[meteorite-list] Cyclic meteorite streams?

[Sterling K. Webb]

Hi,

    E. P. Grondine wrote:
> Along those lines, why are meteor showers (comet
> debris stream intercepts) annual, and not cyclic on
> another basis?

    A small fraction of comets have orbits that intersect
the Earth's orbit at some specific spot. Debris from a comet
tend to eventually get "spread out" all along the comet's orbit
The density of the debris is thick or thin depending on how
long it's been riding along in the general envelope of the
cometary orbit.

    A location, a specific spot, on the Earth's orbit is actually
a date, a time disguised as a place. Our calendar is walk around
the circumference of the Earth's orbit in 24-hour steps. Pick
any date -- August 11 -- and you have pinned down a roughly
one-degree patch at a particular location on the Earth's orbit,
like an address on a circular street.

    If that location is where a comet's orbit intersects the Earth's
orbit there may (or may not) be debris going through the volume
of the intersection at the same time the Earth is. If the debris
stream is reasonably dense in that location year after year, we
call it a meteor "shower."

    There have long been suspicions and suggestions of what
you're talking about: "asteroidal streams," particularly associated
with near-Earth asteroids. For a history of the evidence, scroll
down to page four of this paper:
http://www.lpi.usra.edu/books/AsteroidsIII/pdf/3017.pdf



Sterling K. Webb
--------------------------------------------------------------------------------
----- Original Message ----- 
From: "E.P. Grondine" <epgrondine at yahoo.com>
To: <meteorite-list at meteoritecentral.com>
Sent: Tuesday, February 26, 2008 4:25 PM
Subject: [meteorite-list] Cyclic meteorite streams?


Hi all -

This seems a good a time as any to being this topic up
once again, as the ISS is given a chance of somewhere
between 1 in 20 to 1 in 100 of being holed by ordinary
man made space junk.

While many have taken a look at annual fall patterns,
I have often wondered if some meteorite falls are not
instead cyclic, in other words come from intercepting
recurring debris streams from asteroids?

Along those lines, why are meteor showers (comet
debris stream intercepts) annual, and not cyclic on
another basis?

E.P. Grondine
Man and Impact in the Americas




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