If your GPS suddenly stopped working, would you still be able to find your way?
In this episode we'll teach you tricks and tips to navigate on your own. We'll explain how compasses work and we'll tell you who helped move north to the top of the map. Plus, we'll meet a navigator who goes on long journeys using only traditional Hawaiian navigational techniques and we'll stop by a pitstop for some amazing animal migrators.
All that and a Moment of Um on why diamonds are so rare and so valuable.
If you want to learn more about finding your way without a map, check out Tristan Gooley’s Natural Navigator.
You can find more music from the amazing Kenneka Cook here.
Audio Transcript
Download transcript (PDF)
SPEAKER 1: You're listening to Brains On, where we're serious about being curious.
SPEAKER 2: Brains On is supported in part by a grant from the National Science Foundation.
ELEVATOR: Here we are. Brains On studio.
ANAT: Elevator, are you OK?
ELEVATOR: I'm not sure.
ANAT: Uh-oh.
MOLLY BLOOM: Oh, man. I was worried this thing would be glitchy after Sanden used it underwater to search for lost treasure.
ELEVATOR: Emergency elevator reboot. In 5, 4, 3, 2, 1. Reboot. Shutting down.
MOLLY BLOOM: Whoa. Glad we got here before it broke down.
ANAT: Don't worry, elevator. You'll be up and running in no time.
MOLLY BLOOM: We should let Marc know the elevator's having issues.
ANAT: Oh, wait. He's calling me.
MARC SANCHEZ: Hey, Anat and Molly.
ANAT: Hi.
MOLLY BLOOM: Hi.
MARC SANCHEZ: So I'm downstairs, but it's taking forever for this elevator to get here.
MOLLY BLOOM: Yeah, that's because it's having some technical difficulties. You're going to have to make it to the studio on foot. You know how to get here, right?
MARC SANCHEZ: Come on, Molly. I know Brains On headquarters like the back of my hand.
MOLLY BLOOM: OK, see you soon.
ANAT: Bye.
MARC SANCHEZ: Let's see. I just need to find the stairs.
[MUSIC PLAYING]
A lavish musical dancing scene with two impeccably dressed dancers searching each other's eyes while they tango across a ballroom? Wait a second. What's the sign on this door say? Oh, it's not the stairs. It's Fred Astaire. The famous dancer from Hollywood's Golden Age. Got it. Looking good, you two.
OK, stairs. Stairs. Oh, this looks like a door. Nope. This is the staring contest room. Two chairs, one table. That owl is never going to be beat. All right, I know where I am now. I just have to jump over these goats.
[BLEATS]
And now, a quick pole vault. Whoa! And here we are.
[RINGING]
ANAT: Hello?
MARC SANCHEZ: OK, I've got good news and bad news.
ANAT: Let's hear the bad news first.
MARC SANCHEZ: Well, I tried to find the stairs and got a tad lost. So I'm going to be a little late.
ANAT: And the good?
MARC SANCHEZ: The Brains On taco farm legend is true. I think I just found it.
MOLLY BLOOM: Great. So when you do arrive, you're going to have tacos, right?
MARC SANCHEZ: I'm on it. You can count on me.
MOLLY BLOOM: OK. Anat and I are just going to get started, OK?
ANAT: See you soon. Hopefully.
[MUSIC PLAYING]
MOLLY BLOOM: You're listening to Brains On from American Public Media. I'm Molly Bloom, and my co-host for this episode is Anat from Minneapolis. Hi, Anat.
ANAT: Hi.
MOLLY BLOOM: Anat, how do you generally get around? Do you ever use maps?
ANAT: Yeah, but usually my mom just asks me to use her phone, like on Google Maps.
MOLLY BLOOM: Yes, things like Google Maps and GPS make it so that we don't really have to think too hard about where we're going. But even so, compasses and cardinal directions are still really important. Today's episode was inspired by this question from Nathan.
NATHAN: My question is, how were cardinal directions made?
MOLLY BLOOM: So Anat, do you know what cardinal directions are?
ANAT: Yeah.
MOLLY BLOOM: What are they?
ANAT: They're like north, east, south, west.
MOLLY BLOOM: Exactly. So those directions are used to talk about the way you're facing, the location of something, like we just talked about. My car is driving west, my house is north of the river. But thanks to tools like our phones and GPS navigation, most of us don't need to think much about directions. But before GPS and even compasses, which we'll talk about more in a bit, this idea of north, south, east, and west was based on nature and what people observed in the world around them.
Anat, what things in the natural world can you see as being helpful for people trying to find their way around?
ANAT: Like the stars and the sun.
MOLLY BLOOM: Exactly. So the stars move in a predictable way through the night sky. And during the day, another star we just talked about, the Sun, also moves across the sky. It always rises in the east and sets in the west. And there are also the winds.
DARIN HAYTON: So there are 12 traditional winds that were commonly used for navigational purposes.
MOLLY BLOOM: That's Darin Hayton, a historian of science from Haverford University. And he says these 12 traditional winds align with the way that the compass is divided into north, north-northeast, northeast, east, southeast, south-southeast, and so on. It has a pretty name, too. It's called the wind rose.
It's called a rose because those arrows shooting out from the center and pointing all the different directions look like a flower. So Anat, when you look at a map, which direction is up? Which direction is at the top of the map?
ANAT: North.
MOLLY BLOOM: Exactly. North is up. And that's the way we think of the shape of countries. Like the shape of the United States that you're picturing in your head right now or Italy or your state, that drawing has north at the top. But it's not like that's how you have to look at the world. It would really make just as much sense to have a map with south at the top, or east.
DARIN HAYTON: Until quite recently, north wasn't up. Throughout the Latin Middle Ages, east was at up. And so world maps were oriented 90 degrees from what we're comfortable with. Prior to that, if we go into the Islamic Middle Ages, they tended to orient their maps with south at the top. It's not until the 15th century that we begin to get with some regularity, north at the top of maps.
MOLLY BLOOM: So where did this switch come from? We've talked about the printing press in a few different episodes, and that's because its invention in the 15th century was really important for spreading ideas around the world. Before that, it took forever to print books, because you had to do it all by hand. But the printing press allowed lots of copies of books-- books containing new ideas to be passed around.
[MUSIC PLAYING]
PTOLEMY: That's how my book went viral.
MOLLY BLOOM: Nice work, Ptolemy. Long before the printing press was invented, Greek astronomer Ptolemy wrote a book about mathematical geography. And even though it had been written over 1,000 years ago, the ideas in it became all the rage with geographers in the 15th century.
PTOLEMY: Genius never dies. It just becomes classic. My work is forever in style, like togas. Those are still in, right?
MOLLY BLOOM: In Ptolemy's geography, north was at the top.
DARIN HAYTON: And this is almost certainly connected to his astronomy, which has the North Star at the top.
PTOLEMY: The North Star is a perfect navigational anchor. A literal guiding light. I'm supes into it.
MOLLY BLOOM: The cool thing about the North Star is that unlike other stars, it doesn't seem to move. It's fixed in the sky over the North Pole. That's because it's in line with the Earth's axis. That's the spot the Earth spins around. So the star stays in pretty much the same spot in the night sky while other stars appear to make bigger arcs throughout the night. Navigators could simply find that star and know which way was north.
And it's also around this time that the compass starts to be used as a navigational tool. Anat, have you ever used a compass before?
ANAT: Yeah.
MOLLY BLOOM: Where does the needle on a compass point?
ANAT: North.
MOLLY BLOOM: Exactly. And that's another reason that more maps had north at the top. Compasses started to be used for navigation in China almost 1,000 years ago, and they spread around the world over the next 500 years.
ANAT: And they're still used today. And judging by your questions, a lot of you are using them, too.
JOJO: Hello. My name is Jojo. I'm from Durham, North Carolina, and I'm nine years old. My questions are, what's inside a magnet that attracts it to other things? How do compasses work? And why is the red arrow of a compass attracted to the North Pole?
SUBJECT 1: Why does a compass mean a point north?
SUBJECT 2: How does a compass work?
SUBJECT 3: Hi. My question is, what makes the needle of a compass move? Thank you for answering.
MOLLY BLOOM: To help us answer these questions, we've called up Sonia Tikoo.
ANAT: She studies planetary magnetism at Rutgers University. Hi, Sonia.
SONIA TIKOO: Hi.
ANAT: So I have this question. When you use a compass, the needle always points north. So did someone build a huge magnet up there that the needles are attracted to?
SONIA TIKOO: The needle inside the compass is itself like a little magnet, and it has a north pole and a south pole. And you probably learned about magnets in class. And you know that two magnets can be attracted to each other, where the north pole of one magnet is attracted to the south pole of the other magnet. So opposites attract.
ANAT: Oh.
SONIA TIKOO: Basically the north pole of the compass needle is attracted to the south pole of the Earth's magnetic field. So the Earth is actually a big magnet. You just can't see the force because it's invisible.
ANAT: OK. So does Earth have a magnetic field kind of?
SONIA TIKOO: Yeah, not just kind of. I mean, it's not as strong as a refrigerator magnet that you might have, but it's a pretty big magnetic field. And it covers the entire planet. It's just invisible, so we can't see it.
ANAT: Is it Earth's core that has the magnetic field?
SONIA TIKOO: That is correct, yeah. Earth's magnetic field comes from its core. Right now where we're sitting, you're standing and sitting on the Earth's crust, OK? And underneath the crust is the mantle of the Earth. And underneath the mantle is the core. And do you know what the core is made out of?
ANAT: I don't know.
SONIA TIKOO: Yeah. It's actually made out of liquid molten metal. It's metal that's so hot that's melted into a liquid. And that metal, it moves around like a lava lamp. Have you seen a lava lamp before?
ANAT: Yeah.
SONIA TIKOO: What happens is that hot metal rises from the bottom of the core, and then it goes all the way up to the top of the core, where it cools down. And so then once it's cold, it sinks back down to the bottom. So basically the metal is constantly moving. And it's the motion of this metal that generates the magnetic field.
ANAT: Got it. Another question I have is, what happens if you use a compass at the North Pole? Will the needle go crazy?
SONIA TIKOO: Yeah, the needle will go totally crazy. Because when you're standing at the North Pole, the direction of the Earth's magnetic field is down towards your feet. And likewise, if you were at the South Pole, it would want to point up.
ANAT: That's weird.
SONIA TIKOO: Mm-hmm.
MOLLY BLOOM: Can you tell us how the Earth being a giant magnet makes these two poles?
SONIA TIKOO: Yeah. So with magnetic fields, you can never have just a single point. It always has to have a polarity. It has to have a north and a south. What organizes the Earth's magnetic field into the structure that it has with the North Pole and the South Pole is the rotation of the Earth. So the rotation of the Earth helps the fluid, the liquid metal in the core, it helps it spin around in such a way that you generate a field that is just straight up and down-- north, south.
MOLLY BLOOM: So there's this magnetic pole at the top of the Earth on its axis that the arrow on the compass points to. But why don't our refrigerator magnets go flying north all the time?
SONIA TIKOO: Your refrigerator magnet is a hundred times stronger than the strength of the Earth's magnetic field that we're sitting in right now. The magnet is more attracted to the refrigerator because that's something that's much closer. And it all has to do with the differences in strengths.
MOLLY BLOOM: So then how does the compass work? How does it point north?
SONIA TIKOO: Well, the compass is balanced on a pin in the center. And whenever you use the compass, you tend to keep it away from other things that are magnetic that could attract it. So actually if you were to take the compass and put it near something else that's magnetic, the compass would point to that instead of towards north.
ANAT: Oh, so that's how compasses can lie.
SONIA TIKOO: Yeah, compasses can totally lie.
MOLLY BLOOM: What is a compass made out of?
SONIA TIKOO: It's made out of a mineral called magnetite. So magnetite is a mineral that's made out of iron and oxygen. The iron is what helps make it magnetic.
MOLLY BLOOM: And where exactly is the North Pole?
SONIA TIKOO: The North Magnetic Pole or the North Geographic Pole? Because they're actually not quite the same.
MOLLY BLOOM: Where is the North Magnetic Pole?
SONIA TIKOO: The North Magnetic Pole is located basically on an island in very, very Northern Canada called Ellesmere Island. And the North Geographic Pole is about, I think, 300 miles away. And it's in the middle of the Arctic Ocean. The magnetic pole moves constantly over time, actually. And it tends to move in circles to the west usually. And we call that westward drift of the magnetic pole.
But actually it circles the North Geographic Pole over time. So on average, magnetic north is the same as true north if you average over thousands of years.
ANAT: Thanks for being here today, Sonia.
SONIA TIKOO: Yeah, you're welcome. It was a lot of fun.
MOLLY BLOOM: Bye.
ANAT: Bye.
[MUSIC PLAYING]
MOLLY BLOOM: I'm getting a little hungry. I mean, worried that Marc's still not here.
ANAT: Yeah. I hope he's OK. And the tacos are still warm.
MARC SANCHEZ: Goodbye, my lovely taco farm. I still have to find Anat and Molly. Don't worry, your secret location is safe with me. But I'll be back. OK, let's see. Wait, is this outside? It looks familiar. I think I used to have an apartment around here. Oh yeah, there's the Sherbet Shack. Which means the Two Left Foot Store. I knew it.
Pro tip-- they do not like you dancing in there. I remember when I used to walk home, the Sun would set over the shoe store. So that should be west. And since it's on my left side, I am walking north. Which means the studio should be just over this hill. Oh, I can see it. I can see it. Huh. I never noticed that it looks like a banana from this angle.
[VOCALIZING]
AUDIO TRACK: Brains On.
MOLLY BLOOM: Before we navigate our way through the rest of this episode, it's time for a wee detour to Mystery Sound town. You ready, Anat?
ANAT: Yeah.
MOLLY BLOOM: All right, here it is.
[BARKS]
[BARKS]
[BARKS]
[BARKS]
OK. What is your guess?
ANAT: It kind of sounds like a rain forest and rain. And then that thing that was screaming sounded like a monkey.
MOLLY BLOOM: Yes, it did. There's definitely some birds in the background, some nature going on. That was a very shocking sound. I was not ready for that screaming sound. All right, well we're going to be back with the answer in just a bit.
[MUSIC PLAYING]
ANAT: Do you have a mystery sound you want to share with us?
MOLLY BLOOM: A question you want answered on the show?
ANAT: Or maybe a drawing of Marc navigating his way through the taco farm?
MOLLY BLOOM: You can send them to us by going to brainson.org/contact.
ANAT: That's how we got this question.
ELLIOT: Hi. My name is Elliot, and I am seven years old. And my question is, why are diamonds so hard to find?
MOLLY BLOOM: We're going to answer that during our Moment of Um at the end of the show.
ANAT: And keep listening to the very end of this episode to hear the latest listeners to be added to the Brains Honor Roll.
MOLLY BLOOM: Stick around.
ANAT: You're listening to Brains On from American Public Media. I'm Anat.
MOLLY BLOOM: And I'm Molly. We've heard about how compasses work.
ANAT: And how north became synonymous with up.
MOLLY BLOOM: But long before these developments came to pass, Polynesian voyagers traveled thousands of miles across the Pacific Ocean with no other navigational tools except their senses. Lehua Kamalu is the voyaging director of the Polynesian Voyaging Society. And she navigates canoes many thousands of miles using these traditional techniques. And when you don't have a compass, you have to notice patterns in nature.
LEHUA KAMALU: And if you study those patterns well enough, you come to have a library in your own mind of where the stars move, where the Sun and the celestial bodies and planets move through the sky. And all about the wind. Waves on the water. As well as a lot about the nature of birds and seabirds that can help you find islands in the middle of the ocean. Since Polynesia and these Pacific Islands are very tiny little islands in the middle of very large, large sections of ocean, a lot of the navigation is very specifically designed to work in the technique of trying to isolate and locate a little island in between a lot of water.
[MUSIC PLAYING]
What we do when we see the horizon around us on our canoe or our vaka, we divide up the horizon into 32 different sections. And we call these sections houses. And you can think of a star as leaving its house when it rises and going back into it when it sets. And what you do when you're on land and you're preparing for your voyage is you look out into the night sky and you have a mental projection of where these houses lie on the horizon line. And you will memorize where each of these stars rises, which also tells you about where they're going to set and where they are on that compass. That lines you up north, south, east, west, or whatever direction you plan to go.
During the daytime, a lot of what you want to rely on is no longer up in the sky necessarily, but down on the water. And these things happen in patterns, whether it's how far apart the waves are, how high they are, or what direction they're coming from. And as a navigator, you are watching to see, are the waves coming from the north or the south or the east or the west? Are they growing? Are they slowly getting smaller?
What direction are they coming from as you compare them to the wind or as you compare them to the sunrise location or the sunset location? Is the moon rising during that day? These are all little things that you're going to pay attention to try and find as many signs as you can to hold the right course. So you'll never rely just on one side.
And as the navigator, you stay awake lots of hours. Sometimes all day, sometimes 20 hours, 22 hours a day. Constantly paying attention to these things, because all of this has to live in your mind and give you a picture of where you are and where the weather, the waves, and stars are guiding you.
MOLLY BLOOM: There are more than 1,000 Polynesian islands in the Pacific Ocean, including the Hawaiian islands and Samoa and Tahiti. And the different islands each have slightly different voyaging traditions. Lehua practices the traditions from Hawaii. Earlier this year, Lehua navigated a canoe 2,800 miles from Hawaii to San Francisco. The voyage took 23 days.
[MUSIC PLAYING]
Before we get back to talking navigation, I want to make a pit stop to introduce a special guest, Joy Dolo.
JOY DOLO: Hello.
ANAT: Hi.
MOLLY BLOOM: Joy Dolo is the host of our brand new kids history show, Forever Ago.
JOY DOLO: Yep. Every episode, we explore the history of one cool thing.
ANAT: Like compasses?
JOY DOLO: Exactly like that. But we'll have to save that for season two. This week's episode is all about skateboards.
ANAT: Cool.
MOLLY BLOOM: That's awesome.
JOY DOLO: Yeah. You two want to hear a sneak peek?
ANAT: Sure.
JOY DOLO: OK, here we go.
SPEAKER 3: Homemade skateboards were getting so popular that companies took notice. And by the early '60s, you could buy a skateboard in a store. One of the first ones available was the Roller Derby number 10.
SUBJECT 4: It was a little red skateboard. It was flat. It had no grip tape. The trucks were not adjustable. The wheels were made out of metal. And it really wasn't very practical at all, and a lot of people got hurt using them.
SPEAKER 3: But some kids got really good and did acrobatics on them. Some of them got so good that they could do a handstand on one of these skinny two foot long boards while it was rolling.
SPEAKER 4: That's crazy.
SPEAKER 5: Whoa.
MOLLY BLOOM: I cannot wait to hear the rest of this episode.
ANAT: Me, neither.
JOY DOLO: Well, you don't have to wait too long. Forever Ago episodes come out every Thursday. And if you haven't already, you should go check out our first two episodes. They're about cameras and video games. You can find Forever Ago on Apple Podcasts or wherever you listen.
ANAT: Rate, review, and subscribe.
JOY DOLO: All right, see you later.
ANAT: Bye.
MOLLY BLOOM: Bye.
We've talked all about the clever ways we humans navigate the world. But we've got nothing on the animal kingdom.
ANAT: That's right. Birds, turtles, butterflies, bats, they make epic journeys without compasses.
MOLLY BLOOM: Like monarch butterflies. They travel from all over the US and Canada to meet up on just a few mountaintops in Mexico. Or the bar-tailed godwit, the bird with the record for the longest non-stop migration ever. Over 7,000 miles without stopping.
ANAT: Or humpback whales. They navigate from Alaska to Hawaii with ease.
MOLLY BLOOM: Scientists are still trying to figure out how these creatures do it. Some think they may have a built-in sense of direction, like a biological compass. It lets them know north and south by instinct.
ANAT: Other researchers think animals might get cues from sunlight or even the stars.
MOLLY BLOOM: Whatever they use, it's working. And with all that travel, I bet these beasts know the best roadside pit stops.
SNAKE: Welcome to Crosstrek Cafe, home of the Mighty Migration Combo Meal.
[TRUMPET]
CARIBOU: Hi. I have a reservation under caribou. The porcupine caribou herd.
SNAKE: Ah, yes. Here it is. How many in your party?
CARIBOU: Oh, let's see. One, two, three, four. 218,000.
SNAKE: Great. Let me just clear a table, and we'll seat you shortly.
CARIBOU: Thanks.
MONARCH BUTTERFLY: Hey, pal.
CARIBOU: Oh, hey! I didn't see you down there. Cool wings.
MONARCH BUTTERFLY: Oh, thanks. One nice thing about being a monarch is everyone notices the wings. Which is great, because they never noticed my embarrassing ankle tattoo.
[CHUCKLES]
CARIBOU: Oh, now I see it. It's a drawing of a human that says peace.
MONARCH BUTTERFLY: Yeah, got it on spring break. You're only a caterpillar once, you know?
CARIBOU: Not really. But sure.
MONARCH BUTTERFLY: Where are you headed?
CARIBOU: Oh, just doing our yearly road trip through Canada to our timeshare by beautiful Beaufort Sea.
MONARCH BUTTERFLY: I've never heard of it.
CARIBOU: Oh, it's wild. It's the Daytona Beach of Northern Alaska, if you know what I mean. Going there is a porcupine caribou family tradition. It's a 1,500 mile trek but, so worth it.
MONARCH BUTTERFLY: Nice. I'm on the open road myself about to bust out of here and wing it to Mexico.
CARIBOU: Sweet. You been there before?
MONARCH BUTTERFLY: Never. But every other monarch I goes there. Like millions of us. So I figure it must be pretty nice. I'm stopping here to fill up on milkweed, because it's 3,000 miles to the mountains of Central Mexico.
CARIBOU: Wow.
MONARCH BUTTERFLY: Yeah. I probably won't even make it back. But my kids or maybe my grandkids will.
[MUSIC PLAYING]
[FOOTSTEPS]
BAR-TAILED GODWIT: Bartender, three shots of worms. Pronto.
CARIBOU: Who's that?
MONARCH BUTTERFLY: That's the bar-tailed godwit. The ultimate migrator. I've heard it flies 7,000 miles every year from Alaska to New Zealand, nonstop. It just keeps flying for nine days over nothing but open water. I think it goes a little stir crazy on the trip.
BAR-TAILED GODWIT: Who said that?
[CLINKS]
BAR-TAILED GODWIT: Oh, it's you. My imaginary best friend Trish, the flying elephant that keeps me company on my migration. Sure, Trish. You can eat all the peanuts at the bar. Bartender, get this polka dotted elephant some peanuts, pronto.
HUMAN: Hello?
SNAKE: Welcome to Crosstrek cafe. Whoa, are you a human?
HUMAN: Yeah. Are you a talking snake?
SNAKE: Yeah. Can I help you.
HUMAN: Yeah. Wow, this place is like a zoo. Look, I'm lost. I'm trying to get to City Hall. Do you know--
SNAKE: Two blocks north. Take a left. It's a big building facing south.
HUMAN: Thanks. Bye. I guess.
[LAUGHTER]
MONARCH BUTTERFLY: Where is City Hall? It's like two blocks away. What do you need, a map, pal?
CARIBOU: Yeah. Who gets lost when you're only going two blocks? Poor humans. They're helpless without their GPSes and compass thingies.
[GIGGLES]
MONARCH BUTTERFLY: Yeah. I mean, navigating the world without a map is so easy. The secret is just--
SNAKE: Caribou herd, your table is ready.
MONARCH BUTTERFLY: I don't need to tell you the super obvious answer to how animals know their way around vast distances instinctually. You already know. Have a good dinner.
CARIBOU: Thanks! Have fun in Mexico. Watch out for spiders.
AUDIO TRACK: Brains On!
MOLLY BLOOM: All right, Anat. Hey, well, look at this. We've traveled through almost this entire episode and found our way back to the mystery sound. Here it is one more time.
[BARKS]
[BARKS]
[BARKS]
[BARKS]
OK, so any new guesses after hearing it again?
ANAT: Well, I'm still stuck with rainforest, except the sound that I think is supposed to be rain, it sounds glitchy, like--
MOLLY BLOOM: Oh. That's an interesting observation. I like that. So what do you think that screeching sound is? Last time you said it was a monkey. Do you think--
ANAT: Yeah, I don't know. I think it's some sort of creature that yells a lot.
[LAUGHS]
MOLLY BLOOM: Some very angry creature. Well, here is the answer.
TRISTAN GOOLEY: That was a muntjac deer giving an alarm call well.
MOLLY BLOOM: Yeah. That's natural navigator Tristan Gooley. He spends most of his days building mental maps out of observations he finds in the environments all over the world. Sometimes that includes animal noises.
TRISTAN GOOLEY: Most animals have a way of warning animals of the same species that there's danger in the area. And these are known as alarm calls. But quite a few animals have learned to use other species' alarm calls as well. So in the case of a deer giving an alarm call, it's telling us that that deer has spotted something in its surroundings.
Now that something might be us. But if we're pretty sure it's not us, we're not the ones that have surprised the deer and made it give a call, then it's telling us that something or someone else is out there.
[BARKS]
[BARKS]
There is a whole map available from sound. So part of them being a natural navigator is making use of things that most people don't tune into. And the wind is really, really important there. Everybody knows that the wind, when it hits trees, we hear a rustling sound in the leaves. But we hear different things depending where we are. You'll hear different things in the middle of a wood or if you're standing in open country. But as you get towards the edge of a wood, the sound changes.
MOLLY BLOOM: Following the path of the sun is one way to navigate. But Tristan uses it in another way.
TRISTAN GOOLEY: What's more interesting for most of my work is the way the sun leaves footprints on the landscape. So it shapes everything around us. It shapes trees. Trees are bigger on their southern side in the northern hemisphere. It even shapes the branches and even the leaves. The leaves on the south side of trees are smaller because of the sun.
MOLLY BLOOM: We've talked quite a bit about navigating uninhabited places, like the ocean or the forest. But there are clues in urban environments, too.
TRISTAN GOOLEY: The best thing to do is try and understand the story of why a town or a city is where it is. Quite often, we'll find that they were built up because that's where the only water is. And water will tend to be the lowest point of a town. And suddenly you realize that all the streets have a slight gradient. And if you're looking uphill, you're looking away from the water obviously, and downhill towards the water.
Or we might find the town is-- it's in a valley and it's the only route between high ground. And then suddenly we understand why all the streets are aligned the way they are. And then we go into much more detailed clues, like TV satellite dishes. They have to point to satellites that are over the equator.
So in the northern hemisphere, TV satellite dishes will be pointed broadly in a southerly direction. Depending which satellite they point out will tell you exactly which direction. Where I live, they point southeast. Other parts of the world, it might be southwest. But once you've spotted that trend, it's amazing how helpful it can be all over a big city.
MOLLY BLOOM: Check out naturalnavigator.com for more helpful navigation tips. Tristan suggests a fun natural navigation game without checking a map or GPS. Try to guess which way you're looking. Remember, use clues from your environment to help figure out the answer. You can check your answers on a phone or compass.
[BARKS]
OK, Anat. I am officially worried that Marc still isn't here.
ANAT: I know. Should we call somebody?
[KNOCKS]
MARC SANCHEZ: Hey. Did I make it? Is this still the Cardinal Directions episode?
MOLLY BLOOM: What happened to you?
MARC SANCHEZ: Well, there was this taco farm. Then I found my old apartment. And then the Sherbet Shack. And did from the southeast, our studio looks like a banana? Anyway, here are your tacos.
MOLLY BLOOM: Ooh, thank you, Marc.
ANAT: Yum.
MARC SANCHEZ: Did I miss the taping?
MOLLY BLOOM: Almost all of it, but you're in time to hear the Cardinal Directions song.
MARC SANCHEZ: You mean the one by Kanika Cook?
ANAT: Yeah.
MARC SANCHEZ: Ooh, that song is so good. It's like the hot sauce to my taco.
ANAT: Hit it.
[MUSIC PLAYING]
(SINGING) If you don't know which way to go to get in the right direction, get yourself a compass road or a map as your selection. North and south. North and south. East to west. East to west. Your cardinal direction. Cardinal direction. For your quest. A compass will always point north because of Earth's magnetic field. Use it to go back and forth. Now you know the deal. North and south. North and south. East to west. East to west. Your cardinal direction. Cardinal direction. For your quest.
Early maps were first drawn in Babylon and Greece. Influencing ways today, we navigate with ease. North and south. North and south. East to west. East to west. Your cardinal direction. Cardinal direction. For your quest. If you are looking at a map confused by all the symbols, there's a legend in the corner making it very simple. North and south. North and south. East to west. East to west. Your cardinal direction. Cardinal direction. For your quest.
[VOCALIZING]
ANAT: That was Kaniko Cook and her Cardinal Direction song. Check out kanikocook.com to hear more of her amazing music.
[MUSIC PLAYING]
MOLLY BLOOM: The cardinal directions have their origins in nature.
ANAT: The wind, the stars. And our biggest star, the Sun.
MOLLY BLOOM: Earth's magnetic field is formed by molten lava at its core.
ANAT: North wasn't always up on the map. But Ptolemy encompasses helped make it that way.
MOLLY BLOOM: Using a compass when there are other magnets nearby could give you a false reading.
ANAT: And humans aren't the only ones who can navigate long distances. Many kinds of animals travel far. But we're still not quite sure how they managed to do it.
MOLLY BLOOM: That's it for this episode of Brains On.
ANAT: Brains On is produced by Marc Sanchez, Sanden Totten, and Molly Bloom.
MOLLY BLOOM: We had production help from Ned Leebrick-Stryker and Tressa Versteeg and engineering help from Corey Schreppel and John Miller. Many thanks to Mark Robins and the Macaulay Library of Ornithology. And Molly, David McCarthy, Vicky Crocker, Taylor Kaufman, Mildred Marie Langford, Jennifer Miller, Austin Cross, Todd Masterson, Sam Choo, JB Shankman, and Alex Hui.
ANAT: Brains On is a nonprofit public radio production. Donations from listeners like you allow us to keep making new episodes.
MOLLY BLOOM: You can support Brains On today by heading to brainson.org/donate.
ANAT: Now before we go, it's time for a Moment of--
AUDIO TRACK: Um. Uh. Uh. Um. Um. Um. Um. Um. Um.
ELLIOT: My question is, why are diamonds so hard to find?
MARC HIRSCHMANN: My name is Marc Hirschmann. I'm a geologist. I'm a professor here at the University of Minnesota. My research involves the materials and rocks and minerals that exist deep in the earth. Diamonds, they're made of carbon. Everything, plants and animals and things, everything living has carbon in it. So it's a very common material on the surface.
But diamonds require more than just the presence of carbon. They require very high pressures. They require pressures in excess of what occurs deep in the earth more than about 100 miles. The thing that makes diamonds rare is although carbon is common on the surface, it's very scarce at depth. The common materials deep in the earth are not carbon rich. They're rich in other things-- magnesium, iron, silicon, and so on.
And so the first reason why diamonds are rare is because there's not a lot of carbon in the place where the pressures are high enough to make the form of carbon that is in the diamond structure. And the diamond structure requires high pressure for formation. The second reason is that even if they form down there, it's not so easy to get them to the surface. We certainly can't mine to that depth. We can't drill to that depth.
We have to wait for geologic processes to bring them to the surface. So we need very unusual volcanoes, known as kimberlites, that bring material very suddenly from great depth to the surface. Very rapidly. When kimberlite volcanoes erupt, they bring diamonds to the surface.
MOLLY BLOOM: These names are shining bright. It's time for the Brains Honor Roll. This is the way we thank the amazing listeners who send us their ideas, questions, mystery sounds, and drawings. They keep us going.
[LISTING HONOR ROLL]
AUDIO TRACK: Brains Honor Roll. High fives.
[ALARM]
ELEVATOR: Attention, Brains On headquarters. The elevator repairs are complete. The system will be restored in 5, 4, 3, 2, 1.
[DINGS]
Welcome to Brains On headquarters. What floor?
MOLLY AND ANAT: Elevator!
MOLLY BLOOM: Just in time to get us out of here.
ANAT: Thanks for listening.
SPEAKER 2: Brains On is supported in part by a grant from the National Science Foundation.
ELEVATOR: Here we are. Brains On studio.
ANAT: Elevator, are you OK?
ELEVATOR: I'm not sure.
ANAT: Uh-oh.
MOLLY BLOOM: Oh, man. I was worried this thing would be glitchy after Sanden used it underwater to search for lost treasure.
ELEVATOR: Emergency elevator reboot. In 5, 4, 3, 2, 1. Reboot. Shutting down.
MOLLY BLOOM: Whoa. Glad we got here before it broke down.
ANAT: Don't worry, elevator. You'll be up and running in no time.
MOLLY BLOOM: We should let Marc know the elevator's having issues.
ANAT: Oh, wait. He's calling me.
MARC SANCHEZ: Hey, Anat and Molly.
ANAT: Hi.
MOLLY BLOOM: Hi.
MARC SANCHEZ: So I'm downstairs, but it's taking forever for this elevator to get here.
MOLLY BLOOM: Yeah, that's because it's having some technical difficulties. You're going to have to make it to the studio on foot. You know how to get here, right?
MARC SANCHEZ: Come on, Molly. I know Brains On headquarters like the back of my hand.
MOLLY BLOOM: OK, see you soon.
ANAT: Bye.
MARC SANCHEZ: Let's see. I just need to find the stairs.
[MUSIC PLAYING]
A lavish musical dancing scene with two impeccably dressed dancers searching each other's eyes while they tango across a ballroom? Wait a second. What's the sign on this door say? Oh, it's not the stairs. It's Fred Astaire. The famous dancer from Hollywood's Golden Age. Got it. Looking good, you two.
OK, stairs. Stairs. Oh, this looks like a door. Nope. This is the staring contest room. Two chairs, one table. That owl is never going to be beat. All right, I know where I am now. I just have to jump over these goats.
[BLEATS]
And now, a quick pole vault. Whoa! And here we are.
[RINGING]
ANAT: Hello?
MARC SANCHEZ: OK, I've got good news and bad news.
ANAT: Let's hear the bad news first.
MARC SANCHEZ: Well, I tried to find the stairs and got a tad lost. So I'm going to be a little late.
ANAT: And the good?
MARC SANCHEZ: The Brains On taco farm legend is true. I think I just found it.
MOLLY BLOOM: Great. So when you do arrive, you're going to have tacos, right?
MARC SANCHEZ: I'm on it. You can count on me.
MOLLY BLOOM: OK. Anat and I are just going to get started, OK?
ANAT: See you soon. Hopefully.
[MUSIC PLAYING]
MOLLY BLOOM: You're listening to Brains On from American Public Media. I'm Molly Bloom, and my co-host for this episode is Anat from Minneapolis. Hi, Anat.
ANAT: Hi.
MOLLY BLOOM: Anat, how do you generally get around? Do you ever use maps?
ANAT: Yeah, but usually my mom just asks me to use her phone, like on Google Maps.
MOLLY BLOOM: Yes, things like Google Maps and GPS make it so that we don't really have to think too hard about where we're going. But even so, compasses and cardinal directions are still really important. Today's episode was inspired by this question from Nathan.
NATHAN: My question is, how were cardinal directions made?
MOLLY BLOOM: So Anat, do you know what cardinal directions are?
ANAT: Yeah.
MOLLY BLOOM: What are they?
ANAT: They're like north, east, south, west.
MOLLY BLOOM: Exactly. So those directions are used to talk about the way you're facing, the location of something, like we just talked about. My car is driving west, my house is north of the river. But thanks to tools like our phones and GPS navigation, most of us don't need to think much about directions. But before GPS and even compasses, which we'll talk about more in a bit, this idea of north, south, east, and west was based on nature and what people observed in the world around them.
Anat, what things in the natural world can you see as being helpful for people trying to find their way around?
ANAT: Like the stars and the sun.
MOLLY BLOOM: Exactly. So the stars move in a predictable way through the night sky. And during the day, another star we just talked about, the Sun, also moves across the sky. It always rises in the east and sets in the west. And there are also the winds.
DARIN HAYTON: So there are 12 traditional winds that were commonly used for navigational purposes.
MOLLY BLOOM: That's Darin Hayton, a historian of science from Haverford University. And he says these 12 traditional winds align with the way that the compass is divided into north, north-northeast, northeast, east, southeast, south-southeast, and so on. It has a pretty name, too. It's called the wind rose.
It's called a rose because those arrows shooting out from the center and pointing all the different directions look like a flower. So Anat, when you look at a map, which direction is up? Which direction is at the top of the map?
ANAT: North.
MOLLY BLOOM: Exactly. North is up. And that's the way we think of the shape of countries. Like the shape of the United States that you're picturing in your head right now or Italy or your state, that drawing has north at the top. But it's not like that's how you have to look at the world. It would really make just as much sense to have a map with south at the top, or east.
DARIN HAYTON: Until quite recently, north wasn't up. Throughout the Latin Middle Ages, east was at up. And so world maps were oriented 90 degrees from what we're comfortable with. Prior to that, if we go into the Islamic Middle Ages, they tended to orient their maps with south at the top. It's not until the 15th century that we begin to get with some regularity, north at the top of maps.
MOLLY BLOOM: So where did this switch come from? We've talked about the printing press in a few different episodes, and that's because its invention in the 15th century was really important for spreading ideas around the world. Before that, it took forever to print books, because you had to do it all by hand. But the printing press allowed lots of copies of books-- books containing new ideas to be passed around.
[MUSIC PLAYING]
PTOLEMY: That's how my book went viral.
MOLLY BLOOM: Nice work, Ptolemy. Long before the printing press was invented, Greek astronomer Ptolemy wrote a book about mathematical geography. And even though it had been written over 1,000 years ago, the ideas in it became all the rage with geographers in the 15th century.
PTOLEMY: Genius never dies. It just becomes classic. My work is forever in style, like togas. Those are still in, right?
MOLLY BLOOM: In Ptolemy's geography, north was at the top.
DARIN HAYTON: And this is almost certainly connected to his astronomy, which has the North Star at the top.
PTOLEMY: The North Star is a perfect navigational anchor. A literal guiding light. I'm supes into it.
MOLLY BLOOM: The cool thing about the North Star is that unlike other stars, it doesn't seem to move. It's fixed in the sky over the North Pole. That's because it's in line with the Earth's axis. That's the spot the Earth spins around. So the star stays in pretty much the same spot in the night sky while other stars appear to make bigger arcs throughout the night. Navigators could simply find that star and know which way was north.
And it's also around this time that the compass starts to be used as a navigational tool. Anat, have you ever used a compass before?
ANAT: Yeah.
MOLLY BLOOM: Where does the needle on a compass point?
ANAT: North.
MOLLY BLOOM: Exactly. And that's another reason that more maps had north at the top. Compasses started to be used for navigation in China almost 1,000 years ago, and they spread around the world over the next 500 years.
ANAT: And they're still used today. And judging by your questions, a lot of you are using them, too.
JOJO: Hello. My name is Jojo. I'm from Durham, North Carolina, and I'm nine years old. My questions are, what's inside a magnet that attracts it to other things? How do compasses work? And why is the red arrow of a compass attracted to the North Pole?
SUBJECT 1: Why does a compass mean a point north?
SUBJECT 2: How does a compass work?
SUBJECT 3: Hi. My question is, what makes the needle of a compass move? Thank you for answering.
MOLLY BLOOM: To help us answer these questions, we've called up Sonia Tikoo.
ANAT: She studies planetary magnetism at Rutgers University. Hi, Sonia.
SONIA TIKOO: Hi.
ANAT: So I have this question. When you use a compass, the needle always points north. So did someone build a huge magnet up there that the needles are attracted to?
SONIA TIKOO: The needle inside the compass is itself like a little magnet, and it has a north pole and a south pole. And you probably learned about magnets in class. And you know that two magnets can be attracted to each other, where the north pole of one magnet is attracted to the south pole of the other magnet. So opposites attract.
ANAT: Oh.
SONIA TIKOO: Basically the north pole of the compass needle is attracted to the south pole of the Earth's magnetic field. So the Earth is actually a big magnet. You just can't see the force because it's invisible.
ANAT: OK. So does Earth have a magnetic field kind of?
SONIA TIKOO: Yeah, not just kind of. I mean, it's not as strong as a refrigerator magnet that you might have, but it's a pretty big magnetic field. And it covers the entire planet. It's just invisible, so we can't see it.
ANAT: Is it Earth's core that has the magnetic field?
SONIA TIKOO: That is correct, yeah. Earth's magnetic field comes from its core. Right now where we're sitting, you're standing and sitting on the Earth's crust, OK? And underneath the crust is the mantle of the Earth. And underneath the mantle is the core. And do you know what the core is made out of?
ANAT: I don't know.
SONIA TIKOO: Yeah. It's actually made out of liquid molten metal. It's metal that's so hot that's melted into a liquid. And that metal, it moves around like a lava lamp. Have you seen a lava lamp before?
ANAT: Yeah.
SONIA TIKOO: What happens is that hot metal rises from the bottom of the core, and then it goes all the way up to the top of the core, where it cools down. And so then once it's cold, it sinks back down to the bottom. So basically the metal is constantly moving. And it's the motion of this metal that generates the magnetic field.
ANAT: Got it. Another question I have is, what happens if you use a compass at the North Pole? Will the needle go crazy?
SONIA TIKOO: Yeah, the needle will go totally crazy. Because when you're standing at the North Pole, the direction of the Earth's magnetic field is down towards your feet. And likewise, if you were at the South Pole, it would want to point up.
ANAT: That's weird.
SONIA TIKOO: Mm-hmm.
MOLLY BLOOM: Can you tell us how the Earth being a giant magnet makes these two poles?
SONIA TIKOO: Yeah. So with magnetic fields, you can never have just a single point. It always has to have a polarity. It has to have a north and a south. What organizes the Earth's magnetic field into the structure that it has with the North Pole and the South Pole is the rotation of the Earth. So the rotation of the Earth helps the fluid, the liquid metal in the core, it helps it spin around in such a way that you generate a field that is just straight up and down-- north, south.
MOLLY BLOOM: So there's this magnetic pole at the top of the Earth on its axis that the arrow on the compass points to. But why don't our refrigerator magnets go flying north all the time?
SONIA TIKOO: Your refrigerator magnet is a hundred times stronger than the strength of the Earth's magnetic field that we're sitting in right now. The magnet is more attracted to the refrigerator because that's something that's much closer. And it all has to do with the differences in strengths.
MOLLY BLOOM: So then how does the compass work? How does it point north?
SONIA TIKOO: Well, the compass is balanced on a pin in the center. And whenever you use the compass, you tend to keep it away from other things that are magnetic that could attract it. So actually if you were to take the compass and put it near something else that's magnetic, the compass would point to that instead of towards north.
ANAT: Oh, so that's how compasses can lie.
SONIA TIKOO: Yeah, compasses can totally lie.
MOLLY BLOOM: What is a compass made out of?
SONIA TIKOO: It's made out of a mineral called magnetite. So magnetite is a mineral that's made out of iron and oxygen. The iron is what helps make it magnetic.
MOLLY BLOOM: And where exactly is the North Pole?
SONIA TIKOO: The North Magnetic Pole or the North Geographic Pole? Because they're actually not quite the same.
MOLLY BLOOM: Where is the North Magnetic Pole?
SONIA TIKOO: The North Magnetic Pole is located basically on an island in very, very Northern Canada called Ellesmere Island. And the North Geographic Pole is about, I think, 300 miles away. And it's in the middle of the Arctic Ocean. The magnetic pole moves constantly over time, actually. And it tends to move in circles to the west usually. And we call that westward drift of the magnetic pole.
But actually it circles the North Geographic Pole over time. So on average, magnetic north is the same as true north if you average over thousands of years.
ANAT: Thanks for being here today, Sonia.
SONIA TIKOO: Yeah, you're welcome. It was a lot of fun.
MOLLY BLOOM: Bye.
ANAT: Bye.
[MUSIC PLAYING]
MOLLY BLOOM: I'm getting a little hungry. I mean, worried that Marc's still not here.
ANAT: Yeah. I hope he's OK. And the tacos are still warm.
MARC SANCHEZ: Goodbye, my lovely taco farm. I still have to find Anat and Molly. Don't worry, your secret location is safe with me. But I'll be back. OK, let's see. Wait, is this outside? It looks familiar. I think I used to have an apartment around here. Oh yeah, there's the Sherbet Shack. Which means the Two Left Foot Store. I knew it.
Pro tip-- they do not like you dancing in there. I remember when I used to walk home, the Sun would set over the shoe store. So that should be west. And since it's on my left side, I am walking north. Which means the studio should be just over this hill. Oh, I can see it. I can see it. Huh. I never noticed that it looks like a banana from this angle.
[VOCALIZING]
AUDIO TRACK: Brains On.
MOLLY BLOOM: Before we navigate our way through the rest of this episode, it's time for a wee detour to Mystery Sound town. You ready, Anat?
ANAT: Yeah.
MOLLY BLOOM: All right, here it is.
[BARKS]
[BARKS]
[BARKS]
[BARKS]
OK. What is your guess?
ANAT: It kind of sounds like a rain forest and rain. And then that thing that was screaming sounded like a monkey.
MOLLY BLOOM: Yes, it did. There's definitely some birds in the background, some nature going on. That was a very shocking sound. I was not ready for that screaming sound. All right, well we're going to be back with the answer in just a bit.
[MUSIC PLAYING]
ANAT: Do you have a mystery sound you want to share with us?
MOLLY BLOOM: A question you want answered on the show?
ANAT: Or maybe a drawing of Marc navigating his way through the taco farm?
MOLLY BLOOM: You can send them to us by going to brainson.org/contact.
ANAT: That's how we got this question.
ELLIOT: Hi. My name is Elliot, and I am seven years old. And my question is, why are diamonds so hard to find?
MOLLY BLOOM: We're going to answer that during our Moment of Um at the end of the show.
ANAT: And keep listening to the very end of this episode to hear the latest listeners to be added to the Brains Honor Roll.
MOLLY BLOOM: Stick around.
ANAT: You're listening to Brains On from American Public Media. I'm Anat.
MOLLY BLOOM: And I'm Molly. We've heard about how compasses work.
ANAT: And how north became synonymous with up.
MOLLY BLOOM: But long before these developments came to pass, Polynesian voyagers traveled thousands of miles across the Pacific Ocean with no other navigational tools except their senses. Lehua Kamalu is the voyaging director of the Polynesian Voyaging Society. And she navigates canoes many thousands of miles using these traditional techniques. And when you don't have a compass, you have to notice patterns in nature.
LEHUA KAMALU: And if you study those patterns well enough, you come to have a library in your own mind of where the stars move, where the Sun and the celestial bodies and planets move through the sky. And all about the wind. Waves on the water. As well as a lot about the nature of birds and seabirds that can help you find islands in the middle of the ocean. Since Polynesia and these Pacific Islands are very tiny little islands in the middle of very large, large sections of ocean, a lot of the navigation is very specifically designed to work in the technique of trying to isolate and locate a little island in between a lot of water.
[MUSIC PLAYING]
What we do when we see the horizon around us on our canoe or our vaka, we divide up the horizon into 32 different sections. And we call these sections houses. And you can think of a star as leaving its house when it rises and going back into it when it sets. And what you do when you're on land and you're preparing for your voyage is you look out into the night sky and you have a mental projection of where these houses lie on the horizon line. And you will memorize where each of these stars rises, which also tells you about where they're going to set and where they are on that compass. That lines you up north, south, east, west, or whatever direction you plan to go.
During the daytime, a lot of what you want to rely on is no longer up in the sky necessarily, but down on the water. And these things happen in patterns, whether it's how far apart the waves are, how high they are, or what direction they're coming from. And as a navigator, you are watching to see, are the waves coming from the north or the south or the east or the west? Are they growing? Are they slowly getting smaller?
What direction are they coming from as you compare them to the wind or as you compare them to the sunrise location or the sunset location? Is the moon rising during that day? These are all little things that you're going to pay attention to try and find as many signs as you can to hold the right course. So you'll never rely just on one side.
And as the navigator, you stay awake lots of hours. Sometimes all day, sometimes 20 hours, 22 hours a day. Constantly paying attention to these things, because all of this has to live in your mind and give you a picture of where you are and where the weather, the waves, and stars are guiding you.
MOLLY BLOOM: There are more than 1,000 Polynesian islands in the Pacific Ocean, including the Hawaiian islands and Samoa and Tahiti. And the different islands each have slightly different voyaging traditions. Lehua practices the traditions from Hawaii. Earlier this year, Lehua navigated a canoe 2,800 miles from Hawaii to San Francisco. The voyage took 23 days.
[MUSIC PLAYING]
Before we get back to talking navigation, I want to make a pit stop to introduce a special guest, Joy Dolo.
JOY DOLO: Hello.
ANAT: Hi.
MOLLY BLOOM: Joy Dolo is the host of our brand new kids history show, Forever Ago.
JOY DOLO: Yep. Every episode, we explore the history of one cool thing.
ANAT: Like compasses?
JOY DOLO: Exactly like that. But we'll have to save that for season two. This week's episode is all about skateboards.
ANAT: Cool.
MOLLY BLOOM: That's awesome.
JOY DOLO: Yeah. You two want to hear a sneak peek?
ANAT: Sure.
JOY DOLO: OK, here we go.
SPEAKER 3: Homemade skateboards were getting so popular that companies took notice. And by the early '60s, you could buy a skateboard in a store. One of the first ones available was the Roller Derby number 10.
SUBJECT 4: It was a little red skateboard. It was flat. It had no grip tape. The trucks were not adjustable. The wheels were made out of metal. And it really wasn't very practical at all, and a lot of people got hurt using them.
SPEAKER 3: But some kids got really good and did acrobatics on them. Some of them got so good that they could do a handstand on one of these skinny two foot long boards while it was rolling.
SPEAKER 4: That's crazy.
SPEAKER 5: Whoa.
MOLLY BLOOM: I cannot wait to hear the rest of this episode.
ANAT: Me, neither.
JOY DOLO: Well, you don't have to wait too long. Forever Ago episodes come out every Thursday. And if you haven't already, you should go check out our first two episodes. They're about cameras and video games. You can find Forever Ago on Apple Podcasts or wherever you listen.
ANAT: Rate, review, and subscribe.
JOY DOLO: All right, see you later.
ANAT: Bye.
MOLLY BLOOM: Bye.
We've talked all about the clever ways we humans navigate the world. But we've got nothing on the animal kingdom.
ANAT: That's right. Birds, turtles, butterflies, bats, they make epic journeys without compasses.
MOLLY BLOOM: Like monarch butterflies. They travel from all over the US and Canada to meet up on just a few mountaintops in Mexico. Or the bar-tailed godwit, the bird with the record for the longest non-stop migration ever. Over 7,000 miles without stopping.
ANAT: Or humpback whales. They navigate from Alaska to Hawaii with ease.
MOLLY BLOOM: Scientists are still trying to figure out how these creatures do it. Some think they may have a built-in sense of direction, like a biological compass. It lets them know north and south by instinct.
ANAT: Other researchers think animals might get cues from sunlight or even the stars.
MOLLY BLOOM: Whatever they use, it's working. And with all that travel, I bet these beasts know the best roadside pit stops.
SNAKE: Welcome to Crosstrek Cafe, home of the Mighty Migration Combo Meal.
[TRUMPET]
CARIBOU: Hi. I have a reservation under caribou. The porcupine caribou herd.
SNAKE: Ah, yes. Here it is. How many in your party?
CARIBOU: Oh, let's see. One, two, three, four. 218,000.
SNAKE: Great. Let me just clear a table, and we'll seat you shortly.
CARIBOU: Thanks.
MONARCH BUTTERFLY: Hey, pal.
CARIBOU: Oh, hey! I didn't see you down there. Cool wings.
MONARCH BUTTERFLY: Oh, thanks. One nice thing about being a monarch is everyone notices the wings. Which is great, because they never noticed my embarrassing ankle tattoo.
[CHUCKLES]
CARIBOU: Oh, now I see it. It's a drawing of a human that says peace.
MONARCH BUTTERFLY: Yeah, got it on spring break. You're only a caterpillar once, you know?
CARIBOU: Not really. But sure.
MONARCH BUTTERFLY: Where are you headed?
CARIBOU: Oh, just doing our yearly road trip through Canada to our timeshare by beautiful Beaufort Sea.
MONARCH BUTTERFLY: I've never heard of it.
CARIBOU: Oh, it's wild. It's the Daytona Beach of Northern Alaska, if you know what I mean. Going there is a porcupine caribou family tradition. It's a 1,500 mile trek but, so worth it.
MONARCH BUTTERFLY: Nice. I'm on the open road myself about to bust out of here and wing it to Mexico.
CARIBOU: Sweet. You been there before?
MONARCH BUTTERFLY: Never. But every other monarch I goes there. Like millions of us. So I figure it must be pretty nice. I'm stopping here to fill up on milkweed, because it's 3,000 miles to the mountains of Central Mexico.
CARIBOU: Wow.
MONARCH BUTTERFLY: Yeah. I probably won't even make it back. But my kids or maybe my grandkids will.
[MUSIC PLAYING]
[FOOTSTEPS]
BAR-TAILED GODWIT: Bartender, three shots of worms. Pronto.
CARIBOU: Who's that?
MONARCH BUTTERFLY: That's the bar-tailed godwit. The ultimate migrator. I've heard it flies 7,000 miles every year from Alaska to New Zealand, nonstop. It just keeps flying for nine days over nothing but open water. I think it goes a little stir crazy on the trip.
BAR-TAILED GODWIT: Who said that?
[CLINKS]
BAR-TAILED GODWIT: Oh, it's you. My imaginary best friend Trish, the flying elephant that keeps me company on my migration. Sure, Trish. You can eat all the peanuts at the bar. Bartender, get this polka dotted elephant some peanuts, pronto.
HUMAN: Hello?
SNAKE: Welcome to Crosstrek cafe. Whoa, are you a human?
HUMAN: Yeah. Are you a talking snake?
SNAKE: Yeah. Can I help you.
HUMAN: Yeah. Wow, this place is like a zoo. Look, I'm lost. I'm trying to get to City Hall. Do you know--
SNAKE: Two blocks north. Take a left. It's a big building facing south.
HUMAN: Thanks. Bye. I guess.
[LAUGHTER]
MONARCH BUTTERFLY: Where is City Hall? It's like two blocks away. What do you need, a map, pal?
CARIBOU: Yeah. Who gets lost when you're only going two blocks? Poor humans. They're helpless without their GPSes and compass thingies.
[GIGGLES]
MONARCH BUTTERFLY: Yeah. I mean, navigating the world without a map is so easy. The secret is just--
SNAKE: Caribou herd, your table is ready.
MONARCH BUTTERFLY: I don't need to tell you the super obvious answer to how animals know their way around vast distances instinctually. You already know. Have a good dinner.
CARIBOU: Thanks! Have fun in Mexico. Watch out for spiders.
AUDIO TRACK: Brains On!
MOLLY BLOOM: All right, Anat. Hey, well, look at this. We've traveled through almost this entire episode and found our way back to the mystery sound. Here it is one more time.
[BARKS]
[BARKS]
[BARKS]
[BARKS]
OK, so any new guesses after hearing it again?
ANAT: Well, I'm still stuck with rainforest, except the sound that I think is supposed to be rain, it sounds glitchy, like--
MOLLY BLOOM: Oh. That's an interesting observation. I like that. So what do you think that screeching sound is? Last time you said it was a monkey. Do you think--
ANAT: Yeah, I don't know. I think it's some sort of creature that yells a lot.
[LAUGHS]
MOLLY BLOOM: Some very angry creature. Well, here is the answer.
TRISTAN GOOLEY: That was a muntjac deer giving an alarm call well.
MOLLY BLOOM: Yeah. That's natural navigator Tristan Gooley. He spends most of his days building mental maps out of observations he finds in the environments all over the world. Sometimes that includes animal noises.
TRISTAN GOOLEY: Most animals have a way of warning animals of the same species that there's danger in the area. And these are known as alarm calls. But quite a few animals have learned to use other species' alarm calls as well. So in the case of a deer giving an alarm call, it's telling us that that deer has spotted something in its surroundings.
Now that something might be us. But if we're pretty sure it's not us, we're not the ones that have surprised the deer and made it give a call, then it's telling us that something or someone else is out there.
[BARKS]
[BARKS]
There is a whole map available from sound. So part of them being a natural navigator is making use of things that most people don't tune into. And the wind is really, really important there. Everybody knows that the wind, when it hits trees, we hear a rustling sound in the leaves. But we hear different things depending where we are. You'll hear different things in the middle of a wood or if you're standing in open country. But as you get towards the edge of a wood, the sound changes.
MOLLY BLOOM: Following the path of the sun is one way to navigate. But Tristan uses it in another way.
TRISTAN GOOLEY: What's more interesting for most of my work is the way the sun leaves footprints on the landscape. So it shapes everything around us. It shapes trees. Trees are bigger on their southern side in the northern hemisphere. It even shapes the branches and even the leaves. The leaves on the south side of trees are smaller because of the sun.
MOLLY BLOOM: We've talked quite a bit about navigating uninhabited places, like the ocean or the forest. But there are clues in urban environments, too.
TRISTAN GOOLEY: The best thing to do is try and understand the story of why a town or a city is where it is. Quite often, we'll find that they were built up because that's where the only water is. And water will tend to be the lowest point of a town. And suddenly you realize that all the streets have a slight gradient. And if you're looking uphill, you're looking away from the water obviously, and downhill towards the water.
Or we might find the town is-- it's in a valley and it's the only route between high ground. And then suddenly we understand why all the streets are aligned the way they are. And then we go into much more detailed clues, like TV satellite dishes. They have to point to satellites that are over the equator.
So in the northern hemisphere, TV satellite dishes will be pointed broadly in a southerly direction. Depending which satellite they point out will tell you exactly which direction. Where I live, they point southeast. Other parts of the world, it might be southwest. But once you've spotted that trend, it's amazing how helpful it can be all over a big city.
MOLLY BLOOM: Check out naturalnavigator.com for more helpful navigation tips. Tristan suggests a fun natural navigation game without checking a map or GPS. Try to guess which way you're looking. Remember, use clues from your environment to help figure out the answer. You can check your answers on a phone or compass.
[BARKS]
OK, Anat. I am officially worried that Marc still isn't here.
ANAT: I know. Should we call somebody?
[KNOCKS]
MARC SANCHEZ: Hey. Did I make it? Is this still the Cardinal Directions episode?
MOLLY BLOOM: What happened to you?
MARC SANCHEZ: Well, there was this taco farm. Then I found my old apartment. And then the Sherbet Shack. And did from the southeast, our studio looks like a banana? Anyway, here are your tacos.
MOLLY BLOOM: Ooh, thank you, Marc.
ANAT: Yum.
MARC SANCHEZ: Did I miss the taping?
MOLLY BLOOM: Almost all of it, but you're in time to hear the Cardinal Directions song.
MARC SANCHEZ: You mean the one by Kanika Cook?
ANAT: Yeah.
MARC SANCHEZ: Ooh, that song is so good. It's like the hot sauce to my taco.
ANAT: Hit it.
[MUSIC PLAYING]
(SINGING) If you don't know which way to go to get in the right direction, get yourself a compass road or a map as your selection. North and south. North and south. East to west. East to west. Your cardinal direction. Cardinal direction. For your quest. A compass will always point north because of Earth's magnetic field. Use it to go back and forth. Now you know the deal. North and south. North and south. East to west. East to west. Your cardinal direction. Cardinal direction. For your quest.
Early maps were first drawn in Babylon and Greece. Influencing ways today, we navigate with ease. North and south. North and south. East to west. East to west. Your cardinal direction. Cardinal direction. For your quest. If you are looking at a map confused by all the symbols, there's a legend in the corner making it very simple. North and south. North and south. East to west. East to west. Your cardinal direction. Cardinal direction. For your quest.
[VOCALIZING]
ANAT: That was Kaniko Cook and her Cardinal Direction song. Check out kanikocook.com to hear more of her amazing music.
[MUSIC PLAYING]
MOLLY BLOOM: The cardinal directions have their origins in nature.
ANAT: The wind, the stars. And our biggest star, the Sun.
MOLLY BLOOM: Earth's magnetic field is formed by molten lava at its core.
ANAT: North wasn't always up on the map. But Ptolemy encompasses helped make it that way.
MOLLY BLOOM: Using a compass when there are other magnets nearby could give you a false reading.
ANAT: And humans aren't the only ones who can navigate long distances. Many kinds of animals travel far. But we're still not quite sure how they managed to do it.
MOLLY BLOOM: That's it for this episode of Brains On.
ANAT: Brains On is produced by Marc Sanchez, Sanden Totten, and Molly Bloom.
MOLLY BLOOM: We had production help from Ned Leebrick-Stryker and Tressa Versteeg and engineering help from Corey Schreppel and John Miller. Many thanks to Mark Robins and the Macaulay Library of Ornithology. And Molly, David McCarthy, Vicky Crocker, Taylor Kaufman, Mildred Marie Langford, Jennifer Miller, Austin Cross, Todd Masterson, Sam Choo, JB Shankman, and Alex Hui.
ANAT: Brains On is a nonprofit public radio production. Donations from listeners like you allow us to keep making new episodes.
MOLLY BLOOM: You can support Brains On today by heading to brainson.org/donate.
ANAT: Now before we go, it's time for a Moment of--
AUDIO TRACK: Um. Uh. Uh. Um. Um. Um. Um. Um. Um.
ELLIOT: My question is, why are diamonds so hard to find?
MARC HIRSCHMANN: My name is Marc Hirschmann. I'm a geologist. I'm a professor here at the University of Minnesota. My research involves the materials and rocks and minerals that exist deep in the earth. Diamonds, they're made of carbon. Everything, plants and animals and things, everything living has carbon in it. So it's a very common material on the surface.
But diamonds require more than just the presence of carbon. They require very high pressures. They require pressures in excess of what occurs deep in the earth more than about 100 miles. The thing that makes diamonds rare is although carbon is common on the surface, it's very scarce at depth. The common materials deep in the earth are not carbon rich. They're rich in other things-- magnesium, iron, silicon, and so on.
And so the first reason why diamonds are rare is because there's not a lot of carbon in the place where the pressures are high enough to make the form of carbon that is in the diamond structure. And the diamond structure requires high pressure for formation. The second reason is that even if they form down there, it's not so easy to get them to the surface. We certainly can't mine to that depth. We can't drill to that depth.
We have to wait for geologic processes to bring them to the surface. So we need very unusual volcanoes, known as kimberlites, that bring material very suddenly from great depth to the surface. Very rapidly. When kimberlite volcanoes erupt, they bring diamonds to the surface.
MOLLY BLOOM: These names are shining bright. It's time for the Brains Honor Roll. This is the way we thank the amazing listeners who send us their ideas, questions, mystery sounds, and drawings. They keep us going.
[LISTING HONOR ROLL]
AUDIO TRACK: Brains Honor Roll. High fives.
[ALARM]
ELEVATOR: Attention, Brains On headquarters. The elevator repairs are complete. The system will be restored in 5, 4, 3, 2, 1.
[DINGS]
Welcome to Brains On headquarters. What floor?
MOLLY AND ANAT: Elevator!
MOLLY BLOOM: Just in time to get us out of here.
ANAT: Thanks for listening.
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