StarTalk Radio - Things You Thought You Knew – Head in the Clouds

Episode Date: April 8, 2025

Why are there different types of clouds? Neil deGrasse Tyson and comedian Chuck Nice break down things you thought you knew about twilight, how clouds are made, and why Earth’s coastlines change. NOTE: StarTalk+ Patrons can listen to this entire episode commercial-free here: https://startalkmedia.com/show/things-you-thought-you-knew-head-in-the-clouds/Thanks to our Patrons Kevin, Jaden Peters, Margaret Berry, TheGSTip, Wisdom Ajayi, Thais Carvalho, Tye Bennett, Adam E, Joel Addis, Jurica Posavec, Cheryl Rudisill, Rob DeSanno, Joseph Fogas, Laura Fortier, Melyssa Bailey, Dustin Callas, Aubry Villanueva, Kyla Speakman, Nelson Hernandez, Eika Ng, Steve Gideon, Jake Schultz, Felipe, Sheldon Wilcox, David Sargent, Jason Ralston, Jim Young, Marcus Hart, Cletus Payne, Melinda DeRouen Mueller, Sharon Wright, michele mccarthy, Houston Nickelson III, Gowd Haraginadoni, Kurt_009, manny gonzalez, Fabrizio Hasselbach, Douglas James, Joe, Mohamed Echkouna, Mista Sandman, Javier Ortega A., Donna C McCulloch, Lanie Hollifield, and Sagan is King for supporting us this week. Subscribe to SiriusXM Podcasts+ to listen to new episodes of StarTalk Radio ad-free and a whole week early.Start a free trial now on Apple Podcasts or by visiting siriusxm.com/podcastsplus.

Hey, StarTalkians. I've got another Things You Thought You Knew coming your way. This time we're looking at twilight, clouds, and coastlines. But you gotta check it out to see how they connect and why. See you then. Welcome to StarTalk. Your place in the universe where science and pop culture collide. Star Talk begins right now. Chuck.

Yeah. I'm going to tell you about the three Twilights. No, no, no, no. I'm sorry, I've got to correct you on this one. There are four Twilights. You've got Twilight, then you've got New Moon, then you've got Eclipse, and then you got Breaking Dawn. I'm afraid the answer.

That man can bite me any day. Okay. I'm afraid the answer is incorrect. Okay, what? Astronomically speaking. Oh. This is a science show. Oh, okay.

Astronomical Twilight. That's crazy. Is a thing. That is an actual thing. So Chuck, I don't know if you know this, but there's three different kinds of twilight. Clearly I did not. Oh wait, yes I do know.

So there's the one in the evening, and then there's the one in the morning, and then there's the one where Edward takes my heart. That's not correct. Okay, I'm pretty sure it wasn't. But go ahead, What are the three? So Twilight in any given place on earth we rotate in such a way so that the Sun Dips below your horizon

Unlike some movies and some court cases and some people who think That the instant the Sun sets it's dark Right, okay Nothing could be more false who think that the instant the sun sets, it's dark. Right? Okay? Nothing could be more false than that. They made this mistake in Back to the Future when Marty goes back to 1955 and he's driving out

from the barn, because he visited the farmer's barn in his DeLorean, and it is dark at the beginning of the driveway, and at the end of the driveway, you see sunrise and it's light. No, no, that's not how that works. Okay, in John Wick four, there's this scene that happens early morning hours,

and he ascends this staircase up to this plateau, and it's dark, and then the sun rises, and then it's light. Okay, no, no, these people just have never looked up, okay? They think the sun alone, direct sunlight, is their only source of light. You know what else is lighting things up? The atmosphere. Okay. So the sun dips below the horizon.

Light is still illuminating the atmosphere above your head. Right. It is still glowing from sunlight. That's called twilight. We have a word for that, twilight. Oh, it's beautiful. It's beautiful. That's gorgeous.

It is beautiful. By the way, if we had no atmosphere and the sun went below the horizon, dark. Dark. Dark. Oh, you know they have that on the moon. Yes. Yes.

That's why all of our astronauts landed in the daytime. That's right. Okay. That's a good, because otherwise the lights go out. That's it, yeah. Like that. Okay. So you can ask, the deeper below your horizon the sun goes, the higher and higher up

the sunlight is hitting. So the lower atmosphere is more and more in darkness. Okay? If it's really far around the other side, there's no light illuminating any part of the air above you. We call that nighttime, right? Nighttime. Very good.

Just wanted to let you know I'm with you. All right, there are three kinds of twilight. There is civil twilight. All right, hello, I'm twilight. So terribly nice to meet you. Quite frankly, I don't want to offend you in any way if possible. I saw a comedy skit with civil engineers.

Right. And they're sitting there offering each other tea. After you. Would you like some? Would you care for another pinafore? Oh my good man, please, I wouldn't dare. Civil engineers. Civil engineers.

If only civil wars could be that polite. Oh, wouldn't that be something? You know, I would kill you, but that would be rather unpleasant, wouldn't it? A civil war. What's a civil war? Let's just play checkered. Exactly.

A civil twilight is until the sun is six degrees below the horizon. Six degrees below the, so okay, it's a Kevin Bacon twilight, gotcha. Six degrees, okay, okay. There's still some light in the upper atmosphere, still lighting it, but for practical purposes, for ordinary people, night time begins

when it's six degrees below. There you go. Civil twilight. Civil twilight. So people don't have much need for the sky, like other people do. So civil twilight, six degrees. Let's keep going.

There's another twilight called nautical twilight. Oh, okay. It's gotta be darker than civil twilight for them to use their sextant and their navigate by the stars. That makes sense. That makes sense. So the sun's gotta and their navigate by the stars. It makes sense. So the sun's gotta be 12 degrees below the horizon. Look at that.

Yeah. And at that point you start seeing many more stars for you to navigate by. Okay. Where six degrees, not so much. Right, because there's still light in the atmosphere. There's still a lot of light in the atmosphere above you. The sky's still glowing blue.

Right. The blue sky is light from the sun scattered back to you. On the moon, there is no scattered light, so the sky, daytime sky is as dark as night. Black. So nautical. Nautical. Civil, nautical.

They get some more stars to play with, okay? But the astronomers, we go deeper than what the eye can see. We bring out telescopes. I don't want Twilight messing with my telescopic views of the night sky. So we go an extra six degrees lower than nautical Twilight. Wow, 18 degrees. Below the horizon.

Only then is the end of astronomical twilight. Wow. Yeah. And what time would that be about? Well, no, so it depends. If you're near the equator, the angle that the sun sets to the horizon is almost vertical.

Right. So if you're going vertically down, you're booking into the darkness, okay? Twilight lasts like 15 minutes. I mean, have you ever been in the Caribbean? There is no culture of twilight in the Caribbean. Okay? It's light and then it's dark. Not instantaneously at sunset,

but the sun goes down fast. At most an hour. An hour. An hour later is 15 degrees below the horizon. You're done. You're done. You're done, okay? But the farther away from the equator you go

towards the poles, the sun's angle to the horizon gets shallower and shallower. So here comes the sunset, and how long does it take to get deep below it? Well, it's ambling its way along a hypotenuse, okay? Along a slopey angle, so twilight can last hours and hours. Do you know all of England sits north of the northernmost part of Maine?

Wow, I didn't know that. Of course not. So. Why would I ever know that?. Of course not. Okay, so. Why would I ever know that? So England has very long twilights. Very long twilights. Very long twilights. Oh, is that why, where is it?

Where they have like. Oh, so if you keep going even farther north. Yeah. Okay, there is no night, it's all twilights. It's just twilight. The sun never gets below your designated level. If it's astronomical twilight, it stays above 18 degrees, or above 12 for nautical, above six.

So then, my wife is from Alaska, they just, the Fairbanks, the Midnight Softball game on the solstice, the summer solstice. Yeah, it's just twilight the whole time. Yeah, so these are your twilights. I don't know how many people know about them. So recite them to me, what are they? So you got your civil, of course,

and then your nautical, and then your astronomical, or as we're gonna call that one, the neolite. Neolite. No, it's got to be, no. You don't like that? No. Because it's got your name in it.

No. No. So there you have it, three twilights. Nice. And when we go observing on mountaintops, we are given the time of astronomical twilight. So we can plan our observing schedule around that. Very cool.

I'm Kais from Bangladesh and I support Star Talk on Patreon. This is Star Talk with Neil deGrasse Tyson. Chuck, these don't stop. Okay, that's fine with me. Another explainer. Excellent. Okay, this one on clouds. Have we done a clouds one before?

Because you have better memory than I do. We have not done clouds. We have not done clouds. And you know, I wouldn't think there was a lot to talk about with clouds, and maybe that's why we haven't done it. But have you looked at clouds from both sides now? Okay, you mean top and bottom? That's good.

Joni Mitchell, forgive us. So, you ever wonder why clouds are just up there? I mean, I know. I mean, I haven't wondered. I mean, once I found out that clouds were basically water droplets, just basically vapor, they became extremely uninteresting to me at that point. Okay, let me get your interest back going for you.

Okay. Okay, all right. Allow me to remind you that the sun does not heat the air. That I understand. The sun heats the ground. And the ground radiates. And that heats the air. And it radiates in what band of light? Infrared. Infrared.

And CO2 in the atmosphere actually traps infrared. Right. Oh God, do I know. Okay, so. What a shame. So it's otherwise transparent to sunlight, to ordinary visible light, but once the ground absorbs it, it re-radates back infrared, there you get the trapping, what they call the greenhouse effect.

Okay, did you hear that people? That's how simple it is. Did you see how simple that is? Okay, comes in as visible light and passes through everything with no problem. Heats the ground, ground sends it back as infrared gets trapped, heats the earth, climate change. So how do you know the atmosphere

is transparent to visible light? How do we know? Yes. I don't know. Because you can see the sun. is transparent to visible light. How do we know? Yes. I don't know. Because you can see the sun. No. That makes sense.

If it were not transparent. If it weren't transparent. You wouldn't be able to see the sun. You wouldn't be able to see the sun. And there you have it. Okay. Right. Let me be more blunt.

Windows are transparent to visible light. Right. How do you know this? Because I can see through them. You can see through them. Right. Walls are not transparent to visible light. Because I'm not Superman. Because I'm see through them. You can see through them.

Right. Walls are not transparent to visible light. Because I'm not Superman. Okay. That's it. Okay, so Superman, back then, X-rays were like, relatively new. X-rays were discovered in like,

the first Nobel Prize in Physics was given for the discovery of X-rays. Wow. Yeah, so it was the late 1890s, 1900, was the first time that was awarded. So first Superman comic was maybe 1930s, so X-rays are still kinda cool. Yeah, they're like, woo.

All right, but radio waves go through walls also. Right. So he could have had radio wave vision. Then he'd have to tune in his eyes. Okay. So, but back then, X-ray was just metaphor for seeing through things. For seeing through things. Yeah, but back then x-ray was just metaphor for seeing through things. For seeing through things.

Yeah, that's all I wanted. Yeah, exactly. All right. So, infrared does not pass through windows. Not easily. Not easily? No. Okay.

Do this experiment. If you're in a fireplace, right, and you have some distance from the side, get someone to walk in front of you with a plate glass window. In that instant, you don't feel any of the radiant heat from the fire. That's right, the heat is blocked.

It blocked, okay? Okay, that's cool. It blocks it. So if you had infrared vision, a window is just the same thing as a wall to you. Right. Just think about that. Okay.

All right, so some things are not just inherently transparent, they're only transparent to certain wavelengths of light. All right, so now. And none just inherently transparent, they're only transparent to certain wavelengths of light. All right, so now, and none of that has anything to do with clouds. But that's framing information here. All right, sunlight heats the ground,

the ground heats the air. The farther away you are from the ground, the less heat you're getting. Right, that makes sense. Okay, have you ever tracked the temperature in an airplane? Sometimes they do it on the tractor plane thing. Right.

Okay, what's the temperature up there? Cold. Cold, thank you. That's the temperature. Is it exactly cold? Very, very cold. You measured it. Exactly. It's cold.

Cold. It could be as low as 40 below. Right, yeah. 40 below zero. And Peggy Lee's Fever? Right. All right, and we all know that song. You're giving me fever.

Do do do do do do do. In the morning. Right, right, and that's we know we all know that song you're giving me fever In the morning So all the occasions where one gets fever right right one of the stans stances toward the end is now you've listened to my story Here's the point that I have me chicks are born to give you fever Be it Fahrenheit or centigrade. Ooh. Getting both temperature scales. Yes. In the song.

In the most sexist way possible. And from a woman, that's how bad it was back then. That's how bad it was back then. Even the women were sexist. Chicks were born to give you fever. No, here's why I even went there. Go ahead. First of all, I'm giving him a hall pass

because Fahrenheit is a human being's name. Right. Who actually invented the thermometer, the mercury thermometer. Also American. Thermometer. Centigrade, that's not somebody's name. Right, that's a scale'm not gonna lie. I'm not gonna lie. I'm not gonna lie. I'm not gonna lie.

I'm not gonna lie. I'm not gonna lie. I'm not gonna lie. I'm not gonna lie. I'm not gonna lie. I'm not gonna lie. I'm not gonna lie. I'm not gonna lie.

I'm not gonna lie. I'm not gonna lie. I'm not gonna lie. I'm not gonna lie. I'm not gonna lie. I'm not gonna lie. I'm not gonna lie. I'm not gonna lie.

I'm not gonna lie. I'm not gonna lie. I'm not gonna lie. I'm not gonna lie. I'm not gonna lie. I'm not gonna lie. I'm not gonna lie. I'm not gonna lie. I'm not gonna lie. I'm not gonna lie. I'm not gonna lie. I'm not gonna lie. scale cross at 40 degrees below zero. Oh, interesting. 40 below zero, you don't even have to say.

You don't even have to say it. It's the same on both scales. It's just the same thing. The only temperature for which that is true. 40 below. Yes it is. Yo, that's kinda, that right, I'm ready to stop to explain right now.

That is great information. The only temperature that exists both Fahrenheit and centigrade at the same point is 40 degrees. 40 below zero. And it's within a degree of the temperature that mercury freezes, which is especially relevant to mercury thermometers.

As you get higher, the temperature drops because you're getting farther away from Earth's surface where the sun is heating. This reverses in the thermosphere where ultraviolet is absorbed by the ozone layer. What does that have to do with clouds? Because clouds are formed in warm, moist, unstable air. If you're unstable, it means you're not gonna stay

where you are, you're gonna rise. Have a pocket of air at sea level, or just near the ground. Oh, by the way, the official temperature that gets measured is at a predetermined height above the ground. Just so it can be standardized. Otherwise, you'd have different temperatures all over the place.

Everywhere. You're up in a building, you get a different temperature there than if you're sleeping on a picnic blanket. So they have to standardize that for this reason. All right, so now there's a pocket of air and it has some humidity level in it. Give me a percent, let's say it's 50% humid.

Not bad, New York City is very typical. Deserts, it's down in single digits. Rainforest is always above 80s, always up above 80s, 90s. New York is 50%. That humidity that is reported is actually a relative humidity. What that means is that is, it is 50% relative to how much it could carry at that temperature.

As the blob of air gets heated and rises, the temperature drops. Colder air can hold less humidity than warmer air. So the relative humidity goes up. It starts at 50 in this example, it goes to 60, then to 70, then to 80. So let's take 80. At 80%, you didn't add more water to it.

No. The capacity of the air to hold it dropped. Right. Okay, so nevermind. So there it is, it is ascending, 80, 90. Bada bing! You reach 100%. Right.

100% humidity. bada bing, you reach 100%. 100% humidity. The humidity condenses out as water droplets. Water vapor, basically. And boom, you have a cloud. That's why the cloud is up there and not down here. And now I know how clouds are born. That's how clouds are born.

And all this time I thought you had a mommy cloud and a daddy cloud and they loved each other very much. A stork cloud. That's kind of dope though. So, and it's because of this temperature gradient from high temperature to low temperature from the ground on up. Right. Okay.

There are two ways you won't get clouds. Okay. No matter your height. There's not enough humidity here. Right. Where even if it rises, it can go 10, 20, 30, 50, 70, and it never hits 100 before it gets way up in the air. No cloud.

No cloud. The other way is the blob of air has autonomy and a right to choose. It doesn't have to have a baby cloud if it doesn't want to. Oh, God. Is that where you were going with that? Okay. We were still on the baby making cloud.

I was well, sorry. Okay, I had moved on from that, but okay. I couldn't. You couldn't, you were still, okay. The juvenile brain stayed with it. My childlike brain. All right. But that makes sense because it's really about

the water that it's holding. So, and the relative humidity as it gets. The capacity to hold. The capacity to hold. To hold humidity. Okay, so now, so one way is it starts out so low, even though it gets high up, it never hits 100%. No cloud gets formed.

Another way is if you have descending air. Ooh. That can happen. So you can have, for example, a cold air moving through the mountains, and cold air is, and then it comes into a valley, and it descends, it comes down over the mountaintops, okay? If you have descending air, what's happening to the air?

The air temperature. Well, it's getting warmer. It's getting warmer! So, and then condensation again. It cannot keep holding more and more moisture. You're not making clouds. Right. So temperature. Well, it's getting warmer. It's getting warmer! So, and then condensation again. It can now keep holding more and more moisture. You're not making clouds. Right.

So descending air does not make clouds because it keeps getting warmer. Right. Ascending air with not enough moisture will not make a cloud because it'll never get to 100%. Right, okay. All right, so far this is cool. Okay, you ready?

Okay, so now, suppose there's no wind and you got like, let's say, 70% humidity. All right. The sun sets and the temperature drops, gets to 100%. What happened? What just happened? We made a cloud. Where do we make the cloud?

Where the air is. I mean, at the end. Thank you, Chuck, for that brilliant answer. Right in front of me. Yeah, of course, it would be right here. Right here. We have a new word for that kind of cloud. Do we really?

Yes. What? Fog. You got me. But that's fog. And that's the cloud. That's why when it's foggy, it's always a little cold. Yes. You ever notice that?

Yeah, yeah. It's a little cold. You ever notice that? It's a little cold. And it's a little dank, little chilly. So the fog is when you get this, you reach, it's called a dew point, to be precise. The dew point, and it's right at the ground level. And so it's interesting that in our language you have a different word for cloud above your head than for the same damn cloud right here, right in front language you have a different word for a cloud above your head than for the same damn cloud right here,

right in front of you. If the cloud formation is vigorous, like the temperature dropped real fast and it was really humid, it comes up there and it's still being unstable and it's rising and it's turning into water droplets, you get a cumulus cloud. Okay. Okay?

Okay? If this is intense and it's unrelenting and it continues to build, that cumulus cloud, which is just white with sunlight moving through it, it becomes less white. Okay. Because the droplets are getting bigger and bigger. Oh.

Okay. And it starts getting gray. Nice. We have a gray cumulus cloud. you get cumulonimbus. Okay. That stuff will hurt you. So the cumulonimbus, now the water droplets are so, it is so laden with water, it cannot contain the humidity.

Right. Even at 100%. And so the humidity nucleates, it finds droplets, dust in the humidity, even at 100%. And so the humidity nucleates, it finds dust in the air, things, it says, and other bits of water vapor collect to it. And it's held there for a while, because you have updrafts, because that's how you made the cloud in the first place.

But then it gets so big it drops out. So the more vigorous the cloud is, the heavier the raindrops are. Because it was holding them up. Okay? The very fast moving air is holding it up until it can't hold it up anymore and that big fat ass drop falls out of the sky

and you get the big drop thunderstorms. Okay? Now, let's say it's even more vigorous than that. big fat ass drop falls out of the sky and you get the big drop thunderstorms. Nice. Okay? Now, let's say it's even more vigorous than that. Uh oh. Okay? We went from cumulus nimbus to cumulus negro. That's when the clouds get black.

Black clouds. Yeah, they get black. They get black, okay? So. So, the updrafts are so severe. Right. Okay, oh, I forgot to tell you. No! No! No! No! No! No! No! No! No!

No! No! No! No! No! No! No! No!

No! No! No! No! No! No! No! No!

No! No! No! No! No! No! No! No! No! No! gets to a warmer air temperature and it just melts into rain. Right. Okay, so, all right. Now, imagine updrafts so strong that not even the raindrops can fall out. And it just stays up there.

The thing freezes and gets bigger and bigger. And then one day I say, I can't hold you anymore, I gotta let you go. And now it's too big to melt. Oh my God. And what do you get? You got hail. Hail. That's terrible. You got hail. And what do you get? You got hail. Hail.

That's terrible. You got hail. It's all because of the updrafts. Right. That's updrafts. That's an insurance cloud. Ha ha ha. So the conclusion here is the bigger the hail,

that means the bigger the hail pellets, spheres, the more severe the storm was. Right. Because it meant the updrafts were just so significant, it was so catastrophic, turning just moist air into. Giant balls of ice. Giant balls of ice, that's right. Damn, go on. By the way, with these puffy clouds,

it's why they're more frequent in the tropics, because you still have the ground heating, but you start out with such higher humidity air. Right. That when it rises, of course, you're going to puff up a cloud, like right there. Now, if you pop off a cloud here and not over there,

then it could be raining over there and not over here. Right. Yeah. Okay. And that's this, this is the conditions, almost all the conditions you need for a rainbow. Okay. Okay. And this is the conditions, almost all the conditions you need for a rainbow. Okay. Okay?

So to have a rainbow, you know it's very specific. I don't know if you knew this. Okay? Right. So it's gotta be raining in front of you and has to be late enough in the day for the sun to be low enough in the sky for the sun to be low enough in the sky for the sun to be behind you.

That makes sense. Okay? So it can create the. It would be a late afternoon thunderstorm. Right. That's over there. Right. The sun is behind you.

The sun is behind you. Right. Okay? That's why you never see a rainbow in the middle of the day. Because the sun is directly overhead. Right, and it's not raining under your knees. Right, there you go.

You would if in a sprinkler. Right. Lawn sprinkler. What if you're in a plane looking down? Yes! If you're in a plane looking down, you got full view. You can actually see it. Yeah. Awesome.

Yeah, you got it. That's great. Yeah, so these are the configurations here, and there are other kinds of clouds, like I said. Cirrus clouds, they can be transparent, but they mess with our viewing of the night sky. Little wispy, thin clouds. Right, right, and these are clouds

that just hang out up there, and they're just, they're very stable, cirrus clouds, and then you have weather fronts that come in, where there's a change in temperature. You never heard of a warm front coming in bringing bad weather. That's not how that works. Because if things get warmer,

you're gonna hold more moisture. It's when the cold front comes in. The cold front comes in. And you had warm air that had moisture and they meet at the boundary, it turns your moisture into rain, into storms, into clouds. And so it's always the cold front you gotta watch out for.

It's the drunk uncle at the cookout. The cold front. Just messing things up. All right, so, just one other interesting thing, I think. Okay. These are especially visible in airplanes. You see these long, I'll call them columns, but they're horizontal columns of clouds.

One after another. These are called cloud streets. Cloud streets? Streets. Cloud streets. Okay, because the clouds that I just described, the air goes up, but wait a minute, if air is going up, what's replacing that air?

Gotta be more air. More, more. Thank you, Chuck. That brilliant answer. Okay, so for every bit of air that goes up, there's air that drops down and comes in to fill the gap. So these are convective cells. It's, okay, that's what's happening here.

But in a cloud street, the convective cell is cylindrical. Interesting. Okay, so imagine a horizontal cylinder that's rotating. Oh, nice. Okay, on the side that's rotating up, you get cloud formation. And on the side that's rotating down, no clouds form. Right.

Because it's going, it's downward air. We've been through that, okay? And so, but wait a minute, how about the other cylinder? It has to be turning the opposite way. Otherwise they would cancel. You can have up air and down air simultaneously in the same place. So these cloud streets have cylinders rolling

with sides that match each other, both going down or both going up. So the next time you're in an airplane, look for this. It's beautiful. And it can go on for miles and miles. And so again, depending on how the terrain is heated, where the moisture is, is there a lake, is there an ocean, is there asphalt,

which heats hotter than other. So all of this makes for the beautiful diversity of clouds we see and love in the sky. That's very cool. And to think that all we ever do is look at them and see bunny rabbits and deer. And George Washington. Always George Washington.

No other president. He's got the, you know, he's got the do for it. That George Washington. Right. Always George Washington. Yeah. No other president. He's got the, you know. Yeah. He's got the do for it. Yeah, that's true. Yeah. So Chuck, asking me about coastlines. What's going on with coastlines, Neil? Thank you.

I thought you'd never ask. Yeah. Well, we're in my office here, so nothing is ever farther than an arm's reach for whatever I gotta use. So I'm just reaching right here. Okay. And look at that. I got the whole world.

There you go. In my hands. Did anyone sing that anymore? I bet they don't. No. No, because that was so Kumbaya, United Nations. It was like bring it all together. Bring it all together.

Hippie love. Hippie love, not anymore. Days are gone. All right, anyhow, so here's the Earth. When we think of Earth, we say to ourselves, there are bodies of water, oceans are the largest, and there's land. And we see this and we think about it as though it's a fundamental feature of our planet. That's Africa, because it has that shape.

Here's Asia with this coastline, and Japan is an island. We have this understanding of the world brought to you by settlers and explorers and politicians, with a few wars thrown in here and there. You always gotta have a war, a good war to bring about changes in geography. It's also color coded, Right.

which I came to realize in my cynical adulthood, are ways so that you can learn early on who your friends are and who your enemies are. Ooh. Because none of this is visible from space. No, it isn't. No, it's just land. so that you can learn early on who your friends are and who your enemies are. Because none of this is visible from space. No, it isn't. No, it's just land. And it's just land.

Okay, all right. So, when you take a look at a coastline, there's the urge to think there's something fundamental about it. But there isn't. Oh really? That's just the coastline today. That makes sense.

Okay. Have you seen maps where you can look through the ocean, through the water? Like in North America, for example, here we go. Have you ever seen maps where you can see that the continent extends a little further out underwater? Have you ever noticed that? You know what they call it?

No. The continental shelf. Right, yeah, that, yeah, I've seen. Have you ever noticed that? You know what they call it? The continental shelf. Right, yeah. I've seen that. You've seen that. And so it kind of follows our contour, but it's way, way out there. Exactly. And in fact, a lot of trash dumping activity

in the old days, now you process the trash, the old days, they would put on a barge and go beyond the continental shelf. Dump. Dump it there so it goes way down to the bottom. Right. Rather than possibly ever washing back up. Back up, right.

Okay, and I remember looking at it as a kid and I said, why does the shape of our continent continue underwater? I didn't understand that. Ooh. Because it's intriguing to me. Okay, do you know what that other edge is underwater? I'm not gonna lie to you, I'm not gonna lie to you. I'm not gonna lie to you. I'm not gonna lie to you. I'm not gonna lie to you. I'm not gonna lie to you. I'm not gonna lie to you. I'm not gonna lie to you.

I'm not gonna lie to you. I'm not gonna lie to you. I'm not gonna lie to you. I'm not gonna lie to you. I'm not gonna lie to you. I'm not gonna lie to you. I'm not gonna lie to you. I'm not gonna lie to you.

I'm not gonna lie to you. I'm not gonna lie to you. I'm not gonna lie to you. I'm not gonna lie to you. I'm not gonna lie to you. I'm not gonna lie to you. I'm not gonna lie to you. I'm not gonna lie to you.

I'm not gonna lie to you. I'm not gonna lie to you. I'm not gonna lie to you. I'm not gonna lie to you. I'm not gonna lie to you. I'm not gonna lie to you. I'm not gonna lie to you. I'm not gonna lie to you. I'm not gonna lie to you. I'm not gonna lie to you. I'm not gonna lie to you. Wait, hold on, when the oceans were drained, all these coastlines looked different. They were bigger. They were bigger.

They were bigger. Yeah. And so, well when was the way the oceans drained? During the ice age. Right. You know how ice ages work? You still have your oceans, and you still have evaporation,

because where does water come from that falls out of the sky? It used to be in the ocean. The oceans. Ocean, didn't come from land. No, of course not. Came from oceans and other bodies of water. All right, so the water evaporates up,

but Earth is really, really, really cold. So it goes into the cloud, and then the cloud goes over land, and it doesn't rain, it snows. And deposits that water. As snowflakes. Okay, so the snow is there. Does the snow ever make it back to the ocean? No! There we go. It stays there. And then another snowfall comes and another. And layers on top. And there's feet and

the yards and in some cases miles. Right. By the way, this is a great opportunity to take the time and explain to people that's how we know that climate change is real and that the amount of CO2 in the atmosphere is greater today than it was back then for all you people who say, oh, it's just cyclical. It's not a big deal. That's how we know from what Neil just described because of each one of those layers,

we can count the carbon dioxide. That public service message was brought to you by Chuck. Exactly. So stop it, it's real. Okay, anyway, go ahead. What happens is, once the oceans evaporate out and it snows on land, by the way, it'll also snow in the ocean, and then okay,

it'll just turn into water. It just turns back into water. Water, all right, so that's just fine. But for every snowflake that goes to land and never melts, you have systematically drained water from the oceans. And if this goes on for thousands of years, you then build these layers of snow to make a new form of ice, which is glacial ice.

It's not snow and it's not ice in your freezer. It's a different form of matter for the water molecule. Glacial ice. It's basically compactified snow. All right, it just stays there. It stays there, frozen. All right, so you're draining the ocean and as you drain the ocean, oh my gosh, what happened?

Oh, back here, where Alaska and Asia meet with the Bering Strait. Our ancestors. Walked over. Oh, they didn't take a boat. What? They didn't fly. What you doing Tuesday?

Let's take a walk. Take over a walk. So there they were in Asia, and there was a land and settlements there we've come to learn. They crossed into North America after having risen up out of Africa. Risen up in terms of longitude, latitude here,

up out of Africa into Europe. Others went into Asia. Some stayed low. Others went high. They get to that boundary. They cross over and they settle North America, Central America and South America. Then the Ice Age ends.

Right. Okay. Oh my God. What happened? We're so trapped. What happened to the land bridge? Well, no, that's long forgotten. Yeah.

Okay, it happens kind of slow. Right. And then it covers over. Ah. All right. Many generations. All right, so what, yes, but you are correct. With the water levels rising, changing all the coastlines,

has now stranded a branch, has now stranded a branch of the human species into North, Central, and South America. So we strand a branch of the human species into North and South America, and the water levels begin to rise. But at that time, the coastline of the Americas was that continental shelf.

Now imagine if people started building cities on that continental shelf. They'd all be gone today. What a shame. Okay, so what happens is the Ice Age ends, and the end of the Ice Age is a mixture of warmth and cold, where the cold has retained glaciers for tens of thousands of years,

up here in Greenland, and of course down here in Antarctica. and of course down here in Antarctica. Antarctica. And so that period is relatively stable. Yes, we have some storms and things, yes, but we have sustained one of the most climatically peaceful periods in recent Earth history. 10,000 years of relatively stable climate,

post Ice Age. And when you're relatively stable, you say, oh, well, where is the coastline? Here is the coastline. Let's put New York there, or New Amsterdam. Why? Because it's on a river, you can have irrigation, you have transportation, you have, what else do you use?

Commerce. Commerce, okay, business, all right. So, the coastline of all the world's nations today reflect 10,000 years of stable climate. reflect 10,000 years of stable climate. The glaciers stayed glaciers in the cold parts and other glaciers that had melted, had filled up the oceans, it's been stasis, relative stasis.

We are now warming earth beyond that period of time. And so the glaciers that are still there, that were in kind of equilibrium with us as we built civilization, and by the way, where are all major cities in the world? They're on the water's edge. On the coastline. Practically, except for Denver, right?

Practically every major city in the world, famous historical city, is on some kind of waterline. That's right, yep. Okay, so now we are warming the world, famous historical city is on some kind of water line. So now we are warming the earth. The glacial ice on Greenland, let's find Greenland right there, and the glacial ice on Antarctica, you say, well Greenland's not all that big and Antarctica's not, what are you worried about?

What about deep, da, da? If we lose all the glacial ice in Greenland, it'll melt and go into what? The ocean. The ocean. We melt it on Antarctica? Oceans. Goes into the ocean.

That's right. Raising the sea level. Rising sea level. Okay. If we lose all that glacial ice, the oceans will rise. Now, the Statue of Liberty is actually on a huge pedestal. I don't know if you knew that. It's huge. Almost as big as half the sea. At the bottom of the Statue of Liberty. At the bottom of the Statue of Liberty. Yeah on a huge pedestal. I don't know if you knew that. It's huge. Almost as big as the bottom of the Statue of Liberty.

Yeah, no, that's what she sits on. That's what raises up out of the bed. Exactly. So, the water levels will rise so high that it'll reach her left elbow. That's crazy. That means there will be no more Manhattan. You lose New York.

You lose New York. You lose all of North Jersey. You lose New York. You lose New York. You lose all of North Jersey. You lose, not that anybody cares. Let's be honest. Said no one ever. We lose New York and we lose North Jersey too. Said no one ever in the history of climate conversation. Who invited this guy?

The dude from Jersey. But my mama lives in North Jersey. So you lose all of that. And it's a different coastline. It is. It's a coastline. Once again. Without Florida.

There you go. Oh, so there's one good thing to climate change. Stop, no, stop, stop. Woo. Stop. We gotta protect all our 50 states. So the average elevation of Florida is six feet. Oh, forget it.

What? Say goodbye, Florida. You know, Florida has the lowest highest elevation of all 50 states. Wow, right. Can you follow that sense? That makes sense, because New Orleans is like below sea level,

so Florida has the lowest highest elevation. No, no, but in Louisiana, their highest elevation is way higher than the highest elevation of Florida. Right, that's what I'm saying. No, you can have places with low elevation. I'm talking about the average. The average.

Okay. Well, six feet would do it. Six feet. If you start with six feet, you ain't got nothing. Exactly. It's like, yeah, so basically your elevation is chuck plus an inch. You in a lot of trouble, man.

If you fly over, there's some satellite shots over Florida You're in a lot of trouble, man. If you fly over, there's some satellite shots over Florida and with the sun in the right angle, at the correct angle, you see these reflections off of these bodies of water throughout Florida. So of course there's the Okeechobee Lake, which is the big one right there in the middle. But you look around, it's like body of water, body of water, body of water, so it's like the water

is already ready to take over. Yeah, it's like we're just, we're waiting. Yeah. One day we will all join with one another. Bide your time, fellas. Our time is at hand. We have invited the oceans to join us. Exactly.

The oceans are on board. All we need now is time and their resolve not to do anything. They're human stupidity. So that's a whole other coastline. Look at that. So that's a whole other coastline of the future. And so now you're gonna look down on Earth and there's nothing inherent about the existence

of Florida on Earth's surface, that's my point. There you go. And there are other parts, we'll lose a lot of, in Northern Canada, there's a lot of sort of low-lying lands. Almost all of the South Pacific Island nations are gone. They also have very low elevations. Get your vacations in now. Get your vacations.

Florida, as we said, we lose Florida. The Florida Keys, in fact, have even a lower elevation than Florida itself. That's a shame. So they're gone, and Ken is gone, we're gonna lose Ken. I think he hung out at the Florida Keys. Yeah, exactly. You know.

So anyhow, I just want to impress upon you that when we think of Earth, there's nothing inherent about the existence of land poking up above the existence of water. Right. The water levels have changed over time and they're changing now and they're gonna redraw the map once again.

Cool and not cool. Like it's a great novel thing to know and consider but it's also terrifying that we, the difference is that was a natural engineering of coastlines that you explained before. That's a natural engineering of coastlines. What we have now is a anthropomorphic engineering. Right. an anthropomorphic engineering. Right, and in fact, like I said, we grew civilization on a stable climate

and a stable coastline. Right. And that took thousands of years before that to get to that point and stabilize out. Right. And now on a time scale of decades. Decades. Decades.

We're looking at maybe changing all of that. All of that. Yeah. There you have it. That is, oh no. All right, so Chuck, I don't mean to maybe changing all of that. All of that. Yeah. There you have it. That is. All right, so, Chuck, I don't mean to bum you out. I'm just saying. I'm so sad right now.

I'm so sad. In fact, one last thing, it's neither here nor there. When we talk about how much water is on a body, the way geologists refer to it is, how deep is the water if the water was the same depth everywhere on its surface? It's just a way to think about how much water is there. So if you take the water and spread it smoothly,

like icing on a cake, and so no, it's not filling in the low parts or trickling off the high parts. Just have it go everywhere, how much would it be? So you can say, well, how much water did Mars have? If you give an answer, it'll be in those terms. It would have 50 feet of water, or 1,000 feet of water, or 10 feet of water.

You'll just do this, conduct this exercise. When you do it, you learn things like Europa, one of Jupiter's moons, which is frozen on the outside, and liquid underneath. You add up that liquid, it's more liquid than all the oceans on Earth. And since all our evidence tells us life began in the oceans, that's why we can't wait to get our hands on that ocean

to see if there's any life forms on Europa, which we would have to then call them Europeans. Right, because we have life on Europa. Or we could just call them space white people. What? They're Europeans. Europeans, right. Because that's what's on Europa. Or we can just call them, you know, space white people. What? They're Europeans. Oh, if they're Europeans. Stop.

Don't, they're jokes. Stop. They're jokes, people. Stop it. So that's it. Chuck, that's yet another Star Talk explainer, delivered to you from the Cosmic Cribs. Aha.

Yeah, at the American Museum of Natural History, Hayden Planetarium. Neil deGrasse Tyson here, as always, keep looking up.