Pod Insights StarTalk Podcast StarTalk Live! at the Beacon (Part 2): King of the Kuiper Belt About this episode Our show from NYC’s Beacon Theatre concludes with Neil Tyson and Dr. Natalie Starkey debating Pluto’s status, judged by comedians Eugene Mirman, Ilana Glazer and Scott Adsit. Plus, Christine Lavin sings “Planet X.” Part of the Eugene Mirman Comedy Festival.
Transcript Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.
0:01 Neil deGrasse Tyson? Welcome to StarTalk. Your place in the universe where science and pop culture collide. StarTalk begins right now.
0:14 Neil deGrasse Tyson? I'm your host Neil deGrasse Tyson, your personal astrophysicist. And we've got with us Scott Atzen, who's a comedian and performer and all-around good guy. And Natalie Starkey, visiting from the Open University in the UK, expert on comets. Welcome.
0:36 Neil deGrasse Tyson? Eugene, introduce.
0:37 Eugene Mirman? Alana Glazer from Broad City.
0:43 Neil deGrasse Tyson? And Eugene Mirman. Just so you know, this StarTalk Live concept was birthed as a part of Eugene Mirman's Comedy Festival. And it's called Eugene Mirman's Comedy Festival. It's an honor to be a part of your celebrations.
0:56 Eugene Mirman? Thank you.
0:57 Neil deGrasse Tyson? Which showcases comedians, and as we continue to do even for StarTalk.
1:00 Eugene Mirman? Yes.
1:01 Neil deGrasse Tyson? On this. So, thanks Eugene for that.
1:03 Eugene Mirman? Glad to be here. Thank you.
1:05 Neil deGrasse Tyson? So, ladies and gentlemen, we will be discussing Pluto in its entirety. Everything you ever wanted to know, or never thought you could know about Pluto. Alright, so Natalie, what can you tell us about the New Horizons mission to Pluto? That was launched in 2006. And so it took 10 years to get the Pluto.
1:30 Natalie Starkey? Yeah.
1:31 Neil deGrasse Tyson? And all designed for Pluto. That was its target.
1:34 Natalie Starkey? Exactly. But it wasn't actually an easy mission, because it didn't have a lot of support initially. So, there was a bit of a mission in itself to get it launched, and then eventually...
1:46 Neil deGrasse Tyson? You're looking like it was my fault or something.
1:48 Natalie Starkey? Well, not your fault. I won't blame you. But yeah, there wasn't support. And it basically, a bunch of astronomers got together and thought, right, hold on, we need to go to this planet. Because it so happened, it was in a position in space where it was kind of easy to get to within a certain timeframe. And this was because Jupiter happened to be in alignment, meaning that basically the journey was 50% shorter than it could have been if we waited a bit longer.
2:13 Neil deGrasse Tyson? Shorter in time.
2:14 Natalie Starkey? Yeah, yeah.
2:15 Neil deGrasse Tyson? Not shorter in distance.
2:16 Natalie Starkey? In time, yeah.
2:17 Eugene Mirman? Why is it shorter in time?
2:19 Natalie Starkey? Because they used Jupiter as, we mentioned-
2:21 Eugene Mirman? A slingshot?
2:22 Natalie Starkey? Gravity slingshots, exactly. And Jupiter's really big.
2:26 Neil deGrasse Tyson? Jupiter's the best slingshot.
2:27 Natalie Starkey? It's very big, so...
2:28 Eugene Mirman? The sun is the best, I know from Star Trek IV.
2:33 Eugene Mirman? But I understand-
2:35 Neil deGrasse Tyson? We saved the whales.
2:36 Eugene Mirman? Sands time travel.
2:36 Neil deGrasse Tyson? Saved the whales, Star Trek, okay.
2:38 Eugene Mirman? Yeah.
2:39 Neil deGrasse Tyson? So, we slingshot Jupiter?
2:40 Natalie Starkey? Yeah, we did. And we actually got a really good view of one of Jupiter's moons called Io. Because although the spacecraft was in hibernation for a lot of this journey, because they needed to save the power, they woke it up for this encounter with Jupiter's moon and got some beautiful images of a volcano erupting in space. Which is pretty cool.
3:01 Neil deGrasse Tyson? Now Io, from, just from reading about it, it's the most volcanically active place in the solar system. It kept warm from hot, from the stresses of Jupiter's gravity.
3:12 Natalie Starkey? Exactly.
3:12 Neil deGrasse Tyson? Yeah, so, it's pretty much true, no matter when you'd swing by, there'd be something erupting, pretty much.
3:17 Natalie Starkey? Maybe, but I guess, yeah, we don't really know. We need to go and look at it more.
3:20 Eugene Mirman? So there's volcanoes on a moon of Jupiter that are constantly erupting? Is that accurate?
3:24 Natalie Starkey? Yeah, well, yeah, yeah.
3:25 Eugene Mirman? And it's molten and all that? Okay, cool.
3:28 Neil deGrasse Tyson? That's not even the coolest volcanoes, though. There are other moons-
3:32 Eugene Mirman? Yeah?
3:32 Neil deGrasse Tyson? -that have ice volcanoes.
3:34 Natalie Starkey? Wow.
3:34 Eugene Mirman? Really?
3:35 Neil deGrasse Tyson? Yeah, yeah. Where it's erupting, like, cold things instead. Because it's just a matter of pressure.
3:40 Eugene Mirman? And ice, like, the regular ice, not super heavy or weird?
3:44 Neil deGrasse Tyson? No, no, other things that are ice at much colder temperatures. Yeah.
3:48 Eugene Mirman? It's not water?
3:49 Neil deGrasse Tyson? No, not water ice, no, no. So, so, all that matters is that, at the temperature, something is boiling hot. Okay? So, there are things that are boiling hot at much cooler temperatures. If you look at liquid nitrogen, it is boiling hot. So, but I interrupt, go on. So we swing by Io-
4:04 Natalie Starkey? Yep.
4:05 Neil deGrasse Tyson? And get some good data, close down again, and keep going?
4:09 Natalie Starkey? Yep, and keep going.
4:09 Neil deGrasse Tyson? That's sneaky, that's good.
4:10 Natalie Starkey? And, you know, it was kind of quiet, this mission. I think a lot of people didn't really know it was happening, and what they were aiming for. Because it's hard to get the public excitement over nine years, so it often kind of all happens at the end, as it did with Rosetta as well. And then, you know, I kind of, I wasn't personally expecting it to be as good as it was when it finally got to Pluto. And I thought, oh, they'll just get a few grainy images, you know, a few pixelated images of this little round blob in space, and we're not going to learn anything new. Well, that was completely wrong. We've, I mean, the images are still flooding back. It's gonna take them a huge amount of time to download all the data because we've got a very slow connection. You wouldn't want that kind of internet connection normally. It's gonna take a while to get these images.
4:55 Natalie Starkey? But what we've got coming back already is, it's just absolutely amazing.
4:59 Neil deGrasse Tyson? Now, this is the fastest spaceship ever launched.
5:02 Natalie Starkey? Yeah.
5:03 Neil deGrasse Tyson? Yeah, and so for good reason, they, that's on purpose. It's not an accident because Pluto is far. And as I've said many times on this stage, in any scientific experiment, the number one rule is that you want the experiment to be finished before you die. Right, so, so they, so they stripped the spacecraft of as much of its mass as possible and put the fattest boosters they possibly could. So you have high thrust, low mass.
5:30 Natalie Starkey? Yep.
5:30 Neil deGrasse Tyson? Gives you high acceleration, Isaac Newton's second law. Because you know, Newton's my man, you know that, okay? So, so, so I'm told it got to the orbit of the moon in nine hours. Whereas it took the astronauts three days.
5:48 Natalie Starkey? Yeah.
5:49 Neil deGrasse Tyson? Right, so this is booking out of the, this is- How fast is it going?
5:53 Natalie Starkey? Thirty-six thousand kilometers, I think, was it?
5:55 Neil deGrasse Tyson? Yeah, I have it written down here, thirty-six thousand miles per hour. Left our atmosphere, thirty-six thousand miles per hour. Escape velocity for Earth is twenty-five thousand miles per hour. So this was going at about twelve, thirteen miles per second. From Earth, per second. From launch? Yes. Oh yeah, oh yeah. So it was gone before they could see where it went?
6:24 Neil deGrasse Tyson? Um, but we kind of know where it's going. It's not like, we kind of, we track it. They put a flag on it, something like that? Yeah, no, we got this.
6:33 Eugene Mirman? You pointed it before you turned it on.
6:36 Neil deGrasse Tyson? Yeah, we got this one, Scott. We got this one.
6:38 Speaker 03 How does it launch? How does it launch that fast?
6:41 Neil deGrasse Tyson? No, it's got very strong boosters on a very low mass craft. Now, here's an interesting fact, I think. Back when we launched the Saturn V rocket and the astronauts to the moon, that is a massive thrust, but the rocket is very heavy. So it took a long time for the rocket to clear the tower. So it looked like a very slow launch. The space shuttle had much less mass for its rocket thrust. So, yeah, so the acceleration is high, gets to high speed very quickly because it's going a very long distance. From what you say, it exceeded our expectations in every way.
7:19 Natalie Starkey? Yeah, probably not the scientists that designed it, but I've been really impressed. I just wasn't, I just think we got some amazing images from Rosetta and we've learnt so much about the comet just from getting images. It's amazing as a geologist what we'll do with a picture of a rock, you know. I won't go there, but you know, we can learn so much. But with Pluto, you know, we can learn what is going on on its surface. So we're not going to be analyzing it directly. We don't have a piece of it, you know, that's annoying. But we can learn a lot about what it looks like by comparing what it looks like to what we see on Earth and other planets that we understand very well and then try and work out how it formed.
7:59 Neil deGrasse Tyson? And so, so of course Pluto has its large moon Charon. And I think this also can be pronounced Karen. So, that's a huge moon. In fact, it is so large compared with Pluto. I don't know if you knew this. So we're Earth and like, we have our moon. And the moon doesn't go around Earth. Earth and the moon go around our common center of gravity. But that center of gravity is like within the Earth. So the Earth is kind of jiggling like that as our moon goes around us. Fine. Pluto's moon Charon is so large compared to it that the center mass is outside of Pluto. That's embarrassing. If your moon pulls you...
8:41 Eugene Mirman? Is its moon bigger than Pluto?
8:43 Neil deGrasse Tyson? Don't, no, no. Pluto Charon is about half the size of Pluto, half the diameter of Pluto.
8:49 Speaker 03 Right.
8:49 Eugene Mirman? How big is Karen?
8:54 Neil deGrasse Tyson? I don't know, 1,000 miles across? Something like that?
8:57 Natalie Starkey? Yeah, because I think Pluto is around 2,000.
8:59 Neil deGrasse Tyson? So, I noticed that the terrain, from the images I saw, was not simply a victim of space impacts, which is what I expected it to be.
9:11 Natalie Starkey? Yeah.
9:11 Neil deGrasse Tyson? It looked like it had interesting geologic or Pluto-logic features unto itself.
9:17 Natalie Starkey? Yeah.
9:18 Neil deGrasse Tyson? And you, with geologic roots, what do you say about it? Does that mean Pluto had plate tectonics or build mountains? Did it have a heat source that could make that happen?
9:28 Natalie Starkey? The answer is we don't know for sure. And that's annoying, but scientists are still looking at all the data that's coming out. But the hypothesis was that this thing had just sat in the outer solar system, maybe being bombarded by the odd comet and some impacts had happened. And so we would see the result of that, like we do on our moon, on the surface of Pluto, we'd see lots of craters. But now we look at it, well, we would describe it as a geologically young surface, like the Earth, basically. We have plate tectonics on Earth that renews our surface. Now on Pluto...
10:03 Neil deGrasse Tyson? You say geologically young, it's not how old the planet is, it's how old the surface is.
10:07 Natalie Starkey? Yeah, when that formed. And so we're saying that some of the features on Pluto look like they formed within millions of years ago, rather than billions of years ago. So I know millions is still a huge amount of time, but it's not billions.
10:20 Neil deGrasse Tyson? That means it's got some kind of energy source within it, generating these features.
10:27 Natalie Starkey? Yeah. We're trying to understand the structure at the moment. We think maybe it's got a rocky inner portion. It maybe has a liquid, kind of outer shell to it, and then surrounded by an ice crust, essentially.
10:42 Neil deGrasse Tyson? This would be a water ice crust, because ice floats on water. So you could have a solid surface sitting on top of a liquid next layer, right?
10:50 Natalie Starkey? Yeah, and we think the moon, Sharon, could be the same. But we're still trying to understand, because of the mass of the planet, what we predict the mass to be and the size of it. We can then use that to work out the density of that object. So working on the known densities from these parameters, we can start to predict what is inside that planet.
11:11 Neil deGrasse Tyson? So, if I understand correctly, you are Pluto-phile?
11:16 Natalie Starkey? Yeah, why not?
11:20 Neil deGrasse Tyson? I just want to get a sense of, because you all know my situation with Pluto.
11:27 Neil deGrasse Tyson? I think. If not, how did you even get in here?
11:31 Neil deGrasse Tyson? What do you, where'd you come from?
11:34 Neil deGrasse Tyson? Because Pluto and I have issues that go way back.
11:38 Neil deGrasse Tyson? But if I could just get just from a show of hands or just some noise, who here is still a little disturbed that Pluto got demoted to dwarf planet status?
11:53 Neil deGrasse Tyson? Now, how many of you understand the data on this situation?
12:04 Neil deGrasse Tyson? Because I've found people closer to Pluto have sort of deeper sentiment for it. And we could argue that they know more about it than I do and therefore they're more right. But I just thought we might explore this more deeply. We might actually have sort of a debate in front of you on this. And maybe we can have the three comedians be the judge of... Can you guys know how to judge something? Oh, yeah.
12:26 Eugene Mirman? Yeah, yeah.
12:28 Eugene Mirman? I look forward to telling all of you whether it's a planet or not.
12:34 Neil deGrasse Tyson? So Natalie, you want to give it your best shot?
12:36 Natalie Starkey? Okay.
12:37 Neil deGrasse Tyson? And I'll sit back and I will stay silent the whole time.
12:40 Natalie Starkey? Okay, it's a bait.
12:41 Neil deGrasse Tyson? Okay. So you, so you want to, you're arguing for Pluto's planethood?
12:47 Natalie Starkey? Yeah.
12:49 Neil deGrasse Tyson? And you're in front of, these are my people out here, you want to...
12:53 Natalie Starkey? I'm more worried that I'm debating it with you, but anyway. Okay.
12:58 Neil deGrasse Tyson? Okay, all right, go ahead.
13:00 Natalie Starkey? Okay, well, I think my first reason for Pluto being a planet is maybe a little bit silly, but my mnemonic fails seriously for naming the order of the planets, which I rely on still. So my very easy method just speeds up naming planets. It doesn't really work if it don't have Pluto. So that, I think, across every single language, they're going to have a mnemonic. And what are we going to do? We've got to think of a new one. So, okay, that's pretty bad. Not a disaster. Not a disaster.
13:34 Neil deGrasse Tyson? And just to be clear, pizza is a pretty popular food in the United States, especially New York, especially New York City, especially Manhattan. So our mnemonic, the P stood for pizza. My very educated mother just served us nine pizzas.
13:49 Natalie Starkey? Still doesn't work though, does it, if you lose Pluto? So...
13:52 Neil deGrasse Tyson? Yeah, yeah. If you lose Pluto, we gotta, you gotta fix the mnemonic.
13:55 Natalie Starkey? Yeah. So that's a problem.
13:57 Speaker 04 You'd have to change it to, "My mother just served us nothing."
14:04 Neil deGrasse Tyson? That works.
14:08 Natalie Starkey? Okay.
14:10 Neil deGrasse Tyson? By the way, in my, I don't mean to interrupt, but yes, I do mean to interrupt.
14:14 Natalie Starkey? I thought you were gonna be quiet.
14:16 Neil deGrasse Tyson? In my Pluto book, I had like five pages of new mnemonics to help you through that transition. "My very educated mother just served us nachos."
14:26 Natalie Starkey? Great.
14:27 Neil deGrasse Tyson? Okay.
14:28 Natalie Starkey? Okay.
14:28 Neil deGrasse Tyson? Please proceed.
14:29 Natalie Starkey? We'll move on, because I don't think you can argue with the fact that Pluto appears to be geologically active. Now, it's like a planet, right? We don't get geologically active comets that we know of. We see the comet we went to with Rosetta has processes happening on its surface related to what happens when it goes close to the sun. But it's not the reason on Pluto. Some of it is, but there's some internal force happening. It's acting like a planet. And it's also pretty large. We can't deny the fact that, okay, we found some larger objects out there, but it's kind of been there all the time. It's the little cute Pluto. I don't want to lose it.
15:11 Natalie Starkey? It's, it's just special. And then finally, I think my final reason...
15:17 Neil deGrasse Tyson? Those are your two lead arguments? Now it's finally?
15:19 Natalie Starkey? I don't believe them.
15:21 Neil deGrasse Tyson? Okay, go on.
15:21 Natalie Starkey? One final thing is that you're saying it's a comet. Well, it doesn't behave like a comet. Now, the word comet comes from the Greek for long-haired, because this tail of comet is like a long hair flowing in the wind. When Pluto goes via the sun, it doesn't have a tail. It's not a comet. So, and this is how we define it.
15:45 Eugene Mirman? That's a good one. Neil, you can say your piece and then we can have questions.
15:50 Neil deGrasse Tyson? Okay, so I take my cues from history. I do a fair amount of reading of where our understanding of the universe and our place within it pivoted based on new information. In the year 1800, or was it 1801, we discovered a new planet orbiting between Mars and Jupiter. Everyone was excited. It made it into the books. We even had a Latin name for it, as was the name of the other planets. It was, we named it Ceres, C-E-R-E-S, for the goddess of harvest, and Ceres is the root for the word cereal. Everyone was excited. The books
16:31 Neil deGrasse Tyson? counted an extra planet now discovered between Mars and Jupiter. And then we kept looking and then we found like another planet there, and then another, and then another. Four planets were discovered relatively quickly. Ceres, and we named them Ceres, Pallas, Juno, Vesta. All of these. Everyone was excited. So for a while there, we had Mercury, Venus, Earth, Mars, Ceres, Pallas, Junos, Vesta, Jupiter, Saturn, Uranus. We had like 12 planets. I have textbooks from the 1800s that enumerate these and everyone is celebrating. But then they kept looking and they found even more and more. Now there's 30, now there's 50.
17:12 Neil deGrasse Tyson? And what people realized was that these objects, which were so small, you could not see their size through a telescope. They were pinpoints of light, appearing just the way a star would, a pinpoint of light. They were star-like. Asteroid. And what came out of this exercise was that instead of having discovered four planets, what actually happened is that we discovered a new swath of real estate in the solar system. The asteroid belt. And now we're upwards in hundreds of thousands of these objects. And of course, upon recognizing
17:53 Neil deGrasse Tyson? that the solar system gained a new place, no one got upset by the demotion of these four objects because we didn't lose four freshly discovered planets. We gained an entire deeper and new understanding of the structure of our solar system.
18:12 Neil deGrasse Tyson? And so it was, time would move on, until 1930. We discover, though it was motivated by the search for Planet X, some perturbing unseen force of gravity on the orbit of Neptune. It was not where you would have expected Planet X to be, and Planet X would later evaporate in the dustbin of errors in scientific measurements. That's why you don't hear about Planet X anymore. But, 1930, Clyde Timeout discovers what everyone wants to be, that Planet X, the ninth planet. Everyone is excited. The New York Times reports, that day, the supposed size of Pluto, the size of the Earth. Well, if it's the size of the Earth, it's gotta be a planet. How could it be anything else?
18:57 Neil deGrasse Tyson? What they didn't tell you is that that was not a measurement, it was an assumption. It would take 45 years before our measurements of Pluto would become precise enough to learn that it is a fraction the size of our moon. Not only that, well, that was the 1970s, add another 20 years, right when we are designing the Rose Cent-- what would become the Rose Center for Earth in Space, we're about to cut metal. We want to make exhibits that are future-proof, and we ask, "What's up with Pluto?" And we look around and we find that new objects had just been discovered in the outer solar system. Icy, like Pluto. Weird orbits, like Pluto. And we said to ourselves, "Perhaps Pluto is not the ninth planet.
19:40 Neil deGrasse Tyson? Perhaps Pluto was the first object discovered of a new swath of real estate." Which today, we have come to name the Kuiper Belt of icy bodies. Yes, I call Pluto a comet, that was just, I was being a little mean there, but it is nonetheless an icy-- Mean or wrong? It was nonetheless an icy body, 70% made of ice. If Pluto were where, if you put Pluto where Earth is right now, subject to the heat from the Sun, it would in fact grow a tail. Just as other planets do when they near the Sun. Did you just say "other planets"? Other comets.
20:24 Speaker 03 Oh.
20:29 Speaker 03 Good spot.
20:52 Neil deGrasse Tyson? Si fuori Jupiteri e guardiamo e chiediamo "quanti pianeti sono nel sistema solare?" diremo "quattro" Jupiter, Saturno, Uranus e Neptuno e tutto il resto sarebbero vagabonds specialmente perché Jupiter ha sistemi meteorologici più grandi di quelli di tutto il pianeta Terra quindi non sto nemmeno... la dimensione non è un problema per me qui altrimenti dobbiamo iniziare a demodare Terra quello che è un problema è che l'IAU ha inventato tre criteri per il stato del pianeta uno è sufficientemente grande per che la gravità lo renda circolante? Pluto è così?
21:35 Natalie Starkey? È così, è circolante
21:36 Neil deGrasse Tyson? È circolante, sì, abbiamo detto di sì se Pluto fosse più piccolo la forza della roccia definirebbe la sua forma più che la forza della gravità collettiva delle rocce e è questo il motivo per cui oggetti molto piccoli sono cattivi il vostro cometto non era sferico
21:51 Natalie Starkey? sicuramente no
21:51 Neil deGrasse Tyson? perché è solo a pochi chilometri di lungo i mooni di Marte sembrano patatine d'Idaho, non sono sferici sono di dimensione come Manhattan sono piccoli, la gravità non li può coprire in una sfera quindi forse dovremmo demodare i mooni di Marte in qualcos'altro patatine di Marte o qualcosa del genere, non so lavoriamo su quei successivamente e quindi Pluto è circolante secondo criterio in sua orbita attorno a Terra c'è altro casino orbitando con essa? sì, c'è, il bello di Kuiper la massa del Kuiper è molto più grande della massa di Pluto Pluto non appartiene al suo spazio orbitale ogni pianeta appartiene al suo spazio orbitale
22:35 Neil deGrasse Tyson? e quindi la serie più grande di asteroidi è in realtà sufficientemente grande per essere una sfera l'unico oggetto di tale dimensione nel bello di asteroidi ma non è in sua zona è nel bello di asteroidi Sirius è stato elevato da asteroidi a pianeta di dwarfo Pluto è stato demodato From planet to dwarf planet.
22:57 Natalie Starkey? It's a planet. Planet in the name.
23:00 Neil deGrasse Tyson? Okay, so okay. Okay, so you want to do that on a technicality, that's fine. It's a planet, what kind of a planet is it? It's a dwarf planet. Fine, I'll cede that, if that's what you want.
23:13 Eugene Mirman? What's the third requirement for something being a planet, other than having the word planet in it?
23:18 Neil deGrasse Tyson? I forgot the third criterion.
23:21 Eugene Mirman? Is it matter that it might have geo stuff on the inside doing stuff?
23:25 Natalie Starkey? No, that's not one of the...
23:27 Eugene Mirman? No, that doesn't matter? That was one of your main points.
23:31 Neil deGrasse Tyson? Because once it failed that one, I didn't have to remember any of the other rules.
23:33 Natalie Starkey? But it didn't necessarily fail, the second parameter, because I'm not a physicist, correct me if I'm wrong, but it all depends on the scattering parameter of that planet related to its sun, or sorry, its star system. And so if you were to maybe take Pluto to a different star system, it might have a different scattering parameter such that it did clear its path, it's just that we're looking at here, so we would call it a planet somewhere else, but maybe not here.
24:03 Neil deGrasse Tyson? Okay, so this is a point that Alan Stern, who's the principal investigator of the New Horizons mission, makes. He's saying, whether you call something a planet should not be dependent on where you find it. It should be something inherent in the object itself. And I don't, in principle, have a problem with that. I will just wait for you to find something as puny as Pluto, that in fact did clear its orbit, and then we can resume this conversation. But until you find it, it is a wild hypothesis that Pluto in another system, at its size and at its mass, would own its orbit. That's, it's, I'll wait for you to find it, and then we can talk. But until then, your argument is invalid.
24:48 Neil deGrasse Tyson? I love saying that.
24:50 Speaker 03 You know before how you were like, if Pluto were closer to the sun, it would have a tail?
24:56 Neil deGrasse Tyson? Totally. Totally have a tail. More than half of Pluto's volume is ice.
25:01 Natalie Starkey? But it's not close to the sun. It's a planet, just orbiting happily, it's not getting closer.
25:08 Neil deGrasse Tyson? Okay, so now watch, but you can't have it both ways? I'm now telling you, you're saying it's a planet no matter where it is? I take Pluto, you call it a planet out there, and it doesn't have a tail? Put it near where Mercury is? It's going to have the biggest tail you ever saw?
25:23 Neil deGrasse Tyson? Alright, let's try it.
25:30 Neil deGrasse Tyson? Okay, um, I was reminded of the third, the third criterion, okay?
25:36 Natalie Starkey? My god, that's good.
25:37 Neil deGrasse Tyson? The third criterion is that the primary thing that it orbits is the sun. So, the moon has cleared its orbit.
25:47 Neil deGrasse Tyson? The moon has cleared its orbit, is large enough to be round,
25:51 Neil deGrasse Tyson? but it is not the primary body orbiting the sun. We are. So it's how you exclude moons from this conversation.
26:00 Neil deGrasse Tyson? Now-
26:00 Eugene Mirman? Pluto's its own moon?
26:05 Natalie Starkey? That's not what he said.
26:08 Natalie Starkey? Is it?
26:09 Neil deGrasse Tyson? Now, can I offer reflections on this, if I may?
26:13 Natalie Starkey? Go ahead.
26:13 Neil deGrasse Tyson? Unless you, you have rebuttals to what?
26:15 Natalie Starkey? It does, it does, right, it does orbit. So it meets two of the three criteria.
26:19 Neil deGrasse Tyson? Yeah, two, it meets two of the three. It's the prime, even though it's doing a jig with the, with Sharon, it's still the primary object in that system.
26:27 Natalie Starkey? It meets two of the three, and that other one that you didn't like, we could argue the other way. So it could meet three of the three, in which case it's a planet.
26:37 Natalie Starkey? We just need to prove it, we need to go out and-
26:40 Neil deGrasse Tyson? Do you comedians have any sort of feelings or reaction to this Pluto conversation?
26:44 Eugene Mirman? I was gonna say, I thought Pluto wasn't a planet, but now I think it's maybe a planet. And I think dwarf planet is a type of planet. So I find it upsetting that it's a dwarf planet and that this argument even exists. Like, if you called it a dwarf and then the second word was not the word planet, I would be a lot more comfortable
27:09 Eugene Mirman? with it.
27:10 Neil deGrasse Tyson? I, I have no rebuttal to you on that. Yeah, so Ilana, what?
27:13 Speaker 03 Yeah, um, your points were like, both your points were scary good.
27:19 Speaker 03 It seems to be a tiny planet and a tiny, like, weird planet in our-
27:25 Natalie Starkey? It's a bit of an oddball, you know? It likes to do its own thing, and it's okay to be different, right?
27:30 Speaker 03 It's not like the best planet. It's like a [BLEEP] little planet.
27:38 Neil deGrasse Tyson? Scott.
27:40 Speaker 04 Well, first of all, I don't think Pluto cares what we call it.
27:42 Neil deGrasse Tyson? Yeah, that's kinda true.
27:43 Speaker 05 Wow, that.
27:44 Speaker 04 I mean, that's like, you think about like a, we call something a bivalve invertebrate on the bottom of the ocean, and it just says, "I'm Kevin."
27:57 Speaker 04 So I don't think Pluto cares about this argument at all, but...
28:01 Neil deGrasse Tyson? Do bivalves have gender?
28:02 Speaker 04 Did I say he?
28:03 Neil deGrasse Tyson? You said Kevin.
28:04 Speaker 04 Who says Kevin has to be a boy?
28:06 Neil deGrasse Tyson? Okay.
28:08 Neil deGrasse Tyson? Kevin's quite the lady.
28:13 Speaker 04 I think that, I think you, I think you found a happy medium here when she called you out on calling it a dwarf planet. I think it's, I think you both win, because it is, yes, it's too small to be a planet, it's a dwarf planet, it's still a planet. I think everybody wins.
28:30 Speaker 05 Oh.
28:32 Neil deGrasse Tyson? May I, may I reflect on this?
28:35 Speaker 04 Yeah.
28:36 Speaker 05 Of course.
28:36 Neil deGrasse Tyson? So, my sense of this, and I've made this case, I've made this case, I did a PBS special on this, right, and at the end I just sort of laid it out, what I think really should have been going on all along, is, do you know the original definition of planet? It was defined by the ancient Greeks, and planetes means wanderer. And they looked up in the sky and they counted precisely seven objects that moved against the background stars. Mercury, Venus, Mars, Jupiter, Saturn, the sun, and the moon. These were the seven
29:19 Neil deGrasse Tyson? planetes, the seven planets. We trace the names of the seven days of the week to these seven planets. The fact that they were called wanderers is quite an indication of our ignorance of how and why they moved the way they did, because we call them wanderers rather than orbiters, for example. So, that's the original definition. Copernicus comes along and says, "Wait a minute, the sun is very different from these other objects in the sky. It is in the middle of all of this motion. We are one of these other objects moving around the sun."
29:57 Speaker 04 I hope he was killed for this.
30:03 Neil deGrasse Tyson? So.
30:04 Eugene Mirman? Or at least had to go like, "Just kidding."
30:06 Neil deGrasse Tyson? Yeah, yeah.
30:09 Neil deGrasse Tyson? So, you are half, you are two-thirds right on this.
30:13 Eugene Mirman? I know Greeks.
30:14 Neil deGrasse Tyson? Alright, so, Copernicus, this is in 1542, 1550, around there, mid-sixteenth century. He waited until he was on his deathbed to publish the book. So he wasn't killed for it, he died for it.
30:31 Natalie Starkey? Well, from it.
30:34 Neil deGrasse Tyson? No, he knew he was like...
30:35 Eugene Mirman? Do you think he told his friends?
30:37 Neil deGrasse Tyson? So now...
30:38 Eugene Mirman? "The sun's a little different."
30:39 Neil deGrasse Tyson? Okay.
30:39 Eugene Mirman? "Wait till I die."
30:43 Neil deGrasse Tyson? So then, what, one of the people encouraging him to publish this said, "This is pretty scandalous stuff, heretical stuff, and we need to put a disclaimer in the preamble." So there's a disclaimer there. And it is not written by Copernicus, even though the author of its name is not given. We know from other texts who did this. And the disclaimer says, "Here is a new model for the solar system that will allow the mathematics to be simplified. It does not have to actually be true if it's helpful to the scientists, the mathematicians, to calculate." And so that was the disclaimer. It was a simple mathematical exercise
31:28 Neil deGrasse Tyson? in putting the sun in the middle and the orbits around. Previous to that, we had epicycles and other highly complex orbital patterns of these objects in the night sky. My point is, the original definition of planet, once Copernicus came on the scene, became completely idiotic, alright? Understandable in its day, but it made no sense to think of planets as wanderers anymore once we had a deeper understanding of the structure of the solar system. The sun in the middle, the rest of us going around the sun. That relegated Earth to planet status. The sun to star status. The moon to something, to a satellite of Earth.
32:11 Neil deGrasse Tyson? So we went from seven planets to six planets. Mercury, Venus, Earth, Mars, Jupiter, Saturn. Six planets. So we dropped the planet count at that time. Okay, so now... If a planet is just anything that goes around the sun, then fine. We have billions of planets orbiting the sun. But what you really want a word to be is useful. You want to hear a word, say, "I know what you're talking about as you use that word." So I would have appealed to my community to step back and say, "Let's rethink the entire enterprise and find objects of like properties, like the gas giants. Let's have a term for them."
32:56 Neil deGrasse Tyson? How about the rocky objects, Mercury, Venus, Earth, Mars? They should have their own category. The belt of asteroids, it should be its own category. The icy things, their own categories. In Star Trek, they have this. There's a whole list of planet classifications. All right? And what's useful about that? If you're looking for other planets around other stars and you find a rocky planet in the Goldilocks zone, that should be a class of object. And you just say, "I found a blah blah around it." "Oh, it could sustain life." The very word would indicate that. But right now, if you say, "I discovered a planet," you gotta play 20 questions. Is it big? Is it small? Is it rocky? Is it gas? Is it icy?
33:41 Neil deGrasse Tyson? Is it this? So what the hell is the value of the word "planet" at all?
33:48 Eugene Mirman? Sounds to me like you think Pluto is a small planet. It was mine. I know. I know. Then you're mad as I see.
34:15 Neil deGrasse Tyson? Pluto was discovered in 1930. It's not until the 1970s that we even knew with precision how small Pluto actually was. Its size settled out in our measurements in the 1970s. And when we noticed how small it was, we said, "My gosh, this is not like what we thought it should have been." And textbooks around then started grouping the discussion of Pluto with other icy bodies in the comets and asteroids, the vagabonds of the solar system. And there was a discussion of Pluto. So the writing was on the wall that Pluto's days were numbered.
34:54 Neil deGrasse Tyson? Well, in the 1990s, there's a folk singer who took note of this. And I'm a big fan of when science influences the creativity of artists, where science becomes the artist's muse. And I heard this song called "Planet X." No, I will not sing it. I have something better. I will get the original writer and performer of "Planet X," Christine Lavin. Come on out, Christine Lavin.
35:30 Neil deGrasse Tyson? I want a hug from you, Christine.
35:35 Neil deGrasse Tyson? In my book, "The Pluto Files," chronicling the rise and decline of Pluto, I had to make sure that every word, every lyric from her song "Pluto X" is in an appendix of that book, because it is itself a lesson plan in the plight of America's favorite planet. And you agreed graciously at 2 o'clock this afternoon to come in here and sing this song for us. So Christine Lavin.
36:03 Speaker 06 Yo!
36:06 Speaker 06 In Arizona, at the turn of the 20th century, astromathematician Percival Lowell was searching for what he called "Planet X," because he knew deep down in his soul that an unseen gravitational presence meant a new planet spinning in the air, joining the other eight already known, circling our sun up there. But Percival Lowell died in 1916. His theory, only a theory, till 1930, when Clyde Tombaugh, in a scientific query,
36:47 Speaker 06 discovered Planet X, 3.7 billion miles from our sun, a smallish ball of frozen rock, methane and nitrogen. It joined Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. Our solar system's newest neighbor, two-thirds the size of our moon, a tiny, barely visible speck, cold, minus 440 below. Not exactly paradise, they named the planet...
37:24 Speaker 06 That same year, 1930, Walt Disney debuted his own Pluto as well. But a cartoon dog with the very same name as the CEO of Hell. Oh, that was not your normal Disney style. Most thought he was riding the coattails of Pluto mania sweeping the land, not unlike our modern love for manatees and whales. For the next five decades, mysterious Pluto captivated our minds. As late as 1978, its own moon, Charon, was seen for the very first time. But now satellites and telescopes and computer calculations
38:08 Speaker 06 say that Pluto may not be a planet at all, creating great consternations. Some scientists say that Pluto is a trans-Neptunian interloper swept away by an unknown force. Or a remnant of a wayward comet somehow sucked off course. Others say Pluto is an asteroid in the sun's gravitational pull. But if you had asked Clyde Tomball, he would have told you that's all bull. "I get hundreds of letters from kids every year," he says. "It's Pluto, the planet they love. It's not Pluto the comet, it's not Pluto the asteroid.
38:52 Speaker 06 They wonder about above." And at the International Astronomical Union, working group for planetary system nomenclature. You're probably the first audience who knows that's a real club. They too say that Pluto is a planet, reinforcing Clyde Tomball's view of nature. Norwegian Kari Exnes, professor at the Theoretical Astrophysics Institute. He too says Pluto is a planet, and a significant one to boot. But at the University of Colorado, astronomer Larry Esposito says if Pluto were discovered today,
39:37 Speaker 06 it would not be a planet. End of discussion, Tenito. He says that Pluto was definitely not spun off from solar matter like the other eight planets we know. By every scientific measurement we have, is Pluto a planet? No. And now many astronomy textbooks refer to Pluto as less than a planet. I guess if Pluto showed up at a planet convention, the bouncer might be forced to ban it.
40:10 Speaker 06 St. Christopher is looking down on this, and he says, "Pluto, I can relate." When I was demoted from sainthood, I gotta tell you, little buddy, it didn't feel real great.
40:22 Speaker 06 And Scorpios look up in despair because Pluto rules their sign. Is now reading their daily horoscope just a futile waste of time?
40:36 Speaker 06 It takes 248 Earth years for Pluto to circle our sun. It's tiny and it's cold, but of all heavenly bodies, it was Clyde Tombaugh's favorite one. Till he was 92, he worked every day in Las Cruces, New Mexico, determined to maintain the planetary status of his beloved Pluto. But how now do we deal with it? Scientists think they have proof that Pluto is never a planet. How do we handle this truth? As the PhDs all disagree, who is wrong, who is right? But wherever you are, whatever you are,
41:20 Speaker 06 Pluto, we know you're up there tonight. And on July 14th, you've got to see the New Horizons Express. Fly by and take pictures of your way cool surface to send to your webpage address. S-E-E-P-L-U-T-O-N-O-W.com. SeePlutoNow.com. You've got your own webpage for little guy Pluto. You're the bomb.
41:51 Speaker 06 Yes, at the turn of the 20th century, astromathematician Percy Waldo in his quest for Planet X started this bolter roll. But here in the 21st century, we think he may have been a little off base. So we look at the sky and wonder what new surprises await us in outer space. We look at the sky and we wonder.
42:36 Neil deGrasse Tyson? I'm out of breath just listening to that song. So the origin of that song was 10 years before the International Astronomical Union made an official vote. That song was, the genesis of that song was 1996. The IAU voted in 2006 to officially demote Pluto. And so I want to get just some concluding reflecting remarks. Just, Natalie, if you give us sort of a final reflection that we can react to. If you can just comment on the state of solar system exploration today, either in the European Union or in the United States. And where is the 10-year, 50-year horizon going to take us?
43:17 Natalie Starkey? That's a really good question. I think at the moment we're focusing.
43:22 Neil deGrasse Tyson? You got one. I finally get a good question. Thank you.
43:28 Natalie Starkey? We're focusing on asteroids as one of our main targets. They're pretty close, but they have the potential to tell us nearly as much as comets do because they form very early. Some of them are very carbon-rich and they have the potential to tell us about life on Earth and water. Some asteroids contain a lot of water.
43:46 Neil deGrasse Tyson? So when we think of rocky asteroids. Some of them also have organic
43:50 Natalie Starkey? Yep.
43:50 Neil deGrasse Tyson? Elements on them.
43:51 Natalie Starkey? And water, which, you know, it's this whole crossover which we didn't realise until a couple of years ago.
43:57 Neil deGrasse Tyson? Crossover between comets and asteroids.
43:58 Natalie Starkey? Yeah, yeah, there's this potential continuum of compositions between them. But the other things we want to do is go to some really exciting places we've never been again, which is out to the outer solar system a bit further, like to Jupiter, or we've got a moon called Europa. And this has the potential to...
44:17 Neil deGrasse Tyson? Some Europa in the house right there, yeah.
44:19 Natalie Starkey? Yeah, I know.
44:20 Neil deGrasse Tyson? Yeah.
44:21 Natalie Starkey? That's good. So we've got liquid water that might harbour life. So, you know, it's this long question, are we alone? And I think that would, if we could answer that question in our lifetime, if we found life on Mars, which we're also planning, obviously, I think that's pretty certain. We're trying to put humans on Mars. That's a whole big subject. I'm not sure how I feel about it, because, yeah, we need geologists.
44:46 Neil deGrasse Tyson? Don't get me started on that.
44:47 Natalie Starkey? Like, I want to go, but it just takes a bit of a long time to get there. But I think we need to send people into space. Some of our best samples from space are from the Apollo missions, because we sent geologists up there to pick the right rocks.
45:00 Neil deGrasse Tyson? We sent one geologist.
45:01 Natalie Starkey? One geologist.
45:02 Neil deGrasse Tyson? Just to clarify, yeah. Everyone else was a military pilot, yeah.
45:05 Natalie Starkey? The others were trained in geology, and so they knew what they were picking. But robots can't do that. Robots are slow and they can't pick as good samples. So there's a lot going on. And then we've got all these missions that are still going that are kind of out at the Kuiper Belt at the moment. And, you know, it potentially would take 30,000 years to cross the Kuiper Belt, but they'll be long dead by then. So there's an awful lot going on.
45:29 Neil deGrasse Tyson? So my favourite possibility there is life on Europa. And I've said this before, if we find life on Europa, one of Jupiter's moons, we would have to call it European, right? We'd have to, because that's what else would you call it? Scott, any reflections?
45:46 Speaker 04 I was thinking about how you have a lot of similarities to Bill O'Reilly. Because you bring very smart people on and then just tell them they're wrong.
46:04 Neil deGrasse Tyson? I saved that for the very end. I thought I was pretty well behaved the whole other time. You're a gentleman, sir.
46:11 Neil deGrasse Tyson? So, Ilana.
46:13 Speaker 03 I'm leaving here tonight thinking that all planets are not created equal. And that goes against a foundational value of mine.
46:25 Speaker 03 So I'm a little broken and lost after this experience, but I'm thinking about things.
46:33 Neil deGrasse Tyson? Eugene.
46:34 Eugene Mirman? Yeah, I mean, one, I love that we have some sort of planes that fly around collecting dust that we're learning from. I still think we should make the panels twice as big.
46:46 Neil deGrasse Tyson? The evidence here, especially delivered to us through Natalie, is that solar system exploration remains alive. It's never as much as we want it to be, or would like it to be, but it remains alive with whole bevies of scientists working on it, both sides of the pond.
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