A while back I was having one of those discussions about what we should do about global warming. One of those conversations where I half-remember various sources I've read and sputter on in an unconvincing manner and manage to offend whoever I'm talking to without enlightening anyone.
I do that a lot.
Anyway, in this particular conversation, I said I wasn't very worried about global warming. Whatever comes up there, we'll deal with, and over time we'll have better ways to deal with it.
What I'm worried about, I said, is a comet or meteor or something smacking into the world and wiping us all out. That's a tough one to deal with.
The person I was talking to, like any reasonable person would I suppose, turned to me and said derisively, "That's science fiction!"
Okay, I can empathize with the reaction. Here we are talking about global warming, a phenomenon that is clearly going to wreak havoc on all of us in just a few years if we don't do something damnit, and suddenly I'm going on about stuff you might see in Star Trek. I might as well be coming from another planet, so to speak.
Well, actually... Unlike the vagaries of where exactly the weather will go in the future, we know comet and asteroid impacts can happen and have happened, and have in fact wiped things out on the planet one or more times. But I think what surprised me most about that reaction, on reflection, and what I didn't think to bring up at the time, is that not only is this not science fiction, we just saw it happen, in 1994, to Jupiter...
This left some Earth-sized spots clearly visible on the planet for a while, and would have been quite devastating if it had happened to us (again). There's more about this collision, of course, on Wikipedia. And if you want to scare yourself once in a while, see what's up at NASA's Near Earth Object Program, or read up on the Tunguska event and the history of impact events.
So, yeah, I know it's science fiction, but when it comes to the end of the world as we know it, my bet is on these invaders from outer space...