[meteorite-list] Report increases and debris streams

From: Sterling K. Webb <sterling_k_webb_at_meteoritecentral.com>
Date: Mon, 16 Feb 2009 18:00:22 -0600
Message-ID: <020d01c99092$bb7e95b0$6151e146_at_ATARIENGINE>

Hi, EP, List,

> I don't know if the intersections of the Earth
> with either cometary or asteroidal debris streams
> would necessarily be annual.

For an object to intersect the Earth, it has to intersect
the Earth's orbit at a given point. Points along the Earth's
orbit are dates of the year in the human calendar, so,
yes, these intersections would be annual (or twice annual
if the object orbit was similar in size to the Earth's orbit
but tilted with respect to it, a rare chance).

Not only does the Earth have to be at that point in its
own orbit (a date) but there has to be an object in the
"stream" orbit that goes through that intersection at
the very same time as the Earth. (This is why there is
little need to post traffic cops there...)

The orbits of small bodies, however, change rather
rapidly under the gravitational influence of the larger
bodies. Such a "stream" would like precess, which
would move the intersection along the Earth's orbit,
from one date of intersection to the next or previous
day, in a time-scale of a few centuries or less. The
intersection date might change a day every decade
or more... or less.

This rapid change is why we've never been able to
pin down a suspected "stream-crossing" from old
historical observations. Every meteorite whose orbit
was determined turned out to be from the Belt or the
Zone... out there, anyway. I found very interesting the
recent posting that Buzzard Coulee may not turn out
to be from out there but from an inner system orbit.
That orbit would be worth checking for evidence
of a "stream"!


Sterling K. Webb
--------------------------------------------------------------------
----- Original Message -----
From: "E.P. Grondine" <epgrondine at yahoo.com>
To: <meteorite-list at meteoritecentral.com>
Sent: Monday, February 16, 2009 4:54 PM
Subject: [meteorite-list] Report increases and debris streams


Hi Elton, all -

Elton - "Back to a general note: we are seeing weekly and monthly spaced
major fireballs including large meteorite falls."

Perhaps this is just the effect of the internet, along with the realization
that the falls can lead to cash.

"Statistics tell me that we are only sampling a portion of a much larger
asteroidal debris field in crossing earth orbit."

I don't know if the intersections of the Earth with either cometary or
asteroidal debris streams would necessarily be annual. What you probably
would need to do would be to sort known falls by type, subtract days between
falls, and then look for multiples. That's about as far as I can take this
kind of analysis now, and I know it's less than what would be needed.

Imagine the result if you will: "Ah, March 12. Well tonight perhaps a nice
pallasite is going to fall at 3 in the morning. Time to start up the old
fireball survey system. Wonder what it will have for us tomorrow morning?"

E.P. Grondine
Man and Impact in the Americas



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Received on Mon 16 Feb 2009 07:00:22 PM PST