Scientists have determined the likely origin of the dinosaur-killing asteroid that brought about their extinction and killed three quarters of all life here on Earth.
This asteroid is officially known as the Chicxulub impactor and it struck the Earth 66 million years ago. Scientists have estimated the origin of this asteroid for decades, but a new Southwest Research Institute study posits that it came from the outer half of our solar system’s main asteroid belt, as reported by Space.com.
More specifically, the six-mile-wide Chicxulub impactor originated in the asteroid belt space in between Mars and Jupiter. According to Space.com, scientists used computer models to analyze how asteroids in that region of space are pulled from their orbit to different areas of the solar system. In this instance, the asteroid was pulled from its location way out in space to Earth, where it eventually crashed and created a 90-mile crater.
It was that impact and the resulting effects that killed all dinosaurs and 75% of the world’s animal species.
To determine the trajectory of Chicxulub, the Southwest Research Institute team observed 13,000 asteroid models. In so doing, they determined that because of the characteristics of those asteroids and the belt they existed in, those asteroids are 10 times more likely to reach Earth than scientists previously thought.
With that determined, the team began to look at the possibilities of an asteroid in that belt hitting Earth and discovered “escape hatches.” These are essentially hatches in the asteroid belt orbit created by thermal forces that pull asteroids out of orbit and toward Earth (or anywhere else really).
How did the team connect the dinosaur-killing asteroid with those found in the space between Mars and Jupiter, though? It examined the physical makeup of these asteroids.
By analyzing 66-million-year-old rocks, the team determined that the Chicxulub asteroid had a similar makeup of the “carbonaceous chondrite impactors” found in the asteroid belt.
Looking deep into space at the asteroid belt, though, the team determined that similar asteroids could not be found — most were significantly smaller, clocking in at just one mile. With Chicxulub coming in at six miles, the team had to determine why other asteroids like Chicxulub couldn’t be found.
“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 the Chicxulub crater,” researcher, William Bottke, said in the study. “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.”
And they were — Chicxulub was no standard asteroid. It was a once-every-250-million-years kind of carbonaceous chondrite asteroid, and considering Chicxulub hit the earth 66 million years ago, there’s still theoretically another 184 million years to go until another asteroid of this size heads for Earth.
Ok, got it, so just to be sure: don’t be on Earth 184 million years from now — can do.
For more about the extinction of dinosaurs, check out this story about how some Harvard scientists have come up with a new theory on what caused the extinction and then read about how a T-rex fossil sold for $31.8 million last year. Check out this remarkably preserved dinosaur DNA preserved in a 75-million-year-old fossil after that.
Wesley LeBlanc is a freelance news writer, guide maker, and science guru for IGN. You can follow him on Twitter @LeBlancWes.
