Just be glad that you live in this particular chapter of life’s history on Earth. Be glad that you weren’t around when the asteroid that formed the Chicxulub crater hit and be really, really, really glad you weren’t around when one about 4X as big plopped down well before that. About 3.26 billion years ago, a 57km wide asteroid smacked the earth traveling 72,000 kph and created a crater that would have measured 500km wide. Since no actual crater of this geological puncture wound remains, scientists have recreated what the impact site may have looked like for the first time.
The sizes of the Chicxulub crater asteroid (the one thought to have caused the Cretaceous-Paleogene extinction event) and the much larger asteroid that touched down 3.26 billion years ago as compared to an oddly lush and forested Mount Everest. (American Geophysical Union)
Life on Earth sprouted at around 3.8 billion years ago, which would mean it was still in its elementary stages by the time this asteroid hit. Upon impact, the top layers of the ocean would have immediately boiled and the air would have become incredibly hot and dusty. Talk about a rough childhood. But in the words of chaotician Dr. Ian Malcolm “life – uh – finds a way.” When all those wimpy life forms who couldn’t weather an asteroid impact died off, the remaining survivors must have evolved to fill their niches, continuing the march towards later periods of truly rich biodiversity.
The comparative size of each asteroid’s crater compared with Hawaii’s big island. (American Geophysical Union)
It’s probably a good thing those primitive life forms hadn’t developed brains at this point in the Earth’s history, because it was a pretty terrifying time to be alive. Asteroid impacts were thought to be relatively common, and the monster in question here would have set off a hell storm of tsunamis and 10.8 magnitude earthquakes. However, the massive impact may have set another geological phenomenon in motion as well – plate tectonics. At present, the convection of the Earth’s hot liquid mantle moves the plates of the earth around, but the planet may have needed a massive impact event to shake up the crust and get that process started. According to Simon Redfern at the University of Cambridge, “Even with a hot mantle you would need something to destabilise the crust.”
We’re all lucky to live a in a relatively impact-free era of the earth’s history. How do you like the odds of it staying that way in your lifetime? Express your terror in the comment section below. For more on how we might be able to prevent an asteroid impact from a way, way smaller asteroid than this one, check out this How-To for nuking an asteroid.