The asteroid that caused the extinction of the dinosaurs 66 million years ago likely originated from the outer regions of our solar system.
Researchers from the University of Cologne spearheaded an international investigation to trace the origins of the massive rock that collided with Earth approximately 66 million years ago, causing significant climatic shifts. They examined rock layer samples that represent the boundary between the Cretaceous and Paleogene periods, which coincides with the last significant mass extinction on Earth, where around 70 percent of animal species vanished. Findings from the study, published in Science, suggest that the asteroid was formed outside of Jupiter’s orbit during the early stages of the solar system’s development.
According to a well-established theory, the mass extinction event at the Cretaceous-Paleogene boundary was instigated by an asteroid, measuring at least 10 kilometers across, that struck near Chicxulub on Mexico’s Yucatán Peninsula. Upon impact, the asteroid and substantial amounts of Earth’s material were vaporized. The resultant fine dust dispersed into the stratosphere, blocking sunlight and dramatically altering the planet’s living conditions, halting photosynthesis for several years.
The dust generated from this impact created a sedimentary layer that is found globally, which is why the Cretaceous-Paleogene boundary can be identified in various locations around the world. This layer contains elevated levels of platinum-group metals, which are attributed to the asteroid and are typically very rare in Earth’s crust.
By studying the isotopic makeup of the platinum metal ruthenium at the University of Cologne’s laboratory of Geology and Mineralogy, researchers concluded that the asteroid had its origins in the outer solar system. “The composition of the asteroid aligns with that of carbonaceous asteroids that formed beyond Jupiter’s orbit during the solar system’s formation,” explained Dr. Mario Fischer-Gödde, the study’s lead author.
Additionally, the isotopic compositions of ruthenium were analyzed from other craters and impact sites of varying ages on Earth for comparison. This research revealed that for the last 500 million years, Earth has primarily been struck by fragments from S-type asteroids, which are predominantly sourced from the inner solar system. Unlike the Cretaceous-Paleogene impact, over 80 percent of meteorite fragments that reach Earth come from the inner solar system. Professor Dr. Carsten Münker, a co-author of the study, commented, “We discovered that an asteroid impact like the one at Chicxulub is an exceptionally rare occurrence in geological history. The extinction of the dinosaurs and many other species was determined by this projectile from the far reaches of the solar system.”
