New theory explains how the moon got there

Posted: November 2, 2016 by oldbrew in Celestial Mechanics, moon, solar system dynamics
Tags: ,

sun-earth-moonA key point of the new theory is that as the Moon migrated outwards from Earth, its orbit reached a critical distance where the Sun’s gravitational influence overtook that of the Earth, as Phys.org explains. Needless to say there’s more to it than that.

Earth’s Moon is an unusual object in our solar system, and now there’s a new theory to explain how it got where it is, which puts some twists on the current “giant impact” theory. The work is published Oct. 31 in the journal Nature.

The Moon is relatively big compared to the planet it orbits, and it’s made of almost the same stuff, minus some more volatile compounds that evaporated long ago. That makes it distinct from every other major object in the Solar System, said Sarah Stewart, professor of earth and planetary sciences at the University of California, Davis and senior author on the paper.

“Every other body in the solar system has different chemistry,” she said.


Textbook theory

The textbook theory of lunar formation goes like this. Late in the formation of the solar system came the “giant impact” phase, when hot planet-size objects collided with each other. A Mars-sized object grazed what would become Earth, throwing off a mass of material from which the Moon condensed. This impact set the angular momentum for the Earth-Moon system, and gave the early Earth a five-hour day. Over millennia, the Moon has receded from the Earth and the rotation has slowed to our current 24-hour day.

Scientists have figured this out by looking at the Moon’s current orbit, working out how rapidly angular momentum of the Earth-Moon system has been transferred by the tidal forces between the two bodies, and working backwards.

But there are a couple of problems with the textbook theory. One is the Moon’s surprisingly Earth-like composition. Another is that if the Moon condensed from a disk of material rotating around Earth’s equator, it should be in orbit over the equator. But the Moon’s current orbit is tilted off the equator, meaning some more energy must have been put in to move it.

An alternative to explain it all

Stewart, her former postdoctoral fellow Matija Ćuk (now a scientist at the SETI Institute in Mountain View, Calif.), with Douglas Hamilton at the University of Maryland and Simon Lock, Harvard University, have come up with an alternative model.

In 2012, Ćuk and Stewart proposed that some of the angular momentum of the Earth-Moon system could have been transferred to the Earth-Sun system. That allows for a more energetic collision at the beginning of the process.

In the new model, a high energy collision left a mass of vaporized and molten material from which the Earth and Moon formed. The Earth was set spinning with a two-hour day, its axis pointing towards the Sun.

Because the collision could have been more energetic than in the current theory, the material from Earth and the impactor would have mixed together, and both Earth and Moon condensed from the same material and therefore have a similar composition.

As angular momentum was dissipated through tidal forces, the Moon receded from the Earth until it reached a point called the “LaPlace plane transition,” where the forces from the Earth on the Moon became less important than gravitational forces from the Sun. This caused some of the angular momentum of the Earth-Moon system to transfer to the Earth-Sun system.

This made no major difference to the Earth’s orbit around the Sun, but it did flip Earth upright. At this point, the models built by the team show the Moon orbiting Earth at a high angle, or inclination, to the equator.

Over a few tens of million years, the Moon continued to slowly move away from Earth until it reached a second transition point, the Cassini transition, at which point the inclination of the Moon—the angle between the Moon’s orbit and the Earth’s orbit about the sun—dropped to about five degrees, putting the Moon more or less in its current orbit.

The new theory elegantly explains the Moon’s orbit and composition based on a single, giant impact at the beginning, Stewart said. No extra intervening steps are required to nudge things along.
“One giant impact sets off the sequence of events,” she said.

Source: New theory explains how the moon got there | Phys.org

Abstract: Tidal Evolution of the Moon from a High-Obliquity Fast-Spinning Earth

Comments
  1. Curious George says:

    At the first glance it looks like something fitting in the Journal of Irreproducible Results. Where did they publish it? Nature (2016), DOI: 10.1038/nature19846. A good fit, still.

  2. Peter Norman says:

    Big deal. Guess how the Moon got there? It happened and Earth evolved as a result. I spend my time thinking about why the Universe is here and what’s so special about Earth that we are here thinking about it! How are you ever going to prove one way or another how the moon got there?

  3. oldbrew says:

    The Laplace plane transition

    The Cassini transition

    Abstract says: ‘We use a numerical integrator that follows both the orbit and the spin of the Moon, and find that the Moon was likely in non-synchronous rotation for a prolonged period during Cassini state transition, implying inclination damping in excess of that in synchronous rotation.’

  4. oldbrew says:

    @ Peter Norman

    Science develops theories, but proof is tough.

  5. pg sharrow says:

    Sorry, this doesn’t pass my “sound” test. buzzzzzzzzzzzzzzzzzzzzzzzz!
    next..pg

  6. “The Clockwork Moon Science Ignores”

    Since my discovery–and extensive verification, along every line of study–of the Great Design of the “gods” (as I call it), it is obvious to me (and should be obvious, to anyone, especially scientists, reading the article) that the Moon’s orbit was designed, and that should have been long recognized by science, if it had not gone wrong with the extended Darwinian paradigm, that everything science observes–both the life on Earth and the Earth itself–developed through undirected evolution, that is, through undirected physical processes only (with ever more “cosmic accidents”, always “near the beginning”, needed to keep the paradigm going).

    The paradigm of undirected evolution–especially of the Earth, and Moon–has failed, has in fact been disproved by my unprecedented research.

  7. suricat says:

    Posted: November 2, 2016 by oldbrew in Celestial Mechanics, moon, solar system dynamics
    Tags: moon, solar – planetary theory

    “The Moon is relatively big compared to the planet it orbits, and it’s made of almost the same stuff, minus some more volatile compounds that evaporated long ago. That makes it distinct from every other major object in the Solar System, said Sarah Stewart, professor of earth and planetary sciences at the University of California, Davis and senior author on the paper.”

    This factor is well noted in various ‘other’ disciplines OB. A ‘similar chemistry’ intimates a ‘similar origin’. However, the ‘size’ (mass) of the ‘moon’ would suggest a ‘co-orbit’ within an ‘orbit’.

    Bearing in mind that Earth’s Moon always places the ‘same face’ (same longitudinal presentation) towards Earth’s ‘centre of gravity’ suggests that a gravitational ‘teleconnection’ continues to be extant between the two bodies. Thus, the ‘two bodies’ still ‘orbit’ as one.

    “The textbook theory of lunar formation goes like this. Late in the formation of the solar system came the “giant impact” phase, when hot planet-size objects collided with each other. A Mars-sized object grazed what would become Earth, throwing off a mass of material from which the Moon condensed. This impact set the angular momentum for the Earth-Moon system, and gave the early Earth a five-hour day. Over millennia, the Moon has receded from the Earth and the rotation has slowed to our current 24-hour day.”

    This would be the theoretical impact of the, assumed, Thea with the/a ‘proto’ Earth. The ‘theory’ is quite plausible, but ‘the factual observation’ is negative. Whilst I sympathise with this POV it relies on the ‘truth’ within a ‘model’ (which is hard to prove). However, I do favour it. Lunar and Earth ‘tidal’ observation does imply a complicit behaviour between the Earth and ‘the Moon’ (Earth’s subordinate companion).

    Its late for me, I’ll finish this post later OB.

    Best regards, Ray.

  8. Richard111 says:

    Plate tectonics seems to indicate that considerable continental material is missing from the surface of the earth. Maybe the earth was not that ‘molten’ when the collision occurred?

  9. oldbrew says:

    Ray says: ‘Bearing in mind that Earth’s Moon always places the ‘same face’ (same longitudinal presentation) towards Earth’s ‘centre of gravity’ suggests that a gravitational ‘teleconnection’ continues to be extant between the two bodies. Thus, the ‘two bodies’ still ‘orbit’ as one.’

    Yes, and synchronous rotation aka tidal locking (orbit period = rotation period) is standard for regular-shaped moons of planets in the solar system.
    http://en.wikipedia.org/wiki/Tidal_locking

    But I agree there’s something more – the Sun? – going on with the Moon’s orbital behaviour due to its large size relative to Earth, as the post mentions.

    For example Saturn’s largest moon Titan is bigger than the planet Mercury and orbits at an inclination of just 0.34854° (to Saturn’s equator), compared to our Moon’s 5.145° to the ecliptic.
    http://en.wikipedia.org/wiki/Titan_(moon)

  10. tom0mason says:

    On a different tack, it is arguable that without our over large moon, life would have never have left the oceans. With that said, all these scientist watching other planets orbiting distant stars rarely seem to think about how life here started and progressed.

  11. TA says:

    https://en.wikipedia.org/wiki/Venus#Orbit_and_rotation

    “Alex Alemi’s and David Stevenson’s 2006 study of models of the early Solar System at the California Institute of Technology shows Venus likely had at least one moon created by a huge impact event billions of years ago. About 10 million years later, according to the study, another impact reversed the planet’s spin direction and caused the Venusian moon gradually to spiral inward until it collided with Venus. If later impacts created moons, these were removed in the same way. An alternative explanation for the lack of satellites is the effect of strong solar tides, which can destabilize large satellites orbiting the inner terrestrial planets.”

    Maybe large moons around terrestrial planets is more common than we think, and not such a random process.

    I read a study once speculating that two large planets could form while in the same orbit, and would eventually collide with each other, so this kind of large planetary collision may not depend solely on a random object being thrown into the inner solar system.

    So my question is, how common are terrestrial planets with large moons, in solar systems like ours? Are the collisions that would form such moons random events, or a more common occurrence, as a consequence of how planets form in a solar system similar to ours?

  12. oldmanK says:

    Quote from TA: “About 10 million years later, according to the study, another impact reversed the planet’s spin direction…..” Recalling ‘dimly’ the exercises in applied maths, that’s a big momentum change. Rotational momentum, but in the linear direction there is likely also a big effect, perhaps enough to destablise an orbit.

    Since the obliquities of the the ss planets to the ecliptic are none at zero but vary to a large degree other forces are likely at play. obliquity: http://solarviews.com/cap/vss/VSS00105.htm

  13. oldbrew says:

    I feel a post about certain lunar periodicities and the tropical year coming on – sometime soon 😎

  14. Tenuc says:

    I think this explanation suffers from the same problems the rest of the mainstream cosmological theories suffer from. As usual, this one is too complex and relies too much on chance accidents and special pleading to have any significant merit. Any new conjecture must meet the criteria that everything that happens in the Universe will follow a few simple rules, be self similar at all scales and require no special different mechanisms or accidents to explain all.

  15. oldbrew says:

    Tenuc: perhaps, but the Moon has no equivalents in the solar system.

  16. suricat says:

    oldbrew says: November 3, 2016 at 11:16 pm

    “Tenuc: perhaps, but the Moon has no equivalents in the solar system.”

    I concur! ‘Earth’s Moon’ possesses ~1/3 of Earth’s mass constituent and is/has the ‘greatest’ mass property ratio for any ‘planetary satellite in orbit around a planet’ within Sol’s system. Moreover, gravitational influence is still being ‘modified’ by the ‘left over’ ‘inertia’ that generated this scenario in the first instance.

    IMHO we witness a changing ‘inertia/gravity’ on/within this subject. However, we also need to get back to ‘basic principles’ with a ‘cross discipline’ agenda. The subject is bigger than any singular discipline can observe/understand.

    Best regards, Ray.

  17. oldbrew says:

    Tenuc says: ‘Any new conjecture must meet the criteria that everything that happens in the Universe will follow a few simple rules, be self similar at all scales and require no special different mechanisms or accidents to explain all.’

    This might be of interest…

    Scientists confirm a structural similarity found in both human cells and neutron stars
    http://phys.org/news/2016-11-scientists-similarity-human-cells-neutron.html

    DNA anyone?

  18. Tenuc says:

    oldbrew says:”…Scientists confirm a structural similarity found in both human cells and neutron stars…”

    Thanks for the link. I suspect that in both cases the structures are the result of aligning atoms to facilitate MEP. This ensures that the most energy possible will be extracted from the ambient photon charge field to do work. However, I don’t think this necessarily means that the extracted energy will be used for the same purpose in both systems. Will be interesting to see if this sort of structure occurs in other systems.

  19. Tenuc says:

    The moon is curious in many ways. While watching a total eclipse back in 1999 in Cornwall, I was amazed to have visual confirmation that it lookrd exactly the same size of the sun. It is also strange that the density of the moon is only 3344 kg/m3, while the Earth is 5514. Perhaps if we could develop a better understanding of our small binary system, we would gain insights into how the Universe operates?

  20. oldbrew says:

    Tenuc: ‘Perhaps if we could develop a better understanding of our small binary system, we would gain insights into how the Universe operates?’

    Well, we’ll give it a go – stay tuned 😉

  21. Peter Norman says:

    @ oldbrew

    On reflexion, perhaps I gave the impression Moon science is unimportant in the “universal” picture.
    A unique property of our Moon is how it stripped away most of the Venus-like atmosphere Earth would have developed, magically leaving a hydrosphere. I’m interested in the probability this could ever happen in another solar system. Multiply this by the probability of finding another Sol with a similar planet configuration you realise the probability of another Earth in the known Universe is mind-blowingly small. Mankind is more alone than scientists are prepared to believe.

    On a lighter note: Did you hear the joke about the scientist who spent his whole life looking for proof of intelligence elsewhere in the Universe? He never used his own intelligence to work out the probability of finding it!

  22. pg sharrow says:

    I would posit that the original planet that the Earth/Luna pair was created from was a small gas giant orbiting about where the asteroid belts are now. There are several that are in the planetary plain and one that is inclined that marks the path of the intruder and the point of the near collision. Present Earth /Luna orbit tells me that the near pass was behind and not a collision and was a very large body several times the larger then the present Earth…pg

  23. Peter Norman says:

    @ pg

    Any and all theories of Earth/Luna evolution are open for discussion as far as I’m concerned.
    We’re unique in the known Universe until some alien tells us otherwise.

  24. pg sharrow says:

    I would suspect we are late to that game🙂 we are probably under an embargo for being far too dangerous to approach!..LoL…pg

  25. Wayne Job says:

    Some five or ten thousand years ago the Sumerians wrote down what their bosses told them.
    According to them we were indeed crashed into by a watery world called Tiamat and half the earth was smashed off, but we did gain water. They detail most of our solar system. I only put this up because the scientists are saying something similar.

  26. oldbrew says:

    Everything we know about the formation of solar systems might be wrong, say two astronomers. They’ve discovered the first “binary–binary” — two massive companions around one star in a close binary system, one so-called giant planet and one brown dwarf, or “failed star” The first, called MARVELS-7a, is 12 times the mass of Jupiter, while the second, MARVELS-7b, has 57 times the mass of Jupiter.

    http://www.sciencedaily.com/releases/2016/10/161019162507.htm

  27. suricat says:

    Tenuc says: November 4, 2016 at 8:39 pm

    Sorry for the delayed response. My time is short.😦

    “I suspect that in both cases the structures are the result of aligning atoms to facilitate MEP.”

    I didn’t read it, but:

    Tenuc says: November 4, 2016 at 9:11 pm

    “It is also strange that the density of the moon is only 3344 kg/m3, while the Earth is 5514.” (5514 kg/m3?).

    This is cogent to the ‘Moon’ coalescing from/following a ‘Proto-Earth’ collision with another body Tenuc. Inertia transferred by collision is key here.

    Where/when inertial transfer is effected the ‘energy transfer’ provides a ‘boost’ (greater acceleration) to the ‘lighter’ (less massive elements/compounds) ‘not by the MEP process’, but by the ‘RKP’ (Received Kinetic Process) that ‘leaks’ into ‘other kinetic domains’ that remain unspoken here.

    If you ‘kick’ a cannon ball, it doesn’t go/travel far, but if you ‘kick’ a football it transits a much greater distance for the same ‘energy kick’ to the ‘cannon ball’!

    Pre-contact, the planets play a ballistic dance directed by local gravity. Post-contact, we don’t have planets, but we do have explosive debris that was ‘kicked’ with ~the same kinetic possessing angle vectors to only be speculated upon, and variant speed vectors dependant upon the mass value of the debris.

    Its quite ‘cogent’ that ‘lighter massive materials’ should be thrown further from the/a joint centre of gravity following a light ‘coming together’ type of collisional event IMHO.

    This leaves the ‘rotational element’ from the/an ‘event’. Denser and heavier material mass would remain ‘closer’ to a joint centre of gravity and provide the ‘major massive body’ for the system, whilst maintaining any ‘torque’ (rotational force) induced by the collision. ‘Lighter material’ may either ‘dissipate’ elsewhere, or ‘coalesce’ into a ‘solid body’ at some distance from the ‘major massive body’ to finally ‘orbit’ it.

    At least, IMHO, that’s the way that I envisage events.

    Your thoughts?

    Best regards, Ray.

  28. oldbrew says:

    It’s thought the Moon has less iron content than the average planetary body, including other moons.

    The mass of the Moon is sufficient to eliminate any voids within the interior, so it is believed to be composed of solid rock throughout. Its low bulk density (~3346 kg m−3) indicates a low metal abundance. Mass and moment of inertia constraints indicate that the Moon likely has an iron core that is less than about 450 km in radius. Studies of the Moon’s physical librations (small perturbations to its rotation) furthermore indicate that the core is still molten. Most planetary bodies and moons have iron cores that are about half the size of the body. The Moon is thus anomalous in having a core whose size is only about one quarter of its radius. [bold added]

    http://en.wikipedia.org/wiki/Geology_of_the_Moon

  29. oldbrew says:

    ‘Extra-supermoon’ to appear next week [14th Nov.]
    Stay up Monday night because Luna’s not going to be readier for a close-up for 18 years

    http://www.theregister.co.uk/2016/11/08/extrasupermoon_november_14_2016/

    “Supermoons” occur when the new or full moon coincides with Luna’s closest approach to Earth, although the term also gets used whenever the Moon is especially bright and close to Earth.

    But next Monday the term gets a proper workout as it not only offers a full moon, but will also see Luna reach its perigee, the point of its orbit closest to Earth. NASA’s using the “extra-super” moniker because the 14th is also the moon’s perigee for all of 2016.

  30. oldmanK says:

    In the above something has been missed. The new model requires an earth tilt of 75 degrees.

    [reply] good spot

  31. suricat says:

    oldbrew says: November 4, 2016 at 11:26 pm

    “Well, we’ll give it a go – stay tuned ”

    I disagree oldbrew. ‘Vectors’ are complex and ‘outcomes’ from ‘explosive decompression’ via local gravitational constraints are ‘chaotic’ without a ‘complete understanding’ of events as they unfold/occur.

    A historic ‘model’ (observed data) isn’t available. We can only ‘assume’ events from ‘first principles’ and overlay our POV upon this. This is ‘historical autopsy’ performed with a ‘logical progression’ of ‘Geological evidence’, which brings me to your link in “oldbrew says: November 8, 2016 at 9:18 am” (sorry, but I need to jump posts [yes, I’m in ‘catch-up’ mode]): https://en.wikipedia.org/wiki/Geology_of_the_Moon#Gallery
    Here a comparison of the ‘near’ and ‘far’ sides of the Moon can be ‘visually’ made in the first two images from the left.

    Do you notice the difference in the ‘size of impact craters’ between the ‘near’ and ‘far’ sides? To me this strongly suggests that the ‘oldest’ Lunar terrain is ‘near-side’, whilst the ‘youngest’ Lunar terrain is ‘far-side’. I’ll explain.

    Following any ‘impact event’ (an ‘explosive decompression’ of mass within the local vicinity) an ‘accretion disc’ evolves around the ‘local gravity centre’ generated by the two bodies in collision, and IMHO where the original ‘two bodies’ only suffered a ‘light contact’ (glancing blow) scenario, the angle of the ‘accretion disc’ would be the ‘mean’ between the resultant angle of contact for the bodies (which we don’t know) and the ‘rotational momentum’ for each body prior to ‘contact’ (which we also don’t know).

    However, it is logical to presume that Earth’s orbiting Moon took ‘major hits’ in its infancy (this is evident from the ‘near-side’ graphic), but the Moon took more ‘minor hits’ to its ‘far-side’. IMHO this is conversant with Earth’s Moon ‘mopping up’ low mass debris from the accretion disc generated from a ‘Proto-Earth collision’ and the logic towards a constant ‘Moon face towards Earth’. The Moon’s ‘core’ (gravity wise) ‘is/must be’ ‘offset’ from its central point of the satellite to ‘always’ face Earth.

    Your thoughts oldbrew?

    Best regards, Ray.

  32. oldmanK says:

    Picked 2nd hand from another site; says “Moon shielding Earth….” http://neo.jpl.nasa.gov/j002e3/j002e3d.gif

    [reply] see: http://en.wikipedia.org/wiki/J002E3

  33. oldbrew says:

    @ suricat / ray

    I haven’t put the post up yet!

    Re: ‘Do you notice the difference in the ‘size of impact craters’ between the ‘near’ and ‘far’ sides?’

    Yes. One theory is that compression from Earth affects the near side.

    SHRINKING MOON LINKED TO EARTH’S TIDAL FORCES

    Tom Watters, a planetary geologist at the National Air and Space Museum and researcher with NASA’s Lunar Reconnaissance Orbiter (LRO) project, made headlines in 2010 with his discovery that the moon is shrinking incrementally.
    http://insider.si.edu/2015/10/shrinking-moon-linked-to-earths-tidal-forces/

    NASA explains: ‘Though both sides of the moon were bombarded by similarly large impactors, the near side hemisphere crust and upper mantle was hotter than that of the far side, resulting in the larger impact craters.’ [bold added]

    http://en.wikipedia.org/wiki/Near_side_of_the_Moon#Differences

    But…
    It is commonly suggested that the reason the mare only erupted on the nearside is that the nearside crust is thinner than the farside. Although variations in the crustal thickness might act to modulate the amount of magma that ultimately reaches the surface, this hypothesis does not explain why the farside South Pole-Aitken basin, whose crust is thinner than Oceanus Procellarum, was only modestly filled by volcanic products.

    http://en.wikipedia.org/wiki/Geology_of_the_Moon

  34. suricat says:

    oldbrew says: November 10, 2016 at 9:17 am

    “@ suricat / ray
    I haven’t put the post up yet!”

    Didn’t you notice the ‘in post’ date change?

    “Re: ‘Do you notice the difference in the ‘size of impact craters’ between the ‘near’ and ‘far’ sides?’
    Yes. One theory is that compression from Earth affects the near side.”

    Huh? That doesn’t sound very convincing at all. Did you understand my post? I’m describing ‘bombardment’ of the Lunar surface here. Not Vulcanism, tidal stress, or thermal contraction. Anyhow, Earth ‘stretches’ the ‘near side’ towards Earth more than it does to the ‘far side’. That’s how gravity works.

    “SHRINKING MOON LINKED TO EARTH’S TIDAL FORCES”

    True, but not by the logic implied by your link. The Earth/Moon gravity interface continues to provide a ‘teleconnection’ between the Earth and its Moon.

    However, this ‘teleconnection’ is about ‘Earth spin’ and ‘Lunar orbital speed’. As the Moon ‘accelerates’, Earth’s ‘rotation rate’ decreases. Energy from ‘Earth rotation’ is supplying Earth’s Moon with energy to project ‘the Moon’ into a ‘higher orbit’. The “SHRINKING MOON” ‘scenario’ would be better linked with increasing altitude for understanding my input here. I’m an Engineer, not a Geologist.

    “NASA explains: ‘Though both sides of the moon were bombarded by similarly large impactors, the near side hemisphere crust and upper mantle was hotter than that of the far side, resulting in the larger impact craters.’ [bold added]”

    I don’t believe this to be so. This ‘scenario’ doesn’t take into account the ‘accretion disc’ that must follow an ‘impact event’. The ‘assumption’ that “Though both sides of the moon were bombarded by similarly large impactors” is unjustified. The ‘near side’ regions would receive ‘heavier mass’ bombardment, whereas the ‘far side’ regions would receive ‘lighter mass’ bombardment. Work this out for yourself from the accretion disc that followed the ‘coming together’ of planets.

    “But…”

    Not my ‘remit/subject’

    Best regards, Ray.

  35. oldbrew says:

    Ray: to me ‘post’ means a blog post, responses to it are comments. I have a new blog post on the way.

    Re: Energy from ‘Earth rotation’ is supplying Earth’s Moon with energy to project ‘the Moon’ into a ‘higher orbit’.

    The precession of the equator period is known to be reducing. Here you can input a year e.g. 4000 years ago the period was ~600 years longer than today.
    http://www.iol.ie/~geniet/eng/moonfluct.htm

    Re: Did you understand my post?

    Yes, the NASA idea seems to be that the effect of the Earth on the Moon was to make the near side more sensitive to impact damage e.g. bigger craters.

    It’s perfectly fair to theorise on the matters you raise, especially when ‘official science’ (so to speak) appears to contradict itself to some extent. I don’t have any unique theory of my own to offer in this area.

  36. pg sharrow says:

    Gentlmen, a thing to consider is that most impactors to the far side were mainly debris with low realative speed while the large craters seen on the near side were caused by high speed errants, So not all craters were created under the same energy conditions…pg

  37. Bloke down the pub says:

    Super Moon on Monday night and a spate of earthquakes around the world, coincidence? By the way , if the planetoid that hit the early Earth was formed in the same orbit, would it not be composed of the same material, which would mean that the Moon having the same composition as the Earth is to be expected?

  38. suricat says:

    oldbrew says: November 11, 2016 at 10:59 am

    “Ray: to me ‘post’ means a blog post, responses to it are comments. I have a new blog post on the way.”

    ‘Whatever’! When ‘I’ post you ‘know’ its a ‘comment’! Let’s get one thing straight, ‘we all post’ on/to the ‘Internet’ when we ‘publicly make known’ our personal understanding of/for any ‘subject under discussion’. I’ve already ‘relinquished’ my ‘property of/to copyright’ both ‘here’ and ‘elsewhere’. Just don’t encroach upon any ‘patent’ I may own.😉

    If this forthcoming ‘blog post’ is related to the ‘comments’ I’ve made, I’ll look forward to its materialisation and final ‘posting’.😉

    Please consider my ‘posts’ as ‘comments’. There’s no way I could envisage the ‘time involved’ for the support of any ‘blog post’ that I, hypothetically, may’ve ‘inadvertently’ (unintentionally) made suggestion to because “I DON’T BLOGUE”. This ‘is’ a ‘talkshop’ after all is said and done. I’m only an ‘engineer’ that asks questions that ‘science’ doesn’t seem to answer. My ‘applied science’ doesn’t add up to the ‘science’ represented by many ‘blog postings’! Don’t take this as personal.🙂

    I’ll not ‘comment’ further to the rest of your ‘comment’, as it would seem that, my ‘further comment’ may ‘clash with a forthcoming’ “blog post”!

    Lips sealed, Ray.

  39. suricat says:

    pg sharrow says: November 11, 2016 at 2:46 pm

    I feel an obligation to respond to your comment, so I shall do so.

    “Gentlmen, a thing to consider is that most impactors to the far side were mainly debris with low realative speed while the large craters seen on the near side were caused by high speed errants, So not all craters were created under the same energy conditions…pg”

    I concur that “not all craters were created under the same energy conditions”, but the ‘energy of an impact’ is ‘proportionate to 1/2 the mass multiplied by the speed squared’ of the impactor and is dependant upon the ‘reference frame’ of the ‘observation’.

    I don’t accept the statement that “most impactors to the far side were mainly debris with low realative speed” because ‘massive entities in a higher orbit than Lunar’ require ‘more/greater speed’ to maintain that self same ‘higher orbit’. However, I can accept that the ‘mass’ of impacting objects to the far side of Lunar supplied less energy on impact due to their ‘low mass’ equivalence/value.

    “the large craters seen on the near side were caused by high speed errants”

    That depends on where they came from and their ‘velocity’, amongst other probabilities/possibilities. I think you should get the drift from this/my ‘response’ pg.😉

    Best regards, Ray.

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