Starship Asterisk*

Chemicals Glow as a Meteor Disintegrates

Explanation: Meteors can be colorful. While the human eye usually cannot discern many colors, cameras often can. Pictured here is a fireball, a disintegrating meteor that was not only one of the brightest the photographer has ever seen, but colorful. The meteor was captured by chance in mid-July with a camera set up on Hochkar Mountain in Austria to photograph the central band of our Milky Way galaxy. The radiant grit, likely cast off by a comet or asteroid long ago, had the misfortune to enter Earth's atmosphere. Colors in meteors usually originate from ionized chemical elements released as the meteor disintegrates, with blue-green typically originating from magnesium, calcium radiating violet, and nickel glowing green. Red, however, typically originates from energized nitrogen and oxygen in the Earth's atmosphere. This bright meteoric fireball was gone in a flash -- less than a second -- but it left a wind-blown ionization trail that remained visible for almost a minute.

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A meteorite particle emits light depending on the temperature it acquires, as it heats up with the Earth's atmosphere and/or when it recombines when it cools (even with elements in the atmosphere) and it all depends on the material that was formed.

To no one's surprise, I love the vivid color display of this meteor - especially, of course, the parts of it that are a vivid blue!

But I was disappointed at the caption:

APOD Robot wrote:

Colors in meteors usually originate from ionized chemical elements released as the meteor disintegrates, with blue-green typically originating from magnesium, calcium radiating violet, and nickel glowing green.

Blue-green? Like this? ███


To me the blue color of the meteor looks a lot more like ███ than like ███!

So what chemical is causing the blue color of the meteor trail?

Ann

Ann wrote: ↑Mon Jul 24, 2023 5:04 am ...
But I was disappointed at the caption:

APOD Robot wrote:

Colors in meteors usually originate from ionized chemical elements released as the meteor disintegrates, with blue-green typically originating from magnesium, calcium radiating violet, and nickel glowing green.

Blue-green? Like this? ███


APOD 24 July 2023 detail.png


To me the blue color of the meteor looks a lot more like ███ than like ███!

So what chemical is causing the blue color of the meteor trail?

Ann

Colour (UK spelling) is subjective. I have a specific colour blindness for some shades of blue. I know this because a work colleague of mine was pointing out his car, "the blue one", and I could only see three grey cars. Other colleagues agreed not only on which one was being identified, but also on the colours: two grey cars, one blue. So APOD's 'Blue-Green' may not be quite the same as my 'Blue-Green', or yours.

Ann wrote: ↑Mon Jul 24, 2023 5:04 am

Chemicals Glow as a Meteor Disintegrates. Image Credit & Copyright: Michael Kleinburger

---

To no one's surprise, I love the vivid color display of this meteor - especially, of course, the parts of it that are a vivid blue!

But I was disappointed at the caption:

APOD Robot wrote:

Colors in meteors usually originate from ionized chemical elements released as the meteor disintegrates, with blue-green typically originating from magnesium, calcium radiating violet, and nickel glowing green.

Blue-green? Like this? ███


APOD 24 July 2023 detail.png


To me the blue color of the meteor looks a lot more like ███ than like ███!

So what chemical is causing the blue color of the meteor trail?

Ann

None of the colors we see are reliable indicators of any particular elemental components. That information is apparent in meteor spectra, but our eyes and brains put together combinations of continuum emissions as well as narrowband emissions from numerous elements and heated atmospheric gas to construct "color".

The color variation is the result of changes in speed, size, and temperature of the body, changes in composition of the body as the volatiles burn away at the beginning and the refractory components later in the path, and the atmospheric nature at various altitudes.

Is the meteor trail blue gold or yellow green? After 4 decades, I still don't see my clothes the same way as my wife.

Just dreaming here - wouldn't it be great if we purposely orbited a bunch of retrograde particles into earth orbit and used them to measure upper atmosphere properties? Might save a whole lot of high altitude balloons.

HellCat wrote: ↑Mon Jul 24, 2023 1:30 pm Is the meteor trail blue gold or yellow green? After 4 decades, I still don't see my clothes the same way as my wife.

Just dreaming here - wouldn't it be great if we purposely orbited a bunch of retrograde particles into earth orbit and used them to measure upper atmosphere properties? Might save a whole lot of high altitude balloons.

There have been experiments involving artificial meteors going back more than 50 years. And there's a Japanese company that is planning to create artificial meteor showers (as art, not science) by launching pellets from space in just a couple of years.

Eclectic Man wrote: ↑Mon Jul 24, 2023 11:10 am

Ann wrote: ↑Mon Jul 24, 2023 5:04 am ...
But I was disappointed at the caption:

APOD Robot wrote:

Colors in meteors usually originate from ionized chemical elements released as the meteor disintegrates, with blue-green typically originating from magnesium, calcium radiating violet, and nickel glowing green.

Blue-green? Like this? ███


APOD 24 July 2023 detail.png


To me the blue color of the meteor looks a lot more like ███ than like ███!

So what chemical is causing the blue color of the meteor trail?

Ann

Colour (UK spelling) is subjective. I have a specific colour blindness for some shades of blue. I know this because a work colleague of mine was pointing out his car, "the blue one", and I could only see three grey cars. Other colleagues agreed not only on which one was being identified, but also on the colours: two grey cars, one blue. So APOD's 'Blue-Green' may not be quite the same as my 'Blue-Green', or yours.

Colo(u)rs are individual perception-based, wavelength-dependent neurosensory phenomena : https://medium.com/predict/what-color-i ... faee67dcf2.

I decided to find out about the emission lines of magnesium.

http://seaver-faculty.pepperdine.edu wrote:

The most prominent line in the spectrum of magnesium is 285.2 nm. Other prominent lines are found at 383.8 and 518.4 nm. In what region of the electromagnetic radiation spectrum is each line? Which line is the most energetic?

The 285.2 nm line is in the ultraviolet and is the most energetic; the other two lines are in the visible light.

Yeah, well: 383.8 nm would look something like this, ███, and 518.4 nm would look something like this: ███. (Whoa!!! That's green!!)

And according to Wikimedia Commons, the most prominent spectral lines of magnesium between 400 and 700 nm are these (note that we are missing out on the 383.8 nm line):


Well! That double whammy at center left sure is turquoise!

I still don't understand what caused the blue color of that meteor. I guess we'll never know.

Ann

Ann wrote: ↑Mon Jul 24, 2023 2:38 pm I still don't understand what caused the blue color of that meteor. I guess we'll never know.

Again, our eyes are not spectroscopes, so we cannot reliably connect perceived color with any given spectral lines. That said, calcium (Ca II) strongly emits in the middle of our S (blue) cone spectral sensitivity, and is a dominant line in many meteor spectra.

(And, of course, what's mainly at issue here isn't the response of our eyes, but of the camera that recorded this.)

Too bad a meteor flash lasts for only a few seconds; very pretty! What you looking at; kitty cat?

A few years back I posted a message after I witnessed a bright Bolide meteor over the UK which crossed well over 100 degrees of the sky from my location in Lincolnshire. At first I mistook the meteor for bright white / blue white aircraft landing lights as it was quite low 15 degrees over the north eastern horizon. As it passed in front of Ursa Majors 'pan' it grew intensely bright like looking at a oxy acetylene blow torch which although intensely white had sparkles with violet and blue tones at the UV end of the spectrum. As my meteor passed by it left a bright trail that as it dimmed faded through the visible spectrum from white, white grey, through yellow, orange to red, (which I guess was from the particulates left behind or the ionised gases cooling) whilst the bright white body itself continued to sparkle with all colours, before atmospheric thickening as it approached the north western horizon caused the body to fly apart and the meteor fragments going from white to yellow and then orange as slowed and flew deeper into the atmosphere.

Whilst some of the colours I witnessed were undoubtedly from the after image on my retina, (an an obvious green colour) the colour range I saw of the meteor itself and the trail it left was amazing. This apod does capture the varied effects I witnessed and reminded me vividly of the past event I was lucky to see from start to finish.