How large was the asteroid that formed the Chicxulub crater?

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The Chicxulub asteroid — Earth impact hazard An artist's rendering of the impact of a near-Earth object 66 million years ago in what is today the Caribbean region. Many scientists think that the collision of a large asteroid or comet nucleus with Earth triggered the mass extinction of dinosaurs and many other species near the end of the Cretaceous Period.

The asteroid responsible for forming the Chicxulub crater approximately 66 million years ago is estimated to have been 10 to 15 kilometers (6 to 9 miles) in diameter.123

This massive impact, which occurred off the coast of the Yucatán Peninsula in present-day Mexico, created a crater measuring roughly 180 kilometers (112 miles) across. Scientists determined these dimensions by analyzing the crater's contours and utilizing impact-scaling simulations, which also suggest the asteroid struck Earth at a speed of approximately 20 kilometers (12.5 miles) per second.123