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General Astronomy >> General Observing and Astronomy

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wirenut
scholastic sledgehammer


Reged: 09/21/06

Loc: m'dale Pa
Re: Meteorite hits Russia, people injured new [Re: Mark9473]
      #5683633 - 02/16/13 02:25 PM

Quote:

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.


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drbyyz
sage
**

Reged: 11/04/12

Re: Meteorite hits Russia, people injured new [Re: JayinUT]
      #5683666 - 02/16/13 02:46 PM

Quote:

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.skyandtelescope.com/news/home/Meteorite-Explodes-Over-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.


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GlennLeDrew
Postmaster
*****

Reged: 06/18/08

Loc: Ottawa, Ontario, Canada
Re: Meteorite hits Russia, people injured new [Re: drbyyz]
      #5683727 - 02/16/13 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.


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rdandrea
Carpal Tunnel
*****

Reged: 06/13/10

Loc: Colorado, USA DM59ra
Re: Meteorite hits Russia, people injured new [Re: drbyyz]
      #5683730 - 02/16/13 03:28 PM

Quote:

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/mission_pages/asteroids/news/asteroid20130215.html


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BrooksObs
professor emeritus


Reged: 12/08/12

Re: Meteorite hits Russia, people injured new [Re: GlennLeDrew]
      #5683758 - 02/16/13 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.

BrooksObs

Edited by BrooksObs (02/16/13 03:46 PM)


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rdandrea
Carpal Tunnel
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Reged: 06/13/10

Loc: Colorado, USA DM59ra
Re: Meteorite hits Russia, people injured new [Re: BrooksObs]
      #5683774 - 02/16/13 03:55 PM

Quote:

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.


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Intensity2x
sage


Reged: 09/06/11

Loc: Northern NJ
Re: Meteorite hits Russia, people injured new [Re: rdandrea]
      #5683899 - 02/16/13 05:11 PM

Quote:

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.


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GlennLeDrew
Postmaster
*****

Reged: 06/18/08

Loc: Ottawa, Ontario, Canada
Re: Meteorite hits Russia, people injured new [Re: Intensity2x]
      #5683946 - 02/16/13 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.

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Mike B
Starstruck
*****

Reged: 04/06/05

Loc: shake, rattle, & roll, CA
Re: Meteorite hits Russia, people injured new [Re: GlennLeDrew]
      #5683957 - 02/16/13 05:52 PM



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.


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careysub
Carpal Tunnel
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Reged: 02/18/11

Loc: Rancho Cucamonga, CA
Re: Meteorite hits Russia, people injured new [Re: JayinUT]
      #5684005 - 02/16/13 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.


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Starhunter249
sage


Reged: 06/07/10

Re: Meteorite hits Russia, people injured new [Re: careysub]
      #5684176 - 02/16/13 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.

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careysub
Carpal Tunnel
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Reged: 02/18/11

Loc: Rancho Cucamonga, CA
Re: Meteorite hits Russia, people injured new [Re: Starhunter249]
      #5684558 - 02/17/13 01:45 AM

Quote:

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.


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brentwood
Carpal Tunnel
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Reged: 11/04/05

Loc: BC Canada
Re: Meteorite hits Russia, people injured new [Re: careysub]
      #5685306 - 02/17/13 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.


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GlennLeDrew
Postmaster
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Reged: 06/18/08

Loc: Ottawa, Ontario, Canada
Re: Meteorite hits Russia, people injured new [Re: brentwood]
      #5685363 - 02/17/13 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.)


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WarmWeatherGuy
Carpal Tunnel
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Reged: 08/27/11

Loc: Orlando, FL 28° N, 81° W
Re: Meteorite hits Russia, people injured new [Re: brentwood]
      #5685366 - 02/17/13 02:49 PM

Quote:

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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brentwood
Carpal Tunnel
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Reged: 11/04/05

Loc: BC Canada
Re: Meteorite hits Russia, people injured new [Re: WarmWeatherGuy]
      #5685523 - 02/17/13 04:53 PM

Thank you both, that is a much better answer than I got from CNN! or NASA !

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Saclablue
member


Reged: 11/14/12

Loc: Timmins, Ontario
Re: Meteorite hits Russia, people injured new [Re: brentwood]
      #5685537 - 02/17/13 05:01 PM

Like they didn't see this one coming. Even if there was an asteroid or meteor was going to strike the earth. They would never tell us, think of the civil chaos that would ensue. Societal break down and strickened wide panic. And then after the fact, they have the odacity to address the general public looking like idiots, saying they didn't know it was coming and infer the need for more funding in space exploration. Way to go JPL and NASA.

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GlennLeDrew
Postmaster
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Reged: 06/18/08

Loc: Ottawa, Ontario, Canada
Re: Meteorite hits Russia, people injured new [Re: Saclablue]
      #5685567 - 02/17/13 05:19 PM

Saclablue,
That's a somewhat cynical attitude. Small bodies like this (generally kind of dark) vehicle-sized meteoroid can only be detected when awfully nearby already. And if their approach vector has them coming from the general direction of the Sun, the combination of atmospheric twilight, zodiacal light, solar corona (within a couple or few degrees of the disk) and that we see predominantly the body's night side, the visibility goes down to practically zero until already hitting the atmosphere.


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Michaelo
newbie


Reged: 12/21/12

Re: Meteorite hits Russia, people injured [Re: CharlesW]
      #5686119 - 02/17/13 10:44 PM

I was looking for reports of recent events in order to determine what I saw Feb 17th at approximately 19:00...

While setting up my scope I saw a seriously big fireball...
I was looking westward at the moon using binoculars, and it crossed my field of view (from south to north and appeared to be falling)...

No idea what it was but expect some news report as it was (or appeared to be) seriously big...

If it was a meteor, then is there a storm due?


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rdandrea
Carpal Tunnel
*****

Reged: 06/13/10

Loc: Colorado, USA DM59ra
Re: Meteorite hits Russia, people injured new [Re: Michaelo]
      #5686694 - 02/18/13 09:53 AM

Michaelo, it would help people figure out what you saw if you would give your location.

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