DIDI YOU KNOW? 66 million years ago, an asteroid with a diameter of 6.2 to 9.3 miles (10 to 15 kilometers) hit the Yucatan peninsula – at the time still a shallow sea. The Chicxulub impact had a force of at least 200 million Hiroshima bombs and directly as well as indirectly caused the extinction of up to 75 percent of all plant and animal species living at that time.