malachiorion writes "The Tunguska event, an explosion on June 30, 1908, cleared an 800-sq.-mi. swath of Siberian forest. Was it a UFO crash? An alien weapons test? Now, Sandia National Laboratories has released its own explanation for the Tunguska event. Using supercomputers to create a 3D simulation of the explosion, the Department of Energy-funded nuke lab has determined that Tunguska was, indeed, the explosion of a relatively small asteroid. The simulation videos are well worth checking out — they show a fireball slamming into the earth from the asteroid's air burst. The researchers caution that we should be keeping watch for many more small, potentially earth-impacting asteroids than we are currently tracking."
It seems that while the asteroid itself did not cause as much damage as previously believed (3-5 megatons vs 10-20), the asteroid was most likely much smaller than had been estimated. Too bad the article doesn't give some numbers about the size. Pretty scary thinking about one of these things hitting on top of or near a major population center.
by Anonymous Coward
on Wednesday December 19 2007, @03:01AM (#21749280)
Pretty scary thinking about one of these things hitting on top of or near a major population center.
Yes, every asteroid on television will undoubtedly hit over New York or Los Angeles. There must be some exceptionally high gravitational field at those locations.
Perhaps these dramatic presentations aren't really that helpful. It could be that volcanoes won't erupt under Los Angeles, ice hurricanes won't hit New York, and 10.0 earthquakes won't toss Los Angeles into the Pacific Ocean (and why isn't Chicago or London ever destroyed?). It might be helpful for you to calculate the area that the Tunguska Blast caused devastation, divide by the surface area of the earth, multiply it by the surface area of our major population centers, and then multiply it by the probability of this type of event occurring in the next 50 years. But this is boring and lacks the 'scary thinking' and drama, right?
Yes, every asteroid on television will undoubtedly hit over New York or Los Angeles. There must be some exceptionally high gravitational field at those locations.
I'm not sure about that, most of the asteroid I had seen on television are hitting Kansas, particularly this small village...
Yes, every asteroid on television will undoubtedly hit over New York or Los Angeles. There must be some exceptionally high gravitational field at those locations.
I'm less concerned about a single city, which would be devastating but survivable. What scares me more was the (2004?) near-miss of an asteroid that could have hit somewhere in Pakistan or India precisely when they were in the middle of a very tense standoff. With immature command/control systems, what are the odds that would escalate into a nuclear shooting war, which would kill not the 10's or 100's of thousands of a single strike, but the 10's or 100's of MILLIONS of the resulting conflict.
The article doesn't give direct numbers about the size. It says:
Because of the additional energy transported toward the surface by the fireball, what scientists had thought to be an explosion between 10 and 20 megatons was more likely only three to five megatons. The physical size of the asteroid, says Boslough, depends upon its speed and whether it is porous or nonporous, icy or waterless, and other material characteristics.
Let's pick the middle ground and say four megatons, that's 1.67E16 joules. From what I can see, non-metallic asteroids really aren't all that dense because they tend to be very porous, and it seems likely that a metal asteroid wouldn't explode in this manner but would instead impact and bury itself. So call it 2600 kg/m^3. Assuming Earth escape velocity is probably a safe bet as well; it's possible the thing was an extra-solar object but not likely. So that's 11km/sec. Unless I'm screwing something up, I get a mass of 276,000,000 kg, and a spherical asteroid 30 meters in diameter.
I am on firm ground there? I mean, the only source of energy driving the explosion is the kinetic energy of the asteroid, it's just heating the thing up and making it go boom.
It appears that most asteroids are conglomerates of shale, so they wouldn't be that dense, as in not that densely packed. That's why the idea of blasting them with nukes is a bad idea, they just seperate and reform later.
By reform I'm guessing that you mean reform via gravity? And since we are dealing with asteroids would it be safe to say that 'later' is later on an astrological time scale?
On that scale, I can live with a 'temporary' fix. (Live, have children, grow old, die, kids grow old...)
...how the populations (including the military) in some of the more... nervous areas of the globe would react to a suddden blinding light in the sky followed by an enormous blast wave.
I've often wondered...how the populations (including the military) in some of the more... nervous areas of the globe would react to a suddden blinding light in the sky followed by an enormous blast wave.
I'm currently reading Arthur C. Clarke's 'Rendezvous with Rama', which opens with the lines "Soon or later, it was bound to happen. On June 30, 1908, Moscow escaped destruction by three hours and four thousand kilometers -- a margin invisibly small by the standards of the universe."
In the book, we humans then go on to set up systems to track asteroids that may be a danger to earth, and set up defense systems against them. I know that we currently track some, but how well funded are these organizations that do this? This is really something that is quite important, as it is almost certainly just a matter of when, not if. Do we have systems in place that will allow us to destroy or divert any large asteroids that are determined to be on a path to impact with earth?
The British MP Lembit Opik (name is Scandinavian) has attempted to draw attention to the seriousness of the problem. The media dismiss him as a crank. Watching him on television it has been apparent that television presenters and the like are bottomlessly ignorant on the subject, and because they can't admit it, they just seek to trivialise the issue.
OK, we shouldn't expect media people to know everything, but we are very poorly served by their almost total scientific ignorance. I suspect that politicians would have become interested in global warming much sooner were the mass media not so piss poor at explaining scientific issues to the public, and almost perversely proud of it.
The British MP Lembit Opik (name is Scandinavian) has attempted to draw attention to the seriousness of the problem. The media dismiss him as a crank.
I wonder why they do dismiss him? Global warming was the same. It seems curious in the face of the fact that the media, and the UK media in particular, spend most of their energy drumming up irrational abstract things to be afraid of (terrorists, pedophiles, etc etc), things which are unlikely to ever affect many in the UK.
The computer simulation is interesting, but the Tunguska event is unlikely to be an asteroid. There were strange events reported in the area for days prior to the explosion, there were odd lights, etc.
An alternative explanation was proposed by Wolfgang Kundt, a researcher at the Institut für Astrophysik, University of Bonn:
The basic proposal is that there was a natural gas leak, from the Earth. The gas rose to a certain height, then drifted downwind. After several days, a lightning strike ignited the airborne gas, and the flame then traveled along line (of drifted gas), to the ground source.
It is worth reading the article. An asteroid impact is sexy, but the alternative explanation fits with the data much better.
It is worth reading the article. An asteroid impact is sexy, but the alternative explanation fits with the data much better.
And how does a natural gas explosion leave the nickel and iridium deposits that were found at the site? An asteroid impact is not the accepted theory because it is "sexier", but because of Occam's razor.
Expeditions sent to the area in the 1950s and 1960s did find microscopic glass spheres in siftings of the soil. Chemical analysis showed that the spheres contained high proportions of nickel and iridium, which are found in high concentrations in meteorites, and indicated that they were of extraterrestrial origin.
I've seen the 'natural gas' theory before. It's so contrived that it's almost like science-comedy.
The points raised by the paper you linked to which I found compelling were. ..
1. That there have been far more events in recorded history similar to Tunguska which have been volcanic or geologic in nature than have been due to cometary impact, raising the question of probabilities. --Mt. Saint Helens blowing its top in 1980 is an example, as was Krakatoa in 1983. There was also the 1986 limnic eruption of 1.6 million tonnes of CO2 from Lake Nyos which suffocated 1,800 people in a 20 mile radius. Sometim
1. That there have been far more events in recorded history similar to Tunguska which have been volcanic or geologic in nature... Mt. Saint Helens... Krakatoa... Lake Nyos... And which of these are examples of the supposed megaton range methane gas explosions? Why... none of them. Sorry, unrelated geophysical events don't provide any precedent for the proposed mechanism. The notion seems a bit difficult to buy into - the explosive limits for methane in air is usually quot
Horizon is the worst for sensationalising pseudo-science. Many years ago it was a serious science documentary series.. not it's just unwatchable trash.
The new simulation which more closely matches the widely known facts of destruction than earlier models shows that the center of mass of an asteroid exploding above the ground is transported downward at speeds faster than sound. It takes the form of a high-temperature jet of expanding gas called a fireball.
The theory I've heard a few times was that it was anti-matter. Doctor Raymond Stanz, however, postulated that it may have been the result of a dimensional crossover. This theory has not been widely accepted, though, because no P.K. readings have been captured to support this claim.
Summaries on/. have started to deteriorate in quality. Was there any need for the above? Isnt it just pandering to the WOOWOOists? Why the need to add a tinge pseudo-science to science?
You wont add "Is it the by homeopathy? Ayurveda perhaps" to an article on a new medicine/cure..
Free American English Lesson: Adverbs modify verbs.
Verb in the Subject Sentence: Missed (past tense)
Context: This asteroid was very near to Earth when it missed us.
Adjective: Near (adverb form: nearly)
Thus: The asteroid nearly missed Earth.
Your sentence gets a thumbs up by me! ...Grammar Nazis, please keep walking.:)
Would there be any chance of a small asteroid (one that could cause some problems) currently heading for earth not be detected yet by scientists?
Yes. There is a very real chance that a chunk of rock the size of a basketball court could come at us tomorrow. A very very small, but very real chance. Asteroids that come from the sunward side of Earth's orbit are harder to detect because they are obscured by the Sun. One could come from that direction and astronomers may never see it. Most of the meteors that streak across the night sky are space stones no bigger than your hand, and usually about the size of a pea or smaller. Larger ones come down, but very infrequently. It is impossible for astronomers to chart, track or project the trajectories of the billions of space rocks left over from the formation of the Solar System.
Imagine a world where a small asteroid fragment or comet had struck Russia 60 years after Tunguska - during the depths of the Cold War. It would be a very different world today indeed.
I'll grant you that they do not explode in the traditional TNT/explosives sense of the word. However, falling space debris can indeed "explode" when entering the atmosphere. As they push deeper and deeper and the air gets thicker, it presents more and more resistance on the falling object. Eventually, the wall of air becomes so dense that the action-reaction forces break the falling object up. Violently. Combine that with the fact that the asteroid/comet/meteor and surrounding air has been heated significan
A 3-5 megaton blast over the Atlantic wouldn't cause so much as a rough surf advisory in Key West. In comparison, the USA built a 45 megaton bomb and the USSR's fission-fusion-fission Tsar Bomba would have been 100+ megatons had they not taken the sensible precaution of replacing the final fission stage with inert lead. If a mere 5 megaton warhead could cause such worldwide devastation, I'm pretty sure someone would have mentioned it before now (and trust me, I've read just about every far-fetched doomsday scenario imaginable.)
As for the possibility of similar-sized asteroid impacting the ocean instead of exploding above it--well, the article only says that the asteroid is now thought to be "only a fraction as large as previously published estimates". That doesn't tell us anything. The Tunguska asteroid may or may not have been large enough to trigger a tsunami had it impacted an ocean instead of exploding over land. I'm going to assume that an impact will usually be less energetic (though perhaps more concentrated) than a heat-induced explosion, in which case no, the Tunguska asteroid never posed a significant threat to the world as a whole.
That said, the Tunguska explosion is still fascinating as hell. I know that there's a lot of very strong evidence pointing to the asteroid theory, but it's still fun to toy with conspiracy theories. The atomic bomb was first being conceived of, Tesla's Wardenclyffe Tower was being tested (by some accounts, it was brought online the day before the explosion)... it's all absolute rubbish, to be frank, but it's very entertaining rubbish.
The Gist (Score:5, Informative)
Re:The Gist (Score:5, Interesting)
Perhaps these dramatic presentations aren't really that helpful. It could be that volcanoes won't erupt under Los Angeles, ice hurricanes won't hit New York, and 10.0 earthquakes won't toss Los Angeles into the Pacific Ocean (and why isn't Chicago or London ever destroyed?). It might be helpful for you to calculate the area that the Tunguska Blast caused devastation, divide by the surface area of the earth, multiply it by the surface area of our major population centers, and then multiply it by the probability of this type of event occurring in the next 50 years. But this is boring and lacks the 'scary thinking' and drama, right?
Parent
Re:The Gist (Score:5, Funny)
I'm not sure about that, most of the asteroid I had seen on television are hitting Kansas, particularly this small village...
Parent
Re: (Score:3, Insightful)
Re: (Score:3, Insightful)
Re: (Score:3, Funny)
That's called "wishful thinking".
Re:The Gist (Score:5, Funny)
No, they just suck.
Parent
Re:The Gist (Score:4, Funny)
Parent
Re: (Score:3, Insightful)
Re:The Gist (Score:4, Insightful)
What scares me more was the (2004?) near-miss of an asteroid that could have hit somewhere in Pakistan or India precisely when they were in the middle of a very tense standoff. With immature command/control systems, what are the odds that would escalate into a nuclear shooting war, which would kill not the 10's or 100's of thousands of a single strike, but the 10's or 100's of MILLIONS of the resulting conflict.
THAT'S terrifying.
Parent
Re:The Gist (Score:4, Interesting)
Let's pick the middle ground and say four megatons, that's 1.67E16 joules. From what I can see, non-metallic asteroids really aren't all that dense because they tend to be very porous, and it seems likely that a metal asteroid wouldn't explode in this manner but would instead impact and bury itself. So call it 2600 kg/m^3. Assuming Earth escape velocity is probably a safe bet as well; it's possible the thing was an extra-solar object but not likely. So that's 11km/sec. Unless I'm screwing something up, I get a mass of 276,000,000 kg, and a spherical asteroid 30 meters in diameter.
I am on firm ground there? I mean, the only source of energy driving the explosion is the kinetic energy of the asteroid, it's just heating the thing up and making it go boom.
Parent
Re:The Gist (Score:4, Interesting)
By reform I'm guessing that you mean reform via gravity? And since we are dealing with asteroids would it be safe to say that 'later' is later on an astrological time scale?
On that scale, I can live with a 'temporary' fix. (Live, have children, grow old, die, kids grow old...)
Parent
I've often wondered (Score:5, Interesting)
Re:I've often wondered (Score:5, Funny)
Badly.
Parent
Re: (Score:3, Funny)
The answer's obvious then.
Nuke God.
You've got to admit, it'd solve a hell of a lot of problems.
Re: (Score:3, Funny)
Oh come off it! (Score:5, Funny)
Re: (Score:3, Funny)
http://www.reuters.com/article/oddlyEnoughNews/idUSEIC85598720071219 [reuters.com]
Currently Reading. (Score:5, Insightful)
In the book, we humans then go on to set up systems to track asteroids that may be a danger to earth, and set up defense systems against them. I know that we currently track some, but how well funded are these organizations that do this? This is really something that is quite important, as it is almost certainly just a matter of when, not if. Do we have systems in place that will allow us to destroy or divert any large asteroids that are determined to be on a path to impact with earth?
Re:Currently Reading. (Score:5, Funny)
Only one. [wikipedia.org] Be very afraid.
Parent
Insufficient political attention (Score:4, Insightful)
OK, we shouldn't expect media people to know everything, but we are very poorly served by their almost total scientific ignorance. I suspect that politicians would have become interested in global warming much sooner were the mass media not so piss poor at explaining scientific issues to the public, and almost perversely proud of it.
Parent
Re: (Score:3, Insightful)
I wonder why they do dismiss him? Global warming was the same. It seems curious in the face of the fact that the media, and the UK media in particular, spend most of their energy drumming up irrational abstract things to be afraid of (terrorists, pedophiles, etc etc), things which are unlikely to ever affect many in the UK.
Here are issues that, while rare
Sometime in the future (Score:4, Funny)
Gitmo next for kdawson (Score:5, Funny)
Unlikely to be an asteroid (Score:4, Interesting)
An alternative explanation was proposed by Wolfgang Kundt, a researcher at the Institut für Astrophysik, University of Bonn:
Kundt W. (2001),
“The 1908 Tunguska catastrophe: An alternative explanation [ias.ac.in]”,
Current Science, 81: 399–407.
The basic proposal is that there was a natural gas leak, from the Earth. The gas rose to a certain height, then drifted downwind. After several days, a lightning strike ignited the airborne gas, and the flame then traveled along line (of drifted gas), to the ground source.
It is worth reading the article. An asteroid impact is sexy, but the alternative explanation fits with the data much better.
Re:Unlikely to be an asteroid (Score:5, Interesting)
Parent
Re:Unlikely to be an asteroid (Score:5, Informative)
One of many references if you'd bothered to look: http://www.physorg.com/news819.html [physorg.com]
Pertinent section:
Expeditions sent to the area in the 1950s and 1960s did find microscopic glass spheres in siftings of the soil. Chemical analysis showed that the spheres contained high proportions of nickel and iridium, which are found in high concentrations in meteorites, and indicated that they were of extraterrestrial origin.
I've seen the 'natural gas' theory before. It's so contrived that it's almost like science-comedy.
Parent
Evidence is compelling. . . (Score:3, Interesting)
1. That there have been far more events in recorded history similar to Tunguska which have been volcanic or geologic in nature than have been due to cometary impact, raising the question of probabilities. --Mt. Saint Helens blowing its top in 1980 is an example, as was Krakatoa in 1983. There was also the 1986 limnic eruption of 1.6 million tonnes of CO2 from Lake Nyos which suffocated 1,800 people in a 20 mile radius. Sometim
Re: (Score:3, Interesting)
Compelling evidence? Lets see...
1. That there have been far more events in recorded history similar to Tunguska which have been volcanic or geologic in nature... Mt. Saint Helens ... Krakatoa ... Lake Nyos... And which of these are examples of the supposed megaton range methane gas explosions? Why... none of them. Sorry, unrelated geophysical events don't provide any precedent for the proposed mechanism. The notion seems a bit difficult to buy into - the explosive limits for methane in air is usually quot
Horizon (Score:4, Interesting)
Re: (Score:3, Informative)
Horizon is the worst for sensationalising pseudo-science. Many years ago it was a serious science documentary series.. not it's just unwatchable trash.
Mirror (Score:5, Informative)
The videos total over 56 Megabytes, so I have put up a mirror Here [fransman.fr]
Fireball (Score:3, Funny)
The new simulation which more closely matches the widely known facts of destruction than earlier models shows that the center of mass of an asteroid exploding above the ground is transported downward at speeds faster than sound. It takes the form of a high-temperature jet of expanding gas called a fireball.
Good thing we made the Saving Throw!
Re:Doh! (Score:5, Funny)
In Soviet Russia, the forest flattens the asteroids!
I welcome our new asteroid overlords.
Imagine a beowulf cluster of those!
Parent
Re: (Score:3, Funny)
Nothing to see here! Move along!!
Re: (Score:3, Funny)
Re: (Score:3, Interesting)
2) A tiny bit of antimatter
Re: (Score:3, Funny)
4) Profit!!!
There Fixed that for you.
Re:Doh! (Score:5, Funny)
The theory I've heard a few times was that it was anti-matter. Doctor Raymond Stanz, however, postulated that it may have been the result of a dimensional crossover. This theory has not been widely accepted, though, because no P.K. readings have been captured to support this claim.
Parent
Re:Doh! (Score:4, Funny)
Parent
Bad Summary (Score:3, Insightful)
Summaries on
You wont add "Is it the by homeopathy? Ayurveda perhaps" to an article on a new medicine/cure..
Editors/Firehosers note.
A Comet (Score:3, Interesting)
Re:Doh! (Score:5, Funny)
Yeah, Chuck Norris showed up...
Parent
Re:Hmm.. (Score:5, Informative)
So to answer your question: Yes, it's very possible!
Parent
Re: (Score:3, Informative)
Verb in the Subject Sentence: Missed (past tense)
Context: This asteroid was very near to Earth when it missed us.
Adjective: Near (adverb form: nearly)
Thus: The asteroid nearly missed Earth.
Your sentence gets a thumbs up by me!
Re:Hmm.. (Score:4, Informative)
It nearly HIT earth. The problem with the sentence is the verb, not the construction.
Parent
Re:Hmm.. (Score:5, Insightful)
Imagine a world where a small asteroid fragment or comet had struck Russia 60 years after Tunguska - during the depths of the Cold War. It would be a very different world today indeed.
Parent
Re: (Score:3, Funny)
It'll just probably break some windows and throw some chairs around.
Re: (Score:3, Informative)
Nah, would be no biggie. (Score:5, Interesting)
As for the possibility of similar-sized asteroid impacting the ocean instead of exploding above it--well, the article only says that the asteroid is now thought to be "only a fraction as large as previously published estimates". That doesn't tell us anything. The Tunguska asteroid may or may not have been large enough to trigger a tsunami had it impacted an ocean instead of exploding over land. I'm going to assume that an impact will usually be less energetic (though perhaps more concentrated) than a heat-induced explosion, in which case no, the Tunguska asteroid never posed a significant threat to the world as a whole.
That said, the Tunguska explosion is still fascinating as hell. I know that there's a lot of very strong evidence pointing to the asteroid theory, but it's still fun to toy with conspiracy theories. The atomic bomb was first being conceived of, Tesla's Wardenclyffe Tower was being tested (by some accounts, it was brought online the day before the explosion)... it's all absolute rubbish, to be frank, but it's very entertaining rubbish.
Parent