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(meteorobs) Meteor velocities
There are two references which you must consider when talking about
meteoroid velocities, heliocentric and geocentric. Geocentric velocities
are the ones usually listed in papers for the speed of meteors entering the
Earth's atmosphere. Robert Lunsford correctly pointed out that the observed
velocity of a meteor in the atmosphere is mainly due to how it encounters
the Earth, in a catch up mode or head on. Heliocentric velocities, are
velocities of meteoroids in space at 1 A.U. distance before they encounter
the Earth. Dr. Ian Halliday pointed out to me, that his paper in
Meteoritics, vol 31, 185-217, 1996, lists the heliocentric velocities for
259 fireballs recorded by the MORP fireball patrol cameras. Perseids run at
about 41 km/sec and Geminids about 34 km/sec at 1 A.U. before encountering
the Earth.
If you are interested in looking at the mathematics, Dr. Halliday
pointed me to a series of papers in the Journal of the Royal Astronomical
Society of Canada, JRASC (1960's), "Elements of Astromechanics", by Peter
van de Kamp, of Sproul Observatory, Swarthmore, Pennsylvania. Your math
skills better be better than mine! ;-)
I hope this clears things up for amateurs interested in this topic.
Ed Majden - Courtenay B.C.
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