Dinosaur-destroying meteor struck at ‘deadliest possible’ angle
The flaming space rock that slammed into Earth and wiped out the dinosaurs struck at the worst possible angle, new research suggests. Colliding with an enormous, fastmoving cosmic projectile would have been disastrous under just about any circumstances, but it also hit the planet at a steep angle, causing the deadliest possible outcome by releasing much more gas and pulverised rock than it would have with a shallower approach.
Scientists modelled the path of the meteor as it hurtled towards Earth, creating the first 3D simulations to trace the event from start to finish. The asteroid closed in on its target from the northeast and struck at an angle of about 60 degrees above the horizon.
That crash was around 66 million years ago, ending the Mesozoic Era with a bang. The event triggered global climate change and led to mass extinction, wiping out 75 per cent of all life on Earth, including all non-avian dinosaurs. A scar from the impact remains to this day as a massive circular basin underneath Mexico’s Yucatán Peninsula, known as the Chicxulub crater and measuring around 200 kilometres wide.
In the researchers’ simulations they modelled an asteroid measuring about 17 kilometres in diameter, travelling at approximately 43,200 kilometres per hour and with a density of 2,630 kilograms per cubic metre.
They also examined asymmetrical structures in the crater at subsurface depths of nearly 30 kilometres to visualise the direction and angle of the asteroid as it struck. Though previous studies have modelled the crater’s appearance at the moment of impact, this is the first time that researchers have used deeper structural data to model the crater during the impact’s later stages, as it shifted and settled into its final shape. Working backwards from this formation gave the scientists a more accurate view of the asteroid’s approach.
Compared with most other impact angles, ejecta from such an impact would have produced ‘the worst-case scenario’ for the planet, spewing up to three times as much sulphur and carbon dioxide into the atmosphere as other impact angles did, the models showed.
This steep-angled trajectory “was among the worst-case scenarios for the lethality on impact,” said lead study author Gareth Collins. “It put more hazardous debris into the upper atmosphere and scattered it everywhere – the very thing that led to a nuclear winter.”