Fading Meteors

[Bill Ward]

Hi,

Thanks. Yes, there is definitely a complete spectrum (no pun intended!) of ablation characteristics.

Reviewing the videos from the other night I also caught a “normal” one on the same system. To show how the ablation differs I made up a comparison video.

It is here:

https://youtu.be/y67mQm70dow

cheers,

Bill.

[Bill Ward]

Been doing some research….

It would appear the “melting” or “dissolving” meteors might be classed as the extreme end of the “dustball” meteors. It is remarkable to consider that given the initial small particle size the meteoroid crumbles to an extremely large collection of even smaller particles. Maybe >mm to micron size before evaporation is complete. What seems a bit of a paradox to me, however, is the textbooks imply that this disintegration speeds up the evaporation due to the smaller particles. That is bigger surface area more rapid ablation. But I think it can be seen that is not what happens in the video. The more robust particle, marked as normal, pops into and out of existance much more rapidly than the dissolving one. Even considering a single tiny particle after initial ablation, the video still gives the impression of a much slower demise. …AND on top of that the theory also seems to be that the meteor should also be brighter, that too doesn’t seem to be the case!

The splitting ones might be an intermediate case of the demise of a dustball. A particular case of unusual fragmentation. The same issues apply about speed and brightness I think and although some meteors are seen to fragment into distinct bits these all appear soft. For reference. Physics of meteor flight through the atmosphere by Opik (heavy duty and I don’t understand half of it! 😉 and Meteors comets and meteorites by Hawkins (much easier read and distillation of much of Opiks work). Both quite old texts now but fundamentals are sound. The problems then are still problems now!

I also reviewed a pile of older videos made using shorter focal length lenses and when one really looks closely there are actually quite a few of this type. The longer focal length lenses bring out the effects much more clearly.

So, enigmatic is actually an apt description!

These wonderful little cameras really are re-writing the rules!

cheers,

Bill.

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