Reconstructing the Chelyabinsk meteor’s path, with Google Earth, YouTube and high-school math

Like many others, I was absolutely astounded by the meteor strike over Chelyabinsk when I woke on Friday morning. One silver lining to our self-surveilling society is that an event of this magnitude is certain to get caught on the myriad of always-on dash- and webcams. I for one could not get enough of the videos.

Might it be possible to use this viral footage with Google Earth to have an initial go at mapping the meteorite’s trajectory? I was pondering this question some 2,500km away from Chelyabinsk when I chanced upon this video:

That place is easy to find — it’s Revolution Square at the absolute center of Chelyabinsk, looking almost directly south. It is also easy to measure — the distance between the two central light poles is 32 meters, as per a quick measurement in Google Earth, while the five lanes of traffic going right to left (west to east) measure 19 meters. From this it is easy to estimate the height of the light poles to be around 12 meters — an estimate corroborated by numerous panoramas in Google Earth showing people next to these lamp posts, giving us added data points.

Using all this information, I was able to do some image analysis in Photoshop on the lengths and angles of the shadows as the meteor streaked across the sky. Here’s an animated gif showing the result of that:

gif-animation-small

The ensuing grade-school mathematics (SOHCAHTOA!) resulted in three lines of sight at three instants a few seconds apart. (For the sake of the record, I roughly calculated them to be towards 122 degrees at an inclination of 33 degrees at 9:20:28.7, towards 187 degrees at an inclination of 40 degrees at 9:20:32.2, and towards 222 degrees at an inclination of 32 degrees at 9:20:33.4. These times are the video’s own timeline, though they appear to correlate closely with the timelines of other videos.)

This allowed me to draw an inclined plane in Google Earth that should include the meteor’s path, though it does not allow me to know the distance of the meteor from central Chelyabinsk, nor its speed.

meteorgeview

However, we have more clues. We know a fragment of the meteor landed in Lake Chebarkul, roughly 70km WSW of Chelyabinsk. Gratifyingly, the inclined plane generated from the above video intersects with the crash site. Also useful was the estimate by the Russian Academy of Sciences that the meteorite hit the Earth’s atmosphere at around 50,000 km/h, shattering at an altitude of 30-50km. If that was the rough speed of the meteor as it burned up in the video, then the 4.7 seconds between the first and last shadow measurements would have seen it travel 65 km. Fitting a 65km line between these two lines of sight allows us to draw a straight line path for the meteor towards the crash site, with the first measured time yielding a height of 29km, which is the moment the meteor first brightened enough to give a clear shadow.

Download the visualizations for this as a KMZ file to open in Google Earth. Do play with the opacity slider of the overlay to check the alignments yourself — it’s most of the fun.

Screen Shot 2013-02-16 at 16 Feb 02.07.21 CET

How does this data square with the Meteosat 9 image that has being doing the rounds? At first glance, not well: Overlaying the image in Google Earth and aligning the border with Kazakhstan shows a 240km contrail that appears to end some 75km to the ENE of Chelyabinsk, even though the path when traced on the ground also leads directly to Lake Chebarkul.

At first, I thought the image might have been taken 5 minutes earlier, before the meteor streaked straight across Chelyabinsk proper, because the image’s metadata gives us a time of 3:15:00Z, or UTC, which is 6 hours behind Chelyabinsk time. But no meteor is going to take 5 minutes to traverse 75km, so we’ll just have to live with the time discrepancy. Webcams are not atomic clocks.

Much more interesting is the fact that if you look at the position of Meteosat 9, which is in a geostationary orbit, you see that Chelyabinsk is near the horizon of its view of Earth. This leads to extreme foreshortening in the snapshot of the meteor’s contrail:

Meteor vapour trail, 15th Feb 2013
(Notice the outline of the Sea of Azov in the foreground. Here is another version showing the thermal impact (source).)

The version used in the overlay is an enhanced view of this image, taken from the same angle. (The blacked-out upper right-hand corner of the overlay is behind the horizon as seen from Meteosat 9.). If you simulate this view of Chelyabinsk in Google Earth, you see that in fact, the contrail aligns quite nicely over Chelyabinsk considering that it would be 30km high and at such an extreme angle over the horizon. So the 4.7 seconds of maximal brightness (with contrail) do get to happen just south of Chelyabinsk proper, as per the above video, and without contradiction by Meteosat 9.

I feel this post would not be complete without some big caveats: I am not a trained scientist; I don’t know if meteors travel through the atmosphere in straight lines or at constant speeds (I assume they don’t, but that it doesn’t matter for back-of-the-envelope type calculations). Still, it is satisfying to know that with judicious use of Google Earth, YouTube and Photoshop you can get quite far in the meteor simulation game. I can’t wait to see what the professionals come up with.

UPDATE 2013-02-16: Via SebastienP in the comments comes another triangulation, comparing the calculated path from the KMZ file with the view from another dash cam. It holds up pretty well!

stefangeensreconstituti

(Source)

UPDATE 2013-02-17: In this comment, some smart calculations by Sean Mac are confirmed by a video he’s found showing the contrail crossing almost exactly above the southern suburb of Yemanzhelinsk. I found the exact vantage point of the video he references in Google Earth by connecting this Panoramio photo to this view in the video.

This suggests the meteor’s trajectory towards Earth was higher and steeper along the inclined plane of sight derived from the central Chelyabinsk vantage point than the initial calculation suggested. That’s not surprising, as that calculation was based on an initial estimate of the velocity by the Russian Academy of Sciences, which now appears to have been on the low side.

I’ve now added a second path for the meteor in Google Earth, together with the location of the vantage point in Yemanzhelinsk, in this KMZ file. Open it as a complement to the first KMZ file to see what I would consider to be an upper bound (green) for the trajectory along the same inclined plane, with a new likeliest path (red).

latestredline

“Looking up” in Google Earth from the vantage point in Yemanzhelinsk (I can because I have a 3D mouse from 3DConnexion), I get a very similar angle of view of the contrail when framed by the NNW axis of the buildings on that square.

abovehead

A further video showing the perspective from the town of Korkino further north (included in the new KMZ file) shows that the meteor passed a little to the south of there, allowing for a pretty accurate triangulation. (Thanks to Robin Whittle and liilliil in the comments for the heads up.)

UPDATE 2013-02-22: OK, so this is kind of special: An astrophysics paper has just been submitted to ArXiv.org that models the orbit of the Chelyabinsk meteor, referencing this blog post as a starting point: A preliminary reconstruction of the orbit of the Chelyabinsk Meteoroid by Jorge I. Zuluagaa and Ignacio Ferrin. Details are here, and here comes the resulting animation:

336 thoughts on “Reconstructing the Chelyabinsk meteor’s path, with Google Earth, YouTube and high-school math

  1. Meteors travel through the atmosphere like any other thing entering or reentering the atmosphere, on a parabolic arc. Ignoring the air, it’d be simply ballistics, but the air slows the object in a non-linear manner, due to increasing density of the atmosphere as it comes down and slows down.
    But, as you said, for a quick back of the envelope calculation, it’s quite close enough for government work. ;)

    You also made one assumption, that the impact site was the path of the meteor. Not exactly, one fragment landed there, others may have traveled less or further, they’re fragments as it disintegrated and made rude noises that blew window frames in, broke glass, collapsed one factory roof and pushed in part of that factory’s wall.

    Here’s one to bake your noodle. A few minute either way, earlier or later in our mutual orbits, it’d have been a fireball that went back into space again or a city crushing repeat of the Tunguska event- over a populate area.

    BTW, good job watching the shadows. Not many do that simple trick to establish path.

    Here’s another rough estimate, around 1.0 to 1.2 psi overpressure was experienced in the city that suffered damage, I’m thinking on the high side, as window frames were blown in and not only did a factory roof collapse, but part of the wall near the roof was pushed in.
    That’s a LOT of energy being put out at 30-50km up!

    • wzrd1 on February 16, 2013 at 03:44 said:
      “Meteors travel through the atmosphere like any other thing entering or reentering the atmosphere, on a parabolic arc.”

      Since a large meteor would be only slightly slowed by the air, it would follow a HYPERBOLIC arc.

      • Not really sure on that one, though air braking is variable, depending on altitude/density, gravity is still curving its path.

      • If you ignore air resistance, _and_ assume the earth is flat and gravity constant (doesn’t decrease with height), then the path is parabolic. If you assume a round earth with gravity pointing towards the center and decreasing with square of distance from center, then it’s either elliptical or parabolic, depending on whether total energy (kinetic+potential) is negative or positive.

    • Sometime after 10PM EST, Feb 14, Philadelphia, PA, my Mother who is 91 and hard of hearing, came in from outside and asked me what all the noise was? She asked me if I dropped something big. I hear everything in our neighborhood, but I didn’t hear anything (I didn’t feel anything either.)

      Is it possible, she felt a sonic boom from the Chelyabinsk meteoroid?

    • Great job on triangulating the path! ( Have you looked at the Zapruder film? ;)
      On another forum, I was involved in a discussion of the energy release, as compared to an explosion. My guess is it was nearly a megaton, based just on a >2 psi shock front.

      Blast effects have been extensively studied ( our tax dollars at work ). See, for instance

      http://www.fourmilab.ch/etexts/www/effects/eonw_3.pdf

      Focussing and local merging of shock waves leads to localized effect, which complicates the “yield” estimates – there is talk of longer range effects resulting from high altitude air bursts and passing the shock through the jet stream. (p.94)

    • The damage of zinc plant and opposite window across the street in dye-fab looks like affected by “ray of death”.
      Never clouse up around have no destructions or window breakings.

      • The meteor came in at velocities that are hypersonic. It was still supersonic during the video. That places the sonic boom behind the fireball and meteor and the shock front of the meteor from super compressed air, plus turbulence and massive deceleration while entering the denser stratosphere to cause unimaginable stresses on the meteor.
        Those stresses finally reached the point that overcame the molecular forces holding the meteor together. Once it fractured in the largest release of energy and small particles flying into the plasma of the fireball and brightening it, the remainder of larger pieces would, already being overstressed as well, also fracture.
        Until, it was largely rubble, which would be much more easily slowed by air, lacking the incredible mass of the original full meteor and fall to the ground in a debris field many miles wide and long.
        At the altitude and angle, it probably was still moving at mach 20-25 when it finally reached the point that it lost integrity and began to disintegrate.

  2. Pingback: Eksplozija meteoroida nad Rusijo | Bojan Ambrožič

  3. After making the measurements on GE thanks to your model and the photomontage I made, I found out the Fire tunnel was roughly 1200m wide at an altitude of 17000m. o_O

    • Based on the time difference (90s), the explosion is about 30.6 km away from the camera. Looking at the shadows, the meteor doesn’t explode directly above (almost).

      • The sound was not an explosion, but a sonic boom, so it doesn’t necessarily connect with the brightest part of the path.

        • Actually, it was an explosion. A simple sonic boom wouldn’t have traveled as far and as destructively.
          Overcoming the binding energy of the object requires significant energy and significant energy is hence released when it finally fractures. Smaller debris would then shoot outward into the plasma shock front created by its high velocity passage through every thicker air and flare brightly when entering that plasma sheath and vaporize smaller fragments. Larger fragments then create their own contrail and fireball and begin to fragment as well.
          Hence, the additional reports from smaller fragments also fragmenting until the fragments were small and light enough to be easily slowed by subsonic passage through the atmosphere to eventually fall to Earth.

          Take a large rock and keep hitting it with a sledgehammer. Now, think of that loud crack when the rock finally fails structurally. Scale that upward, add in reflection of the energy by the shock front of the leading edge of the fireball and reflection from the trailing sonic boom shock front, you end up with a directional reflector of variable geometry, depending on velocity and atmospheric density.

          • Multiple “explosions” (rock collapsing under pressure) + multiple sonicboom/shockwave sounds looks to fit the pic/video I have seen.
            Interesting one pic below:
            http://www.flickr.com/x/t/0096009/photos/93249543@N04/8475399871/
            Shows fireball period in trail – but it remains basically within its own path – can see some expansion of the trail but still mostly in one direction – but it did not just explode in all directions like one might expect from say a bomb. So some combination of explosions/boom/shock would be my guess.

          • Also thinking of the devices used to record the event most probably use “automatic recording level” (ie they adjust the recording level to the average of the surrounding sound) to get good sound without distortion. Which does the trick in most normal circumstances but does not react well to very sudden increases in sound. Typically the very first part of the loud noise will be distorted while the levels are adjusted. I think that might impact a little on these recordings of the sonicboom/explosions/shockwave too. That plus the rock(s) are moving and breaking up at 40x the speed of sound.

          • Actually, it’s more than that, Gary. Consider small fragments flying out into the plasma sheaf that is surrounding the meteor.
            They’d rapidly vaporize, larger fragments shattering nearly instantly.
            Not true explosions in a classic sense, but not sonic booms precisely. It’s partially an instant vaporization, piercing the sonic boom shockwave, partially being reflected by it and ducted between the training sonic boom wave and the primary shock front caused by the intense air compression at the front of the fireball proper.
            There are quite a few things going on, all nearly instantly.
            So, in essence, you’re right, it’s a combination of explosions (vaporization events from entering the plasma sheaf), shock front at the front of the fireball from the meteor compressing the atmosphere and the trailing sonic boom. When the object finally drops below the velocity of sound, the sonic boom would have advanced, been close to the meteor itself, creating even greater stresses on it, then as it further slowed to subsonic, the sonic boom would disappear.
            Shortly after that, adiabatic heating of the air would quickly cease and only pressure from subsonic, but still high velocity flow of air would be effecting the remnants of the meteor, plus of course, gravity and eventually, it’d be at terminal velocity.
            Something still significant, considering the Hodges meteorite, which was grapefruit sized, crashing through a roof and ceiling, bouncing off of an old wooden radio, to strike a woman, bruising one side of her body. With such a great mass of 5.56kg.

  4. Pingback: Meteor nad Czelabińskiem – analiza toru lotu za pomocą Google Earth, YouTube i podstawowej matematyki. « NOWGIS

  5. Cool work Stefan. All those different pictures and videos catching that fireball.. it’s nice living in the future, isn’t it?

  6. Pingback: Briefly | Stats Chat

  7. Pingback: The whole asteroid thing! « Dr. Erika Grundstrom

  8. Nice work… I did a very similar analysis with time stamped footage from another traffic camera in Chelyabinsk. What was unique about the footage I used was that it was a video lasting ~6Mins… I was able to calculated the slope of shadows (much like you, using the 3,4,5 principle of right triangles). The First light of the video cast a shadow at the 46 second mark of the video at a slope of 1.4 the peak light intensity occurred 4 seconds later at a slope of 1.333 (which I assumed was the detonation point). 160 seconds later the shock wave hit the camera (i know this because the video captured a cars alarm going off).

    Knowns:

    Slope of peak light intensity (1.333)
    Shock wave to vantage point (160 Seconds)
    Speed of sound (1,126 ft/s)

    160×1,1126= 180,160/5,280= 34.12 (slope) Miles from vantage point to detonation point.

    34.12 miles / 1.333 = 25.6 Mile (Run) ground distance

    Using the 3,4,5 principal I could calculate that the height of the meteorite at explosion was ~20.5 Miles

    based on all that I could make this statement…

    The meteorite exploded 25.6 Miles SSW of Chelyabinsk at an altitude of 20.5 Miles. This would put the detonation point relative to the ground ~ 1.5 miles NE of of Yemanzhelinsk.

    To confirm I wasn’t way off on my calculations I searched youtube for “yemanzhelinsk meteor” and found this.

    Video confirms the epicenter was slightly NE of Yemanzhelinsk.

    Here’s an image of the video analysis that I used.

    https://dl.dropbox.com/u/472582/chelscreenshot.jpeg

    Just an FYI… you can calculate the speed of the meteor in your analysis by using the videos time stamp and the apex of the rises of your triangles.

    knowns:

    x= time stamp of triangle1
    y= time stamp of triangle 2
    z= distance between apex of triangle1 and triangle2

    velocity of meteor= z/(y-x)

    do the same with the time between triangle2 and triangle3 and you’ll be able to calculate the rate at witch the meteor was slowing down in the atmosphere…

    How did you plot your point on google earth???? That’s pretty cool.

    Nice to know i’m not the only nerd in the world!

    • Nice work! Re calculating the speed from the distance in my example, that would be a bit circular in that I was only able to come up with a distance based on a given speed (from news reports). Should the speed prove slower, then, the meteors path will have been closer to the ground along the inclined plane, and along a shallower angle.

      • 48KM South of Revolution Square is too far South — that would place the contrail south of Yemanzhelinsk, which we know from videos it is not. If the meteor passed between Yemanzhelinsk and Korkino (as per the red line) then the distance south of Rev Square was 36km. With the angle of view from Revolution Square straight south established at 40 degrees (in the article above) then the height of the meteor at the time (which is also near when it was at its brightest) would be around 28km.

        • In Emanzh glasses of window weren’t breaking down. As like in Epi of nuc.
          But in Korkino – yeeehhh.
          Here the wave of explosion is llayed flatling.
          The most breaked town is Korkino.

    • actually, the speed of sound is slower at high altitude:
      330m/s at sea level, 0 Celsius
      295m/s between 12,000 and 20,000 m altitude (takes into account atmospheric variations of temp, humidity (i.e. density), if you re an experienced pilot you know that mach1 is slower ‘up there’ than ‘down here’ when looking at speed over ground).

      that’s a 10% variation, so the meteorite was probably blasting more around 17,000 to 18,000 meters than 20,000 (the curve speed of sound vs altitude is not linear)

  9. Pingback: Live-Blog zum nahen Erdbesuch von 2012 DA14 « Skyweek Zwei Punkt Null

  10. If this little-watched video is from Korkino, as noted by liilliil

    http://www.youtube.com/watch?v=odKjwrjIM-k

    near Rosa/Rosa, then the path or the meteor was slightly to the south of there. Likewise this one from Rosa/Roza:

    http://www.youtube.com/watch?v=Mwieex7gFAs

    ~23km south of Chelyabinsk. This shows the path of the meteor being a few km to the south.

    With some knowledge of shock wave propagation speeds at various altitudes, it should be possible to calculate the altitude and velocity of the meteor at this point.

    Another little-watched video with the smoke trail almost overhead:

    http://www.youtube.com/watch?v=64gXz9W2oyQ

    This is supposedly from Emanzhelinsk / Yemanzhelinsk, which is further south still. I think this shows the smoke trail to be somewhat to the north, with the initial view of the trail being at the western end.

    This would enable the track of the meteor to be located just a few km north of this location, somewhere between Korkino or Roza and Emanzhelinsk / Yemanzhelinsk.

  11. Pingback: Internet, video, trigonometria e mappe

  12. You’re working with video that has defined and known frame rate. This means that you could actually find out the speed of the meteor.

    • Only if we know the distance, which we now do (see the update that I *just* published a moment ago.) But I need some sleep so perhaps I will leave it for an enterprising commenter:-)

  13. OK, let’s say you are able to figure out all the dynamics of this meteor strike, and let’s give you the stats on the next 1000 meteors after the fact as well. Think you could tell me which direction number 1002 will be coming from? We are nothing more then a moving target in a shooting gallery. Point is; enjoy life today, as tomorrow is just as uncertain as it was for the caveman.

  14. Speed of sound is dependent on temperature and as ambient temperature was below zero and temperature drops even more with height, the average speed of sound was around 300 m/s.
    From liilliil’s video it’s possibe to calculate distance of the meteore above the town where the video was taken. It took ~90 seconds to travel for the sound boom and it is pretty clear, that the nearest distance at that point was ~27000 m. This corresponds to the fact, that atmospheric density starts to grow rapidly below 30 km and that was the reason why the meteore expoded.

  15. It is pretty obvious, that the main piece did not fall into Chebarkul.
    The opening in the ice cover was too small. The impact velocity was not so high, possibly as low as 400…500 km/h, but mass of the piece had to be way below 1000 kg. Otherwise the ice opening was much larger.

  16. Most possibly major part of the debris flew up to tens of kilometres ahead and the piece that fell into Chebarkul lake was only relatively small piece that was deviated from its course by the explosion. And it disintegrated even more due to impact and thermal shock when fell into cold water. So it is pretty hard to find some residues from the bottom mud.
    As fields in the area are covered by snow, it is pretty hard to find small impact traces of other pieces. If the meteorites have high metal content, then metal detectors could help to find debris.
    Population density of the landing zone seems to be very low, so it is almost impossible, that somebody will find some debris by chance soon.
    It seems that the rescue teams are searching in wrong areas because the correct route of the meteor is possibly not fixed yet. I have heard of 3 found impact zones, but the on in Chebarkul lake is the only published so far.

  17. Bolshoi Sarykul (Сарыкуль) – (Big) Yellow Lake.
    Sokolovo – Falcon (joke New Skolkovo)
    Posev (посев) – seeding of meteor parts
    Рикошет и Взрыв – Ricochet n Explosion
    излёт после рикошета – spent part afier ricochet

  18. Pingback: Meteoriteneinschlag in Tscheljabinsk - Seite 3

  19. You missing the fact that meteors path crosses the stright view of the video from Korkino, linked by liilliil

    Your path is pretty much parallel to the camera view.

    I think the meteor flew directy above the lake that is 2 km SE from Korkino. And explosion took place just above the lake.

    • Where is this exactly?
      that remains to be seen.

      Im operating by videoclips with precision location on the map of city – crossroad, buolding.

        • Thanks for that. I just checked the alignment in Google Earth with the existing red-line path and the angle corresponds very well. I’ll update KMZ file to reflect the more accurate location in Korkino shortly.

  20. Amazing work!
    Thank you for sharing
    something fell along the line after an explosion on a ballistic trajectory
    The lake is not the end point and the direction, azimuth.

  21. Pingback: Оцифровка метеора | Lifehack.ru

  22. landed in Lake Chebarkul hoax have stated, the hole came for other reasons, and it was already announced that the meteorite was probably south of it at a considerable distance

    • Looking at the light pole shadow, you can tell that the meteor travelled a little to the south of this location in Korkino, and elsewhere we know it travelled to the north of Yemanzhelinsk; Combine this with the view from RevolutionSquare and we pretty much fixes a point in space where we can tell the meteor was. Then, looking at the angle of the trajectory when looking up in the video at Yemanzhelinsk, we have a good idea of the direction it was heading — towards lake Chebarkul. A smaller piece may have dropped in Lake Chebarkul or nothing at all, but I think we now have multiple corroborating calculations that show the meteor traveling towards it.

      • I realized.
        Exploded high, clearly in outline where and at what height, but after the explosion (the complete destruction of the falling object into fragments), then goes the free fall along a parabola, not a straight line. At the time of the explosion object loses kinetic energy, I think
        Do not want to believe that the object is completely destroyed, 10,000 tons of dust.
        Followed by painstaking work of scientists and searchers

  23. Look at this video, which is totally different from the other ones:
    http://www.youtube.com/watch?v=Z-BoS_YEhfg

    It was taken from Miass, abt. 90 km WSW of Chelyabinsk, or maybe 20 km west of Chebarkul, thus situated in the immediate direction of the meteorite path: it shows a white cloud, slowly billowing up (probably the impact site?) with a thin dark smoke trail leading towards it.

    • Very interesting. Here is my interpretation. The dark line is not a smoke trail but the shadow from the sun to the east. The cloud itself is seen almost head on — i.e. heavily foreshortened — with a slight direction down and a little to the left, pointing to a location ENE of the viewpoint. THe meteor contrail is thus pointing almost directly at the viewer, aiming ENE of the viewer. That would corroborate the other sightings. Thanks for the heads up.

  24. Hi Stefan & JEM, I compared your path with the direction of the trail as seen from the satellite. Something seems wrong, as satellite data shows a heading to the WSW, and the reconstruction so far points toward WNW, because it make the asteroid on a collision course to the lake. But now, it doesn’t make sens to follow this point. In fact the trajectory can become flat! See the pic here:
    http://img580.imageshack.us/img580/6145/cheliabinsk.jpg

    • Because Meteosat 9′s viewpoint is roughy aligned with the plane along which the meteor traveled, you can’t tell at what angle it was falling to Earth or if it was going parallel to Earth. However, other viewpoints on Earth do show the direction of the meteor (going WNW above Yemanzhelinsk as confirmed in this image http://ogleearth.com/wp-content/uploads/2013/02/abovehead.jpg), which allows us to deduce that the path was indeed aimed towards Earth.

      • You’re right Stefan. I checked with a 3D Model of the Earth+Satellite. A horizontal one looks the same than an oblique one. That’s good news for fragments.

  25. Pingback: Meteorite Fragments – Russia « Earth « Science Today: Breaking science news from around the world

    • Yeah, that was a very stupid news story. It’s obviously a man made hole, how could anyone think anything else? (Still, great analysis being made here! Of course it has to adapt to changing new information, but great work!)

      • So, a man made hole, mysteriously instantly appearing, per local fishermen, with stone fragments around the hole sitting on the ice (and slightly melted into the ice)?
        Sorry, but something the size of a bowling ball, traveling 300kph or more, will do interesting things. Especially if it’s still hot from passing through the plasma from the fireball.

  26. The piece that fell into the lake was rather small. Most of the hole in the ice is caused by the water vawes, that appear to be almost symmetric around smal falling object. As energy of the waves decreases symmetrically, therefore waves break symmetric hole up to the diameter where waves are not strong enought to break the ice.

    It is unthinkable, that someone was able to create manmade hoe this big during that short time. Even using a chainsaws it is impossibe.

    • Really? Would a meteor crashing through an icy lake really make a circular hole? And no cracks around it? I think fishermen saw such holes in the ice (the light gathers fish), and that one already existing was used as a hoax, or stupidly misunderstood.

      Sure, there’s ice thrown around, but maybe that is part of the process of sawing such fishing holes.

      • If you look at the thickness of the ice above the waterline and apply the iceberg rule, the ice must be around a metre thick (In the Great Patriotic War, the Soviets drove tanks across lake ice). Like a bullet going through a metal plate, the meteorite is going to leave a circular hole through deformation more than making cracks, I think.

        Also, if the ice is that thick, consider how long it’s going to take to excavate a hole several metres acrosss using only hand tools, and then distribute the cutout chunks around the hole to resemble ejecta.

        • I don’t think the ice is more than 20cm thick. In fact, it may be considerably less. Just look at those chunks of ice; they are rather small and look thin.

          Otherwise, I think it looks very natural, if you count as “natural” holes in ice made by falling space rocks. I’ve only seen holes made by high explosives and they sure are almost round just like this one.

      • Could the ice be so tick and the fragment so small but
        warm, that fragment actually “landed” on the ice without cracking
        it, but then it gradually warmed up ice and water until fragment
        fall down, continued warming up water and created the hole AFTER
        falling? Or do fragments arrive to surface already cold? (I guess
        it depends on mass and material). This would cause a hole without
        ejecta.

        • Fishermen said that they observed this moment: the stone
          broke the ice and caused large splash of water. Scientists also
          reported about clear signs of large directional splash of
          water.

        • No, to melt that much ice, the meteorite would have to be immense, especially if it somehow managed to land softly enough to not vaporize ice, but hot enough to melt through and heat an immense amount of water.

          Meteorite fragments were found all around the hole, amongst the ejecta of fist sized blocks of ice.
          Something the size of a bowling ball, impacting at 300 kph or greater would create just such a hole. The mass causing the ice to fail, the pressure wave of displaced water creating an ejecta spray around impact and whatever remained intact after impact would embed itself in the silt at the bottom of the lake.
          Once the ice melts, they’ll eventually find the fragment.

          • Why “immense”? It shouldn’t have to warm up whole lake, bringing water over 0°C for some minutes would have been enought to melt the ice just above the falling location.

            Anyway, now scientist suppose the fragment is around 200 kg, so it would have anyway caused a big hole, hot or cold!

            (this comment was posted by clicking REPLY directly at the bottom of the comment).

  27. Pingback: Disrupt « Stuff