crazy theory?: Moon created by nuke explosion

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silylene

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I know this sounds woo. I think it does., However, it is seriously proposed.

arXiv reference, click on the pdf (22 pages) to read: http://arxiv.org/abs/1001.4243

http://news.discovery.com/earth/did-a-nuclear-blast-give-birth-to-the-moon.html

Did a Nuclear Blast Give Birth to the Moon?
By Michael Reilly | Fri Jan 29, 2010 12:18 AM ET

Looking at the silvery Moon hanging in the sky, it's hard to believe that quiet, comforting night light was formed in an episode of incredible violence several billion years ago.

But that's exactly what scientists are proposing in a new theory about Luna's formation: they think a massive nuclear explosion occurred at the edge of Earth's core, flinging red-hot, liquid rock into space. The orbiting detritus gradually congealed into what is now our planet's lone satellite.

If this holds any water, it's bound to be controversial. Most scientists believe that the Moon formed from the debris left over when a Mars-sized object hit our newly-formed planet around 4.5 billion years ago. This is based on several modeling studies that provide a pile of evidence in favor of the idea.

There are some holes, though. For one, the Moon's chemistry is very similar to Earth's. That makes sense until you consider that in a titanic impact like the one proposed, a good portion of the offending object would be melted, vaporized, and incorporated into the wreckage that eventually formed the Moon.

But if there was no impact, there's still the matter of the explosion -- how do you get a nuclear bomb to go off in the middle of the planet?

Well, the researchers think that as the molten Earth spun, radioactive thorium and uranium accumulated at the boundary between the core and mantle in large enough quantities to spark a runaway fission reaction. Heat and energy built up until Whamo! A nuclear jet pushed giant globs of molten rock into space.

Sound like a crazy idea? It is, but the scientists think there's a way to test the idea: look for isotopic signatures on the Moon left over from when the "georeactor" exploded. If they're there, it's a good chance that Earth once went critical in a huge way, and our ghostly galleon was tossed into the heavens by the world's first nuclear detonation.
 
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3488

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Hi silylene, to me it looks like woo & IMO should not be taken seriously.

If radioactive isotopes on the outer core / lower mantle boundary did go critical, then why did it only happen once?

Had the Earth already differentiated by this time?

Where there enough radioisotopes present to trigger an explosion of that magnitude?

Why do we not see similar evidence with Venus & Mercury?

Would such a detonation accelerate such a huge amount of material to near escape velocity?

Just a few problems already apparent.

Andrew Brown.
 
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JonClarke

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Bona fide researchers in a bona fide journal postulating something that is almost certainly gibbering lunacy.

The biggest problem is that uranium and thorium are extremely lithophile elements whereas nickel and iron are strongly siderophile. Expecting enough uranium and thoriumn to partition into the core to generate a nuclear reaction is about as likely as expecting something to fall up.
 
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silylene

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Hello Jon, good to hear from you again!

Jon and Andrew, I agree this hypothesis has a high degree of bogacity! I still thought it was interesting enough to post here.

A couple of other random thoughts:
I do recall reading another very recent paper which made a good argument based on simulation that the Moon could not have been formed by the current leading theory (recondensed from the residue remaining from a large planetoid collision with early earth). However, this paper argues against a large body of modeling and geological data which suggested otherwise.

On the nuclear explosion theory, I also have a very hard time accepting that a nuclear explosion could have enough energy to rip apart a planet. I know it is very difficult to purposefully design a large nuclear bomb to have the materials purity and the precision of construction to generate enough multiple generations of yield enhancement to generate a high yield explosion without ripping the bomb itself apart prematurely- and this purposeful bomb is far, far smaller than the yield necessary to destroy a planet.
 
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3488

Guest
I agree it is wonderful to hear from Jon Clark again.

I tried to think of something similar to Jon Clark's doubts about the required concentrations of radioctive isotopes in relation to the iron & nickel & as the article appears to concentrate of the outer core, lower mantle boundary, the further dilution of said isotopes in iron sulphide & silicate rick material. Not to mention IMO the compression at that depth insode the Earth would over come a potential nuclear detonation.

It is just sheer woo woo nonsense beyond belief, which somehow has got the attention of serious Geologists & Planetary Scientists.

You were certainly right to bring this here silylene as it is an interesting topic to discuss & I thank you for that very much.

Andrew Brown.
 
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MeteorWayne

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Note that the paper has been submitted, not accepted.

I'm sure the ratio of submissions to acceptance is quite high for reputable peer reviewed journals.
 
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Saiph

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yeah, my two big bones of contention, just from your synopsis are...

how does spinning concentrate the uranium in the mantle...the earth doesn't spin fast enough for that sort of centrifugal seperation to occur...


and how does a massive nuclear explosion not cause the same melting and vaporization problem as a big impact? At those energy levels the general affects will be the same. the only difference would be massive amounts of nuclear fallout..
 
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CalliArcale

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One big red flag for me is the term "georeactor". It seems the authors have confused a nuclear reactor with a nuclear bomb. They are very different entities. It also seems to be about a zillion-to-one chance; far too much has to go right. An impactor seems much more plausible, given that this sort of thing has been known to happen elsewhere in the solar system.
 
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JonClarke

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silylene":cohlb5l2 said:
Hello Jon, good to hear from you again!
Yes, I am spending minimal time on blogs thee days because of work and real life in general.

Jon and Andrew, I agree this hypothesis has a high degree of bogacity! I still thought it was interesting enough to post here.
Bogus might be harsh, I don't think it is fraudulent. It just isn't crazy enough to be true.

A couple of other random thoughts:
I do recall reading another very recent paper which made a good argument based on simulation that the Moon could not have been formed by the current leading theory (recondensed from the residue remaining from a large planetoid collision with early earth). However, this paper argues against a large body of modeling and geological data which suggested otherwise.
Yes, some people still are not happy with the impact idea. Supposedly the geochemical solutions are not unique and there are issues with the partioning of tungsten and hafnium. Far to technical for me!

On the nuclear explosion theory, I also have a very hard time accepting that a nuclear explosion could have enough energy to rip apart a planet. I know it is very difficult to purposefully design a large nuclear bomb to have the materials purity and the precision of construction to generate enough multiple generations of yield enhancement to generate a high yield explosion without ripping the bomb itself apart prematurely- and this purposeful bomb is far, far smaller than the yield necessary to destroy a planet.
Indeed. And to get an explosion you need high enriched pure uranium, not the slightly enriched form and percent grades that allow natural reactors in old rocks.
 
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silylene

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Hello Jon,

Seems you agree with some critics of the nuclear Moon hypothesis:
http://www.newscientist.com/blogs/shortsharpscience/2010/02/critics-blast-nuclear-bomb-the.html

February 1, 2010 6:07 PM
Critics blast nuclear 'bomb' theory of moon's birth
Marcus Chown, contributor

The moon was created by a jet of matter that stabbed out of the Earth's interior, where it originated in a runaway uranium fission reactor at the boundary between the core and mantle. Wow! This is the stuff of science-fiction movies. And it has certainly grabbed headlines across the world. But does the amazing idea, promoted in an online paper by Rob de Meijer of the University of the Western Cape in South Africa and Wim van Westrenem of VU University Amsterdam, stand up to scrutiny?

Marvin Herndon, an independent geophysicist based in San Diego, previously put forward the controversial hypothesis that uranium, the heaviest naturally occurring element, has sunk to the Earth's core and formed a "georeactor" several kilometres across (see Fire down below). But even he points out that such a reactor could not exist at the core-mantle boundary. That's because uranium is so heavy that when it liquefies in a nuclear reaction, it should fall to the Earth's core. "Meijer and Westrenem fail to realise that such a georeactor would melt itself down to the centre," he told me.

Others question the idea that a runaway reactor would shoot out of the Earth as proposed, since modelling this kind of explosion is far from trivial. "How do they really know it would produce a thin jet of matter?" says astrophysicist Richard Gott of Princeton University.

Planetary physicist David Stevenson of Caltech is also sceptical. "The whole idea is not physically sensible," he says. "Life is too short to spend on things like this."

If the georeactor hypothesis is right, Gott questions why Venus did not form a moon in the same process, since Venus boasts a similar mass and composition to the Earth. "OK, it might have just been a fluke it happened to the Earth but not Venus," he says. "But how do you explain Charon, the big icy moon of Pluto? That would require an 'ice-reactor', which is a nonsensical idea!"

But the biggest hole in the idea is not that it is unnecessarily complicated – it is simply unnecessary. In the standard "big splash" picture of the moon's origin, the infant Earth was struck by a Mars-mass impactor, dubbed Theia. Some of the impactor, along with the Earth's mantle, formed a ring around the Earth that eventually congealed into the moon.

The main reason Meijer and van Westrenem concocted their scenario was to explain why the composition of the moon and the Earth's mantle are identical when the moon should have been contaminated by material from the impactor. "The simple answer is that the impactor formed from material at the same distance from the sun as the Earth, and therefore had the same composition," says Gott. This could have happened if the body formed at either the stable Lagrange-4 or Lagrange-5 points, 60° behind and ahead of the Earth in its orbit around the sun. This idea was proposed by Gott and his Princeton colleague Edward Belbruno in 2004. "The impact scenario, with the impactor coming from a Lagrange point, fits pretty much all the observations," says Gott.
 
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UFmbutler

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JonClarke":16c9ixt4 said:
Bona fide researchers in a bona fide journal postulating something that is almost certainly gibbering lunacy.

The biggest problem is that uranium and thorium are extremely lithophile elements whereas nickel and iron are strongly siderophile. Expecting enough uranium and thoriumn to partition into the core to generate a nuclear reaction is about as likely as expecting something to fall up.
I'd hesitate to call the author bona fide. If you look at his ADS entry, he has no noteworthy publications, with the exception of one paper in "Earth, Moon, and Planets"(it's not clear if that journal is peer reviewed or not though), and has only appeared at conferences(probably hosted by himself or a friend), and submitted papers on arxiv. That alone doesn't condemn his idea, but it means everyone should view it with extreme skepticism. It is interesting to think of alternatives to the moon's formation though..unfortunately this kind of event happening just doesn't really make much physical sense.

Edit: I slightly disagree with the above article regarding Pluto's moon. Not all moons have to be created and captured in the same way - Charon could just be a result of gravitational capture or maybe it formed in situ. This doesn't make the nuclear "bomb" theory any more credible though.
 
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yevaud

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silylene":14u1h1zh said:
But the biggest hole in the idea is not that it is unnecessarily complicated – it is simply unnecessary.
The overy convoluted and complicated idea is usually not what you see in nature; you see elegantly simple mechanisms. That's my spin on it.
 
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silylene

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yevaud":1pxguwwv said:
silylene":1pxguwwv said:
But the biggest hole in the idea is not that it is unnecessarily complicated – it is simply unnecessary.
The overy convoluted and complicated idea is usually not what you see in nature; you see elegantly simple mechanisms. That's my spin on it.
Well a nuclear Moon explosion is simple...but wrong. On the other hand, the collision theory for the formation of the Moon is also rather simple.
 
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yevaud

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Well, I'd think the collision theory is the far simpler and more correct. After all, we know and have seen collisions taking place before, and the mechanism is pretty straightforward. On the other hand, the Nuclear Explosion idea requires too many improbables to all occur in tight sequence. After all, as you know, nuclear explosions don't just...occur.
 
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silylene

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Maybe a U235 rich asteroid hit the earth, and created a heavy mascon of U235 which sank into the crust until it encountered another waiting mass of U235 in the mantle, and the combined mass of fissile materials exceeded the critical mass...coincidentally enveloped in masses of neutron reflective minerals rich in Be, C and saturated with deuterium rich water ....and the high pressures deep in the mantle held the blast long enough to yield multiple iterations of nuclear amplification...BOOM!

yea too complex... :lol:
 
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yevaud

Guest
silylene":hxd7dvbs said:
Maybe a U235 rich asteroid hit the earth, and created a heavy mascon of U235 which sank into the crust until it encountered another waiting mass of U235 in the mantle, and the combined mass of fissile materials exceeded the critical mass...coincidentally enveloped in masses of neutron reflective minerals rich in Be, C and saturated with deuterium rich water ....and the high pressures deep in the mantle held the blast long enough to yield multiple iterations of nuclear amplification...BOOM!

yea too complex... :lol:
On the other hand, you have a definite future, writing Sci-Fi for Hollywood. :)
 
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