The door to the airlock closes behind you before you can stop it. You turn slowly to face the outer doors, and with growing dread you realize you are face to face with the worst fear of every astronaut since the dawn of the space age: when the outer doors open, you'll experience explosive decompression. You're about to be introduced to the hard vacuum of space.
What would that be like? If you watch movies, you might get a somewhat confused view of this. Your head will explode like a balloon full of pizza ("Outland"), your eyes and tongue will bug out as you choke to death ("Total Recall"), you'll freeze instantly ("Mission to Mars").
The problem is that none of these things is right.
Artist Nathan Hoste got as tired as I was of Hollywood's depiction of getting tossed out the airlock, so he decided to draw a series of comic book-like panels showing the fact and fiction of breathing vacuum. He's calling the series Bodies in Space, and the drawings are really cool.
This one is called "Radiation". I love the retro feel to it, and his caption is great: "Another thing that happens in space, away from an atmosphere or space ship, is being bombarded by cosmic rays. Many many years after he dies of oxygen deprivation, he will die of cancer." Ha!
The other drawings are equally excellent (though some are arguably NSFW). His science is good, and he plans on doing several more in the near future. I can't wait! I love stuff like this, and it's great that he's using this medium of comic art to show real science... which in this case is both scarier and more interesting than fiction.
If you want to know more, I've written on this topic several times, including my reviews of Mission to Mars and Star Trek (the reboot), and twice on my old website: in a short article as well as answering a reader's question.
I also talked about this in an episode of Q&BA:
So there you go. The bottom line: stay out in the vacuum of space and you'll die, in a horribly unpleasant way. Just not in the horribly unpleasant way shown in movies!
Tip o' the space suit visor to the good folks at io9. Art by Nathan Hoste, used by permission.