midtskogen wrote:Absolutely. The glowing part of a meteor is a mixture of atoms from the object that have been vaporized, ionized, and mixed with the surrounding air which is also ionized, and this glowing region is much larger than the object itself.It's also important to understand that the glow is not because the gases are hot, even though they are easily hot enough that you would think they should glow like a sun. The glow is more closely related to a neon sign, made up of distinct spectral colors (emission lines due to electron jumps), than to a continuous thermal
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What we see is not really the object itself glowing, but the air surrounding it glowing. So altitude, atmospheric composition, speed conditions should also matter.
spectrum like sunlight. This is because the gas density is too low at those altitudes to form a continuous spectrum. It's the same reason the Sun's photosphere is white (continuous spectrum), while the less dense chromosphere above it is pink (an emission spectrum of mostly hydrogen and helium -- this is also how the element helium was first discovered by the way). In meteors, which spectral lines we see depends on the composition of the meteor, the air, and their ionization level.Since all these spectral lines are well known, taking a spectrum of a meteor can immediately determine which elements it contained (though not necessarily in what original relative abundance -- different elements get vaporized and mixed with the gas at different rates along its journey.) There is also a "wake" of light emission following immediately behind the meteor, which has a similar spectrum as the head, but the lines have different relative intensities:
At very high altitude, like where most Perseids start to become visible, the air pressure is low enough that a "forbidden" transition
in oxygen atoms can occur. It's the same transition which causes green aurora, and this is what makes the greenish trails that last for a few seconds after the meteor has already passed.
As Perseids get deeper into the atmosphere this forbidden transition is shut off, and a pinkish emission takes over from ionized sodium and magnesium (magnesium lends white while sodium adds yellow), combined with red from ionized nitrogen and oxygen from the surrounding air. Other meteor compositions can produce different colors; I just haven't studied them.
Some "exploding" meteors at this altitude can also leave a trail of smoke that glows reddish for up to several minutes and curls in the high atmosphere's winds. It is very similar in origin to airglow, where single atoms combine and emit light through the chemical reactions.
All in all, the physics and chemistry behind meteor colors is highly complex and interesting, and you can learn a lot about them by studying their spectra. This could actually be something really cool to combine with your automated meteor observing networks, if that's possible.