Study: Early Earth gobbled up mini-planets to grow

The volatile processes that shaped the Earth

Oxford University scientists have shed new light on how the Earth was first formed.

Based on observations of newly-forming stars, scientists know that the solar system began as a disc of dust and gas surrounding the centrally-growing sun. The gas condensed to solids which accumulated into larger rocky bodies like asteroids and mini-planets. Over a period of 100 million years these mini-planets collided with one another and gradually accumulated into the planets we see today, including the Earth.

This is an image illustrating the late-stage building blocks of planetary formation (planetessimals and proto-planets) and the extensive volatile degassing that took place. CREDIT Ashley Norris, Oxford University

Although it is widely understood that Earth was formed gradually, from much smaller bodies, many of the processes involved in shaping our growing planet are less clear. In a new study featured on the cover of the latest edition of Nature, researchers from the University of Oxford’s Department of Earth Sciences untangle some of these processes, revealing that the mini-planets added to Earth had previously undergone melting and evaporation. They also address another scientific conundrum: the Earth’s depletion in many economically important chemical elements.

It is well known that the Earth is strongly depleted, relative to the solar system as a whole, in those elements which condensed from the early gas disc at temperatures less than 1000°C (for example, lead, zinc, copper, silver, bismuth, and tin). The conventional explanation is that the Earth grew without these volatile elements and small amounts of an asteroidal-type body were added later. This idea cannot, however, explain the “over abundance” of several other elements – notably, indium, which is now used in semiconductor technologies, as well as TV and computer screens.

Postgraduate student Ashley Norris and Bernard Wood, Professor of Mineralogy at Oxford’s Department of Earth Sciences, set out to uncover the reasons behind the pattern of depletion of these volatile elements on Earth and for the “overabundance” of indium. They constructed a furnace in which they controlled the temperature and atmosphere to simulate the low oxidation state of the very early Earth and planetesimals. In a particular series of experiments they melted rocks at 1300°C in oxygen-poor conditions and determined how the different volatile elements were evaporated from the molten lava.

During the experiments each of the elements of interest evaporated by different amounts. The lava samples were then rapidly cooled and the patterns of element loss determined by chemical analysis. The analyses revealed that the relative losses (volatilities) measured in the molten lava experiments agree very closely with the pattern of depletion observed in the Earth. In particular, indium volatility agrees exactly with its observed abundance in the Earth – its abundance, turns out not to be an anomaly.

Professor Bernard Wood said: ‘Our experiments indicate that the pattern of volatile element depletion in the Earth was established by reaction between molten rock and an oxygen-poor atmosphere. These reactions may have occurred on the early-formed planetesimals which were accreted to Earth or possibly during the giant impact which formed the moon and which is believed to have caused large-scale melting of our planet.’

Having focused their original experiments on 13 key elements, the team are in the process of looking at how other elements, such as chlorine and iodine, behave under the same conditions.

Ashley Norris said: ‘Our work shows that interpretation of volatile depletion patterns in the terrestrial planets needs to focus on experimental measurement of element volatillities.’


Notes to editors:

The full citation for the paper is ‘Earth’s volatile contents established by melting and vaporisation’ and features in the September 28 2017 edition of Nature.

This web link will be active from 1:00 PM EST / 6:00 pm BST on Wednesday 27 September: DOI – 10.1038/nature23645


86 thoughts on “Study: Early Earth gobbled up mini-planets to grow

    • Realizing the we have absolutely no extraterrestrial rocks that haven’t passed through Earth’s atmosphere (except for the few moon regolith specimens) where did they obtain their samples of early protoplanets?
      Was this simply an experiment to melt manmade specimens?

    • I assume that they started with the observed abundances of elements in the solar system, galaxy or detectable universe.

      • That is correct. They reconstructed, for example, the chemical balances of chondrite meteorites thought to come from the asteroid belt. Their results not only explain relative anundance compared to the solar system as a whole, they explain almost exactly relative isotope abundances, for example magnesium. I suspect it was more the moon formation impact than a series of planetesmals, because as Earth grew their relative impact diminishes.

      • The Indium obviously survives by design. As it is used in Computer Screen and Television screens…
        World forms at 10…News at 11…

        Without all the Indium, we wouldn’t hve been able to broadcast (or webcast) the event as noone would have been able to tune in

      • “Over 90% of the Earth’s crust is composed of silicate minerals, making silicon the second most abundant element in the Earth’s crust (about 28% by mass) after oxygen.”

      • “Over 90% of the Earth’s crust is composed of silicate minerals, making silicon the second most abundant element in the Earth’s crust (about 28% by mass) after oxygen.”

      • Ferd,

        I’d have thought it fairly obvious why silicon is abundant in earth’s crust. For starters, it’s the seventh most common element in the universe. Why earth’s crust is enriched in it so that it’s the second most abundant there, is because heavier elements, eg iron and nickel, settled into earth’s mantle and core. Lighter silicon floats on the mantle.

        The mantle is composed of rocks with higher concentrations of mafic minerals (containing iron and magnesium) and lower of the felsic minerals (aluminum and silica) than rocks of the crust. Silicon is a little denser than magnesium, but the latter mixes better with iron.

  1. I presume the hot planetesimals also had a low enough escape velocity that the evaporated elements were driven off.

    • It’s not merely planetary mass which holds onto its atmosphere. What strips away the atmosphere is solar wind. The planets magnetic fields will also affect the strength of the impingement of the solar wind. Relative proximity to the host star is also a factor.

  2. I find studies like this to be interesting, really. The problem I have with them is that they are very much like “modeling.” They made a decision as to what they “thought” was the process – basic programming assumptions, so to speak – have run their experiments that were basically designed to prove what they thought, and since their results, oddly, matched their expectations, have duly determined that their original hypothesis has somehow been vindicated and have declared it just short of a scientific fact. This really has been the problem with science overall.

    • TO, I see this study differently and very much in line with the essence of the scientific method. (See chapter 1 of the The Arts of Truth for a philosophical discussion of that and more).The authors of this neat paper start from an observation, that Earth is short elements in greater abundance elsewhere in the solar system (based, for example, on meteorites). They formulate a hypothesis as to why based on the planetesmal accretion theory of rocky planet formation. (One of the three astronomical indicia of a true planet is that it eventually sweeps the space around its orbit free of everything else. The moon has lots of very old craters, and almost no ‘new’ craters (at least on the visible side) because it is gravitationally locked to Earth. They artificially create lab chemistries representing elsewhere, heat those ‘planetesmal rocks’ up in a furnace as collisions with an accreting Earth would, cool them down, and find the chemistry of ‘elsewhere’ has been converted to the chemistry of Earth’s elemental composition. That is pretty classic science, experimental confirmation of a hypothesis. A+ and Ph.D summa cum laude. IMO.

      • ristvan:

        ” … heat those ‘planetesmal rocks’ up in a furnace as collisions with an accreting Earth would, cool them down, and find the chemistry of ‘elsewhere’ has been converted to the chemistry of Earth’s elemental composition.”

        With regard to the cooling aspect, i.e., “[t]he lava samples were then rapidly cooled and the patterns of element loss determined by chemical analysis.”, does it matter whether or not the original cooling was “rapid” to the results of the experiment? E.g., would there be different “patterns of element loss” were the cooling gradual?

        If it does matter, by what evidence did the researchers assume there was “rapid cooling” and how is that defined? What brought the rapid cooling about?

      • I agree. This looks like good science to me. It will become better science when other researchers perform the same experiments and either confirm the results or not. Confidence arises not just from an experiment that jives with theory, but with independent replication of such experiments.

      • Sy,

        In a controlled (low oxygen) furnace, rapid cooling is may be necessary to make sure the evaporated material stays separate(?)

        Slow cooling mightwould give differing results that don’t match the assumed indium (or other element) parameters.

        Starting with higher or lower element percentages and running the same furnace experiment would likely get close to the same measured leftover. But a more rapid heating or cooling, or longer overall burn, would likely change remaining element leftover significantly.

        Lots of assumptions on variables, but she had to start somewhere. As she says, needs … more experimental measure

      • Don:

        “Lots of assumptions on variables, but she had to start somewhere. As she says, needs … more experimental measure”

        I appreciate your response. That clarifies things to some degree.

      • “One of the three astronomical indicia of a true planet is that it eventually sweeps the space around its orbit free of everything else.” – ristvan

        Then we don’t have any true planets in the solar system. There are planet-crossing asteroids, Jovian Trojans, comets — the planets and moons are still collecting craters. (Gas giants don’t crater, but we’ve seen comets slam into Jupiter and leave nasty spots on the atmosphere that lasted some while.) And how many asteroids have been buzzing past Earth now that we have good enough sensors to count?

        There’s no place inside the orbital plane of the solar system that is truly clean. That criterion was invented so they could throw Pluto out of the club; and depending on your standards of cleanliness, you could throw all the other planets out too.

    • If they’d only replace the word “know” (eg line 2) with “believe” I’d be happy enough . . .. but to know . . . mmmm . . bit reckless! They used to “know” that a single “big bang” was the start of everything, even though it made very little sense to anyone who sat down and gave it a little bit of thought . . . Now we’ve got the possibility of an infinite number of big bangs . . . and so it goes . . . . “know”? . . I don’t think so. . .

      • Jim,

        A Big Bang at the start of our present universe isn’t shown false by the possibility of multiple Big Bangs in the history of our universe and hypothesized others.

        Science is never settled.

        There is always more to attempt to understand, and the more that is well explained, the more there is that needs further investigation. Send money!

      • Epistomology 101: If it walks like a duck and quacks like a duck, it is a duck, especially if it also looks, swims, dives and flies like a duck.

  3. scientists know… are confident that the solar system began as a disc of dust and gas surrounding the centrally-growing sun

    Scientists are prone to inference that corresponds with their faith and indulgence in assumptions/assertions that force means to meet spiritual but more often secular ends. The real scientists will limit their logical exploration to the scientific domain which is uncomfortably limited in both space, near and far, and time, past, present, and future.

    • Scientists do not “know” this. They make observations on nearby forming systems and other local solar system characteristics. They then apply first principle physics to make presumptions about similar cognate systems, such as our own. They then create models to predict the behavior of their presumptions and correlate them back to observations for verification.
      No, we cannot “know” these things to be certain, but I have much better confidence in my astrophysics models than any climate model.

    • Many protoplanetary disks have been observed around young stars of solar mass. There is every reason to suppose that the solar system formed in the same way. Indeed all available evidence supports that conclusion, and none opposes it.

      Science has nothing at all to do with faith and everything to do with observation. The only “faith” involved is the reasonable assumption that the universe behaved some five billion years ago as it does now.

      • Agree. There is such a thing as too much skepticism based on the travesty of ‘climate science’. A lot of the rest of the hard true ‘science’ (mathematics, physics, chemistry, astronomy, biology, molecular biology, geology, materials, computer science, … –except in some trendy portions of evidence based medicine like carbs v. fats and proteins, or gluten free) is very solid. GPS works. We find oil. We have plastics. Bridges do not fall down. Electric motors and semiconductors are ubiquitous. Smart phones are, well, smart. Very different than the ‘social sciences’ or ‘climate science’ which proves to be social engineering in disguise.

      • We assume that both the mechanics and fitness function have not evolved, and that they are, in fact, uniform and invariant, then apply contemporary principles of secular faith that give meaning to inference drawn beyond a limited frame of reference in time and space. It’s an interesting exercise that creates an illusion of productivity, knowledge, and skill.

        That said, the model of Earth’s climate, notably an observable phenomenon in a limited frame of reference, will improve but remain forever constrained to the scientific domain, where accuracy is inversely proportional to the product of time and space offsets from an established frame of reference. This is particularly true for purposes of designing a risk management regime, despite our progressive lack of skill to know and predict even closely coupled time and space. For example, we know that human evolution begins at conception and ends with death, but we are limited to perceive and predict each event.

      • “Science has nothing at all to do with faith and everything to do with observation.”

        Indeed. There’s absolutely no more reason to believe by faith in gods, angels, demons and flying sky dragons!

        We have String Theory now.

      • Sy,

        String theory isn’t faith-based, either. Well may lead nowhere, but it is science, in the same way that Newtonian mechanics was and is science. It has been partially confirmed and partially shown, well, partial.

      • “String theory isn’t faith-based, either. Well may lead nowhere…It has been partially confirmed and partially shown, well, partial.”

        My mistake.

      • Willy:

        “Scientific theories are testable and falsifiable. Religious beliefs, not so much.”


        “String theory isn’t faith-based, either. Well may lead nowhere…It has been partially confirmed and partially shown, well, partial.”

      • NN, no, some of us do NOT make that fallacious assumption. See The Arts of Truth discussion of the intelligent designer classic example, the eye. The ID fallacy is exactly freezingnthen projecting the evolutionary fitness function. The most interesting part is that the eye evvolved separately in three different ways: insect compound (best for them), vertibrate (not so good for macular degeneration), and cephalopod (most rational and best for low light them. Nature is grand.

      • sy computing September 28, 2017 at 3:57 pm

        Yes, Newtonian mechanics was repeatedly confirmed until its limitations were discovered, at which time, it needed to amended by relativity theory. That’s how science works.

        String theory will be confirmed in whole or part, or shown false by experiment and further observation. It will be either confirmed and improved upon, or discarded, as have been other scientific theories and hypotheses.

      • “Epistomology 101: If it walks like a duck and quacks like a duck, it is a duck, especially if it also looks, swims, dives and flies like a duck.”

        Except when it’s not a duck at all:

        “Yes, Newtonian mechanics was repeatedly confirmed until its limitations were discovered, at which time, it needed to amended by relativity theory. That’s how science works.”

        Anyway…moving on…

      • Ristvan, the eye is a good example against ID (or at least the intelligence of the “designer”). The “intelligent designer” built it backwards with the photosensitive cells behind the translucent membranes of the retina. Any second rate optical designer today can do much better. There are numerous physiological absurdities in the human body that more certainly would not have been “designed” that way. All evidence demonstrates that the oddities developed in that manner because they were morphed from existing configurations that may have followed a more efficient pathway in previous ancestors.

      • Scientist,

        ID is just old creationist vinegar in new, supposedly non-religious bottles, as was shown to general hilarity in the Dover, PA trial, as if further proof were needed.

        Most of living things are idiotically designed, for the reason you state. The human body indeed shows many instances of idiotic design. That’s just one reason why creationists blaspheme God, since if He designed organisms including humans, then far from being omnipotent, He’s stupid.

        The fact of Idiotic Design alone shows creationism false, as if more evidence were required.

      • “Most of living things are idiotically designed, for the reason you state. The human body indeed shows many instances of idiotic design. That’s just one reason why creationists blaspheme God, since if He designed organisms including humans, then far from being omnipotent, He’s stupid.”

        How about if God did it this way: creating the basic building blocks of life and then allowing evolution to proceed without interference to any and all ends. You could still have a Creator, and evolution, too, even stupid evolution.

        I read a good article not long ago describing some things in nature that seem to be impossible to exist without Devine Intervention. I’ll see If I can dig it up. It has very good questions which I would love for our experts here to discuss.

        As for me, I don’t know one way or the other, how our universe started out, whether it was Divine Intervention or just a process of nature. I’m still looking for answers.


        Some excerpts:

        “Chirality is a major issue because amino acids that make up proteins come in right- and left-handed versions. Life on Earth is made up of only left-handed amino acids. Sugars used by the proteins are limited to the right-handed direction and so is DNA. The wrong chirality just will not work to support life so how could nature sort out the chirality?”

        “What is especially interesting is that Berman raises questions about the ability of evolution to explain on a chance basis some of the designs we see in living things. He uses the example of the airfoil that all flying forms of life have. The upper surface is convex using the Bernoulli effect to produce lift. The earliest bird and the flying reptiles all had a wing design that works. Trial and error would not work well to explain how the wing design would come into existence by chance. Berman points out that “some 400,000 cells would all have to simultaneously mutate in just the right way to create a properly shaped wing. This defies an evolutionary hypothesis.”

        “Berman quotes Francis Crick, the co-discoverer of DNA’s double helix as saying that the origin of life is “almost a miracle, so many are the conditions which would have had to have been satisfied to get it going.” We don’t invent a “god” to explain these things, but we would point to these things as one more evidence that there is a God and that blind chance is not a good designer of the complexity we see in the world around us.”

        end excerpts

        Would love to hear the experts expound on these three points.

  4. There is no depletion or surplus of any elements on Earth, all the missing data is hiding in places they have not got to yet.

    • Disagree. Using hyperbolic creaming curve analysis by petroleum basin, it can be rigorously shown that about 3/4 of all the petroleum ever to be discovered already has been. That includes source rock shale. Using TRR analysis (independent of crude oil prices) it can be shown what remains to be physically extracted from the known discoveries. Using the previous extractions, the remaining extractable crude (at any price) can be estimated.
      There is no ‘missing data’ since price is not in any of these geophysical estimates. Wrote 2/3 of one ebook, 1/3 of a second, and a grossly simplified part of half of a third ebook on these basic facts. You might wish to educate yourself. Not Club of Rome omputer model nonsense, just the hard geophysics of crude oil. (Note, I make no such similar claims for natural gas for equally persuasive reasons: Oil v. Gas windows, delta TRR, relative window shale extents, and such. For example, deeper means hotter. Hotter means more gas rather than oil window. Lots of very deep kerogen shales like the Marcellus, with no catagenic oil but lots of catagenic natural gas left.)

  5. This is from the “every thing old is new again”: this idea was in a book on astronomy that I read in the 70s.

    • The difference is that now it’s not “just” an hypothesis, since we have seen real protoplanetary disks around young, sun-like stars.

      • We have inferred their existence and character from signals that are assumed to be accurate, unadulterated reflections of their emitters, which are notably sampled below the Nyquist Rate, in a frame of reference that is progressively distant from its source. It’s not science, but rather philosophy, and perhaps faith, where replication of the original phenomenon in not forthcoming and may, in fact, be impossible (e.g. if time is a progressive measure of kinetic energy).

      • nn,

        We haven’t just inferred the existence of protoplanetary disks. We have directly observed them in great detail with Hubble Space Telescope, the Atacama Large Millimeter Array and other instruments.

        ALMA image of that around HL Tauri:

      • Jim,

        The observations are of protoplanetary disks. Dunno what IYO constitutes “knowing”, but observing disks of matter around a young star which display all the characteristics of hypothesized protoplanetary disks would normally be considered observing such disks. Hence, we know that the disks of matter just like hypothesized protoplanetary disks exist.

        Thus, epistomologically, we know that they exist. Do you think we need to go to HL Tauri in order to confirm these observations?

  6. If 2 balls of rock travelling at speed and collide will they stick together or smash apart? My physics master will hypothesize that they smash apart and isn’t that what happened at the asteroid belt?

    • The asteroid belt is thought to have remained as it is, from gravitational disruption by Jupiter. If Jupiter was farther away, it is likely that the asteroids would have accreted to form another planet.

      • Some of them got close, ie the dwarf planet Ceres and asteroid Vesta, which would have been one except for a collision after it formed.

        But Jupiter’s gravity kept a larger planet from forming, and ejected from the Belt much of the material that would have gone into making such a planet. Subsequently of course, there were collisions, too. In some of them, the asteroids stuck together and in others were broken apart.

        A growing planetesimal with much of the mass of Earth, however, would absorb smaller bodies.

    • It is not whether they smash apart, but whether the fragments have a velocity greater than the escape speed of the total mass.

  7. See! Even before we existed humans were greedy and evil. Eeviiillll, I tells ya!!!!! I always thought this theory had been put forward a long time ago and observations of activity in the Asteroid Belt led people to accept that something much like it is how planets formed, ya know, accretion of material as it “flowed” in the same general directions in orbital bands around Sol? Appears to be a pile-O-money being spent for no appreciable purpose.

  8. It is good to see an empirical observational experiment performed.

    Now why are there no such experiments dealing with the GHE in various mixes of atmosphere (say CO2 200 ppm 300 ppm 400 ppm 500 ppm 600 ppm etc, in dry air and air containing various concentrations of water vapour using a BB radiator at 288K), and LWIR over large volumes of water (utilising some of the large test tanks)

    Should be quite easy to perform some realistic experiments that would shed further light on how things might work.

    • Much easier and lucrative just to estimate, assume, “model”, infill (ie, invent “data”) and assert than to conduct actual experiments, which might produce unwelcome results and derail the gravy train.

    • Lab simulation of the atmosphere can give you the no-feedback sensitivity of 1.1 C per 2x CO2. This is not really in dispute. Both skeptics and alarmists generally accept this value. The debate is on the feedback amplification or reduction of warming, whether positive or negative and how large. This cannot be easily simulated in the lab as it involves ocean-atmosphere interaction, evaporation, precipitation, convection, cloud formation, etc.

  9. ” … the Earth is strongly depleted, relative to the solar system as a whole, in those elements which condensed from the early gas disc at temperatures less than 1000°C (for example, lead, zinc, copper, silver, bismuth, and tin).”…

    What does this mean exactly. You know this is in space. Sure, there is a brand new Sun about 1 AU away blasting these bits with solar radiation (and some at higher energies in the new Sun) but this is also in space.

    How do metals “condense” from a gas in space only when temps are less than 1000C? Why are these elements highlighted?

    I just want to know what the real physics explanation is here. What really happens.

    Gravity collects molecules together but why call it a gas, etc.?

    • Melting Points of Various Metal Elements and Alloys

      Melting Points
      Metal Fahrenheit (f) Celsius (c)

      Lead 327 163
      Zinc 787 419
      Magnesium 1204 651
      Aluminum 1218 659
      Bronze 1675 913
      Brass 1700 927
      Silver 1761 951
      Gold 1945 1063
      Copper 1981 1083
      Cast Iron 2200 1204
      Steel 2500 1371
      Nickel 2646 1452
      Wrought Iron 2700 1482
      Tungsten 6150 3399

  10. its fun watching people struggle with whether this is “science” or not,
    or whether it is “known” or not.

    That’s part of the problem with the naive popperism that skeptics have picked up, but never actually
    tested. That’s right your popperist notions are largely blindly accepted. popper dogma.

    The question of DEMARCATION, what is science and what is not science, is an UNSETTLED philosophical

    Hint: your decision to accept one side of an unsettled philosophical question, doesnt help you decide
    scientific question about climate.

    put another way: Philosophy is not evidence used to make science. Philosophy cannot settle science or even tip a scientific scale.

    • Obviously as most of what science has studied or concluded is really never truly settled. “Settled Science” is just another oxymoron.

    • “science is defined as that which confirms my initial intuition & provides the logic to move in the direction that I want” – 97% of climate scientists

    • Mosher,

      Since you have an undergrad degree in English and Philosophy, maybe you can teach us naive practitioners of the scientific method what science really is.

      To be specific, if the scientific method is not observing a natural phenomenon, forming an hypothesis which might explain it, testing that guess by making predictions upon its basis, capable of being shown false, then what is the scientific method and what is science?

      It most assuredly is not “climate science” as practiced.

      • “Climate scientists” and their running dogs won’t be satisfied until they’ve corrupted not just climatology but all of science, turning the endeavor into whatever they say it is, as infallible priests.

  11. I’ve been struggling with this “article” trying to figure out what it could possibly be about. As I am approaching 80,was never all that smart to begin with, and I’m getting even dumber with time, that’s taken me a while. I eventually concluded that we’re looking at a press release written — as seems traditional — by a “communications specialist” who has little or no understanding of the subject matter.

    Anyway, I finally got the bright idea of digging up the abstract presumably written by the folks who actually did the study. It’s at The paper itself is paywalled and I’m not curious enough to look for an unpaywalled version elsewhere.

    I’ll try to insert the abstract as a blockquote

    The silicate Earth is strongly depleted in moderately volatile elements (such as lead, zinc, indium and alkali elements) relative to CI chondrites, the meteorites that compositionally most closely resemble the Sun1. This depletion may be explained qualitatively by accretion of 10 to 20 per cent of a volatile-rich body to a reduced volatile-free proto-Earth2, 3, followed by partial extraction of some elements to the core1. However, there are several unanswered questions regarding the sources of Earth’s volatiles4, 5, notably the overabundance of indium in the silicate Earth. Here we examine the melting processes that occurred during accretion on Earth and precursor bodies and report vaporization experiments under conditions of fixed temperature and oxygen fugacity. We find that the pattern of volatile element depletion in the silicate Earth is consistent with partial melting and vaporization rather than with simple accretion of a volatile-rich chondrite-like body. We argue that melting and vaporization on precursor bodies and possibly during the giant Moon-forming impact6, 7, 8 were responsible for establishing the observed abundances of moderately volatile elements in Earth.

    So, probably what it says is that the relative abundance of elements in the outer layers of the Earth looks to be consistent with the early Earth having been warmed by an unspecified mechanism to around 1300C and then having cooled. It does not seem to address where the missing volatile elements went to.

  12. I apologise to sy computing, rocketscientist, jim hogg and a couple of others for burdening them with left-wing support, but I think that their points are valid. The experiment may have been well-constructed, but it relies on certain assumptions about the early Earth and its formation processes that are highly dubious and may well turn out to be wrong. Tom O spelt it out pretty well.

    Does anyone remember a time when all dinosaurs were ‘known’ to be cold-blooded reptilians? We’re not so sure now. There are plenty of other examples of unchallengeable scientific ‘wisdom’ that were subsequently demonstrated to be wrong. In many cases the ground-breaking individuals were branded as heretics and their ultimate victories occurred long after they were safely (and ignominiously) dead.

    Willy Pete
    “The only ‘faith’ involved is the reasonable assumption that the universe behaved some five billion years ago as it does now.”

    Similarly, it is reasonable to assume that the Earth’s climate behaved some 50,000 years ago as it does now. If this is unreasonable, then the assumption about the universe’s behaviour (at least, in our corner of it) is about five orders of magnitude worse. If you wish to argue the ‘evidence,’ you will find that the evidence is very arguable.

    • Lefty,

      That dinosaurs were cold-blooded was never dogma, such as you find in claims of settled science for climate. In the 1860s, Huxley proposed that birds were dinosaurs. When evidence emerged in the 1960s for warm-bloodedness, its advocates weren’t subjected to attacks such as climate skeptics have endured. You’d have a better case for entrenched geologists’ attitude towards advocates of megafloods and “continental drift”.

      Earth’s climate did behave 50,000 years ago as it does now. Ice ages come and go naturally, based largely upon orbital mechanical and rotational cycles still operating today.

      However radioactive decay is a lot easier to understand than is a complex situation like climate on earth.

    • And what about those 450000000 year old bones with flesh on them. Sorry but I have less faith in so called science than most here. I’ve seen so much Scientific BS over the decades, most of which is science fiction. I immerse myself in Chemistry and mathematics. True sciences that are quantifiable.

    • Joe,

      As with the other planets, Earth’s rotation is a vestige of the original angular momentum of the protoplanetary disk, that cloud of dust, rocks and gas that coalesced to form the solar system. This primordial cloud was composed of hydrogen and helium produced in the Big Bang, plus heavier elements ejected by supernovae. As this interstellar dust is heterogeneous, any asymmetry during gravitational accretion resulted in the angular momentum of the eventual planet.

      However, if the giant-impact hypothesis for the origin of the Moon is correct, this primordial rotation rate would have been reset by the “Theia” collision ~4.5 billion years ago. Regardless of the speed and tilt of Earth’s rotation before the impact, it would have experienced a day some five hours long after the collision. Tidal effects would then have slowed this rate to its modern value. But this applies to speed of rotation, not direction.

      • Helium (He) is an interesting element to think about in this context (but not mentioned in the summary of the paper). It is most volatile of all. And least reactive of all, therefore never bonded with any other element and therefore never “tied down” by anything else..

        That we still have any He on Earth, recoverable in deep mines, is NOT a mystery; it is easy to understand how some was trapped within the rock. And presumably there was billions times more He in the original gas cloud that formed the planets, than there is today; so we have only a very small fraction left. But what I wonder is if the earth’s core is still releasing some He into the mantel, or if the mantel is still releasing He into the crust.

      • When a large unstable nuclei releases a beta particle when it decays, this beta particle will acquire two electrons and become a helium atom. So the source of He from the Earth isn’t all coming from the remains from the formation of the planet.

  13. I found this to be pretty interesting.

    From Astronomy magazine, Oct. 2017, page 19: All stars may be born in pairs.

    “The Perseus molecular cloud may be revealing a strange truth about the universe: Most stars, if not all, are born in pairs.

    I do love astronomy! :)

  14. Is Earth really a planet, or simply a collection of debris?

    The well known astronomer Isaac Asimov described our solar system as consisting of “four planets, plus debris.” The four planets being the gas giants.

    Certainly, our solar system would not miss the four rocky worlds. After all Jupiter itself has more mass than all the other 7 planets combined. Earth is just a pimple, albeit an important one for us.

    Interestingly, our current definition of planet (which has rendered Pluto into a dwarf planet), has more to do with position of the solar body than anything else. If Earth was out in the back reaches of the solar system it is likely that it would no longer be regarded as a planet since it is unlikely that it would have cleared its orbit, or in the unlikely event that it had, it would be quite different to the Earth we see today.

    Personally, I am unsure whether our current definition of planet is particularly useful, and I doubt that the definition would have been changed to exclude Pluto and to downgrade it to a dwarf planet had we seen the results of the New Horizons mission which has shown Pluto to be a very interesting world.

  15. So you have concluded how the entire Earth was put together from 1 sample collected from where?… ur back yard. Sounds about right.

  16. No doubt some very green media will pick on this excellent work and then declare: “Further proof that human-kind (mostly white men) have depleted the earth of essential elements”

  17. I don’t think so. All speculations about the early history of the Solar System suffer from the same fatal flaws: too much assumption, too much reliance on what supposedly happened, and ignorance of certain essential constraints.

    Taking the last consideration first, Henri Poincare determined in the late 19th century that any spinning object must flatten out and eject equatorial portions of itself until it slows down to below the critical rotation for fission, which depends only on the object’s density. Given the density of the Proto-Sun, this should have happened several times, each event producing a protoplanet, which would subsequently spiral slowly outward as rotational inertia was transferred to it from Proto-Sun. This accounts for both the planets and for the odd distribution of angular momentum in the Solar System, with most of the latter resident in the various planets and very little in Sun.

    These protoplanets, gradually moving outward through the Solar Nebula, would also have undergone Poincare fission, producing their assorted natural satellites, which wouldn’t have had sufficient rotational energy to undergo fission, but would have remained spin-orbit-coupled to their primaries, the fission debris from their creation falling back into both the protoplanet and the satellites, accounting more plausibly for the cratered nature of their near sides than a postulated “Great Bombardment” that somehow filled the young Solar System with flying debris.

    This scenario also accounts well for the presence of heavier gases in the atmospheres of the outer planets (early-out planets would have preferentially gleaned the heavier gases, leaving lighter ones to accumulate on later-out planets) and for the logarithmic distribution of planetary distances from Sun.

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