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Fireball over Canada and USA



I did not think this particularly relevant so I entered no
post about it, but now someone else has done so and got it all
wrong. I am a member of the Canadian Space Agency  Meteorite
and Impact dvisory Committee, and one of our a ctivities is
investigating all such reports.
        The fireball  was seen from Ottawa to P hiladelphia
at ap proximately 00.35 to 00.38 (just after midnight) on
August 24.  It was brighter than the full moon for a few
seconds. Some reports said that it lasted  more than 5
seconds.  It was heading in southeasterly direction.  One
TV crew managed to film it (CITY-TV, Toronto), but through
a break in the clouds.  The fire in a trailer near Windosr,
Windsor Ontario was coincidentally about the same time, but
turned out to be arson, and nothing to do with the fireball.
There was no sound associated with the fireball.
The best mathematical model I can come up with suggests that
the fireball was a fragile chunk of something, p robabaly a
comet fragment, with a mass of about 3 tons.  It entered
the atmosphere at a s peed of about 15 kilometers p er second
(relative to the earth) and began to burn off because of 
friction, and became visible from earth when it had descended
to about 120 to 125 kilometers elevation.  By the time it
reached 50 kilometers it ceased to be visible, either because
it has slowed to less than 3 kilometers p er second (below
which it would not ablate to give glowing particles), or more 
likely because it had burned  up co mpletely.  There is no
indication that anything landed, and I don't think anything
came below the stratopause (the bottom of the stratosphere).
Peter Brown (University of Waterloo), John Rucklidge (Univ
of Toronto ) and I are busy trying to sort out its  trajectory.

All this is not very relevant to donosaurs, not even to their
extinction, so I have not posted it before.  CSA-MIAC has had 
a great flurry of e-mail about it though.

David

--
>From: David Brez Carlisle
bk090@Freenet Carleton.CA