Did a skydiver see a meteoroid in flight?

A story surfaced over the last few days about a Norwegian skydiver who captured on film a rock flying by just after he deployed his parachute. Actually this happened about two years ago during which time some experts have been examining the evidence and have concluded that what he recorded was a falling meteoroid (it becomes a meteorite once it hits the ground)  I was very skeptical about this story and was waiting for the bad astronomer to debunk it but he failed to do so, so I will have to do it for myself. Update 7-4-2013: Phil Plait has now posted a more skeptical followup suggesting similar ideas as written here (and by others elsewhere) which I fully agree with.

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The first thing to think about is what are the chances of this happening? Records indicate that only one person has ever been hit by a meteorite. The person was a German boy who was hit by a pea sized meteorite. He was fine. There is also a story of a dog that was hit and vaporized but that story seems to be fake. In addition there are also a handful of cases  where cars have been hit by sizable meteorties. At least one, the Peeksill meteorite was verified.

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It could be that there are more unrecorded cases but we dont need precise numbers so let’s assume that as many as one car a year is actually hit by a sizable meteorite. There are about a billion cars in the world and most of them are outside exposed to the sky for most of the time. That is a lot of target space. On the other hand there are not too many active skydivers, maybe a hundred thousand at most doing on average a few jumps a year. Let’s be very optimistic and call it a million jumps where an event might have been recorded. A typical descent lasts about 5 minutes which is about a hundred thousandths of a year. You can work it our yourself, with these generous figures and the assumption that a car hit has a similar cross-section to the claimed event,  then we expect about one event like this every 100 million years. Yes, coincidences happen, but not something like that.

So what are the alternative theories. One possibility is a planned hoax. It would not be hard to put such a hoax together and there are plenty of hoaxes around, but the motivation to do an elaborate science hoax like this seems lacking. This is much more likely to be a hoax than a meteoroid but I dont think that is the best solution.

The most plausible explanation is the first thing that came into my mind and which others on slashdot have also suggested. It was a small stone that fell out of the parachute. Some people have disputed this because they say it was going too fast. In fact the estimated speed of the falling stone depends on its size or distance from the camera. The meteor experts estimated a large rock of a few kilograms travelling at 300 km/hr, but that is really based on the assumption that it is a meteoroid falling at terminal velocity. If it was a stone that fell out of a parachute it would have to be much smaller and slower and therefore nearer to the camera. This is equally consistent with what was recorded.

The object fell past about four seconds after the canopy opened. This is perfectly in line with expectations if it was on top of the parachute and bounced off. Is it possible for a skydiver to pack a stone in his parachute? Yes certainly as this video shows. A testimony from a skydiver on slashdot confirms that this happens. It is not common but it is common enough to expect someone to capture it on video sooner or later.

Update 8-4-2014: There is now an official explanation along the lines that the stone fell out as the parachute began to open and then passed the camera as the skydiver turned back a few seconds later. This is possible, as is my own similar explanation that it bounced off the top of the parachute and fell back a few seconds later.

Now everybody is saying that it is all fine and they knew all along that it might not have been a meteorite etc. Funny that the video and all the news reports made a very strong case for it being a meteorite and very few of us immediately noticed that this was very unlikely. That is the power of wishful thinking, confirmation bias and the persuasiveness of the authority of a qualified expert . If you were fooled, you will know to be more skeptical next time. In fact if you watch the video again you will see that they considered the possibility that it fell from the chute and that this was the one other possibility that they could not easily dismiss, but they did not say that outright. They just conveniently skipped over it and talked about other theories that could be more easily dismissed. The expert is also reported to have said that the chances of this happening are like winning the lottery three times in a row. That is about right and it is something that never happens but he did not seem to get that. Sometimes people’s desire to be involved in something special are just so strong that their powers of reason are put on hold.

Of course this does not mean that everything a scientist says can be dismissed. It means you have to listen to the reasoning rather than just the claim. It is not always possible to estimate the approximate probability for something being true as it was in this case and not everyone has the right kind of sense to make the right judgement. If that is you then you might want to take note of who quickly saw the truth in this story and who didn’t so you have a better idea of who to trust next time :-)

27 Responses to Did a skydiver see a meteoroid in flight?

  1. skyweek says:

    The “meteorite hits German boy” story actually was a hoax – but http://www.history.com/this-day-in-history/meteorite-strikes-alabama-woman is true.

    • Philip Gibbs says:

      Ok thanks, it is funny how that article says the Egyptian dog story is true, but that one seems unlikely according to other reports

  2. svik says:

    About as likely as the tricept results holding up. I mean bicepts.

    Must be a slow news day.

  3. Mark Thomas says:

    You would not be able to see a perceptual curve in the short space that the path shows in the picture if it had fallen from space. Also it looks so well framed and Hollywood clean.. Definitely fake.

    • Philip Gibbs says:

      The path on the photo may only appear curved because the camera was moving at a non-uniform rate (although a curved trajectory from the canopy would also explain it). That picture is very misleading. For another thing the stone came in view from the edge of the field of view at the point where the trail starts and the picture does not show that.

      Everything is fully consistent with the theory that it was a small stone that fell from the canopy and that is not a very improbable event. Some form of setup is possible too but I think less likely. All other theories are improbable and the meteoroid theory is by far the least probable, as you seem to agree.

      • Mark A. Thomas says:

        I should say that the stone from the canopy is the most likely scenario which has reasonable probability. Also, I should not have said it is a fake to lend some credence to the nice couple as they do seem sincere and amused about it. I would think that the camera is well coupled to the skydiver and that the perceptible curve is more likely due to the stone falling from the canopy. Meteors tend to travel faster than this unless there is a breakup from the atmosphere. Many things could be analysed here. This of course is all in the name of good fun. Apologies for calling it an assumed (well planned) fake. A few years ago there was a video of the Columbia Space Shuttle exploding in space for which I knew that many people believed to be actual footage. Number one it was very clear and set such that you had a perfect vantage point of the event. It was perfectly framed. The explosion was what you would expect from a Hollywood movie. Also, the sattelite or camera just happened to be there (maybe it was crazy military optics from thousands of miles away ;) ). I know a professor who believed the footage and he is actually a smart guy ;) ) If something on camera, video looks incredibly good in a very low probable event then it is more likely not be the event purported to be or something like that.

      • Philip Gibbs says:

        I think a hoax is plausible as a kind of social experiment. I.e. you present some carefully faked video evidence for a ridiculously unlikely event that average people find hard to judge the probability for. Then you get an expert scientist to declare that it must be the real thing and dismiss other more likely explanations without good explanation, providing no peer review for the analysis. Then you sit back to see who is taken in. I dont think that is what happened but it is much more likely than the meteoroid theory.

  4. Lubos Motl says:

    Hi Phil, good thoughts. How did you measure the distance of the stone, i.e. the required cross section? Couldn’t it have been 100 meters? That would increase the probability about 10,000 times, right?

    • Philip Gibbs says:

      Hi Lubos, I am considering the cross-section for what the expert scientist concluded, i.e. a distance of about 2 to 5 meters. If it was 100 meters it would have to be a very big rock travelling very fast and other evidence might be expected such as a very bright meteor flash, noise or ground crater. Also the increased cross-section might be cancelled by the lower flux for meteroids that big.

      Of course you could do a much more careful analysis using data for the flux of meteorites of different sizes and careful measurements from the video frames, but the probability is so ridiculously small that errors of a few orders of magnitude are not going to change the conclusion.

      • Lubos Motl says:

        Can these very small objects – 2-5 meters – get through the atmosphere at all? Just to be sure, I do think that you’re right it’s probably either a hoax or a stone from the parachute.

      • Philip Gibbs says:

        That’s an interesting question. It seems the largest known is the Hoba meteorite at 2.7×2.7×0.9 metres, so I suppose anything bigger gets broken up or vapourised at high altitude or on impact, not sure which.

      • Lubos Motl says:

        Oh really? My point was exactly the opposite one. If a meteoroid is too small, it always gets fully vaporized in the upper atmosphere, doesn’t it? It’s only large enough objects that make it to the surface, I thought.

      • Philip Gibbs says:

        We need an expert to explain but I think small meteoroids up to a few centimeters get vapourised at high altutude and larger ones are more likely to be broken up so that pieces over a metre hitting the ground are very rare

      • Lubos Motl says:

        BTW did you notice the cosmic ray hit at Mars?

        https://www.google.com/search?aq=f&hl=en&gl=us&tbm=nws&btnmeta_news_search=1&q=cosmic-ray+mars#gl=us&hl=en&q=cosmic-ray+mars&safe=off&tbm=nws&tbs=sbd:1

        It’s the UFO light bulb on the pictures. I thought that they originally meant that a cosmic ray caused the actual explosion in the landscape. ;-) But they really meant, as clear now, that the cosmic ray hit the sensitive pixels in the rover’s camera. It’s also pretty small – there must be lots of such rays on Mars, due to the thin atmosphere. I guess that it’s not healthy to be bombarded by it, and one gets more hits than the small array of the camera, so astronauts on Mars should better be protected a lot.

      • Philip Gibbs says:

        Yes I saw that. It was debunked more quickly because alien lights on Mars are a more obviously ridiculous idea, although the chances of such a thing may be higher than the chance of a skydiver’s camera seeing a meteoroid.

        I agree about the problems with trips to Mars. Radiation is already a big risk for the journey there. It makes much more sense to colonize the Moon first. Mars will be colonized by humans only after it is feasible to launch large spaceships from the moon I think. AI bots may be able to build a Mars base for us before we arrive. Of course there might be a suicide mission for reality TV much earlier but the astronaut’s horrible death should deter others.

  5. Philip Gibbs says:

    Note that Phil Plait now agrees with the stone-in-the-chute-theory as the most likely explanation

  6. […] praktisch tot, nachdem sich deren Kronzeuge der Stein-kam-aus-dem-Schirm-Erklärung (s.a. hier, hier und hier) de facto angeschlossen hat: Man glaubt gar nicht, was alles in Fallschirmen stecken […]

  7. skyweek says:

    In https://www.facebook.com/Philtill/posts/10203622350143366?comment_id=8406226&offset=0&total_comments=25 the key scientist of the it’s-a-meteorite faction reconsiders. Case more or less closed, I’d say …

  8. (From my interesting experience) if a meteoroid pass this close to you, you will smell it’s scent. It smell like burned metal, smell is similar to welding fumes. (Maybe we should ask parachute jumper: “Did you smell something different?”)

    About probability:
    probability is high enough (billions of small cameras) if you subtract parachute situation.

    My vote for explanation goes to ordinary rock (not meteoroid).

    • Philip Gibbs says:

      Oliver, everybody accepts the rock-in-the-parachute theory now. If you look through all the reports you will see that almost all blogs and media were confident that it was a meteorite until I posted my refutation. Then everyone started to change their minds.

      Those that thought about it dismissed the rock theory for two reasons. Firstly they could not understand the 4 second delay after the shoot opened before the rock fell. I pointed out that it could have bounced up from the top of the chute before falling back. Secondly they said the rock was too big to be in the chute. I pointed out that the estimate of the rock’s size was based on the assumption that it was a meteoroid at terminal velocity which would have to be far from the camera and therefore big. A rock from the chute would be smaller, nearer and slower. I don’t understand why so many people fell for this obviously circular reasoning. It was when I pointed out this error that some people started to come round.

      Before me, a few people had doubted the meteoroid theory for other reasons. They thought it should be glowing, or moving much faster, or that there should have been an obvious meteor trail in the sky. These things were wrong reasons to doubt the meteoroid theory. People who doubted mostly thought that the most likely alternative was a hoax. Your point about the smell is also not convincing. If a meteoroid fell next to you on the ground you might smell it but in the air it is moving fast and the skydiver was also moving fast even with his chute open. I think it would be unlikely that enough vapour from the meteoroid would reach his nose. Perhaps it is possible but we cannot use this argument to dismiss the meteoroid theory.

      By the way there was a video that caught the Chelyabinsk meteor from a distance as it splashed into the lake. As far as I know it is considered genuine. So you are right that there are enough ground based cameras to catch them falling.

      • Phil you have good insight as always :)

        About smell…

        I felt it one night, right after meteorite whizzed above me (I don’t know how big it was or how close it was (as you pointed, you can’t know that)).

        I saw it (moved almost horizontally at incredible rate (much faster then in video)), smell lingered on couple of minutes after…

        (And there are some ancient stories about brimstone and fire falling from the sky)

        Once again, I believe You are right:

        That is a rock, not meteo-whatever.

  9. Dirk Pons says:

    ‘coincidences happen, but not something like that.’
    Phil, I share your opinion about the likely origin of the stone. However I think your probabilistic reasoning is not really relevant as a means of excluding a rare event. Even rare events still do have finite likelihood of occurring, and in which case it really does not matter how remote the possibility might be.

    Douglas Adams famously utilised this in ‘Hitchhiker..’, and even physicists have their Boltzmann Brains. Disasters, e.g. aviation, are littered with examples of apparently rare events occurring, even sequences thereof, to cause of the failure sequence.

    BTW did you notice the stone’s rotation?

    • Philip Gibbs says:

      Hi, Dirk, I am going to assume you are serious about the probability thing despite the reference to Hitchikers guide :-)

      It is true that coincidences happen. There are countless conspiracy theories based on observations of coincidences that people assume must have a sinister explanation. They fail to see that in complex situations where many things are happening some coincidences are expected. As physicists interpreting experimental results we also have to take account of the fact that there are many experiments we dont hear about until they discover something unusual. The chances of an error look slim but we are ignoring the many things that many experiments are looking for. Improbable events happen if you try them often enough. A similar effect is true when investigating airplane accidents because the accident highlights a rare event amongst things that happen many times without accident.

      However, every moment of your life there are ridiculously improbable events that could happen and dont. If the probability of an event is much smaller than the reciprocal of the number of similar events that could happen then you can reasonably expect that something like that will not happen. It really does matter how remote the probability is. If you witnessed something unlikely and the evidence clearly shows that it did happen you have to accept it, but you have to eliminate more probable explanations first.

      The case of the meteowrong was unusual in that it was possible to estimate the probability of seeing a meteoroid in these circumstances quite well and it was incredibly unlikely even taking into account the number of similar things that could have happened in the timeframe. In this case the real explanation also seemed unlikely but that was an example of a coincidence of a sort that is to be expected from time to time.

      Recognizing when something is really unlikely versus something that is a reasonable coincidence is one thing that distinguishes people with good sense from those that believe in all kinds of crazy nonsense. It is unusual for things to be as clear cut as they were in this case, but we are making relative judgments of this sort all the time without thinking or calculating carefully.

      Your point about the rotation is also interesting. When an object is kicked up into the air it usually gains some rotation either because the force that hit it was not aligned with the centre of mass or because there was some rolling friction with the surface it took off from. That is why we would expect a stone from the parachute to be rotating.

      If it had been a meteoroid it would also have been rotating but for a different reason. When falling objects reach terminal velocity their initial angular momentum is no longer significant because the aerodynamic forces on them are big enough to dominate their motion. The motion that an object such as a meteoroid in dark fall would have depends on its shape and can be complicated. A typical result would be a spin about an axis in the direction of fall but more complicated motion is not unusual. For disk-like shapes the motion can be chaotic.

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