Focus 580; Astronomy: The Little Book of Stars

In this part of focus 580 we welcome back to the program Jim Kaylor. He's professor of astronomy at University of Illinois. Once in a while on fairly regular basis we have astronomers on Jim and John tickle his colleague here here occasionally we talk about what you can see in the sky various times of the year. John in fact was just on last week I think and we did that. So the program today is has a little bit of a different focus. We thought that we might concentrate on what is Jim's particular area of scientific interest and expertise and that is stars. He has authored a new book which is just come out a very nice book in a very handy compact format. It's titled The Little Book of stars. It's published by Copernicus books and it is small in size but it has a good basic introduction I think to what stars are all about small but it has a big heart. Exactly so and perfect for a stocking stuffer. And this holiday season if you're if you have some perhaps on your gift list and we're talking about sort of the level of the book say maybe high school level and see who's

interested in science or interested in astronomy. This would be a good thing for them. And also let me mention that Jim will be doing a book signing at the airline a union bookstore next month January 20 ninth. It's a Monday from 4:30 to 5:30 in the afternoon in their author's corner so he'd like to get an autographed copy. You can do that. And questions of course are welcome. You want to call us 3 3 3 9 4 5 5 toll free 800 2 2 2 9 4 5 5. Has this always been a when you think about your involvement with astronomy as the attraction to stars always been there. Yeah yeah that's really what I fell in love with as a kid and always been interested in and then you often tell people what do you do. Do stars and they look at you blankly like don't all astronomers do stars as what it's all about but no I mean there's lots more. Stars are the most obvious things in in the sky. I did most of my research was done in interstellar gas clouds actually rather than stars but of course are related to stars so you get right back to the

heart of things eventually anyway. But there are people who get involved in galaxies and planetary researches there's a great depth to this subject and a lot of things that don't specifically involve stars but I sort of came back to roost in the last 10 20 years and got much more interested in stars specifically again and I love writing about them. How many are there. How many are there now. Well depends on your terms in in the naked eye sky about 8000 that the human eye can see with the naked eye over the course of the whole celestial sphere. And in the galaxy our local assembly about 200 billion of them in the visible universe although I guess somewhere around. A billion trillion. Something like that. It's it's almost an uncountable number. Hundred billion trillion. Some of you know it gets silly after he can't really conceive numbers like that. The one of the analogies it's

often used is that there are more stars in the visible universe than there are grains of sand on all the beaches of the world. Which is gives you a sense of the number that are there and that's just the visible universe the part that we can actually see. We haven't been able to see everything we may never see everything we're even counting the stars the visible stars in the sky it's a significant tasking not not to mention counting the stars in our galaxy. Well you can. We've catalogued several tens of millions that have sort of catalog names positional coordinates names the Hubble space telescope has to use faint stars for guiding and we have precise positions of huge numbers of them. And the task has been going on for. Literally millennia. You go back to ancient Greek times who were making maps of the sky and counting and recording them beginning and named them and organize the minutes it accelerated during the seventeen hundred eighteen hundreds for navigational reasons and for

astronomical reasons too and in our own century we just catalog huge numbers of them. You can't get them all in astronomy is largely a statistical science and you sample Bisbee impossible to catalog them all. Oh it just it when I talk with John the other day one of things I asked him about was fairly recently some astronomers announced that they had discovered some some more moons of Saturn and you'd think well that was close enough so that we probably should have been able to know how many there were there and get these little bitty things and they're awfully difficult to see from here you get him down a hundred kilometers or so across or just very faint little things it was a new one of Jupiter just found. That brings the total to 17 known once and undoubtedly there are more. You get down to just rocks. You know where you stop calling it a moon. We just it's if you want to think of the satellites of Saturn and the rings are made a little bitty satellite see it's got billions of them. At some point the count gets a little a little bit pointless. We're not at that point yet certainly because we're still counting the fairly big bodies the moons of Jupiter. If Jupiter

weren't there the big ones are so bright you could see them with the naked eye if Jupiter weren't there. That's just the glitter of Jupiter that prevents you from looking at him. Seen with binoculars is a bright and easily found. You talk about the fact that when you say when people talk about you say that you're an astronomer and that you are interested in stars people say well yeah of course. Another thing that maybe would surprise people is that there are a lot of different kinds of stars. And when we look up there. Basically they seemed all to look the same their you know their twinkling points. Yeah but they're they're all different they they get it's sort of like people all sort of look alike too except that they all have individual characteristics and you get to know your friends in the same is true of stars really no two of them are exactly alike. You can even see the differences with the naked eye you can see subtle colors in a range from kind of a bright bluish white to fairly orangey red and the several you can pick the red ones off fairly easily with the naked eye and they're all they're all different I got to run a

website out of the astronomy department I do a little essay on a different star every week and I have two hundred fifty of them now and a lot just the naked eye ones named ones at this point that I think in the front of it is to dedicated to showing the No 2 stars or like or something like this that they're all different and they're all fascinating in their own ways. You could make a life study and people have done this on one particular star and of course the sun is the favorite. Are there major categories when you talk about different kinds of oh yes. Yeah yeah. They've been trying to categorize them since the middle of 18 hundreds and we use one now a system now that was developed around 1890 all over a century ago that just basically they're lettered according to their their spectral characteristics but really it's according their temperatures and the old classical BFG K.M. any beginning astronomy student gets to gets to get to their annoyance gets to learn the sequence. And but the first thing any astronomer wants to know what a star what classes at noon is basically temperature class sons of G Star 6000 5000 degrees

surface absolute temperature. And there are a lot there and busy in different subtypes. You can you can spend half a lifetime looking animal when you get into the some of the very some of them don't some of them have weird chemical compositions some of them spin fast some spin slow some of their various stages of aging some are brand new Others are in the process of dying yet others are totally dead. Those mints range of me get them from only a few percent the mass of the sun up to maybe a hundred times the mass of the sun. The tremendous range of characteristics and we just happen to have a really nice one that hosts the earth very very well. The relationship between the color is determined by the temperature. Yeah yeah them almost entirely by the temperature a little bit. Chemical composition in some extreme cases but mostly by the temperature. The red ones are the cool ones. Temperatures go down around 2000 degrees or so for most standard stars they can get lower fact they are discovering now sort of sub star stars that are

are really who don't have enough mass to run the thermo nuclear fusion that powers stars like the sun and you get down the temperature a self-cleaning oven on some of these things you know about a hundred degrees right now as the is the recently discovered minimum at the surface. They're not even visible they wouldn't even be visible of the ITA telescope you have to use infrared detectors to find them. So it is just that that's one of the things that's fascinated me about him is his fantastic range of properties and the ability again of the theoreticians who have been very successful in doing this over the last 50 years to string the different kinds together into an evolutionary flow so you can see what's going to happen to him from birth to death we have a very good idea of what's going to happen to the sun over the next six seven billion years. And it ain't pretty. Fortunately we won't be here to watch it. It'll take a long time yeah. That's one thing we don't have to worry about. Our guest this morning is Jim Kaylor. He's a professor of astronomy University of Illinois and has authored a number of books including recently the little

book of stars published by Copernicus books answering all of your basic star questions right here in this book. And of course if you have some basic star questions or other astronomy questions you can can we you know about anything at the 3 3 3 9 4 5 5 toll free 800 2 2 2 1 4 5 5. Well perhaps just as a way of talking about what the life cycle of a star is. Why don't we talk about the sun. Where did the sun come from. You can look into the Milky Way. Those of you who are out in the country can actually see the Milky Way away from the bright lights of Champaign-Urbana which just blotted out completely. It's pretty much still overhead an early evening through Cassiopeia and so on although it'll get a little bit drab or over the winter it's just circle of light around the sky. That is the disk of the galaxy and you can view out and say an August evening some time out in the woods in the country and you look up you see the Milky Way's got tremendous structure to it it's not just a simple white band. There's all kinds of

holes and lanes and dark stuff. Those are dark dusty clouds that block the light of the background. And in those clouds the temperature drops so low that stars condense so they get formed out of those clouds sort of chaotically and randomly and we've been pretty successful and in figuring out the processes that actually do it's a son was born about four and a half billion years ago out of a cloud similar to that it's long lost its birth cloud of course or any siblings that might have had. They tend to be born in groups in these these some of these huge clouds in in the hundreds or thousands even in the hundreds of thousands of times and it condenses to the point where it fires up the fusion of hydrogen to helium in the core temperatures got to be up around 10 million degrees or so and that stabilizes the star and the sun's been pretty stable now for the last almost five billion years as a result of that thermo nuclear fusion that's what generates the energy of the sun. And we got about another five billion years left calculations takes about 10 billion years from

beginning to end to use that core hydrogen upturn and all of the helium and then the fun starts because the core collapses and then the sun swells and it'll probably swallow Mercury Ill probably get Venus the earth might escape but it's only barely the sun to become a giant star. And you know it turned kind of cool off the surface turned kind of reddish and those are the ones you go out in the nighttime sky and front both star the Big Dipper Arcturus fronts all star the Little Dipper all kind of reddish hues and all of these stars are these giants that are in the process of dying and the sun to lose all its outer layers eventually and turn into what's called a white dwarf or just a little dim star about the size of the earth very compact metric ton per sugar cube very dense and will die that way. Hey well how do you know that when you look out you see the white doors you see these little critters you see the giant stars you see all of this stuff out there and application of in-principle relatively simple physical theory shows you that you should get them all in succession. And you explain everything you

see. So we figure we know what's going to happen to the sun. And I probably in ninety nine point nine percent certainty. And I'll say ours for sensor and all stars fall that same. The ones like the sun do. Depends a lot on their mass and then you get at these really rare ones the tiny fraction stars get up above about 10 times the mass of the sun and those are the ones you got to watch out for because they'll explode. Sun won't Little die as when these little little bird out little things but the big ones and there are several visible the naked eye will after it within the billion years or a hundred million years don't seem to have much choice other than to blow up. Fortunately they're very rare so you don't see it very often we haven't seen an exploder in our galaxy since 16 for Seoul and that's a good thing you do. There's a purported death zone around an exploding star of about 30 light years and your inside that is going to damage the earth even that far away. The violence of the explosion as it is is just mind blowing. And that's a

pretty good distance 30 light years. Yeah yeah I mean heavens in your stars four light years away and we can't get there and we aren't even close to getting to a star. Take thousands of years of the kind of propulsion systems we have even to get to the nearest one. And here you're talking 30 year talk and many times that distance near stars for four light years away. So as we're talking this morning which I'm killer he's a professor of astronomy at the U of I were talking about stars and if you have questions you can call us three three three. W y l l toll free 800 1:58 W while perhaps we should talk about fusion and how that ad differs from vision which is what you get in a nuclear reactor. YEAH OUR you just ordinary uranium the heavy stuff gets unstable you get the very heavy elements and they're unstable and they fall apart. Uranium decays to lead. Given enough time and. You can fission it if artificially if you want as well. Produce atomic bombs and reactors and things like this. The you

get energy out of fission and heavy atoms you get it you get energy out of fusing light atoms you can also get energy by fusing hydrogen into helium which is what a hydrogen bomb is all about. We haven't figured out how to actually create peaceful power yet of any sort actually fusing it. The sun does it very nicely it's a natural reactor because the great mass can drive the temperature up in the core to the point where the fusion just naturally occurs and that actually keeps the sun from shrinking down gravitational and stabilize its sun. There's enough in there to go on for 10 billion years. The there are other. You and a heavy star what you do is to fuse that hydrogen to helium and then the helium into carbon and so on up the chain and you fuse up the iron and that's sort of the bottom of it. You really can't get anything past an iron that way create energy and if you get an iron core and a heavy start core collapses the Star blows up. And that there is pretty well pretty well in hand actually a lot of details that aren't understood but the basic ideas

is very well in hand and in the explosion you create all the natural chemical elements and all the weave all the iron in the world has come from exploding stars in the past generations of. And it's not a speculation you can watch a star blow up we can see it happen in other galaxies and doggone it you do produce a huge amount of iron in the explosion all figure the number of exploders that we had in our galaxy over the last 10 billion years. Creates all and you need you know we have a caller when we talk with him. OK. Gibson setting the line number four. Hello. Oh hello Dr. Taylor like this is if you don't want to give City it we have talked a couple of times before. What I want to ask you is. I believe Venus will come to inferior conjunction at about March 15 or so and I'm wondering in the weeks between now and the time of unfair your contention will we get a pretty good view of Venus as a crescent. Oh yeah I don't know when I don't have that in front of me right now. It I think it's

an early late winter I think it'll be reach its brightest point and when it reaches that after passes elongation its greatest separation from the sun at that point it appears to be a half face in the sky. And then after that shortly before the conjunction it will appear as a really large Crescent. The you can actually see it in reasonably high powered binoculars. It doesn't take much optical power in arguments for years whether the naked human eye can actually see the crest of Venus when it's and its largest and generally people think no but there have been reports often on of little kids with really good eyesight saying get a look at little bitty Crescent or something like this so apparently it's just barely possible. But most of us would need power. I have a 7 by 50. Will I be able to pick up the crap. Mike I don't know I've got a left pair of 11 power binoculars and I can see it just barely with that I think it's 7 depends in your eyes if you hold very steadily you should be able to see it see that it's not round in any case and it kind of depends how good your eyes are.

I'll try it myself when I get some of the this this would be after it's reached its brightest and starting to approach the sun again and go through conjunction that's when it will be at its largest. Yes and it's a very attractive site this really skinny Crescent is very pretty and it's just leaving the smallest transparent but very skinny right. Yeah yeah yeah. OK thank you I'll keep a sharp eye out. OK. Between now and here. Yeah by all means everybody ought to be out there and they in the in the winter's cold looking up there in the southwest and whenever it's clear you know her so much. You're welcome. And catch Venus it is just so bright and beautiful. Right now it's getting brighter with time and Venus is over in the southwest and you look over nice new Jupiter not all that much fainter. The sky's really good evening skies really getting nicely filled with planets. After a very drab spring or autumn rather when we didn't have any to show our students the telescope observing says it's nice to have them back. Our guest again is Jim Keller He's professor of astronomy here. You have I have questions we've been talking a

lot about stars which is the subject of his recent book The Little Book of stars and his his special interest. But of course other questions walking two three three three. Wy a little toll free 800 to toot toot heavily while well brings back to Venus because you should admire it now because in around six or seven billion years you won't be there anymore because the sun will probably vaporize when it gets to be a giant star and expands to the orbit of Venus. So enjoy it now when you get a chance. Right well now let me ask you know there is another basic question here well let me ask you a few basic questions OK so fusion the the the reaction that powers the sun happens when we take the simplest atom hydrogen Yeah and we use that to make the next one up helium which is helium. Right right. OK so and that that reaction releases energy and that's what's makes the thing go. So how do we then get from I want to make sure that I understand this. How do we get then from helium to the other things that

well we have. You can if you have enough nuff energy available you can make all the chemical elements by simply ramming things together at very high speeds. That's what it comes down to. The that the sun will eventually begin to die when its hydrogen in the core not the surface in the cores all turn to helium and then gravity takes over and compresses it down heats it up and then all of a sudden the helium finds it confuse itself to carbon and then oxygen and that's what will happen to the sun it'll stop there because the sun doesn't have enough mass to make the engine run any farther than that. You know high mass star then the carbon and oxygen eventually when you have developed a core of carbon oxygen that'll squeak ready to squeeze that down and that'll fuse into a mixture of neon magnesium oxygen and other stuff and then you squeeze that down and that gives you a heavier elements and gradually you develop an iron core. But you can't fuse iron and get energy out of it. That's iron just refuses to do anything more efficient it won't

fuse under under pressure like that so it it once you get it. Gravity takes over again and since then it can't fuse and sort of stop the compression. The core collapses in less than a second. Bang. And you produce a violent explosion. The temperatures go up into the hundreds of billions of degrees and in the explosion. And as the rest of the star gets exploded away you've got yourself a fantastic nuclear furnace and in that explosion you create all have all the elements. There are other ways of doing it. And in even stars like the sun will produce nitrogen helium carbon stuff like that and to get a ject and back into space an explosion produces most of the really heavy stuff. And there are just thousands of nuclear reactions that produce literally everything that you would be difficult to write them all down some of which absorb energy some of which create energy. And you know we're sitting around the table I got a gold ring on a wedding ring that's made in you know

maybe a truckload of supernovae of it. It's about the only place you can get gold. All the uranium was made in in supernova explosions exploding stars in almost all the heavy stuff. It's actually everything just everything that is made there right and there are other sources stars like the sun will produce elements to in their nuclear furnaces and some of the the by products get lofted up to the surface the star going to jacked it back into space and with with the theory of this and if you produce sort of a theoretical model of a galaxy in a computer and you let all the stars run and explode and eject their gases and calculate what the chemical composition of the universe ought to be or the sun ought to be you you get the chemical composition of the sun it works. He works remarkably well. OK well let's talk with another person here there in Indiana on our line number four. Hello. Yes this is probably a tangential question but we're going

one find a name in the very true satellite of our planet. They're listed in a variety of books. The best one I know of off the top of my head is called the new solar system. And I've seen it in local bookstores. You can certainly order it. You may be able to find it in the library and I can't remember who the authors are I should but I can't remember but the title is the new solar system and that has a wonderful appendix in it that lists everything and you can get the names there and I think you know they're great. Sure. How does your book compare with Golding. Well this isn't meant for children. If that's what you're referring to this is an adult book and certainly high school students would have any trouble with it but it's meant I think I would say if I had to guess high school and up it's an introductory book for adults who are interested in the stellar science and stars of know what they are like what they do how we've used them over the years to navigate tell time a variety of things.

You know how we even told fortunes with them that you know the their application of human life in a lot of ways it tries to cover the basics of what they're all about and what they've meant to humanity. You're going to hear what you all think. John was here the other day. He was talking about how he was coming up to giving a final in his introductory class and he said he was convinced that some percentage of his students would come away thinking that they had taken a course in astrology. Yes yes yes that that does happen. I once had a I addressed it in class because there are a lot of people who believe in it and talk about its history and what it what it is sort of is it you know a system of fortune telling the like and how it doesn't really having to astronomy but most people really really think it does and he's got a long parallel history with astronomy and. I can be a little sarcastic bot of the times you claim it is. I had a very nasty note pinned to my door once after a class of someone who took real offense

because I did not say nice things about astrology. So they're viewed with great seriousness up there. We're a little bit past the boy here and your questions are welcome and are about astronomy with you of astronomer Jim Keeler in 3 3 3 9 4 5 5 toll free 800 to 2 2 9 4 5. We have someone next in Rantoul and this is line 1. Hello. Oh yes yes I had a question about what your feelings are regarding life on Mars. It doesn't look too likely. The there's been evidence for it off and on. And then the evidence seems to disappear and the only the thing that's close to viable evidence are these little micro or nano fossils that they have found in the Mars rock that they picked up out of Antarctica and that's been heavily challenged by the geologist saying you get the same structures through natural geological

processes. There's no compelling evidence at all that there's life there and it doesn't mean there isn't. It's just that there's no real evidence for it at this point that I think is anywhere close to convincing and I think the only way we're going to find out is to be able to go there with either with robotic craft or humans and take core samples really to sample the planet and bring it home not rely on an accidental rock that was exploded off Mars and it happened to hit the earth. And I don't think Elvis lives there that's been suggested often and it's. Are your feelings similar to Carl Sagan have. High probability you know fly somewhere in the queue a galaxy. Well again there's no compelling evidence for that becomes a philosophical question at this point my feeling is that yeah there is. I mean it's it's a philosophical point of view and I can't quite believe that this is all just for us. Maybe it is but I don't know that there is no evidence for at all other than right here on Earth. The ME CAN'T GO ON look or

shouldn't I think it's a wonderful thing to go out and look through the various safety programs and be a good idea. But again no evidence. OK thank you. Well thanks. Certainly there are scientists who suggest that conditions might be right and some of the satellites of other planets in our solar system has been suggested satellite of Jupiter because it apparently has a warm ocean beneath all that and an icy surface. And the planets are turning up. There are about 40 discovered planets out there not visibly seen but you can tell by the fact that they haven't the stars of the planets are there's no question about that and hardly any question about it anymore. They're not conducive to light their Jupiter like planets but where they exist well maybe planets like the earth exist too and you get enough of those maybe there's life elsewhere. It seems reasonable to suppose that but again there's no evidence for it. All right let's go next to the line number two someone here locally and champagne Urbana Hello. Well yes I was wondering if there's some place in the immediate vicinity that's good for stargazing it still misled police around I just wonder. Where people

go or is there you know there are various locations. If I want to get out I just hit a country road someplace where there isn't any traffic and stop the car get out. That may or may not be a good idea I don't know the champagne Urbana astronomy club has a as it's called it in the local You buy Stronach club to get have what's called a dark site down south of the airport. You can find out information on that by calling planetarium and or the Astronomy Club I think they'll give you information on that. Host open house is down there on a key on occasion but the state parks around here as well. The Cajun we have Star Parties The There's not too much its organizers say I just find myself a nice quiet dirt road someplace and the traffic is down the point with maybe 1 car an hour. That's fine.

OK thanks but appreciate your welcome thank you. And again locally here Line 3 0 0 0 and several years at the University of Illinois. I have heard much about the fundamental contribution that Professor even has made to the understanding of stars but I've never had it explained to me in terms. Someone in the humanities could understand. Could you explain in layman's terms what his research has contributed. Yeah sure I can because I work fairly closely with him over the years and a lot of Chapter 6 in this little book is is it describes a lot of the work he's done. He was been instrumental in developing theories of stellar structure and the theories of how stars evolve. I mean a lot of people have worked in this field over the years. And but but he's got a sterling record of it of theory in

how the process actually works and how stars. Live their lives as hydrogen fuser in terms of the real hard core theory the numbers and how they develop and how they evolve. And he among others have they have demonstrated exactly how the that the sun will turn into a giant star. How is a giant star it will begin to fuse helium in its core into carbon and how some of that carbon gets lofted up to the surface of the star and gets ejected from the star in a good fraction of the carbon including a good fraction of what you're made of has come from stars like the sun by processes that have been described by by eco even in his collaborators. He was also instrumental then in seeing what happens next which is the contraction of that carbon core which drives the star even even to greater size. As as as a red giant star and at that point the the the star will approach the orbit of the earth

and how the stars lose mass and how they turn into white dwarfs. The whole process has been. Pretty well elucidated bye bye bye ECO and his friends and collaborators they've just done a brilliant job of of connecting the various kinds of stars we see into a flow of theory. He's also done a great deal of work with doubling and that's something that's often ignored in in textbooks to school just text book descriptions of stellar evolution and stellar processes and stellar death you get two stars that are close together and they're evolving at different paces at different times they can do really weird things to each other. They'll throw matter back and forth one to the other we actually see that happen and Eco's worked pretty hard at it again among others but he has worked pretty hard at trying to figure out what happens if you get two stars that are really close together and how one affects the other's evolution and that has a powerful effect upon exploding stars has a powerful effect on evolution on the Galaxy. Does that help. Yes. Thank you very much.

You're welcome. All right thank you for the call again and we have a caller here locally in line one of their Nextel Oh good morning. I have a question I don't quite know how to phrase in the probably proper you know language but I just didn't like this repeated part going on earlier. The expansion of the universe keeps going between it's going to be expanding forever. Other people come up with something new. It's probably going to be closed down too. So what are the factors that go into debt. You know historically and Good one of the crew. Actors have to re-evaluate the experience through the contractions were we going to go. Well it's that it's funny you should bring it up by conversation with public conversations recently about about this work. I will give it away to all my future synonymy 100 students that usually the last question on my exam is what you know it is what is the nature of the universe you know is it close open going to contract going to expand forever going to accelerate and the question pretty much

stays the same but the answers have continued to change over. Lets Talk to your sister. Those seem to be the same two semesters in a row. The factors that go into it are really ability to observe and to observe accurately and the sizes the telescopes that you use the Hubble Space Telescope has probably been the biggest single factor in helping to elucidate how the universe our present view at least of what the universe is going to do that and our ability to sense the other wavelengths of the spectrum to be able to sense and record and measure the so-called cosmic background radiation which is the remnant radiation of the Big Bang cooled now at only three degrees above absolute zero. Pardon. One factor in determining whether it's going well. You can you can you can observe fluctuations in these fluctuations are sensitive to all the parameters of the universe it turns out if you get yourself a really good

theory cation who who can evaluate how the the expansion rate and so on can factor into this. Their launchings going to be launching several satellites to observe the background radiation and to observe it back observe its fluctuations that's really at the heart of it because that shows you what the universe was like in the very very early days not too terribly long after the Big Bang. The other is been our ability to measure distances over very large paths over very large distances. When I broke into this business you had trouble measuring distances any more than you know 20 30 light years away and you really had to just guess and guess and guess at some of the. The distances of galaxies and that's been improving dramatically. We can now resolve stars in other galaxies whose absolute brightness as we know that's been been one of the key projects of the Hubble Space Telescope allowing us to look out into the

tens of millions of years and now we're beginning to find other exploding stars that would allow us to get distances out to billions of light years away and that's really being been the biggest single key factor the given what we know about these distances implies that the universe is not only expanding it may actually be accelerating and there me is seems to be some mysterious source of energy is being pumped into it and nobody really understands very well it. More than anything any single thing. Yeah it's been the ability to get the Hubble Space Telescope above the earth's atmosphere where you can see to very very fine detail to very great distances in addition to building much larger instruments on the ground. I mean you know for years Palomar at five meters across range and now we've got two 10 meters atop Mona Kay in Hawaii several eight meter telescopes and there are plans for a 30 meter in California. The Scandinavians recently announced a suggestion that they're going to put the European community build a hundred meters so it's I don't know where the end of this is going to be.

I wouldn't wouldn't bet the farm that everybody has got it right at this point not given what I've seen there may well be I would be amazed if there weren't some surprises along the way. Thank you very much. You're welcome and thanks for the call. We have about 10 minutes left. Our guest is Jim Keller he's a professor of astronomy here at University of Illinois author of several books including The new one which is the little book of stars published by Copernicus. If you're interested in learning more about stars you can look for that and questions are welcome three three three w wild toll free 800 1:58 WLM. We had some questions the other day when John was here and I think someone actually called it off the air asking the same question there. They're interested in when the conditions might be right to see the space station. And apparently it's it's it's so bright that at certain times you can see it but the thing that's sort of the catch you can't see it all the time. It's only particular times that you can you know you can.

It can be predicted for any given location I think there are websites that will predict it. I don't know I don't know the answer and it's on the you have on your astronomy. Yeah I guess I don't even have a link to that. I suppose I ought to try to find out because I've had this question before. It's not really an astronomical thing it's just it's you know sort of a curiosity you know it's a curiosity and you can see satellites are not difficult to see. Almost any twilight and look up if you're patient you'll see a satellite look like a high flying airplane until it disappears into your shadow which goes away and doesn't a strobe lights on it. You can tell the difference that way which airplanes do. The space station was just a brighter version of that and I'm not sure it's the brightest one in back in 1965. 61 I think we launched the echo balloon which was a huge thing was supposed to reflect radio signals and it was a primitive attempt at transatlantic communication by bouncing the signals off thing but it was in near orbit and Man that thing was bright it was amazing. It was Bob's Brahms bright Venus. So there's nothing

unusual but bright. Bright satellites this satellite system the Motorola launched were if they caught glimpse of sunlight and they could be predicted as well just blossomed up brighter than Venus or I've had a number of calls on that what is that thing I saw you know you have as immediate knowledge is that in a radium flare and I I am a little bit concerned about this because the situation can probably only get worse and worse with these bright things that are orbiting the Earth and you know your structure is going to start being careful because one of these things passes across your field of view it's not going to your detectors any good and I think it's you know you're beginning to deal with some not just light pollution on the ground but light pollution in the sky and as pretty as the space station might be to see I'm not sure I'm a big fan of being able to see it you know OK we have some other calls here a couple minutes left. Let's talk with someone else locally on line 1. Hello good morning. Yes I just want to there's a great Web site if you want to. The

International Space Station I think actually they predict where you were or you haven't dash about Doc. Oh yeah someone called in the other day a different person will mention the same one and show you what you need you can go there and you put in your location and it tells you whether you've actually telling your band and they'll tell you the next time you'll be the space station your and your video player. That's how you were to look at the magnitude an exact time. Thank you what's the name of that again. Heavens dash dot com. OK thank you very much. You're on the street and we appreciate that that. I'm glad the caller mentioned it because indeed when John was on the other day somebody else called in and gave that site and I pulled it up on the laptop here and it looks like it should be pretty easy to use and they're not what you want you have the equations for the orbits are not not not hard to predict. OK so I just can't do it myself. W w w dot heavens dash above. Just like it sounds heavens dash above dot com and it'll not only will it point those things out but I think that it also will tell you other things like you know where where you see the

planets and maybe some basic stars and constellations and in things like that. OK very good thanks for that. To another caller here line too. Hello. Oh yeah. Could you recommend a reading. Layman's language. Oh there are not off the top of my head. If you call me at the office I can probably give you a couple there are three or four. There's an older one by Kaufman that was was pretty good and quite readable and there are two or three others that are pretty good and I'd have to dig them out of my library. But if you're number it's 2 1 7 3 3 3 9 3 8 2 0 it's robots. All right thank you. Anything really new when it comes to black holes. Well they're they're they're they're big and they're black in the hold. They Yeah I mean there's always something new coming along the discovery that within the last year one was apparently naked blackhole you detect them when they're

in orbit around more or less normal stars and through their action the star. It seems to be the only conclusion is that you got a black hole orbiting the star. The but there was one. There's a lot of programs over the last few years that involve what's called gravitational lensing if you get one star exactly in back of another the gravity of the star in front can lens the light from the star in back and make it kind of blossom make it blue make it look brighter. This is a byproduct of the Einstein's relativity in the bending of space time and the some astronomers observed one star just sort of blossom up and then fade back again and was added all the characteristics of a black hole passing in front of the star. And it may be the first actual discovery of a black of a free black hole in space without a companion and black holes. They they also are something that are produced by the stars as they go through there.

You can get into a lot arguments about that but the the the the wisdom at this point is that they are probably caused by the upper end of the high mass stars it's above 10 that you get the explosions and maybe above 30 40 solar masses. These are the things that produce black holes either by explosions or the age of the darn things just collapse into themselves and disappear. And there are all manner of theories for this and it's not understood is really not understood how you produce them. We have to sort of leave it at that. We're almost sure they're there and we're almost sure that the only way we can produce them is through the collapse of Hi Mr. Art but the process isn't understood. Let me go back to I'm still you know thinking about the the fusion in the life cycle of a star. We talk about the fact that the route what we do is we take hydrogen. We fuse it and we make helium and then when all the hydrogen the color of the star gets used up then the helium starts to the helium core will collapse and you could contract over a period

of millions of years under gravity. It just squeezes down and just like the mixture in a diesel engine as it squeezes down and heats up and it reaches a point of about 100 million degrees where the helium can then begin to fuse into carbon. It requires progressively higher and higher temperatures to get the engine to go to higher and higher mass atoms and requires higher temperatures yet to get the helium to fuse the rather the carbon diffuse into magnesium or something even heavier and that's not available in the sun. So the sun will stop as a ball of little ball of carbon and oxygen locked up forever as little bitty white world. So I guess one of the thing I was wondering about was when the when the core collapses then though the star gets bigger. Yeah that's it. Is stars behave. They do behave just the opposite of what you expect them to do they always seem to do this. It's the core of this contracting but that generates so much energy that you take the outer parts of the star and that temporarily blossoms outward and expands the sun will expand to beyond the orbit of Venus right now and it's you know it's it's the

sun is about 100 the size of the Earth's orbit give or take the radius of the earth's orbit and it'll it'll expand to actually probably pretty close to the size of the orbit of the earth in a few billion years and it will also begin to lose mass like crazy and it will lose that outer envelope will literally get lost and that reduces the gravitational interaction between the Earth and the sun and the earth will probably spiral away so we may save ourselves. That that's I guess the best we can do. So the temperature then the would be the fusion of the helium generates much higher temperatures in the fusion of the mill I think it's higher temperatures to generate the fusion of the helium works the other way around say gravity is the driving force here. If if there were any such thing as fusion the sun would be luminous for a while but keep shrinking right down to a point because gravity would be producing all of the energy simply by compression and making the sun hot enough to radiate. And that's the

fusion that stops the contraction that's why the sun so stable long as you got that fusion going on Gravity can't do anything. As soon as if it's like like two forces battling each other and eventually when the fusion runs out which runs effectively on what's called the strong force which is what binds atoms together. The granny takes over again and then gravity generates the energy of the star and then the helium fusion picks up and then helium fusion for then its gravity wins and then gravity eventually pretty much wins the battle to get down to the white door proportions and all kinds of other forces sort of keep keep the thing stable which are explained in the book in the high mass stars Gravity wins really high massive when you produce the black hole Gravity wins forever. It's an immensely powerful driver of the stars right. That's what we come away with from the program today. Gravity wins gravity With All right thanks to you or to Jim Keller professor of astronomy at University of Illinois here in Abana champagne your interest in learning basic stuff about stars. Look for his book The Little Book of stars it's published by

Copernicus Copernicus books.