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Giant impact proven? Not so fast

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A team of isotope geologists now say they have definitive proof that a giant impactor, four and a half billion years ago, struck the earth and formed the moon. What they've found does not convince even every conventional scientist. A leading creation scientist says this new finding does not change his own conclusion: the giant impact hypothesis is unworkable, and the recent finding is further evidence of his own theory.

Dr Daniel Herwartz and his team say they found significant differences in the ratios of oxygen-17 to oxygen 16 in lunar samples returns by the crews of the Apollo 11, 12, and 16 missions. These samples have more oxygen 17 by 12.3 parts per million. The difference is small, but statistically significant. They published their findings today in the journal Science.

Dr. Herwartz also believes he knows what the giant impact object, named Theia, was made of. (Theia, in classical mythology, was a Titan and the mother of Selene, goddess of the moon.) Herwartz identified a class of meteoroids called enstatite chondrites, having an oxygen isotope ratio similar to that which his team found in the Apollo samples. He therefore proposes the giant impact object was made of the same material as these enstatite chondrite meteoroids. But he also admits these samples could also have come from a meteoritic bombardment that happened after the moon formed.

Thus far no reporter, covering these findings, has mentioned this admission of another explanation for the oxygen isotope ratio. Various reports mentioning the new finding also appeared today in the journal Nature, the online news outlet space.com (link courtesy Yahoo! News), and BBC News from London. According to the Nature report and the BBC report, this new finding does not impress every isotope geologist who has so far looked at it. Dr Robert Clayton, formerly of the University of Chicago, said the new findings might be more precise but still reveal little about the composition of the moon that scientists did not already know. Lydia Hallis at Glasgow University pointed out that oxygen isotope ratios can vary among lunar samples. For that reason, she said, lunar samples from three Project Apollo missions cannot adequately characterize the moon as a whole. (She also speculated to the Nature author that Herwartz and his team ought to have measured isotope compositions for titanium and silicon also. They, too, have earlier shown isotope ratios similar to those on earth.)

Professor Alex Halliday at Oxford expressed surprise that the oxygen isotope ratio was no more different between the Earth and the moon than 12.3 parts per million. As he and others noted, oxygen isotope ratios tend to vary much more greatly among meteorites said to have arisen from the planet Mars and other bodies from the outer solar system. Why, then, should the giant impact object have a composition so similar to that of the earth?

The BBC article also reported the theory of Professor Rob de Meijer of Groningen University in Holland. He proposed the moon is made of materials from the earth's crust and mantle, blown into space in a nuclear detonation centered 1800 miles deep to the surface of the earth.

Today's article almost marks a sea change at Science. In October of last year, Daniel Clery wrote almost scathingly that his fellow scientists first thought the giant impact would have destroyed both the earth and the impactor. Out of the resulting debris cloud, so the theory went, the earth re-formed, and the moon formed in orbit around it. That was supposed to explain why lunar samples were nearly identical in composition to earth rocks. As Clery reported, "recent computer models show, such a collision wouldn't have scrambled the two bodies together enough to explain the similarity."

But today Dr. Herwartz claimed the lunar samples are significantly different from earth rocks. His team used more refined methods to measure the isotopic composition of the lunar samples far more precisely than anyone had been able to do before.

Walter T. Brown, of the Center for Scientific Creation, is best known for his Hydroplate Theory of the global flood. He has always held that the earth and moon were created together, about seven thousand years ago, as Genesis chapter 1 records. He also said the global flood occurred when a sub-crustal ocean broke containment and formed a hypersonic jet of water. This jet carried large amounts of water, rock, and mud into outer space - about three percent of the earth's mass, Brown told this Examiner today. Some of this would have fallen to the moon. The two lunar poles collected a lot of water as ice, because they are in perpetual shadow. The rest of the surface suffered the first meteoritic bombardment that formed the craters, "bays," "lakes," and "seas" of the moon today.

The other key part of this theory, relevant to this discussion, is the production of super-heavy elements in the Earth's crust, due to the tremendous earthquakes in a crust laden with quartz. These super-heavy elements split to form the trans-lead radioactive elements on the earth today. This process also released the highest neutron flux ever observed on earth. Heavier isotopes of oxygen and other elements formed through simple neutron capture. The deeper parts of the earth's crust were closer to the neutron flux, so they formed heavy isotopes in greater proportions. This, Brown explained, is also the same material that went into space in the hypersonic jet.

Brown also reminded this Examiner that the astronauts of Project Apollo could do no more than pick up rocks, or occasionally chip them off, on the surface. The astronauts did carry drills and shovels, but never drilled or dug more than a few feet deep.

"The purpose of Project Apollo was to find out the origin of the moon," he said. "Forty-five years after [Apollo 11], we still don't know it."

In his book In the Beginning: Compelling Evidence for Creation and the Flood, Brown discusses several reasons why the giant impact hypothesis cannot hold. "The orbit of the moon is severely inclined with respect to the earth's equator," he said. "A giant impact should have kept that orbit co-planar with the equator. Besides, the moon's orbit is nearly circular. Even a glancing blow would have produced an elliptical orbit. And a head-on blow would have sent a mass flying off the opposite side, never to return, or else to go out and back in a high-arc trajectory, not an orbit." Furthermore, a giant impact would have formed not only one moon, but several.

Brown mentioned what he called a worse problem: the angular-momentum problem. "About seventy percent of the angular momentum in the Earth-Moon system is associated with the moon, in its rotation and its orbit." With a giant impact, earth's day should be far shorter than twenty-four hours.

Finally, a giant impact would have melted the crust and mantle at impact. No geologist has ever reported evidence of such a melt. But the Apollo lunar samples included tiny glass beads, that apparently formed from a melt on the moon. Those beads, incredibly, held water inside. With a giant impact, all this water should have escaped into vacuum.

Brown says the new oxygen-isotope findings confirm the Hydroplate Theory, not the giant impact theory. He also ruefully observed that Daniel Herwartz and his team know nothing of the Hydroplate Theory. But Brown chuckled over Rob de Meijer's theory of a thermonuclear detonation causing an explosion that expelled the material that formed the moon. "He'd better have a mechanism for focusing all the energy from that explosion," Brown said. "And if anyone talks seriously of violent nuclear explosions on the prehistoric earth, how much less believable is my theory about water and rock escaping from a sub-crustal ocean?"

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