Armaggedon, Deep Impact, and a host of other space-rock-hurtling-toward-earth blockbusters all follow the same unrealistic formula, writes Discovery Channel's Phil Plait at Blastr. These movies invariably begin when "an amateur astronomer spots something in the sky that shouldn't be there." What follows is typically "a hurried email, a chat over the 'net, and then confirmation from professional observatories — but a discovery kept secret from the public." Then, NASA quickly trains and dispatches a crack team (led by an action star like Bruce Willis) to fly into outer space and blow up the asteroid just before it wipes out civilization. In real life, though, robotic networks would be the likely candidates to spot a dangerous asteroid. And astronomers would be terrible at keeping a secret. Oh, and NASA, a famously slow-moving outfit, would need years to mount such a dangerous and complex operation. Even then, detonating a nuclear bomb on top of an asteroid isn't quite the solution that Hollywood claims. Here, an excerpt:

This is where the movies really part from reality. First of all, anything hundreds of miles across — or even just a few — won't get shattered to smithereens by a nuke. You might carve a chunk out of it, but it would be like tossing a firecracker at a boulder. In Armageddon, given the size of the asteroid involved, they'd need a nuke that could detonate with the same energy output as the sun.

I'm rather glad we don't have a weapon like that.

Read the entire piece at Blastr.