Did comets kill the dinosaurs? Sixty-five million years ago, 70 percent of all species then living on Earth disappeared within a very short time. This included the last of the great dinosaurs. One possibility is that a comet about 10 kilometers in size struck the Earth. Scientists think that the impact disrupted the environment by displacing great amounts of dirt and rocks into the air.

 
 
 

 

The explosion that this object must have caused was similar to the explosion a rock the size of Mount Everest, traveling 10 times faster than the fastest bullet, would cause if it hit the Earth. There is a 65-million-year-old crater from an impact of similar magnitude just off the coast of Mexico in the Yucatan Peninsula.

 

  
 

 

NASA knows of no asteroid or comet currently on a collision course with Earth. The probability of such a collision is quite small. In fact, as far as we can tell, no large object is likely to strike Earth any time in the next several hundred years.