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zankaon
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For cataclysmic collision of proto-earth and planetesimal, how long would it take for the liquid cores to combine after collision of 2 bodies' surfaces; how fast would proto-earth's surface radially expand?
...In view of these considerations, one must conclude either that significant aspects of current models are in need of revision, or attribute important aspects of the Earth-Moon system to a rather large coincidence.
Andre said:There are some concerns about that hypothesis.
sylas said:Andre said:There are some concerns about that hypothesis.
...In view of these considerations, one must conclude either that significant aspects of current models are in need of revision, or attribute important aspects of the Earth-Moon system to a rather large coincidence.
You need to read that paper again. You appear to have completely misunderstood what it is about.
4. something that relates or pertains to a person; business; affair: Law is the concern of lawyers.
5. a matter that engages a person's attention, interest, or care, or that affects a person's welfare or happiness: The party was no concern of his.
6. worry, solicitude, or anxiety: to show concern for someone in trouble.
7. important relation or bearing: This news is of concern to all of us.
8. a commercial or manufacturing company or establishment: the headquarters of an insurance concern.
9. Informal. any material object or contrivance.
One might want to be careful with fallacies like strawman tactics. Once exposed, those tend to turn against the originator in an intelligent society like this.[strike]10. a rebuttal or refusal claim of a hypothesis[/strike]
Andre said:Once exposed, those tend to turn against the originator in an intelligent society like this.
Well that was cheery.sylas said:Cheers -- sylas
You want to know what I thought when I was reading this explanation of how the Moon came to be?: Did you just pull that out of your ***? The certainty of knowledge expressed is so fantastical. It took an hour to become molten, and then it was molten for millions of years? You don't say!Xnn said:The proto-earth and moon... [became] molten within an hour. The metallic cores combined quickly, but it probably took several weeks for most ejected material to condense into the moon or collide with earth... the Earth's surface was completely molten for... millions of years... and the atmosphere was lost.
Is There Any Evidence that the Earth Ever Had a Magma Ocean?
No. Another anticipated result of the Giant Impact is a terrestrial magma ocean [3]. This melting event was likely not an opportunity to homogenize but, rather, an opportunity to differenti- ate. And because there are mantle spinel lherzolites whose compositions closely approximate that of the bulk silicate Earth, this seems to imply that there was never a global magma ocean [7].
Mk said:As an outsider, I see two things in this paper and have a few questions:
Introduction:
one must conclude either that significant aspects of current models are in need of revision, or attribute important aspects of the Earth-Moon system to a rather large coincidence.
Conclusion:
Ringwood’s [11] assertion that the Moon formed from the Earth’s mantle, remains a difficult hypothesis to reject out of hand.
...What? First you say the models are horrible, then you say the hypothesis is "difficult to reject?" This just doesn't make sense.
Xnn said:More about the impactor: I don't understand why that paper has a problem with it forming at 1 AU from the sun. I would think it formed in about the same orbit as Earth at a Lagrange point. Eventually, as it grew larger and larger (from accretion), its orbit would have become unstable and it would have been gravitationally attracted to earth.
If it is presumed that there's no good reason for the impactor and proto-Earth to have similar isotopic composition, then isotopic similarities might be explained by having the Moon formed mainly from material thrown up from proto-Earth. This, however, runs into problems with current "SPH" models (smooth particle hydrodynamics) which would have the Moon formed 80% from the material of the impactor.
Xnn said:I appreciate your comments, but I still don't see what's wrong with the impactor initially accreting at a Lagrange point. That is, having it formed from basically the same material as earth. In addition, as the Earth is accreting at this time, there were many smaller collisions that also threw material into space. Some of this material then falls to the impactor. Likewise, as the impactor is also accreting from collisions, it is throwing material into space that lands on earth. Since both the Earth and impactor are sweeping areas near 1 AU, as long as most impacts are small, they will assume nearly identical materials on their surfaces.
Count Iblis said:
zankaon said:For cataclysmic collision of proto-earth and planetesimal, how long would it take for the liquid cores to combine after collision of 2 bodies' surfaces; how fast would proto-earth's surface radially expand?
Their idea is that centrifugal forces would have concentrated heavier elements such as uranium and thorium near the Earth's surface on the equatorial plane. High concentrations of these radioactive elements can lead to nuclear chain reactions which can become supercritical if the concentrations are high enough.
We propose an alternative explanation for the compositional correspondence, namely that the Moon was formed from the ejection of terrestrial mantle material in a heat-propelled jet, triggered by a run-away natural georeactor at Earth core-mantle boundary. The energy produced by the run-away reactor supplies the missing energy term in the fission hypothesis for lunar formation first proposed by Darwin (1879). Our hypothesis straightforwardly explains the identical isotopic composition of Earth and Moon for both lighter (oxygen, silicon, potassium) and heavier (chromium, neodymium and tungsten) elements.
A cataclysmic collision of proto-earth and planetesimal refers to the hypothetical event in which a large, planet-sized object collided with the proto-earth during the early stages of the solar system's formation. This collision is thought to have played a crucial role in shaping the formation and evolution of our planet.
The exact mechanism of this collision is still unknown, but it is believed that it occurred due to the chaotic movements and gravitational interactions of objects in the early solar system. As proto-planets and planetesimals grew in size, they were more likely to collide with each other.
The size of the planetesimal that collided with proto-earth is estimated to be about the size of Mars, which is roughly half the size of Earth. This collision is thought to have occurred around 4.5 billion years ago.
This collision had a profound impact on the formation and evolution of our planet. It is believed that the collision caused the proto-earth to melt and form a hot, molten planet. The debris from the collision eventually formed the moon, and the energy released from the impact may have contributed to the differentiation of the earth's layers.
While there is no direct evidence of this specific collision, there is evidence to suggest that such collisions were common during the early stages of the solar system's formation. For example, the moon's composition is very similar to that of the earth's mantle, which supports the idea that the moon was formed from debris from a collision with the proto-earth.