Eclipses, Cosmic Cataclysms, and More with Janna Levin

What can we learn from eclipses? Janna Levin joined by comedian Matt Kirshen and professor of astronomy and astrophysics at Columbia University, Joe Patterson, discuss the 2017 eclipse, binary star systems, supernovae and more. What is an eclipse on Jupiter like?

Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.

• 0:00Neil deGrasse Tyson?

  Coming up is a show recorded on the day of the last total solar eclipse to cross the United States back in 2017. It's got my friend and colleague, Janna Levin, who will carry you through what to look for, what to expect, and give you little tidbits about the sun as well. Coming up.

• 0:20Neil deGrasse Tyson?

  Welcome to StarTalk, your place in the universe where science and pop culture collide. StarTalk begins right now.

• 0:33Janna Levin?

  Welcome to StarTalk All-Stars. I'm your All-Stars host, Janna Levin. I'm also professor of physics and astronomy at Barnard College of Columbia University and director of sciences here at Pioneer Works, where we're hosting this show. Very excited to be here. We've never done a show from here before, so this is awesome. I want to introduce my guest, co-host, Matt Kirshen, comedian and host of Probably Science Podcast. Hi, Matt.

• 1:00Matt Kirshen?

  Hey, Jana.

• 1:01Janna Levin?

  Welcome. How was your nap?

• 1:03Matt Kirshen?

  It's been good. I came in on the red eye just in...

• 1:06Janna Levin?

  Yeah, you had a little nap.

• 1:07Matt Kirshen?

  Had a little sleep on. You've got some very good couches here at Pioneer Works. I'm feeling great.

• 1:11Janna Levin?

  Okay, excellent. And I'm very excited to welcome for the first time on the show our expert scientist, Professor Joe Patterson. And I have to say about Joe, he is many things. He's a professor of astronomy at Columbia University. He is also, I think you said, director of the Center for Backyard Astrophysics. Super cool citizen science, well before its time, well before citizen science was even a phrase, right? Cool. And also, my first astronomy professor. I remember very fondly.

• 1:43Speaker 03

  And she got pretty good grades.

• 1:47Janna Levin?

  I got me. I would climb into the back of the classroom in Puvin at Columbia with those stacked levels, you know? They're so steep with like my big cup of coffee. And I'd be like... But you were such an amazing professor, Joe. Really, just the greatest. So, thank you for that. A little small applause for Joe. Welcome to our show. I'm also wearing my eclipse glasses because this is the day of the August 21st, 2017 eclipse. You know what I loved in the 1918 newspapers when they talked about the eclipse that ran from the Pacific to the Atlantic? They said forecasted the next eclipse of its kind in 2017. Isn't that kind of crazy?

• 2:29Janna Levin?

  That the people at the time would have been reading those papers?

• 2:33Speaker 03

  Yeah, well, I think eclipses were probably very, very exciting then. Actually, the next year, there was an eclipse in the Indian Ocean, which is one I know that you know quite a bit about because it's the one that verified Einstein's.

• 2:45Janna Levin?

  1919.

• 2:46Speaker 03

  1919.

• 2:47Janna Levin?

  Yeah, when Eddington went off the coast of Africa.

• 2:50Speaker 03

  That's right, and, and it was also the significance of 1919 was magnified because, of course, the armistice had just been signed. And it was a British team verifying a theory by a German scientist which overthrew, overthrew Newton's theory of gravity.

• 3:10Janna Levin?

  And this is six months after World War I. When the countries were killing each other. And they're like, it's like out of the shadow of the war into the shadow of the moon.

• 3:19Matt Kirshen?

  Science wins. Can you tell, can you tell me what, what it was that they verified? This is, this is something that Einstein made a prediction, general relativity, and then the, something happened during the eclipse that they could use to test one of these predictions? What was it?

• 3:33Janna Levin?

  Yeah, Joe, Joe can tell the story.

• 3:35Speaker 03

  Okay, yeah, one of the predictions, light, light of course carries energy. And Einstein said that energy and mass are equivalent. His famous equation, E equals mc squared. So if it carries energy, it carries mass. If it has mass, then it means gravity must affect it, must affect light. Never really been thought about before. But in Einstein's theory, a, a strong source of gravity should bend light. And so, but there were no sort of strong sources of gravity around at the time, except that people thought, well, during this, during a solar eclipse, if you look at the position of a star, take a photograph of the sun in solar eclipse,

• 4:19Speaker 03

  you can see some stars around the edges because it's so dark out. And look at the positions of those stars. And if the light has been bent, those positions will have shifted from their normal positions.

• 4:33Matt Kirshen?

  So you, you'd know where the star should be just because of where it has been in its trajectory in space?

• 4:37Janna Levin?

  Right, because of astronomy.

• 4:38Matt Kirshen?

  And then, and then the sun is suddenly in the way, and that light from the star would have slightly curved around it.

• 4:44Janna Levin?

  Right, so if there hadn't have been an eclipse, you'd be blinded by the light of the sun. So like, in this case, I think they looked at the Hades cluster. And so it was directly behind the sun and usually you'd be completely blinded by the light of the sun and what would you know, right? But with the total eclipse, the sun goes dark and you have this opportunity to see this thin vapor of light, right? Just come around the bend when you know it's behind the sun.

• 5:07Matt Kirshen?

  Right. So you're just able to see a tiny bit of this star that you should never be able to see because there should be an entire star between them.

• 5:13Speaker 03

  Yeah.

• 5:13Janna Levin?

  Yeah, but I love what you were saying in the, you know, opening, which is that this was really a tremendous moment for people to crawl out of this hideous patriotism, right? Nationalism. And, um, and instead to feel like citizens of one place, you know, one planet.

• 5:32Matt Kirshen?

  I mean, to be fair, Einstein later left Germany and went to America and then that was part of the ally team. So we got him back. So I'm still, I'm still claiming Einstein as part of Team Allies.

• 5:42Janna Levin?

  Well, you know, amazingly, Eddington is really the one who catapulted Einstein's fame in the English-speaking world. I mean, that was really the event, right? And, and then Einstein becomes incredibly famous. It's on the covers of all the newspapers. And that's the cleverest experiment I can think of from an eclipse. But there are some really amazing experiments now, which are probably deeply clever, but just somehow don't have the singular historic placement, you know? So what do people do now to scientifically, to, from an eclipse? Like, what is scientifically valuable? I mean, we had this eclipse today. It was incredible. You had 4,000 people out of Columbia. It was amazing. How was your view, by the way? Did you get clouds?

• 6:24Speaker 03

  You know, uh, it was sort of, it was sort of partly cloudy.

• 6:27Janna Levin?

  Yeah.

• 6:27Speaker 03

  Uh, but, um, gosh, you know, there was just very little, everyone was very elated at this event.

• 6:32Janna Levin?

  I know.

• 6:33Speaker 03

  It, it hadn't happened in such a long time. Um, and people for, for reasons that, you know, amaze me and delight me, uh, people. Are, um, people react with enormous glee.

• 6:48Janna Levin?

  Yeah.

• 6:48Speaker 03

  At this sort of scientific spectacle in the sky.

• 6:51Janna Levin?

  Yeah. Um. So you didn't expect 4,000 people?

• 6:54Speaker 03

  Uh, yeah.

• 6:55Janna Levin?

  What did you expect?

• 6:56Speaker 03

  I, I expected maybe about 250 people.

• 6:59Janna Levin?

  Okay. I started to worry about like 700 people coming or something like that. But I did not expect thousands. That was really fantastic. And it was exciting, right? Did people, they got into it, even when the clouds were there and then it would come back?

• 7:12Speaker 03

  Yeah, there were, well, people, they'd come with their friends and they'd look for gla- we, we brought 500 glasses.

• 7:18Janna Levin?

  Yeah, I stole some of your glasses. You had 500 minus about 70.

• 7:21Speaker 03

  Okay, well, there you go.

• 7:23Janna Levin?

  You gave them to me personally.

• 7:25Speaker 03

  That's true, yeah, I remember it now. A lot has happened since yesterday. But, um, yeah, so they disappeared pretty fast, but people, uh, shared them around.

• 7:33Janna Levin?

  Yeah.

• 7:33Speaker 03

  And, uh.

• 7:34Janna Levin?

  I mean, you don't sit there looking at it for four hours.

• 7:36Speaker 03

  No, absolutely not. Yeah, the only one who did was me.

• 7:38Janna Levin?

  It's good to share them.

• 7:39Speaker 03

  It was me, cause I kept, people kept needing help with the telescope and.

• 7:42Janna Levin?

  Yeah.

• 7:43Speaker 03

  Frankly, I'm still getting some afterimages in my eyes.

• 7:45Janna Levin?

  Oh, no.

• 7:46Speaker 03

  But, I think I'll be okay. I think I'll be okay in a few hours. But, uh, uh, yeah, and, uh, yeah.

• 7:54Janna Levin?

  You were using like the finder of the telescope without a filter?

• 7:57Speaker 03

  No, the technique is we would just, uh, use your hand in the finder there and find it and then.

• 8:01Janna Levin?

  Right, so the, so, so the finder casts an image of the sun on your hand?

• 8:04Speaker 03

  Yeah.

• 8:05Janna Levin?

  And that's how you know you're pointing in the right direction?

• 8:07Speaker 03

  That's how you know you're pointing in the right direction. And of course, when the kids come up, some of the, the, the littlest of children are the most violent treaters of telescopes. Some kind of mathematical law there. And so they would sort of bash the telescope and you'd have to re-.

• 8:22Janna Levin?

  Yeah.

• 8:22Speaker 03

  Orient it there.

• 8:23Janna Levin?

  Yeah.

• 8:24Speaker 03

  But it was, uh.

• 8:25Matt Kirshen?

  But that's great to have that many people getting excited at a young age and.

• 8:28Speaker 03

  No, absolutely. Absolutely, yeah.

• 8:31Janna Levin?

  So I asked, oh, sorry, Matt, please.

• 8:33Matt Kirshen?

  No, go for it.

• 8:33Janna Levin?

  No, I was just gonna say, I asked you originally, what are the scientific experiments that people do now from an eclipse? So we did it for fun annihilation and excitement.

• 8:41Matt Kirshen?

  Yeah, everyone was happy. It was my first time seeing an eclipse in America as well, which is cool. Like normally, as you know, I'm normally like in a jungle somewhere, tricking people into making them my god. Uh, or me their god rather. And that's the best use of any eclipse scientifically, to trick.

• 8:56Janna Levin?

  Mm-hmm. Yeah, and, and has it worked in the past?

• 8:59Matt Kirshen?

  Yeah, I, I'm now the god of quite a few different cultures and it, also, little tip, you don't have to wait for a solar eclipse. Lunar eclipse work perfectly well.

• 9:08Janna Levin?

  In terms of intimidating.

• 9:10Matt Kirshen?

  Yeah.

• 9:11Speaker 03

  Columbus, Columbus found that out in fifteen twenty-three.

• 9:14Matt Kirshen?

  And one of the many good things he did.

• 9:16Janna Levin?

  So wait, what was fifteen twenty-three?

• 9:18Speaker 03

  Well, he, uh, no, it was, it was an earlier one. It was fifteen oh four. It's fifteen oh four. He knew there was gonna be a lunar eclipse on a particular night. And, you know, he was, uh, you know, set up an assembly line, uh, tell the local people to supply him with a certain amount of sugar and gold and, uh, whatnot.

• 9:36Janna Levin?

  And then they would get those cardboard glasses?

• 9:38Speaker 03

  No, no, no, no. They, he, uh, he would have loved to have them, but, but, you know, he basically said, look, you know, your, your shipments have been a little sparse lately. If you don't, uh, pick up the pace, uh, I'm gonna basically blot out the moon tomorrow night.

• 9:53Janna Levin?

  My God.

• 9:54Speaker 03

  I don't think so, buddy. I don't think. And, and, uh, and then he did.

• 9:59Janna Levin?

  Oh, my God. That's, that's a good trick.

• 10:02Speaker 03

  He got a lot of cooperation after that.

• 10:04Janna Levin?

  Wow.

• 10:05Matt Kirshen?

  What most people don't know is there wasn't actually an eclipse planned. He really did have that power. So.

• 10:11Janna Levin?

  And you've learned to harness it. Okay, I'm gonna ask Joe for the third time. The third time, I'm gonna get Joe to answer this question.

• 10:18Matt Kirshen?

  Fun and games aside, what is the real science that real scientists are doing?

• 10:22Speaker 03

  Okay. There's not, you know, right now, the solar eclipse is primarily a place where people go crazy. Lives are changed. My life was changed with my first, first eclipse. But scientific experiments are being done primarily to study the corona. Um, the corona is never studied as sensitively as when the sun is bl- when the photosphere of the sun is blotted out. Um, and while you can do it a little bit from the tops of mountains, where you get above the dust layer, and then you could kind of study the outer layer of the corona 'cause some of the bright blue sky is muted, uh, up there. Uh, the lower corona, you can never see. But during an eclipse, you can, because when the moon fits over the sun like a glove

• 11:04Speaker 03

  and you get the entire photosphere blocked from the, then you can look at the lower corona and you can see, well, the structure in the lower corona. And one of the things that we'd like to know, for example, is, um, uh, what supports the corona? Um, most people have seen pictures of the corona. Most of them are actually taken during eclipses, as a matter of fact. And, um, uh, so you have this big. Thing in the sky, big luminous thing in the sky, you'd think that it ought to collapse down on the sun.

• 11:35Janna Levin?

  Mm-hmm.

• 11:36Speaker 03

  You know, gravity, the sun's pretty intense, so why doesn't that gas, you know, collapse back?

• 11:41Janna Levin?

  Yeah, so it's like some kind of plasma, magnetic plasma, magnetized plasma.

• 11:43Speaker 03

  Yeah, it's very hot gas.

• 11:44Janna Levin?

  And it's like frothing, it's always like churning and frothing.

• 11:48Matt Kirshen?

  That's something I heard just last week because of all the articles about the eclipse. I didn't realize that the corona is hotter than the surface of the sun.

• 11:54Janna Levin?

  By a lot.

• 11:55Speaker 03

  The hottest parts are 100 million K.

• 11:59Janna Levin?

  Kelvin.

• 12:00Speaker 03

  Kelvin.

• 12:01Janna Levin?

  People speak only Fahrenheit in our audience, so I'm not going to attest that nobody speaks Celsius or Kelvin, but I'm going to say it's like tens of millions of Fahrenheit, is that about right?

• 12:13Speaker 03

  Okay, well, double it approximately. I don't know. Anyway, about 10 million Kelvin for the center of the sun, but about 100 million for the outside. So it is, it's hotter, parts of it are hotter.

• 12:25Janna Levin?

  Which is crazy because the center of the sun is where all the nuclear reactions happen. So like, it's hot enough in the center of the sun to have a nuclear bomb, right?

• 12:32Matt Kirshen?

  Yeah, nuclear fusion.

• 12:33Janna Levin?

  And then like the atmosphere gets down to like 10,000 Fahrenheit or something like that.

• 12:38Speaker 03

  Atmosphere is about 10,000 Fahrenheit.

• 12:39Janna Levin?

  Yeah, and then it goes way up at the corona.

• 12:41Speaker 03

  Yeah.

• 12:42Janna Levin?

  So, nobody knows why.

• 12:43Speaker 03

  Nobody really knows.

• 12:44Janna Levin?

  Maybe they will after this eclipse.

• 12:46Speaker 03

  That's a possibility. I mean, there's some kind of way to generate energy into the atmosphere, and we have, of course, we have an atmosphere which also rises in temperature slightly when you go farther up.

• 13:00Matt Kirshen?

  I did not know that.

• 13:01Speaker 03

  Yeah, when you go up to about 100,000 feet, it's dropping, dropping, dropping, dropping. Then above 100,000 feet, it starts to climb a little bit.

• 13:08Matt Kirshen?

  Interesting.

• 13:09Speaker 03

  Yeah, so.

• 13:10Janna Levin?

  Is that because of like sunlight hitting?

• 13:12Speaker 03

  Well, yeah, it's because some of the sunlight, some of the sunlight actually gets absorbed up there.

• 13:17Matt Kirshen?

  Right.

• 13:18Speaker 03

  And it gets absorbed directly, and there's not much matter up there, so you absorb the sunlight, there's not much matter, and so it's fairly, fairly hot. Now, even though it's hot, if you went there, and it went outside, you'd die immediately, but, you know, I don't know how you would die exactly, but, but.

• 13:34Matt Kirshen?

  So you had some kind of support system.

• 13:36Janna Levin?

  But if you didn't die that way, there'd be an alternative.

• 13:38Speaker 03

  Yeah, you'd find it cold because, of course, the density is so low.

• 13:41Matt Kirshen?

  Right.

• 13:42Speaker 03

  That the amount of, you know, collisions on your body.

• 13:44Matt Kirshen?

  So these particles have more energy than they would do a little bit lower down, but they're hitting you less frequently.

• 13:48Janna Levin?

  Right, exactly, rarely. So, is the corona responsible for the solar winds?

• 13:55Speaker 03

  Uh, the corona itself, we don't know the answer to that.

• 13:58Janna Levin?

  Okay, so like Aurora Borealis and the northern lights are coming from solar winds striking our own magnetic field, and so it's unknown if that originates from the corona.

• 14:07Speaker 03

  Uh, well, it originates in the same place that the corona originates, but the present, I think, uh, most common theory is that they come out of holes in the corona. Corona has holes in it.

• 14:20Janna Levin?

  Huh.

• 14:21Speaker 03

  And so basically because some time lapse movies have been taken of basically streams of material coming out in through these holes in the corona, and they go out to, well, they go out to, they go out to the whole solar system.

• 14:34Janna Levin?

  Amazing.

• 14:35Speaker 03

  And they eventually cause the northern lights and the southern lights, and they get to Jupiter, and eventually they leave the solar system.

• 14:42Janna Levin?

  So you were mentioning your first solar eclipse changed your life.

• 14:45Speaker 03

  Yeah.

• 14:46Janna Levin?

  What year was that?

• 14:47Speaker 03

  Uh, it was, uh, nineteen seventy.

• 14:49Janna Levin?

  But you had seen an eclipse before, just not a total. Is that right?

• 14:53Speaker 03

  Well, that's right. As a child growing up in Japan, I had seen a, about ninety percent eclipse, and, um, so...

• 15:02Janna Levin?

  You didn't stare at it, did you?

• 15:03Speaker 03

  I don't know what I did. Somebody gave me a piece of glass or something, and I can't remember anything about it. I just do remember when nineteen seventy rolled around, I thought, well, you know, I see a ninety percent, you know, should I go down to Virginia to see a, a total, see a hundred percent? What could the ten percent be? And, uh, I just, I was just graduated from college, and my, uh, one of the math teachers there said, "It doesn't work that way." He was a math teacher. Had to, had to accept it.

• 15:36Janna Levin?

  Had to work that way, right?

• 15:37Speaker 03

  So we go down there, and, uh, so on March the seventh, nineteen seventy, it was totally clear, uh, it was an experience that changed my life. It was, I think for many people who see a total eclipse, it's sort of a marker in their life, you know, like, you know, your birth, your death.

• 15:56Speaker 03

  Your marriage, perhaps.

• 15:57Janna Levin?

  The solar eclipse comes after death?

• 16:01Janna Levin?

  Are you doing this chronologically, Joe? I'm very confused.

• 16:03Speaker 03

  Well, this is science. We don't know everything.

• 16:05Janna Levin?

  Wait, wait, wait. Birth, death, then marriage?

• 16:09Speaker 03

  Well, okay. These things can be rearranged in various orders depending on your metaphysics or your lifestyle. But the, uh, anyway, so, you know, I became an eclipse junkie then. I saw the next eclipse.

• 16:22Janna Levin?

  Have you chased many?

• 16:23Speaker 03

  Uh, I've only chased, uh, four. I don't guess I, I guess I count this one because I live in New York City.

• 16:29Janna Levin?

  Yeah.

• 16:30Speaker 03

  I'm.

• 16:31Janna Levin?

  Yeah. You opted not to go?

• 16:33Speaker 03

  I opted not to go. Um, it, you know, it, it is a kind of, there are certain things you only need to do once, actually. Uh, and I.

• 16:41Janna Levin?

  Is death one of them?

• 16:42Speaker 03

  I would be a little afraid. I would be a little afraid that if I, if I went to another total eclipse.

• 16:48Janna Levin?

  It would alter you?

• 16:49Speaker 03

  It would, no, no, no. It would just be, it'd just be some kind of letdown. It would just be, I did it before. It's the same. You know, I can't, it's not, I don't know.

• 17:01Janna Levin?

  Yeah.

• 17:02Speaker 03

  Because I never saw, the, the second one I saw was very spoiled by clouds.

• 17:05Janna Levin?

  Right.

• 17:05Speaker 03

  The third one, the same.

• 17:06Janna Levin?

  Right.

• 17:07Speaker 03

  So.

• 17:07Matt Kirshen?

  But what happened, if you do have one that's even better than the first one, then you end up, then you're stuck, then you have to spend your entire life saving up to the next eclipse and.

• 17:15Speaker 03

  Oh, yeah, it's even worse. It's true.

• 17:17Matt Kirshen?

  And you're like, all right.

• 17:18Speaker 03

  You should find that out.

• 17:19Matt Kirshen?

  It turns out to be better than the first one. And you're like, okay, I guess it just gets better every time. Now I have to, that's my life now. I have to put teaching on and research on hold.

• 17:27Janna Levin?

  Technical addiction. That's the technical definition of addiction.

• 17:29Matt Kirshen?

  Yeah.

• 17:30Janna Levin?

  But there are people who chase eclipses all the time.

• 17:33Speaker 03

  Some people have seen 50.

• 17:34Janna Levin?

  That's insane.

• 17:36Speaker 03

  There's about one a year somewhere on the Earth's surface.

• 17:40Matt Kirshen?

  One, one partial or one total?

• 17:41Speaker 03

  No, there's about one total eclipse a year somewhere on the Earth's surface. Yeah. About one, somewhere.

• 17:48Janna Levin?

  So, do you want to tell us why it's so rare? Why, why don't we have it monthly?

• 17:52Speaker 03

  Yeah.

• 17:53Janna Levin?

  Why isn't that every time there's a new moon, when the sun is basically behind the moon, in, to some extent, right? Um, so it goes dark. Why don't we have a, a total eclipse every month?

• 18:06Speaker 03

  Yeah. So, uh, if the moon orbited in exactly the same plane as the sun, uh, then indeed, every time there was a new moon, it would just fit right over the sun like a glove, have an eclipse. You have to turn the lights on if you're driving.

• 18:22Janna Levin?

  Yep.

• 18:23Speaker 03

  You know, and then after a while, people would think of it as, I don't know, a nuisance.

• 18:28Janna Levin?

  Right, they'd be like, oh, this again.

• 18:30Matt Kirshen?

  It'd be something they just list next to the weather.

• 18:33Janna Levin?

  Right.

• 18:33Speaker 03

  Something like that.

• 18:34Janna Levin?

  Like, imagine if there was only a full moon once every hundred years. We'd be like, there'd be parties to go see the full moon. We'd be like howling at the moon.

• 18:42Matt Kirshen?

  But it would. It would just, it would just list it in the paper, just like sunrise, sunset, eclipse.

• 18:46Janna Levin?

  Hasn't been a full moon since 1918.

• 18:48Matt Kirshen?

  Yep.

• 18:49Speaker 03

  Yeah, so the rare, so that's what it would be if it were in the same plane.

• 18:54Janna Levin?

  Right.

• 18:54Speaker 03

  But the moon's orbit is tilted by five degrees.

• 18:57Janna Levin?

  Mm-hmm.

• 18:58Speaker 03

  It's five degrees, okay? So the moon is half a degree in diameter.

• 19:02Janna Levin?

  So it misses.

• 19:03Speaker 03

  Yeah, so it misses like nine tenths of the time. And so...

• 19:07Janna Levin?

  So each time it goes around and crosses the orbit of the Earth, it's, it's not necessarily new moon.

• 19:15Speaker 03

  Yeah, well, there's a technical definition of new moon when it's sort of exactly, you know, above or below the sun or at the sun.

• 19:24Janna Levin?

  Okay.

• 19:24Speaker 03

  So that's the technical definition of new moon. And we, so we do say there is a new moon. But, but it's not exactly

• 19:30Janna Levin?

  Right.

• 19:30Speaker 03

  the newest of all new moons.

• 19:41Speaker 04

  I'm Jasmine Wilson, and I support StarTalk on Patreon. This is StarTalk with Neil deGrasse Tyson.

• 19:54Matt Kirshen?

  Am I right in thinking it's just coincidence that the moon fits exactly over the sun? Or is there any greater reason why, why it's exactly the right size for an eclipse?

• 20:07Speaker 03

  I, I guess, I guess it can only be coincidence, yeah. I can't think of any reason that, that, you know, one half a degree, which is the angle that the, both the sun and the moon have. Uh, you know, I, I guess the only thing I'd think of is if it were something smaller. If the moon were smaller than it is, or bigger than it is, it may not have been, the orbit might not have been stable. Right. Every orbit has to hang around for four and a half billion years because we're now talking, we're having this conversation, four and a half billion years after all these events took place that arranged the solar system. Right. So, everything that you arranged has to be stable.

• 20:49Speaker 03

  And there are certain things that are not very stable, like if the moon is farther away, a lot farther away than its present distance, then, basically Jupiter, Saturn could, you know, occasionally sort of tug it out and we might lose our moon. Oh, right. Yeah.

• 21:07Janna Levin?

  So, the moon is 400 times smaller than the sun, is that right?

• 21:10Speaker 03

  400, yeah.

• 21:11Janna Levin?

  So, it also, 400, so it also happens to be 400 times closer.

• 21:15Speaker 03

  Yeah.

• 21:16Janna Levin?

  And that, like, my thumb is a lot smaller than the moon, but I can keep it really close to my eye and I can cause a total eclipse of the sun this way, right?

• 21:23Speaker 03

  You absolutely can. It's very instructive to do it, too, actually. You, you got a feeling, on a clear day, on a cloudy day, it's not interesting at all. But on a clear day, you can just do that and it's a measure of exactly how clear the day is.

• 21:37Janna Levin?

  Oh, interesting.

• 21:38Speaker 03

  Because sometime, sometimes you can see the blue going all the way to the edge of your thumb. That's a really, really clear day. And that's how solar astronomers, when they pick their observatory, that's how they, you know, they're going, they're all on mountain tops.

• 21:52Janna Levin?

  Yeah.

• 21:53Speaker 03

  And, you know, there's a lot of people that stick their thumbs in the air.

• 21:56Janna Levin?

  So, the big difference with the, with the lunar, with the moon eclipsing the sun and a solar eclipse in my thumb is that I cast a much tinier shadow and the entire US is not excited about the shadow cast by my thumb. Is that fair to say? So, the moon casts a 70-mile-wide shadow that we can all share.

• 22:15Speaker 03

  Yeah.

• 22:16Janna Levin?

  But in principle, I could do this every day and be like, woo, it's an eclipse of the sun.

• 22:19Speaker 03

  Well, but this is an interesting thing because what it also means is that the angular size, you know, it just so happens that humans have an arm, this is, and a thumb, an arm that is long enough and a thumb that is wide enough to replicate that particular half-a-degree number.

• 22:38Janna Levin?

  I certainly do.

• 22:39Speaker 03

  She does. Sure, her proportions are mo- fairly normal.

• 22:44Janna Levin?

  Skip the fairly, brother. Let's not get into this in a podcast.

• 22:48Matt Kirshen?

  So would it be possible, if like, if you wanted to do some of the experiments that you normally only have to wait till on the clips to do, to send up into space a telescope and a blocker?

• 23:01Janna Levin?

  There is one.

• 23:02Matt Kirshen?

  Okay.

• 23:02Janna Levin?

  Yeah. There is an experiment where they fake an eclipse all the time.

• 23:06Matt Kirshen?

  So they have one, one telescope in space pointing at the sun?

• 23:10Janna Levin?

  And it has a, do you remember what it's called? I can't remember what it's called. Sorry, apologies to the P I on that particular experiment. But I mean, there's something that is supposed to be spectacular about the moon doing it. And I'm not sure exactly what it is, but in terms of coronal physics and studying it. But I have another question about coincidences. So I've heard a theory, and I know it's just a theory, that it's not that well substantiated, that early in the Earth's formation, an asteroid slammed into the planet, a big one, and sloughed off the moon, basically, out of Earth's stuff. And created the moon, the moon settled into a spherical shape, the Earth settles into a spherical shape, and it also tilts the Earth.

• 23:52Janna Levin?

  So it creates not only our lunar system, but the seasons. Have you heard this theory?

• 23:57Speaker 03

  Um, yes.

• 23:59Janna Levin?

  What's your, what's your feeling on it?

• 24:00Speaker 03

  Well, you know, I haven't read the papers on it. I know when I first heard about it, I, I thought it was a stretch, to say the least. I didn't really know why you need to have a special mechanism to make the moon.

• 24:16Janna Levin?

  Cause there are moons all over the place.

• 24:17Speaker 03

  There are moons all over the solar system.

• 24:18Janna Levin?

  Yeah.

• 24:20Speaker 03

  Are there going to be special mechanisms or all those other things? On the other hand, the moons, our moons are a little different because the Earth-moon system is a kind of sister-brother relationship.

• 24:30Janna Levin?

  They're almost two planets.

• 24:31Speaker 03

  They're almost the same compared to the ratio with Jupiter has just a bunch of tiny things going around.

• 24:36Janna Levin?

  Yeah, so Jupiter has what, dozens of moons?

• 24:38Speaker 03

  Yeah, it has, I think, at least 28 named moons, actually.

• 24:42Janna Levin?

  Yeah, and they're much, much, much smaller than Jupiter, because Jupiter is like huge. But the moon's what, a quarter the size of the Earth? That's not that much smaller. That's like in the zone. Like, I'm a quarter your size.

• 24:54Speaker 03

  Yeah, and in fact, you know, interstellar travelers, if they're zooming in on the solar system, uh, they would be, their eye would be caught by the Earth-moon system.

• 25:02Janna Levin?

  Mm-hmm.

• 25:03Speaker 03

  And I, you know, none of us knows exactly what caused life on Earth.

• 25:08Janna Levin?

  Right.

• 25:09Speaker 03

  Uh, but, um, anyway, they, I think they, they could actually consider it a good habitat for life, actually, because of the moon.

• 25:16Janna Levin?

  So this tilt that the Earth has is also part of the way the eclipses work, and the complexity of it, and where they land on the Earth. Um, and this tilt is also really important for the seasons. Do you think the tilt of the Earth is important for emergence of life on the Earth? I mean, could it be, so, so, so instead of the Earth facing straight up when it orbits the Sun, it actually points towards the Sun?

• 25:39Speaker 03

  Yeah.

• 25:40Janna Levin?

  And, and, and it's the reason why it's summer in the northern hemisphere and winter in Australia and vice versa at the same time?

• 25:48Speaker 03

  Yeah, well, if you had a tilt, if you had no tilt, or if you had like a ninety-degree tilt.

• 25:52Janna Levin?

  Yeah.

• 25:53Speaker 03

  Like Uranus has a ninety-degree tilt.

• 25:54Janna Levin?

  Is it, is it straight up and down?

• 25:55Speaker 03

  Eighty-eight and a half degree or something like that.

• 25:57Janna Levin?

  Is it like the only one of the planets?

• 25:59Speaker 03

  It's the only one that's really close to ninety. So if it was ninety, then what would happen is the equatorial regions.

• 26:05Janna Levin?

  Yeah.

• 26:06Speaker 03

  Would be hot all the time.

• 26:07Janna Levin?

  Right.

• 26:08Speaker 03

  And the polar regions would be.

• 26:09Janna Levin?

  Cold all the time.

• 26:10Speaker 03

  Extremely cold all the time, although the Sun would always be on.

• 26:12Janna Levin?

  So no seasons?

• 26:13Speaker 03

  There'd be no seasons, or, or, and they might call them seasons, but you'd have to travel to get to the, you know.

• 26:18Janna Levin?

  Right.

• 26:19Speaker 03

  And, um, so that can't be good for life, all, because life generally, I don't know if life needs changes, it needs really seasons. But it does sort of need, the hottest of temperatures on Earth, and the coldest of temperatures on Earth don't seem to be very favorable.

• 26:34Janna Levin?

  Hmm.

• 26:35Speaker 03

  For life. But not necessarily primitive life. Primitive life might, uh, might like heat more.

• 26:39Janna Levin?

  Do you think that we're gonna discover other primitive life in the solar system?

• 26:43Speaker 03

  Well, I doubt it. Uh, I can't think of where it would be exactly.

• 26:48Janna Levin?

  You doubt it not on the moons? Other moons? Like you were saying of Saturn?

• 26:52Speaker 03

  Uh, well, uh.

• 26:53Janna Levin?

  Jupiter. It's a lot of moons, and they're Earth-sized, some of them.

• 26:57Speaker 03

  Yeah, no, I don't, I'm, I'm not suggesting that they should all, uh, be, uh.

• 27:02Janna Levin?

  Habitable?

• 27:03Speaker 03

  Uh, ha, no, inhabitable.

• 27:04Janna Levin?

  Oh, okay.

• 27:05Speaker 03

  I'm not suggesting that, uh, there, there's, the prospects are gloomy, uh, but they're, um... They're not as optimistic, we can't be as optimistic as say a hundred years ago. I don't know if you remember, there was a famous-

• 27:17Janna Levin?

  A hundred years ago, I don't remember that well. I have like a vague memory.

• 27:21Speaker 03

  Oh, a hundred years ago, it was great.

• 27:23Janna Levin?

  What about you, Matt?

• 27:23Matt Kirshen?

  Were you drinking a lot back then?

• 27:26Speaker 03

  Well, let me tell you about it, I have been around a hundred years, but close. Okay, so back in the day, everybody knows about the Charles Lindbergh, uh, you know-

• 27:33Janna Levin?

  Yes.

• 27:34Speaker 03

  The solo trip across the Atlantic and he did it for a cash prize of whatever it was, fifty thousand dollars, which was a lot of money at the time. Well, there was a Frenchman at the time who put out a cash prize to anybody who would discover uh, intelligent life outside the earth. And various people and, but, there was a provision is you have to find the intelligent life uh, from some other civilization with the exception of Mars. Cause he thought it would be too easy.

• 28:05Janna Levin?

  Too easy.

• 28:05Speaker 03

  Too easy to find intelligent life on Mars. And so, you gotta, you know, I'm not gonna part with my a hundred thousand francs for-

• 28:13Janna Levin?

  Just to bring it back to eclipses, can't you see eclipses from Mars but with different bodies? I think, didn't the rover see-

• 28:21Speaker 03

  Well, they have, of course, they have some very small moons, uh, uh, Mars, Phobos and Deimos. Uh, they orbit really fast, uh, do they cast shadows on Mars? I think the answer is no.

• 28:31Janna Levin?

  I think they're too inclined or something.

• 28:33Speaker 03

  They're too small.

• 28:34Janna Levin?

  Oh, they're too small, okay.

• 28:35Speaker 03

  Now, the real adventure on eclipses is Jupiter. Because tho- those moons are moderately big and they're close in. So on any one night, people with a, with a sort of a small telescope-

• 28:48Janna Levin?

  Yeah.

• 28:49Speaker 03

  Portable telescope, uh, you can train it on Jupiter and the cha- your chances of getting, uh, seeing a little dark spot move on Jupiter are moderately good. They're like ten or twenty percent on a given night.

• 29:01Janna Levin?

  Wow.

• 29:01Speaker 03

  So if seven nights, you, you'll see several of them.

• 29:03Janna Levin?

  Wow.

• 29:04Matt Kirshen?

  And that's just one of Jupiter's many moons, just eclipsing a bit of Jupiter?

• 29:09Speaker 03

  Yeah, yeah. It's the four big moons that do it.

• 29:11Matt Kirshen?

  Right.

• 29:12Speaker 03

  Yeah, and one of them, it races around really fast and so it produces a lot of- You can actually, if you follow with a telescope with a lot of patience, astronomers are famous for, uh, then you can actually, from hour to hour, you can see it move on the planet.

• 29:25Janna Levin?

  So, apparently though, it's very hard to get solar glasses there.

• 29:29Matt Kirshen?

  Yeah.

• 29:29Janna Levin?

  Yeah, really are.

• 29:31Matt Kirshen?

  And a good place to stand.

• 29:31Janna Levin?

  Like worse than getting them in New York City.

• 29:33Matt Kirshen?

  Actually, what happens if you- Like Jupiter's a gas giant, right? Does that have any kind of solid rock or is it just gas? Is it collected? Would you just sink into Jupiter?

• 29:44Speaker 03

  Yes, you would. Jupiter, the surface of Jupiter is, if you tried to land on it, what would happen is your spacecraft would just kind of fall, keep going until you got to a place where your density was about equal to the density of the local surroundings.

• 30:01Matt Kirshen?

  And that's just the floating point?

• 30:03Speaker 03

  Yeah, that would be the floating point and you would just sort of float there.

• 30:06Janna Levin?

  Like the Dead Sea.

• 30:06Matt Kirshen?

  Yeah, or like, I'm just thinking about when I went scuba diving years back and you just, a lot of scuba diving is equalizing your density until you stay at a specific height.

• 30:16Speaker 03

  Is that right?

• 30:17Matt Kirshen?

  Or specific depth, I guess is the correct term, but yeah, and you're not meant to, you're not meant to swim up or down, you just increase or decrease the amount of air in your jacket and you just...

• 30:25Janna Levin?

  You're well-prepared for a trip to Jupiter.

• 30:27Speaker 03

  There it goes.

• 30:28Janna Levin?

  You're the first, we're sending you.

• 30:29Matt Kirshen?

  Yeah, so I think with my basic open water certification from 15 years ago, I'm more than qualified to be the first human on Jupiter.

• 30:37Janna Levin?

  Agreed. Qualifications mean nothing anymore.

• 30:40Matt Kirshen?

  Yeah, you know, I think the most important thing nowadays is just believing you can do it.

• 30:46Janna Levin?

  Yeah, just express your opinion on the web.

• 30:49Matt Kirshen?

  Yeah.

• 30:50Janna Levin?

  But I was gonna follow up-

• 30:51Matt Kirshen?

  Every opinion is equally valid, Jana.

• 30:53Janna Levin?

  It's true, in the comment section on Amazon. So Joe, you said something which I think is really interesting about your work, which is you said astronomers are known for their patience. And, and some of your research is based on things exploding. Things exploding, cannibalizing, you know, the kind of stuff that's really fun to do in the lab, like blow things up or smash them together. And, but you don't do it in the lab, you kind of wait patiently for, for nature to do these things. So tell me about one of, like, let's, let's pick up cataclysmic variables here. Can you tell us what those are?

• 31:35Speaker 03

  Yeah, well, these are star, they're, they're very close binary stars, in other words, uh, two, two distinct stars. Which are orbiting around each other typically every few hours. Okay, so in other words, a year in that binary would be, say, two hours.

• 31:50Janna Levin?

  So these immense things moving incredibly quickly.

• 31:53Speaker 03

  That's right. One of them is, one of them is a kind of a, a fairly normal star, but a very low mass star, like one fifth of a solar mass. Uh huh. And the other one is, is around one solar mass, but it's tiny, it's just the size of the earth.

• 32:08Janna Levin?

  So is it a dead star?

• 32:09Speaker 03

  It's a dead star.

• 32:10Janna Levin?

  It's already had its long life.

• 32:11Speaker 03

  It's a dead star, this, this one is, uh, this particular one's called the white dwarf. Um, and it's, uh, it's got the, um, uh, size of the earth, excuse me, the size of the earth, the mass of the sun. So the density is tremendous and, uh...

• 32:28Janna Levin?

  So did it, did it have a supernova event, or did it blow up? Did it, like, it had a long life?

• 32:33Speaker 03

  It had a long, it had a long life, the sun, the sun will become one of these.

• 32:36Janna Levin?

  Oh, so, so it just sort of, it just sort of distends?

• 32:40Speaker 03

  Yeah, the sun, the sun will, you know, slough off its outer layers.

• 32:44Janna Levin?

  Mm-hmm, vaporizing.

• 32:45Speaker 03

  And its inner part, because its outer layers will, uh, be responding to the inner layers that get very hot in the later stages of life. And so it kind of drives off the outer layers. What's left is the inner layer, which is a little bit, in our case, it'll be about half a solar mass. Half the mass will be expelled, the other half will be there.

• 33:04Janna Levin?

  Okay, so then it'll just sort of quietly, and then it just gets really dense, it tries to collapse.

• 33:08Speaker 03

  It tries to collapse, but then what happens is that the electrons kind of crystallize, actually, they sort of form a lattice.

• 33:14Janna Levin?

  Hmm.

• 33:15Speaker 03

  So a lot, I mean, we're surrounded by things that have crystallized, you know, rocks.

• 33:19Janna Levin?

  And they become hard and resistant to compression.

• 33:22Speaker 03

  Absolutely, a white dwarf would be quite a bit harder than, than the hardest diamond.

• 33:26Janna Levin?

  Hmm.

• 33:27Speaker 03

  And, um, anyway, so there are these things, they're going around, uh, each other, and, uh, what happens is the gravity from the white dwarf is so strong. Rips off matter from the other star, falls down onto the white dwarf. And that matter is hydrogen, it builds up. Well, hydrogen, as we have known since about 1950.

• 33:47Janna Levin?

  Yeah.

• 33:47Speaker 03

  Hydrogen will explode. If you put enough hydrogen at a high enough temperature.

• 33:52Janna Levin?

  Okay.

• 33:53Speaker 03

  It explodes.

• 33:54Janna Levin?

  So, like a nuclear weapon?

• 33:55Speaker 03

  It's exactly like a thermonuclear weapon.

• 33:57Janna Levin?

  Okay.

• 33:58Speaker 03

  Only it is all over the surface of the star.

• 34:01Janna Levin?

  Mm-hmm.

• 34:02Speaker 03

  All over the surface. If it were at the center, it would blow the star up.

• 34:06Janna Levin?

  Okay.

• 34:07Speaker 03

  But there is no hydrogen at the center.

• 34:08Janna Levin?

  Okay, so.

• 34:09Speaker 03

  The reason is the gravity is so strong in this star that the center is iron.

• 34:13Janna Levin?

  Mm-hmm.

• 34:14Speaker 03

  And then out beyond that is, you know, magnesium, you know, silicon, and then carbon, and then.

• 34:20Janna Levin?

  Great natural resources, all trapped.

• 34:23Speaker 03

  You can't get to them, they're all trapped.

• 34:25Janna Levin?

  You can't get to it.

• 34:26Speaker 03

  Absolutely. And it's all crystallized, and you have that hydrogen. So the hydrogen blows up about every, in the case of this star that fascinates me the most. About every 30 years, it happens.

• 34:35Janna Levin?

  Oh, really? So it's constantly cannibalizing its companion?

• 34:38Speaker 03

  Constantly cannibalizing its companion.

• 34:40Janna Levin?

  And then, but only every 30 years does it, like, hit criticality?

• 34:42Speaker 03

  Every 30 years it hits criticality. It's not like a, it's not like clockwork.

• 34:47Janna Levin?

  Okay.

• 34:47Speaker 03

  Sometimes it's 20, sometimes it's 40. But about every 30 years, it's happened six times in the last 140 years.

• 34:54Janna Levin?

  Wow.

• 34:55Speaker 03

  And the, just the recent one, just a few years ago. And then what happens there is, it expels all the gas around it. It expels all the gas that lay on the surface, all the hydrogen gas, that didn't get burned.

• 35:08Janna Levin?

  Mm-hmm.

• 35:09Speaker 03

  And it also oblates the companion, basically.

• 35:12Janna Levin?

  So it just blows it, what is it?

• 35:13Speaker 03

  Yeah, it kind of blows away the outer parts of the companion. Just a shell, just a little.

• 35:17Janna Levin?

  So I'm just imagining, like, this hairless sad creature.

• 35:20Matt Kirshen?

  Yep.

• 35:20Janna Levin?

  Just a sad.

• 35:21Matt Kirshen?

  No, it's actually really good for the other star's complexion.

• 35:26Speaker 03

  You guys have a very positive look on these things. We call it a mutual suicide pact. Because what happens is, because the secondary, the only reason this is happening is the secondary is feeding. It's feeding the white dwarf, and then the white dwarf is thanking it by basically sort of blowing it apart. So it's, I mean, this is.

• 35:46Janna Levin?

  Just a metaphor for life.

• 35:47Speaker 03

  This is what?

• 35:48Matt Kirshen?

  This is how you repay me.

• 35:49Speaker 03

  Yeah.

• 35:49Matt Kirshen?

  After all I've given to you.

• 35:50Speaker 03

  But it just keeps going, because they don't learn.

• 36:06Janna Levin?

  I'm Jan Levin. I'm here with my co-host, Matt Kirshen, comedian and co-host of Probably Science. Welcome, Matt. Thanks for coming all this way. I've been on your show a bunch.

• 36:17Matt Kirshen?

  You have.

• 36:18Janna Levin?

  We have to do it again.

• 36:19Matt Kirshen?

  You have. You're our go-to astrophysicist.

• 36:21Janna Levin?

  We haven't done a clip show.

• 36:23Matt Kirshen?

  We'll have to do that.

• 36:24Janna Levin?

  We'll do it again.

• 36:24Matt Kirshen?

  Anytime there's any kind of black hole story or anything like that, we're like, "Ah, we're stuck, Jan, help."

• 36:28Janna Levin?

  You guys have called me like in the middle of the night, seriously. I've been lying on the couch and Skyped with you guys and it's been like good material.

• 36:34Matt Kirshen?

  Well, thanks. Yeah, we've got a three-hour time difference as well. It's not like we're podcasting at midnight.

• 36:40Janna Levin?

  And we're also here with our expert scientist, Professor Joe Patterson, professor of astronomy at Columbia University, and also the director, right, of the Center for Backyard Astrophysics. I love that. What do you guys do for backyard astrophysics?

• 36:54Speaker 03

  Well, we're a collection of about 100 people scattered around the world, mostly amateur astronomers. There's a few professionals sprinkled in there, but mostly amateur astronomers with sophisticated telescopes in their backyards. And they're people who, you know, they started out in astronomy and looking at the moon and looking at the moons of Jupiter.

• 37:16Janna Levin?

  Is that how you started out?

• 37:18Speaker 03

  Couple galaxies, absolutely. That's how I started out. And then after a while, they thought, "Well, you know, maybe I could do science with the telescope."

• 37:26Janna Levin?

  Is that what you thought?

• 37:28Speaker 03

  I never thought that myself, no. And they look around and I've been, we've been running this organization now for 35 years, actually. So I'm pretty well-known in the amateur astronomy community. And they write me letters. They say, "Well, you know, here's my setup. Can I contribute to your research?" And I write back to them. I write lots of letters every day.

• 37:54Janna Levin?

  Wow.

• 37:57Speaker 03

  In some cases, it's, you know, like a small child in Uzbekistan or something.

• 38:03Janna Levin?

  It's amazing.

• 38:04Speaker 03

  So that's the, I don't get too much from that. But the, but interestingly enough, we actually got a very good station. There was an Air Force intelligence officer stationed in Uzbekistan. Who said, can I contribute to your research? Well, turns out our research needs global coverage because we follow star, follow the brightness of stars all the, you know, over 24 hour period.

• 38:27Janna Levin?

  Right.

• 38:27Speaker 03

  So we need stations all around the earth and Uzbekistan was a good place. And he was a great, great observer and he would send us data back on the brightness of stars. He was sort of spying on Al Qaeda by day and stars by night.

• 38:43Janna Levin?

  Don't tell us anymore about this guy. I just want him to live through the next StarTalk episode.

• 38:48Speaker 03

  Okay.

• 38:49Janna Levin?

  But you know what I love of the many things I love about this story is it combats the notion that science is elitist. Because, you know, it really is a subject of just almost childlike curiosity, right? Relating to the natural world. That's really what it is. It's got to be the least elitist subject imaginable. And yet, we have this reputation, I think, of being an elitist field. Do you think that that's true, that we have that reputation?

• 39:15Speaker 03

  Well, we do to some extent. It, I have to say, it's greatly mitigated by the great successes at popularizing astronomy, of which you are, you know, a very prominent example, of course.

• 39:33Janna Levin?

  Thank you.

• 39:34Speaker 03

  And as this program is, as a matter of fact.

• 39:37Janna Levin?

  And Neil.

• 39:37Speaker 03

  And absolutely, absolutely. Neil is, you know, tremendous energy and tremendous commitment to everybody. The last time I went, Neil and I are both big baseball fans. Went to a game with Yankin Stadium. And of course, everybody recognizes Neil and people come up to him.

• 39:56Janna Levin?

  Yeah.

• 39:57Speaker 03

  And they say, I remember this one guy in particular said,

• 40:02Speaker 03

  They don't know how to ask a question about astronomy.

• 40:05Janna Levin?

  Right.

• 40:05Speaker 03

  When the great Neil Tyson is there. And but so they can't figure out, but they have a friend, you know, who's an amateur astronomer. They call up their friend, say, hey, I'm in the next row here. Neil Tyson, do you have a question about astronomy? And they hide, they hide Neil the cell phone.

• 40:19Janna Levin?

  Oh, my head.

• 40:20Speaker 03

  They answer him, and he answers cheerfully.

• 40:23Janna Levin?

  That's so sweet.

• 40:24Speaker 03

  This is really sweet.

• 40:25Janna Levin?

  I know, he's got a really great demeanor. Like, I'm much grumpier than Neil. Amazing. So, we were talking earlier about blowing things up. And, and we were talking about the cataclysmic variables. But there is another phenomenon in which, well-known, things blow up spectacularly. And that's the supernova event. And you've been doing some research on this recently.

• 40:50Speaker 03

  Yeah, well, I mostly study what happens, you know, after the supernova event. Because what basically happens with, with a massive star is instead of just blowing off its outer layers, that has a thermo, that has a nuclear instability in the core. So that's the really dangerous place to ignite an instability in the core of the star. That will blow up most or all of the star. And it, it's a...

• 41:15Janna Levin?

  Now, isn't that good for us?

• 41:17Speaker 03

  Uh, well, I guess it...

• 41:19Janna Levin?

  And this is one of the things I really distinctly remember from your astronomy class when I first took it, how it's important for life that a star blows up. If stars never blew up, we're pretty much gonna say goodbye to emergent supply for the universe.

• 41:32Speaker 03

  If stars never blew up, we would be mostly hydrogen and helium creatures. That would be pretty uninteresting. Pretty boring. Very high pitched voices. Very high pitched voices, but helium has no chemistry at all. But if you, if we breathe, that we'd all have high pitched voices. Sound like Donald Duck. But the, um, yeah.

• 41:51Janna Levin?

  Thought you were gonna mention a different Donald.

• 41:52Speaker 03

  We need the supernova. The stars manufacture the heavy elements. But, but then they have to blow up.

• 41:59Janna Levin?

  Yeah, if they didn't blow up, right.

• 42:01Speaker 03

  And so they do blow up, and that's why you get everything up to uranium.

• 42:06Janna Levin?

  So, you've been studying supernovas. What's new? What's new in the field of stars blowing up? I mean, supernova events are amazing because they're one of the few things we can see with the naked eye. Like, one day, there's nothing there. Because the star was too faint to see. Then it blows up, and suddenly you see this big object in the sky. Why can you see it after it blows up? Why isn't it just gone?

• 42:30Speaker 03

  Well, basically, a couple of things happened. First of all, it's an enormous cloud. It becomes, you know, very, very big, much bigger than any star, and it's still, it's still dense. So they stay bright for, well, the famous, the most famous one of all, the one that made the Crab Nebula, it happened in the year 1054, on July 4th, patriotically enough.

• 42:51Matt Kirshen?

  How do we know it was 1054? Is that from historical records, or is that?

• 42:56Speaker 03

  Yeah, historical records, Chinese and Korean records of a bright thing appearing in the constellation Taurus, and they described where it was, and we know, they wrote it all down in books that we can read now, and we can, their constellations are now understood by Chinese scholars, and we know where it was, and that is the, where we now see a cloud of gas that is expanding slowly outward.

• 43:22Matt Kirshen?

  So you know that, okay, a supernova happened there, and then you're like, alright, well then, that's, they must have written, and you say both Chinese and Korean scholars wrote about it separately?

• 43:32Speaker 03

  They wrote about it separately.

• 43:33Janna Levin?

  And we can see it now?

• 43:34Speaker 03

  There's a big, we can see it now, it's very faint now, you need a moderate-sized

• 43:38Janna Levin?

  How long, how long was it bright for?

• 43:39Speaker 03

  Well, it was visible in daylight for a month.

• 43:44Janna Levin?

  In daylight?

• 43:46Speaker 03

  In daylight.

• 43:47Janna Levin?

  That's insane. That's like, the only thing that's visible in daylight for us is the moon, very, very, very rarely.

• 43:53Speaker 03

  That's right. Well, the sun, of course, but, sun is daylight. It was visible in daylight, and then it was visible in the night sky for, I believe, two years. In the night sky, meaning naked eye, because they didn't have any telescopes. And, and then, of course, faded, nobody knew about it, and then the telescope was invented, and suddenly it came back to history.

• 44:15Matt Kirshen?

  And then you're like, alright, it's still there.

• 44:17Speaker 03

  There it is, and then it was figured out.

• 44:19Matt Kirshen?

  So we can still detect it a full millennium later?

• 44:22Speaker 03

  We can see it a thousand years later, yeah, and we can still see it expanding outward.

• 44:26Janna Levin?

  It's still expanding outward?

• 44:28Speaker 03

  Oh yeah, it's still expanding outward, about a thousand kilometers a second, pretty hefty rate of expansion.

• 44:32Janna Levin?

  Wow.

• 44:33Speaker 03

  And...

• 44:34Janna Levin?

  And so it's giving all of that good stuff, the carbon, the heavy metals, all that good stuff, to its own environment?

• 44:42Speaker 03

  That's right.

• 44:42Janna Levin?

  And then, how does that lead to emergence of life? Like, that can't, like, it blows out, and then what?

• 44:50Speaker 03

  You're asking me to now, on StarTalk, explain the origin of life?

• 44:53Janna Levin?

  Yeah, well, no, not the origin of life, but I'm saying like, so the nebula expands outward, but then, then what? Like, how do you make a solar system out of that?

• 45:02Speaker 03

  Well, it has to mix in the galaxy. All this stuff is just gonna get mixed in the galaxy. Basically, about every thirty years, another supernova in some other part of the galaxy goes off. All this stuff mixes, and now the biologists have to come in and tell us how we're gonna get life.

• 45:24Janna Levin?

  That's another episode.

• 45:25Speaker 03

  Yeah, they should get to work.

• 45:26Janna Levin?

  So you were saying our solar system was the consequence of multiple supernova events.

• 45:31Speaker 03

  Absolutely.

• 45:31Janna Levin?

  Snow plowing, all of this great stuff together, these heavy elements together to make rocky planets and water and all this good stuff. That's not a bad scenario.

• 45:40Speaker 03

  Yeah, and there even, there's even one theory that says the origin of life, and you're probably familiar with this theory, that says the origin of life actually was the result of a nearby supernova. Because, you know, a nearby supernova, you know, what it does is it sort of compresses the blast wave from the, it actually compresses the gas around it, so you can sort of form new structures in the debris.

• 46:05Janna Levin?

  Like a snowplow.

• 46:06Speaker 03

  Like a soapstone.

• 46:08Janna Levin?

  Yeah, yeah. So what's, so we were asking you earlier, what's new in the supernova world that you're working on?

• 46:13Speaker 03

  Well, the big, the big thing that most people that study supernovae, this is the great discovery, it was made in 1998, discovered dark energy, and it was made possible by looking at the, there is a class of supernovae that have exactly the same intrinsic brightness.

• 46:30Janna Levin?

  Okay.

• 46:31Speaker 03

  Okay, so by looking at how faint they are in the sky, you can determine their distances very precisely.

• 46:37Janna Levin?

  Yeah.

• 46:38Speaker 03

  They're in galaxies.

• 46:38Janna Levin?

  Yeah.

• 46:39Speaker 03

  Those galaxies share in the Hubble Law of Expansion.

• 46:42Janna Levin?

  Mm-hmm.

• 46:42Speaker 03

  And so, they were the key to being able to basically test the velocity-distance relationship, which I'm.

• 46:50Janna Levin?

  So it's like, it's like I have a light bulb here, I move it further away, and because I know a lot about that light bulb, I can tell its distance.

• 46:58Speaker 03

  Yeah.

• 46:58Janna Levin?

  Because I know a lot about it ahead of time.

• 47:00Speaker 03

  Exactly.

• 47:00Janna Levin?

  So, so I can place that these light bulbs, which are the supernova, are actually in other galaxies, and I can tell that they're moving away, that they're, and therefore measure the expansion rate of the universe.

• 47:11Speaker 03

  That's right.

• 47:13Janna Levin?

  I knew that, but I was just recapping.

• 47:14Speaker 03

  Yeah.

• 47:14Janna Levin?

  For effect. It was a device.

• 47:17Speaker 03

  That's the big thing about supernovae. Our particular research is a little more on the remnant. Because many supernovae leave neutron stars behind. When you blow up a star, you don't necessarily blow up the whole star. You blow up the outer part of the star. The inner part of the star could be so compact that the gravity can survive that. And that frequently happens. And it makes neutron stars. And there's thousands of neutron stars in our galaxy. Some are in binary star systems. Those are the ones I like. Because we study these binary star systems. We can measure their periods. We can measure their rotations.

• 47:51Janna Levin?

  So what is a black widow pulsar?

• 47:53Speaker 03

  A black widow pulsar is a very tight binary, like a cataclysmic variable. Where the two stars are so close together that the pulsar beam, you know, pulsar is like a big...

• 48:03Janna Levin?

  So pulsar's a neutron star.

• 48:05Speaker 03

  So a rapidly rotating neutron star with a big sort of searchlight beam. Charged particles searching around, going around. Typically about...

• 48:14Janna Levin?

  It's a lighthouse.

• 48:14Speaker 03

  Yeah, like a lighthouse, going out around, say about 30 times a second. Or say 10 to 30 times a second.

• 48:22Matt Kirshen?

  So if you're at a specific point in space, you just see it flashing on and off?

• 48:25Speaker 03

  You'd see pulse, pulse, pulse, pulse, pulse.

• 48:27Janna Levin?

  So instead of a 24-hour period, it's a pretty fast period.

• 48:30Speaker 03

  It's less than a second. Most of them are less than a second. Some of them are a few seconds. But, you know, right about that. And so what happens is if there's another star that's in the vicinity of it, it keeps getting hit, hit, hit, hit. With all this energy, these electrically charged particles that are emitted, keep getting, they keep bombarding the other star. And basically, it's a black widow pulsar. The companion eats it.

• 48:56Janna Levin?

  On that note, I did, before we close the show, want to ask Matt to throw us a cosmic query to bring us back to remember that we were on this day, August 21st. Joe, your shirt has, "Where will you be on August 21st, 2017, the Great American Eclipse?" Where is the eclipse in that picture?

• 49:21Speaker 03

  The eclipse is down there in Tennessee.

• 49:22Janna Levin?

  In Tennessee. Okay. But you are not in Tennessee. So let's bring this back to the eclipse day, and I think we have a cosmic query.

• 49:28Matt Kirshen?

  We have one cosmic query from Ben Ratner. And that is, "On a planet from a binary system, what would a solar eclipse look like? And could a star create the eclipse of the other star?"

• 49:41Speaker 03

  Well, could a star create an eclipse of the other star? Absolutely.

• 49:47Speaker 03

  If it was a faint star occulting a bright star, that would be, you know, that would be like what we saw today. Or what people in totality saw today.

• 49:55Matt Kirshen?

  Uh huh.

• 49:55Speaker 03

  Yeah. It could be a bright star occulting a faint star and nobody would care.

• 50:00Matt Kirshen?

  Right.

• 50:02Speaker 03

  And

• 50:02Janna Levin?

  It's like the sun occulting a distant star. We don't care.

• 50:05Speaker 03

  Yeah, we don't care about that. And, uh, and so now I have to have a planet in there too?

• 50:10Matt Kirshen?

  And then the second thing, yeah, you've got a, you've got a planet. So there's

• 50:12Janna Levin?

  You're on the planet.

• 50:13Matt Kirshen?

  You've got a binary star and I guess there's a planet somehow orbiting in some, I imagine the orbit would be weird as well.

• 50:19Janna Levin?

  Are you on that planet or are you on a different planet?

• 50:21Matt Kirshen?

  I believe you're on that planet is my understanding.

• 50:24Speaker 03

  Okay.

• 50:25Matt Kirshen?

  And then, and then let's say there's a moon as well. Yeah, well

• 50:28Speaker 03

  Oh, please. Well, the moon probably is a small moon, so I'm gonna neglect the moon. But yeah, no, I was assuming the planet, the planet

• 50:35Matt Kirshen?

  A planet and another planet maybe.

• 50:37Speaker 03

  Yeah, the planet would normally see the binaries and then every so often they would line up and one would go in front of the other. I'm not sure it would be celebrated in any particular way unless it was the faint one going in front of the bright one. Because that's really what creates the spectacle.

• 50:51Janna Levin?

  Actually, maybe you could mention how we use that technique to look for exoplanets. So that's really cool.

• 50:58Speaker 03

  Yeah, absolutely. Well, of course, if you, um, very popular technique for, turns out extremely useful technique for finding exoplanets. Is just look at a nearby star and just watch it for, continuously say for six months or so. We have spacecraft and doing this. Humans can't do that, but spacecraft can do it.

• 51:21Janna Levin?

  I'm very patient.

• 51:22Speaker 03

  And what happens, what happens occasionally is that a planet will wander and if there is a planet up there. It may wander across the face and you'll see the face of that, you won't see light from the planet. But you'll see that the light from the star has a little dip in it.

• 51:37Janna Levin?

  Right.

• 51:38Speaker 03

  And then

• 51:38Janna Levin?

  It's an eclipse.

• 51:39Speaker 03

  Four days later, it has another little dip in it. And then another little dip in it. And then another little dip. And after about 10 of these things, you say, hey, it's regular. So if it's regular, it's not like, you know, the weather or something.

• 51:51Matt Kirshen?

  So something's orbiting.

• 51:52Speaker 03

  There is something orbiting it.

• 51:53Janna Levin?

  And we're literally using the eclipse of a tiny planet, so it's nowhere near a total eclipse. It's an absolutely teeny tiny partial eclipse.

• 52:02Matt Kirshen?

  Just enough to reduce the light intensity.

• 52:03Janna Levin?

  Yeah, so that from Earth, we can tell that the star has planets. And we can start to count the number of planets they have and estimate their sizes. I mean, that's a spectacular use of the eclipse phenomenon, basically. So we see other eclipses from Earth besides just solar.

• 52:17Speaker 03

  Yeah, I forgot all about those.

• 52:19Janna Levin?

  Isn't that great? I know, just occurred to me just now.

• 52:21Speaker 03

  Yeah, right.

• 52:22Janna Levin?

  You've been listening to StarTalk All Stars. Thank you so much for tuning in. I'm Jan Levin, your All Stars host. My co-host, Matt Kirshen. Hey. Wave, wave to the audio audience and a couple of video audiences. And our expert guest, scientist astronomer Joe Patterson. Thanks so much, guys, for coming. Thank you. It was so fun. Let's keep talking when the cameras are off. Salutations from the shadow of the moon, August 21st. See you next time.