Scottish crater proves threat to Earth is no movie fantasy
Huge asteroid impact site discovered in Scotland highlights the clear and present danger of astral bodies like the one which passed Earth recently
IN the somewhat fanciful plot of Hollywood blockbuster Armageddon, the “world’s greatest deep sea driller”, Harry Stiller – played by a stoic, steelyjawed Bruce Willis – has his unique skillset procured by Nasa and finds himself blasted off to the surface of an incoming asteroid to blow it out of the sky with a nuclear bomb.
Highly dubious science aside, Armageddon did serve to highlight a very real threat to the human race’s survival that is perhaps even more sobering than pandemics such as coronavirus – huge asteroids on a trajectory to Earth with the potential to wipe out much of the planet’s biological life.
Certainly, the astral body that flew past last month – Asteroid (52768) 1998 OR2, to give the two mile-long rock its Sunday name – would have wiped out much of the planet’s organic matter, if it hadn’t soared past at a relatively nearmiss of 16 times the Earth-Moon distance.
Asteroid (52768) was the biggest fly-by expected this year, with professional and amateur observers watching it pass as a slow-moving “star”. More visible to the naked eye, however – if life hadn’t been confined to the oceans at the time – would have been the huge object that smashed off the northwest coast of Scotland 1.5 billion years ago, an event recently discovered by geologists.
A team of UK researchers has uncovered signs of a huge asteroid collision in the Stac Fada deposit in the northwest Highlands, with rocks there containing high levels of chemicals found in asteroids.
They also detected quartz crystals which have been subjected to intense pressures and heat – leading researchers to believe they have pinpointed the exact spot where the asteroid hit.
Academics from the University of Oxford and the University of Exeter claim the impact crater lies between nine and 12 miles off the coast in the Minch, which separates the mainland from the Outer Hebrides.
Today, the spot is buried beneath water and rocks, rendering it inaccessible – so they pinpointed the possible site by studying the alignment of magnetic particles and distribution of debris thrown outwards at the time of the collision.
“If you imagine debris flowing out in a big cloud across the landscape, hugging the ground, eventually that material slows down and comes to rest,” said study author Kenneth Amor. “But it’s the stuff out in front that stops first while the stuff behind is still pushing forward and it overlaps what’s in front.
“That’s what we see and it gives us a strong directional indicator that we can trace backwards.”
The huge asteroid, estimated to have been between 0.6 and 1.2 miles wide, is believed to have struck when Scotland was a still a semi-arid environment located near the equator. Amor estimates the crater resulting from the impact spans almost nine miles in length, with a depth of around 1.9 miles – making it the biggest-ever astral collision ever discovered in the UK. Experts believe meteorite strikes were relatively common billions of years ago, as Earth and other planets were pelted with debris left over from the formation of the solar system.
Amor says the new research marks such an exciting discovery because impact craters typically erode over time. “It was purely by chance that this one landed in an ancient rift valley where fresh sediment quickly covered the debris to preserve it,” he stated.
Now that the crater’s possible location has been discovered, scientists aim to conduct targeted, 3D geophysical surveys of the Minch Basin.
High-resolution surveys could help the research team get a better sense of the dimensions of the crater – and it might even have important implications for other celestial bodies if we learn more about their composition and trajectory.
“Impact craters on Earth are exceedingly rare,” Amor said. “The better we can understand how they formed the better we can understand observations on the rocky planets and moons of the solar system.”
It was purely by chance that this particular asteroid landed in an ancient rift valley where fresh sediment quickly covered the debris to preserve it