Simulating the Age of the Moon

Like the author of a whodunit, researchers searching for the moon’s age have woven together clues from several stories to make an appealing one of their own. It may even end up being a best-seller, but like its predecessors it still resides in the category known as fiction.

For the segment of the scientific community that rejects God’s Word, the supposed 4.55 billion-year age of the earth was definitively established in 1956. However, the age of the moon is less clear to secular scientists. They have proposed a number of models to explain the moon’s origin, but most have fallen victim to insurmountable difficulties and left the “giant impact model” as the only story taken seriously by most secular scientists. Answers in Genesis astronomer Dr. Danny Faulkner explains, “For more than 30 years the theory of lunar origin is that the earth underwent a glancing collision from a Mars-sized body, and material from that collision plus some from the earth were expelled into orbit, and that material coalesced to form the moon.”

For four decades the commonly accepted secular theory of lunar origins has held that a Mars-sized object smashed into the early earth, melting its surface and blasting away debris that coalesced to form the moon. The latest twist to that model places that giant impact a just little later in earth’s history. Image by Dana Berry, via National Geographic.1

Dueling dates have, however, remained a problem. The moon’s age has remained the subject of debate due to discrepancies in the radiometric dates obtained on earth and moon rocks. “Geochemists get into a lot of fights with each other trying to determine what these ages mean,” says Seth Jacobson, lead author of the study published in Nature. “We were excited to find a ‘clock’ for the formation time of the Moon that didn’t rely on radiometric dating methods,” he says. “This correlation just jumped out of the simulations and held in each set of old simulations we looked at.”2

His team’s new “geologic clock” is based entirely on computer simulations, making it the first of its kind in that it completely avoids radiometric dating, or so the story goes. According to a press release from the Southwest Research Institute in Boulder, Colorado, the international team’s efforts represent an “independent and direct measurement of the age of the Moon”3 which will in the future “help guide which radioactive dating measurements are the most useful for this longstanding problem.”4

Simulated Truth

The moon’s age has remained the subject of debate due to discrepancies in the radiometric dates obtained on earth and moon rocks.

The planetary scientists base their conclusions on 259 computer simulations of moon-forming impacts, each of sufficient magnitude to melt the earth’s surface. The combinations that worked together best in the model put this moon-forming impact later than others have placed it, about 95 +/- 32 million years after the solar system—including earth—formed. This would make the moon younger than previously thought. (This date agrees with some radiometric dates and disagrees with others.)

The solar system as envisioned in the evolutionary nebular hypotheses was a violent collision-rich environment in which the earth gained mass to reach its present size from many of these collisions. Jacobson’s team maintains that each time an object struck the early earth, the elements like platinum and iridium—elements that are attracted to iron—melted and sank toward the earths core, explaining the apparent near absence of these elements in earth’s mantle today.

The researchers say their simulation accounts for the fact that the earth’s crust and moon rocks have the same proportions of elemental isotopes better than other iterations of the impact model. By placing the giant moon-forming impact as much as about 100 million years after the earth formed instead of right at the beginning, the earth wouldn’t have had to take on as much mass from additional collisions to reach its current size as in previous models. That, plus the idea that the new material sank deep into the earth, presumably explains how the surfaces of the moon and the earth could be so nearly identical at the atomic level.

In this new computer simulation, the earth remained molten longer than previously supposed. The researchers note that their conclusion that the earth took longer to finish forming will affect other conclusions about conditions on the early earth, including the question of how long earth had to wait before liquid water could exist on it. Their conclusions also rock the boat for other rocky planets like Venus and Mars. While earth, they conclude, took nearly 100 million years to form the moon and complete its own formation, Mars took only 2 to 5 million years after the solar system formed to form.

Model-Dependent Stories

Has this group of planetary scientists solved the mystery of the moon’s origin and age? Should the new model in the future be, as the researchers suggest, the standard by which other moon models should be judged? No. Actually, when it comes to ideas about or origins, the standard by which all models should be judged if they are to have a hope of representing reality is the eyewitness account provided by the Creator of the universe.

Answers in Genesis astronomer Dr. Danny Faulkner, commenting on the study, says:

Once again, this is a result that relies entirely on simulations and hence is very model dependent. Actually, it depends upon at least two models, one being the suite of models of formation of the solar system in general, and the other being the theory of the moon's peculiar origin. I say peculiar, because 40 years ago recognition of lunar characteristics eliminated the original three models of lunar origin and replaced it with the theory that the moon resulted from a late, glancing collision of a Mars-sized body with the earth. No other satellite in the solar system has such an origin scenario.

The authors ran more than 200 simulations of the two basic types of solar system formation models. In their simulations they computed the relative late-accreted mass as a function of time of last giant impact. In the words of the authors, this amounts to a clock. Knowing the late-accreted mass, one can read out the time of last giant impact. They argue that abundances of the highly siderophile elements in the earth's mantle produces an estimate of the amount of late-accreted mass, yielding the time of last giant impact, which presumably coincides with the impact that formed the moon.

Their result is 95 million years after condensation in the solar system, plus or minus 32 million years. This date is considerably later than previously thought. I would concede that within their model(s), this is an excellent example of a recurring complaint that I have, that many results are extremely model dependent. That is, if one changes the model, the result will change. Some people have criticized such comments of mine by arguing that all results are model dependent. However, I don't think that my critics understand my complaint. This is not a test of the models, though many people seem to think that it is. This is merely a constraint placed upon the models. Almost no one is bothering to ask if the models are even true. Nor is it clear to me that one can even test whether the models are true. The authors have used existing data to reinterpret within their model.  No predictions were made, so there is no way to confirm this by the normal means that we use in science.

Even the nebular hypothesis, the currently popular secular version of how the solar system came to be and the background in which this entire story of the moon’s origin is rooted, is at odds with the laws of physics. Dr. Faulkner explains:

There are many problems with this theory. There is no agreed-upon mechanism of how the tiny pieces of material began to stick together so that they eventually formed planetesimals. Planetesimals supposedly grew into planets, so the amalgamation of these tiny particles is the first step in forming planets. But without this step, there can be no planets. Also, angular momentum is not uniformly distributed in the solar system—the planets have almost all of it, but have very little of the mass.

Astronomers generally think that this theory is correct, because they need the solar system to form naturally somehow. So they assume that they just don't understand yet how some of these things happened.

I call this “evolution of the gaps.”

The researchers believe they have found a way to make the earth gain weight while safely tucking away elements inconvenient to the scheme, based on the presumed composition of earth’s mantle. Yet here lurk additional assumptions. Answers in Genesis geologist Andrew Snelling notes:

Their estimates for the composition of the mantle are simply that. Sure, we believe we have samples of the earth’s mantle from inclusions and chunks brought up in volcanic eruptions and in diamond pipes, but we have no way of knowing for sure from those tiny samples what the trace element composition of the whole mantle (1800 miles thick) is. Again they also turn to meteorites, assuming some of those are equivalent to rock from asteroids that are leftover primordial materials that might be the same as the earth’s mantle. But again these steps of logic are based on so many assumptions that all begin with seeking a naturalistic origin for the solar system, the earth and the moon.

Furthermore, the claim that this method completely avoids radiometric dating is rather short-sighted. Dr. Snelling points out:

The age they quote is not independent of radiometric dating, as the date for the formation of the solar system is derived from the radiometric dating of meteorites. Then these simulations assume that date to calculate how soon after that date the impact occurred to form the moon. So their “date” still is dependent on radiometric dating, in spite of their claim to the contrary.

Has this group even produced an “independent and direct measurement” of the moon’s age? The answer is still a resounding “no.” While their method may be independent of discordant radiometric dates, it is completely dependent on numerous unverifiable worldview-based assumptions about events and timetables of the solar system’s and earth’s origins. They have “measured” nothing. Furthermore, there is actually no way to “directly measure” the age of the moon when no scientist or temporal yardstick was around to observe the moon’s birth. The true age of the moon, like the true age of the earth, cannot be determined without reference to a reliable historical record. That record is available only from the eyewitness who has provided it, the Creator God of the Bible.

Any Story But God’s

The Bible’s history is certainly at odds with the nebular hypothesis account of the solar system’s birth and all secular versions on the moon’s origin including the latest, which consists only of assumptions piled atop assumptions. Being spit out of a computer doesn’t give these ideas special claim to reality as they are still based on the speculative worldview-based biblical-history-rejecting models on which the computer simulations were based. God our Creator made all things in just six days (Exodus 20:11, NKJV). He made the earth before He made the rest of the solar system. And He tells us in Genesis 1:14–16, NKJV that He made the sun, moon, and stars on the fourth day of Creation Week.

God waited until the fourth day of Creation Week to make the moon, and as far as we know our moon is unlike the moons of any other planet anywhere. Larger in proportion to its planet than other moons and possessing a very unusual orbit, the moon interacts with earth in unique ways that equip it to fulfill the purposes for which God made it. Read more about how the moon’s unique qualities affect life on earth and how even our scientific understanding of the universe in which we live really got its start from observations about the moon’s behavior in “A Perfect Partner.” The moon—so perfectly designed for the purposes God made it—should lead us not to speculate idly about how it could have been born through naturalistic processes but rather to glorify the God who made it.