Minor Planets

A total of 130 impact craters have been identified on Earth's surface, the largest of which is the Sudbury crater in Canada. The sizes of the known terrestrial craters vary from approximately 100 ft (30 m) in size to 200 mi (320 km) or more in diameter.

The last globally catastrophic collision between Earth and an asteroid probably took place 65 million years ago at the end of the Cretaceous period. It now seems reasonably likely that the extinction of many species, including the great dinosaur extinction which occurred at the Cretaceous-Tertiary boundary, was caused by the impact of an asteroid approximately 6.2 mi (10 km) in diameter. The submerged remnants of the giant impact crater produced in this terminal Cretaceous collision were recently discovered on the coast of the Yucatan peninsula in Mexico. The crater, Chixulub (pronounced CHIKS-a-lub), is approximately 112 mi (180 km) in diameter and has long been buried under coastal sediments.