A match made in the heavens
Let’s say you have a rock in the solar system. And it’s not any boring, settled-into-a-routine kind of rock — but a young, vivacious rock. The universe is at its metaphorical feet. This rock has been hanging out with its family between Mercury and the Sun for the last few millennia when suddenly it’s flung millions of miles from its comfort zone. By some random chance, it comes close enough to Earth to be captured by the planet’s gravity. And with that, the wayfaring rock becomes Luna, Earth’s moon — guide to lovers, inspirer of bedtime stories, and subject of the life’s work of Emeritus Professor of Geology Bob Malcuit.
When he retired from teaching at Denison in 1999, Malcuit didn’t know where the moon came from. He just had his “capture theory” on how it came to be Luna, having worked on this puzzle on and off since his graduate school days in the early ’70s. But as confident as was about that theory, he remained in a significantly small minority of scientists. That is, until recently, when geological findings in Australia gave new strength to his understanding.
The theory that has managed to reign supreme for the past 30 years is the giant impact model. Around 4 billion years ago, its supporters claim, a Mars-sized object smashed into the Earth and the Moon formed from the resulting debris. With every point from the giant impact camp, however, Malcuit has lobbed back a counterpoint with the argument that Earth drew the moon during its cyclical trajectory through the solar system, and securely captured it in orbit on its 18th pass. What’s more, he argues, that event created the geologic and atmospheric conditions that made life on Earth possible.
As detailed in the winter 2007/2008 issue of Denison Magazine, Malcuit’s strongest piece of evidence for the capture theory was the large, circular maria pattern on the face of the moon, what he calls a “signature” of capture. But even up until just a few years ago, however, Malcuit was still reading newly published articles, conducting his own research, and gathering information to back up his theory. You can never be too sure.
The attention to detail seems to have paid off. These days, Malcuit has a pretty good idea of where the Moon came from. He even knows how it got all the way over to Earth, and has the numerical codes, computer-generated models, and geologic record to prove it (essentially, ancient zircons found in Australia could not have formed under the conditions of impact). All in all, he now has enough evidence to make a seriously strong case for the capture theory (which he will when he eventually publishes the key paper, “Where Did the Moon Come From?”), even though going against the commonly accepted giant impact model is still, as Discovery News put it, “cosmic blasphemy.”
Despite its popularity, the giant impact model, according to Malcuit, is nothing more than a sensationalist bit of flash that has little to do with hard, scientific fact. “People believe [the giant impact model] because it’s so spectacular, and that anything this spectacular must be true… But it doesn’t relate to the geologic records of Earth or Luna. And it doesn’t relate to the chemistry.”
This, according to Malcuit, is where the politics side of Moon theories comes into play. “It’s kind of a David and Goliath scenario,” he says. “The Big Science versus the Little Science.” Somewhat unfortunately, scientific research requires hefty finances to back it up. And guess whose pockets are deeper?
But remember, Malcuit points out, that the continental drift proponents probably didn’t get a lot of research funding either. No one gave a damn about that stupid plate tectonics idea. Galileo was excommunicated from the Roman Catholic Church for suggesting Earth wasn’t the center of it all. And, going back even farther, those first ancient Greek scientists who said that Earth wasn’t flat were considered to be entirely off their nut. And if the capture theory gets the credit it deserves with the publishing of Malcuit’s seminal paper, we might soon be entering a new phase.