Society for Popular Astronomy

The Daily Mail are carrying a report on the upcoming auction (18 Aug 2009 11:00) of part of Rob Elliott's meteorite collection.

As Rob says...

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David Entwistle

For anyone wanting to collect meteoritic dust ( which descends through the atmosphere all the time ) leave an open jar of water outside for a long time, then, insert a magnet to pick up the metallic dust.
I've never tried it myself, just read about it somewhere.

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brian

Brian: Sadly, this 'water-jar' method, and other ideas for surface collection of supposed meteoritic dust, are generally unworkable, since most of the dust will be lower atmospheric contaminants. The only real chance for such collection methods to work is in very remote places far from man-made activities, and even then the collection rates are so small for genuine meteoritic fragments, it's hardly worth the effort. Of course, each possible dust particle would then have to be rigorously tested to confirm it was extra-terrestrial, even so.

Alastair McBeath,
Meteor Director, Society for Popular Astronomy.
E-mail: <meteor@popastro.com> (messages under 150 kB in size only, please)

Could somebody please explain the above text, I thought 21 had been recorded in the UK?

http://tin.er.usgs.gov/meteor/metbull.php

Just put in UK and click search.

Trev.

Hi Trev,

There's a subtle distinction between a "fall" and a "find". The majority of meteorites recovered in the UK have been from observed "falls".

Rob has recovered two meteorites which were not directly associated with any observed fall. The remaining finds have not been classified as true meteorites.

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David Entwistle

Dave.

Thank’s for the clarification, it all makes perfect sense now.

Trev.

Why David?

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Andrew
Eyes, binoculars, DSC-F828

There's no place like 127.0.0.1

Hi Goodtime,

That's a good question and not one I'm able to answer satisfactorily.

The objects listed by the Meteoritical Society, that have not been classified at meteorites have been classified as either:

Pseudometeorite: An object that has been claimed to be a meteorite, but which is nonmeteoritic in origin.

or

A doubtful object: Designates an object for which if there is significant uncertainty over whether it is a real meteorite or, in some cases, whether it ever existed.

I can only assume that all objects submitted for classification are kept in the database and classified, regardless of the meteoric origin, or otherwise.

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David Entwistle

Is every other meteorite found in the UK that questionable? Even when the fall has been observed? Almost makes me want to ask "what is Rob Elliott's position in the Meteoritical Society?" but I won't...

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Andrew
Eyes, binoculars, DSC-F828

There's no place like 127.0.0.1

It's important to note the time frame over which the reports have originated - many are hundreds of years old. The acceptance that meteorites have a natural, but extraterrestrial origin is relatively recent. The proportion of reports accepted as genuine improves dramatically as our understanding of the phenomena improves.

If your aren't already familiar, it's worth reading the fascinating history of some of the reports to get a feel for events.

It just goes to show how rare and elusive a true meteorite is. You could say that finding a meteorite, which wasn't observed to fall from the sky, makes finding a "needle in a haystack" seem trivial by comparison. Especially in the UK's damp, and green landscape.

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David Entwistle

This is quite interesting, surely they are enough observed falls that have been collected and analysed under say an electron microscope to use as a cross reference against the non observed falls.
I would have expected that this would have been a priority in checking them, if they are genuine then they must fall into a classification type of the observed falls, lack of funding perhaps?

http://www.meteoritemarket.com/type.htm

but an old find/fall or whatever has to have as great a chance of being a meteorite as those claimed by Robb Elliott, I mean those that he found could have just as easily lain there for hundreds, even thousands of years prior to him picking them up and declaring them 'real'? It sounds rather strange to me...

I will follow your link...

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Andrew
Eyes, binoculars, DSC-F828

There's no place like 127.0.0.1

Proving meteoric origins is ok for the nickel-iron ones due to the relatively easy experiment to reveal the distinctive pattern when etched and polished.- Widmanstatten Pattern (think that that is the spelling!). The stony ones are obviously less "provable".
"Falls + Finds" are pretty obvious, just "finds alone" are more difficult and probably none are known from Britain (I think - do not have the catalogue to hand to check) but plenty from Antarctica and some deserts where they stand out on the surface.
All putative meteorite finds brought to the Booth Museum and Foredown Tower were not - nearly every one one was a lump of Marcasite (Iron Sulphide) common on the chalk South Downs - one was a bit of roadstone covered with tar. It is fair to say, to some non-expert who brings in a find, "it will not be a meteorite" even before you look at it.
Re the "meteoric dust". A colleague had a go at trying to locate this, not by the water method mentioned, but when he cleaned out his gutters. By drying the gunge and careful magnetic extraction, he located a large number of small shiny metalic balls - using the microscope. Obviously it was impossible to test them to prove that they were all meteoric but general consensus suggests that they could be. It is not as if there are iron smelters down the road - or probably anywhere in this island anymore! maf

I've had a quick look through the catalogue of meteorites and it seems that the English records listed as "doubtful" are derived from historical documentary evidence alone and no physical samples remain. So, perhaps the evidence was considered good, that some unusual event had occurred, but it is not possible to show any scientific evidence of a meteoric connection.

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David Entwistle

Professor Monica M. Grady, editor of the fifth edition of the Catalogue of Meteorites, confirms the nature of the problem. In an e-mail she writes:



I'd like to express my thanks to Professor Grady for the clarification.

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David Entwistle