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Meteorite hits Russia, people injured

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#51 Dave Mitsky

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Posted 16 February 2013 - 05:00 AM

500 kilotons equals 0.5 megaton.

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#52 dan777

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Posted 16 February 2013 - 09:00 AM

... what an interesting day. I actually made a record of the day to remember it. Should be one for the history books.

Indeed, this event and the transit of Venus within less than 12 months of each other and then the total solar eclipse passing across the US in 2017.

#53 Special Ed

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Posted 16 February 2013 - 09:39 AM

S&T published this thoughtful and informative article on their website. The first video, which is a compilation, is pretty stunning.

#54 JIMZ7

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Posted 16 February 2013 - 09:50 AM

Just incredible videos! This morning a video from San Francisco showed a bright meteorite burning up in the night sky. What will the heavens bring next. :question:

Jim :dob:

#55 careysub

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Posted 16 February 2013 - 10:43 AM

Wondering if its possible that any of the explosions heard were echos from sound waves bouncing off the top of the atmosphere. Could that happen?


Yes, definitely and in fact almost certainly. Large atmospheric nuclear explosions (and the current ~200 kt estimate of the Chelayinbk blast classifies it as large) often had shock wave "echo" zones in bands hundreds of kilometers from the explosion, far outside the normal limit of effects.

It is more like refraction than reflection though, sound waves being bent in natural wave-guide.

#56 JayinUT

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Posted 16 February 2013 - 11:26 AM

Just curious where your getting 200 kilotons when NASA is reporting 500 kilotons. Do you have a link?

#57 Achernar

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Posted 16 February 2013 - 12:19 PM

Yes, .5 megatons is equal to 500,000 tons of TNT. That is a little more than the destructive power of just one of the eight nuclear warheads aboard a Trident D-5 missile carried by a our Trident submarines. That's enough to level a major city. In other words, a blast of this magnitude near the ground will destroy every building for several miles in every direction unless they are specially constructed military facilities. Even if the actual blast was closer to 200,000 tons of TNT, that still would have been the equivalent of a Tomahawk cruise missile carrying a nuclear warhead against a city. Russia was most fortunate this object exploded at a high altitude and not directly over Chelyabinsk. Fourty people are now in the hospital with serious injuries, and most of the 1,200 injured were cut by flying glass.

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#58 Starhunter249

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Posted 16 February 2013 - 12:43 PM

I was doing the math on how high this object was when it exploded. I calculated the altitude to be approx 20.4 miles above the earth. This is based on a video taken 300km away. The angle approx 5 degrees from the horizon. A sextant used at the location the video was shot would provide a more accurate measurement of angle above horizon. I could be way off on the angle; the angle could be larger which would increase its altitude at final explosion. I also took the curvature of the earth into account at 300km distance which is approx. 4 miles of additional height at horizon. I did not account for the elevation of the city of Chelyabinsk and the city of where the video was taken 300km away which could impact the calculation by a few miles.

What is also interesting is the time from the final flash and the shock wave heard. I have read various accounts from a minute to 3 minutes. Temperature and altitude effect the speed of sound and we are assuming the shock wave is traveling near or at the speed of sound. Colder air temperatures decreases wave velocity. Temperature at ground level was 4 degrees that morning and only gets colder as you ascend altitude until you reach the tropopause. The tropopause is a layer that separates the troposphere and the stratosphere. This is where the air is the coldest in the atmosphere. Above the tropopause is the stratosphere, the air temperature gets warmer as altitude increases, opposite of the troposphere. The air temperature at 20 miles above sea level is about -40 F. Speed of sound is about 0.19 miles per second. At ground level it was 4 degrees above zero which is about 0.20 miles per second. I don’t know what the tropopause temperature is but you can assume its approx -70 F which is 0.184 miles per second. That would slow it down slightly compared to the -40 F at 100000 feet. We can ignore it. Assuming the shock wave is traveling at the speed of sound it would take as long as 107 seconds and as quick as 102 seconds. The true time is in between. As the wave is traveling thru warmer air, it’s speeding up. Air density does have a small slight factor on wave speed by it can be neglected for the purpose of estimates. If the meteor exploded at 10 miles as some experts of suggested, the interval would be half the time I estimated. Eye witness said it occurred several minutes later. If we can get an accurate time between flash and boom. We can get a better idea of the altitude of detonation.

Estimates of the energy released are about 300 kilotons. This is massive amount of energy, 30 times greater than the bomb dropped on Hiroshima. The troposphere which is about 11 miles at mid latitude absorbed much of the impact of the shock waves traveling first thru the stratosphere. If the explosion occurred inside the troposphere, this thing would be devastating to the city below. The Tunguska event, scientists estimate it detonated 3 to 6 miles above the earth and release 10 to 15 megatons of energy devastating 830 square miles of forest (from Wikipedia). Although the event on 2/15/2013 was much smaller in energy compared to Tunguska, the city below would have been severely damaged (not flattened like Tunguska)if the object exploded at 30,000 feet (5 miles) at 300 kilotons. At 10 to 12 miles above surface at 300 kilotons should result in more damage than blown windows and doors. I am not an expert in high altitude explosives but I believe this impact was higher in the atmosphere than preliminary estimates.

#59 hm insulators

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Posted 16 February 2013 - 12:46 PM

I went out to my mother's house yesterday while all this was going on and one of the things that we discussed is that in our frantic, high-tech go-go-go world, we forget that we truly are connected to space. We discussed how so many of the ancient peoples of the world understood that we are part of a vast universe, from the ancient Babylonians, Egyptians and Greeks, the Native Americans (particularly the Mayans), and especially the Pacific Islanders, who were utterly superb navigators, using the stars to steer by and settle such places as Tahiti, Samoa and Hawaii.

#60 JayinUT

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Posted 16 February 2013 - 01:05 PM

Peter Brown of the University of Western Ontario, Canada is giving an estimate of 300 kilotons but stating that can easily double as more data comes in. NASA continues to report it as a 500 kiloton event for now.

One thing I hope everyone remembers is that the NY Times is reporting that of those hospitalized 200 are children. May our thoughts go out to them and their families at this time.

#61 wirenut

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Posted 16 February 2013 - 02:25 PM

No, this meteorite event in Russia is from a stone that traveled north-to-south; the asteroid 2012 DA14 (that you can now follow live at http://www.ustream.tv/nasajpl2 ) is going south-to-north.

I can't use that to rule things out cause I've seen during meteor showers 1 or 2 come 180 degrees from the radiant. I always thought they took the long way around for my viewing pleasure
hypothetical question, if a celestral body passing earth south -north got trapped by gravity but only enough velicity to make it pass the north pole have a impact trajectory in the north - south direction?
I don't think it should be ruled out on that reason alone it needs the math to go with it.

#62 drbyyz

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Posted 16 February 2013 - 02:46 PM

Just curious where your getting 200 kilotons when NASA is reporting 500 kilotons. Do you have a link?


Sky and Telescope reported it as 300 kilotons... http://www.skyandtel...Russia-19137... but also acknowledged NASA's estimate of 500 kilotons. I know that doesn't answer your question but thought I'd throw it out there.

#63 GlennLeDrew

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Posted 16 February 2013 - 03:27 PM

Wirenut,
These objects are traveling far too fast to effectively get 'trapped' in a partial orbit around Earth. They either just miss and fly by, with a *somewhat* altered path, or enter the atmosphere. No arcing around the planet to any significant degree.

#64 rdandrea

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Posted 16 February 2013 - 03:28 PM

Sky and Telescope reported it as 300 kilotons..


That number was from yesterday afternoon's NASA conference call.

They have since revised size, mass, and explosive force upward.

http://www.nasa.gov/...id20130215.html

#65 BrooksObs

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Posted 16 February 2013 - 03:45 PM

Regarding the amount of energy released in yesterday's event, the figures circulating are now so diverse that one can pick any number they wish and be considered OK.

Since early this morning I have seen reported in the news media by supposedly "knowledgeable scientific authorities" that the yield of the blast was "3 times the Hiroshima bomb", "200 kilotons"," 500 kilotons",and "3 megatons". That certainly is quite a range!

Likewise, a CNN science reporter gave the meteroid's dimension as about 10', elsewhere reported as 20', and the latest I've seen being 50'. At the same time the weight has ranged from 10 to 7,000 tons! The implication to me is that science has an awfully long way to go interpreting events of this sort with any meaningful accuracy.

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#66 rdandrea

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Posted 16 February 2013 - 03:55 PM

The implication to me is that science has an awfully long way to go interpreting events of this sort with any meaningful accuracy.


Or maybe the media can't be bothered to report CURRENT numbers.

#67 Intensity2x

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Posted 16 February 2013 - 05:11 PM

Or maybe the media can't be bothered to report CURRENT numbers.


I've seen quite a few news-casts / articles where I had first hand knowledge of the event itself and you would be amazed at how inaccurate most "news" is. And not minor mistakes either. Anything from a "news" source I would discredit entirely and stick to getting facts from places like NASA and the like. That said, there is still quite of wide range of numbers being given out by different agencies.

#68 GlennLeDrew

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Posted 16 February 2013 - 05:45 PM

In last night's (Friday) 11PM CTV national newscast, the coverage stated that first it went dark as the meteor blocked the sun! I kid you not.

#69 Mike B

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Posted 16 February 2013 - 05:52 PM

:foreheadslap:

Yeah, something went dark, alright...

Just recently some friends were discussing clever sayings regarding foolish speach... many famous quotes may not be accurate at all, or be re-hashes of someone ELSE's quote- but many are excellent nonetheless. My personal fave:
The fool is one who, having nothing intelligent to say, provides everyone verbal evidence of the fact."

Case in point: this CTV newscaster.
:tonofbricks:

#70 careysub

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Posted 16 February 2013 - 06:22 PM

They have upped their mass and yield estimate from their first report (from 7,000 tons to 10,000 tons).

But the 500 kT figure is too high if the mass and velocity are correct (10,000 tons, 18 km/sec). This gives a total kinetic energy of "only" 385 kT in the whole body.

The calculation is:
(10^7 kg*(18000 m/sec)^2)/2)*(4.2*10^12 J/kiloton) = 385 kT

Probably less than half of the original energy might be released at once in the main explosion, so really we are still looking at a ~200 kT blast.

#71 Starhunter249

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Posted 16 February 2013 - 08:19 PM

I think its odd that the Russian Scientists and the NASA scientists have numbers way off from each other. I think I'm gonna trust the Russians on the calculations rather than NASA. Russia still sends people into space, we (USA) don't anymore. I guess they did win the space race after all.

#72 careysub

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Posted 17 February 2013 - 01:45 AM

I think its odd that the Russian Scientists and the NASA scientists have numbers way off from each other. I think I'm gonna trust the Russians on the calculations rather than NASA. Russia still sends people into space, we (USA) don't anymore. I guess they did win the space race after all.


What Russian scientist numbers are you referring to? Official estimates of size and yield since Friday are conspicuous by their absence. Roscosmos is reported to reported a 30 km/sec velocity (much faster than NASA's 18 km/sec)- but I can't find any actual citation in English. Russian news is carrying the NASA estimates currently.

This explosion was picked up by a world-wide network of seismographs, and atmosphere shockwave stations set up and monitored internationally to detect nuclear tests. No one in the nuke monitoring community is disputing a 100 kiloton class explosion estimate.

#73 brentwood

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Posted 17 February 2013 - 02:09 PM

There is still something about these events that is still bothering me. It is being said that these two events, the meteorite & asteroid cannot be connected as they came from opposite directions. Could this have happened this way if the meteorite was in orbit around the asteroid?
I can imagine the meteoroid in a highly elliptical orbit striking the Earth in its 'return' trip, ahead of the near miss of the asteroid.

#74 GlennLeDrew

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Posted 17 February 2013 - 02:47 PM

If DA14 had (or could possibly have) a companion in orbit, the orbit would have to be *extremely* small due to DA14's very small mass. By small orbit, I mean hardly larger than the body itself, as its tidal radius would not extend far. And such a situation could not last at all long against the tidal forces of the Sun and (occasionally) other planets.

On top of that, the orbital velocity would measured in perhaps cm/s, which compared to the pair's velocity of km/s is utterly minuscule. Therefore both bodies, either in mutual orbit or after being pulled apart, will have essentially identical space velocity and direction. There is no possibility of one coming at us from a direction different to any significant degree (allowing for the fact of the rotating Earth and location/time at impact introduces an additional velocity vector which must be subtracted.)

#75 WarmWeatherGuy

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Posted 17 February 2013 - 02:49 PM

There is still something about these events that is still bothering me. It is being said that these two events, the meteorite & asteroid cannot be connected as they came from opposite directions. Could this have happened this way if the meteorite was in orbit around the asteroid?
I can imagine the meteoroid in a highly elliptical orbit striking the Earth in its 'return' trip, ahead of the near miss of the asteroid.


To orbit something that is 50 meters across (DA14) would require you to be extremely close to it. If you got very far from it then the pull of the object (DA14) would be so tiny that the pull from other masses (say the Sun or Jupiter) would be much larger and you would leave the orbit.

I calculate that the orbital period around DA14 (using 190,000 metric tons for its mass) would be 15.5 hours if you were only 100 meters away from the center of it. It would be 20.4 days if you were one kilometer away. If you were 384,000 km (the distance from Earth to the Moon) then the period would be 13.3 million years.






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