StarTalk Radio - Things You Thought You Knew – Your Zodiac is Wrong

Episode Date: July 28, 2026

Does time always move at the same rate? Neil deGrasse Tyson and Chuck Nice break down things you thought you knew about time dilation, gravity assists, the north star, and your zodiac sign. NOTE: StarTalk+ Patrons can listen to this entire episode commercial-free. Thanks to our Patrons Dan Kelly, Richard Dickinson, Wendy Gaspard, Adam Diaz, Dylan Baun, Chuck Cosmo, Antal Turóczi, Cassie Mayberry, Chris L, Kiela Peoples, Bruce Lessey, Mark Marcello, E. S., David Sanders, Lottiedon, Paweł Opala, Troglodite89, Ezekiel Finch, Scout, David Mekertichyan, Craig Young, Nokomiska (No-Ko-Mee-Ska) 🪶, Ross Graves, Claire Richardson Pence, J Patrick Kinney, Diego Sanchez, Darren, Micah Letts, Elliot Reza, Daniel Zolberg, Nicholas Cooper, ANTHONY SHAMRAY, Justin, William Zuhlke, Wendy Armstrong, Sarah Gould, Aaron Morris, Jemma Theivendran, Jallison, Joshua Bramhall, Seth Cox, Adam, RalfAL, Ron Pirkle, Mark Filetti, Marilyn Seuss, upul premawardhana, Andy Junkins, Albert, Lesio Milton Dillard, Owen Poehner, Rune Sahruvaak, Alysha Rucker, Jason Hissong, Laureen DeMello, James, Thomas Przybylski, Jesse, Blake Wickam, Orville Johnson, Dennis Grimes, Kaos Sorenson, shrimpandwhitewine, Edouard-Jean Blineau, Philip May, Michael Burleson, Jo Guido, Sceptkl 1, Bryan Ramirez, Danijel Durovic, Gerald Ringgold, Annie, TKW73, David Barlow, Emily Johnson, Jaykay, Marc Roussel, Andrew Stamarski, and languid_spider 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. Hosted by Simplecast, an AdsWizz company. See pcm.adswizz.com for information about our collection and use of personal data for advertising.

Hello, StarTalkians. Coming up, we've got another Things You Thought You knew episode. This time, Chuck and I riff on Einsteinian time dilation, the mysterious gravity assists that space probes get, and the North Star. Spoiler alert, it's not all it's cracked up to be. Coming up on StarTalk. Welcome to StarTalk.

Your place in the universe, where science, and pop culture collide. StarTalk begins right now. I still lose sleep over this fact. Okay. I still lose sleep over it. And I want you to lose sleep, too. I don't want to be the only one staring at the ceiling at night.

I'm going to tell you, a lot of things already beat you to that. Oh, sure. I mean the asteroid strike that could happen? Exactly. Or the global warming or? All right. So here it is.

You may remember, or you may have heard, that Einstein's relativity, more specifically, you learn this in special theory of relativity, where the faster you move, the slower time ticks for you as others view it. Relative to the observer. Relative to the observer, correct. You don't know anything's happening. Right. your clock still ticks as far you still got your your heartbeat all of this okay so this is not a physiological thing is an actual property of the fabric of space and time under those conditions wow okay that is fascinating it is it's completely fascinating it's completely so i watch you fly by and the faster

you go the slower time ticks for you okay but my time stays the thing To you. To me. To you. So not only does speed do this, also the strength of a gravitational field will have the same effect on you. The stronger the gravitational field is, the slower time ticks for you. And that wasn't formulated until his general theory of relativity 10 years later. That took a lot more math and deeper insights into the universe.

So once again, it makes sense because you're dealing with the fabric of space time. It's a fabric of space time. Correct. But initially when formulated, you're thinking it's just because you're moving. Right. But it's actually way deeper than that. And that's why that one, oh, by the way, his original special theory of relativity was not called that. The title of the research paper was on the electrodynamics of moving bodies.

What? Okay. That was the title. We would later call it the special theory of relativity because it was a special case of what would later than be called the general theory of relativity. Okay. So the geosynchronous satellites are like middle orbit. it. That is far enough away from Earth's source of gravity for them to have a difference, a measurably different space time condition. Oh. So that their clocks tick faster than our

clocks on Earth's surface because they're farther away. And so remember I said the more intense, the gravitational, the slower time ticks. So they're farther away. Their time ticks faster. Their time ticks faster relative to us. Wow. But we get precise timings from geosynchronous satellites. So how does this work? We pre-correct the time signal from the GPS satellites to compensate for Einstein's general theory of relativity so that by the time the time reaches us, it's been properly corrected

and it matters to us and our spacetime continuum, not the one. that's in middle earth orbit. Oh, my goodness. So GPS couldn't work as accurately as it does. However, wait a minute. What? I'm sorry, just for me. You would have to have a standard in order to pre-correct something.

You know the rate at which its time is speeding up because you can calculate what the gravitational field is up there. There you go. There you go. Okay. And once you calculate that, then you do when you say, Oh, my gosh. We, the, the formula works. Einstein was right.

Right. All right. This is not just something on a few high theory. By the way. hypothesized that may or may not be true. It is true. I just want to be there when that phrase is uttered. Oh my God.

Einstein was right. Yeah. These aren't just cult heroes that we wish they were right. Right. These are real. This is real. Okay. The real universe we're talking about here.

Okay, so now watch. Let's keep going faster and faster. Let's go half the speed of light. Three quarters of the speed. 90% the speed of light. 99% the speed of light. Time is taking slower and slower and slower. For you, you will watch the whole future history of the universe

unfold in front of your eyes as fractions of a second go by for you. As you go 99, there's a formula for this, of course, but 99.99.99% 99.99% the speed of light. Because you're the observer of that. Of that. But for you, your time has slowed to the point where as you observe the things that are not moving at the speed of light, you see them. Speeding. Exactly.

You see them unfold. Correct. That is insane. So now watch. Oh, my God. Wait. No watch. Okay.

Wow. So I didn't even get to the part where I lose sleep. Okay. Okay. That's what happens. By the way, by the way, there are particles that decay. You've heard of like radioactivity, right? Yes.

Right. It decays and becomes another part. It releases the often deadly energy. Yes. Okay. Radioactivity. All right. Some particles.

Let's take, for example, the proton or the muon. one of these decay is in like six minutes when it's left out in the in the wild okay when it's not part of an atom when it's not in captivity i forgot which of these it doesn't matter for my example decay isn't like six minutes okay okay what happens if you take that particle and speed it up in a particle accelerator so you take a community of these particles speed them up calculate wait a minute the internal wristwatch on these clocks says they should live longer and sure enough their decay time takes longer. Wow.

That's, oh my God. Yes. Yes. Oh, wow. Yes. And that becomes, that becomes living proof of what Einstein said. Yes, because we can't go half the speed of light. Right.

You can accelerate a particle to do that. Yes. It has an internal built-in clock that decays after a certain amount of time. And there they are taking longer to decay in the exact amount that Einstein predicts. That is genius. So we don't make this stuff up, okay? Yes, it is. genius. It's like triple genius. All right. Now, let's take this to an extreme level.

Right. Let's go so fast that we're going the speed of light itself. Right. Well, we can't do that because we're made of material substance and there's no way to do that. But there are things that travel at the speed of light. And what is that? Uh, those would be photons. Yes. Thank you. Those would be, like your finger gesture. That would be, I would say, what travels at the speed of light? Light does. Yeah, I was about to say light. So, if photons had a clock, the clock would never tick.

Nice. Which means when I go to a mountaintop, as I did in graduate school, to observe the center of the Milky Way galaxy, for stars that emitted their light 30,000 years ago, traveling through the gaps of interstellar space, and they move through space, come through Earth's atmosphere, they come down into the telescope, they reflect, go back to my detector and land on my CCD chip.

That photon, when it was born at the star that emitted it, was detected at my telescope in the same instant. Wow. According to the photon itself. Live fast, die hard. The photon has no knowledge of that trip. Right. Because time did not exist for it.

Oh, that's great. And I'm saddened that many of these photons like hit people tanning on the beach, you know? And imagine travel 30,000 years and land on someone's buttocks. Very sad. With the telescopes I collected, I'm now decoding the nature of the universe. And some photons go right on by Earth and are still moving. But they have no internal time clock. Wow.

And they're just traveling through like, I hope when I'm born, I hit a telescope. Bam! You're born and you hit a telescope? Yeah. That would be interesting. what I want to be when I grow up? Right. You know, or the instant I am emitted, where am I going to be?

Where would I like to be? Right, right, right. And so just the idea that light can move across the universe and have no, and not age, this is a fascinating fact to me. Wow. Yeah. That is more than fascinating. Yeah.

I mean, that's mind boggling. Yeah, yeah. So that is light, the age of light. It's like it doesn't age at all. I am convinced that all of you guys secretly microdose and smoke weed. I'm just, I'm just, I'm, I'm, I'm, another episode. Another episode. I'm Ali Khan Hemorrhage, and I support StarTalk on Patreon.

This is StarTalk with Neil deGrasse Tyson. Do you like these, these explainer? Of course. I, uh, one, because Neil Splaining has always been good for me. Neil spaining has always been good for me. Okay. You know. All other splanings are not good.

Man splaining ain't good. You know what I mean? Blacksplain, white spleening ain't good. But Neil splaining, it works. That's a whole other thing. Yeah. Thank you for that. Those words of encouragement.

So I'll just continue. Cool. And what do you got? So I got today, we've all heard of gravity assists for spacecraft. Yes. That was in on Space Jam, right? It's a gravity assist. Oh, that was, oh, that's it, people.

I just retired. It's over. Because that was the worst I've ever done in my life. Jesus. So a gravity assist, the way people typically think about it is you send out a spacecraft and you wanted to give it more speed than it currently has. Right. And so you find some planet that it sort of falls towards.

And of course, it'll speed up as it does that. Right. And we think of it as kind of a slingshot. Obviously, it falls not towards it, but towards the side of it. Yes. Otherwise, it's not a gravity assist. It's a gravity crash. Exactly.

So you want it to sort of swing by and it picks up speed in so doing and it flings out the other side. And if you angle it right and position it right, you could head towards your next destination. And as a result, you can have multiple destinations in the same voyage. So famously, Voyager 1 and 2, this is back in the 1970s when it was launched, they had trajectories that, well, let me say that differently. The solar systems planets were configured in such a way that it could get multiple planetary assists, multiple gravitational assists. And by the time it was done, it had so many gravitational assists, it had enough energy to leave the solar system entirely. Wow. And you could end up doing that without using a very big rocket to begin with.

Right. So you're basically exploiting the gravitational attraction of planets for your speed, rather than spending money on fuel. So it's the poor man's way to get out of the solar system. It's basically cosmic drafting. Drafting. Oh, I like that. Cosmic drafting. It's just like, yeah, why should I pedal?

Let this sucker pedal for me. Think about this. As you approach a planet and its gravity attracts you, everyone has said and it believes and thinks that it pulls you in and then flings you out the other side. But wait a minute. Yeah, just like there used to be from me with women at a nightclub. Oh, is that how that worked for you?

Yeah, man. There was an attraction. Pull me in. And they'd be like, oh, no, no, no, no. there, no, you got, uh-uh, out to understand. See you, bro. Completely symmetric picture there, right? Exactly. So the problem with thinking of it that way is the same gravity that's pulling you in is also preventing you from leaving. Right. Okay, so you'll speed up as you fall in. But now as you try to escape, the gravity is saying,

no, I'm pulling you back. Right. So it turns out if you look at, at the pure gravity picture, it is exactly symmetric to the planet. Right. Okay? The planet pulls you in. You gain speed. You have maximum speed right when you're passing the planet. Now you want to exit the planet.

The planet starts pulling you back. Right. Every time I try to get out. Your speed falling in and your speed going back is an exact mirror image of your motion. Okay. So then the question is, how do I end up getting all this damn scheme? Where are this slingshot effect? Okay. This is something that's hardly ever explained. And that's why we have these explainer videos. Cool. So here's the answer. It turns out, if you approach a planet from behind. Okay. Okay. There it is orbiting the sun. Right. And you approach.

it from behind in its orbit. Right. Not only will the gravity pull you in, but you will gain speed just to catch up with the planet in its orbit. That makes sense. Yes. Right. How are we going to catch up?

How are you going to hit the planet, come near the planet, unless you have the planet's orbital speed? Right. The planet's orbital speed has nothing to do with the planet. With the planet's gravity. Correct. Okay. So even though the gravity is symmetric, all the speed and energy you gain falling in, the planet takes back away from you, that's symmetric. Right.

But the speeds you get from catching up with the planet in the orbit is not symmetric. Right. Look at that. Okay. And so what actually happened is you were tugging on the planet, okay? as the planet was moving and you were speeding up because of this. But what it means is you stole some of the planet's orbital energy to do this. Wow. You don't tell you about that. No, they don't.

So you basically, you approach the planet from behind. And you just like, don't make a ghetto mugging out of this. Yo. Yo, give me some of that speed. Don't turn around. Don't look at my face. Don't look at my face. Just give me this.

That's me. Nobody needs to get hurt here. And then you take it and you keep going and you got the thing and it doesn't. And it doesn't have it and you have it. So these are, this is the art of the of the slingshot. Dude, that is, that's pretty amazing. That makes sense. You can slingshot off of anything.

We've had planets orbit, the sun, launched from Earth and then slingshot around Earth twice. Right. Wow. Okay. Now, it takes longer, right? That's if you're not in a hurry, you do this. And use Earth to slingshot.

You could slingshot off the moon. You can slingshot off of Mars. Okay? It doesn't matter what planet you want to slingshot from. Right. In the case of Voyager, Voyager 1, I think it was it's slungshot. What's past tense of two slingshot? It's slung-shotted.

Slang shot. Slang shot. It was slang shot. It's slang shit off of Jupiter. Right. And so people think, oh, Jupiter has big gravity. You'll get a huge speed. It's only getting Jupiter's orbital speed.

It doesn't make that clear. Look at that. And Jupiter's traveling slower than planets that orbit closer in. So the gravitational pull cancels out, but the orbital speed is what's left over and that's what you ended up stealing in order to get the speed to go. And if you want an inverse mugging, which no one will actually want to do in space, right? If you, you can fall towards the planet, right, opposite the direction it's traveling.

Oh, wow. Okay. And if you do that, then you have sped up the planet. it eats some of your or your trajectory's energy, and you'll come out the other side moving slower than you did before. Oh, so you could actually use it as a break. As a break, that's correct.

Oh, wow. Okay, that's fascinating stuff. If you need it to break in space, that's a way, and it takes a long time to line up and make it all happen. So there you have it. Wow, look at that cosmic drafting and space breaking. That's amazing. And so the more times you do this, the more energy you have, the more speed you accumulate,

and that's how we leave the solar system. Cool. Yeah. And you might ask, but you didn't. If you drag, if you, if you slingshot off of Mars like 20 times, like, what happens to the Mars orbit itself if you're taking away its energy? Right. You haven't asked that. No.

I don't. Because you don't care. I was going to say. you know, I'm not worried about Mars. Okay. I think Mars is going to be okay. But anyway, what does happen? Let's say over, over, over, over, over.

I mean, you're basically siphying off a tiny little bit of energy. Siphoning off a tiny little bit of energy. So, okay. So here's the thing. You know, maybe in a trillion years, if you did this every day, it would matter. But the mass of these objects, relative to the mass of our measly, probes. That ratio is so huge that it's like a gnat flying full speed ahead into an elephant. The elephant doesn't say, but, you know, watch out.

Quit your shoving. The mass difference is so huge that it's not relevant. It's not important in what's going on in the solar system. But in addition, take Earth, for example, in any given day, we plow through 100 tons of meteors every single day. Wow. Tons. So this stuff falling and this stuff. So it's, don't worry about it. We have other things we should be worrying about, like climate change. Yes. Tell me about it.

You know, if you worry about, oh, my gosh, what, how about Mars? We're about your own damn planet. How about that? I'm all about that. Speaking of Mars, you said, worry about your own planet. Don't worry about Mars. And so I got both of them in one. I got a Mars pad from the Out of this World collection from Soul Guard, right?

And check this out. Every single suitcase that they make pulls about 229 bottles of plastic out of the environment. Really? Yes. So here we are with Mars and we worried about our own planet at the same time. Boom! Wait, wait. So you're saying I should drink more plastic bottles so you can make more of those, that luggage.

No. No. I'm saying, for the idiots that drink plastic bottles, this is part of the solution. And for the smart people who want to buy this and help, that's what they should do. Okay. So it's not only gets the bottles out, if you like the universe, if you love the universe, you got one that looks like Mars. Yep. That's right.

That's right. Very cool. 12 million plastic bottles pulled in 2021, right? See, that's what we're doing here. Wait, Chuck, do I recognize Valis Marinaris on that? Really? Don't pretend like. I'm like, because here's what I'm saying.

Do you? No, it looks like a high resolution image of Martian surface. It's not just like red, right? No. Pretending to be Mars. It is Mars. It's got very good detail on the surface. So highly recognizable if you're Mars fluent, which apparently you're not.

No. Okay. speak Martian. I'm sorry. Valis Marineris is basically the Mars Valley. And it's a huge canyon, way bigger than the Grand Canyon here on Earth. Okay. And it's a very striking

scar in the Martian surface. Clearly, Mars has had a whole lot of activity long ago, shaping and forming and reshaping its surface. And that's one other bits of evidence of it. So that adds to the authenticity of what you got in your hands there. Very cool. I'm just going to let you

talk while I sit here and play black van or white. Is that how that goes? But I need a vowel, though. I got a few of them right here. Oh, yeah, there you go. I can tell you this, that there's nothing more boring than people's luggage. Think about it. You're absolutely.

By the way, speaking of that. So now there's a piece of luggage that, like, Like, that's good. I want one. There's some exciting looks. By the way, the cool thing about this, not only is it, like, it's Mars right here, which means that when it comes down. Can't argue with Mars. When it comes down the shoot, right?

Okay. Mars down the conveyor belt. Mars is coming down the conveyor belt. You'll be able to recognize yours. And as a matter of fact, you can turn to somebody and go get your eyes to Mars. And. But don't take my luggage while you do that. Okay, very cool.

I'm playing you all. They're working on good stuff. Gotta love this comfortable. Goal guard. All right. All right, Chuck, so that's all we have. That was great. I love it.

So now you know, and I never thought to analogize, a gravity assist with a mugging. I'm glad I could be of service. Yeah, thank you, Chuck. As always. What's the brightest star in the nighttime sky? Are we talking my career here, Neil? No. Just saying, I've been waiting for us to get around to this.

How bright is your star, Chuck? Yeah, no, if it were me up in the sky, I would just be a dim spot in the Milky Way. It is funny that a fundamental word in all of Hollywood is derived from my profession, astrophysics. It is. It is the most fundamental word. It is. Are you a star, meaning are you burning thermonuclear fuel in your core? Exactly. Right. And the Walk of Fame, it's a star.

It's a star. That's all astro. Well, it's said that from everything I've ever heard, that's the North Star, that's what people say. Well, that's the North Star. You can always find your way home because it's the brightest star in the sky. Just follow the North Star. Yeah, so in my experience, nine out of ten people will say that. Right.

Yeah, okay. They'll see the first bright star. after sunset and then assert that it's the North Star. In 100% of those cases, they're looking at a planet. Well, that makes sense because a planet is right there. Planet's right in front of our noses. Planets are right here, man. But for me, the funny part is they'll make a wish on the, you know,

Star Bright, Star Bright, First Star I see tonight. Right. And then they make a wish. And, of course, the wishes don't come true because they're wishing on planets. That's why. You never knew that. I want to explain that to any kid now.

And then if you're not, if you're not wishing on the star, and because you know that they're planets, it means you know enough science not to be wishing on stars. That's pretty cool. It all balances out. And it's so funny that you say that. It just popped into my head what a culturally entrenched. a sentiment that is, wishing on a star. I mean, there's songs about it.

It transcends, you know, geography and culture. You know, you have it in pretty much all kinds of writings, wishing on a star. That's pretty wild. Yeah, and I'm honored that my field supplies this level of cultural referencing to all that we do. So, so, yeah, so the North Star is not the brightest star in the night sky. Okay. I just want to make that clear. Okay.

Now, so now here's the thing. Yeah. Because what, what is the North Star then? Like, what is the North Star and why is it? So, so let's get, why is it of any significance if it's not the brightest star? There you go. So we'll get to the brightest star in a minute. So the North Star is the star.

in the sky that's closest to where Earth's axis points on the sky. So you have a rotating Earth and it's just sort of rotating and the axis

is just sort of sitting there as Earth spins around it. That axis is pointing to a spot in space. Okay? In the sky. Gotcha. So we say,

is there a star near to that spot? Because then we'd always be pointing in that direction. Right. So the star closest to that spot is the North Star. And the North Star has a name. Did you know this?

I want to guess because the only star that I hear the name of all the time is the Dog Star. Yeah, no, that's not. Okay, well, there you go. I said there was a guess. It's not serious. It's not serious the Dog Star. Yeah, yeah. Yeah, the Dog Star is serious.

series of the dark star, not the North Star. So the name of this star is sensibly Polaris. Oh, for the pole or the axis, Polaris. Polaris. And in fact, that was the name, I think, of America's first nuclear submarine, Polaris, that could launch intercontinental ballistic missiles. We're about to drop a star on you. So American. That's so American. Okay, we're about to drop a Star on you. That produces energy to vaporize you just the way the centers of stars do. Right. It's the same thermonuclear mechanisms going on.

So anyway, so it's got a name Polaris. Now, the big dipper, okay, the lip of the big dipper, this part right here, okay, the lip. So there's a handle and then there's the cup and the lip is the front edge of that cup. Right. that points to the North Star. Okay. Okay. That's how you can always find the North Star.

Got it. Because the Big Dipper is very obvious in the northern hemisphere. Absolutely. Okay. So you, and then it points, and you go like four segments up, and then boom, there it is. Okay. So there are a couple of issues with this. First, the North Star is not exactly above the pole.

Okay. You can fit two four. full moon widths between it and the exact spot over the North Pole. Gotcha. All right? Which means if you took a camera and a long exposure photo centered on the North Star, the North Star will not be pegged in the middle. You'll see it make a circle.

Interesting. So it is not exactly above the North Star. And the reason why you're seeing it make a circle is because you have the long exposure and the earth is rotating where you're camera? Yes, exactly. And so otherwise you just take snapshots, you just get the stars where they are. But if you take a long exposure, you get the stars blurring, basically, but they blur with the rotation of the earth. Gotcha. And so you'll see that it actually would trace a circle around the actual North Pole.

Because people are saying, isn't it amazing that we have a star exactly over the North Pole? Oh, what are the odds? Well, it's not exactly. The odds would be zero. That's a bad bet. It's not exactly off the noble. Not only that, the lip of the big dipper kind of misses the North Star. If you did an exact line, it's off.

So there's a lot of fakery going on. Not bad fakery, but just people want the sky to have more meaning than it actually does. Wow. And so you say things that are sort of partly true just because you feel better about what it is you're talking about. Okay, so the North Star is kind of like directionally. It's kind of like getting directions in the hood. He's kind of over there. Yeah, man.

So what you want to do? Are you going to keep on down there? You won't keep going and going, right? You're going to come to, so it's a car right, but one of the wheels is up on the crate? Yeah, make it right there. Come to get right there. All right. You're going to keep going, right?

Just keep going and going, right? That's right. Directions on the sky from the stars are exactly like that. So now let me tell you how bright the North Star is. It's not the brightest, but let me tell you. Take a guess. I'm going to say it's a B student bright. Okay.

It's not in the top. First of all, how do you measure brightness in the night sky? I really don't even know that. But we have meters that do this. This is science. You don't have to worry about that. We got this. All right.

And even if you didn't have meters, you can say, yeah, that's brighter than that. And that's dimmer than that. Yeah, we got this. Okay. We've had this even since before there were telescopes. Okay. So it is not in the top 10. Oh, no.

No. It is not in the top 20. Oh, goodness. It is not in the top 30. Dad, North Star. What are you doing? It is not even in the top 40. Oh my God. The North Star is like the United States with respect to math and science. We say we're number one, but we're 47th. The North Star is the 49th brightest star in the night sky. Oh, my gosh. It is completely. completely uninteresting. It is easily missable. It is, does not

call attention to yourself. That's why you need the lip of the big dipper to find it. Because you actually need a pointer because it really isn't remarkable at all. It is not remarkable. Not remarkable.

Wow. Wow. It kind of reminds me to somebody I know. That's just you sound like you should have your own TV. show, reminiscences of everyone you grew up with. The stories.

So, yeah, so the North Star is just lame. I mean, it's just embarrassing. And meanwhile, people think it's the brightest star in the night sky. And that's what's weird about it to me. I just, because they've never checked. And so this is the lore overriding people's curiosity. I wonder how Venus feels about that. You know?

Venus is the most mistaken object for the North Star, because it's the brightest in the night sky, the morning sky. Venus is sitting around like, just like a man, just like a man. Here I am just as bright as I can be. Every single night I come out. Is that what Venus sounds like? Look at me and you know what they say? Oh my God, look at the North Star.

Once again, a man just taking my credit for the hard work that I do. Okay. And no, there doesn't happen to be a star in the South Pole. It's just a big empty spot. There is a star closer to the South Pole than the North Star is to the North Pole, but it's even dinner. And we don't call that the South Star? You can, but it's, it has a name. It's called Sigma Octans.

And it's very unassuming and nobody cares. I don't, you know why nobody cares? Because its name is Sigma Octans. Don't nobody want to talk about Sigma Octans? Because there's a consolation called Octans, which is an octant. which is an early version of a sextant, and there's a lot of navigational instruments among the constellations of the Southern Hemisphere.

You know why? Because when Europeans got to the Southern Hemisphere and decided to map the stars, we had already begun the Industrial Revolution. And so they weren't thinking centaurs and Greek mythology. They were thinking, oh, my gosh, I'm going to put some badass equipment here.

So there's an architect's table there's a telescope, a microscope, a sextant, and an octant. Wow. It's all there. These are all constellations of the 88 in the night sky. Wow. So one last thing about the North Star. So you can picture this.

If you are Santa Claus looking straight up, what star do you see? Looking straight up, you see a dead spot. Well, yes, because we just learned that. Right. Oh, I thought it was a trick question. No, that's not true. Santa Claus will look up and see the North Star. The North Star, right.

Okay, so how many degrees up is that? From the horizon. Yeah. From the horizon. Well, that should be nothing. He's already there. No, no. Degrees from the horizon to straight overhead for Santa Claus.

Let me see, because he's at the top of the world, so the degrees on the horizon. No, forget the, it doesn't matter. Yeah, Santa Claus is on the, quote, top of the world. Sure. But now he wants to know how high up is the North Star for him. above the horizon. So how many degrees is that? Oh, that's straight up. That's 90 degrees. 90 degrees. What is the latitude of the North Pole?

360 degrees. What is the latitude of the North Pole? It's 90 degrees. 90 degrees, thank you. Okay. I just love, no, I said that because I wanted to see, this is what I love you being the educator that you are, because I'll do that, and I'm just waiting for the reaction. Because if it were me, I'd be like, man, what the hell is wrong with you?

You dumb what you're doing? Hey, you do this. I gave you a second chance. I gave you a second chance. You're like, I said my boy knows better than this. I'm going to give me a second chance. I'm not going to say a damn thing. He's going to fix his own damn mistake.

Exactly. Right. But I love it. I love it. Go ahead. The North Star is 90 degrees up. When you're at the North Pole, which is at a latitude of 90 degrees. that is not a coincidence

okay if Santa Claus marches south the North Star will get lower and lower and lower and lower in the sky Santa Claus gets to the equator the North Star is on the horizon the latitude of the equator is zero the elevation of something on the horizon

is zero so the elevation in degrees of the North Star above your horizon is your last attitude on Earth. Oh, because it follows all the way down. It follows all the way now. It follows all the way down. That, well, that's pretty interesting. Yes, very interesting. And so this was an important navigational tool. That makes sense. For everybody. Right. Right. And, of course, the Underground Railroad, follow the North Star, because if you just walk towards a North Star, you'll eventually reach Santa Claus, but Ohio is good enough.

Who knew that the North Star was such a poser? Very much a poser. Actually, it's not its fault. It's people want it to be so special, and it just isn't. So I have more to tell you about how unspecial it is. Oh, awesome. We're a 49th. We're a 49th.

Yes, for those who missed it, the North Star is the 49th brightest star in the night sky. Right. And in the night sky, it's not saying, I am. It is not doing that. All right. So, but wait, there's more. Earth's spinning on its axis and it's at, it's North Pole points upwards, close-ish to where

the North Star is on the sky. All right. What I didn't tell you is, I don't know, no one has them anymore. Do you ever play with tops as a kid? I did. That's how old I am. Of course. You play with the top and it spins and then eventually begins to wobble.

Right. Okay. Right. Okay, we have an official term for that. It's called precession. Precession. Precession. Precession.

That's an official term. So, earth wobbles. Okay. Do we spin once in how often? How long does it take to spend once? 24 hours, I guess. Thank you. Yeah.

If you want to be precise, it's actually 23 hours and 56 minutes and four seconds. Wow. In case, that's another explainer. Well, you know, why do we think it's 24 hours when it's actually that? Okay. I will, that's a whole other, we'll save that. Okay. Okay.

All right. So, we spend once in 24 hours and we wobble. And the wobble takes 26,000 years. The wobble takes 26,000 years. Correct. So we've only really completed one wobble since Caveman. days, right? Wow.

You know, 30,000 years ago. Right. So that's slow. And it took some very careful measurements and brilliant thinkers throughout the last thousand years, 2,000 years to figure this out that this is actually happening in the actual sky. All right. So now, because we're wobbling, it means the North Pole of Earth isn't always pointing towards the North Star.

Uh-huh. And we called it Polaris. But wait a minute, if it's no longer, if later on it's not going to point to Polaris, not only is it not the North Star, should we keep calling it Polaris? Or just sort of grandfather in, well, that's what I once was back in the day. Exactly. So if you look at that circle, the diameter of that circle is in degrees is 23 and a half degrees. Okay.

Okay. Because that's how tipped we are from vertical. All right. Okay. That's Earth. That's what gives us our seasons, the fact that we're tipped. So we tip that and then we process around that central point. All right.

So if you draw that circle on the sky, yes, it will go through the North Star, because that's what it is now. But any other stars that it comes near? One of the stars in the night sky, I think you have. You've heard of. It's called Vega. Okay. Vega is one of the brightest stars of the night sky. It's about 30 light years away. Okay.

We think there's a planetary system forming around it. We see a disk of material that's not quite discrete planets, but it's kind of, it's work in its way towards forming planets. So we know some stuff about Vega. In 14,000 years, the wobble will. will take the North Pole axis close enough to Vega for that to be our pole star. Gotcha. And in ancient Egypt, that was long enough ago, you know, 4,000, 5,000 years ago. That's an appreciable fraction of the 26,000 years.

They had a different pole star than the North Star. Right. So in recorded history, civilizations have had different pole stars. and only right now is it what we're calling Polaris. Wow. Okay, that is. There's nothing magical or permanent about it. Wow, it's like being in Minuto.

Does anyone under 50 even know what that reference means? No, they have no idea what I'm talking about right now. But for those of you who don't know, Minuto was a boy band and they just kept swapping out members. What of which was Ricky Martin? Oh, that forgot about that. That's right. Yeah.

So Minuto was not a set of names. Right. It was a concept. It was a concept. Yes. Yes. And you just locked out the members as they, and they were age out.

They'd be like 18. They'd be like. Age out. That's what I'm like. Yeah. Sorry, Manuel. Your time is up. You gotta go, bro.

Wait, wait, wait. You are now a man. You must join the man band instead of the boy band. Can't be in a boy band anymore. Yeah. So that's pretty wild. Yeah. So the North.

star is a concept and sometimes you won't have one. When it's sort of between other two stars, we're not going to have a North Star. That's dope. I love it. That is the most interesting thing about the North Star is that the North Star, one, is not the North Star, and

two, it ain't even, it's not even going to be there. It's not going to be there in a few thousand years. And it's not even in the top 40. And it's not even the top 40. You know? That's pretty wild.

All right. That is totally wild. Now, there's one other thing. It's the con man of all stars. Don't blame. No, don't blame the star itself. You fraud. I got one more thing.

The North Stars are fraud. Go ahead. I got one more thing. Ready? All right. All right. One of the consequences of the procession. Right.

is that the sun is in a different part of the sky at the same time of the year. In other words, right now, pick a month. Okay. Right. So let's pick October. Okay. And so October, astrologically, the sun is moving through Libra. Okay.

Okay. Well, the procession of the earth, the wobble, over the 26,000 years will systematically put the sun in a different constellation in the month of October. Right. Okay. So the entire zodiac rotates through the calendar. Wow.

In fact, when the zodiac was codified two and a half thousand years ago, wait a minute, that's like one 12th, of 26,000. Oh my gosh. So is October still the month for Libra? No. The sun was in Libra 2,000 years ago in October. All of that has shifted. And so if you thought you were Libra,

you're actually Scorpio right now. And that's when the sun gets all sexy. I didn't know you were fluent in this. So the zodiac people, the astrologers, still describe the sun being in these various constellations as they were mapped out 2,200 years ago. Right. Between 2,000 and 2,400 years ago. And so if you're, it's cancers, Scorpio, Gemini, you would expect the sun to be in that constellation

the day you were born. It was 2200 years ago. Oh, man, that is so... It is not today. It's all shifted. And they don't really... They're not really forthcoming about that. No, because if they were, then all of astrology would be...

Oh, crap! That is... Oh, man. Oh, not only that, not only that, the... The zodiac, the sun in the zodiac actually passes through a 13th constellation. It's called Ophiuchus. All right. God bless you. Ophiuchus.

Ophiukus. Ophiukus. Wow. Okay. In fact, the son spends more time in Ophiukas than it does in Scorpius. Okay. So if you thought you were Scorpio, you were probably Ophiukin, and all Scorpios and Ophukans are currently Libran's. Wow. I thought I put that out there.

I just want to know where does that leave cancer? Because that's what I am. Oh, your cancer? Yeah. I'm a cancer. So cancer is one of the lamest constellations ever constructed in the night sky. Damn. There's like five stars and they have like a crab with claws and a crustacean.

It's like, what will you smoking? What opium was working in your system to say, oh, let's call that a crab? Man, you just, I can't believe this. It's like, one, I got a lousy constellation. Two, they made... Plus, those stars aren't very bright. And they're not... Okay.

I got a loud... If you ask, if you ask astrologers, they're 12 prominent constellation in the sky. No, they're not. Dead. Most of it. There's like three. They kind of look like what they're supposed to. I got a lousy, dim constellation.

They made me into a stupid bottom feeder crab. And on top of that, I'm a festering malignancy. So... Yes, which they named after crabs. Right. Yes. Oh, God. Oh, man.

Cancer. Is it too late to be a Sagittarius? Where's cancer now? I don't know. I don't keep it. I'll memorize that. I'll come back to you on another episode. Okay.

All right, we got to call it quits there. Just to round out everything you didn't need to know about the North Star and its brethren. Very cool. Star Talk, Explainers. Neil de Grasse Tyson. Keep looking up.