amir Khan

https://arxiv.org/pdf/2408.16840

 

[Harry Costas]

More info is required.
We cannot draw the conclusion yet.
Maybe soon

 

[Catastrophe]

Unless the Moon started to form slightly later, or elsewhere when/where the iron etc volatile composition of the volume that it was forming within lacked the same proportion of those, compared to the Earth.

Other than that they are similar - too similar it seems for the impact hypothesis to account for. I am no expert, as you can tell, and beyond what I have posted earlier, have nothing more to say, which is why I invited a discussion wrt to this paper which challenges your, and the impact proposition :-

Paolo A. Sossia, Miki Nakajimab, Amir Khan

https://arxiv.org/pdf/2408.16840

Did you read all 50+ pages?

 

[Catastrophe]

I can see in the videos the interloper's iron core melds with proto-Earth's, then the two bodies mantles mix together and a large amount shoots into space and forms a ring which eventually makes the Moon.

Billslugg, did you mean this one?

View: https://www.youtube.com/watch?v=kRlhlCWplqk


Cat

 

[billslugg]

I had not seen that one, it is really detailed. It gives two bodies, one of which falls back to Earth, the other stays out there to become the Moon. What is very evident is that the outcome is extremely dependent on the offset between the two bodies. This means that the impact scenario is flexible, can account for most any observation today simply by changing where it hit.
I would like to see a similar movie showing how an accretion scenario might work out.