“Panel confirms dino crater link”, BBC News, 4/3. After much debate, various experts have decided that the culprit for making the dinosaurs extinct was an asteroid after all – the one that caused the crater at Chicxulub.
The review confirms that a unique layer of debris [iridium] ejected from a crater is compositionally linked to the Mexican crater and is also coincident with rocks associated at the Cretaceous-Tertiary (K-T) boundary.
The team also says that an abundance of shocked quartz in rock layers across the world at the K-T boundary lends further weight to conclusions that a massive meteorite impact happened at the time of the mass extinction. This form of the mineral occurs when rocks have been hit very quickly by a massive force. It is only found at nuclear explosion sites and at asteroid impact sites.
“Combining all available data from different science disciplines led us to conclude that a large asteroid impact 65 million years ago in modern day Mexico was the major cause of the mass extinctions,” said author Dr. Peter Schulte, assistant professor at the University of Erlangen in Germany.
There have been 5 major extinction events to date; the most extensive one was earlier than the K-T, the Permian–Triassic extinction event 251 million years ago which killed off most Earth life (the cause of this is unknown). I suspect the next major event will involve humanity (human-caused extinction of other life forms is already happening). If that eventuates, I wonder what will evolve to replace us. I doubt they would have the same type of intelligence as us, so they may not develop anything we recognize as technology or a civilization, and so no archaeologists to dig up our artifacts. In that case humans will just be another forgotten footnote in Earth’s long history.
If time travel were possible, I would (like many) love to go back and see the dinosaurs (though preferably not get eaten!). Earth then would be like an alien planet – the atmosphere (more oxygen), the sun (younger and hotter), different plants and creatures. The Moon would appear larger in the sky as it was closer (it is moving away about 3.8 cm per year, so 75 million years ago it would be 2850 km closer, if my calculation is correct). The days would be a little shorter (a day was 21.9 hours long 620 million years ago). So things would be familiar yet strange.
If an asteroid or comet were to approach Earth on an impact trajectory, there would be nothing we could do with current technologies, even if it were detected in time. Stephen Baxter’s novel Titan (possibly the gloomiest novel ever written!) has such a scenario, though this asteroid is a human-induced impact. The extract below describes the nightmarish moment of impact:
It came in at an angle, far to the east, a blindingly white line scrawled across the sky. It was a crack in the Aristotelian dome, Fahy thought, allowing in the monsters.
Asteroid 2002OA had arrived.
She had to turn away, it was so bright.
It was going to be an ocean strike, then. Just as NORAD predicted. A few hundred miles off the coast, she guessed.
The dazzling light had faded now.
So it was true. She thought she’d imagined, with some soft unscientific part of her, until this moment, that it might be just some fantastic hypothesis.
Well, Earth hadn’t suffered a strike like this for millions of years. Human written culture went back maybe five thousand years. There was no institutional memory of such an event as this. No wonder it was hard to comprehend, even to plan for. It should be.
Clouds were boiling, scudding across the sky. The spectacle was playing out in an eerie silence. Even the traffic noises seemed to have stilled.
The atmosphere would have provided no effective shield against the strike; the asteroid must have reached the ocean with no significant loss of mass or velocity: a mountainous mass of rock, moving at orbital speeds, through the delicate atmosphere of Earth. There was essentially an immense cylindrical explosion going on right now, its effects scouring outwards over the surface of the planet.
From orbit, she thought, it would be a hell of a sight: the crater still visible, a glowing red puncture miles across, keeping the sea at bay with its raw heat; an immense column of dust and pulverized rock and vapor rising up above it, its lip extending tens of miles into the atmosphere; the clouds bubbling outwards in ranks, like the concentric rings around a bull’s eye target.
A breeze, warm and heavy, pushed against her face, pressing from the east. There were flecks of moisture on the wind. She licked her lips. Salt: ocean water, scooped up and hurled across hundreds of miles.
Maybe there would be tsunamis. But the geometry was dicey; it depended precisely where the impact was, the topography of the ocean bed. Gradual slopes could reflect the wave energy back to the Atlantic…
There was noise now, at last, a deep bass rumble like remote thunder. The light continued to fade.
The ground shifted, the solid marble of the Memorial’s vast plinth shuddering like a live thing.
For the first time, she was scared. The ground wasn’t supposed to move under you, damn it. It was as if some deep superstitious part of her had woken, an animal peering up at a violent sky in terror.
Dark, thick storm clouds streamed over the sky above Fahy, obscuring the sun. Rain started to fall, big droplets, pelting against the marble surfaces, her clothes and hair, heavy and warm and salty.
She permitted herself a fragment of hope. After all she wasn’t dead yet. The strike itself was over. The world was going to be a piece of shit after this, war or not; but maybe, just maybe, she might live through this to see it.
Maybe NORAD and the rest had miscalculated, she thought. Maybe 2002OA just wasn’t a big enough punch to –
But there was something on the horizon, now: a grey wall, perhaps a bank of cloud.
Oh.
The secondary effects need not concern her any more, she thought.
The wall was water, a bank of it that had to be a mile high. Already it was marching inland. Even from this distance she could see debris embedded in its curving, steel-grey flank: rocks, fragments of ships, pieces of smashed-up buildings. It was the debris that would do the damage, she knew; with its help that wave could scour the ground clean of any sign this capital city had ever existed.
We don’t deserve this, she thought. Although maybe it looks different if you sit in Beijing. And there are those who say something like this, some terrible conclusion, was inevitable, that the huge technological project we’ve been following was bound to end in grief and destruction.
But I know we don’t deserve to have this done to us. Sure, we got things wrong. And we’re guilty of being the only nation in history to have dropped an atomic weapon on an opponent. But didn’t we beat back the Nazis and the Japs? Wasn’t it a good thing that we won the Cold War, and not the other side? Was it really such a terrible thing, to aspire to walk on the moons of Saturn…?
I will, she thought, never see the sun again.
She felt a wrench, a deep sorrow.
The clouds thickened, and moist air buffeted her face, driven ahead of that horizon-spanning piston of water.
