Miracle Planet

A simulation of a 300 mile wide asteroid striking the Earth.

An impact with an iron bolide of this size would likely liberate an amount of energy equivalent to many trillions of megatons of TNT, regardless of where it struck. In 1961 the Soviet Union detonated the most powerful nuclear device ever built, a massive city killer called the "Tsar Bomba." It clocked in at "only" about 50 megatons.