On a seemingly ordinary day 66 million years ago, Earth experienced a sudden and catastrophic event that led to the extinction of approximately 75% of all life forms on the planet. In an instant, a colossal asteroid, measuring between 11 and 81 kilometers in diameter, crashed into the Earth, forever altering its landscape and ecosystems.

In a flash, the asteroid penetrated the atmosphere, impacting the shallow waters of a sea with catastrophic force. The energy released was greater than 10,000 times that of all the nuclear weapons in the world combined. A massive fireball erupted, incinerating everything in its path, while a shockwave spread across the globe, triggering tsunamis, landslides, and volcanic activity. The skies darkened, temperatures plummeted, and within a few years, three-quarters of Earth's species, including the mighty dinosaurs, faced extinction.

The asteroid, speeding towards the Yucatán Peninsula in Mexico, was so massive that it didn’t merely enter the atmosphere; it obliterated the air above a chain of ancient volcanic islands in a split second. Upon impact, the shallow sea—barely 100 meters deep—was vaporized almost instantly, sending massive waves in all directions.

The impact created a crater over 100 kilometers wide and 30 kilometers deep within seconds, ejecting pulverized rock and debris high into the atmosphere. The force of the collision equated to that of 100 million atomic bombs.

Yet the devastation was just beginning. A colossal blastwave radiated outward at speeds of around 70,000 km/h, flattening forests and sending creatures flying hundreds of kilometers away. The aftermath included a vacuum effect that caused winds to reverse and return to the impact site with cyclonic fury.

Meanwhile, the sea at the impact site surged over 100 meters into the sky, creating tsunamis that traveled toward Africa and the Americas. Although the shallow waters lessened their intensity, waves would still have been towering by the time they reached the shores, wreaking havoc across continents.

Fossil evidence indicates that Texas experienced waves reaching up to 50 meters high, with boulders carried hundreds of kilometers inland. The planet convulsed under the weight of the impact, producing seismic activity measured at 10 to 13 on the Richter scale—far surpassing any recorded earthquake.

The shockwaves traveled across the globe, causing geological upheaval even in distant locations like the Indian Ocean. The aftermath was catastrophic for any life forms within sight of the impact; many were obliterated instantly, while others perished in the ensuing chaos.

At the heart of the impact, molten rock blasted high into the atmosphere, followed by massive quantities of debris that would soon rain down upon Earth, igniting widespread wildfires.

The skies lit up as nearly 200,000 km³ of material fell back, releasing energy equivalent to 30 times that of sunlight. The intense heat ignited forest fires worldwide, creating an inferno that led to a rapid rise in temperature. Within an hour, the heat energy reaching the surface could have been enough to cook the soil to 400°C, effectively turning the planet into an oven.

Surprisingly, some life managed to endure. Researchers believe that cloud cover may have shielded certain regions from the devastating effects of the heat pulse, while other areas faced dire consequences. The Earth's rotation caused the debris to fall unevenly, leading to varied levels of destruction across the globe.

In the aftermath, millions of species vanished. The dust and debris that lingered in the atmosphere blocked sunlight for months, leading to a prolonged winter that devastated plant life and collapsed food chains. The sudden drop in temperature, from a mild 20°C to as low as -20°C, left many herbivores and predators starving.

Extinctions are a natural part of evolution, with new species often rising to fill ecological niches. However, mass extinctions—such as the one that claimed the dinosaurs—are rare. The last such event occurred 66 million years ago, characterized by a rapid loss of species, including the dinosaurs, which had dominated the planet for millions of years.

Dinosaurs first appeared around 250 million years ago, thriving until the beginning of the Cretaceous period, roughly 144 million years ago. However, they began a gradual decline for reasons still under investigation. Ultimately, their reign ended abruptly with the arrival of a massive asteroid.

Paleontologists examining layers corresponding to 66 million years ago have discovered unprecedented amounts of carbon deposits, suggesting widespread forest fires and the destruction of countless animals. It's estimated that the fires consumed around 100 billion tonnes of organic material, with half being from plants and the rest from animals.

No large species survived the impact; only smaller mammals remained, capable of reproducing and thriving in the aftermath. These creatures, which survived by being adaptable and having diverse diets, eventually evolved into the mammals we know today.

In a profound way, the catastrophic asteroid impact that caused the extinction of the dinosaurs also paved the way for the evolution of mammals. Without this event, many modern species—including humans—might not exist.

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PROOF OF THE PAST

How do we know so much about that catastrophic day 66 million years ago? It’s the result of meticulous scientific research. The notion that a sudden event led to the extinction of the dinosaurs dates back to the 18th century, proposed by Georges Cuvier, a pioneer in paleontology. However, for a long time, the prevailing belief was that change occurred slowly, aligning with Darwinian evolution.

In the late 1960s, scientists began to suggest that a large asteroid or comet could have caused the extinction, but this idea faced skepticism due to a lack of concrete evidence.

In 1977, geologist Walter Alvarez and paleontologist Isabella Premoli Silva were studying ancient limestone layers in Gubbio, Italy. They discovered a thin layer marking the end of the dinosaur era, above which nearly 90% of plankton species had vanished. This led to questions about whether the layer represented a sudden event or a gradual accumulation.

Alvarez consulted his father, Luis Alvarez, who proposed testing for iridium—a metal rare on Earth but common in space. They found that this layer contained 30 times more iridium than surrounding layers, leading to the hypothesis of a massive extraterrestrial impact.

Their findings, published in 1980, sparked controversy, but subsequent discoveries of similar iridium-rich layers around the world solidified their theory. Shocked quartz—indicative of high-energy impacts—was also found, confirming the catastrophic nature of the event.

As evidence mounted, researchers searched for the impact site. In 1990, geologist Alan Hildebrand identified a 180 km crater off the coast of Yucatán, which matched the timing and characteristics needed to be the impact site.

This site was named Chicxulub, deriving from a nearby village and meaning ‘tail of the devil’ in the ancient Mayan language—a fitting name for the site of a deadly cosmic collision.