The Asteroid That Extincted the Dinosaurs Was Not Alone

Scientists say that the massive asteroid that struck Earth 66 million years ago and led to the extinction of the dinosaurs was not alone, as a smaller asteroid also collided with our planet during the same period. Detailed scans of an underwater crater near the coast of Guinea in West Africa show that this crater was formed by the impact of a large asteroid at the end of the Cretaceous period. This crater, known as Nadir, was first discovered in 2022 by Dr. Oysdin Nicholson, a marine geologist from Heriot-Watt University in Edinburgh, but its exact origin was unclear at that time. Now, Dr. Nicholson and his colleagues have confirmed, using high-resolution 3D seismic imaging, that this 9-kilometer depression is the result of an asteroid striking the seabed. The impact of this asteroid, which was about 450 to 500 meters in diameter and struck Earth at a speed of approximately 72,000 kilometers per hour, created a crater about 9 kilometers in diameter. Although this asteroid was smaller than the one that created the 180-kilometer Chicxulub crater in Mexico, it was still large enough to have significant effects on the planet. The impact of this asteroid was catastrophic, causing severe tremors that liquefied sediments beneath the ocean floor and created faults under the seabed. Additionally, a massive tsunami at least 800 meters high was generated, likely traveling across the Atlantic Ocean. Scientists say that large amounts of water were expelled from the seabed and then flowed down, creating unique effects on the seafloor. The occurrence of two large asteroids striking Earth in a short time frame is very rare. Scientists do not know why these two asteroids reached Earth so closely together, but they suspect that these impacts may have been part of a series of meteorite and asteroid collisions with Earth at the end of the Cretaceous period, which ended the 165 million years of dinosaur dominance on Earth. The Nadir asteroid was nearly the size of Bennu, which is currently recognized as the most dangerous near-Earth object. According to NASA, there is a possibility of the Bennu asteroid colliding with Earth on September 24, 2182, but this probability is only 1 in 2700. The 3D seismic imaging technique used for this study has provided an unprecedented opportunity for scientists to test hypotheses related to impact craters and develop new models for crater formation in marine environments. Dr. Nicholson states, 'This is the first time we have been able to see inside an impact crater in this way—it's really exciting. There are only about 20 marine craters in the world, and none have been studied with this level of detail.' Scientists hope to gain a better understanding of the history of asteroid impacts on Earth and their effects on the planet's life. This research could help us be better prepared for similar events in the future and answer more questions about how the dinosaurs went extinct.