Meteorite Self-test check-list

https://sites.wustl.edu/meteoritesite/items/meteorite-fusion-crust/

by accrual • 2 years ago

77 21 2 years ago

sites.wustl.edu

Titan2189• 2 years ago

Why is the "Did someone see it fall?" included? Sounds like that question is irrelevant

CommitSyn• 2 years ago

Because identifying meteorites is very difficult and almost always requires taking them to a university for analysis.

jumploops• 2 years ago

This meteorite fell last Thursday, tracked with cameras[0].

[0]https://www.reddit.com/r/meteorites/s/pPlwNsizEE

snitch182• 2 years ago

There are 365 degree cameras in every larger populated area. The people operating them report to a central database. I once saw a fireball going to the supermarket at night. It was in the database a couple hours later. It is like winning the powerball lottery if you would find a meteor not seen by anyone.

lupire2• 2 years ago

Those are impressive cameras!

But that's not what we're talking about here. https://news.ycombinator.com/item?id=39790272

extraduder_ire2• 2 years ago

If you see a meteorite "fall" or something that looks like a shooting star, you aren't going to find it.

If it's moving fast enough to be a glowing streak, it's going to land hundreds of miles away from you. If it's near enough that you found it, you have no chance of seeing it land (sort of like seeing a bullet whizzing past your head).

Keep in mind that this flowchart is to cut down the number of people who contact this person wondering if their rock is a meteorite, which it almost always is not. I first learned about this chart from this: https://xkcd.com/1723/

lupire2• 2 years ago

Commenters didn't look at the chart to understand your question.

It's just a mistake in the chart.

"No" should point somewhere else to continue classifying. Also "someone" is ambiguous -- it could mean "someone nearby" (not meteorite) or "someone far away" (possibly meteorite).

https://sites.wustl.edu/meteoritesite/items/some-meteorite-r...

anamexis• 2 years ago

I don't think it's a mistake - just a cheeky note that if you "saw it fall," you probably didn't. Your own link supports this.

If you saw a meteor and later found a stone, then the stone is not a meteorite
Meteorite fragments land far from where you last saw the meteor and there is no way that observers at a single point on the Earth’s surface are going to find fragments of the meteorite. It requires triangulation from several viewpoints, usually with cameras.

dang2• 2 years ago

We changed the URL from https://sites.wustl.edu/meteoritesite/items/self-test-check-... ("Do this first – Self-test check-list") to the more informative related page, but both are worth taking a look at!

extraduder_ire2• 2 years ago

The title should probably also be changed to "Meteorite fusion crust" or something like it.

dang2• 2 years ago

Ah yes, I forgot that earlier. Thanks!

toss12• 2 years ago

I read another article which asked strongly that people NOT use rare earth, neodimium or other strong magnets on meteorites, so this should perhaps be emphasized more strongly.

>You say that your rock attracts a magnet or a compass. Most (>95%) of meteorites (irons and ordinary chondrites) attract cheap magnets because they contain iron-nickel metal. Many terrestrial rocks, however, contain the mineral magnetite, which also attracts a cheap magnet. (Do not use a rare-earth magnet; a cheap “refrigerator magnet” will attract a meteorite.)

The reason is that the strong magnets can re-orient the magnetic properties of the meteorite, ruining it for some aspects of tests or research. Seems polite to not ruin the thing for research for only a few seconds of 'that's cool' sensation.

kibitzor• 2 years ago

To add: there's ongoing research to "reverse-engineer" the magnetic properties of certain meteorites that contain tetrataenite [0], which is as strong as a rare-earth magnet, but requires no rare-earths, but takes millions of years to make[1]. I studied techniques to speed this process up in the lab over a decade ago when this was new, and got to handle meteorites in the process.

A less "magnetically invasive" way to check if a material has magnetic material would be to put a compass nearby (as recommended by the site). Also, one could put a rare earth magnet on a string, watch it align to the earth's field away from the rock in question, then bring it carefully close to the meteorite seeing if it settles to a newer direction. This would still expose the meteorite to a magnet, but a very small field vs checking if something sticks.

[0]https://www.cam.ac.uk/research/news/new-approach-to-cosmic-m... [1]https://en.wikipedia.org/wiki/Tetrataenite

toss12• 2 years ago

Great extra detail -thx!

Sounds like fun research and a quick skim seems to indicate success in fabrication - congrats! Did you get to the point of making magnets and if so, how strong did they get?

baxtr• 2 years ago

Nice check-list. I wished it had also some “it’s not a meteorite but this instead” pathways included.

Simon_ORourke• 2 years ago

1. Are you in the Antarctic?

2. Is that a stone on top of all the snow and ice?

3. That's a meteorite

adonovan• 2 years ago

A friend (whom I shall not name) with the British Antarctic Survey once told me that the mornings after a meteor shower, they would take a Twin Otter plane out low, looking for dark rocks against the snow, land, gather, repeat, and finally sell the rocks on eBay.

Your tax pounds at work. :)

codetrotter• 2 years ago

I’m ok with this

xandrius• 2 years ago

Unexpected bread: loved it.

pugworthy• 2 years ago

R/Arrowheads could use something like this. “JAR” (for Just A Rock) is not an uncommon reference for things that are in fact, just a rock.

formiko• 2 years ago

https://github.com/anthonyehrhardt/Meteorite-self-test-check...

Meteorite Self-test check-list

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