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Norwegian skydiver nearly struck by meteorite

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Re: Norwegian skydiver nearly struck by meteorite

#51

Post by ProAm »

dclowd9901 wrote: post #47

I'm... skeptical. If you look at the frames of the meteorite falling, it looks like each frame has the fragment at about 3 feet from its last position. If that's a 60fps camera (I think it is?), that's 180 f/s speed or 122mph. That seems really slow for a rock flying into the atmosphere from space, and far slower than a rock would have to be going for it to "cut him in half." My guess: a rock that fell off the underc…

These rocks slow down considerably when they move through the atmosphere (Unless they are massive and this one was not). What is also interesting is most the time they are cold to the touch immediately after impact.[1][2]

[1]http://misconceptions.us/are-meteorites-hot-or-cold-when-the... [2] http://curious.astro.cornell.edu/question.php?number=215

Re: Norwegian skydiver nearly struck by meteorite

#52

Post by Zigurd »

dclowd9901 wrote: post #47

I'm... skeptical. If you look at the frames of the meteorite falling, it looks like each frame has the fragment at about 3 feet from its last position. If that's a 60fps camera (I think it is?), that's 180 f/s speed or 122mph. That seems really slow for a rock flying into the atmosphere from space, and far slower than a rock would have to be going for it to "cut him in half." My guess: a rock that fell off the underc…

GoPros have high frame-rate modes.

Re: Norwegian skydiver nearly struck by meteorite

#53

Post by peterwwillis »

tummybug wrote: post #38

Seems strange that the other diver is following the same path as the meteorite and passes by just a few seconds later. Could he have dropped it and it accelerated to a speed faster than he was travelling?

Possibly. A small rock would have a lot less air resistance than a person, and those suits are designed to increase air resistance. So it might end up with a higher terminal velocity and fall slightly faster.

http://www.wired.com/2013/10/do-heavier-objects-really-fall-... http://www.physicsclassroom.com/mmedia/newtlaws/efar.cfm

Re: Norwegian skydiver nearly struck by meteorite

#54

Post by allthatisgold »

dclowd9901 wrote: post #47

I'm... skeptical. If you look at the frames of the meteorite falling, it looks like each frame has the fragment at about 3 feet from its last position. If that's a 60fps camera (I think it is?), that's 180 f/s speed or 122mph. That seems really slow for a rock flying into the atmosphere from space, and far slower than a rock would have to be going for it to "cut him in half." My guess: a rock that fell off the underc…

Camera isn't stationary.

Re: Norwegian skydiver nearly struck by meteorite

#55

Post by andyjohnson0 »

dclowd9901 wrote: post #47

I'm... skeptical. If you look at the frames of the meteorite falling, it looks like each frame has the fragment at about 3 feet from its last position. If that's a 60fps camera (I think it is?), that's 180 f/s speed or 122mph. That seems really slow for a rock flying into the atmosphere from space, and far slower than a rock would have to be going for it to "cut him in half." My guess: a rock that fell off the underc…

By the time it has reached the kind of altitude that skydivers would be operating it, a meteor would have lost most of its speed to atmospheric compression and friction. According to this faq [1] the terminal velocity for a small meteorite is 200-400 miles/hour, which is not far from your estimate.

[1] http://www.amsmeteors.org/fireballs/faqf/#12

Re: Norwegian skydiver nearly struck by meteorite

#56

Post by base698 »

tummybug wrote: post #38

Seems strange that the other diver is following the same path as the meteorite and passes by just a few seconds later. Could he have dropped it and it accelerated to a speed faster than he was travelling?

A wingsuit has a forward speed of around 100mph and your arms are bound. It definitely didn't come from a friend. It looks like it has significant forward speed like the jumpers. Throw from the aircraft stops at around the 10 second mark into freefall on a wingsuit jump it's likely they were 2 minutes or more after exit making the forward speed of the rock likely to come from neither another jumper or the plane.

Re: Norwegian skydiver nearly struck by meteorite

#57

Post by simias »

jessedhillon wrote: post #30
simias wrote: post #12

Earlier quoted context omitted.

Yeah, Occam's razor tells me that it's much more likely that a stone got stuck somewhere in their skydiving apparatus than having a meteorite fly right past you while you're skydiving. Maybe I'm underestimating the quantity of meteorites falling on the earth but since the newspapers aren't exactly filled with news of people getting killed by falling rocks I'm not yet ready to believe that was a meteorite.

If you look at how a parachute is packed, and how it unfolds when deployed, what you described is definitely not the simpler explanation preferred by Occam's razor.

Well, since it seems I'm in a minority here I'll accept that I might be misjudging the odds on this one, especially since I know nothing about skydiving.

I guess it goes to prove that since nowadays we're almost all carrying video recorders with us at all times the probability of catching the most elusive events on video gets increasingly large. I expect to see a video of someone standing at the foot of a rainbow any day now.

Re: Norwegian skydiver nearly struck by meteorite

#58

Post by bitL »

dredmorbius wrote: post #46

A related question: what's the probability of an aircraft being struck by a meteor. Seems this question was asked in the wake of the Air France flight 447 disappearance (since resolved as pitot tube freezing combined with pilot error and control feedback failures of the Airbus design). But still, the odds of a strike on _an_ aircraft over the next 20 years are about 4%: http://blog.revolutionanalytics.com/2009/06/how…

That would be under an assumption that the distribution of planes around the globe is even. Given most jetliners are flying in corridors, I would say the actual probability is much much lower. The same can be probably said about meteorites - I guess their geographic distribution is uneven as well.

Re: Norwegian skydiver nearly struck by meteorite

#59

Post by stouset »

binarymax wrote: post #7
jon_black wrote: post #3

Is it me or does it look like the "meteorite" is moving quite slow. Shouldn't it be moving so fast that you'd need a high speed camera to see it in that detail? Also...his parachute is always above him, maybe it fell out of that.

It had already entered the atmosphere, and probably slowed down significantly due to friction, then based on its mass it reached a low terminal velocity. https://en.wikipedia.org/wiki/Terminal_velocity

Ram pressure, not friction

Re: Norwegian skydiver nearly struck by meteorite

#60

Post by woodchuck64 »

Shouldn't we be expecting a rock that has just been heated to plasma stage by atmospheric friction only seconds earlier to be glowing, steaming or leaving little molten fragments of itself behind?

Update: maybe not. The last stage of flight is "dark and cold" according to this: http://www.meteorite-recon.com/en/Meteorite_fusion_crust_1.h...

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