Researchers discover unexpected origin of dinosaur-killing asteroid

The asteroid that caused the extinction of the dinosaurs 66 million years ago probably came from the outer solar system.

Researchers discovered that the asteroid that wiped out the dinosaurs came from beyond Jupiterand sheds light on a rare cosmic event that caused massive changes on Earth about 66 million years ago.

Origin of the dinosaur-killing asteroid

Geoscientists at the University of Cologne have led an international study to determine the origin of the huge boulder that hit the Earth around 66 million years ago and permanently changed the climate. The scientists analyzed samples of the rock layer that forms the boundary between the chalk and Paleogene. This period also saw the last major mass extinction on Earth, in which around 70 percent of all animals died. species extinct. The results of the study published in Science suggest that the asteroid formed outside the orbit of Jupiter during the early evolution of our solar system.

Asteroid impact and mass extinction

According to a widely accepted theory, the mass extinction at the Cretaceous-Paleogene boundary was triggered by the impact of an asteroid at least ten kilometers in size near Chicxulub on the Yucatán Peninsula in Mexico. The impact vaporized the asteroid and large amounts of rock. Fine dust particles spread throughout the stratosphere and obscured the sun. This led to dramatic changes in living conditions on the planet and brought photosynthetic activity to a standstill for several years.

Tracing the origin of asteroids using sediments

The dust particles released by the impact formed a layer of sediment around the globe, which is why the Cretaceous-Paleogene boundary can be identified and sampled in many places on Earth. It contains high concentrations of platinum group metals that originated from the asteroid and are otherwise extremely rare in the rocks of the Earth's crust.

Isotope analysis reveals asteroid origin

By analyzing the isotopic composition of the platinum metal ruthenium in the clean room laboratory of the Institute of Geology and Mineralogy at the University of Cologne, the scientists found that the asteroid originally came from the outer solar system.

“The composition of the asteroid is consistent with that of carbonaceous asteroids that formed outside the orbit of Jupiter during the formation of the solar system,” said Dr. Mario Fischer-Gödde, lead author of the study.

Comparison with other impact structures

For comparison, the ruthenium isotope compositions were also determined for other craters and impact structures of different ages on Earth. These data show that within the last 500 million years, almost exclusively fragments of S-type asteroids have hit the Earth. In contrast to the impact at the Cretaceous-Paleogene boundary, these asteroids originate from the inner solar system. Well over 80 percent of all asteroid fragments that hit the Earth in the form of meteorites come from the inner solar system.

Professor Dr. Carsten Münker, co-author of the study, adds: “We have found that the impact of an asteroid like the one at Chicxulub is a very rare and unique event in the history of the Earth. The fate of the dinosaurs and many other species was sealed by this projectile from the outer regions of the solar system.”

Reference: “Ruthenium isotopes show that the Chicxulub impactor was a carbonaceous asteroid” by Mario Fischer-Gödde, Jonas Tusch, Steven Goderis, Alessandro Bragagni, Tanja Mohr-Westheide, Nils Messling, Bo-Magnus Elfers, Birger Schmitz, Wolf U. Reimold, Wolfgang D. Maier, Philippe Claeys, Christian Koeberl, François LH Tissot, Martin Bizzarro and Carsten Münker, 15 August 2024, Science.
DOI: 10.1126/science.adk4868