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Russian meteor largest in a century

Explosion rivalled nuclear blast, but rock was still too small for advance-warning networks to spot.


A meteor that exploded over Russia this morning was the largest recorded object to strike the Earth in more than a century, scientists say. Infrasound data collected by a network designed to watch for nuclear weapons testing suggests that today's blast released hundreds of kilotonnes of energy. That would make it far more powerful than the nuclear weapon tested by North Korea just days ago and the largest rock crashing onto the planet since a meteor broke up over Siberia's Tunguska river in 1908.

"It was a very, very powerful event," says Margaret Campbell-Brown, an astronomer at the University of Western Ontario in London, Canada, who has studied data from two infrasound stations near the impact site. Her calculations show that the meteoroid was approximately 15 metres across when it entered the atmosphere, and put its mass at around 7,000 metric tonnes. "That would make it the biggest object recorded to hit the Earth since Tunguska," she says.

Hidden approach

The meteor appeared at around 9.25 a.m. local time over the region of Chelyabinsk, near the southern Ural Mountains. The fireball blinded drivers and a subsequent explosion blew out windows and damaged hundreds of buildings. So far, more than 700 people are reported to have been injured, mainly from broken glass, according to a statement from the Russian Emergency Ministry.

The meteor contrail seen over Chelyabinsk, Russia, on 15 February. The object's explosion in the atmosphere is reported to have injured more than 700 people.

Despite its massive size, the object went undetected until it hit the atmosphere. "I'm not aware of anyone who saw this coming," says Heiner Klinkrad, head of the European Space Agency's space debris office at the European Space Operations Centre in Darmstadt, Germany. Although a network of telescopes watches for asteroids that might strike Earth, it is geared towards spotting larger objects — between 100 metres and a kilometre in size.

"Objects like that are nearly impossible to see until a day or two before impact," says Timothy Spahr, director of the Minor Planet Center in Cambridge, Massachusetts, which tracks asteroids and small bodies. So far as he knows, he says, his centre also failed to spot the approaching rock.

The meteoroid itself was probably made of rock, but may have also contained nickel and iron. Campbell-Brown says that it was likely to have come from the asteroid belt, a region containing hundreds of thousands of rocky bodies and located between Mars and Jupiter. The European Space Agency does not think that the meteor is related to a much larger asteroid known as 2012 DA14, which will be passing within about 20,000 kilometres of Earth later today. Both the timing of the meteor's appearance and its location indicate that it came from a different direction, Klinkrad says. Campbell-Brown agrees: "We happened to have close approaches to two of them, and one of them got us," she says.


Although there are reports of fragments of the meteor, or meteorites, striking the ground, Klinkrad says that he believes the vast majority of damage in the region was caused by shockwaves of the explosion, as the rock broke up in the upper atmosphere. Campbell-Brown says that the infrasound data shows a very shallow angle of approach — a feature that funnelled much of the energy from the blast to the city below. Still, she adds, "It's lucky that there wasn't more damage."

The infrasound stations belonged to the Comprehensive Test Ban Treaty Organization, an international body that is designed to watch the Earth for nuclear-weapons tests. It is unlikely to be the only source of data on the strike. Both the United States and Russia have satellites in geosynchronous orbit that watch for the heat signatures of missile launches and warhead re-entries. The US military has released data on meteor strikes in the past, but it is unclear whether they will do so for today's event.

Klinkrad says it would have been hard to give warning of the blast. In addition to being relatively small in size, the rocky meteoroid was probably dark in colour, making it even harder to spot against the backdrop of space.  "We just have to live with it," he says.

Journal name:



An earlier version of this article estimated the mass of the meteor at around 40 tonnes.


  1. Report this comment | #55254

    Chris Jefferies said:

    It seems to me that this may have been two objects travelling in closely parallel trajectories. The videos and images of the trail suggest this.

    Has anyone else considered this possibility? A single object could have broken apart before or soon after entering the atmosphere.

  2. Report this comment | #55255

    Chris Jefferies said:

    It seems to me that this may have been two objects travelling in closely parallel trajectories. The videos and images of the trail suggest this.

    Has anyone else considered this possibility? A single object could have broken apart before or soon after entering the atmosphere.

  3. Report this comment | #55259

    Jarmo Korteniemi said:

    If the original mass is ~40 tonnes as calculated here, then the title is totally incorrect. Please check your facts. About 30 tonnes of material was collected from the Sikhote-Alin event, and estimates are around 70 tonnes for total survived material 1. This puts the original mass of that body around 100 tonnes...

    1 Norton and Chitwood, Field Guide to Meteors and Meteorites, Springer-Verlag, 2008.

  4. Report this comment | #55260

    Kostas Gourgouliatos said:

    " 15 metres across when it entered the atmosphere, and put its mass at around 40 tonnes"

    This gives a density of ~0.02 g/cm^3, isn't it too small?

  5. Report this comment | #55261

    Kevin Fox said:

    Yes, the numbers don't add up. A rock with twice the density of water and 15 meters across would have a mass of 2702 metric tonnes, not 40.

    Perhaps the scientist meant to say it had a destructive force of 40 kilotons?

  6. Report this comment | #55262

    Ananyo Bhattacharya said:

    Thanks for your comments. Geoff's the expert on this but Nasa has now confirmed this was the biggest event since Tunguska. I believe the issue is that mass figure is more variable in the initial estimates. We'll update the story as soon as we can.
    Nasa on twitter: @NASA #RussianMeteor is largest reported meteor since Tunguska event. Impact was at 3:20:26 UTC. Still being measured. More info to come.

  7. Report this comment | #55266

    Geoffrey Brumfiel said:

    Thanks readers, for spotting the mass issue. Campbell-Brown has revised her calculations and now puts her estimate at more like 7,000 tonnes.

  8. Report this comment | #55268

    Ruth Kletnick said:

    Last night, a glass on a counter in my bathroom in New Hampshire, US, shattered spontaneously and seemingly, without any physical cause. I looked up the time difference between Chelyabinsk and my home, and the glass shattered at almost exactly the same time that the meteor hit. Has anyone heard of anything else like this happening? I know there was no other possible physical cause.

  9. Report this comment | #55269

    Jarmo Korteniemi said:

    It still says Chelyabinsk "is largest after Tunguska". It is not. Sikhote-Alin, 1947, several times larger.

  10. Report this comment | #55275

    yousaf butt said:

    Geoff: was the mass/size arrived at by infrasound or by NASA measurements?

  11. Report this comment | #55277

    Geoffrey Brumfiel said:

    Hi Yousaf, the mass and size in my story were from the infrasound measurements, but NASA has since confirmed similar figures: Jarmo, note that NASA also calls this the largest recorded event since Tunguska.

  12. Report this comment | #55278

    Mark Leaver said:

    will there, search apophis red meteor 2029 and 2036

  13. Report this comment | #55279

    Jarmo Korteniemi said:

    Geoffrey: I do not see how "NASA calls it something" is a valid argument in science, or in science journalism. Just do the math and research yourself. "7 metric tonnes" < "23 or 70 tons"* by any definition. And this results in larger energy of the latter, thus being a larger event.
    *This is the oldest reference I could find on the subject:

  14. Report this comment | #55288

    Lalit Patel said:

    The asteroid 2012 DA14 was expected to pass above Indian Ocean on 14 February 2013. The meteor, which fell in Russia on 13 February 2013, was not expected. Most scientists have expressed that the befallen meteor was not related to the expected asteroid and it was only a coincidence that these two events happened almost concurrently.
    If the expected asteroid 2012 DA14 were not same as the meteor fallen in Russia, scientists would have observed the asteroid somewhere nearby its expected location sometime on its expected day. However, there was no solid observation of such an event. If the meteor fallen in Russia were not same as the expected asteroid, scientists would have observed the meteor long before its falling. However, there was no observation of such an event. Based on this, it is reasonable to conjecture that the befallen meteor is same as the expected asteroid.
    The asteroid 2012 DA14 was expected to travel from north to south. The befallen meteor traveled from south to north. Based on this difference in their directions, scientists have ruled out any relation between the two. However, as explained below, this difference in their directions does not prove that they are different objects.
    Even though the asteroid was tiny and moving at a great speed, the gravitational force between the Earth and the asteroid can change the asteroid’s trajectory. The probability of such a change in the asteroid’s trajectory can be quite significant. It is likely that the duration and magnitude of such a change were too small to be picked up by today’s computational resources.
    It is possible that when the asteroid entered into the Earth’s vicinity, it got a sudden gyroscopic deflection by the Earth’s rotation and its speed. This gyroscopic deflection changed its direction, as observed in the befallen meteor.
    Because of this change in direction, the asteroid got a great frictional resistance as it moved further into the Earth’s vicinity. This friction chipped off its outer layers and reduced its size and mass. This explains why the befallen meteor was smaller than the expected asteroid.
    It was possible for the asteroid to carry some electrically charged layer and a resultant magnetism. This magnetism and the Earth’s magnetism could have created an attractive force, in addition to the gravitational drift.
    Based on this, it is logical to state that the meteor fallen in Russia was same as and/or a byproduct of the expected asteroid 2012 DA14.

  15. Report this comment | #55292

    James Dwyer said:

    Lalit Patel – I generally agree, even if no causal relationship can be definitively established.
    As I understand, if events of magnitude similar to the Russian impactor occur at an average frequency of every fifty years, for example, and its assumed that proximal flybys of objects like 2012 DA14 occur every 10 years (we have no extended history of detecting such events), then the probability of two such events randomly, independently occurring within a single 24 hour period would be something on the order of 1/(36500*3650). The independent, coincidental occurrence of two such events would be extremely improbable.

    However, if the two events are casually related, then the probability of two dependent objects entering Earth's space on the same day is much greater. For this reason alone, without understanding exactly how the appearance of these two objects might be causally related, there's sufficient justification for intense investigations to consider how they could have been related. This would mean that the occurrence of multiple potential impactors in Earth's space might be more common than currently thought since historically, objects that did not impact the Earth were almost always undetected.

    The possibility that the recent asteroids were related was summarily dismissed (probably in part out of concern for Chicken Little) on the rationalization that 2012 DA14 was approaching Earth from the Southern hemisphere while the Russian impactor was observed to enter Earth's atmosphere in Northern latitudes, apparently headed in a southern direction. I also suspect that a southernly approach to Earth for the Russian impactor can't be precluded on that evidence alone, since its terminal oblique trajectory was largely determined by Earth's gravitation.

    Unless the Russian impactor's approach to Earth can be definitively reconstructed, I don't think it can be determined that the two asteroids' nearly simultaneous appearance in Earth space was unrelated, that there was no interaction between the two objects that produced the Earth impact event.

  16. Report this comment | #55294

    Hop David said:

    Jarmo, the corrected article does not say 7000 kg, it says 7000 tonnes. 7000 > 23 or 70.

  17. Report this comment | #55296

    Shirt Flash said:
    "In Soviet Russia, Space Explores You!"


  18. Report this comment | #55297

    yousaf butt said:

    Geoff: yes, I saw that NASA mentions a 15m figure and 7000 ton mass, but do you know — or could you kindly check with them — that NASA independently confirms these numbers, or is NASA repeating them?

    Does NASA, e.g. have independent optical or radar measurements?

    Secondly, could you please get some error values on the 15m and 7000t numbers from the infrasound folks? What are +/- values here?

    Thank you, Yousaf

  19. Report this comment | #55298

    yousaf butt said:

    Geoff: I see NASA is mentioning that infrasound people revised the numbers up a bit, (17m, 10,000t) but it still appears NASA is simply echoing infrasound folks' data — and it would be good to know error limits on this. Thank you for your reporting.

  20. Report this comment | #55304

    Kimberley M said:

    "Explosion rivalled nuclear blast, but rock was still too small for advance-warning networks to spot." Does anyone else find it interesting that this object hit in Chelyabink Russia – and area with multiple nuclear sites and disasters over the years? Could it be more that coincidence? I would love to see some investigative reporting – take a look at these sites and references:!/2012/10/lake-karachay-mayak-and-chelyabinsk-40.html
    chelyabinsk – 40

  21. Report this comment | #55306

    Ivan G said:

    I would like to note that the Youtube video features some very obscene words which you will never hear on russian TV or in a scientific conversation. It is funny to hear them in the video at Nature News.

  22. Report this comment | #55322

    James Dwyer said:

    Kimberley M -
    Regarding the coincidence that the three larges asteroid impacts of the past ~century have occurred in, specifically Siberia, there is the coincidental presence of a massive flood basalt flow deposited by the Siberian Traps eruption. More likely though, is simply the probability that (at least in the past) detected explosive impacts were more likely to occur, be witnessed and leave historical evidence over large terrestrial expanses. Perhaps increased monitoring will allow future detections over oceans and polar caps and other remote areas as well.

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