The Los Alamos Lab simulation of the Chicxulub impact used a closing velocity of 15 to 20 kilometers per second for the impactor. “At impact, the asteroid is estimated to have been traveling at 20 kilometers per second (44,640 miles per hour), roughly 20 times the speed of a rifle bullet,” the university said in a news statement. Taking the low end, 15 km/s is about 62 times the speed of sound at the outer shell of the atmosphere, 100 km high.

It isn’t possible to know. 65 million years ago, a massive asteroid crashed into Mexico's Yucatan Peninsula — a site now known as the Chicxulub Crater. Impacts of this size on Earth are thought to happen on average about once every hundred million years. However, various estimates, based on presumed size, impact crater width & depth, lead some scientists to suppose between 35,000 & 60,000 miles per hour. In 1980 there was no known impact structure, which could be responsible for this extinction. Photograph by Faith Tucker, NASA ... such as the asteroid’s size and speed, to paint a vivid picture of events. Illustration courtesy of NASA In 1980, Alvarez and colleagues proposed that, in the transition from the Cretaceous to Paleogene, a large impactor collided with Earth being the cause of the mass extinction occurred at the limit K / Pg. This cataclysmic event that triggered a world-wide tsunami and disrupted global climates has been linked to the extinction of the dinosaurs and up to 75% of all other life. This is a piece of the asteroid that made the Chicxulub Crater.