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Meteorites Might Not Have Created Solar System

Jan 15, 2015 01:14 PM EST
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Despite conventional belief, meteorites might not have led to the creation of the solar system, according to a new study.

Scientists have long thought that the chondrules found on meteorites - tiny, spherical grains that were once molten droplets - were the early beginnings of the terrestrial planets that now make up our solar system. During its formation, these molten droplets supposedly collided with bits of gas and dust to form larger planetary precursors.

However, a team from MIT and Purdue University says otherwise, arguing that these chondrules were actually just byproducts of smashes between Moon-sized bodies, and not the building blocks we once thought they were.

"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," Brandon Johnson of MIT said in a statement. "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."

In order to paint this rather unusual and violent picture, Johnson and his colleagues created simulations of collisions between protoplants - rocky bodies ranging from the size of an asteroid to the size of the Moon. They modeled all sorts of possible impacts, accounting for location timing, size and velocity.

According to their results, Moon-sized worlds formed rather quickly - within the first 10,000 years, before chondrules likely even existed.

So why have we thought that chondrules were the solar system's building blocks all this time? Well, the researchers say that the impacts were so intense that they melted and ejected molten material out into space (called impact jetting), where it would cool into chondrules and attach to larger bodies that later would collide with Earth, forming the meteorites that scientists have studied to this day.

And based on the new study's simulations, this theory is possible. They calculated that during the solar system's first five million years, impact jetting would have produced enough chondrules in the asteroid belt region to explain the number that have been detected in meteorites today.

In addition, protoplanetary collisions occurring at a rate of 2.5 kilometers per second could have created the conditions needed for chondrules to cool down at their normal rate (10 to 1,000 kelvins per hour).

While this theory hasn't yet been proven definitively, it would certainly change our thinking of meteorites as relics of the early solar system.

"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," added co-author Fred Ciesla. "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 were published in the journal Nature.

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