[meteorite-list] Re: Entry Burn [was Lunar Burn]
I agree with Chris. Bear in mind that the source of the luminous phenomena we see when we see a meteor, is not so much the meteoroid itself burning up: it's the atmosphere around it becoming incandescend. - Marco There are only a limited number of meteor spectra, so the colors aren't real well understood, but I'd be surprised if you saw the nickel emission over the atmospheric oxygen. The majority of slow, bright meteors are reported as green by many witnesses, but only a small fraction of those contain significant nickel. Chris - Dr Marco Langbroek Dutch Meteor Society (DMS) e-mail: [EMAIL PROTECTED] private website http://home.wanadoo.nl/marco.langbroek DMS website http://www.dmsweb.org - __ Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
Re: [meteorite-list] Re: Entry Burn [was Lunar Burn]
Hi all - While one might think that the difference in entry spectra is simply a reflection of the neural function of the eye, based on my observational experience, I have to disagree. Both entries were bright, and there was a distinct difference in spectra. I think this could go the way of the cold meteorites discussion, but fortunately in this case the color capabilities of automatic videotaping systems will probably resolve the question in the near future. The one had a green cast to it, the other did not. At least that's how it looked to me. I suppose for the time being maybe its best to leave it at that. good hunting, Ed --- Marco Langbroek [EMAIL PROTECTED] wrote: I agree with Chris. Bear in mind that the source of the luminous phenomena we see when we see a meteor, is not so much the meteoroid itself burning up: it's the atmosphere around it becoming incandescend. - Marco There are only a limited number of meteor spectra, so the colors aren't real well understood, but I'd be surprised if you saw the nickel emission over the atmospheric oxygen. The majority of slow, bright meteors are reported as green by many witnesses, but only a small fraction of those contain significant nickel. Chris - Dr Marco Langbroek Dutch Meteor Society (DMS) e-mail: [EMAIL PROTECTED] private website http://home.wanadoo.nl/marco.langbroek DMS website http://www.dmsweb.org - __ Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list __ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com __ Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
[meteorite-list] Re: Entry Burn [was Lunar Burn]
Ed, Chris me do not dispute that meteors can have different colours. What we point out is that these colours do not necessarily reflect the meteoroid composition, such as was assumed earlier in the thread. This is certainly the case for reported greenish colours, as we know from what meteor spectra exist that the Oxygen line at 558 nm (green), which is due to atmospheric Oxygen, often is a very prominent line in these spectra. The contribution of gasses in the atmosphere will vary with respect to altitude, and energy release. This is very evident in photographs of persistent trains of meteors, e.g. the many shot by us and others during the Leonids the past decade. Quit often you see that the early (higher) part of this is green, while the later (lower) part of these is yellow-red. - Marco Both entries were bright, and there was a distinct difference in spectra. I think this could go the way of the cold meteorites discussion, but fortunately in this case the color capabilities of automatic videotaping systems will probably resolve the question in the near future. The one had a green cast to it, the other did not. At least that's how it looked to me. I suppose for the time being maybe its best to leave it at that. good hunting, Ed - Dr Marco Langbroek Dutch Meteor Society (DMS) e-mail: [EMAIL PROTECTED] private website http://home.wanadoo.nl/marco.langbroek DMS website http://www.dmsweb.org - __ Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
Re: [meteorite-list] Re: Entry Burn [was Lunar Burn]
Welcome back, Walter I'd like to point out that my original comment was intended to desuggest copper in favor of nickel. We who have done blowpipe mineral studies tend to think in that framework. Several years ago on my farm outside Ft Benning, Georgia I saw 2 nearly identical fireballs in the same sky location but they were on adjacent nights. Both were headed towards the Benning impact area, so I had doubts as to their true identity. Most notable was that both showed a pressure/bow wave clearly leading the dimmer fireball. The bow waves were orange in the center with green wings. Since the sighting of two identical fireballs on successive evenings is improbable, my inclination was that this might be secret rail gun experiments. The rail gun fires a Lucite slug with copper plate. Ergo the assumption that this was a copper blowpipe signature.( I now believe that these were true meteoroids not weapon's testing) Around that time there was a list discussion about green meteors and the consensus was that green from a meteor was due to nickel--copper being an extremely minor element found in meteorites. Thus the origin of that thought: nickel vs copper. There was also a lengthy discussion about the desire to do spectral analysis on fireballs as a signature for identifying possible meteoroid composition. I hadn't heard much since that time. I don't disagree that oxygen has a green spectral line, just that this was the first I heard of atmospheric oxygen as an emmiter in fireball reentry. I rarely see green as a color in fireballs with some Leonoids and the two specific fireballs I mentioned before as the notible exceptions. If anyone has specific links to the discussion of meteor spectrums, please share. Elton __ Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
[meteorite-list] Re: Entry Burn [was Lunar Burn]
Hi Chris, list I have seen two entrie. I believe I posted the first one to the list, and it was green - at the time I was in Virgina, and the entry was so green I first thought that it either had to be a)an accidental launch warhead entry (which I stopped thinking when nothing exploded), or b) a piece of space junk. But it was neither, if I remember the news reports from the time - no space junk announcement from NORAD, and press pieces (as always, of dubious reliability) that it was a meteorite. The second entry I saw about early December, 2003. It should have been over Ohio, I was driving west thtough the Winchester Gap. No green tinge at all on this one, just big. I like Elton's observation that it is probably the nickel. This agrees well with the recently observed entries of small pieces of SW3. good hunting, Ed --- Chris Peterson [EMAIL PROTECTED] wrote: The color produced by a meteor is primarily a product of the ionization of atmospheric gases. You might learn something about the composition of the object spectroscopically, but such measurements are difficult and rare. Simply using color reported by witnesses is of no value in assessing composition. Chris * Chris L Peterson Cloudbait Observatory http://www.cloudbait.com - Original Message - From: Meteorite Game [EMAIL PROTECTED] To: meteorite-list@meteoritecentral.com Sent: Monday, August 21, 2006 4:08 PM Subject: [meteorite-list] Lunar Burn What color would a lunar meteor give off in the atmosphere? If I'm not mistaken their basalt? Could a probability factor be given to pass and future meteors showing the probability of a meteor being lunar? With a high probability factor would this not aid meteorite hunters to make a recovery of a lunar meteorite? Cordially, Rick __ Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list __ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com __ Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
Re: [meteorite-list] Re: Entry Burn [was Lunar Burn]
There are only a limited number of meteor spectra, so the colors aren't real well understood, but I'd be surprised if you saw the nickel emission over the atmospheric oxygen. The majority of slow, bright meteors are reported as green by many witnesses, but only a small fraction of those contain significant nickel. Chris * Chris L Peterson Cloudbait Observatory http://www.cloudbait.com - Original Message - From: E.P. Grondine [EMAIL PROTECTED] To: meteorite-list@meteoritecentral.com Sent: Tuesday, August 22, 2006 11:14 PM Subject: [meteorite-list] Re: Entry Burn [was Lunar Burn] Hi Chris, list I have seen two entrie. I believe I posted the first one to the list, and it was green - at the time I was in Virgina, and the entry was so green I first thought that it either had to be a)an accidental launch warhead entry (which I stopped thinking when nothing exploded), or b) a piece of space junk. But it was neither, if I remember the news reports from the time - no space junk announcement from NORAD, and press pieces (as always, of dubious reliability) that it was a meteorite. The second entry I saw about early December, 2003. It should have been over Ohio, I was driving west thtough the Winchester Gap. No green tinge at all on this one, just big. I like Elton's observation that it is probably the nickel. This agrees well with the recently observed entries of small pieces of SW3. good hunting, Ed __ Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
