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

From: Rob Matson <mojave_meteorites_at_meteoritecentral.com>
Date: Wed, 4 Nov 2015 00:53:35 -0800
Message-ID: <000701d116de$4a563710$df02a530$_at_cox.net>

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-bounces at meteoritecentral.com] On
Behalf Of Marco Langbroek via Meteorite-list
Sent: Wednesday, November 04, 2015 12:06 AM
To: meteorite-list at meteoritecentral.com; baalke at 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: dms at marcolangbroek.nl
http://www.marcolangbroek.nl
Received on Wed 04 Nov 2015 03:53:35 AM PST