Searching for Alien Worlds with Anjali Tripathi

Could a new telescope one day spot city lights on exoplanets? Neil deGrasse Tyson and comedian Matt Kirshen answer questions about the frontiers of exoplanet science with astrophysicist and NASA Exoplanet Science Ambassador, Anjali Tripathi.

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

• 0:00Neil deGrasse Tyson?

  So Matt, are you Generation Exoplanet?

• 0:02Matt Kirshen?

  I don't know. Am I?

• 0:05Neil deGrasse Tyson?

  Tune in and find out all the latest updates on exoplanets in the cosmos coming up on StarTalk.

• 0:14Neil deGrasse Tyson?

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

• 0:26Neil deGrasse Tyson?

  This is StarTalk. Neil deGrasse Tyson, your personal astrophysicist, I got with me Matt Kirshen. Matt, welcome back to StarTalk.

• 0:35Matt Kirshen?

  Thank you so much. It's nice to be back.

• 0:37Neil deGrasse Tyson?

  You're in New York.

• 0:38Matt Kirshen?

  I am in New York City.

• 0:39Neil deGrasse Tyson?

  You're an LA guy.

• 0:41Matt Kirshen?

  Right now. I've made the trip.

• 0:42Neil deGrasse Tyson?

  So.

• 0:43Matt Kirshen?

  I walked across the country. It took many that we lost. We lost a lot of people. There were we were attacked along the way, but we made it.

• 0:50Neil deGrasse Tyson?

  So we'll find you on mattkirshen.com.

• 0:52Matt Kirshen?

  Yes, please. Yeah. I love. I always love it when StarTalk listeners and viewers come out to see the show.

• 0:57Neil deGrasse Tyson?

  Yeah, excellent. Excellent. So today we're doing a cosmic queries on exoplanets. It's been a while since we dipped into that ocean.

• 1:07Matt Kirshen?

  I love hearing about this because my understanding, and I'm sure both you and our expert will talk significantly more about this. But this is a very new branch of science. This is a we knew almost nothing about this fairly recently in science.

• 1:20Neil deGrasse Tyson?

  That's a that's a true fact.

• 1:22Matt Kirshen?

  Yep.

• 1:22Neil deGrasse Tyson?

  A true fact. And my depths of knowledge of exoplanets stops at just what's the latest number of them.

• 1:30Matt Kirshen?

  It's like one of those sort of charity, how much we've raised ticker just on the thermometer bulb that goes.

• 1:35Neil deGrasse Tyson?

  I'm good for that.

• 1:36Matt Kirshen?

  Yep.

• 1:36Neil deGrasse Tyson?

  So of course we found an expert who works at the Jet Propulsion Lab in Pasadena, California, coming in over video. Unjali Tripathy. Unjali, welcome to StarTalk.

• 1:49Speaker 02

  Thanks, Neil. It's great to see you again and nice to meet you, Matt.

• 1:52Neil deGrasse Tyson?

  Nice to meet you too. So let me get your titles correct here. You're science ambassador. So there's is like a United Nations and things and you you resolve conflicts. Science ambassador for NASA's exoplanet exploration program. If someone gets arrested on another planet, then you step in and help smooth the way. Exactly. You need the ambassadors all over.

• 2:14Speaker 02

  We don't speak about that outside of official facilities. I'm sorry.

• 2:17Neil deGrasse Tyson?

  She's so diplomatic.

• 2:18Speaker 02

  I will say the last time I was in the city was to be at the UN last year, Neil, so.

• 2:23Neil deGrasse Tyson?

  Wow, love it. Also a science communicator, and if someone is labeled that in NASA, since so many people at NASA are really good at science communicating, if someone actually has that designation, that's we're talking real. So we have high expectations of you for this conversation.

• 2:41Speaker 02

  No pressure, no pressure.

• 2:44Neil deGrasse Tyson?

  And I'd love this the most, a former White House fellow. And this would have been a science fellow, is that correct?

• 2:49Speaker 02

  Uh, it was everything. So I was the only scientist in my cohort. There were 16 of us. The others, one of them's a one-star general, one's one of the first congresspeople who's Native American. So all stripes.

• 3:02Neil deGrasse Tyson?

  If I remember correctly, these fellows are represent all different ways you could advise the president that the president might not otherwise know natively. Is that is that a correct way to think about this?

• 3:13Speaker 02

  It's usually one advisor per cabinet agency. So I took on the Agriculture Department and the Science and Technology Policy Office of the White House. And that was back about eight years ago.

• 3:24Neil deGrasse Tyson?

  I love it. So can you update us on exoplanets? There's been so many other things in the news. Meanwhile, you and your research cohort domestically and around the world have been busy at this activity, finding exoplanets, studying them further. So could you just catch us up? What should we be thinking about today?

• 3:46Speaker 02

  Yeah, the last time I was on the show, Neil, was a couple of years ago and we were still, you know, fresh off of being at about 5,000 exoplanets. And as of today, you know, Matt, you were asking, we're at 5,921. So within about a month, probably by the time this airs even, we'll be at 6,000 in flashing lights, which is pretty cool. And, you know, when you think about the fact that when I was born, I think when everybody on screen was born, we didn't know about any of those. That's a pretty big deal. But it's just going and going because within a couple of years, once we've got the Nancy Grace Roman Space Telescope up, taking observations from space, we're going to get tens of thousands of exoplanets counting. So then 6,000 will just be a drop in the bucket.

• 4:30Neil deGrasse Tyson?

  So remind us who Nancy Grace Roman is? Was she the first NASA chief scientist? Is that right?

• 4:36Speaker 02

  She was the first chief of astronomy in the Office of Space Science at NASA. And she, you know, some people call her the mother of Hubble, right? She helped architect some of these big missions. And so we're really delighted to have this next flagship named after her.

• 4:50Matt Kirshen?

  And just to be clear, she's not going to be up there operating the telescope?

• 4:54Speaker 02

  I couldn't, I couldn't tell you that, but that's not currently the plan. We've got some redundancy if she's not up there doing anything.

• 5:01Matt Kirshen?

  I mean, they think of everything at JPL.

• 5:03Neil deGrasse Tyson?

  Or her spirit energy will be there controlling it. So the general habit is to name telescopes after dead people, just so you know. Yeah, so she's not, there's one exception to that, but all the rest, that's been the case.

• 5:17Matt Kirshen?

  Ah, so she, so she'd be no use up there right now?

• 5:19Neil deGrasse Tyson?

  That's correct. Totally no use. So, and also, give us a reminder of what it means for a telescope in orbit to be a flagship mission.

• 5:28Speaker 02

  So at NASA, we have lots of telescopes of different sizes and lots of satellites. We've got things down to CubeSats that, you know, universities can build up to these things that cost billions of dollars. And so this flagship observatory is going to do lots of great science for dark energy and dark matter. It's going to map all of the structure that we can see in detail so we can understand all kinds of cosmological questions. All sorts of queries are going to be answered there, but I'm really excited that. It's not only going to, as it's staring at all of the mass out there, look for tiny changes in light that can tell us about thousands of planets using micro lensing, right? How gravity is distorting light. But then it's also got this whole tech demonstration,

• 6:11Speaker 02

  a chronographic instrument that can actually block out light so that you can see things that are about 10 million times fainter than the stars that you're looking at. So this flagship means that it can do all kinds of science. It's not just focused on one specific question.

• 6:26Neil deGrasse Tyson?

  And it probably sounds like flagship is also defined by price. Like, the expensive telescopes would be flagship.

• 6:34Speaker 02

  I mean, they're the things that we're most proud of.

• 6:38Matt Kirshen?

  Not that you play favorites, but this is your most special child.

• 6:42Speaker 02

  Neil is everyone's personal astrophysicist here at NASA's Exoplanet Exploration Program Office. We are the nation's, you know, exoplanet purveyors, so.

• 6:51Neil deGrasse Tyson?

  We'll take it. We're good. I'm good with that. So you mentioned this, this coronographic capability. So right now, we don't actually look at planets, exoplanets. We're looking at their effect on the host star. So you're going to be able to directly image exoplanets with this telescope. Is that correct?

• 7:12Speaker 02

  That's going to be how we're going to see some of them. Right now, you can get a handful of these with the James Webb Space Telescope. We've also directly imaged some planets from the ground with really big telescopes, like the Keck telescopes in Hawaii. But this is going to be the first time that we actually fly a demonstration that can get us down to these fainter things because, you know, something big like Jupiter is a lot easier to see than Earth. And so we're going to push on that a little bit, getting ready for some of our future flagship missions.

• 7:40Neil deGrasse Tyson?

  So our catalog is overrepresented by Jupiter's, would you say?

• 7:43Speaker 02

  Those have been easier to find with some of these early techniques. But, you know, we actually find a lot of different types of exoplanets that are also smaller. So it's quite the range.

• 7:55Neil deGrasse Tyson?

  Okay, very good. So tell me also about the Habitable Worlds Observatory.

• 8:00Speaker 02

  Yeah, so this is one of these missions that we're really excited to be working on. So the idea is that we now know that there are so many exoplanets out there that we think there should be enough nearby around stars that you could just go out and look and take a picture of them. And what you really want to do is not just take a picture of an exoplanet, but you really want to get a sense of what's in its atmosphere. So hopefully you can actually take a picture using ultraviolet, infrared, visible light, and this whole wavelength range to get spectra and look for biosignatures.

• 8:33Neil deGrasse Tyson?

  So biosignatures, like on Earth, that would be oxygen, I guess, right?

• 8:37Speaker 02

  Right now, that would be oxygen, but it's funny because if you look at Earth's past, the biosignatures actually change over time. So way in the past, you know, when we were four billion years ago, up until about two and a half billion years ago, if you had looked at Earth's atmosphere, you would have mainly seen methane. And that was the metabolism of the earliest organisms. But then over time, oxygen built up, and then when you went into the Proterozoic, you would actually get from then two and a half to about 500 million years ago, you would actually see lots of ozone as the thing to look for in the atmosphere. And it's only when you get to the modern era, then you get the oxygen, all of this coming from photosynthesis and signs of life.

• 9:17Neil deGrasse Tyson?

  Okay.

• 9:17Speaker 02

  Three planets, one.

• 9:19Neil deGrasse Tyson?

  And you don't know when in the planet's evolution you're peeking in upon it.

• 9:25Speaker 02

  Exactly. So you want to design a telescope that can cover all of those possibilities because we want to be sure that we're looking for life in as many options as we can.

• 9:33Matt Kirshen?

  Even presumably, you don't know that it would evolve in similar ways and produce similar gases.

• 9:38Neil deGrasse Tyson?

  Of course, right. It could go a whole other direction. Might there be chemical signatures that could be signatures of life as we don't know it, and therefore you're not looking for it?

• 9:49Speaker 02

  You know, there's all kinds of things that if they produce life, we might miss it because we don't know how to look for things that aren't familiar to us. But there are lots of interesting signatures of life that we can look for that go beyond oxygen and ozone and methane, right? You can look for nitrogen dioxide, which is an industrial pollutant. You can look for some of these other, you know, like looking for what's in your hairspray. All kinds of things out there to look for for life. Like, you know it.

• 10:18Neil deGrasse Tyson?

  The chlorofluorocarbons in the hairspray?

• 10:19Speaker 02

  Exactly.

• 10:20Neil deGrasse Tyson?

  Is that still in the hairspray? Do they still do that? I thought they took it out.

• 10:23Speaker 02

  I don't know, but.

• 10:24Neil deGrasse Tyson?

  Yeah. But what you're saying is you could look for

• 10:27Matt Kirshen?

  Yeah.

• 10:27Neil deGrasse Tyson?

  Alien pollution. That's what you're telling me.

• 10:29Matt Kirshen?

  We we're looking for aliens that have flyaway hair that needs controlling. Like, if they have unmanageable hair and or toilets that need

• 10:39Neil deGrasse Tyson?

  I don't think I've

• 10:39Matt Kirshen?

  They're a little on the smelly side.

• 10:41Neil deGrasse Tyson?

  I've never seen an alien in a movie that had hair.

• 10:44Matt Kirshen?

  Yeah.

• 10:44Neil deGrasse Tyson?

  They're always bald.

• 10:45Matt Kirshen?

  Let alone just having bad hair. They never seem to have bad hair days. They must. Some bad tentacle days. I don't know what.

• 10:50Neil deGrasse Tyson?

  Bad tentacles.

• 10:51Matt Kirshen?

  But they sometimes need controlling and sometimes the things they use to control them have damaging effects on their atmosphere.

• 10:58Speaker 02

  That would be great for us to see, right? Because we want to see those signs of pollution of hairspray. I mean, even looking for the satellites that they've got going around their planets or, you know, looking for their city lights at night. All of those are things that we could hope to look for with this telescope and to look for signs of life. So it's not just the oxygen.

• 11:17Neil deGrasse Tyson?

  Are you also looking in binary star systems where the planet orbit might be a little unstable?

• 11:25Speaker 02

  So we'll look at some binary star systems. But so one of the tricks, though, about the habitable worlds observatory is to find something actually like Earth. It's actually got to look at something that's 10 billion times fainter than the star, right? So this is like a bird flying near the sun. So if you're trying to look at Icarus, right, before bad things happen, it's kind of hard. You'll need some sunglasses. And so this telescope will also have a coronagraph instrument or a high contrast instrument that'll be able to dim that down. And so once you can actually do that, then it becomes possible to look for planets like Earth and to see all of the sort of variations in what might be there.

• 12:06Neil deGrasse Tyson?

  So tell me about the formation of exoplanets. So in my day, in my professional days, I remembered the very first Images of a protoplanetary disk where it's a disk of gas around a star that hasn't made a planet yet. And is that big time industry now within your community?

• 12:28Speaker 02

  So I'm very biased, Neil. You know, my PhD thesis was on protoplanetary disks, except back, you know, 10 years ago or so, when I did this, you were basically looking at blobs. It was the science of blobology. And we've come a long way since then because now you can actually use radio telescopes like the Alma Telescope in Chile to look at, you know, these radio wavelengths of the dust and these beautiful spiral structures. You can see gaps and rings. There's a lot of beautiful science that's coming out of it. So I don't know if it's as big time as looking for alien life, but it's something that's definitely advancing quickly. And I just love talking about disks because everyone gets really excited about planets. But I think that in the same way that you

• 13:12Speaker 02

  think like, oh, yeah, I'm going to be an astronaut, I'm going to go to space and I can see a beautiful picture of Earth. We'll see these beautiful pictures of Earth. But, you know, you might want the 23 and me of the astronomy world of, you know, where did we come from? What else is out there? And you can get all that information from disks because if you look at a protoplanetary disk, all of that material goes into forming planets. It's, you know, leftover from forming a star when the gas and dust collapse. And, you know, most of it goes into the star, but, you know, about 1% or so goes into forming planets. And then long after that gas has dissipated and you formed your planets, you have some leftover material, right? In the solar system, we have the zodiacal dust where the planets are. And then further out, we've got the Kuiper Belt, which we know

• 13:53Speaker 02

  is your favorite for giving Pluto a hard time there, Neil. So.

• 13:59Neil deGrasse Tyson?

  And one other thing about the disks, it was only 1% goes into planets. Where does the rest of the gas go?

• 14:05Speaker 02

  So, most of the mass, right, from that gas cloud is going into forming the star, right? And then you've got a lot going into forming the planets. So, a lot of this is going to dissipate in time, right? The star has UV radiation that's going to interact with the material there. Some of it's going to blow away.

• 14:23Neil deGrasse Tyson?

  Oh, wait, so maybe I misunderstood. So the 1% number you gave. Is that 1% of the disk mass or 1% of the the cloud, the total cloud mass, the protocloud?

• 14:34Speaker 02

  Right, okay, sorry. So I conflated two things there. So of the protostellar nebula, you have about 95% of that mass goes into the star and the rest goes into the disk. And of what's in the disk, about 1% is solid material, right? So it's the little dust and grains and the other 99% is gas.

• 14:55Neil deGrasse Tyson?

  Got it, got it.

• 14:56Speaker 02

  And so you've got these couple stages of disks. You've got that protoplanetary disk early on. And later on, after that gas goes away, you're left with the planets. You have things fighting each other and colliding. And that's what gives you debris disks like the Kuiper Belt and the Zodiakolite here in the solar system.

• 15:24Speaker 03

  This is Ken the Nerd Neck Zabera from Michigan and I support StarTalk on Patreon. This is StarTalk Radio with Neil deGrasse Tyson.

• 15:40Neil deGrasse Tyson?

  So now, update me on the latest from JWST because that's been going like gangbusters.

• 15:45Speaker 02

  It's so cool what we can finally see from space. So they were actually able to use the near-infrared superpowers of JWST to actually see water ice and crystalline form in this debris disk around a star called HD 181327. And this is really exciting that you can actually see water ice in a debris disk. Because in the Kuiper Belt, we've got all of these dirty snowballs, right? We've got the comets, all kinds of icy material. And there's been hints of this from the ground before, but we've never actually been able to see it. So when they took a look at the lights scattering off of this disk and compared it to what we see in the Kuiper Belt, it looked pretty similar. You've got these dirty snowballs.

• 16:26Speaker 02

  And so what this tells us is that Kuiper Belts are not just something that we only see in the solar system. They might be kind of common.

• 16:33Neil deGrasse Tyson?

  So you found a Kuiper Belt in an exoplanetary system?

• 16:36Speaker 02

  Exactly.

• 16:37Neil deGrasse Tyson?

  Very cool. All right, that's with JWST.

• 16:40Speaker 02

  That's right. And so it means that there's all kinds of icy material out there just waiting to form planets. So water might be more common in the early solar system.

• 16:49Matt Kirshen?

  So that somewhere out there, there's another Neil deGrasse Tyson dismissing another Pluto.

• 16:54Neil deGrasse Tyson?

  Because there's a Kuiper belt waiting for that to happen in there. No, I'm not. I was an accessory to the demotion. I was not. I didn't pull the trigger on that. So this is fundamentally a Cosmic Queries edition.

• 17:06Matt Kirshen?

  It is.

• 17:06Neil deGrasse Tyson?

  And we solicited questions from our Patreon fanbase.

• 17:09Matt Kirshen?

  They've sent in a fantastic assortment of questions.

• 17:11Neil deGrasse Tyson?

  On this subject. Well, let's bring it on. Go.

• 17:14Matt Kirshen?

  Well, I always like to start with, I think it's always fun when there is a young fan. So Hugo Dart from Rio de Janeiro says, with my seven-year-old daughter Olivia, who is also a big fan of StarTalk, here is our question. What do you find most surprising or humbling about the current state of knowledge of exoplanets compared to when you first entered the field?

• 17:34Neil deGrasse Tyson?

  Hmm, good one.

• 17:35Speaker 02

  Obviously, there's so many more exoplanets now than when I started, you know, 20 years ago. But I think what's really humbling is the fact that we keep finding new worlds in places where we've looked, we thought, oh, we've already found what's there. But then you find another one. For example, James Webb's recently found some planets in a system where they're puffy planets. This is Kepler 51. And suddenly they said, oh, there's one more that we missed. You know, the Kepler spacecraft was up a while ago, and we're still analyzing that data and finding new information. And the fact that we can find worlds that are so different from our own, right? There are these ocean worlds, there are these lava worlds. It's all just so spectacular that it's really exciting, but also kind

• 18:17Speaker 02

  of humbling to find that diversity of planets. It's like a zoo.

• 18:21Neil deGrasse Tyson?

  Did you not expect that diversity?

• 18:23Speaker 02

  I think for so long, we assumed everything looked like the solar system and Earth, right? Because it was all we knew. And in the solar system, we don't have worlds covered in lava. So the fact that that can be out there, that's great.

• 18:36Matt Kirshen?

  Well, while we're talking about different types of worlds and things that look different, Adrian Martinez from Houston says, my question is, is it possible for a planet to naturally form in a doughnut shape, like a Taurus? And if not, what are the weirdest or most unusual planet shapes we've discovered in the universe so far? Do we even, do we even know, do we even know the shapes of a lot of these planets? Because a lot of the time, you're just going on mass, aren't you? Or can you see a shape even? I don't know.

• 19:00Speaker 02

  So that's a good question, Adrian. I don't think it's possible to form a donut planet. You know, Neil, correct me if I'm wrong, but that seems hard with gravity concentrating everything. And you know, the easiest shape to be is round because it pulls everything in, nice and tight.

• 19:14Neil deGrasse Tyson?

  Yeah, I wrote an essay back when we opened the Rose Center for Earth and Space because in the middle of this facility is a round thing. Okay, there's a sphere. So I wrote an essay called "On Being Round", and it was all about how nature just wants to make things round. And when it's not round, there's a really interesting reason why it's not round. But I don't think we ever get anything a donut, because the gravity wants to put it all in one place.

• 19:41Matt Kirshen?

  And wants to put it in the middle.

• 19:42Neil deGrasse Tyson?

  In the middle, exactly.

• 19:44Speaker 02

  I was just gonna say, though, there is, though, a really cool planet called Wasp 12b, though, that's sort of egg-shaped, right? So I think that's pretty cool because it's really hot, it goes around its star almost, you know, once a day. And because it's so hot, it's actually tidally locked and it's getting stretched. So not only do you have this planet that's like an egg, it's not perfectly spherical anymore, but it's actually giving off mass. And so we often find that planets can actually disintegrate a little bit and leave a torus of material from where they were. So you don't get a torus-shaped planet, but you have the leftovers in a torus, which is pretty cool.

• 20:20Neil deGrasse Tyson?

  And what about the, was it a comet or an asteroid that looked like it was two spherical pieces stuck together? It looked like a dumbbell, like there were two. So you can get that, but it didn't form that way.

• 20:33Matt Kirshen?

  So it formed as two round things and then it sort of, they kind of met.

• 20:36Neil deGrasse Tyson?

  I think that's the understanding of it.

• 20:38Speaker 02

  Well, so you can get all kinds of weird shapes in asteroids and these smaller bodies because it's one that you get up to being a planet when you have so much mass, then you're becoming round and forced to sort of circularize.

• 20:50Matt Kirshen?

  Oh, because the smaller things have less mass?

• 20:52Neil deGrasse Tyson?

  Yeah, they have less mass and gravity.

• 20:54Matt Kirshen?

  Right.

• 20:54Neil deGrasse Tyson?

  And so the rocks win. Whatever the rock is doing, it stays that way.

• 21:00Matt Kirshen?

  Well, I've got a couple of, there's a couple of questions here about habitability that I, I like to combine questions sometimes if they're on similar topics. So William Warren from Abingdon, Maryland says, what exactly defines a planet as potentially habitable? Is it just being in the habitable zone where liquid water could exist? Or should we consider atmospheric composition, magnetic fields, plate tectonics and more? Love it. And then also Sean Browning from Hood River, Oregon. When our star inevitably expands and consumes the inner solar system, what effects would that have on the remaining planets and what planets would fall into the new habitable zone? Ooh. Or would the expansion of the sun change the remaining planets' orbits? Or would the mass not change, therefore leaving the planets in their current orbit? So what makes a planet habitable and how will that change as the sun starts to I love it. swallow our worlds?

• 21:45Speaker 02

  No, that's such a good question. I mean, right now, we use the term habitable zone, but really that should, you know, the long, you know, the asterisk, read the fine print should really be region around a star where liquid water may be possible and seen on the surface. So just because a planet is in the habitable zone, that just means it's the right distance from the star where liquid water could hopefully persist on the surface. So sometimes people talk about the distance from Venus to Mars because, you know, in the past, these looked different. But people use different definitions and part of how we think about habitability on a planet is involving liquid water, right? Because that's what we know life on Earth uses today. But there's so many other factors, right? So you need water, you need energy.

• 22:30Speaker 02

  So starlight, all that UV radiation is good stuff, right? Makes the crops grow, but too much and that's a problem. So if you've got, you know, the stellar wind and all kinds of stellar flares from your star coming and beating down on you, that's bad news. So you want just the right amount of energy and then you of course need nutrients to make everything happen. So I think there were some questions in there about, you know, what happens as our star changes, right? And our relationship with our world is not the same. And I think You know, where the habitable zone is in the solar system today is not where it was in the past, and it's not where it'll be in the future, because it used to be a little closer

• 23:10Speaker 02

  into the sun. That's why Venus used to be wetter than it is today. You had more earth-like conditions, and then, of course, you had this runaway greenhouse effect, and now it looks kind of hellish. And so in the future, we expect as the sun gets brighter and expands out, Mercury and Venus are actually going to be sucked into it and eaten up. But we should be okay. But out by Saturn is going to look pretty good for habitability. So maybe Titan, you know, the moon around Saturn, could have a good day, because it's got a lot of methane in its atmosphere, kind of like early Earth.

• 23:44Neil deGrasse Tyson?

  I heard this, and I didn't believe it until I did the calculation, that when the sun becomes a red giant, and Earth is long gone, so is Mercury and Venus, and Mars becomes uninhabitable, as a hot zone, Pluto becomes a habitable place.

• 24:01Matt Kirshen?

  Right.

• 24:01Neil deGrasse Tyson?

  I heard this. And I double-checked it, and it checks out.

• 24:04Matt Kirshen?

  The number's crunched correctly.

• 24:07Neil deGrasse Tyson?

  It crunched correctly, to make Pluto a place where we might all have to escape to survive. There'll probably be a picture of me at the immigration.

• 24:15Matt Kirshen?

  No, it's just, you get taken into the second room.

• 24:18Speaker 02

  Aren't you going to be reconsidering your life choices at that point?

• 24:24Matt Kirshen?

  We've found some things you've said, and we'd like to ask you some more questions. Speaking of more questions, Ben Grund from Detroit, Michigan, says, "I hear it's sometimes said that our solar system is pretty atypical in its constituency. Is every solar system a snowflake, or are there some common themes to their layouts?"

• 24:42Neil deGrasse Tyson?

  Well, I like that.

• 24:43Speaker 02

  Well, I mean, you were just talking about the debris disk with water ice. So we do have some snowflakes out there in other systems, quite literally. But I think the thing that we originally thought was that everything was like the solar system. And then we found always these big planets like Jupiter, close into their star, hot Jupiters, because they were easy to find. We discovered that actually they're nothing like the solar system. But over time, we're finding more elements that are pretty similar. So I think that we can say that we are not, you know, totally unique, but totally dissimilar. So I like the snowflake analogy, because I actually think that there's enough similarities and differences for it to work for us. Also, people just tell me I'm a special snowflake.

• 25:26Speaker 02

  I love the fact that you have exoplanets discovered all over the world, right? It's not just telescopes in one place. And say you have WASP, right? This Wide Angle Search for Planets that found exoplanets in its early days. And then they've souped up versions. There's SuperWASP now. So I think there's even a SuperWASP telescope in South Africa. They're all over the place. And this is just one of many. Many of them have awesome names, by the way, right? There's the Trappist ones that come out of Belgium that are making these great discoveries. And then we can keep studying them, both from the ground and in space.

• 26:01Matt Kirshen?

  God, scientists love a contrite acronym. Nothing makes scientists happier than finding some acronym.

• 26:08Neil deGrasse Tyson?

  When I was in college, there was some computer scientists, this is early days, before that was even a title. There was some program we were all using and its acronym was MAGIC. Okay, what does that stand for? It says, "Neutronics are generally idiotic constructions." So ever since then, I have not overdone my mnemonics. So what else you got?

• 26:33Matt Kirshen?

  All right. So Ryan Guerance from Pittsburgh, Pennsylvania, says, "There are many different types of telescopes with a variety of sizes, but none of them have the resolution to actually see exoplanets." So my question is, how big would a telescope have to be to have the resolution to actually see a nearby exoplanet? Could we align multiple telescopes on Earth to make a telescope effectively as large as one of our planet's hemispheres? And would that even be big enough?

• 26:57Neil deGrasse Tyson?

  I'm betting, because we do have images of planets, I think this questioner wants to see continents and oceans and cities. What do you think?

• 27:07Speaker 02

  I mean, because I'm right there with you, Neil, that we've seen exoplanets already, right? Again, they don't look like Earth so far. We just got a couple of pixels, although, you know, as Carl Sagan's famous marker of the pale blue dot from Voyager 1 spacecraft, and it's, you know, out at the edge of the solar system, looking back at Earth, you just see a pale blue dot. So we're not yet at the level of continents and oceans. But actually, one really cool thing about the Habitable Worlds Observatory, you might actually be able to get a sense of oceans because of how the light... You would have the glint coming off of the water. So to get to the stage of continence is pretty far off. I haven't done the math on what you would mean to do that. It seems hard, but certainly we can take pictures of exoplanets now from the ground

• 27:50Speaker 02

  and that are big like Jupiter and again with HWO in the future, we'll be able to see the planet itself without that level of detail.

• 27:59Neil deGrasse Tyson?

  So not to diss Pluto even more,

• 28:01Matt Kirshen?

  Mm-hmm.

• 28:02Neil deGrasse Tyson?

  but when you described this pale blue dot image taken by the Voyager 1, prompted by the efforts of Carl Sagan when Voyager 1 exited the solar system. That picture was taken when Voyager 1 passed Neptune.

• 28:15Speaker 02

  Mm-hmm.

• 28:16Neil deGrasse Tyson?

  That's the edge of the solar system.

• 28:18Matt Kirshen?

  Wow.

• 28:21Neil deGrasse Tyson?

  It was well inside of the orbit of Pluto.

• 28:23Matt Kirshen?

  Yeah.

• 28:24Neil deGrasse Tyson?

  So the idea was aliens would come upon our solar system and they'd see the first planet and that would be Neptune.

• 28:31Matt Kirshen?

  Mm-hmm.

• 28:32Neil deGrasse Tyson?

  And that's when they take a picture of all in inside. So I didn't want people to think the edge of the solar that they were way out there.

• 28:39Speaker 02

  No, it was relatively nearby, right?

• 28:41Neil deGrasse Tyson?

  Yeah, relatively nearby, exactly.

• 28:43Speaker 02

  We saw a picture of the family portrait, right? It was taken on Valentine's Day in 1990, right? It's showing the love, right? The love of a couple of pixels here and there.

• 28:51Neil deGrasse Tyson?

  Yeah, yeah. I have time for a few more, I think.

• 28:54Matt Kirshen?

  Yeah, absolutely. So Jay Starks from Waco, Texas says, "Here and reporting for cosmic query duty. I've been thinking a lot about how planets in our solar system are impacted differently by the distance from the sun, such as temperatures and the number of days it takes each planet to orbit our Helios. Do all exoplanets follow this pattern with their stars too regarding distance? I'm curious if this is a universal truth for all exoplanets in outer space."

• 29:20Neil deGrasse Tyson?

  Interesting. I think he's asking, are the laws of physics that describe orbits, does it change from one planetary system to another?

• 29:28Speaker 02

  I mean, the beautiful thing about physics is you don't have to have a great memory. The same rules apply over and over again. You just have to learn it once. But I think it's kind of interesting to think about the solar system because you know Bodhi's law, right? Neil, right? How back in the day when people were looking for, you know, Uranus and Neptune and things, they would look at the distance from the star, from the sun, and say like, "Oh, there's a planet at these geometric distances." And so then they found the planet and they went, "Yep, that checks off." And then they said, "Oh yeah, we found Ceres." Because back then, Ceres dwarf planet was viewed as a planet. And then they said, "Oh yeah, there's these other things," and then it didn't quite work. And so we stopped. But the notion of, "Ah, distances from the star having planets" is one that people have thought a lot about over history.

• 30:12Speaker 02

  And I think it's actually pretty cool that when we look out at these exoplanet systems, what we see looks nothing like the Earth and the solar system, and that's partly because they're different systems. But also even with our own solar system, everything moved around. You know, Jupiter and Earth didn't just form exactly where they are today. They did a little dance to get there.

• 30:32Neil deGrasse Tyson?

  The planet migration.

• 30:34Speaker 02

  Yeah.

• 30:34Neil deGrasse Tyson?

  What's going on there? Yeah. So I'm reminded that when Isaac Newton first wrote down his gravity equation, and it worked for Earth and the moon, and worked for the sun and Earth, it also worked for Jupiter and its moons. So it wasn't just like a sun thing. It was, "Oh my gosh." And so that we correctly, though audaciously, said it's a universal law of gravitation. That's kind of bold, but, I mean, why not? We're egocentric as humans, right?

• 31:07Matt Kirshen?

  While we're talking about moons, there's a moon question from Fred Dog. That's patron Fred Dog. I don't know if you're from the Westchester Fred Dogs, any relation? But Fred Dog says...

• 31:20Matt Kirshen?

  "It was once thought that habitable worlds had to exist within the habitable zone and would require a magnetic field to protect itself from harmful solar wind particles. However, this has since been determined to not necessarily be the case as our understanding of habitability continues to grow. Now moons like Enceladus and Europa have become candidates for housing possible life, but fortunately, they also happen to be protected by the magnetospheres of their respective planets." My question, how has the inclusion of moons further complicated the search for life beyond our solar system?

• 31:50Neil deGrasse Tyson?

  I love that. And I'm going to add to it. Will there come a day where we just abandon this concept of habitable zone? Because if the conditions are ripe somewhere else and it's not in the zone, it could have life. So maybe the habitable zone concept is constricting our creative thoughts of how, when, and where we might find life.

• 32:13Speaker 02

  Yeah, so I mean, it's great that Fred Doug mentions these moons, right? Europa and Cetus, where you might have this thick layer of ice and you've got all this heating that makes a nice cozy ocean underneath. So one of the things about the habitable zone, like I said, that fine print, long liquid water maybe found on the surface here, right? If there is life under the ice, you won't be able to see it from the atmosphere as we know of now, right? So when we talk about the habitable zone, it's about where could we actually look at our telescope and say, maybe there's a biosignature for a life here? So it's not saying that moons are out of the question. People are definitely looking at moons. I think David Kipping, who you frequently have on this show here down the street there in New York, he's always thinking about exo-moons.

• 32:55Neil deGrasse Tyson?

  He's up the street. He's up the street.

• 32:58Speaker 02

  Excuse me, am I

• 33:00Matt Kirshen?

  No, he's very specific about directions.

• 33:02Neil deGrasse Tyson?

  Yeah, yeah, get my New York straight here. No, yeah, he's up at Columbia and we're delighted when he's on the program.

• 33:08Speaker 02

  So, you know, I don't know if we can detect the signatures of life from a moon yet, but it's one of the things that we want to look for. And actually, the question of, does it complicate things? Yes, because if you want to get the signature of a moon, now you have to get rid of all the information about the planet. You can't just say, oh, I'm only seeing the moon there. In the same way that when we study exoplanets, we have to get rid of the star to study the planet. So there's a different level of complexity. And to your point, Neil, of maybe it's time for a new definition. I think it's just, you know, you need something without the asterisk and the fine print of, you know, liquid water on the surface here.

• 33:43Neil deGrasse Tyson?

  And let me tell you how old I am. So when I was in graduate school, the Voyager mission was doing its grand tour and everyone was in high anticipation of what it would discover about the planets. And when it started imaging the planet moons, oh my gosh, the moons became more interesting than the planets themselves. And now people don't care about the planets. Jupiter's moons are way more interesting than Jupiter, by far. I don't know, I'm speaking out of turn here. Tell me, you gotta agree with at least some of that sentiment here.

• 34:18Speaker 02

  I think that moons are spectacular, right? I mean, I think the fact that, you know, you can look around Saturn and see hundreds of moons, and they all, you know, you've got ones that look like the Death Star, right?

• 34:28Neil deGrasse Tyson?

  Yes, it's got this big crater in it. It looks like the Death Star bit that would send out the ray. Yeah, it's, don't you guys call it the Death Star Moon?

• 34:37Speaker 02

  I think we normally call it Mimas, but, you know,

• 34:41Speaker 02

  we can have different names, sure.

• 34:43Matt Kirshen?

  For when no one's listening, when, behind closed doors, when you're just a few pints.

• 34:48Speaker 02

  Exactly, so there's all kinds of beautiful things there. But I wouldn't count, you know, how awesome Jupiter and Saturn and the solar system planets are, because there are things we don't understand, like, why does Saturn have a hexagon at its pole? And, you know, why do all of these outer planets have rings, right? Saturn gets all the credit for, you know, the hula hoops that shine. But, you know, all of these giant planets do, Neptune, Uranus. So, I think there's a lot going on there, and I can't wait to see this for other systems.

• 35:37Matt Kirshen?

  There's a nice question here from Andy L., who lives just up the road from Anjali and me, in Thousand Oaks, California. "My understanding of the two main exoplanet search methods, periodic stellar dimming and stellar Doppler wobble, is that they both rely on their star's ecliptic being in line with our line of sight. Does this mean that if a distant star's ecliptic plane is angled off our sightline, neither of these methods would work? Could that explain why some stars don't seem to have planets?"

• 36:08Neil deGrasse Tyson?

  Don't our people ask good questions?

• 36:10Speaker 02

  Your people ask great questions, Neil. I mean, and that's one of the best parts of getting to hang out with all of you is it's just the most fun. You know, people say like, ah, it's a secret. I don't want to tell anyone. I want everyone to know how cool exoplanets are.

• 36:23Neil deGrasse Tyson?

  Oh, yeah.

• 36:24Speaker 02

  And answers to the questions. Like, once we find life, you know, you were joking earlier, Matt, like, I can't tell anybody in my ambassador role, but no, I want everybody to know, you know? Call your senators, call everybody, tell them it's amazing. We have two methods for finding exoplanets that Andy L. mentions, and it's exactly right that the transit method, right, where the planet is lined up just right to block out the starlight every time it goes around, you do need that geometry to be pretty close to at an angle. We call this sort of edge on. If it was so-called face on, 90 degrees off, you wouldn't actually be able to see that starlight getting blocked. And in the same way, the radial velocity or

• 37:04Speaker 02

  Doppler wobble method is where the mass of the planet tugs on the star and we go back and forth. And this only works, of course, if that star is moving back and forth from the telescope. So both of these don't work if it's at exactly 90 degrees or face on, as we call it. But if it's even a little bit off, we can actually see components there. And this actually tells us some interesting facts about the mass of a planet, because there's a famous system that was early on detected as a possible planet in the early days of exoplanets. And it turned out that they had that angle totally wrong. Later, when they had astrometry, where they were actually able to look at the positions of

• 37:47Speaker 02

  the planets, then, and look at the position, sorry, of the stars, they could see it was actually the other way around. And this was actually a brown dwarf, actually even a little bit bigger than that. So the angle matters, but we can get there as long as it's not exactly 90 degrees.

• 38:04Neil deGrasse Tyson?

  And there's another piece of this where we know the statistics. If these systems are randomly oriented to our field of view, then we will know precisely how many systems we're missing. So I think just because you don't see a planet because it's tipped out of the field of view, we have a way of Arithmetically compensating for that. So, in fact, we have this number of planets in our catalog. But again, like Andy L. said, if it's not lined up, we don't see a planet, even if there is a planet there. So statistically, presumably, we know this, and we can scale up the number of planets we detect as if we would have seen all planets around all stars.

• 38:48Neil deGrasse Tyson?

  So do you have a latest planet count for that?

• 38:52Speaker 02

  I don't have the exact numbers, Neil, but I'm totally on the same page as you and Andy L. That just because we don't see it today doesn't mean that there couldn't be planets in the system. And that's actually one of the really cool things that the Roman Space Telescope is going to do. Because it's going to be finding planets through microlensing, it doesn't care about the geometry, right? So it can actually look for planets that are farther away than what we do with the transit where it's nearby and we have to see it regularly. And so we expect we're going to see planets and systems where we thought, oh, didn't see that there? But okay, I guess I could have seen that cut in.

• 39:26Matt Kirshen?

  Just to be clear, was what you were saying a second ago, Neil? You can sort of just assume that planet's orbital plane is evenly distributed in all angles. So you can go like, we can see these angles and these angles. So you can then calculate, well, these ones must also exist.

• 39:40Neil deGrasse Tyson?

  Exactly. You extrapolate. You extrapolate into the galaxies that don't, where you didn't see any planets at all. Once you know what fraction of stars have planets that you've detected, and there's all these other planets that don't, then you just look at the statistics of the orientations. And you can fill in those missing numbers, if it's randomly distributed out there.

• 40:00Matt Kirshen?

  While we're talking about that kind of detection and validation of things that are distant away, Alan G. says, "Hello, great and mystic diviners of the cosmos." How accurate do we believe these remote measurements and determination of atmospheres and life conditions are when we have no way of validating something 50,000 light years away?

• 40:18Neil deGrasse Tyson?

  Oh, those are fighting words. Mm-hmm. No way of validating. Show your work. What was he, wanna go there and, and, and get a beaker of sample? Like, no.

• 40:29Speaker 02

  Question though, right?

• 40:31Neil deGrasse Tyson?

  He just indicted your whole community, right there.

• 40:33Speaker 02

  But I, I love this question, because this gets at the very heart of what it means to do science, right? Because of course, we test the heck out of our equipment, so that we know what to expect. Um, and so we can say that maybe we trust what's coming out of it. But the beautiful thing about science is you can make predictions, right? Like that you know when that solar eclipse is coming, so you can be the kid in King Arthur's court. And so even though we can't go there and see it up close, you can make predictions about other things you expect to see. Like maybe when that planet goes to another part of its orbit, what might you see? And so I think the fact that you can make predictions, and then you can test, and then you can get more data, that's like, that's magic. I mean, imagine that you could predict the stock market, so.

• 41:17Speaker 02

  I, I think that's great. I'm not worried about not being able to go there and visit, although I would love to do that. I mean, I just have to wait for pieces of the solar system to fall to earth, and then we can see them.

• 41:28Neil deGrasse Tyson?

  So I think, uh, in my 1840s, somewhere around there, before spectra became a tool to understand the chemistry of something from afar, there was a philosopher who, in his thesis, first he, he asserted, there will never be more than the seven known planets. He just asserted that, okay? And then quickly thereafter, we discovered more planets. But he also said that the stars in their beauty in the sky, we will know their colors and their locations, but we will never know what they're made of, because they're just too far away. That's what your man here sounds like. Right.

• 42:10Neil deGrasse Tyson?

  And, and within a few years, we turned spectroscopes to the stars, and we know exactly what they're made of. Right. So I, I'm, I'm not ever gonna say we will never know. Because I don't know that we'll never know.

• 42:23Speaker 02

  If you look at these drawings of the solar system from long ago, right? And you know, they're still drawing, you know, Saturn is the furthest we know about because, you know, up until the time that America was a country, that was the furthest planet we had known about. But there are some people who draw all of these different orbits and saying there might be other worlds. And you might think it's kind of fantastical, but some people had that imagination. And of course, the data bore us out. So I don't know, I get excited about seeing planets, about seeing discs. Like I said, when they fall to earth, you know, as long as I'm not a dinosaur, I'm cool with that. But meteorites are great. I mean, did you ever hang out with a meteorite at the White House, Neil, the little one that's there?

• 43:02Neil deGrasse Tyson?

  Where was that?

• 43:03Speaker 02

  So in one of the rooms in the White House, there is on loan from the Smithsonian, a piece of the Allende meteorite.

• 43:10Neil deGrasse Tyson?

  No, I've not seen it.

• 43:11Speaker 02

  Okay, I called my friend yesterday to check. They said, oh yeah, the Smithsonian just came and cleaned it, but it's still here at the White House.

• 43:17Neil deGrasse Tyson?

  Not all of us just hang out in all the rooms of the White House. Just let the record show.

• 43:21Speaker 02

  I was just staff, right? You're a, you know, a fancy distinguished guest.

• 43:27Neil deGrasse Tyson?

  I did spend a little bit of time at the White House. Yes, I know bits and pieces of the White, I don't know all the White House.

• 43:32Speaker 02

  No, no, it's, it's just cool though, because people look at this and they go, that's just an ugly rock, right? Because it's like a little black rock with white dots. And I used to go and explain to people like, no, this is amazing. This is older than the earth, right? You've got more than four and a half billion years here. And this is like, if you were baking a cake, right? And you were messy and you got flour everywhere, you bake the cake, you eat the cake. Okay, in this case, the cake or the planets. But you know, you've got with a little fossilized flour in this meteorite, you know, and it's here that we can study on earth and sort of observe at the White House. Because it's something that that meteorite landed here around the time when we were getting ready to analyze lunar rock samples. And in the end, the meteorite ended up being cooler than

• 44:15Speaker 02

  moon rocks. So I'm just saying, I'm here for planets in all their forms. As long as I'm not a dinosaur.

• 44:24Neil deGrasse Tyson?

  By the way, we might still be dinosaurs, because we don't have a way to deflect an asteroid. And we'll be, if we go extinct from an asteroid, we'd be the laughing stock of intelligent life in the galaxy for going extinct, even though we had a space program. See, dinosaurs didn't have a space program. That we know of.

• 44:46Speaker 02

  We just don't have the dinosaurs called their congresspeople to say, hey, make sure you put more funding into that.

• 44:52Matt Kirshen?

  Yeah, they had, they had the beginnings of it and it was going well, but then it got into trouble, they got into committees and then they got bogged down with red tape and you know how things go.

• 45:01Neil deGrasse Tyson?

  Fake news.

• 45:02Matt Kirshen?

  Yeah, and then money got redistributed and somehow.

• 45:06Neil deGrasse Tyson?

  Matt, we got time for one more question, it better be a kick ass question.

• 45:09Matt Kirshen?

  All right, well, I like, I like this question, hello doctors TNT.

• 45:13Neil deGrasse Tyson?

  Oh.

• 45:14Matt Kirshen?

  This is Nancy from Hell's Kitchen NYC.

• 45:18Neil deGrasse Tyson?

  All right.

• 45:19Matt Kirshen?

  Are we up or down or across the road from that, which direction are we?

• 45:22Neil deGrasse Tyson?

  They're down from us.

• 45:23Matt Kirshen?

  They're down from us, okay. So Nancy is down from us right now and Nancy is wondering, have you ever had a simulation give you a result so strange you thought either this is a bug or the universe is trying to tell me something?

• 45:35Neil deGrasse Tyson?

  Hmm.

• 45:36Speaker 02

  So I will first of all say lots of bugs, no chat GPT in my coding, so have seen plenty of those, but I actually don't think I've ever had a moment of thinking, oh, that's so weird, but instead, oh, that's so beautiful, because I always think it's amazing that we can just code the laws of gravity into our simulations and then you can watch stars and gas form into galaxies and you can look at these pictures, these simulations that are, you know, cosmological in scale and then compare them to real observations and they look the same. So I think the universe is telling us, you're doing great, can do a little better on that subgrid physics, but you know, the big scales, you got it going on.

• 46:19Speaker 02

  And it's, it's just amazing that we can see it on the computer, because if you go back, have you ever seen those tumor ray simulations from the seventies where they actually used different characters like the letter Q and the number seven as their particles in these really early computer graphics of galaxies coming together? It's so primitive compared to what we have now, but even then it was right. So I feel like at that point you would have been like, my computer is telling me something.

• 46:44Neil deGrasse Tyson?

  Well, except when, generally when you have a simulation, when you are simulating something, I like Anjali's point about the fact that you get to put laws of physics into your code, but if you've done that.

• 47:01Neil deGrasse Tyson?

  The code is not gonna show you something that is based on some new undiscovered law of physics, because you put the laws of physics in it, alright? And so, for me, the most interesting part of a simulation is, if I simulate something with my best understanding of all the laws of physics, and it still doesn't match, that means something else is happening in the universe that I have not reckoned in my models. Would you agree that you're more likely to not match the real world, because the real world has something more interesting going on in it than your simulation? And now you gotta go back to the drawing board of your simulation and figure out what's going on?

• 47:45Speaker 02

  I think there's always so much complexity in nature, and we always start from the ground up. And so you always think, "Oh, there's that more detail I could add." Just like when I draw, I'm not a great artist. I start with a stick figure, and you go, "Oh, okay, I can add some eyelashes and some more things, but it needs some color, it needs a little bit more." It's just the same way with our simulations. So oftentimes, you can think about what's missing here, and how do we add that little chef's kiss of color?

• 48:08Neil deGrasse Tyson?

  Yeah, she mentioned this experiment by Tomborey. He's a very famous astronomer of the day. And we saw these galaxies out there that were very disturbed-looking, and we didn't know why. There was even a catalog of disturbed galaxies, okay? The Atlas of Peculiar Galaxies. And why do they look peculiar, but we look perfect? We have two-arm spirals. And are they a different kind of galaxy? And so, we had to figure out that these are the products of colliding galaxies. And all the gravity, they distort, because they all feel different parts of the gravity at all different times.

• 48:52Neil deGrasse Tyson?

  And Anjali, do you remember how he figured that out? How he did the experiment?

• 48:59Speaker 02

  I mean, I just, I have the visual in my mind, right, of the Tomb Ray and Tomb Ray, because it was Alar and his brother, right, who were doing these simulations.

• 49:07Neil deGrasse Tyson?

  Was it he the one, or was it someone before him? Because how do you simulate? You don't really have a computer yet to do it full-blown. Oh, no, no, it was someone before him. Before him, I forgot who was.

• 49:19Speaker 02

  Figure out the mergers.

• 49:21Neil deGrasse Tyson?

  Even before Tomb Ray's first computer simulations of this, as Anjali describes, Eric Holmberg, another galaxy guy, he figured out how to do it with light. Because gravity drops off as one over the distance squared. Okay? Mm-hmm. One over the distance squared. Now, if you don't have a computer, how are you going to simulate that on a table? How are you going to do that? You can like move everything every moment and then calculate everything, but that's too much effort. So what he did? He had light bulbs and light meters. Because light drops off as one over distance squared, the intensity of light. That makes sense. And so the light bulbs were the parts of galaxies.

• 50:05Neil deGrasse Tyson?

  And he took light readings at what the intensity of the light was, and that was proxy for the intensity of the gravity. And you got to see the distortions in the spiral arms of the galaxy, and you could recreate all the messy galaxies that look like puppy vomit on the sky.

• 50:20Speaker 02

  Oh, Neil, galaxies are beautiful, right? I'm cute too, so maybe you think anything that comes out of a puppy is cute, but...

• 50:27Neil deGrasse Tyson?

  Yeah, puppy vomit can be beautifully autistic. Okay, that's pretty clever, right, you think?

• 50:32Speaker 02

  I mean, it's amazing what people do in all sort of senses, right? It's not just looking at it on a screen. We did that actually this past year where we actually had a museum exhibit, and we tried to make it multisensory for exoplanets. So I worked with a perfumer and a sound engineer, so we had the sounds and smells to get you in that world. We didn't do any experiments with it, but it helped bring people in in different ways, which was pretty cool.

• 50:57Neil deGrasse Tyson?

  So presumably some of these planets might have hydrogen sulfide.

• 51:01Speaker 02

  You did not poison anybody, Neil. No, actually, the most interesting part of working with a perfume artist is when you said, oh, we wanted to get towards habitability in life. She brought me lots of smells of manure because she said there is nothing more lifelike than manure. So we didn't have the puppy vomit smells, but we had some other smells there that were very.

• 51:25Neil deGrasse Tyson?

  Your perfumer brought you manure?

• 51:28Speaker 02

  No, no, smells of manure.

• 51:32Speaker 02

  Aren't you glad you don't work at NASA with me smelling?

• 51:35Neil deGrasse Tyson?

  Thank you for clarifying.

• 51:36Matt Kirshen?

  Just the little manure scent that you can just dab on your wrist and behind your ears.

• 51:40Neil deGrasse Tyson?

  Remind me not to buy that person's perfume.

• 51:43Speaker 02

  No, the rest of it, though, was incredible because what we ended up doing is we had smells like rose garden and horse stables and things like G and T on a Saturday night. It wasn't the tea and tea drink that we apparently need to come out with, but you know, things that people would recognize. And then the other wall had these smells of, you know, what does lightning on Saturn smell like or interstellar space or a rock garden on Mars or a clean spaceship? Getting you imagining that one day in the future, those smells could be just as realistic and familiar to us as the rose garden where you don't have to read the plaque. And so going from there to then being immersed in the sound bath where the distances of these exoplanets

• 52:24Speaker 02

  were represented by pauses in the music. It just sort of brought it together. And even though some of the smells maybe were not what you would choose for, you know, going out on a Friday night, it was still pretty cool.

• 52:36Neil deGrasse Tyson?

  Well, thank you, Anjali, for participating in our cosmic queries.

• 52:41Speaker 02

  It's so good to be here.

• 52:43Neil deGrasse Tyson?

  When you pass 6,000, give us a call. 6,000 exoplanets.

• 52:47Speaker 02

  I honestly suspect it will pass 6,000 by the time this airs.

• 52:51Neil deGrasse Tyson?

  Oh, okay. And you know what I do at every one of my public talks? I ask everyone to stand who has born since 1995 because that was the first exoplanet discovered.

• 53:02Matt Kirshen?

  Which is a lot of people.

• 53:04Neil deGrasse Tyson?

  A lot of people, yeah, a lot of people. And because they only known life with exoplanets in the catalog, right? Okay. So they're all standing up and I say, raise your right hand. And they raise their right hand. And I say, I declare all of you to be Generation X exoplanet.

• 53:24Neil deGrasse Tyson?

  And then they sit down.

• 53:26Speaker 02

  I love that, Neil.

• 53:27Matt Kirshen?

  But again, that just hammers home how absurdly new this entire branch of science is.

• 53:31Neil deGrasse Tyson?

  That's how you began the whole conversation.

• 53:33Matt Kirshen?

  Yeah.

• 53:33Neil deGrasse Tyson?

  Yes. Laura, I tell all my friends at JPL I said hi.

• 53:36Speaker 02

  Will do. Will do.

• 53:38Neil deGrasse Tyson?

  Matt, we'll see you on your website.

• 53:40Matt Kirshen?

  Yeah, I'm on tour and on Probably Science. We will get you back very soon.

• 53:44Neil deGrasse Tyson?

  Probably, that's your podcast.

• 53:46Matt Kirshen?

  That is my podcast.

• 53:47Neil deGrasse Tyson?

  Probably Science, okay.

• 53:49Matt Kirshen?

  Very happy to steal you.

• 53:50Neil deGrasse Tyson?

  I've been on it only once, apparently.

• 53:51Matt Kirshen?

  We're making it happen again. We're making it happen again.

• 53:53Neil deGrasse Tyson?

  Near my phone the whole time.

• 53:55Matt Kirshen?

  You're a busy man. We need to pick up moments.

• 53:59Neil deGrasse Tyson?

  All right. This has been another installment of Cosmic Queries. This would be the Exoplanet edition. I want to thank my guests, Anjali Chirapathy and Matt Kirshen. Until next time, I bid you to keep looking up.