Monster asteroids like the one that wiped out dinosaurs feared to be more common than previously thought, study says

MONSTEROUS asteroids such as the one that wiped out dinosaurs millions of years ago could be more common than previously thought, a new study has found.

The asteroid that caused the extinction of dinosaurs, known as the Chicxulub impactor, is believed to have crashed into Earth around 66 million years ago.

The rock, estimated to have been 7.5 miles wide, produced a blast equal to 100 million megatons - or the force of 10 billion WWII-era atomic bombs - when it crashed into the Gulf of Mexico, wiping out 75 percent of life.

Scientists believe the force of the strike was enough to trigger wildfires, tsunamis, and blast so much dust into the atmosphere that it blocked out the sun, plunging the planet into darkness.

The impact first triggered an inferno, scientists believe, enough to scorch plants thousands of miles away. The dust then caused temperatures to plummet in a "nuclear winter", freezing many surviving creatures, plants, and vegetation.

WHERE DID IT COME FROM?

Scientists have previously theorized where the Chicxulub impactor came from and how often similar events have happened in the Earth's 4.3 billion years of life.

Hoping to answer those questions, experts with the Department of Space Studies at the Southwest Research Institute (SRI) in Colorado used a NASA supercomputer to reconstruct how asteroids from the outer half of the asteroid belt might come to collide with Earth.

"We decided to look for where the siblings of the Chicxulub impactor might be hiding," David Nesvorný, lead author of the study, said.

The asteroid belt is 92 million miles in width and circles the sun between the orbit of Mars and Jupiter.

Scientists found that asteroids that are the same size as the Chicxulub impactor actually hit Earth at least 10 times more often than previously thought.

Such impacts, however, remain incredibly rare.

'SPECIAL CIRCUMSTANCE'

The SRI study found that asteroids that are three miles wide or larger hit the Earth between once every 16 billion and 32 billion years.

The SRI paper also states that the Chicxulub impactor is likely to have come from a distant part of the asteroid belt and its chemical composition is unusual.

That finding led researchers to determine that the Chicxulub impactor was a "special circumstance."

Further, samples taken from around the site of the strike suggest the asteroid had a carbonaceous chondrite composition, described in the study as "quite rare."

"This work will help us better understand the nature of the Chicxulub impact, while also telling us where other large impactors from Earth's deep past might have originated," Nesvorný said.

DINOSAURS DOOMED BEFORE STRIKE?

It comes just weeks after a report released in the journal Nature Communications that suggested that dinosaurs were in decline for as many as 10 million years before the Chicxulub impact.

The apparent decline happened worldwide and affected both carnivorous groups such as Tyrannosaurs, and herbivorous groups such as Triceratops.

While the cause of the decline remains up for debate, one contributing factor may have been climate change. During that period, the Earth cooled globally by around 7-8C.

Dinosaurs needed a warmer climate for their metabolism to function properly.

"They were not ectothermic (cold-blooded) animals like crocodiles or lizards, nor endothermic (warm-blooded), like mammals or birds," the study explained.

"They were mesotherms, a metabolic system between reptiles and mammals, and needed a warm climate to maintain their temperature and thus perform basic biological functions. This temperature decrease must have had a very strong impact on them."

The study was unable to speak as to whether dinosaurs would have gone extinct anyway, even without the Chicxulub impact.

"It's difficult to say. Many palaeontologists believe that if the dinosaurs had survived, primates and therefore humans would never have appeared on Earth.

"What we can say is that the ecosystems at the end of the Cretaceous period were under significant pressure due to climatic deterioration and major changes in vegetation - and that the asteroid dealt the final blow."