Comment Re:Stars collision rarity (Score 4, Informative) 236
What I find more interesting is why stars rarely collide?
Too much empty space.
This.
Consider that for two stars to hit each other, they essentially have to pass within one stellar diameter of each other (absent gravity, but they're moving at over escape speed relative to each other, so gravity won't enlarge that distance a whole hell of a lot).
So, one stellar diameter is ~1.4 Gm for Sol. Nearest star is 40,000,000 Gm away. If that nearest star were headed toward us (it's not), it's course would have to be within 0.01 seconds of arc of our Sun in order to actually hit it.
And stars farther away have an even smaller course window to be in to smack us....