Death by meteorite

By Phil Plait | October 13, 2008 9:00 pm

I recently wrote about the odds of getting hit by a meteorite. But what are the odds of getting killed by one?

Turns out, they’re a lot higher! Why?

Meteor impact from a commercial
Dude. Run. (Click for source.)

Because you are small and the Earth is big, getting knocked on the noggin by a meteorite is a low odds event. But a big meteorite, say one 100 yards across, doesn’t have to directly fall on top of you to shuffle you off this mortal coil. It could land kilometers away and the blast wave (or the heat) could do you in. And a bigger one can land hundreds of kilometers away and still snuff you out, especially if it hits in the ocean and causes a big tsunami to march over the beaches and coastlines.

However, big asteroids coming in and whacking us are much rarer than small ones; if you go out on a clear night you might see a dozen meteors caused by rocks smaller than a grain of sand, but you could wait 100 million years for a dinosaur-buster. You have to account for that as well. This is a calculation worth doing, because a) a lot of people fret about it, and b) it could in fact mean the end of all life on Earth. That might be worth knowing.

Me in front of Meteor Crater in Arizona
Me, in front of Meteor Crater in Arizona. The far rim is almost a mile away.
Click for more impact.

Astronomer Alan Harris has made that calculation. Allowing for the number of Earth-crossing asteroids — the kind that can hit us because their orbits around the Sun intersect ours — as well as how much damage they can do (which depends on their size), he calculated that any person’s lifetime odds of being killed by an asteroid impact are about 1 in 700,000.

One out of seven hundred thousand! That’s still pretty low… and certainly not enough to lie awake at night worrying about it.

But there are a few important things to consider.

1) A big asteroid is rare, but one bigger than about 10 km across would kill everyone, all 6 billion of us. That skews the odds. If one of those hit every 100 million years, then your lifetime odds of dying in an impact is 100 million years divided by 70 years = 1 in 1.5 million.

A small impact might happen 1000x more often (every 100,000 years), but might only kill 1/1000th as many people, so the odds are roughly the same. Weird.

2) We are lousy at understanding low probability events. I know that 1 in 700,000 is a ridiculously low probability, but it’s hard to grasp. As a comparison, you’re more likely to die in a fireworks accident. But what’s funny is, this is a slightly higher chance than being killed by a terrorist! Despite propaganda to the contrary, the odds of any given person being killed by a terrorist attack are incredibly low. While terrorist attacks in the long run are a near certainty, the odds of you getting killed are very low.

It’s like the lottery: someone wins every time (eventually), but chances are it won’t be you.

Worrying about preventing a terrorist attack is a good idea, but (unless you work in a high-risk job) worrying specifically about dying in one is not*.

Incidentally, you have about the same odds as being killed on an amusement park ride. Wheee!

And that brings us to one more thing to consider:

3) We need only spend a relatively small amount of money to drop those odds a lot more.

We spend billions on terrorist attacks, but hardly anything on preventing asteroid impacts. Yet, of all the ways we can die from astronomical events, asteroid impacts are both the highest probability event and the only ones we can prevent. We can’t stop the Sun from blasting out flares which take down our power grids, or a nearby star from exploding. But we do in fact have the technology (or will in literally ten years) to detect incoming asteroids and then move them out of the way.

I won’t go into details here — go read the B612 Foundation’s site for info — but this tech will exist as soon as we have the Ares rockets ready to launch in 2015 or so (and I suspect the heavy-lift rockets already in use by other countries might do as well). The investment will be a few billion dollars, but the outcome is preventing the wiping out of the human race.

Per capita, I think that’s worth a few bucks.

Note: If you’re curious for more, I have a lot more detail about asteroid and comet impacts in my book. A lot more.


*That is, if an attack is on the same scale as previous ones. A really big event — the use of a dirty bomb, poisoning of a water system, or some other cheery thing like that — will up the odds quite a bit.

Comments (113)

Links to this Post

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  1. Wayne

    Good points. I gave a similar argument to my astronomy class the other day. Of all the things the government spends money on, the space program is potentially the most important from a saving-humanity standpoint. Who was it that said, “The dinosaurs are extinct because they didn’t have a space program”?

  2. IVAN3MAN

    Dr. Phil Plait: “We spend billions on terrorist attacks, but hardly anything on preventing asteroid impacts.”

    That’s because politicians need a bogeyman, such as Al-Qaeda, to justify their extravagant military spending. It’s more fun for Evangelical politicians to “kick some A-rab ass” than to take precautions against asteroid impacts, which might not happen.

  3. quasidog

    If we as a species can’t work out how to stop millions from starvation, when the planet has an abundance of food for all, I don’t really care about trying to stop a meteor that may or may not hit us anyway, let alone worrying about a terrorist attack. I read an interesting fact recently that suggested that 5 days of spending on the current war effort for the USA, could set up a small 3rd world country for many years to come. … digressing a bit but my point is …. who cares about what may happen, when we have it in our power to fix bad things that are now currently happening. The funny thing is, we will, as a race, probably end up fixing the threat of asteroid impact far before we fix world wide starvation and disease and other current human problems. It is so lame.

  4. Trocisp

    ALL life on Earth?

    Aren’t you being a bit melodramatic there, man?

    All HUMAN life on Earth, sure… but there are microbes that live hundreds of meters underground that would likely survive, and perhaps their descendants would pick up our (by that time, obviously failed) attempt that galactic domination.

  5. MDF

    Nice shot of you in my home state, BA.

    Arizona ROCKS! (Pun intended)

  6. Bigfoot

    This is why us Sasquatch have built large undetectable underground lairs — we are prepared for distant large meteorite events.

    We only surface when we need to harass isolated individuals with wild imaginations and no evidence gathering abilities whatsoever, and of course to read the BA blog.

  7. Chip

    My office is on the second floor of a two story building. Maybe I should move to the basement.

    No. I like the view. I’ll risk it. ;)

  8. Dr. Phil Plait, do you remember that Down 2 Earth: Impact Calculator program you mentioned in your previous post, “Wipe England Wales off the map”, back in 13-June-2008? Well it’s been improved since then; previously, one was only able to select Wales as the “target”, but now you can select: Cardiff; London; Paris; New York; Barringer Meteor Crater, Arizona; Wolf Creek, Australia; Mistastin Lake, Canada; Aorounga, Africa; Roter Kamm, Namibia; Bosumtwi, Ghana, and finally, Kara-Kul, Tajikistan.

    Anybody who’s interested, click on my name for the link.

  9. Those odds go down a lot if you accept Professor Keller’s argument that the dinosaurs were still happily walking around 150,000 years after Chuxulub, and that they were actually done in by volcanoes, climate change, and other unknown, but much larger impacts.

    “No significant species extinctions are associated with the Chicxulub impact, which can be partly explained by the relatively small size (~120 km in diameter) of the impact crater. Craters of about 100 km, such as Popigai, did not cause significant species extinctions. ”

    From: http://geoweb.princeton.edu/people/keller/chicxulub.html

    Assuming a 12:1 crater/impactor ratio, a 10 km bolide will produce strictly local effects.

  10. Craig

    @quasidog — amen to that!

  11. TSFrost

    So 6 billion people each have a 1 in 700,000 chance of being killed by an asteroid? That would mean in my life time, over 8500 people will die by space detritus.

    That doesn’t sound like a “ridiculously low probability” to me. ;)

  12. Mark

    @Trocisp:
    If it’s large enough, you’d be surprised what an asteroid can do…

  13. Just a question about the impact crater in Arizona: How much destruction would that have caused as far as a blast wave?

  14. Oh, and obviously the whole thing about the dino’s being wiped out 65 million years ago is a bunch of horse hooey. Sarah Palin says she’s seen pictures of human footprints and dino prints together… so there! But what do I know, I’m just an average “Joe Six-Pack” ;)

  15. slw

    Those odds seem way too high, is there a recorded death to a meteorite impact in all of human history? According to those odds, it would happen on average once every 3 days.

  16. First, I gather it’s now closer to 7 billion people than 6. Catch up!

    Second, given the technology to divert an asteroid, the likelihood of it being used to divert objects to strike targets on earth is overwhelmingly greater, in any given year, than of it being used to divert them to miss. That’s history for you.

    If members of some Maastrichtian dinosaur species or other achieved spaceflight, then the asteroid that scattered iridium all over the planet shortly thereafter might not have fallen on its own; more likely it was pushed. Big “if”, though.

  17. quasidog

    Sorry .. ignorant Australian question …

    When she says “Joe six pack” … is she insulting people that don’t have 6 pack abs ? .. or is she insulting people that are average but don’t drink beer ?

    I know she is insulting someone here .. (tongue in cheek) It is an amazing expression, in the sense of how stupid it is.

    I don’t know (or care ) too much about USA politics, but from what I have read regarding her quotes, and beliefs, if her party gets voted in, well … you know its all over for your country right ? I mean .. voting that last idiot in was one thing, voting in someone else that is out of touch with reality .. again !!! …. omg … it will be all over. Vote for someone smart for a change … please. (I like USA …but its the fools in charge at the moment that are killing it but) I guess I would vote for Obama. (if I was a citizen) He seems decent, seems to have his morals in the right place, and clearly smarter than anyone else I have seen on the news.

  18. Jose

    What are the odds the earth will pass through the tail of a comet causing most people to turn into red dust?

  19. quasidog

    … never tell me the odds! (quote from some movie with robots in it ) :)

  20. @quasidog:
    Joe Six Pack is a reference to an average guy. But yeah, most guys are insulted by it… BUT, she is hot, in a quirky, odd sort of way.

    Ummm, actually, if she gets voted in, and McCain goes to that Hanoi Hilton in the Sky… she becomes President. Now, you’re in Australia, so depending upon the atmospheric wind currents, you might be okay down there. I’m not sure if radioactive fall-out will quite make it that far down when she tries to get Jesus to come back by pressing the Big Red Button, and launching the Apocalypse.

  21. Clive

    Dr Plait I do not understand this statement of yours: “Worrying about preventing a terrorist attack is a good idea, but (unless you work in a high-risk job) worrying specifically about dying in one is not.”

    Can somebody assist?

  22. Jose

    … never tell me the odds! (quote from some movie with robots in it )

    How many times do you have to survive fifty gazillion to one odds before you stop and think, “Boy, my robots really crappy at calculating odds.”

  23. Jose

    @Clive
    I’ll try and re-write it with a little folksy charm thrown in at the end.

    Taking steps to prevent a terrorist attack is good idea, but unless you work for something like a bomb disposal unit, any worry about actually being killed by an act of terror is misplaced because there are so many other things that pose a far greater risk to the average Joe Six Pack or Mary Cow Milker.

  24. Great points Phil. People need to understand that a space program is much more than sending astronauts to the moon.

    I’m scared by the prospects of another Republican president over in the US, especially the one who’s running right now. As much as I wanted not to care about the politics in a country I don’t live in, whoever is in Office does impacts in things around the world.

  25. Kullat Nunu

    Um, dirty bomb is a terribly ineffective way to kill people. It can be lethal if people are exposured to the radiation for a long time, but since moving people out from the fallout area is easy that is preventable. Even cleaning up the contaminated area isn’t impossible.

  26. “this tech will exist as soon as we have the Ares rockets ready to launch in 2015 or so”

    I thought that the first Ares rocket only barely qualified as a heavy launcher, and was getting less and less capable as development continued.

    If we wanted a working heavy launch vehicle sooner rather than later, wouldn’t we be better off with the DIRECT system?
    http://www.directlauncher.com/

  27. Cheyenne

    BA- We actually do have the means today to stop both asteroid impacts and terrorist attacks.

    His name is Bruce Willis.

    He could stop an incoming asteroid with terrorists riding on it with only an Aerosmith soundtrack and a dry sense of humor.

  28. The dinosaurs that pushed the KT event rock into the planet will be back… one day…

  29. mk

    Hey… that was a tease. I click on pic to see an “embiggened” version, you know, more “impact!” And what? Same size, only on flikr. That’s just mean. ;^}

  30. JohnW

    any person’s lifetime odds of being killed by an asteroid impact are about 1 in 700,000.

    Lloyd Christmas: What are the chances of a guy like you and a girl like me… ending up together?
    Mary Swanson: Not good.
    Lloyd Christmas: Not good like one in a hundred?
    Mary Swanson: I’d say more like one in a million.
    Lloyd Christmas: So you’re telling me there’s a chance?

  31. Dave

    Thought you might like to know: I just got an e-mail from Amazon saying that my advanced order copy of “Death from the Skies” has shipped. Wooohoooo!!!!!!

    Can’t wait!

  32. TSFrost, statistics don’t actually work like that. Heck, I’m not really sure they work at all. ;) There are lies, damn lies, and statistics.

    “Click for more impact”… *groan*

  33. Are there any thoughts on how this probability will change as commercial space flight becomes more viable and more and more people spend time without the protection of our atmosphere to burn up incoming particles?

  34. !AstralProjectile

    Kullat Nunu beat me to it, although it could cause immense economic devastation, diverting resources from those who need it most.

  35. KC

    It occurs to me that while asteroids and comets can cause greater devastation than terrorists, asteroids and comets aren’t actively seeking to do us harm. Perhaps a better case can be made by comparing the amount of money spent on minimizing harm in other natural disasters verses looking for death from the skys. Seriously. How much is spent, say, on a tsunami warning system verses the search for NEOs?

  36. @KC : “It occurs to me that while asteroids and comets can cause greater devastation than terrorists, asteroids and comets aren’t actively seeking to do us harm”

    KC, I don’t think it works that way. Statistically speaking it doesn’t matter. Probability doesn’t care whether the risk factor is deliberate or not.

    The Indians have suggested a tsunami warning system for the Indian Ocean may cost the 36 countries on that ocean around $200 million. Dunno what the system in the Pacific cost. I’m guessing the NEO warning system is a bloke in a backyard with a telescope.

  37. TheManVersion

    Is Meteor Crater, AZ, one of the neatest places on Earth or what? Last time I was there, I got to watch a thunderstorm roll in across the plains. Gorgeous.

  38. Off topic I’m afraid (unless some of the deadly meteorites are being erupted into space at us from a Mercurian volcano) but I’m keen to find out :

    1) Is there any more info /images /news dtaa /whatever to come from that second MESSENGER’s Mercury fly-by still?

    2) Did they ever find that Mercurian shield volcano suggested by Arecibo radio mapping data?

    3) Or any other volcanoes on Mercury or suggestions thereof?

    Anyone know & care to enlighten me? Please?

    NB. Click on my name for a link to the Marchaut by messenger thread here asking this question also.

  39. Jared Lessl

    The nice thing is that if we ever get our act together and expand out into space in a major way, defense against meteors will be a cheap and easy thing to do. In fact it’s pretty much a freebie that comes along with space colonization. We have a hard time spotting incoming objects now because all we have is this one vantage point. Can’t tell how many times I’ve read about some comet that came worryingly close but we never saw it because it came at us from the sun. But stick people out on Luna, in solar orbit, amongst the asteroids, Lagrange points galore, it becomes much easier to deal with.

    Heck, a potential earth-smasher becomes a good thing. Nudge it enough to capture it in a nice wide orbit and start breaking it up for materials.

  40. Bein'Silly

    TheManVersion Says:
    October 14th, 2008 at 7:33 am

    “Is Meteor Crater, AZ, one of the neatest places on Earth or what?”

    No. Its not neat at all – its very messy! ;-)

    What with all those rocks strewn about and dust and bird droppings and a little bit of litter here and there and so on ..

    Gorgeous tho’? Yeah it is that. :-) Stunning, bretah-taking & awesome too. :-)
    Last time I was there, I got to watch a thunderstorm roll in across the plains. Gorgeous.

  41. StevoR

    Jared Lessl Said on Oct. 14th, 2008 at 7:47 am :

    “The nice thing is that if we ever get our act together and expand out into space in a major way, defense against meteors will be a cheap and easy thing to do. In fact it’s pretty much a freebie that comes along with space colonization. We have a hard time spotting incoming objects now because all we have is this one vantage point. Can’t tell how many times I’ve read about some comet that came worryingly close but we never saw it because it came at us from the sun. But stick people out on Luna, in solar orbit, amongst the asteroids, Lagrange points galore, it becomes much easier to deal with.

    Heck, a potential earth-smasher becomes a good thing. Nudge it enough to capture it in a nice wide orbit and start breaking it up for materials.”

    Or another idea (maybe crazy but what the heck ..) why not redirect a few Earth crossing asteroids to slam into Venus instead? If they hit it hard enough might they be able to blast some of Venus’es too-dense suffocating and toxic atmosphere away and help “terraform” that planet? Maybe?

    What do folks think?

  42. Clive

    Jose Says:<<>>

    It still makes no sense. If we need not worry about terror attack because the chances are minuscule, then how come is it a good idea to take steps to prevent it?? Why spend trillions on HUGELY unlikely threats?

  43. Bein'Silly

    D’oh! Lat line inmy post there wasn’t mreant to be there & isn’t mine.

    It was cut& pasted – by mistake – from ‘TheManVersion”s original post. Sorry. :-(

  44. Nigel Depledge

    mk said:

    Hey… that was a tease. I click on pic to see an “embiggened” version, you know, more “impact!” And what? Same size, only on flikr. That’s just mean. ;^}

    Notice, though, that the version on flickr has a little linky just above the picture (kinda sitting on its top edge) that says “All sizes”. Click this and it will go to the large size (in this case, 1000 x 576 pixels).

  45. Bein'Silly

    Arrgh! Typos.

    Make that : “the last line in my post wasn’t meant to be there.”

    No, not *that* last line, the other one ..!
    No, not that post the other one ..

    Oh stuff it. Pity we can’t edit here BA!

  46. slw: The statistics don’t work that way. You can’t average over time in that manner, because the event itself is rare. But the odds get funky because in a big impact, everyone is killed. Remember too, that we don’t know of any impactors big enough to wipe out all life that can hit in the next 70 years. So in reality, your odds of being killed by a 10km asteroid are 0. :-)

  47. StevoR

    Incidentally at a guess (not having clicked the source) that first picture there :

    Filming ‘Independence Day’ movie the bit where the saucer crashes with Wil Smith either flying it or forcing the alien to crash! “I could’da been at a barbecque!”

    Am I right? ;-)

  48. You guys think Barringer Crater is big, look at this one!!!

    http://www.flickr.com/photos/chuckexpeditions/2940971491/in/set-72157602565097458/

    Hey Phil, this is the book you signed for me at the RASC GA in Toronto.

    Chuck

  49. StevoR

    What about a 10km comet though Phil? Or is that in the book?;-)

  50. StevoR

    Meant to emphasis the word ‘Comet’ as in :

    “What about a 10km * COMET * though Phil? Or is that in the book? ;-)

    Because aren’t they a little less predictable and don’t they appear from nowhere (well okay the Kuiper Belt /Oort cloud) a lot more abruptly?

  51. Nigel Depledge

    KC said:

    It occurs to me that while asteroids and comets can cause greater devastation than terrorists, asteroids and comets aren’t actively seeking to do us harm. Perhaps a better case can be made by comparing the amount of money spent on minimizing harm in other natural disasters verses looking for death from the skys. Seriously. How much is spent, say, on a tsunami warning system verses the search for NEOs?

    In Japan, there is a huge investment in tsunami warning systems. In the last couple of years, a system has also been installed in the eastern Indian Ocean to alert people to impending tsunamis, after that one that struck just after Christmas about 3 years ago.

    Large amounts of money are spent on trying to predict earthquakes and volcanic eruptions, too.

    It all comes down to a question of risk versus benefit. We know that cities in earthquake zones will get hit sooner or later, and the tricky part is predu=icting when a quake will strike and how hard. Similarly, we can be fairly confident that the Earth will, sooner or later, be struck once again by a fairly hefty chunk of asteroid. The timescale is larger, but then so is the consequence if the impactor is very large. An earthquake could destroy a city and kill thousands – a large impactor could destroy all the buildings on a continent and kill millions (and a really huge one could wipe out all humans).

    With earthquakes, having a few days’ notice is sufficient to save many lives. However, with asteroids, the more notice we get, the more chance we have of being able to do something about it. IIUC, we would need more than a year’s notice to have a serious chance of deflecting an asteroid that is on course to strike the Earth. Now, for a small impactor, you can predict where it will strike and evacuate the area (and all nearby coasts if it strikes the ocean). For a large impactor, it is far better to deflect it than to evacuate half the globe. For a really huge one, evacuation is not an option – deflection is your only chance to survive.

    So, we should worry at least as much about asteroid impacts as about other natural disasters, especially as we get to grips with predicting and protecting people from such things as tsunamis, earthquakes, volcanic eruptions and hurricanes.

  52. The place in the States with the most awesome view of destruction is Mt. St. Helens. Not a huge disaster in terms of death, but there’s no place like it for shear destruction. I had the famous series of photos of the volcano blowing up on my wall for years.

    And – completely terrestrial.

  53. TheBlackCat

    Clive Says

    It still makes no sense. If we need not worry about terror attack because the chances are minuscule, then how come is it a good idea to take steps to prevent it?? Why spend trillions on HUGELY unlikely threats?

    The odds of a specific person being killed by a terrorist attack are small. The odds of any of the 6-7 billion people on the planet being killed by a terrorist attack, however, are much higher. It is not the government’s responsibility to protect you are me, it is its responsibility to protect everyone in the country. It doesn’t matter who is the one who is killed.

    It is like the lottery. You, or any other specific person, are almost certainly never going to win the lottery. But because there are so many people playing the chance that some player will win in a given week is quite high.

  54. Clive

    TheBlackCat Says:

    <<>>

    OK now I follow that. So how many Americans are killed domestically every year by terrorists? Other than the single event spiking the stats on 9/11 it can not be more than 10 or 20 per year. Which is fewer than the number of children dying in swimming pools no?

    I suspect if you safeguard swimming pools or motor cars just slightly better you get much more value for your money than the entire “war on terror” and without sacrificing your civil liberties. But maybe I am wrong on this – where do I get the stats?

  55. Clive, Americans killed domestically by terrorists every year? 10 or 20 sounds way too high even if you count Right-To-Lifers killing doctors. If, for example, Al Qaeda killed one person in the US in a year (not counting 2001) it would be The End Of The World As We Know It ™.

  56. Clive-

    Google ’causes of death’ (I’m assuming I still can’t post links) and your first result will give you the following for the ways people died. These are from the year 2002, and I don’t think there were any asteroid impacts that year. With a little more searching, you’ll be able to find other years from the CDC. I don’t think the 2001 attacks in the US would have put ‘terrorism’ within this realm of most common ways people died. The list gives the technical name, common name, and percentage (there’s an ‘other’ category at 17.4%):

    (1) Diseases of the heart heart attack (mainly) 28.5%
    (2) Malignant neoplasms cancer 22.8%
    (3) Cerebrovascular disease stroke 6.7%
    (4) Chronic lower respiratory disease emphysema, chronic bronchitis 5.1%
    (5) Unintentional injuries accidents 4.4%
    (6) Diabetes mellitus diabetes 3.0%
    (7) Influenza and pneumonia flu & pneumonia 2.7%
    (8) Alzheimer’s Disease Alzheimer’s senility 2.4%
    (9) Nephritis and Nephrosis kidney disease 1.7%
    (10) Septicemia systemic infection 1.4%
    (11) Intentional self-harm suicide 1.3%
    (12) Chronic Liver/Cirrhosis liver disease 1.1%
    (13) Essential Hypertension high blood pressure 0.8%
    (14) Assault homicide 0.7%

  57. My-Name-is-Kenneth

    Why is it only rednecks get to see things like meteorite impacts, just like with UFOs?

    Maybe I should start watching NASCAR while drinking beer in my pickup truck listening to music with my Confederate flag.

  58. flynjack

    First you have to define terrorist attack. Clearly 911 fits the definition, but what about narco terrorist in south and central america who are using terrorist methods to kill? Revolutionaries using terrorist methodology(beheading, homicide bombing, etc). If one doesnt get hung up on defining terrorism as Al Queda, then the number of deaths world wide go up significantly. One doesnt have to be in the military or law enforcement to be at risk ei. 911, London bombings, Spainish train bombings etc…Clearly the stats will go off the scale if a nuclear bomb is used in a terrorist attack. BA clearly underestimates the annual deaths by terrorism in MHO.

    I do however agree that funding for NEO asteroid identification and mitigation is important.

  59. bjn

    It’s not as simple as a Dinosaur-extinction size impact averaging every 100 million years or so. There seems to be a periodicty to extinction events in the geologic record. These appear to relate to large impact events and I’ve read that these cycles may be related to the solar system’s passing through the galactic plane (or the influence of some unknown perturbing body like “Nemesis”). When an event is more likely to happen at certain intervals, your odds of experiencing the event vary according to when you live in the cycle.

  60. Tom Marking

    “I know that 1 in 700,000 is a ridiculously low probability, but it’s hard to grasp. As a comparison, you’re more likely to die in a fireworks accident. But what’s funny is, this is a slightly higher chance than being killed by a terrorist!”

    You’d have to be a little more specific on what statistics you are claiming before we could evaluate the claim. For example, if you consider lifetime statistics then the September 11th attacks killed about 3,000 Americans out of 300 million: odds are 1 in 100,000 just considering that one attack alone. This is higher than 1 in 700,000.

    That also goes for the statistic on lifetime asteroid mortality. Without more specifics on what assumptions were made it’s very hard to estimate its accuracy.

  61. Jim

    I think your 1 in 700,000 estimate is the annual risk, not the lifetime risk. I think the numbers are closer to 1 in 10,000 for the lifetime risk of being killed by an asteroid impact. Consider that the threshold for global risk are objects around 1 km in diameter and that something around that size is likely to cause the death of about half the humans on the planet. And that a 1km impactor probably hits Earth a few times per million years. I suspect Al Harris’ numbers should generate about 1 in 700,000 years given that impact size hazard alone, so you need to multiply that my the average human lifespan.

    Jim.

  62. Rich

    Tom,

    I’m not even remotely a statistician, so bear with me, but time has something to do with it. For example how many Americans have been killed in terrorists attacks in the last decade? Three thousand, plus a couple hundred more (if we are being morbidly generous). Call it 3,000 anyway just to make my math easier. Wouldn’t that mean that in any 10 year period your chances of dying in a terrorist attack are a little closer to 1 in 1 million. If you reduce the time scale sure that changes things, but if you simple select a different period, say a year in which no one dies in a terrorist attack the numbers say the risk is zero. For example in the U.S. no one died in an attack in 2007. Does that mean the chances of anyone dying in a terrorist attack are zero?

    With asteroid impacts the timelines are huge. A ecosphere killer hits on average every 100 million years (let’s say), but the death rate for higher order plants and animals is 100%. Now that impacts (no pun intended) the math in a major way. First you gotta figure out the chances of the event in your lifetime (how often do they happen, when was the last one, % likelihood of an “early” impact and a bunch of other stuff I am not educated enough to factor in) and the probability of survival 0% to figure the risk. Terrorist attacks may happen more often on a geoligical scale, but their scope is limited until such a time as a change in weapons or tactics affects an increase in the numbers that are killed in any one attack, or the frequency of attacks increases dramatically.

    Basically, a high frequency event that kills few people often is ultimately less dangerous than a low frequency event that only has to happen once to kill everyone. I guess I could have taken a lot less time to type just that one sentence.

  63. Gary Ansorge

    Tom: But consider that was 7 years ago. Now, by factoring in the time it figures out to,,,,1/100,000 per 7 years(assuming we don’t have another this year) which equals ,,,1/700,000. Like HE said,,,

    Quasidog: We do a lot to alleviate starvation world wide, sending billions in aid to third world countries every year. Some of that gets diverted into despot pockets, some is used to provide the indigenous peoples with the means to grow food. Some is actually food for hungry bellies. It’s a truism that the USA throws away enough food every day to feed most of the starving of the world, unfortunately, THAT excess would be spoiled by the time we sent it to them. It’s a question both of economics and locale. We’re here, they’re,,,far away,,,and then of course, when you feed a hungry people they use the energy gain to breed,,,more hungry bellies,,,
    Malthus was right, as far as he went. He didn’t know however, that technology could/would be able to keep us ahead of the overbreed/starvation cycle,,,for a while,,,

    One should note, that in every developed country in which people have the choice to breed (ie, have access to contraceptives and social programs for the aged) they choose to limit their breeding. Japan is on the brink of negative population growth, China has things pretty well under control, Europe is stable and the only reason the US population is expected to continue its population increase is because of immigration and that will likely level off by the time our population hits 350 million.

    It’s energy per capita that allows a populace to experience those choices. The more energy we have available to expend, the more choices we have. That’s just the way it is. So the solution is to bring the whole world into the 21st century. Then starvation will end,,,

    Gary 7

  64. Tom Marking

    WARNING!!! The following post contains numerical equations. You might want to consider RUNNING AWAY!!! at full speed to avoid overtaxing your brain.

    /Scare-the-pants-off-everyone-mode = on

    So we have the following equation:

    dT-Impact = (D / 4) ^ 2.35

    where dT-Impact is the average time between impacts in years,
    D is the impactor diameter in meters
    (See the Rain of Iron thread for details on how this was derived)

    Then:

    P-Year = 1/dT-Impact = (D / 4) ^ -2.35

    where P-Year is the probability of an impact of size D per year

    Then:

    P-Lifetime = L * P-Year = L * (D / 4) ^ -2.35

    where P-Lifetime is the probability of an impact of size D over a human lifetime and L is the average human lifetime (~70 years).

    Now let’s define:

    R-Death = F-Death * D

    where R-Death is the radius of death (all human beings closer than this to the impact point will die, all human beings farther than this from the impact point will live — yes, I know it’s a gross oversimplification but it serves its purpose) and F-Death is a dimensionless factor.

    Then:

    N-Death = pi * rho * R-Death^2 = pi * rho * F-Death^2 * D^2

    where N-Death is the number of humans killed by the impact if it should happen and rho is the population density of Homo sapiens (1.3E-5 humans per square meter).

    Also:

    N-Lifetime = N-Death * P-Lifetime =
    81.66 * rho * L * F-Death^2 * D^(-0.35)

    where N-Lifetime is the number of humans killed by an asteroid of size D over one human lifetime

    Then:

    P-Personal-D = N-Lifetime / N-Humans =
    81.66 * rho * L * F-Death^2 * D^(-0.35) / N-Humans

    where P-Personal-D is the personal probability of death over your lifetime from an asteroid of size D and N-Humans is the total number of humans on the planet (6.6 billion)

    But:

    rho = N-Humans / (4*pi * R-Earth^2)

    So:

    P-Personal-D = 81.66 * L * F-Death^2 * D^(-0.35) / (4*pi * R-Earth^2)
    = 6.50 * L * F-Death^2 * D^(-0.35) / R-Earth^2
    = 1.60E-13 * L * F-Death^2 * D^(-0.35)

    Now integrate over D from zero to some maximum value D-Max:

    P-Personal = Integral from D = 0 to D = D-Max of P-Personal-D
    = 2.46E-13 * L * F-Death^2 * D-Max^0.65

    Thus, we see how this probability depends critically on the maximum size of an impactor that we can expect, D-Max. If we let L = 70 years, F-Death = 100, and D-Max = 10,000 meters (e.g., Apophis) we have:

    P-Personal = 6.86E-5 or 1 in 14,500 odds (that’s 48 times greater than the 1 in 700,000 odds being posted). If F-Death = 14.4 then we get 1 in 700,000 odds but that seems awfully close (i.e., 144 km away from a 10 kilometer impactor).

    And if we assume an even greater maximum impactor of 100 km, then the odds of personal destruction are 1 in 3,250 which is even more scary. For a maximum impactor of 1,000 km the odds are as high as 1 in 700 which is higher than many typical poker hands. So the whole calculation is dominated by the size of the maximum impactor.

    /Scare-the-pants-off-everyone-mode = off

  65. Tom Marking

    Sorry, D-Max = 10,000 meters is NOT Apophis which is only 350 meters. Meant to say Chixculub, the dinosaur killer which was roughly that size.

  66. Tom Marking

    “Call it 3,000 anyway just to make my math easier. Wouldn’t that mean that in any 10 year period your chances of dying in a terrorist attack are a little closer to 1 in 1 million.”

    300 million divided by 3,000 is 100,000 and NOT 1 million

  67. Tom Marking

    Also, considering ocean strikes that generate tsunamis then F-Death will be quite large because tsunamis can cross entire oceans and still have enough energy to kill people. Perhaps F-Death is then ~1,000 for ocean strikes. Then if D-Max = 10 kilometers and L = 70 years:

    P-Personal = 1 out of 145

    Ooo, truly scary now!

  68. mk

    @ Nigel…

    Thanks very much. Not familiar too with flikr, obviously.

  69. KC

    Shane:

    Statistically it’s a different metric because the threat isn’t constant. For example, from, oh, 1708 to 1808 there was a significant risk of Indian raids along the East coast of the U.S. By 1908 that risk was non-existent. And even between 1708 and 1808 that risk wasn’t constant.

    Right now we have a high risk of terrorism. That risk was much lower (note, not non-existent) prior to the first attempt on the World Trade Center. This has to be taken into consideration. Plus, there’s the statistical “gotcha” of only looking at successful terrorist attempts verses attempts foiled or aborted due to pressure from law enforcement.

    OTOH, the risk from asteroids, meters, and comets has been constant for millions of years. This is more on the level of a natural disaster such as tsunamis. Thus this makes a frame of reference than terrorism. The scale of disaster is also comparable.

  70. Grand Lunar

    I figured the Ares rockets, likely the Ares V, could be a good rocket to be used in taking care of an incoming asteroid. I hope the govt won’t mind using a few nukes to deflect a potential impactors course.

    @quasidog;

    The US did try to help a nation with it’s food shortage, with a shipment of geneticaly modified corn. Well, fears of GE foods made them decline the offer.
    Also, we already sent out millions, if not more, in foreign aid.

    There is no easy, simply, scientific solution to ALL of humanity’s problems, because not everyone has the same solution to their problems. Ideals and cultural differences often get in the way.

    Countries can argue until the officals are blue in the face on how to solve our problems, but won’t get any closer to an actual solution.

    Also, consider that it’s the people of the US, not the govt, that are the ones that really need convincing. Think of how much is spent on tobacco, alcohol, and gambling.

    IMO, our going into space can, potentially, help solve our problems.

    “I don’t really care about trying to stop a meteor that may or may not hit us anyway…. ”

    It isn’t a question of “IF” a meteor will hit.

    It’s a question of “WHEN”.

  71. Gary Ansorge

    Tom:
    Consider that in ANY 122 year period your chances of dying are 100%.

    So, why worry???

    GAry 7

  72. @quasidog:
    This picture illustrates the reason you should be concerned about US politics, and who is elected:

    http://edkrebs.com/herb/apocalypsead.jpg

  73. Tom Marking

    @Gary Ansorge “Consider that in ANY 122 year period your chances of dying are 100%. So, why worry???”

    Because it makes a difference to me if I die in 2008 or in 2130. Or more to the point, in 2029 or 2036.

  74. Mark Hansen

    quasidog, if we do direct money that could go to detecting an Earth-impacting asteroid into solving starvation on Earth, that would be great. Until the first Earth-impactor came through and wiped out the very people you saved from starvation. This is the problem with either-or arguments. We need to get rid of starvation AND detect hazardous asteroids. A whole lot of other things need fixing as well but you get the point.

  75. SouthShoreSamurai

    Laurie, I tried to find this series of pictures of Mt. St. Helens you mentioned, but I couldn’t find precisely what you are talking about.

    Where could I find this series?

  76. Before we develop the capacity to divert asteroids, we have to worry about one blundering into us. After we have that capacity, we have to worry about Preznit Palin (Jr.) ordering a smiting on Tehran, or Hu Hsi on Taipei, or Putinovitch on Chechnya. Are we at the greater risk before or after?

    Asteroids make excellent weapons. They leave no radioactive fallout, they offer “deniability”, and they are indistinguishable from divine wrath.

    If Putinovitch or Palin Jr. gets the capability, the others bad better have it, too, in order to re-divert any ill-directed cometary bodies. One can onlyl hope the team on the way out to re-divert it suffers no unfortunate hyperkinetic mis-haps.

  77. quasidog

    @ Gary says”Quasidog: We do a lot to alleviate starvation world wide, sending billions in aid to third world countries every year. Some of that gets diverted into despot pockets, some is used to provide the indigenous peoples with the means to grow food. Some is actually food for hungry bellies. It’s a truism that the USA throws away enough food every day to feed…. yada”

    Yeah I am well aware of how it all works ( or doesn’t work ) however my point is the fact we can’t do it, so who gives a sh.. about an asteroid that may or may not happen.

  78. quasidog

    @ Mark .. no I don’t see it as a ‘either- or argument’. I am pointig out the epic fail that is humans not having the balls to even work out how to eliminate hunger and starvation, then having given that, I don’t see the point in worrying about asteroids. Yes asteroids are scary.

    It’s sort of like going outside and worrying about getting hit by a car, or running around pointing out that a car may hit people, when the people you are pointing out the ‘possibilty’ … remote possibilty even of it happening …. when at the same time everyone around you is starving, or has no money .. or whatever sob story spin you want to put on it … and ignoring that. Deal with the problems at hand first. The immediate issues first. I’m pretty sure world hunger, disease, war, economy, whatever ….. is something we should put all our efforts into first, before we put that same amount of energy into the small chance an asteroid might wipe us out.

    Yes, hunt for asteroids that, may hit us… go hard. I really don’t want to be hit by one. Just don’t take the spotlight away from the other .. bigger .. more immediate issues. I am not saying it is an ‘either-or’.

  79. quasidog

    I will also point the the odds that Phil has pointed out of the event happening as a good reason why we; yes should watch the skies for the possibility, but watch the bad stuff that is happening in our own back yards and our neighbours, and try to deal with that, first. It is just a priority thing.

  80. Ryan

    I used to do these type of fun calculations with my astronomy section. We actually estimated the chance of getting directly hit by an asteroid, and came up with a number close to the actual value (a few people in the past 100 years). Another interesting calculation is how likely is it that an airplane has been hit by a big enough asteroid to take it down. Although it is incredibly unlikely that your airplane will crash, it is pretty likely (>50%) that it has already happened in the past 20 years).

  81. Gary Ansorge

    Priorities mean little when the big impacters arrive.

    Taking care of those “little” problems is energy dependent. Wealth is energy dependent. The more energy we have access to, the more peripheral endeavors we can accommodate, such as feeding the poor, providing universal health care, educating one and all, etc.. One might note that (30 years ago) in Asia, there was so little excess energy/wealth that dogs were food. Today, the rising middle class in China actually has enough excess wealth to enable them to treat dogs as PETS. You might call that trickle down compassion. When wealth is limited, people can’t afford to worry about the poor horse caught in a river. When people are rich, we worry about ALL the disadvantaged,,,
    Roughly half the world is still living in a subsistence economy. That changes when energy drives industry and intensive farming, when a rising standard of living frees up our compassion.

    The only open ended source of energy in this solar system is the sun. All we need to do is access that source efficiently with power sats and the energy economy of the world can rise by orders of magnitude, per capita wealth can explode and we have the excess wealth to perform near miracles.

    We are SOOO close to implementing the Dyson Type II civilization. All we need to do is make the commitment to go out and do it,,,

    GAry 7

  82. Jim S

    I’m a little confused. You say the odds of death by meteorite are something like 1 in 700,000 for any living person. Doesn’t that mean that of the 6,550,000,000 people currently alive that something like 9,300 of those people (6.55 Billion/7 Hundred Thousand) will die by meteorite? Nothing like that many people have died by meteorite in the past century! A quick google search showed the last meteor that struck someone fell in 1954 (admittedly, a hasty search that was in no way thorough), and she lived (the woman, not the meteor)! By contrast, close to three thousand Americans were killed by terrorists in the past decade. If you are an American who was alive then, the chance you were one of those in 2001 that died was 1 in a little over a one hundred thousand (280+ Million Americans in 2001/approximately 2750 dead at the WTC). Worldwide, the chance drops to 1 in 2.2 million (6 Billion/2750). This estimate is lower than the 1 in 700,000 number, but I’m still wondering how that estimate was reached in the first place. Further note that I haven’t bothered to include the deaths from the Bali bombings, the Marines killed in a disco in Lebanon in the ’80′s, the plane that crashed into the Pentagon or any of the many smaller terrorist attacks of the past 50 years.

  83. “I’m a little confused. You say the odds of death by meteorite are something like 1 in 700,000 for any living person. Doesn’t that mean that of the 6,550,000,000 people currently alive that something like 9,300 of those people (6.55 Billion/7 Hundred Thousand) will die by meteorite?”

    No, that’s the wrong way to think about it. The probability that any given human being is killed by an asteroid or a comet of 1 in 700,000 (more likely to by 1 in 15,000 as I’ve shown) is dominated by extremely rare events (i.e., impacts of large objects). If you included just the small impactors (100 meters or less in size) then the odds are reduced by a factor of 20. So the events that are likely to actually happen within a person’s lifetime make up only 5 percent or less of the statistic. The extremely rare events make up 95 percent of the statistic, even though they never happened in your lifetime, your father’s lifetime, your grandfather’s lifetime, or even during recorded history.

    That doesn’t change the statistic at all. The assumption that these events never occurred during all of human history and therefore can never occur in the future, is entirely an illusion. Tomorrow may be entirely different than anything anyone has ever experienced before.

  84. @Gary Ansorge “We are SOOO close to implementing the Dyson Type II civilization. All we need to do is make the commitment to go out and do it”

    Close? Sure, if by close you mean off by a factor of 10 trillion. We are currently a type 0.7 Kardashev civilization. To get to type 2.0 status we need to increase our energy output by a factor of 1.0E13.

  85. K9 is always right

    shane Said on October 14th, 2008 at 5:14 am :

    “The dinosaurs that pushed the KT event rock into the planet will be back… one day…”

    Yeah, that has already happened & been stopped by the Doctor in Jon Pertwee incarnation a coupleof times actually : the Silurians and the Sea Lizards. ;-)

  86. StevoR

    I thouyght I had thepicture with saying it was from :

    “Filming ‘Independence Day’ movie the bit where the saucer crashes with Wil Smith either flying it or forcing the alien to crash! “I could’da been at a barbecque!”

    Am I right?

    D’oh! Turns out I’m not. :-(

    But Phil about that 10km *Comet* threat – any response? Please?

    Oh & no one has anything to say on slamming the Near Earth Asteroids into Venus and using that as a terraforming tool either? Is it too dumb or something in the idea or ..?

  87. Tom Marking

    @StevoR: “But Phil about that 10km *Comet* threat – any response? Please?”

    I think Phil has already moved on. From what I can gather the cometary threat is poorly understood but it may be significant. And we will not typically receive decades of warnings before impact as we do with asteroids. For comets following nearly hyperbolic orbits the warning period may be only a matter of months.

    http://www.lpl.arizona.edu/~marcus/CollinsEtAl2005.pdf

    “Currently, the relative importance of comets to the Earthcrossing impactor flux is not well-constrained. The Near-Earth Object Science Definition Team (2003) suggests that comets comprise only about 1% of the estimated population of small NEOs; however, there is evidence to suggest that, at larger sizes, comets may comprise a significantly larger proportion of
    the impactor flux (Shoemaker et al. 1990).”

  88. Tom Marking

    @StevoR: “slamming the Near Earth Asteroids into Venus and using that as a terraforming tool either?”

    The problem is how much of the planetary atmosphere actually gets ejected from the planet? For impactors less than ~100 km the answer is probably not much. The ejecta travel through the atmosphere and may reach escape velocity. That does not necessarily mean that they impart such a velocity to the gas molecules themselves.

  89. StevoR

    Thanks Tom. :-)

    Your answers are appreciated. :-)

  90. Melvin Goldstein

    Question: question 12 in “Thinking Physics” – page 259
    Inside a warm damp cave completely sealed off from the outside world could life flourish indefinitely?

    Answer: No life forms could flourish indefinitely. In an isolated system, entropy always increases. Life tries to push entropy in the opposite direction. When life is created, entropy decreases in the cave but nature demands a greater entropy increase offset. The cave, being sealed, would mean that entropy would reach its max, thus energy necessary to sustain and generate new life would be unavailable. Maybe we should learn a lesson from this. Available energy is mandatory. Wealth may equate to available energy. If you want to live in a nation that is prospering make sure that its available energy supply is abundant.

    Entropy is one of “Physics Foibles”

  91. random guy

    im not sure if anyone mentioned this (becuase there was far to much to read) but not only that from space our planet appears to be coverd in nats.From broken satalites and other debris so we have a sort of shield but not to mention(again) that we have comet swallowers(Gas Gaints(Iupitar,Satarn,Neptune,Uranis) in our solar system who will most likly prevent most celestial bombardment.By (with there gravity) pulling of comets and larger meators(from out of our sytem)into them selves or out of our way.

  92. Argentinian guy

    It seems like it happened today in Argentina? First time in the story?

  93. Pds314

    Who here thinks that 10km isn’t big enough for 100% kill-rate? I mean, Little Boy (Hiroshima nuke) only killed a fraction of the people within a mile, yet it leveled many structures within that radius and set most ignitables on fire within minutes if that.
    If humans can survive that sort of hellish environment, then being 3000km from a deep-sea, 10km iron impact at 17km/s would only be able to hurt you with the tsunami and the 103 mph winds, while that sounds severe, 103 mph is laughable in terms of destroying buildings or crushing people.

    when the water is only average ocean depth, the impact is basically the same, but one gets 6 hours of tsunami warning instead of 3, and the tsunami is half as big.

    if it lands on a continental shelf only 200 meters deep, at 3000km away, you would have a full 19 hours before the tsunami arrived at some other coast. at your distance, and it would be a dangerous, but not apocalyptic, 15-30 feet high.

    if it lands on sedimentary rock, one can expect only broken windows and branches blown from trees.

    the same is true if it lands on crystalline rock.

    in fact, before their is even a good chance of a quick kill on a land-locked person 10,000km
    away. one needs a 40km asteroid to break down SOME of the buildings there, and one would need a massive, 50km asteroid to throw someone at temrinal velocity, never mind the 100km-wide asteroid it would take to MAYBE kill someone in a trench sitting in the middle of the great plains.

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