by Brooks Hays
Boston (UPI) Jan 15, 2015
That meteorites and their collisions with early planetary masses played a predominant role in the formation of the early universe is a narrative popular among astronomers and the average high school science class.
But new research suggests the contributions of meteorites in forming Earth and its planetary neighbors was minimal. These ancient hunks of rock hurling haphazardly through an infant solar system were more a byproduct than building blocks, researchers at MIT say.
Previously, scientists have posited chondrules as the key ingredient in planet formation. Chondrules are the droplets of molten rock produced by high energy impacts between two sizable pieces of space rock -- asteroid hitting astroid, planet hitting planetesimal, meteorite hitting protoplanet.
Scientists at MIT and Purdue ran computer simulations to crunch the numbers on the formation of the early solar system. The models suggest that by the time space rocks big and fast enough for their collisions to create chondrules showed up on the scene, planetary embryos the size of the moon (the real building blocks) were already well-formed.
"This tells us that meteorites aren't actually representative of the material that formed planets -- they're these smaller fractions of material that are the byproduct of planet formation," study author Brandon Johnson, a postdoc in MIT's Department of Earth, Atmospheric and Planetary Sciences, explained in a recent press release. "But it also tells us the early solar system was more violent than we expected: You had these massive sprays of molten material getting ejected out from these really big impacts. It's an extreme process."
What's more, the simulations showed each meteorite impact turned only a small portion of their solid materials into chondrule. Small droplets and violently exploded rock may have been ubiquitous, but it was relatively minor in volume as compared to already forming planets.
In other words, chondrules may have been the spices that flavored young planets, but they certainly weren't the main ingredient.
"This would be a major shift in how people think about our solar system," said Fred Ciesla, a planetary scientist at the University of Chicago who wasn't involved with the study. "If this finding is correct, then it would suggest that chondrites are not good analogs for the building blocks of the Earth and other planets."
"Meteorites as a whole are still important clues about what processes occurred during the formation of the solar system, but which ones are the best analogs for what the planets were made out of would change," he added.
The new study was published this week in the journal Nature.
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