More than 66 million years ago, Earth experienced one of the greatest transformations in its history when a giant asteroid struck the Yucatan Peninsula in Mexico, leaving behind a huge crater that changed the course of life on the planet.
Since the discovery of the Chicxulub crater in the 1970s, the prevailing scientific view has been that dust blocking sunlight led to a long "collision winter" that caused the collapse of food chains and the extinction of the dinosaurs.
However, a recent study suggests that the disaster began more violently, with massive firestorms possibly sweeping across the Earth in the first hours after the impact, wiping out huge numbers of living organisms before the global winter began.
The study was published on July 28 in the journal JGR Biogeosciences, and was conducted by researchers from Purdue University in the United States, led by planetary scientist Brandon Johnson.
A collision that changed the face of the Earth
The study indicates that the asteroid, which was about 10 kilometers in diameter, collided with Earth at a tremendous speed, causing a large part of the rocks at the impact site to vaporize and turn into extremely hot steam.
As part of this vapor cooled, tiny rocky balls formed and spread around the world before falling back through the atmosphere at speeds of several kilometers per second.
A drawing depicting the moment a giant asteroid collided with Earth's surface, accompanied by a massive explosion and a giant meteorite crater.
A drawing depicting the moment a giant asteroid collided with Earth's surface, accompanied by a massive explosion and a giant meteorite crater (Spacecom).
Previous models suggested that friction of these particles with the atmosphere unleashed a powerful heat wave, similar to a global grill, capable of killing animals with thin, exposed skin, but not enough to ignite widespread fires in the vegetation.
However, researchers believe that these models overlooked a crucial element: a thick layer of fine silicate dust resulting from the evaporated rocks, which did not turn into those rocky spheres.
Dust trapped the heat and turned the ground into a furnace.
The outlines of this hypothesis began to strengthen in 2023 after the discovery of a very thin layer of impact dust at the Tanis fossil site in North Dakota, directly above the rock spheres layer. A similar layer was then found at the boundary between the Cretaceous and Paleogene periods in the Raton Basin on the border between Colorado and New Mexico.
The dinosaurs didn't die from the cold alone... they probably burned within hours!
The researchers point out that this dust acted like a huge thermal blanket, preventing a large portion of the thermal radiation from escaping into space and redirecting it towards the Earth's surface.
According to their calculations, the surface heat wave became about 3.5 times stronger than previous estimates that relied on the falling rock balls alone.
Brandon Johnson, a researcher at Purdue University, said: "This discovery revived my interest in what happened to the remaining steam, and that's where this study began, as we reached a point where we might be facing a scenario that eliminates almost everything within the first hour or two."
Deadly heat fueled the fires
The study explains that the resulting thermal radiation may not have been sufficient to ignite thick tree trunks directly, but it exceeded the limits necessary to ignite grasses, lichens, and pine needles, providing natural fuel for large-scale fires that spread across vast areas.
The calculations also indicate that the exposed wild animals may have been exposed to a heat dose equivalent to 17 times the heat dose that is lethal to humans, which means that many creatures may have died within a very short period after the collision.
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