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Re: (meteorobs) Fireballs, dark flight and meteorites
>A REPOSITORY OF SCIENCE "FACT." THE OBJECT IMPACTING THE EARTH WOULD NOT HAVE
>BEEN BURNING, AS WITNESSED BY THOSE ABOUT TO DIE, UNLESS THE PULL OF GRAVITY
>KEPT ITS SPEED AT A RATE WHICH WOULD HAVE CAUSED ENOUGH FRICTION TO COMBUST
Actually, John, the premise behind "Deep Impact" was that there *was* a comet
fragment which was MORE than large enough to reach the surface of Earth while
still at celestial velocity: an object of sufficient mass would reach Earth's
surface travelling a sizeable fraction of its original entry velocity. Above
perhaps 1 million(?) tons, I'd imagine the object would not be appreciably
slowed at all by its friction with our atmosphere: so it would strike the
surface of earth at a speed between 11 and 72 km/s, probably causing some
effects very much like what that movie depicted...
Of course, the movie's depiction of visible flames traveling behind the comet
fragment days BEFORE its impact, among other things, were entirely silly. :)
Clear skies and pleasant dreams all,
Lew
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