Rogue Planets & Exomoons with David Kipping

Did we discover an exomoon? Neil deGrasse Tyson and Chuck Nice learn about the search for exoplanets with biosignatures, super Earths & mini Neptunes, and whether rogue planets outside of a solar system could harbor life with astrophysicist David Kipping.

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

• 0:00Neil deGrasse Tyson?

  So Chuck, love me some David Kipping.

• 0:01Chuck Nice?

  Yes.

• 0:02Neil deGrasse Tyson?

  Gets on his skateboard, comes down from Columbia.

• 0:04Chuck Nice?

  From Columbia.

• 0:06Neil deGrasse Tyson?

  Catches us up on all the cool stars out there.

• 0:08Chuck Nice?

  And I gotta tell you, you're not supposed to say it, but he's very good looking.

• 0:13Neil deGrasse Tyson?

  Coming up on StarTalk.

• 0:19Neil deGrasse Tyson?

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

• 0:32Neil deGrasse Tyson?

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

• 0:38Chuck Nice?

  Yeah, what's up? What's up Neil?

• 0:39Neil deGrasse Tyson?

  Chuck, baby.

• 0:40Chuck Nice?

  Hey.

• 0:41Neil deGrasse Tyson?

  All right. This is gonna be Cosmic Queries.

• 0:42Chuck Nice?

  Oh, okay. Good.

• 0:44Neil deGrasse Tyson?

  One of our favorite people out there in the hood.

• 0:47Chuck Nice?

  That's right. The boy band of astrophysics, a boy band of one, a heartthrob, no doubt.

• 0:55Neil deGrasse Tyson?

  We have the one, the only. David Kipping, David, welcome back to StarTalk.

• 0:58Speaker 02

  I don't deserve the introduction, but I will take it. Thank you. Very kind.

• 1:03Neil deGrasse Tyson?

  And I have to announce that you're based in Columbia University, which is up the street a couple of miles. And you skateboarded here. It wasn't even a skateboard. What do you call the thing with the single wheel?

• 1:18Chuck Nice?

  Oh, that's a, that's a uni- a unicycle.

• 1:23Speaker 02

  That's what it is.

• 1:24Chuck Nice?

  It's a unicycle.

• 1:26Neil deGrasse Tyson?

  Literally, yes. Hoverboard style. So you are Associate Professor of Astronomy up in Columbia. That's where I got my PhD, Columbia University. And you are the host of Cool World Podcast.

• 1:45Speaker 02

  Cool World YouTube show and a podcast.

• 1:47Neil deGrasse Tyson?

  Yes, yes. Cool World.

• 1:49Chuck Nice?

  The same, same name.

• 1:51Speaker 02

  I always find people get confused. I say, even when I just had a YouTube channel and I'd say, I'd describe to people like, oh, so tell me about your podcast. I'm like, no, no, that's a different, a podcast is a different thing.

• 2:01Speaker 02

  Yes, we have a main, why do you like these kind of mini documentaries about space and universe and things I'm working on? And then we have the podcast.

• 2:07Chuck Nice?

  So it's a Cool World Podcast and YouTube channel.

• 2:10Speaker 02

  You got it.

• 2:10Chuck Nice?

  There you go.

• 2:11Neil deGrasse Tyson?

  Yeah. So David, you study exoplanet.

• 2:14Speaker 02

  That's right. Yeah.

• 2:14Neil deGrasse Tyson?

  Last I checked, we were rising through 6,000 of these things in the catalog, pushing 7,000.

• 2:20Speaker 02

  I've stopped counting at this point.

• 2:22Neil deGrasse Tyson?

  I'm old enough to remember when there were none. Okay.

• 2:25Chuck Nice?

  Right.

• 2:26Neil deGrasse Tyson?

  Back in the day.

• 2:27Chuck Nice?

  Well, they were there.

• 2:30Neil deGrasse Tyson?

  And, but we gotta get right to it. We're a planet. We're presumably an exoplanet to aliens.

• 2:38Chuck Nice?

  Right.

• 2:38Neil deGrasse Tyson?

  Orbiting some other star.

• 2:39Speaker 02

  Right. Absolutely.

• 2:40Neil deGrasse Tyson?

  We have a moon. So what's this I hear that an exo-moon was recently discovered?

• 2:49Speaker 02

  Yeah, there was in the news recently, CD 35, a load of letters, B, just call it CD 35B for short.

• 2:57Neil deGrasse Tyson?

  And. CD, is this the name of the catalog it came from?

• 3:00Speaker 02

  That's the catalog. I've no, I've no idea what the CD is supposed to stand for, but that's the boilerplate name going around. And what's interesting about this object is it's a brown dwarf.

• 3:10Neil deGrasse Tyson?

  Okay.

• 3:11Speaker 02

  That orbits a M-dwarf star. And around that brown dwarf, they see evidence for a companion. And the question is, is that a moon or is that a planet?

• 3:23Neil deGrasse Tyson?

  So a brown dwarf, again, is a, not quite a star, a little too massive to be a planet.

• 3:28Speaker 02

  So this is an object which is in between the mass of, say, 13 Jupiter masses to about 80. And 80 is the point where you have enough mass for hydrogen fusion where it happens. So you can shine like a star. But below that, you can actually still have enough mass for deuterium fusion to occur. But there's hardly any deuterium. It's not, it's not a very efficient process.

• 3:48Chuck Nice?

  You're like a reality star.

• 3:51Speaker 02

  Yeah, you're on that C tier.

• 3:54Chuck Nice?

  Like, I was big on Bravo for a while.

• 3:57Speaker 02

  Right. So you know that people, the people who study brown dwarfs get kind of edgy about that, that kind of stuff because they're like, no, no, it's not a failed star. It's a overachieving planet, right? So it depends how you, how you frame it.

• 4:12Chuck Nice?

  I'm gonna tell you the truth. I'd rather be Jupiter.

• 4:16Chuck Nice?

  I'd rather be Jupiter.

• 4:17Speaker 02

  King of the planet.

• 4:19Chuck Nice?

  Just king of the planets instead of the overachieving, not quite a star.

• 4:26Neil deGrasse Tyson?

  You have a red-blooded star, a almost star, not quite a star, too much to be a planet thing.

• 4:32Chuck Nice?

  Right.

• 4:32Neil deGrasse Tyson?

  And that's not weird to have a brown dwarf orbiting a star. So this is the first time we found a, basically a triple system. An object orbiting an object orbiting the object where two of them are not stars.

• 4:44Speaker 02

  Well, not quite, because, because we have binary stars, which have.

• 4:48Neil deGrasse Tyson?

  No, I'm saying, this is what, two of them are not stars.

• 4:49Chuck Nice?

  It's a two of them are not stars.

• 4:51Speaker 02

  Yes. It sort of depends on how you think of the brown dwarf. Cause some might say the brown dwarf and the star is kind of a binary star system.

• 4:59Neil deGrasse Tyson?

  Yeah.

• 5:00Chuck Nice?

  Yeah, but you can't, you just eliminated that possibility by degrading it to a not-quite-star overachieving planet.

• 5:09Neil deGrasse Tyson?

  So did it make the news because we don't really know what to call it? It's not that it was some major astrophysical and bit of enlightenment? Is it just who ordered this kind of thing?

• 5:21Speaker 02

  I think it's a bit of both. I mean, first off, there is an object almost identical to this one that we discovered before. It's like HD 206, something, something or other. That's, that's a very similar configuration. They use a different method to find it and they're not as confident. So they say this is a candidate object around a brown dwarf around a star. The authors of this paper are much more confident. Like, this is, this is legit. This is definitely something that.

• 5:43Neil deGrasse Tyson?

  And so who's lead author on this?

• 5:45Speaker 02

  Kevin Hoy. So it's a Chilean group who love this, using the VLT to take observations. And they, they're able to measure the wobble, the Doppler wobble of this object. And that's where they get this evidence for. But yeah, if you go, if you turn to the I U definitions, they're actually pretty clear. And they say that this thing's a planet. Anything in orbit of a brown dwarf is a planet, according to those definitions. Now, we can argue about those definitions, but it's.

• 6:07Neil deGrasse Tyson?

  So it doesn't then say, suppose the brown dwarf is orbiting something else?

• 6:12Speaker 02

  Doesn't say anything about it. It says, no matter how, when it says, actually specifically, no matter how it formed, what it's doing, what, what is color it is, whatever it is. If it's between 13 to 80 Jupiter masses, it's a brown dwarf and anything in orbit of that, again, doesn't really matter, is always a planet.

• 6:26Neil deGrasse Tyson?

  Wait, but suppose I have a binary brown dwarf orbiting the main star? You can't call that a planet.

• 6:32Speaker 02

  No, then it's a binary brown dwarf. Yeah. Cause they actually do have a, it's a footnote of if it's more than, less than one over 25 mass ratio. Then it's, then it's a binary. So this object is one over 37 mass ratio.

• 6:44Neil deGrasse Tyson?

  So that's in moon category right there.

• 6:47Speaker 02

  Planet category. I'd say. There is no moon category in the I U definition. The I U says, there's no word moon or satellite anywhere in this document. So that's why it's an ambiguity here. Yeah, I think so.

• 6:59Neil deGrasse Tyson?

  Yeah. We should bring the Pluto haters back because they know how to.

• 7:03Chuck Nice?

  They know how to get things done. Yeah. Without a doubt. Yeah, you know.

• 7:08Neil deGrasse Tyson?

  Okay. So is it something to be excited about or is it just something to add to the catalog?

• 7:11Speaker 02

  I think it's definitely an exotic object. I look for exo-moons, as you know, and for me, the reason why I do it is because I want to understand how common is the Earth-moon system? How common are the moons around Jupiter? Like, how common is us? Like our backyard? You know, where do we come from? And this object, as cool as it is, doesn't really speak to anything familiar to that which we have in the solar system. So it's an exotic object.

• 7:33Neil deGrasse Tyson?

  That's the rub right there. I love it. It doesn't fit.

• 7:36Chuck Nice?

  The way you originally described it, it's very exotic. And that's, yeah, that's what makes it.

• 7:39Speaker 02

  Which is cool. I like a bit of exotic. But I also want to understand our story.

• 7:44Chuck Nice?

  Right. Yeah.

• 7:45Neil deGrasse Tyson?

  Right. How did this Chilean group discover this exo-moon?

• 7:48Speaker 02

  I think this brown dwarf was already known and they were able to separate the light from the brown dwarf and the star using a chronograph. And then they were able to measure the Doppler shifts of the light from that brown dwarf. So it's kind of similar to how we discovered the first exoplanet around 51 Pegasus B. That was just a star by itself and we saw the Doppler lines. Here it's harder because you've got two sources of light. So you have to do that separation.

• 8:12Neil deGrasse Tyson?

  Disentangle that.

• 8:13Speaker 02

  And then you can actually look for things around the brown dwarf.

• 8:15Neil deGrasse Tyson?

  Got it. So, but they had to know, to think, to do that in the first place?

• 8:19Speaker 02

  Yeah. Yeah. It's not easy work. Yeah.

• 8:22Neil deGrasse Tyson?

  So now you recently submitted for publication a paper that explores life on exoplanets. But that's quite the cottage industry. It's, you know, not a few months go by before another result. We found some chemistry in the atmosphere that means there's life on the surface, because you can't see the surface.

• 8:40Chuck Nice?

  Right.

• 8:40Neil deGrasse Tyson?

  It's too small, too distant, too dim, right? But the chemistry pops out. So what are you, how are you adding to that conversation?

• 8:47Speaker 02

  You know, I was just frustrated as someone interested in the search for alien life, that we keep seeing so many false stars. Right? So you've had, you go all the way back when I was a kid, I remember Bill Clinton stood on the White House lawn talking about the Allan Hills meteor.

• 8:58Neil deGrasse Tyson?

  Yes.

• 8:59Speaker 02

  As evidence for life. And of course that evaporated. We've had recently K to 18B, this evidence of dimethyl sulfide that everyone got excited about could be life. And again, it's been challenged and we had venusian phosphine. So we just seem to have like time and time again.

• 9:11Neil deGrasse Tyson?

  Dimethyl sulfide and it's also dimethyl disulfide, right? I think there were two.

• 9:15Speaker 02

  Well, the original claim is just DMS, but now they think there's that as well.

• 9:18Neil deGrasse Tyson?

  So on Earth.

• 9:19Chuck Nice?

  Right.

• 9:19Neil deGrasse Tyson?

  Phytoplankton.

• 9:21Chuck Nice?

  Okay.

• 9:21Neil deGrasse Tyson?

  The boys that do photosynthesis.

• 9:23Chuck Nice?

  The, the basis of everything here.

• 9:25Neil deGrasse Tyson?

  The basis of everything.

• 9:26Chuck Nice?

  Right.

• 9:27Neil deGrasse Tyson?

  They're the ones that give us the, these dimethyl sulfides.

• 9:30Chuck Nice?

  Yeah.

• 9:30Neil deGrasse Tyson?

  And so if you're gonna find that on another planet.

• 9:32Chuck Nice?

  It's possible.

• 9:33Neil deGrasse Tyson?

  So then that's, that's headline making.

• 9:36Chuck Nice?

  That's really cool.

• 9:37Neil deGrasse Tyson?

  So has that been retracted, that discovery?

• 9:39Speaker 02

  It's not been, it's not been retracted, but other authors have come up with other ways you could plausibly expect to have this in atmosphere without necessarily life being involved.

• 9:47Neil deGrasse Tyson?

  And you want, you want a strong result.

• 9:50Speaker 02

  Yeah. So this is kind of frustration I have that every, it seems like over and over again, someone sees something which looks like evidence of life. And then six months later, a theorist comes along and says, oh, by the way, I can think of a way of, of doing that without life involved.

• 10:04Neil deGrasse Tyson?

  But that doesn't make them right.

• 10:06Speaker 02

  Doesn't make them right.

• 10:07Neil deGrasse Tyson?

  All right. So have you found a way to make a, an airtight argument here?

• 10:12Speaker 02

  Well, I tried to point out two things. One is that as we plan these new observatories, like the Habitual Worlds Observatory, which will be the successor, hopefully to James Webb. Another multi-billion dollar telescope we're planning right now. We have to confront the reality of this epistemic problem that will be persistent, I think, for generations to come. And I suggest that one strategy could be kind of what we do in YouTube space of A B testing. So instead of just looking at a bunch of things and saying, how often do I detect dimethyl sulfide? How often do I detect a biosignature? Split your group into two categories and accept that there will be some number of confounders in these, in these two groups.

• 10:52Speaker 02

  But hopefully you can design these two groups such that the confounder rate is the same, but the life rate is somehow different. If you can do that, I'm not saying it's easy to do that, but if you can do that, you can solve this problem cleanly, statistically. And that's kind of the whole premise of my paper, that we need to think about the strategy, not just the technology, but really how we even approach this question.

• 11:13Neil deGrasse Tyson?

  Hmm. So is that similar to, because I remember back during the, was it the Challenger disaster?

• 11:21Neil deGrasse Tyson?

  Any disaster, they bring in all the evidence and then come up with a conclusion. What I always think they should do is they should bring in only half the evidence and see what you conclude.

• 11:31Chuck Nice?

  Oh, yeah, yeah.

• 11:31Neil deGrasse Tyson?

  And then you add.

• 11:33Chuck Nice?

  Add to it and see if the conclusion remains.

• 11:36Neil deGrasse Tyson?

  Yeah, if, if the last bit of evidence is what tips it, then it means most of the evidence wasn't really pointing to that result.

• 11:43Chuck Nice?

  Yeah.

• 11:44Neil deGrasse Tyson?

  And in science, you want the more evidence to align with what your thoughts were.

• 11:49Chuck Nice?

  Right.

• 11:49Neil deGrasse Tyson?

  Otherwise, go home.

• 11:50Chuck Nice?

  Right, yeah.

• 11:51Speaker 02

  Yeah, I mean, in statistics, we call that cross-validation.

• 11:54Neil deGrasse Tyson?

  Cross-validation, okay.

• 11:55Speaker 02

  When you block out some of the data, you do all your fits on the data you have, and then you, you uncover your hand and ask which one actually works. And that's like the, the true discriminatory test of which one is working.

• 12:07Neil deGrasse Tyson?

  So this will be a way to keep people on notice.

• 12:10Speaker 02

  I think it's an important, it's the question we all care about, right? I think it's where there's life out there, and I, I just wanna get an answer before I die, right? I hope that HWO succeeds.

• 12:18Neil deGrasse Tyson?

  This is a major motivation of science.

• 12:20Chuck Nice?

  Yeah, I wanna get it done before I die.

• 12:22Neil deGrasse Tyson?

  Before I die.

• 12:22Chuck Nice?

  Right, don't worry, when you die, Jesus will tell you all the answers, okay? Then you don't have to worry, he'll be right there.

• 12:40Neil deGrasse Tyson?

  Space fact, if Earth rotated once in 90 minutes rather than in 24 hours, the centrifugal force of that rotation would render everyone on the equator weightless.

• 12:57Neil deGrasse Tyson?

  If you liked that fact, you can find 4,999 more in Lost in Space. 5,000 facts to help navigate the universe. Latest collaboration between StarTalk and National Geographic Books. Lost in Space is now available for pre-order wherever books are sold.

• 13:34Neil deGrasse Tyson?

  This is a Cosmic Queries. You have a huge fan base out there among our followers, and so, Chuck, you got the, you got it lined up?

• 13:44Chuck Nice?

  I have them right here.

• 13:46Neil deGrasse Tyson?

  Okay, and you haven't seen these questions, right? They're coming right out of the blue for you.

• 13:50Chuck Nice?

  Cool, good for, yeah, that, that makes three of us.

• 13:55Neil deGrasse Tyson?

  Okay, and these are our Patreon supporters who have given us $5 a month.

• 13:59Chuck Nice?

  Right, which qualifies you to be able to submit your query. All right, here we go. This is Andora Klump, who says, Dear Dr. Kipling, Dr. Tyson, Lord Nice.

• 14:10Speaker 02

  Kipping.

• 14:10Chuck Nice?

  Uh, Kipping, sorry. Uh, dear, I said Kipling. Oh, I made you quite literary, didn't I?

• 14:20Chuck Nice?

  I say, oh, boy. Anyway, dear Dr. Kipping, Dr. Tyson, Lord Nice. LHS 1140B has a confirmed atmosphere 48 light years away. If microbial life lives there under ice or in its ocean, what would be the very first sign we would detect from this distance? Greeting from Rotterdam, the Netherlands. And so, if I remember from the news, 1140 is a rocky planet, right?

• 14:55Speaker 02

  Well, we're not sure, that's a good question. Uh, we're actually not sure.

• 14:58Chuck Nice?

  Oh, really?

• 14:59Speaker 02

  So, yeah, actually, it's probably almost certainly not rocky, to be honest with you.

• 15:01Chuck Nice?

  Really?

• 15:02Speaker 02

  Okay, it's about five and a half Earth masses.

• 15:05Chuck Nice?

  All right.

• 15:05Speaker 02

  But it's 1.7 Earth radii. So when you do the math, that gives you a density that is actually similar style of the Earth.

• 15:12Neil deGrasse Tyson?

  Sounds like it.

• 15:13Chuck Nice?

  Right, so that's why they, that's why all the news was rocky planet found.

• 15:17Speaker 02

  Right, so you might think that's rocky, but the problem with that is, is that that's, that's compressed density, right? There's 1.7 Earth radii squeezing all that self-gravity. So if you kind of relaxed it, it means that the stuff that it's made of must be lighter than rock. It can't just be pure rock.

• 15:32Neil deGrasse Tyson?

  It can't have squeezed in that way.

• 15:34Speaker 02

  Correct, so it's probably some rock and then something on top, like a big envelope of gas or maybe an ocean or something in between, like ice or something.

• 15:43Neil deGrasse Tyson?

  So something's confounding those blunt calculations and confusing how to interpret.

• 15:50Speaker 02

  I mean, it's, it's a challenge because we have nothing in the solar system to point at and say, oh, that's what it must be.

• 15:55Neil deGrasse Tyson?

  There's the problem.

• 15:56Chuck Nice?

  There you go.

• 15:57Neil deGrasse Tyson?

  Right, the solar system is not a thing.

• 15:59Speaker 02

  It's in between Earth and Neptune. And we just don't really know what those things are.

• 16:02Neil deGrasse Tyson?

  Does that nullify the inquiry here?

• 16:04Speaker 02

  No, it is, it's at the right distance from a star, potentially for liquid water, if it, if it is.

• 16:09Neil deGrasse Tyson?

  Goldilocks zone.

• 16:10Speaker 02

  If it has water, yeah, it's in the Goldilocks zone. And, um, it's, it's small, so it seems like it would be potentially possible that it could have had water delivery, it's not a gas giant.

• 16:21Chuck Nice?

  Uh huh.

• 16:21Speaker 02

  Um, so if it has life on it, which I think is possible, it's not an Earth-like planet, I wanna be clear about that, it's not an Earth-like planet, but it could still have life nevertheless. And then maybe we could look for things like phytoplankton, like this dimethyl sulfide signature that we talked about earlier. Um, we could look for oxygen, you could look for methane, you could look for some of these gases. But then it kind of comes back to that original question of like, well, then, how are you sure that if you see methane, that really is life? So that's just an unsolved question.

• 16:49Chuck Nice?

  So here's what I wanna know, all right, just has really nothing to do with this, just because you said something that triggered me.

• 16:55Speaker 02

  Yeah.

• 16:56Chuck Nice?

  All right, when Goldilocks zone, right?

• 16:59Speaker 02

  Yeah.

• 17:00Chuck Nice?

  The star that creates the Goldilocks zone, you said the right distance. Does that distance change on the size of the star and the age of the star? And do stars burn cooler when they get older, increasing or decreasing the Goldilocks zone?

• 17:19Speaker 02

  Yes, yes and no, is the short answer to those three questions, yeah.

• 17:22Neil deGrasse Tyson?

  There you go.

• 17:23Speaker 02

  Yeah, so, so.

• 17:25Chuck Nice?

  That was easy.

• 17:27Neil deGrasse Tyson?

  Yeah, I wasn't tracking it to be that efficient in my reply.

• 17:30Speaker 02

  Yeah, next one, no, yeah, all stars, and this is actually an M-dwarf, so it's a small star. Um, I'm not sure of its exact mass, but it's less than half the mass of the sun. So that's why it has this red dim light, that's why it's in the LHS catalog, because it's nearby and, but it's not, it's not a visible star. It's not a naked eye star, you can't see it with a naked eye, so you have to take telescopes to detect it. Um, but it is nearby, um, the star, because it's less luminous than the sun, means this Goldilocks zone is much closer. Um, and yeah, as it ages.

• 18:00Neil deGrasse Tyson?

  And importantly, for these cooler stars, cooler, there's thousands of degrees, the Goldilocks zone is not only closer, it's narrower.

• 18:07Chuck Nice?

  Ah, okay.

• 18:08Neil deGrasse Tyson?

  Okay, so the hotter stars get bigger Goldilocks zones.

• 18:11Chuck Nice?

  Right.

• 18:11Neil deGrasse Tyson?

  So these are, in the statistics of Goldilocks planets, this matters.

• 18:15Chuck Nice?

  Okay, yeah, of course, yeah.

• 18:16Speaker 02

  Yeah, and then just finish that point, as it ages, that the Goldilocks zone mostly move out usually for main sequence stars. So it should, as the sun is increasing luminosity, it was about 30% less luminous four billion years ago than it is today, I think that's roughly about right. So that means the Goldilocks zone is moving out.

• 18:31Chuck Nice?

  Right.

• 18:31Speaker 02

  We used to be on the outer edge of the Goldilocks zone, and now the Earth is on the inner edge, which is why we're so sensitive to CO2, right? If, if it wasn't, if we were two billion years ago, we could have probably polluted a lot more, not worried about it. But because we're on the inner edge of the habitable zone now, we have to kind of worry about this a bit more.

• 18:46Chuck Nice?

  Yeah, a lot more, yeah, wow.

• 18:49Neil deGrasse Tyson?

  Or go back four billion years.

• 18:53Chuck Nice?

  Yeah, let's go on, here we go. This is Alejandro Guardado, he says,

• 19:03Chuck Nice?

  he says, Hello, Dr. Tyson, Lord Nice, and Dr. Kipping. Alejandro here from Washington State. Hello, or should I say, hola?

• 19:18Neil deGrasse Tyson?

  That is not what's in there.

• 19:19Chuck Nice?

  I know it's not.

• 19:26Chuck Nice?

  Okay, he says this, let me stop messing around.

• 19:30Speaker 02

  I'm sorry.

• 19:32Neil deGrasse Tyson?

  I gotta agree, that's what Alejandro should sound like, yeah. If he don't sound like that, he should take some lessons.

• 19:39Chuck Nice?

  I just see him sitting around drinking an espresso with Antonio Banderas.

• 19:43Neil deGrasse Tyson?

  Yeah, exactly, that's who I'm around, yeah.

• 19:46Chuck Nice?

  All right, here we go, this is what he says. My question is, in our search for life in the universe, why does it matter if aliens are intelligent? Should the search for intelligent life be simplified to just life? Would this simplification lead to less fear in our society about aliens and lead to advances in the search? Thank you for always keeping me curious.

• 20:11Neil deGrasse Tyson?

  NASA, in the day, used to have interest in the search for life.

• 20:16Chuck Nice?

  Okay.

• 20:16Neil deGrasse Tyson?

  Which included the search for intelligent life.

• 20:18Chuck Nice?

  Okay.

• 20:19Neil deGrasse Tyson?

  And then it ended up in the sights of William Proxmire for the Golden Fleece Award, which was given to agencies who do research on public monies for things that he judges is a waste of money. Golden fleece, okay? And so NASA, in the search for intelligent life, he viewed that exercise as completely, uh, beyond the pale. And so NASA.

• 20:46Neil deGrasse Tyson?

  In response, separated the search for life, which is of interest to everyone, biologists and everybody, from the search for intelligent life. And in that separation, they forfeited the search for intelligent life, and that was picked up by SETI.

• 21:00Chuck Nice?

  Right.

• 21:00Neil deGrasse Tyson?

  Okay, so there's a whole SETI institute, which is privately supported.

• 21:04Chuck Nice?

  Yes.

• 21:04Neil deGrasse Tyson?

  And so, kinda in response to this, they are two separately funded activities. Now, if someone in your, on your exoplanet waves to you, you, you don't have any problem with that. But that's not what you're after. You're looking for any kind of life at all.

• 21:20Speaker 02

  I think, I mean, I would especially be interested in life that was technological. I try to avoid the word intelligent, because we may not even have intelligent life here.

• 21:27Neil deGrasse Tyson?

  Yeah.

• 21:30Speaker 02

  But technological life, I think, is something we could look for. And it's pretty interesting if that's out there. And it does answer a different question, because it's one thing to say, okay, a planet has some kind of life, microbial life. But what if in the evolutionary chain that gets from there to something like us, there is a, what we call a great filter, some point, which is a bottleneck, which makes it incredibly unlikely that the animals ever develop past a certain point or something. So if we discover technological life, then it would prove that, oh, there is no great filter. It's just a smooth track all the way. And it would make the so-called Fermi paradox even more puzzling.

• 22:05Neil deGrasse Tyson?

  So what you're suggesting is just one other example would show that however narrow that bottleneck is, it's not so narrow, it would have only produced one example of technology in the universe.

• 22:16Speaker 02

  Right.

• 22:17Neil deGrasse Tyson?

  So if you have another example.

• 22:19Speaker 02

  I think one independent example of either life or technology would be enough to say, like, hey, universe has done it twice, completely independently.

• 22:28Neil deGrasse Tyson?

  And life has been on Earth for three and a half billion years. For two and a half of those three and a half billion, it was just single-celled organisms. So if you're throwing a dart at planets with life, and if Earth is any measure of that, you're probably going to hit a planet with microorganisms.

• 22:44Chuck Nice?

  Right.

• 22:44Neil deGrasse Tyson?

  More.

• 22:45Chuck Nice?

  More likely to do that.

• 22:47Neil deGrasse Tyson?

  There's some of the dart statistics on this. But, okay. And would one sign of technology be smog?

• 22:57Speaker 02

  It could be. I mean, that'd be depressing, wouldn't it? That was, I think the advantage, the beauty of a techno-signature is that some of them, not all of them, not smog, could be unambiguous. But if you get, like in the film Contact, where Jodie Foster has the headphones on and gets the, the, the transmission, and you can unpack it, and there's this engineering plan of how to build a machine, there's no way that's random chance. Someone's engineered that. Whereas if we detect a, a gas, so that would be, that'd be slam dunk. There's definitely aliens. If you detect dimethyl sulfide in exoplanet atmosphere, people are going to argue about that for, for years and decades to come. So that's the advantage of techno-signatures. It can be cut.

• 23:40Neil deGrasse Tyson?

  They're not going to argue over engineering plans.

• 23:42Chuck Nice?

  Exactly. Like, if they send you a key of directions,

• 23:49Chuck Nice?

  it's a done deal.

• 23:50Neil deGrasse Tyson?

  How to put together your table.

• 23:52Chuck Nice?

  Right. And then at the end of the directions, it says, don't worry if there are pieces left over.

• 24:00Chuck Nice?

  Oh, wow, that's really cool. And I love that. Technical, yeah, technical life, that's the way to go. All right, here we go. Larry Chan says, I'm Larry Chan from NYC, and I'm a science fiction writer. Once humanity travels to other star systems, planets will most likely be named after the gods of ancient times. For example, Tyroa and Cataquill were Native American gods. After the list of gods reaches its limit, how would we name exoplanets? I suggest naming them after characters of classical literature. For example, Ahab, the Mad Hatter, Tom Sawyer, Alice Liddell, um, etc.

• 24:45Neil deGrasse Tyson?

  I love that. And there's no shortage of those, of those names.

• 24:48Chuck Nice?

  Right.

• 24:48Neil deGrasse Tyson?

  You know, we had a similar challenge when asteroids were discovered. How many are there? Well, there's at least 10, all right? And they were initially named, well, the first asteroids we thought were planets. So they're named after Roman gods, as are the other planets. And then we discovered there's some other category of object. But there was an urge to name them after feminized versions of people. So there's an asteroid, not called Mozart, but Mozartia.

• 25:20Chuck Nice?

  Okay.

• 25:22Neil deGrasse Tyson?

  So that was a little, because it was the feminine would be the diminutive variant of a planet name.

• 25:27Chuck Nice?

  Gotcha.

• 25:27Neil deGrasse Tyson?

  Okay, because they're asteroids, right? So, so then you quickly run out of names, although there's still a lot of names. I mean, there's a lot of names. People name after their pet. There's, there's, there's an asteroid, Santa. Okay, people love observing that on New Year's Eve.

• 25:41Chuck Nice?

  Right.

• 25:41Neil deGrasse Tyson?

  Okay, a friend of mine did that, and he showed me the data.

• 25:44Chuck Nice?

  Okay.

• 25:44Neil deGrasse Tyson?

  Just kind of.

• 25:45Chuck Nice?

  That's cool.

• 25:46Neil deGrasse Tyson?

  When you have nerd friends, that's the kind of stuff you do.

• 25:49Speaker 02

  Right. I kind of think we should just call them GPS coordinates, you know? Just like, you give me a number, and then I know exactly where.

• 25:55Chuck Nice?

  Where to go and find them.

• 25:56Speaker 02

  Because if you give me a name like, go to Aurelius or something, I'm like, well, I don't know anything about that star just from that name. I'd like to get some information about the star from the name.

• 26:06Neil deGrasse Tyson?

  As you may know, the moons of Uranus, that are all named for Shakespearean, fictional characters in Shakespearean literature.

• 26:12Chuck Nice?

  Okay.

• 26:12Neil deGrasse Tyson?

  Of which there are plenty enough to, to get you going. So another, they wanted to name, largely successfully initially, all of the asteroids whose orbit cross Earth's orbit, which puts us at risk, they're named after evil gods.

• 26:29Chuck Nice?

  That's awesome.

• 26:30Neil deGrasse Tyson?

  Yes.

• 26:30Chuck Nice?

  Now that makes sense.

• 26:31Neil deGrasse Tyson?

  Yeah, so one of them is Apophis.

• 26:33Chuck Nice?

  Right.

• 26:34Neil deGrasse Tyson?

  The Egyptian god of death and darkness. Yeah. And there're plenty of, you know, in, in the polyseistic realms, there's no shortage of these. Well, there is a shortage, because there's hundreds of thousands of asteroids that'll do this. So that's the problem.

• 26:49Speaker 02

  But you go to literature, you got Sauron. That's what I'd be doing.

• 26:55Chuck Nice?

  Yeah. I love that. Well, hey, hey, there you go.

• 26:59Neil deGrasse Tyson?

  Yeah, but I think David is right. At some point, the coordinate on the sky is uniquely identifies it.

• 27:05Chuck Nice?

  Right.

• 27:05Neil deGrasse Tyson?

  And you know what we, we can do? Because, were you an amateur astronomer at all?

• 27:09Speaker 02

  As a kid, not, not at a high level.

• 27:12Neil deGrasse Tyson?

  Yeah, yeah. That was a pretty high level amateur astronomer. So we, um, there are a lot of objects discovered by an amateur, would later be, get a catalog designation. But then you would carry both names.

• 27:26Chuck Nice?

  Right. I was gonna say, you have the coordinate as the name, and then in parentheses underneath.

• 27:31Neil deGrasse Tyson?

  Or in quotes. There's Tabby Star.

• 27:34Chuck Nice?

  Yeah.

• 27:34Neil deGrasse Tyson?

  There's Barnard Star.

• 27:35Chuck Nice?

  Right.

• 27:36Neil deGrasse Tyson?

  Uh, Barnard Star is another one of these stars that's nearby. And Barnard first studied it, but it's got a catalog name. So I think that's how you do it. If there's a reason to have a name because of its properties or because of who discovered it, you do it. But you still, you still need the unambiguous identifier.

• 27:51Chuck Nice?

  Okay.

• 27:52Neil deGrasse Tyson?

  Yeah.

• 27:52Chuck Nice?

  All right.

• 27:52Neil deGrasse Tyson?

  All right.

• 27:53Chuck Nice?

  Hey, well, thanks a lot there, Larry. That was a good question. Okay, let's go to Mary Rose. Mary Rose says, hello to all at StarTalk. This question is coming to you from the tiny island of Malta in the Mediterranean.

• 28:08Neil deGrasse Tyson?

  I want to be there.

• 28:09Chuck Nice?

  Yes.

• 28:09Neil deGrasse Tyson?

  Invite us. What's your name again?

• 28:11Chuck Nice?

  Um, Mary Rose.

• 28:12Neil deGrasse Tyson?

  Mary, invite us all.

• 28:14Chuck Nice?

  Yes, we're, we're, we'll, we'll be right there. Hope you got room for a sleepover. Okay, she says, David, what has been the most surprising find for you so far in the study of exoplanets? Thank you, Mary Rose.

• 28:28Neil deGrasse Tyson?

  I love that.

• 28:29Speaker 02

  Yeah, that's a great question. There are many things we've discovered which blew our minds. I think the, what we kind of expected, I mean, this is a little bit for my time, is that we'd find other solar systems which looked like our solar system.

• 28:42Chuck Nice?

  Right.

• 28:42Speaker 02

  This is the template, everything would look the same.

• 28:44Chuck Nice?

  Of course.

• 28:45Speaker 02

  And I think the greatest.

• 28:46Chuck Nice?

  Oh, the hubris.

• 28:46Speaker 02

  Yeah. We, we, we are the, the default. But it turns out we're actually kind of weird, and most solar systems look very different. So I think, and it's a very, like, kind of vague answer, but to give some examples, mini Neptunes, which we talked about with this LHS 1140, that's the most common type of planet in the universe.

• 29:05Chuck Nice?

  What?

• 29:06Speaker 02

  And we do not have one.

• 29:07Neil deGrasse Tyson?

  And we don't have one.

• 29:08Chuck Nice?

  We don't have one of those.

• 29:10Neil deGrasse Tyson?

  That ain't right. Yeah.

• 29:11Speaker 02

  That's weird.

• 29:11Neil deGrasse Tyson?

  That ain't right.

• 29:12Chuck Nice?

  That's kind of strange.

• 29:13Neil deGrasse Tyson?

  Well, how mini is a mini Neptune?

• 29:15Speaker 02

  It's in between about.

• 29:16Neil deGrasse Tyson?

  What fraction of Neptune's mass would that be?

• 29:18Speaker 02

  Uh, well, it's in between about two and four times the size of the Earth. So that's about, um, half the size of Neptune.

• 29:24Neil deGrasse Tyson?

  So, so Super-Earth?

• 29:25Speaker 02

  Yeah.

• 29:26Chuck Nice?

  A Super-Earth, yeah.

• 29:27Neil deGrasse Tyson?

  A Super-Earth, is that the same as a mini Neptune?

• 29:28Speaker 02

  We don't know. The other thing, because people argue about the name. Sometimes someone will say, you can't call it Super-Earth, we don't know it's rocky, you shouldn't call it mini Neptune.

• 29:35Neil deGrasse Tyson?

  I invite you to show for you to say that you don't know. You're, you're the expert here.

• 29:38Speaker 02

  We, we don't know.

• 29:40Neil deGrasse Tyson?

  That's how you know he's good.

• 29:41Chuck Nice?

  That's, that's right. That's it. That's it. Exactly.

• 29:43Neil deGrasse Tyson?

  Okay.

• 29:44Speaker 02

  But I think that, that diversity is, is surprising. There are circumbinary planets, like a Tatooine, like you had in Star Wars. Like George Lucas imagined that, and everyone just thought he was crazy. But we now know that that's a very common.

• 29:57Chuck Nice?

  Do you think he really knew, or did he just think it was cool?

• 29:59Neil deGrasse Tyson?

  No, no, no, no. But I do, it's the only science in.

• 30:05Chuck Nice?

  All of Star Wars.

• 30:07Speaker 02

  That's as good as it gets.

• 30:08Chuck Nice?

  Oh, my God.

• 30:08Speaker 02

  Downhill.

• 30:10Neil deGrasse Tyson?

  It is downhill.

• 30:12Chuck Nice?

  Oh, that's just awful.

• 30:13Neil deGrasse Tyson?

  Totally downhill from there. Um, that only worked because of the distance to the planet relative to the distance between the stars.

• 30:25Chuck Nice?

  Mm-hmm.

• 30:26Neil deGrasse Tyson?

  So that the planet sees two stars, that's the double sunset. The famous scene, the double sunset. Those have to be so close together that the planet thinks they're one source of gravity. Because if they were more separated and the planet is trying to figure out

• 30:42Chuck Nice?

  Where to go.

• 30:43Neil deGrasse Tyson?

  How to orbit. You get a chaotic trajectory.

• 30:46Chuck Nice?

  That's the three body thing, right?

• 30:47Neil deGrasse Tyson?

  It's a three body problem.

• 30:48Chuck Nice?

  It's a three body problem.

• 30:49Neil deGrasse Tyson?

  You lose the stability, either falls into one of the planets or escapes. So that one was correctly shown with the two stars setting together. And we can judge what that distance.

• 30:59Chuck Nice?

  Yeah.

• 31:00Neil deGrasse Tyson?

  That planet was. So you can create stable orbits that way. So that's the only way that works. So that's good science.

• 31:04Speaker 02

  And just add, we call that a P type orbit.

• 31:07Chuck Nice?

  A P type.

• 31:07Speaker 02

  Because you have a binary star where they're close together, like Tatooine, that goes around the two close together on the outside. That's a P type orbit, planet type. Or you can have the binary stars widely separated and the planet goes around.

• 31:18Neil deGrasse Tyson?

  Oh, that's also a stable orbit.

• 31:20Speaker 02

  That's an S type.

• 31:21Neil deGrasse Tyson?

  That was the S for?

• 31:22Speaker 02

  Satellite.

• 31:23Neil deGrasse Tyson?

  Oh, okay. Yeah.

• 31:24Chuck Nice?

  That's cool.

• 31:25Neil deGrasse Tyson?

  There you go.

• 31:25Chuck Nice?

  Very cool.

• 31:26Neil deGrasse Tyson?

  But then you don't get two sunsets.

• 31:27Chuck Nice?

  No.

• 31:27Neil deGrasse Tyson?

  Yeah, yeah, yeah.

• 31:28Speaker 02

  That was cool.

• 31:28Neil deGrasse Tyson?

  Okay.

• 31:29Chuck Nice?

  So here's what I want to know. I read that one of the most common things that we never consider with planets are rogue planets that in the formation of solar systems, so many planets are flung out of the solar system. So stable orbits can be achieved by the rest of the planets, right?

• 31:46Speaker 02

  They just got out of dodge.

• 31:47Chuck Nice?

  Just get out of there. Yeah. So how common would it be if we were able to see them? Would we just see planets wandering around like they lost from the home?

• 32:00Neil deGrasse Tyson?

  Yeah.

• 32:01Chuck Nice?

  Homeless.

• 32:01Neil deGrasse Tyson?

  They're homeless and then, then they became rogue planets.

• 32:04Chuck Nice?

  Oh, well, that sounds a lot more badass.

• 32:06Neil deGrasse Tyson?

  It's a little bit more badass.

• 32:07Chuck Nice?

  Yeah. I don't need none of y'all.

• 32:10Neil deGrasse Tyson?

  So David, my, the numbers I remember are that our solar system might've started with as many as 30 planets.

• 32:15Chuck Nice?

  Oh.

• 32:16Neil deGrasse Tyson?

  Coming down to the eight that we now have.

• 32:18Chuck Nice?

  Yeah.

• 32:18Neil deGrasse Tyson?

  So that tells us that maybe there are more rogue planets than there are planets with homes.

• 32:24Speaker 02

  Right, yeah, there's a, this is a really hot area in astrophysics right now, rogue planets. So you're, you're, you could get a, you know, a PhD right now doing this. It's a hot topic.

• 32:32Chuck Nice?

  Right on.

• 32:33Speaker 02

  Um, but you're right, the, it's thought the solar system had more planets. Some of them merged together. It's, it's really thought there was a fifth giant planet. There's a lot of evidence for that. It's actually really difficult to keep Neptune stable unless there was another Neptune like planet in the solar system in the past. So that's, it's not canonical, but it's widely accepted that it's likely true there was a fifth giant planet in the solar system in the past that got ejected out into space. And that's how you keep the outer solar system stable. So there should be a ton of those. And the Roman Space Telescope, which is coming up, is gonna be.

• 33:05Neil deGrasse Tyson?

  Nancy Grace Roman.

• 33:06Speaker 02

  Yeah.

• 33:06Neil deGrasse Tyson?

  Telescope.

• 33:06Speaker 02

  It's gonna be the perfect machine using micro lensing to detect a whole host of those. So we're expecting thousands of those to be found.

• 33:14Chuck Nice?

  Wow.

• 33:15Neil deGrasse Tyson?

  So this is where you have a star in the background. Ideally, it's a dense star field, like the center of the galaxy.

• 33:19Chuck Nice?

  Of course.

• 33:19Neil deGrasse Tyson?

  And you just watch for any starlight that, that increase. No, no.

• 33:24Chuck Nice?

  That it, oh.

• 33:25Neil deGrasse Tyson?

  Gets brighter.

• 33:26Chuck Nice?

  Gets.

• 33:27Neil deGrasse Tyson?

  It's not in a eclipse, okay?

• 33:28Chuck Nice?

  Oh.

• 33:29Neil deGrasse Tyson?

  Gets brighter. Why? Because the light going on either side of the planet, you can't see that the rogue planet, of course, because it's, nothing's illuminating it. It's in the middle of fricking nowhere.

• 33:38Chuck Nice?

  Right.

• 33:38Neil deGrasse Tyson?

  And there's a planet behind it, pathways of that star's life going around the planet, come back and join.

• 33:45Chuck Nice?

  Uh huh.

• 33:45Neil deGrasse Tyson?

  Magnifying the brightness of the star itself. Because a sideline would've gone and missed you.

• 33:51Chuck Nice?

  Right.

• 33:51Neil deGrasse Tyson?

  This light line would've missed you.

• 33:52Chuck Nice?

  Right.

• 33:53Neil deGrasse Tyson?

  It got bent into your view, adding to the brightness of the object.

• 33:56Chuck Nice?

  So it's gravitational lensing for rogue planets.

• 33:59Neil deGrasse Tyson?

  But it's a, it's only a tiny amount and just, we call it micro lensing.

• 34:02Chuck Nice?

  Yes, yeah, yeah. There's enough of a variation in the travel of the light for you to determine that?

• 34:09Speaker 02

  That, I mean, in terms of the magnification.

• 34:11Chuck Nice?

  In magnification, yeah.

• 34:12Speaker 02

  Uh, it's very small, but Roman's a very precise telescope.

• 34:15Chuck Nice?

  Holy crap.

• 34:15Speaker 02

  The real trick is that these are very rare events. So you'd have to observe millions and millions, even billions of stars simultaneously to have a chance of detecting one per day or so, right? And that's kind of the rate they want to get to.

• 34:27Chuck Nice?

  One per day, yeah.

• 34:28Speaker 02

  That's the power of Roman. It's, I mean, you probably know the numbers better than I do, but the field of view is like 10 times Hubble or something, or 20 times Hubble.

• 34:34Neil deGrasse Tyson?

  Wow. Yeah. That, that can boost your statistics.

• 34:36Chuck Nice?

  Yeah. Well, if the star gets brighter and dimmer, how do we know it's not the star doing that?

• 34:40Neil deGrasse Tyson?

  Because usually the star repeats that, whereas a micro lensing event is singular in time, plus it has an exact profile.

• 34:48Chuck Nice?

  Oh, it would be singular because the planet is on the move.

• 34:51Neil deGrasse Tyson?

  Planet's on the move.

• 34:51Chuck Nice?

  It's on the move. Oh, crap.

• 34:54Neil deGrasse Tyson?

  And the profile of the brightness and the dimming is, you know that in advance because of Einstein's general relativity. So let me ask you, David.

• 35:02Chuck Nice?

  That's wild.

• 35:03Neil deGrasse Tyson?

  David, Earth retains some of its heat of formation.

• 35:07Chuck Nice?

  Yeah.

• 35:08Neil deGrasse Tyson?

  And it's got heat from radioactive decay.

• 35:11Chuck Nice?

  Yeah.

• 35:11Neil deGrasse Tyson?

  Within the crust. If Earth left the solar system, there would still be a source of energy within it. Some life would not care that we no longer have the sun to sustain it. How many of these rogue planets still have energy within them? And therefore might still have life, making no reference to the sun, because life in the bottom of the ocean never seen the sun ever.

• 35:35Chuck Nice?

  Yeah.

• 35:35Neil deGrasse Tyson?

  Anyway, they're all blind.

• 35:36Speaker 02

  It's possible. I mean, people have speculated about that recently. Um, if you have moons, it's even better, right? Because moons can have tidal heating. Think about Io.

• 35:44Chuck Nice?

  Right.

• 35:45Speaker 02

  Io is a volcanic world. Lots of energy there. Europa too, probably has a liquid ocean.

• 35:50Chuck Nice?

  Tidal heating, you mean like a subtle stretching and contracting of the.

• 35:54Speaker 02

  Yes, as, as multiple moons interact with each other, it causes sometimes the moons to plunge a little bit deeper into Jupiter's gravitational field, sometimes a little bit further out. And so it's like a squash ball. It kind of gets stretched and squeezed, like a piece of dough. So the, uh, that's probably what happened to these moons. And so you could have for billions of years, life just thriving in between the stars.

• 36:17Chuck Nice?

  That is dope.

• 36:18Neil deGrasse Tyson?

  Yes, totally dope.

• 36:18Chuck Nice?

  That is unbelievable, man. Well, it's totally believable. That's what makes it dope. Wow.

• 36:22Neil deGrasse Tyson?

  Yeah. And in fact, look at the bias thrust upon us by biologists.

• 36:26Chuck Nice?

  Right.

• 36:27Neil deGrasse Tyson?

  Saying the sun is the source of all life in the world. It's, it's the source of most life.

• 36:32Chuck Nice?

  Right.

• 36:32Neil deGrasse Tyson?

  But there's life doing the backstroke at the bottom of the ocean.

• 36:35Chuck Nice?

  That never, never gets a chance to encounter.

• 36:37Neil deGrasse Tyson?

  Geothermal energy.

• 36:38Chuck Nice?

  Right.

• 36:38Neil deGrasse Tyson?

  And so it's not that life needs the sun, it's that life needs energy. And if you find another way to get the energy, that's why we're looking for life on Europa.

• 36:44Chuck Nice?

  Yeah.

• 36:45Neil deGrasse Tyson?

  Uh, another tidally heated.

• 36:47Chuck Nice?

  Right.

• 36:48Neil deGrasse Tyson?

  Moon of Jupiter.

• 36:50Chuck Nice?

  Right.

• 36:50Neil deGrasse Tyson?

  Yeah.

• 36:51Chuck Nice?

  Interesting.

• 36:51Neil deGrasse Tyson?

  Okay.

• 36:52Chuck Nice?

  Wow, that's so cool, man.

• 36:53Neil deGrasse Tyson?

  But so, so what's the difference between Europa and Io in their tidal heating?

• 36:58Speaker 02

  In terms of the amount of energy?

• 36:59Neil deGrasse Tyson?

  Yeah.

• 37:00Speaker 02

  Well, Io is on the inside, as close as Jupiter, so it gets the real brunt of it.

• 37:03Neil deGrasse Tyson?

  There you go.

• 37:04Speaker 02

  Um, Europa's, I think, number two, right? So it, it still gets heated, but not as much as Io.

• 37:08Chuck Nice?

  Okay.

• 37:09Neil deGrasse Tyson?

  But Io was so significant that there's volcanoes on it.

• 37:12Speaker 02

  Yes, yeah.

• 37:12Neil deGrasse Tyson?

  Right. Yeah, it's liquefied the rocks.

• 37:14Speaker 02

  Oh, you can see it coming out into space, from Io, it's crazy.

• 37:17Neil deGrasse Tyson?

  Yeah, yeah, yeah.

• 37:28Speaker 03

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

• 37:45Chuck Nice?

  All right, this is Peter Jacobs and Peter Jacobs says, good eye to David, Neil, and the, uh, applaudable, laudable, audible, oh my lordy, lordy, Lord nice.

• 37:55Neil deGrasse Tyson?

  What?

• 37:56Chuck Nice?

  Yeah. Peter Jacobs here from Mululaba in sunny Queensland, Australia.

• 38:04Neil deGrasse Tyson?

  Okay.

• 38:04Chuck Nice?

  I'd like to get me some dimmies.

• 38:06Neil deGrasse Tyson?

  Oh, okay.

• 38:07Chuck Nice?

  All right. He says, thinking of the Fermi.

• 38:11Neil deGrasse Tyson?

  That's quite the intro to this. Did, did you make that up?

• 38:14Chuck Nice?

  No, this is written.

• 38:15Neil deGrasse Tyson?

  I don't know sometimes.

• 38:16Chuck Nice?

  I was just doing a terrible Australian accent. That's all I had to say.

• 38:19Neil deGrasse Tyson?

  Sometimes I don't know what it is.

• 38:23Neil deGrasse Tyson?

  Okay, go on.

• 38:23Chuck Nice?

  Okay. He says, thinking of the Fermi paradox, how close can we get to Sag A before ambient radiation from surrounding stars would make life impossible? And would pulsars, quasars and colliding black holes sterilize their galaxies? Oh, wow.

• 38:42Neil deGrasse Tyson?

  Wow.

• 38:43Chuck Nice?

  So the amount of radiation coming out of a pulsar or a collision.

• 38:48Neil deGrasse Tyson?

  Sagittarius A is the supermassive black hole in the center of the galaxy.

• 38:51Chuck Nice?

  Right.

• 38:51Neil deGrasse Tyson?

  And it's, it is, it is a rockin', rockin', sockin' place.

• 38:56Chuck Nice?

  Yeah.

• 38:56Neil deGrasse Tyson?

  And there, and other galaxies, it's even more severe than ours in terms of just the, the flux of high energy radiation.

• 39:02Chuck Nice?

  So.

• 39:03Neil deGrasse Tyson?

  So do you guys think about?

• 39:04Chuck Nice?

  That's wild, yeah.

• 39:05Neil deGrasse Tyson?

  Let's, let's soften this just a little bit.

• 39:07Chuck Nice?

  Okay.

• 39:07Neil deGrasse Tyson?

  Some stars give off a lot of UV, but like the, the, the.

• 39:11Chuck Nice?

  Oh, that's a good point.

• 39:12Neil deGrasse Tyson?

  The bluer stars.

• 39:13Chuck Nice?

  Right.

• 39:13Neil deGrasse Tyson?

  And UV is hostile to life.

• 39:15Chuck Nice?

  Everything.

• 39:15Neil deGrasse Tyson?

  So are you thinking about life on planets that orbit, uh, high mass, high temperature stars?

• 39:21Speaker 02

  Yeah, so I think, but it's a great question. And I think it's, it touched on an idea called the galactic habitable zone. So you can have a habitable zone around a star, but there may also be a habitable zone in our own galaxy, right?

• 39:33Neil deGrasse Tyson?

  And that would be a radiation problem for you if you're a little too close to the center.

• 39:37Speaker 02

  Not necessarily just radiation. It could be, um, metallicity, the metallicity of the galaxy changes.

• 39:43Chuck Nice?

  I don't know what metallicity is.

• 39:44Speaker 02

  So how, the.

• 39:45Neil deGrasse Tyson?

  It's jargon. Now he's now got to explain the jargon.

• 39:48Speaker 02

  Okay, so it's the, it's the heavy atomic elements, especially in astronomy, anything heavier than hydrogen, helium, the two things came out of the big bang.

• 39:54Chuck Nice?

  Right.

• 39:54Speaker 02

  Are a metal. And that's what you're, you're made out of primarily.

• 39:57Neil deGrasse Tyson?

  Chemists hate that.

• 39:58Chuck Nice?

  Yeah.

• 39:58Neil deGrasse Tyson?

  Because you call everything metals. Is it metal rich?

• 40:01Chuck Nice?

  Yeah.

• 40:01Neil deGrasse Tyson?

  If it has lithium, you know, uh, uh, carbon, it's considered a metal.

• 40:05Chuck Nice?

  Right.

• 40:06Neil deGrasse Tyson?

  And chemists hate that.

• 40:06Chuck Nice?

  So the whole universe is one big headbanger's ball. A metal man.

• 40:13Neil deGrasse Tyson?

  Okay, so you have the radiation in the center.

• 40:15Chuck Nice?

  Yeah.

• 40:15Neil deGrasse Tyson?

  And you need enough heavy elements.

• 40:18Speaker 02

  To make planets.

• 40:19Neil deGrasse Tyson?

  To make planets and, and people.

• 40:21Speaker 02

  Yeah. And you need, I mean, in, when you really look at around Sagittarius A star, you've seen some of these animations, they've, they've reconstructed the star paths. They're on top of each other. So planets wouldn't even be stable.

• 40:32Neil deGrasse Tyson?

  Yeah.

• 40:33Speaker 02

  Right? So these stars.

• 40:34Neil deGrasse Tyson?

  They're like these loop orbits and it's, it's what won the Nobel Prize.

• 40:37Chuck Nice?

  Right.

• 40:38Neil deGrasse Tyson?

  Uh, that the observations confirming the black hole in the center of the galaxy by tracking these orbits.

• 40:43Chuck Nice?

  Okay.

• 40:44Neil deGrasse Tyson?

  Shared the Nobel Prize with our guy, our physics guy, Roger Penrose, who showed early the mathematical rigor of why you would get a black hole in the first place.

• 40:54Chuck Nice?

  Interesting.

• 40:55Neil deGrasse Tyson?

  The perfect combination of theory and observation.

• 40:57Chuck Nice?

  Wonderful.

• 40:57Neil deGrasse Tyson?

  There. So there's other parameters, so.

• 40:59Speaker 02

  Yeah. So you've got to form a planet, you've, you've got to.

• 41:02Neil deGrasse Tyson?

  With the right ingredients.

• 41:03Speaker 02

  Yep, you've got to have a stable orbit.

• 41:05Neil deGrasse Tyson?

  Stable.

• 41:06Speaker 02

  And then the radiation environment has to not sterilize you.

• 41:09Neil deGrasse Tyson?

  Right.

• 41:09Speaker 02

  And obviously if there's lots of stars around and say one in a thousand stars go supernova, then the chances are, if you're in a busy neighborhood, if you're in Manhattan, you're likely to have one of these guys go off at you.

• 41:20Neil deGrasse Tyson?

  So you don't even want to be around another star that blows up.

• 41:22Chuck Nice?

  Right.

• 41:23Neil deGrasse Tyson?

  Yeah, okay, yeah, cool.

• 41:24Chuck Nice?

  That's, that's funny because I read that one of the reasons for life here, where is the fact that we're in a suburb of the Milky Way galaxy.

• 41:34Speaker 02

  Yeah. Yeah, I think that's true. And we also don't, you know, our orbit is more or less circular. It doesn't like have an eccentric, but we plunge towards the center and come back out. So we're in a, we're in a nice neighborhood.

• 41:46Neil deGrasse Tyson?

  We're about two thirds of the way out.

• 41:50Speaker 02

  We don't have to commute into the city.

• 41:52Neil deGrasse Tyson?

  We've been redlined from early on.

• 41:58Chuck Nice?

  We're in the Carol Gardens of the Milky Way.

• 42:04Neil deGrasse Tyson?

  So we're about two thirds of the way out and I hadn't appreciated, yes, we're in a basically circular orbit. So we're not, we don't risk changing neighborhoods and, and surviving the consequences of it. Yeah. And one full orbit is a couple of hundred million years. So that's at our distance.

• 42:23Chuck Nice?

  Plenty of time.

• 42:24Neil deGrasse Tyson?

  Well, no, but that evolutionarily, that's, it works.

• 42:28Chuck Nice?

  That's pretty stable. Yeah. Yeah. Gotcha. All right. Wow. That's all cool stuff, man. Damn. Yeah. You do some cool stuff, man.

• 42:36Neil deGrasse Tyson?

  I think it's called the cool laboratory.

• 42:38Chuck Nice?

  Oh, that's right.

• 42:42Chuck Nice?

  There we go. Uh, this is Mike Landers. He says, hi, Dr. Ty Singh, Dr. Kipping, Lord Nice. This question comes from San Francisco. If we eventually detect an unambiguous techno signature or biosignature, do you think it might belong to a civilization that is already extinct by the time the signal reaches us, making our first contact essentially an archaeological dig?

• 43:04Neil deGrasse Tyson?

  Oh, I like that. So how far away are your stars?

• 43:07Speaker 02

  For SETI, for techno signatures, we, we can search across huge spans of the galaxy. I mean, you can span tens of thousands, even a hundred thousand light years in some extreme cases.

• 43:17Neil deGrasse Tyson?

  So they could easily have gone extinct, but your stars, your cool stars, they're not that far away.

• 43:23Speaker 02

  Biosignatures, things that James Webb are observing and trying to get signs of atmospheres, those are nearby. So those are tens, 20 light years, 30 light years away.

• 43:33Neil deGrasse Tyson?

  Okay. So if presumably civilization takes so much longer than 30 years to establish, that a 30 year delay is not some major.

• 43:42Chuck Nice?

  It's not prohibitive of you.

• 43:43Speaker 02

  Right. But the tennis signature doesn't have to be like an active beacon. It could be, um, one of the coolest ideas I've ever heard for a tennis signature is the idea of putting shades in space that orbit the sun and they would be artificial transits. So like put a giant triangle in space, like a sheet of aluminium. And as it transits the sun, it would create a very strange eclipse to alien observers. They'd be like, hold on, someone's put a triangle around that thing. That doesn't occur in nature.

• 44:09Chuck Nice?

  That's a space Dorito.

• 44:11Speaker 02

  Exactly. You'd be like, that's weird. That shouldn't be there. And that thing would be stable for millions, billions of years, long after we're gone. So we could leave a relic that would betray our presence. And you, you could even have interesting signals.

• 44:26Neil deGrasse Tyson?

  These are the Easter Island heads.

• 44:28Chuck Nice?

  Oh.

• 44:29Neil deGrasse Tyson?

  They were, the civilization left them there.

• 44:31Chuck Nice?

  Right.

• 44:32Neil deGrasse Tyson?

  And it's been argued that you come upon the island and they're looking at you still.

• 44:39Neil deGrasse Tyson?

  Yeah. If you leave some, some purposeful relic.

• 44:42Speaker 02

  A monument. I mean, the pyramids are a communication from another civilization to us through time. And we too have the opportunity with a time capsule of some kind to communicate to future civilizations, perhaps even future, I think the most likely contact.

• 45:00Neil deGrasse Tyson?

  He's not saying that pyramids were left by aliens.

• 45:02Speaker 02

  No.

• 45:03Neil deGrasse Tyson?

  Just, I just wanna.

• 45:03Speaker 02

  A human civilization.

• 45:05Neil deGrasse Tyson?

  Left by basically an extinct human civilization, ancient Egypt.

• 45:10Speaker 02

  Yeah, yeah.

• 45:10Neil deGrasse Tyson?

  Is, is no longer with us. There's like, they're descendants, but they're not building pyramids anymore.

• 45:15Speaker 02

  My, my provocative claim is that the most likely alien contact we will ever have, not really a contact, but a way of them knowing that we're here, is that we could leave something like the voyage, like the golden record, like the pioneer plaques, we could leave something like that, perhaps on the moon. And maybe in 500 million years from now, another advanced civilization will emerge and discover that on the earth. So it will be a non-human intelligence, not alien, but still non-human that evolves after us. And they pick this up and they realize, oh, we are not the only ones to ever develop.

• 45:48Neil deGrasse Tyson?

  But that would imply that there isn't a continual awareness of a previous civilization. Are you referring to an apocalyptic earth? We all die, civilization disappears, and then some other intelligence evolves later and discovers that.

• 46:01Speaker 02

  Doesn't have to be an apocalypse, but yeah, we, we fade out maybe just gradually. There's evolution, you know, species very rarely last longer than a million years. So eventually we change into something else and some other future civilization emerges.

• 46:14Neil deGrasse Tyson?

  I think it's mammal species around a million. Other species, I'm not sure.

• 46:18Speaker 02

  Yeah.

• 46:18Neil deGrasse Tyson?

  Unless it's all species.

• 46:19Speaker 02

  It's rare. There are some, but it's unusual for a species to last that long. So I.

• 46:23Chuck Nice?

  Believe me, we're not gonna.

• 46:25Neil deGrasse Tyson?

  We're not gonna do it right now.

• 46:26Chuck Nice?

  We don't even have to worry about whether or not we're gonna make it to a million years. Come on.

• 46:33Speaker 02

  So I, I think relics are a cool way. There's a whole thing called artifact SETI, which is the, the question askers should definitely look into. Yeah.

• 46:41Chuck Nice?

  All right. Here we go. This is, um, here we go. This is Aiden Rodriguez, who says, hello, Dr. Tyson, Lord Nice, and Dr. Kipping, uh, greetings from Panama City, Panama, the country that gave the world the Panama Canal. I've been a fan of you guys for many years and I'm a Patreon supporter now. My question is, could life exist on a planet with much stronger gravity than Earth? Say two or three times stronger. If so, it also, would it evolve in an atmosphere with much higher pressure than ours? Thanks so much. Keep up the amazing work. Um, yeah, that's pretty wild.

• 47:16Speaker 02

  That's a great question. I think the immediate challenge is how would you engineer a planet to have two or three times Earth gravity? Because as you, as you increase the gravity, a planet will naturally accumulate gas.

• 47:28Chuck Nice?

  Right.

• 47:28Speaker 02

  Around it as it's forming. So you're going to turn to a gas giant, basically.

• 47:31Neil deGrasse Tyson?

  So even only three times the gravity?

• 47:34Speaker 02

  I, I think probably three times. Yeah. I don't think there's any super Earths that are more than like 1.7, 1.8.

• 47:40Neil deGrasse Tyson?

  So super Earths are just slightly more muscular, but not multiples. I did not know that.

• 47:45Speaker 02

  They don't get that extreme.

• 47:47Chuck Nice?

  Oh. Yeah. And at that point, all the fluid that has, uh, accreted puts a pressure on the surface. And so the pressure would be super huge too.

• 47:56Speaker 02

  Right. And what, yeah. So the pressure would be high. I mean, it is cool. You could probably have 1.5 times Earth gravity, no problem. And what's interesting, I think about these things.

• 48:04Neil deGrasse Tyson?

  And everyone would weigh 50% more.

• 48:06Speaker 02

  Unfortunately, everyone would be on a zemp.

• 48:10Neil deGrasse Tyson?

  Just here's the thing. Most of us are already weigh 50% more. So if you want to know what it feels like to be on such a planet, there you are.

• 48:18Speaker 02

  Yeah.

• 48:18Neil deGrasse Tyson?

  Okay. Now you want to feel like it's back on earth, lose that one third of your body weight. And then you're back to what it is on earth.

• 48:26Speaker 02

  But let me tell you something cool about weight though. Look at what's behind you, the Saturn V.

• 48:29Neil deGrasse Tyson?

  Yes.

• 48:30Speaker 02

  Now, if you made the gravity 1.5 times heavier, that thing's not getting up. And so if you think about the rocket equation, the size that thing would have.

• 48:38Neil deGrasse Tyson?

  Which one does all the time? You think about the rocket equation.

• 48:40Chuck Nice?

  Of course, yes.

• 48:41Speaker 02

  That thing would have to be the size of a pyramid to get up. And so that's how, you'd have to lose 99.99999% of your mass as fuel. So it's thought that super Earth might be a prison, that civilization might be trapped there. They can never get off them because the gravity is so strong, they can't have a space.

• 48:58Neil deGrasse Tyson?

  Wormholes. Don't be so.

• 49:01Speaker 02

  They have to go. There's no natural progression, the same way that we've enjoyed.

• 49:06Neil deGrasse Tyson?

  So much smarter to, let's do, uh, little Timmy in preschool just designed a new wormhole.

• 49:11Speaker 02

  Right.

• 49:12Neil deGrasse Tyson?

  Let's use that one instead of the other. So know that it isn't interesting. Given our engineering flight technologies.

• 49:20Speaker 02

  Yeah.

• 49:20Neil deGrasse Tyson?

  We would not be able to launch.

• 49:22Speaker 02

  We'd be stuck.

• 49:22Neil deGrasse Tyson?

  From an earth that's one and a half.

• 49:24Chuck Nice?

  Yeah. Look at that.

• 49:25Neil deGrasse Tyson?

  You know what else I think about? If we were Venus, you would never know there was a night sky with stars in it.

• 49:32Chuck Nice?

  Right.

• 49:33Neil deGrasse Tyson?

  Because Venus is a thick, dense, opaque atmosphere.

• 49:36Chuck Nice?

  There's a tarp over Venus.

• 49:38Neil deGrasse Tyson?

  It's a tarp. It's a old tarp. So let me end on something that I wanted to even start with. This notion of unknown unknowns.

• 49:47Chuck Nice?

  Yeah.

• 49:48Neil deGrasse Tyson?

  Because on Venus, like I'm saying, I know that tarp will prevent anybody from seeing anything about the universe. There'd be no astronomy. No one would have ever thought it up because when you look up, you just see clouds. Okay? So to them, an unknown unknown is, it could be a universe beyond your planet. We don't have that problem here. Is there some unknown unknown that we don't even know we don't know? That puts us in a prison that another planet freely escapes from?

• 50:20Speaker 02

  That, that is a truly frightening thought, Neil. And it reminds me of how in cosmology, cosmologists often take for granted the fact we live now, but were we to emerge 10, maybe a hundred billion years in the future, when the, the universe has expanded so much, you would not see the galaxies at a certain point.

• 50:39Neil deGrasse Tyson?

  Would expand it beyond our horizon.

• 50:41Speaker 02

  And so you wouldn't, you'd think the Milky Way was the universe and you would never know all of that which is out there. That, I think that's an amazing coincidence.

• 50:51Neil deGrasse Tyson?

  In the time of Einstein's relativity, that's what anybody thought. To him, the universe was all the stars and the night sky of our Milky Way galaxy.

• 50:59Chuck Nice?

  Right.

• 50:59Neil deGrasse Tyson?

  So have you thought about a missing chapter in our book of the universe that we don't even know is not there?

• 51:05Speaker 02

  How can you think about that, but you do not know? It's impossible, but, but it's certainly possible. But we just, we can't imagine what that might be.

• 51:13Neil deGrasse Tyson?

  Wow. Okay. That we're just blithering idiots in the.

• 51:16Chuck Nice?

  I, I was gonna say, um, one thing is for sure, we're stupid.

• 51:21Neil deGrasse Tyson?

  Thank you, Chuck. So David, how can we find you? Remind us.

• 51:25Speaker 02

  Uh, you can find me on the Cool Worlds YouTube channel. So.

• 51:28Neil deGrasse Tyson?

  It's just called Cool Worlds?

• 51:29Speaker 02

  Yeah. Cool Worlds. It's just called Cool Worlds. And I've also got a pod, so you can go to the Cool Worlds podcast.

• 51:35Neil deGrasse Tyson?

  And revenue from that drives your lab, isn't that correct?

• 51:38Speaker 02

  Yeah. Yeah. Yeah. We, we, if we have donors, like you have your Startalk patrons, we have patrons, but, um, all of that money is just used for research actually. So that's kind of fun that you could, you can pledge your money to go to real discovering, hopefully.

• 51:51Neil deGrasse Tyson?

  And as more and more research money is evaporated.

• 51:54Chuck Nice?

  God, yeah.

• 51:54Neil deGrasse Tyson?

  That funding model becomes more and more significant.

• 51:57Speaker 02

  I think so.

• 51:58Chuck Nice?

  Thank you, Doge.

• 51:59Speaker 02

  Yeah.

• 52:00Neil deGrasse Tyson?

  Until the day you get the phone call from somewhere else saying, we got a lab for you here.

• 52:04Chuck Nice?

  Which is probably, yeah. And, you know, with that accent, he's like, see ya bitches. No, I'm joking.

• 52:14Neil deGrasse Tyson?

  So yeah, we already know, we already have colleagues who have been cherry picked.

• 52:17Chuck Nice?

  Yeah. This is a real problem. You guys better write, you know, reach out to your congress people, reach out to your senators and let them know that you want science funded in this country.

• 52:28Neil deGrasse Tyson?

  Chuck for president.

• 52:29Chuck Nice?

  The power of the purse still resides in the Congress and not the executive branch. And that you won't stand by and allow for science to be defunded. Okay? So that's it.

• 52:41Neil deGrasse Tyson?

  Thank you, Chuck.

• 52:42Chuck Nice?

  No worries.

• 52:42Neil deGrasse Tyson?

  Are you just smart enough?

• 52:46Chuck Nice?

  So true.

• 52:46Neil deGrasse Tyson?

  Funny, you should say that, Neil.

• 52:49Chuck Nice?

  That's the name of my special, which is right here on the, on the Startalk YouTube channel. Check it out. Just smart enough.

• 52:55Neil deGrasse Tyson?

  It's easy to find. It's right there. All right. So thanks, David.

• 52:58Speaker 02

  My pleasure. Thank you.

• 52:59Neil deGrasse Tyson?

  Skateboarding.

• 53:00Speaker 02

  Anytime. Anytime.

• 53:02Neil deGrasse Tyson?

  For one wheeling over here.

• 53:03Chuck Nice?

  Forty blocks south. Saving the, saving the planet with your water bottle and your one wheel.

• 53:10Neil deGrasse Tyson?

  He's still exhaling CO2 though.

• 53:13Speaker 02

  Still working on that.

• 53:16Neil deGrasse Tyson?

  This has been StarTalk, Cosmic Queries, Cool Worlds edition. Until next time, we bid you to keep looking up.