Moon Origin Story Collapses
In a one-two punch, discoveries undermine the accepted story of the moon’s origin and its subsequent history.
Moon Origin Story Collapse
“Measurements of an element in Earth and Moon rocks have just disproved the leading hypotheses for the origin of the Moon.” That’s the first sentence in a post on Science Daily. Did a Mars-sized protoplanet impact the Earth, spinning off the moon? The problem, recognized for a long time but now reaching a crisis, is that isotopic similarities between the two bodies are too similar.
The probability that the impactor just happened to have the same isotopic signature as Earth was vanishingly small.
So the giant impact hypothesis had a major problem. It could match many physical characteristics of Earth-Moon system but not their geochemistry. The isotopic composition studies had created an “isotopic crisis” for the hypothesis.
The latest high-precision measurements still show too much similarity, especially for potassium isotopes. All theorists can do now is make the impact so violent, it would vaporize the Earth’s crust and mantle. That’s what Space.com‘s article says: “Moon’s Birth May Have Vaporized Most of Earth, Study Shows.” How likely is it that the remaining cloud would condense into the moon and the earth? How credible is it to assume this violent collision would result in a life-friendly planet with a moon just right to stabilize its orbit and tides?
Moon Development Story Collapse
Another story that has taken on the air of certainty is the so-called “Late Heavy Bombardment.” It even has an acronym: LHB. This story says that there was a period of violent impacts about 600 million years after the moon formed, 3.9 billion years ago. That’s what pockmarked the surface with its large impact basins.
Now, a paper in PNAS calls the story “illusory.” Data have been misinterpreted, say two scientists from UCLA.
The vast majority of evidence marshaled for the Late Heavy Bombardment comes from 40Ar/39Ar age spectra of Apollo samples, interpreted through “plateau” ages, which show an apparent cluster at ∼3.9 Ga [billion years]. Whether such data can be uniquely inverted to constrain impact histories in the Earth−Moon system has never been tested. We show that diffusive loss of 40Ar from a monotonically declining impactor flux coupled with the early and episodic nature of lunar crust formation tends to create clustered distributions of apparent 40Ar/39Ar ages at ca. 3.9 Ga. Instead, these 40Ar/39Ar data can be reconciled with a continuously decreasing bollide flux. Thus, impacts may have played a minimal role in terrestrial habitability, early Earth dynamics, and the formation of Hadean zircons.
It’s astonishing that such a long-standing, widely-accepted story has “never been tested” till now. As they indicate, collapse of the LHB not only affects theories of the moon’s surface; it ripples into issues like habitability, early Earth dynamics, and the formation of zircons used for dating the Earth.
Update 9/14/16: New Scientist says of the new paper, “A proposed period of intense asteroid and comet strikes on the inner solar system might be a fiction.” There was no Late Heavy Bombardment; instead, a continuous rain of impactors “more like a gentle massage.” The re-interpretation of impact evidence from Apollo samples has other implications. Evolutionists can no longer assume that an LHB “was a lucky break for Earth: that bombardment could have brought the first water and even prebiotic molecules to the infant planet.”
Update 9/14/16: Another earth-shattering announcement undercuts prior beliefs about the origin of the Earth. PhysOrg‘s headline reads, “New discovery shatters previous beliefs about Earth’s origin.” The analysis by James M. D. Day in Nature analyzes radioisotope products in chondrites and in the Earth. On one hand, the authors appear to confirm a chondrite origin for the Earth’s materials. But on the other hand, they invoke special conditions, turning supernovae into chefs without a brain:
Even so, Earth remains extraordinary. Enstatite chondrites and calcium–aluminium inclusions cannot have formed Earth; they might partly overlap isotopically with our planet, but they are either too depleted in key elements, including volatile elements, or too chemically reduced to explain the terrestrial composition. Conversely, carbonaceous and ordinary chondrites are too depleted in 142Nd (ref. 3). Moreover, chondrites and their components are unlikely to be representative of the materials that formed Earth because the materials that fed the formation of the inner planets no longer exist, having been processed within Mercury, Venus, Earth, the Moon or Mars. Instead, the formation of the Solar System might have been the result of ‘cosmic cookery’, in which stars and supernovae sprinkled variable isotopic compositions into the mix, akin to a chef seasoning a dish before serving it.
Day’s statements are based on two papers, Nature (Burkhardt et al.) about anomalysis neodynmium, and Nature (Bouvier and Boyet) claiming that Earth’s 142Nd shares a common origin with primitive solar system materials.
These are great lessons in philosophy of science. Theories are only tentative, not certain. Theories are subject to being overturned. But before falsification, they can survive long enough to take on a life of their own, affecting textbooks, animations, and even the popular culture. Yet they can be completely illusory!
It should have been evident that both theories were examples of “special pleading”—the invocation of ad hoc rescue devices to account for unexpected observations. It’s not proper in science to invoke one-off scenarios that can never be repeated, including the origin of the moon by an impact or a special period of high impact volumes. But the only other position is to suppose that the Earth and its moon always were (or were created the way they are). Since those options are philosophically distasteful, secular theorists would rather make up implausible stories that follow the evidence.