Asteroid Apophis, a hunk of rock a few hundred meters across, will pass so close to the Earth in 2029 that it will actually be below many of our satellites.
Got your attention?
OK, so maybe you've heard of Apophis. There's the usual doomcries about it, of course. It won't hit us on 2029, but depending on exactly how close it gets (these things are hard to tell with enough precision so far in advance) it may hit us on its next pass, in 2036. The odds are really low, like 1 in 45,000 as it stands now (better observations may move that up or down).
Should you be scared?
I'm not. 1 in 45,000 are long odds. It's roughly the same odds as flipping a coin 15 times and having it come up heads every time. Ever had that happen to you? No? There you go.
The odds of dying in a car accident are 1 in 6000, a bit higher than the odds of Apophis ruining our day. That's high enough, with a severe enough outcome, that it's wise to take precautions when you're in a car. Look around before making a turn. Wear your seat belt. Turn the damn cell phone off while driving (you've very likely to die in this manner, as someone might shoot you for being such an idiot). It just makes sense to make at least a minimal amount of preparation, given that you spend a lot of time on the road, and the odds are not that small. We all know someone who was hurt in an accident.
So it makes sense to prepare for an asteroid impact. The Earth spends all its time on the road, and while asteroids may not make cell phone calls, they'll definitely call on us someday. So it just makes sense to take some precautions.
The comic strip User Friendly has been on this as well: