How many megatons was the pre-historic chixculub meteor impact equal to? This was estimated to be millions of times more powerful than the cumulative explosive power of all of the nuclear weapons in the world combined. It caused the extinction of most life on Earth during that time (namely the dinosaurs) and even caused the oceans to evaporate. This meteor was about 6 miles in diameter. If a 6-mile meteor is capable of doing that, imagine the kind of damage an asteroid the size of Texas could do.