Sixty-six million years ago, an asteroid slammed into the Earth's atmosphere, traveling 45,000 miles per hour. The asteroid ripped a hole 18 miles deep in the Earth's crust, triggering devastating winds, seismic waves, and tsunamis. For decades, scientists have hypothesized that the asteroid wiped out the dinosaurs. The debris thrown into the atmosphere blocked out the sun, wiping out plants, and then herbivores, and then carnivores. And now, recently uncovered evidence provides a snapshot of exactly what happened on the day of the impact.