Searching for Habitable Worlds with David Kipping

0:00So Chuck, we went everywhere on exoplanets. We got from planets to the ingredients of the entire universe. So that's how much was covered in this show. And exoplanets with moons. Yes. You know, we're thinking just it's a planet, but why can't they have a moon? We got a moon. Give them a moon too. Exactly. And so we have people interested in the moons of exoplanets. Yeah. And we can actually - Will they never be satisfied? That's what I'm saying. Like, when does this end? All right. A lot of exoplanets coming up on StarTalk. Welcome to StarTalk, your place in the universe where science and pop culture collide.

0:44StarTalk begins right now.

0:51This, StarTalk, Neil deGrasse Tyson, your personal. This is Chuck with me. How you doing, man? Hey, what's happening? Doing all right? Doing great. Thank you. Doing good. Nice. A little while ago, you recorded a comedy. special yeah but it's not hasn't aired yet um we have to sell it so anybody knows anybody at netflix i need my money back i'm telling you the truth people i was going to do like one of those like what are they called uh fund me go fund me yeah but i was like okay no listen if you believe in yourself go ahead put out the money you'll get it back you got the talent don't worry about it i should have did the go fund me oh you're saying that about yourself yeah exactly no it's not but hopefully um hopefully it'll be out very soon all right we'll look for that so it's another the Cosmic Queries today, and it's bespoke.

1:36Very spook. It's not a grab bag. That's right. And the topic is cool world. What? Ooh. What? I know like a little bit about cool world, but I don't know enough to do a whole Cosmic Queries on it. So we combed the hood. Yes. And up the street, there's an entire university called Columbia. It is. That's where I got my PhD. Right. Columbia. Yes, it's the Rutgers of Harvard here in New York City. What? So, we have a professor of astronomy from Columbia. Yes. David Kipping, welcome. The leader of all cool worlds. I'm the man right here. Yeah. Thank you for having me, guys. Yes, so you're head of the cool world's lab.

2:21So, since you're a scientist, not a hipster, I have to believe that the word cool references temperature and not attitude. It's a bit playful, but yeah. We're not Dope Worlds Lab. That's what you should have named it. That would be amazing. You should have named it Dope Worlds Lab. Oh, man. You'd lost that opportunity. Brand proposals might be a bit tricky if we have that on the tagline. Check my temperature, yo. Because my planets are dope. Well, sick. We could go sick maybe next to Worlds. Sick is another one. Yo, you ready for this? Sick Worlds. I'm down with a kid.

3:02I'm sorry you caught me on that one. It's been my experience that anyone who says I'm down with the kids is not down with the kids. All right, so full worlds, we're referring in your particular case to worlds outside of our solar system, exoplanets or exoplanet moons. Anything exo. Exo rings and exotrojans. You can throw it all in there. All right. Exo-tromets, you go. Okay. Well, tell them what you mean when you say exo-trojans. Because he's thinking— You saw me. I went—you saw what I did. So I was just like, I've heard of the birth of a star. I've heard of that. Where they don't use trojans.

3:42Yes. But the trojans are like— Why are we going back to ancient Greek? Yeah, this is—around Jupiter, there are these additional small bodies called trojans, and they're in the little grunge point. So Jupiter, as it goes around its orbit, that if you look 60 degrees off axis on either side, there's the Trojans and the Greeks, and it's these small collection of asteroids and small bodies. And so we think we could detect those around other stars. And so then there would be exo-Trojan. Yeah. Put exo in front of anything. And there you go. That's the branding. Put exo in front. Put some exo on it. So that Lagrange point is the sun and Jupiter.

4:20So that would be, I guess, L1234. of three and four. Right. We did a whole thing on LaGrange Point. Yes, we did. We did. Yes. This is why, and people say, when I say things like, right, or okay, they think I'm just playing along to look like I'm like, oh, I'm in on this. But what they don't understand is that we've talked about this stuff. Yeah. And what's happening is it's coming to my memory and I'm like, right. Okay. You should have an honorary PhD. Not at all. You're almost there, right? I'm not. I'll find some certificate up here. See, I'm afraid to receive that just because they're like, you should know a lot more.

4:58You should actually know a lot more than you do. This can't be right. So our solar system is a template for you to think about and imagine what could exist in other star systems. Indeed. That's fair to say. Yeah, exactly. Okay. Are there any super anomalous solar systems come across that are just so unlike ours that it really perks things up? Or do most of them just kind of fall in line? I'm going to answer for them. Oh, all of them. Yeah. Really? Okay, now go. You give your answer. I would say you're not too far off here. I would say that the majority of solar systems look radically different to that of our own.

5:33That's amazing. Yeah, you have binary star systems, which, you know, are very, very common. And that's a half of all the stars you see in the night sky have multiple stars. Two or more. Just off the bat, that makes it unusual. Even having a Jupiter is unusual. Only 10 % of single stars have a Jupiter-like planet. So just having not just one, but two Jupiters in our solar system is already kind of unusual. Two Jupiters would be Jupiter and Saturn. Yes. Yeah, I'm going to throw Saturn in because it's the same size. It's very different mass, but it's roughly the same size. It would be nice to it because Saturn is one of my, see my desk lamp here?

6:02Oh. Oh, you guys can't see. No shade on Saturn. It's beautiful. My desk lamp, I hand made in woodshop in seventh grade. And it's a ring. It's made of wood and it's a ball and a ring. and you press down the ring, and the ring tips, and it turns the light on. It turns the light on. So me and Saturn go way back. Don't just lump it in with Jupiter. And he only lost one finger. That's what you said. But I also, in my notes here, it says there's a YouTube channel on this? Yeah, I've got a, yes, my team is called The Cool World's Lab at Columbia University. We're a research group. I have currently four graduate students on my team, and we're studying all different projects, looking for exomoons, looking for these weird phenomena around these cool planets.

6:44But at the same time, when I first arrived at Columbia, which was, eight years ago now, I decided one of the things I wanted to do was also talk about science. You're well aware of the importance of doing that in popular culture. So I started a small YouTube channel. Didn't think Hullian would watch it, but during COVID, many people decided for whatever reason they were interested in astronomy. And you post there with what frequency? Usually once every three weeks or so. Yeah, so it's, I mean, I have a full-time job doing my research, so I can't post there as much as I'd like. People moan about that all the time, but, you know, it keeps things fresh.

7:17by having one foot in research and one foot in the psychon world. Yeah, otherwise you get stale in both. Perhaps, yeah. That doesn't happen. Yeah. Now, you said you have four graduate students. When someone boasts of how many graduate students they have, it means there's actually a lot of work that needs to be done. And they will do work because they need to get their degree, and you alone stand between them and their degree. Well, that's too much power for one man to die. Oh, that's terrible. Great power. No, but we have evidence that there's life after this arrangement. One of your former students we've had as a guest on StarTalk.

7:50Who was that? Moira McTeer. Yes. Dr. Moira McTeer. Yeah, she was one of my first PhD students. You get to say doctor. It came through. By the way, that doctor is courtesy of me, Mr. Kipping. Yeah, it does feel like an honor to bestow, you know, help these students get to that point. I mean, I normally actually come to the defending the PhD. It's not just my decision, of course. I'm actually supposed to keep my mouth shut and let, you know, the other people decide. There's actually a committee that puts you through the ringer. They're not there to be nice to you. They're there to stump you. And the less stumpable you are, the better a scientist you can become.

8:23I gave all my PhD students, I think, a lightsaber. So I think Moye probably has one buried in her cupboard probably at some point. Just in case. Bestow upon her with a lightsaber, her PhD. No, no, but the thing is, an actual saber will stop at your shoulder, whereas a lightsaber won't. This is just a toy lightsaber. Oh, toy lightsaber. Just relax. Okay, fine, fine. I'm quite there, yeah. Don't let people know that. We actually have real lightsabers out there. Right. You can tell all of Dr. Kibbing's students because they have a very significant burn. It goes from their shoulder to their navel.

8:56Didn't you wait tonight? So tell me, before we get to our Patreon questions, tell me, what are some of your challenges? How much of what you do is theory or modeling or observations? What telescopes do you use? Do you have a favorite spot in the universe? using Kepler data? What feeds your operation? It's a big bag of all sorts of stuff, to be honest. I mean, I'm kind of glad that you didn't ask, are you a theorist or an observer? Because I really don't like labels like that. I kind of feel like if you call yourself an observer, if somebody goes to the telescope, looks for different objects in the sky, it kind of limits your mind space, right?

9:35So now you think, well, I can't do the hard theory stuff because I'm an observer and vice versa. I try to keep my feet sort of in every pocket as I can to try and stay nimble. But the data set we're excited about at the moment is JWST, of course, like many people. That's the… JWST is touching everybody. Yeah. Not in that way, but in the good way. You weren't thinking that. You're the one. You're just… Okay. I like it, though. So it's infrared data of what objects? The observations we're planning in October will be of a Kepler planet, actually, called Kepler 167e just rolls off the tongue. Why Kepler?

10:15Why Kepler? Kepler was great for finding cool worlds because it was very patient. So it stared at the same... Kepler's been dead for 400 years. Not Johannes Kepler. That's a good... Oh, thank you. Okay. We should not be thinking about Johannes Kepler, but the telescope named in his honor... There you go. Okay. There's a telescope. Listen, so we got a medium and it appears that Kepler says... His spirit energy. There's this planet. Yeah. Okay. But go ahead. So this planet was discovered by the Kepler mission, I should say, the NASA Kepler mission. And it was a planet actually I discovered, curiously enough.

10:48And it turns out this is pretty much the best planet for looking for exomoons out there. Exomoons. Exomoons. It is a Jupiter twin. It has the same mass as Jupiter within 1%, the same radius within 5%, has the same equilibrium temperature, it's the same kind of coldness, if you like, as Jupiter. It's in a similar kind of system, a multi-planet system. Everything's just like boom, boom, boom. Everything looks like Jupiter. And Jupiter has a bajillion moons of its own. and so presumably that's the case here. Yeah. Can I ask maybe a dumb question? I just want to emphasize here that you're about to make progress using a telescope that is building on the progress of a previous telescope.

11:24That's right. Yeah. So it's not just people pulling stuff out of nowhere. We are all standing on the shoulders of hardware that came before. Oh yeah. Amazing. I'm at the end of a, you know, this is a 12-year personal journey trying to find these axiomons for me at this point. So we're still waiting. We're hoping this is going to be the one. So this is my question about exomoons. So now when you're looking at the planet, it's pretty easy because you're looking for it to transit the star. Yeah. Now, if that's how you're finding the planet. That's how Kepler found all of its planets. If Kepler found all of its planets.

11:57The transit, the eclipse was in front. Are you looking for the reflection of light off the planet for the moon to transit in front of the planet? Or are you looking for the moon itself to also transit the star Where is the blockage of light that lets you know that this is indeed a moon? Translation, how the hell do you detect it? Short answer is option two. You kind of said it. We look for the shadow of the moon in front of the star. So if the planet, it's a shadow really that blocks out starlight. That gives us this dip in starlight. If there's a moon there, it will either be trailing or behind.

12:31And so we'll see this little extra dip in light. And it's that. So we see two dips. One huge one due to the planet. And then we zoom right in on that data, and hopefully we see a tiny little one due to the moon. Or even multiple, maybe multiple depths, of course. Yeah, but wait a minute. How? Okay, so you're in a cool world's lab, but all you're getting here is a cool shadow. Yeah, right. And I feel like Plato's cave right now. You don't know jack about the object that's making that shadow. No, it's a limited technique. I mean, what we get from this is essentially the size of the object. We can't figure out how far away from its planet it is.

13:07It's some major access. And maybe we could figure out some other things, such as its orbital period, its inclination. So just the bare bones. The bare bones. That's not a world yet to me. No. A world is what's going on on the surface. Yeah. But we will get there. I mean, we're hoping to build telescopes like the Habitable Worlds Observatory, HWO, which might get rebranded one day to something else, perhaps like Carl Sagan Observatory or something. That sounds good. That could be fun. Let me tell you something that's going to get you a lot more play than Habitable Worlds. Habitable world. I don't like the name.

13:39Habitable world. I can barely say habitable, so I don't want that to be a title. But this telescope will take actual photos of plants one day. And so then we really would get a sense of its color, its atmosphere, and maybe even some surface properties. So we'll get there, but it's all baby steps. You know, you can't just jump straight to the end. And you won't be able to see dinosaurs walking on it. No, no. You'd need a telescope even larger than the sun to have any chance of that. Yeah.

14:13I'm Nicholas Costella, and I'm a proud supporter of StarTalk on Patreon. This is StarTalk with Neil deGrasse Tyson.

14:29Well, I'm impressed that we were able to solicit questions on this very bespoke topic. And we got a lot of them. Cool world. I mean, a lot of them. So let's pivot. People like you. People love the cool world. Maybe they could be fans of your YouTube channel, even. There might be one or two, but not. Don't sell yourself short, David. Don't sell yourself short. Okay. Here we go. Hello, Dr. Tyson, Dr. Kippen, Lord Nice. I am Sai from Hakannata, India. Chuck, I thought we can test your pronunciation on names of towns this time. Really? Don't do that. What are these people? What's going on? They're trying to bring you along, Jack.

15:07I know. Trying to help you. My question to Dr. Kipping is, in your studies, you've worked with the concept of occultations. To detect exomoons and planets, could you paint us a picture of how this works? And are these the most important cosmic breadcrums, according to you? There was a famous astronomer, Henry Norris Russell, in 20th century. He once said that eclipses are the royal road to success. Interesting. I love that quote. It just goes to show you how eclipses are like a shortcut. They allow us to see things that's kind of ahead of our technology yet. Like we shouldn't have the ability really to know anything about 5 ,000 exoplanets because we can barely take images of nearby planets.

15:47It's still something we're struggling to do. But using this trick of seeing a planet pass in front of a star, it gives us an extra window. And it only works in some cases. You have to have just the right alignments. You have to be lucky. But when you get that lucky fortuitous alignment, it gives you this unique ability to probe all these extra things like the period, the semi-draxxus, the size of the planet. So it's our first look at these things. Just to be clear, you're only seeing systems that happen to be edge-on to your field of view. Or nearly edge-on. Let me say that in the negative. None of the other systems are going to give you these eclipses, these transit phenomenon.

16:23And so they go undiscussed, unrecognized, uncatalogued. For now. We'll get them one day. Look at that. Well, of course, we can get some of those using other methods. So, for instance, the radial velocity method has also been very successful. Not as successful as transits, but that has discovered hundreds of planets in its run rate. Now you have to tell us what the radial velocity method is. Okay, so this is wobbling stars. So as you see, if you look at a star's light, and you see it being blue-shifted a little bit, then periodically red-shifted, that is telling you it is moving back and forth.

16:50When it's blue-shifted, it's coming towards you, red-shifted away from you. So it's just like the siren of the ambulance going down the street. Oh, what a nice, I like the picture. Yeah, you see, you hear the pitch change. when we hear that pitch change or really see a pitch change in the color of the light of the star, that is telling us that something gravitationally is tugging on that object. And that's how we can infer planets indirectly. So there you don't need the precise alignment. Although if it was completely 90 degrees off, we would see nothing. Because then the star would be doing this, it kind of wobbling in the plane.

17:21And so we wouldn't have any blue shift or red shift to look at. Not coming towards you or away from you. Yeah, exactly. But most of the time we can still get there. I think what we have in our favor, because I did this calculation now 30 years ago. I haven't done it lately, but I don't see why the math would change. Over time. Over time. But if you do this, you are statistically more likely to discover edge-on systems than face-on systems if you do the math on that. David's looking at you like, as your peer, I'm going to have to review that. Let's go to the video game. Let's go to the video game.

17:57Let's go. All right. So what else you got? Another question. All right, here we go. All right, so this is Lisa Cotton. She says, dear Dr. Tyson, David Lord Nice, greetings. This is Lisa from North Hero, Vermont. I'm a fan of both StarTalk and Cool Worlds, and I love watching both shows on YouTube. One thing that I have been pondering lately is the birth of our star, the sun. It seems like a lot of talk happens about when the sun dies. What I would like to know is, was our son born in a star nursery? And if so, would we know which one or be able to predict where it might have been or come from in the Milky Way galaxy?

18:35Thank you so much. And keep up the excellent work. Ooh, we love this. We got good fans out there for this. Yeah, that's a really intriguing question. And it's a question that I know many of my colleagues are thinking very hard about, even at Columbia. So, you know, of course, the sun must have been born, we think, in a stellar nursery. And so there would have been siblings born alongside with us from that giant molecular cloud that collapsed and fragmented and formed all these small stars. We don't know exactly how many, but there's probably many such stars. And the question is, what happened to them?

19:06Over billions of years, the stars will disperse. They'll move into slightly separate directions, and especially because of tidal forces from the galaxy, they'll get kind of pulled apart and could be essentially long-lost siblings at this point, spread across half the galaxy or more. And the sun, given its age and its speed, it's been around the center 20 times. And so if it had a whole family 20 times around given everything you just said that can happen en route, you know, your siblings are long gone. But they should be out there. And so an interesting question is - Guys, when are we getting together?

19:37Yeah, we want to have a reunion. You guys never stay in touch. Give me Zoom, we'll do it next time. A family reunion might be possible, at least in a sense of discovering them by actually looking at the chemistry of those stars. So there is an active effort to measure the detailed chemistry, the abundances of every single element you can think of inside these stars and compare them to that of our sun. And these sibling stars should have not only the same age, of course, but also the same chemistry. So a gas cloud not that far away would still have all these elements, but not in the exact amounts relative to each other.

20:15Yes. That's like a fingerprint. Yes, exactly. So there should be a unique chemical fingerprint. We've got people looking to get the family back together. That's so cool. Get the band back together. I don't know the latest on that, but I know that there are many astronomers who are hunting hard for those. And I think we'll probably hear big news when they're discovered. Let me restate that question, but in another kind of way, because we can't see the birth of the sun, having happened in our past, but we see the birth of other stars. Nobody made a videotape, unlike people who really disturb you by trying to show you theirs.

20:48so how much insight are we getting now that we can see stars being born with their planets how much insight from these other systems do we then bring back to ours there are some startling things we've discovered i mean one thing from direct imaging which actually taking photos of these young planetary systems in the process of forming planets catching in the act right i mean they're very young hundreds of millions of years old or less what's young that's young in cosmic terms One thing that's very startling about these is we see, and I mentioned earlier that Jupiters are rare, but that's in mature systems.

21:19In these young systems, you actually do find lots of Jupiters. And what's strange is that they're really, really far from that star. They're on an order of hundreds of AU. So an AU is the Earth's orbit around the sun. Astronomical unit. Yes, Jupiter is 5 AU, Saturn I think is about 10 AU. So these things are 10 times more than that. They're sort of the distance where we talk about looking for planet nine. Planet nine is being hypothetical planet in the solar system. Really, really far out. And we're discovering Jupiter's very often that far out. And they're very massive. They're actually bordering on brown dwarfs, which are like sort of 10 to 20 times the mass of Jupiter.

21:55And that is a mystery. It's, you know, maybe the solar system then also formed such planets, but they were somehow lost because these things are so far out that they may be tenuously held gravitationally and will be stripped away. And there was an active - They would be, what do we call them? Vagabond planets? Rogue worlds. Rogue worlds. Yes, free-floating planets. Recently, there was discovery of what's called jumbos, which is pretty interesting. These are Jupiter. That's an acronym. Oh, yeah. Jupiter binary mass objects, I think. So these are two Jupiters, and these are free-floating. So not just one Jupiter hanging out in space by itself, but two of them orbiting around each other.

22:36And we can understand how maybe one Jupiter could get kicked out of its solar system. but how the hell do you end up with two bound to each other? And they're right, and they're together. Yeah, that's so weird. We don't understand those. Those are jumbos. The pair is called a jumbo. Recently discovered by JWST in the Orionis Nebula. If they do something stupid, we call it a bimbo. Like that. Ooh, what a great question. Good for you. All right. Look at all these questions you're scrolling through. Oh, I'm telling you, this is like unbelievable. These people, we have great listeners. That's all I can say.