On the last day of the Cretaceous period, a 7.5-mile-wide asteroid slammed into Mexico’s Yucatán Peninsula and changed the arc of life on Earth. Sixty-six million years later, scientists have used supercomputers to re-create the devastation of that infamous impact in unprecedented detail. The models are helping to solve a longstanding mystery about what killed off all dinosaurs except birds and offering a new glimpse at how life on Earth responds to rapid environmental change.

Scientists already knew that the extraterrestrial impactor blew a crater roughly 120 miles wide into Earth’s crust, hitting in just the right spot—and at just the right angle—to fling colossal amounts of cooling gases and soot into the upper atmosphere. Skies blackened as