New Study Suggests That Meteorites Were Not Building Blocks Of Planets


Although we've long thought that meteorites played a significant role in the formation of planets in our solar system, a new study suggests that meteorites were less important to planet formation than we initially thought.

The study, done by MIT and Purdue University, suggests that meteorites did not serve as the building blocks of planets, as originally believed. These researchers uncovered that it's likely that meteorites are just byproducts of the planet formation process.

The surface of meteors contains small spherical grains of molten droplets called chondrules. Scientists once thought the glass-like chondrules were the building blocks of the solar system's planets. The idea was that when the solar system formed, these chondrules represented where meteors constantly collided with gas and dust, which eventually formed planets.

Now, though, after running a series of computer simulations, scientists believe that the chondrules are just the remains of other collisions between protoplanetary bodies that occurred during the solar system's early years, which were more violent and numerous than we imagined.

 (Photo : NASA/California Institute of Technology) Artist's concept of a protoplanetary collision

"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," says Brandon Johnson of MIT's Earth, Atmospheric and Planetary Sciences department. "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."

Researchers used simulations to study collisions of protoplanetary bodies between the size of the moon and an asteroid. These simulations showed that bodies the size of the moon formed quickly, well before chondrules appeared on meteors. Another simulation figured out the kind of collision that formed chondrules, as well as estimated how many of these collisions happened during the first 5 million years of the solar system.

Results of the simulations supported the new theory that chondrules aren't as important as previously thought, at least to planet formation.

If confirmed, this study's results change a lot of what we know about our early solar system and how the planets formed. However, scientists stress that understanding the nature of meteorites still holds answers about our solar system's early days.

"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," says Fred Ciesla, associate professor of planetary science at the University of Chicago. "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."

[Photo Credit: Smithsonian Institution]

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