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

[Jose Campos]

----- Original Message ----- 
From: "Jose Campos" <josecamposcomet at netcabo.pt>
To: "Chris Peterson" <clp at alumni.caltech.edu>
Sent: Saturday, January 06, 2007 1:15 AM
Subject: Re: [meteorite-list] 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.
>
>
>
>
>
>
> ----- Original Message ----- 
> From: "Chris Peterson" <clp at alumni.caltech.edu>
> To: "Meteorite List" <meteorite-list at meteoritecentral.com>
> Sent: Friday, January 05, 2007 11:21 PM
> Subject: Re: [meteorite-list] Fw: Meteors Light Up Morning Sky in Colorado
>
>
> Hi José-
>
> Fireballs can certainly be visible for more than a few seconds. This
> one: http://www.cloudbait.com/science/fireball20061001.html was visible
> for at least 45 seconds. I've recorded several others that were at least
> 15 seconds long. People under the central part of the Peekskill path saw
> it for about 30 seconds. The Grand Teton fireball was about 30 seconds.
> Tagish Lake produced a fireball at least 15 seconds long.
>
> Reentering space debris is not necessarily traveling at a much lower
> speed than natural meteors. An object decaying from low Earth orbit
> (which would seem to describe all space junk) has a speed of about 8
> km/s, and a slow meteor has a speed of about 11 km/s. Of course, most
> meteors will be faster (up to 71 km/s), but the famous slow fireballs
> have very similar characteristics to decaying space junk- low speed and
> shallow entry angles- and may similarly be seen for many seconds.
>
> Chris
>
> *****************************************
> Chris L Peterson
> Cloudbait Observatory
> http://www.cloudbait.com
>
>
> ----- Original Message ----- 
> From: "Jose Campos" <josecamposcomet at netcabo.pt>
> To: <gary at webbers.com>; "Meteorite List"
> <meteorite-list at meteoritecentral.com>
> Sent: Friday, January 05, 2007 3:46 PM
> Subject: Re: [meteorite-list] Fw: Meteors Light Up Morning Sky in
> Colorado
>
>
> Hi Gary,
>
> By space debris, I meant several  pieces of a MAN MADE spacecraft,
> desintegrating thru the Earth's atmosphere.
> Sorry about the confusion.
> As regarding time, a meteor's visibility  lasts only a few seconds,
> whereas
> for man made space debris, as it travells at  a much slower speed, it's
> burning trail  becomes visible  for a few minutes. The video shown on
> CNN is
> quite spectacular.
> I have seen a similar event, some 20 yrs ago (?), at night, over the
> Indian
> Ocean, when I was walking with friends on the beac front in Durban,
> South
> Africa. This event was seen by many people. The next day, it was
> reported on
> south african newspapers and TV.
>
> The visibility of a  meteor, even a -14 mag  fireball, (that is as
> bright as
> the full moon),  will not last longer than a few seconds, at most.
> José Campos
>
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