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Tunguska Blast Was a Small Asteroid
Posted by
kdawson
on Wed Dec 19, 2007 02:37 AM
from the fire-came-by dept.
from the fire-came-by dept.
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."
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Science: Crater From 1908 Tunguska Blast Found 192 comments
MaineCoasts writes "A team of scientists from the Marine Science Institute in Bologna claims to have found the crater left by the aerial blast of a comet or asteroid in 1908 in the Tunguska region of Siberia. The blast flattened 770 square miles (2,000 square kilometers) of forest, but to date no remains or crater have been found. This has left open the question of what kind of object made the impact. The team believes that, contrary to previous studies, nearby Lake Cheko is only one century old and 'If the body was an asteroid, a surviving fragment may be buried beneath the lake. If it was a comet, its chemical signature should be found in the deepest layers of sediments.' The team's findings are based on a 1999 expedition to Tunguska and appeared in the August issue of the journal Terra Nova."
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Science: Chance for a Tunguska Sized Impact on Mars 184 comments
Multiple users have written to tell us of an LA Times report that an asteroid may hit Mars on January 30th. The asteroid is roughly 160 feet across, and JPL-based researchers say that it will have a 1-in-75 chance of striking Mars. Those odds are very high for this type of event, and scientists are hoping to witness an impact of a similar scope to the Tunguska disaster. From the LA Times:
"Because scientists have never observed an asteroid impact -- the closest thing being the 1994 collision of comet Shoemaker-Levy with Jupiter -- such a collision on Mars would produce a 'scientific bonanza,' Chesley said."
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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?
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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...
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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.
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Re:The Gist (Score:4, Funny)
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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.
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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.
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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...)
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I've often wondered (Score:5, Interesting)
Re:I've often wondered (Score:5, Funny)
Badly.
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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.
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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.
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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.
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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.
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Re:Doh! (Score:4, Funny)
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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.
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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.
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