The Stars That Guide Us, with Nainoa Thompson

Discover how the stars have guided some of our greatest adventures as Neil deGrasse Tyson, co-host Maeve Higgins, Native Hawaiian navigator Nainoa Thompson, navigation expert Frank Reed, author Dava Sobel, and Natalia Reagan explore the science of celestial navigation. NOTE: StarTalk All-Access subscribers can listen to this entire episode commercial-free here: https://www.startalkradio.net/all-access/the-stars-that-guide-us-with-nainoa-thompson/ Photo Credit: By Newportm [CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0) or GFDL (http://www.gnu.org/copyleft/fdl.html)], from Wikimedia Commons.)

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

• 0:01Neil deGrasse Tyson?

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

• 0:22Neil deGrasse Tyson?

  Welcome to the Hall of the Universe. I'm your host Neil deGrasse Tyson, your personal astro physicist, and tonight we explore the science of celestial navigation through the legacy of the great Polynesian wayfinders. And they're the ones who used the stars above to explore the vast Pacific Ocean over a thousand years ago. So let's do this.

• 0:49Neil deGrasse Tyson?

  So who do I have with me? My co-host Maeve Higgins.

• 0:51Speaker 01

  Hello.

• 0:53Neil deGrasse Tyson?

  Maeve, you're host of a podcast, Maeve in America.

• 0:56Speaker 01

  Yep.

• 0:56Neil deGrasse Tyson?

  And I was honored to be a guest on your podcast.

• 0:58Speaker 01

  You were a wonderful guest.

• 0:59Neil deGrasse Tyson?

  How did that episode go? Was it okay?

• 1:01Speaker 01

  It was one of the lower rated ones, but I appreciate the effort.

• 1:06Neil deGrasse Tyson?

  On this topic of celestial navigation, I know a little bit about it because it just uses the sky, but I would not call myself an expert. We combed the land for an expert on this, and we get Frank Reed. Frank, welcome.

• 1:18Speaker 02

  Thank you for having me here.

• 1:20Neil deGrasse Tyson?

  So you're the only one in town who can declare they're an expert in celestial navigation.

• 1:27Speaker 02

  Yes, that's what I do, yes.

• 1:28Neil deGrasse Tyson?

  Now you teach it. Who wants to learn it if you teach it?

• 1:32Speaker 02

  There's lots of different kinds of folks that want to learn it. I mean, there are people that just want to learn about history and astronomy and math, what we might call, you know, astronomy nerds.

• 1:40Neil deGrasse Tyson?

  Okay, and you're the man for that.

• 1:42Speaker 02

  I'm the man.

• 1:43Neil deGrasse Tyson?

  Very good. So we'll like heavily on your expertise tonight. And so we're featuring my interview tonight with master navigator Nainoa Thompson. Nainoa Thompson, ocean voyager who used the traditional Polynesian methods of non-instrument navigating. And what Nainoa does is reinvent some of the great voyages that we know his ancestors had taken in their exploration of the Pacific. He limits himself to only the traditional tools and methods that his ancestors invoked. And so I asked him about the first voyage that he led from Hawaii to Tahiti, and that happened back in 1980. Let's check it out.

• 2:22Speaker 03

  I was on a, what we call a Polynesian replica of a deep sea voyaging canoe. That from Hawaii to Tahiti, Tahiti's our ancestral homeland.

• 2:31Neil deGrasse Tyson?

  Okay.

• 2:32Speaker 03

  The voyage is about twenty-four hundred miles.

• 2:34Neil deGrasse Tyson?

  Wow.

• 2:35Speaker 03

  Primarily...

• 2:36Neil deGrasse Tyson?

  That's the width of the continental United States.

• 2:38Speaker 03

  Exactly.

• 2:38Neil deGrasse Tyson?

  Twenty-four hundred miles.

• 2:39Speaker 03

  Exactly.

• 2:40Neil deGrasse Tyson?

  You, you use the word canoe. And, you know, my naive sense of a canoe is it holds three people and it's tipsy and so, do I need to modify my usage of the word in this context?

• 2:52Speaker 03

  Maybe I'll use, I'll use the Hawaiian word, it's called va'a. Va'a means the equivalent to canoe. Ka'luu'a means two, two houses. The va'a ka'luu'a really was the first catamaran.

• 3:02Neil deGrasse Tyson?

  But are there beds? I mean, people are sleeping, eating, cooking?

• 3:06Speaker 03

  The va'a is sixty-two feet long, Hokulea. It's twenty feet wide, it's big. It's powered by two big sails. And if you imagine the first voyage, it came from Tahiti to Hawaii, it traveled those twenty-four hundred miles, two thousand years ago. Arguably, it might have been the greatest feat of navigation and exploration of its time.

• 3:26Neil deGrasse Tyson?

  So Frank, these Polynesian voyages, I mean, the Pacific Ocean is vast. It's the vastest thing on Earth.

• 3:33Speaker 02

  Pretty big.

• 3:34Neil deGrasse Tyson?

  Yeah, yeah, pretty, it's not only pretty big, it's like the biggest thing on Earth, right? So, how does that compare with the, the European voyages that they took to, to the New World? Much, much later, obviously.

• 3:46Speaker 02

  Well, you know, we can look at voyages that might have been nearly contemporaneous, which is, of course, the, the Norse, the, the, the people we think is the Vikings. We're crossing the Atlantic circa a thousand A.D. And this is...

• 4:00Speaker 01

  What were they using for their navigation? Those helmets?

• 4:07Neil deGrasse Tyson?

  Because you know they didn't have compasses, they didn't have telescopes, they didn't have sextants, presumably they didn't have maps. If you're going where no one has gone before, you don't have a map of where you're going.

• 4:16Speaker 02

  Yeah.

• 4:16Neil deGrasse Tyson?

  So, it's hard for any of us in modern times to even think of what it means to navigate without these tools.

• 4:23Speaker 02

  Right. It was, it was a lot riskier, you know. Modern scientific navigation, what it did was it made navigation a whole lot safer and a lot more efficient economically, which is really one of the big things that we're looking at. But... Modern navigators are not the people who discovered how to cross oceans. Crossing oceans just took some guts.

• 4:45Speaker 01

  Did they know they were going to Tahizik?

• 4:47Neil deGrasse Tyson?

  Well, I know, that's what I'm saying.

• 4:48Speaker 01

  Or were they just like, let's...

• 4:49Neil deGrasse Tyson?

  If you don't know where you're going, and this is a vast ocean...

• 4:52Speaker 02

  This is the giant question. Was it deliberate, or was it accidental? And of course, you know, there was this guy, David Lewis, who wrote We the Navigators about forty-five years ago. And, uh, and he gets it right away, which is, hey, it's three thousand years. Undoubtedly, both of these things happened. There were accidental voyages, and there were intentional voyages.

• 5:13Neil deGrasse Tyson?

  Plus, there's no record of all the voyages where they never found their destination nor ever came back.

• 5:19Speaker 02

  Right.

• 5:19Neil deGrasse Tyson?

  So, I asked Nainoa Thompson, uh, how his ancestors were able to navigate so well by the stars, right? So let's check it out.

• 5:30Neil deGrasse Tyson?

  So you guys must have known the stars really well. And, I mean, I, you know, I use my tools to remind me where they rise and set, and where to expect them, but if you don't have the tools, then it's in you somehow, and then you navigate with them. So, how do you do that?

• 5:51Speaker 03

  Okay. I mean, one issue is to even be able to identify and pick out stars, and memorize that it's a specific star, it's identification.

• 6:00Neil deGrasse Tyson?

  Right, because a star isolated is nothing, there's a context.

• 6:02Speaker 03

  Right.

• 6:03Neil deGrasse Tyson?

  A pattern that you have to... so pattern recognition matters.

• 6:06Speaker 03

  Right.

• 6:06Neil deGrasse Tyson?

  Yeah.

• 6:07Speaker 03

  But, because you can find the star in the sky, it doesn't tell you anything about navigation, you need to know primarily where it rises and sets.

• 6:14Neil deGrasse Tyson?

  Okay.

• 6:14Speaker 03

  And so there is this mental construct called a star compass.

• 6:20Neil deGrasse Tyson?

  Star compass, I like that, uh-huh.

• 6:21Speaker 03

  It's as if you're a satellite looking down at the ocean's horizon, and there's a canoe in the center of this big circle. And in the circle, is that, that circle, that is...

• 6:31Neil deGrasse Tyson?

  I got the circle, alright, here we go.

• 6:33Speaker 03

  And it's divided into thirty-two star houses. Maybe north is here, south's here, east is here, west is there. And there's seven star houses in between each quadrant.

• 6:43Neil deGrasse Tyson?

  Okay, uh-huh.

• 6:44Speaker 03

  And so, let's say this is the eastern horizon, so you can take a star and identify it, but you need to know what starhouse it is. Like, Mintaka, in Orion's Belt, rises due east, comes across the sky and sets due west, or any of the stars.

• 6:59Neil deGrasse Tyson?

  Right, okay. So you, so you've split... This, the perimeter, the horizon into these places.

• 7:08Speaker 03

  If you can identify the star, and if you know what starhouse it rises in, you can hold direction.

• 7:14Neil deGrasse Tyson?

  Hmm.

• 7:15Speaker 03

  So if you wanted to go east, you go straight towards Mintaka.

• 7:19Neil deGrasse Tyson?

  Well, that'd be easy, right, okay.

• 7:20Speaker 03

  If you wanted to go west, you go straight away from Mintaka.

• 7:22Neil deGrasse Tyson?

  And any place in between, you can know the rest of the stars to make that happen.

• 7:25Speaker 03

  And we line them up on pieces of wood on the canoe. There's actually a canoe compass that is on a deck that, that makes the thirty-two houses. So we actually, if you have a star compass, we're turning the canoe compass in the star compass and lining up different stars of different parts of the canoe to hold the desired heading.

• 7:48Neil deGrasse Tyson?

  So Frank, do you keep stars in your head?

• 7:50Speaker 02

  Yeah.

• 7:52Speaker 02

  And you do too, you know, you.

• 7:54Neil deGrasse Tyson?

  I do, but not just because I, just because it's fun, not because I need it to not die.

• 7:59Speaker 02

  Right, right, right.

• 8:01Speaker 01

  Less urgency.

• 8:02Neil deGrasse Tyson?

  Yeah.

• 8:02Speaker 02

  But it's a pattern recognition thing, you know? You can, you can, you can see patterns and, and they pop right out at you. You, you know when the stars are right and when they're wrong. If you saw a movie and it.

• 8:12Neil deGrasse Tyson?

  What does that mean, wrong stars?

• 8:13Speaker 02

  Oh, you know, if there was like the last scene of a movie when, you know, say somebody's sinking under the waves.

• 8:17Neil deGrasse Tyson?

  The Titanic.

• 8:18Speaker 02

  Yeah, you recognized that right off the top of your head, didn't you?

• 8:21Neil deGrasse Tyson?

  Yeah, I called that out.

• 8:22Speaker 02

  So, but.

• 8:23Neil deGrasse Tyson?

  James Cameron did not have the correct sky over the sinking Titanic in his movie.

• 8:27Speaker 01

  Is that what you noticed when Jack was drowning?

• 8:31Neil deGrasse Tyson?

  It was all I could think of when that was happening.

• 8:34Speaker 01

  So that's why you were crying when everybody else was like, die!

• 8:37Neil deGrasse Tyson?

  Yeah, I was, uh, yeah.

• 8:39Speaker 02

  Some of us were multitasking, okay?

• 8:41Neil deGrasse Tyson?

  Yeah, thank you, I was multitasking. Yeah, so you're right, so I did catch it. I, I did, I caught that it was wrong.

• 8:47Speaker 02

  And I saw that it was wrong in a second too, because, because I know the sky this way. It's a pattern matching thing, you know? I can see it, I can pattern recognize it.

• 8:54Neil deGrasse Tyson?

  So in addition to the patterns, what tools do you use?

• 8:57Speaker 02

  For celestial navigation, we use sextants and, and we're measuring the altitudes of the stars above the horizon.

• 9:03Neil deGrasse Tyson?

  Okay, so you've used, you're, you're comfortable with a sextant?

• 9:05Speaker 02

  Oh, yeah.

• 9:06Neil deGrasse Tyson?

  So I pull this from my office.

• 9:07Speaker 02

  Yeah, sure, this sits on your shelf.

• 9:08Neil deGrasse Tyson?

  This is a vintage sextant.

• 9:09Speaker 02

  Yeah, it's actually a quintant, which makes it even more rare.

• 9:12Neil deGrasse Tyson?

  Ooh.

• 9:13Speaker 02

  It's quite exotic.

• 9:14Neil deGrasse Tyson?

  Ooh.

• 9:14Speaker 02

  But yeah, it's, they're all, it's perfectly fine to call them all sextants.

• 9:19Neil deGrasse Tyson?

  You're saying this is one-fifth of a circle, not one-sixth?

• 9:21Speaker 02

  Right, right.

• 9:22Neil deGrasse Tyson?

  A sext would be a sixth.

• 9:24Speaker 02

  Uh huh.

• 9:24Neil deGrasse Tyson?

  I never knew that about my own sextant.

• 9:26Speaker 02

  Yeah, yeah.

• 9:26Speaker 01

  It's not a sextant.

• 9:27Neil deGrasse Tyson?

  Apparently, it's a quintant.

• 9:29Speaker 01

  Oh.

• 9:29Neil deGrasse Tyson?

  Yeah, yeah.

• 9:30Speaker 02

  It's, it's, it's one up, it's not one down.

• 9:32Speaker 01

  Oh, better.

• 9:33Speaker 02

  Yes, yes, yes.

• 9:33Speaker 01

  Ah.

• 9:34Neil deGrasse Tyson?

  Oh, yeah, I knew that, yeah, yeah, yeah.

• 9:37Speaker 01

  Wait, so what is it? It's like little mirrors and little telescopes and...

• 9:40Speaker 02

  It's two mirrors that let you look in two different directions at once. So what this device does...

• 9:45Speaker 01

  That would be good for makeup, you know?

• 9:48Speaker 01

  You could see the back.

• 9:50Speaker 02

  It lets you superimpose two different directions, so you can look in two directions at once. So you can see the sun up in the sky and the horizon out in front of you. And what you do is you line up these two different views. And when they're lined up just so, you can read off the angle between them from the scale at the bottom of the instrument.

• 10:06Neil deGrasse Tyson?

  What does it mean that, that Apollo had a sextant? I, I read about this, I didn't believe it. It was a combination of not believing it and not understanding why.

• 10:13Speaker 02

  Right, right. So they built a sextant right into the hull of the command module of the Apollo spacecraft. And it was a real sextant, and it was coupled directly to that, to that really spectacular computer that they had aboard with its, you know, its 12K of RAM, which sounds crazy to us. But, but, but, but it was a really powerful...

• 10:32Neil deGrasse Tyson?

  Well, so we have more computing power than that, and we don't know how to get to the moon anymore. So, so we've regressed, as far as I can tell.

• 10:38Speaker 01

  How mu- how much is 12K? It's like a...

• 10:40Neil deGrasse Tyson?

  It is, it is the size of one of your emails.

• 10:42Speaker 02

  You can't imagine how small it is. You can't imagine.

• 10:45Speaker 01

  So that, and then a sextant?

• 10:47Neil deGrasse Tyson?

  It's a fraction of the size of one of your emails.

• 10:49Speaker 01

  Wow.

• 10:49Neil deGrasse Tyson?

  Right. So, so, so what would they use it for?

• 10:52Speaker 02

  So this sextant that they had about, aboard the Apollo spacecraft, they originally thought that they were going to navigate at least back from the moon using the sextant. Because you know what they were worried about?

• 11:02Neil deGrasse Tyson?

  No.

• 11:03Speaker 02

  They thought that the Russians might try to jam on the navigation on the way... See, that was the height of the Cold War when this thing was built. This, the, the, the sextant and the computer were designed right at the beginning.

• 11:14Speaker 01

  And were they worried because the, the stars would look different up there? Like, even if they had like those star maps in their minds? If you're like on the moon, wouldn't they look...

• 11:22Neil deGrasse Tyson?

  No, no, you're not that far away.

• 11:23Speaker 01

  Oh, you're not far away.

• 11:24Neil deGrasse Tyson?

  The stars are so far away compared to the Earth-Moon system. You go to the moon, it's not, it's not, no.

• 11:28Speaker 01

  Really?

• 11:29Neil deGrasse Tyson?

  Yeah.

• 11:29Speaker 02

  And you still need to measure it to get... But what, what they originally thought was that they were going to determine their position using this sextant. They were going to fix where they were in space, how far they were from the moon, on what vector and all that.

• 11:41Neil deGrasse Tyson?

  Today, this is obsolete. Is there any reason for anyone to still know how to use this?

• 11:46Speaker 02

  Sure, you can buy a brand new one on, uh, right tomorrow. I mean, they still sell them retail.

• 11:50Neil deGrasse Tyson?

  Why would anyone, I can, who, why?

• 11:57Speaker 02

  Okay, uh, uh, first of all...

• 11:59Neil deGrasse Tyson?

  So you pull this out and you're flipping mirrors and looking on the horizon and hoping it's not cloudy out and you're, and you're hoping it's at night so that there's a star to look at. And I pull out, I say, "Siri, where am I?"

• 12:09Speaker 01

  Yeah.

• 12:10Neil deGrasse Tyson?

  That...

• 12:11Speaker 02

  Yeah, that's fine. Now, suppo- Okay, okay, okay. What, what's the best backup to, to a GPS?

• 12:18Neil deGrasse Tyson?

  Well, I suppose I don't need a backup.

• 12:19Speaker 02

  What's the best backup to a GPS?

• 12:21Neil deGrasse Tyson?

  What's the best backup to your car? Is it, is it a horse? No, you gave up on horses a hundred years ago.

• 12:26Speaker 02

  Exactly, exactly.

• 12:27Neil deGrasse Tyson?

  There's a point where you give up on the old stuff.

• 12:29Speaker 02

  This is, this is exactly where I'm going. What's the best backup to your car? It's your wife's car, right? So the best backup to a GPS is another GPS. And what's the best backup to that second GPS? A third GPS. GPS, uh, using celestial navigation today isn't about backing up. It's about double checking. It's about sanity checking.

• 12:48Neil deGrasse Tyson?

  Okay.

• 12:49Speaker 02

  So one of the most important things that you can do with celestial navigation is you can validate that the GPS is providing you real information. There are two ways that it might not be. I mean, not from your cellphone. Your cellphone's gonna be right. But suppose you're a mariner at sea. Now, there's these guys called pirates. And these days, the pirates are technologically sophisticated. So what if they're feeding false GPS signals into the airwaves?

• 13:18Speaker 01

  They do that?

• 13:20Speaker 02

  Yes.

• 13:21Speaker 01

  They do?

• 13:22Neil deGrasse Tyson?

  It seems to me if they're that smart, they can find another way to make money than pirating other ships.

• 13:26Speaker 01

  Yeah.

• 13:27Neil deGrasse Tyson?

  Yeah.

• 13:28Speaker 01

  They could just, like, start a club or something.

• 13:32Neil deGrasse Tyson?

  So, you know, recently Disney, back in 2016, Disney released the film Moana. It's about a native Hawaiian girl's journey of discovery across the ocean. And the main character, Moana, she uses traditional Polynesian techniques to navigate by the stars. So, so what did you think of the film, Frank?

• 13:52Speaker 01

  I'm so worried you're gonna drag it like Titanic.

• 13:54Speaker 02

  I'm gonna just drag it through the dirt and geek it out. No, I'm not, I'm not, I'm not at all. It's beautiful and it's, it's, it's heartwarming and it's terrific. You know, there's a, there's a line in, in one of the main songs. It's Lin-Manuel Miranda, so you can't go wrong there. And, and one of the lines is, "At night, we name every star, we know where we are, we know who we are." And that's the essence, I think, of what, what Nyona Thompson is doing. Exactly. So they, they put some real effort into making, getting this right.

• 14:23Neil deGrasse Tyson?

  Well, this ancient art was never written down and had to be passed down orally. And if there's any part where someone forgets to tell somebody else, it gets broken and lost. And so part of Nyona Thompson's mission is to try to rediscover what was not passed continually down through time. And so, no matter how master a navigator you are, you can't follow stars in the daytime.

• 14:50Speaker 01

  Yeah.

• 14:51Neil deGrasse Tyson?

  Except for the one star that's closest to us, the sun. So I had to ask him about that. Check it out.

• 14:57Speaker 03

  The daytime is the hard part. Sunrise, sunset's the most important time of the day. So let's say, let's say it's March 21st and the sun's rising on the equinox, it's zero.

• 15:08Neil deGrasse Tyson?

  So this is the spring equinox.

• 15:10Speaker 03

  Right.

• 15:11Neil deGrasse Tyson?

  And the sun is rising exactly due east.

• 15:12Speaker 03

  Right.

• 15:13Neil deGrasse Tyson?

  And we'll set exactly due west, the only one of two days where that happens, okay.

• 15:17Speaker 03

  So we're in an imaginary voyage from Hawaii to Tahiti, we're heading south. You really wanna hope that the sunrise is gonna be on your port, if you're looking forward, your left side beams. It's ninety degrees from your, your, your heading. The big challenge, middle of the day, when the sun gets up too high, you don't, you don't know where it came up.

• 15:37Neil deGrasse Tyson?

  Yeah.

• 15:38Speaker 03

  That's where...

• 15:40Neil deGrasse Tyson?

  By the way, that's only a problem near the equator, because you, I mean, the equator, it, the sun essentially, at noon goes directly overhead.

• 15:50Speaker 03

  Right.

• 15:51Neil deGrasse Tyson?

  And then it could've come from anywhere.

• 15:52Speaker 03

  Right.

• 15:52Neil deGrasse Tyson?

  But if you're like way north or way south, the sun, you know, it's a low arc across the sky. And you're saying, oh, it probably came from somewhere over there and it's gonna land somewhere over there. Yeah.

• 16:03Speaker 03

  You're very smart, because that's why the system's a tropical system. You take this system to Alaska and try navigate, because the movement of the celestial bodies are more horizontal than the vertical, it doesn't work. Well, I bet it doesn't work, but it, but it becomes much, much more inaccurate.

• 16:20Neil deGrasse Tyson?

  Mm-hmm.

• 16:21Speaker 03

  Even when we sail to New Zealand, we only, we only use stars that rise from the equator out forty-five degrees.

• 16:28Neil deGrasse Tyson?

  Yeah.

• 16:29Speaker 03

  We don't use them near the poles, cuz they're not accurate enough.

• 16:32Neil deGrasse Tyson?

  Mm-hmm.

• 16:33Speaker 03

  They're much more to horizontal.

• 16:34Neil deGrasse Tyson?

  Right, they start skimming the horizon. Right, right, much, much harder to measure that.

• 16:38Speaker 03

  Right.

• 16:39Neil deGrasse Tyson?

  Oh, I, I hadn't thought that through, but of course.

• 16:41Speaker 03

  We use half the stars.

• 16:42Neil deGrasse Tyson?

  Yeah.

• 16:42Speaker 03

  In New Zealand. Alaska, we wouldn't do it.

• 16:46Neil deGrasse Tyson?

  So, so Frank, is there an ideal latitude where all these measurements are perfect for you?

• 16:52Speaker 02

  No, we can obviously correct for them in any way we want, but there are differences in the way things work in different latitudes. Uh, certainly, if you're in the tropics, there are approximations. That's how we would think about it today. There, there are rules of thumb that we can work with that work much better. Uh, for example, within the tropics...

• 17:10Neil deGrasse Tyson?

  The tropics is twenty-three and a half degrees north and south of the equator.

• 17:13Speaker 02

  Uh-huh.

• 17:14Neil deGrasse Tyson?

  That's a tropics, okay.

• 17:15Speaker 02

  Sure, sure. And so, and so, for example, the star, uh, uh, Arcturus will rise, oh, I think it's, it's, uh, nineteen degrees to the north of east, and it'll set nineteen degrees to the, to the north of west. And that's a fixed number. The, the star Zubanel Janubi, I always...

• 17:31Neil deGrasse Tyson?

  Love that star.

• 17:33Speaker 02

  It'll rise 16 degrees to the south of east and set 16 degrees to the south of west. And those numbers will not change much within the tropics. It's because the, if you want to do the math geek stuff on it, it's because the cosine of a number doesn't change much around zero. You can ask your phone, you can talk to your phone, you can say, "Okay, Google, what is the cosine of 10 degrees?" And it'll come back and it'll tell you. And you'll see that it's only off by 1.5% or something like that. And I hope people are doing that right now.

• 18:04Speaker 01

  I wonder what would happen if you asked a sextant, he'd be waiting.

• 18:09Speaker 02

  It's not as smart, it's not as smart.

• 18:10Speaker 01

  But I'm still not clear on like when there's no stars, like how do you know which way to go?

• 18:16Speaker 02

  You don't, you just sit around and wait.

• 18:17Speaker 01

  You do, really?

• 18:18Neil deGrasse Tyson?

  You wait till it's dark.

• 18:19Speaker 01

  For all those hours, so you work at night, basically?

• 18:22Neil deGrasse Tyson?

  I guess so.

• 18:23Speaker 02

  It's one way out of it. Or, you know, what if it's cloudy? Well, what do you do if it's cloudy? You go home or you...

• 18:29Neil deGrasse Tyson?

  You drift aimlessly at sea until you can, a star shows up.

• 18:34Speaker 02

  Until you, yes, you can reset.

• 18:36Neil deGrasse Tyson?

  Well, coming up, we will explore the navigational quandary that is one of science's all-time greatest challenges. And this is the longitude problem when StarTalk returns.

• 18:58Neil deGrasse Tyson?

  Welcome back to StarTalk. We're talking about the art and science of ocean navigation. And joining us now to share some of this historical perspective is science writer, journalist, Dava Sobel. Welcome.

• 19:16Neil deGrasse Tyson?

  She was one of our first guests in like the first season of StarTalk, even before we were on television. Welcome back. And back then, we interviewed you, your mega bestseller, Longitude, which of course is still available. You've got another book that you just published, The Glass Universe, about the women at the Harvard College Observatory.

• 19:33Speaker 04

  You're Sisters of the Sun.

• 19:34Neil deGrasse Tyson?

  Sisters of the Sun. They basically discovered how stars work, but single-handedly. It's a remarkable story, but that's not why we have you on the show.

• 19:42Speaker 04

  Okay.

• 19:42Neil deGrasse Tyson?

  No, not this book.

• 19:43Speaker 04

  But thank you.

• 19:44Neil deGrasse Tyson?

  Great, but that's not why.

• 19:47Neil deGrasse Tyson?

  Longitude.

• 19:50Neil deGrasse Tyson?

  So tell me, could you just summarize for everyone what the longitude problem is? So we have latitude, which is zero, the equator is zero. And we just by convention use degrees, this thing called degrees, which is an angle. We go from zero to ninety, north pole, zero to minus to south ninety, south pole. So that's latitude. And that's easy, you just get the elevation of Polaris above the horizon. So that, so that we got that. So longitude would just be east and west of some standard.

• 20:20Speaker 04

  Right, but the Earth is turning all the time, so it's hard to get something as a landmark, a sky mark.

• 20:27Neil deGrasse Tyson?

  Because the stars find themselves over different parts of the Earth throughout the day. So there's no anchor.

• 20:36Speaker 04

  There's nothing that holds still for you, the way the North Star would help you find your latitude.

• 20:41Neil deGrasse Tyson?

  Okay.

• 20:42Speaker 04

  The problem boils down to knowing what time it is in two places at once. If you can do that, you can determine your longitude.

• 20:51Neil deGrasse Tyson?

  Okay.

• 20:51Speaker 04

  So you could have a clock with you that would tell the time at your home port or any place of known longitude. And then as you travel, you keep establishing your local time by the Sun. And so you always have a comparison. You have the home port time, and you have your local time, and then you can do the math and figure out where you are.

• 21:15Neil deGrasse Tyson?

  Do the math, you hear that? That's a, it's a.

• 21:18Speaker 04

  You can never get away from doing the math. And that was understood very early on, certainly by the early 1500s. People knew if they could do that, they could get where they wanted to go, but the technology didn't exist.

• 21:34Neil deGrasse Tyson?

  So you can keep time very accurately with sort of pendulum clocks, right? But of course, that's, if you're on a rocking ship. Then it interferes with the rhythms of your pendulum, or anything that has a kind of a gravitational rhythm to it. So this is what they had to overcome.

• 21:51Speaker 04

  Exactly.

• 21:52Neil deGrasse Tyson?

  It was hard.

• 21:52Speaker 04

  It was very hard.

• 21:53Neil deGrasse Tyson?

  Well, we're featuring my interview with traditional Polynesian ocean voyager, Nainoa Thompson, and I had to ask him how the ancient Polynesians navigated 2,400 miles from Hawaii to Tahiti without being able to calculate longitude. Let's check it out.

• 22:11Speaker 03

  Okay, imagine, imagine.

• 22:15Speaker 03

  You're standing on the beach of Waikiki. You're looking over the horizon to where Tahiti is. And then imagine you draw one line, like an arc, to the west side of Tahiti and the other line to the east side. That's your target. It's less than a degree.

• 22:30Neil deGrasse Tyson?

  So, your destination is not in view because it's far beyond your horizon. So, your destination spans an angle from where you're standing.

• 22:43Speaker 03

  In Waikiki.

• 22:44Neil deGrasse Tyson?

  And as long as you navigate inside that angle, nothing else matters.

• 22:48Speaker 03

  Right.

• 22:49Neil deGrasse Tyson?

  Because you're gonna get to your target on the other side.

• 22:50Speaker 03

  Really, really smart.

• 22:51Neil deGrasse Tyson?

  Wait, wait. In fact, it seems to me, your angle can be wider than that because you just have to get your destination within your horizon and then you can just dead reckon to it.

• 23:02Speaker 03

  Right, 15 miles.

• 23:02Neil deGrasse Tyson?

  Yeah, yeah, 15 miles. So you have a 30 mile, so it's really the width of 30 miles at the distance of where you're headed. That's your angle.

• 23:10Speaker 03

  2,400 miles away, though.

• 23:14Neil deGrasse Tyson?

  So, so, so. Right, so it's 30, yeah, so it's, it's narrow, but still, it's a known problem.

• 23:19Speaker 03

  Right. So, but, there's so many unknowns in the navigation that it's not, it's not a GPS. It's not a coordinate system. You don't have longitude. You need, you need instruments and you need tables, which we don't have. It's a dead reckoning system. So you only know where you are by memorizing where you come from. If you memorize where you come from, that meant you gotta be awake. You know, we stay up 21, 22 hours a day. So, it ain't easy.

• 23:48Neil deGrasse Tyson?

  Here's what you do. Here's what you do.

• 23:52Neil deGrasse Tyson?

  Slip this in your coat. Don't tell anybody, okay? So, what, that's that same sex.

• 24:00Speaker 03

  I see he didn't take it.

• 24:01Neil deGrasse Tyson?

  No, he didn't take it. No, no, no.

• 24:03Speaker 01

  He doesn't need it, that's the whole point. He's like, "I got this."

• 24:08Neil deGrasse Tyson?

  So if you know where you are and other people don't, then you're in charge. That's what this comes down to. Yeah. And so the Brits, their power rose in the 18th century and 19th century because they valued this.

• 24:18Speaker 04

  Oh, yes. Oh, oh, there was a huge prize offered to spur technology. People knew that somebody had to come up with a practical method. Who was offering the prize? The Parliament. Oh, they were? Yeah.

• 24:33Neil deGrasse Tyson?

  How much money was it?

• 24:34Speaker 04

  It was 20,000 pounds, but in 1714, so...

• 24:38Neil deGrasse Tyson?

  That's a lot of money.

• 24:39Speaker 04

  Millions of dollars, yeah.

• 24:40Neil deGrasse Tyson?

  Oh, my gosh. So what solution did John Harrison, the one...

• 24:45Speaker 04

  The hero of the story.

• 24:46Neil deGrasse Tyson?

  Yeah, yeah. How did he solve the problem?

• 24:49Speaker 04

  He managed to build a clock that was not affected by the motion of the ship and... A digital, digital clock.

• 24:59Speaker 04

  There you go. So instead of a free pendulum that had parts that were connected by springs, you could practically turn it upside down and it would still keep beating. And he also conquered the problem of changing temperature. To win the prize, you had to sail from England to a warm climate like Jamaica, Barbados. And so there's a huge temperature change and...

• 25:26Neil deGrasse Tyson?

  That's part of the parameters of the prize winning.

• 25:29Speaker 04

  Right. So the, the parts of the clock would, would, would expand in the heat. And he had to design around that and he managed to do it.

• 25:39Neil deGrasse Tyson?

  This is completely brilliant.

• 25:40Speaker 04

  Yeah, yeah.

• 25:41Neil deGrasse Tyson?

  So what year did this seaworthy chronometer get introduced?

• 25:45Speaker 04

  It was the middle of the 18th century.

• 25:47Neil deGrasse Tyson?

  And then England takes control of the world after this.

• 25:50Speaker 04

  Yeah.

• 25:51Neil deGrasse Tyson?

  So they get to say the sun never sets on the British Empire.

• 25:53Speaker 04

  The British Empire, yeah.

• 25:54Neil deGrasse Tyson?

  Because they invented the damn clock to enable them to do so.

• 25:57Speaker 04

  And he only got 20 grand.

• 26:01Neil deGrasse Tyson?

  Well, coming up, more on the science of celestial navigation when StarTalk returns.

• 26:14Neil deGrasse Tyson?

  Welcome back to StarTalk from the American Museum of Natural History in New York City. We're talking about the science of navigation by the stars. We're featuring my interview with ocean voyager and master navigator Nainoa Thompson. He's a native Hawaiian, and I had to ask him about his ancestors' first voyage to Hawaii. Let's check it out. When I think of navigation, I think I'm here and I want to get there. Okay? But the discoverers of Hawaii are not saying, "Let's find Hawaii today." This is not on their docket. They must simply be exploring. They were finding another planet.

• 26:58Speaker 03

  Right, right.

• 26:59Neil deGrasse Tyson?

  2,000 years ago.

• 27:00Speaker 03

  So, go back 7,000 years ago. Go to South China Sea. The first kind of maritime culture was designed. It was first to go to sea, but not far. But once they got to Western Polynesia, and the next jump was against the trade winds, the easterly winds, they get into Central Polynesia. That would be the Cook Islands. That would be Tahiti. Now, that, our guess is it took 1,000 years for them to build a vehicle and find a navigator, train the navigator, figure out how to navigate deep-sea, open ocean. So, let's say, then they get into Central Polynesia. Now, they're in Tahiti about time of Christ, and somebody made this voyage to Hawaii. Did they know where Hawaii was? How would they know?

• 27:45Speaker 03

  Probably not. So, then the question was, why did they? What was the motivation for voyaging?

• 27:56Neil deGrasse Tyson?

  Why would anyone do this? This is a question. And we have Nataya Regan in studio. Nataya!

• 28:07Neil deGrasse Tyson?

  Thanks for joining us. Thank you for having me. Natalia is an anthropologist and she's one of our StarTalk science correspondents. So Natalia, what can you tell us about the Polynesian voyagers who discovered the Hawaiian Islands?

• 28:20Speaker 05

  Well, humans have been on the move since the dawn of us becoming a species. And anthropologists have to get creative when they want to understand why and how they did this migratory movement. And they look at things like language similarities, skeletal remains, genetic markers, radiocarbon dated artifacts, and oral histories to undetermine basically who were these first Hawaiians. And because science is not always easy, we don't know exactly who or when the first Hawaiians arrived. It's putting together pieces of a puzzle. And that's what makes, I feel like, anthropology and science so interesting, is every day you're gathering more and more data, and as you gain more data, your theories change.

• 28:58Neil deGrasse Tyson?

  Well, thank you for coming to StarTalk.

• 29:01Speaker 05

  Thank you.

• 29:02Neil deGrasse Tyson?

  Natalia, yeah.

• 29:06Neil deGrasse Tyson?

  That brings us to the part of the show called Cosmic Queries.

• 29:12Neil deGrasse Tyson?

  This is where we answer questions from our fanbase, drawn from all over the internet. And tonight, you've solicited questions about the science of navigation.

• 29:21Speaker 05

  Yeah.

• 29:22Neil deGrasse Tyson?

  I haven't seen the questions, but if there's about navigation, I might get one or two, but Frank is gonna have to get all the rest. I can have two, yes. Okay. All right. What do you have?

• 29:31Speaker 01

  Here, our first question is from Frank Kane. He's in Orlando, which is in Florida.

• 29:33Neil deGrasse Tyson?

  Orlando. Florida's Space Coast.

• 29:35Speaker 01

  Space Coast.

• 29:36Neil deGrasse Tyson?

  In Florida, yeah.

• 29:37Speaker 01

  And this is his question. How did early spacecraft like Voyager navigate without the benefit of digital computers or cameras?

• 29:44Neil deGrasse Tyson?

  Well, they had cameras. They had cameras. Plus, we know where the bright stars are in the night sky. And, or in the sky at all. Because when we think of day and night on Earth, it's daytime because sunlight scatters into the atmosphere, preventing you from seeing stars. But on the moon, you can see stars in day and night. This night-day thing is an atmospheric Earth phenomenon. When you're out in space, there's stars everywhere at all times. So NASA's list, they just get the brightest stars north and...

• 30:12Speaker 02

  Sure, yeah.

• 30:13Neil deGrasse Tyson?

  That's all it is?

• 30:14Speaker 02

  Well, it depends. I mean, the early star trackers on these spacecraft, they were, of course... Sensitive only to low intensity light, so they could just see the brightest stars. So Sirius and Canopus, those are good stars to use. Arcturus, Vega.

• 30:28Neil deGrasse Tyson?

  Yeah, yeah, top 10 brightest stars.

• 30:30Speaker 02

  Another big thing, of course, is that these spacecraft are tracked. So we're talking about air traffic control. You know, they can see them. And so they track.

• 30:39Neil deGrasse Tyson?

  The Deep Space Network knows where they are.

• 30:41Speaker 01

  Yeah.

• 30:42Neil deGrasse Tyson?

  At all times.

• 30:42Speaker 01

  There's probably some guy really near him in Florida. Who's like, "Tell him." Okay, this question comes from Brian Vedder. How do you navigate when traveling near the speed of light? Must it be planned, or can you make adjustments along the way?

• 30:54Neil deGrasse Tyson?

  Yeah, if you have that much momentum in one direction, it's gonna be kinda hard to like stop and turn around or make a left turn. So, but if you accelerate it to near the speed of light, you know where you're going. I presume, right?

• 31:08Speaker 02

  You know, there was this movie Passengers?

• 31:09Neil deGrasse Tyson?

  Yeah, it's on my list.

• 31:10Speaker 02

  And there's a silly scene where this interstellar craft, which is traveling something like 30% of the speed of light, it's not clear. They do a gravitational slingshot past Arcturus. And you know, Arcturus, that's Hokulea by the Hawaiian name. So we have this scene where this ultra-relativistic spacecraft bends its trajectory by swinging past us. No.

• 31:34Neil deGrasse Tyson?

  No, no, no, it's just gonna go straight by.

• 31:37Speaker 01

  Isn't that what the little Voyagers did? Didn't they like?

• 31:40Neil deGrasse Tyson?

  Yes, they did, but they're not going 30% the speed of light. That's the issue here.

• 31:44Speaker 01

  Right.

• 31:45Neil deGrasse Tyson?

  Yeah, so the Voyager spacecraft didn't have enough energy to leave the solar system entirely when they were launched. But now they do have that much energy. Where'd they get it? They basically stole it by slingshotting around, they get gravity assistance around multiple planets. Instead of multiple planet, it's like a multiple banked pool shot.

• 32:05Speaker 01

  Yeah.

• 32:06Neil deGrasse Tyson?

  Right, like, shh, shh, shh. Then it, so it steals orbital energy from Jupiter and from Saturn and Uranus, and then it's got enough energy to leave the solar system entirely.

• 32:15Speaker 01

  The coolest idea ever.

• 32:17Neil deGrasse Tyson?

  Coolest ever.

• 32:18Speaker 01

  I have a final.

• 32:18Neil deGrasse Tyson?

  Oh, final. Okay, so a final, yeah.

• 32:20Speaker 01

  Okay, this is from Fersi Leon. When lost in space, how does one find their way back to Earth?

• 32:25Neil deGrasse Tyson?

  If you're lost.

• 32:29Speaker 01

  You're not.

• 32:30Neil deGrasse Tyson?

  You're lost.

• 32:30Speaker 01

  You're not able to find your way back.

• 32:31Neil deGrasse Tyson?

  Right, that's how I look at it. Would you, would you agree, sir?

• 32:34Speaker 01

  How would you try?

• 32:35Speaker 02

  Oh, okay, what are some, what are some things that you might try? Uh, let's say you're, you're lost twenty light years from Earth. You might do something like look for the solar spectrum. You know, you could, you could start pinging stars and looking for the specific spectrum of the sun.

• 32:47Neil deGrasse Tyson?

  That matches what you know the sun to be.

• 32:49Speaker 02

  Yeah, yeah.

• 32:50Neil deGrasse Tyson?

  Okay, that's good. But otherwise, yeah, just, just kiss your ass goodbye.

• 32:54Speaker 01

  Accept it.

• 32:57Neil deGrasse Tyson?

  So, up next, we will find out how the Polynesian voyagers navigated across the Pacific using only the signs of nature when StarTalk returns.

• 33:17Neil deGrasse Tyson?

  We're back on StarTalk from the American Museum of Natural History. And we're exploring the ancient art of celestial navigation, joining the sea, the sun, and the stars. I asked traditional Polynesian voyager Nainoa Thompson what his greatest navigational fear might be. So let's check it out.

• 33:38Speaker 03

  My first voyage, I, I, I over-studied the stars because I, I wanted...

• 33:41Neil deGrasse Tyson?

  No, no, you don't over-study the stars.

• 33:43Speaker 03

  Yeah.

• 33:44Neil deGrasse Tyson?

  Not, don't come in my office and say you over-studied the stars. Give me a different sentence, go.

• 33:49Speaker 03

  Well, okay, so I studied, I, I put the vast amount of my time, my available study into the stars.

• 33:55Neil deGrasse Tyson?

  Oh, so you missed, you didn't study something else?

• 33:56Speaker 03

  So I was trying to be like perfectly accurate when I could see.

• 33:59Neil deGrasse Tyson?

  Okay.

• 34:00Speaker 03

  But my first voyage in 1980, I feared the most cloudiest place on the earth. It's called the Intertropical Conversion Zone. It's halfway between Hawaii and Tahiti. It's where the northeast trade winds and the southeast trade winds essentially collide. Just north of the equator, cloudiest place on the, on the earth and the rainiest place on the earth.

• 34:19Neil deGrasse Tyson?

  Yeah, the equator's not known for clear weather. That's why we put telescopes in desert latitudes, north and south. Typically thirty degrees north, thirty degrees south is where we put our telescopes. Yeah, if you're crossing the equator, you, you're gonna have some non-navigational days.

• 34:35Speaker 03

  And the band is normally about three hundred miles wide. And so, um, I feared it because actually, learning the stars...

• 34:46Speaker 03

  Was the easiest part of navigation. Because there are points of light that you can identify in the sky. And you can memorize mathematically what they rise and what they said. When nature takes that away and blinds you essentially. Your question is really what separates the master from the novice.

• 35:06Neil deGrasse Tyson?

  So Frank, master and novice. What's the difference? Navigationally, what's the difference?

• 35:13Speaker 02

  Yeah, right. This is something that's different between a traditional form of navigation and a modern form of navigation. You know, a modern navigator can be taught to be an expert in two weeks. Four weeks tops. You don't have to go beyond that. But for the kind of navigation that Nainoa is talking about. One of those key things is that ability to see patterns. To be able to see a few stars through a break in the clouds. And say, oh, that's Regulus. Now, that kind of pattern recognition, that takes years and I'm not sure how long it takes because I just grew up doing that myself and I don't know.

• 35:50Neil deGrasse Tyson?

  People will, there'll be a part in the clouds. A star will show up and people say, what star is that? I just have no idea.

• 35:57Speaker 02

  If there's a few extra stars.

• 35:58Neil deGrasse Tyson?

  I need some more stars.

• 35:59Speaker 01

  Aren't you ever tempted to just be like, that's blah, blah, blah. And like, nobody's gonna be like, no, it isn't. Like, you can just even make up a word.

• 36:07Neil deGrasse Tyson?

  Yeah, yeah.

• 36:08Speaker 01

  And they'll be like, I knew it, that man, he's a genius.

• 36:12Neil deGrasse Tyson?

  Yeah, no, that's not how I roll.

• 36:14Speaker 01

  No?

• 36:15Neil deGrasse Tyson?

  No, no.

• 36:15Speaker 01

  You just say, I don't know.

• 36:16Neil deGrasse Tyson?

  Yeah, yeah, yeah, I'll just say, I need fewer clouds before I can make this judgment. And so, Nainoa Thompson, he told us about this star compass that the Polynesians used to, for their dead reckoning. And he explained how a master navigator can use that concept to navigate without a single star in sight.

• 36:39Speaker 01

  Oh, really?

• 36:40Neil deGrasse Tyson?

  And I said, I don't know how you do that. So let's check it, check it out.

• 36:45Speaker 03

  In the star compass, we hold the sun, we hold the moon, the house during the year and the house during the month. We hold ocean waves, we hold the wind, we hold flight paths of birds. We hold every single

• 36:58Neil deGrasse Tyson?

  Cue.

• 36:59Speaker 03

  Cue is, needs to be placed into some framework that you can understand where it's coming from or where it's going. If you see seaweed from the reefs, you know the island's upcurrent. You can see shallow lagoons underneath clouds that turn turquoise. You can see wave refraction or absence of wave when the wave breaks it off and if it's upwind of you. But the main best friend on the oceans besides the stars is a seabird. There's two species that live on the island, fly out to sea and come back.

• 37:35Neil deGrasse Tyson?

  By an amount that you know?

• 37:36Speaker 03

  Yeah.

• 37:37Neil deGrasse Tyson?

  By a distance that you

• 37:38Speaker 03

  Hundred twenty miles, yeah. So this, there's two, one only flies ten miles and you don't need that bird because you see the land. But the other one's called Manu Oku, it's a white tern. This bird will fly out a hundred twenty miles and then it'll fish somewhere in that distance. That's its range and it'll come back.

• 37:57Neil deGrasse Tyson?

  You can just follow it back?

• 37:58Speaker 03

  And we use the stars, the altitude of stars and the meridian that tells latitude. And we just dead reckon in the cone, stay in that cone. And then we, we wait for the first white bird. And when we see the Manu Oku, in the day, they fly like butterflies, just small turns and they, and they pick off the water. But when, when the sun gets low in the afternoon, they rise and they fly direct. To your point, path of the, flight path of the bird is, is, is the path to the island.

• 38:29Neil deGrasse Tyson?

  So Frank, I was, I was stunned by this, I mean, in a very positive way. It was a, I, after he said it, it was like, of course you can do that. But I'm thinking, you know, I come in from a whole other angle. I need a, an instrument, I need a, a, a technology, I need a GPS. And he's, he's talking about reading nature.

• 38:47Speaker 01

  But I always know when I'm coming close to like New York City, when I see like a pigeon smoking a cigarette. I'm like, man, that

• 38:53Neil deGrasse Tyson?

  These are your cues.

• 38:55Speaker 01

  Yeah.

• 38:57Neil deGrasse Tyson?

  So, do you, when you teach navigation, celestial navigation, because this is what you teach it, do you care, do you care about nature?

• 39:04Speaker 02

  Not in that way, and you know, that's something you can, we talk about those sorts of things because it's icing on the cake, you know.

• 39:12Neil deGrasse Tyson?

  Oh, would you use all, all?

• 39:15Speaker 02

  You want to use everything. And the single most important principle of good navigation is to use everything that you can see all the time.

• 39:23Neil deGrasse Tyson?

  Okay.

• 39:24Speaker 02

  If I can see my GPS, well, obviously, that's, that's the best thing I got going, but there are hundreds of other things that I can look at to validate it. And you know, traditional European navigators, back, back in the time before the, the longitude solution, when they were approaching the English Channel, one of the biggest things that they would do is throw a line over the side with some, some glue on the end of the weight, and they'd pull up the mud. And they'd look at this mud, and they'd study all this mud, and sometimes they would taste the mud. And that's about as close, as close to nature as you might want to get.

• 39:55Speaker 01

  Wait, what were they tasting for?

• 39:57Neil deGrasse Tyson?

  I know, right. Don't, don't leave us hanging there. Why did they do this?

• 40:00Speaker 01

  Like, English mud tastes better than the rest of the world's mud?

• 40:03Speaker 02

  Well, see, there's, there's English mud over here, and then over here, there's Irish mud. And you don't want to eat that Irish mud, okay?

• 40:10Speaker 02

  But they knew if it was like clay or something like that, they were like... Exactly, here's, here's the deal. As you're coming into the Channel, there are these streams of different kinds of muds and things, and some of them are, are filled with organisms, you know, like little tiny shells, and you can see that in the mud that comes up, so they, they could figure out where they were coming into the Channel before, before the solution of the longitude problem.

• 40:29Neil deGrasse Tyson?

  But somebody has to have established that this was a thing to do first.

• 40:34Speaker 02

  This, this is one of those things that makes you wonder, you know, it, it's a lot like asking, how did they figure out all those mushrooms were poisonous, right?

• 40:40Neil deGrasse Tyson?

  Right, okay.

• 40:42Speaker 02

  So somewhere along the line, there was, there were people, there were people that were out, that were out there tasting mud and making charts, making charts of the, of the kinds of...

• 40:50Neil deGrasse Tyson?

  So that a next generation person can taste the mud and said, I'm 20 miles from the coast.

• 40:54Speaker 02

  Right, right, right.

• 40:55Speaker 01

  I'm gonna keep going.

• 40:56Speaker 02

  In, in terms of...

• 40:57Neil deGrasse Tyson?

  In, in science, we call this calibrating the instrument.

• 41:00Speaker 02

  Yeah, that's right.

• 41:01Neil deGrasse Tyson?

  Yeah, right. So, I, I liked what this was called, I hadn't put it two and two together, that what the Polynesians call this, when they include all the factors together, is wayfinding.

• 41:13Speaker 02

  Yeah.

• 41:13Neil deGrasse Tyson?

  So I, that's a way more beautiful term than navigation.

• 41:16Speaker 02

  It is, it is.

• 41:17Neil deGrasse Tyson?

  I asked Nainoa about his deep heritage of this ancient art. Let's check it out.

• 41:24Speaker 03

  Wayfinding is a relationship to being in nature, part of nature.

• 41:28Neil deGrasse Tyson?

  Because pure navigation ignores all of that.

• 41:30Speaker 03

  Right.

• 41:31Neil deGrasse Tyson?

  It's like Earth is just a surface with a grid on it.

• 41:34Speaker 03

  Right. My teacher, I sailed all the way to Tahiti, all the way back, 6,000 miles. He said, "Nainoa, sit down." He goes, "You did okay. If you want someone to know everything, send your son. You started too old." And so, he said, "My grandfather picked me when I was one, him. Put in tide pools to play with the wind and the water and the sand, to play." At old age of five, he was sailing on the Virgin Canoe. He say, "When the wave take the canoe up and down, the canoe make me sick. My grandfather tie my hands with rope, throw me overboard, drag me behind the canoe." And he says, "Because I can go in the wave. And when I go in the wave, I become the wave. When I become the wave, then I'm navigator. That's wayfinding."

• 42:24Neil deGrasse Tyson?

  So Frank, did anyone throw you overboard and drag you through the waves?

• 42:27Speaker 02

  First of all, best seasickness cure ever. It seems like a great idea. You know sailors tell fish stories and gurus tell stories about what, how you... You're never young enough to start. I seem to recall, that's what Yoda told Luke Skywalker. He is too old. And so, this is just part of the legend, the legend of an art like this.

• 42:54Neil deGrasse Tyson?

  So, would you say that wayfinding is a pure form of navigation than all this new-fangled stuff we're using today?

• 43:03Speaker 02

  It's a different kind of thing, you know. One of these, the wayfinding that Nainoa does, is deeply cultural. And there's a poetic side to it as well. It's romantic.

• 43:15Neil deGrasse Tyson?

  So you say it's important to keep that alive?

• 43:16Speaker 02

  It is, it is.

• 43:17Neil deGrasse Tyson?

  Would you ever think of it as a backup plan?

• 43:20Speaker 02

  Some of the things that they do...

• 43:21Neil deGrasse Tyson?

  In a zombie apocalypse?

• 43:22Speaker 02

  Some of the things, yes. In the zombie apocalypse.

• 43:25Speaker 01

  He has information.

• 43:26Neil deGrasse Tyson?

  You see how quickly he agreed? Definitely for that case.

• 43:32Speaker 02

  In the event of the zombie apocalypse, what can you take from these indigenous methods of navigation? There are things that you can take. Here's something you can use around this part of the world. It won't work in the tropics, but it's something that you can use around here. If you see Orion, and you see the belt vertical in the sky, that means that you're looking east, and maybe a little southeast. If you see the belt horizontal, that means that you're looking west, or a little southwest. Oh, and by the way, there's a neat little mnemonic for this. Think about the letter E. It looks like that. So take the three stars of Orion's belt.

• 44:10Neil deGrasse Tyson?

  Yeah, yeah.

• 44:13Neil deGrasse Tyson?

  It's a navigator's gang sign.

• 44:15Speaker 02

  It's a navigator's gang sign for Orion's Belt vertical. But it means east, okay? The three stars vertical, east. And when it crosses over to the other side of the sky, now you get this gang sign, which is west. And the three stars are horizontal. And that works very nicely. And that's a good, old-fashioned, traditional method for just quickly detecting compass direction. Things like that really are useful. They're useful for the most important kind of check on technology, which is checking for the great big screw-up. You know, sometimes there's just operator error. Somebody inputs the wrong waypoint into the autopilot.

• 44:53Neil deGrasse Tyson?

  So I call it an I/O error, incompetent operator.

• 44:55Speaker 02

  That's the one, yeah.

• 44:58Speaker 02

  And these things happen. So how can you detect them really quickly? Well, one of the ways that you can do it is by maintaining these sorts of tricks so that you can instantly look at the sky and say, "We're going the wrong way."

• 45:09Neil deGrasse Tyson?

  So it's an idiot check, basically?

• 45:11Speaker 02

  It's a sanity check.

• 45:12Speaker 01

  But it seems to mean more than that, too, no? Like, weren't you kind of taken up with the romance of it?

• 45:17Neil deGrasse Tyson?

  Yes, yes, yes. No, it's a beautiful thing.

• 45:20Speaker 02

  Oh, there's nothing wrong with that.

• 45:22Neil deGrasse Tyson?

  It's much more romantic than this section.

• 45:24Speaker 02

  You get that stuff for free. You know, that you get for free.

• 45:28Neil deGrasse Tyson?

  Well, and I know his current mission is a worldwide voyage on a Polynesian replica canoe. So this is a mission to call attention to the fact that not only are they using this wayfinding method as a way to navigate... Earth is what is supplying these wayfinding methods. And is there any better way to tell you to take care of Earth than that?

• 45:52Speaker 01

  And I feel like with some journeys, people think they're fighting against that. You know, they're like, we have to get across there.

• 45:58Neil deGrasse Tyson?

  Yeah, oh, interesting, yeah.

• 46:00Speaker 01

  But this way, you're like, oh, the sea read is helping me and like the birds are showing me. Like, it's not a fight.

• 46:06Neil deGrasse Tyson?

  So if I can offer some sort of reflecting thoughts here.

• 46:12Neil deGrasse Tyson?

  Just the audacity of a people to see this infinite ocean and say, let's just go sail it. And see what's there. Oh, my gosh. What does that require? Maybe it's actually in our DNA. Maybe we shouldn't be so surprised. Because we were kind of doing that ever since we've been human. We left Africa, crossed Europe and Asia into North America, down to South America. And that's just the land part. Then we figure out how to float a boat.

• 46:42Neil deGrasse Tyson?

  It's just water. So what? Let's keep moving. Let's keep exploring. Now that we've explored the entire surface of the Earth. The new ocean is space. And the shore of that ocean is Earth's surface. Fully mapped.

• 47:03Neil deGrasse Tyson?

  So if we're going to continue this DNA-driven exploration of the unknown. Space beckons. We've been to the moon. We've sent our robotic emissaries to the planets, to moons of the planets. I can't help but think that in 3,000 years there will be our descendants looking back at the late 20th century. And reflecting on what we did the way we are now reflecting on the Polynesians. And they say, they did it first. They stepped off the Earth into this vastness of space. Not really knowing if they'll survive. Not really knowing whether they would or should return.

• 47:50Neil deGrasse Tyson?

  And so.

• 47:53Neil deGrasse Tyson?

  Suppose we navigate space. I lose sleep at night wondering what lies beyond that. What is space the shoreline of in the next voyage beyond? That is a cosmic perspective. I want to thank Maeve Higgins, Frank Reed. Excellent. I've been your host of StarTalk, Neil deGrasse Tyson, your personal astrophysicist, and as always, I bid you to keep looking up.