June 1, 2015 | David F. Coppedge

Moon Origin Models Require Cheating

You can’t get Earth’s moon from a planetary collision without quasi-miraculous tweaks to the models.

Science TV shows often make the moon’s formation look simple: a body flies into the Earth, breaks it up, and out of the pieces the Earth-moon system forms. This accident of nature was unique to the Earth, since it didn’t happen for the other three rocky planets. Viewers of the animations may not be aware that the simple picture is false. Specifically, the materials making up Earth and the moon are too similar to be explained by some third body, which likely would have been composed of different materials.

A recent paper in Nature by Israeli and French astrophysicists reveals what secular naturalists are up against trying to explain Earth’s moon by purely physical processes, without design.

The Earth–Moon composition similarity poses a major challenge to the standard model of the giant-impact scenario because it conflicts with the predominant derivation of the Moon composition from the mantle of the impacting planet. A wide range of alternative impact scenarios were therefore investigated. However, all such models suffer from potentially considerable difficulties and/or require fine-tuned conditions (see ref. 14 for a review).

Of course they’re not going to just give up on the problem. They run some new models to try to get the chance-impact scenario to work:

Our analysis of Solar-System-like planet formation scenarios potentially offers a solution to the major composition-similarity obstacle to the standard giant-impact scenario. We find that a significant fraction of all planetary impactors could have had compositions similar to the planets they struck, in contrast with the distinct compositions of different planets existing in the same planetary system.

Their job is to show that their “scenario” does not suffer from “considerable difficulties” or “require fine-tuned conditions” so that it becomes more plausible or likely, at least to the secular naturalist. But count up the special conditions their new model requires:

  • They overlook the problem of dust accretion that plagues every solar system model, and assume that particles will form planetesimals.  “Each of these planets accreted a large number of planetesimals during its evolution.”
  • They propose ad-hoc starting conditions. “Each simulation started from a disk of 85–90 planetary embryos and 1,000–2,000 planetesimals extending from 0.5 astronomical units (1 au is the Earth–Sun distance) to 4.5 au.”
  • They dodge the problem of the gas giants. “Jupiter and Saturn are fully formed and have different orbits and inclinations in different sets of simulations….”
  • They simplify the planets and impactors into tiny subsets of the particles so as to make computation easier. “We include only the 20 cases where both the impactor and planet are composed of at least 50 particles each, so as to have sufficient statistics.”

Initial runs show that the probability the impactor’s material would be similar to Earth’s is only 15%, so they tweak the model more to get the probabilities up:

  • “In 3 out of 20 cases the feeding zones contributing to the Moon and those contributing to the planet are consistent with being drawn from the same parent distribution. In other words, the Moon’s feeding zones, if derived solely from the impactor, are consistent with the Earth’s in 15% of the impacts.”
  • “The consistency further improves if we assume that a fraction of the proto-Earth was mixed into the Moon.”
  • “For the typical 20% mix of proto-Earth material with the impactor material forming the Moon (as found in simulations), 35% of cases are consistent with their feeding zones being drawn from the same parent distribution, and the success rate increases further for a higher mass contribution from the proto-Earth…. While this shows that the proto-Earth and the Moon-forming impactor may have had similar feeding zones, it does not yet quantitatively guarantee that the composition is as similar as that of the Earth–Moon system.”
  • “In 20% of the cases the impactors and planets have absolute offsets comparable or smaller than the measured absolute offset in the Earth–Moon system, that is, smaller than the 1σ limit estimated using the lunar samples (<15 p.p.m.). Taking into account the 1σ uncertainty calculated for the Δ17O [oxygen isotope differences] in the simulated systems, the fraction of consistent pairs can be as large as 40% of the whole sample.”
  • “This fraction becomes larger when partial mixing of Earth material is allowed, as observed in simulation data (it increases to 50% for a 20% (and to 55% for a 40%) contribution from the planet….”

So despite carefully-chosen initial conditions and assumptions, they still arrive at an 85% chance it wouldn’t work—until they factor in additional special conditions and assumptions. But then they mention other problems. “However, it is debatable whether even a similar impactor–planet composition could resolve the compositional similarity of silicon,” for instance.

At the very best, all they offer is a slightly-less-implausible scenario for the origin of the moon, if one is willing to accept their set of initial conditions and model tweaks.

We conclude that our findings can potentially resolve the apparent contrast between the observed similarity of the Earth and the Moon composition and its difference from that of other Solar System bodies. This primordial composition similarity solution may therefore remove the main obstacle to the standard giant-impact origin of the Moon, as well as ease some of the difficulties for the alternative giant-impact scenarios suggested in recent years.

Old-timers may remember how the three “standard” theories for the moon’s origin (co-accretion, spin-off and collision) were all falsified by Apollo data in the 1960s and 1970s. The currently-favored impact model, though more recent, seems destined for the same fate.

We ask the naturalists, are you any better off than you were 45 years ago? Secular naturalists scoff at the Bible’s eyewitness account of the moon’s origin by intelligent design. We have “science” now, they boast. You call this science? These “scenarios” pile on the improbabilities and assumptions beyond what rationality can bear. “We’ll figure it out some day,” they retort smugly, “without appealing to a god or to miracles.” Yet their chance hypothesis is tantamount to believing in miracles – multiplied miracles!

Seeing that everyone believes in miracles, we appeal to the secular naturalists to get off their pedestals and face reality. Be logical here: since everyone believes in miracles, and everyone believes in the supernatural (since philosophy, logic and rationality are not made of atoms), isn’t it preferable to believe in miracles of intelligent design rather than miracles of chance? What’s the point of that? You’re back to the “Stuff Happens Law.” And even then, the stuff you want to happen by chance won’t happen unless you interfere with nature by your own intelligently-designed computer models. Why, we plead, do you think you are better off than believing the Genesis account?

Secularists have been trying to figure this out since Laplace, who boasted to Napoleon, “I have no need of that [God] hypothesis.” Oh, yeah? Someone should have confronted his bluff and told the king, “Yes, but he has need of multiple miracles of chance! He has need of God—he just doesn’t want it, because he is too proud to admit it.” So here we are, over 200 years later, and mankind’s leading secularists still cannot figure it out without invoking probabilistic miracles. With all the observational data at their disposal Laplace could only dream of, they are worse off then he was! This is why their criticism of “God of the gaps” is so off-base. Science is not closing the gap. It’s been getting wider for two centuries. Claiming superiority by replacing God with “chance-of-the-gaps” is not a sign of progress.

The moon is a masterwork of design. It’s just the right size to aid life on Earth by circulating tides. It gives extra light on some nights. It stabilizes Earth’s axis. It appeals to the human heart, emotions, and sense of beauty. It challenges secular explanations. The only reason these astrophysicists, and so many others like them, keep throwing the dice and trying the chance hypothesis is that they do not wish to include God in their thinking. Despite breathing the air of a perfectly-habitable world as they use their sophisticated brains, they will not believe the Word of the One who was there at the beginning, who knows everything and communicated His truth to the world. In His mercy, our Creator gives man a choice to believe or not believe Him. Those who disbelieve are doomed to wallow in folly, trying to convince themselves and everyone else that the Idol of Stuff Happens is better. It’s lunacy.


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  • joelazcr says:

    It turns out that our moon is 1/400th the size of the sun. But the sun is 400 times farther away from earth than the moon. So when the moon comes between the sun and the earth a small portion of earth experiences a total solar eclipse, meaning the sun is fully blocked out by the moon.

    When a total solar eclipse occurs, the sun is fully blocked out by the moon darkening the earth and providing a unique glimpse of the sun’s atmosphere or corona. Normally the sun’s corona is overwhelmed by the sun’s brightness, but in an eclipse the moon so completely shuts out the sun that the corona shines brightly for a few minutes. It is then that scientists can measure the light spectrum of the corona which reveals what is burning inside the sun. Otherwise we would not be able to measure the elemental makeup of the sun. So the fact that earth experiences a total eclipse of the sun makes our planet unique in the solar system with respect to what we can learn about what goes on in the sun’s interior.

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