About 66 million years ago, an object estimated to be 6 miles wide (9.6 kilometers) fell to Earth, triggering a series of catastrophic events that resulted in the disappearance of non-avian dinosaurs.
Scientists now believe they know where this object came from.
According to a new study, the impact was caused by a huge dark primitive asteroid on the boundary of the solar system’s main asteroid belt, which lies between Mars & Jupiter. This area is home to many dark asteroids-the chemical composition of space rocks makes them appear darker (and reflect very little light) compared to other types of asteroids.
“I suspected that the outer half of the asteroid belt – That is where the dark, primitive asteroids are located, which can be a major source of terrestrial impactors, “said David Nesvorný, a researcher at the Southwest Research Institute in Colorado who led the new study.” But I didn’t expect the results to be this definitive, “adding that this may not be the case for the smaller impactors.
Previously, evidence of an object ending the rule of non-avian dinosaurs was found buried in the Chicxulub Crater. This is a 145-kilometer-wide circular scar left by an object collision on the Yucatan Peninsula of Mexico. Geochemical analysis of the crater shows that this [impacting] object belongs to a class of carbonaceous chondrites, a primitive group of relatively high carbon meteorites that were likely formed very early in the history of the solar system.
Based on this knowledge, scientists have previously tried to identify the origin of the impactor, but many theories have fallen apart over time. Researchers had previously suggested that the impactor came from a family of asteroids found in the inner part of the main asteroid belt, but follow-up observations of these asteroids found that they were not the right composition.
In the new study, published in the November 2021 issue of Icarus journal, researchers developed a computer model to see how often Main Belt asteroids escaped toward Earth and whether such escape could be responsible for the dinosaur era ending incident.
The model simulated over hundreds of millions of years and showed thermal forces and gravitational pulls from the planets that periodically pull large asteroids out of the belt. On average, every 250 million years, an asteroid more than 10 km wide from the outer edge of the belt was thrown into collision course with Earth, the researchers found. This calculation makes such an event five times more frequent than previously thought & consistent with Chicxulub Crater, which formed only 66 million years ago, it is the only known impact crater believed to have been created by such a large asteroid in the last 250 million years. In addition, the model analyzed the distribution of “dark” and “light” impactors in the asteroid belt and showed that half of the asteroids [expelled] were dark carbonaceous chondrites, which matches the type believed to have caused the Chicxulub crater.
“This is just an excellent article,” said Jessica Noviello, a NASA fellow in the Universities Space Research Association’s postdoctoral management program at Goddard Space Flight Center who was not involved in the new research. “I think they’re a good argument as to why [the Chicxulub impactor] might have come from this part of the solar system.
Not only may the results explain the origin of the Chicxulub crater impactor, but they will also help scientists understand the origins of other asteroids that have struck Earth in the past. Neither of the other two largest impact craters on earth, the Vredefort Crater in South Africa & the Sudbury Basin in Canada, have a known origin impactor. The results could also help scientists predict where future large impactors might [originate].
“We found in the study that about 60% of the large terrestrial-impactors come from the outer half of the asteroid belt … and most asteroids in this area are dark / primitive,” Nesvorný told Live Science. – There is 60% -3 out of 5 – probability that the next one will comes from the same region.
Article originally published on Live Science.