Thursday, 05 April 2012 08:45
April 5, 2012
New research indicates the Moon might not have originated from a meteorite crashing into Earth.
The New York Times reports that scientists have long posited that the Moon formed when a massive object roughly the size of Mars slammed into Earth. University of Chicago researcher Junjun Zhang noted that under such a theory, approximately "half of the Moon-forming material should come from the Mars-size impactor."
However, new engineering research suggests that such a model may not be as accurate as once believed. Recent samples of isotopic titanium that were taken from the Moon and the Earth show that substances emanating from the Earth dominate the landscape on the Moon. The new research, which scientists published in the journal Nature Geoscience, has upturned the previously held theory, and has prompted scientists to rethink the classic model that underlies current understanding of the Moon.
ScienceNow reports that the prevailing theory stipulates roughly 40 percent of the magma that ultimately became the Moon would have to have come from Theia, the Mars-sized object that collided with the Earth, to remain consistent with the laws of physics. Zhang asserted that it is unlikely that Earth would have exchanged titanium gas with the magnum disk that subsequently formed the Moon because titanium has a very high boiling point.
"The oxygen isotopic composition would be very easily homogenized because oxygen is much more volatile, but we would expect homogenizing titanium to be very difficult," according to Zhang.
The team's new findings indicate the Earth and the Moon share a common makeup, according to Zhang. She and her fellow scientists used data in their work that astronauts gathered during the Apollo missions that occurred in the 1960s and 1970s. They said that after comparing isotopic titanium samples from the Moon and the Earth, they determined they essentially had identical ratios.
Moreover, the researchers concluded that meteorites have a much more expansive range of isotopic titanium. Such a finding lent added weight to their theory that the Moon is more likely to have detached from the Earth than to have from sprung from space debris that slammed into the planet eons ago.
"The Moon has an identical titanium composition to the Earth," she noted. "That also tells us that the impactor that hit the Earth was very unlikely to have to the same composition as the Earth. So the prevailing model of the giant impact probably needs to be revisited."
Zhang and her colleagues worked with scientists at the University of Bern in Switzerland on the study, according to ScienceNow. Researchers examined titanium isotopes in 24 separate samples of lunar rock and soil to reach their conclusion. As a result of the new research, scientists have begun to formulate new theories regarding the origin of the Moon.
Some have speculated that a passing meteorite could have struck the Earth, forcing it to spin so rapidly that it ultimately caused a piece of the planet to fly into space. Scientists have questioned such a model, however, noting that it would not explain where the extra angular momentum went after the Moon originated.
Nevertheless, researchers such as Matthias Meier of Sweden's Lund University are not ready to abandon the standard model governing the Moon's creation. He said that although the new findings are persuasive, they prompt more questions than they answer.
"I think the general idea of having an impact forming a disk and this disk then forming a moon is probably right, but this paper shows us that we still don't understand exactly what the mechanism is, and there is a lot of work to be done in that field," he said.
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