Rogue Planets & Exomoons with David Kipping

12:54Neil deGrasse Tyson:So is that similar to, because I remember back during the, was it the Challenger disaster? 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. Oh yeah, yeah. And then you add to it and see if the conclusion remains. Yeah, if the last bit of evidence is what tips it, then it means most of the evidence wasn't really pointing to that result. Yeah. And in science, you want the more evidence to align with what your thoughts were. Right. Otherwise, go home.

13:30David Kipping:Right. Yeah. Yeah. Right? Yeah, I mean, in statistics, we call that cross-validation. Cross-validation. Okay, I like that. When you block out some of the data, you do all your fits on the data you have, and then you uncover your hand and ask which one actually works. Yeah. And that's like the true discriminatory test of which one is working. Okay, so this will be a way to keep people on notice. I think it's an important question. It's the question we all care about, right? I think it's where there's life out there and I just want to get an answer before I die, right? I hope that HWO succeeds. This is a major motivation of science.

14:00David Kipping:Yeah, I want to get it done before I die. Before I die. Right, don't worry. When you die, Jesus will tell you all the answers, okay? You don't have to worry. He'll be right there.

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18:06Neil deGrasse Tyson:This is a Cosmic Queries. You have a huge fan base out there among our followers. And so, Chuck, you got it lined up? I have them right here. Okay. And you haven't seen these questions, right? They're coming right out of the blue for you. Cool. Good for, yeah, that makes three of us. Okay. And these are our Patreon supporters who have given us$5 a month. Right, which qualifies you to be able to submit your query. All right, here we go. This is Andor Klomp, who says, Dear Dr. Kipling, Dr. Tyson, Lord Nice. Kipping. Kipping, sorry. Dear, I said Kipling. Oh, I made you quite literary, didn't I? Kipping and Richard is father.

18:52I 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? Well, we're not sure.

19:29David Kipping:That's a good question. We're actually not sure. Oh, really? Yeah. So actually, it's probably almost certainly not rocky, to be honest with you. Really? Okay. It's about five and a half Earth masses. All right. But it's 1.7 Earth radii. Okay. So when you do the math, that gives you a density that is actually similar to that of the Earth. Sounds like it. Right. Right, so that's why all the news was, Rocky Planet found. Right, so you might think that's rocky, but the problem with that is is that that's compressed density, right? There's 1.7 Earth radii, it's 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.

20:03David Kipping:It can't just be pure rock. It can't have squeezed in that way. 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,

20:15Neil deGrasse Tyson:like ice or something. So something's confounding those blunt calculations and confusing how to interpret.

20:23David Kipping:I mean, it's a challenge because we have nothing in the solar system to point out and say, oh, that's what it must be. Again, there's a problem. There you go. Right, the solar system is not a thing. It's in between Earth and Neptune. It's okay. And we just don't really know what those things are. Does that nullify the inquiry here? No, it's at the right distance from its star, potentially for liquid water, if it has water. Yeah, it's in the Goldilocks zone. and 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. So if it has life on it, which I think is possible, it's not an Earth-like planet.

20:59David Kipping:I want to 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. 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. So here's what I want to know. All right, just has really nothing to do with this, just because you said something that triggered me.

21:29All right. When it's Goldilocks zone, right? Yeah. 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?

21:52David Kipping:Yes, yes and no is the short answer to those three questions. Wow, there you go. That was easy. I wasn't tracking it to be that efficient in my reply. No, yeah, all stars, this is actually an M dwarf, so it's a small star I'm not sure if it's 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, but 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. But it is nearby. The star, because it's less luminous than the sun, means this Goldluck zone is much closer.

22:31David Kipping:And yeah, as it ages...

22:33Neil deGrasse Tyson:And importantly, for these cooler stars, cooler, there's thousands of degrees, the Goldilocks zone is not only closer, it's narrower. Ah, okay. Okay. Okay. So the hotter stars get bigger Goldilocks zones. So these are, in the statistics of Goldilocks planets, this matters.

22:48David Kipping:Okay, yeah, of course, yeah. And just to finish that point, as it ages, the Goldilocks zone must actually move out, usually, for main sequence stars. So it should, as the sun is increasing luminosity, it was about 30 % less luminous 4 billion years ago than it is today. I think that's roughly about right. Yeah, that feels right. So that means the Goldilocks zone is moving out. Right. 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 it wasn't, if we were two billion years ago, we could have probably polluted a lot more, not worried about it.

23:15David Kipping:But because we're on the inner edge of the Havdel zone now, we have to kind of worry about this a bit more. Yeah, a lot more. Yeah. Wow. We'll go back four billion years. Either one. Exactly. Yeah, let's go on. Here we go. This is Alejandro Guardado. He says, he says hello Dr. Tyson Lord Nice and Dr. Kipping Alejandro here from Washington State hello or should I say hola that is not what's in there I know it's not

23:57oh god okay he says this let me stop messing around I'm sorry.

24:05Neil deGrasse Tyson:I got to agree. That's what Alejandro should sound like. If he don't sound like that, he should take some lessons. I just see him sitting around drinking an espresso with Antonio Bandana. Yeah, exactly. That's what I'm about. 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 the simplification lead to less fear in our society about aliens and lead to advances in the search? Thank you for always keeping me curious. NASA, in the day, used to have interest in the search for life.

24:48Okay.

24:49Neil deGrasse Tyson:Which included the search for intelligent life. Okay. 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 money 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 beyond the pale. and so nasa 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 right okay so there's a whole seti institute which is privately supported yes and so kind of in response to this they are two separately funded activities.

25:44Neil deGrasse Tyson:Now, if someone on your exoplanet waves to 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.

25:52David Kipping: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. That's the idea. That's been established. But technological life, I think, is something we could look for, and it's pretty interesting if that's out there. 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 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.

26:28David Kipping: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.

26:38Neil 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. Right. So if you have another example...

26:52David Kipping:I think one independent example of either life or technology would be enough to say, hey, universe has done it twice, completely independently.

27:01Neil deGrasse Tyson:And life has been on Earth for three and a half billion years. Right. For two and a half of those three and a half billion, it was just single-celled organisms. Right. 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. Right. More likely to do that. There's some of the dart statistics on this. But, okay. And would one sign of technology be smog?

27:30David Kipping:It could be. I mean, that'd be depressing, wouldn't it? I think the advantage, the beauty of a techno signature is that some of them, not all of them, not smog, could be unambiguous. If you get, like in the film Contact, where Jodie Foster has the headphones on and gets 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 that someone's engineered that. Whereas if we detect a gas, so that would be slam dunk. There's definitely aliens. If you detect dimethyl sulfide in an exoplanet atmosphere, people are going to argue about that for years and decades to come.

28:11David Kipping:So that's the advantage of technosignatures. It can be clear cut. They're not going to argue over engineering plans. Exactly. Like if they send you IKEA directions, it's a done deal. How to put together your table. Exactly. Right. And then at the end of the directions, it says, don't worry if there are pieces left over.

28:33Oh, wow. That's really cool. And I love that. 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, Tiroa and Catoquil 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, etc.

29:18Neil deGrasse Tyson:I love that. And there's no shortage of those names. those names. Right. You know, we had a similar challenge when asteroids were discovered. Yeah. 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. Oh, okay. Okay? So that was a little weird. Because it was the, feminine would be the diminutive variant of a planet name.

30:00Neil deGrasse Tyson:Gotcha. Okay, because they're asteroids, right? 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 an asteroid Santa. Okay? people love observing that on New Year's Eve a friend of mine did that and he showed me the data when you have nerd friends that's the kind of stuff you do

30:21David Kipping:I kind of think we should just call them GPS coordinates you give me a number and then I know exactly where to go and look at it because if you give me a name like go to Aurelius or something 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

30:39Neil deGrasse Tyson:as you may know the moons of Uranus that are all named for Shakespearean, fictional characters in Shakespearean literature. Okay. Of which there are plenty enough to get you going. So another thing, 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. That's awesome. Yes. Now that makes sense. Yeah, so one of them is Apophis. Right. The Egyptian god of death and darkness. Nice. Yeah. And there are plenty of, you know, 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.

31:21Neil deGrasse Tyson:So that's the problem.

31:22David Kipping:But you go to Lysh, you've got Sauron. You've got Sauron. That's what I'd be doing. Yeah, cool.

31:27Neil deGrasse Tyson:Yeah, man. Yeah. I love that. Well, hey, hey, there you go. Yeah, but I think David is right. At some point, the coordinate on the sky is uniquely identifies it. Right. And you know what? think we can do because were you an amateur astronomer at all as a kid not not at a high level 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 right i was gonna say you have the coordinate as the name and then in parentheses underneath. Or quotes. Or quotes. There's Tabby Star.

32:07Neil deGrasse Tyson:Yeah. There's Barnard Star. Right. Barnard Star is another one of these stars that's nearby and Barnard first studied it, but it's got a catalog name. Okay. 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 need the unambiguous identifier. Okay. Yeah. All right. All right. 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. Ooh, I want to be there.

32:42Yes, we are. Invite us. What's your name again? Mary Rose. Invite us all. Yes, 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. I love that.

33:02David Kipping:Yeah, that's a great question. There are many things we've discovered which blew our minds. I think what we kind of expected, I mean, this is a little bit before my time, is that we'd find other solar systems which looked like our solar system. This is the template, everything would look the same. Of course. And I think the greatest... Oh, the hubris, but go ahead. We are the default. But it turns out we're actually kind of weird. And most solar systems look very different. So I think it's a very 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.

33:38David Kipping:What? And we do not have one. And we don't have one.

33:41Neil deGrasse Tyson:We don't have one of these. That ain't right. That ain't right. Yeah. That's weird. That ain't right. That's kind of strange. How mini is a mini Neptune? It's in between about... What fraction of Neptune's mass would that be?

33:51David Kipping:Well, it's in between about two and four times the size of the Earth. So that's about half the size of Neptune. Yeah, so super Earths. Yeah.

33:59Neil deGrasse Tyson:A super Earth.

34:00David Kipping:A super Earth, is that the same as a mini Neptune? We don't know. The other thing, because people argue about the name, some of them say, you can't call it a super Earth, we don't know it's Rocky, you shouldn't call it a mini Neptune. I invite you on the show for you to say

34:09Neil deGrasse Tyson:that you don't know. You're the expert here. We don't know. That's how you know he's good. That's right. That's it. Exactly. Okay.

34:17David Kipping:But I think that diversity is surprising. There are circumbinary planets, like the Tatooine, like you had in Star Wars. George Lucas imagined that and everyone just thought he was crazy, but we now know comment about that. Do you think he really knew or did he just think it was cool? No, no, no.

34:33Neil deGrasse Tyson:No, no. But I do. It's the only science in all of Star Wars. That's as good as it goes. Oh my gosh. It's downhill from there. It is downhill. Oh, that's just awful. It is totally downhill from there. That only worked because of the distance to the planet relative to the distance between the stars. so that the planet sees two stars. That's the double sunset. The famous scene is 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 where to go out of orbit, you get a chaotic trajectory.

35:19Neil deGrasse Tyson:That's the three-body thing, right? It's a three-body problem. That's a three-body problem. 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 that planet was. So you can create stable orbits that way. So that's the only way that works. So that's good science.

35:37David Kipping:And just add, we call that a P-type orbit. A P-type orbit. Because you can 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 the world. Oh, that's also a stable orbit. That's an S-type.

35:54Neil deGrasse Tyson:That was the S-type. Satellite. Oh, okay. Yeah. That's cool. There you go. That's very cool. But then you don't get two sunsets. No. Yeah, yeah, yeah. That was cool. Okay. 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? Yeah, they just got out of dodge. Just get out of here. Yeah. So how common would it be if we were able to see them? where we just see planets wandering around like they lost from the home.

36:33Yeah, yeah. Homeless planets. Homeless planets. They were homeless,

36:35Neil deGrasse Tyson:and then they became rogue planets. Oh, well, that sounds a lot more badass. It's a little bit more badass. It's only none of y 'all. So, David, the numbers I remember are that our solar system might have started with as many as 30 planets, coming down to the eight that we now have. Yeah. So that tells us that maybe there are more rogue planets than there are planets with homes.

36:57David Kipping:Right, yeah, this is a really hot area in astrophysics right now, rogue planets. So you could get a PhD right now doing this. It's a hot topic. But you're right, it's thought the solar system had more planets. Some of them merged together. 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 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.

37:31David Kipping: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 going to be... Nancy Grace Roman Telescope. It's going to be the perfect machine using microlensing to detect a whole host of those. So we're expecting thousands of those to be found. So this is where you have a star in the background.

37:49Neil deGrasse Tyson:Ideally, it's a dense star field, like the center of the galaxy. Of course. And you just watch for any starlight that that increase no no that it oh gets brighter gets it's not in a eclipse okay oh it 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 freaking nowhere right and there's a planet behind it pathways of that star's light going around the planet come back and join magnifying the brightness of the star itself because a sight line would have gone and missed you.

38:24Neil deGrasse Tyson:This sight line would have missed you. They had bent into your view, adding to the brightness of the object. It is gravitational lensing for rogue planets. But it's only a tiny amount, and we call it microlensing. Yes, yeah, yeah. There's enough of a variation in the travel of the light for you to determine that? I mean, in terms of the magnification? The magnification, yeah.

38:45David Kipping:It's very small, but Roman's a very precise telescope. Holy crap. 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. One per day, yeah. That's the power of Roman. 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. That can boost your statistics. Well, if the star gets brighter and dimmer, how do we know it's not the star doing that?

39:13Neil deGrasse Tyson:Because usually the star repeats that, whereas a microlensing event is singular in time. Plus it has an exact profile. Oh, it would be singular because the planet is on the move. It's on the move. It's on the move. Oh, crap. 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. That's wild. David, Earth retains some of its heat of formation. Yeah. And it's got heat from radioactive decay 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 yeah anyway they're all blind it's possible

40:10David Kipping: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. Io is a volcanic world. Lots of energy there. Europa 2 probably has a liquid ocean. Tidal heating, you mean like a subtle stretching and contracting of the... Yeah, so 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. It's like a squash ball. It kind of gets stretched and squeezed like a piece of dough. That's probably what happened to these moons.

40:43David Kipping:And so you could have, for billions of years, life just thriving in between the stars. That is dope. Yes, totally dope. That is unbelievable, man.

40:53Neil deGrasse Tyson:Well, it's totally believable. That's what makes it dope. Wow. Yeah, and in fact, look at the bias thrust upon us by biologists. Right. Saying, the sun is the source of all life in the world. It's the source of most life. Right. But there's life doing the backstroke at the bottom of the ocean. That never gets a chance to encounter. Geothermal energy. Right. And so it's not that life needs the sun. is that life needs energy. And if you find another way to get the energy, that's why we're looking for life on Europa. Yeah. Another tidally heated moon of Jupiter. Right. Yeah. Interesting. Okay. Wow, that's so cool, man.

41:26Neil deGrasse Tyson:So what's the difference between Europa and Io in their tidal heating?

41:31David Kipping:In terms of the amount of energy? Yeah. Well, Io is on the inside. It's close to Jupiter, so it gets the real brunt of it. There you go. Europa is, I think, number two, right? So it still gets heated, but not as much as Io.

41:41Neil deGrasse Tyson:Okay. But Iowa's so significant that there's volcanoes on it. Yes. Yeah. Right. It's liquefied the rocks.

41:47David Kipping:Oh, you can see it coming out into space. Yeah. It's crazy. Yeah. Yeah. Yeah. Okay.

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43:30All right, this is Peter Jacobs, and Peter Jacobs says, G'day to David, Neil, and the applaudable, laudable, audible, oh my lordy, lordy, lord nice. What? Yeah. Peter Jacobs here from Mooloolaba in sunny Queensland, Australia. Okay. I'd like to get me some dimmies. Oh, okay. All right.

43:54Neil deGrasse Tyson:He says, thinking of the Fermi Pass. That's quite the intro to this. Did you make that up? No, this is written. I don't know sometimes. I was just doing a terrible Australian accent. That's all I added to that. Sometimes I don't know what it is. No, I'm ready for Bingham. Okay, okay, go on. 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. Wow, that's too wild. So the amount of radiation coming out of a pulsar or a collision.

44:35Sagittarius A is the supermassive black hole in the center of the galaxy. Right.

44:38Neil deGrasse Tyson:And it is a rockin' sockin' place. And other galaxies, it's even more severe than ours in terms of just the flux of high-energy radiation. So do you guys think about— That's wild. Let's soften this just a little bit. Okay. Some stars give off a lot of UV. like the blue stars, the bluer stars, and UV is hostile to life. It's to everything. So are you thinking about life on planets that orbit high-temperature stars?

45:08David Kipping:Yeah, but it's a great question, and I think it touched on an idea called the galactic haptical zone. So you can have a haptical zone around a star, but there might also be a haptical zone in our own galaxy. Okay, and that would be

45:20Neil deGrasse Tyson:a radiation problem for you if you're a little too close to the center.

45:24David Kipping:Not necessarily just radiation. It could be metallicity. The metallicity of the galaxy changes in different locations. I don't know what metallicity is. It's jargon.

45:33Neil deGrasse Tyson:He's now got to explain the jargon.

45:35David Kipping:Okay, so it's the heavy atomic elements. Basically, in astronomy, anything heavier than hydrogen and helium, the two things that came out of the Big Bang, are a metal. And that's what you're made out of primarily. Chemists hate that.

45:45Neil deGrasse Tyson:Because we call everything metals. Is it metal rich? Yeah. If it has carbon, it's considered a metal. And chemists hate that. So the whole universe is one big headbanger's ball. A metal man! Okay, so you have the radiation in the center, and you need enough heavy elements... To make planets. To make planets and people.

46:08David Kipping:Yeah, and you need, I mean, when you really look around Sagittarius A-star, you've seen some of these animations they've reconstructed of the star paths. They're on top of each other. So planets wouldn't even be stable. Yeah, okay. These stars...

46:21Neil deGrasse Tyson:Yeah, there's like these loop orbits, and it's what won the Nobel Prize. Right. That the observations confirming the black hole in the center of the galaxy by tracking these orbits 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. Interesting. A perfect combination of theory and observation there.

46:45David Kipping:So there's other parameters. Yeah. So you've got to form a planet. You've got to have... With the right ingredients. Yeah. You've got to have a stable orbit. and then the radiation environment has to not sterilize you. 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.

47:07Neil deGrasse Tyson:So you don't even want to be around another star that blows up. Okay, yeah, cool. That's funny because I read that one of the reasons for life here is the fact that we're in a suburb of the Milky Way galaxy. Yeah.

47:21David Kipping: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 where we plunge towards the center and come back out. So we're in a nice neighborhood.

47:33Neil deGrasse Tyson:We're about two thirds of the way up. We don't have to commute into the city. It's been red line from early on.

47:45We're in the Carroll Gardens. Milky Way.

47:50Neil 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 yeah and one full orbit is a couple hundred million years so that's at our distance plenty of time well no but that evolutionarily right that's it works that's pretty stable yeah yeah Yeah. Gotcha. All right. Wow, that's all cool stuff, man. Damn. Yeah, you do some cool stuff, man. That's why. I think it's called the cool laboratory. Oh, that's right. Cool world. Cool laboratory. All right. There we go. This is Mike Landers.

48:30He says, hi, Dr. Taising, Dr. Kipping, Lord Nice. This question comes from San Francisco. If we eventually detect an unambiguous technosignature 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 day. Oh, I like that.

48:52David Kipping:So how far away are your stars? For SETI, for technosignatures, we can search across huge spans of the galaxy. I mean, you can span tens of thousands, even 100 ,000 light years in some extreme cases. So they could easily have gone extinct. But your stars, your cool stars, they're not that far away. For biosignatures, there's things that James Webb are observing and trying to get signs of atmospheres, those are nearby. So those are 10s, 20 light years, 30 light years away.

49:20Neil 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... It's not prohibitive of you getting a similar... Right, but the technosignature

49:31David Kipping:doesn't have to be like an active beacon. It could be... One of the coolest ideas I've ever heard for a technosignature 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 aluminum. 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. That's a space Dorito. 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.

50:06David Kipping:So we could leave a relic that would betray our presence and you could even have interesting signals there. These are the Easter Island heads.

50:15Neil deGrasse Tyson:Oh. Yeah. The civilization left them there. Right. And it's been argued that you come upon the island and they're looking at you still. Right. Yeah, if you leave some purposeful relic. A monument.

50:30David Kipping:Monument, that's the word. The pyramids are a communication from another civilization to us through time. Mm-hmm. 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. Wait, just to be clear,

50:47Neil deGrasse Tyson:he's not saying that pyramids were left by aliens. No. I just want to... A human civilization. Left by basically an extinct human civilization. Yes. Ancient Egypt is no longer with us. It's like they're descendants, but they're not building pyramids anymore.

51:02David Kipping:My provocative claim is that the most likely alien contact we will ever have, not really a contact, but a way of 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.

51:35Neil 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 Earth used to have - It doesn't have to be an apocalypse,

51:50David Kipping:but yeah, 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. I think there's mammal species around a million.

52:04Neil deGrasse Tyson:Other species, I'm not sure.

52:05David Kipping:Yeah. It's rare. It's rare. There are some, but it's unusual for a species to last that long. So I, that's my - Believe me, we're not going to be. No. We don't even have to worry about whether or not we're going to make it to a million years. Come on. So I think - All right, that's cool. Velics are a cool way. There's a whole thing called Artifact SETI, which is the question askers should definitely look into, yeah. All right, here we go. This is, here we go. This is Aidan Rodriguez who says, hello, Dr. Tyson, Lord and Nice, and Dr. Kipping, greetings from Panama City, Panama, the country that gave the world the Panama Canal.

52:42I'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, also would it evolve in an atmosphere with much higher pressure than ours? Thanks so much. Keep up the amazing work.

53:02David Kipping:Yeah, that's pretty wild. That's a great question. I think the immediate challenge is how would you engineer a planet to have two or three times Earth's gravity? Because as you increase the gravity, a planet will naturally accumulate gas around it as it's forming. So you're going to turn into a gas giant, basically. Even only three times the gravity? I think by three times, yeah. Really? I don't think there's any super-Earths that are more than like 1.7, 1.8.

53:27Neil deGrasse Tyson:Oh, so super-Earths are just slightly more muscular, but not multiples. I did not know that. They didn't get that extreme. Oh. Yeah. And at that point, all the fluid that has accreted puts a pressure on the surface, and so the pressure would be super huge too.

53:43David Kipping:Right. 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...

53:51Neil deGrasse Tyson:Everyone would weigh 50 % more. Unfortunately. Just so you know. Everyone would be on a Zempick. Oh, I hate to call a Zempick. Just here's the thing. Most of us already weigh 50 % more, so if you want to know what it feels like to be on such a planet, There you are. Yeah. Wow. Now, you want to feel like it's back on Earth. Lose that one-third your body weight, and then you're back to what it is on Earth.

54:13David Kipping:Let me tell you something cool about weight, though. Look at what's behind you, the Saturn V. Yes. Now, if you made the gravity 1.5 times heavier, that thing's not getting up. Yeah, look at that. And so, if you think about the rocket equation, the size that thing would have to be— Which one does all the time? You think about the rocket equation. Of course, yes. That thing would have to be like the size of a pyramid. Yeah. You'd have to lose 99.99999999 % 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.

54:44David Kipping:They can't have a space edge. Don't invent wormholes. Don't be so Earth-jingoistic. Right, but there's no natural progression the same way that we've enjoyed.

54:52Neil deGrasse Tyson:Maybe there's so much smarter. Dude, little Timmy in preschool just designed a new wormhole. Right. let's use that one instead of the other so know that it isn't interesting given our engineering flight technologies yeah we would not be able to launch we'd be stuck from an earth that's one and a half yeah look at that you know what else I think about if we were Venus you would never know there was a night sky with stars in it right because Venus is a thick dense opaque atmosphere there's a tarp over Venus it's a tarp it's a tarp so let me end on something that I wanted to even start with this notion of unknown unknowns yeah 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 because it could be a universe beyond your planet We don't have that problem here.

55:54Neil deGrasse Tyson: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?

56:07David Kipping: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 100 billion years in the future when the universe has expanded so much, you would not see the galaxies at a certain point.

56:26Neil deGrasse Tyson:The galaxies would have expanded beyond our horizon.

56:28David Kipping:And so you'd think the Milky Way was the universe, and you would never know all of that which is out there. I think that's an amazing coincidence.

56:38Neil 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. So have you thought about a missing chapter in our book of the universe that we don't even know is not there.

56:52David Kipping:How can you think about that but you do not know? It's impossible, but it's certainly possible. But we just, we can't imagine what that might be.

57:00Neil deGrasse Tyson:Wow. Okay. That we're just blithering idiots. I was going to say, one thing is for sure, we're stupid. Thank you, Chuck. So David, how can we find you? Remind us.

57:12David Kipping:You can find me on the Cool Worlds YouTube channel. It's just called Cool Worlds? Yeah, Cool Worlds. It's just called Cool Worlds and I've also got a pod so you can go to the Cool Words podcast. And revenue from that drives your lab, isn't that correct? Yeah, yeah, yeah. We have donors, like you have your startup patrons, we have patrons, but all of that money is just used for research, actually. So that's kind of fun that you can pledge your money to go to real discovering, hopefully new planets.

57:39Neil deGrasse Tyson:And as more and more research money is evaporating, that funding model becomes more and more significant. I think so. Thank you, don't. Yeah. Until the day you get the phone call. from somewhere else saying, we got a lab for you here. Which is probably, yeah. And, you know, with that accent, he's like, see ya, bitches. No, I'm joking.

58:00Neil deGrasse Tyson:So, yeah, we already know, we already have colleagues who have been cherry-picked. 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. Chuck for president. And that 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. Thank you, Chuck. No worries. Are you just smart enough? So true. Funny you should say that, Neil. That's the name of my special.

58:37Which right here on the StarTalk YouTube channel. Check it out.

58:40Neil deGrasse Tyson:Just smart enough. It's easy to find. It's right there. All right. So thanks, David. My pleasure. Thank you. skateboarding. Anytime. Anytime. For one-wheeling over here. 40 blocks south. Saving the planet with your water bottle and your one-wheel. That's right. He's still exhaling CO2, though. Well, yes. Still working on that. This has been StarTalk at Cosmic Queries Cool Worlds Edition. Ooh. Yeah. Until next time, we bid you to keep looking up.

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