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Thread: SPLIT : Glenn Jacobs' Personal Theory

  1. #101  
    Brassica oleracea Strange's Avatar
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    Quote Originally Posted by Glenn Jacobs View Post
    My mind bogs down at radiation that was produced at the first bust-up somehow coming back to us rather than continuing on and on into the infinitude of space.
    The "surface of last screaming" analogy might help you get your head round this (it worked for me): Inflation and the CMB - C.H. Lineweaver
    ei incumbit probatio qui dicit, non qui negat
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  2. #102  
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    I'm not really the best person to answer these kinds of questions, but I'll give it a shot.

    The CMB is not from stars. Its from the moment when the glowing hot universe cooled just enough to become transparent. Just before that everything was too full of light and energy to see through. (This is what people mean by echoes of the big bang. Not literal echoes.)

    And yes, while the specific sphere of 13.8 billion year old light we see when we look up didn't come from 13.8 billion light years away originally, that, in it self, is not terribly important as the light was coming from everywhere. What's important about that is that the light originally emitted wasn't microwave light. It was something more like star light (not actually star light though) but space between here and there has stretched quite a bit since then. When you stretch space, light doesn't slow down, but it does lose energy, which makes it's wavelength longer.

    If you crunch the numbers by taking what the light should have been like and stretching it by the amount it should have stretched by, you get that the background radiation should be a certain microwave wavelength. And when you look, it is.

    As for the stars, there was a period between the release of the CMB and the formation of the first stars. There is no light from that time. But we can see light from when the first stars start firing up. The CMB is from everywhere though, not just from those points of light. (We can also compare the spectra of the two types of light.)

    The sun is only about 4.5 billion years old, so it's light hasn't reached all that far away, relatively speaking. As far as we know, we can't see any echoes of the sun's light anywhere. Even if the universe wraps around, it's big enough that the light from the sun hasn't had time to go all the way around. (Gravity does bend light though, so maybe, just maybe a tiny bit got bent all the way around, but it'd probably be too little to make out.)

    Edit: Ninja'd
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  3. #103  
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    Quote Originally Posted by John Galt View Post
    Quote Originally Posted by hkyriazi View Post
    I thought it was clear that I was talking about our thoughts about the universe - the model of it we choose to adopt - not the universe itself.
    So, you appear to be saying that we should choose a model that we prefer, rather than one that best fits the facts. In what way is that not either remarkably foolish, or mind numbingly arrogant?
    Apparently I didn't make it clear that I was trying to present two options in terms of theoretical frameworks, both of which fit the facts, but only one of which is explanatory in the mechanical, pictorial sense described in the quote by Leonard Loeb (see post #74 in the "Gyron Aether Theory (GAT)" thread), while the other is purely descriptive. (Not that I think two such perfectly-fact-fitting structures can exist.)
    Last edited by hkyriazi; January 9th, 2014 at 08:06 PM.
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    Ah! Yes. Now I remember. A Black Body not only absorbs energy evenly but radiates it evenly as well.

    Our physics professor had a stack of razor blades that he said resembled a black body in that it absorbed everything thrown at it, and radiated evenly all over the spectrum.

    Starlight has those bright lines from which we can tell the speed of departure by the red shift (and the speed of approach by blue shift?)

    TECHNICAL QUESTION: With a billion blazing galaxies at different speeds of departure sending red-shifted bright lines our way -- and each star in each galaxy having a different red shift, and opposite sides of each star having different red shifts. does this blur into a homogeneous background radiation?
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  5. #105  
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    Quote Originally Posted by Glenn Jacobs View Post
    With a billion blazing galaxies at different speeds of departure sending red-shifted bright lines our way -- and each star in each galaxy having a different red shift, and opposite sides of each star having different red shifts. does this blur into a homogeneous background radiation?
    Apparently not. Not my area of expertise but one thing to consider is Olbers' paradox But also, to get a uniform distribution, there would need to be far more gas and dust than we see.

    Don't forget, the facts supporting the big bang model have been known for a very long time. Over the decades, people have tried to make all sorts of different explanations fit the data. So far, there is only one that appears to explain all the evidence in a consistent way.

    (I get the impression that some people think scientists are mindless drones who are told "big bang" at university and just accept it unthinkingly.)
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  6. #106  
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    Quote Originally Posted by Glenn Jacobs View Post
    TECHNICAL QUESTION: With a billion blazing galaxies at different speeds of departure sending red-shifted bright lines our way -- and each star in each galaxy having a different red shift, and opposite sides of each star having different red shifts. does this blur into a homogeneous background radiation?
    It's not just homogeneity. I repeat: It's the conformance -- an amazingly close to perfect one (better than we can build in labs here) -- to an ideal blackbody spectrum that makes the CMB special. It's not just a ubiquitous glow (which is what you keep describing). It's a very special glow.

    Did you bother to read any of the material I linked to earlier? If not, you really should read it. It's well-written (I am not the author of any of those pages), and should clear up a lot of persistent misconceptions.
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    TECHNICAL QUESTION:

    ?? "Black body"??

    ??Is this about all the dark matter in the universe??

    ??Does every piece of matter above Absolute Zero radiate?

    ??Does the background radiation come from the energy within all those -- um, everything from dead stars right on down to quarks??

    ??Does the Moon radiate?? ??Does it have any heat energy left to radiate?? ??Does it radiate the tidal flux energy??
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  8. #108  
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    Quote Originally Posted by Glenn Jacobs View Post
    ?? "Black body"??
    ??Is this about all the dark matter in the universe??
    ??Does every piece of matter above Absolute Zero radiate?
    ??Does the background radiation come from the energy within all those -- um, everything from dead stars right on down to quarks??
    ??Does the Moon radiate?? ??Does it have any heat energy left to radiate?? ??Does it radiate the tidal flux energy??
    Just an FYI: questions don't start with two question marks and they only need to end with a single question mark.

    For example
    ??Does the Moon radiate??
    should be punctuated like so
    Does the Moon radiate?

    I realise that English is not everyone's mother tongue, so this is just meant to be a polite "heads up".
    SayBigWords.com/say/3FC

    "And, behold, I come quickly;" Revelation 22:12

    "Religions are like sausages. When you know how they are made, you no longer want them."
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    You mean, like THIS? Thank you.

    Actually, I speak and write pretty fair English. This funny-business with the question marks was to step myself down from stating my guesses as "theories".

    So I don't have "theories" any more. Just "W.E.G.s" (Wild-Eyed Guesses).

    I guess the moon might radiate. Does the moon radiate? If so, does it radiate something like a Black Body?

    I was throwing in all the extra punctuation to show Strange that my strident insistent statements were now toned down to mere questions -- not to irritate you.
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  10. #110  
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    Quote Originally Posted by Glenn Jacobs View Post
    I guess the moon might radiate. Does the moon radiate? If so, does it radiate something like a Black Body?
    I am pretty sure that the moon only radiates the energy absorbed from the Sun.
    It doesn't have its own internal heat source.
    SayBigWords.com/say/3FC

    "And, behold, I come quickly;" Revelation 22:12

    "Religions are like sausages. When you know how they are made, you no longer want them."
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  11. #111  
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    Quote Originally Posted by Glenn Jacobs View Post
    Is this about all the dark matter in the universe?
    No, "black body" is description of the spectrum (the distribution of power at different frequencies). It is the spectrum that would be emitted by a perfectly black surface at a given temperature.
    Black-body radiation - Wikipedia, the free encyclopedia

    Does every piece of matter above Absolute Zero radiate?
    Yes.

    Does the background radiation come from the energy within all those -- um, everything from dead stars right on down to quarks??
    No. It comes from the point in time when the density and temperature of the universe dropped far enough for it to become transparent, thus releasing all the photons that had been bouncing around before then. This is about 360,000 years after the earliest time we can go back to.

    ??Does the Moon radiate?? ??Does it have any heat energy left to radiate?? ??Does it radiate the tidal flux energy??
    It just reflects sunlight.
    ei incumbit probatio qui dicit, non qui negat
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    Dr. Strange,

    I can see that about the moon reflecting sunlight.

    I have seen the tides come and go.

    I had heard tell that the moon flexes the rocks of the earth as well as the water.

    In a long-ago lecture, I heard that the earth flexes the moon a bit and delivers some measure of energy to it.

    People who know about things like this say the moon is much closer to black than to white.

    Is that tidal energy radiated as heat?

    Is that radiation similar in nature to black body radiation?
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  13. #113  
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    Quote Originally Posted by Glenn Jacobs View Post
    I had heard tell that the moon flexes the rocks of the earth as well as the water.

    In a long-ago lecture, I heard that the earth flexes the moon a bit and delivers some measure of energy to it.
    Very true.

    People who know about things like this say the moon is much closer to black than to white.
    It varies, but I believe it is generally a dark grey.

    Is that tidal energy radiated as heat?
    Tidal stretching of rocks will cause a tiny amount of heating. Compared to the amount of heat from the Sun it is insignificant.
    ei incumbit probatio qui dicit, non qui negat
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    Thank you. You have answered all the preliminary questions.

    So the moon gets some heat from the sun and some from tidal stretching of the rocks, (and some from the "space aliens on the dark side lighting candles to see by!")

    The question then is how it radiates that energy away. As a Black Body? As a dark grey body? Evenly across the spectrum? Lumpy? All moon-frequency? Small as that radiation is, does it look like Background Radiation?

    No. That is not even the question. The question is how does one distinguish between the background radiation coming from every particle in the universe that is above Absolute Zero -- and the background radiation that is bouncing around the whole universe left over from the Big Bang.

    The other question is whether the dark matter produces the background radiation. That's why I asked about the moon.
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  15. #115  
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    Quote Originally Posted by Glenn Jacobs View Post
    The question then is how it radiates that energy away. As a Black Body? As a dark grey body? Evenly across the spectrum? Lumpy? All moon-frequency? Small as that radiation is, does it look like Background Radiation?
    Nearly all the light from the moon will have approximately the same spectrum as the sun (as the moon is a fairly neutral colour). The small amount of thermal radiation will approximate a block body spectrum but will, I assume, be undetectably small.

    No. That is not even the question. The question is how does one distinguish between the background radiation coming from every particle in the universe that is above Absolute Zero -- and the background radiation that is bouncing around the whole universe left over from the Big Bang.
    Not my area of expertise. But, as far as I know, most of the interstellar and intergalactic medium is hot and ionised so has a distinctive and high-energy spectrum which is very unlike a black body. There is also very little of it. My understanding is that detailed measurements of the CMB have to subtract this.

    The other question is whether the dark matter produces the background radiation.
    No. Because dark matter, by definition, does not interact electromagnetically so neither absorbs no emits light.
    ei incumbit probatio qui dicit, non qui negat
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    I see that I have tripped over a definition.

    From your answer, I understand that "dark matter" is not just stuff that doesn't emit light. It is "something else" and cannot interact with energy like familiar things can.

    Let me rephrase the question: Do cold dark objects like the moon and asteroids and meteoroids radiate away whatever heat they receive in the form of something that looks like Black Body radiation?

    Also you said that the interstellar and intergalactic medium is hot and ionized.

    Are we coming back to Aether?

    What medium?

    How could it be hot?

    Every particle (if it has particles) would instantly radiate away its store of heat.

    The comets come in from out in the cold, all frozen and only in approaching the sun do they make a visible tail of ice crystals or frozen water vapor or whatever.

    The meteorites come with a surface blazing hot from atmospheric friction, but they frost over in five minutes after hitting the ground.

    Is something in the interstellar and intergalactic medium "hot" in a way that we don't usually experience hot down here on the ground?

    Is each particle hot from being battered for billions of years on end by energetic photons -- without heating up the vacuum around it?

    AH! The vacuum cannot be heated because it has no corporeality to receive energy.

    So, if there is one hydrogen molecule per cubic kilometer, it can be kept at a white-heat without heating up the void.

    And it will radiate away that energy with a known hydrogen signature.

    But, if there is a piece of rock there, it may radiate away whatever energy it receives with a rock radiation signature, or with a bland, even, amorphous background radiation somewhat similar to a Black Body. (insert a long line of question marks here.)S
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  17. #117  
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    Quote Originally Posted by Glenn Jacobs View Post
    Do cold dark objects like the moon and asteroids and meteoroids radiate away whatever heat they receive in the form of something that looks like Black Body radiation?
    It will be approximately a black body spectrum. Unlike the CMB.

    Also you said that the interstellar and intergalactic medium is hot and ionized.

    Are we coming back to Aether?

    What medium?
    Mainly hydrogen.
    ei incumbit probatio qui dicit, non qui negat
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    Whole different question: How can a planet "capture" a moon?

    PLAN A: They approach, drawn by mutual gravitational pull. As it were, they fall toward one another since forever.

    They miss.

    Since they have the energy of their fall toward each other, they have mutual escape velocity. No orbit.

    PLAN B: They impact. No orbit.

    PLAN C: They just barely graze each other, converting lots and lots of kinetic energy into heat, crushed and vaporized rock and such.

    If one does not lose enough energy in that encounter, no orbit.

    If one does lose sufficient energy, then the orbit is converted to an ellipse. Only, the next time around, they impact. SPLAT! No orbit.


    I asked around and someone suggested that if there were TWO bodies, in orbit about each other, approaching a third body, one of them might be slingshotted right out of the area, carrying the right load of energy to let the other go into orbit.

    Not knowing how energy would be transferred from one body to another, I had to just agree and thank him.

    Now, not a theory, and not even a hypothesis, but a W. E. G. -- suppose a body approaches within it's Roche's Limit -- and then comes apart at the seams. That gives a multitude of bodies with very similar orbits, and SOME of them could be zipped out of there posthaste, leaving others to impact or be captured into orbit.

    Please advise.
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  19. #119  
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    In C, the collision will change the relative orbit of both bodies. It'd be rare, but such a collision could leave two bodies in close, but stable orbits (at least, I think so). Over time, the orbit can widen into a position that couldn't reasonably be reached directly from a collision. (Our moon is moving away from us, slowly.)

    C and D probably happened quite a bit during the formative phase of the solar system, but naturally become less and less likely as fewer and fewer bodies remain. (In fact, C is very close to the current best explanation for our own moon, although it wasn't exactly a graze as it completely destroyed one object and turned the other molten. The moon then formed out of the debris.)

    But all of your scenarios only consider two bodies. Captures are much more likely (though still rare) with three bodies. If a third body passed by during a close approach of two other bodies, it could steal enough energy (look up a gravitational sling shot; same principal) to leave the two bodies in orbit around each other. Energy is transferred through gravity and motion, converting gravitational potential energy to kinetic energy and vice versa.
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    MagiMaster,

    Your explanation is clear. Thank you. I appreciate that.

    The impact version of the formation of the moon indicates nearly a head-on collision, with enough sideways vector for one or more pieces to make an orbit instead of falling back in complete accretion.

    The question remains if the approaching bodies don't actually touch, but pass within Roche's Limit so that one of them is disrupted and comes apart like a cup of hot coffee thrown out the window. Suddenly, instead of a "three-body problem" you have perhaps half-a dozen big ones and several thousand little ones in accordance with fractal rules. My W.E.G. (Wild-Eyed Guess) is that some will impact. Possibly one or more will make orbit and any number of them will be sent, um, ah, elsewhere.

    This does not depend on a third body just happening to be in the immediate neighborhod at exactly the right time.

    Two bodies in orbit around each other approaching a third body also avoids needing that long-shot coincidence.

    Please advise.
    Last edited by Glenn Jacobs; January 21st, 2014 at 03:43 PM. Reason: Put last three sentences in different order.
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  21. #121  
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    Everything I've heard about the moon forming event said that it was a mostly glancing blow as a direct impact would have simply destroyed both bodies. (That is, scattered the pieces too widely to reform as they are now.)

    Having one body break apart from passing too closely sounds like a plausible, if rare, event. You need a large body to pull the smaller one apart, which I think means it'd have to happen later in the process, and you'd need the small body to pass very close to the larger one. The later into the formation you get, the fewer small, mobile bodies there are. (At least that's my understanding of things. I'm no expert on this.) I would imagine there'd be a size limit on the moons that could be produced in this way though, but I wouldn't know where to start to try and calculate what that would be.
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    MagiMaster,

    Thank you.

    All capture events are necessarily rare, as we only see a few dozen possibles in the four billion year history as displayed for this solar system.

    I was just trying to get my head set to understand that "captures" could happen AT ALL.

    Such a thing may have happened to Mars, depriving it of its ancient atmosphere, ocean -- and whatever was laying around loose.

    There is some possible chance those two odd moons of Mars resulted from the encounter.

    Such a thing may have happened to a postulated planet that perchance used to orbit between Mars and Jupiter -- but to its complete destruction. Furthermore, by now, 99% of the pieces seem to have fallen into the sun or Jupiter or someplace.

    Glenn Jacobs
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  23. #123  
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    The moons of Mars do look a lot like captured asteroids, but I don't know if that's the currently accepted explanation or not. I doubt such a capture (or more likely two separate captures) would have anything to do with its oceans though as I really doubt the timing lined up. From what I remember, Mars lost its atmosphere and oceans because its core cooled. That caused it to stop generating atmosphere through vulcanism and most of what was left drifted away into space. Eventually the pressure was too low and the temperature too cold for liquid water to remain on the surface (though it looks like there's still water frozen under the surface).

    (Also from what I remember) The asteroid belt between Mars and Jupiter was never a planet. It was prevented from forming into one by being too close to the massive Jupiter. I don't know whether there's a planet's worth of material in the asteroid belt or not, so I can't really comment on your 99% figure. But it shouldn't really be too hard to look at least some approximate numbers up.

    Another capture event not yet mentioned would be if two objects collided over a larger third object. If they were moving in opposite directions, there would be a major loss of kinetic energy (transformed into heat, etc.) which could leave something with too little energy to escape, but (if the masses were right) enough to stay in orbit.
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    MagiMaster,

    Yes, Sir. It would be a real long shot. Very rare.

    But everything that we see in place in the Solar System is against the odds anyway.

    When I first read "captured asteroid," it seemed like a smooth, neat transaction:

    Asteroid comes near planet. Asteroid goes into orbit around planet. No muss. No fuss.

    Only, the energy of falling since forever is conserved as escape velocity. No closed orbit.

    A slightly grazing collision -- a long shot -- just right to close that hyperbolic orbit into an ellipse -- puts the bodies in contact again at the end of exactly one orbit. SPLAT!

    As you said, a third body is needed to absorb the excess kinetic energy.

    It may even have happened dozens of times in Solar System history that three large objects came close enough to do this dance.

    This neat, smooth transaction is getting very messy looking.

    There is much more chance of two bodies missing by, say, a few hundred miles, than actually touching.

    However, such a close encounter is likely to disassemble the less massive body.

    This gets REALLY messy, so that a liquid-core body is suddenly likely to act like a glass of water thrown thru the air.

    But that sets up the scenario necessary for a "capture": Suddenly there are multiple bodies with only slightly different orbits.

    Some to be "sling-shotted" toward undisclosed destinations. Some to impact. And quite possibly one (with reduced energy) to orbit.

    In the Mars scenario, Mars would be the less massive body and would be nearly destroyed in the transaction.

    The possible(?) plausible(?) former planet(?) that gets reduced to mere asteroids in the other scenario would also be the less massive body -- and it gets scattered to the winds in the encounter. This is "Close Encounters of the Worst Kind."

    This is not settled science. This is not theory. This is not even hypothesis. It is only a W. E. G. (Wild-Eyed Guess).

    Thank you for your patience.

    Glenn Jacobs
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  25. #125  
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    It does seem like a two-body-only capture would be exceedingly unlikely, and almost certainly destructive (in that neither object is likely to retain their original form; like our moon forming event). I have no idea whether either of the moons of Mars were from such events or from less destructive 3-body events. Either way, it doesn't seem likely to me (caveat: based on very little evidence either way) that either Phobos or Deimos were once much larger than they are now.

    Whether or not a grazing collision will always leave the two bodies on either a collision or escape course, I'm not sure. I can just imagine something in between, but I'd have to do some math to really know whether or not it would be possible. (But if you add a third body passing by any time between the two collisions, they might just go into orbit instead.)

    Well, when I say I'd have to do some math, I'd be pretty surprised if the math hasn't already been done, but I don't really know where to look for something that specific.

    As for liquids, at that scale, there's not much difference between water and stone. Both would be scattered in a qualitatively similar way.
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  26. #126  
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    The following abstract addresses reasonably current (2011) thinking on the formation of the Martian moons.

    Rosenblatt, P "The Origin of the Martian Moons Revisited" The Astronomy and Astrophysics Review August 2011

    Abstract
    The origin of the Martian moons, Phobos and Deimos, is still an open issue: either they are asteroids captured by Mars or they formed in situ from a circum-Mars debris disk. The capture scenario mainly relies on the remote-sensing observations of their surfaces, which suggest that the moon material is similar to outer-belt asteroid material. This scenario, however, requires high tidal dissipation rates inside the moons to account for their current orbits around Mars. Although the in situ formation scenarios have not been studied in great details, no observational constraints argue against them. Little attention has been paid to the internal structure of the moons, yet it is pertinent for explaining their origin. The low density of the moons indicates that their interior contains significant amounts of porous material and/or water ice. The porous content is estimated to be in the range of 30–60% of the volume for both moons. This high porosity enhances the tidal dissipation rate but not sufficiently to meet the requirement of the capture scenario. On the other hand, a large porosity is a natural consequence of re-accretion of debris at Mars’ orbit, thus providing support to the in situ formation scenarios. The low density also allows for abundant water ice inside the moons, which might significantly increase the tidal dissipation rate in their interiors, possibly to a sufficient level for the capture scenario. Precise measurements of the rotation and gravity field of the moons are needed to tightly constrain their internal structure in order to help answering the question of the origin.
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    MagiMaster and John Galt,

    Thank you for the free education.

    Having read what you just sent, Iwish to upgrade my W.E.G. (Not to a speculation. A speculation is much higher-level than a W.E.G.!)

    A rather large, somewhat loose accumulation of worse-for-wear asteroids, specifically including Phobos and Deimos, chunks of rock, iron, ice (and old candy-wrappers?) approaches Mars within the Roche Limit and comes apart under the gravitational stress. In a great blur of activity, hundreds of chunks of stuff sort themselves out to impact Mars or to "slingshot" off towards parts unknown -- leaving Phobos and Deimos, now somewhat energy deficient, to go into low and wild orbits.

    The encounter that took Mars' atmosphere and ocean would seem to have happened previously to this one, or it would have taken both moons, too.
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    Given what John posted, that doesn't sound too plausible, but I don't know enough to really say either way.

    An impact large enough to strip away a planet's atmosphere would probably have some impact on the orbits of its moons, especially if they were small ones like Phobos and Deimos. That said, I don't think there's any evidence that Mars lost its atmosphere due to such an impact (and that kind of thing tends to leave a lot of evidence).
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    MagiMaster,

    Not an actual impact, Sir.

    My guess involves a close encounter, within the Roche Limit, which would tear up that approaching lesser body without it actually banging into Mars.

    Accumulation of space thingies approaches Mars.

    Accumulation dis-accumulates.

    Miscellaneous chunks hit the planet.

    Other pieces hit the road for points unknown.

    A two-body encounter suddenly turns into a multi-body one.

    Two big chunks, now known to us as Phobos and Deimos, fortuitously reduced in energy by the transaction, are left going around and around until yet.

    CAPTURE! Two points!

    Whatever disaster happened that sucked away Mars' atmosphere and ocean must have happened earlier, or it would have taken those two little moons, too.

    My guess is that something very heavy came just barely within the Roche Limit of Mars and gathered up air, water and loose rock.
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    My reference to an impact was in reply to the comment on Mars' loss of atmosphere, not on it's moons. All evidence I know of suggests Mars lost its atmosphere slowly over time. And while I'm not exactly confident about a lot of the comments I've made, I'm almost certain no passing body can pull a loose rock off the surface of a planet without severely damaging it (though a variety of ways, such as the massive fireball such a body passing through an atmosphere would generate).
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    MagiMaster,

    Yes. Severe damage. Loss of oceans, atmosphere and all the other loose rocks. At the point where gravity from the heavier object overcomes Mars own gravity, this disruption occurs. Mars itself is pulled, and makes a most destructive instantaneous tidal bulge. A little closer or a little longer time exposed to this gravity and Mars would be taken clear apart, leaving only a second asteroid belt to mark Mars' former orbit.

    That reading concerning Roche's Limit indicates that within a calculable radius, the heavier body would wreck an approaching lighter one, possibly even disrupting it totally.

    A short time of exposure at the edge of Roche's Limit would sweep up oceans, atmosphere and loose rock. A longer one, closer in, would completely break up the lighter body.

    Yes, it would be rare. Maybe close encounters are even more rare than head-on impacts.

    Being a complete newcomer to this, having only heard of Roche's Limit last month, I cannot pronounce settled science. But I think maybe Roche did.

    I offer a W.E.G. (Wild-Eyed Guess) that was the mechanism that wrecked Mars and left it with such odd moons.

    At your suggestion, I looked up some "impact-formed-moon" material and was highly impressed with an artist's illustration showing the earth with a monumental tidal bulge reaching upward to touch the impacting body.

    Now, please imagine unto yourself a body ten times larger than the present moon, composed of an accumulation of outer-Solar-System debris, crossing Earth's orbit again and again, and eventually coming within it's Roche's Limit to the earth. It comes apart at the predictable point, and instantly changes from a two-body close encounter to a multi-body encounter. Some chunks are slingshotted away in predictable directions, carrying excess kinetic energy with them. Some chunks commit the Early Heavy Bombardment of Earth, and some lose the right amount of kinetic energy to go into orbit. Loose pieces fall back into the forming moon. Others are swept up by it during the next few billion years, liberally peppering it with craters (among craters from other violent encounters).

    I really do appreciate your patience with my Wild-Eyed Guess.


    Glenn Jacobs
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    I don't really doubt that such an event is possible, more or less, but I'm pretty sure it wouldn't occur quite like you're imagining it. For starters, the oceans elsewhere on the planet wouldn't be disrupted, at least not in the short time frame you're proposing. The same goes for most of the atmosphere. Plus such an event would likely leave very visible and distinct scars on the surface of Mars that we don't see today. Also, there's no other bodies in the solar system that matches your description and no evidence that such a body once existed.

    If we go measure the composition of Phobos and/or Deimos and find they're strikingly similar to the composition of Mars itself (like how the Earth and Moon are made of extremely similar stuff) then we might have to reconsider things, but so far there's no evidence (at least none I know of) suggesting that Mars experienced such an event.
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    Mister MagiMaster;

    Good point. I forgot to take time into consideration.

    An object going in the opposite direction would be gone before it could do much of anything.

    If it didn't impact, it would be like in the old western train song: "Look out here she comes she's coming! Look out there she goes she's gone!"

    An object going in the same approximate direction, crossing your orbit -- now THAT is a different story and impossible for a mathematical illiterate like me to guesstimate.

    The moon makes a measurable "rock tide" from a quarter-million miles away -- but it's there all day and all night, rolling around the planet about twice a day.

    The artist's illustration of the collision involved in creating the moon showed a tidal bulge perhaps two thousand miles high -- reaching right up to the approaching body and colliding with it. Of course, the artist wasn't there to photograph the event. It could be vastly exaggerated.

    Supposing it took twenty minutes from the time the gravity of the approaching body equaled the gravity of the near point of Mars, until it didn't.

    The approaching object's gravity overcomes the local gravity on one side of Mars.

    Air is no longer held down, but falls up toward the approaching body. That is air from the whole near side of Mars.

    Air from the other side is still pulled down by Mars' gravity and so it pushes sideways for those twenty minutes, creating a hurricane-force wind, tearing things up.

    Water on the affected side of Mars is no longer held down, but falls up toward the approaching body.

    Water from beyond the affected area rushes in, ripping things loose and rolling big rocks along.

    Of course, in twenty minutes not all the air nor even half the water could possibly leave the surface, but the planet would be devastated so that over time, the rest of the air and water might dissipate into space.

    The scars you predict are there. Unexplainable watercourses beginning and ending nowhere. The lack of the known former ocean and atmosphere.

    Comets are described as dirty snowballs. Someplace out yonder they accumulated rock and ice. Asteroids are considered to be largely iron and rock. Some of them are thought to be gatherings of smaller asteroids. No. They don't seem to grow to planet-smashing mass.

    But planets do. The orbits of the existing planets are said to have been "circularized". Before the circularization, they might have had rather more elliptical orbits -- orbits capable of putting Mars close to Earth at one time and close to Jupiter at other times.

    How close would they have to come to do this sort of damage? What would be the Roche's limit between Mars and Earth or Mars and Jupiter? In passing that close, how long would they be so vigorously influencing each other?

    What I have here is not proof. It is merely an idea -- and not necessarily a good idea at that.

    Again, this is not Science, nor a theory, nor even a hypothesis. I doesn't even rise to a speculation, but is a mere W.E.G.

    Look at the cover of the current National Geographic.

    Glenn Jacobs
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  34. #134  
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    The scars I mentioned wouldn't be little things like a lack of water. It would be a vast area of drastically different landscape where the crust had been pulled loose. It would be something clearly visible even after much erosion, especially if most of the water and atmosphere was lost shortly afterwards.
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    Mister MagiMaster:

    With all due respect, Sir, it sounds like you're describing Mars.

    Another planet may have gotten the same treatment, but a little closer and a little longer and if this is so, all that is left of it is about one percent of its former bulk, represented as asteroids.

    Of course that is not even a hypothesis, but a mere Wild-Eyed Guess. My guess is that anciently Mars and Jupiter had somewhat more elliptical orbits and that one time Mars got just barely within its Roche's Limit of Jupiter. Obviously it didn't pull the crust loose, but it took "everything that wasn't nailed down".

    Glenn Jacobs
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  36. #136  
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    Out of curiosity, I calculated the Roche limit for Jupiter and Mars. Mars would have had to come within less than 1 Jupiter radius of Jupiter. (Edit: or less than 1 Jupiter diameter if you use the fluid constant.) That's a bit more than just an elliptical orbit.

    I don't think it's possible for a near miss like that to take "everything that isn't nailed down." I'm sure it could blow away a good chunk of atmosphere, but the water would stay with the rocks. Like I said, at that scale there's not much difference between the two. And yes, if it took rock from the surface, it would take more than just the loose stuff. There would be a massive scar which isn't there.

    Again, everything points to Mars losing its atmosphere and surface water slowly due to being small and cold. There's no evidence it was due to any kind of sudden catastrophe. WEGs are one thing, but you shouldn't hang on to them too tightly, especially when there's evidence for other explanations.

    Edit: Also, given the way the Roche limit is described, it looks like there is very little "almost" to it. Things bulge more and more until suddenly everything falls apart.
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    MagiMaster and Editor;

    Since I cannot calculate things beyond simple algebra, I appreciate that you did.

    What a surprise! I had no idea Mars would have to come that close to start losing important components.

    That would be a real long-shot to get that close without impacting into Jupiter. (I suppose lots and lots of objects have done just that.)

    As I understand it, "elliptical" is the only kind of closed orbit known to modern man. So any way for anything to impact anything else is either an open orbit brings it in from points unknown for a first-round target-hit -- or two crossing elliptical orbits eventually do that. (Could Pluto and Neptune impact? Do the planes of their orbits intersect at all?.)

    For two planets to approach so closely would be a rare occurrence -- even before their orbits "circularized" -- but then, in four point five times ten to the ninth years, lots of rare things have happened in this cubic light-year.

    Obviously the result of the calculation you did was not "one Jupiter radius, center-to-center" because that would mean they would have already impacted.

    Guessing it was "one Jupiter radius, top-of-Jovian-atmosphere-to-top-of-Martian-atmosphere" that is still most amazing close!

    At that point, then, does Jupiter start sucking up Mars' atmosphere?

    One atmosphere-thickness closer and the whole planet comes unzipped?

    It suddenly makes sense that, lacking more evidence, we must consider that Mars' loss of atmosphere was a gradual dissipation to space.

    Immanuel Velikovski was a crackpot. I must stop letting his W.E.G.s influence my aged mind.
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  38. #138  
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    Yeah, it would be one Jupiter radius between the upper edge of the two planets. I really don't know if passing the edge of the atmosphere through the Roche limit without passing the surface through it would cause a significant loss of atmosphere as it would have to happen extremely quickly, but either way terrestrial atmospheres are really, really thin compared to everything else. (Space is only about 100 km away.) I also don't really know what would happen to a planet that came very close to its Roche limit, but I'd be willing to bet we'd see some physical evidence of it.

    And yeah, all closed orbits we've seen are roughly elliptical. Ellipses are what's predicted by Keplerian astrophysics, and Newtonian physics in the 2-body case, but they're only mostly accurate for stable orbits beyond that. Once you get to 3 Newtonian bodies, things can (at least theoretically) get more complicated.

    No idea who Immanuel Velikovski is.
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    MagiMaster,

    Certainly at orbital speeds -- even with Mars and Jupiter going in approximately the same direction -- the time of exposure would be very short.

    The three-body orbits could get more complex than we want to know. I was only taking it as Mars and Jupiter in nearly intersecting orbits.

    Immanuel Velikovski wrote some fascinating crackpot books fifty or a hundred years ago alleging that some astounding things had happened in historical times, including that Mars and Earth came so close every fifty years that their gravity caused big problems to one another. His mission was to prove that many historical happenings described in ancient texts were accurate descriptions of actual results of rather less circularized planetary orbits. Worlds in Collision. Ages of Chaos. Etc.

    Glenn Jacobs
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  40. #140  
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    Oh yeah, I forgot to mention earlier, but Neptune and Pluto would have collided (or at least Pluto would have been shifted elsewhere) if they weren't in a stable 3:2 resonance, which means they'll never actually get particularly close to one another despite their crossing orbits.

    A lot of people have tried to prove various historical accounts as accurate or not. In many cases there just isn't enough evidence to say either way. In some cases there is evidence one way or the other though and in those cases, you have to go with the evidence.
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    MagiMaster,


    Does "3:2 resonance" mean that for every time Nepture goes around three times, Pluto goes around twice?

    Does "stable" mean that Neptune fortuitously pulls Pluto a little (when they get closest) to make it stay in that resonance?

    Does it mean that if Pluto got to that point a day early, Neptune would pull it from behind?

    Does it mean that if Pluto got to that point a day late, Neptune would pull if from in front?

    Does it mean that the place where they get closest is not anywhere near where the two orbits intersect?

    Does "shifted" mean that it would violently "perturb" Pluto's orbit permanently?

    Did Neptune at some time in the past perturb Pluto into its present resonance?

    If it were not for this resonance would the two planets come to the intersection of their orbits at different times until finally they both got there at the same time?

    If that were to occur, would there be any other possibility than (A) Pluto gets sling-shotted into some new orbit; (B) Pluto ijpacts Neptune, or (C) Pluto becomes a captured moon -- ?

    Are some other pairs of planets in stable resonance?

    Assuming a random starting point at some random time and all the sky-thingies were in random orbits, how do two planets get into lock-step like Neptune and Pluto?

    Glenn Jacobs
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  42. #142  
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    Yes, roughly, I don't know, I don't know, yes, I think so, Neptune and probably other bodies, more or less, not that I can think of right now, not sure (but I know several moons are), it's stable.

    Err, maybe I can elaborate on some of those. Yes, resonance means that Neptune goes around 3 orbits for every 2 orbits of Pluto and in their specific resonance when Pluto is within Neptune's orbit, Neptune is a quarter orbit away from it (if I've got that straight in my head). If they weren't in such a resonance, the most likely result would be that Neptune would alter Pluto's orbit after the first close pass which could lead to a collision later. (Most resonant orbits are unstable with each orbit pulling things a little further out of line each orbit.)

    As to how things get into a stable orbit, I'm not exactly sure, but as a stable configuration, small differences get damped out over time, so it just needed to start close. (Also, it's impossible to reason post hoc about probabilities.)

    I don't know which planets are in resonant orbits. I do know several moons of Jupiter and Saturn are in similar orbits. You can check the Wiki article for some examples.
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    MagiMaster:

    I think I understand what you said:

    In a stable resonance, the differences are ironed out by corrections. [ Naturally, they don't know they are correcting anything.]

    If Pluto arrives one second late to the point at which they are closest, there is Neptune pulling (perturbing) from in front.

    If Pluto gets there one second early, there is Neptune perturbing from behind. Even if they are fifty million miles apart, this slight correction tends toward stability.

    In an unstable resonance, the supposed "resonance" is all just a coincidence. A million trips later and they are completely out of phase.

    Glenn Jacobs
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  44. #144  
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    While it's not quite that simple, that's more or less right, at least from what I understand.
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    MagiMaster:

    That was the best I could come up with based on your saying that the differences got ironed out over time.

    It has to work, or by now Pluto would have impacted Neptune, been captured by it or been sent packing on some close encounter.

    Thank you.

    Glenn Jacobs
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    MagiMaster:

    Me again, Sir. What you said about the formation of the moon got me going on the same tangent again.

    Almost certainly, most of the material of the moon comes from the earth's crust.

    How's it get up there?

    PLAN A: The moon formed and accreted in place at the same time that the crust of the earth was accreting -- after the iron core was in place.

    PLAN B: "Theia' came and knocked a big piece off of the earth. Some fell back down. Some went elsewhere. Some formed up the moon and more fell into it later.

    PLAN C: Back in the eons before the orbits regularized and circularized and shaped into parallel planes, and when great big planets were still banging into each other, ProtoEarth and Jupiter (or Nibiru -- or Nemesis or Krypton or whatever) came very close to impacting.

    Close enough for the tidal forces to tear big blobs of the still liquid rock crust off. Some fell into Jupiter. Some were gravity-boosted away to points not of interest, and some, having lost the right amount of kinetic energy in all the confusion, went into orbit around ProtoEarth.

    No lithosphere-to-lithosphere impact.

    No mystical "Theia".

    Liquid floating rock would be lifted off the liquid iron core when Jupiter's gravity overcame Earth's gravity at that place and time.

    Twenty minutes longer in that planet-wrecker and Proto-Earth would have been reduced to asteroids.

    By the time Earth and Jupiter came into close opostition again, the orbits had changed enough so that they didn't come nearly that close again.
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  47. #147  
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    There's nothing mystical about any of this. The theory of such an impact was nearly dismissed out of hand for being too outrageous when it was first proposed, so why do we consider it the most likely explanation today? Because it's the explanation with the most evidence.

    Also the planets were never in that elliptical of an orbit. They formed out of a rotating disk of gas and dust and the orbit of a planet is the average of the orbits of the dust grains that made it. Only later disturbances caused anything to enter any particularly elliptical orbits.

    Further details.
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    MagiMaster,

    ?Theia could approach Earth, but Earth could not approach Jupiter?

    ?Or Mars? ?Or Venus? ?Or some "loose cannon" of a formerly-existing planet?

    ?Orbits got circularized over eons of time but were never way out-of-round nor way out of the plane of the Zodiac?

    Back to the drawing board! (I've GOT to get Velikovski out of my mind.)

    All right, here's another W.E.G. -- without the wildly-shifting orbits:

    ?ProtoEarth and ProtoMoon accumulate rock, iron and stuff falling into them?

    ?The heat of impact melts it all?

    ?Some rather larger impacts splatter most of that ancient iron moon all over space?

    ?The much-larger ProtoEarth takes the big impacts without losing much material?

    ?The iron largely stops falling but the rocks continue unabated?

    ?ProtoEarth and ProtoMoon continue to accrete from the infall of rock -- plus a little iron?

    Fast forward a few billion years to the present. We find the moon and the earth made of similar materials, but the moon is without much of an iron core.

    (Naturally this guess depends on the proportion of rock and iron infall changing over astronomic ages. No doubt that has been measured. It could be that in the hot ProtoSun disk, the iron distilled out first and the rock later?)

    Glenn Jacobs (Not to be confused with the professional wrestler of the same name)
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  49. #149  
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    Theia was supposed to be around the size of Mars, which is about 11% the mass of the Earth. It's much easier to knock small planets out of orbit. And I said the planets formed in mostly circular orbits, not that they were never out of those circles, but once you start perturbing orbits, things tend to become unstable since the perturbation will keep happening. Ending up back in a mostly circular orbit seems unlikely. (Things that perturb each other into more stable orbits do happen, but an orbit that crosses from Earth to Jupiter is not stable.) Theia probably formed in an orbit that was too close to one of the gas giants and over time got pulled into a more and more elliptical orbit until it collided with something.

    That page I linked earlier mentioned the co-accretion hypothesis. It also said that that doesn't account for the angular momentum of the Earth and Moon. I'm not exactly sure what the accretion hypothesis predicts it should be, but someone's crunched the numbers and it doesn't add up.

    As for your WEG, why is that any better than the hypothesis that a giant impact formed the moon itself? Why would an impact scatter the iron any more than the rock? The protoplanetary disk already contained all the iron and rock that would later make up the planets. There's no distillation there. Everything acts under gravity which doesn't distinguish much between iron and rock.

    As I said, no one much liked the giant impact hypothesis when it was first proposed. Most scientists dismissed it as a WEG. But again, the reason we call it the 'truth' (in so much as science can claim something is true) today is because it is the explanation with the most evidence for it. If you want to change that view, you'll need evidence that something else was more likely. A WEG is of no interest to any scientist unless you also have some evidence to go with it.
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    Completely changing the subject here.

    Some Solar System moons are considered "captured asteroids".

    Let me see if I understand this:

    Asteroid orbit intersects planetary orbit.

    Sooner or later the actual asteroid approaches the actual planet.

    PLAN A: Asteroid impacts planet. (Yes, this may be considered a capture, but not the kind we're talking about here.)

    PLAN B: Asteroid barely misses planet. Having fallen toward it since forever, it has built up immense energy, makes a single open orbit and never comes back.

    PLAN C: Asteroid barely grazes planet. It loses much kinetic energy, turning it to pulverizing rock, vaporizing rock and throwing big rocks around. But not enough. The main body of the asteroid still maintains escape velocity and takes off for parts unknown.

    PLAN D: Asteroid barely grazes planet. It loses just the right amount of energy to make a closed orbit. After exactly one point zero elliptical orbit, it comes back to the same relative position, and impacts.

    PLAN E: Asteroid is a double.
    One gets the gravity slingshot treatment and the other loses enough energy in that maneuver to go into a closed orbit.
    CAPTURE! Two points! (Double asteroids being relatively rare, PLAN E hardly ever happens.)

    PLAN F: "Rubble pile" or other fragile asteroid approaches planet. Is torn apart by gravity stresses just inside its Roche's Limit. Suddenly this is no longer a two-body problem, but multi-body. Some of the pieces impact the planet. Some of the pieces get the gravity slingshot treatment, greatly adding to their kinetic energy, and they go far, far away. One or more pieces actually lose energy in the transaction, and one may go into stable elliptical orbit.

    Capture! Two points!

    Please advise.
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  51. #151  
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    See above.

    No new ideas. No private theory to overcome Newton or Einstein.

    Just me trying to understand asteroid capture.

    Please advise.
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  52. #152  
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    I can't really offer any advice beyond what I've already given. I'm not a cosmologist. All your bullet points sound plausible, but beyond that I don't know any details or whether or not you've overlooked some cases.
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  53. #153  
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    Thank you. Thank you.
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  54. #154  
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    Actually, there's one case you did miss, which is a moon-forming collision where the asteroid is destroyed from the collision, but the debris ends up in orbit. Something between D and F.
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    MagiMaster,

    Ah! Thank you.

    Something like this?

    Asteroid grazes planet and busts up into large and small fragments according to the principles of fractal geometry.

    Many pieces stay on (or in) planet.

    Many pieces bounce off in open orbits and are never seen again.

    Some pieces bounce off in closed orbits and impact after exactly one trip. (They fall back.)

    One or more pieces bounce off in stable closed elliptical orbits (Having lost the "correct" amount of kinetic energy in the transaction) -- possibly to form a ring -- or (a really long shot) to recombine after a few million trips around.

    (Is there an action collecting rocks? Certain known asteroids are designated "rubble-piles" . Can loose rocks in space bump together so gently they don't bounce apart? Can all the kinetic energy of them moving toward one another be transmogrified into pulverizing a bit of their contacting surfaces when they impact? Crunch!)

    Glenn
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  56. #156  
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    Well, something like that. After a collision, some of the debris will be from the planet itself as well as the remains of the asteroid. And yes, a ring system is certainly one possible outcome. Whether those rings collapse to the planet or form into a moon is a question I'm pretty sure astronomers have looked in to, but I don't know the answer. (Ring systems are unstable though, so they have to go somewhere in the long run.)
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    MagiMaster,

    Unstable? They fade after a million years? A billion?

    Saturn's rings, then, are new -- or get renewed from fresh infall?

    The faint rings of the other gas giants are old?

    Faded?

    Do they accumulate into little moonlets that we cannot see?

    Do they fall into the planet?

    What could slow them down?

    Glenn
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  58. #158  
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    Here's some information: Planetary ring - Wikipedia, the free encyclopedia
    I think that page has better answers than I could give.
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    MagiMaster,

    Thank you. I went to that site and read it all the way to the bottom.

    I better go read it all again, because I don't feel any smarter.

    Glenn
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    If you really want all the details, you'd likely have to take a few astronomy courses at a university. (While you can probably find the answers to any specific question by digging around the internet, there's still a lot of details and questions-you-didn't-know-to-ask that you'd miss out on.)
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