Ethan Siegel, It Starts With a Bang on Medium:
If one of these objects were destined to hit us, we presently have no way to stop it, especially if we realized it at the last minute.
So imagine there were someone who could stop it. Imagine you’re a superhero. Not a rich playboy like Batman or Iron Man; not a normal human who fell into great power like Spider-Man or The Flash; not even a hero from another world with power well beyond any Earth creature like Superman or Thor. Imagine that you’re just a normal human who’s trained hard to become the strongest hero, and from what you can tell, perhaps that’s exactly what you are. Now you’ve got to face your toughest challenge ever: a meteor the size of a small mountain is headed towards Earth, and the impact is slated to occur right in your city in a matter of seconds. When it hits, if nothing slows it down, it will release tens of thousands of Megatons’ worth of TNT of energy: the equivalent of a hundred hydrogen bombs going off all at once. And the only defense is you.
And your big, shiny, bald head.