[meteorite-list] Fw: Meteors Light Up Morning Sky in Colorado

From: Chris Peterson <clp_at_meteoritecentral.com>
Date: Sat, 6 Jan 2007 09:03:56 -0700
Message-ID: <08ae01c731ac$450ca120$2721500a_at_bellatrix>

Hi Jos?-

There's no doubt that the vast majority of meteors last at most a few
seconds. But there is a class of fireballs which are usually seen in the
early evening, produced by low eccentricity prograde bodies. When these
bodies enter at a shallow angle, they can produce fireballs that are
seen for a good fraction of a minute, or even longer. Fireballs like
this, while rare, are still more common than reentering space junk
(especially large junk like the recent rocket body). So while it's
certainly true that reentering space junk is slow compared with the
average meteor, it isn't much slower than the average shallow fireball
witnessed over a wide area.

I think it would be very unusual for space junk to be seen for much
longer than a minute by any one observer (although a three minute path
is certainly possible, as it is also for a natural meteor). A piece of
debris with a three minute incandescent path will be quite high, and not
experiencing very high drag forces. It will have a path length of about
1200 km. That is too long for a single observer to see the entire thing.
It may burn for three minutes, but few are in a position to see all of
it.

When I saw the video for the Colorado event, I immediately thought
"reentry". The low speed was certainly a part of this, but the primary
indicator for me was the exact nature of the breakup. Even very fragile
meteoroids don't show the same degree of fragmentation this did. That's
not surprising, considering that any meteoroid is likely to be much more
homogeneous than a 10 meter long collection of sheet metal, pipes, nuts
and bolts! It was breaking into hundreds, maybe thousands of individual
fragments- something I've never seen in any natural fireball caught on
video.

Chris

*****************************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com


----- Original Message -----
From: "Jose Campos" <josecamposcomet at netcabo.pt>
To: "Meteorite List" <meteorite-list at meteoritecentral.com>
Sent: Saturday, January 06, 2007 3:29 AM
Subject: [meteorite-list] Fw: Fw: Meteors Light Up Morning Sky in
Colorado


> Hi Chris,
>
> When I say "more than a few seconds" for fireballs, I do mean less
> than a
> minute, as IN COMPARISSON to man made space debris; Of course, there
> are
> fireballs that last some 30s or so - I have seen a few of them - the
> one
> that you claim to have lasted 45s is most unsual, but certainly it is
> possible to last this long.
> Yes, the minimum speed for a meteor is about 11 km/s - that's way
> these
> are called slow meteors, - but by far, the vast majority of meteors
> we see, are much faster, namely in the early morning sky.
>
> Luminous trails produced by man made space "junk", are notoriously,
> SLOW
> moving objects - as compared to the average meteor.
> The time duration of their visibility is on ther order of a minute at
> least, more often 2 or 3 minutes - not only seconds (in this
> instance, by
> "seconds", I mean less than 1 min.). Most visual observers, with some
> experience, would say that the event seen in the sky in Colorado on
> the
> 4th of this month, was made not by meteors, but by space debris - even
> from a video such as the one shown, running at its normal speed.
> Jos? Campos
> PS- Good night to all, on that side of the word - here in Portugal its
> now
> 01h15 AM.
Received on Sat 06 Jan 2007 11:03:56 AM PST