A Bad Day to be a Dinosaur
ABOUT 66 million years ago, dinosaurs of many different shapes roamed the Earth. If you were a dinosaur, you’d be rather happy with your environment, and blissfully unaware of the fact that the story of your species was about to come to a dramatic end – George R. R. Martin style.
Hurtling through space at a speed of 72,000km/h – a speed at which you could go around the entire Earth in a little over ten minutes – an asteroid had its sights set on the third planet from the Sun.
This particular celestial body, left over from the creation of our solar system, was about 10km across, and had a similar density to aluminium.
About 66 million years ago, the last day of the Mesozoic era, was the last day that most dinosaurs would roam the Earth.
The asteroid collided into the Earth with devastating effect, landing in what we now call the Yucatán Peninsula, in southeast Mexico. The Chicxulub Impactor – named after the now nearby town – created an explosion that was 37.4 billion times more powerful than the Hiroshima nuclear bomb. Yes, that was billion, as in 37,400,000,000.
Using the Impact Calculator website, we can determine the effects of these ‘end-of-days’ asteroid events and can imagine what it would have been like to be there.
Let’s pretend you were there on this day. Spoiler alert: you’re not going to survive. If you weren’t out swimming in the lovely Yucatán Peninsula waters where the asteroid created an incredible 163km-wide crater, then unfortunately your demise would have been much worse. Almost 9,500 cubic kilometres of dirt, rock and water from the impact zone was instantly melted or vaporised, meaning a quick end to your story.
What if you were further away? If you were about 250km away, which is roughly the distance you’d have to travel to get from Melbourne to Wangaratta, would you even know it had happened?
Turns out, after seeing the fireball – which, mind you, would have a radius of 225km and would appear 204 times larger than the Sun – you would have about 11 seconds before an intense heatwave hits you. This thermal radiation would be so hot, that your clothes would instantly ignite, as well the trees and the grass around you.
However, for the sake of curiosity, let’s pretend that you’re some enhanced cyborg with the power to withstand third degree burns to your entire body. You would then have another 40 seconds to survey the hellish landscape surrounding you before a 10.3 magnitude earthquake hits. This earthquake would be more powerful than anything ever recorded in human history. The Mercalli Scale suggests that “most masonry and frame structures [would be] destroyed”. In other words, total carnage.
It’s not over yet!
Still standing? The ejecta cloud is on its way! By the time it reaches you – which only takes just under 4 minutes – this blanket of matter thrown outwards from the impact will be travelling at over 3,900km/h, and will have an average thickness of 56 metres. That’s higher than an 18-storey building. With an average fragment size of 11cm where you are – think hail, except superheated and made of rocks – simply putting up your umbrella won’t protect you.
If, by some miracle, you found a structure that hadn’t been destroyed yet, and you were taking shelter, you’d have about another 8 minutes until the blast of air arrives. But this isn’t any ordinary gust of wind; it’ll have a speed of 7,800km/h, and will effectively level anything that is left standing. Buildings? Gone. Bridges? Collapsed. Trees? Up to 90% would be blown away, and the rest would no longer have branches or leaves. You’d also be thankful if you had a good pair of earmuffs, since the sound of the air blast would reach 137dB, which is just short of the threshold of pain in humans.
In short, let’s cross our fingers and hope that no asteroids have us targeted in the near future.