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(meteorobs) Fireballs ,meteor sounds, nomenclature etc,
We need some way to differentiate between cometary (shower) fireball
meteors and asteroidal fireballs. These are quite different phenomenon.
Shower meteors are considered to generally be loose conglomerates of small
particles some what akin to cigarette ash. They make their appearance high
in the atmosphere, generally in the region of 120 km to 60 km. High
velocity Perseid and Leonid meteors become visible at higher altitudes than
their slower counterparts. Simultaneous sound has been reported from one
Leonid member.
On the other hand, asteroidal meteors are generally solid objects often
travelling at lower velocities and they penetrate much lower into the
atmosphere. These are the type of object that may produce a meteorite on
the ground. Are they associated with simultaneous sound phenomenon also?
It is difficult for a visual observer to estimate the velocity of a meteor
with any certainty. A near head on, high velocity Leonid may appear slow to
an observer if it is nearly head-on where it appears fast further from the
radiant.
Generally we term a meteor a fireball if it is brighter than -3.0
magnitude or so. Depending on the type of fireball your taking about,
shower type or meteorite dropping kind, this should be re-defined. A -3.0
fireball is not likely to drop a meteorite.
These definitions should be refined by the professional nomenclature
groups so when people talk about these things we are talking about the same
thing!
Ed Majden
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