The Dino-Killing Asteroid Picked The Perfect Spot To Slam Into The Planet


Robin Andrews

Science & Policy Writer

Perfect timing. Triff/Shutterstock

A new BBC documentary, The Day The Dinosaurs Died, has aired just as the groundbreaking effort to drill into the famous impact crater’s central peak ring has come to an end. As is becoming increasingly obvious to researchers, the villainous 15-kilometer-wide (9.3 miles) asteroid hit one of the worst possible places on Earth.

The Chicxulub crater, which is a staggering 180 kilometers (112 miles) across and 20 kilometers (12 miles) deep, was created both on land and in shallower waters. This ensured that plenty of gypsum, a common rock type in the region, was vaporized and sent into the planet’s upper atmosphere.


Gypsum contains plenty of sulfur, which as an aerosol is remarkably effective at blocking out sunlight. The colossal plume of sulfur-rich dust persisted in skies all over the world for several decades, and perhaps centuries.

The global temperature drop forced the planet into a temporary ice age, which plenty of life was unprepared for. Add to this the fact that photosynthesis both on land and in the oceans would have abruptly shut down, resulting in the collapse of food chains across the planet, and you’ve got yourself a dinosaur-killing mass extinction event.

The impact itself was terrifying enough. Geological layers were instantaneously turned into a fluid, and within 10 seconds, a wave of rock 25 kilometers (16 miles) high splashed up into the sky. The impact even managed to crack open the crust in what is now North America. It was like a cannonball – traveling at 17 kilometers (10.6 miles) per second – smashing into a frozen pond.

The fireball would have incinerated anything in its path across a radius of hundreds of kilometers, and the forest fires that followed would have burned for many tens of thousands of years.


Ultimately, though, it was the extremely rapid sulfur-driven climate change that killed the non-avian dinosaurs, not the impact itself.

Don’t get us wrong: a deep ocean impact – which would have taken place if the asteroid’s arrival was delayed by just a few seconds – would have been verifiably catastrophic. It would have still generated a massive fireball, and a megatsunami of Biblical proportions would have swept across several continents, killing a cornucopia of living things within and without.

However, a Pacific Ocean impact may have been “soft” enough to ensure that the reign of the dinosaurs may have continued, and the mass extinction event that wiped out 75 percent of all life may have been averted.

In any case, as impressive as Chicxulub is, it’s not the biggest crater we’ve ever discovered on Earth. The winner of this accolade goes to the collapsed 2.02-billion-year-old Vredefort crater in South Africa, which was once a staggering 300 kilometers (186 miles) across.


The world's largest impact crater can be found in South Africa. Julio Reis/Wikimedia Commons; Public Domain

[H/T: BBC News]


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