One of the largest collisions by an extraterrestrial object with the Earth was the Chicxulub hit, 66 million years ago. The asteroid is estimated to have been six to nine miles in circumference. Its impact created an impact crater more than a hundred miles across and twelve miles deep. It was only discovered in 1978 by Glen Penfield, who was conducting fieldwork for the Mexican oil corporation Pemex. It takes its name from the town nearest the center of the impact, Chicxulub, in Mexico’s Yucatan Peninsula. The impact would have released an almost inconceivable amount of energy, equivalent to thousands of times the energy potential of all the nuclear weapons existing in the world. The impact was a catastrophe for life on Earth, causing the extinction of perhaps three fourths of all species then existing. It did in the dinosaurs.