Researchers Identified Asteroid That Caused Mass Extinction
A study confirmed the 66 million-year-old impactor was a carbonaceous chondrite from the outer solar system.
Updated on Sept. 21, 2026 in Geology
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Scientists determined that the asteroid that struck the Yucatan Peninsula 66 million years ago was a CO-class carbonaceous chondrite. This finding challenges previous theories by suggesting that atmospheric debris, rather than sulfur, triggered the extinction of 75% of Earth's species.
Why it matters
The study provides critical clarity on the extinction mechanism by revealing that the asteroid contained significantly lower sulfur levels than previously assumed. This shift in understanding suggests that blocking solar radiation with atmospheric debris played a larger role in the climate collapse than chemical reactions.
Researchers identified the projectile composition by analyzing nickel isotopes in a global sediment clay layer. The impacting object measured 10 to 15 kilometers in width and traveled at a velocity of 64,000 km/h.
The players
Yucatan Peninsula
This is the geographical region in Mexico that serves as the site of the Chicxulub crater formed by the asteroid impact.
The details
By analyzing the chemical signatures of global clay layers, scientists traced the asteroid to the outer asteroid belt near Jupiter. Because CO-class chondrites represent only 5% of all known meteorites, the findings highlight a specific, rare source for the event that altered Earth's biological trajectory.
Timeline
66 million years ago: An asteroid struck the Yucatan Peninsula and triggered a mass extinction event.
The Big Picture
This discovery updates the scientific consensus regarding the Cretaceous-Paleogene extinction event by identifying the specific chemical composition of the impactor. It shifts the prevailing hypothesis away from sulfur-driven toxicity toward solar radiation blockage caused by microscopic atmospheric debris.
While historical, this study refines our understanding of planetary defense and the long-term impact of asteroid strikes on Earth's climate. Future research in this field could lead to better predictive models for how various types of extraterrestrial objects affect the global atmosphere.
The takeaway
Understanding the chemical makeup of past impactors helps scientists refine models for how specific asteroids would interact with our modern atmosphere. It highlights that even rare types of celestial debris can carry profound consequences for life on Earth.
Further reading
For more on the history of Earth's crust and major geological events, explore the Geology section.
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