Asteroid Collisions Linked to Ancient Earth Climates, New Research Suggests
A new study published in Nature Astronomy sheds light on the origins of L-type chondrites, a common type of meteorite found on Earth, and proposes a surprising connection between asteroid collisions and major climate shifts in our planet’s history. Researchers from france’s Museum National of Natural History, CNRS, Sorbonne University, and other institutions have traced these meteorites back to at least three distinct asteroid families, revealing a history of violent impacts spanning billions of years.
Each year, approximately 30,000 meteorites reach Earth’s surface, fragments broken off from larger bodies like asteroids. For decades, scientists have sought to identify the “parent” asteroids responsible for these space rocks. This latest research focuses on L-type chondrites, which comprise 35% of collected samples, but whose origins have remained a puzzle.The team analyzed eight chondrites recovered from diverse locations – China, Australia, and the Sahara Desert – specifically selecting samples exhibiting notable evidence of past impacts. By examining the mineral structures altered by these high-energy collisions, researchers were able to “reset” the meteorite’s internal clock and determine when it was ejected from its parent body. The intensity and duration of these shocks also provided clues about the size of the original asteroid.
Combining this analysis with data from recent meteorite falls, allowing for trajectory mapping and pinpointing potential source regions within the asteroid belt, the team challenged previous assumptions. Instead of originating from a single, large asteroid disturbed 470 million years ago, the evidence points to a “collisional cascade” - a series of impacts occurring at 4.5 billion, 4.470 billion, 700 million, 470 million, and 100 million years ago.
This series of collisions created multiple asteroid families, including those linked to the Gefion 2 and Juno asteroids. Notably, impacts around 470 million years ago coincided with a surge in meteorite activity that left its mark in geological layers dating back to the end of the Ordovician period. This period was a pivotal moment in Earth’s history, characterized by a major glacial period and the first mass extinction event, impacting exclusively marine life.
The researchers suggest that a significant influx of meteoritic dust could have darkened the atmosphere, contributing to the cooling that triggered this extinction.Furthermore, a collision identified around 700 million years ago, linked to the Nysa-Polana asteroid family, coincides with the Cryogenian glacial period, further hinting at a potential link between asteroid impacts and dramatic climate change.
“These findings suggest a potentially significant role for meteoritic input in shaping Earth’s climate throughout its history,” explains lead author Marine Ciocco. “While further research is needed to fully understand the complex interplay between asteroid impacts and planetary climate, this study provides compelling evidence for a long-suspected connection.”