The similar dating of the two giant craters revealed that there were two asteroids related to the extinction of the dinosaurs.
Scientists confirm that the giant asteroid that crashed into Earth and wiped out the dinosaurs 66 million years ago was not alone. A second, smaller meteorite fell into the sea off the coast of West Africa, creating a large crater at the same time. This was a “catastrophic event”, generating a tsunami at least 800 m high that swept across the Atlantic Ocean, BBC reported on October 3.
Dr Uisdean Nicholson from Heriot-Watt University first found the Nadir crater in 2022, but was unsure how it actually formed. Now, Nicholson and his colleagues are certain that the 9km depression was caused by an asteroid crashing into the seabed. They have not been able to find the exact date of the event, or conclude whether it took place before or after the asteroid that caused the 180 km wide Chicxulub crater in Mexico and ended the reign of dinosaurs. But smaller asteroids also appeared at the end of the Cretaceous period when the dinosaurs became extinct. While falling through Earth’s atmosphere, it created a fireball.
“Imagine the asteroid hits Glasgow and you are 50 km away in Edinburgh. The fireball will be about 24 times the size of the Sun in the sky, enough to burn down trees in Edinburgh,” explained Nicholson.
A powerful, noisy airflow then formed, followed by a vibration similar to a level 7 earthquake. Huge amounts of water could be pushed off the seabed, then fall back down, creating unique traces. It is quite unusual for two such large asteroids in the solar system to crash into Earth in a short period of time, but the research team does not yet know the cause.
The asteroid created the 450 – 500 m wide Nadir crater. Scientists think it hit Earth at a speed of about 72,000 km/h. The event closest to its scale occurred in 1908 when a 50 m asteroid exploded over Siberia. Asteroid Nadir, as large as Bennu, is currently the most dangerous object flying near Earth. Scientists estimate the time Bennu could crash into Earth is September 24, 2182, according to NASA, but the risk is only 1/2,700.
There has never been an asteroid impact of this magnitude in human history, and researchers often have to look at erosion craters on Earth or other planets. To learn more about Nadir crater, Nicholson and his colleagues analyzed high-resolution 3D data from a geophysics company called TGS. Much of the crater was eroded, but this crater was well preserved, allowing them to closely examine each layer of rock.