Lately, most scientists have come to an agreement that a huge extinction event that happened around 66 million years ago was, indeed, caused by a huge asteroid hitting Earth. Around 75% of all life on the planet was wiped out, ending the era of dinosaurs that has been going on for hundreds of millions of years. All that devastating destruction was caused by a mere 10-kilometre space stone!
Mexico is home to a 150-kilometre crater that has been hiding under the Yucatan Peninsula for millions of years until it was finally discovered by Glen Penfield in late ’70. It was only 20 years later that the geologist could come back and take samples that would prove that it was, indeed, an impact crater – there was a gravity anomaly in the area, as well as tektites and shocked quartz found inside the crater. Scientists estimate that an asteroid roughly the size of Boston hit the Yucatan Peninsula, creating a shockwave and causing the biggest extinction event our planet has ever witnessed. But where did this space traveller come from, exactly?
Known as the Chicxulub asteroid because of the area in Mexico it hit, this space traveller was found to be a very regular ‘carbonaceous chondrite’ asteroid, which can be found all across and beyond our Solar System. But none of such asteroids known to astronomers are as big as the one that wiped out the dinosaurs! Which is a good thing, if you come to think of it, but scientists are still baffled as to where that asteroid actually came from.
It was apparent that such big asteroids weren’t hanging around anywhere close to Earth, that’s why their next guess was that it came from the outer asteroid belt. But what would make such a huge fellow change its trajectory and hit Earth directly? To answer that question, astronomers used the power of a supercomputer to create a model of various asteroids interacting with each other. It turned out that the gravitational forces of different asteroids, big and small, as well as thermal forces of the sun, could, indeed, pull a huge-sized asteroid and make it change its course towards the Earth.
Scientists from Harvard believe that it wasn’t just any asteroid, but a huge comet that was travelling on the outskirts of the Solar System. It was pulled in towards the sun by the gravitational field of Jupiter, then it came apart and a piece of the comet fell down to Earth, causing the appearance of the Chicxulub crater and a massive extinction of life on Earth. While asteroids aren’t always made of carbonaceous chondrite, comets that travel for long distances are usually made of this exact material. The good news is that space travellers of such size, whether it’s a comet or an asteroid, are likely to head towards Earth only once in 200 million years.