Things You Thought You Knew – The Geometric Universe

What is the Sun’s ecliptic? Neil deGrasse Tyson and comedian Chuck Nice break down the things you thought you knew about spheres in the universe, navigating the sky, and taking spacecraft out of orbit.

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

• 0:00Neil deGrasse Tyson?

  E equals mc.

• 0:02Chuck Nice?

  Square.

• 0:02Neil deGrasse Tyson?

  Square.

• 0:03Chuck Nice?

  We're squaring it.

• 0:03Neil deGrasse Tyson?

  Right. And what's on the other side of the equation?

• 0:06Chuck Nice?

  Energy.

• 0:06Neil deGrasse Tyson?

  E. So the energy goes as the velocity squared.

• 0:10Chuck Nice?

  Look at that.

• 0:11Neil deGrasse Tyson?

  And that's just. You've known that from birth.

• 0:12Chuck Nice?

  Didn't even know it.

• 0:13Neil deGrasse Tyson?

  Didn't even know.

• 0:13Chuck Nice?

  Didn't even know I didn't even know I knew that.

• 0:15Neil deGrasse Tyson?

  That's right.

• 0:16Chuck Nice?

  Look at that.

• 0:16Neil deGrasse Tyson?

  There you go.

• 0:17Chuck Nice?

  That's awesome.

• 0:20Neil deGrasse Tyson?

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

• 0:33Neil deGrasse Tyson?

  Chuck, I got another one for you.

• 0:34Chuck Nice?

  Okay.

• 0:35Neil deGrasse Tyson?

  What shape is Earth?

• 0:37Chuck Nice?

  Oh, you know, it sounds like a trick question.

• 0:41Neil deGrasse Tyson?

  No, no, no, it's not. No, just what's your first?

• 0:44Chuck Nice?

  Well, I'm looking around your office and I'm gonna say round.

• 0:46Neil deGrasse Tyson?

  Round.

• 0:47Chuck Nice?

  Cause there's a lot of globes in here.

• 0:48Neil deGrasse Tyson?

  There's a lot of round stuff.

• 0:49Chuck Nice?

  And there's a lot of round stuff.

• 0:50Neil deGrasse Tyson?

  Round. In fact, you know, in my office, nothing is more than arms reach away.

• 0:56Chuck Nice?

  Right.

• 0:56Neil deGrasse Tyson?

  Right, so Earth is round. The moon?

• 1:00Chuck Nice?

  I'm gonna say the same thing. There's the moon.

• 1:03Neil deGrasse Tyson?

  The moon is round. In fact, this is the correct relative size of the Earth and the moon.

• 1:08Chuck Nice?

  Earth and the moon.

• 1:08Neil deGrasse Tyson?

  Yeah.

• 1:08Chuck Nice?

  Nice.

• 1:09Neil deGrasse Tyson?

  Got you here, okay. The moon is round, how about the sun?

• 1:11Chuck Nice?

  The sun, see now, that's a different story, cause the sun is whatever it wants to be. See, because both the Earth and the moon are rocky, whereas the sun is like, baby, I'm plasma, baby.

• 1:24Neil deGrasse Tyson?

  It's all plasma.

• 1:25Chuck Nice?

  I do what I want. I do what I want.

• 1:26Neil deGrasse Tyson?

  It's all plasma, yet it's still round.

• 1:28Chuck Nice?

  Still round. Ah.

• 1:31Neil deGrasse Tyson?

  We got rock that's round and plasma that's round, okay?

• 1:33Chuck Nice?

  Nice.

• 1:34Neil deGrasse Tyson?

  You look around the universe, round is a thing.

• 1:37Chuck Nice?

  Yes, it is, pretty much. I mean, unless, of course, you know, you are a, how shall we say, an alternate thinker.

• 1:48Chuck Nice?

  Someone who likes to embrace the unusual.

• 1:51Neil deGrasse Tyson?

  Something.

• 1:51Chuck Nice?

  Yeah.

• 1:52Neil deGrasse Tyson?

  With the word flat in it.

• 1:54Chuck Nice?

  Yeah, you like discs. You believe in discs. You're my flat person.

• 1:58Neil deGrasse Tyson?

  Flat discs.

• 1:59Chuck Nice?

  You know, so yeah, but yeah, no, you look around and everything's round.

• 2:03Neil deGrasse Tyson?

  Okay.

• 2:04Chuck Nice?

  Or if it's not round, it's trying to be round.

• 2:07Neil deGrasse Tyson?

  Yeah, so there's laws of physics related to that. So when I use the word round, I'm referring to basically something that's spherical.

• 2:14Chuck Nice?

  Right.

• 2:14Neil deGrasse Tyson?

  Okay, because technically a circle is round.

• 2:17Chuck Nice?

  Yes.

• 2:17Neil deGrasse Tyson?

  But if you say circle, it's a circle, there are no circles in the universe.

• 2:20Chuck Nice?

  Right.

• 2:21Neil deGrasse Tyson?

  Okay.

• 2:21Chuck Nice?

  Right.

• 2:21Neil deGrasse Tyson?

  Everything has a shape. They're three dimensional.

• 2:23Chuck Nice?

  They're three dimensional.

• 2:24Neil deGrasse Tyson?

  Right, right, right.

• 2:25Chuck Nice?

  Even a black hole isn't a circle.

• 2:27Neil deGrasse Tyson?

  Yeah, that's right, it's spherical, right? So even in the Bible, it refers to earth as a circle.

• 2:33Chuck Nice?

  Okay.

• 2:33Neil deGrasse Tyson?

  Okay, the circle of the earth.

• 2:34Chuck Nice?

  I know, okay.

• 2:35Neil deGrasse Tyson?

  And there are people, the Christian apologists, who are defenders of the faith.

• 2:43Chuck Nice?

  Right.

• 2:43Neil deGrasse Tyson?

  Will say that that's, the Bible knew the earth was a sphere. But anyone at the time saw the word circle and drew circles.

• 2:49Chuck Nice?

  Right.

• 2:50Neil deGrasse Tyson?

  For all maps of the earth, with Jerusalem in the middle and water surrounding.

• 2:54Chuck Nice?

  Right.

• 2:54Neil deGrasse Tyson?

  A coastline and demons off the edge of the map. So, but the point is, in the universe.

• 3:01Chuck Nice?

  Mm-hmm.

• 3:01Neil deGrasse Tyson?

  Forces conspire to make round things.

• 3:06Chuck Nice?

  Nice.

• 3:07Neil deGrasse Tyson?

  Okay?

• 3:07Chuck Nice?

  Okay.

• 3:08Neil deGrasse Tyson?

  All right, so, let's start with soap bubbles.

• 3:12Chuck Nice?

  I mean, when we're talking about the universe, why not?

• 3:14Neil deGrasse Tyson?

  Why not? It was like when you saw a triangular soap bubble. Never, okay, no.

• 3:19Chuck Nice?

  I'm sad now, I'm very sad. Because I've never seen a triangular soap bubble.

• 3:24Neil deGrasse Tyson?

  Or a cube.

• 3:25Chuck Nice?

  And/or a cube, and now I want to see both of those, so bad, I don't know what to do.

• 3:29Neil deGrasse Tyson?

  So, in a soap bubble, you have this film.

• 3:33Chuck Nice?

  Right.

• 3:34Neil deGrasse Tyson?

  And the film wants to be as small as possible.

• 3:40Chuck Nice?

  Okay.

• 3:41Neil deGrasse Tyson?

  Okay, now if there's any part of the film that's sticking out.

• 3:45Chuck Nice?

  Mm-hmm.

• 3:46Neil deGrasse Tyson?

  It says to itself, I can make it smaller than that. Okay?

• 3:51Chuck Nice?

  Right.

• 3:51Neil deGrasse Tyson?

  So all parts of the film want to make the whole structure as small as possible.

• 3:57Chuck Nice?

  Okay.

• 3:58Neil deGrasse Tyson?

  And there's only one shape that accommodates that, and that's a sphere.

• 4:02Chuck Nice?

  Okay.

• 4:03Neil deGrasse Tyson?

  Now here's what's interesting.

• 4:04Chuck Nice?

  Mm-hmm.

• 4:05Neil deGrasse Tyson?

  For a given amount of material, surface.

• 4:10Chuck Nice?

  Mm-hmm.

• 4:11Neil deGrasse Tyson?

  The shape that contains the largest volume.

• 4:16Neil deGrasse Tyson?

  Is a sphere. Okay, got you. Right. I see what you're saying. It's an interesting fact. Okay. Okay. So for, so if you have a nice spherical fruit. Mm-hmm. Okay. I'm hungry now. If you make that any other shape. Right. It's gonna bust out the side. Right, I know that cuz I have stepped on many oranges. Why doesn't the orange just? Right. No. No. No. It's just, it's right out the side. Right out the side. Exactly. Okay. Right. Same thing will happen if you step on a, on a, on a water bug. Just pops right out. Does, yes. They're not spheres, but they're, they're trying to be. Right. Alright. And in my little neighborhood, you could hear them scream. Scream? That's how big they were. They said, "Get the hell off of me."

• 5:03Neil deGrasse Tyson?

  That's a serious water bug. Hey, what the hell? Get the hell off of me. Back your ass up. Can't you see I'm walking here? That's funny. I'm walking over here.

• 5:15Neil deGrasse Tyson?

  Uh, that's funny. Alright. Okay. So, this thing with spheres, what it also does is brings the material inside of it as close to itself as it can possibly be. Nice. Once you start flattening it out. Mm-hmm. The parts that are farther away from other parts than they would otherwise be if it was in a sphere. Okay. Okay, okay. By the way. Right. Have you ever seen a cold pigeon?

• 5:43Neil deGrasse Tyson?

  I don't think I've ever seen a warm pigeon. You don't know the difference? I don't know what the difference is. Okay, if you look at, if you look at pigeons, we're in a city here, so I'm referencing pigeons. We get birds in general. Right. They're warm-blooded. Yes. How do they stay warm? First they have like feathers. Right. Which are highly insulating. Right. Which is why we yank them off birds and stick them in our coats. Right, yes, exactly. And are, alright. Called down, it's called down. Down, right, right. Alright, so, the, the bird gets as round as it possibly can.

• 6:11Chuck Nice?

  Oh.

• 6:12Neil deGrasse Tyson?

  Just take a look at a pigeon in the cold. It is round.

• 6:15Chuck Nice?

  They puff up.

• 6:16Neil deGrasse Tyson?

  They puff up and they're round.

• 6:18Chuck Nice?

  As they can, yes.

• 6:19Neil deGrasse Tyson?

  And that way, there are no extremities at risk. They've reduced how flat or extended they would otherwise be. Okay, so even cold pigeons want to be round.

• 6:30Chuck Nice?

  Nice.

• 6:31Neil deGrasse Tyson?

  For thermodynamic reasons.

• 6:32Chuck Nice?

  Yep. Cold pigeon sounds like the worst hood liquor. It's like, you know.

• 6:39Neil deGrasse Tyson?

  Worse than cold duck?

• 6:40Chuck Nice?

  Yeah, worse than cold duck. Oh, man, I can't afford cold duck. You must be rich. I'm drinking cold pigeon.

• 6:51Neil deGrasse Tyson?

  Pigeons, I tell you, pigeons get no respect.

• 6:53Chuck Nice?

  Oh, man.

• 6:54Neil deGrasse Tyson?

  You know what their formal name is?

• 6:55Chuck Nice?

  No.

• 6:55Neil deGrasse Tyson?

  In the wild?

• 6:56Chuck Nice?

  No.

• 6:56Neil deGrasse Tyson?

  Rock doves.

• 6:57Chuck Nice?

  Rock doves?

• 6:58Neil deGrasse Tyson?

  Yes, and they evolved in, in canyons.

• 7:02Chuck Nice?

  Okay.

• 7:02Neil deGrasse Tyson?

  And they swooped down and up in the canyons, and they live on the walls of the canyons.

• 7:06Chuck Nice?

  Rock doves?

• 7:07Neil deGrasse Tyson?

  Right, and so cities, what are they if not steel canyons?

• 7:12Chuck Nice?

  That's absolutely right.

• 7:14Neil deGrasse Tyson?

  There it is, and they, and we share our, our space with them.

• 7:18Chuck Nice?

  Yes, we do, and, and our shoulders with, with their leavings. And supposedly, that's good luck.

• 7:26Neil deGrasse Tyson?

  All right, so now let's get out of the earth and go into the universe. If you gather matter together in the universe, you can say, well, what shape will it take? Well, if it's rock, the rock is happy being a rock.

• 7:38Chuck Nice?

  Okay.

• 7:39Neil deGrasse Tyson?

  It'll be whatever shape the rock is.

• 7:40Chuck Nice?

  Mm-hmm.

• 7:42Neil deGrasse Tyson?

  Most asteroids just look like rocks.

• 7:44Chuck Nice?

  True.

• 7:45Neil deGrasse Tyson?

  All right, some of them may be Idaho potatoes, but they're not spherical.

• 7:49Chuck Nice?

  Right.

• 7:51Neil deGrasse Tyson?

  Because they don't have enough gravity to overcome the rock.

• 7:55Chuck Nice?

  Right.

• 7:56Neil deGrasse Tyson?

  The structural integrity of the rock is what's determining the shape of the asteroid. Above a certain size, the gravity of all the material overcomes whatever the rock wants to do by itself.

• 8:11Chuck Nice?

  Hmm.

• 8:12Neil deGrasse Tyson?

  And the high places, the material will fall into the low places.

• 8:16Chuck Nice?

  Mm-hmm.

• 8:17Neil deGrasse Tyson?

  And this will continue until basically you have a sphere on your hands.

• 8:20Chuck Nice?

  Look at that.

• 8:22Neil deGrasse Tyson?

  So, one of the criteria for the definition of a planet.

• 8:27Chuck Nice?

  Uh-huh.

• 8:28Neil deGrasse Tyson?

  Is, is it big enough to be a sphere?

• 8:30Chuck Nice?

  Right.

• 8:32Neil deGrasse Tyson?

  Pluto satisfies that criterion. Uh oh, watch out. I have to make a retraction. No, there are other rules Pluto fails, but it satisfies that one. Of being round. Be on being round. Uh huh. It has enough mass for it to structurally, because this is gravity at work. Gravity says, everybody come to the center. Mm hmm. And there's only one shape that can get the most number of people as close to the center as they can possibly be, and that's. A sphere. A sphere. Right. Exactly. Pluto's moon is even a sphere. Wow. Charon. Charon.

• 9:09Neil deGrasse Tyson?

  Now, why is the moon called Charon? I don't know. Charon is the ferryboat driver who takes your sorry ass across the river Styx to Hades. Yeah, to where Pluto is. Right. Well, it's the Greek version of the Roman. So that's how we name our moons, the Greek. Not a part of the life of the Roman god, if the Roman god were Greek. Right. Right. Alright, so, let's keep going. The sun. Mm hmm. It's got badass gravity. Yes. And it's got gas. Yeah. It's holding on to its gas.

• 9:42Neil deGrasse Tyson?

  I'm sorry. I couldn't help it, I'm so juvenile. I know, that is like, are you eight years old Chuck?

• 9:51Neil deGrasse Tyson?

  You can't resist the scatological. I didn't make a joke, but I couldn't stop laughing.

• 9:58Neil deGrasse Tyson?

  The sun holds, generally holds its gases. Yes. Occasionally there are effluences, which we call solar flares. Yes, exactly. Alright, so, well, the gas, it's trying to get to the center of the sun too. Everybody's trying to get to the center of the gravity. The shape that results from that is a sphere. Okay. Period. That's it. That's all it is. Alright, and this persists for every star, for every planet, for large non-planets. Right. Like Pluto, one of the asteroids got, you know, Pluto got demoted with these, this new rule, but there's an asteroid that got promoted. Okay. The asteroid Ceres. Ceres. The largest asteroid. Asteroid.

• 10:41Neil deGrasse Tyson?

  Okay, named for the goddess of harvest. Okay. And that's where we have the root for the word cereal. Oh, nice. Ceres cereal, okay. Cereal. Ceres.

• 10:55Neil deGrasse Tyson?

  Was the only spherical asteroid.

• 10:58Chuck Nice?

  Right.

• 10:58Neil deGrasse Tyson?

  So it satisfied the sphere criterion, but it didn't satisfy the other two. So we, it graduated to dwarf planet.

• 11:05Chuck Nice?

  Oh, look at that.

• 11:05Neil deGrasse Tyson?

  Yeah, yeah. So Pluto had company in this new, Pluto got demoted, others got promoted, and now they got a new family there.

• 11:12Chuck Nice?

  They got a new family, dwarf planet.

• 11:13Neil deGrasse Tyson?

  Okay, so now, so we have, we have the, the laws of surface tension, I didn't use that term at the moment, the laws of surface tension help us create soap bubbles. It's also what beads up liquid if you just waxed your car.

• 11:27Chuck Nice?

  Right.

• 11:28Neil deGrasse Tyson?

  It wants to be a sphere.

• 11:29Chuck Nice?

  Right.

• 11:30Neil deGrasse Tyson?

  So bad. And every part that's not touching the car is round, all right?

• 11:35Chuck Nice?

  Exactly.

• 11:36Neil deGrasse Tyson?

  All right. If you dripped liquid in zero G.

• 11:44Chuck Nice?

  Right.

• 11:45Neil deGrasse Tyson?

  Surface tension, pop, pop that into a sphere, right?

• 11:47Chuck Nice?

  Right away.

• 11:47Neil deGrasse Tyson?

  Straight away.

• 11:48Chuck Nice?

  Yeah.

• 11:48Neil deGrasse Tyson?

  There's a scene in Star Trek.

• 11:51Chuck Nice?

  I know what you're talking about, where they shoot.

• 11:54Neil deGrasse Tyson?

  They, they shoot the Kling, the Klingons in the room.

• 11:57Chuck Nice?

  And, and they're in zero G because they turned off the artificial gravity in the ship, and the blood.

• 12:03Neil deGrasse Tyson?

  The blood spews out.

• 12:04Chuck Nice?

  All in big droplet forms that are round.

• 12:07Neil deGrasse Tyson?

  Spherical blob.

• 12:08Chuck Nice?

  Yeah.

• 12:09Neil deGrasse Tyson?

  And people after that said, that's weird, they must have weird blood. No, your blood would do that too.

• 12:14Chuck Nice?

  Right.

• 12:15Neil deGrasse Tyson?

  In zero G.

• 12:15Chuck Nice?

  Right.

• 12:16Neil deGrasse Tyson?

  But in one G, the blood goes down and drops on the ground.

• 12:19Chuck Nice?

  Right.

• 12:20Neil deGrasse Tyson?

  Okay? Now, in zero G, you can make an arbitrarily large blob of liquid, unless you bring it into any kind of G at all, and then the gravity overcomes the surface tension and it flattens out.

• 12:33Chuck Nice?

  Right.

• 12:34Neil deGrasse Tyson?

  That's why you can't just haul a blob of water out of the ocean and, you know, put it in a, put it in a, in a display case as a sphere.

• 12:45Chuck Nice?

  Right.

• 12:45Neil deGrasse Tyson?

  Earth's gravity overcomes that.

• 12:47Chuck Nice?

  Right.

• 12:48Neil deGrasse Tyson?

  Okay? So, it's a, it's a contest of forces at all times. Uh, Earth's gravity overcomes the rocks.

• 12:56Neil deGrasse Tyson?

  The sun's gravity overcomes the gas. Everybody gets a sphere out of this. So, in the universe, you have exceptions to this when you have rapidly rotating objects.

• 13:07Chuck Nice?

  Okay. All right.

• 13:09Neil deGrasse Tyson?

  Guess what happens to them?

• 13:11Chuck Nice?

  Uh, they flatten out.

• 13:12Neil deGrasse Tyson?

  They flatten out.

• 13:13Chuck Nice?

  Mm-hmm.

• 13:13Neil deGrasse Tyson?

  Saturn rotates once every something like ten hours.

• 13:17Chuck Nice?

  Wow.

• 13:17Neil deGrasse Tyson?

  Saturn is big and it rotates twice as fast as we do. My boy's flattened.

• 13:21Chuck Nice?

  Yes.

• 13:22Neil deGrasse Tyson?

  Ten percent flattened. It's ten percent shorter pole to pole than side to side.

• 13:27Chuck Nice?

  Wow.

• 13:27Neil deGrasse Tyson?

  Next time you look at a photo, check that out. You can notice it easily with your eyes.

• 13:32Chuck Nice?

  Okay.

• 13:32Neil deGrasse Tyson?

  So...

• 13:33Chuck Nice?

  How about the rings? Are the rings rotating at the same, uh, as rate as the planet?

• 13:38Neil deGrasse Tyson?

  No, no, no, they're rotating.

• 13:39Chuck Nice?

  Are they rotating in the planet independently?

• 13:42Neil deGrasse Tyson?

  According to their own orbital physics.

• 13:44Chuck Nice?

  Each one of them has their own orbital physics.

• 13:45Neil deGrasse Tyson?

  So why aren't they a sphere? Well, when the moon formed, because we got slammed by a protoplanet in the early universe, in the early solar system.

• 13:54Chuck Nice?

  Right.

• 13:55Neil deGrasse Tyson?

  We had, we had a ring of debris.

• 13:57Chuck Nice?

  Mm-hmm.

• 13:58Neil deGrasse Tyson?

  But some debris was a little larger than other debris, which means it had a little bit more gravity than the other. You get a little bit more, then you get a little extra stuff. Now you have even more gravity.

• 14:08Chuck Nice?

  Come join me. One of us. One of us.

• 14:12Neil deGrasse Tyson?

  And so this is a runaway process.

• 14:13Chuck Nice?

  Right.

• 14:14Neil deGrasse Tyson?

  So the ring coalesces to become

• 14:16Chuck Nice?

  The moon itself.

• 14:17Neil deGrasse Tyson?

  Our moon itself.

• 14:18Chuck Nice?

  Wow, that's great.

• 14:19Neil deGrasse Tyson?

  Yeah, and so you get the sphere ultimately.

• 14:22Chuck Nice?

  Right.

• 14:22Neil deGrasse Tyson?

  And one of the saddest moments in my professional life was reading a research paper on the dynamics, the orbital dynamics of the particles in Saturn's rings. And they said it's a temporary phenomenon.

• 14:32Chuck Nice?

  Oh.

• 14:33Neil deGrasse Tyson?

  That was sad.

• 14:34Chuck Nice?

  That is, that means Saturn's gonna lose its ring.

• 14:35Neil deGrasse Tyson?

  Yes, and then it probably didn't have its rings ten million years ago, which meant the dinosaurs, if they had telescopes and looked at the Saturn, it would have had no rings.

• 14:43Chuck Nice?

  Look at that.

• 14:43Neil deGrasse Tyson?

  That's sad.

• 14:44Chuck Nice?

  That is sad.

• 14:44Neil deGrasse Tyson?

  That's sad. So anyhow, so I wrote a whole essay twenty-five years ago called "On Being Round."

• 14:51Chuck Nice?

  On Being Round?

• 14:51Neil deGrasse Tyson?

  I think it's online, too. Just go "On Being Round" and Tyson. Church deGrasse, just in case Mike Tyson did something round.

• 14:58Speaker 02

  That's right. I, I have, I have a thing called, I, I have a thing called "Stick Around."

• 15:04Neil deGrasse Tyson?

  Stick around?

• 15:04Speaker 02

  Stick around. That's, that's why I tell you.

• 15:07Neil deGrasse Tyson?

  You might be glad he ain't here to whoop your ass, imitating him.

• 15:10Speaker 02

  I wouldn't stick around for that. That's the whole point of my thesis.

• 15:18Neil deGrasse Tyson?

  So, so you search for "on being round" and you get the full discussion there.

• 15:23Chuck Nice?

  Nice.

• 15:24Neil deGrasse Tyson?

  Or you just heard this, so you don't even need to read this.

• 15:26Chuck Nice?

  Exactly.

• 15:27Neil deGrasse Tyson?

  It's a 2,000-word essay.

• 15:28Chuck Nice?

  Right. And for all of you disk lovers, you flat disk lovers, there you go. This is why, you know, what you believe is stupid.

• 15:38Neil deGrasse Tyson?

  Oh, the flat Earth folk. Yeah. So, and our galaxy is very flat.

• 15:42Chuck Nice?

  Right.

• 15:42Neil deGrasse Tyson?

  Okay, when it formed.

• 15:43Chuck Nice?

  Right.

• 15:44Neil deGrasse Tyson?

  Okay. As it formed, material falling from the top and the bottom was gaseous. It stuck together in the midplane and then formed stars there.

• 15:53Chuck Nice?

  Right.

• 15:54Neil deGrasse Tyson?

  Because the gas clouds don't have a, they don't pass through. They stick together like hot marshmallows.

• 15:58Chuck Nice?

  Right.

• 15:58Neil deGrasse Tyson?

  Touching, you know, in midair.

• 16:00Chuck Nice?

  Yeah.

• 16:01Neil deGrasse Tyson?

  So, so whenever you find something that's not a sphere, there's a fascinating reason why that's the case. But the natural state of the universe is, and black holes, there's non-rotating black holes is a sphere. If you want to rotate it, it will flatten out.

• 16:15Chuck Nice?

  Right.

• 16:15Neil deGrasse Tyson?

  As rotating things do. And you'll get like a Taurus or a donut.

• 16:19Chuck Nice?

  Ah, nah.

• 16:20Neil deGrasse Tyson?

  So rapidly rotating black holes are actually donuts, which are still kind of round.

• 16:23Chuck Nice?

  Yeah, exactly.

• 16:24Neil deGrasse Tyson?

  In their own way.

• 16:24Chuck Nice?

  Yeah.

• 16:25Neil deGrasse Tyson?

  Yeah.

• 16:33Speaker 03

  I'm Nicholas Costella and I'm a proud supporter of StarTalk on Patreon. This is StarTalk with Neil deGrasse Tyson.

• 16:47Neil deGrasse Tyson?

  Okay, lines in the sky.

• 16:49Chuck Nice?

  Lines in the sky.

• 16:51Neil deGrasse Tyson?

  Okay.

• 16:52Chuck Nice?

  All right.

• 16:53Neil deGrasse Tyson?

  All right. So, let's start.

• 16:55Chuck Nice?

  All right.

• 16:56Neil deGrasse Tyson?

  Okay? You're standing there.

• 16:58Chuck Nice?

  Okay.

• 16:59Neil deGrasse Tyson?

  And you're looking due south.

• 17:00Chuck Nice?

  All right.

• 17:01Neil deGrasse Tyson?

  Okay?

• 17:02Chuck Nice?

  Okay.

• 17:02Neil deGrasse Tyson?

  You take your hand and draw a line from due south.

• 17:07Chuck Nice?

  Okay.

• 17:07Neil deGrasse Tyson?

  Directly overhead to due north.

• 17:11Chuck Nice?

  All right.

• 17:11Neil deGrasse Tyson?

  You do that, okay?

• 17:13Chuck Nice?

  Okay.

• 17:14Neil deGrasse Tyson?

  That line has a name.

• 17:16Chuck Nice?

  All right.

• 17:16Neil deGrasse Tyson?

  Yes, it does. And by the way, it's not the same for everybody. If you go east of me.

• 17:21Chuck Nice?

  Right.

• 17:21Neil deGrasse Tyson?

  You're gonna make your own line.

• 17:22Chuck Nice?

  Right.

• 17:23Neil deGrasse Tyson?

  North to south.

• 17:24Chuck Nice?

  Right.

• 17:24Neil deGrasse Tyson?

  Okay? So, everybody, depending on where you are in longitude on earth, you're gonna have your own line.

• 17:32Chuck Nice?

  Okay.

• 17:33Neil deGrasse Tyson?

  Okay?

• 17:33Chuck Nice?

  That makes sense.

• 17:34Neil deGrasse Tyson?

  Okay. That line has a name.

• 17:36Chuck Nice?

  Okay.

• 17:37Neil deGrasse Tyson?

  You know what it's called?

• 17:37Chuck Nice?

  No.

• 17:38Neil deGrasse Tyson?

  The meridian.

• 17:39Chuck Nice?

  Okay.

• 17:40Neil deGrasse Tyson?

  The meridian.

• 17:41Chuck Nice?

  We'll call it Mary.

• 17:43Neil deGrasse Tyson?

  Now, I need you to remember this.

• 17:45Chuck Nice?

  The meridian.

• 17:46Neil deGrasse Tyson?

  The meridian.

• 17:47Chuck Nice?

  Got it. It's a great hotel, by the way.

• 17:49Neil deGrasse Tyson?

  Okay, okay. All right?

• 17:51Chuck Nice?

  Yes.

• 17:52Neil deGrasse Tyson?

  So, the meridian. Everyone has a meridian, and it goes directly over their head, connecting due south to due north.

• 17:57Chuck Nice?

  Okay.

• 17:57Neil deGrasse Tyson?

  That's one of the lines in the sky. Okay?

• 18:00Chuck Nice?

  Okay.

• 18:01Neil deGrasse Tyson?

  The sun, when it rises, okay?

• 18:05Chuck Nice?

  Mm-hmm.

• 18:05Neil deGrasse Tyson?

  Works its way towards your meridian.

• 18:09Chuck Nice?

  Okay. Yes. Watching it. It's coming, coming, coming.

• 18:13Neil deGrasse Tyson?

  Comes from the east.

• 18:13Chuck Nice?

  It's there.

• 18:14Neil deGrasse Tyson?

  No, no, no. It's coming from the east.

• 18:16Chuck Nice?

  Right.

• 18:17Neil deGrasse Tyson?

  And it'll cross your meridian.

• 18:18Chuck Nice?

  Right.

• 18:19Neil deGrasse Tyson?

  Go to the other side of your meridian, and then set.

• 18:21Chuck Nice?

  Okay.

• 18:22Neil deGrasse Tyson?

  Okay?

• 18:22Chuck Nice?

  That makes sense.

• 18:23Neil deGrasse Tyson?

  Okay.

• 18:26Neil deGrasse Tyson?

  Do you know what AM stands for?

• 18:29Chuck Nice?

  Um, AM, after midnight.

• 18:33Neil deGrasse Tyson?

  No.

• 18:34Chuck Nice?

  No.

• 18:36Chuck Nice?

  Okay. Oh! Let me think. Something meridian.

• 18:41Neil deGrasse Tyson?

  Antemeridian.

• 18:42Chuck Nice?

  There you go. Anti- anti.

• 18:44Neil deGrasse Tyson?

  Ante. Like, like antebellum. It's before.

• 18:47Chuck Nice?

  Before.

• 18:48Neil deGrasse Tyson?

  Antemeridian.

• 18:49Chuck Nice?

  Antemeridian.

• 18:50Neil deGrasse Tyson?

  Before the meridian.

• 18:51Chuck Nice?

  Right. And so then PM must be post- meridian.

• 18:56Neil deGrasse Tyson?

  There you go. It's where we get AM and PM from.

• 18:59Chuck Nice?

  I thought AM was after midnight.

• 19:04Chuck Nice?

  But then I thought, and what would PM be? Pre-midnight? Well, this makes no sense. Antemeridian.

• 19:14Neil deGrasse Tyson?

  Antemeridian and post- meridian. Okay.

• 19:17Chuck Nice?

  Cool.

• 19:17Neil deGrasse Tyson?

  Two whole concepts that rely on your meridian.

• 19:20Chuck Nice?

  Right.

• 19:21Neil deGrasse Tyson?

  We'll start there. Okay. Let's keep going. You ready?

• 19:23Chuck Nice?

  Okay, let's keep going.

• 19:24Neil deGrasse Tyson?

  Okay. Um...

• 19:27Neil deGrasse Tyson?

  Earth's equator. If you extended it out to the sky.

• 19:33Chuck Nice?

  Okay.

• 19:33Neil deGrasse Tyson?

  There's a line on the sky that corresponds to Earth's equator.

• 19:37Chuck Nice?

  Okay.

• 19:37Neil deGrasse Tyson?

  That's called the celestial equator.

• 19:39Chuck Nice?

  Alright.

• 19:40Neil deGrasse Tyson?

  Okay?

• 19:40Chuck Nice?

  That's cool.

• 19:41Neil deGrasse Tyson?

  We together?

• 19:42Chuck Nice?

  I'm with you.

• 19:42Neil deGrasse Tyson?

  You're with me?

• 19:43Chuck Nice?

  Yeah.

• 19:43Neil deGrasse Tyson?

  We, we good?

• 19:44Chuck Nice?

  I'm good.

• 19:45Neil deGrasse Tyson?

  Okay. Alright. Now. There is a line. That. Crosses. There's another line, circle on the sky. The Earth's equator is a full circle on the sky.

• 19:57Chuck Nice?

  Right.

• 19:58Neil deGrasse Tyson?

  Cause the equator goes around the Earth.

• 19:59Chuck Nice?

  Goes around the Earth.

• 20:00Neil deGrasse Tyson?

  Everybody on the equator looks up. There, it's right there.

• 20:03Chuck Nice?

  Okay.

• 20:03Neil deGrasse Tyson?

  Okay, overhead. Everybody else sits at an angle.

• 20:05Chuck Nice?

  Mm-hmm.

• 20:06Neil deGrasse Tyson?

  Okay. So.

• 20:09Neil deGrasse Tyson?

  There's another line. That crosses the celestial equator. So think of it as two rings at an angle.

• 20:15Chuck Nice?

  Right.

• 20:16Neil deGrasse Tyson?

  To each other.

• 20:18Neil deGrasse Tyson?

  Okay? This ring crosses the celestial equator. At an angle of twenty-three and a half degrees.

• 20:25Chuck Nice?

  Okay. Alright. That makes sense.

• 20:28Neil deGrasse Tyson?

  Okay.

• 20:29Chuck Nice?

  Okay.

• 20:30Neil deGrasse Tyson?

  Twenty-three and a half degrees.

• 20:31Chuck Nice?

  Twenty-three and a half degrees.

• 20:31Neil deGrasse Tyson?

  That line.

• 20:33Chuck Nice?

  Mm-hmm.

• 20:34Neil deGrasse Tyson?

  Is the path. Throughout the year that the sun takes. Against the background stars. Of course, the sun is not taking a path.

• 20:44Chuck Nice?

  Right.

• 20:45Neil deGrasse Tyson?

  We're going around it. It.

• 20:46Chuck Nice?

  Right.

• 20:47Neil deGrasse Tyson?

  But let's, let's be pre-Copernican here.

• 20:49Chuck Nice?

  Right.

• 20:50Neil deGrasse Tyson?

  Just to make the. Discussion simple.

• 20:52Chuck Nice?

  Okay.

• 20:52Neil deGrasse Tyson?

  So, day by day. The sun moves a little bit along that line.

• 20:57Chuck Nice?

  That line.

• 20:58Neil deGrasse Tyson?

  Right. Okay.

• 20:59Chuck Nice?

  That makes sense.

• 21:00Neil deGrasse Tyson?

  Okay.

• 21:00Chuck Nice?

  Yeah.

• 21:01Neil deGrasse Tyson?

  Got that?

• 21:01Chuck Nice?

  Yeah.

• 21:02Neil deGrasse Tyson?

  Okay.

• 21:05Neil deGrasse Tyson?

  The moon. Has his own line.

• 21:08Chuck Nice?

  Okay, but this is way too many lines. We're getting a little crazy with the lines.

• 21:14Neil deGrasse Tyson?

  Okay.

• 21:14Chuck Nice?

  Okay. So now, first we got the celestial equator.

• 21:17Neil deGrasse Tyson?

  Yes, the celestial equator.

• 21:18Chuck Nice?

  Now we got the meridian, which is your own personal line. And then we have the line that, uh, is at twenty-three degrees.

• 21:27Neil deGrasse Tyson?

  Angled.

• 21:28Chuck Nice?

  Angled.

• 21:29Neil deGrasse Tyson?

  Okay.

• 21:29Chuck Nice?

  Right.

• 21:30Neil deGrasse Tyson?

  And that's the path the sun takes.

• 21:31Chuck Nice?

  That's the path the sun takes.

• 21:31Neil deGrasse Tyson?

  Okay.

• 21:32Chuck Nice?

  Alright.

• 21:32Neil deGrasse Tyson?

  Okay.

• 21:33Chuck Nice?

  Still good.

• 21:33Neil deGrasse Tyson?

  Now, now, now. Why is it twenty-three and a half degrees?

• 21:37Chuck Nice?

  Because we're tilted that way.

• 21:38Neil deGrasse Tyson?

  That is the tilt of Earth.

• 21:40Chuck Nice?

  Okay.

• 21:41Neil deGrasse Tyson?

  Okay?

• 21:41Chuck Nice?

  Alright.

• 21:42Neil deGrasse Tyson?

  Earth is tilted that.

• 21:43Chuck Nice?

  Yes.

• 21:44Neil deGrasse Tyson?

  And because we're tilted.

• 21:45Chuck Nice?

  Right.

• 21:46Neil deGrasse Tyson?

  The sun doesn't line up with our equator. If we were not tilted. That path of the sun would be right on Earth's equator. It would've been interesting and different, okay? Exactly, right. But now we're tilted, it means we have seasons. Because it gives us seasons. All right, so now watch. The moon, in its path around the earth, has its own Line. Its own line, okay? Okay? That's angled five degrees to our equator. Okay. So, right. Okay. Okay. So.

• 22:21Neil deGrasse Tyson?

  Okay, all right, I got you. If the moon is crossing the path of the sun, at the same time the sun is in that spot, you get what? An eclipse. An eclipse. Right. So this path the sun takes around the earth is called the ecliptic. Because that's where you would get an eclipse. Nice. Okay. The ecl- the ecliptic. Yes. All right. Yes, that's the sun's path around the earth, okay? Anytime the moon intersects it, if they're together, eclipse. All right. We call it the ecliptic. Okay. All right. Now, if you want a way to think about it, a loose way to think about it, how far does the sun go every day along that ecliptic?

• 23:07Neil deGrasse Tyson?

  All right, how many days are in a year? Three sixty-five. How many degrees in a circle? Three sixty. Ah! Look at that. The sun goes approximately a degree a day. Right. Is that cool? That is very cool. That's very cool. A degree a day. So in a month, it goes, uh, a month, so a month is thirty degrees. Thirty degrees. So, a degree a day goes thirty degrees across the sky. Okay. Just add all that up, okay? So, more lines. I ain't done with you. Wow. There's more, damn, it's got more lines than the damn subway.

• 23:42Neil deGrasse Tyson?

  Okay, you ready? Go ahead. Earth's longitude and latitude. All right. You can project that onto the sky and have a grid system on the sky. Right. We have that. And our longitudes become what we call right ascension.

• 23:59Neil deGrasse Tyson?

  And the latitudes become what we call declination.

• 24:02Chuck Nice?

  Okay.

• 24:03Neil deGrasse Tyson?

  Okay. And right ascension is measured in hours. And the declination is measured in degrees. So every object in the sky has a coordinate in right ascension and declination.

• 24:15Chuck Nice?

  Which corresponds from the grid that we project onto the sky.

• 24:19Neil deGrasse Tyson?

  The style of that grid we project onto the sky.

• 24:21Chuck Nice?

  I got you.

• 24:22Neil deGrasse Tyson?

  Okay. But that's the closest that, other than that, there's not, okay.

• 24:26Chuck Nice?

  There's nothing.

• 24:26Neil deGrasse Tyson?

  There's nothing.

• 24:27Chuck Nice?

  I got you. Good.

• 24:27Neil deGrasse Tyson?

  All right.

• 24:28Chuck Nice?

  No, I understand.

• 24:28Neil deGrasse Tyson?

  You're not gonna say, "Well, here I am on Earth. Where's my spot on the sky?" That's not gonna happen. Okay? But just to, if you wanna think about the, the, the orange wedges of longitude on Earth and the horizontal slices across, we've done that with the sky.

• 24:42Chuck Nice?

  And then whatever's up there, that's what that is.

• 24:44Neil deGrasse Tyson?

  Correct.

• 24:44Chuck Nice?

  Right.

• 24:45Neil deGrasse Tyson?

  Okay.

• 24:46Chuck Nice?

  Okay.

• 24:46Neil deGrasse Tyson?

  So, so if you look at a star map, you'll see this grid.

• 24:50Chuck Nice?

  Right.

• 24:51Neil deGrasse Tyson?

  That's how we know where anything is. That's how we tell a telescope to find something on the sky.

• 24:55Chuck Nice?

  I was gonna say, that's when you look up and you find any celestial body in a telescope.

• 24:59Neil deGrasse Tyson?

  In a telescope, it's got coordinates.

• 25:01Chuck Nice?

  They say the ascension, right ascension.

• 25:03Neil deGrasse Tyson?

  And declination.

• 25:04Chuck Nice?

  And that gives you the plot point.

• 25:05Neil deGrasse Tyson?

  It's degrees, minutes, seconds, and there's hours, minutes, seconds, just kinda the way we have here on Earth. Okay?

• 25:11Chuck Nice?

  Cool.

• 25:12Neil deGrasse Tyson?

  All right. Except we have hours for our right ascension. Here, our longitude is still in degrees, but we could've measured it in hours, because there's 24 hours around. We just didn't.

• 25:22Chuck Nice?

  Okay.

• 25:22Neil deGrasse Tyson?

  Okay. All right. So now. The north and south pole have spots on the sky.

• 25:30Chuck Nice?

  Okay.

• 25:31Neil deGrasse Tyson?

  North and south pole of the Earth, project them out to the sky, you get the north celestial pole.

• 25:36Chuck Nice?

  Mm-hmm.

• 25:36Neil deGrasse Tyson?

  The south celestial pole.

• 25:37Chuck Nice?

  Okay.

• 25:38Neil deGrasse Tyson?

  Got that?

• 25:38Chuck Nice?

  Right.

• 25:39Neil deGrasse Tyson?

  Our south celestial pole is near Polaris.

• 25:46Chuck Nice?

  All right.

• 25:46Neil deGrasse Tyson?

  The north star.

• 25:47Chuck Nice?

  Okay.

• 25:48Neil deGrasse Tyson?

  It's not actually pointing to Polaris. It's like two full moons widths away from it.

• 25:53Chuck Nice?

  Okay.

• 25:53Neil deGrasse Tyson?

  Okay? Something like that. It's not, it's not pointing. So it's just kinda near it. And people say, "Oh, we have a pole star. There's something divine about that for our navigation and, and..." No. It's just sort of near it.

• 26:07Chuck Nice?

  Sort of near.

• 26:08Neil deGrasse Tyson?

  Okay? All right.

• 26:11Neil deGrasse Tyson?

  Earth tilted and spinning on its axis, tugged on by the moon, actually wobbles. Uh oh. Okay, it wobbles. What happens to all these lines? I'm about to tell you! Oh my god. Watch, here you go, you ready? Okay, so, the north celestial pole precesses in a circle on the sky. Right. Once every 26,000 years. Oh my god. So, the north pole traces a circle on the sky, once every 26,000 years. Wow. Alright, which means the north star, Polaris, only happens to be our north star now.

• 26:56Neil deGrasse Tyson?

  Right. Okay, in the days of the Egyptians, 5,000 years ago, it was not pointing to the north star. Right. I think, I gotta check my notes, it was pointing to a Thubin, there's some other star, which was the pole star for the Egyptians. For those guys, right. Okay, different pole star. Wow. Alright. Wow. Uh, and I think we'll get a li- Take that, Zodiac. I think we'll, we'll get a little closer to the north star before we go away from it again. Okay. Alright, there's a 26,000 year cycle, okay? Alright, and it drags our grid with it. Okay. Because our, the grid on the sky emanates, it, it's, matches the grid on the earth.

• 27:41Neil deGrasse Tyson?

  But how about the stars? What coordinate are they if we're dragging the co- So, this freaks people out if they hear it for the very first time. Every coordinate we have for objects in the sky Mm-hmm. Have a date.

• 27:58Neil deGrasse Tyson?

  If, that is the coordinate they had at that date. Oh wow.

• 28:02Neil deGrasse Tyson?

  And so we all agree, we, is it, we, are we referencing the year 2000?

• 28:07Chuck Nice?

  Right.

• 28:08Neil deGrasse Tyson?

  January 1st at midnight, okay? Boom. That's, you give the coordinate and you give a date. Then you hand that to your computer, hand it to your telescope, which is talking to a computer. And the computer says, let us process the coordinates of your object from that date that you gave it to tonight. So it'll process the coordinates.

• 28:33Chuck Nice?

  Wow.

• 28:34Neil deGrasse Tyson?

  From the year 2000 to the moment you were observing that object. So the grid system is not constant.

• 28:42Chuck Nice?

  Right.

• 28:43Neil deGrasse Tyson?

  It's crazy.

• 28:44Chuck Nice?

  That's insane.

• 28:45Neil deGrasse Tyson?

  Yeah, and before we had computers doing this.

• 28:47Chuck Nice?

  Somebody had to do it by hand?

• 28:49Neil deGrasse Tyson?

  Yes.

• 28:49Chuck Nice?

  Oh my God!

• 28:51Neil deGrasse Tyson?

  We had to process the coordinates by hand using something called spherical trigonometry.

• 28:58Chuck Nice?

  Wow.

• 28:59Neil deGrasse Tyson?

  Yes. Spherical trig. And it used to be an entire graduate course in astrophysics. And I got into graduate school just when the computers started taking this over.

• 29:10Chuck Nice?

  Right.

• 29:10Neil deGrasse Tyson?

  And I did not have to, and the name of the guy who wrote the book on spherical trigonometry, his name is Smart.

• 29:16Chuck Nice?

  Well, guess what? You're dumb now.

• 29:21Chuck Nice?

  Woo, all them royalties dried right up. Oh, what a shame.

• 29:26Neil deGrasse Tyson?

  Yeah, because it was like, I ain't doing this, I don't have to do this.

• 29:28Chuck Nice?

  I don't have to do this.

• 29:29Neil deGrasse Tyson?

  I don't have to do this. Now, a consequence of this.

• 29:33Chuck Nice?

  Right.

• 29:33Neil deGrasse Tyson?

  Of this grid shifting is that the constellation in the sky that the sun was in

• 29:44Neil deGrasse Tyson?

  at that month of the year has also shifted.

• 29:47Chuck Nice?

  Right.

• 29:51Neil deGrasse Tyson?

  Up, up, up, up, up, up. So 2000 years ago.

• 29:56Chuck Nice?

  Exactly.

• 29:56Neil deGrasse Tyson?

  When they're laying out the constellations that the sun moves in front of, and they decided there's 12 of them. And they call them the zodiac because there's animals at zoo. The zoo is the key.

• 30:12Chuck Nice?

  Right.

• 30:12Neil deGrasse Tyson?

  The key.

• 30:13Chuck Nice?

  Zodiac.

• 30:13Neil deGrasse Tyson?

  Zodiac, okay?

• 30:16Neil deGrasse Tyson?

  They were all lined up for astrologers 2,000 years ago. Okay? So 2,000 years ago, when all these were laid out and the boundaries and the houses and everything, 2,000, what fraction of 26,000 is 2,000?

• 30:30Chuck Nice?

  Uh, two times 13, so 20, 113.

• 30:32Neil deGrasse Tyson?

  It's 113, which is not that far from 112.

• 30:35Chuck Nice?

  Right.

• 30:35Neil deGrasse Tyson?

  Okay?

• 30:35Chuck Nice?

  Okay, oh!

• 30:36Neil deGrasse Tyson?

  This is my saying! This is what I'm saying!

• 30:38Chuck Nice?

  That's where we go when I see it.

• 30:39Neil deGrasse Tyson?

  So, all these constellations are shifted by a whole constellation along the zodiac.

• 30:47Chuck Nice?

  That kind of messes up the whole premise though, doesn't it? Like of...

• 30:51Neil deGrasse Tyson?

  You telling me, you telling me that?

• 30:53Chuck Nice?

  I'm like...

• 30:54Neil deGrasse Tyson?

  Okay, so...

• 30:56Chuck Nice?

  If I'm born in a certain month...

• 30:58Neil deGrasse Tyson?

  Correct, the month was when the sun was in that constellation.

• 31:00Chuck Nice?

  When the sun was in that constellation.

• 31:01Neil deGrasse Tyson?

  It's a completely other constellation now.

• 31:03Chuck Nice?

  Oh my god!

• 31:04Neil deGrasse Tyson?

  Correct, correct, so...

• 31:06Chuck Nice?

  Wait a minute, I'm so sorry guys.

• 31:10Chuck Nice?

  This is worse than Pluto for you.

• 31:11Neil deGrasse Tyson?

  Cause it, cause it got set up 2,000 years ago.

• 31:15Chuck Nice?

  Right.

• 31:16Neil deGrasse Tyson?

  That's when it got, not in ancient Egypt, 2,000 years ago, it got set up. Everything shifted by a constellation, plus the sun has a, has another constellation it goes into, Ophiuchus. So, the sun, the 13, the sun passes through 13 constellations, not 12. So, but they, they didn't tell you this, so, in fact,

• 31:37Neil deGrasse Tyson?

  the sun spends more time in Ophiuchus than in Scorpius.

• 31:41Chuck Nice?

  Well, that's because, I mean, Ophiuchus is hard to say, so, Scorpius is easy.

• 31:46Neil deGrasse Tyson?

  Okay.

• 31:47Chuck Nice?

  You know?

• 31:47Neil deGrasse Tyson?

  So, so, if you thought you were Scorpius, you were probably Ophiuchan. And all Scorpions and Ophiuchans are currently Librarians.

• 31:58Chuck Nice?

  Yes, and they're also really sex crazed. I'm very sex crazed, I'm an Ophiuchan Scorpio. Anyway, that's the deal with Scorpios, they're supposed to be into sex.

• 32:09Neil deGrasse Tyson?

  Oh, is that right?

• 32:10Chuck Nice?

  Yeah, that's what they say.

• 32:11Neil deGrasse Tyson?

  Okay.

• 32:11Chuck Nice?

  But clearly you're not, because you're Ophiuchan. Okay?

• 32:16Neil deGrasse Tyson?

  So, this ecliptic, which is where you find the zodiac. Right. Has shifted against the background stars. That's right. Okay, it shifted against where the sun is on the month of the year. Right. So, these are your lines in the sky. I'll tell you just a couple more lines and then we'll call it quits. Okay. The Milky Way. All right. Is this band of light. Right. Okay, I think if the Romans used the word "street" instead of "way", to refer to their thoroughfares, because the Appian Way. Right. This is, okay, it would be called the Milky Street. Right, because it looks like a road. It's a road across the sky. It was like a road of Milky Way. Right, right.

• 32:58Neil deGrasse Tyson?

  Oh, man, thank God they didn't though, because that's a lousy candy bar.

• 33:04Neil deGrasse Tyson?

  Milky Street? The Milky Street. You don't want that candy bar.

• 33:09Neil deGrasse Tyson?

  I'll have a little bite of my Milky Street.

• 33:13Neil deGrasse Tyson?

  So. Nobody wants that. So, the plane of the Milky Way. Right. Has a line associated with it, and we call that the Galactic Equator. All right. That's another line on the sky. Another line on the sky. You follow that around, the Milky Way is puffy on either side of that. Nice. All the way around the sky. Cool. Right, so, it turns out the center of the Milky Way goes directly overhead when seen from the southern hemisphere, from like 30 degrees south. My PhD thesis focused on the center of the galaxy. The bulge in the center of the Milky Way galaxy, and to see that best, all my data came from Chile, in the mountains of Chile. Oh. The Saratolo Inter-American Observatory.

• 33:52Neil deGrasse Tyson?

  I spent like half my time in graduate school on that mountain, obtaining data. Wow. Communing with the cosmos. That's super cool. Oh, yeah. I'm jealous. So, we got the meridian, we got the ecliptic. Ecliptic. We got the Moon's Equator, doesn't have a fancy word. It's just the moon's path of the moon. We've got right ascension declination lines, and we've got. The celestial equator. The celestial equator. Right. On top of, and we got the north and the south. And you have the processional circle. Wow. So, all those are lines on the sky. Well, you did it again. What? I thought this was gonna be a bunch of crap.

• 34:32Chuck Nice?

  When you start out with lines in the sky, I'm like, where can we go with this? This is terrible, but this is great.

• 34:41Neil deGrasse Tyson?

  Yeah, so and and now you know what AM and PM stand for.

• 34:44Chuck Nice?

  Yes, anti meridian and post meridian.

• 34:47Neil deGrasse Tyson?

  And by the way.

• 34:49Chuck Nice?

  And my own personal meridian.

• 34:51Neil deGrasse Tyson?

  Oh, that's what PM stands for. When I was a kid, fourth grade, we went on a walking trip to the neighborhood post office.

• 34:58Chuck Nice?

  Right.

• 34:59Neil deGrasse Tyson?

  To see the machines, you know, it was a field trip. So I noticed on the door.

• 35:07Neil deGrasse Tyson?

  It said what time it opens, okay? And it said it opened at like eight or nine AM. Okay. And then it said 12. And then it continued on to the PM and gave another set of hours and the 12 just had an M next to it.

• 35:27Neil deGrasse Tyson?

  And when I was a kid, I said, why does it just have an M?

• 35:31Chuck Nice?

  Right.

• 35:31Neil deGrasse Tyson?

  It says meridian.

• 35:32Chuck Nice?

  Meridian.

• 35:32Neil deGrasse Tyson?

  It's 12 noon, the middle of the day.

• 35:34Chuck Nice?

  Wow, that's even a new thing we all just picked up. What time will you want to meet? Why don't we meet at 12 AM?

• 35:43Chuck Nice?

  Man, what the hell are you talking about? 12 AM, my friend?

• 35:47Neil deGrasse Tyson?

  I think traditionally, the noon is given the PM.

• 35:50Chuck Nice?

  Right.

• 35:50Neil deGrasse Tyson?

  Because by the time you say noon.

• 35:53Chuck Nice?

  It's post meridian.

• 35:54Neil deGrasse Tyson?

  Post meridian, right.

• 35:55Chuck Nice?

  But still, I'm at right at 12.

• 35:58Neil deGrasse Tyson?

  Right, not not not a millisecond. Or before.

• 36:02Chuck Nice?

  Right, or before.

• 36:04Neil deGrasse Tyson?

  Yeah, so there you go.

• 36:06Chuck Nice?

  That's great.

• 36:06Neil deGrasse Tyson?

  Lines in the sky.

• 36:07Chuck Nice?

  Nice.

• 36:07Neil deGrasse Tyson?

  Okay.

• 36:21Neil deGrasse Tyson?

  Chuck, you got another one for us?

• 36:22Chuck Nice?

  Okay.

• 36:23Neil deGrasse Tyson?

  All right. So you've seen or read about or heard that when spacecraft come back to Earth.

• 36:30Chuck Nice?

  Right.

• 36:31Neil deGrasse Tyson?

  They have heat shields.

• 36:32Chuck Nice?

  Yes, of course.

• 36:33Neil deGrasse Tyson?

  And otherwise they'll burn up.

• 36:34Chuck Nice?

  Yeah.

• 36:35Neil deGrasse Tyson?

  So the the heat dissipates the energy, the kinetic energy of the craft. Until it can just deploy parachutes and and land smoothly.

• 36:45Chuck Nice?

  Gently waft down to the Earth's surface.

• 36:48Neil deGrasse Tyson?

  Unless you're Russian.

• 36:49Chuck Nice?

  Right, in which case, you know, you just crash into the Earth.

• 36:53Neil deGrasse Tyson?

  They don't land in water.

• 36:55Chuck Nice?

  That's right.

• 36:55Neil deGrasse Tyson?

  They they land on on dirt.

• 36:58Chuck Nice?

  Yes.

• 36:59Neil deGrasse Tyson?

  Okay.

• 36:59Chuck Nice?

  Because we are Russian.

• 37:02Chuck Nice?

  That is right, comrade.

• 37:05Neil deGrasse Tyson?

  So, uh, so people tend to have the attitude, attitude's not the right word. They tend to think that this re-entry is some very scary part of the trip. And we wish we didn't have to do this, but it's a necessary evil of coming back to Earth.

• 37:27Chuck Nice?

  Well, I mean, it's easy to see why you would think it's a scary part because every time they show anything coming into the Earth's atmosphere, it is on fire.

• 37:37Neil deGrasse Tyson?

  It is on fire, right, but you're thinking, oh, my gosh, it's too bad we have to go through this. No, that's the wrong attitude.

• 37:45Chuck Nice?

  Ah.

• 37:45Neil deGrasse Tyson?

  We are glad we're going through it.

• 37:48Chuck Nice?

  Okay.

• 37:49Neil deGrasse Tyson?

  You know why?

• 37:50Chuck Nice?

  Hmm.

• 37:51Neil deGrasse Tyson?

  It means I don't need fuel to slow down.

• 37:54Chuck Nice?

  Oh, there you go. That's right. Yeah, that's right. Cause when you land on the moon, you gotta.

• 38:00Neil deGrasse Tyson?

  Yeah, you need retro-rockets so that you land smoothly.

• 38:05Chuck Nice?

  Right.

• 38:05Neil deGrasse Tyson?

  There ain't no air on the moon.

• 38:06Chuck Nice?

  Exactly.

• 38:07Neil deGrasse Tyson?

  So re-entry of Earth's atmosphere is functionally aero braking.

• 38:11Chuck Nice?

  Nice.

• 38:12Neil deGrasse Tyson?

  How to take your energy of motion and deposit it somewhere else.

• 38:16Chuck Nice?

  Using the atmosphere as brakes.

• 38:18Neil deGrasse Tyson?

  As brakes. Correct.

• 38:20Chuck Nice?

  There you go.

• 38:21Neil deGrasse Tyson?

  Otherwise, the Apollo astronauts, in their case, or anybody, but especially the Apollo astronauts, would have had to have carried fuel from their original launch pad to the moon, back to Earth, so that they can slow down.

• 38:34Chuck Nice?

  Right.

• 38:35Neil deGrasse Tyson?

  Okay. By the way, if there were filling stations in orbit.

• 38:38Chuck Nice?

  Oh, okay.

• 38:39Neil deGrasse Tyson?

  That would be fun, cause then they just have to fill up.

• 38:41Chuck Nice?

  Mm-hmm. Watch the windows, sir.

• 38:45Neil deGrasse Tyson?

  Check the oil. They don't do that anymore. That's, that's old reference, man.

• 38:49Chuck Nice?

  That is.

• 38:50Neil deGrasse Tyson?

  So how old are you?

• 38:51Chuck Nice?

  Well, no, cause I'm living Jersey.

• 38:53Neil deGrasse Tyson?

  Oh, oh, in Jersey?

• 38:54Chuck Nice?

  We still have those guys.

• 38:55Neil deGrasse Tyson?

  You still have full service?

• 38:56Chuck Nice?

  We still have, no, everything is full service by law.

• 38:59Neil deGrasse Tyson?

  Wow.

• 38:59Chuck Nice?

  So when you pull up, a dude comes out and he's like, what'll it be? And I'm just like, I'm like, yeah, see, it'll be, fill her up, see?

• 39:09Speaker 02

  Fill it up, see, and get me a pack of Lucky Strikes.

• 39:13Chuck Nice?

  And check the oil while you're at it.

• 39:15Neil deGrasse Tyson?

  Yeah, that's like, I forgot.

• 39:16Chuck Nice?

  Yeah, well, I live in Jersey, so, uh, no matter where you go.

• 39:19Neil deGrasse Tyson?

  There is no self-

• 39:20Chuck Nice?

  Full, there's no self-serve.

• 39:21Neil deGrasse Tyson?

  In Jersey, okay.

• 39:22Chuck Nice?

  And they do your windows and the whole deal.

• 39:24Neil deGrasse Tyson?

  Man.

• 39:25Chuck Nice?

  Yeah.

• 39:25Neil deGrasse Tyson?

  Okay. All right. So. Now, where was it? Why are you distracting me like this?

• 39:31Chuck Nice?

  I'm sorry.

• 39:32Neil deGrasse Tyson?

  And by the way, I forgot what movie it was. Was it Mission to Mars? One of the Mars movies, where someone is on a space platform.

• 39:39Chuck Nice?

  Uh huh.

• 39:40Neil deGrasse Tyson?

  And they fall off. And they just fall towards the planet.

• 39:44Chuck Nice?

  Right.

• 39:44Neil deGrasse Tyson?

  And you see them burn up. It's like-

• 39:46Chuck Nice?

  Oh, that is dope!

• 39:48Neil deGrasse Tyson?

  No, like-

• 39:49Chuck Nice?

  It doesn't happen though?

• 39:49Neil deGrasse Tyson?

  No!

• 39:50Chuck Nice?

  Damn it!

• 39:51Neil deGrasse Tyson?

  No!

• 39:52Chuck Nice?

  Why not? I want them to burn up!

• 39:55Neil deGrasse Tyson?

  No!

• 39:56Chuck Nice?

  I mean, if, wait a minute.

• 39:57Neil deGrasse Tyson?

  It's not how it works. Let me explain.

• 39:59Chuck Nice?

  Oh, come on.

• 40:00Neil deGrasse Tyson?

  If you're in orbit around the Earth.

• 40:03Chuck Nice?

  Oh, then you're just gonna fall around the Earth.

• 40:04Neil deGrasse Tyson?

  Oh, no, hold it. You're in orbit around the Earth.

• 40:06Chuck Nice?

  Right.

• 40:08Neil deGrasse Tyson?

  And I-

• 40:09Chuck Nice?

  Push me off a platform.

• 40:10Neil deGrasse Tyson?

  Hang on. If you're in orbit around the Earth.

• 40:12Chuck Nice?

  Right.

• 40:12Neil deGrasse Tyson?

  And I say, okay, I'm done orbiting the Earth, I just wanna be on Earth.

• 40:16Chuck Nice?

  Right.

• 40:16Neil deGrasse Tyson?

  You have to get rid of your eighteen thousand miles an hour.

• 40:20Chuck Nice?

  Gotcha.

• 40:22Neil deGrasse Tyson?

  And the air braking will do that.

• 40:24Chuck Nice?

  Right.

• 40:25Neil deGrasse Tyson?

  Okay? However, if you're on a platform.

• 40:28Chuck Nice?

  Right.

• 40:28Neil deGrasse Tyson?

  Hovering above Earth.

• 40:30Chuck Nice?

  Right.

• 40:30Neil deGrasse Tyson?

  Okay, as these were.

• 40:32Chuck Nice?

  Mm-hmm.

• 40:32Neil deGrasse Tyson?

  Hovering above their, their, their destination. And you just sort of fall off.

• 40:37Chuck Nice?

  Oh, well, now you're just falling at-

• 40:39Neil deGrasse Tyson?

  You're just falling.

• 40:40Chuck Nice?

  You're just falling.

• 40:40Neil deGrasse Tyson?

  You're just, as this configuration was demonstrated, okay?

• 40:44Chuck Nice?

  You're just going down now.

• 40:45Neil deGrasse Tyson?

  You're not eating up your speed.

• 40:46Chuck Nice?

  You would never-

• 40:47Neil deGrasse Tyson?

  It's just a vertical speed.

• 40:47Chuck Nice?

  It's a vertical speed.

• 40:48Neil deGrasse Tyson?

  That you're falling down.

• 40:49Chuck Nice?

  Nine point eight, ten meters per second squared, or whatever it is.

• 40:52Neil deGrasse Tyson?

  Ooh!

• 40:53Chuck Nice?

  Is that right?

• 40:53Neil deGrasse Tyson?

  Ooh, Chucky baby. Remembering his metric.

• 40:57Chuck Nice?

  Exactly.

• 40:58Neil deGrasse Tyson?

  Acceleration of gravity at Earth's surface.

• 41:00Chuck Nice?

  Yes.

• 41:01Neil deGrasse Tyson?

  Nine point eight meters per second, per second.

• 41:03Chuck Nice?

  That's right.

• 41:03Neil deGrasse Tyson?

  Right. So just, an acceleration is- The rate and change of your speed. Right. This way have to be per second, per second. Right. Right, so after one second, you're going 9.8 meters per second. Right. After two seconds, you're going. Well, 9.8 twice. Times two. Times two, yeah. Right. That would be 19.6 meters per second. Yeah, I didn't say I was that good.

• 41:27Neil deGrasse Tyson?

  So, so, uh, the point, so here's what you could do. If you had filling stations in space. Right. Load up the fuel. Right. And you didn't want to air brake because you're afraid of the heat. You load up the fuel, aim your rockets backwards. Fire them until you have zero orbital velocity. Gotcha. At that point, you just fall. You just fall. You just fall back to earth. Right, and now you could just use a parachute. Now you just use a parachute. Yeah, because you're just falling. You're just falling. Not a big deal. Not a big deal. Right. There you go. That's kind of cool. I want that dude to burn up so bad, I don't know what to do, man. No, just to be clear, if you're falling from very, very far away, like from the moon. Right. You'll have enough speed, you gotta, you gotta work, you got, you're gonna need some, some heat shields. Right. Because then your speed is very, very high.

• 42:11Neil deGrasse Tyson?

  I mean, but just, just stopping your orbit and falling straight down. Right. All right, so this is off topic, but what are heat shields made of? Oh, good, good. Seriously. I, yeah, exactly, because, so in the old days. Right. Apollo era, where stuff was functional and blunt. Right. Okay. That's right. All right, this shit worked. That's right. NASA, the way we like it, like, like the men who made it, functional and blunt. That's right. We smoke cigarettes while we calculate re-entry equations. That's right. With a slide rule. That's right. We're NASA, of course we use slide rules to calculate what we're doing. We're NASA. They weren't all smoking. Yes, they were. No, they were not. All right, so, so the early heat shields of the Apollo capsules. Right.

• 42:56Neil deGrasse Tyson?

  And others, but were ablative. So they were layers like an onion. Nice. Of material that would burn. Okay, so you're burning off layers. Good, right, exactly. Brilliant. And layers are very insulative, so the outer layer, when it burns. Right. That, it burns completely and then the next layer. The next layer burns. Kicks in. Right. Okay, you don't want to burn the whole thing all at once. That's, that's not gonna work, okay? So, so it was an ablative heat shield. That's. And what, what it meant was, if you just come out of orbit, you're going five miles per second, eighteen thousand miles an hour. Right. To go to zero, but if you're coming from the moon. You're re-entering at seven miles per second. Wow.

• 43:37Neil deGrasse Tyson?

  Okay, that has twice the energy as five miles per second does. Right. You know how you know that? No. Take five and square it, what do you get? Uh, five, five, twenty-five. Take seven and square it, what do you get? Forty-nine. Thank you, okay, so forty-nine is twice twenty-five, basically. Basically. So, energy goes as the velocity squared. Nice. So. So go ahead. So the energy, which is what has to be dissipated by these panels, by these, these layers, goes as the velocity squared. Gotcha. So, orbital speed is five miles per second, re-entry from, from the moon. That's seven miles. It's a seven miles per second. Wow. All right, you know why seven miles per second? No. Because you had to get to that speed to reach the moon in the first place. Oh, okay. But.

• 44:22Neil deGrasse Tyson?

  But wait a minute. That's called the Earth's escape velocity. Right. So if you fall towards Earth from very, very far away, by the time you hit Earth, you are going at escape velocity. Escape velocity. Because that's the velocity you needed to have gotten to where you were in the first place. So. It's symmetric that way, it's very beautiful. That is very cool. In the equations. Now, wait a, okay, well, I was gonna ask, is, is there a limit to that velocity as you, is there a terminal velocity? Yes, seven miles per. That, that's it. If you fall from the edge of the universe to Earth. Right. You'll hit Earth at seven miles per second. So that's it. That's it. Woo. If, if the, if it's Earth gravity that's pulling you. Right, that's the gravity. Because far away is very weak. Right, exactly. You're not sailing right now. No big deal. Yeah, so no matter where you fall. Right. So, in other words, yes, if you fall from the edge of the universe, you're gonna hit exactly Earth's escape velocity.

• 45:06Neil deGrasse Tyson?

  If you fall from the moon, as far as the equations go, that is tantamount to the edge of the universe. Right, might as well be. Most of the energy that you're gonna acquire from falling to Earth happens in the last bits. Right. Not in most of the early stages. Okay, I got you. So, so that's why it's, it's, it's loose, but it's accurate enough for the, for the example. All right, now, see, now I'm just thinking, so let's change. So the astronauts probably went six point eight. Okay. Meters per. So if they were falling to, would you, go ahead. So the astronauts probably went six point eight miles per second. Okay. To get to the moon. Oh, that's close enough. But it's close enough to seven, right, it's close enough to seven. So, the point is, this velocity squared. Right. What's the first equation you ever learned in school?

• 45:48Neil deGrasse Tyson?

  Actually, the first, oh, okay, obviously, that's not an equation, I don't know, that's, uh. Equals mc squared. That's true. Of course you did. That's true. What is the c in that equation? It's a constant of the speed of light. It's the speed, and what are we doing with the speed?

• 46:03Neil deGrasse Tyson?

  E equals mc.

• 46:05Chuck Nice?

  Square.

• 46:05Neil deGrasse Tyson?

  We're squaring it.

• 46:06Chuck Nice?

  Right.

• 46:07Neil deGrasse Tyson?

  And what's on the other side of the equation?

• 46:09Chuck Nice?

  Energy.

• 46:09Neil deGrasse Tyson?

  E. So the energy goes as the velocity squared.

• 46:12Chuck Nice?

  Look at that.

• 46:13Neil deGrasse Tyson?

  And that's just. You've known that from birth.

• 46:15Chuck Nice?

  Didn't even know it.

• 46:16Neil deGrasse Tyson?

  You didn't even know.

• 46:16Chuck Nice?

  Didn't even know, I didn't even know I knew that.

• 46:18Neil deGrasse Tyson?

  That's right.

• 46:19Chuck Nice?

  Look at that.

• 46:19Neil deGrasse Tyson?

  There you go.

• 46:20Chuck Nice?

  That's awesome.

• 46:21Neil deGrasse Tyson?

  Okay, so, so, and so basically all of the energy equation.

• 46:25Chuck Nice?

  By the way, you made a very big assumption about me learning that as my first equation. I went to Philadelphia Public Schools.

• 46:31Neil deGrasse Tyson?

  Okay. Okay, so you learned it when you were 21. Okay, fine, it's still your first equation.

• 46:37Chuck Nice?

  Exactly, okay, go ahead.

• 46:38Neil deGrasse Tyson?

  So, so that's, so that's why the energy is higher. You have to dissipate twice as much energy, so the shields on the Apollo capsules that came back from the moon.

• 46:46Chuck Nice?

  Right.

• 46:46Neil deGrasse Tyson?

  Were at least twice as thick.

• 46:48Chuck Nice?

  Gotcha.

• 46:49Neil deGrasse Tyson?

  And you just ablaze.

• 46:49Chuck Nice?

  You're peeling them off.

• 46:51Neil deGrasse Tyson?

  You're peeling them off.

• 46:51Chuck Nice?

  Just peeling them off.

• 46:52Neil deGrasse Tyson?

  It was very easy, from an engineering point.

• 46:55Chuck Nice?

  Right.

• 46:55Neil deGrasse Tyson?

  To increase the heat resistance of the capsule.

• 46:59Chuck Nice?

  Yeah, you're just putting on more layers.

• 47:00Neil deGrasse Tyson?

  Just putting on more layers.

• 47:01Chuck Nice?

  Yeah, you don't even have to change the material or anything, just put on more layers.

• 47:03Neil deGrasse Tyson?

  Okay, so, the other method that NASA used was, that was invoked for the shuttle tiles.

• 47:09Chuck Nice?

  Yeah, we saw that.

• 47:10Neil deGrasse Tyson?

  We, we saw the shuttle, the shuttle, right.

• 47:11Chuck Nice?

  We went to Los Angeles, we saw the, the, the California Science Center.

• 47:16Neil deGrasse Tyson?

  Yeah, the Endeavour.

• 47:16Chuck Nice?

  The Endeavour, that's what it was, the Endeavour.

• 47:18Neil deGrasse Tyson?

  It's in captivity in the California Science Center. So, those are, it's not ablative, because they want to reuse materials.

• 47:25Chuck Nice?

  Right.

• 47:26Neil deGrasse Tyson?

  So this material, you could take a blowtorch to it.

• 47:28Chuck Nice?

  Right.

• 47:28Neil deGrasse Tyson?

  It's red hot.

• 47:29Chuck Nice?

  Right.

• 47:30Neil deGrasse Tyson?

  Put the torch down, return to it, and it's room temperature.

• 47:33Chuck Nice?

  That's really cool.

• 47:34Neil deGrasse Tyson?

  Yeah, so it dissipates heat rapidly.

• 47:37Chuck Nice?

  Right.

• 47:37Neil deGrasse Tyson?

  Rapidly. As it gets hot, it's radiating away while it gets hot, like in real time, so it's a beautiful thing.

• 47:44Chuck Nice?

  That's very cool.

• 47:44Neil deGrasse Tyson?

  So, so now you're in orbit, you want to get out of orbit.

• 47:46Chuck Nice?

  Okay.

• 47:47Neil deGrasse Tyson?

  Okay? You need some kind of thing to slow you down a little bit.

• 47:53Chuck Nice?

  Right.

• 47:53Neil deGrasse Tyson?

  So that the atmosphere can kick in.

• 47:56Chuck Nice?

  Okay.

• 47:56Neil deGrasse Tyson?

  So you slow me down a little bit, I drop to a lower orbit.

• 47:59Chuck Nice?

  Right.

• 48:00Neil deGrasse Tyson?

  Where there's a few more air molecules.

• 48:02Chuck Nice?

  Right.

• 48:03Neil deGrasse Tyson?

  Now the air molecules are hitting me.

• 48:04Chuck Nice?

  They're hitting me.

• 48:05Neil deGrasse Tyson?

  Okay?

• 48:05Chuck Nice?

  Right.

• 48:06Neil deGrasse Tyson?

  I don't have to use my engines anymore, because you're hitting air.

• 48:09Chuck Nice?

  That's slowing me down.

• 48:10Neil deGrasse Tyson?

  Slowing me down a little more, where the air is even denser.

• 48:13Chuck Nice?

  Right.

• 48:14Neil deGrasse Tyson?

  Slows you down even more.

• 48:15Chuck Nice?

  A little more.

• 48:16Neil deGrasse Tyson?

  Even denser, slows you down more. This is a runaway process.

• 48:19Chuck Nice?

  Got you. De-orbiting.

• 48:21Neil deGrasse Tyson?

  De-orbiting is, is as, as, as textbook as it comes.

• 48:25Chuck Nice?

  Unless you're Chinese.

• 48:28Chuck Nice?

  In which case they say, have whatever happens.

• 48:31Neil deGrasse Tyson?

  Oh, some of their boosters were not.

• 48:35Chuck Nice?

  I love how you're trying to defend them because they're your people.

• 48:38Neil deGrasse Tyson?

  No, no, my space people.

• 48:41Chuck Nice?

  They're space people.

• 48:42Neil deGrasse Tyson?

  Let's be clear. Let's be clear.

• 48:44Chuck Nice?

  Okay, let's be clear.

• 48:44Neil deGrasse Tyson?

  Anything that de-orbits will come down rapidly because of this phenomenon.

• 48:49Chuck Nice?

  Of course.

• 48:50Neil deGrasse Tyson?

  You'd lose a little bit of, okay, and there's more air molecules.

• 48:53Chuck Nice?

  Right.

• 48:53Neil deGrasse Tyson?

  And you go to a place where there's even more air molecules.

• 48:55Chuck Nice?

  Right.

• 48:56Neil deGrasse Tyson?

  So the arc out of orbit is actually pretty steep.

• 48:59Chuck Nice?

  Right.

• 48:59Neil deGrasse Tyson?

  Okay. You'll wanna do this where it's not gonna hurt anybody.

• 49:04Chuck Nice?

  Right.

• 49:05Neil deGrasse Tyson?

  Earth happens to have nearly a third of all of its longitude spanned by the Pacific Ocean.

• 49:12Chuck Nice?

  Nice.

• 49:13Neil deGrasse Tyson?

  There's Hawaii in there and the Galapagos.

• 49:16Chuck Nice?

  Oh, you know.

• 49:16Neil deGrasse Tyson?

  Couple of islands, but.

• 49:18Chuck Nice?

  Nothing we really need.

• 49:19Neil deGrasse Tyson?

  No, no, stop.

• 49:21Chuck Nice?

  Yeah, no.

• 49:22Neil deGrasse Tyson?

  So, but the total area of non-populated ocean is huge.

• 49:27Chuck Nice?

  That's great.

• 49:28Neil deGrasse Tyson?

  So you start your de-orbit at a place where you then plonk the thing down in the, in the Pacific.

• 49:35Chuck Nice?

  NASA's toilet.

• 49:36Neil deGrasse Tyson?

  The Pacific is the great toilet bowl of space, yes. So what happened with the Chinese boosters was they did not have a means to control their de-orbit.

• 49:46Chuck Nice?

  Right.

• 49:47Neil deGrasse Tyson?

  And they were just sort of ambling, wherever they happened to pick up enough molecules to drop them, that's where it is.

• 49:53Chuck Nice?

  Right.

• 49:54Neil deGrasse Tyson?

  And.

• 49:56Chuck Nice?

  And we got lucky.

• 49:57Neil deGrasse Tyson?

  Yeah, so, so they could not control, so you wanna have a little bit of fuel.

• 50:02Chuck Nice?

  Just a little.

• 50:03Neil deGrasse Tyson?

  To tell it when to start that de-orbit and then drop it in the Pacific. And if you don't, it's actually irresponsible.

• 50:09Chuck Nice?

  Yes, yes.

• 50:10Neil deGrasse Tyson?

  Okay, and that happened with several Chinese, um, boosters and, and rocket parts.

• 50:16Chuck Nice?

  Right.

• 50:17Neil deGrasse Tyson?

  Right.

• 50:17Chuck Nice?

  Okay.

• 50:18Neil deGrasse Tyson?

  So, so that's, that's all, that's all de-orbiting is.

• 50:22Chuck Nice?

  That's really cool.

• 50:23Neil deGrasse Tyson?

  It's why you need fuel to land on the moon, but you don't need fuel to land back on Earth.

• 50:28Chuck Nice?

  Nice, because Earth's atmosphere is your braking system.

• 50:32Neil deGrasse Tyson?

  Aero braking.

• 50:33Chuck Nice?

  Aero braking.

• 50:34Neil deGrasse Tyson?

  Treated as this is a beautiful thing, rather than, oh my gosh, will they survive? I don't know, it's dangerous.

• 50:40Chuck Nice?

  We didn't burn up in the atmosphere, we, we just had a unfortunate braking mishap.

• 50:47Neil deGrasse Tyson?

  No, so you know what engineers say about rocket accidents?

• 50:50Chuck Nice?

  What?

• 50:50Neil deGrasse Tyson?

  They're, they're not mistakes, they're, they're launches that are rich in data.

• 50:57Neil deGrasse Tyson?

  That is rough. Data learning opportunities. That is rough, man.

• 51:04Neil deGrasse Tyson?

  But you need enough sensors around so that you can actually get the data. Right. You're not just a visual spectacle. There you go. You want to have cameras and. Cameras and. Thermometers, yeah, whatever. Recordings. Recordings of everything. Yeah. Take it back to the lab, say, okay, here's what went wrong. Right. There it is. Oh, one last thing. Go ahead. One last thing. Yes. Uh, the space probe Cassini. Yeah. Which was sent to Saturn. Saturn. But 13 years orbiting Saturn, visiting moons. Taking pictures. Hanging out, taking pictures, and then we were done with it. Yeah. So what we did? Yeah. We de-orbited it. Nice. Okay, into Saturn. Okay. Okay, but it didn't have heat shields. Okay. Oh, so it burned up?

• 51:49Neil deGrasse Tyson?

  Vaporized. Look at that. Cause we didn't want it accidentally slamming, once we're done with it, we're not monitoring it. We didn't want it accidentally slamming into one of Saturn's moons that later on, we want to see if there's life, life there. Right. And before, before we know, somebody sneezed on, on the spacecraft. Right. And it goes to. And we killed all the life on the Saturn, on a Saturn moon. With our sneeze virus. With our sneeze virus.

• 52:18Neil deGrasse Tyson?

  So that's a case where it was de-orbited, but with no hope of survival. Gotcha. Now, when it's time to take this, the space station out of orbit. Okay. That's a big mama jama. That's huge. That, do you realize the space station has the area, it's the extent of a football field? I did not know that. When you include the solar panels and all the modules. All of it together. All of it together. All of it together. Wow, a football field in space. Yeah, there'll be, it's, there'll be a day when we're done. Right. We are, are the international partners. Bring that whole thing down at once, or do they? It's not designed to be brought back in one piece. Oh, snap. In one shape. Okay, so if you're going to de-orbit any of it or all of it, you're going to plunk it into the Pacific. Right.

• 53:00Neil deGrasse Tyson?

  As you, as you, we did everything else. And keep it, it's been up there for 25 years, something like that. Look at that. Yeah, I know. So, uh, we're proud of it, but there comes a time when we have better technology, better computing, better materials. Right. Better everything. Right. And you, and we'll do it. All right, that's all we got time for. All right, Neil deGrasse Tyson here for StarTalk. And by the way, we are recording in my office. A cosmic crib.

• 53:29Neil deGrasse Tyson?

  I don't think the authorities would sanction that. Gotta go for it. In my office at the Hayden Planetarium of the American Museum of Natural History. This space, otherwise known as... The Cosmic crib. Alright, Neil deGrasse Tyson, keep looking up.