I’m currently writting a book (isn’t everyone?) and i need some info to make it believable. first, the premise:
ok, imagine the movie armagedon (i’m simplifing a lot here) if the astonauts had failed. most of life on earth has been wiped out, but not all. people saw it coming and prepared, built shelters and whatnot, so some of humanity survived. (gathering energy from geo-thermal vents maybe?)
so what i need to know, is how big would the rock have to be in order for everyone to think it would kill everything, but have it still not do so?
and, if a rock this size did hit, how long would the nuclear winter be? (the story takes place durring the ash-blotting-out-the-sun period)
Too many unknowns (thank goodness) re what really happens at impact and afterward in the real world for you to get a concrete answer. If you’re lookingfor a SWAG double the estimated size of the Chexilub meteorite and you should get a “kill almost everything except for” rock.
Nuclear winter time? Who knows… this is even more problematic to determine than the size of the rock. Double the estimated coverage time for the aforesaid Chixilub metorite of 65 million years ago.
I betcha there are books on this if you look. I should also warn you this story was done in a book before…“Lucifer’s Hammer” but its not like plots don’t get recycled often enough (ick, I don’t know how to put that last sentence better).
Anyway, I am not sure but willing to guess. I think I have heard that one a couple of miles in diameter ought to be pretty good for it. But I recommend checking out a book, or even a website for more accurate info…try http://www.nasa.gov.
Not very big, actually. I read somewhere (Discover or Popular Science magazine, IIRC) that a rock 100 yards wide would vaporize a big city (New York-ish); several hundred yards, would wipe out an area the size of Texas; a mile or three, North America; 20 miles, a hemisphere; 50 miles, worldwide nuclear winter. It’d last at least a few years.
I read a few reviews for that book, and (luckily) it is nothing like mine. mine is more of a “how would people survive” type book, with an evil organization thrown in for conflict. thanks for the heads up on that though.
Actually, there’s so much leeway that you could probably use any figures you want for the size of the meteorite and the length of the nuclear winter. As a matter of fact, that sort of detail probably isn’t essential for the type of story you want to tell.
I agree, you could pick about any size you want and justify it. It’s effect would vary widely depending on where it hit, what sort of angle it hit at, and what it was made of.
Be sure not to go too large, though. An iron meteoroid the size of Texas, like they used in Armageddon, would have actually gone straight through much of the planet. It would have not just killed a lot of stuff, it would have made most or all life impossible for a long time. And you couldn’t have damaged or redirected it with all the bombs on Earth.
In Lucifer’s Hammer, most of the story does take place in the “survival” phase after the impact. But the impact was from a comet, and it hit ocean. So there was a very, very long thunderstorm over a hemisphere, but not a widespread extinction of humanity. So your story isn’t very similar, as you said.