If you've got to die, you might as well see something spectacular on the way out, right? So what would it be like to stand on the surface of one planet while another came crashing down? A noted astronomer explains what REALLY happens when worlds collide.
Imagine: the twin suns, so close they appear to almost touch, set toward your western horizon. As dark rises to the East, so does the rim of a vast disk. After an hour, it clears the horizon: a disk of light in the heavens so bright you have to squint, and so big it spans half the sky. It's a rogue planet, and only a year before it was barely more than a brilliant point of light in the sky. Now it looms so large you feel you could fall into it.
A strong earthquake shakes the ground as they have for the past few days; the result of the titanic tidal stress induced on your planet from the others' gravity. On the other planet, with your naked eye, you can see networks of hundreds of massive cracks lit dull red from magma, the tides from your home world stressing and tearing apart the interloper. The disk grows as you watch, blotting out the majority of the sky by the time it sets a few hours later.
The suns rise, and happily you're on the side of the planet facing away from the location where the two worlds will touch. You're spared the actual sight of the catastrophe.
Not that it matters, really.
Head on over to Discover magazine to check out the whole thing and find out the rest of the story!