Meteorite Chondrules are Seeds of Destruction Rather Than the Origins of Planets

Meteors that have slammed into Earth have long been considered relics of the early solar system. Studded with chondrules, tiny, glassy spherical grains that were once molten droplets, these meteors can tell researchers a lot about our universe. In the past, scientists believed that chondrules actually represented early kernels of terrestrial planets. Now, though, they've found that this is not the case.

The researchers used computer simulations to find that chondrules actually aren't building blocks of planets, but are instead byproducts of a violent and messy planetary process. In fact, the scientists discovered that bodies as large as the moon likely existed well before chondrules came onto the scene.

So how were chondrules created, then? It's likely that they formed during the collision of moon-sized planetary embryos; these planetary bodies smashed together with such violent force that they melted a fraction of their material, and shot a molten plume out into the solar nebula. Residual droplets would eventually cool to form chondrules which, in turn, attached the larger bodies.

"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," said Brandon Johnson, one of the researchers, in a news 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."

The model actually estimated the number of impact-jetting collisions that probably occurred in a solar system's first five million years, which is the period of time in which scientists believe chondrules first appeared. In the end, they found that these collisions would have produced enough chonrules in the asteroid belt region to explain the number that have been detected in meteorites today.

"This would be a major shift in how people think about our solar system," said Fred Ciesla, an associate professor of planetary science at the University of Chicago who did not contribute to the research. "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."

The findings are published in the journal Nature.

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