There’s been intense debate for decades about the cosmic rock that destroyed the dinosaurs, but a new study has uncovered some important — and far-reaching — data about the rock’s origin story.
The researchers, whose findings were published Thursday in the journal Science, used an innovative technique to demonstrate that the supernova that hit Earth’s surface 66 million years ago and caused the recent mass extinction formed beyond Jupiter’s orbit.
They also refute the idea that it was a comet.
New information about an asteroid located in Chicxulub on the Yucatan Peninsula in present-day Mexico could improve our understanding of celestial bodies that approach our planet.
“With all this information we can now say that this asteroid initially formed outside of Jupiter,” Mario Fischer-Godde, lead author of the study and a geochemist at the University of Cologne, told AFP.
This finding is particularly noteworthy, since this type of asteroid very rarely collides with Earth.
Such information could prove useful in assessing future hazards, or determining how water came to be on the planet, Fischer-Godde said.
Samples
The new findings are based on analysis of sediment samples formed in the period between the Cretaceous and Paleogene eras, the time of the asteroid’s catastrophic impact.
The researchers measured isotopes of the element ruthenium, which is not uncommon on asteroids but extremely rare on Earth. So by observing deposits in several geological layers that mark debris from the impact at Chicxulub, they could be sure that the ruthenium studied “100 percent came from this asteroid.”
“Our laboratory in Cologne is one of the rare laboratories that can make these measurements,” said Fischer-Godde, “and it was the first time that such study techniques were applied to layers of impact debris.”
Ruthenium isotopes can be used to distinguish between two main groups of asteroids: C-type, or carbonaceous, asteroids that formed in the outer Solar System, and S-type silicate asteroids that come from the inner Solar System, near the Sun.
The study confirmed that the asteroid that caused a massive earthquake, a global winter and wiped out the dinosaurs and most other life forms was a C-type asteroid that formed beyond Jupiter.
Studies two decades ago made similar assumptions, but with much less certainty.
The findings are surprising, Fischer-Godde explained, because most meteorites — fragments of asteroids that fall to Earth — are S-type.
Does this mean that the Chicxulub impactor formed beyond Jupiter and headed straight for our planet? Not necessarily.
“We can’t really be sure where the asteroid was hiding just before it hit Earth,” Fischer-Godde said, adding that after its formation, it likely stayed in the asteroid belt, which lies between Mars and Jupiter and is where most meteoroids originate.
Not a comet
The study also rules out the idea that the devastating impactor was a comet, a concoction of icy rock from the very edge of the solar system. Such a hypothesis was put forward in a much-publicised study in 2021 based on statistical simulations.
Analysis of the samples now shows that this celestial body was very different in composition from a subset of meteorites that have been thought to be comets in the past. So it is “impossible” that the impactor in question was a comet, Fischer-Goode said.
The geochemist made two suggestions regarding the broader utility of his findings.
They believe that more precisely defining the nature of the asteroids that struck Earth 4.5 billion years ago could help solve the puzzle of the origin of water on our planet.
Scientists believe that water may have come to Earth via asteroids, most likely C-type ones, like the one that struck 66 million years ago, although these are now rare.
Studying past asteroids also gives humanity an opportunity to prepare for the future, Fischer-Godde said.
“If we find that past mass extinctions may also be related to the impact of C-type asteroids, then … if there is ever a C-type asteroid in an orbit that crosses Earth, we have to be very careful, because it may be the last asteroid we see,” he said.
(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)
