That will be a bit of a bother, wouldn't it? My insurance doesn't cover galactic impact!
I thought a collision between galaxies was more of a merger than anything else, with the exception of large galaxies that devour the smaller ones.
And to return to the original thread, I remember reading a little blurb about Gliese 710 a few years ago in Astronomy magazine. It's predicted to shine at magnitude 0.6, brighter than quite a few stars. Should be pretty.
Even though it would be passing at quite a distance, it reminded me of the scenario in the book What If the Moon Didn't Exist? The scenario was a star of half the sun's mass passing through the solar system. What happened in this fictitious system was:
Earth's orbit was made more eccentric
Jupiter was destroyed (it collided with a gas giant orbiting the other star)
Uranus was ejected from the solar system
Neptune was captured by the other star, and was somewhere in the star's CHZ. It began to melt and become more amenable to life (or was on it's way to becoming such.)
I can't remember if the other planets were affected or not. I would think the above would be enough.
-M-
