Just to reiterate, the term "bolide" is best avoided when precision is
required- not because it is undefined, but because it is overdefined! It
means one thing to (most) meteoriticists, something else to geologists, and
yet something else to meteorologists.
Like "planet", it is a word best left without formal definition, and used
only with qualification.
AFAIK the IAU is not considering a definition for bolide. A couple of years
ago they were considering revising the definition of "meteor" to include the
body itself during its atmospheric passage (which most now use "meteoroid"
for). I don't know where things are on that proposal. In any case, I hope
they just leave "bolide" alone, since even with a formal definition applied
to meteoritics, we aren't likely to get any less confusion.
If you're talking casually, in a known context, use whatever terms seem
reasonable. But if you want to make things clear, something like "a
30-second fireball with extensive fragmentation and subsequent acoustic
events" is always going to be a better choice than "an impressive bolide".
Chris
*****************************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com
----- Original Message -----
From: "MEM" <[email protected]>
To: "Chris Peterson" <[email protected]>;
<[email protected]>
Sent: Sunday, January 16, 2011 2:47 AM
Subject: Re: [meteorite-list] Meteorites 101-Bolide
I largely agree, Chris, and like the overuse of the term "oriented", it
seems
everything has become a "bolide"-- minor fireballs and major impactors
alike.
The author on the work around the Chesapeake impactor adopted the term
"bolide"
in his works and I believe that was a bastardized usage-- not based in
traditional usage. IMO a crater producing impactor is NOT a bolide unless
it
produces an explosive terminus at altitude. An asteroid which excavates an
8
mile deep crater likely doesn't "bolide" upon encountering maximum
aerodynamic
pressure, and no ground observer is likely to survive to tell us if there
was
one anyway! Tagish Lake was by all accounts a super bolide having both
the
magnitude and the report. I remember seeing the term bolide used in 19th
century
descriptions, of course "areolite" was also a term used back then but I
think
bolide --suitably defined has a use in literature, still.
I think the IAU should probably adopt a definition for bolide which
narrows the
distinctions to reflect not just magnitude but disruption and audible
report.
Traditionally "bolide" was used to describe a fireball that terminated in
a
bright flash and /or explosive report. Having seen a traditional "bolide"
up
close and personal, I can attest that it is not your regular fireball
class
event. The "explosive" event is distinct from a sonic boom.
In preparation for this reply, I revisited the wiki page and I have a lot
of
disagreement regarding the adequacy or magnitude alone being the
distinction.
If we are to abandon the term bolide then we need a convention to describe
a
fireball which terminates in an expanding/explosive disintegration with
audible
report. IMO.
Elton
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