You mean the movies got it wrong?

I've just given myself nightmares...possibly for weeks. I stayed up late last night watching a show on the History Channel called "Last Days on Earth" -- wherein extremely smart scientists ponder the top threats to the planet and how the earth might end (and, of course, what happens to us when this occurs). Gamma radiation bursts, supervolcanos, asteroids, black holes -- all discussed by the likes of Stephen Hawkings, astrophysicist Neil De Grasse Tyson, and experts in vulcanology, geology, etc.

Sure, there have been disaster movies on SciFi for years about the giant asteroid heading towards earth, or a volcano erupting in Los Angeles or something. At the last moment, while the desperate people on earth watch in awe, the asteroid is destroyed, or the lava is rerouted, or most people excape the giant tsunami. It's a popular genre.

But the reality -- as this History Channel special explains with computer simulations and detailed scientific explanations of the predicted results -- is never so pretty. A massive eruption of the enormous caldera that sits under Yellowstone Park could drop ten feet of ash and sulfuric acid over the entire US and within weeks over most of the globe. The oceans would have the pH of battery acid and the darkness would kill off most of the plant life for many years. And we're about 30,000 years overdue for a massive eruption, if history is any predictor.

A black hole swinging close to our solar system (not as far fetched as it sounds) would give us decades of warning that the earth was going to be destroyed. And not a damn thing we could do about it.

Asteroids are a common movie villain, but the rosy outlook promised by the movie Armageddon isn't quite reality, according to the experts. An asteroid the size of Connecticut is currently plotted to come close enough to the earth in 2029 that it will actually pass beneath the orbit of some of our communication satellites -- and when it returns seven years later, no one knows whether it will hit us or not. If it does -- well, we know how the dinosaurs died off, and if anyone actually survived the firestorm in the atmosphere that would follow such an impact, it would be a short and painful existence. One of the interesting discussions in the show was of the movie-version of an asteroid hitting the earth: everyone standing outside, lookup up as the glowing rock leaves a shooting-star trail across the sky. Nope, according to science. THese things move at hundreds of miles per second, supersonic. We'd never hear it, and if we were anywhere within a thousand mile radius, the heat of the asteroid coming through the atmosphere would fry people instantly. No pretty glowing trails in the sky, just boom!

We can't actually waste much time worrying about this sort of thing, of course. These events are of such scope and impact that there isn't anything we can do to stop them -- and if they occur, there isn't any way for anyone to "fix" things. We can plan and we can have warning systems in place, but these would be world-ending events. Or at least, species-ending events for anything that needed to breathe and eat and drink. Nothing we do will avoid mile-high tides caused by a black hole, or the blasts of gamma radiation that quite literally shuts down our cells. We can't respond to this sort of thing, and the reality is that we shouldn't spend a whole lot of time trying to do it.

Not quite the nice end to the weekend that I envisioned!

Keep an eye out for the show on the History Channel -- or pick up the DVD here. It's interesting, even if it is enough to keep you up at night staring and the ceiling and wondering.