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Scientists believe they have discovered the origin of the asteroid that wiped out the dinosaurs. The 6-mile-wide dinosaur-killing asteroid that collided with Earth and triggered a mass extinction event 66 million years ago is believed to have originated from a dark asteroid belt.
Researchers from the Southwest Research Institute determined that dinosaur-killing asteroid likely originated from the outer half of the main asteroid belt between Mars and Jupiter. The region, which is previously thought to produce few large impactors, actually produced large impactors 10 times more than previously believed.
The Cretaceous–Paleogene (K–Pg) extinction event blasted a 90-mile-wide crater known as “Chicxulub” in what is now Mexico’s Yucatan peninsula. The mass extinction event killed three-quarters of the plant and animal species on Earth, ending dinosaurs that were around for 150 million years.
“To probe the Chicxulub impact, geologists have previously examined 66-million-year-old rock samples found on land and within drill cores,” the press release for the study said. “The results indicate the impactor was similar to the carbonaceous chondrite class of meteorites, some of the most pristine materials in the solar system. Curiously, while carbonaceous chondrites are common among the many mile-wide bodies that approach the Earth, none today are close to the sizes needed to produce the Chicxulub impact with any kind of reasonable probability.”
Researchers used computer models to track how objects escape the main asteroid belt.
“Over eons, thermal forces allow these objects to drift into dynamical ‘escape hatches’ where the gravitational kicks of the planets can push them into orbits nearing Earth,” the study reads. “Using NASA’s Pleaides Supercomputer, the team followed 130,000 model asteroids evolving in this slow, steady manner for hundreds of millions of years. Particular attention was given to asteroids located in the outer half of the asteroid belt, the part that is furthest from the Sun. To their surprise, they found that 6-mile-wide asteroids from this region strike the Earth at least 10 times more often than previously calculated.”
Dr. Simone Marchi, one of the paper’s co-authors, added, “To explain their absence, several past groups have simulated large asteroid and comet breakups in the inner solar system, looking at surges of impacts on Earth with the largest one producing Chicxulub crater. While many of these models had interesting properties, none provided a satisfying match to what we know about asteroids and comets. It seemed like we were still missing something important.”
“This result is intriguing not only because the outer half of the asteroid belt is home to large numbers of carbonaceous chondrite impactors, but also because the team’s simulations can, for the first time, reproduce the orbits of large asteroids on the verge of approaching Earth,” said co-author Marchi. “Our explanation for the source of the Chicxulub impactor fits in beautifully with what we already know about how asteroids evolve.”
Scientists discovered that 6-mile-wide asteroids smash into Earth once every 250 million years on average, a timescale that works with the dinosaur-killer in Chicxulub.
The journal Icarus published a paper about this research titled: “Dark Primitive Asteroids Account for a Large Share of K/Pg-Scale Impacts on the Earth.”