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Re: (meteorobs) Re: Point meteor!

Any meteor seen to move toward the zenith, with a trail which stops before the
zenith, is a candidate to hit you on the head*. This is true for small meteors
which end in free fall under gravity, but also not incorrect for larger ones,
which maintain some original velocity.

*Not a very big chance, though.

Re zenith point meteors, I think that the effects of earths rotation is
virtually cancelled out by the fact that the atmosphere moves with the earth;
therefore, apart from meteors' velocity towards you, system of you, earth,
atmosphere, and meteor, are fixed. Upper atmosphere winds notwithstanding.


exceld77 wrote:

> ----------
> > Od: Alexei PACE <apace@maltanetdot net>
> > Za: meteorobs@jovian.com
> > Zadeva: Re: (meteorobs) Re:  Point meteor!
> > Datum: 6. marec 2000 15:50
> >
> Why is that?
> I guess it would
>  > have to have some perceivable length for its trajectory to
>  > be right to hit you...
> May somebody please explain/
>
> What I wanted to say is, that if you happen to see a point fireball
> (not in the zenith!), there would be no chance od being hit by a potential
> meteorite, as the meteorite would travel on a parabolic trajectory.
>
> How much could the earth have turned in the <5seconds time the meteorite
> would take to fall to the ground?
>
> I don't think the Earth's rotation (if this is what you mean) would do much
> in 5 seconds. Also, there is no definite time required for a meteorite
> to reach the ground. But since the meteoroid's speed would have to be
> reasonably
> low at the beginning for it to reach the ground (less than 28 or something
> km/s?)
> and the terminal velocity would be around 2 to 4 km/s, I guess it would
> take more
> than 5 seconds from the beginning of the luminous path to the meteorite
> drop.
> Experts - correct me if I'm wrong!!!
>
> A meteoroid with a shallow angle of atmospheric
> entry may be airborne for over 30 seconds, but then again, seeing such a
> point fireball is extremely unlikely!
>
> Ok, this is just about as much as I know about meteorite drops - from what
> I've read at IMO and AMS sites and some articles in S&T and other
> magazines...
>
> Clear skies!
>
> Jure A.
>
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