Meteorites have been striking Earth since its formation 4.5 billion years ago, sometimes causing minimal damage and other times triggering significant events. But where do these space rocks originate? New research has provided the answer.
By analyzing the composition of meteorites that have landed on Earth and studying the asteroids in our solar system, astronomers have determined that approximately 70 percent of known meteorite impacts come from just three groups of asteroids located in the main asteroid belt between Mars and Jupiter.
“It is a group of asteroids which have similar orbits because they were fragments created during a collision between two asteroids,” explained astronomer Miroslav Broz of Charles University in Prague, the lead author of two of the studies published in the journals Nature and Astrophysics.
The research team conducted numerical simulations to model the formation and evolution of asteroid families orbiting the sun in the main asteroid belt. Collisions within this belt send rocky fragments flying through space, with some eventually making their way to Earth.
Michael Marsset of the European Southern Observatory in Chile, lead author of another study published in Nature, noted, “While more than 70,000 meteorites are known, only 6 percent had been clearly identified by their composition as coming from the moon, Mars, or Vesta, one of the largest asteroids in the main asteroid belt. The source of the other meteorites had remained unidentified.”
The studies revealed that the Massalia asteroid family, formed about 40 million years ago, accounts for a class of meteorites called L chondrites, representing 37 percent of known Earth meteorites. The Karin and Koronis families, formed 5.8 million and 7.6 million years ago respectively, account for H chondrites, which represent 33 percent of known meteorites.
An additional 8 percent of Earth meteorites can be traced to the Flora and Nysa asteroid families in the main belt, and about 6 percent to Vesta. Previous research found that less than 1 percent of meteorites came from the moon and Mars. The researchers are still investigating the origins of the remaining 15 percent of known meteorites.
These findings shed light on the origins of the space rocks that have played a crucial role in shaping Earth’s history. While the new research did not focus on the asteroid that struck Earth 66 million years ago—triggering the mass extinction that wiped out the dinosaurs—it provides valuable insights into the dynamics of asteroid collisions and their impact on our planet.
In recent times, the potential threat of asteroid impacts has led to proactive measures. In 2022, NASA’s DART spacecraft successfully collided with the asteroid Dimorphos in a planetary defense test, demonstrating that a spacecraft can alter the trajectory of a celestial object enough to keep Earth safe.
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Astronomers trace the origin of meteorites that have struck Earth
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