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Meteorite crash in Russia

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Re: Meteorite crash in Russia

#291

Post by nooneelse »

ChuckMcM wrote: post #284
Zancarius wrote: post #276

Earlier quoted context omitted.

I assume there would have also been a detectable gamma burst that Western satellites would've picked up if they're trained on the region.

There was an interesting (if short) conversation on another list about how the US was able to spot small scale nuclear events (even things like a criticality event in a poorly shielded reactor) The speculation revolved around some unidentified sensors that were on the GPS satellite at the San Diego Air & Space museum, since removed (the sensors not the model)) and the way in which GPS satellites could tell you where…

So far the Arms Control Wonk blog hasn't said anything about it.

Re: Meteorite crash in Russia

#292

Post by lobster45 »

mmastrac wrote: post #31

Here's a collection of insane videos of the event, some with the enormous sonic boom: http://www.youtube.com/watch?v=XIAm5hq8WWc http://www.youtube.com/watch?v=b0cRHsApzt8 http://www.youtube.com/watch?v=Np_mpGYSBSA Can anyone translate what they are saying in the first one? You can get a good idea of the new videos being posted using YouTube's "last hour" filter: http://www.youtube.com/results?search_query=%D0%BC%D0%…

He first said it is preperation. Something to prepare for. He is saying take your jackets and lets run. The best is yet to come. When he runs into the group he describes that it was flying overhead. Then he points to the smoke saying it was in the atmosphere. People said that could be war starting. They were not sure of the reason for the explosion. He almost got hit by the broken glass.

Re: Meteorite crash in Russia

#293

Post by InclinedPlane »

Udo wrote: post #173
InclinedPlane wrote: post #172

Earlier quoted context omitted.

Mach 32, that's Earth's escape velocity, which is also how how fast objects tend to fall to Earth.

That's what I mainly meant by "fast", the angle of attack appeared to be relatively steep. I suppose you could be right about the idea that the breakup sound should have been heard before the entry sonic boom, but wouldn't you expect there to be two distinct bangs in that case? I still think the breakup was not that energetic, but it's hard to tell from the footage. It's all just guesswork, but still exciting :)

Turns out it was actually going much faster than escape velocity, at around Mach 59.

Re: Meteorite crash in Russia

#294

Post by InclinedPlane »

Udo wrote: post #173
InclinedPlane wrote: post #172

Earlier quoted context omitted.

Mach 32, that's Earth's escape velocity, which is also how how fast objects tend to fall to Earth.

That's what I mainly meant by "fast", the angle of attack appeared to be relatively steep. I suppose you could be right about the idea that the breakup sound should have been heard before the entry sonic boom, but wouldn't you expect there to be two distinct bangs in that case? I still think the breakup was not that energetic, but it's hard to tell from the footage. It's all just guesswork, but still exciting :)

Turns out it was actually going much faster than escape velocity, at around Mach 59.

Re: Meteorite crash in Russia

#295

Post by narag »

lutorm wrote: post #280
venus wrote: post #111

Earlier quoted context omitted.

I wouldn't think they are contrails. One would expect them to mainly be smoke and dust from the disintegration/combustion/ablation during the descent.

By definition, they aren't "contrails". A "condensation trail" can only happen when something like an internal combustion engine injects water (or another compound that will condense) into the air.

A fast object compress the air in front of it reducing the amount of water that can be solved into it, so the excess of water condenses.

It's very visible in planes about to break the sound barrier. Look for Youtube videos. The cones are spectacular, but also notice how a trail is sometimes visible originating from the tips of the wings.

So you don't need to inject the water, but to extract it from the air compressing it. Anyway, I'd bet the meteor trails consist of vaporized matter from the meteor itself.

Edit: see this one at 0:20:

http://www.youtube.com/watch?v=gw9MjutMhLs

Re: Meteorite crash in Russia

#296

Post by lutorm »

narag wrote: post #295
lutorm wrote: post #280

Earlier quoted context omitted.

By definition, they aren't "contrails". A "condensation trail" can only happen when something like an internal combustion engine injects water (or another compound that will condense) into the air.

A fast object compress the air in front of it reducing the amount of water that can be solved into it, so the excess of water condenses. It's very visible in planes about to break the sound barrier. Look for Youtube videos. The cones are spectacular, but also notice how a trail is sometimes visible originating from the tips of the wings. So you don't need to inject the water, but to extract it from the air compressin…

It's true you can get water condensation features from local pressure minima like in wingtip vortices. However, they are transient, because as soon as the air returns to ambient pressure the condensation goes away.

Re: Meteorite crash in Russia

#297

Post by loppix »

pixl97 wrote: post #253
sheri wrote: post #94

Earlier quoted context omitted.

After the initial boom there seem to be a bunch of secondary smaller pops. Anyone know what those are?

Reflections of the shockwave/sonic boom off of other solid objects. Echos pretty much.

"off of"? what is this, the youtube comment section?

Re: Meteorite crash in Russia

#298

Post by venus »

pixl97 wrote: post #253
sheri wrote: post #94

Earlier quoted context omitted.

After the initial boom there seem to be a bunch of secondary smaller pops. Anyone know what those are?

Reflections of the shockwave/sonic boom off of other solid objects. Echos pretty much.

I was thinking it might be the actual sound of the disintegration. It doesn't sound like echoes to me. And, obviously, it is only just arriving, straight after the shockwave.

Re: Meteorite crash in Russia

#299

Post by venus »

lutorm wrote: post #280
venus wrote: post #111

Earlier quoted context omitted.

I wouldn't think they are contrails. One would expect them to mainly be smoke and dust from the disintegration/combustion/ablation during the descent.

By definition, they aren't "contrails". A "condensation trail" can only happen when something like an internal combustion engine injects water (or another compound that will condense) into the air.

Well. If the meteorite was partially composed of water, which was then vaporised off during the atmospheric ablation, then it might indeed be partially contrail!

A pure water meteorite hitting the atmosphere would be contrails all the way; just not in the way we're used to.

Re: Meteorite crash in Russia

#300

Post by edouard1234567 »

jevinskie wrote: post #207
creamyhorror wrote: post #64

Earlier quoted context omitted.

Here's a great dashcam video that captures the meteor arcing across its field of vision and lighting up the scene more brightly than the sun like a nuclear blast (first submitted to HN by dennisgorelik). I almost thought it was a hoax, and even tried to examine the video for signs that it was CGI. http://www.youtube.com/watch?v=tJOJ6B2XOyA The guy doesn't even say anything for a long while, just starts speeding up. e…

Can anyone explain why I see so many dashcam videos from Russia?

Useful in the event of a meteorite crossing the street.
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