The comet that wiped out the dinosaurs travelled 186 billion miles before being "pinballed" by Jupiter, research has found.
Harvard scientists reckon the 10-mile wide space rock started off as debris from the Oort Cloud at the edge of the Solar System.
Their new theory says it was pulled out of its orbit by Jupiter before the Sun ripped it apart and sent bits smashing into the Earth.
Harvard's top astronomer Professor Avi Loeb and astrophysicist Amir Siraj said their predictions matches with the dates of other massive craters on Earths.
Mr Siraj said: "Basically, Jupiter acts as a kind of pinball machine.
"Jupiter kicks these incoming long-period comets into orbits that bring them very close to the Sun."
Mystery surrounds the origin of the devastating impact 66 million years ago triggered the extinction of the dinosaurs.
The Chicxulub impactor also saw the extinction of nearly three-quarters of all plant and animal species on Earth.
Previous studies have suggested the resulting crater off the coast of Mexico that spans 93 miles and goes 12 miles deep came from the asteroid belt between Mars and Jupiter.
But the new study has now claimed that a significant fraction of the dino-killing comet was a "sun grazer" from the Oort cloud.
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Those are debris at the very edge of the Solar system 186 billion miles away that end up slinging round the Sun as comets.
Prof Loeb and Mr Siraj's calculations suggested that about 20 percent of "long-period comets" become sun grazers – which fits into findings from previous research.
And their statistical analysis and gravity simulations showed they could slam into Earth every 250 to 730 million years.
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That's ten times more often than current estimates, and they claimed matches with dating of other massive craters on Earth.
The pair said in the paper: "Our hypothesis predicts that other Chicxulub-size craters on Earth are more likely to correspond to an impactor with a primitive (carbonaceous chondrite) composition than expected from the conventional main-belt asteroids."
Prof Loeb added: "Our paper provides a basis for explaining the occurrence of this event.
"We are suggesting that, in fact, if you break up an object as it comes close to the sun, it could give rise to the appropriate event rate and also the kind of impact that killed the dinosaurs."
Mr Siraj said: "When you have these sun grazers, it's not so much the melting that goes on, which is a pretty small fraction relative to the total mass, but the comet is so close to the sun that the part that's closer to the sun feels a stronger gravitational pull than the part that is farther from the sun, causing a tidal force.
"You get what's called a tidal disruption event and so these large comets that come really close to the sun break up into smaller comets. And basically, on their way out, there's a statistical chance that these smaller comets hit the Earth."
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