Asteroid that ended dinosaurs came from beyond Jupiter, study discovers

The Chicxulub asteroid struck Earth with 10,000 times the power of the world’s nuclear arsenal.

Key Takeaways

1. The asteroid that wiped out the dinosaurs likely originated from the outer solar system, beyond Jupiter, as suggested by a new isotope analysis.
2. This discovery differentiates the Chicxulub asteroid from other impactors, which primarily originated in the inner solar system.
3. Ruthenium isotopes found in rocks from the K/Pg boundary helped identify the asteroid’s origin.
4. The Chicxulub impactor’s devastating collision led to the extinction of 80% of species and marked the emergence of mammalian dominance.
5. The study solidifies the asteroid theory, ruling out the previously proposed hypothesis that the object might have been a comet.

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Chicxulub’s Catastrophic Impact

Sixty-six million years ago, a colossal asteroid struck Earth, triggering a mass extinction event that eradicated the dinosaurs and reshaped the planet’s biological history. Scientists now suggest the Chicxulub impactor originated in the outer solar system, beyond Jupiter, based on isotope analysis published in Science. Unlike five other asteroid impacts studied, which involved inner solar system rocks, the Chicxulub asteroid exhibited a distinct composition tied to its carbon-rich makeup.

The asteroid, measuring between 6 and 12 miles in width, collided with Earth at 15.5 miles per second, carving out the Chicxulub crater on Mexico’s Yucatán Peninsula. NASA estimates its energy output equaled 10,000 times the world’s nuclear arsenal. The collision unleashed massive amounts of soot and vapor, creating a global shroud that led to the extinction of 80% of species, including the non-avian dinosaurs. This catastrophic event also paved the way for mammals to become Earth’s dominant life forms.

Ruthenium’s Isotopic Signature

To pinpoint the Chicxulub asteroid’s origin, researchers analyzed the rare metal ruthenium found in the K/Pg boundary—a geologic layer marking the impact. This layer preserves evidence of the asteroid’s aftermath, and its isotopic composition is directly linked to where the asteroid formed in the solar system. By comparing ruthenium isotopes from boundary samples with meteorites, scientists identified a match with carbonaceous asteroids from the outer solar system.

Lead author Mario Fischer-Gödde emphasized that understanding the origins of such objects is vital for assessing future collision threats. The findings also contradict earlier theories suggesting the Chicxulub impactor might have been a comet. Instead, the study reinforces that it was a carbonaceous asteroid—a result supported by its isotopic evidence and distinct mineralogical traits.

Astrophysicists like Steve Desch and Sean Gulick have praised the study for its robust methodology and findings. This research not only strengthens our understanding of the Chicxulub event but also provides a framework for studying other asteroid impacts.