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