Dinosaur Asteroid Size and Dimensions
The dinosaur-killing asteroid was roughly 10 to 15 kilometers (about 6 to 9 miles) wide. This size is based on crater evidence and impact models. At that scale, it was far larger than most near-Earth asteroids people encounter today.
Impact Speed and Crater Scale
The asteroid struck Earth at an estimated speed of about 20 kilometers per second. The collision created the Chicxulub crater, which is around 180 kilometers (110 miles) wide. The energy released was equivalent to billions of atomic bombs.
Why Size Mattered for Extinction
Its large size allowed the asteroid to punch through the atmosphere and excavate massive amounts of rock and dust. This triggered global climate changes that disrupted food chains and led to the extinction of about 75 percent of species, including non-avian dinosaurs. For more details, see NASA's overview of the Chicxulub impact.
