 Imagine a storm big enough to swallow the Earth, with 300-mph winds that could smash our cities to rubble and keep on raging for 300 years, after all signs of life had disappeared. Imagine an unstoppable, mile-high wall of choking dust and sand, devouring the Earth at half the speed of sound, until every square foot of land was sandblasted to oblivion. Imagine lightning bolts exploding with the energy of atomic blasts. And imagine a rain of deadly radiation ripping our atmosphere apart, until all life was extinct.