The Chelyabinsk event was a warning shot. For all its terrifying power, it was a minor cosmic event. But what happens when something truly large strikes the Earth? To find the answer, we must become planetary detectives, searching for the scars of ancient collisions. Our own planet is a frustrating crime scene; the relentless action of wind, water, and tectonics erases evidence over millions of years. But our silent, unchanging Moon tells a different story. Its face is a ledger of cosmic violence, a record of 4.5 billion years of bombardment. As Carl Sagan noted, ‘The sky is calling to us.’ By studying these ancient wounds, we can read the history of our solar system and understand the profound role that catastrophic impacts have played in the story of life on Earth.

The Earth and Moon have shared the same neighborhood for billions of years, meaning they have been hit by space debris at roughly the same rate. The Moon, having no atmosphere or geological activity, preserves its craters almost perfectly. Earth does not. Plate tectonics recycles the crust, erosion wears down mountains, and oceans hide the evidence. Yet, we have found over 190 confirmed impact structures on Earth. By studying the size and frequency of craters on the Moon, we can estimate how often Earth has suffered similar impacts. The data tells a clear story: small impacts are common, while civilization-ending impacts are exceedingly rare, happening on timescales of tens of millions of years.

Around 66 million years ago, a six-mile-wide asteroid screamed out of the sky and slammed into the shallow sea where the Yucatán Peninsula is today. The impact, known as the Chicxulub event, released more than a billion times the energy of the atomic bombs dropped on Japan. It triggered a global firestorm, continent-spanning tsunamis, and plunged the world into a ‘nuclear winter’ as dust and soot choked the atmosphere, blocking sunlight for years. This catastrophic climate disruption led to the Cretaceous-Paleogene mass extinction, an event that wiped out 75% of all species on Earth, including the non-avian dinosaurs. The evidence for this event is a thin layer of iridium—an element rare on Earth but common in asteroids—found in rock strata all over the world, dating to precisely the same time.

For millions of years, the world of the dinosaurs was a stable system. Evolution proceeded, ecosystems thrived, and the climate was relatively constant. Then, in a single day, that stability was shattered. The Chicxulub impact is the ultimate example of the Stability and Change thinking lens. It reveals that Earth’s history is not a story of slow, gradual change alone. It is characterized by long periods of equilibrium, punctuated by brief, catastrophic events that cause rapid, transformative change. These rare but powerful events can completely reset the course of evolution. The extinction of the dinosaurs, for example, cleared the way for the rise of the mammals, eventually leading to us. We are, in a very real sense, the children of a cosmic catastrophe.