About science; About meteorites
This is about science produced by the California Institute of Technology and originally broadcast by station KPCC in Pasadena California. The programs are made available to the station by a national educational radio. This program is about media rights with host Dr. Albert Hibbs and his guest Dr. Irene Goddard of the Kel-Tec geochemistry Department. Here now is Dr. hip throughout recorded history meteorites held a place of special mystery and it's very likely that man discovered iron first in the form of meteorites. As a matter of fact some languages show this by the similarity of the words that they use for iron and star. And now although we certainly know a considerable amount about meteorites more than we did then we still have a few mysteries that haven't quite been dispelled. And to tell us about some of the new research on the nature of meteorites as well as some of the old stories that have followed them through the years we have as our guest Irene Goddard of the geo chemistry
department at Caltech and Irene let me start out by going back to some of these old tales was it always pretty much understood that meteorites were a heavenly phenomenon and did indeed come from the sky. Yes I think that there was no question to the ancients that they did come from the sky since they saw them fall and they accept it without any qualms. And consider it to be a gift from the gods or some swords in their Oculus manifestation. And they did indeed call. Iron iron from heaven for example Hittites called it that and Egyptians ancient Egyptians called it metal from heaven and then the Greek word for irony. See there are US which is similar to Latin so there are not faint star which means star. So there was a definite connection always lines between
layers and so that the origin wasn't others very much. For quite a while and then first start I was doing that question and he suggested that the probably were aerial phenomena and I mean he sees are just a media which came out of the air you know all the day Arjun he's thought they were connected with the Stars and then scientific controversy. And then a few lonely voices every now and then such as for itself says the 16th century. Was quite convinced that the Stones may descend from having the exhibit no one listened to him very much because by Middle Ages people still thought that they were in the different heaven but that there were signs of God's anger but they had a religious meaning throughout as well obviously as this come from. Just in. And so then when the Enlightenment period came when the emphasis was very much on the empirical method in science and
since most scientists certainly had not witnessed meteorites fall through there are just completely discounted all reports even those that were there well substantiated. Also the change was not to simply reject religious or mythological it was to reject the whole idea recess. And people such as the famous French chemist Lev was here actually analyzed by the blue say which is known to be a meteorite and found it to be a pyrite which is a terrestrial rock. And in sending incentive to whole committee from the Paris Academy of Science and the memorandum which concluded that stones are supposedly cosmic origin were ordinary terrestrial rocks struck by lightning and that the falling of stones from the sky is physically in part. Sounds a little bit pronounced model I thought our unscientific
groupie. Exactly and the unfortunate thing is that then that carries if the authorities are impressive enough then they carry with them a lot of other scientists just who get on the bandwagon. And so there were a whole series who even in sync in one thousand francs is a meteorite shower fell right before the eyes of the excuse of the mayor and the whole city council in Barberton France and they made it this is your money and recorded in the city records and then there are to learn other French Sanctus said how sad it is that the entire municipality enters folktales upon official records presenting them as something actually seeing while they cannot be explained by physics nor by anything reasonable. And so this continues for quite a while and even into the 19th century even though by the turn of the century thanks to one particular physicist Hogmanay
who had enough courage to go against the current and did write a book explaining in a very reasonable fashion how meteorites could come from could be explained as outside. Exactly. But even then so some scientists by then already believed it. But there. In 18 0 7 for example a stone meteorite shower film your western Connecticut and was extensively described by professors Kingsley in Salem and of Yale. President Thomas Jefferson when he heard of this. Is reported to have commented that he found it easier to believe that Yankee professors would lie than that stones would fall from heaven. So it takes a long time. What is the difference between a meteorite a meteorite.
For practical purposes we use the definition meteorite is something that is a shooting star that makes a flash in the sky. And meteorite. Is something large enough to pass through the atmosphere and not burn up and reached the ground as a large enough chunk so that it can be found on the planet. Not the only difference between them and actually you know because the media are sort of to arise he's at least in their behavior. There are some that are periodic that coming swarms at the certain time of the year which means that the earth when it goes around the orbit once a year crosses and runs and we were in meteor stream years and these are the returning Riady meteor showers. And they most likely are the debris of comets.
I see this is what's left over from common rail from Comet had some libraries act going around the exactly and then they gradually get dissipated and this is why the showers vary from year to year and eventually the exact position on the origins and then on the other hand there are sporadic so-called sporadic movie orders that just appear. At any old time at random and those may well have the same origin as meteorites except that they are smaller and growing up in the atmosphere so there are clearly them from these two kinds of behavior that must be reached to origins. Two things one how often does a meteorite one that is big enough to hit the ground. It often is How has happened. Well it's difficult to to to say definitely because the earth is covered by water such a large extent and of course some of the areas are still uninhabited but yes
with calculating from the most densely populated areas such as India Japan Valley inordinately were especially many falls have been reported mainly because there are some people around who would steal them and other theoretical considerations. Harrison Brown has calculated that there are probably about five hundred sixty year I'd false a year all or all of the earth. All right so then dividing it. It would be one point one false per year per one million kilometers squared. An area of 1000 kilometers and about 600 miles square and you get about one a year. Right you have to pick up right of course this is this is just an average and actually they don't fall evenly distributed. I suppose big ones are much more rarely big ones. It's estimated again that it's probably every few hundred years
that a large one falls and that's a large one such as for instance the Russian meteorite shower which fell I believe in one hundred forty seven or thereabouts and it was several tons worth of material were collected and it was calculated calculated that several hundred tons may have been evaporated during the flight. Because it's a very large mass and therefore a tremendous energy would be converted to vapor. This is the reason that sometimes these very large meteorite craters of which there are a number identified by now instantly has only been 60 years since it was first suggested that meteorites may make craters. Right. And so more and more are being discovered this being of maturity origin finally allowed to be thought of that.
Exactly. All the Indians knew better about the accounting the ABLA as a matter of fact the name Canyon Diablo in Spanish means the Devil's Canyon or was this recognized. Well you Indians had its relations I suppose that a fiery God had descended from the sky and that spot how long ago was a sort of hang with estimated it was 5000 years ago. That's a long time for a legend but it might have been a very impressive sight what happened exactly. Something is as big as that of startlement legend good Michael Whelan and. Then there are there are a series of creators in Australia which are estimated to be only about a thousand years old. And yes three and Aborigines have a name for it and that is sort of a combination of words. Sky Fire devil stone I see. And that whole area is deluded. They don't go near them. So they also recognize that this would happen.
I suppose that actually very few of these are seen as they fall most of them must be picked up at some later time is there any estimate of how many arms are picked up right away sort of hot out of the sky. How many of yes are found at some later time. As a matter of fact one of Dr. Brown's graduate former graduate students Dr. M.R.. Did such a calculation using a private catalogue which was. A very good catalogue include a great many of the known falls and fines and you can find out. Yes yes I want to go back up on the ones that later on you. You grinding thing it looks strange and you take it somewhere inside and had to be a meteorite. So far as he derided the years for making hundred nine hundred fifty three fifty year periods. And he found
that in the period from 800 waiting 50 60 70 percent of falls were reported within five years which is quite remarkable since it was only the turn of that century that they decided to believe. And then within the next ten years an additional 6 percent were reported and then next 10 years again four more percent so it was 77 percent reported after 20 years. And then 30 years as 2 percent in 50 years 92 percent reported. Now how does he know that not all of them reported it because some were seen to fall and then and even were picked up and identified as meteorites but were never recovered. For example to go back to this Enlightenment period the pressure was so hard that the you know to be identified with the people on the right side and not the superstitious ones that the neurologist I believe born with his name in Vienna where he
had already started a pretty good collection was called the Imperial collection of all kinds of strange objects and among them were a lot of meteorites. And he was afraid that his reputation was at stake that he was collecting these silly things and so he threw them all out. And so they were recorded and could never be three. So then as we go on in years. We find that for instance from one hundred nine thousand fifty. Within the first five years and the 1 percent get reported and then next 10 years it comes to 86 and then within 20 years 95 percent are reported in the first five years of that category and that's the ones that were actually seen to fall and the person who found them just didn't get around to telling us or didn't know you know where her daughter is that this is a very important factor. And well very critical actually because it has been estimated that for instance the United States only
one knew me here right. For a year and gets into the hands of scientists who are dying to get their hands on it before we want to further master them. If someone should find see immediately or for one can find a meteor meteorite meteorite or go out and find it. What should you do. Well it does advance the cause of magics. Fortunately there are two definite places where he could. The right thing. And tell them about it and send in the thing to be identified without any charge. One is the Smithsonian Institution Astrophysical Observatory in Cambridge Massachusetts and was director and the person to write to is Dr F. L. Whipple W. HIPPA stock to the Smithsonian astronomical writer or Dr. E.P. Henderson
who is curator of neurology and petrology at the US National Museum in Washington for us National Museum in Washington Dr. Henderson. Dr. Whipple of the Smithsonian in Cambridge Smithsonian buys them and in United States. The person on whose property the meteorite is found is the legal owner of it. In other countries depending on if was of any value to say let it lie there and staking it out so that somebody can come around around it and so on. If it's only for a very short time. On one hand yes it would but actually perhaps it would be better to take a picture of it in place before taking it out. Because one reason that some need arise it's important to get them very quickly is because they have been doing studies of some of the reactive guy's attempts
which would tell about their cost me crazy exposure ages because I was just running for it. Yes because and also if there are fragments then different. Ones have been found to have different ages. For instance this way and some of the isotopes have short lives so and so that if one waits then at least that part is what lost completely forget them. Yes when he was in so one should take pictures and of course if you actually see it fall then every little detail that one can possibly remember is very important and one should write it all down immediately afterwards because it's very easy to forget things one time as another fact. From. The point of view of our research the time is extremely important and so I would even suggest that one check of the personal watch
with with the telephone Tang or something like that because it can be that important. And then one should remember and it has been suggested and I think it's a very good idea to make a sketch because very often if the meter idea is large enough it will appear as a bolide as a big fireball in the night sky and will make a trail and sometimes chunks will break off and fall and all these things will be noted and recorded and it will be then good to make a sketch with you and people have been showing a path. Exactly because it's very difficult to to tell the orbits of asteroids since usually people that do happen to see them are not trained observers so you're workers looking at the orbits of meteorites. Yes Dr. Brown I did one study. The frequency of meteorite falls because for quite some time it was known that they do seem to fall not
quite evenly at random. They come in cycles but there seem to be and maxima and minima for example there are seasonal variations of one in about March and another in summer and just variations of people finding a Mars. Well this is something that of course we had to consider and that it was found that even though certainly it does have some influence for example in Europe. If you look even at the days of the week fewer falls like by about 30 or 40 percent fewer calls are recorded and Sundays. Because people working in the fields and the other hand. And then then to the sort of area is very important because for example in India although there were very many meteorites
reported but a very large completely out of the ordinary proportion of them were false. Because he is very dense vegetation and so forth were in Chile where there were about 30 or 40 and none of them were seen to fall. But because it is dry they can and yes they can easily be seen and because it is dry they they are preserved longer and this is another important point of these two major categories. There are two very distinct classes. Some are made almost entirely of our nickel and others are stony meteorites. Actually I am the one you hear about most of the time a famous Army are these the comet known as another fact most of the faults that are seen are of the other type. Stone at the stone meteorites But the irony here rights are easier to identify and they're often very look very
impressive because they're very very heavy. And this is why it's much easier to identify one when you find one and sometimes they look black and they have sort of like fingerprints like invitations made by thumb which is because of melting while they are flying through space only once have called the stony ones sometimes may look like an ordinary rock right of the spot exactly and so much larger proportion of the finds are ironies and much larger proportion of the falls are Congress but it's thought that. Probably they are 50/50. I see but this is this is not definite because again we just don't have enough data. But the analysis of when they fall and where they come from does indicated that this variation from a concentration in spring and late summer is a real concentration. Yes and not only that when we looked at different
classes and we theorize for instance among these stony once there are two again very distinct classes which we call low iron high iron nickel. Most of them aren't even in the stone Oh yes. Throughout there. Well practically all of them have some. And so when we looked at these two different concepts redly it seems that some of the Maxima some of the peaks. Our due to the high iron variety and others to the low iron. So this which is very important because it would suggest that they do behave slightly differently that this is a grouping of actual Yesin Arma rather exact observations and then they will be looked at longer periods. For example a five year period seems to have a very high peak and this is to be expected if indeed there should be a meteorite stream through which the earth then would pass every year like to a comet pass. However if
the need to rise within their orbit are not distributed evenly all around but are in clusters then only every now and then will we again come to the same splash and meet the class there. And there seems to be some indication of that too. If meteorites move in orbits like this it sounds very much like orbits of asteroids or connection. There seems to be a very definite connection and a. Great majority of students in your eyes believe that they indeed come from the asteroid belt. Let's of course concentrate mostly between Mars and Jupiter a long way from here. Yes except that because Jupiter has such a large mass it perturbs the orbit of asteroids and every now and then one will stray far enough. So that it's me approach Earth. Actually there are several large ones and we're limited again until we can go out in space and look at the belt
itself by what we can see with telescopes. And very often the orbits are very eccentric and during the days difficult to see them because they're not very large but there are several who do approach the earth fairly close I believe there is one that is coming next year. But the calculation so that it's necessary the more observations you have of of an asteroid the more occasions the more careful you can calculate the orbit. And because these are seen each time there are new calculations made. What I am I believe I read in the paper recently that Dr. Herrick from UCLA had done the calculations and announced it will be all about million miles or so. Just as we're used to now between the planets. But it must be very difficult to get the orbits of meteorites when all you see is the tail and the second guess
it was extremely difficult and as another fact the only one that has been carefully calculated was one in Czechoslovakia the Seagram fall. Quite recently in 40 something and it so happened that two cameras were photographing the sky not just by law to say precisely at 2 stations 40 kilometers apart and they both photographed it and so it was possible to calculate it well and it turned out to have an asteroid will orbit so at least in the one case we assume there is another one the shower that very large shower in eastern Siberia. I first think of a Russian calculated the trajectory from very many reports this chart was so large that turning people had seen it over a large area and so by projecting what they saw in the directions if they had seen with an eye on.
Yes and again he gets a sort of asteroidal if someone is interested and following up the study of meteorite his own becoming meteorite hunter rather and a good reference with any books that give a good background in his business. Well amateur meteorite hunter could make use of for a beginning. I would suggest two paperbacks. They're fairly recent certainly recent enough to be corrected things and one is by Fletcher G Watson. It's called Between the planets. This talks about asteroids meteorites yours comets cosmic dust the whole bit. And here is a translation of an excellent book called meteorites by Fritz hide their English translation and by a unique science series.
So between the planets by Watson and meteorites by Heidi h h e ID. And out to the second one and concentrate on the media it sounds right. It's really simple way that a person can recognize a meteorite very often they have or they call fusion crust. It's black. Fusion crust The happens during their flight through the atmosphere because they do get very hot and the outside layer becomes one foot stone as well as for the arm while the Iranians are easier to recognize because they're very heavy and black and all have a little indentation right. Right and then they have other characteristic. Things like. Living granules living is something that doesn't occur in terrestrial rocks. There are small nodules less than three millimeters in diameter and they're
made of silicate materials so that they look sort of like little beads imbedded in this and now it doesn't. And so that if you do especially one of them breaks when the fracture surface these little leaves that are sometimes one can see iron particles and that is another indication that this thing is a meteorite or a course of C1 horn you can make any notes at all about the past streak across the sky. Exactly or any of the acoustical phenomena sometimes they make noises so have a lot of. Meteorite watchers. Thank you very much every. Thank you. This was about science with host Dr. Albert Hibbs and his guest Dr. Irene Goddard of the geochemistry department at the California Institute of Technology. Join us again for our next program when two more members of the
- About science
- About meteorites
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- California Institute of Technology
- KPCC-FM (Radio station : Pasadena, Calif.)
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- This program focuses on the scientific study of meteorites. The guest for this program is Irene Goddard.
- Interview series on variety of science-related subjects, produced by the California Institute of Technology. Features three Cal Tech faculty members: Dr. Peter Lissaman, Dr. Albert R. Hibbs, and Dr. Robert Meghreblian.
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Guest: Goddard, Irene
Host: Hibbs, Albert R.
Producing Organization: California Institute of Technology
Producing Organization: KPCC-FM (Radio station : Pasadena, Calif.)
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