[Prev][Next][Index][Thread]

re: (meteorobs) Radiant angular size: how come?

I really wish you wouldn't mention that new guide.
Looks like I'll have to be reordering, since between the German and US 
postal services, I only wound up with an empty envelope. It's been a month, 
and our USPS hasn't even seen fit to send back a reply telling me they 
can't find it, and did not respond to an e-mail inquiry on their web page. 
Jerks.
Sorry for venting and whining.
;-<
Wayne
O-
Wayne
-------------
Original Text
From: Lew Gramer <dedalus@latradedot com>, on 10/16/96 1:42 PM:
To: "Meteor Observing Mailing List" <meteorobs@latradedot com>

While just perusing the (snazzy, newly updated!) IMO Visual Meteor 
Observing 
pages on the World Wide Web, I came on the following item:

 "Due to perturbations and different ejection conditions from their parent 
object, the individual particles of a meteor shower do not move on exactly 
the 
same orbit. Thus they do not all enter the atmosphere exactly parallel to 
one 
another. The result of this is that a radiant is not a point but an area of 
a 
certain size whose dimensions depend on how widely the individual orbits 
are 
spread, and on the geometrical conditions of how the stream encounters the 
Earth, and thus differs from shower to shower (Kresak & Porubcan, 1970)."


What confuses me about this is that I know (from other AMS and IMO 
publications) 
that meteoroids' orbits are actually GREATLY perturbed from their original 
source body's orbit, due to solar wind, planetary perturbations, etc., etc.

So in spite of the fact that meteoroids may end up in "Apollo-like" orbits, 
even 
when they originate from hyperbolic-orbit comets, does the tiny initial 
velocity 
each one has relative to its parent body REALLY get preserved long enough 
to 
show up as a radiant dispersion?! Or is there some other effect (like time 
variations in solar output, or tiny-scale tidal effects on the stream, 
whatever) 
that results in more like a poisson distribution over a given radiant area?

Just a curious question from a theoretical wannabe,
Lew
Follow-Ups: