Meteorites – rocks that fall to Earth from space – have been striking our planet since its formation about 4.5 billion years ago. While most cause minimal damage, some have led to significant cataclysms, including the mass extinction event that wiped out the dinosaurs.
Recent research has unveiled that approximately 70 percent of known meteorite impacts on Earth originate from just three groups of asteroids located in the main asteroid belt between Mars and Jupiter. By analyzing the composition of meteorites and the characteristics of asteroids in our solar system, astronomers have traced the vast majority of these space rocks.
The studies involved numerical simulations to model the formation and evolution of asteroid families orbiting the sun. \"These asteroid families have similar orbits because they were fragments created during collisions between larger asteroids,\" explains Miroslav Broz, lead author of two studies published in Nature and Astrophysics.
One of the key findings links the Massalia asteroid family, formed around 40 million years ago, to L chondrites, which make up 37 percent of Earth meteorites. Similarly, the Karin and Koronis families account for 33 percent of H chondrites. Additionally, 8 percent of meteorites can be traced to the Flora and Nysa families, and about 6 percent originate from Vesta, one of the largest asteroids in the main belt.
Despite these insights, the origins of roughly 15 percent of meteorites remain unidentified. These findings not only enhance our understanding of meteorite distribution but also play a crucial role in planetary defense. For instance, NASA's DART spacecraft successfully altered the trajectory of asteroid Dimorphos in 2022, demonstrating a viable method to protect Earth from potential future impacts.
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Astronomers trace the origin of meteorites that have struck Earth
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