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Re: (meteorobs) Re: bolide explosions



Perhaps the biggest problem in understanding how meteors explode is the
general use of the word to mean "chemical explosion" (rapid expansion of
gasses following a violent chemical reaction) rather than the more general
"violent breakup" of a body.  The explanation George gives is correct, but
the analogy is perhaps too extreme.  The pressures experienced at the
times of breakup, as documented from fireball photos, are very much
smaller than the tensile strength of the recovered meteorites.  It would
therefore appear that the original bodies have pre-existing weaknesses or
fracture lines.  This would be expected from the likely genesis of the
meteorites in violent collisions between asteroids or when being blasted
off the surface of the Moon or Mars.  George's analogy is certainly most
apt for the low density cometary bolides which disintegrate at heights of
around 80km.

Cheers, Rob

Robert H. McNaught
rmn@aaocbn.aaodot gov.au

On Fri, 15 Jan 1999 GeoZay@aol.com wrote:

> 
>  howard>> My question is: What makes them explode??<<
> 
> Howard,
> Basically there are enormous pressure differences between the forward and rear
> surfaces of an incoming meteorite. The atmosphere rapidly compresses the
> forward surface, while behind the body a near vacuum exists. This extreme
> pressure difference acts to flatten the body, creating even greater resistance
> to it's forward motion. If the body isn't sturdy enough to withstand these
> differances of pressure, it will explode like a dirt clod slamming into a
> brick wall.
> GeoZay
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