Because Bill Nye explains the world better than even experiencing it yourself, here's our childhood maestro of science explaining how we could possibly stop an asteroid from destroying Earth. Giant bombs, huge rockets and even freaking lasers probably can't stop it. And even if they could stop it, we might not be able to build them. So, uh, yeah.
In all seriousness, Bill Nye says we only have to slow down the speed of a giant planet destroying asteroid by 1/1,000,000th of a metre. That sounds way easier than it actually is but I like our chances with Bill Nye on our side. [AsapSCIENCE]