Using estimates of the total amount of iridium in the K–Pg layer, and assuming that the asteroid contained the normal percentage of iridium found in chondrites, the Alvarez team went on to calculate the size of the asteroid. The answer was about 10 km (6.2 mi) in diameter, about the size of Manhattan.[5] Such a large impact would have had approximately the energy of 100 trillion tons of TNT, or about 2 million times greater than the most powerful thermonuclear bomb ever tested.

Cretaceous–Paleogene boundary - Wikipedia, the free encyclopedia Tuesday, April 1, 2014 @ 10:51pm