Editing 1723: Meteorite Identification
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− | '''Note:''' Clicking on the image on xkcd (click the date above the comic to go to the comic on xkcd) takes you to the | + | '''Note:''' Clicking on the image on xkcd (click the date above the comic to go to the comic on xkcd) takes you to the ''[http://meteorites.wustl.edu/check-list.htm Meteorite or meteorwrong? Self-Test Check list]'' flow chart at the [http://eps.wustl.edu/ Department of Earth and Planetary Sciences] at {{w|Washington University in St. Louis}}. |
==Explanation== | ==Explanation== | ||
− | {{ | + | {{incomplete|Needs an explanation of the Title text}} |
− | + | {{w|Meteorite|Meteorites}} form when a {{w|meteoroid}} survives entrance through the Earth's atmosphere as a {{w|Meteoroid#Meteors|meteor}}. They a thus very rare rocks that come from space, and can stem from broken {{w|asteroids}}, the {{w|Moon}}, and sometimes (very rarely) even from {{w|Mars}}. | |
− | + | The {{w|flowchart}}, though facetious, would actually work the vast majority of the time a person picks up a rock and believes it to be a meteorite, since, given any single rock one finds on the surface of the earth, it is almost definitely not a meteorite. | |
− | + | Flowcharts are often used ([[:Category:Flowcharts|also in xkcd]]) to give the inexperienced a step-by-step process to follow, but meteorite identification is very difficult, so the brevity of this flowchart in a way pokes fun at the need for a flowchart to identify meteorites, since laypeople are not experienced enough to confirm that a rock is indeed a meteorite. The image links to a [http://meteorites.wustl.edu/check-list.htm more detailed flowchart] which, among other things, links to a [http://meteorites.wustl.edu/realities.htm long list] detailing the many things that must be taken into consideration in order to confirm that a rock is a meteorite. | |
The authors of those resources notes that they have received many rock samples and photos (or even personal visits) from people claiming to have discovered meteorites and thus they would likely benefit from just providing people the shortcut flowchart from Randall, as a way of saying, "leave meteorite identification to the professionals." | The authors of those resources notes that they have received many rock samples and photos (or even personal visits) from people claiming to have discovered meteorites and thus they would likely benefit from just providing people the shortcut flowchart from Randall, as a way of saying, "leave meteorite identification to the professionals." | ||
− | + | In the title text [[Randall]] mentions that the comic is a link to the more detailed ''[http://meteorites.wustl.edu/check-list.htm Meteorite or meteorwrong? Self-Test Check list]'' flow chart at the [http://eps.wustl.edu/ Department of Earth and Planetary Sciences] at {{w|Washington University in St. Louis}}. He also mentions his favorite part of this "real" flow chart, which is the part where if anyone saw the "meteor" fall then it is 'NOT A METEORITE.' What he most likes about it it, that this is not a mistake. | |
− | First of all the chance of actually being near a falling meteorite is exceedingly small. From the | + | First of all the chance of actually being near a falling meteorite is exceedingly small. From the flow chart is a link to a [http://meteorites.wustl.edu/realities.htm 64 point long checklist], which basically all ends in "..., then it's not a meteorite." In point 3 is noted the following: |
:Since 1900, the numbers of recognized meteorite "falls" is about 690 for the whole Earth. That's 6.3 per year. Only 98 of those occurred in the US. That's less than 1 per year. Even when a meteorite is observed to fall, experienced meteorite hunters may find only a few stones when hunting dawn to dusk for a week. | :Since 1900, the numbers of recognized meteorite "falls" is about 690 for the whole Earth. That's 6.3 per year. Only 98 of those occurred in the US. That's less than 1 per year. Even when a meteorite is observed to fall, experienced meteorite hunters may find only a few stones when hunting dawn to dusk for a week. | ||
− | Second, meteors | + | Second if you did see a meteor then if you find a rock it is not the meteorite formed by that meteor. Because, except for meteors large enough to form a big crater then the speed of the meteor will be reduced to below glowing point long before it reached the ground, and then it will stop glowing. At this point it is very small and too high up for a human to see it when it's not glowing (also in daylight) and thus there are no chance of following it with the naked eyes. Once it reaches this point it will fall with terminal velocity to the ground, and not make any deep mark when it lands. If close by it may be possible to hear a swish and a thunk. This is what happened with the 690 events mentioned above. All this is described on [http://www.meteoritemarket.com/metid2.htm How to Identify a Meteorite] from [http://www.meteoritemarket.com/ The Meteorite Market] which is linked in point 48 in the table from Washington University. |
− | What Randall finds so funny about this part of the | + | What Randall finds so funny about this part of the flow chart is that there are three arrows leading to the question did someone seem it fall, but from there only "yes" is possible, and then this gives the result "not a meteorite." This indicates that if you have found a rock, that has no dark crust or [http://meteorites.wustl.edu/id/regmaglypts.htm regmaglypts] (the options that by saying no takes the user to the question about seeing it fall), then it is not a meteorite, and then the only reason people might still believe it to be a meteorite must be because someone saw it fall. Since seeing it fall rules out that it could be a meteorite there only need to be this single option left... |
− | If the rock actually | + | If the rock actually have those thumbprint like impressions on the surface (that scientist calls {{w|Glossary_of_meteoritics#Regmaglypts|regmaglypts}}) then the flowchart actually asks to see the stone. |
− | See also [[1405: Meteor]] about how people | + | See also [[1405: Meteor]] about how people mistakes the words for meteorites with meteor. The many misspellings of meteorite is mentioned in point 63 in the table. |
==Transcript== | ==Transcript== | ||
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:Start | :Start | ||
:No, it's not a meteorite. | :No, it's not a meteorite. | ||
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{{comic discussion}} | {{comic discussion}} | ||
[[Category:Flowcharts]] | [[Category:Flowcharts]] | ||
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