The Moon: What is it's purpose?

*Note

I've noticed that many of the simulations do not include the core rotation as part of the motion dynamics. If I'm right it might suggest that large collisions in planets are not conducive to the super-rotating-core. (Mars size) With Venus and Mars as Prime examples of collisions visible trauma and effects it might disprove the GIH for the moon. Both planets are cold, have little magnetic shielding and no plate tectonics.

 

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If the Moon wasn't in orbit around us, the Earth would tip over in its orbit--or at least would be a lot more drastic in its orbital inclination.

 

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Ref the footnote of post 160: in case of Ni the isotopes and natural abundances (as best as I can read my old chart*) are:

67.76% is 58
26.16% is 60
01.25% is 61
03.66% is 62
01.16% is 64

It would seem possible that Ni58 which is >2/3 of all Nickel could absorb a neutron to become Ni59 which seems not to normally exist. I.e. if Ni59 is found in the nickel of the metallic meteorites then that would be strong support for the idea that the asteroids do come from an nuclear fission exploded planet.

Anyone have access to Mass spectragraph and tiny piece of metallic asteroid?
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*From Fermi's 1949 lectures on Nuclear Physics

 

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There are several problems with this concept.

First and foremost, the statement "their rotation grinds to a halt when the collide" is wrong, whether spelled correctly or not. Angular momentum is a conserved quantity. Assuming such a perfect collision is possible, this scenario does not conserve angular momentum. The combined bodies would remain (must remain) spinning counterclockwise after colliding and merging. (The rotation rate would be reduced because the moment of inertia of a solid sphere with uniform density is 2/5MR[sup]2[/sup].)

Lesser problems: Such a perfect collision (no change in orbital state) has zero chance of occurring because the probability space of such perfect collisions is a set of measure zero. A pair of planets forming exactly opposite each other similarly has zero chance of occurring. Since the L3 Lagrange point is a metastable position, a pair of planets could not form even close to opposite one another.

In short, your proposed formation cannot happen, and if it did, it would not result in a zero rotation rate.

 

Yes there is a positive feed back but a gas giant does have a negative feedback problem too in collecting a lot of gas - it heats and expands as it does so.

For example the biggest gas giant in the solar system, the sun, left matter behind it could not collect. I think that if Jupiter were only 10% of its actual mass it could have collected that mass faster despite the gravitation positive feedback you mention because the negative feedback I mention would have been much smaller with greater surface garvity (AS NOT THERMALLY EXPANDED), but not as much as if it were a rocky planet of the same size OR SAME MASS. Also, everything else being the same, it should ALWAYS take less time to collect less mass as the bigger mass planet had to do that and then collect some more. Thus, one can argue that a smaller planet made of denser matter should certainly form faster to any given mass than one collecting gas molecules with a larger radius (lower surface gravity) for any given mass.

Remember most of that gas Jupiter had to collect was far away (even on the other side of the sun!). Jupiter is still, millions of year later, with excessive heat - radiates more energy than it receives from the sun. I do not deny that Jupiter's pull on passing gas molecules was stronger than a lesser mass would have, but you should not ignore the "thermal repulsion" negative feedback either. Eventually when Jupiter does cool down to thermal equilibrium with the solar energy flux it will be smaller.

I focus more on how rapidly Jupiter's density center got to the mass of a bowling ball verse a planet being made of high atomic number elements, especially metal atoms that do stick together and form very much denser bowling ball mass easily.

I.e. when Jupiter’s eventual mass center had bowling ball mass it may have been hundreds of meters in diameter as it was a gas still. Then the gravitational field pulling more gas to the surface of the 100s of meters sphere was much LESS intense that the gravitational field collecting more matter for the surface of the small metallic bowling ball.

I am not trying to be precise - only to make you see that when the condensation has just started, build a mass center of metals and other high atomic number elements is much easier and quicker than from Jupiter's mainly hydrogen and helium gases.

You must focus on how the "densification" starts as that is what takes most of the time, not just say "look how much more massive Jupiter is (now) than the "pre-asteroid" planet was." I hope this at least suggests that which became a planet first is very complex and not obvious from fact Jupiter is NOW a much larger mass.

How long it took to form is more a question of INITIAL growth rates for assemble of a gaseous vs. a rocky planet than what their ultimate gravitational fields are. Perhaps Mars was well formed before Jupiter was. Do you have any reason to think that false? Are you even sure that the sun was radiating when Mars formed? If not, then your next two "it was hotter at Mars than at Jupiter" arguments also go out the window.

True If the sun had started fusion and is radiating; probably false if not. Be careful not to fall into circular reasoning. - The question is: In what order did things occur - do not assume either that the sun was radiating or the Jupiter formed prior to the rocky planets to prove that that was the case.

Same answer again. (Do not make circular argument to "prove" your POV.) We are discussing which and what happened first so you cannot assume the sun was radiating before the "pre-asteroid" planet formed and then argue that the sun's radiation made formation of the "pre-asteroid" planet occur after Jupiter did because space at Jupiter's orbit is NOW colder than at the "pre-asteroid" planet's orbit.

If you want to make these last two "solar radiation makes T drop with separation from the sun" arguments then show independently of that now true condition why the sun went thermonuclear before the rocky planets formed. They may have, but your circular argument does not show that.

 

Must gpo to bed nowbut just a quick reply to part:

Yes the center region of a cloud which will form suns and planets is hoter than near the deges, but It is my understanding the "local group" of stars all fomred form from the same gas cloud. Perhaps the hot center was between these stars and too hot for condensation. That is the cloud was not without more local density consentrations. (Our solar system being one). Perhaps that more central density was high but so much hotter that the density was lower than some of the local regions and no solar system formed in the hotter region (for reasons I have suggested are at least possible) For example, the much more massive sun has lower density than the Earth. Total mass alone does not determine which center of mass is denser.

I will re-read (instead of just skim) you post tomorrow. hope this one not too inconherent - I am tired now.

 

I appreciate you dedication to all things littteral even in the figurative but can you illistrate more plainly why the collision of considerable speed and set directly opposing against another mass would only slow and not reverse?

For the sake of being litteral, 'Such a perfect collision (no change in orbital state' is not my assertion. Nor was 'zero' rotation. I presented little change as a result. But if this is such a problem even to say lesser then how much so an arbitrary strike in the opposing direction of a Mars sized Mass with is the prevailing theory to still come out to a eccentricity that is still circular to the nearest hundredths?

I have yet to learn ove the Lagrange Points in detail I'll review them. I have only a passing knowledge. I also do not understand the term metastability. I'll review this aswell.

Appreciate the input.

 

Angular momentum is a conserved quantity. The post-collision and pre-collision angular momentum must be equal to one another. If, as you suggested, the planets come together with near-zero velocity, the only angular momenta of interest are the angular momenta due to rotation.

Suppose the two planets are the same size, same mass, same uniform density, have parallel rotation axes, and are rotating in the same direction. The moment of inertia of a solid, constant-density sphere is \(I=\frac 2 5 M R^2\). The angular moment of each planet is \(L=I\omega\) and thus the total pre- and post-collision angular momentum is \(L_{tot}=2 I \omega\). The combined planet with have a mass of 2M, a radius of \(^3\sqrt 2 R\), and a combined moment of inertia [itex]I_{merged}=2^{5/3} I_{individual}[/tex]. The resulting rotation rate will be \(\omega_{merged} = I^{-1}_{merged} L_{tot} = 2^{-2/3} \omega\), or about 63% of the pre-collision rotation rate.

A planet forming at the L4 or L5 point does the trick nicely.

Grab a run-of-the-mill kitchen broom. Hold the broom from the top of the shaft and let the business end of the broom hang free. This is a stable position. If you give the business end nudge the broom will simply swing back and forth, like a pendulum. Now balance the broom upside-down with the end of the shaft nesting in your palm. The broom will fall if there is the slightest deviation from this purely vertical orientation. The broom will not fall if it has a perfectly vertical orientation. This perfectly vertical orientation is an example of a metastable position. Another example: A ball at the bottom of a valley is in a stable position. A ball precariously placed at the top of a hill is a metastable position.

 

Thank you DH, save that and break it down.
(heading back to the drawing board)

 

Yes, we generally agree on this, but seem to have very different ideas as to the size of the cloud from which our solar system formed.

I think that it was very large compared to the solar system’s 100 or so AU scale. Probably the scale of the cloud was initially much larger than the “local group” of stars that formed from it. Yes, it had an ill-defined center of mass (There were no well “defined edges” to the cloud.) but that may not have been the hottest and densest point long before any stars started to form. I expect that there were several parts, separated by dozens or more of light years, one from another, that were both hotter (if you can call 30 to 50K “hotter” than 20 to 40K) and denser than where the CoM happened to be. Most likely the local group stars did assemble because of these local mass centers. (If we ignore random density variations in dark matter, which was probably much more important.)

If this view is correct, the temperature difference between points separated even 10 times larger than the solar system’s 100 AU was probably less than a milla-degree C. For this reason I did not think the temperature gradient across solar system scales were important. Thus, when you spoke of them as controlling condensation I naturally did assume that you were assuming a later time than I was and postulating that the sun was shining before the postulated pre-asteroid planet was even a “bowling ball” mass.

Now in this enormous, by solar system scale, gas cloud, there were some atoms of elements heavier than Hydrogen and Helium – even some heavier than iron. Occasionally two of them that could form a “two atom alloy” collided and did so. I.e. “cosmic dust” was being born long before anything else as occasionally these alloy pairs also collided, etc.

Admittedly the gravitational attraction between a “3 atom cluster” of heavy atoms and a five atom cluster of them is not very great, but there is a lot of time for the slight attraction to work and very little thermal energy to make them stay apart as “Brownian motion” effect tries to separate them. I.e. the hydrogen atoms, H, or molecules of H2 colliding with the three atom cluster of say (Fe, Pb & U) just bounce off and do not break that tiny alloy apart into separate atoms. So, as you said, there is a positive feedback process working here and in dozens of millions of years there will be some visible specks of metallic alloy (mainly) dust. I think that much later when the sun did turn on and radiate its radiation pressure reflecting on the larger than photon wavelength conductive specks to push them away from orbits near the sun to become the reflectors of the “zodiac lights.” I.e. complex alloys with binding energy greater than the very low thermal collision energy of the enormous (many light years big still but slowly shrinking generally towards it CoM) had formed and were growing throughout the cloud. (They probably had only 1 or 2% of the clouds mass as ~99% was still just H, H2 & He gas and it was still no where hotter than 100K.)

Now the CoM was far away and some more local mass center’s gravity dominated the local (10,000 AU scales, a least) region and these “local” mass concentrations started to “fall together” faster than they were falling towards the CoM, partially because they were already “orbiting” the CoM. Each of the local group of stars is the result of this “local” condensation. Perhaps (even probably) there is essentially nothing at the local group’s CoM now (unless it is some sort of stable Lagrangian point in a multi-body system.)

As the “10,000 AU local region” contracted to 1000 AU the density went up 1000 fold and the metallic dust speck collided and stuck together more frequently but the H, H2 & He were still just gases (except for some 2D quasi liquids on some dust speck surfaces, if the surrounding gas temperature was not yet high enough to “boil them off.” ) I.e. Before there were any gravitationally assembled clusters of H2 & He alone, there were growing specks of metallic dust (metallic in the sense of electrically conducting aggregates of many different types of atoms, including some radioactive ones), on which the H2 molecules could surface adsorb. Eventually when the local region was solar system size, there probably were a few “bowling ball” mass metallic aggregates and many golf ball size ones, all now having lost their 2D quasi liquid film layers due to the rising temperatures.

Summary of my expectations (guesses):
I do not know detail of why, but the approximately quadratic separation of the planet orbits (with one forming at the asteroid belt orbit) is probably some dynamic resonance interaction that tends to group these bowling ball masses into orbits roughly as the planets do now have. This dynamic interaction also tends to scatter the “orbit crossers” into circular orbit also.) If this interaction (and resonance) were the cause of current planetary orbits locations, then one at the orbit of the asteroids is necessary – and it was looked for when this roughly quadratic spacing pattern was first noticed). I expect the metallic alloy masses mutually collided and continued to grow and radiate black body radiation away so that the cloud could heat more slowly as it continued to shrink. I expect that even the gas giants like Jupiter, have large metallic cores that help them form as planets. I see no reason why the rocky / metallic planets, including the postulated pre-asteroid one, could not have formed BEFORE Jupiter was able to add much gas mass to its rocky metallic core.

I.e. I do not buy the argument that there was no pre- asteroid planet because the perturbation of Jupiter would prevent it from forming. This is the only point I am trying to defend. I did not intend to get into deep discussion with you about thermal distributions in collapsing cosmic clouds and think we basically agree, except possible about the scale of the cloud.

Warning to those who may read my model above of how gas cloud formed solar systems: I am only speculating based on the physics I know and may have the story entirely wrong. I am too lazy to search but sure a more accurate story with numerical calculations and simulations exist. It is just such analysis that tries to tell me that there was never a pre-asteroid planet because Jupiter would not let it form. I.e. I do not believe simulations that have a serious, unstated assumption. (In this case, that Jupiter formed to current mass before “pre-asteroid” planet could form.) As they say: “There is no fool, like an old fool.” (Too stubborn to easily change his POV.)

 

To sing about! Listen if you don't believe me....

http://www.youtube.com/watch?v=aS6-b7CONDI

 

No confusion.

I just did not use those names in my post, but I clearly distinguished them and even explained how they differ and why the smaller developed from the larger.("CoM was far away...."). Here that part is again with your names* now inserted in red:

As far as how the temperatures within the Solar Nebula were distributed I doubt your version again for reasons I already noted. (My last sentence quoted above, which I will now expand some so the point is more clearly stated.):

The black body radiation surface of the metallic dust was enormous and the photon mean free path within the solar nebula is very large -at least a significant part of one AU, I would guess and much more than that for parts of Black Body spectrum H2 etc can not absorb. H and He would absorb nothing at the temperatures we are considering as there are no photons with 3/4 of 13.6ev and certainly none which can excite He to its first excited state. (H does have the 21 cm line due to spin flip nuclear spin interaction but that is tiny part of the spectrum.) Thus, I am almost certain that radiative transport of energy is orders of magnitude greater than conduction (collisional transfer) in the thin gas of the Nebula.

If this is true (as I believe it must be) and the sun is not yet with fusion heat source to radiate (just its gravitational collapse heating) then its surface temperature is not much different from Jupiter's now. I.e. with the metallic dust surface making black body radiation and the radiative transfer dominate there would not be the large thermal gradients you and your references suggest. I only mentioned this in prior post in one sentence:

"I expect the metallic alloy masses mutually collided and continued to grow and radiate black body radiation away so that the cloud could heat more slowly as it continued to shrink."

Perhaps I should have explicitly noted that Black Body radiation from the enormous surface area of the metallic dust combined with the low gas density (large mean free photon paths) controlled the thermal distribution to make it quite uniform within the Solar Nebula PRIOR TO solar fusion starting. If your references have ignored this huge radiative transport, it is little wonder that they did not come to this conclusion.

It is interesting to know, if you do not already know, that inside a piece of molten glass even though it is dense and conduction is important radiative transport is larger as the glass is transparent in enough parts of the spectrum to make this the case. In the thin gas of the nebula radiation dominates conduction even at temperatures well below room temperature (i.e. despite the T^4 law.) I believe that radiation dominates conduction as the main heat transfer mechanism even inside the sun today until the convection zone is reached.
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*I know they are standard names, not “your names,” but when I can I avoid giving names as many readers here may not be sure what they refer to. I usually prefer to explain what I am speaking of rather than just name it.

 

I'm at a loss. I know of no other method of producing flood basalts than volcanism. Can you suggest such an alternative.

1. I have absolutely no idea what role you think a molten core would play in volcanism. It is irrelevant.
2. I am not talking about current volcanism, and your posts did not in any way indicate you were talking about current volcanism, therefore the thermal conditions of the interior have bugger all to do with volcanism 3.5 by ago.

Well setting aside the bloody samples brought back by the US astronauts I suppose there isn't a bloody lot.

Excuse my shortness BillyT,, but really. The nature of the Mare basalts is as well established as the existence of Mount Everest. I thought you were contending that 17% coverage by volcanic rocks is not all that great when on the Earth its more like 75%. Since that wasn;t what you wer saying I shall just say, 'You are wrong.'

 

You know considerably more geology than I do, so probably are correct in your post. I am thinking the moon's mares were made by impacts of "Lesser Moons" on the "Larger Moon" shortly (10,000 years or less I would guess.) after some body much more violently collided with the Earth to make all these bodies (Probably a few dozen or more briefly existing "little moons" of the Earth.) They would all have roughly the chemical mix of the Earth's crust and some of the upper mantle if impactor went deep* (and possibly some of the non-volatile material of the colliding body). I.e. I imagine that they would soon (a few years at most) be quite spherical with a radiatively cooled solid skin and mainly (98%?) a still molten internal mass when they collide with the growing "Larger Moon." (Possibly from below on average to help keep it outside of the then current Roche limit as it grows.)

More than one moon of Earth in near Earth orbit is unstable and the lesser ones are throw into collision - most probably back into the Earth but when some hit the "greater Moon" these molten core "Eggs" both crack open can add relative kinetic energy of the inelastic collision to the growing "greater moon." I.e. I imagine than a sea "molten basaltic" material is added to the greater moon in less than five minutes and gravity works on it to make it a quite spherical surface sector of the Lunar mare.

My comments about no molten core of the Moon reflect my ignorance, in part, as I did think volcanism required that. It is still hard for me to understand how crustal rocks become molten without losing their heat to the not molten core and why radiocative decay per cubic meter is not greater in the core than in the crust, if that rather than plate tectonic friction is the heat source. (Also hard to understand how one can even have plate tectonic friction without a molten core.) Can you clarify how non-molten core volcanism works? Surely the core is hottest with a thermal gradient dropping towards the surface. I am going to need a lot of help to think otherwise.

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If the 17% were to have come from the interior of the current moon, I think it would take much longer (more than a year, not five minutes) and parts would be solid with other parts flowing over them - I.e. very clear evidence of volcanic cone and flow fields, which AFAIK, do not exists. I admit that in millions of years that these surface irregularities associated with typical volcanic flows would be reduced some towards a more spherical surface by the moon's gravity and "plastic flow" of the rocks but moon's gravity is very weak compared to the Earth's gravity which even with the aid of weather has not removed some old volcanic cones and obvious flows.

If there is some reason why this is impossible or even implausible, I will yield, but it seems to me, in my state of relative ignorance about geology etc, that the burden of proof is with your POV. I.e. why is there no evidence of significantly irregular surface in the moon's mares, (except meteor craters) from the years-long, multi-layer overflows of volcanic eruptions, given the moon's weak gravity and zero water errosion weather?
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*It probably did if not a "glancing strike" collison.

 

BillyT,
to fully answer your points will require a little time. Let me just say that since what I am stating is wholly accepted by the scientific community (where do you think I got it) it is not on me to offer proof. The proof is available in any elementary textbook on geology that has anything to say about the moon. A brief google will provide you with far more information than I can provide.
Nevertheless I shall address each of your points in turn, when I have time.
O.

 

I look forward to your comments. I was mainly supplying the "alternative" you asked for, not really challenging the accepted POV. I do that in cognitive science concerning how perception arises. I think they do not know or have any model so just say it "emerges." I have definite model, tell where it is implemented, why evolution would have selected for it (And against the accepted POV with its time delays for synaptic transfers). My model explains at least a dozen serious problems of the accepted model but I am a crackpot (and proud of it in this field)

By giving an alternative explanation of how the moon's mares could have formed to you, I am not trying to become one in physics also as I have no evidence supporting it, only what on the surface at least seems to be a plausible story. I have lots of evidence supporting my crackpot POV about perception and all of its predictions are consistent with the known facts.* -Something the currently accepted POV cannot claim.


For details, and evidence supporting this non-standard POV about perception, see: http://www.sciforums.com/showpost.php?p=1294496&postcount=52
It is a long read, about 8 pages if printed, but that post was concerned with “free will” and those parts can be quickly skimmed. (Only the parts about the Real Time Simulation direct relate to perception.) In spite of my augments that free will can be consistent with physics, I am inclined to think it is an illusion. I.e. we are just very complex biological machines.

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*For example, my model not only predicts but would function poorly if there were not a large number of retrograde axons sending information back from the parietal region to the early stages of the “visual cortex.” The fact that there are slightly MORE of these retrograde fibers than even those coming from the eyes, via the LGN, is not only not explained or predicted by the conventional POV, but a great mystery for it as to why they should even exist.

My model also predicts that the EEG signal known as P300 (or sometimes called the “startle response”) should exist and that it should be strongest in EEG electrode signals over the parietal regions (it is.) etc. for many other known facts totally unexplained by the accepted “emergent” POV of perception, including at least a dozen that are not neurological in nature, but behavioral. It even gives a new reason for two ancient historical events (“Out of Africa” and our ancestors ability to kill off the stronger, bigger-brained Neanderthals, which are also without adequate explanations.)

SUMMARY: A CRACKPOT can be useful, and sometimes even right!