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Re: (meteorobs) Fwd: How fast do Meteors go?

        Ok, I have to chime in here.  I wouldn't even put myself up against the
likes of Lew ;)  but I don't get how speed is the most important factor.  There
are dim leonids and there are bright leonids, all traveling at roughly the same
speed.  And there are dim Pi-puppids and there are bright ones.  The difference
in brightness must come from size, not speed necessarily.  The brightest of all
meteors, fireballs, must be related to their size and size only, otherwise there
is no way to account for Persied fireballs, or even less bright Persieds all
traveling at the same rate other than in their size/compositon..  In other words,
all things being equal (read: speed) size/composition is the factor that
influences brightness.
        My logic may be off, but when comparing brightness between shower members
of the same shower, speed cannot even be taken into account..dot can it?

Kim Y.



Lew Gramer wrote:

> >What factor most determines a meteors brightness (magnitude)? Is it angle
> >of entry, speed, size, composition, or a combination of all of the above.
> >The student waits for the answer.
>
> Well, Jeff, I will sure not put myself up as the biggest expert on THIS list:
> at least not with the likes of Peter Jenniskens, Peter Brown, Marco Langbroek
> or Rainer Arlt in our midst! :) But according to my understanding, the single
> most important factor in brightness (other than distance from the observer!)
> is sort of like the mantra for real estate developers: speed, speed, speed.
>
> Recall that the radiation generated by these tiny, fluffy particles during
> atmospheric entry is generated by friction, and derives ultimately from the
> kinetic energy of the fluff. And as folks remember from High School physics,
> the formula for kinetic energy is "1/2 mv^2" ("one half of em vee squared").
> Naturally, as 'v' increases, the amount of kinetic energy that is available
> to be released by friction also increases - very rapidly!
>
> The difference between the energy of a pea-sized Leonid (71 km/s) and pea-
> sized pi-Puppid (18 km/s) is like that between a bullet and a fast-ball.
>
> Of course, mass (which comes from size and density, and so indirectly from
> composition) is also important: but to far lesser degree than speed. As for
> entry angle, it DOES affect luminosity - but darned if I can explain how. :)
>
> >Long trains.
>
> And smiling gators to you! :)
>
> Lew
>
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