Question Earth Moon Origin

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Mar 5, 2021
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Hello one and all
just dropped in for a sec

I wish I had a time machine.
I have been run off my feet.

OK maybe the blast from the past may have created the moon.

We should have more info in the near future.
I wonder why very few people actually believe in Darwin's idea of the Moon's creation? to me it is the most realistic!
 
Darwin proposed the fission theory, where the molten Earth spun up and discharged enough material to coalesce in orbit and form the Moon. It has two problems, 1) it does not specify where the spin up energy came from. 2) Spun off material will either fall back onto the Earth or go into orbit around the Sun but cannot go into orbit around Earth. Expelled material has no way of obtaining the sideways velocity component needed to go into Earth orbit.
 
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Darwin proposed the fission theory, where the molten Earth spun up and discharged enough material to coalesce in orbit and form the Moon. It has two problems, 1) it does not specify where the spin up energy came from. 2) Spun off material will either fall back onto the Earth or go into orbit around the Sun but cannot go into orbit around Earth. Expelled material has no way of obtaining the sideways velocity component needed to go into Earth orbit.
Like all the other moons, probably, a capture rather than a material spinoff or knockoff.
 
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Mar 5, 2021
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Darwin proposed the fission theory, where the molten Earth spun up and discharged enough material to coalesce in orbit and form the Moon. It has two problems, 1) it does not specify where the spin up energy came from. 2) Spun off material will either fall back onto the Earth or go into orbit around the Sun but cannot go into orbit around Earth. Expelled material has no way of obtaining the sideways velocity component needed to go into Earth orbit.
Ok, you are the first person I've talked to about this. But I really believe this theory and I won't go easily, I hope you have some physics background. What I've read about the early Earth says that it was spinning at 6 times the speed it is now or more when the Moon appeared. Would that be enough spin energy? Also if the Moon was to slowly emerge out of the Earth like a drop of water that slowly accumulates on the end of a dropper, that might be enough to keep it in orbit. The moon is moving away from us at 1 and a half inches a year and that is pretty slow compared to having a Moon emerge out of a planet. But if it emerge quicker and clung on at the end, both entities being completely molten, then in that situation it might just go into orbit. Correct?
 
I studied Celestial Mechanics at the college level 53 years ago.

The escape velocity from the surface of the Earth is 11,000 m/s. A object at Earth's equator is traveling at 460 m/s. The Earth would have to be spinning 24 times faster in order to throw objects off. This is unlikely to have ever happened.

Additionally, anything thrown off the Earth returns to it. You cannot put something into orbit around an object, from the surface of that object with only one impulse of energy. What goes up must come down.

Only by putting something up there, and then giving it a sideways impulse can you put something into orbit.
 
I studied Celestial Mechanics at the college level 53 years ago.

The escape velocity from the surface of the Earth is 11,000 m/s. A object at Earth's equator is traveling at 460 m/s. The Earth would have to be spinning 24 times faster in order to throw objects off. This is unlikely to have ever happened.

Additionally, anything thrown off the Earth returns to it. You cannot put something into orbit around an object, from the surface of that object with only one impulse of energy. What goes up must come down.

Only by putting something up there, and then giving it a sideways impulse can you put something into orbit.
A constant of velocity is always some form of constant acceleration (constant of deceleration) to play keep away from the speed of light. A splitting of dimensionality because it doesn't and can't possibly work ((t=+1), (t=-1), (c = (t=0))). What comes down must go up (per observed "accelerating expansion"). o_O :);) :eek::rolleyes::cool:
 
Mar 5, 2021
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I studied Celestial Mechanics at the college level 53 years ago.

The escape velocity from the surface of the Earth is 11,000 m/s. A object at Earth's equator is traveling at 460 m/s. The Earth would have to be spinning 24 times faster in order to throw objects off. This is unlikely to have ever happened.

Additionally, anything thrown off the Earth returns to it. You cannot put something into orbit around an object, from the surface of that object with only one impulse of energy. What goes up must come down.

Only by putting something up there, and then giving it a sideways impulse can you put something into orbit.
Ok, but in my & Darwin's theory, when the Earth was 4-4.5 billion year ago, it was spinning 6-8 times faster. Making it only necessary to spin at 4-3x faster for the Moon to reach orbit. The moon made of mostly sand and radioisotopes and the gravity on both probably reduced do to its and Earths molten state with no real atmosphere or Van Allen belt to hold things down, the idea then gets closer to the ballpark figure, having it to only 2-1.5x faster (gravity alone) and if ALL the above afor mentioned aspects are taken into account, maybe even half that at 1-.75 times faster. Also even with the moon only partially ejecting, when it started to bulge out, the added mass all on one edge could make up for this reduced figure. Then simply the high rotation and the moon rising off at a low angle from the Earth surface could be enough to giving it a sideways impulse to reach orbit insertion. (1) You are a physicist and I am not, although I understand things about rotation and centrifugal force, like when there is reduced gravity, atmosphere and both bodies are in a molten state with different composition. If you know how to calculate for these different aspects, please do and tell me what you figure out. But as you see from what I've discussed, 'Heaven isn't too far away'!
(1)-The moon lags behind the Earth's rotation. Is there a calculation that describes how fast it ejected to reach this reduced orbit speed? There are many ideas to take into account the Earth's rotation speed and that then the Moon maybe was rotating too, which could've given it extra lift.
Have a good one and keep in touch, - k.
 
Your first error is in sentence two. "spin at 4-3x faster for the Moon to reach orbit." Physics does not allow this. You cannot toss something off a body and put it into orbit. You can put it up there, but it simply falls back.
I explained this in post #80. You are not paying attention. I'm moving on.
 
Problem is, that if the Earth were to spin fast enough to throw off a moon-size blob because that area reached escape velocity, as the blob ascends, the escape velocity decreases with altitude, the blob continues to ascend to never return. There is nothing to slow it down to orbital speed from escape speed.
 
[Submitted on 7 Mar 2024]

Parallel numerical simulation of impact crater with perfect matched layers​

Huacheng Li, Zongyu Yue, Nan Zhang, Jinhai Zhang, Zhongzheng Miao
Impact craters are the primary geomorphic features on the surfaces of celestial bodies such as the Moon, and their formation has significant implications for the evolutionary history of the celestial body. The study of the impact crater formation process relies mainly on numerical simulation methods, with two-dimensional simulations capable of reproducing general patterns of impact processes while conserving computational resources. However, to mitigate the artificial reflections of shock waves at numerical boundaries, a common approach involves expanding the computational domain, greatly reducing the efficiency of numerical simulations. In this study, we developed a novel two-dimensional code SALEc-2D that employs the perfect matched layer (PML) method to suppress artificial reflections at numerical boundaries. This method enhances computational efficiency while ensuring reliable results. Additionally, we implemented MPI parallel algorithms in the new code to further improve computational efficiency. Simulations that would take over ten hours using the conventional iSALE-2D code can now be completed in less than half an hour using our code, SALEc-2D, on a standard computer. We anticipate that our code will find widespread application in numerical simulations of impact craters in the future.

And this one, for your appraisal.

[Submitted on 13 Mar 2024]

Crash Chronicles: relative contribution from comets and carbonaceous asteroids to Earth's volatile budget in the context of an Early Instability​

Sarah Joiret, Sean N. Raymond, Guillaume Avice, Matthew S. Clement
Recent models of solar system formation suggest that a dynamical instability among the giant planets happened within the first 100 Myr after disk dispersal, perhaps before the Moon-forming impact. As a direct consequence, a bombardment of volatile-rich impactors may have taken place on Earth before internal and atmospheric reservoirs were decoupled. However, such a timing has been interpreted to potentially be at odds with the disparate inventories of Xe isotopes in Earth's mantle compared to its atmosphere. This study aims to assess the dynamical effects of an Early Instability on the delivery of carbonaceous asteroids and comets to Earth, and address the implications for the Earth's volatile budget. We perform 20 high-resolution dynamical simulations of solar system formation from the time of gas disk dispersal, each starting with 1600 carbonaceous asteroids and 10000 comets, taking into account the dynamical perturbations from an early giant planet instability. Before the Moon-forming impact, the cumulative collision rate of comets with Earth is about 4 orders of magnitude lower than that of carbonaceous asteroids. After the Moon-forming impact, this ratio either decreases or increases, often by orders of magnitude, depending on the dynamics of individual simulations. An increase in the relative contribution of comets happens in 30\% of our simulations. In these cases, the delivery of noble gases from each source is comparable, given that the abundance of 132Xe is 3 orders of magnitude greater in comets than in carbonaceous chondrites. The increase in cometary flux relative to carbonaceous asteroids at late times may thus offer an explanation for the Xe signature dichotomy between the Earth's mantle and atmosphere.