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. Originally Aired July 11, 2023.

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

• 0:00Neil deGrasse Tyson?

  Hey, StarTalkians. Neil here. You're about to listen to an episode specially drawn from our archives to serve your cosmic curiosities. The archives run deep. If you enjoy this, take a peek at the full catalog on your favorite podcast platform. There's a lot there to tickle your geek underbelly. Check it out.

• 0:24Neil deGrasse Tyson?

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

• 0:33Neil deGrasse Tyson?

  StarTalk begins right now.

• 0:37Neil deGrasse Tyson?

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

• 0:44Chuck Nice?

  Yes.

• 0:46Neil deGrasse Tyson?

  Doing it again. Doing it again. The universe is nonstop.

• 0:50Chuck Nice?

  That's right.

• 0:51Neil deGrasse Tyson?

  And it is continually.

• 0:52Chuck Nice?

  Is it really though, Neil? Is it really?

• 0:54Neil deGrasse Tyson?

  Yes.

• 0:55Chuck Nice?

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

• 1:02Neil deGrasse Tyson?

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

• 1:05Chuck Nice?

  There you go.

• 1:06Neil deGrasse Tyson?

  Bam.

• 1:07Chuck Nice?

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

• 1:12Neil deGrasse Tyson?

  Ooh.

• 1:15Neil deGrasse Tyson?

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

• 1:18Chuck Nice?

  Yes.

• 1:18Neil deGrasse Tyson?

  Life on other planets. And we've got a friend and colleague of mine, Aouma Wa 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.

• 1:54Chuck Nice?

  What?

• 1:55Neil deGrasse Tyson?

  I know.

• 1:56Chuck Nice?

  Watch out.

• 1:56Neil deGrasse Tyson?

  Also, also a trained actor.

• 1:59Chuck Nice?

  What? I know. Now, wait a minute.

• 2:02Neil deGrasse Tyson?

  I know, I know.

• 2:02Chuck Nice?

  Wait a second.

• 2:04Neil deGrasse Tyson?

  But I'm not done.

• 2:05Chuck Nice?

  Oh, cool.

• 2:05Neil deGrasse Tyson?

  Until I'm done. All right. Now, she's got a new book out.

• 2:09Chuck Nice?

  Okay.

• 2:10Neil deGrasse Tyson?

  Now you can react.

• 2:11Chuck Nice?

  Okay. What?

• 2:17Neil 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.

• 2:31Speaker 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, I don't know.

• 2:45Neil 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.

• 2:53Chuck Nice?

  Okay, that's what I'm saying.

• 2:55Neil deGrasse Tyson?

  This is the evidence we need.

• 2:55Chuck Nice?

  How was the trip?

• 2:58Speaker 02

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

• 3:04Speaker 02

  Yes.

• 3:04Neil deGrasse Tyson?

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

• 3:28Speaker 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 and it's.

• 3:38Neil deGrasse Tyson?

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

• 3:41Speaker 02

  That's right.

• 3:42Neil deGrasse Tyson?

  So.

• 3:43Speaker 02

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

• 3:52Neil deGrasse Tyson?

  Right.

• 3:52Speaker 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.

• 4:17Neil deGrasse Tyson?

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

• 4:21Speaker 02

  That is true. That is true. And this is why.

• 4:24Neil deGrasse Tyson?

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

• 4:28Speaker 02

  Very true. And this is why the, 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 there, that's really important. We can't be so Earth-focused that we miss discovering life because of that.

• 5:03Chuck Nice?

  Hmm.

• 5:04Neil deGrasse Tyson?

  Hmm. But 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.

• 5:14Speaker 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.

• 5:27Chuck Nice?

  That sounds to me like we should be looking there.

• 5:30Speaker 02

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

• 5:37Neil deGrasse Tyson?

  M. So we're a G star. Sun is a G star.

• 5:41Speaker 02

  Yeah.

• 5:42Neil deGrasse Tyson?

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

• 5:49Speaker 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.

• 6:01Neil deGrasse Tyson?

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

• 6:06Speaker 02

  Still, still really hot.

• 6:07Chuck Nice?

  Yes. Not, not Robert Downey Jr.

• 6:09Neil deGrasse Tyson?

  You'll still be incinerated.

• 6:13Speaker 02

  Yeah, it's all relative.

• 6:14Neil deGrasse Tyson?

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

• 6:21Speaker 02

  Yeah.

• 6:22Neil 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?

• 6:29Speaker 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 on the beach and you're crowding around a little campfire, you're going to 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.

• 7:11Neil deGrasse Tyson?

  It just redraws your habitable zone.

• 7:12Speaker 02

  That's right.

• 7:12Neil deGrasse Tyson?

  That's all it does.

• 7:13Speaker 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.

• 7:22Chuck Nice?

  Yeah.

• 7:23Speaker 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.

• 7:54Neil deGrasse Tyson?

  It can't be good for life.

• 7:55Speaker 02

  People have thought that it would be really bad.

• 7:58Chuck Nice?

  Right, yeah.

• 7:59Neil deGrasse Tyson?

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

• 8:01Chuck Nice?

  You just have like a work side of the planet and a party side of the planet.

• 8:06Neil deGrasse Tyson?

  Oh.

• 8:07Speaker 02

  I like it. Just go life on the night side.

• 8:10Neil deGrasse Tyson?

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

• 8:13Chuck Nice?

  Yeah, you go tonight.

• 8:14Neil deGrasse Tyson?

  You go tonight. Oh, Chuck.

• 8:16Chuck Nice?

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

• 8:26Speaker 02

  And.

• 8:27Neil deGrasse Tyson?

  All right.

• 8:28Speaker 02

  You know?

• 8:28Neil deGrasse Tyson?

  It works.

• 8:29Speaker 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. Dun dun dun dun dun dun dun dun. The dividing line between the day and the night side. That's what we call the Terminator.

• 8:52Chuck 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?

• 9:01Speaker 02

  Yeah.

• 9:02Neil deGrasse Tyson?

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

• 9:04Chuck Nice?

  That would be a super hot planet, right?

• 9:05Neil deGrasse Tyson?

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

• 9:09Chuck Nice?

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

• 9:15Speaker 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. We coined this term Terminator habitable, and that's the name of our paper. And like, you can't not think about.

• 9:34Chuck Nice?

  Dably comfortable. Very comfortable.

• 9:40Chuck Nice?

  It's like a warm bath.

• 9:43Neil deGrasse Tyson?

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

• 9:52Speaker 02

  Please.

• 9:54Neil 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 could, that transitioned 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, K, L, M, N, O, 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.

• 10:33Neil deGrasse Tyson?

  And it turns out these features can duplicate 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.

• 10:53Neil deGrasse Tyson?

  And why didn't we just re-letter them, which I think we should have at the time?

• 10:57Chuck Nice?

  Yeah.

• 10:58Neil deGrasse Tyson?

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

• 11:00Chuck Nice?

  Could have gone with numbers. Pretty simple.

• 11:02Speaker 02

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

• 11:08Neil deGrasse Tyson?

  Forever and ever and ever.

• 11:11Speaker 02

  Every year I get that question.

• 11:12Neil deGrasse Tyson?

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

• 11:25Chuck Nice?

  Oh.

• 11:26Neil 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, Arabic, Arabic numeral two, Roman numeral five. Wow. You tell that to an astrophysicist, they know exactly what kind of star you're talking about.

• 11:50Chuck Nice?

  G25.

• 11:51Neil deGrasse Tyson?

  It's code.

• 11:51Speaker 02

  Yep.

• 11:52Neil deGrasse Tyson?

  That's what it is.

• 11:52Chuck Nice?

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

• 12:00Neil deGrasse Tyson?

  What would it be?

• 12:01Chuck Nice?

  Yeah, G25, baby.

• 12:03Neil deGrasse Tyson?

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

• 12:12Speaker 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.

• 12:31Neil deGrasse Tyson?

  That helps.

• 12:32Speaker 02

  You know?

• 12:33Neil deGrasse Tyson?

  Before you invent life on a planet, make sure that that kind of planet could actually exist.

• 12:39Speaker 02

  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...

• 13:04Neil deGrasse Tyson?

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

• 13:09Speaker 02

  That's right.

• 13:10Neil deGrasse Tyson?

  Where everything else, because the physics would just be the physics, but the rotation rate and the, and the sun's energy entering system. These are knobs, right?

• 13:20Speaker 02

  These are knobs that we can turn, so we...

• 13:21Neil deGrasse Tyson?

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

• 13:24Speaker 02

  That's right. So we are changing the spectrum of the host star, right? How its, 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

• 14:04Speaker 02

  at with next large generation telescopes to find out if there really is life there. So, you know...

• 14:12Neil deGrasse Tyson?

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

• 14:18Speaker 02

  Yes.

• 14:18Neil deGrasse Tyson?

  Right, you go into climate science, folks, they don't care about exoplanets, right? They just care about Earth.

• 14:23Speaker 02

  I know, and I'm on a personal crusade to, 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 these 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 ice.

• 14:48Neil deGrasse Tyson?

  So different ice would reflect their sunlight differently.

• 14:51Speaker 02

  Differently.

• 14:51Neil deGrasse Tyson?

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

• 14:56Speaker 02

  That's right.

• 14:56Neil deGrasse Tyson?

  Is that, did I say that right?

• 14:58Speaker 02

  That's exactly right.

• 15:08Speaker 03

  I'm Nicholas Costella and I'm a proud supporter of StarTalk on Patreon. This is StarTalk with Neil deGrasse Tyson.

• 15:21Neil deGrasse Tyson?

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

• 15:27Speaker 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

• 16:10Speaker 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

• 16:49Speaker 02

  with acting and this whole edge that I carried 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. But there's, it's about the whole journey.

• 17:16Chuck Nice?

  First of all, that's, 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...

• 17:28Neil deGrasse Tyson?

  You could be, you could be a counselor. You could be like a therapist.

• 17:32Chuck Nice?

  Yeah, if you want to mess up your life.

• 17:40Neil deGrasse Tyson?

  No, I think if you're, if you have these loves, you know, I had, I had two head 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 received the book, they appreciated 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.

• 18:13Speaker 02

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

• 18:23Neil deGrasse Tyson?

  I'm in the book, okay.

• 18:24Speaker 02

  I write...

• 18:24Chuck Nice?

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

• 18:28Speaker 02

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

• 18:33Neil deGrasse Tyson?

  And you're in the book. And you're in the book.

• 18:35Speaker 02

  Who isn't in the book? 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 had, you know, 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.

• 19:19Chuck Nice?

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

• 19:36Neil deGrasse Tyson?

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

• 19:43Speaker 02

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

• 19:50Neil deGrasse Tyson?

  Distractions.

• 19:51Speaker 02

  He's 100% actor, although he does enjoy those like doomsday Nat Geo shows or like Super Volcano or, you know...

• 19:59Neil deGrasse Tyson?

  Okay, yeah, yeah.

• 20:00Speaker 02

  And he's a...

• 20:00Neil deGrasse Tyson?

  That's in us.

• 20:01Speaker 02

  He's a lot...

• 20:02Neil deGrasse Tyson?

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

• 20:08Speaker 02

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

• 20:12Neil deGrasse Tyson?

  Oh.

• 20:12Chuck Nice?

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

• 20:16Speaker 02

  Yes.

• 20:17Chuck Nice?

  Okay? Listen.

• 20:19Speaker 02

  I, yeah, I...

• 20:20Chuck Nice?

  That's, that's the real stuff.

• 20:22Speaker 02

  Yeah.

• 20:23Chuck Nice?

  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're getting a job.

• 20:34Speaker 02

  One would hope.

• 20:36Speaker 02

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

• 20:40Chuck Nice?

  Right.

• 20:40Speaker 02

  We, I wanted to study it in the same way that I studied astronomy, I, you know, and, and that was so much fun, you know, after, so I had left the PhD program that I was struggling academically in, and I had an old white male professor tell me to consider other career options and, you know, and I internalized that and, and left. And, you know, when I got to acting grad school, it was like I was...

• 21:07Speaker 02

  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 overtime. 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.

• 21:34Neil deGrasse Tyson?

  Summoning it on command.

• 21:35Speaker 02

  Yeah.

• 21:36Neil deGrasse Tyson?

  Summoning it on command. Yeah.

• 21:37Chuck Nice?

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

• 21:40Neil 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?

• 21:53Speaker 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.

• 22:39Neil 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.

• 23:05Speaker 02

  Yeah, thank you.

• 23:05Chuck Nice?

  It's fantastic.

• 23:06Neil deGrasse Tyson?

  Well Chuck, let's get to some queries.

• 23:07Chuck Nice?

  All right, why not?

• 23:08Neil deGrasse Tyson?

  Especially tuned for this visit.

• 23:10Chuck Nice?

  Absolutely.

• 23:13Neil deGrasse Tyson?

  These are questions from our Patreon members?

• 23:15Chuck Nice?

  Patreon patrons who, just for a halter, almost insignificant, $5 a month. All right, this is Mike Parker. And Mike Parker says, hello, Dr. Shields. Mike Parker here from Richmond, Virginia. If life does exist in our solar system, which planet or moon do you think offers the most promising location?

• 23:44Neil deGrasse Tyson?

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

• 23:47Speaker 02

  Oh, my gosh.

• 23:47Neil deGrasse Tyson?

  Not just one.

• 23:48Speaker 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-

• 24:12Neil deGrasse Tyson?

  Can't, can't argue with geysers.

• 24:14Speaker 02

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

• 24:19Chuck Nice?

  There you go.

• 24:19Neil deGrasse Tyson?

  Geysers lead to geezers.

• 24:22Chuck Nice?

  Geysers lead to geezers.

• 24:26Neil deGrasse Tyson?

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

• 24:28Chuck Nice?

  Okay.

• 24:30Speaker 02

  And then, gosh, number three.

• 24:31Neil deGrasse Tyson?

  And third one, give me your third one.

• 24:34Speaker 02

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

• 24:42Neil deGrasse Tyson?

  Mars, the under, undersurface Mars.

• 24:45Speaker 02

  Undersurface.

• 24:45Neil deGrasse Tyson?

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

• 24:48Speaker 02

  Yeah.

• 24:49Neil deGrasse Tyson?

  I'll be your third, your third option.

• 24:50Speaker 02

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

• 24:53Chuck Nice?

  Or it could be Mars might have fossilized life.

• 24:58Neil deGrasse Tyson?

  Okay.

• 24:58Chuck Nice?

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

• 25:08Speaker 02

  True. And we have so much-

• 25:10Neil deGrasse Tyson?

  I'll give you that.

• 25:11Speaker 02

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

• 25:15Neil deGrasse Tyson?

  At one point. Yeah.

• 25:16Chuck Nice?

  Right, right.

• 25:17Neil deGrasse Tyson?

  Excellent. Excellent question there.

• 25:19Speaker 02

  Yes.

• 25:19Chuck Nice?

  Nice question, Chuck. Mike Parker, way to go. All right, here we go. This is Sheri 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.

• 25:53Speaker 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, we host annual virtual workshops during the summer for middle school girls of color. And that means ages 10 to 14 or 15 roughly.

• 26:14Chuck Nice?

  Oh, wow.

• 26:15Speaker 02

  No one is turned away.

• 26:16Chuck Nice?

  It's virtual?

• 26:17Speaker 02

  And they're virtual. So we have girls-

• 26:19Chuck Nice?

  So no matter where you are.

• 26:20Speaker 02

  That participate from all over the country. And we even have girls participate from, from other countries too. And we're, 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

• 27:01Speaker 02

  make its, 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. And-

• 27:26Neil 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.

• 27:48Speaker 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-

• 28:13Neil deGrasse Tyson?

  Organic chemistry.

• 28:14Speaker 02

  Yeah, the organics, organics.

• 28:17Neil deGrasse Tyson?

  Okay.

• 28:17Speaker 02

  Energy source and liquid. 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. 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

• 29:01Speaker 02

  climate. So it does depend on the star. 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, a long time.

• 29:17Chuck Nice?

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

• 29:21Speaker 02

  There are no dumb questions.

• 29:23Chuck 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. No, but, so are, are there different stars that give off different colors? And can the, 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?

• 29:46Speaker 02

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

• 29:54Chuck Nice?

  Okay.

• 29:55Speaker 02

  It's not a tough question.

• 29:57Chuck Nice?

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

• 30:01Speaker 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.

• 30:45Speaker 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. 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

• 31:28Speaker 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.

• 31:36Neil 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 the 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?

• 31:50Speaker 02

  Yep.

• 31:51Neil deGrasse Tyson?

  Is it reflected?

• 31:52Speaker 02

  Yeah.

• 31:52Neil deGrasse Tyson?

  And then if it reaches the surface, then you gotta worry about the surface. And, and somewhere in there, maybe there's light.

• 31:58Speaker 02

  It's so true.

• 31:58Neil deGrasse Tyson?

  This sounds like a really hard problem.

• 32:00Speaker 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...

• 32:39Neil deGrasse Tyson?

  Where you're protected from the UV.

• 32:41Speaker 02

  Where you're protected.

• 32:41Neil deGrasse Tyson?

  Water is a good UV absorber.

• 32:43Chuck Nice?

  Yeah.

• 32:43Speaker 02

  Yeah.

• 32:44Chuck Nice?

  All right. Okay, cool. Super cool.

• 32:57Neil deGrasse Tyson?

  All right, Chuck, keep it coming.

• 32:58Chuck 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

• 33:41Chuck Nice?

  could accelerate our interstellar mission to understand and reach other worlds?

• 33:48Speaker 02

  Oh. Whoa.

• 33:51Chuck Nice?

  Now, wait a minute, is your husband named Omar?

• 33:57Speaker 02

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

• 34:10Chuck Nice?

  Oh, look at that.

• 34:11Speaker 02

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

• 34:15Neil deGrasse Tyson?

  I see what you did there.

• 34:16Speaker 02

  And go to risingstargirls.org, because you'll, 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, of which they're an integral part.

• 35:02Speaker 02

  So we're, 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 then there's a story of their deaths, right?

• 35:42Neil deGrasse Tyson?

  Except planets don't have mother issues.

• 35:44Chuck Nice?

  Right.

• 35:48Speaker 02

  That's right.

• 35:48Neil deGrasse Tyson?

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

• 35:51Speaker 02

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

• 35:54Neil deGrasse Tyson?

  There are stories nonetheless.

• 35:56Speaker 02

  There's stories, right? 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, right, the universal experience.

• 36:42Speaker 02

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

• 36:49Neil 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 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.

• 37:12Speaker 02

  Right.

• 37:12Neil 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.

• 37:22Chuck Nice?

  Yeah.

• 37:22Speaker 02

  Yes.

• 37:23Neil deGrasse Tyson?

  And right now, that is not the case.

• 37:25Speaker 02

  Yeah, that is absolutely not the case.

• 37:26Chuck Nice?

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

• 37:39Neil deGrasse Tyson?

  Okay, it was half of the mass, but, but in less than half the actual brain power of the universe. I get it.

• 37:45Speaker 02

  Yeah, and, 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, 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...

• 38:22Neil deGrasse Tyson?

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

• 38:27Speaker 02

  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. And 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, oh, someone told me that, you know, I shouldn't be here, right?

• 39:11Speaker 02

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

• 39:21Chuck Nice?

  All right, cool.

• 39:23Neil deGrasse Tyson?

  All right, let's see, we've slipped in two more questions, Chuck.

• 39:25Chuck 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?

• 39:37Speaker 02

  Ooh. Ooh, this is a, this is a popular question within the astrobiology community. I believe that the term for this is panspermia.

• 39:47Chuck Nice?

  Yes.

• 39:47Speaker 02

  Right, that something comes in from other, from elsewhere and like, seeds the earth.

• 39:52Chuck Nice?

  Seeds us.

• 39:53Speaker 02

  Yeah.

• 39:53Chuck Nice?

  Yeah.

• 39:55Speaker 02

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

• 40:13Chuck Nice?

  Hmm, okay.

• 40:14Neil deGrasse Tyson?

  Okay.

• 40:15Chuck Nice?

  All right. Okay, this is Jason. He says, 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.

• 40:35Chuck Nice?

  That's a, that's a very specific question.

• 40:37Neil deGrasse Tyson?

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

• 40:40Chuck 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.

• 41:08Speaker 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?

• 41:51Speaker 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

• 42:34Speaker 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, emulate what was done on our planet with Columbus

• 43:14Speaker 02

  and Magellan and all the rest and the implications of that, that led to genocide? 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 hope. 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 communicate with other species. But I carry with me the hope that I would want to do whatever we do from a place of

• 43:52Speaker 02

  love, kindness, inclusivity, and welcome and humility, to be honest. So that, I think, is the key, that to be a scientist, I must concede that there is more out there that can be explained and I can hold on to that humility and allow that to serve as a north star for me morally.

• 44:18Chuck Nice?

  Well, that is beautiful. And as a comedian, let me just say this, that ain't happening. That is not what is gonna happen.

• 44:30Neil deGrasse Tyson?

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

• 44:40Speaker 02

  Oh, rather than like Independence Day and they're gonna come and kill us?

• 44:46Chuck 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 Jehovah's Witnesses or something. They'll be like, they're here. Don't let them, we're not, get away from the window.

• 45:00Speaker 02

  But that question-

• 45:01Chuck Nice?

  Get away from the window.

• 45:02Neil 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-

• 45:15Speaker 02

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

• 45:22Neil deGrasse Tyson?

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

• 45:28Chuck Nice?

  Oh, Lord.

• 45:29Neil deGrasse Tyson?

  -as we portray in the films, then we're creating them not based on a supposition of how they would behave, but on actual knowledge of how we did behave. So in fact, all of the alien movies are mirrors to our culture, as you-

• 45:47Speaker 02

  Treating it almost like a guidebook or a recipe.

• 45:51Neil deGrasse Tyson?

  Yes, yes. And I couldn't help, you have to publish a paper on the interstellar visitor, Umuamua. So we have Au Maua-

• 46:02Speaker 02

  I know, it's so close to my-

• 46:05Neil deGrasse Tyson?

  We need that research paper.

• 46:07Speaker 02

  I write in the book, I say, "Umuamua, it sounds like my name."

• 46:11Chuck Nice?

  Yeah, that's great.

• 46:13Neil deGrasse Tyson?

  Au Maua studies Umuamua.

• 46:15Speaker 02

  That's right.

• 46:16Neil deGrasse Tyson?

  But Umuamua is Hawaiian and Au Maua, does that have some origins?

• 46:20Speaker 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 once-

• 46:29Neil deGrasse Tyson?

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

• 46:32Chuck Nice?

  Very nice, very nice.

• 46:33Neil deGrasse Tyson?

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

• 46:35Speaker 02

  Right, or Moon Beam.

• 46:37Chuck Nice?

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

• 46:42Speaker 02

  But yeah, Umuamua means messenger from afar arriving first.

• 46:47Neil deGrasse Tyson?

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

• 46:56Chuck Nice?

  This is good.

• 46:57Neil deGrasse Tyson?

  Thanks for being on and congratulations again.

• 46:59Speaker 02

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

• 47:02Neil deGrasse Tyson?

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

• 47:04Chuck Nice?

  Always a pleasure.

• 47:05Neil deGrasse Tyson?

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