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How can a meteorite explode?


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#21 Toothpix   Crossbones+   -  Reputation: 810

Posted 18 February 2013 - 04:19 PM

I'll tell you how they explode: Bruce Willis.

 

All horribly cheesy Armageddon references aside, someone would have noticed by now if that was a ballistic missile, as radiation counts would go off the charts in Russia.


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#22 phantom   Moderators   -  Reputation: 7260

Posted 18 February 2013 - 04:24 PM

I'm not sure if samoth has taken too many pills, or too few pills, but I think it's safe to say he hasn't taken the right amount.

Also his tin foil hat appears to have fallen off.

#23 Chindril   Members   -  Reputation: 172

Posted 18 February 2013 - 04:39 PM

samoth, where did I say I was 100% convinced it was a meteorite ?  I'm only 99.9% sure of that.

 

What I said was I'm 100% convinced it is NOT a north korean missile. Not only every video shows clearly that it is NOT a missile (seriously, don't even question it), but if it was a nuclear missile from north korea that exploded about Russia, Russia would be at war today.

 

And about this quote:

Well, that is somewhat of a distorted way of putting it, but what's really scary is that you're almost fanatic about not letting the slightest possibility it might be something different than what it looks like at first sight.

 

There are very few things I take for granted or trust without questioning and I usually stay out of conspiracy theories because of that, however your conspiracy is about the same level of the flat earther's. If by some miracle you are right, I'll gladly come back on GD.net and apologize publicly.

 

EDIT: some spelling mistakes


Edited by Chindril, 18 February 2013 - 04:39 PM.


#24 laztrezort   Members   -  Reputation: 965

Posted 18 February 2013 - 04:45 PM

Since this is a programming forum, forget Occam's Razor - lets use duck typing (test).

 

If it quacks and walks like a meteorite, then it is a meteorite.

 

Also, this thread reminds me of the the question

"If a meteor made out of diamond and 100 feet in diameter was traveling at the speed of light and hit the earth, what would happen to it?"

 

The answer to above question is here: http://what-if.xkcd.com/20/



#25 Hodgman   Moderators   -  Reputation: 30351

Posted 18 February 2013 - 07:05 PM

If it was a nuke, then people in Europe and Asia should be able to measure a slight increase in ambient radiation by now, right? That is, normal citizens with Geiger counters could verify this (not government operatives, and every member of the comprehensive test ban treating who are obviously in on the conspiracy - the same operatives who are covering up the fact that the invaders are poisoning your food and water supplies mwa ha ha ha)...

 

Let's assume that is the correct number, and assume that only 1% of this was left in the big piece falling into the lake afterwards.

What makes you think that it would break apart into no more than 100 fragments? If it was 10k tons to begin with, then you're talking about a 100 ton boulder falling into the lake, not a tiny bit of shrapnel weighing a few grams.

 

According to report from NASA the object had diameter of maximally 17 m, mass around 10000 tonnes (a really heavy one, because their density is often less than water density) and velocity 17900 m/s. Kinetic energy of this object is 1602050000000000 J = 1602 TJ. Energy equivalent (in TNT) of this kinetic energy value is around 383 kTons of TNT - e.g. we need at least 383 kTons of TNT equivalent energy to just stop the motion of the meteorite. Assuming that energy of explosion must be higher than just kinetic energy (it's calculated using the thermodynamic energy of detonation) - we could get somewhere to 500 kTons.

My first mental picture (an I'm sure a few other people) - is that of an object that's equivalent to x-thousand tons of TNT falling from the sky, and then at some certain altitude, exploding suddenly, releasing all that energy...

...but I guess the energy release is a lot different than that. From the very moment that it touches the air it's energy is decreasing, as it's converted into sound and heat and deceleration. It's more as if that this giant bundle of TNT is constantly lighting fuses of individual sticks and throwing them out from the bundle. Eventually the bundle itself is lit, but by that point it's a lot smaller than it was initially.

 

Also, I used to think of sonic booms as an event that occurs as you cross the sound barrier: at that point in time, there is a loud thunderclap of noise... but I don't think this is really true either. For the entire length of time that the object is travelling faster than the speed of sound, it's emitting a sonic boom.

To compare it to a bullet, if you shoot at someone several hundred meters away --

* From your point of view: as soon as you fire, there is a crack from the explosion in the barrel, and a simultaneous boom from the bullet being accelerated to a supersonic speed. 

* From their point of view: just after the bullet has whizzed past them, there will hear the sonic boom that it's leaving as a conical trail. A moment later they will hear the explosion from your barrel.

* If the bullet passes past a person far enough away so that it's slowed down to a sub-sonic speed, then they might not hear it make a sound at all besides a quiet whizz.

 

So in the videos, when we hear a giant boom, it's not necessarily any kind of explosion at all right? It's likely just the noise of the object moving through the air, which due to it's speed, has been compressed into a sonic boom, which has just reached the observer. Is it this boom that broke the windows, or was there actually a sudden explosion with a powerful shockwave as well? Is it basically one very long explosion that lasts for it's entire descent?


Edited by Hodgman, 18 February 2013 - 09:35 PM.


#26 maxgpgpu   Crossbones+   -  Reputation: 279

Posted 18 February 2013 - 08:47 PM

One more thought.  I haven't been paying attention to the news recently, so I'm not sure how plausible this speculation might be.

 

Sometime in the past couple weeks a NEO (near earth object (asteroid)) passed within [something like] 18km of earth.  This meteor entered the atmosphere not that many ?days? later.  An asteroid in a highly eccentric (non-circular) orbit isn't much different than a comet, except most non-metalic elements and compounds have been exhausted (evaporated, dispersed) by previous passes close to the sun (within roughly 200,000km).

 

Also, any asteroid that isn't [just about] solid metal (nickel-iron), tends to slowly fracture, crack and "smear out" in its orbit due to repeated heating and cooling as the orbit takes the asteroid close to the sun, then far away.

 

My point is, based upon decades of experience, any asteroid that isn't "solid metal" tends to have a sort-of invisible tail like a comet, except much less visible, and much less gaseous (bits and pieces rather than gases).  The obvious inference here is that any large meteor event within days of a close asteroid pass is likely to be one of these fragments that broke off the main asteroid hundreds, thousands, or even millions of years ago.

 

If I had paid more attention to these two events, and checked the orbital paths, I could have made such an inference with more care.  But at least consider this possibility.



#27 Hodgman   Moderators   -  Reputation: 30351

Posted 18 February 2013 - 09:15 PM

The close asteroid flyby (2012 DA14 - 27,700 km) did occur just hours after the Russian meteor, but it's just a coincidence. They had very different orbits (almost the opposite direction).


Edited by Hodgman, 18 February 2013 - 09:29 PM.


#28 laztrezort   Members   -  Reputation: 965

Posted 18 February 2013 - 09:18 PM

So in the videos, when we hear a giant boom, it's not necessarily any kind of explosion at all right? It's likely just the noise of the object moving through the air, which due to it's speed, has been compressed into a sonic boom, which has just reached the observer. Is it this boom that broke the windows, or was there actually a sudden explosion with a powerful shockwave as well?

I was wondering this too, but here is my conjecture:

I suppose it depends on how "explosion" is defined? All a (conventional) explosive does is move matter at very high speed, which creates a shockwave (and heat/light). In the meteor's case, the energy was potential kinetic and spread out over a large area, as opposed to stored chemical energy in a localized area.

Interestingly, in at least one of the videos, you can hear what appears to be aftershocks or smaller explosions after the first large one. I wonder if those were shockwaves generating higher up in the atmosphere, or something else?

#29 Kaze   Members   -  Reputation: 948

Posted 18 February 2013 - 10:29 PM

KE=(M*V^2)/2

 

Objects in space travel very fast due to lack of friction.

 

Any collision with a relative velocity over a kilometer per second will explode due to the raw energy involved.



#30 szecs   Members   -  Reputation: 2139

Posted 18 February 2013 - 10:55 PM

The sonic boom issue is not that simple. Remember, it happened high above where the air is less dense, so the speed of sound is very different.

 

Where did all the energy go? For example in the 400 km long and several km wide cloud (remember, the material was just vaporized, not extinguished). The vaporization of the rock itself. It broke glasses and blew some doors 30 km away (it's a luck that there weren't more cities around). It probably heated the air around it, we can't feel it on the ground.

 

 

But I guess my posts are being ignored on this forum (I thought I gave a pretty good idea that one could do one's own calculations, based on videos, which may be edited (um.... I haven't seen such a fine CGI yet)), posted some very similar looking images of meteors (um,, of course, they can be missiles too)

 

 

So I dunno why the fuck I bother


Edited by szecs, 18 February 2013 - 11:02 PM.


#31 Olof Hedman   Crossbones+   -  Reputation: 2823

Posted 19 February 2013 - 03:10 AM

But I guess my posts are being ignored on this forum

Why do you think you're ignored?
I really liked your pictures, and would've upvoted them if I could.
Everyone but Samoth is agreeing with you, so not much to reply to unfortunately.

#32 slicer4ever   Crossbones+   -  Reputation: 3884

Posted 19 February 2013 - 05:02 AM

But I guess my posts are being ignored on this forum


 

i read your posts, but as Olof said, the only thing to do with that post is to agree, the only person with cause to directly respond/conflict with what you've said is samoth.

 

I really really hate to say this, but i'm sure i'm not the only one to think this. but if this meteorite had actually decimated a city(and thankfully it didn't), it probably would have increased our global awareness toward expanding into space by a hundred fold or so.  as it stands now, it'll be a forgotten event in less than a year=-\.


Edited by slicer4ever, 19 February 2013 - 05:06 AM.

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#33 samoth   Crossbones+   -  Reputation: 4765

Posted 19 February 2013 - 05:23 AM

"If a meteor made out of diamond and 100 feet in diameter was traveling at the speed of light and hit the earth, what would happen to it?"

Wedding rings get cheaper?

#34 Olof Hedman   Crossbones+   -  Reputation: 2823

Posted 19 February 2013 - 06:29 AM


"If a meteor made out of diamond and 100 feet in diameter was traveling at the speed of light and hit the earth, what would happen to it?"

Wedding rings get cheaper?


I guess you're right.
Since there wouldn't be any humans left alive, not much demand for wedding rings.

#35 ddn3   Members   -  Reputation: 1285

Posted 19 February 2013 - 11:02 AM

Given the temperatures involved its quite possible for things to explode. Look at the mythbusters experiments with ice and thermite  The sheer heat from the thermite might be disassociating the ice into hydrogen and oxygen and creates a massive explosion. It isn't the heat of the thermite turning the ice into steam since the effect seem to take alittle time to occur instead of on contact. I'm sure super heated iron mixed with ice inside the meteor provides ripe opportunity for much interesting chemistry and explosive effect. Or maybe it was the sonic shock wave itself which blew apart the meteor once it dropped below the speed of sound..






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