reply to post by candcantiques
You said it was "slow", and it is indeed true that satellites are relatively slow compared to natural meteors in general, in terms of relative
velocity. But the
apparent velocity depends on both the relative velocity as well as perspective, so a meteor can appear to be moving very
slowly, or even not at all depending on perspective.
What is just as important in determining a possible culprit is how long it lasted. Satellite reentries tend to last much longer, and can take a few
minutes to cross the sky. Even the slowest natural meteors won't take much more than about a minute to cross the sky from "horizon to horizon" (or
close to it), so I'd be pretty confident that what you saw in 2001 was a satellite reentry.
Here are a couple of examples. Mir (coincidentally although I don't think that was what you saw) on March 23 2001 from Fiji, and a Russian SL-4
rocket body that re-entered the atmosphere over Colorado and Wyoming.
As for the colours, yes, meteors, especially brighter meteors, can often have vivid colours, but it's not quite as simple as composition of the
meteoroid alone, as I explained in this thread
here a few weeks back. The
green color you saw was most likely due to the OIII forbidden emission line of atmospheric Oxygen (see below). Copper is not generally found in
meteorites or in the spectral emission lines of meteors as far as I'm aware.
I don't believe there is much evidence to support the idea that meteor
color (as seen with the eye) has much relationship to the meteoroid
composition- at least, when we are talking about fireballs. There is good evidence, however, that the color is mainly the from ionization of
atmospheric gas- especially oxygen. I've personally collected images of
several bright fireballs through a 501 nm narrow band (6 nm) filter,
which argues for a very strong [OIII] component to the light.
FWIW, a quick review of the meteor reports (nearly all fireballs) I've
received in the last 11 years shows this:
9110 reports total
3735 (41%) report some sort of color
3069 (82% of those reporting color) report some shade of green
I've long since concluded that bright fireballs are almost always green.
The exceptional cases are those which are not (and these are almost
always reported as white).
The only other color that tends to show up in witness descriptions is
red/orange, and a close look reveals that this is almost always at the
end of the path, when it is easily explained as the output of a cooling
blackbody radiator.
Chris
*******************************
Chris L Peterson
Cloudbait Observatory
Source:
METEOROBS (The Meteor Observing mailing list)
Try
this google search for lots of reading on the subject.
