[meteorite-list] Asteroid, Meteorite Impacts Can Preserve Biodata for Millions of Years

[Ron Baalke via Meteorite-list]

http://www.sci-news.com/geology/science-asteroid-meteorite-impacts-biodata-01867.html

Asteroid, Meteorite Impacts Can Preserve Biodata for Millions of Years
Sci-News.com
Apr 18, 2014

In two separate studies, geologists led by Dr Haley Sapers from the University 
of Western Ontario and Dr Pete Schultz of Brown University have found 
floral, microbial and organic matter in glass created by ancient asteroid, 
comet and meteorite impacts. Such glass samples could provide a snapshot 
of environmental conditions at the time of those impacts and could be 
a good place to look for signs of ancient life on Mars.

[Image]
This image shows microbial trace fossils in 15 million-year-old impact 
glass from the Ries Impact Structure, Germany. Image credit: H.M Sapers 
et al.

In the first study, published in the journal Geology, Dr Schultz with 
colleagues found fragments of leaves and preserved organic compounds lodged 
inside glass created by a several ancient impacts in Argentina.

"The soil of eastern Argentina, south of Buenos Aires, is rife with impact 
glass created by at least seven different impacts that occurred between 
6,000 and 9 million years ago," Dr Schultz explained.

"One of those impacts, dated to around 3 million years ago, coincides 
with the disappearance of 35 animal genera."

"We know these were major impacts because of how far the glass is distributed 
and how big the chunks are. These glasses are present in different layers 
of sediment throughout an area about the size of Texas," he said.

Within glass associated with two of those impacts - one from 3 million 
years ago and one from 9 million years ago - the team found exquisitely 
preserved plant matter.

"These glasses preserve plant morphology from macro features all the way 
down to the micron scale. It's really remarkable," Dr Schultz said.

The glass samples contain centimeter-size leaf fragments, including intact 
structures like papillae, tiny bumps that line leaf surfaces. Bundles 
of vein-like structures found in several samples are very similar to modern 
pampas grass, a species common to that region of Argentina.

Chemical analysis of the samples also revealed the presence of organic 
hydrocarbons, the chemical signatures of living matter.

To understand how these structures and compounds could have been preserved, 
the scientists tried to replicate that preservation in the lab.

They mixed pulverized impact glass with fragments of pampas grass leaves 
and heated the mixture at various temperatures for various amounts of 
time. The experiments showed that plant material was preserved when the 
samples were quickly heated to above 1,500 degrees Celsius.

"It appears that water in the exterior layers of the leaves insulates 
the inside layers, allowing them to stay intact. The outside of the leaves 
takes it for the interior. It's a little like deep frying. The outside 
fries up quickly but the inside takes much longer to cook," Dr Schultz 
explained.

In the second study, published also in the journal Geology, Dr Sapers 
and her colleagues discovered microbes preserved in impact glass.

They analyzed tubular features in hydrothermally altered impact glass 
from the Ries Impact Structure, Germany, that are remarkably similar to 
the bioalteration textures observed in volcanic glasses.

Mineral-forming processes cannot easily explain the distribution and shapes 
of the Ries tubular features; therefore, they suggest the tubules formed 
by microbes etching their way through the impact glass as they excreted 
organic acids.

A meteorite impact into a water-rich target such as Earth or Mars has 
the potential to generate a post-impact hydrothermal system.

Impact structures, especially post-impact hydrothermal systems, represent 
an understudied habitat with potential relevance to early life and the 
evolution of early life on Earth.

Understanding the biological significance of impact products such as impact 
glass on Earth will better inform the search for evidence of life and 
past life on other terrestrial planets such as Mars.

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[meteorite-list] Russia's First Static Meteor Observing Station is Opened in Siberia

[Ron Baalke via Meteorite-list]

http://siberiantimes.com/science/casestudy/news/n0471-russias-first-static-meteor-observing-station-is-opened-in-siberia/

Russia's First Static Meteor Observing Station is Opened in Siberia
The Siberian Times 
28 October 2015

One early visitor: a fireball streaking across the sky and splashing into 
Lake Baikal.

The station is in remote Tunka valley, in the Republic of Buryatia, an 
ideal vantage point for observing incoming meteors because of the absence 
of artificial lighting. Created by the astronomical observatory of the 
Irkutsk State University (ISU), it operates from two unmanned modules 
some 58 kilometres apart. 

This allows researchers to observe the same meteor from two different 
locations, and to measure its size, light energy, direction, weight of 
meteoric particles and other parameters, more precisely. 

[Photo]
It operates from two unmanned modules some 58 kilometres apart.  Picture: 
The Siberian Times

Kirill Ivanov, researcher at ISU's observatory, explained that the cameras 
are pointed in such a way that the centres of their field of view match 
at a height of about 100 km. 'They ensure maximum overlap of the field 
of view, two thirds, at a height of about 80-120 km. The data is stored 
in industrial computers.' On a clear night, the equipment has registered 
up to 40 meteorites.

On 22 October, two weeks after the facility opened it recorded recorded 
a bright fireball, flying from west to east, over the mountains of Mongolia 
and Buryatia. Having originated in the Asteroid Belt, the meteorite's 
journey ended as it sank into the waters of Lake Baikal, about 1 km from 
the shore, and 17 km from the village of Bolshoye Goloustnoye.

'Most likely that meteorite fell under the 'bad' influence of Jupiter, 
and away from its 'true path',' said Ivanov. Its initial mass was around 
one kilogram, its size - about 10 centimetres. This meteorite  - shown 
in the video here - was also spotted by locals. 

A key research aim is to expand our knowledge of the meteors, their 
characteristics 
and paths. In November researchers plan to observe the prolific Leonid 
meteor shower. This occurs when the Earth crosses the orbital path of 
Comet Tempel-Tuttle. The comet litters its orbit with fragments of bits 
of debris which enter the Earth's atmosphere and vaporise.

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Re: [meteorite-list] Very Bright Fireball Over Europe on Halloween Night

[kashuba via Meteorite-list]

Rob, Marco,

OK, so color isn't important.  But why the different colors?  Not green
can't mean no oxygen. Is the green overwhelmed by other colors?  Why?

- John

John Kashuba
Bend, Oregon 

-Original Message-
From: Meteorite-list [mailto:meteorite-list-boun...@meteoritecentral.com] On
Behalf Of Rob Matson via Meteorite-list
Sent: Wednesday, November 04, 2015 12:54 AM
To: 'meteorite-list'
Subject: Re: [meteorite-list] Very Bright Fireball Over Europe on Halloween
Night

HI All,

Marco took the words out of my mouth. Getting tired of hearing that a green
meteor tells you anything about its composition. I know that it's natural
for
people to think the most important thing they can report about a meteor
is its color, but I wish various broadcast media would do the public a
service
and disabuse them of this notion. It would be far better if witnesses
could be trained to get in the habit of counting the duration accurately,
and noting the exact time of the meteor to the nearest minute. Seeing as
how almost everyone has a cell phone these days, and all cell phones have
accurate clocks, there really is no excuse to get the time wrong. Yet even
a casual browse of the AMS fireball site reveals that people clearly don't
think getting the time right is important. And even more obvious is that
most people have no business reporting anything about fireball starting
and ending bearings and elevation angles.  --Rob

-Original Message-
From: Meteorite-list [mailto:meteorite-list-boun...@meteoritecentral.com] On
Behalf Of Marco Langbroek via Meteorite-list
Sent: Wednesday, November 04, 2015 12:06 AM
To: meteorite-list@meteoritecentral.com; baa...@zagami.jpl.nasa.gov
Subject: Re: [meteorite-list] Very Bright Fireball Over Europe on Halloween
Night

> A lot of folks say it looked green to them, which means it may have been
> metallic;


It is a perpetuated misunderstanding that meteor colours are primarily due
to 
their composition. It's a science myth inspired by High School Bunsen burner

experiments that appears hard to kill.

While composition in some cases does have some influence on the colour, it
is 
actually the composition of the atmosphere that is usually dominant for our 
perception of meteor colours.

That certainly is true for green colours. Meteor spectra show that meteors 
usually are very strong at the "forbidden" Oxygen line at 5577 Angstrom
(557.7 
nm). This line is due to atmospheric Oxygen, the same atmospheric Oxygen 
exitation line also responsible for the green colours of Aurora.

So green meteor colours are likely atmospheric in origin and say little
about 
the meteoroids' composition.

- Marco

-
Dr Marco (asteroid 183294) Langbroek
Dutch Meteor Society (DMS)

e-mail: d...@marcolangbroek.nl
http://www.marcolangbroek.nl

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[meteorite-list] What Smacks Into Ceres Stays On Ceres

[Ron Baalke via Meteorite-list]

https://news.brown.edu/articles/2015/10/ceres

What smacks into Ceres stays on Ceres
Brown University
Contact: Kevin Stacey   401-863-3766
October 14, 2015   

Ceres, the largest object in the asteroid belt and closest dwarf planet 
to Earth, had been remarkable for its plain surface. New research suggests 
that most of the material that has struck Ceres in high-speed collisions 
has stuck - billions of years worth of meteorite material.

PROVIDENCE, R.I. [Brown University] - A new set of high-velocity impact 
experiments suggests that the dwarf planet Ceres may be something of a 
cosmic dartboard: Projectiles that slam into it  tend to stick.

The experiments, performed using the Vertical Gun Range at NASA's Ames 
Research Center, suggest that when asteroids and other impactors hit Ceres, 
much of the impact material remains on the surface instead of bouncing 
off into space. The findings suggest the surface of Ceres could consist 
largely of a mish-mash of meteoritic material collected over billions 
of years of bombardment.

The research, by Terik Daly and Peter Schultz of Brown University, is 
published in Geophysical Research Letters .

Ceres is the largest object in the asteroid belt and the nearest dwarf 
planet to Earth. Until the recent arrival of the Dawn spacecraft, all 
that was known about Ceres came from telescopic observations. The observations 
showed Ceres to be mysteriously low in density, suggesting it is made 
either of very porous silicate material, or perhaps contains a large layer 
of water ice. Observations of its surface were remarkable as well - largely 
for being unremarkable.

"It's really bland in the telescopic observations," said Daly, a Ph.D. 
student at Brown and the study's lead author. "It's like someone took 
a single color of spray paint and sprayed the whole thing. When we think 
about what might have caused this homogeneous surface, our thoughts turn 
to impact processes."

And to understand impact processes, the researchers turned to NASA's Vertical 
Gun Range, a cannon with a 14-foot barrel that can launch projectiles 
at up to 16,000 miles per hour. For this work, Daly and Schultz wanted 
to simulate impacts into low-density surfaces that mimic the two broad 
possibilities for the composition of Ceres' surface: porous silicate 
or icy.

"The idea was to look at those two end-member cases, because we really 
don't know yet exactly what Ceres is like," Daly said.

For the porous silicate case, the researchers launched impactors into 
a powdered pumice. For the icy case, they used two targets: snow, and 
snow covered by a thin veneer of fluffy silicate material, simulating 
the possibility the Ceres' ice sits below a silicate layer. They then 
blasted these targets with pebble-sized bits of basalt and aluminum, simulating 
both stony and metallic meteorites.

The study showed that in all cases, large proportions of the impact material 
remained in and around the impact crater. This was especially true in 
the icy case, Daly said.

"We show that when you have a vertical impact into snow - an analog for 
the porous ice we think might be just beneath the surface of Ceres - you 
can have about 77 percent of the impactor's mass stay in or near the crater."

The results were a bit of a surprise, said Schultz, who has studied impact 
processes for many years as professor of earth, environmental, and planetary 
sciences at Brown.

"This is really contrary to previous estimates for small bodies," Schultz 
said. "The thought was that you'd eject more material that you'd collect, 
but we show you can really deliver a ton of material."

The impact speeds used in the experiments were similar to speeds thought 
to be common in asteroid belt collisions. The findings suggest that a 
majority of impacts on porous bodies like Ceres cause an accumulation 
of impact material on the surface.

"People have thought that perhaps if an impact was unusually slow, then 
you could deliver this much material," Schultz said. "But what we're saying 
is that for a typical, average-speed impact in the asteroid belt, you're 
delivering a ton of material."

Over billions of years of such impacts, Ceres may have accumulated quite 
a bit of non-native material, Daly and Schultz said, much of it mixing 
together to create the relatively nondescript surface seen from telescopes. 
The researchers are hopeful that as the Dawn spacecraft scans the surface 
at much higher resolution, it might be able to pick out individual patches 
of this delivered material. That would help confirm the relevance of these 
experiments to celestial bodies, the researchers say.

The results have implications for missions that aim to return asteroid 
samples to Earth. Unless the landing sites are carefully chosen, the 
researchers 
say, those missions could end up with samples that aren't representative 
of the object's original material. To get that, it might be necessary 
to find an area where there has been a relatively 

Re: [meteorite-list] Asteroid, Meteorite Impacts Can Preserve Biodata for Millions of Years

[John Lutzon via Meteorite-list]

Hello List, Ron,

H, is there any chance that terrestrial inclusions may be
preserved in Besednice Moldavite glass?
I never thought to scope it. Are there any studies on this subject?

John

- Original Message - 
From: "Ron Baalke via Meteorite-list" 
To: "Meteorite Mailing List" 
Sent: Wednesday, November 04, 2015 4:37 PM
Subject: [meteorite-list] Asteroid,Meteorite Impacts Can Preserve Biodata for 
Millions of Years




http://www.sci-news.com/geology/science-asteroid-meteorite-impacts-biodata-01867.html

Asteroid, Meteorite Impacts Can Preserve Biodata for Millions of Years
Sci-News.com
Apr 18, 2014

In two separate studies, geologists led by Dr Haley Sapers from the University 
of Western Ontario and Dr Pete Schultz of Brown University have found 
floral, microbial and organic matter in glass created by ancient asteroid, 
comet and meteorite impacts. Such glass samples could provide a snapshot 
of environmental conditions at the time of those impacts and could be 
a good place to look for signs of ancient life on Mars.

[Image]
This image shows microbial trace fossils in 15 million-year-old impact 
glass from the Ries Impact Structure, Germany. Image credit: H.M Sapers 
et al.

In the first study, published in the journal Geology, Dr Schultz with 
colleagues found fragments of leaves and preserved organic compounds lodged 
inside glass created by a several ancient impacts in Argentina.

"The soil of eastern Argentina, south of Buenos Aires, is rife with impact 
glass created by at least seven different impacts that occurred between 
6,000 and 9 million years ago," Dr Schultz explained.

"One of those impacts, dated to around 3 million years ago, coincides 
with the disappearance of 35 animal genera."

"We know these were major impacts because of how far the glass is distributed 
and how big the chunks are. These glasses are present in different layers 
of sediment throughout an area about the size of Texas," he said.

Within glass associated with two of those impacts - one from 3 million 
years ago and one from 9 million years ago - the team found exquisitely 
preserved plant matter.

"These glasses preserve plant morphology from macro features all the way 
down to the micron scale. It's really remarkable," Dr Schultz said.

The glass samples contain centimeter-size leaf fragments, including intact 
structures like papillae, tiny bumps that line leaf surfaces. Bundles 
of vein-like structures found in several samples are very similar to modern 
pampas grass, a species common to that region of Argentina.

Chemical analysis of the samples also revealed the presence of organic 
hydrocarbons, the chemical signatures of living matter.

To understand how these structures and compounds could have been preserved, 
the scientists tried to replicate that preservation in the lab.

They mixed pulverized impact glass with fragments of pampas grass leaves 
and heated the mixture at various temperatures for various amounts of 
time. The experiments showed that plant material was preserved when the 
samples were quickly heated to above 1,500 degrees Celsius.

"It appears that water in the exterior layers of the leaves insulates 
the inside layers, allowing them to stay intact. The outside of the leaves 
takes it for the interior. It's a little like deep frying. The outside 
fries up quickly but the inside takes much longer to cook," Dr Schultz 
explained.

In the second study, published also in the journal Geology, Dr Sapers 
and her colleagues discovered microbes preserved in impact glass.

They analyzed tubular features in hydrothermally altered impact glass 
from the Ries Impact Structure, Germany, that are remarkably similar to 
the bioalteration textures observed in volcanic glasses.

Mineral-forming processes cannot easily explain the distribution and shapes 
of the Ries tubular features; therefore, they suggest the tubules formed 
by microbes etching their way through the impact glass as they excreted 
organic acids.

A meteorite impact into a water-rich target such as Earth or Mars has 
the potential to generate a post-impact hydrothermal system.

Impact structures, especially post-impact hydrothermal systems, represent 
an understudied habitat with potential relevance to early life and the 
evolution of early life on Earth.

Understanding the biological significance of impact products such as impact 
glass on Earth will better inform the search for evidence of life and 
past life on other terrestrial planets such as Mars.

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[meteorite-list] Drift of Draconid Radiant

[E.P. Grondine via Meteorite-list]

Hi all - 

For the last several years, I have been speaking at Serpent Mound:

http://ancientearthworksproject.org/1/post/2014/07/new-radiocarbon-dates-suggest-serpent-mound-is-more-than-2000-years-old.html

Originally and abysmally, this structure was dated by Brad Lepper to the 1066 
CE appearance of Halley's Comet.

It appears clear from the structure itself that it was meant to reflect the 
constellation Draco, 
although Its builders the Andaste were genocidally exterminated 
before any detailed record was made of their astronomy. 

While the weather here in Ohio usually prevents viewing the Draconids, 
it appears they would be visible a month or a month and a half earlier at the 
time this site was first cleared, 
sometime after 1,000 BCE or so. 
Note especially the later construction ca 360 BCE.
We currently have no idea what triggered that.


Draco's radiant's location has implications as far as Gobekli Tepe's 
alignments. 
Has the Earth been hit by trwo cometary streams in the last 15,000 years, both 
Giacbinii Zinner and Encke?
In other words, precisely how bad is the cometary impact hazard?
Has the recent rate of cometary injection been high, or is this normal?

E.P. 
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Re: [meteorite-list] Very Bright Fireball Over Europe on Halloween Night

[Chris Peterson via Meteorite-list]

Meteor color is important. It's just not a very useful measure for 
determining composition. Color changes with meteor speed and meteor 
depth in the atmosphere. And certainly, the composition is a factor, 
both in terms of chemical composition and bulk properties. But the 
relationship is complex, so there's no simple correlation between these 
things and color that we can make much use of.


Common groups of factors tend to lead to common colors, which is why we 
see specific colors with specific showers.


Chris

***
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

On 11/4/2015 3:16 PM, kashuba via Meteorite-list wrote:

Rob, Marco,

OK, so color isn't important.  But why the different colors?  Not green
can't mean no oxygen. Is the green overwhelmed by other colors?  Why?

- John

John Kashuba
Bend, Oregon


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Re: [meteorite-list] Drift of Draconid Radiant

[E.P. Grondine via Meteorite-list]

Hi Mike - 

I hope I am not spoiling anyone's source here, but 

Your go-to guy for Serpent Mound geological specimens is Tom Johnson of the 
House of Phacops.
He can also provide local fossils.

IMO, there is a whole lot of BS that is spouted as regards the ceremonial 
complex there.

That said, the EMF there at the impact epicenter is high enough to disorient 
migrating birds, 
and interfere with electronic circuits, including those of the human brain.

I hope to put my and my colleague Fletcher Wilson ( one of Ohio's leading naked 
eye astronomers)
pamphlet into e-book from someday.

E.P.


On Wed, 11/4/15, Galactic Stone & Ironworks  wrote:

 Subject: Re: [meteorite-list] Drift of Draconid Radiant
 To: "E. P. Grondine" 
 Cc: "MPML" , "Meteorite List" 

 Date: Wednesday, November 4, 2015, 8:33 PM
 
 Hi EP and
 List,
 I have been fascinated lately with the folklore
 surrounding the Serpent Mound crater. My interest was
 triggered by receiving a batch of Serpent Mound breccia
 chunks which I cut and sold. (still have some
 available).
 I have never visited the site, but if I ever
 find myself in that neck of the woods, I will certainly pay
 a visit.  Hope to see you there one day.  :)
 Best regards,
 MikeG 
 On Nov 4, 2015 8:28 PM,
 "E.P. Grondine via Meteorite-list" 
 wrote:
 Hi all
 -
 
 
 
 For the last several years, I have been speaking at Serpent
 Mound:
 
 
 
 
http://ancientearthworksproject.org/1/post/2014/07/new-radiocarbon-dates-suggest-serpent-mound-is-more-than-2000-years-old.html
 
 
 
 Originally and abysmally, this structure was dated by Brad
 Lepper to the 1066 CE appearance of Halley's Comet.
 
 
 
 It appears clear from the structure itself that it was meant
 to reflect the constellation Draco,
 
 although Its builders the Andaste were genocidally
 exterminated
 
 before any detailed record was made of their astronomy.
 
 
 
 While the weather here in Ohio usually prevents viewing the
 Draconids,
 
 it appears they would be visible a month or a month and a
 half earlier at the time this site was first cleared,
 
 sometime after 1,000 BCE or so.
 
 Note especially the later construction ca 360 BCE.
 
 We currently have no idea what triggered that.
 
 
 
 
 
 Draco's radiant's location has implications as far
 as Gobekli Tepe's alignments.
 
 Has the Earth been hit by trwo cometary streams in the last
 15,000 years, both Giacbinii Zinner and Encke?
 
 In other words, precisely how bad is the cometary impact
 hazard?
 
 Has the recent rate of cometary injection been high, or is
 this normal?
 
 
 
 E.P.
 
 __
 
 
 
 Visit our Facebook page https://www.facebook.com/meteoritecentral
 and the Archives at http://www.meteorite-list-archives.com
 
 Meteorite-list mailing list
 
 Meteorite-list@meteoritecentral.com
 
 https://pairlist3.pair.net/mailman/listinfo/meteorite-list
 
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Re: [meteorite-list] Very Bright Fireball Over Europe on Halloween Night

[Michael Mulgrew via Meteorite-list]

Different colors because there are different constituents in our atmosphere.

Unless people are recording meteors with a spectrograph reporting
"color" is useless since everyone sees colors differently, and the
human eye is hardly a scientific calibrated device.

Michael in so. Cal.

On Wed, Nov 4, 2015 at 2:16 PM, kashuba via Meteorite-list
 wrote:
> Rob, Marco,
>
> OK, so color isn't important.  But why the different colors?  Not green
> can't mean no oxygen. Is the green overwhelmed by other colors?  Why?
>
> - John
>
> John Kashuba
> Bend, Oregon
>
> -Original Message-
> From: Meteorite-list [mailto:meteorite-list-boun...@meteoritecentral.com] On
> Behalf Of Rob Matson via Meteorite-list
> Sent: Wednesday, November 04, 2015 12:54 AM
> To: 'meteorite-list'
> Subject: Re: [meteorite-list] Very Bright Fireball Over Europe on Halloween
> Night
>
> HI All,
>
> Marco took the words out of my mouth. Getting tired of hearing that a green
> meteor tells you anything about its composition. I know that it's natural
> for
> people to think the most important thing they can report about a meteor
> is its color, but I wish various broadcast media would do the public a
> service
> and disabuse them of this notion. It would be far better if witnesses
> could be trained to get in the habit of counting the duration accurately,
> and noting the exact time of the meteor to the nearest minute. Seeing as
> how almost everyone has a cell phone these days, and all cell phones have
> accurate clocks, there really is no excuse to get the time wrong. Yet even
> a casual browse of the AMS fireball site reveals that people clearly don't
> think getting the time right is important. And even more obvious is that
> most people have no business reporting anything about fireball starting
> and ending bearings and elevation angles.  --Rob
>
> -Original Message-
> From: Meteorite-list [mailto:meteorite-list-boun...@meteoritecentral.com] On
> Behalf Of Marco Langbroek via Meteorite-list
> Sent: Wednesday, November 04, 2015 12:06 AM
> To: meteorite-list@meteoritecentral.com; baa...@zagami.jpl.nasa.gov
> Subject: Re: [meteorite-list] Very Bright Fireball Over Europe on Halloween
> Night
>
>> A lot of folks say it looked green to them, which means it may have been
>> metallic;
>
>
> It is a perpetuated misunderstanding that meteor colours are primarily due
> to
> their composition. It's a science myth inspired by High School Bunsen burner
>
> experiments that appears hard to kill.
>
> While composition in some cases does have some influence on the colour, it
> is
> actually the composition of the atmosphere that is usually dominant for our
> perception of meteor colours.
>
> That certainly is true for green colours. Meteor spectra show that meteors
> usually are very strong at the "forbidden" Oxygen line at 5577 Angstrom
> (557.7
> nm). This line is due to atmospheric Oxygen, the same atmospheric Oxygen
> exitation line also responsible for the green colours of Aurora.
>
> So green meteor colours are likely atmospheric in origin and say little
> about
> the meteoroids' composition.
>
> - Marco
>
> -
> Dr Marco (asteroid 183294) Langbroek
> Dutch Meteor Society (DMS)
>
> e-mail: d...@marcolangbroek.nl
> http://www.marcolangbroek.nl
>
> __
>
> Visit our Facebook page https://www.facebook.com/meteoritecentral and the
> Archives at http://www.meteorite-list-archives.com
> Meteorite-list mailing list
> Meteorite-list@meteoritecentral.com
> https://pairlist3.pair.net/mailman/listinfo/meteorite-list
>
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>
> Visit our Facebook page https://www.facebook.com/meteoritecentral and the 
> Archives at http://www.meteorite-list-archives.com
> Meteorite-list mailing list
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[meteorite-list] Witness information that is more helpful than color

[Matson, Rob D. via Meteorite-list]

Hi John,

I think there are definitely things that can be learned by looking at the 
spectroscopy
of fireball emissions, but of course such data are rare. And human 
eyeballs/brains
are a poor substitute. We don't have the necessary spectral resolution, and of 
course
the optical response is far from flat. It is perhaps not coincidental that 
green-blue
(0.498 microns) is the peak of our scotopic response. Deep red (>0.63 microns)
sensitivity is almost non-existent in scotopic vision, so even if a fireball 
had a
significant red component, a much smaller green component would swamp it just
due to our spectral response.

Since nothing really diagnostic can be learned from a witness's perception of a
fireball's color (as far as the meteoroid's composition is concerned), I see 
little
point in asking them or encouraging them to report it. The next best thing
that a novice witness can report (other than an accurate time and duration)
is the slope of the meteor track relative to the horizon -- perhaps using a
clockface analogy to avoid scary geometry. If I know the approximate fall
zone reasonably accurately, a distant observer's slope approximation can
greatly narrow down the true flight bearing, even without azimuth information
(which can already be inferred from their location relative to the fall with
greater accuracy than they can report).

Mike Hankey has put together some very nice tools on the AMS site for
amateurs to contribute useful information, concentrating on those things
that non-technical people are reasonably good at. With enough witnesses,
the average solution can sometimes be fairly accurate, even if the individual
reports are all over the place.  --Rob

-Original Message-
From: Meteorite-list [mailto:meteorite-list-boun...@meteoritecentral.com] On 
Behalf Of kashuba via Meteorite-list
Sent: Wednesday, November 04, 2015 2:16 PM
To: 'Rob Matson'
Cc: 'meteorite-list'
Subject: Re: [meteorite-list] Very Bright Fireball Over Europe on Halloween 
Night

Rob, Marco,

OK, so color isn't important.  But why the different colors?  Not green can't 
mean no oxygen. Is the green overwhelmed by other colors?  Why?

- John

John Kashuba
Bend, Oregon 

-Original Message-
From: Meteorite-list [mailto:meteorite-list-boun...@meteoritecentral.com] On 
Behalf Of Rob Matson via Meteorite-list
Sent: Wednesday, November 04, 2015 12:54 AM
To: 'meteorite-list'
Subject: Re: [meteorite-list] Very Bright Fireball Over Europe on Halloween 
Night

HI All,

Marco took the words out of my mouth. Getting tired of hearing that a green 
meteor tells you anything about its composition. I know that it's natural for 
people to think the most important thing they can report about a meteor is its 
color, but I wish various broadcast media would do the public a service and 
disabuse them of this notion. It would be far better if witnesses could be 
trained to get in the habit of counting the duration accurately, and noting the 
exact time of the meteor to the nearest minute. Seeing as how almost everyone 
has a cell phone these days, and all cell phones have accurate clocks, there 
really is no excuse to get the time wrong. Yet even a casual browse of the AMS 
fireball site reveals that people clearly don't think getting the time right is 
important. And even more obvious is that most people have no business reporting 
anything about fireball starting and ending bearings and elevation angles.  
--Rob

-Original Message-
From: Meteorite-list [mailto:meteorite-list-boun...@meteoritecentral.com] On 
Behalf Of Marco Langbroek via Meteorite-list
Sent: Wednesday, November 04, 2015 12:06 AM
To: meteorite-list@meteoritecentral.com; baa...@zagami.jpl.nasa.gov
Subject: Re: [meteorite-list] Very Bright Fireball Over Europe on Halloween 
Night

> A lot of folks say it looked green to them, which means it may have 
> been metallic;


It is a perpetuated misunderstanding that meteor colours are primarily due to 
their composition. It's a science myth inspired by High School Bunsen burner

experiments that appears hard to kill.

While composition in some cases does have some influence on the colour, it is 
actually the composition of the atmosphere that is usually dominant for our 
perception of meteor colours.

That certainly is true for green colours. Meteor spectra show that meteors 
usually are very strong at the "forbidden" Oxygen line at 5577 Angstrom
(557.7
nm). This line is due to atmospheric Oxygen, the same atmospheric Oxygen 
exitation line also responsible for the green colours of Aurora.

So green meteor colours are likely atmospheric in origin and say little about 
the meteoroids' composition.

- Marco

-
Dr Marco (asteroid 183294) Langbroek
Dutch Meteor Society (DMS)

e-mail: d...@marcolangbroek.nl
http://www.marcolangbroek.nl

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[meteorite-list] Mound Near Lunar South Pole Formed by Unique Volcanic Process

[Ron Baalke via Meteorite-list]

https://news.brown.edu/articles/2015/10/mound

Mound near lunar south pole formed by unique volcanic process
Brown University
Contact: Kevin Stacey   401-863-3766
October 15, 2015   

Within a giant impact basin near the Moon's south pole, there sits a large 
mound of mysterious origin. Research by Brown University geologists suggests 
that the mound was formed by unique volcanic processes set in motion by 
the impact that formed the basin.

PROVIDENCE, R.I. [Brown University] - A giant mound near the Moon's south 
pole appears to be a volcanic structure unlike any other found on the 
lunar surface, according to new research by Brown University geologists.

The formation, known as Mafic Mound, stands about 800 meters tall and 
75 kilometers across, smack in the middle of a giant impact crater known 
as the South Pole-Aitken Basin. This new study suggests that the mound 
is the result of a unique kind of volcanic activity set in motion by the 
colossal impact that formed the basin.

"If the scenarios that we lay out for its formation are correct, it could 
represent a totally new volcanic process that's never been seen before," 
said Daniel Moriarty, a Ph.D. student in Brown's Department of Earth, 
Environmental and Planetary Sciences and the study's lead author.

The research has been accepted for publication in Geophysical Research 
Letters, a publication of the American Geophysical Union, and is available 
online.

Mafic Mound (mafic is a term for rocks rich in minerals such as pyroxene 
and olivine) was first discovered in the 1990s by Carle Pieters, a planetary 
geologist at Brown and Moriarty's adviser. What makes it curious, other 
than its substantial size, is the fact that it has a different mineralogical 
composition than the surrounding rock. The mound is rich in high-calcium 
pyroxene, whereas the surrounding rock is low-calcium.


A volcanic structure

"This unusual structure at the very center of the basin begs the question: 
What is this thing, and might it be related to the basin formation process?" 
Moriarty said.

To investigate that, Moriarty and Pieters looked at a rich suite of data 
from multiple lunar exploration missions. They used detailed mineralogical 
data from the Moon Mineralogy Mapper, which flew aboard India's Chandrayaan-1 
spacecraft. NASA's Lunar Orbiter Laser Altimeter provided precise topographic 
data, and data from the GRAIL mission characterized gravitational anomalies 
in the region.

Those combined datasets suggested that Mafic Mound was created by one 
of two unique volcanic processes set in motion by the giant South Pole-Aitken 
impact. An impact of that size would have created a cauldron of melted 
rock as much as 50 kilometers deep, some researchers think. As that sheet 
of impact melt cooled and crystalized, it would have shrunk. As it did, 
still-molten material in the middle of the melt sheet may have been squeezed 
out the top like toothpaste from a tube. Eventually, that erupted material 
may have formed the mound.

Such a process could explain the mound's strange mineralogy. Models of 
how the South Pole-Aitken melt sheet may have crystalized suggest that 
the erupting material should be rich in high-calcium pyroxene, which is 
consistent with the observed mineralogy of the mound.

Another scenario that fits the data involves possible melting of the Moon's 
mantle shortly after the South Pole-Aitken impact. The impact would have 
blasted tons of rock out of the basin, creating a low-gravity region. 
The lower gravity condition could have enabled the center of the basin 
to rebound upward. Such upward movement would have caused partial melting 
of mantle material, which could have erupted to form the mound.

These scenarios make for a strong fit to those very detailed datasets, 
Moriarty said. And if either is true, it would represent a unique process 
on lunar surface. Moriarty said a sample return mission to the South Pole 
Aitken Basin would be a great way to try to verify the results. The basin 
has long been an interesting mission target for lunar scientists.

"It's the largest confirmed impact structure in the solar system and has 
shaped many aspects of the evolution of the Moon,' Moriarty said. "So 
a big topic in lunar science is studying this basin and the effects it 
had on the geology of the Moon through time."

A sample return mission to the basin could bring back bits of lunar mantle, 
the composition of which is still not fully understood. A returned sample 
could also put a firm date on when the impact occurred, which could be 
used as a standard to date other features on the surface.

And in light of this work, a sample could also help to shed light on a 
unique lunar volcanic process.

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Re: [meteorite-list] Very Bright Fireball Over Europe on Halloween Night

[Doug Ross via Meteorite-list]

Thanks for the very informative and interesting discussion. Could the altitude, 
angle and distance from which a meteor is viewed also affect perceived color? 
Seems to me that the air between the fireball and the witness might 
significantly filter the colors, in the same way that the sun can appear red at 
sunset, viewed at a low angle through more atmosphere.

Doug Ross


> HI All,
> 
> Marco took the words out of my mouth. Getting tired of hearing that a green
> meteor tells you anything about its composition. I know that it's natural
> for
> people to think the most important thing they can report about a meteor
> is its color, but I wish various broadcast media would do the public a
> service
> and disabuse them of this notion. It would be far better if witnesses
> could be trained to get in the habit of counting the duration accurately,
> and noting the exact time of the meteor to the nearest minute. Seeing as
> how almost everyone has a cell phone these days, and all cell phones have
> accurate clocks, there really is no excuse to get the time wrong. Yet even
> a casual browse of the AMS fireball site reveals that people clearly don't
> think getting the time right is important. And even more obvious is that
> most people have no business reporting anything about fireball starting
> and ending bearings and elevation angles.  --Rob
> 
> -Original Message-
> From: Meteorite-list [mailto:meteorite-list-boun...@meteoritecentral.com] On
> Behalf Of Marco Langbroek via Meteorite-list
> Sent: Wednesday, November 04, 2015 12:06 AM
> To: meteorite-list@meteoritecentral.com; baa...@zagami.jpl.nasa.gov
> Subject: Re: [meteorite-list] Very Bright Fireball Over Europe on Halloween
> Night
> 
>> A lot of folks say it looked green to them, which means it may have been
>> metallic;
> 
> 
> It is a perpetuated misunderstanding that meteor colours are primarily due
> to 
> their composition. It's a science myth inspired by High School Bunsen burner
> 
> experiments that appears hard to kill.
> 
> While composition in some cases does have some influence on the colour, it
> is 
> actually the composition of the atmosphere that is usually dominant for our 
> perception of meteor colours.
> 
> That certainly is true for green colours. Meteor spectra show that meteors 
> usually are very strong at the "forbidden" Oxygen line at 5577 Angstrom
> (557.7 
> nm). This line is due to atmospheric Oxygen, the same atmospheric Oxygen 
> exitation line also responsible for the green colours of Aurora.
> 
> So green meteor colours are likely atmospheric in origin and say little
> about 
> the meteoroids' composition.
> 
> - Marco
> 
> -
> Dr Marco (asteroid 183294) Langbroek
> Dutch Meteor Society (DMS)
> 
> e-mail: d...@marcolangbroek.nl
> http://www.marcolangbroek.nl



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Re: [meteorite-list] Very Bright Fireball Over Europe on Halloween Night

[Robert Verish via Meteorite-list]

Yes Doug, 
I agree with you. 
In fact, I witnessed the very scenario you described.  

It was a long duration (earth-grazing) fireball that I was lucky enough to 
catch early-on in its flight. 
While it was at high elevation the fireball was a bright-blue ball with a 
greenish coma. 
As it streaked down to the horizon, it changed to a greenish-yellow flame, and 
as it approached 
the horizon it became a much dimmer, reddish sparkler.  
The flight-path gave me the distinct impression that the fireball was 
travelling away from me, 
much more than it was travelling downward.  
This helped me rationalize that the fireball hadn't really "dimmed" in 
brightness at the horizon.  
I was sure that it was just as bright and bluish-green for any lucky observers 
down-range and 
who were directly beneath the fireball, at the same point in its flight-path 
where I perceived it 
as being "reddish".  
Just as you worded it, Doug, the color changed "the same way that the sun can 
appear 
red at sunset, viewed at a low angle through more atmosphere."  

So, were in agreement then, that 
color AND magnitude are in the eye [and view angle] of the beholder.
Bob V.

On Wed, 11/4/15, Doug Ross via Meteorite-list 

 To: "Meteorite List" 
 Cc: "Matson, Rob D." 
 Date: Wednesday, November 4, 2015, 7:25 PM
 
 Thanks for the very informative and interesting discussion. 
 Could the altitude, angle and distance from which a meteor is viewed 
 also affect perceived color? 
 Seems to me that the air between the fireball and the witness might 
 significantly filter the colors, in the same way that the sun can appear 
 red at sunset, viewed at a low angle through more atmosphere.
 
 Doug Ross
 
 
 > HI All,
 > 
 > Marco took the words out of my mouth. Getting tired of hearing that a green
 > meteor tells you anything about its composition. I know that it's natural
 > for people to think the most important thing they can report about a meteor
 > is its color, but I wish various broadcast media would do the public a
 > service and disabuse them of this notion. It would be far better if witnesses
 > could be trained to get in the habit of counting the duration accurately,
 > and noting the exact time of the meteor to the nearest minute. Seeing as
 > how almost everyone has a cell phone these days, and all cell phones have
 > accurate clocks, there really is no excuse to get the time wrong. Yet even 
 > a casual browse of the AMS fireball site reveals that people clearly don't
 > think getting the time right is important. And even more obvious is that
 > most people have no business reporting anything about fireball starting
 > and ending bearings and elevation angles.  --Rob
 > 
 > -Original Message-
 > From: Meteorite-list [mailto:meteorite-list-boun...@meteoritecentral.com]
 > On Behalf Of Marco Langbroek via Meteorite-list
 > Sent: Wednesday, November 04, 2015 12:06 AM
 > To: meteorite-list@meteoritecentral.com; baa...@zagami.jpl.nasa.gov
 > Subject: Re: [meteorite-list] Very Bright Fireball Over Europe on Halloween 
 > Night
 > 
 >> A lot of folks say it looked green to them, which means it may have been
 >> metallic;
 > 
 > 
 > It is a perpetuated misunderstanding that meteor colours are primarily due 
 > to 
 > their composition. It's a science myth inspired by High School Bunsen burner 
 > experiments that appears hard to kill.
 > 
 > While composition in some cases does have some influence on the colour, it 
 > is 
 > actually the composition of the atmosphere that is usually dominant for our 
 > perception of meteor colours.
 > 
 > That certainly is true for green colours. Meteor spectra show that meteors 
 > usually are very strong at the "forbidden" Oxygen line at 5577 Angstrom 
 > (557.7 nm). 
 > This line is due to atmospheric Oxygen, the same atmospheric Oxygen 
 > exitation line also responsible for the green colours of Aurora.
 > 
 > So green meteor colours are likely atmospheric in origin and say little
 > about the meteoroids' composition.
 > 
 > - Marco
 > 
 > -
 > Dr Marco (asteroid 183294) Langbroek
 > Dutch Meteor Society (DMS)
 > 
 > e-mail: d...@marcolangbroek.nl
 > http://www.marcolangbroek.nl 
 __
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[meteorite-list] Meteorite Picture of the Day

[Paul Swartz via Meteorite-list]

Today's Meteorite Picture of the Day: Murnpeowie

Contributed by: Graham Macleod

http://www.tucsonmeteorites.com/mpodmain.asp?DD=11/05/2015
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[meteorite-list] MRO HiRISE Images: November 4, 2015

[Ron Baalke via Meteorite-list]

MARS RECONNAISSANCE ORBITER HIRISE IMAGES
November 4, 2015

o Meanders in Ridge Form in the Zephyria Region 
  http://hirise.lpl.arizona.edu/ESP_024695_1745

  In this image, an ancient sinuous meandering river system 
  is surrounded by features called "yardangs."

o Small Channels and a Rocky Patch in the Cydonia Region
  http://hirise.lpl.arizona.edu/ESP_032283_2115

  The southern section of this observation is dominated by both a 
  series of craters and the remnants of channels that may be from a 
  past fluvial system.

o Marching Dust Devils  
  http://hirise.lpl.arizona.edu/ESP_042201_1715

  On an early fall afternoon in Ganges Chasma, we managed to capture 
  a cluster of 8 dust devils. Not too bad!

All of the HiRISE images are archived here:

http://hirise.lpl.arizona.edu/

Information about the Mars Reconnaissance Orbiter is 
online at http://www.nasa.gov/mro. The mission is 
managed by NASA's Jet Propulsion Laboratory, a division 
of the California Institute of Technology, for the NASA 
Science Mission Directorate, Washington, D.C. Lockheed 
Martin Space Systems, of Denver, is the prime contractor 
and built the spacecraft. HiRISE is operated by the 
University of Arizona. Ball Aerospace and Technologies 
Corp., of Boulder, Colo., built the HiRISE instrument.

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Re: [meteorite-list] Very Bright Fireball Over Europe on Halloween Night

[Chris Peterson via Meteorite-list]

The whole issue of meteor color is complex. We now have many examples of 
high resolution meteor spectra... but "color" is a physiological 
phenomenon that isn't always easy to relate to physical spectra.


The light of meteors consists mostly of thermally broadened atomic 
emission lines- lots of them- from both the meteoritic material and the 
atmosphere. As has been noted, the atmospheric contributions tend to 
dominate. But there are often strong lines from meteoritic material, as 
well. In the case of large fireballs (where we have much less 
spectroscopic data) there may be a blackbody contribution as well, 
either from the ablating surface or from a supercompressed plasma. And 
since this is mostly driven by thermal effects, the speed of the body 
makes a big difference in perceived color. Throw into all of this the 
complexities of human vision- differences in retinal response, 
persistence effects, psychological effects given typically short 
observation times- and it's little wonder this entire area remains 
poorly understood.


After large fireballs, when I get many witness reports submitted, I 
review color. It's common for about half the witnesses who report color 
to agree on one in particular (green is by far the most common), while 
the other half see red, orange, yellow, or blue.


My takeaway is that we should generally assume that most color is coming 
from atmospheric contributions, probably modified slightly by meteoritic 
components (often too subtly for people to report accurately), and that 
above all, it's almost impossible to make any assumptions about 
meteoroid composition from color.


Chris

***
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

On 11/4/2015 5:21 AM, Beatty, Kelly via Meteorite-list wrote:

Marco, Rob...

this discussion is timely. what you've noted is exactly my understanding. just 
yesterday I came across a high-profile blog about these fireballs, and the 
writer stated that most of the light comes from the superheated vaporized 
particle as it ablates. suspecting this was wrong, I looked in several places 
for the correct information -- IMO, AMS, RASC Handbook, etc -- and yet I didn't 
really find the physics spelled out explicitly. (maybe I was looking in the 
wrong places?) the closest I came was this post by Peter Jenniskens 
(http://leonid.arc.nasa.gov/meteor.html), which was equivocal.

clear skies,
Kelly

***
J. Kelly Beatty
Senior Editor, Sky & Telescope
SkyandTelescope.com
(a division of F+W, a Content + eCommerce Company)

617-864-7360 x22168
@NightSkyGuy


-Original Message-
From: Meteorite-list [mailto:meteorite-list-boun...@meteoritecentral.com] On 
Behalf Of Rob Matson via Meteorite-list
Sent: Wednesday, November 04, 2015 3:54 AM
To: 'meteorite-list'
Subject: Re: [meteorite-list] Very Bright Fireball Over Europe on Halloween 
Night

HI All,

Marco took the words out of my mouth. Getting tired of hearing that a green 
meteor tells you anything about its composition. I know that it's natural for 
people to think the most important thing they can report about a meteor is its 
color, but I wish various broadcast media would do the public a service and 
disabuse them of this notion. It would be far better if witnesses could be 
trained to get in the habit of counting the duration accurately, and noting the 
exact time of the meteor to the nearest minute. Seeing as how almost everyone 
has a cell phone these days, and all cell phones have accurate clocks, there 
really is no excuse to get the time wrong. Yet even a casual browse of the AMS 
fireball site reveals that people clearly don't think getting the time right is 
important. And even more obvious is that most people have no business reporting 
anything about fireball starting and ending bearings and elevation angles.  
--Rob

-Original Message-
From: Meteorite-list [mailto:meteorite-list-boun...@meteoritecentral.com] On 
Behalf Of Marco Langbroek via Meteorite-list
Sent: Wednesday, November 04, 2015 12:06 AM
To: meteorite-list@meteoritecentral.com; baa...@zagami.jpl.nasa.gov
Subject: Re: [meteorite-list] Very Bright Fireball Over Europe on Halloween 
Night


A lot of folks say it looked green to them, which means it may have
been metallic;



It is a perpetuated misunderstanding that meteor colours are primarily due to 
their composition. It's a science myth inspired by High School Bunsen burner 
experiments that appears hard to kill.

While composition in some cases does have some influence on the colour, it is 
actually the composition of the atmosphere that is usually dominant for our 
perception of meteor colours.

That certainly is true for green colours. Meteor spectra show that meteors usually are 
very strong at the "forbidden" Oxygen line at 5577 Angstrom (557.7 nm). This 
line is due to atmospheric Oxygen, the same atmospheric Oxygen exitation line also 
responsible for the green colours of Aurora.

Re: [meteorite-list] Very Bright Fireball Over Europe on Halloween Night

[Beatty, Kelly via Meteorite-list]

Marco, Rob...

this discussion is timely. what you've noted is exactly my understanding. just 
yesterday I came across a high-profile blog about these fireballs, and the 
writer stated that most of the light comes from the superheated vaporized 
particle as it ablates. suspecting this was wrong, I looked in several places 
for the correct information -- IMO, AMS, RASC Handbook, etc -- and yet I didn't 
really find the physics spelled out explicitly. (maybe I was looking in the 
wrong places?) the closest I came was this post by Peter Jenniskens 
(http://leonid.arc.nasa.gov/meteor.html), which was equivocal.

clear skies,
Kelly

***
J. Kelly Beatty
Senior Editor, Sky & Telescope
SkyandTelescope.com
(a division of F+W, a Content + eCommerce Company)

617-864-7360 x22168
@NightSkyGuy


-Original Message-
From: Meteorite-list [mailto:meteorite-list-boun...@meteoritecentral.com] On 
Behalf Of Rob Matson via Meteorite-list
Sent: Wednesday, November 04, 2015 3:54 AM
To: 'meteorite-list'
Subject: Re: [meteorite-list] Very Bright Fireball Over Europe on Halloween 
Night

HI All,

Marco took the words out of my mouth. Getting tired of hearing that a green 
meteor tells you anything about its composition. I know that it's natural for 
people to think the most important thing they can report about a meteor is its 
color, but I wish various broadcast media would do the public a service and 
disabuse them of this notion. It would be far better if witnesses could be 
trained to get in the habit of counting the duration accurately, and noting the 
exact time of the meteor to the nearest minute. Seeing as how almost everyone 
has a cell phone these days, and all cell phones have accurate clocks, there 
really is no excuse to get the time wrong. Yet even a casual browse of the AMS 
fireball site reveals that people clearly don't think getting the time right is 
important. And even more obvious is that most people have no business reporting 
anything about fireball starting and ending bearings and elevation angles.  
--Rob

-Original Message-
From: Meteorite-list [mailto:meteorite-list-boun...@meteoritecentral.com] On 
Behalf Of Marco Langbroek via Meteorite-list
Sent: Wednesday, November 04, 2015 12:06 AM
To: meteorite-list@meteoritecentral.com; baa...@zagami.jpl.nasa.gov
Subject: Re: [meteorite-list] Very Bright Fireball Over Europe on Halloween 
Night

> A lot of folks say it looked green to them, which means it may have 
> been metallic;


It is a perpetuated misunderstanding that meteor colours are primarily due to 
their composition. It's a science myth inspired by High School Bunsen burner 
experiments that appears hard to kill.

While composition in some cases does have some influence on the colour, it is 
actually the composition of the atmosphere that is usually dominant for our 
perception of meteor colours.

That certainly is true for green colours. Meteor spectra show that meteors 
usually are very strong at the "forbidden" Oxygen line at 5577 Angstrom (557.7 
nm). This line is due to atmospheric Oxygen, the same atmospheric Oxygen 
exitation line also responsible for the green colours of Aurora.

So green meteor colours are likely atmospheric in origin and say little about 
the meteoroids' composition.

- Marco

-
Dr Marco (asteroid 183294) Langbroek
Dutch Meteor Society (DMS)

e-mail: d...@marcolangbroek.nl
http://www.marcolangbroek.nl

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Re: [meteorite-list] Very Bright Fireball Over Europe on Halloween Night

[Rob Matson via Meteorite-list]

HI All,

Marco took the words out of my mouth. Getting tired of hearing that a green
meteor tells you anything about its composition. I know that it's natural for
people to think the most important thing they can report about a meteor
is its color, but I wish various broadcast media would do the public a service
and disabuse them of this notion. It would be far better if witnesses
could be trained to get in the habit of counting the duration accurately,
and noting the exact time of the meteor to the nearest minute. Seeing as
how almost everyone has a cell phone these days, and all cell phones have
accurate clocks, there really is no excuse to get the time wrong. Yet even
a casual browse of the AMS fireball site reveals that people clearly don't
think getting the time right is important. And even more obvious is that
most people have no business reporting anything about fireball starting
and ending bearings and elevation angles.  --Rob

-Original Message-
From: Meteorite-list [mailto:meteorite-list-boun...@meteoritecentral.com] On
Behalf Of Marco Langbroek via Meteorite-list
Sent: Wednesday, November 04, 2015 12:06 AM
To: meteorite-list@meteoritecentral.com; baa...@zagami.jpl.nasa.gov
Subject: Re: [meteorite-list] Very Bright Fireball Over Europe on Halloween
Night

> A lot of folks say it looked green to them, which means it may have been
> metallic;


It is a perpetuated misunderstanding that meteor colours are primarily due to 
their composition. It's a science myth inspired by High School Bunsen burner 
experiments that appears hard to kill.

While composition in some cases does have some influence on the colour, it is 
actually the composition of the atmosphere that is usually dominant for our 
perception of meteor colours.

That certainly is true for green colours. Meteor spectra show that meteors 
usually are very strong at the "forbidden" Oxygen line at 5577 Angstrom (557.7 
nm). This line is due to atmospheric Oxygen, the same atmospheric Oxygen 
exitation line also responsible for the green colours of Aurora.

So green meteor colours are likely atmospheric in origin and say little about 
the meteoroids' composition.

- Marco

-
Dr Marco (asteroid 183294) Langbroek
Dutch Meteor Society (DMS)

e-mail: d...@marcolangbroek.nl
http://www.marcolangbroek.nl

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Re: [meteorite-list] Very Bright Fireball Over Europe on Halloween Night

[Marco Langbroek via Meteorite-list]

A lot of folks say it looked green to them, which means it may have been
metallic;



It is a perpetuated misunderstanding that meteor colours are primarily due to 
their composition. It's a science myth inspired by High School Bunsen burner 
experiments that appears hard to kill.


While composition in some cases does have some influence on the colour, it is 
actually the composition of the atmosphere that is usually dominant for our 
perception of meteor colours.


That certainly is true for green colours. Meteor spectra show that meteors 
usually are very strong at the "forbidden" Oxygen line at 5577 Angstrom (557.7 
nm). This line is due to atmospheric Oxygen, the same atmospheric Oxygen 
exitation line also responsible for the green colours of Aurora.


So green meteor colours are likely atmospheric in origin and say little about 
the meteoroids' composition.


- Marco


-
Dr Marco (asteroid 183294) Langbroek
Dutch Meteor Society (DMS)

e-mail: d...@marcolangbroek.nl
http://www.marcolangbroek.nl
-
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Re: [meteorite-list] Very Bright Fireball Over Europe on Halloween Night (2)

[Marco Langbroek via Meteorite-list]

The recent spade of very bright fireballs is due to the Taurid meteor stream by 
the way, which every 5-6 years shows enhanced activity of this kind.


- Marco


-
Dr Marco (asteroid 183294) Langbroek
Dutch Meteor Society (DMS)

e-mail: d...@marcolangbroek.nl
http://www.dmsweb.org
http://www.marcolangbroek.nl
-
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