Cosmic Queries – Life on Other Planets with Aomawa Shields

If scientists discovered that we are not alone, what would they do with that information? Neil deGrasse Tyson and Chuck Nice learn about the search for life, habitability around M stars and more with astrophysics professor and author Aomawa Shields.

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 on StarTalk, we speak with my friend and colleague, Aouma Shields. She's an associate professor of astronomy specializing in astrobiology at UC Irvine. And we talk about the search for life on planets that are already known to exist in orbit around their host stars. We're going to learn what M stars are. We're going to find out what the color of the star has to do with what life might be like on a planet's surface that orbits it. And we'll also take questions, cosmic queries from our Patreon members. All that and more, coming right up.

• 0:39Neil deGrasse Tyson?

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

• 0:52Neil deGrasse Tyson?

  This is StarTalk. Neil deGrasse Tyson here, your personal astrophysicist. I've got Chuck Nice with me, Chuck.

• 0:59Chuck Nice?

  Yes, doing it again.

• 1:02Neil deGrasse Tyson?

  Doing it again. The universe is nonstop.

• 1:05Chuck Nice?

  That's right.

• 1:06Neil deGrasse Tyson?

  And it is continually...

• 1:08Chuck Nice?

  Is it really though, Neil?

• 1:09Neil deGrasse Tyson?

  Yes.

• 1:10Chuck Nice?

  Does it? I mean, seriously, can we say with certitude that the universe does not stop? I mean...

• 1:16Neil deGrasse Tyson?

  If there's anything in the universe that doesn't stop, it's the universe itself.

• 1:20Chuck Nice?

  There you go.

• 1:21Neil deGrasse Tyson?

  Bam!

• 1:22Chuck Nice?

  Okay. I'm gonna, I'm gonna see your statement and raise your entropy, so I'm...

• 1:27Neil deGrasse Tyson?

  Ooh!

• 1:30Neil deGrasse Tyson?

  Today, we're talking about life on other planets.

• 1:33Chuck Nice?

  Yes!

• 1:33Neil deGrasse Tyson?

  Life on other planets. And we've got a friend and colleague of mine, Aouma Shields. So, she's an astrophysicist and, more specifically, an astrobiologist, which is kind of a new field, new in the last few decades. I'm old enough to call that new. Also, on the landscape of science communication, she's there, and she's a force. She's an associate professor in the Department of Physics and Astronomy at UC Irvine and founder of Rising Star Girls, a program dedicated to helping girls discover the universe.

• 2:09Chuck Nice?

  What?

• 2:10Neil deGrasse Tyson?

  I know!

• 2:11Chuck Nice?

  Watch out!

• 2:11Neil deGrasse Tyson?

  Also, also a trained actor.

• 2:14Chuck Nice?

  What? Now, wait a minute!

• 2:17Neil deGrasse Tyson?

  I know, I know!

• 2:17Chuck Nice?

  Wait a second!

• 2:18Neil deGrasse Tyson?

  Wait, wait, but I'm not done.

• 2:20Chuck Nice?

  Oh, cool.

• 2:20Neil deGrasse Tyson?

  I'm done until I'm done, all right? Now, she's got a new book out. All right, now you can react.

• 2:25Chuck Nice?

  Okay.

• 2:27Neil deGrasse Tyson?

  What?

• 2:32Neil deGrasse Tyson?

  And she's got a new book, Life on Other Planets: A Memoir of Finding My Place in the Universe. Whoa, and that comes out in the middle of 2023. Welcome back to StarTalk. I think we've had you on before.

• 2:46Speaker 02

  You have. Thank you. It's wonderful to be back. Last time, we were talking about terraforming Mars. And now we get to talk about more life on other planets, places where there actually could be life, although maybe Mars.

• 3:00Neil deGrasse Tyson?

  Yeah, plus I want to get to the bottom of what it means to have a book titled Life on Other Planets. And now you call it a memoir. Chuck, I think she's an alien. Okay, that's what I'm saying. This is the evidence we need. How was the trip?

• 3:13Speaker 02

  I have a lot to share. I have a lot of information now.

• 3:19Speaker 02

  Yes.

• 3:19Neil deGrasse Tyson?

  So we'll get to your book a little later. But let me just, can you update us on where are we in the search for life in the universe? Because you focus on the habitability of exoplanets and in multiplanet systems, what climate might be on those planets. So what are you doing when you go to work each day?

• 3:42Speaker 02

  Yes. So my team's work starts after the planets have actually been found. So it's hard enough, as you know, to find a planet around another star in its own.

• 3:53Neil deGrasse Tyson?

  Although we are going like gangbusters, we're approaching 6,000 planets.

• 3:56Speaker 02

  That's right.

• 3:57Neil deGrasse Tyson?

  So, yeah.

• 3:58Speaker 02

  And that's the tiniest fraction of our own galaxy. Never mind the fact that we have 100 billion plus galaxies in this universe.

• 4:07Neil deGrasse Tyson?

  Right.

• 4:07Speaker 02

  But yeah, we've got close to 6,000 now that we've found. And so, well, we don't really know anything about how habitable they might be, whether they might have water on their surfaces, which is what we define as habitable, because we know all life on Earth needs water. Everything from the tallest, largest elephant to the smallest, teeniest microbe needs water.

• 4:32Neil deGrasse Tyson?

  But you just confessed that you're completely biased. You're not just looking for life, you're looking for Earth life.

• 4:36Speaker 02

  That is true. That is true.

• 4:38Neil deGrasse Tyson?

  Okay, I just want you to fess up just right here and now. Show your cards. Okay.

• 4:43Speaker 02

  Very true. And this is why the field of astrobiology is so important, because there are astrobiologists like me who are looking for planets that might be warm enough for liquid water on the surface, but not too warm. And there are also astrobiologists whose job it is to ask the question, what about life as we do not know it? What about non-Earth-like life? Could, could life use something else besides water? Or something else besides carbon as in its backbone? So that's really important. We can't be so Earth-focused that we're mis-discovering life because of that.

• 5:20Neil deGrasse Tyson?

  Because I've seen some missions, they're looking for Earth-like planets around Sun-like stars. You can't get more sort of biased than that, it seems.

• 5:29Speaker 02

  True, true. And Sun-like stars are not the majority of the stars in our galaxy. The majority of the stars in our galaxy are actually much cooler, smaller, and redder than the Sun. So that brings up-

• 5:42Chuck Nice?

  That sounds to me like we should be looking there.

• 5:45Speaker 02

  I have spent a lot of my career focusing on that, right? These M stars, these cool, small stars.

• 5:52Neil deGrasse Tyson?

  M, so we're a G star, Sun is a G star.

• 5:56Speaker 02

  Yeah.

• 5:57Neil deGrasse Tyson?

  So with OBA of G, K, M. So M is like the coldest star category we have. So why would you think-

• 6:03Speaker 02

  Pretty cool. We have, we know of some even cooler ones now, like Ls and Ts. But then there's been some controversy. Are those really stars? Are we getting so cool that we're in the like brown dwarf regime? But, um-

• 6:16Neil deGrasse Tyson?

  And just to be clear, when an astrologist refers to a cool star, we're talking a few thousand degrees.

• 6:21Speaker 02

  Still, yeah, still really hot.

• 6:22Chuck Nice?

  Yes. Not, not Robert Downey Jr.

• 6:24Neil deGrasse Tyson?

  You'll still be incinerated.

• 6:28Speaker 02

  Yeah, it's all relative.

• 6:29Neil deGrasse Tyson?

  All right. So how do you modify your search for life around an M dwarf star?

• 6:36Speaker 02

  Yeah.

• 6:37Neil deGrasse Tyson?

  If you know it's not as warm as the Sun? So what happens to the habitable zone and other sort of properties that you're seeking?

• 6:44Speaker 02

  So if we want to look for a planet that could be what we call it, this habitable zone, or the Goldilocks zone, because it's not too close to its star, not too far away, so it's not too hot, not too cold. We have to look much closer to an M star than we would to around a sun-like star. In the same way that if you're, you know, say you're at on the beach and you're crowding around a little campfire, you're gonna have to stand much closer to that campfire to get the same amount of heat as you would if that campfire was a bonfire. But the same principle exists when we talk about these cool stars versus the hotter stars. So we're really close.

• 7:25Neil deGrasse Tyson?

  It just redraws your habitable zone.

• 7:27Speaker 02

  That's right.

• 7:27Neil deGrasse Tyson?

  That's all it does.

• 7:28Speaker 02

  Yeah, so it smushes it closer up. And there's some interesting things that can happen when a planet is orbiting that close in to its star. There's forces at work.

• 7:37Neil deGrasse Tyson?

  Yeah.

• 7:37Speaker 02

  There's tides. The planet pushes on the star, the star pushes on the planet, and the planet's rotation period can get slowed down and maybe even to the extreme case where there's one permanent day side and the other side it's always night. And we call that situation synchronous rotation. It's like this extreme case of tidal locking. And it's literally always day on the day side, always night on the night side. And, and my team.

• 8:09Neil deGrasse Tyson?

  It can't be good for life.

• 8:10Speaker 02

  People have thought that it would be really bad.

• 8:13Neil deGrasse Tyson?

  Not if you want a nap.

• 8:13Chuck Nice?

  Right, yeah.

• 8:14Neil deGrasse Tyson?

  So how are you gonna put life on a planet like that?

• 8:16Chuck Nice?

  Or maybe you just have like a work side of the planet and a party side of the planet.

• 8:20Neil deGrasse Tyson?

  Oh, I like that.

• 8:23Speaker 02

  Just go life on the night side?

• 8:25Neil deGrasse Tyson?

  So I get it. You don't wait for night to come.

• 8:27Chuck Nice?

  Yeah, you go tonight.

• 8:29Neil deGrasse Tyson?

  You go tonight. Oh, Chuck.

• 8:31Chuck Nice?

  It's like, yo, what you doing later? Yo, I'm going over tonight, bro. And we about, we gonna, we gonna top it up crazy like.

• 8:41Speaker 02

  And, you know?

• 8:43Neil deGrasse Tyson?

  It works.

• 8:43Speaker 02

  So that's, that has been a big concern. However, fresh off the presses, my team actually has some new work that shows that you could have life along the Terminator.

• 8:57Speaker 02

  The dividing line between the day and the night side. That's what we call the Terminator.

• 9:06Chuck Nice?

  So, so, and now, so, temperature wise, if it's always night and you're just never facing anything, that, that would be like a super cold part of the planet, right? Yeah.

• 9:16Neil deGrasse Tyson?

  Right, and then if they're always daytime, that'd be warm.

• 9:19Chuck Nice?

  That would be a super hot place, right?

• 9:20Neil deGrasse Tyson?

  So, there's gotta be a spot. That's just right.

• 9:23Chuck Nice?

  Right. Okay. And, and it's funny, the just right spot, you call the Terminator.

• 9:30Speaker 02

  Right? So, so, much more, much more amenable, much more neutral than our, our pop fiction Schwarzenegger Terminator. But I can't help, I cannot help, I, we coined this term Terminator habitable. And that's the name of our paper, and like, you can't not think about it.

• 9:49Chuck Nice?

  It's so doubly comfortable, very comfortable.

• 9:54Chuck Nice?

  It's like a warm bath.

• 9:57Neil deGrasse Tyson?

  So, before we continue, let me, if, if I may, I will give a, a brief tutorial on how stars got the letter classifications.

• 10:07Speaker 02

  Please.

• 10:08Neil deGrasse Tyson?

  So, you go back 120 years, we're getting data on stars that are not just pictures of them, but spectra. And we don't know what spectra are yet because quantum physics wasn't yet discovered. But we knew some spectra looked like others, and you could put them on a continuum, and you, that transition from one kind of spectrum to another. And so, we did that. And we lettered them, A, B, C, D, E, F, G, H, I, G, the elemental P. Okay. Then, quantum physics came around, and we said, yo, there are reasons why the spectra look this way, and it's not what you're thinking. And it had to do with the temperature of the star. And it turns out, these features can duplicate

• 10:53Neil deGrasse Tyson?

  between being too cool to have a feature, and too warm to have that same feature. By the time we shuffled these letters into a temperature sequence, A, B, C, D, E, F, G became O, B, A, F, G, K, M. And why didn't we just re-letter them? Which I think we should have at the time.

• 11:12Chuck Nice?

  Yeah.

• 11:12Neil deGrasse Tyson?

  But we didn't. Okay, so we have this artifact.

• 11:15Chuck Nice?

  Could have gone with numbers. Pretty simple.

• 11:17Speaker 02

  Yeah. Because now we get to confuse astronomy students the world over, year after year.

• 11:23Neil deGrasse Tyson?

  Forever and ever and ever.

• 11:25Speaker 02

  Every year I get that question.

• 11:27Neil deGrasse Tyson?

  So O stars are hot, and B stars are next hot. It's O, B, A, G, where G star. And then each category is split into 10 other subcategories. Okay, zero through nine. So we are the G2.

• 11:40Speaker 02

  Oh.

• 11:41Neil deGrasse Tyson?

  Okay, Arabic numeral two. Okay? And we divided them by what's called luminosity class. Like, how big are you? And so we have classes one through five, or four, or three, yeah, five. And so we are G, Roman numeral two. I've got G, Arabic numeral two, Roman numeral five. Wow. You tell that to an astrophysicist, they know exactly what kind of star you're talking about.

• 12:05Chuck Nice?

  G25.

• 12:05Neil deGrasse Tyson?

  It's code.

• 12:06Speaker 02

  Yep.

• 12:07Neil deGrasse Tyson?

  That's what it is.

• 12:07Chuck Nice?

  Sounds like something that rappers fly to their next concert in.

• 12:15Neil deGrasse Tyson?

  What would it be?

• 12:15Chuck Nice?

  Yeah. G25, baby.

• 12:18Neil deGrasse Tyson?

  So I'll, tell me, what did you need to do to model a Terminator habitability? Like, what kind of calculations were necessary there?

• 12:27Speaker 02

  Yes, and I have to give a shout out to my postdoc, Anna Lobo, who's spearheaded this work. And, you know, we had to ask that question, as I write in the book, that having this question, could these planets even exist? It's the first place to start for any scientist or any curious person.

• 12:46Neil deGrasse Tyson?

  That helps.

• 12:47Speaker 02

  You know?

• 12:48Neil deGrasse Tyson?

  Before you invent life on a planet, make sure that that kind of planet exists.

• 12:52Speaker 02

  Could actually exist. And the first thing we had to do, we're using models, climate models, that are normally used to predict the climate on Earth. So they're the same models that have been used to predict the effects of Climate change into the 2100s. The reason why we know that climate change is real and that it's going to continue unless we do something is in part because we're using these models to forecast those effects. But what we're doing-

• 13:19Neil deGrasse Tyson?

  And these models, so all you have to do is change some of the- They probably have knobs you can turn-

• 13:24Speaker 02

  That's right.

• 13:25Neil deGrasse Tyson?

  Where everything else, because the physics would just be the physics, but the rotation rate and the sun's energy-

• 13:32Speaker 02

  That's right.

• 13:33Neil deGrasse Tyson?

  -entering the system, these are knobs, right?

• 13:34Speaker 02

  These are knobs that we can turn, so we-

• 13:36Neil deGrasse Tyson?

  I didn't know these are general climate models. Fascinating.

• 13:38Speaker 02

  That's right. So we are changing the spectrum of the host star, right? How its energy, its light is distributed across the whole spectrum is going to be different depending on the temperature of the star, the type of star. We're changing how, the shape of its orbit, how much is in its, how much atmosphere, like what its atmospheric composition is. Because we don't know those things for Earth-sized planets. We have no information about the type of atmospheres they might have or their surfaces. And understanding the effects on climate of different types of atmospheres is going to help us understand which of these nearly 6,000 planets we want to prioritize and look at with next large generation telescopes

• 14:23Speaker 02

  to find out if there really is life there. So, you know-

• 14:27Neil deGrasse Tyson?

  So this is a beautiful example of the cross-pollination between two otherwise very different disciplines.

• 14:33Speaker 02

  Yes.

• 14:33Neil deGrasse Tyson?

  You go into climate science, folks, they don't care about exoplanets. They just care about Earth.

• 14:38Speaker 02

  I know, and I'm on a personal crusade to change that. Because it's true, like this is, it's so interdisciplinary. We're using atmospheric science, climate science, astronomy, geology in some cases, glaciology, because I'm all about ice and different types of ices. And different types of ices interact with different types of light, depending on the type of ice. There's more than just water ice. We're looking at CO2 ice and other-

• 15:03Neil deGrasse Tyson?

  So different ice would reflect their sunlight differently-

• 15:06Speaker 02

  Differently.

• 15:06Neil deGrasse Tyson?

  From other kinds of surfaces and would change how much energy enters the system.

• 15:11Speaker 02

  That's right.

• 15:11Neil deGrasse Tyson?

  Is that, did I say that right?

• 15:12Speaker 02

  That's exactly right.

• 15:24Speaker 03

  I'm Joel Cherico and I make pottery. You can see my pottery on my website, cosmicmugs.com. Cosmic Mugs, art that lets you taste the universe every day. And I support StarTalk on Patreon. This is StarTalk with Neil deGrasse Tyson.

• 15:45Neil deGrasse Tyson?

  So, Alma Wa, tell me, what, how does all this fold into this, this book that you just wrote?

• 15:51Speaker 02

  I'm so excited for this book. This has been a dream of mine for a long time. And as you know, I have, I was astronomer, then I trained, I changed and studied acting, and then I came back and finished my PhD and became a professional astronomer and a professor. And for the longest time, I was trying to reconcile these two things that I loved, acting and astronomy. And I thought that they couldn't coexist. I thought I had to choose. And when I would share with people those two loves, I got a lot of like, what? This is so strange. Why? How? And I, you know, I think I internalized that and tried to, you know, figure it out. And it was funny because when I stopped figuring it out, these incredible miracles

• 16:34Speaker 02

  got to happen where I saw how they can really coexist, like hosting a science TV show, which I could never have planned on my own. Eventually going back to grad school in part because of your suggestion and, you know, being put in touch with you and your mentorship. And also I had applied to the Astronaut Candidate Program and had not made, had not reached the next level. It was like everything was saying, go back, get your PhD. And I finally became willing to listen. And so, the book really is about that whole journey. It's about why I fell in love with the stars and the night sky, and why I fell in love with acting and this whole edge that I carried.

• 17:18Speaker 02

  For a long time of like, feeling like I was an astronomer or a scientist around actors, feeling like I was an actor around scientists, and eventually coming into full acceptance of this non-traditional background that I had and how it could really make me a better scientist and a better communicator because of it. It's about the whole journey.

• 17:41Chuck Nice?

  First of all, that's beautiful, what you just said, because it's a reconciliation of self, which I think is always a wonderful, wonderful thing that anyone has ever...

• 17:53Neil deGrasse Tyson?

  You could be a counselor, or something. You could be like a therapist.

• 17:57Chuck Nice?

  Yeah, if you want to mess up your life.

• 18:04Neil deGrasse Tyson?

  No, I think if you're in, if you have these loves, you know, I had, too had so secondary pathways, but none as significant in my life as your acting was. But I just did little things. I doodled, and I liked calligraphy when I should have been doing other things. But now when I sign my books, I use a calligraphic pen. And the people receive the book, they appreciate it that much. With little things like that, you find a way to fold it in, your life and the lives of others are much more enriched. So I'm so glad that you pursued what you love, rather than what people thought you should be doing.

• 18:37Speaker 02

  Thank you. I have to say, I still remember, and you're gonna find out, you probably read parts of it already, but if not, you'll see later, like, you're in the book.

• 18:47Neil deGrasse Tyson?

  I'm in the book.

• 18:48Speaker 02

  I write...

• 18:49Chuck Nice?

  Wait a minute, wait a minute. Am I in the book?

• 18:52Speaker 02

  You're gonna have to read it to find out.

• 18:57Neil deGrasse Tyson?

  And you're in the book.

• 19:01Speaker 02

  There are a lot of people who are in the book. But like, I write about that moment when, you know, I first met you in person at the AAAS, the American Astronomical Society. That's our professional conference, for those who don't know what AAAS means. And we sat, you know, on some umbrella chairs or whatever, and people were walking by like, "Is that..." Is that who we think it is? Is that Neil deGrasse Tyson? And, you know, and, and you were just there. And I think I like started to cry at one point because I, you know, I'd be, we'd been talking about my background and how I had, no, I had, there were ups and downs. I had struggled academically because my head was not in the place, like my, my heart and my head were not in the same place.

• 19:43Chuck Nice?

  You know? You know, it's funny because I cried when I met Neil too.

• 19:49Chuck Nice?

  But, but that's because he was standing on my foot the whole time he was talking to me. And he's a big guy. I'm telling you, he's a large man. It was not pleasant.

• 20:01Neil deGrasse Tyson?

  Wait, I almost, plus it didn't help matters that you also married an actor. Isn't that right? If I remember correctly, is that correct?

• 20:07Speaker 02

  I did, yes. And he is 100% actor. He doesn't have the like, my actor, scientist, engineer, architect.

• 20:14Neil deGrasse Tyson?

  Distractions, distractions.

• 20:15Speaker 02

  He's 100% actor, although he does enjoy those like doomsday Nat Geo shows or like super volcano or, you know?

• 20:23Neil deGrasse Tyson?

  Okay, yeah, yeah.

• 20:24Speaker 02

  And he's a.

• 20:25Neil deGrasse Tyson?

  That's in us.

• 20:26Speaker 02

  He's a lot.

• 20:26Neil deGrasse Tyson?

  But what I'm saying is that, that, that would have been a force that would have been supportive of your acting, correct? And I presume.

• 20:32Speaker 02

  Absolutely. We met in acting grad school. He was my classmate.

• 20:36Neil deGrasse Tyson?

  Oh.

• 20:36Chuck Nice?

  You were, you were becoming a real actor. She said acting grad school.

• 20:41Speaker 02

  Yes.

• 20:41Chuck Nice?

  Okay?

• 20:42Speaker 02

  Well, this is. I, yeah, I.

• 20:45Chuck Nice?

  That's, that's the real stuff.

• 20:46Speaker 02

  Yeah.

• 20:47Chuck Nice?

  Okay? That's when you're just like, you know how people say, well, I'm going to be an actor? And they're like, well, you're never going to get a job. If, when you say, I'm going to acting grad school, they'll be like, oh, you getting a job.

• 20:58Speaker 02

  One would hope. That's what we hoped and expected. That wasn't always the case, but yes.

• 21:04Chuck Nice?

  Right.

• 21:04Speaker 02

  We, I wanted to study it in the same way that I studied astronomy. I, you know, and, and, and that was so much fun, you know? I after, so I had left the PhD program that I was struggling academically in and I had a old white male professor tell me to consider other career options and, you know, and I internalized that and, um, and left. And, you know, when I got to acting grad school, it was like I was. It was like I was free. I felt so light. They, but it wasn't like it was easier compared to astronomy grad school. It was harder in a different way. And I write about this. It was like, it didn't, it wasn't necessarily about the brain cells working over time.

• 21:49Speaker 02

  It was about dredging up my emotions and feelings and childhood experiences and like bringing it all up, you know, that I needed to use it to embody these different characters.

• 21:59Neil deGrasse Tyson?

  Summoning it on command.

• 22:00Speaker 02

  Yeah.

• 22:00Neil deGrasse Tyson?

  Summoning it on command. Yeah.

• 22:01Chuck Nice?

  It's gotta be real. It's gotta be real.

• 22:04Neil deGrasse Tyson?

  Yeah. So you stitched this, you've made a tapestry of your life with your professional ambitions in this book. So it's part memoir, part, part advice column? Is that, is that fair?

• 22:17Speaker 02

  Yeah, there's a little bit of, there's certainly, it's all spoken for the most part in the first person. Like, this is what I did. This is what helped me make my life better and reconcile these different parts of myself. And I hope that I'm writing it for the people that have that question of like, is it too late? There's that part of me that I never could, you know, bring up into my life and, but it's always been there. Like I say in the book, it's, when you leave a dream behind, it never dies. It's like sitting on the side of the road and eventually it'll catch up. And that's what happened for me, you know? And, and the whole, the message of the book is that it's not too late and that if there's no role model that's doing what you want to do, you can be your own role model.

• 23:03Neil deGrasse Tyson?

  Yeah, yeah. That's right. And in fact, if you always needed a role model, you would only ever do things that other people did before you. But sometimes you have to trailblaze. And like you just said, if you become your own role model, that's harder, of course. And you gotta figure things out on the fly. But if, and when you succeed, then people will say, of course, that's what I always wanted to do. Those who come behind you. So just congratulations on that.

• 23:29Speaker 02

  Yeah, thank you.

• 23:30Chuck Nice?

  It's fantastic.

• 23:30Neil deGrasse Tyson?

  Well Chuck, let's get to some queries.

• 23:32Chuck Nice?

  All right, why not?

• 23:33Neil deGrasse Tyson?

  Specially tuned for this visit.

• 23:34Chuck Nice?

  Absolutely.

• 23:37Neil deGrasse Tyson?

  These are questions from our Patreon members?

• 23:39Chuck Nice?

  Patreon patrons who, just for a hal tree, almost insignificant, $5 a month. All right. This is Mike Parker. And Mike Parker says, hello, Dr. Shields. Mike Parker here from Richmond, Virginia.

• 23:57Chuck Nice?

  If life does exist in our solar system, which planet or moon do you think offers the most promising location?

• 24:08Neil deGrasse Tyson?

  I love it. In fact, give me the top three cases in order.

• 24:11Speaker 02

  Oh, my gosh.

• 24:11Neil deGrasse Tyson?

  Not just one.

• 24:12Speaker 02

  Okay, this is a fantastic question. Thank you for asking it. Europa, which is Jupiter, a moon of Jupiter, would be my top. Even though there's a lot of buzz right now around Saturn's moon Enceladus, which would be my number two, the next one. Saturn's moon Enceladus has geysers, geysers of liquid water that are shooting out from its south pole. And there was a recent-

• 24:37Neil deGrasse Tyson?

  Can't, can't argue with geysers.

• 24:39Speaker 02

  And apparently, all of the basic elements of life are there.

• 24:43Chuck Nice?

  There you go. Geysers lead to geysers. Geysers lead to geysers.

• 24:50Neil deGrasse Tyson?

  Chuck, I don't think that's how language works.

• 24:52Chuck Nice?

  Okay.

• 24:54Speaker 02

  And then, gosh, number three.

• 24:56Neil deGrasse Tyson?

  And third one, give me the third one.

• 24:58Speaker 02

  I'm thinking. I mean, I'm skeptical about Mars, but yeah.

• 25:07Neil deGrasse Tyson?

  Mars, the undersurface Mars.

• 25:09Speaker 02

  Undersurface.

• 25:10Neil deGrasse Tyson?

  Where you know there might be some liquid water in aquifers.

• 25:12Speaker 02

  Yeah.

• 25:13Neil deGrasse Tyson?

  I'll be your third, your third option.

• 25:15Speaker 02

  I was about to say that, but I'm skeptical. But yes, I-

• 25:18Chuck Nice?

  Or it could be Mars might have fossilized life.

• 25:22Neil deGrasse Tyson?

  Okay.

• 25:23Chuck Nice?

  So the life was there, it's no longer there, but that still counts. Because it ain't here. It ain't here. If we can prove that it was there, it still counts as life because it was there.

• 25:32Speaker 02

  True. And we have so much-

• 25:34Neil deGrasse Tyson?

  I'll give you that.

• 25:35Speaker 02

  And there's so much evidence of liquid water on the surface at some point.

• 25:40Neil deGrasse Tyson?

  At one point, yeah.

• 25:41Chuck Nice?

  Right, right.

• 25:42Neil deGrasse Tyson?

  Excellent. Excellent question there.

• 25:43Speaker 02

  Yes.

• 25:43Chuck Nice?

  Nice question, Chuck. Mike Parker, way to go. All right, here we go. This is Sherry. Uh, Carissu and Sheri Carissu says, "Hello, Dr. Shields. Do the ideal conditions for life on extrasolar planets depend on the star itself? Or are the requirements the same no matter what? Also, thank you, thank you for Rising Star Girls. I am registering my niece. You are an inspiration, Sheri from San Diego."

• 26:17Speaker 02

  Thank you so much, Sheri, for asking that question and can't wait to see your niece in Rising Star Girls workshops. Rising Star Girls hosts summer, we host annual virtual workshops during the summer for middle school girls of color. And that means ages 10 to 14 or 15 roughly.

• 26:38Chuck Nice?

  Oh, wow.

• 26:40Speaker 02

  No one is turned away.

• 26:41Chuck Nice?

  It's virtual?

• 26:41Speaker 02

  And they're virtual. So we have girls-

• 26:43Chuck Nice?

  So no matter where you are.

• 26:44Speaker 02

  That participate from all over the country. And we even have girls participate from other countries, too. And we're ramping up to do even more. We also host educator webinars where we we show educators how to use the activities in our handbook with girls in their own communities all over the world. So, and, and back to your question, the ingredient, we, the primary ingredients for life are liquid water or a liquid, which on our planet is water. And as we know, we can't just look for water, but that's, like, that's our first order thing. We're looking for some liquid that, that life can use to make its, uh,

• 27:27Speaker 02

  the stuff it needs to carry out its chemical processes and reactions. Some kind of energy source, whether it's the sun, the star, or chemical energy, like life that lives in the deep ocean around these hydrothermal vents has no access to sunlight, and yet there's life there. So it's using the chemistry of rocks and heat from, from the, the core of the earth.

• 27:50Neil deGrasse Tyson?

  Can I add there that when I was taught biology, it was only assumed that life could thrive- It was assumed that life could only use sunlight because we hadn't discovered the life at the bottom of the ocean yet. So they had to broaden the definition. Not that life depends on the sun, but life depends on an energy source. So I like this, that that's now folded into that definition. Okay, so keep going.

• 28:12Speaker 02

  And then the last one is the basic building blocks of life, like some and some kind of environment for life to to make its, you know, to carry out its metabolic processes and to use. So we we think of this like it needs sulfur or phosphorus or oxygen or nitrogen or carbon. These are like the basic elements of life. So.

• 28:37Neil deGrasse Tyson?

  Organic chemistry.

• 28:38Speaker 02

  Yeah, the organics, organics.

• 28:41Neil deGrasse Tyson?

  Okay.

• 28:41Speaker 02

  Energy source and liquid.

• 28:43Neil deGrasse Tyson?

  Mm hmm.

• 28:43Speaker 02

  Um, so all of those things are what we look for when we're looking for a planet that could be habitable. And for what I the part that I am really focused on is where could the climate be suitable for water to not freeze, not evaporate away, but to stay in in liquid form somewhere on that surface. Um, and so this can be affected by the type of star as you bring up in your question, because this starlight can be different depending on the temperature of the star, how that starlight interacts with the surface of the planet, the various atmospheric molecules on that planet, that can influence the planet's

• 29:26Speaker 02

  climate. So it does depend on the star. Um, but those three ingredients are the main ingredients that that we think any kind of planet would need to host life, to keep life going for, you know.

• 29:41Chuck Nice?

  Now you just made me think of a question that I've, if it's a dumb question, just let me know.

• 29:45Speaker 02

  There are no dumb questions.

• 29:47Chuck Nice?

  That that is not true. You not you have not heard me ask questions. When people say there's no dumb questions, I'm like, just wait. Um, no, but so are are there different stars that give off different colors and can look like our star is white? Are there different stars that give off different colors and can those different colors actually affect the development of light? I mean, of life?

• 30:10Speaker 02

  That is the complete opposite of a dumb question. That is a fantastic question. So yeah, I'm not going to believe anything you say now.

• 30:19Chuck Nice?

  Okay.

• 30:20Speaker 02

  It's not a tough question.

• 30:22Chuck Nice?

  It just popped in my head. So when it just pops in my head, I'm like, maybe that's a dumbass question.

• 30:25Speaker 02

  Never, never. So, yes, different stars have different colors. And if you, if you are fortunate enough to live someplace where you don't have a lot of light pollution, if you go out on your porch or your stoop and look up, you'll see this. You'll see this in action, that all of the stars don't all look the same. Some of them look white, some of them look yellow, some look a little orange or a little red. And if they're twinkling, that's a pretty good bet that that's a star. If it, if it's not twinkling, then you can be more convinced that it's a planet. There's a lot more stuff between us and a star than there is between us and a planet in our own solar system.

• 31:09Speaker 02

  And so there's a lot more atmospheric distortion and turbulence, and that's what we see as twinkling. But anyway, yes, the colors, the colors are real, and that has to do with the temperature of the star and how much light it's emitting. And that, that light, again, that's gonna, if, if there's a planet around that star, and just about every star in our galaxy has a planet around it. It may not be in the habitable zone, but just about every star has a planet. Then that planet, if it's got an atmosphere, if it's got a surface, that light is gonna be shining down on that planet. And how, how much light is, in what region of the spectrum, the color of that light

• 31:52Speaker 02

  is definitely gonna influence how it interacts with what's on that planet. And, and the weather, the temperature, the climate of that planet.

• 32:01Neil deGrasse Tyson?

  So you have one of the most complicated problems to solve out there, it seems to me. Because it's not just light shining in a planet, it's like, how does the chemistry of the atmosphere interact with the light that's shining down on the planet? Does it get absorbed? Does it get re-emitted? Is it reflected? And then if it reaches the surface, then you gotta worry about the surface. And, and somewhere in there, maybe there's light.

• 32:22Speaker 02

  It's so true.

• 32:23Neil deGrasse Tyson?

  This sounds like a really hard problem.

• 32:24Speaker 02

  It is a really hard problem, because those same, those same cool stars that, you know, comprise 70% of all stars in the galaxy, those M stars, they're really awesome because they're so numerous, and there's a lot of advantages. To looking for life around those stars, but there's some disadvantages too. They have really long phases where they send out a lot of X-ray and UV radiation shooting towards the surface. And we know the reason why we wear sunscreen is that UV radiation is not good for biology. And so it could be that, you know, life could only exist at the bottom of the ocean on those planets. It really

• 33:03Neil deGrasse Tyson?

  Where you're protected from the UV.

• 33:05Speaker 02

  Where you're protected.

• 33:06Neil deGrasse Tyson?

  Water's a good UV absorber.

• 33:07Chuck Nice?

  Yeah.

• 33:08Neil deGrasse Tyson?

  Yeah.

• 33:09Chuck Nice?

  Okay, cool. Super cool.

• 33:21Neil deGrasse Tyson?

  All right, Chuck, keep it coming.

• 33:23Chuck Nice?

  All right, here we go. This is Omar Marcelino. And Omar says, hello, Dr. Tyson, hello Chuck and Dr. Shields. Omar here from Dallas, Texas. Dr. Shields, given your unique journey through the cosmos of astronomy and theater, two fields that are often mentioned never in the same sentence, let alone in the same career, you have boldly gone where few have gone before and leading the way in ensuring others from diverse backgrounds can do the same through your work with your Rising Star Girls. In your perspective, how could this universe of diverse talent and experiences propel us further into the final frontier? How do you think incorporating a spectrum of perspectives in astronomy could accelerate

• 34:07Chuck Nice?

  our interstellar mission to understand and reach other worlds?

• 34:12Speaker 02

  Whoa.

• 34:13Chuck Nice?

  Now, wait a minute. Is your husband named Omar?

• 34:17Speaker 02

  Is he about to be? No, I'm kidding. That was an excellently written question and recited. So, yeah, I'm gonna say Omar, you wanna read this book.

• 34:34Chuck Nice?

  Oh, look at that.

• 34:36Speaker 02

  This has got the whole journey in there, pretty much everything.

• 34:39Neil deGrasse Tyson?

  I see what you did there.

• 34:40Speaker 02

  And go to risingstargirls.org because you'll see, we're not just teaching these girls astronomy and astrobiology. We're not just saying, hey, there's stars out there, there's galaxies, these are the names of it. They get to write a poem about what they're learning. They get to design their own exoplanet and make Choices about how many stars it orbits and if there's life there and if there's not, why not? They get to write their own constellation myths. They get to calculate the distance from themselves, from the Earth to different solar system bodies and units of themselves. So we're doing this all to develop a personal connection between these girls and the universe

• 35:24Speaker 02

  of which they're an integral part. So we're processing what they learn through a creative arts-based lens. And I wanted to bring it back to Rising Star Girls because that's really, my journey has been epitomized by this program of like, they're not these, the arts and the sciences are not as disparate as many people might think. In both cases, it's about the story, right? Everything has a story. Planets, stars, they all live, right? And they die. And there's a story of their becoming and there's a story of their evolution and there's a story of their deaths.

• 36:05Neil deGrasse Tyson?

  Except planets don't have mother issues. Right. Later on.

• 36:10Speaker 02

  That's right.

• 36:11Neil deGrasse Tyson?

  There's certain stories they're not going to tell, I'm pretty sure.

• 36:15Speaker 02

  Yeah, the stories, the stories are different, but they, but there's.

• 36:19Neil deGrasse Tyson?

  There are stories nonetheless.

• 36:20Speaker 02

  There's stories, right?

• 36:21Neil deGrasse Tyson?

  Stories nonetheless.

• 36:22Speaker 02

  Or the stories of humans on the stage or on the screen, right? Looking to live, as, as one of my method acting teachers used to say, right? Trying to find happiness and fulfillment. So there's that whole like science and the arts. And in fact, not only are they not as disparate as we might think, but they actually, interweaving them is the key in my mind to answering your question is to creating imaginative thinkers and enlightened scientists and enlightened artists for that matter, realizing that these disciplines can fuel each other, can be used to, right, to elevate our, our core understanding of the human experience and the, the universal experience.

• 37:06Speaker 02

  So that, that would be my. My best way to to answer that really exciting question.

• 37:13Neil deGrasse Tyson?

  And can I answer that as a minimum? In a day when only men did science, it means half the population of the world, half the intellectual capital of our species was not at the table.

• 37:24Speaker 02

  That's right.

• 37:24Neil deGrasse Tyson?

  At the time, anyone is thinking about how the universe works. So the extent to which you can extend that to have 100% of our species have access to, whether they choose it, that's another question.

• 37:36Speaker 02

  Right.

• 37:37Neil deGrasse Tyson?

  But if they don't access to it, then you can ensure that that we're getting the best minds who want to actually think about our past, present, and future in the universe.

• 37:47Speaker 02

  Yeah.

• 37:47Neil deGrasse Tyson?

  And right now, that is not the case.

• 37:49Speaker 02

  Yeah, that is absolutely not the case.

• 37:50Chuck Nice?

  Physically, it was half. Percentage wise, it was way more than half.

• 38:03Neil deGrasse Tyson?

  Okay, it was half of the mass, but and less than half the actual brain power.

• 38:07Chuck Nice?

  There you go.

• 38:10Speaker 02

  Yeah, and we want these girls to claim ownership of what they're learning. You know, to know that that they matter, that they're an integral part of this universe. That, you know, just in the same way that if we were to look at the Milky Way galaxy through one, one type of light, just visible light. All right, you'd see like this, this thin, right, this thin line with a bunch of dark clouds in it, and you'd think there was nothing there. If all you looked at, if you looked towards the center of the Milky Way galaxy, that swath of space that some of us can see if we go out in the desert. If you just thought that that was the only...

• 38:46Neil deGrasse Tyson?

  None of us could see. Yeah. Remaining 3% of the population of the world.

• 38:51Speaker 02

  Right, where there's no extra light pollution. Right, if you thought, if we thought there was nothing there, we'd miss out on so much information about this galaxy. But if we looked at the infrared, we see so much, so much going on. Right, never mind UV and gamma, there's so much more, right, to the, to the galaxy than meets the eye. So too is there so much more to these girls than meets the eye. We want them to have that that ownership of that star, that planet, that galaxy that they're studying so that when they continue on and the heavy math comes in, they'd be less likely to leave the field because they think, oh, you know, I didn't get that question right on that test. I didn't know someone told me that, you know, I shouldn't be here,

• 39:36Speaker 02

  right? Just knowing that they, they, there's a connection that they have between what they're learning and who they are, um, that we hope will really help them stay.

• 39:46Neil deGrasse Tyson?

  All right, cool. All right, let's see if we can slip in two more questions, Chuck.

• 39:49Chuck Nice?

  All right. Well, here's one from Carrie Manaberg. And Carrie says, hi, Dr. Shields. Is there any scientific evidence that life on Earth came here from an interaction with a comet or asteroid that had biological foundation chemicals?

• 40:01Speaker 02

  Oh, oh, this is a, this is a popular question within the astrobiology community. I believe that the term for this is panspermia, um, right? That something comes in from other, from elsewhere and like seeps their

• 40:16Chuck Nice?

  Seeds us.

• 40:17Speaker 02

  Yeah.

• 40:17Chuck Nice?

  Yeah.

• 40:18Speaker 02

  Um, it's, I mean, of course, it's possible. I don't think it's been given very much, um, funding, to be honest, uh, and in terms of exploration of this topic, but it certainly has been discussed within astrobiology communities.

• 40:37Chuck Nice?

  Okay.

• 40:39Neil deGrasse Tyson?

  Okay.

• 40:39Chuck Nice?

  All right. Okay, this is Jason. He says, uh, hello, Dr. Shields. Do you have any personal moral quandaries about science moving forward? Or is pretty much just forget morals and let's just see how far we can go. Now, I don't know if Jason is making an indictment of any sort or not. Well, you know, that's a, that's a very specific

• 41:01Neil deGrasse Tyson?

  It's starting out with the premise that all scientists are immoral.

• 41:05Chuck Nice?

  Yeah, basically. But I think, I think I know what he means. It's like scientists want to discover, what if you and you too, Neil, had the opportunity to make a discovery that would enlighten, but there was a larger chance that it would destroy? Would you still expose that discovery? That's a moral quandary.

• 41:32Speaker 02

  Yeah, this is an important question. This hearkens back to the last episode that I was fortunate enough to be on with you, where we talked about terraforming and we talked about some of the moral and ethical implications of that question of is it okay to terraform another planet or terraform Mars. I do think that as scientists, ethics must be key. So I don't subscribe to the view that science and discovery at all costs. There's a piece that I've written for an upcoming periodical that's like, why do this? Why look for life elsewhere?

• 42:15Speaker 02

  Why spend billions of dollars doing all of this? And is that object, umuamua, that first interstellar object, is it really an alien's craft? Or is it just, can it be explained by regular scientific method? I think what it comes down to is if we go, and I'm talking about this in the context of the search for life elsewhere, there's all sorts of other genetics and questions about cloning and all of that that have their own ethical implications. But from my part of the sphere on that question, can we, if we were to discover that we are

• 42:58Speaker 02

  not alone, what would we do with that information? Would we have to go and visit? Or could we stay on our planet and know that we're not alone and let that information inform how we think and feel and move throughout the world? Or would we need to go? And if we would need to go and visit, could we just go and visit and then come back home? Or would we need to stay? And if we needed to stay, could we just stay and not try to conquer? Or would we have to go the way that that and emulate what was done on our planet with Columbus and Magellan and and all the rest and the implications of that, right, that led

• 43:43Speaker 02

  to genocide? It, I would hope that we would be able to learn from the lessons of the past and not repeat them. And that really is what I think it all comes back to is is hope. You know, I have no clear answer about what other scientists might do and maybe even what I might do if given the opportunity to go to another world and and communicate with other, you know, other species. But I I carry with me the hope that I would want to do whatever we do from a place of love, kindness, inclusivity, and welcome and humility, to be honest.

• 44:26Speaker 02

  So that I think is the key that that to be a scientist, I must concede that there is more that that that out there that can be explained and I can hold on to that humility and help and and allow that to guide to serve as a north star for me morally. Um, so.

• 44:45Chuck Nice?

  Well, that that is beautiful. And as as a comedian, let me just say this, that ain't happening.

• 44:51Neil deGrasse Tyson?

  It's not gonna happen.

• 44:52Chuck Nice?

  That is not what is gonna happen.

• 44:54Neil deGrasse Tyson?

  Well, but I got two reactions. One, I how charming it was that you thought we would go find aliens on another planet and that we might exploit them.

• 45:04Speaker 02

  It's just. Oh, rather than like Independence Day and they're gonna come and kill us.

• 45:10Chuck Nice?

  Yeah, yeah, yeah. And believe me, if we go see them, they're not answering the door. They're gonna play the role just like we Jehovah's Witnesses or something. They'll be like, they're here.

• 45:20Speaker 02

  Right.

• 45:21Chuck Nice?

  Don't let them, we're not, get away from the window.

• 45:24Speaker 02

  But that question.

• 45:25Chuck Nice?

  Get away from the window.

• 45:26Neil deGrasse Tyson?

  I've never had heard anyone talk about an encounter with aliens and talk about we exploiting them. That is like never, I don't know, any storyline. If you're thinking of that storyline, that is completely.

• 45:40Speaker 02

  But of course, but of course, it mirrors our, what happened on our planet. I mean, you know, how could I not think of it that way, you know, that like.

• 45:47Neil deGrasse Tyson?

  You know, you know why I think about it? I think if they come here and they do what we do to each other.

• 45:52Chuck Nice?

  Oh, Lord.

• 45:53Neil deGrasse Tyson?

  It's as we portray in the films, then we're creating them not.

• 46:00Neil deGrasse Tyson?

  Based on a supposition of how they would behave, but on actual knowledge of how we did behave.

• 46:06Speaker 02

  Hmm.

• 46:07Neil deGrasse Tyson?

  So in fact, all of the alien movies are mirrors to our culture as you.

• 46:12Speaker 02

  Treating it almost like a guidebook or a recipe.

• 46:15Neil deGrasse Tyson?

  Yes, yes. And I couldn't help, you have to publish a paper on the interstellar visitor Amuamua. So we have Aomawa.

• 46:26Speaker 02

  I know, it's so close.

• 46:30Neil deGrasse Tyson?

  We need that research paper.

• 46:31Speaker 02

  I write it, I write in the book, I say, "Umua-mua, it sounds like my name."

• 46:36Chuck Nice?

  Yeah, that's great.

• 46:37Neil deGrasse Tyson?

  Aomawa studies Amuamua.

• 46:39Speaker 02

  That's right.

• 46:41Neil deGrasse Tyson?

  But Amuamua is Hawaiian and Aomawa, does that have some origins?

• 46:44Speaker 02

  My parents made it up. They made up vowel sounds, they put together, they're musicians, they made a chant up. But yeah, that sounds, I went to Hawaii.

• 46:53Neil deGrasse Tyson?

  They sounded like hippies. They sound like some leftover hippies right there.

• 46:56Chuck Nice?

  Very nice, very nice.

• 46:58Neil deGrasse Tyson?

  Well, at least you weren't named Moon Unit, okay?

• 47:00Speaker 02

  Right, or Moonbeam.

• 47:01Chuck Nice?

  Right, or Pilot Inspector. I mean, come on. That's unfortunate.

• 47:06Speaker 02

  Yeah. But yeah, "Umua" means messenger from afar arriving first.

• 47:12Neil deGrasse Tyson?

  Yes, the first messenger, yes. Yeah, yeah. So guys, we gotta end it there. That's sad.

• 47:19Chuck Nice?

  Oh my God. That is good.

• 47:21Neil deGrasse Tyson?

  Thanks for being on and congratulations again.

• 47:23Speaker 02

  Thank you so much, Neil, and thank you, Chuck. It's great to be here.

• 47:27Neil deGrasse Tyson?

  All right, Chuck, good to have you, man.

• 47:29Chuck Nice?

  Always a pleasure.

• 47:30Neil deGrasse Tyson?

  All right, I'm Neil deGrasse Tyson, your personal astrophysicist for StarTalk. As always, I bid you to keep looking up.