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(meteorobs) Meteor Colors and Luminescent Trains
Hello List,
After reading some of the posts on spectra and luminescent trains, I
thought of two things which might bear on the spectra thread.
Colors.
Before we had spectrometers and microprobes, mineralogist used a "blow
pipe" test to determine chemical content. Powdered samples were fused
(melted) by a high temperature jet of air, blown under "lung power",
through the flame of lab burner and onto the sample. The resultant
change in flame color was compared to known chemical compounds. I
understand that this color scheme has been associated by early
researchers with the colors seen in meteors (but I don't remember the
reference). (i.e, green with nickel, orange with iron, etc.). The
physical process of ablation on a meteoroid is not unlike the dynamics
of the blowpipe test. I am surmising here, but consulting a
mineralology text about blow pipe results should have a list of
associated elements and colors.
Trains with self luminosity.
For those of us who have been fortunate to see these rarities, we know
that in the darkest nights some meteors leave trains which glow long
after the meteor has passed--well beyond what one would consider to be
caused by ionization/plasma. For those familiar with florescent
minerals, we know that certain atoms serve as "activators" in the
mineral matrix to convert some ultraviolet wave lengths into visible
light.
The bulk of ultraviolet (UV radiation) reaching the atmosphere is
scattered or filtered out for ground observers, however in the upper
atmosphere it is quite intense. UV waves are bent, in lens like fashion
by the atmosphere such that, a large amount of UV still illuminates the
upper atmosphere around the globe in area swhere the sun is well over
the horizon.
Understanding that UV radiation can exist above the dark face of the
earth , and the effect it can have on certain minerals
(e.g.phosphorescence,etc.) -- could luminescent trains be the result of
very high altitude UV shining on the dust and produce a visual
wavelengths which we see as a faint glow in a very dark night?
Regards,
Elton
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