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Most of Earth's meteorites may have come from the same 3 spots

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Scientists say they've uncovered where the vast majority of Earth's meteorites came from.

A long-exposure photo showing many meteors streaking across the night sky
(Image credit: CFOTO via Getty Images)

Earth is constantly getting pummeled by meteorites. We are unaware of most of them, as they burn up in our atmosphere before they hit the ground. Every now and again, though, something larger gets drawn into Earth's gravitational field — and when this happens, it usually spells bad news for any life living on our planet's surface.

Scientists know that the vast majority of meteorites that come crashing down to Earth originate from the solar system's main asteroid belt: a region between Mars and Jupiter where irregularly shaped rocks left over from the formation of the solar system crash into and bounce off each other during their journeys around the sun.

Using a telescopic survey to determine the composition of the main families of asteroids in the main asteroid belt and tapping into computer simulations to map the colossians and evolution of these families, researchers were able to reveal which three families the vast majority of Earth's meteorites likely come from.

Related: 200 meteorites on Earth traced to 5 craters on Mars

Namely, they originate from the Karin, Koronis and Massalia asteroid families, which formed from collisions in the main asteroid belt that occurred about 5.8 million, 7.5 million and 40 million years ago, respectively. In particular, the Massalia family is said to be responsible for 37% of known Earth meteorites.

Until now, 6% of meteorites had been identified ( via their compositions) as coming from the moon, Mars or Vesta, which is one of the largest objects in the main asteroid belt. Where the other 94% originated from had remained something of a mystery.

So, why are these young asteroid families the source of so many meteorites? Younger families of asteroids, broken up by relatively recent collisions, are composed of more fragments, which means they are more likely to have fragments that escape the main asteroid belt, possibly in the direction of Earth. As time rolls on, families get older and slowly lose their fragments, becoming less of a source for meteorites.

Nonetheless, let's hope there isn't a kilometer-size asteroid waiting in the main belt with our name on it.

Originally posted on Space.com.

Conor Feehly
Conor Feehly

Conor Feehly is a New Zealand-based science writer. He has earned a master's in science communication from the University of Otago, Dunedin. His writing has appeared in Cosmos Magazine, Discover Magazine and ScienceAlert. His writing largely covers topics relating to neuroscience and psychology, although he also enjoys writing about a number of scientific subjects ranging from astrophysics to archaeology.