Ancient asteroids struck Earth frequently, delayed rise of life - study
Some of these asteroids were around 10 kilometers in size, and struck the Earth 10 times as often as current models would have suggested.
An asteroid is shown in an artist's rendition crashing into Earth in an event that scientists believe occurred in the Caribbean region at the boundary of the Cretaceous and Tertiary periods in Earth's geologic history about 65 million years ago causing the extinction of dinosaurs. (photo credit: REUTERS)ByAARON REICH
