About 66 million years ago, a cataclysmic event marked the end of the dinosaur era. This episode is linked to the impact of a giant asteroid in the Chicxulub region of Mexico. Until now, the exact nature and origin of this celestial body remained subject to debate.
A new study published in
Science sheds light on these mysteries by revealing that this asteroid originated from the outer Solar System, beyond Jupiter, and not from a comet as some had supposed.
Illustration image Pixabay
Researchers employed an innovative method to analyze samples of ancient sediments. These contain ruthenium, a chemical element absent from terrestrial rocks. By comparing the isotopes of ruthenium in the samples with those from different classes of meteorites, they determined that the asteroid that struck Earth was a carbonaceous type (type C). This indicates it formed beyond Jupiter's orbit, in a region where asteroids contain more carbon and volatile elements.
This discovery challenges the hypothesis put forward in 2021 by two Harvard researchers, who proposed that the Chicxulub impactor was a long-period comet. According to their theory, the comet was fragmented by the Sun's gravitational influence before a fragment collided with Earth. However, the new data confirm that the celestial object was indeed a carbonaceous asteroid, thus refuting the comet idea.
Ruthenium played a key role in this identification. In fact, the isotopes of this element allow for distinguishing type C asteroids, formed in the outer Solar System, from type S asteroids, which are more common and originate from the inner Solar System. The fact that the Chicxulub asteroid is type C is particularly significant, as most meteorites found on Earth are type S, formed in regions closer to the Sun.
The implications of this discovery extend beyond dinosaur history. According to Mario Fischer-Gödde, a geochemist at the University of Cologne and lead author of the study, better understanding the nature of asteroids that have impacted Earth over time could provide clues about the origin of water on our planet. He also suggests that if other mass extinctions were caused by type C asteroids, it would be essential to closely monitor this type of celestial object in the future, as they could pose a significant threat to life on Earth.
Article by: Cédric DEPOND