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Meteor fireballs across central Russia

The views expressed are those of the author and are not necessarily those of Scientific American.

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Still image of fireball video (RT/Youtube/Potapow)

[Updated:] About 7,000 metric tons of meteor streaked across central Russia on Friday 15th February 2013, its fireball leaving great contrails in the sky and generating explosive shockwaves that smashed windows and damaged buildings. Reports indicate a number of craters a few meters across as the debris impacted the ground.

The Earth is constantly encountering chunks of solid material in the solar system. Typically the relative velocity of these encounters is between about 17 kilometers a second and 50 kilometers a second – in other words fast. Our atmosphere provides a roughly 60 mile barrier to these speedy pieces, and frictional and pressure forces generate high temperatures as material passes through it – probably reaching up to about 3,000 F (1,600 C), hot enough to melt and boil even rocky material.

We’re seeing this all the time. The streaks of pretty meteors (they’re not meteorites until they hit the ground) are usually very high altitude events and caused by tiny crumbs of matter. This stuff is part of the detritus of the solar system, the same material that once formed planets. It has a wide range of compositions. Some is iron-nickel rich, the exhumed pieces of what was once a planetary embryo some 4.5 billion years ago. Other pieces are even more primitive, the clumped splatters of minerals that have never formed part of anything bigger – unprocessed and primordial.

It all comes in every size imaginable, from microscopic grains to great big asteroids and cometary nuclei that may be miles across. But the bigger they are, the rarer they are and the less and less likely it is for their orbits to ever intersect with ours. It does happen though, and across Earth’s history we’ve been hit by some pretty serious stuff – ask the dinosaurs….oh wait, you can’t.

The trail of the meteor across the sky (Youtube/Gregor Grimm)

The event in the Chelyabinsk region of Russia is a spectacular example of what was probably a chunk of material just 15 meters across, perhaps weighing in at about 7,000 metric tons. Russian sources estimate that it had an initial velocity of about 30 kilometers a second and a low trajectory that carried it across a very significant area. It seems to have exploded into fragments at a few kilometers altitude and impacted the ground in a number of locations.

To quote the Russian English-language news channel RT: “Army units found three meteorite debris impact sites, two of which are in an area near Chebarkul Lake, west of Chelyabinsk. The third site was found some 80 kilometers further to the northwest, near the town of Zlatoust. One of the fragments that struck near Chebarkul left a crater six meters in diameter.” They also report that many hundreds of people have suffered injuries – presumably mainly from flying glass or debris due to the shockwaves.

The flash was reported in a huge area from the Chelyabinsk, Tyumen and Sverdlovsk regions, to Russia’s Republic of Bashkiria and in northern Kazakhstan.

My very crude estimate of the energy of the material pegs it at a couple hundred kilotons TNT equivalent before it hit the atmosphere. This could produce an airburst explosion of 70 kT, possibly more. [Update: this meteor likely produced about 100 times less explosive energy compared to what the fly-by asteroid 2012 DA14 - see below - would have caused if it impacted Earth - a few tens of kT versus about 3 mega-tons].

What's claimed to be a collapsed roof/wall of a local zinc factory - due to the meteor shockwave/explosion (Photo from user @TimurKhorev)

Image from Meteosat 10 of object soon after it entered the atmosphere above central Russia (Copyright 2013 © EUMETSAT)

What’s interesting, although almost certainly coincidental, is that a known asteroid – the object 2012 DA14 – is passing close to the Earth right now. It’s been the subject of a certain amount of media attention because it’s one of the closer passages of an object (about 46 meters across) at about 27,700 kilometers (17,000 miles) that we’ve been aware of.

However, 2012 DA14 is approaching Earth from the terrestrial south, while the Russian event was due to an object coming in from the north – so it’s highly unlikely that there is a physical relationship between these two things. In fact it just highlights the fact that this kind of meteor event is happening more often than we perhaps usually know. Seventy percent of the Earth’s surface is water and effectively uninhabited – there are likely plenty of meteors that are simply not witnessed or reported by anyone.

Caleb A. Scharf About the Author: Caleb Scharf is the director of Columbia University's multidisciplinary Astrobiology Center. He has worked in the fields of observational cosmology, X-ray astronomy, and more recently exoplanetary science. His books include Gravity's Engines (2012) and The Copernicus Complex (2014) (both from Scientific American / Farrar, Straus and Giroux.) Follow on Twitter @caleb_scharf.

The views expressed are those of the author and are not necessarily those of Scientific American.

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  1. 1. jtdwyer 1:48 pm 02/15/2013

    As I understand, the shock wave set off nuclear explosion detectors in Russia, so events of this magnitude aren’t likely to go undetected in large areas of the world, at least. Some have assessed this as the largest asteroid impact since Tunguska, making this a 100 year event. It’s difficult to assess the historical frequency of 2012 DA14 scale asteroid flybys, but it also seems to be a pretty rare event. If we assume this is two coincidental occurrences of 100 year events that are completely random and unrelated, wouldn’t the probability that they occur within a single 24 hour period be something on the order of 1/((365*100)^2)? If this is correct, wouldn’t such extreme coincidences argue for some direct causal relationship – even if that cause is indeterminable?

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  2. 2. Caleb A. Scharf in reply to Caleb A. Scharf 2:01 pm 02/15/2013

    I believe the difficulty arises in the post-hoc nature of the statistics. We are only aware of the one asteroid ‘near pass’ occurring in this 24 hour period – but 2012 DA14 is pretty close to the limits of what we can easily detect, in other words there may be many near passes occurring of smaller sized objects during this same period. The Russian impact is one of those unseen objects that *did* intercept Earth, hence we noticed it. To put it another way, if we’d *not* known about 2012 DA14 we’d simply put this morning’s meteor down to a ‘once every fifty years’ (or whatever) chance event.

    You’re correct about the test-ban detection equipment, so this was definitely a large impact that would have a chance of being detected anywhere.

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  3. 3. jtdwyer 3:43 pm 02/15/2013

    Yes – thanks for your consideration. However, the probabilities are assigned for events involving objects of this size – particularly the impactor, so that the frequency of smaller object appearances should not be involved. The main difficulty is assessing the probability of large object flybys, since almost none could have been detected in past years… If I simply assign a 10 year event frequency to the flyby and the impactor was a 100 year event, the probability of independent coincidence would still be 1/(36500*3650).

    Meanwhile, I think there is some potential that, for example, a single collision event or chain of higher velocity collisions in the asteroid belt, for example, could have simultaneously dislodged these two fairly large asteroids, potentially causing them to arrive at Earth at nearly the same time, even from different paths – correct?

    It is the coincidental timing of these two I think fairly large asteroids in Earth space at nearly the same time that seems to me to argue for a common causation. I’m more concerned that reportedly at least several scientists summarily dismissed all possibility that the two events are related. I do appreciate that ‘Chicken Little’ panic should be discouraged in the public’s interest… I guess the only real proof will be if there’s another large impact in the next several hours – thankfully, also a very unlikely event… Thanks!

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  4. 4. jtdwyer 4:05 pm 02/15/2013

    BTW, a “Nature News” commentator mentions “Sikhote-Alin”:
    “Sikhote-Alin is an iron meteorite that fell in 1947 on the Sikhote-Alin Mountains in eastern Siberia. Though large iron meteorite falls had been witnessed previously and fragments recovered, never before in recorded history had a fall of this magnitude been observed. An estimated 70 tonnes of material survived the fiery passage through the atmosphere and reached the Earth.”

    So today’s impact could be about a 50 year event, at least in Russia! Or maybe a 100,000 year event outside Russia! Perhaps its the massive flood basalts of the Siberian Traps – attracting meteorites…

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  5. 5. Caleb A. Scharf in reply to Caleb A. Scharf 4:54 pm 02/15/2013

    Re origin of the Russian meteoroid and 2012 DA14 – I believe the majority of Near Earth Objects are in long term helio-centric orbits (i.e. they’re not just zooming through), the issue is that the orbits are similar in distance from the sun to the Earth’s and so there is a tiny, but finite probability for close encounters or worse. So although 2012 DA14 was only discovered about a year ago it’s likely been orbiting for a long long time – even if originally it was from the asteroid belt. Chances seem good that the Russian meteoroid was of the same ilk, it just got unlucky this time!

    I agree that it feels like a coincidence, but I don’t think it is statistically significant – as I said, post hoc analyses are always tricky. If for example it had hit in the middle of the Pacific it would have been unlikely to be reported – even if detected by things like infrasound – and the numbers I’m seeing bandied around suggest that this size hit has an average rate of anywhere between a few months and a decade.

    Anyhow, I guess the ultimate test will be whether anything else comes to visit in the next few days/weeks!

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  6. 6. Witold 6:39 pm 02/15/2013

    Perhaps the DA14 asteroid, while approaching the Earth, had struck some of the bodies hovering in the so-called Lagrangian points of the Earth-Moon system (the Kordylewski cloud) and the Chelyabinsk meteor was on of the debris! The timing looks right for such an event if you consider the distance, the speed, and the Moon phase.

    Anyway, these two *similar* events must be related. Let’s assume, we are now able to predict a near asteroid passage every 10 years; then the probability of a coincidence with an experienced rare meteor impact would be only about 1/3650, or 0.03%

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