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Farrell
15th Feb 2013, 06:47
First video leaves me awestruck IF it is genuine.

Взрыв Челябинск - YouTube

The second video is the newscast which is equally impressive.

Apocalypse Now? Meteorite hits Russia lighting sky, shattering windows - YouTube (http://www.youtube.com//watch?v=36MEsWC1Pzc)

uffington sb
15th Feb 2013, 07:08
Wow!!
Scary stuff, must have been 2012 DA14's little brother.
That would have hurt if it had impacted the ground whole.
Good job those Ivan's like their in car video recorders, some interesting shots and considering it was almost daylight, it was like an atomic flash.

tony draper
15th Feb 2013, 07:32
Just as well the cold war is over or we might have been hearing a few louder bangs here.
:uhoh:

alisoncc
15th Feb 2013, 07:41
Vee are coming for you Monkey people. Your time is nigh. :}

Hokulea
15th Feb 2013, 07:48
I suspect it's genuine. I'm glad I wasn't there.

150 hurt as meteorite hits central Russia | Reuters (http://www.reuters.com/article/2013/02/15/us-russia-meteorite-idUSBRE91E05Z20130215)

PS. Should add there's clearly some nonsense in that report but also think it does support the suggestion a small asteroid did explode while entering the atmosphere above Russia on Friday.

Loose rivets
15th Feb 2013, 07:52
Hard to scale the distance, and the curvature of the lens, but one high horizontal one did seem influenced by gravity.

JCviggen
15th Feb 2013, 07:57
PS. Should add there's clearly some nonsense in that report but also think it does support the suggestion a small asteroid did explode while entering the atmosphere above Russia on Friday.

No kidding, most reports don't seem to be hindered by any knowledge on the subject.

There are even ridiculous reports of missiles blowing it out of the sky.

But it's genuine and the sonic boom really was rather spectacular to say the least. No impact confirmed, probably small fragments will be found soon (suspect many people are booking the first flight out there, these bits are going to be gold)

ORAC
15th Feb 2013, 08:08
42rJJy4Ooso

L9iUaCKr6Mw

Pelikal
15th Feb 2013, 08:13
"I was standing at a bus stop, seeing off my girlfriend," said Andrei, a local resident who did not give his second name. "Then there was a flash.......Giving his girlfriend a good seeing to at the bus stop. Explains it all.

Slasher
15th Feb 2013, 08:33
Just as well the cold war is over or we might have been hearing a
few louder bangs here.

Too right Drapes - in fact both sides were concerned if a natural
event took place like this and mistake it for a preemptive attack.

A tiny asteroid no more than the size of a party balloon impacts
somewhere in the USSR or the US - and Mankind's response is to
promptly destroy itself.

Coincidently I rewatched Bad Universe - Asteroids on the DVD last
night.... :ooh:

Captain Dart
15th Feb 2013, 08:42
Ironically, an asteroid impact is one natural disaster that man has a possibility of forecasting and preventing; given commitment and resources. But we are preoccupied with politics, religious mumbo jumbo and economics.

Maybe that is why we may be alone in the universe, previous civilisations made the same mistakes.

Hokulea
15th Feb 2013, 08:47
JCviggen,
But it's genuine and the sonic boom really was rather spectacular to say the least. No impact confirmed, probably small fragments will be found soon (suspect many people are booking the first flight out there, these bits are going to be gold) Just curious, but am assuming you heard the sonic boom yourself. Were you in Belgium at the time or elsewhere? The videos so far seem to suggest this thing entered the atmosphere at a very shallow angle and if that's the case would have likely been seen or heard in several countries.

Just to be clear, I think that bang in the OP's original video is not a sonic boom, more likely the largest fragment exploding in the atmosphere, but there clearly would have been one in the places this rock passed over. I'm not sure what the other bangs are in the video, could be sonic booms from fragments or something else.

Takan Inchovit
15th Feb 2013, 08:51
Perhaps the Mars Pathfinder has bounced all the way back to earth. :uhoh:

Load Toad
15th Feb 2013, 08:57
Maybe they didn't set the clock. Maybe eh...?

Tankertrashnav
15th Feb 2013, 09:28
Has to be genuine. If it had been made up it would have occurred in the USA, where our experience of watching disaster movies tells us all meteor strikes, alien invasions etc occur!

Why is the dashcam on that lower video reading 31 Dec 2012?


The conspiracy theories start :(

Probably for the same reason the air temperature gauge in my car tells me it's a constant 67 C outside!

El Grifo
15th Feb 2013, 09:39
I knew the name had a certain resonance.

Don't have a lot of luck these guys do they !!!

Chelyabinsk has had a long association (since the 1940s) with top-secret nuclear research, though this is more properly applicable to Chelyabinsk Oblast as a whole, as nuclear facilities such as Chelyabinsk-70 (Snezhinsk) are, or were, located far outside the city. A serious nuclear accident occurred in 1957 at the Mayak nuclear fuel reprocessing plant, 150 km north-west of the city, which caused deaths in Chelyabinsk Oblast but not in the city. The province was closed to all foreigners until 1992 other than a British medical team following a two train rail explosion in the mid 1980s.

Hokulea
15th Feb 2013, 09:43
The conspiracy theories start http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/sowee.gifYou couldn't be more right, Tankertrashnav.

dead_pan
15th Feb 2013, 09:46
Amazing stuff - looks real enough to me. Surely it must be part of the DA14 'system', I mean the timing is more than a coincidence.

Apparently nothing can happen in Russia nowadays without it being captured on someone's dashcam. Maybe we all ought to get them?

Terentiy
15th Feb 2013, 09:55
Now officials report about 500 injured, 3 of them are in a bad condition. Most of them were injured by broken windows glasses. Shock waves broke many windows in about 300 buildings in 6 cities near Chelyabinsk. Schools and kindergartens are closed. So far only 3 places of the impact were found. The rough speed of the object was about 30 km/s.

603DX
15th Feb 2013, 10:04
Seems if a country is as large as Russia, it is going to be subject to more than the average number of "mysterious" falling objects exploding over its territory, like this monster one in 1908:

The Tunguska explosion: an unexpected loud bang and explosion (http://www.philipcoppens.com/tunguska.html)

tony draper
15th Feb 2013, 10:12
I thought they had decided the Tunguska object was a small comet as no bit have ever been found where it fell or rather exploded.
Luckily for us most of the big lumps flying about hit us 3.5 billion years ago.
:uhoh:

OFSO
15th Feb 2013, 10:13
I believe the one photographed thru the car windscreen was from last year. Although Deja Vu has taken up residence in my brain so maybe it's that !

CATIII-NDB
15th Feb 2013, 10:13
The vid showing the object entering the atmosphere at a shallow angle does show what appears to be an explosive event what/ 5-10 secs into the event. I think that one sonic boom was from the explosion and the other was from tr re entry cone pressure front.

It would be interesting to get an idea of the time delay between the pictures and the arrival of the blast front. One report said the "boom" occurred several minutes after the visual effects that suggests an event at somewhere like 20- 30 Miles altitude (The blast propagating at say 12 Statute mikes a min - Yes I know its more complex)

Any better informed ideas. edit: [OFSO may well be correct ?]

It was fascinating to watch, but I regret the casualties from broken glass.

CAT III

tony draper
15th Feb 2013, 10:16
Would the air be dense enough at that height to generate a sonic boom?:)

adsyj
15th Feb 2013, 10:36
Left a bloody Chemtrail as well. Tin Foil Hats on please

Terentiy
15th Feb 2013, 10:36
New reports state that one of the craters was found. Its diameter is about 6 meters. The background radiation near the crater is normal.

El Grifo
15th Feb 2013, 10:42
Reckon if I had a shower like that, I would call the plumber.

Prolly tell me the head was knacked or something :ugh:

Takan Inchovit
15th Feb 2013, 10:44
I guess shower makes it seem gentler? :\


t

Terentiy
15th Feb 2013, 10:44
This picture was made by one of the pilots from the FL near Chelyabinsk.
http://i54.fastpic.ru/big/2013/0215/66/1d6cc8d2b2e95609ad9e4ca3ad9ff066.jpg

New reports say about 725 victims of the shock waves (159 of them are children). 31 of them are hospitalized. Gas supply was interrupted because of automatic disconnection in more than 500 buildings in Chelyabinsk.

CATIII-NDB
15th Feb 2013, 10:46
Yes i think it would - the thing will be traveling at about 20 Kilometres a second and would be a rocky snowball in the order of a few tens of Metres across. - The point of Closest approach of 2012 DA 14 is very approx 16 9: correction 3.5 hours from now - It comes from the south (according to the Guardian) - There's a probability that the asteriod has a cloud of fellow travellers associated with it.

So there's a possibility that we may get more events of this type before & after the closest approach.

CA III (insurance renewal in hand )

CATIII-NDB
15th Feb 2013, 10:51
This been that sort of week.

Now I've got Meteorites in my horse burgers, the Pope's quit, and Obama has had a military hair cut.

Time to get out the REM singles CD and play "Its the ..........

CAT III

Terentiy
15th Feb 2013, 10:54
This picture was made by an airline pilot from the FL near Chelyabinsk.
http://i54.fastpic.ru/big/2013/0215/66/1d6cc8d2b2e95609ad9e4ca3ad9ff066.jpg
Now reports say about 725 victims of the shock waves, some of them are hospitalized. Because of the automatic disconnection system gas supply is interrupted to more than 500 houses in Chelyabinsk.

ChrisJ800
15th Feb 2013, 12:12
Here is a longer video with a loud sonic boom around 30 seconds in!

Zfpol2YP838

Paracab
15th Feb 2013, 12:28
I wonder how close it got to the aircraft from which that picture was taken. Now that really would be unlucky...

sitigeltfel
15th Feb 2013, 12:47
News reports say that many of the injuries were due to people rushing to look out of the windows when they heard the first noises, just in time for the glass to implode in their faces. :ouch:

CATIII-NDB
15th Feb 2013, 13:01
It may be visible with a small telescope from about 17.30 local in the UK traveling south to north - the fig i calculated was from a post in the Guardian - Obviously they failed to specify the time the comment was actually spoken. Silly me.

I was 12 hours out in my calculation.

CAT III

Ronald Reagan
15th Feb 2013, 13:12
Latest update by RT
Meteorite hits Russian Urals: Fireball explosion wreaks havoc, over 900 injured (PHOTOS, VIDEO) — RT (http://rt.com/news/meteorite-crash-urals-chelyabinsk-283/)

Over 950 people injured.

This should be a warning to everyone of what could happen on a far bigger scale one day. Some of the footage on RT is amazing.

El Grifo
15th Feb 2013, 13:40
Here you go CAT111

Event Time Announcer - Asteroid 2012 DA14 flyby LIVE WEBCAST | Bareket observatory, Israel (http://www.timeanddate.com/worldclock/fixedtime.html?msg=Asteroid+2012+DA14+flyby+LIVE+WEBCAST+%7C +Bareket+observatory,+Israel&iso=20130215T20&p1=110&ah=2)

added :-According to unconfirmed reports, the meteorite was intercepted by an air defense unit at the Urzhumka settlement near Chelyabinsk. A missile salvo blew the meteorite to pieces at an altitude of 20 kilometers, local newspaper Znak reported quoting a source in the military.
The regional Emergency Ministry denied that military air defenses were involved in the incident.
Regnum news agency quoted a military source who claimed that the vapor condensation trail of the meteorite speaks to the fact that the meteorite was intercepted by air defenses.

What do we reckon ???

green granite
15th Feb 2013, 13:51
What do we reckon ???

http://i1.ifrm.com/1889/52/emo/PMSL.gif http://i1.ifrm.com/1889/52/emo/PMSL.gif http://i1.ifrm.com/1889/52/emo/PMSL.gif

El Grifo
15th Feb 2013, 13:59
No doubts there then Mr Granite :ok:

hellsbrink
15th Feb 2013, 14:00
This should be a warning to everyone of what WILL happen on a far bigger scale one day.

Fixed it for ya! :ok:

Still plenty big lumps flying around out there that we don't know about, it's a matter of time before there is a big one on a collision course.


Come to think about it, DA14 comes back near us in 2034, don't it? Guess what could happen if a little gravitational "pull" altered it's course a little.......



El G

Hasn't that "report" been debunked in the same manner as some of the "crater" videos on youtube?

hellsbrink
15th Feb 2013, 14:22
Just realised something.

A meteor goes "POP" over Russia on the last day of a G20 meeting in Moscow.

Not a bad sighter...................

lomapaseo
15th Feb 2013, 14:23
Seems like there are two distinct chemtrails. Are they missing a large twin jet?

OFSO
15th Feb 2013, 14:43
Looked up the path for my location on heavensabove.com. From tonight about 2100 I shall be gazing east north east, and hoping to see nothing.

206Fan
15th Feb 2013, 14:50
I like this footage!

iCawTYPtehk

dead_pan
15th Feb 2013, 15:31
Its funny how the Russian drivers seem distinctly unimpressed by what they have witnessed, like they see this sort of thing all of the time.

airship
15th Feb 2013, 15:35
What makes me truly scared is when someone like Drapes wrote what he wrote here earlier: Luckily for us most of the big lumps flying about hit us 3.5 billion years ago. :uhoh: And finally admitting that he also considers himself to be some form of 'dinosaur' within these forums. :ok: Compared to meself, "Uneasy Pleistocene Leftover", having known for a very long-time now that my own existence here is quite miraculous for many reasons.

Whatever, in view of the most recent "asteroid / comet and/or remnant" to have hit the planet (Russia) earlier today, I wonder if this is not a pre-cursor, confirming or at least announcing the forth-coming "peak human activity"?

Looks like far too many other animal / insect / fish / reptilian species etc. are on the wane in 2013, even to the point where many will simply disappear, becoming extinct, as species over the next 1-30 years. Even as all of us 6 billion+ homo-sapiens take increasing possession of the planet and resources.

Ca. 65 million years ago:

T-Rex #1: "Life's so good here! I merely have to growl, and all the newly-born prey on the plains try to hide in the tall-grasses whilst their moms linger nearby. I just have to pick 'em up gently, one at a time and feed them alive to my own brood (OK, alive because the brood are getting older and need to play / hunt).

T-Rex #2: "Look up there mate, what's that bright light up in the sky...?!"

As their brains sizzled within their own skulls almost instantly, and the "bright light" fizzled out to become the most destructive force any being has experienced on this planet ever since. :ok: :sad: :{

TEEEJ
15th Feb 2013, 15:53
lomapaseo wrote

Seems like there are two distinct chemtrails. Are they missing a large twin jet?

Chemtrails?:rolleyes: You mean Contrails! The Meteor broke up resulting in the contrails being formed. You do realise why contrails form and sometimes persist?

Contrail Science (http://contrailscience.com/)

Tankertrashnav
15th Feb 2013, 16:16
TEEEJ - did you miss the irony in lomopaseo's post?

Or am i missing the irony in yours?

JB gets very complicated at times :confused:

The Russian guy in ChrisJ800's video twice says "it was like a meteorite" and explains to the woman that what they are seeing is many kilometers up. Pretty informed on the spot assessment.

HOMER SIMPSONS LOVECHILD
15th Feb 2013, 16:28
Can I be the first pedant to point out that while it's flying through the atmosphere it's a meteor. If you then find a lump of it in your garden , that's a meteorite.

500N
15th Feb 2013, 16:31
Seems it went through the ice in the lake so quickly it didn't cause
any waves, back wash or cracking of the ice ?????

So much so that you can stand right next to the hole ?????

Yet if the meteor had landed on land, it would have formed a hole
and a crater with lips ?


It's all a Gov't fabrication to cover up the loss of a twin jet
laying secret chemtrails.

El Grifo
15th Feb 2013, 16:40
Its funny how the Russian drivers seem distinctly unimpressed by what they have witnessed, like they see this sort of thing all of the time.

In stark contrast to the cuzzins, who are able to find something awesome about a lowly burger :ok:

lomapaseo
15th Feb 2013, 17:09
Can I be the first pedant to point out that while it's flying through the atmosphere it's a meteor. If you then find a lump of it in your garden , that's a meteorite.


actually if you find it in your garden it's $$$

OFSO
15th Feb 2013, 17:57
Luckily for us most of the big lumps flying about hit us 3.5 billion years ago.

Most of them hit Jupiter which acts as a pooper-scooper for objects entering the system.....

ShyTorque
15th Feb 2013, 17:58
Chemtrails? You mean Contrails! The Meteor broke up resulting in the contrails being formed. You do realise why contrails form and sometimes persist?

You do realise this is Jetblast.....

Were you really taking those comments seriously? ;)

TURIN
15th Feb 2013, 18:08
actually if you find it in your garden it's $$$

If you find it in MY garden it's a FIGHT!

Lon More
15th Feb 2013, 18:10
I once had a number of pilots report something similar over the North Sea. Before the days of internet. When it hit one, at least, thought it was a nuclear explosion.

chksix
15th Feb 2013, 18:13
We're lucky that they have cams in their cars (taxis?) otherwise there would be no useful pics of the event.

I hate when people drop the camera or points it at the ground as soon as something interesting happens in the viewfinder. Both sonic boom captures resulted in useless images :ugh:

chksix
15th Feb 2013, 18:16
Feb. 15, 2013

Steve Cole
Headquarters, Washington


Janet Anderson
Marshall Space Flight Center, Huntsville, Ala.


MEDIA ADVISORY: M13-033

NASA EXPERTS DISCUSS RUSSIA METEOR IN MEDIA TELECONFERENCE TODAY

WASHINGTON -- NASA experts will hold a teleconference for news media
at 4 p.m. EST today to discuss a meteor that streaked through the
skies over Russia's Urals region this morning.

Scientists have determined the Russia meteor is not related to
asteroid 2012 DA14 that will pass safely pass Earth today at a
distance of more than 17,000 miles. Early assessments of the Russia
meteor indicate it was about one-third the size of 2012 DA14 and
traveling in a different direction.

Panelists for the teleconference are:
-- Bill Cooke, lead for the Meteoroid Environments Office at NASA's
Marshall Space Flight Center in Huntsville, Ala.
-- Paul Chodas, research scientist in the Near Earth Object Program
Office at NASA's Jet Propulsion Laboratory in Pasadena, Calif.

News media interested in participating should dial 888-843-7186 and
use the passcode METEOR.

The teleconference will be carried live online at:

NASA - NASA News Audio Live Streaming (http://www.nasa.gov/newsaudio)

For detailed information concerning the Earth flyby of 2012 DA14,
visit:

NASA - Asteroid 2012 DA14 ? Earth Flyby Reality Check (http://www.nasa.gov/topics/solarsystem/features/asteroidflyby.html)


-end-

Kulverstukas
15th Feb 2013, 18:26
CsOp5vqHnHM

Kelly Hopper
15th Feb 2013, 18:54
How come DA14 has been known about and tracked for a year now yet this one, just a few hours before, was totally missed?
I go to bed tonight a little more worried than last night.

chksix
15th Feb 2013, 18:56
The meteorite went down like the Name and Shame thread in R&N :D

500N
15th Feb 2013, 19:00
Kelly

It crossed my mind as well.

By the sounds of it they were not small one's either.


Still can't understand how it went through the ice
without causing a wave, splash or broken edge or
even affacting the snow sitting on top of the ice.

Photo in this article.

Russian meteor shower: Sonic boom caused by meteorite hurtling above Chebarkul injures 1,000 people | Mail Online (http://www.dailymail.co.uk/news/article-2279020/Russian-meteor-shower-Sonic-boom-caused-meteorite-hurtling-Chebarkul-injures-1-000-people.html)

El Grifo
15th Feb 2013, 19:00
How come DA14 has been known about and tracked for a year now yet this one, just a few hours before, was totally missed?
I go to bed tonight a little more worried than last night.

Well far be it from me to go into details, it turns out that size actually does matter :{

rgbrock1
15th Feb 2013, 19:01
That makes the three of us, 500N. First thing which crossed my mind: "they" have been going out of their way to reassure us about the DA14 meteor flying harmlessly by and then, poof, one smacks us anyway.

Perhaps someone is pissed off because of the Pope resigning?

No, El Grifo, size does NOT matter. It's not the size of the stick but the magic of the wand.

Asteroid DA14 has flown by us. The closet it got was 17,500 miles above Indonesia.

G-CPTN
15th Feb 2013, 19:07
Still can't understand how it went through the ice without causing a wave, splash or broken edge or even affacting the snow sitting on top of the ice.
Maybe it was hot ?

Very hot . . .

dead_pan
15th Feb 2013, 19:09
Early assessments of the Russia
meteor indicate it was about one-third the size of 2012 DA14 and
traveling in a different direction.

Someone 'avin' a larf up there - there we are all fixated on DA14 then at almost instant one swipes us from behind. 'spose we were lucky it wasn't the other way around.

El Grifo
15th Feb 2013, 19:12
Thanks rg.

Just cut and pasted that and slapped it up on the bookface page of La Grifa.

Phew :D

500N
15th Feb 2013, 19:13
G-CPTN


With the fireball, I could well believe.

The fireball travels in front of the rock as well
as sides and behind.

Plus the air being pushed aside.

Hardly seems to be much damage, that's all.

G-CPTN
15th Feb 2013, 19:35
You wouldn't want to pick up pieces from a meteorite until it had cooled down somewhat.

500N
15th Feb 2013, 19:44
Well generally it takes one hell of a long time to
find pieces and by that time it has cooled down !

Fareastdriver
15th Feb 2013, 20:02
Comparing the size of Meteor Crater in the States with that hole in the ice the remains of the meteorite will be about the size of a lemon pip.

tony draper
15th Feb 2013, 20:20
Most meteors we see as shooting stars are no bigger that a grain of sand ones that produce a bright fireball and plasma trail about the size of a hazel nut tens of thousands of these hit the upper atmosphere every day,most of these burn up about 80 miles up and fall the rest of the way as dust.
They also hit the earth at various speeds some approach from behind in the same direction as the Earths orbit,(slow) and those that come in head on,their velocity plus the earths (fast)
I suspect this one is not as big as peeps think,probably the size of me arm chair when it hit the upper atmosphere if it was a rocky one, probably smaller if it was a iron bugger.
:uhoh:

broadreach
15th Feb 2013, 20:40
500N

Re why it didn't break the surrounding ice, my being far too lazy to find the answer in physics, the mind's eye turns to a bullet hole in a window. Why didn't the entire window shatter, as it probably would if one threw a stone at it?

That hole in the ice does look big. Some six meters in diameter? Have to wonder, if it had hit on land, what the size of the crater would have been. And what terminal velocity was likely.

500N
15th Feb 2013, 20:44
Most bullet holes I've seen in glass - and photos
- show cracking around the edges.

You may be correct, a peanut size meteorite
makes and 8 metre hole.

broadreach
15th Feb 2013, 20:55
51 or 52 years ago I witnessed a meteor land in the Pacific Ocean. We were on a church camping weekend, sitting on a beach south of Lima, Peru, in the late evening, having watched for the "green flash" one sometimes sees when the sun goes below the western horizon.

We didn't see the green flash but the meteor certainly lit up the sky, much like the Russian one. Orange turning to yellow and then white, and then gone, not even enough time to be frightened, just awestruck. It came in almost vertically, or so it appeared. I have no idea how far away, and there wasn't a word about it in the next day's news.

Edit: in response to onecemorealoft's post below, I don't know if the meteor I saw long ago actually reached the surface of the earth. But it was pretty damn big and the fireball did go to all the way to the horizon as we saw it. It could well have been 500km away and disintegrated before hitting the water, but the air was clear, not hazy at all, so it might have been a bit closer. But there was certainly no sonic boom that we heard.

oncemorealoft
15th Feb 2013, 21:41
I may have missed something but other than the hole in the ice pictures is there any other evidence that bits of this meteor actually made it to the ground?

Early reports I heard could have been interpreted as damage and injuries caused were by debris whereas it seems more likely that this was as a result of a shock wave. If it's real, on one of the videos I saw here the sound of the resulting boom was impressive.

Broadreach's comments about witnessing a meteor/meteorite over the Pacific mention an impact into the ocean but no details beyond seeing the meteor in the air.

I've seen a couple of 'fireball' type meteors over the years where a reasonable assumption might have been that there would be an impact but actually with no real reference point it's difficult to assess and in fact there were no reports of an impact otherwise there'd be noticeable holes in Birmingham or Luton - no comments please!

G-CPTN
15th Feb 2013, 21:48
Why did the 'vapour trail' fade out?

Did the meteor escape the Earth's atmosphere, or did it burn up completely?

Hokulea
15th Feb 2013, 22:16
G-CPTN - the meteor broke up/exploded and at that point the smoke trail will end (it is a smoke trail rather than a vapour trail). Any surviving fragments will cool rapidly so won't be visible even if they make it all the way to the ground and at that point they are falling at their terminal velocity of three or four hundred mph, so no additional heating is occurring.

The hole in the ice is interesting. Generally meteorites create a crater 10-20 times their size but am not sure what the relationship is with a fall onto ice, but it suggests that surviving fragment might have been a foot or so in diameter.

broadreach
15th Feb 2013, 22:46
Hi Hokulea,

I can understand the "smoke not vapour trail" part of your post and I can almost grasp the concept of a huge mass of superheated air following behind a basketball-sized piece of rock or metal burning a 20ft diameter hole in the ice. I'm just having some difficulty with the terminal velocity.

Are you saying that whatever remaining bits of the meteor reduced speed from their initial - what was the figure I read - something like 33,000 mph, to one thousandth of that, 300-400mph?

Because if that was really terminal velocity, would the trail of superheated air behind the fragment have dissipated?

It'll be very interesting to see what the divers come up with! And, of course, to hear whether that hole in the ice was the only fragment to survive.

Hokulea
15th Feb 2013, 22:56
Broadreach - yes, they slow dramatically (well, as long as they are relatively small like this one!). Remember the explosion took place probably at an altitude of 50 to 60 thousand feet and by that time they have lost their cosmic speed due to the atmosphere. Whatever is left after the explosion will fall under the influence of gravity.

Actually, I think 10 tons is about the limit for something losing its cosmic velocity in the atmosphere. I've seen one or two reports that give this meteor a mass of 10 tons so it may well have been going a bit faster, but if it broke up the remaining fragments would have lost their velocity very quickly.

As for the trail, this was smoke, i.e., stuff burned off the meteor, so no reason for it to dissipate. On the other hand you often get an ionization trail behind these things and they don't last long at all. So I suspect it's likely this had both but the really obvious one is the smoke trail as that hangs around.

Hokulea
15th Feb 2013, 23:26
So just saw an update from NASA and this rock at a mass of several thousand tons(!) so definitely would have kept much of its cosmic velocity until it exploded, but then the fragments would have slowed very quickly. The height of the blast is estimated at around 30-50 km so the remaining fragments had a long way to fall.

fitliker
16th Feb 2013, 00:22
Maybe it was a weather balloon :}:}

Spacepope
16th Feb 2013, 01:44
"Well generally it takes one hell of a long time to
find pieces and by that time it has cooled down !"

It'll be cool to the touch when you find it. As the material ablates on the hot side, it takes the heat with it. The rest is still supercooled.

500N
16th Feb 2013, 02:25
Space

Thanks, I didn't know that.:ok:

Slasher
16th Feb 2013, 03:42
What would cause this thing to explode if indeed that's what it did?

Unless it contained liquid or gas at its core, it behaved more like what you'd expect from
a comet.

I can't determine if the bang heard was purely sonic pressure (as against a sonic boom)
from an explosion, or just a sonic boom.

Hok?

Hokulea
16th Feb 2013, 04:02
Slasher - it's mainly the pressure difference between the front and back side of the meteor. You're compressing the air in front and decompressing it behind and at some point the difference exceeds the structural strength of the meteor effectively blowing it apart. Obviously as the meteor travels through the denser part of the atmosphere the more likely this is to happen.

I don't know for certain, but do suspect the loud bang you hear in many of the videos is the actual explosion - it was the equivalent of of a few-hundred kT explosion.

Slasher
16th Feb 2013, 04:06
Thanks mate. :)

lomapaseo
16th Feb 2013, 04:08
I would have thought a sonic boom would travel along a wave on the ground and be heard at different times by people along its path. A detonation would radiate out in all directions and everybody should hear it at the same time within 100 miles or something akin to whatever altitude it broke up,

Cacophonix
16th Feb 2013, 04:22
Slash

One of the primary causes of the breakup of a relatively large meteorite will be thermal shock. As somebody here has said already the front of the meteorite will be ablating due to friction and the heating that causes while the back end might still be super cooled (might be because the meteorite may tumble resulting in a different thermal scenario).

Depending on the constitution of the meteorite, the different rates of expansion between the front surface and the back and the relatively slow transfer of heat across the body of the meteorite will cause cracking and then the actual air pressure difference will aid the fragmentation and breakup.

In fact, it appears that the smaller the meteorite the more likely it will be to make the surface of the earth intact for the reasons noted above (including the fact that it will decelerate very quickly and is less likely to face the thermal differential faced by a larger body due to the quick transmission of heat across the smaller body).

1969SSRv...10..230V Page 231 (http://articles.adsabs.harvard.edu//full/1969SSRv...10..230V/0000231.000.html)

In fact this very interesting question is a complex one and the reasons for the breakup depends on the type and structure of the meteorite itself as well (as you implied) amongst many other factors.

http://www.lpi.usra.edu/books/MESSII/9040



Caco

Hokulea
16th Feb 2013, 05:09
Caco - was about to say something about the smaller size of a meteor making it more likely to get to the surface but see you added some more information, and yes, what happens to a meteoroid is complex and depends on many factors. For anyone interested, the following is a fun site but quite educational:

Earth Impact Effects Program (http://impact.ese.ic.ac.uk/ImpactEffects/)

You can enter all sorts of parameters (they suggest values for the more common numbers you might want to use) and tell you the likely effects you'll experience given your distance from the event. No fancy graphics, but very interesting (at least to me!). I just did a quick run there and ended up being buried under several metres of debris and if I somehow managed to survive that would then be facing a thousand foot tsunami. But that was a dinosaur-killer asteroid, not the recent Russian one...

Nemrytter
16th Feb 2013, 05:39
(it is a smoke trail rather than a vapour trail)If we're being pedantic then because the trail is formed primarily from the ablated surface of the meteor then it is a vapor trail. ;)
As for the trail, this was smoke, i.e., stuff burned off the meteor, so no reason for it to dissipate.It dissipates because of the wind blowing the trail around. A lot of the particulate matter also falls towards the Earth although some of the lighter stuff will remain up there for a while.
In this case the trail lasted for about 90 minutes: Meteor vapour trail animation, 15th Feb 2013 | Flickr - Photo Sharing! (http://www.flickr.com/photos/simon_rp/8476482308/)

Windy Militant
16th Feb 2013, 10:02
I seem to recall a few years ago in the USA they used CCTV footage to plot the path of a meteor. By using the time stamps and also the shadow angles they worked out the trajectory and probable impact point fairly accurately.
I presume the Russian Boffinskis are doing something similar to figure out where it came from.

Slasher
16th Feb 2013, 10:30
Thanks Caco - I don't know how the physics would've went if that lump over Russia had've been pure
iron but I'll probably find the answer in that 1940 download. BTW that link needs .pdf bunged on the
end of it.

Yeh I have that same URL Hok. Would you say its reasonably accurate?

MadsDad
16th Feb 2013, 11:40
One thing about the photos of the ice hole. There seemed to be two different holes shown (using the people stood nearby as a scale the hole in the third picture looked quite a lot smaller than the hole shown in the first two. Also the text said the hole was 8 meters but the hole in the third picture looks quite a bit smaller than that (while the first two could well be that size).

SpringHeeledJack
16th Feb 2013, 13:42
It makes you wonder where it might have hit if it had been that bit earlier or later and how many panes of glass might have imploded if a large city had been overflown. I suppose that statistically the planet has more empty spaces than conurbations but all the same.....:uhoh:



SHJ

hellsbrink
16th Feb 2013, 13:57
http://i155.photobucket.com/albums/s287/hellsbrink/21665_611405812222209_891543122_n_zpsab32a89c.jpg

OFSO
16th Feb 2013, 15:12
It makes you wonder......

...whether, were the consumption of vodka in Russia the same as it was 20 years ago, anyone would have noticed..........

NOSTROVIA !

Hokulea
17th Feb 2013, 05:32
Slasher,
Yeh I have that same URL Hok. Would you say its reasonably accurate?I suspect it's about as accurate as we can get given all the parameters and unknowns involved. The guys who created that page are much more expert in the field than I am, so probably not fair to ask me! I am an astronomer but meteors and impacts is not my field of expertise, although have done some solar system asteroid work in the past.

I think what's really interesting is that this recent event shows us that although we do have programmes to find potential earth-impacting asteroids we're never going to find them all unless a lot more money is spent. This particular object was too small and in an unusual orbit (according to NASA) to have been spotted before it entered the atmosphere. If a slightly larger object had been in the same orbit things would be a little different today! I think it's fair to say that at the moment we are either going to know many years in advance of a potential devastating impact or will not know until it happens. Comets are another matter entirely...

cavortingcheetah
17th Feb 2013, 07:44
Once again Britain is in debt to the heroic suffering if the Russian people.
Meteorite 'could have devastated northern UK' | Science | The Observer (http://www.guardian.co.uk/science/2013/feb/16/meteorite-uk)

Lon More
17th Feb 2013, 07:53
That would probably have made Camerloon's day. All those nasty, unthankful Labour voters. ...

Hokulea
17th Feb 2013, 08:00
Please, Cheetah, try and understand that what gets reported in the media is confused and very likely not what the scientists actually said. In this case it's very clear the reporter has no clue.

Edited to add:
The ATLAS project mentioned in that Guardian article wouldn't have detected the Russian meteor even if it was funded and running. It was too small and below the ATLAS project's threshold.

ChrisJ800
17th Feb 2013, 09:08
Why do (mad?) scientists choose corny acronyms that make up a name like in an Austin Powers movie? At least most aviation acronyms dont make up silly words! :yuk:

TEEEJ
17th Feb 2013, 17:49
An oblique view using 0.73 m visible channel images from the Japanese MTSAT-2 satellite (below; click image to play animation) revealed that the stratospheric component of the meteor trail could be seen for as long as 9 hours with the aid of illumination from the sun.

http://cimss.ssec.wisc.edu/goes/blog/wp-content/uploads/2013/02/130215_mtsat_vis_meteor_trail_anim.gif

From

General interpretation CIMSS Satellite Blog (http://cimss.ssec.wisc.edu/goes/blog/archives/category/general-interpretation)

G-CPTN
17th Feb 2013, 21:13
Was that ANCHOR (without the W ) ?

tony draper
17th Feb 2013, 21:30
Apparently we now have a new unit of astronomical measurement, as well as the parsec and light year,we now also have objects the size of a Olympic Swimming Pool ,WTF does that mean? I have not the slightest idea how big or small a Olympic swimming pool is.
:confused:
Feckwits

Lon More
17th Feb 2013, 21:36
1 Olympic Swimming Pool = 4.38 Children's Paddling Pools

as eny fule no

http://farm4.static.flickr.com/3088/2413488617_33f4fce744.jpg

tony draper
17th Feb 2013, 21:50
Why dont they use summat sensible, I mean a swimming pool is bloody flat,How about a unit that the billions of us who have no feckin interest whatsoever in their poxy olympics could mentally picture ie the size of a armchair, the size of a garden shed,the size of a house,the size of a church or the size of a cathedral or really bad news the size of Gibraltar
Another thing, since when did meteors become asteroids? asteroids hail from the asteroid belt betwixt Mars and Jupiter,meteors come from any direction.
:suspect:

G-CPTN
17th Feb 2013, 22:20
How many double-decker buses?

Brian Abraham
17th Feb 2013, 23:18
GobonaStick, well she is a blonde. Did you expect more? ;)

B Fraser
18th Feb 2013, 07:45
How many African elephants is that ?

At least we know how many holes it takes to fill the Albert Hall.

Kulverstukas
18th Feb 2013, 07:47
Do they mean full pool or empty?

Hokulea
18th Feb 2013, 07:48
Tony,
Why dont they use summat sensible, I mean a swimming pool is bloody flat,How about a unit that the billions of us who have no feckin interest whatsoever in their poxy olympics could mentally picture ie the size of a armchair, the size of a garden shed,the size of a house,the size of a church or the size of a cathedral or really bad news the size of Gibraltar
Another thing, since when did meteors become asteroids? asteroids hail from the asteroid belt betwixt Mars and Jupiter,meteors come from any direction.
http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/cwm13.gifIt was roughly the size of a large house, I hope that helps. The thing was also clearly an asteroid before it entered the Earth's atmosphere. It was large enough to be an asteroid and according to reports the recovered fragments are consistent with an ordinary chondrite which is what you'd get from an asteroid entering the atmosphere. It then became a meteor (or bolide, actually more likely a superbolide) and the remaining fragments that hit the ground were meteorites.

Although your definition of an asteroid is incorrect, the asteroid that became the Russian meteor had an orbit that extended beyond Mars but not as far as Jupiter. As you mention, that's where the asteroid belt is.

MarianA
18th Feb 2013, 08:24
For conversions to more sensible units see here:

So, what's the velocity of a sheep in a vacuum? ? The Register (http://www.theregister.co.uk/2007/08/24/vulture_central_standards/)

Kulverstukas
18th Feb 2013, 09:10
Now every part of the world want their ovn metheorit! It's ours! :ugh:

HLpTOc1i8_8

R77bQVAJn0o

The mystery of the Somerset 'meteor': Wildlife photographer catches flaming object streaking through West Country sky | Mail Online (http://www.dailymail.co.uk/news/article-2279992/The-mystery-Somerset-meteor-Wildlife-photographer-catches-flaming-object-streaking-West-Country-sky.html)

B Fraser
18th Feb 2013, 11:42
There were reports of a strangly lit object causing panic in rural Somerset.


It was probably a double decker bus.


:E

vulcanised
18th Feb 2013, 11:56
It was probably a double decker bus.


Nah. There'd be two of them.

hellsbrink
18th Feb 2013, 15:27
Them amateur rocket builders been trying to set fire to Somerset again?

G-CPTN
18th Feb 2013, 15:39
Russian meteor exploded with the force of 30 Hiroshima atomic bombs | Metro News (http://metro.co.uk/2013/02/17/russian-meteor-exploded-with-the-force-of-30-hiroshima-atomic-bombs-3481621/)

tony draper
18th Feb 2013, 15:39
If you look at this from the Meteors point of view it has been happily floating round out there bothering nobody for the last four billion year when WHAM!! a bloody big planet fell on it.
:uhoh:

haughtney1
18th Feb 2013, 15:53
Russian meteor exploded with the force of 30 Hiroshima atomic bombs | Metro News


Lucky it didn't land on Hiroshima then.......:8

B Fraser
18th Feb 2013, 17:44
Come friendly rocks and fall on Slough!
It isn't fit for humans now,
There isn't grass to graze a cow.
Swarm over, Death!

Come, asteroids and blow to smithereens
Those air -conditioned, bright canteens,
Tinned fruit, tinned meat, tinned milk, tinned beans,
Tinned minds, tinned breath.

Mess up the mess they call a town-
A house for ninety-seven down
And once a week a half a crown
For twenty years.

And get that man with double chin
Who'll always cheat and always win
Who washes his repulsive skin
In women's tears:

And smash his desk of polished oak
And smash his hands so used to stroke
And stop his boring dirty joke
And make him yell.

But spare the bald young clerks who add
The profits of the stinking cad;
It's not their fault that they are mad,
They've tasted Hell.

It's not their fault they do not know
The birdsong from the radio,
It's not their fault they often go
To Maidenhead

And talk of sport and makes of cars
In various bogus-Tudor bars
And daren't look up and see the stars
But belch instead.

In labour-saving homes, with care
Their wives frizz out peroxide hair
And dry it in synthetic air
And paint their nails.

Come, friendly rocks and fall on Slough
To get it ready for the plough.
The cabbages are coming now;
The earth exhales.

broadreach
18th Feb 2013, 21:58
B Fraser I was just so hoping it was you ... but no, Betjeman.

Anyway, wanted to get back to the chondrite > asteroid > meteor > bolide> superbolide > meteorite sequence Hokulea's referred to, what the original size was (large house, full/empty double decker bus or was that a swimming pool etc), what size the fragments that scattered were or could have been.

Some Russian authority has said the 6m diameter hole in the ice has nothing to do with the meteorite. And divers haven't found a thing. Yet.

One has read about impact speeds of 300-400 knots up to several times supersonic. About a meteorite with a basketball's diameter and possibly one of 15m diameter. And that if it had exploded only xxkm (enter a number) lower over a large population city it would have caused xxxm casualties.

The mis/dis-information is pretty astounding, rather reminiscent of threads on the top Pprune channel when there's an aircraft accident.

Cacophonix
19th Feb 2013, 01:30
30 atom bombs...

What an utterly stupid headline. What about two 15 megaton bombs, morons?

Bring back the Tsar Bomba...


The largest nuclear weapon ever: Tsar Bomba 50 megatons of TNT. [VIDEO] (http://www.wimp.com/tsarbomba/)

Caco

Hokulea
19th Feb 2013, 05:42
Broadreach - I hope you aren't implying I've been posting misinformation. some of the numbers have changed over time as measurements are analysed, but essentially the latest is this:

A lump of rock, approximately 17 metres in diameter and mass 10,000 tons entered the atmosphere with a speed of about 40,000 mph. It broke apart/exploded at altitude although I think the actual altitude is still uncertain, but it would have been several miles. The explosion was measured to be the equivalent of 500 kilotons of TNT. It's almost certain there were fragments that survived the explosion and reached the ground, but they would have been slowed down significantly by the atmosphere and likely reached the ground with a speed of a few hundred mph as most meteorites do. What small fragments have been found so far, according to some Russian reports, were found on the surface of a frozen lake, so clearly weren't traveling that quickly when they hit the ground.

I hope that's clear enough and remember, the numbers are likely to change somewhat over time after the measurements that are available have been analyzed further.

Hokulea
19th Feb 2013, 06:22
Caco - I think your calculations are off a little. If the explosion had been the equivalent of two 15-megaton bombs I doubt we'd have so many dash cam videos of the event to watch.

B Fraser
19th Feb 2013, 06:53
B Fraser I was just so hoping it was you ... but no, Betjeman.

I'm sorry to disappoint you Broadreach, I banked on 99% of the readership not only recognising it but able to recite the opening verse from memory. I guess sales of Private Eye don't extend to Sau Paulo. Perhaps Frau Kirchener has issued a writ.

Anyhow, for the sake of international relations I shall give more thought to the subject and pop back later. In the meantime, keep sending the Malbec and the steak.

green granite
19th Feb 2013, 07:25
NASA - Russia Meteor Not Linked to Asteroid Flyby (http://www.nasa.gov/mission_pages/asteroids/news/asteroid20130215.html)

"The estimated size of the object, prior to entering Earth's atmosphere, has been revised upward from 49 feet (15 meters) to 55 feet (17 meters), and its estimated mass has increased from 7,000 to 10,000 tons. Also, the estimate for energy released during the event has increased by 30 kilotons to nearly 500 kilotons of energy released"

Lots more in the article.

tony draper
19th Feb 2013, 08:31
So 500 kilotons sky bursting above a town only broke a few window?,buggah! what have we been worried about nuclear war for all these years..:rolleyes:

B Fraser
19th Feb 2013, 08:38
Here's one for you Broadreach

Come, friendly rocks, and fall on Slough!
It isn't fit for humans now,
There isn't grass to graze a cow.
Armageddon , we hail !

With comets this town should be hosed
There used to be three but they closed
In a final hurrah was their stock disposed,
Liquidation sale.

Flatten this mess with a rock from space
A boil on the arse of the human race
And with a third runway, rebuild and replace
What went before

Come icy balls of rock and dust
Improve this part of the earths crust
Wipe out Bracknell as needs must
Just along the M4

El Grifo
19th Feb 2013, 09:17
Could be mistaken but I think perhaps Caco is ridiculing the possibility.

What an utterly stupid headline. What about two 15 megaton bombs, morons?

Hokulea
19th Feb 2013, 09:40
Possibly, EG, but personally I think 30 Hiroshima bombs is a good indication of the size of the blast whereas two 15-megaton bombs isn't. Hopefully Caco will explain.

Edited for spelling.

broadreach
19th Feb 2013, 09:54
Hokulea, not at all! Your posts have been most informative and reliable! I was poking fun - or so I thought - at all the panicky, contradictory stuff coming in. I apologise if it seemed to be aimed at you! Didn't one Russian authority even say the meteorite had nothing to do with the hole in the ice?

broadreach
19th Feb 2013, 10:04
B Fraser :ok:
Private Eye's available on the internet but Pprune's much more entertaining.
I think most of my friends south of the border would be happy to guarantee you a lifetime supply of Malbec and bife de chorizo - if you'll take Mrs Kirchner as well.

B Fraser
19th Feb 2013, 11:03
Oh bugger, I got my geography in a muddle. Apologies Broadreach for mixing you up with your southern neighbours.

errr ummmmmm ............ keep sending the volleyball teams and the coffee !

:O

airship
19th Feb 2013, 16:20
I always thought that JB was the best place for info.

And it still is, in view of my own contribution today. NASA reports (http://www.nasa.gov/mission_pages/asteroids/news/asteroid20130215.html) that: The estimated size of the object, prior to entering Earth's atmosphere, has been revised upward from 49 feet (15 meters) to 55 feet (17 meters), and its estimated mass has increased from 7,000 to 10,000 tons. Also, the estimate for energy released during the event has increased by 30 kilotons to nearly 500 kilotons of energy released. These new estimates were generated using new data that had been collected by five additional infrasound stations located around the world the first recording of the event being in Alaska, over 6,500 kilometers away from Chelyabinsk. The infrasound data indicates that the event, from atmospheric entry to the meteor's airborne disintegration took 32.5 seconds. The calculations using the infrasound data were performed by Peter Brown at the University of Western Ontario, Canada.

I guess most JBers were otherwise enamoured/satisfied by their own conclusions of a "double-decker London bus-sized meteor" as the source... :p :uhoh:

tony draper
19th Feb 2013, 16:34
Thirty two seconds? seems a long time for summat traveling at that clip to get through the atmosphere even if it was slowing down,must have been at a very shallow angle.
:uhoh:

Hokulea
20th Feb 2013, 04:28
Broadreach - thanks for the clarification, much appreciated! I agree that much of the stuff in the media has been confusing. Just today I read about one Russian politician who is blaming this event on a secret American weapon and came across another site that apparently shows the meteor being shot down by a missile from a UFO.

Hokulea
20th Feb 2013, 04:34
Tony - ESA are estimating the angle at about 20 degrees, so yes, very shallow.

Slasher
20th Feb 2013, 05:23
If you look at this from the Meteors point of view it has been happily floating
round out there bothering nobody for the last four billion year when WHAM!!
a bloody big planet fell on it.

Not quite Drapes but that made me laugh! Sir Jupe and Lady Saturn must've had the
day off from their vacuuming chores.

Hok is there a critical angle at which a meteor would just bounce off the atmosphere?
Admittedly its entry would be far greater than 36,000fps, which I understand was the
base datum used by NASA for determining the reentry angle for CM descents (or vv).

Hokulea
20th Feb 2013, 05:49
Slasher - yes, there is, but pretty certain it would also depend on the velocity (and perhaps even the mass and composition) and I don't know what the relationship is. I know there are one or two videos around of exactly what you mention, a large rock grazing the atmosphere and bouncing back into space. In one case I remember I think a video was taken at a football or baseball game in the US (Seattle?) and the thing left a trail for several hundred miles, maybe even longer. It was a few years ago though so my memory of the event isn't so good. I'll have a dig around when I get the chance.

broadreach
20th Feb 2013, 06:32
Hokulea,
Am I right in thinking that the shallow angle of approach was fortunate? I.e. that those 32 seconds bled off lots of energy and speed, and that a much steeper angle would have resulted in rather more damage?

Hokulea
20th Feb 2013, 07:00
Broadreach - I think something of this size and composition (stony) would still have broken up before it hit the ground even if it came in vertically. I mentioned this site earlier in the thread:

Earth Impact Effects Program (http://impact.ese.ic.ac.uk/ImpactEffects/)

but suspect it might be updated in the future because I can't get that site to give the same answer as to what actually happened. The main difference seems to be the altitude at which the object broke up and hence the sound that would have been heard on the ground. So far the site says it would have broken up much higher than it seems to with a sound on the ground like loud traffic which clearly wasn't the case! On the other hand it's consistent that no matter what angle the meteor had, it would have broken up and I think that's probably realistic.

I'm not surprised about the disparity. It's not as if this thing happens every day, so there's a lot of theory involved but not many measurements to base revisions on. I suspect the shallow angle of the meteor really screws things up as well. Even stuff like the actual shape of the asteroid before it entered the atmosphere must make a difference I would have thought (it almost certainly wasn't spherical - it was too small for that).

If you can get past the detailed physics then the paper written by that site's creators is interesting:

http://impact.ese.ic.ac.uk/ImpactEffects/effects.pdf

but just beware it isn't written for the layperson! Slasher - I read this paper some years ago and just skimmed it now. I don't think they take into account the possibility of a rock bouncing off the atmosphere in that paper in case you thought of asking!

broadreach
20th Feb 2013, 07:03
B Fraser

I'm trying hard to focuss on meteorites and here you keep skidding off topic, shame on you for distracting me with Private Eye, steaks and, now, volleyball teams. Mmm, you wouldn't be thinking of the LADIES' volleyball teams now would you? If so I know what you mean.

Moons ago when I lived in Santos, had two sons visiting from uni in UK; returned home to flat after tennis, all of us sweaty, took the service lift from the garage floor. In it already were two sweaty young members of the Brazilian junior VB team, which had rented flats in the building for a few weeks during training. My sons are 6'3"and 6'5", and I'm 6'4". After the initial shock of looking UP at them, we all burst out laughing.

broadreach
20th Feb 2013, 07:11
Thanks Hokulea,

Yes I tried the Earth Impact site you mentioned a few days ago with pretty inconclusive results.

I'm very firmly in the lay category. Steep or shallow angle, the bottom line is one would probably prefer to witness such events via webcam clips uploaded to YouTube rather than personally!

Hokulea
20th Feb 2013, 07:40
Too right. That explosion and noise would have scared the cr*p out of me if I'd been there. Remember, those people in Chelyabinsk would have seen the explosion and smoke trail a minute or so before the sound, so would have been pretty worked up already only to have all their windows and eardrums knocked out a little later.

broadreach
21st Feb 2013, 00:04
Something to mention to the grandchildren when they're not engrossed in TV or games. "Don't rush to the window if there's a sudden brightening of the sky, wait a few minutes". So many of the Russian injuries were caused by windows exploding in their faces.

On the bright side, if there is one, I saw a clip of a pre-teen girl out hunting in the snow for the fallen "new gold". She'd found one, a little smoothed chip. I can envision hundreds of children out searching for little pockmarks before the next snowfall. Have to wish them luck and good fortune for their families.

500N
21st Feb 2013, 00:08
Shades of WWII when the kids used to
search the streets for bomb fragments
and shells.

B Fraser
21st Feb 2013, 07:41
you wouldn't be thinking of the LADIES' volleyball teams now would you?

Is there a team other than the ladies volleyball team ? I know that in the film "Top Gun", there was a volleyball scene. Given that the film was all about when the Village People joined the Air Force, you can understand that sort of thing.

Crikey, talk about thread drift. Perhaps El Slasho will be along in a minute with a sporty photo of a heavenly body so we all get back on track.

Hokulea
21st Feb 2013, 08:05
http://images.fineartamerica.com/images-medium-large/heavenly-body-crispin-delgado.jpg

Windy Militant
21st Feb 2013, 10:33
Strange how things jog your memory, ahem.
Right back to the thread, Slashers question about bouncers, er I mean Earth Grazing Meteors reminded me of the Grand Teton Meteor. This was held up by the UFO fraternity as photographic evidence of an extraterrestrial object entering the atmosphere. Well they were right about the ET bit shame about the lack of little green men on board.
http://www.youtube.com/watch?v=KcsJ6e8S5lA
The Great Daylight 1972 Fireball (or US19720810) was an Earth-grazing meteoroid which passed within 57 kilometres (35.4 miles) of the surface of the Earth at 20:29 UTC on August 10, 1972

Slasher
21st Feb 2013, 10:59
I don't think they take into account the possibility of a rock bouncing off the atmosphere in that paper in
case you thought of asking!

I took a look at Fig 1 Hok and thought of playing around with Theta, but subsequent equations ignore the
curvature of the Earth and I toyed with equations 6 through 8 but no joy. As well as curvature, one would
also need more density data than the simple exponential provided.

tony draper
21st Feb 2013, 11:31
I remember the one that did the fly by in the seventies,I used to get Sky and Telescope sent over from our American Colonies and it had articles about it.
One was a keen amateur astronomater then.
:)

B Fraser
21st Feb 2013, 15:10
Same here Admiral. I saw Mercury just before sunrise a few months ago. It set me up for the whole day :ok:

tony draper
21st Feb 2013, 16:31
Only ever seen Mercury once meself,was heading down the road around sunrise one morning and and there was a extra spark in the sky that should not have been there,buggah me! one thunk that must be Mercury,never really sought it out telescopically,not a lot to see on the inferiors cept phases.
:)

OFSO
21st Feb 2013, 17:20
is there a critical angle at which a meteor would just bounce off the atmosphere?


The top of the atmosphere isn't smooth, it's pretty ragged, with bits sticking up and valleys sticking down. Hence it's difficult to predict exactly what's going to happen when solid rock meets vapourous air - as I know from being on duty through several re-entries.

Slight drift: very exciting watching spacecraft telemetry during re-entry. Most of the sensors are OOL long before the on-board encoding and transmission path packs it in.

Slighter drift: and when you were on duty during the same spacecraft launch many years before, re-entry is akin to a funeral. Or perhaps a cremation, anyway it's a time of farewell to an old friend.

broadreach
21st Feb 2013, 23:18
Hokulea,

Your contribution of a "heavenly body" errr... rocks!

B Fraser

I'd forgotten all about that volleyball scene in Top Gun! Lest you get the wrong impression, I wish to confirm that the sweaty volleyball players taller than us in the lift were the LADIES' junior team. It's a rare event that tall guys look up to taller ladies; we're never prepared for it and they know it. That's why we all burst our laughing.

broadreach
21st Feb 2013, 23:21
Drapes, get yourself an iPad and download one of the several "Sky at Night" apps. Magic.

Hokulea
22nd Feb 2013, 06:12
Windy - thanks for the video of the Earth grazer. That's probably the event I was thinking of but thought there was a video of something similar but it was at night. I can't find it though, so probably misremembering. It was a while ago.

The great daylight fireball of 1972 made it to NASA's Astronomy Picture of the Day in 2009 - APOD: 2009 March 2 - Earthgrazer: The Great Daylight Fireball of 1972 (http://apod.nasa.gov/apod/ap090302.html)

http://apod.nasa.gov/apod/image/0903/earthgrazer_ansmet.jpg

OFSO - I can certainly understand where you're coming from. Although I've never been part of a team overlooking launches or re-entries I do remember the emotions shown by several colleagues and friends of mine when ROSAT (http://en.wikipedia.org/wiki/ROSAT) re-entered the atmosphere a year or so ago. When I was a student I worked with many people who used the initial data from that observatory and have remained friends with them ever since. It's strange how an inanimate object can actually invoke emotions in people (even scientists!) but it definitely happens.

B Fraser
22nd Feb 2013, 07:48
I know from being on duty through several re-entries.

Oh happy days.

Broadreach. If you had to look up at the ladies beach volleyball team then as a gentleman, I recommend that you avoid eye contact and look straight ahead next time. Try and find a point to focus on. If you can't find one then adjust the air conditioning.

:E