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

[Chris Peterson]

Hi José-

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.
> José Campos
> PS- Good night to all, on that side of the word - here in Portugal its 
> now
> 01h15 AM.