h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Hi Frogbit!

Excellent and informative article - congrats!

A quick question for you (and indeed everyone).

How worried should we be about being struck by a large meteorite again?


Best wishes

Otto

Thanks for your kind comments.

Judging by the geological record, an impact is inevitable. Whetehr it will occur while we are still extrant as a species is another matter.
A big asteroid came close recently, there's a pamapas plain in Argentina which has a series of deep gouge marks, indicating where a large meteor skipped across the Earth. There's evidence to suggest that ten or more planetesimals (the difference between a meteor and a planet) have hit us, and there is plenty of evidence for smaller ones, which have only wiped out 40/50% of all species living at that time. In Africa (will dig out exact location) there's a lump of iron 60 tonnes in weight - all that remains of a much larger meteorite that hit about 100 thousand years ago (interestingly enough, that was the rough date for H.erectus leaving the area). And let's not forget Tunguska - a large area of Russian forest was flattened when a meteor exploded above ground. Had that been in any major city, an awful lot of asteroid spotting funds would have been freed up.
Can we do anything about it? Not much - at least not when the spotting budget is next to nothing. Even if they're spotted there probably isn't a great deal you could do.
Popular films such as 'Armaggedon' used one of the most touted methods, but blowing asteroids up with nukes isn't such a smart idea. Unless it splits precisely how you want it to, you'll end up scattring many, many smaller meteors across the surface of the planet, potentially causing greater damage.

So yes and no - we could do more, but I wouldn't worry about it - if a big enough one comes you won't be able to do anything.
And anyway - see it as pruning. After mass extinction, evolution blooms again to fill all the empty niches.
Frogbit.

The USA should probably worry more about the Caldera volcano currently building up under Yellowstone park. It explodes once, roughly every 600,000 years and guess what? The last eruption was around 600,000 years ago, scientists can measure the rock rising over a wider area and the explosion would make Vesuvius or Krakatoa look lie a pop gun. Caldera's are also called supervolcanos and are supposedly responsible for mass extinction events also...

Oh. A very article by the way - just up my alley but I think you know that already Frogbit