Talk:Chelyabinsk meteor/Archive 1

Archive 1

Archive 2

Archive 3

Archive 4

Captured footage?

I feel as though some videos of captured footage should be noted as well, especially noting that a large number of people started recording the smoke trail of the meteorite which then captured the loud sonic boom that followed after. Here are a list of videos known so far: http://pastebin.com/HCxx2Q9S — Preceding unsigned comment added by 92.5.14.184 (talk) 09:33, 15 February 2013 (UTC)

Much of the footage was captured by wide angled dashboard cameras. As this article from Popular Science notes, one of the most remarkable things around this event is the sheer amount of video captured:http://www.popsci.com/science/article/2013-02/videos-space-rock-exploded-over-russia-slammed-buildingCheerioswithmilk (talk) 15:24, 15 February 2013 (UTC)

The number of videos is reportedly due to the high prevalence of dashboard cameras in the cars in Russia. That in itself is worth a mention here, probably with a link to a separate article. The cause is apparently mostly related to insurance requirements in Russia, with secondary causes related to police corruption and random violence. However, the result is that almost any weird event in Russia is quite likely to get captured on camera as long as it occurs near cars. Shanen (talk) 08:57, 17 February 2013 (UTC)

Seen some genuine informed debate whether the "explosion" sound heard was the meteor exploding or sonic boom. "explosion" aound quite clear on this one: http://www.youtube.com/watch?feature=player_embedded&v=b7mLUIDGqmw#! Also YT compilation of videos here: http://www.youtube.com/watch?v=Z_OYxWDUaI8&list=PLMJ4n80nrQwqUuDwUVMFHRBRdFSVEH86D — Preceding unsigned comment added by 92.29.228.245 (talk) 15:43, 15 February 2013 (UTC)

a good blog summary of the event by an astronomer (Phil Plait) with video: http://www.slate.com/blogs/bad_astronomy/2013/02/15/breaking_huge_meteor_explodes_over_russia.html

More footage compiled here: http://idealab.talkingpointsmemo.com/2013/02/russia-meteorite-video-footage.php

The video below has particularly clear audio - can hear multiple smaller explosion sounds after the big one. Does Sonic Boom do that? http://www.youtube.com/watch?feature=player_embedded&v=MKx97csfPy0#! — Preceding unsigned comment added by 92.29.228.245 (talk) 15:53, 15 February 2013 (UTC)

54,000 km/h (supersonic speed), the object exploded in many fragments. Probably it's the sound of its desintegration. --Chris.urs-o (talk) 16:02, 15 February 2013 (UTC)

The BIG first boom that you hear, and possibly 1 or 2 others about 1/2 second apart too close to distinguish, will be the initial shock wave/sonic boom combination from the meteor slamming into the atmosphere. This would have been the first sound to arrive. Within mere seconds of this, the reentry stress would have ripped the rock into several pieces, vaporizing most. So the other littler booms are combinations of sonic booms from the remaining pieces, now dozens of miles from initial contact (notice how the smaller ones sound like coming from a different direction :) ), & the actual disintegration noises from the rocks breaking apart. This latter noise has much less intensity than a sonic boom, which can stay together for hundreds of miles, so they could have well been completely canceled & torn apart by the booms, leaving only the sonic imprints from all larger pieces left to hear. In that scenario, which we'll never be 100% sure about, this would have been a completely silent event if not for the sonic booms & the arrival of the overpressure wave upon their eardrums. This happened at Mt. St. Helens, when the intensity of the explosion literally blew the sound waves up & apart. To most survivors in the area, it was completely silent until the actual overpressure arrived & caused noise from blowing things around. Take it or leave it, but I've studied this stuff for 3 decades. I'm right. — Preceding unsigned comment added by 98.159.69.146 (talk) 21:01, 15 February 2013 (UTC)

Fascinating animated gif here of meteor entry and trail: http://i.imgur.com/SnVvLv8.gif via http://www.slate.com/blogs/bad_astronomy.html — Preceding unsigned comment added by 92.25.221.105 (talk) 23:49, 15 February 2013 (UTC)

It would great if we could get one of these user-made videos as free media at commons, particularly with the sonic boom involved. --MASEM (t) 00:14, 16 February 2013 (UTC)

Putin parody

Vladimir Putin was depicted as riding the meteor in a parody of his "feats of strength" in a manor reminiscent of Major T. J. "King" Kong from the Kubrik film, Dr. Strangelove. --Walter.bender (talk) 03:04, 17 February 2013 (UTC)

References

Supersonic speed

The dutch wikipedia is reporting the damage is because of a supersonic boom. [1] — Preceding unsigned comment added by 82.95.250.30 (talk) 10:13, 15 February 2013 (UTC)

Some reports say the boom, some reports say a single event when it blew up. Guess one will over a wider area than the other? - SimonLyall (talk) 10:17, 15 February 2013 (UTC)

Until the science is not in, we can mention both as possible. I'm sure that the speed can be determined from the images and videos. We will have the numbers soon :). --Tobias1984 (talk) 10:21, 15 February 2013 (UTC)

Yes, sonic booms (such as lightning) and meteor air bursts cause shock waves. BatteryIncluded (talk) 18:53, 15 February 2013 (UTC)

How many Near Earth Objects have caused injuries?

Tunguska and the meteorite that injured a woman in the 50s? Sagittarian Milky Way (talk) 10:41, 15 February 2013 (UTC)

Our article doesn't mention any injuries at Tunguska, making this only the second known space object to cause injures to humans in recorded history - and by orders of magnitude. We seem to have gone from one person directly hit by a meteor to over a thousand hurt. But I haven't seen any news sources commenting on this aspect yet. Rmhermen (talk) 18:26, 15 February 2013 (UTC)

I also thought there was only one person in history (1954) that was directly struck by a meteorite -but it turns out that is only one American person struck. There have been many deaths before. Please take a look at this injury/fatality list: Reported Deaths and Injuries from Meteorite Impact. Chees, BatteryIncluded (talk) 18:58, 15 February 2013 (UTC)

There is a recorded episode in the very distant past of China's history of a meteor shower which purportedly killed and injured many thousands. I have never seen confirmation of that event, but its something possibly worth mentioning as being unconfirmed, if a new subsection is added on previous injuries. Best: HarryZilber (talk) 20:19, 15 February 2013 (UTC)

At least one of the items on that much copied list is a known hoax: [2] Rmhermen (talk) 21:48, 15 February 2013 (UTC)

As far as I know, there has been only one person hit by a meteorite -- Mrs. Hewlet Hodges of Alabama -- it broke her arm. It is also called the sylacauga Metorite -- here is teh wiki link http://en.wikipedia.org/wiki/Sylacauga_(meteorite). I have written a book and in one of the chapters I cover meteorites and the problems casualties. I have never heard of people being hit in China. The Tunguscak event did hurt and kill people but it was from the explosion as the meteorite burst if memory serves. There have been many meteorites to strike earth in the past. The best known is the one that struck at the end of the Cretaceous 65 mya and killed off the dinosaurs.Volcanoman7 (talk) 06:03, 16 February 2013 (UTC)

Long ago and perhaps even recently, most people who witnessed such a meteoric event probably had no idea what was really happening. Decisions made in panic can also cause injury and death. In this particular case, the meteor seems to have exploded in one giant fireball, over land, on a very clear day. But sometimes a meteor breaks apart upon entering the atmosphere and then there are multiple explosions, as in Pultusk, Poland, January 1868. Imagine that you observe a succession of vapor trails and resounding atmospheric explosions through a fog from aboard a 19th Century sailing vessel that happens to be carrying explosive cargo. What would you guess might be happening? What would you do about it? Though this is entirely speculative and original, I suggest that debris from Biela's Comet may be the actual solution to the as-yet-unsolved Mystery of the the Mary Celeste. Jonathan Lane Studeman (talk) 11:40, 16 February 2013 (UTC)

Height

In the reference it states 32,800 ft, not 33K. It we use references, we should stick to the info in it. Kennvido (talk) 10:52, 15 February 2013 (UTC)

As discussed. The yahoo story references an older reuters story (also on the yahoo site) which has 10,000 metres first. I've updated the ref. In any case the ref says "about 10,000 metres" with a conversion to feet. Especially since we have "about" at the front I think we should go with "about 10,000 metres" and have a feet conversion like the template provides (assuming the current MOS is to provide conversions). Considering how inaccurate the estimate is likely to be having it to 3 digits in feet is overkill - SimonLyall (talk) 11:19, 15 February 2013 (UTC)

"about 10,000 metres"Kennvido (talk) 11:27, 15 February 2013 (UTC)

Intercepted by air defense

This report is indicating it was taken out by air defense but an official source in English is needed before we add it to the article. - Shiftchange (talk) 11:19, 15 February 2013 (UTC)

According to German news this is only a story made up by one Russian newspaper to get more readers. --Christian140 (talk) 11:41, 15 February 2013 (UTC)

Yeah, I'd wait till at least two good sources report it and not even put in a rumor. Kennvido (talk) 11:49, 15 February 2013 (UTC)

There's no way "air defense" intercepted a meteor. Like all stoney meteors of about this size, the heat of re-entry destabilize, and eventually cause them to explode before they impact the earth. We don't have the technology to detect meteors coming in from space unless they are relatively massive. Any "space defense" system is just pie-in-the-sky now. HammerFilmFan (talk) 13:44, 15 February 2013 (UTC)

Oops, I should have read this before editing. I removed what I had added earlier relating to this.Cheerioswithmilk (talk) 15:11, 15 February 2013 (UTC)

The Atlantic Wire explains that Russia Today posted an update to their original story in which they state that "Russia's defense ministry took no action connected to the incident." (see Russian Meteorite Conspiracy Theories, Debunked). So this claim can now be laid to rest. --Mike Agricola (talk) 22:12, 15 February 2013 (UTC)

 Done Incorporated into article, thanks! Sailsbystars (talk) 23:07, 15 February 2013 (UTC)

Uploaded to the Internet

This line with no cite should not even by here. It is an opinion based on seeing many videos. I tried to fine a reference to keep it, but could not. Kennvido (talk) 11:57, 15 February 2013 (UTC)

Removed it. Evanh2008 ^{(talk|contribs)} 12:03, 15 February 2013 (UTC)

List of meteor air bursts

Somebody removed the "see also" to this list. I thought it to be kind of useful. Any second opinions? --Tobias1984 (talk) 12:03, 15 February 2013 (UTC)

Useful? Sure. Kennvido (talk) 12:05, 15 February 2013 (UTC)

It is a relevant link and I don't see any reason why it is being removed repeatedly. --PlanetEditor (talk) 12:27, 15 February 2013 (UTC)

I agree. It may be being removed due to edit conflicts. - Shiftchange (talk) 12:32, 15 February 2013 (UTC)

Brightness

Could someone add the apparent magnitude to the article, did it exceed -17 which is getting toward "Superbolide"? — Preceding unsigned comment added by 78.148.44.54 (talk) 17:28, 15 February 2013 (UTC)

Given the current size/energy estimates, and from all the videos, it was fantastically bright, well beyond -17, but I haven't seen any scientific numbers. Brighter than the Sun (-27) is certainly possible, and likely from everything I've seen. 70.88.60.185 (talk) 21:44, 15 February 2013 (UTC)

The Sutter's Mill meteorite had an apparent magnitude of -19 if I recall right. -- Kheider (talk) 16:28, 16 February 2013 (UTC)

Number of injured

The reported number of injured has now risen to 950. Source: https://twitter.com/SkyNewsBreak/status/302407144056188928 — Preceding unsigned comment added by 82.154.203.239 (talk) 13:28, 15 February 2013 (UTC)

Need something more official - "Russia Today" (not a Reliable Source) is also repeating the governor's claims. It's a current event, the totals will flucuate. HammerFilmFan (talk) 13:48, 15 February 2013 (UTC)

Injuries now up to 1200. http://www.popsci.com/science/article/2013-02/meteorite-blasts-russia-live-updateCheerioswithmilk (talk) 20:03, 15 February 2013 (UTC)

Lake frozen?

According to the Lake's page, it is currently frozen. The impact location should hence be visible (broken ice) if it really hit it. This should be clarified. — Preceding unsigned comment added by 83.64.188.210 (talk) 14:13, 15 February 2013 (UTC)

Done.--Auric talk 14:25, 15 February 2013 (UTC)

"Meteoriten-Splitter stürzten in See" (in German). Tages Anzeiger.: there is one picture of a 6 m diameter crater. --Chris.urs-o (talk) 14:34, 15 February 2013 (UTC)

English translation. Kingturtle = (talk) 14:47, 15 February 2013 (UTC)

I don't know how "fair use" and "copyright" work on the use of photos on the English Wikipedia from German and/or Russian sources. But if anyone does know how to navigate those wiki-waters, it would improve the article to have a photo of the large hole in the lake here in this article. N2e (talk) 15:23, 15 February 2013 (UTC)

"Fair use" is hopeless, I hope that we get some free images on Commons. As the fragments weight only some kilogramms, the craters and broken ice would be small. --Chris.urs-o (talk) 15:33, 15 February 2013 (UTC)

news sources showed a hole in the lake ice where the meteorite hit. I was concerned because it was very circular and would not expect that but the cameraman showed pieces of meteorite around the hole. Volcanoman7 (talk) 06:06, 16 February 2013 (UTC)

Let's all be clear - the object exploded - these are fragments that have fallen to Earth - it's wrong to say "the meteorite" hit if it isn't made clear these are fragments of the original object, not the "original" object - which, if it could have hit the ground, would have caused a catastrophe. HammerFilmFan (talk) 13:41, 16 February 2013 (UTC)

After the airburst, the fragments would enter "dark flight" and fall at terminal velocity. -- Kheider (talk) 16:31, 16 February 2013 (UTC)

Bolide

This is opinion and not fact based on someone's take of the article, if they can find a cite from an accredited source, I won't argue. I don't want an edit war on this. The editor has put back twice already. Kennvido (talk) 14:43, 15 February 2013 (UTC)

fireball is the best wiki term. Bollide is technically even a better term, but not often used outside of peer-reviewed papers. NOTE: It is a fireball while in the atmosphere, it is not a meteorite until it hits the ground. -- Kheider (talk) 14:53, 15 February 2013 (UTC)

Semantics... I would wait till someone OFFICIAL OFFICIALLY calls it what it is and then put it in the article. Kennvido (talk) 14:57, 15 February 2013 (UTC)

Forbes called it a bolide, though I wouldn't go off of this since it isn't an "official" science source.Cheerioswithmilk (talk) 16:05, 15 February 2013 (UTC)

References

There is no OFFICIAL OFFICIALLY for terms such as fireball & bolide. Think of them more as describers than given names. If you walk outside tonight & see a meteor streak through the sky, making a flash bright enough to cast shadows (actually rather common), you can proclaim it a bolide & be just as correct as me, an astronomer of over 3 decades ... or as correct as the IAU, NASA, or FOX. These type adjectives are not really hard & fast "official" names.

Add new section "Response" ?

Rather than grouping the information in initial report, would it be helpful to make a new section entitled "Response" ? Initial reports could be used for reports by witnesses while "Response" could be for government responses and reactions from scientists. Any opinions on this? Cheerioswithmilk (talk) 15:17, 15 February 2013 (UTC)

Energy involved?

BBC gives this information: "The Russian Academy of Sciences estimates that the meteor weighed about 10 tonnes and entered the Earth's atmosphere at a speed of at least 54,000 km/h (33,000mph). It would have shattered about 30-50km (18-32 miles) above ground, with most of the meteor burning up" (www.bbc.co.uk/news/world-europe-21468116).

Is anyone here able to calculate the energy of this event out of these data? It might be interesting to have an info about its (kilo-???)ton TNT equivalent in the article.

Greetings -- Tolman Telephone (talk) 15:24, 15 February 2013 (UTC)

Using those numbers, a straightforward Ke=1/2mv^2 calculation gives the objet a kinetic energy of 9.84 * 10^ 11 joules, which is about 235 tons of TNT equivalent. However, I would definitely hold off on putting anything down until we get an official energy equivalent from someone.Cheerioswithmilk (talk) 16:00, 15 February 2013 (UTC)

Good idea, it'd be Wikipedia:Original Research --Chris.urs-o (talk) 16:04, 15 February 2013 (UTC)

Wow, I never that there was such a thing as Wikipedia:Original Research. Let me know if anyone else decides to work on this, since I'd be happy to contribute.Cheerioswithmilk (talk) 16:09, 15 February 2013 (UTC)

I wonder if you misunderstood a bit there CwM. The point is that we are not allowed to use original research in Wikipedia articles; we need so-called reliable sources. With regards, Iselilja (talk) 16:23, 15 February 2013 (UTC)

Oops, silly me. Thanks for bringing this up. Lucky I didn't add this to the page. I left an article from Nature that estimated the yield to be several hundred kilotonnes down below if anyone would like to incorporate this.Cheerioswithmilk (talk) 16:37, 15 February 2013 (UTC)

I always get a laugh out of the "no original research, only reliable sources" argument. Where is the "reliable" list? Did someone "original" make that list? When someone "original" uses a "reliable" model of known physics, how is that different from someone elses calculation, who will remarkably use the same exact model to come to their OWN (i.e. original) calculation. — Preceding unsigned comment added by 98.159.69.146 (talk) 17:37, 15 February 2013 (UTC)

This just came in which shows that my initial, calculation was WAY off. The article says that the blast was in the hundreds of kilotonnes. However, it also puts the mass at 40 tons rather than 10-11 tons that we've been hearing.Cheerioswithmilk (talk) 16:19, 15 February 2013 (UTC)

References

Calculating the energy from a given speed and mass is NOT original research. From the given figures of 10 tons and 30 km/s I calculated 4.5 TJ or ~11 kilotons of TNT. I think the damage points to a larger explosion. I would go with Nature and say "several hundred kilotonnes". -- Petri Krohn (talk) 17:12, 15 February 2013 (UTC)

It is OR, and furthermore you've all made many calculation errors... it's 15 km/s so the equivalence is (15000m/s)^2*10000kg/4.184e9 J/kT=about 540 kT..... if 30 km/s it scales to ~2MT Sailsbystars (talk) 17:41, 15 February 2013 (UTC)

Even you're wrong, it's 4.184e9 J/T. Sagittarian Milky Way (talk) 18:12, 15 February 2013 (UTC)

Damn, you're right. This is why we let the Reliable Sources make the mistakes and don't include the numbers in the article otherwise. :) Sailsbystars (talk) 18:15, 15 February 2013 (UTC)

Actually it looks like Nature is also wrong, since they claim hundreds of kT, but the kinetic energy is only a few kT.... egads.... Sailsbystars (talk) 18:29, 15 February 2013 (UTC)

I'm speculating that the discrepancy is due to differing reports of mass/velocity. We've seen reports of 15-30 km/s which can cause the Ke to vary by a factor of 4 while there's also been a lot of differing mass estimates too. We'll have to see.Cheerioswithmilk (talk) 20:06, 15 February 2013 (UTC)

Nature is now estimating 7000 tonnes, which is self consistent with the other values they have listed. I can show from first principles and OR that you need at least tens of kilotons of kinetic energy (so not shown here).... so nature's estimate is most likely now the correct one. Sailsbystars (talk) 20:53, 15 February 2013 (UTC)

The JPL at NASA stated 20,000,000 lbs for the object - with an explosive force of about 500kt when it blew, about the size of a sub-launched Trident missile's single-warhead maximum yield from an American SSBN - without the effects of a nuclear detonation, of course. HammerFilmFan (talk) 13:45, 16 February 2013 (UTC)

If, as NASA reported, the speed of the object was 54,000Kph, and the mass was 10,000 metric tonnes, then the explosive energy could not have been ~550Kt. That's just incorrect math. The correct number should be half that. ~275Kt. This may have been a calculation error, or due to confusion about terms:
US Ton/short ton = 2000lbs.
Metric ton/long ton(tonne) = 1000Kg or 2200lbs.

Kinetic energy is calculated with the formula Ke=1/2mv^2. m is mass in kilograms and v is velocity in meters per second(m/s). An object traveling at 54,000kph, is traveling at 15,000m/s.(54000km/h * 1000m/km / 3600sec/hour) That results in a total energy of ((15000^2 * 10,000,000)/2) or 1.125x10^15J. Or 1.125 petajoules.

A kiloton equivalent of TNT explosive force is defined as 4.184x10^12(4.184terrajoules). Divide the two and you get an explosive equivalent of 268.88Kt. Or almost exactly half of the reported value of 550Kt.

I suspect that either someone forgot to do the "divide by 2" when working the kinetic energy formula, or got crossed up between 2000lbs per ton, and 1000kg per ton, when trying to work out the Kt equivalent.

It's also not clear how NASA produced their estimates. The speed is likely to be correct as NASA and Russian spacecom almost certianly got a fix on this thing and the computers should have been able work out a speed and track. From there, it's a question of: Did they have a way to estimate mass and derived the energy from that? In which case the value of 550Kt is twice too big. Or did they have a way to measure the energy expended and then they back calculated the mass from the energy released? In which case the value of 10,000 metric tons is too small by half.
Gcronau (talk) 18:42, 16 February 2013 (UTC)

550 Kt is from the infrasound measured (part of the Comprehensive [Nuclear] Test Ban Treaty). We are at 64-65,000 km/h. As I understand it, speed and energy gives mass. --Chris.urs-o (talk) 13:17, 17 February 2013 (UTC)

Speed?

The article currently cites two figures: "at least 54,000 km/h" (15 km/s), and 30 km/s. Any idea which is correct? Or is one figure its estimated speed at the object's entry into the atmosphere and the other at the time it passed over Chelyabinsk and started to blow up? Userboy87 (talk) 16:37, 15 February 2013 (UTC)

Impact crater

I found a picture of the frozen lake crater in the National Geographic website, with the respective proprietary notices: http://news.nationalgeographic.com/news/2013/02/pictures/130215-russia-meteorite-fragments-space-asteroid-chelyabinsk/#/russia-meteor-strike-lake_64337_600x450.jpg — Preceding unsigned comment added by 82.154.203.239 (talk) 18:21, 15 February 2013 (UTC)

Is that really an impact crater? It seems too perfectly round to be real. The object would have hit the ice at an angle and was almost certainly irregularly shaped (and possibly tumbling). The crater in the photograph is very round and there doesn't seem to be any damage to the ice outside of the crater or any ice "splashed" around the crater, either. — Preceding unsigned comment added by 78.16.145.6 (talk) 15:13, 16 February 2013 (UTC)

Such a crater would be easily more than 20 times larger than the body causing it, most of the hole been carved not by the passage of the body itself but by the horizontally accelerated ice. Shape and direction of the body play a much smaller role. Most of the horizontally moving ice would fragmentate to powder and get blown away, leaving near the edge of the hole just some slush and a few pieces of blue ice, which are indeed visible on the pictures, eg. http://darkroom.baltimoresun.com/wp-content/uploads/2013/02/REU-RUSSIA-METEORITE_1-719x540.jpg -- 46.115.56.181 (talk) 13:55, 17 February 2013 (UTC) Marco Pagliero Berlin

Largest object in a century?

• This article states: "The Chelyabinsk meteor is the largest object to hit the Earth in over a century, since the Tunguska event.[11]" and "Sciences estimated that the meteor, called KEF-2013,[7] had a mass of 10 tons[8]." However, the article at Sikhote-Alin meteorite states that another object fell in 1947 and weighed over 70 tonnes. Therefore, there is a contradiction between the two articles. Envergure (talk) 19:14, 15 February 2013 (UTC)
• Nature News has the mass of the 2013 object at 7,000 tonnes. Envergure (talk) 19:19, 15 February 2013 (UTC)

• It would be nice if the source were accessible and more specific. I have no problem changing it to "one of the largest". μηδείς (talk) 19:21, 15 February 2013 (UTC)

• 2012 DA14 has this table, 2013 object desintegrated at 30-50 km, it can't weight 7,000 tonnes:

Airburst estimates for a stony asteroid with a diameter ranging from 30 to 85 meters

Diameter	Kinetic energy at atmospheric entry	Airburst energy	Airburst altitude	Average frequency
30 m (98 ft)	708 kt	530 kt	16.1 km (53,000 ft)	185 years
50 m (160 ft)	3.3 Mt	2.9 Mt	8.5 km (28,000 ft)	764 years
70 m (230 ft)	9 Mt	8.5 Mt	3.4 km (11,000 ft)	1900 years
85 m (279 ft)	16.1 Mt	15.6 Mt	0.435 km (1,430 ft)	3300 years

• The table above uses Sentry's stony asteroid density of 2,600 kg/m³, Sentry's atmospheric entry velocity (V_impact) of 12.7 km/s, and an angle of 45 degrees.
• --Chris.urs-o (talk) 19:29, 15 February 2013 (UTC)

There appears to be a wide range of values for the size of the object being quoted ranging from several metres and ten tonnes (Russian Academy sciences), to 15 metres across and 7,000 tonnes in the Nature article (mass corrected from this morning). At the lower end of the range this object would not be remarkable other than it landed in a populated area and was widely seen.--Andromedean (talk) 19:55, 15 February 2013 (UTC)

We'll drink a tea, and wait for a reliable souce ;) --Chris.urs-o (talk) 20:07, 15 February 2013 (UTC)

Sound takes c. 3 seconds/km, so it takes 90-150 seconds for 30-50 km distance to hit the ground. I'll stick to 2 m diameter.[3] ;) --Chris.urs-o (talk) 20:22, 15 February 2013 (UTC)

NASA is saying several thousand tons, 15 metres (49 ft) diameter and a yield of several hundred kilotons, which fits with Chris's table above. If you halve the 30 m line that gives you a yield of perhaps 250 kt for an airburst. Per Medeis's comment above, NASA is also saying definitively that this is the largest since Tunguska. [4] Prioryman (talk) 23:08, 15 February 2013 (UTC)

I realise NASA is saying something different to the Russian academy of sciences or Russian scientists, the russians still seem to claim it was 10-15 tonnes in mass, yet the article claims they have used NASAs figure, check the link. --Andromedean (talk) 10:52, 16 February 2013 (UTC)

In this case, we should use both the lower and higher estimates = the range & note the appropriate refs. Cheers, !!!!

Are we sure that it was a stony metorite? If it was nickel-iron its density would be about a factor of 3 higher. LarryJayCee 20:45, 16 February 2013 (UTC)

Iron meteorite, density around 8; stony meteorite, density around 2.6; stony-iron meteorite, around 50% stony and 50% iron-nickel alloy. --Chris.urs-o (talk) 13:07, 17 February 2013 (UTC)

DA14 closest predicted approach

From the NASA article on the coincidental DA14 flyby:

Q: What makes 2012 DA14 special?

A: The flyby of asteroid 2012 DA14 is the closest ever predicted Earth approach for an object this large.

μηδείς (talk) 19:17, 15 February 2013 (UTC)

A Russian news source referred to both events on the same day as a 'cosmic coincidence'. HarryZilber (talk) 20:32, 15 February 2013 (UTC)

For what it's worth (and this constitutes original research), the impact on Chelyabinsk and close fly-by of 2012DA14 are probably not purely coincidental. Both objects (as well as the 1947 impactor) probably originated with the same body. When a gravitational encounter (with Earth) changes the orbit for an object, the intersection point for the new orbit with Earth's orbit remains the same location. So 2012DA14 is probably a fragment of the same object that produced the 1947 and 2013 impactors, in a deflected orbit from a meteor swarm which crosses earth's orbit in mid-February. Tarl.Neustaedter (talk) 01:16, 16 February 2013 (UTC)

From this NASA webpage: "According to NASA scientists, the trajectory of the Russia meteor was significantly different than the trajectory of the asteroid 2012 DA14, making it a completely unrelated object. Information is still being collected about the Russia meteor and analysis is preliminary at this point. In videos of the meteor, it is seen to pass from left to right in front of the rising sun, which means it was traveling from north to south. Asteroid DA14's trajectory is in the opposite direction, from south to north." Bubba73 ^{You talkin' to me?} 22:28, 16 February 2013 (UTC)

Sound of impact wave

If useful, including a link to this video that has the sound of the impact wave, including the sound of broken glass. I found it on Reddit. • Sbmeirow • Talk • 19:33, 15 February 2013 (UTC)

• https://www.youtube.com/watch?v=b0cRHsApzt8

10 tons and 15 meters diameter can't be right

If the meteor was roughly sperical, its volume should be around 1700m^3. If it had 10 tons, its density would be roughly 6 Kg per 1m^3! I'm no physicist but something's wrong. --Adam Zivner (talk) 19:54, 15 February 2013 (UTC)

See #Largest object in a century?

Meteorites aren't spherical

Sentry's stony asteroid density of 2,600 kg/m³

There appears to be a wide range of values for the size of the object being quoted ranging from several metres and ten tonnes (Russian Academy sciences), to 15 metres across and 7,000 tonnes in the Nature article. --Chris.urs-o (talk) 20:06, 15 February 2013 (UTC)

There's definitely some dispute over the mass/size of the object. This diagram from SETI: https://sphotos-a.xx.fbcdn.net/hphotos-ash4/487918_10151476473535535_2146887876_n.jpg has it pegged at 2 meters.Cheerioswithmilk (talk) 20:15, 15 February 2013 (UTC)

I know that they are not spherical and there can be less dense asteroids but density on the order of tens of Kg per 1M^3 is just ridiculous. Problem originates from mixing data from two estimates - if there's 15m diameter in the article, we should probably say weight is estimated to 7000 tons (which seems right) or alternatively "several meters diameter" and 10 tons, not to mix them both into the same context which then doesn't make much sense. --Adam Zivner (talk) 20:16, 15 February 2013 (UTC)

The 7000 tonnes is the only mass that makes sense, otherwise the kinetic energy is orders of magnitude too low to get the explosive energy measured.... Sailsbystars (talk) 20:50, 15 February 2013 (UTC)

I think that recent reports by NASA say 7,000 tons. We'll definitely have to edit the summary of the article because right now the size/mass just don't add up!Cheerioswithmilk (talk) 21:00, 15 February 2013 (UTC)

You could generically compare the Russian impactor to 2010 JL88 for a size / velocity / energy comparison. -- Kheider (talk) 21:12, 15 February 2013 (UTC)

Easy: we should specify the range of the estimated mass and size. BatteryIncluded (talk) 13:59, 16 February 2013 (UTC)

It seems that some sources are systematically mixing up tons and thousands of tons. Here is one example from today: "40 tonnes, 15 meters across". A 4 ton bolder would be about 1.5 meters across; 15 meters equals about 4,000 tons. -- Petri Krohn (talk) 16:04, 16 February 2013 (UTC)

If it was only 10 tons, at 18 km/s it would evaporate in 0.00000000001 seconds, while the people from NASA (who are clever enough to only lose 1 space shuttle per decade) say it stayed in the atmosphere for about 30 seconds.

But honestly, I think both those figures are "3-dimensional" - someone looked at the ceiling, at the floor, at the wall, and gave a random number. They simply have NO clues of how to calculate it's mass. No trajectory tracking, no material analysis (or is it analisys?), nothing. BadaBoom (talk) 17:00, 16 February 2013 (UTC)

They have ways to take educated guesses even in the short period since the event. De-acceleration, seismic energy imparted, strength and geographic extent of the sonic boom / shock wave, brightness etc. but they are just that. Also, spherical is a random unlikelihood, with a range of other shapes also being likely. Same with makeup, it could be rock, metallic, a dirty snowball like a comet, or a grouped cluster of such items. North8000 (talk) 23:33, 16 February 2013 (UTC)

• If we simplify and assume a cubic body 10 meters on a side with an absolute density of five, we get a mass of 100 x 100 x 100 x 5kg, which equals 5,000,000kg or 5,000 metric tons. A spherical body slightly larger with 7,000 ton mass makes perfect sense with such assumptions. μηδείς (talk) 23:44, 16 February 2013 (UTC)

Winter without window

• Any information about the consequences of all these homes without window in the cold Russian winter ? 83.163.5.82 (talk) 20:01, 15 February 2013 (UTC)

Can't remember where, but I saw maybe on pop sci that one of the most pressing issues was restoring heating and that people were trying to patch up windows with anything they had. I'll have to look around.Cheerioswithmilk (talk) 20:08, 15 February 2013 (UTC)

From first hand and popular knowledge in Canada: broken windows in winter = snow/melting snow/water damage plus frozen water pipes. The frozen pipes will usually burst leading to further, often very extensive water damage throughout the buildings unless the water pipes are quickly drained. You can bet there's a major repair campaign that will be going on throughout the region non-stop 24/7 to try and limit the damage to interiors. I have no cites for all that, but they are likely available. Best: HarryZilber (talk) 20:28, 15 February 2013 (UTC)

Apparently it may be even worse because the city uses central-supplied steam heating. Rmhermen (talk) 21:28, 15 February 2013 (UTC)

Actually, central heating (it's not steam, it's hot water) will actually make the situation somewhat better: even with the broken windows the heat from the tubes and radiators could keep the structures above freezing until the windows are repaired. In fact, the inhabitants are reported to jury rig some temporal window closures immediately, so they can wait for the more solid repairs. Khathi (talk) 03:45, 16 February 2013 (UTC)

It's about -15°C there, so the repairs are going non-stop.Khathi (talk) 03:45, 16 February 2013 (UTC)

Photo of crater in iced over lake.

http://rt.com/news/meteorite-crash-urals-chelyabinsk-283/ — Preceding unsigned comment added by Reddwarf2956 (talk • contribs) 20:46, 15 February 2013 (UTC)

Yeah, right. It's the drunk students who ran to the lake to "capture the aliens". They found a hole in the ice (most likely, made for fishing) and then told the reporters it's the crater. :-) Try photo Google searching and remember, Russia Today is a TV-mutation of New York Post. BadaBoom (talk) 17:05, 16 February 2013 (UTC)

Sikhote-Alin meteorite

May I change 1947 "Sikhote-Alin event" to 1947 "Sikhote-Alin meteorite" ? Dlohcierekim 21:11, 15 February 2013 (UTC)

I was bold :) --Robot Monk (talk) 22:23, 15 February 2013 (UTC)

 Done

Zinc factory zany

Wikipedia is not a forum

Why did the Chelyabinsk "zinc factory" roof cave in and why did its brick walls topple? Did the facility receive a direct hit from a falling object? It looks unlikely the roof and the walls fell merely to the power of sonic boom waves, as not even ALL the windows shattered in the city and there is no sign of masonry damage elsewhere, just glassware. By the way, Chelyabinsk is a major industrial and military center of Russia: nuclear powerplant, plutonium reprocessing facility, the tractor factory (tractor as in battle tank), etc. In an effectively infititely large land, like the former USSR, what is the chance of a space stone hitting a city instead of vast empty swaths? According to some recently discovered documents the nazis launched 4 IRBMs at the southern Ural industrial centre (probably Chelyabinsk) in April 1945 and at least 3 of those impacted in the target area. Consequently was this asteroid a neo-nazi, trying to imitate the deeds of that austrian painter or was it yet another great power with invasion plans, trying to hurt Mother Russia? 91.82.37.28 (talk) 21:18, 15 February 2013 (UTC) I think: the masonry of the zinc factory was in a bad state anyway. The shock wave was just 'the straw that broke camel's back' ;) --Chris.urs-o (talk) 21:26, 15 February 2013 (UTC) You have come to the wrong website. Ericoides (talk) 21:27, 15 February 2013 (UTC)

Lead sentence

The lead sentence of an article describes the thing, it does not restate the title we have chosen for the thing. "The 2013 Russian meteor event occurred on the morning of 15 February 2013 when a meteor" violates WP:MOSBOLD. We do not need to say that a "Meteor event (i.e., thing that occurred) occurred when a meteor did something". Per WP:MOSBOLD we just get straight into it. μηδείς (talk) 21:23, 15 February 2013 (UTC)

You guys are amazing

I know this does not bring anything to the discussion on how to improve this article, but I just want to tell how awesome this is that there is already such a detailed page on this event.

--Grondilu (talk) 21:32, 15 February 2013 (UTC)

• I have reviewed your Good Job and endorse its rationale. Dlohcierekim 21:54, 15 February 2013 (UTC)

• I was also impressed with the article. Great stuff! -- Alan Liefting (talk - contribs) 22:14, 15 February 2013 (UTC)

As the Official Parade Rainer, I have to say that most of this "detailed article" violates WP:NEWSPAPER. BadaBoom (talk) 17:28, 16 February 2013 (UTC)

New info

The NASA news conference is mentioning a Earth-crossing meteoroid with a 2-year orbit with an aphelion in the asteroid belt and a blast in the range of 300-500 kilotons. Hopefully this will show up in print sources soon as I don't think I can use this source as a reference. Rmhermen (talk) 21:37, 15 February 2013 (UTC)

Casualties?

So the following sentence...

The Chelyabinsk meteor is the largest recorded object to have hit the Earth since the 1908 Tunguska event and the 1947 Sikhote-Alin event, and the only known such event to result in a large number of casualties

...makes it sound like this killed a large number of people, but there is nothing on the article that mentions any deaths. Am I reading this wrong or is there some kind of discrepancy?

Jscottcc (talk) 23:04, 15 February 2013 (UTC)

Both injuries and fatalities count as casualties. Sailsbystars (talk) 23:06, 15 February 2013 (UTC)

Understood, though I've never heard of that before. Thanks, Jscottcc (talk) 23:18, 15 February 2013 (UTC)

Casualty (person) has the answers. Prioryman (talk) 23:27, 15 February 2013 (UTC)

True it means both injuries and fatalities but the readers tend to assume casualties to mean deaths. Indeed some thesauruses while mentioning wounded lean heavily to words such as deaths, fatalities and losses. Slight Smile 02:13, 16 February 2013 (UTC)

I think it should be changed to "injuries". Bubba73 ^{You talkin' to me?} 19:58, 16 February 2013 (UTC)

Near-Miss

"Though the known near-miss of asteroid 2012 DA14 occurred about 15 hours later"

At the end of the initial description, this other event is referenced as a "near-miss", despite the fact it missed the Earth. Intent to use the interesting verbiage "near-" should at least be follow by "hit", since a "near-hit" indicates that this asteroid indeed, missed the Earth. 68.35.43.145 (talk) 01:11, 16 February 2013 (UTC) Fixed in the time it took me to post, thanks. 68.35.43.145 (talk) 01:16, 16 February 2013 (UTC)

I see your logic, but near-miss is used idiomatically to mean "coming close but missing". You shouldn't change it. μηδείς (talk) 01:18, 16 February 2013 (UTC)

Explosive power

So the article currently says 0.1 kiloton twice and hundreds of kilotons twice. I really can't be both. Rmhermen (talk) 02:03, 16 February 2013 (UTC)

The latest word seems to be 300-500 kilotons, see this. Bubba73 ^{You talkin' to me?} 02:11, 16 February 2013 (UTC)

Easy: we should specify the ranges of the estimated power. BatteryIncluded (talk) 14:03, 16 February 2013 (UTC)

Data

This seems to be the latest info on the data:

• 45 feet across
• 7,000 tons
• hit the atmosphere at 40,000 MPH
• exploded 15 miles high
• 300-500 kilotons of explosive force

And it also describes it as a small asteroid from the asteroid belt. Data in the article could be updated. Bubba73 ^{You talkin' to me?} 02:21, 16 February 2013 (UTC)

Well, this one says 33,000MPH and 18-32 miles high. Bubba73 ^{You talkin' to me?} 02:30, 16 February 2013 (UTC)

Now these updated figures are 55 feet in diameter (17 meters), 10,000 tons, and nearly 500 kilotons. Bubba73 ^{You talkin' to me?} 03:31, 16 February 2013 (UTC)

Daily Mail says 40 tons, as does a TV report I just saw. All I know is that someone is incredibly wrong here. Evanh2008 ^{(talk|contribs)} 04:18, 16 February 2013 (UTC)

Of those four sources, the one closest to the data and likeliest to stand behind their numbers is NASA. The other three are undoubtedly just re-reporting what they heard elsewhere. Another source is Here, which uses 7000 tons and admits they've corrected it from an earlier figure of 40 tons. Tarl.Neustaedter (talk) 04:56, 16 February 2013 (UTC)

Cause of so many injuries by broken glass

Due to the slow speed of sound and shockwave versus speed of light, the bright light of the bolide was seen seconds to minutes before the shockwave. Since the light arrived first, many people went to their windows to look. When the shockwave arrived, the people were still at their windows looking at the smoke trail and were in a perfect place to be injured by the flying glass.

I think this should be included in the article

Vmaldia (talk) 02:36, 16 February 2013 (UTC)

It seems obvious but we're going to need a source on that. And judging by some of the damage, the windows exploded rather violently, so even those a distance away would have been hit. --MASEM (t) 02:43, 16 February 2013 (UTC)

Weight

NASA's weight estimate has risen from 7,000 to 10,000 tons. For a short time, this is what was stated in the article (10,000 tons). This is an estimate. It has one significant digit, which has been changing. It does not make sense to give a conversion with three significant digits. Also, with this resolution and it being an estimate, it doesn't matter whether it is a English ton (2,000 pounds) or a metric ton (1,000 kilograms). I agree with it being given as "10,000 tons". Bubba73 ^{You talkin' to me?} 05:23, 16 February 2013 (UTC)

I'll not weigh in on the estimated mass of the meteor; happy to go with whatever the scientists come up with after a few days from now. But I will mention that you can handle conversion using the {{convert}} template and still control the significant digits of the output variable with the |sigfig parameter. Take a look at the WP:CONVERT page to see all the syntax capabilities of that powerful unit conversion template. Cheers. N2e (talk) 05:37, 16 February 2013 (UTC)

Why did it break up?

I read somewhere that a Russian scientist explained that the reason this object broke up entering the earth's atmosphere is that the difference in pressure between the front side and the back side became so great that the object lost its ability to stay in one piece. I've not seen this written anywhere else. Usually the explanation is that it's the heat from friction that causes it to explode. Which is it, and could the correct explanation be included, as it applies to this meteoroid (or meteorite)? JohnClarknew (talk) 05:34, 16 February 2013 (UTC)

I'm sure that any and all forces that act on the meteor will additively make up the forces that produce the pressures that result in the ultimate deflagration of these air bursts. So both the force differential front to back, and also the heat which transmits a distance into the meteor and can boil off volatiles that are in some meteors can exert forces that lead to an air burst. I suspect we'll have to wait a few days/weeks for even the initial science claims to settle, and longer for the all the papers to be written as various scientists debate the interpretation of the data. Cheers. N2e (talk) 05:54, 16 February 2013 (UTC)

I assume, stony meteorites don't make it to the ground in one piece, but iron meteorites do. The applied forces are just too great. --Chris.urs-o (talk) 05:57, 16 February 2013 (UTC)

Yes I think irons have a better chance but we do not know what this was do we? At any rate, when meteors enter the atm. they heat up from the friction and tine pieces are knocked off. The heat also causes expansion which can melt or break further pieces off. Most meteor burn up before they hit the ground. Only large one like this make it to the ground. Judging from the size of the hole in the ice, I suspect that it was a fair size meteorite that hit. I am sure that scientist will try to locate it under the ice in the lake but may have to wait until summer. Volcanoman7 (talk) 06:59, 16 February 2013 (UTC)

The Tungunskan event may have been related to a meteor that heated so much and expanded so rapidly that it exploded before it hit the ground which would explain the lack of meteorites there. Volcanoman7 (talk) 06:59, 16 February 2013 (UTC)

It's an assumption, still. Iron meteorites don't explode, they could break apart, but stony meteorites desintegrate. --Chris.urs-o (talk) 08:18, 16 February 2013 (UTC)

I saw a picture of a olivine fragment, it might be a stony-iron meteorite. --Chris.urs-o (talk) 12:08, 16 February 2013 (UTC)

A picture of black fragments.[5] --Chris.urs-o (talk) 22:03, 16 February 2013 (UTC)

Why did it break up and explode in the air? This question needs a two part answer.

1. The meteor entered the atmosphere in a very shallow angle, just skimming the upper atmosphere. (See #Shallow angle below) In a steeper angle it might have pierced the atmosphere and hit the ground without breaking up. This precise angle is yet another coincidence. Apollo astronauts had a difficult task of firing their rockets on lunar orbit to at just the right moment hit the earth at the right angle. (TO DO: Find source for shallow angle, this may not be good enough.)
2. I meteor moving at 20 km/s has enormous kinetic energy, enough to vaporize the whole thing many times over. 1 kg at 20 km/s has 2*10^8 J/kg or 50 kg-TNT equivalent of energy. This again is similar to a spaceship re-entering Earth. Designing a re-entry vehicle is a difficult task, a breach will lead to a catastrophic failure as we saw happen to Space Shuttle Columbia. The meteor needs to slow down by ablation. At some point the heat generated may fracture the meteor. Any break up will lead to a catastrophic chain reaction; a larger surface is facing the atmosphere, more heat is generated, until whole chunks are broken into dust and stopped instantly – releasing all their energy at once. The videos show that some core components survived the blast and continued into... who knows where. -- Petri Krohn (talk) 23:07, 16 February 2013 (UTC)

And fractures cause a pressure build up inside the meteoroid. --Chris.urs-o (talk) 07:43, 17 February 2013 (UTC)

Location

The location is a problem. The meteorite struck a frozen lake according to news stories. Is it possible to get the actually location of the lake? Volcanoman7 (talk) 05:51, 16 February 2013 (UTC)

The main fragments hit near Chebarkul/ Chebarkul Lake. --Chris.urs-o (talk) 05:58, 16 February 2013 (UTC)

The crater in frozen Cherbakul Lake is reported to be 20 feet (6 meters) wide and is located approximately 3300 feet (1 kilometer) outside of the town of Chebarkul, which has a population of approximately 46,000 people. 2002:770C:F6A5:0:0:0:770C:F6A5 (talk) 06:44, 16 February 2013 (UTC)

Yes but the long/lat assoc. with this article puts the meteorite strike in the forest. Do you have a correct estimate of long/lat?Volcanoman7 (talk) 06:50, 16 February 2013 (UTC)

Meteorite fragments hit as an elliptic strewnfield, see File:Bassikounou meteorite strewn field.jpg and File:Allende Strewnfield1.jpg --Chris.urs-o (talk) 08:14, 16 February 2013 (UTC)

The Wikimapia page for this lake has a supposed location for the crater: 54°56'48"N 60°19'15"E [6].--Auric talk 17:34, 16 February 2013 (UTC)

I think the location should point to the site of the 0.5 megaton air burst explosion, located some 20 km south-south-east of Chelyabinsk. A six meter hole in the ice on some lake is totally irrelevant when we are talking about a 20 million pound boulder with a TNT equivalence of 50 times that. As for the location of the meteor, my best guess – based on the visual evidence – is that it exited the atmosphere and flew off into space. -- Petri Krohn (talk) 23:56, 16 February 2013 (UTC)

This source says "there’s still no sign of even the smallest bit of the meteorite". Therefore any location near Chebarkul Lake is bogus. -- Petri Krohn (talk) 01:38, 17 February 2013 (UTC)

So what made the hole in the ice? Absence of evidence is not evidence of absence. 1.178.161.116 (talk) 14:29, 17 February 2013 (UTC)

Here is a location: 55.150°N, 61.410°E (6 km South (185°) from Chelyabinsk, Russia) -- Petri Krohn (talk) 03:00, 17 February 2013 (UTC)

Other Meteorite Events?

I saw the most recent inclusion of the San Francisco Event, but there's no mention of the Cuba Event that supposedly took place during the same day of the event. I wonder if we should include the Cuba Event here or should we split the various events into it's own page showing all events that has taken place on Febuary 15th? Sawblade5 ^{(talk to me | my wiki life)} 06:15, 16 February 2013 (UTC)

Neither has been reported as connected in any fashion that I can find. I removed the San Francisco bit; visible meteors hit pretty often, and the media is going to be reporting ANY random meteor for the next couple days most likely... So unless there is something notable about the other event (e.g. 2012 DA14, which is notable so we mention it's not connected), or the events are connected in reliable sources, then it probably shouldn't be listed. – 2001:db8:: (rfc | diff) 06:26, 16 February 2013 (UTC)

scientific community is not making an connection between other meteorites hitting or the close fly by that happened today.Volcanoman7 (talk) 06:52, 16 February 2013 (UTC)

Basketball sized objects impact-Earth daily. -- Kheider (talk) 17:02, 16 February 2013 (UTC)

Ogg file

I think an ogg file should be insert in this article. Model, but not free. [7] - EugεnS¡m¡on(14) ® 09:39, 16 February 2013 (UTC)

Time and duration of the event

Are there any reliable sources that mention when this event happed (GMT)? And also, how long the event took in minutes? These details would seem important. Thanks. 64.40.54.103 (talk) 11:01, 16 February 2013 (UTC)

Moving at a speed of at least 54,000 km/h, from c. Chelyabinsk (55°09′17″N 61°22′33″E) to c. Chebarkul (54°59′N 60°22′E). The sound and the shock wave took longer from 30-50 km high (c. 90-150 seconds). --Chris.urs-o (talk) 11:08, 16 February 2013 (UTC)

Thank you 64.40.54.103 (talk) 11:22, 16 February 2013 (UTC)

NASA says 3:20:26 UTC on Feb. 15. Other sources concur. The prior stated time of 3:13 was not in provided references, and is appallingly inaccurate given the reliability of the data for 3:20. Samuel Erau (talk) 01:31, 17 February 2013 (UTC)

CCTV camera footage gives a time of 09:20:31 for the 0.5 megaton blast. The fireball outshines the sun starting at about 09:20:27. -- Petri Krohn (talk) 02:00, 17 February 2013 (UTC)

Slight correction

The article says "Although the known close approach of asteroid 2012 DA14 occurred about 15 hours later" - it should read 'about 14 hours later' as DA14 was at its closest to earth at 19:25 GMC/UTC. (ref: http://www.bbc.co.uk/news/science-environment-21442863). 03.20 UTC to 19.25 UTC = 14 hours and 5 minutes. 86.133.51.180 (talk) 12:24, 16 February 2013 (UTC)

• also can someone add UTC to this bit "On the same day of 15 February just after 8 PM PST," so we can directly compare it with the Russian event? 86.133.51.180 (talk) 12:27, 16 February 2013 (UTC)

Atmospheric Entry Time Sequence Incorrect

The main article states "On 15 February 2013, a meteoroid entered Earth's atmosphere over Russia around 09:20:26 Yekaterinburg Time (03:20:26 UTC), becoming a fireball." Yet this sequence is incorrect. The time stated in the article is not the actual atmospheric entry time but the time of the main explosion. According to The Planetary Society... "The time of the main flare/airburst was 03:20:26 UT on Feb 15, 2013; the fireball began ablation about 30 secs before this time." This then indicates that the entry into Earth's atmosphere is currently unknown and most references to time relates primarily to the actual explosion of the meteoroid. The fireball commenced 30 seconds before the explosion and the meteoroid entered the atmosphere at some point before the appearance of the fireball. Therefore the first sentence of the article needs to be corrected to better reflect a more correct sequence of events. The Planetary Society states that this information was updated at a NASA Press Conference.

Source: The Planetary Society 1.178.161.116 (talk) 13:48, 16 February 2013 (UTC)

No, moving at about 18 kilometers per second, the fireball began at 50 km altitude and exploded at 15-20 km altitude, just some seconds later. The sound and the shock wave took c. 45-60 seconds from 15-20 km altitude to reach the ground.

Quote: "disintegration in the skies over Chelyabinsk, Russia, at 7:20:26 p.m. PST, or 10:20:26 p.m. EST on Feb. 14 (3:20:26 UTC on Feb. 15)."

Quote: "The infrasound data indicates that the event, from atmospheric entry to the meteor's airborne disintegration took 32.5 seconds."[8]. Ok, you are right. --Chris.urs-o (talk) 13:51, 16 February 2013 (UTC)

That is exactly what The Planetary Society is saying. Ablation occurred at approximately 30 seconds before the explosion, which is enough time for the meteoroid to travel from 50km altitude to 20km altitude, although NASA themselves claim that the explosion erupted at around 10,000 meters altitude (10km). And the shock wave took an average of about 120 seconds, not 60 seconds, as evidenced from videos recorded in the cities directly underneath the meteor trail. 1.178.161.116 (talk) 14:16, 16 February 2013 (UTC)

90-150 seconds seems to be the average time as evidence by most video sequences, from explosion to shock wave. 1.178.161.116 (talk) 14:28, 16 February 2013 (UTC)

90-150 seconds means that the air burst was 31-51 km from Chelyabinsk, at 10-15 km altitude. --Chris.urs-o (talk) 15:05, 16 February 2013 (UTC)

The shadows point to a higher angle, almost 45 degrees from Chelyabinsk, meaning a higher altitude for the explosion. -- Petri Krohn (talk) 16:28, 16 February 2013 (UTC)

Tons

Right now, in one place it says 10 tons and another it says 10,000 tons. Bubba73 ^{You talkin' to me?} 15:27, 16 February 2013 (UTC)

See #10 tons and 15 meters diameter can't be right above. -- Petri Krohn (talk) 16:20, 16 February 2013 (UTC)

NASA is at 18 km/seconds, estimated size of 17 m, 10,000 tons and 500 kilotons of TNT equivalent. This is one estimation.

Iron's specific gravity is c. 7,870 kg/m³, Hoba meteorite's specific gravity is around 8,000 kg/m³ (an iron meteorite), Sentry uses a specific gravity of 2,600 kg/m³ for stony asteroids. --Chris.urs-o (talk) 18:00, 16 February 2013 (UTC)

Controversy response

Can be this declaration included in the article? - EugεnS¡m¡on(14) ® 17:59, 15 February 2013 (UTC)

Perhaps eventually in a "conspiracy theories" section complete with debunking. The claim is not credible because the velocity of an ICBM cannot exceed about 7 km/s owing to orbital mechanics, but this rock was travelling at 15 km/s. Sailsbystars (talk) 18:04, 15 February 2013 (UTC)

We do not yet know the speed of the object. The estimate 15 km/s 11 km/s is just the escape velocity from Earth's gravitational field, meaning anything falling from deep space would have at least that speed. Triangulating from the video footage of the event would allow one to calculate the speed of the object, but as far as I know, no one has yet even calculated the trajectory. -- Petri Krohn (talk) 18:15, 15 February 2013 (UTC)

Although eventually a small section on conspiracy theories may need to be included, I don't think any of it is appropriate as of now. If one individual makes an outlandish claim and it is published without widespread adoption as possibly being true I don't believe it should be included per WP:N. It can't be a conspiracy theory until a sizable number of people believe it to be true. Schenka (talk) 18:23, 15 February 2013 (UTC)

Escape velocity is 11 km/s. 15 km/s is substantially faster.... Sailsbystars (talk) 18:34, 15 February 2013 (UTC)

The main thing would be the orbital velocity of an object around the Sun, not the escape velocity of Earth. Bubba73 ^{You talkin' to me?} 21:31, 15 February 2013 (UTC)

That's not correct. Basic physics. Escape velocity is the velocity needed to escape from earth's gravity well. I.e. it's the kinetic energy needed to cancel the negative potential energy. Entering the gravity is the opposite process, so the impact velocity has to be at least the escape velocity... The velocity relative to earth gets added on top of that... Sailsbystars (talk) 21:37, 15 February 2013 (UTC)

The meteor did not hit the Earth because it was pulled in by Earth's gravity. It hit because its orbit around the Sun put it on a collision course. Bubba73 ^{You talkin' to me?} 01:49, 16 February 2013 (UTC)

Yes and no: without gravity at all, it would probably have passed somewhat farther away. The gravitational cross-section of Earth is slightly larger than its geometrical cross-section: http://www.ips.gov.au/Educational/4/1/8 --46.115.56.181 (talk) 13:38, 17 February 2013 (UTC) Marco Pagliero Berlin

Its velocity was mainly because if its orbit around the Sun. The Sun had a stronger pull on it than the Earth did until it got pretty close. Bubba73 ^{You talkin' to me?} 14:47, 17 February 2013 (UTC)

Punctuation

The following text is a verbatim quote from our article, and has wrong punctuation:

which would make it 20-30 times more powerful than the Trinity nuclear test in New Mexico (18 kilotons of TNT equivalent)[10], or atomic bomb detonated at Hiroshima (16 kt), atomic bomb detonated Nagasaki (21 kt).

It should instead say this:

which would make it 20-30 times more powerful than the Trinity nuclear test in New Mexico (18 kilotons of TNT equivalent)[10], the atomic bomb detonated at Hiroshima (16 kt) or the atomic bomb detonated Nagasaki (21 kt).

98.118.62.140 (talk) 15:34, 16 February 2013 (UTC)

L1 Lagrangian point shepard = related

L1 Lagrangian point shepard = related

I wouldnt trust Phil Platt to tell me the sun was coming up - and any other astromomer that is so quick to decide that the two events are not related is a moron--68.231.15.56 (talk) 18:57, 16 February 2013 (UTC)

I believe that WP:NOT somehow applies to this, but seeing as how I cannot find anything appropiate, I will just point out that we have references that state NASA, the Sodankylä Geophysical Observatory, and several independent astronomers have stated that the two events are independent of each other. (We also have a mention that the European Space Agency and "Russian sources" have also considered the two events to be unrelated, but that is not currently referenced.) Do you have a source of a notable astronomer who believes that the two events are related? --Super Goku V (talk) 20:35, 16 February 2013 (UTC)

i see that you just dont get it - the point is that anyone telling you that they know this quick is not to be trusted - most astronomical work takes years of data crunching - anyone telling you they know something by the next "news cycle" is a liar and a hack - let me know again in a year from now and then all the real astronomers will have carefully checked out the solution set--68.231.15.56 (talk) 20:44, 16 February 2013 (UTC)

Very well, but can you produce a current source that either shows or suggests that the events are related or a source about an astronomer that is planning on checking the "solution set" in the next year or so? That would allow for a way to include it into the section as an alternate point-of-view. --Super Goku V (talk) 21:18, 16 February 2013 (UTC)

as for source - I have worked in about 20 different scientific labs in my life - if you go look at the published literature on any one of them you would be 3 years incorrect on what they are actually currently working on - they are in the business to publish thus they dont tell you or their competitors what they are doing until they submit a finished publishable paper - who is working on it today? there is no way to know - what i do know is that someone will alter the article in the a couple of years to tell us what the real truth is and they will have peer reviewed data and equations to prove it--68.231.15.56 (talk) 21:34, 16 February 2013 (UTC)

I have one last question. How does this section help to improve the article? --Super Goku V (talk) 22:07, 16 February 2013 (UTC)

NOTNEWS- What is written today about "the meteor and asteroid are not related" is = NEWS which wiki is not--68.231.15.56 (talk) 22:22, 16 February 2013 (UTC)

WP:NOTNEWS says "Wikipedia is not a paper source, editors are encouraged to include current and up-to-date information within its coverage, and to develop stand-alone articles on significant current events. (emphasis added)" If you would like to have this article deleted, then you can suggest an AfD. However, I do not understand the point you are trying to making, especally by citing Wp:NotNews. In any case, I believe that this section is possibly violating WP:NOT#FORUM and, if it is found to be the case, should be closed as such. --Super Goku V (talk) 22:34, 16 February 2013 (UTC)

Modern super computers do not take years to "crunch data". Most computer simulations these days are in real time and it would only take several hours for astronomers to gather the data and build a coherent reconstruction of the event. Also this suggestion smacks of 'conspiracy' and does not belong in an article devoted to factual reporting. The fact remains that NASA, the Sodankylä Geophysical Observatory, and several independent astronomers all strongly believe that the two events are not related and that is what the article will state. To ignore such statements as non-factual risks introducing original research. 1.178.161.116 (talk) 01:49, 17 February 2013 (UTC)

Check out these links for more information on the orbit of the Russian meteor. These are people that do this for a living.

• How do we know the Russian meteor and 2012 DA14 are not related? (NASA Meteor Watch)
• Video of the orbit of Russian meteor (David Clarke)

check out what? both of these are hack attempts to get quick publicity for absolute ignorance - both of these so called orbits ASSUME that they know the orbit before the yesterday which they do not - essentially nothing this earlier in the data crunching gives more than the trajectory from an initial value point of more than a few minutes since the meteor was unobserved and completely unknown before that - to put it in plain English you dont know the initial values more than a few minutes back which is just about useless for an next day "news cycle" calculations--68.231.15.56 (talk) 21:20, 16 February 2013 (UTC)

Freud replied "sometimes a cigar is just a cigar," - usually the most likely solution is the correct one - a rare large meteor and a rare large asteroid near earth at the same time - guess what? they are probably related!--68.231.15.56 (talk) 21:43, 16 February 2013 (UTC)

You can trace the trajectory backwards using multiple video sources and can easily determine the impactor had a significantly different orbit than DA14. -- Kheider (talk) 21:43, 16 February 2013 (UTC)

The MIT astronomer on the NY Times video said that they were traveling in opposite directions, so unrelated. Bubba73 ^{You talkin' to me?} 21:51, 16 February 2013 (UTC)

this means nothing - i will ask you this - DA14 was a non plane of the ecliptic solar object was the meteor also? if yes i tell you are an idiot to think that two fairly RARE non plane of the ecliptic solar objects just happened to arrive at earth in any similar time frame--68.231.15.56 (talk) 22:02, 16 February 2013 (UTC)

2012 DA14 has a modest orbital inclination of 11 degrees. I see 4499 known NEOs with an orbital inclination > 11. -- Kheider (talk) 22:21, 16 February 2013 (UTC)

i have altered my statement to fit your data--68.231.15.56 (talk) 22:40, 16 February 2013 (UTC)

The Russian meteor was travelling from east to west in a west-south westerly direction while DA14 passed the earth from south to north in a north-north westerly direction. The two trajectories were nearly perpendicular to each other and indicate that the meteor approached from a very different angle to the asteroid. 1.178.161.116 (talk) 02:03, 17 February 2013 (UTC)

removed forum-like comedy content not on topic--68.231.15.56 (talk) 06:42, 17 February 2013 (UTC)

so let me be clear i have been threatened 3 times in this talk content section - who exactly would bother to expect me to continue supplying any discussion of what is clearly wrong with the article? Speak heresy and next thing you get is threats - myself, i only wish to know truth - and what is in the article currently is next day "news cycle" pseudoscience - grats if that is what you think should be in an encyclopedia.--68.231.15.56 (talk) 06:47, 17 February 2013 (UTC)

You need to back up your contributions with reliable sources if you wish to present them in such a persuasive way as you have, not rely on trust or belief to forward your 'supply' of information. If your contribution does not come from your own logical deduction then you must present your source of information that leads you to such conclusions. Anything apart from that approach will be met with considerable doubt and disinterest from others. 1.178.161.116 (talk) 09:48, 17 February 2013 (UTC)

Shallow angle

The entry was shallow. This blog entry clearly explains that if the same object had entered the atmosphere at a steep angle, the 10000 tons of it would have reached the ground without breaking up with catastrophic consequences. Hektor (talk) 20:06, 16 February 2013 (UTC)

It seems that the angle was extremely shallow. With the stated figures of 31 seconds flight and a speed of 20 km/s, the meteor could have flown 620 km before the explosion. The curvature of the Earth in 620 km (5,58 degrees) is about 30 km. It is thus possible that the meteor "entered" the atmosphere somewhere above Siberia at the height of 50 km and flew vertically over Chelyabinsk. If the trajectory had been only a few kilometers higher, we would have seen a fireball in the sky, flying past and re-entering space after leaving the atmosphere.

Form the videos we see that some parts of the meteor survived the air burst explosion and continued on the same trajectory. The smoke trails continue for several hundred kilometers. It is thus possible that these pieces of the meteor exited the atmosphere and possibly Earth's gravitational field. If not, they might be coming back next week. -- Petri Krohn (talk) 23:41, 16 February 2013 (UTC)

Orbit

Has the orbit of the object around the Sun before impact been determined? Hektor (talk) 20:27, 16 February 2013 (UTC)

Russian Page Translation / Names and Diameter of Both Objects

Russian Page:

• "The fall of the meteorite in the Urals in the year 2013"

• Can be translated here: Bing Translator

The Russian impact meteor is tentatively named KEF-2013 and was roughly 50 feet wide/in diameter. The one that missed some 15 hours later is named 2012 DA₁₄ and is roughly 150 feet wide/in diameter. ---Radical Mallard (talk) 20:43, 16 February 2013 (UTC)

Units

" a roughly 50-foot wide" How much is that?. Use meters! 190.162.143.208 (talk) 20:46, 16 February 2013 (UTC)

17 meters and 50 meters.---Radical Mallard (talk) 20:50, 16 February 2013 (UTC)

Energy Released Clarification

When NASA said it released 500 kilotons of energy they mean in the entire time it burned up, not in some great explosion.... so even if KEF-2013 landed on a city it would have only damaged an area like that of the thee craters found so far, so it wouldn't have been cataclysmic at all. Which is good to know, right? I think the public will want to know the names of the two objects, the sizes, the masses, any relation to each other, and how much damage they could cause. Hopefully it will motivate Russia and the USA and Europe to work on a better Spaceguard system.---Radical Mallard (talk) 21:12, 16 February 2013 (UTC)

• Being that it was traveling at more than 60,000 MPH, I don't think there's any serious question that the damage done would have been very serious indeed had this thing hit the ground in one piece. ► Belchfire-TALK 00:05, 17 February 2013 (UTC)

I'm guessing only could have done that id the entry trajectory was less of an oblique angle and was directly aimed at the surface. Too much time in the sky and the thing sheds too much matter. The actual impacts were nowhere near as impressive as the sky show and the pressure wave.---Radical Mallard (talk) 02:22, 17 February 2013 (UTC)

• Regarding your statement about Spaceguard, the Los Angeles Times is reporting that this incident has spurred U.S. Congressional Rep. Lamar Smith to "schedule a hearing to examine ways to better identify and address asteroids that pose a potential threat to Earth." (see Russia meteor prompts U.S. lawmakers to call for protective steps). Politico also covered the story and provides some additional information. It seems sufficiently notable for the article's "Reaction" section to make mention of. --Mike Agricola (talk) 21:26, 16 February 2013 (UTC)

If it hadn't "blown up", all of that energy would have still been in the meteor when it hit Earth - causing a larger crater. Rmhermen (talk) 21:45, 16 February 2013 (UTC)

For asteroids less than ~85 meters in diameter, airbursts do more damage than a ground impact would. There is a reason military bombs are designed to burst above the ground rather than explode on impact. -- Kheider (talk) 07:44, 17 February 2013 (UTC)

NY Times Report of Meteor Size

Well according to this New York Time video from yesterday:

• Meteor Hits Russia, With Debris Blanketing Siberia - Fire in the Russian Sky

...KEF-2013 was "the size of an SUV"... like, no larger than 4.5 meters in diameter, instead of 17 meters. Of course nobody really knows all the facts just yet.

Here is an early RussiaToday report (this isn't a political story so I guess it isn't subject to the usual bias):

• Apocalypse Now? Meteorite hits Russia lighting sky, shattering windows

Once all of the many cell phone and closed circuit videos are made public scientists will be able to determine a decent amount of detailed information about the energy released based on what they see in them. ---Radical Mallard (talk) 21:31, 16 February 2013 (UTC)

NASA says 17 m of diameter and 7000 to 10000 tons, which corresponds to a density of 4 tons per cubic meter, which seems to me quite realistic. 83.163.5.82 (talk) 23:16, 16 February 2013 (UTC)

And NASA measured the energy released by the airburst using a global network Infrasound detectors, designed to measure the location and size of atmospheric nuclear tests, the 500 kiloton figure is accurate. They probably use the impact effects calculator[9] developed by Marcus, Jay Melosh and Collins[10] to work out the pre-impact mass and diameter of the object. Though I have to use 7.5 tons/m³ (an Iron-Nickel meteorite) to get a compatible result. The shock-wave however seems to be modelled correctly, arriving 33 seconds after the airburst. --Diamonddavej (talk) 02:11, 17 February 2013 (UTC)

Coincidental asteroid approach

The section "Coincidental asteroid approach" should be removed, as an encyclopedia should state facts, not be a detailed record of the speculations that were made before the facts became known.

The sentence that covers this in the intro is entirely sufficient. Bomazi (talk) 22:06, 16 February 2013 (UTC)

Disagree. Even if the two turn out to be unrelated, the coincidence is notable just for its extreme un-likelyhood. Gaohoyt (talk) 01:01, 17 February 2013 (UTC)

It is possible to follow the rules so strictly that you "break" something. It would be incredibly obtuse if we didn't mention this staggering coincidence, and similarly, I notice some people dont want us to use the Russian name for the asteroid that impacted, as if we are waiting for NASA to name it, so the Russian designation is being buried away and it's just called "the asteroid event". But What if we want diagrams with the track of this asteroid in the past few hundred years before it hit earth? surely it shows up in photos, we just ignored it until now. What should we call it?---Radical Mallard (talk) 02:30, 17 February 2013 (UTC)

Map image

We really need a map image showing its path over Russia and where it went boom with those concentric circles showing where the windows blew out and where it was audible, and even where it was visible. This is exactly what 180,000 visitors want to see.

If someone doesn't make one fast, I'll be forced to make one from maps-for-free, a pocket calculator, and MSPaint, and it won't be pretty. So get on it, boffins! :) Anna Frodesiak (talk) 01:35, 17 February 2013 (UTC)

Do we have a source for the trajectory? The best I have seen so far is a weather satellite image of the smoke trail. -- Petri Krohn (talk) 01:42, 17 February 2013 (UTC)

We could use that for now with an image caption "approximate". Anna Frodesiak (talk) 01:45, 17 February 2013 (UTC)

Okay. I see File:Russianmeteorche.jpg. It may be deleted, but we could use the data along with the smoke trail sat photo to cobble something together. It's been an hour and still no map! Come on boffins. We're waiting. Is it a national holiday on the Boffin Islands or something? Anna Frodesiak (talk) 02:59, 17 February 2013 (UTC)

Excellent for a start. I think an elliptical area would be a 2nd step. But oriented how? We ought to be able to determine what direction the track came in from? Dimensions/exact shape of the damage area will take time Friendly Person (talk) 05:40, 17 February 2013 (UTC)

See Talk:2013 Russian meteor event#Direction of the object. From c. Yemanzhelinsk (54°45′00″N 61°19′00″E)/ Chelyabinsk (55°09′17″N 61°22′33″E) to c. Chebarkul (54°59′N 60°22′E), NE to SW? (File:Chelyabinsk 2013 meteoroid trajectory.jpg) (EUMETSAT Meteosat-9.i - EUMETSAT Meteosat-9.ii) --Chris.urs-o (talk) 07:50, 17 February 2013 (UTC)

See Reconstructing the Chelyabinsk meteor’s path, with Google Earth, YouTube and high-school math --Chris.urs-o (talk) 11:16, 17 February 2013 (UTC)

Google withdraws asteroid logo

Will any mention be made about Google and their sudden decision to withdraw their animated logo after hearing reports of the Russian meteor? The decision was made after hearing that hundreds of people had been injured in the blast. I believe it is significant enough to rate a mention in the article somewhere. The Google logo basically consisted of the letter 'g' jumping aside to allow the asteroid to pass through the word 'Google'. 1.178.161.116 (talk) 02:26, 17 February 2013 (UTC)

Not worthy of mention, IMO. Bubba73 ^{You talkin' to me?} 02:31, 17 February 2013 (UTC)

Find a source. -- Petri Krohn (talk) 02:42, 17 February 2013 (UTC)

Likely it was a logo for the DA14 asteroid since otherwise Google would need to make a logo within an hour or so of hearing of the event, but before it heard about an injuries, which would be unlikely in my book. --Super Goku V (talk) 03:18, 17 February 2013 (UTC)

Indeed worthy of mention. Here is just a small sample of sources... The Telegraph The Hindustan Times CNet Yahoo News The Drum Search Engine Watch ABC News Silicon Republic Gizmodo The Inqusitr RYOT Beta 1.178.161.116 (talk) 04:59, 17 February 2013 (UTC)

Peak Overpressure Needed to Break Window Glass

The threshold peak overpressure needed to break window glass is ca. 0.25 pound per square inch (psi) (1% breakage), 90% of windows break at 0.9 psi (Lee's Loss Prevention in the Process Industries: Hazard Identification, Assessment, and Control on 17/236). An on-line meteor impact effects calculator[11] using current accepted parameters predicts a 0.293 psi peak over pressure. --Diamonddavej (talk) 02:35, 17 February 2013 (UTC)

"Chelyabinsk meteoroid" - wrong label

Why is it being called "Chelyabinsk meteoroid" in the first sentence? --PlanetEditor (talk) 03:00, 17 February 2013 (UTC)

To answer your question, most likely because that is the name the the media, i.e. our sources use. It is however questionable if the object should be called a meteoroid. All other objects listed in Near-Earth object#Historic impacts are called asteroids. -- Petri Krohn (talk) 03:26, 17 February 2013 (UTC)

It was an asteroid, asteroids are >1 metre in diameter, it was ~17 metres in diameter ("Meteorite and meteoroid: New comprehensive definitions"[12]). --Diamonddavej (talk) 03:45, 17 February 2013 (UTC)

Just because we didn't notice it doesn't count for anything. It was real, it existed all this time. It was as real as all the thousands of objects like it in orbit around the sun, and as real as all the hydrogen bombs in the worlds arsenal. Also, can't we use the name the Russian astronomers are using for the object?--Radical Mallard (talk) 05:11, 17 February 2013 (UTC)

It was caused by an asteroid and will probably come to be known as the "Chelyabinsk event". -- Kheider (talk) 06:50, 17 February 2013 (UTC)

No, fragments were found, it'll be named "Chelyabinsk meteorite", probably. --Chris.urs-o (talk) 07:37, 17 February 2013 (UTC)

Detectable?

First paragraph currently reads, "Being significantly smaller than objects that are tracked through current efforts by space object scientists, the meteor was not detected before atmospheric entry.[11]" I think this is incorrect. NASA and other databases routinely track near-earth objects of 2-3 meters in diameter, and TC 2008, the 2-5 meter asteroid that hit Sudan in 2008, was detected 20 hours in advance. The reason this one was not detected was because we don't detect many of them. Funding is too sparse to do that. Had we detected this one a few hours in advance, these people could have gotten away from windows at least. Friendly Person (talk) 05:31, 17 February 2013 (UTC)

• Well if it had been detected on short notice the trajectory would not had been very well known so the impact point would not have been known either. It was a shallow entry, that means the asteroid nearly missed Earth. If it had been Bull's eye, the entry slope would have been 90 degrees... That means if it had been detected the alert would probably have had to be worldwide. The question of the detection comes to the orbit prior to impact. Is it known ? was the object eccentric ? was it coming from the direction of the Sun, making it hard to detect ? 83.163.5.82 (talk) 07:27, 17 February 2013 (UTC)
  • It was black, black objects are more difficult to find. --Chris.urs-o (talk) 07:34, 17 February 2013 (UTC)