Astronomers trace the origin of meteorites that have struck Earth
Meteorites, the space rocks that have bombarded Earth since its formation 4.5 billion years ago, have long fascinated scientists. New research sheds light on their origins, revealing that approximately 70% of known meteorite impacts stem from just three families of asteroids in the main asteroid belt between Mars and Jupiter.
In a series of studies published in Nature and Astronomy and Astrophysics, astronomers analyzed the composition of meteorites alongside data from asteroids, determining that the Massalia, Karin, and Koronis asteroid families are significant contributors to the meteorites we find on Earth.
“The Massalia family, created from a collision around 40 million years ago, accounts for 37% of known Earth meteorites,” explained Miroslav Brož, an astronomer from Charles University in Prague and lead author of two of the studies. The Karin and Koronis families, formed 5.8 and 7.6 million years ago respectively, contribute another 33% of meteorites known as H chondrites.
Only 6% of meteorites have been clearly linked to the Moon, Mars, or Vesta, one of the largest asteroids. The majority—more than 70,000 meteorites—had remained of uncertain origin until now. This extensive research utilized numerical simulations to model the formation and evolution of asteroid families, highlighting how collisions send fragments hurtling toward Earth.
While much of this research focused on meteorites’ origins, it did not delve into the infamous asteroid that led to the extinction of the dinosaurs 66 million years ago. Previous findings suggested that this particular space rock likely originated beyond Jupiter, subsequently migrating to the main asteroid belt before colliding with Earth.
“Large space rocks can pose a significant threat to life,” noted Brož, referencing NASA’s successful DART mission, which recently demonstrated that a spacecraft could alter an asteroid’s trajectory as a planetary defense measure.
Meteorites not only help us understand the solar system’s past but also serve as remnants from the primordial protoplanetary disk that existed before the planets formed. “Chondrites are vital for studying the early solar system,” stated Michaël Marsset of the European Southern Observatory, lead author of one of the studies.
As researchers continue to trace the origins of the remaining 15% of meteorites, their findings underscore the crucial role these cosmic travelers play in both Earth’s history and the broader narrative of our solar system.
