Author Topic: Meteor Strikes Chelyabinsk, Russia  (Read 140778 times)

Offline ugordan

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #300 on: 02/17/2013 01:42 PM »
The shortest period between the flash and the shock wave in the video is 89 seconds. Based on the height of the explosion is 0.305x89=27.15 km

Can you post a link to that video? The shortest I've seen yet was still over 2 minutes.

Offline JohnFornaro

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #301 on: 02/17/2013 01:47 PM »
perhaps Russian citizens would be wondering why one of the World's most capable space nations allowed a City to be destroyed.

Get a dictionary.

If the Russians knew it was coming, knew where it was going to hit, had in hand the means to destroy it, and did not take action, then you could say they "allowed" the meteor to strike anyhow.

Instead, they didn't know it was coming, didn't know where it would hit, didn't have a means to destroy it, and not too surprisingly, didn't take any action.

No allowances here.  Move along.
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Offline JohnFornaro

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #302 on: 02/17/2013 01:48 PM »
I would also be very interested in eyewitness reports of electrophonic sound PRIOR to the acoustic shock -- that is, during the brightest flaring of the fireball. This is a at-long-last well-established effect of plasma-generated radio noise coupling into near-observer physical objects and creating a hissing or whooshing sound. It occurs simo with the visual flares, seems to come from 'all around' [not from above], has been reported for centuries by some bright fireball witnesses and pooh-poohed by scientists until work by Colin Keay and others established its validity. 

Thanks for the "learn something new every day" comment.  I had not known of this.
Sometimes I just flat out don't get it.

Offline 360-180

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #303 on: 02/17/2013 01:51 PM »
Can you post a link to that video? The shortest I've seen yet was still over 2 minutes.
'Метеорит. Коркино.'
Car DVR recording was made. Recording been mounting. But the gap can be calculated from the timestamp in the bottom left corner. 43:05 flash,  44:34 shock wave.
« Last Edit: 02/17/2013 02:06 PM by 360-180 »

Offline ugordan

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #304 on: 02/17/2013 02:10 PM »
Thanks!

Offline smoliarm

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #305 on: 02/17/2013 02:39 PM »
...
'Метеорит. Коркино.'
Car DVR recording was made. Recording been mounting. But the gap can be calculated from the timestamp in the bottom left corner. 43:05 flash,  44:34 shock wave.

Thanks a lot!! This looks authentic. Moreover, from shades movement it was VERY close to epicenter, the source of light is moving right overhead. And amazingly - the shock effect is quite mild, it was barely able to shake off some show from roofs and no damage at all.
I'll pass this video to my students, we will look more into this.
Thanks.

Offline ChileVerde

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #306 on: 02/17/2013 02:41 PM »
I would also be very interested in eyewitness reports of electrophonic sound PRIOR to the acoustic shock -- that is, during the brightest flaring of the fireball. This is a at-long-last well-established effect of plasma-generated radio noise coupling into near-observer physical objects and creating a hissing or whooshing sound. It occurs simo with the visual flares, seems to come from 'all around' [not from above], has been reported for centuries by some bright fireball witnesses and pooh-poohed by scientists until work by Colin Keay and others established its validity. 

Interesting history of this at http://www.gefsproject.org/electrophones/index_history.html
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Offline 360-180

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #307 on: 02/17/2013 02:53 PM »
And amazingly - the shock effect is quite mild
These roofs do not have windows.  ;)
And besides, there is no reflection of the shock waves from the earth's surface.

In the town Korkino meteorite smashed many windows too
« Last Edit: 02/17/2013 03:15 PM by 360-180 »

Offline ChileVerde

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #308 on: 02/17/2013 02:56 PM »
...
'Метеорит. Коркино.'
Car DVR recording was made. Recording been mounting. But the gap can be calculated from the timestamp in the bottom left corner. 43:05 flash,  44:34 shock wave.

Thanks a lot!! This looks authentic. Moreover, from shades movement it was VERY close to epicenter, the source of light is moving right overhead. And amazingly - the shock effect is quite mild, it was barely able to shake off some show from roofs and no damage at all.
I'll pass this video to my students, we will look more into this.
Thanks.

>  Коркино

That's at 54.90, 61.40, about 30 km south of Chelyabinsk proper.
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Offline JohnFornaro

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #309 on: 02/17/2013 02:58 PM »
Another dash cam.  This one in SF.  Unrelated, exept in time:

Sometimes I just flat out don't get it.

Offline JimO

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #310 on: 02/17/2013 03:01 PM »
I would also be very interested in eyewitness reports of electrophonic sound PRIOR to the acoustic shock -- that is, during the brightest flaring of the fireball. This is a at-long-last well-established effect of plasma-generated radio noise coupling into near-observer physical objects and creating a hissing or whooshing sound. It occurs simo with the visual flares, seems to come from 'all around' [not from above], has been reported for centuries by some bright fireball witnesses and pooh-poohed by scientists until work by Colin Keay and others established its validity. 

Thanks for the "learn something new every day" comment.  I had not known of this.

Happy to take my turn informing -- I'm gratefully on the receiving end as a rule on high-quality threads such as these.

We got a handle on electrophonic sounds in the early 1980s when reentering Orbiters crossed the skies of Texas, and witnesses began reporting HEARING the hissing overflight in real time. 'Like a skier down a slope', one said; 'like a quiet-motor powerboat passing through a choppy lake', said another. I watched many overflights, and heard nothing until the long-after dull THUD. But it seems to really depend on lucky coincidences of specific materials near the observer -- dry pine needles, a tin wall, even frizzy hair, all seem to have worked, but I was out on an open street near empty fields.

Offline Mongo62

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #311 on: 02/17/2013 03:07 PM »
Can you post a link to that video? The shortest I've seen yet was still over 2 minutes.
'Метеорит. Коркино.'
Car DVR recording was made. Recording been mounting. But the gap can be calculated from the timestamp in the bottom left corner. 43:05 flash,  44:34 shock wave.
I was pleased to see this.  I was finding it difficult to reconcile the estimated explosion energy (500 kilotons) and the implied altitude (about 52 km) from a 140s shock wave travel time with the observed damage.  The much lower airburst altitude implied from a 90s travel time (about 29 km) would result in an overpressure about three times greater when it reaches the ground, which is sufficient to do the observed damage.
« Last Edit: 02/17/2013 03:20 PM by Mongo62 »

Offline 360-180

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #312 on: 02/17/2013 03:17 PM »
In the town Korkino meteorite smashed many windows too

Offline smoliarm

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #313 on: 02/17/2013 03:17 PM »
...
What difference would it have made if it was made of iron? Might have not fragmented as easily and hence carried more of its energy downrange...

Exactly.
Also, compared to stone meteorites, irons are much more dense, specific gravity of iron meteorites is 7.9 g/cm3, most stony meteorites have about 3 g/cm3. Therefore, irons tend to carry their energy in larger pieces (or, less fragmentation), they conserve more energy (lower surface/mass ratio -> lower drag), and they bring their energy to lower altitude, where explosion makes much stronger shock wave (due to higher atm. pressure).



Offline Danderman

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #314 on: 02/17/2013 04:04 PM »
I am wondering if the cause of the mysterious rogue waves that appear in the middle of the ocean might be asteroid impacts even further out in the ocean.

Offline smoliarm

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #315 on: 02/17/2013 05:21 PM »
I would also be very interested in eyewitness reports of electrophonic sound PRIOR to the acoustic shock -- that is, during the brightest flaring of the fireball. This is a at-long-last well-established effect of plasma-generated radio noise coupling into near-observer physical objects and creating a hissing or whooshing sound. It occurs simo with the visual flares, seems to come from 'all around' [not from above], has been reported for centuries by some bright fireball witnesses and pooh-poohed by scientists until work by Colin Keay and others established its validity. 

I never herd of this effect, thanks for the reference.
In this case, all the eyewitness reports that I saw have no such thing, most people noted that fireball looked powerful, magnificent, and - amazingly silent. However, we should remember that it was busy morning in a big city, the background noise was significant.

Offline R7

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #316 on: 02/17/2013 05:54 PM »
Many videos seem to show that there was twin contrail from the beginning of reentry. Weird? Are the aerodynamic forces big enough to brake the meteor before contrail begins to form?

Propeller hat idea 1: It did skip elsewhere, broke and two pieces reentered

Propeller hat idea 2: Moon perturbed and broke it in the process.

Propeller hat idea 3: The Bugs have discovered a chain shot.
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Offline sanman

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #317 on: 02/17/2013 06:18 PM »
I, for one, welcome our Klendathu arachnid overlords

Offline Star One

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #318 on: 02/17/2013 06:24 PM »
Quote
The meteorite that caused devastation in the Urals on Friday could have struck Britain if it had entered the atmosphere at only a slightly different time of day, astronomers revealed yesterday.

The region around Chelyabinsk hit by the meteorite impact is 55 degrees north, the same latitude as northern England. Had the meteorite's timing been only few hours different, it could have caused widespread damage in the British Isles, astronomers at the University of Hawaii said yesterday.

http://www.guardian.co.uk/science/2013/feb/16/meteorite-uk

No doubt applicable to other land masses along the same latitude.

Offline ugordan

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #319 on: 02/17/2013 06:31 PM »
Many videos seem to show that there was twin contrail from the beginning of reentry. Weird?

I've been thinking about this as well. Seems implausible to me that it was a binary from the moment it entered atmosphere or that it split into two roughly equal pieces so soon after entry. Also, I don't believe we've ever really seen a big meteor vapor trail like this from almost underneath. A unique vantage point.

I'm wondering if it was convection that split it in two. When you have a spherical mass of hot air (like a nuclear fireball), convective movement and resulting vacuum effects quickly produce a rotating toroidal cloud. Maybe what we see here is is what happens with a  "cylindrical" fireball? It splits into two, like a cross section of a toroidal cloud?

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