In short
Einsteinian time dilation, evidence from particle decay and photons, spacecraft gravity assists (“cosmic drafting”), and the North Star/Polaris (not the brightest), including how Earth’s precession shifts the zodiac so your zodiac sign can be “wrong.”
Guest backgrounds
No named guests appear in the transcript; it’s Chuck and Neil deGrasse Tyson riffing as hosts.
Key claims
Faster motion and stronger gravity make time tick slower for the moving/affected observer; GPS pre-corrects satellite clock rates. Particle accelerators show accelerated particles decay more slowly, matching relativity. Photons have no internal time, so light from far stars arrives “instantaneously” in the photon’s frame. Gravity assists gain speed by stealing a bit of a planet’s orbital energy when approaching from behind; Voyager used multiple assists to escape the solar system. Polaris is ~49th brightest; it’s near Earth’s axis, not directly overhead except at the North Pole, and precession means the “pole star” changes over millennia, shifting zodiac constellations.
Notable examples
GPS satellites; muons/protons decaying in ~6 minutes; photons from the Milky Way’s center (30,000 years ago); Voyager 1/2; Big Dipper “pointer”; Vega as future polestar; Ophiuchus as the 13th zodiac constellation.
Written by AI. May contain mistakes. Listen to the episode to check what was said.
Chapters
Tap a time to open that second in VOEinstein and Time Dilation
0:15 to 0:26
Explore Einstein's theory of relativity and its effects on time perception.
“First steps, first swim lesson, or first sleepover.”
Einstein and Time Dilation
0:55 to 1:49
Explore Einstein's theory of relativity and its effects on time perception.
“Welcome to StarTalk, your place in the universe where science and pop culture collide.”
Gravitational Effects on Time
1:49 to 3:37
Discuss how gravity influences time, especially with satellites.
“You still got your heartbeat, all of this.”
GPS and Relativity
3:37 to 4:52
Understand how GPS technology is affected by relativity corrections.
“So that their clocks tick faster than our clocks on Earth's surface because they're farther away.”
Speed of Light and Time
4:52 to 6:22
Learn about the relationship between light speed and the aging of photons.
“And once you calculate that, then you do and you say, oh my gosh, the formula works.”
Particle Decay and Relativity
6:22 to 7:30
Examine how particle decay times are altered by speed in accelerators.
“So I didn't even get to the part where I lose sleep.”
Observing the Universe
7:30 to 9:29
Discover the implications of light travel times in astronomy.
“And that becomes living proof of what Einstein said.”
Observing the Universe
11:25 to 11:45
Discover the implications of light travel times in astronomy.
“with the same clinically proven ingredient.”
Observing the Universe
11:53 to 12:23
Discover the implications of light travel times in astronomy.
“Whether you're prepping for wedding season, festival season, or just planning the ultimate vacay, the right shoes can make or break an RSVP.”
Gravity Assists in Space Travel
12:44 to 14:00
Learn how gravity assists work and their significance in space missions.
“One, because Neil-splaining has always been good for me.”
Show all 20 chapters
Understanding Gravity Assists in Space Travel
14:00 to 21:07
Learn how spacecraft use gravity from planets to gain speed and travel efficiently in space.
“And you could end up doing that without using a very big rocket to begin with.”
The Impact of Spacecraft on Planetary Orbits
21:07 to 21:46
Explore the implications of using gravity assists on planetary orbits and energy.
“And that's how we leave the solar system.”
Mars and the Importance of Environmental Awareness
23:23 to 26:19
Discuss the significance of caring for Earth while exploring Mars and its features.
“So you're saying I should drink more plastic bottles so you can make more of that luggage?”
The North Star and Its Misconceptions
28:00 to 30:55
Explore common misconceptions about the North Star's brightness and significance.
“What's the brightest star in the nighttime sky?”
Understanding the North Star's Position
30:55 to 35:38
Learn about the North Star's position relative to Earth and how to identify it.
“That axis is pointing to a spot in space, okay?”
The North Star's Brightness and Cultural Significance
35:38 to 42:01
Discuss the North Star's actual brightness and its cultural role in navigation.
“Directions on the sky from the stars are exactly like that.”
The North Star's Role and Significance
42:01 to 48:32
Learn about the North Star's navigational importance and its actual brightness ranking.
“So the elevation in degrees of the North Star above your horizon is your latitude on Earth.”
The North Star as a Concept
48:33 to 48:50
Discover how the North Star is more of a concept than a fixed point in the sky.
Astrology and the Zodiac Shift
48:51 to 52:09
Explore how Earth's precession affects the zodiac signs and their corresponding dates.
“One of the consequences of the precession Right.”
Cancer's Unfortunate Constellation
52:10 to 53:12
Unpack the humorous and critical take on the Cancer constellation and its significance.
“There's like five stars and they have like a crab with claws and a crustacean.”
Transcript
Automatic transcript. May contain errors.0:00There's a fire inside you you can't ignore. Stand still, not a chance. You're a lifelong learner who's come this far. Now, we're here to help you keep going further. Capella University, what can't you do? Visit capella.edu to learn more. Carter's has your family covered for every summer first. First steps, first swim lesson, or first sleepover. Our clothes help kids and parents shine, thanks to comfy design and easy dressing details. Visit carters.com to shop the latest styles or find a Carter's store near you.
0:31Neil deGrasse Tyson: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 assist 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.
1:10Neil deGrasse Tyson: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've got to tell you, a lot of things already beat you to that. Oh, sure. You mean the asteroid strike that could happen? Exactly. Or the global warming? Yeah. 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.
1:57Neil deGrasse Tyson:Correct. You don't know anything's happening. Right. Right. Your clock still ticks as far. You still got your heartbeat, all of this. OK, so this is not a physiological thing. It is an actual property of the fabric of space and time under those conditions. Wow. OK. 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 same 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 um 10 years later that took a lot more math and and deeper insights into the universe So once again, it makes sense because you're dealing with the fabric of space time.
2:57Neil deGrasse Tyson: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 then be called the general theory of relativity. Okay. So the geosynchronous satellites are like middle orbit. That is far enough away from Earth's source of gravity for them to have a difference, a measurably different space time condition.
3:37Oh.
3:38Neil deGrasse Tyson: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 fluid, the slower time ticks. So they're farther away. 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 where it's been properly corrected and it matters to us and our space-time 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.
4:42Neil deGrasse Tyson: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. Okay. And once you calculate that, then you do and you say, oh my gosh, the formula works. Einstein was right. Right. This is not just something on a few high theory, 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.
5:19Neil deGrasse Tyson:Yeah, these aren't just cult heroes that we wish they were right. These are real. This is real. Okay. This is 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 speed, 90 % the speed of light, 99 % the speed of light. Time is ticking 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, 99.9, 99.99 % the speed of light. Because you're the observer of that.
6:01Of 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. Correct. Basically, you see them unfold. Correct. Boom. God. Correct. That is insane.
6:19Neil deGrasse Tyson:So now watch. Oh my God. Wait. Now 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. One part of it decays and becomes another part and releases the often deadly energy. Yes. Radioactivity. All right. Some particles, let's take, for example, the proton or the muon. one of these uh decays in like six minutes when it's left out in the in the wild okay when it's not part of an atom okay when it's not in captivity i forgot which of these it doesn't matter for my example decay is in like six minutes okay okay what happens if you take that particle and speed it up in a particle accelerator so you take a a community of these particles speed them up calculate wait a minute the internal wristwatch on these clocks says they should live longer and And sure enough, their decay time takes longer.
7:24Neil deGrasse Tyson:Wow. That's, oh my God. Yes. Yes. Oh, wow. Yes. And that becomes living proof of what Einstein said. Yes. Because we can't go half the speed of light. Right. We 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.
8:11Neil deGrasse Tyson:But there are things that travel at the speed of light. And what is that? Those would be photons. Yes. Thank you. Those would be 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.
9:06Neil deGrasse Tyson: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 hit people's tanning on the beach. You know? They're very sad. Imagine traveling 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.
10:01but 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're in a telescope
10:15Neil deGrasse Tyson:yeah yeah that would be an interesting but when i what i want to be when i grow up 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. That is more than fascinating. 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... That's another episode. That's what I'm saying. Another episode.
11:09Hey! Hi, can you say Oshkosh Pagosh? Oshkosh Pagosh! Oshkosh Pagosh! Oshkosh Pagosh! Shop back to school styles at Oshkosh.com or visit a Carter store near you. The GLP-1 pill you've been waiting for is now on row. Yep, it's finally here. with the same clinically proven ingredient. Now in a pill. And now on Rho. It's the first FDA-approved GLP-1 pill for weight loss. At the lowest price available, that's one daily GLP-1 pill for big results. Now on Rho. Go to roe.co slash listen to see if you qualify. RX only. Go to roe.co slash safety for serious side effects and boxed warning associated with GLP-1s.
11:56At DSW, we ask the important questions. Like, what shoes are you going to wear? Whether you're prepping for wedding season, festival season, or just planning the ultimate vacay, the right shoes can make or break an RSVP. So own the moment. You've got big plans, and we've got just the shoes. At the perfect price, of course. Get ready to get ready with Designer Shoe Warehouse. Head to your DSW store or DSW.com today. And let us surprise you. I'm Ali Khan Hemraj, and I support StarTalk on Patreon. This is StarTalk with Neil deGrasse Tyson.
12:43Do you like these, these explainer? Of course. One, because Neil-splaining has always been good for me. Neil-splaining, that's the thing. That's a good thing. Okay. For me. Okay.
12:56Neil deGrasse Tyson:You know, all other splainings are not good. Man splainings. That's exactly. Man splaining ain't good. You know what I mean? Black splaining, white splaining ain't good. But neosplaining, 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 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 want it to give it more speed than it currently has.
13:43Neil deGrasse Tyson: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 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 one and two this is back in the 1970s when it was launched they had trajectories that well let me say that differently the solar system's planets were configured in such a way that it could get multiple planetary assists right 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.
14:51Neil deGrasse Tyson: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 rather than 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, 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.
15:31Neil deGrasse Tyson:But wait a minute. Yeah. Just like there used to be for 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, no. You got out the other side. 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's saying, no, I'm pulling you back. Right. So it turns out if you look at the pure gravity picture, it is exactly symmetric to the planet.
16:20Neil deGrasse Tyson: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. OK, so then the question is, how do I end up getting all this damn speed? Where are the slingshot effect? OK, 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.
17:08Neil deGrasse Tyson: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 we 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.
17:53Neil deGrasse Tyson:Right. But the speed 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. They 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, give me some of that speed. Don't turn around. Don't look at my face. Don't look at my face.
18:38Just give me the speed. Nobody needs to get hurt here.
18:46Neil deGrasse Tyson: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 this, these are, this is the art of the, of the slingshot. Dude, that is, that's pretty amazing. That would make sense. Yeah. You can slingshot off of anything. Right. 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 can slingshot off the moon. You can slingshot off of Mars. Okay? It doesn't matter what planet you want to slingshot from.
19:30Neil deGrasse Tyson:Right. In the case of Voyager, Voyager 1, I think it was, it's slungshot. What's the past tense of to slingshot? It's slungshotted. Yeah, yeah. Slangshot. Slangshot. It was slangshot. It's slang shit off of Jupiter. Right. And so people think, well, Jupiter has big gravity. It'll get a huge speed. It's only getting Jupiter's orbital speed. Right. 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.
20:12Neil deGrasse Tyson:And if you want an inverse mugging, which no one will actually want to do in space, if you can fall towards the planet 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 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.
20:56Neil deGrasse Tyson: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 slingshot off of Mars like 20 times, what happens to the Mars orbit itself if you're taking away its energy? You haven't asked that. No. 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 siphoning off a tiny little bit of energy.
21:45Siphoning off a tiny little bit of energy.
21:47Neil deGrasse Tyson: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 okay that ratio is so huge that it's like a gnat flying full speed ahead into an elephant the elephant doesn't say you know watch out quit your shoving this 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 a hundred tons of meteors every single day wow tons so this stuff fallen and and 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 it's if you worry about oh my gosh what How about Mars?
22:47Neil deGrasse Tyson:Worry 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're 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 that luggage? No. Is that the takeaway?
23:31No. 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,
23:41Neil deGrasse Tyson: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 Valles Marineris on that? Really? Don't pretend like you're doing it. Because here's what I'm saying. Do you?
24:12Neil deGrasse Tyson:No, it looks like a high resolution image of Martian surface. It's not just like red, right? 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. I don't speak Martian. I'm sorry. Valles Marineris is basically the Mars Valley. and it's a huge canyon, way bigger than the Grand Canyon here on Earth. 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 of the bits of evidence of it.
24:53Neil deGrasse Tyson: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 of White. Is that how that goes?
25:09Neil deGrasse Tyson:but i need a vowel though yeah i got a i got a few of them right here oh yeah there you go i can 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 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 chute, right? Okay. Mars down the conveyor belt. Mars is coming down the conveyor belt. You'll be able to recognize yours.
25:45And as a matter of fact, you can turn to somebody and go, get your ass to Mars.
Read the full transcript
25:53Neil deGrasse Tyson:But don't take my luggage while you do that.
25:58Neil deGrasse Tyson:Okay. Very cool. I'm glad y 'all are working on good stuff. Gotta love this company. Soul 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.
26:16I'm glad I could be of service. Yeah, thank you, Chuck.
26:19Neil deGrasse Tyson:As always.
26:33In a world full of new, some things never change. Hey! Hi, can you say Oshkosh B 'Gosh? Oshkosh B 'Gosh!
26:47Neil deGrasse Tyson:It's easy. Osh? No, I say Oshkosh. Oshkosh B 'Gosh. I don't get it. Oshkosh B 'Gosh! Shop back to school styles at Oshkosh.com or visit a Carter store near you. The GLP-1 pill you've been waiting for is now on Rho. Yep, it's finally here with the same clinically proven ingredient. Now in a pill and now on Rho. It's the first FDA approved GLP-1 pill for weight loss. At the lowest price available, that's one daily GLP-1 pill for big results. Now on Rho. Go to Rho.co slash listen to see if you qualify. rx only go to road.co slash safety for serious side effects and boxed warning associated with glp ones you know that thing where you get an amazing pair of shoes at a really great price and want to tell everyone about it yeah so do we here at designer shoe warehouse we'll give you something to brag about like the latest styles from brands you love or the trends everyone's obsessing over or shoes that make you feel like well you so go ahead show off a little buying shoes that get you at prices that get your budget.
27:56Head to your DSW store or DSW.com today. DSW, let us surprise you.
28:13Neil deGrasse Tyson:What's the brightest star in the nighttime sky? Are we talking my career here, Neil?
28:20just saying i've i've been waiting for us to get around to this how bright is your star jack uh yeah no if if it were me up in the sky i would just be a dim a dim uh spot in the milky way
28:36Neil deGrasse Tyson:it is funny that a fundamental word in all of hollywood is derived from my profession it is astrophysics 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. Yeah. 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 10 people will say that.
29:16Neil deGrasse Tyson:right yeah okay they'll see the they'll see the first bright star after sunset and then assert that it's the north star so when in 100 of those cases they're looking at a planet well that makes sense because the planet is right there
29:34planets right in front of our noses planets are right here man
29:39Neil deGrasse Tyson: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 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 sentiment that is. Wishing on a star.
30:24I 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.
30:38Neil deGrasse Tyson:And I'm honored that my field supplies this level of cultural referencing to do all that we do. So so yeah. So the North Star is not the brightest star in the night sky. OK. I just want to make that clear. OK. Now. So now here's the thing. Yeah. Because. What what is the North Star? 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.
31:34That axis is pointing to a spot in space, okay?
31:38Neil deGrasse Tyson:In the sky. So we say, is there a star near to that spot? Because then we'd always be pointing in that direction. 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 correct. Okay, well, there you go. I said it was a guess. It's not Sirius. It's not Sirius the Dog Star. Yeah, the Dog Star is Sirius. Sirius is the Dog Star, not the North Star. So the name of this star is sensibly Polaris. Oh, for the pole or the axis, Polaris. Polaris.
32:27Neil deGrasse Tyson: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. I know. 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. All right. It's the same thermonuclear mechanisms going on. So, anyhow, 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.
33:13Neil deGrasse Tyson: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. Absolutely. And then it points and you go like four segments up and 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 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.
34:05Neil deGrasse Tyson: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 your camera is? Yes, exactly. And so otherwise, if 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?
34:43Neil deGrasse Tyson:What are the odds? Well, it's not exactly. The odds would be zero. That's a bad bet. It's not exactly over the North Pole. 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. It's kind of over there.
35:29Yeah, man. So what you want to do? You want to keep going down there? You're going to 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 a crate? Yeah, make it right there. Make it right there. All right? You're going to keep going, right? Just keep going and going, right?
35:46Neil deGrasse Tyson: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.
36:04I'm going to say it's a B student bright.
36:10Okay. It's not at the top. First of all, how do you measure brightness in the night sky? I really don't even know that.
36:16Neil deGrasse Tyson: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 could 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. 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.
37:05Neil deGrasse Tyson:The North Star is the 49th brightest star in the night sky. Oh my gosh. It is completely uninteresting. It is easily missable. Right. It is, does not call attention to yourself. That's why you need the lip of the Big Dipper to find it. To find it. because you actually need a pointer because it really isn't remarkable at all. It is not remarkable. Not remarkable. Wow. It kind of reminds me of somebody I know.
37:40Neil deGrasse Tyson:You sound like you should have your own TV show, reminiscent 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. That's what I'm saying. Venus is sitting around like, ah, just like a man.
38:18Just 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.
38:35Neil deGrasse Tyson: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 dimmer. And we don't call that the South Star? You can, but it has a name. It's called Sigma Octens. And it's very unassuming and nobody cares. You know why nobody cares? Because its name is Sigma Octens. Don't nobody want to talk about Sigma Octens? Because there's a constellation called Octens, 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.
39:18Neil deGrasse Tyson:You know why? ah 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 gonna put some badass Equipment here. So there's a there's a there's an architect's table. There's a 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 but right but oh i thought it was a trick question no that's not true no you look up 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 well that no that should be nothing he's he's already there no no degrees from the horizon to straight overhead oh for santa claus um 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 just 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 um uh straight Straight up, that's 90 degrees.
40:44Neil deGrasse Tyson:90 degrees. What is the latitude of the North Pole?
40:52360 degrees. What is the latitude of the North Pole? 90 degrees. 90 degrees, thank you. Okay. I just love, no, I said that because I wanted to see. This is what I love. 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. Hey, you do this. I gave you a second chance. You always do this. You're like.
41:24Neil deGrasse Tyson:I said my boy knows better than this. I'm going to give him 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 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 latitude on Earth.
42:10Oh. Oh, because it follows all the way down. It follows all the way down. It follows all the way down. That, well, that's pretty interesting.
42:17Neil deGrasse Tyson: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 the North Star, you'll eventually reach Santa Claus. But Ohio is good enough. Tell me.
42:41Who knew that the North Star was such a poser?
42:45Neil deGrasse Tyson: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 49th. We're 49th. We're 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, here 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 its 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.
43:30Neil deGrasse Tyson: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's called precession pre-session Precession that's an official term. So earth wobbles Okay Do we spend once in how often how long does it take to spin once 24 hours? I guess. Thank you Yeah, if you want to be precise is actually 23 hours and 56 minutes and four seconds Wow In case that but that's another explainer Well, you know, why do we think it's 24 hours when it's actually that? Okay.
44:12Neil deGrasse Tyson:I will. That's a whole other. We'll save that. Okay. With your permission. 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.
45:06Neil deGrasse Tyson: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 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.
46:00Neil deGrasse Tyson:But any other stars that it comes near? One of the stars in the night sky, I think 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 working its way towards forming planets. So we know some stuff about Vega. In 14 ,000 years, the wobble 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.
46:50Neil deGrasse Tyson:That's an appreciable fraction of the 26 ,000 years. They had a different Polestar than the North Star. Right. So in recorded history, civilizations have had different Polsars. 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.
47:20Neil deGrasse Tyson: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, one of which was Ricky Martin. Oh, I 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 swapped out the members as they were age out. They'd be like 18. They'd be like age out. That's what it was. Yeah. Sorry, Manuel. Your time is up. You got to go, bro. Wait, wait. You are now a man. You must join the man band instead of the boy band.
47:58Can't be in the boy band anymore. So that's pretty wild.
48:03Neil deGrasse Tyson: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 even 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? Yep. 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.
48:43Neil deGrasse Tyson:No, don't blame the star itself. You fraud. I got one more thing. The North Star is a fraud. Go ahead. I got one more thing. Ready? All right. All right. One of the consequences of the precession 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. Let's pick October. Okay. And so October, astrologically, the sun is moving through Libra. Okay. Okay? Well, the precession 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.
49:42Okay.
49:43Neil deGrasse Tyson: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 twelfth of twenty six thousand. Oh, my gosh. So is October still the month for Libra? No, the sun was in Libra two thousand 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 the zodiac people the astrologers still describe the sun being in these various constellations as they were mapped out 2200 years ago right between 2000 and 2400 years ago and so if you're it's cancer scorpio gemini you would expect the sun to be in that constellation the day you were born.
51:00Neil deGrasse Tyson:It was 2 ,200 years ago. Oh, man, that is so... It is not today. It's all shifted. And they're not really forthcoming about that. No, because if they were, then all of astrology would be bullcrap. That is... Oh, man. Oh, not only that, not only that, the sun in the zodiac actually passes through a 13th constellation. It's called Ophiuchus. All right. God bless you. Ophiuchus. Ophiuchus. Wow. Okay. In fact, the sun spends more time in Ophiuchus than it does in Scorpius. Okay. So if you thought you were Scorpio, you were probably Ophiuchan, and all Scorpios and Ophiuchans are currently Librans. Wow.
52:00Neil deGrasse Tyson:I just thought I'd put that out there. I just want to know, where does that leave cancer? Because that's what I am. Oh, you're a cancer? Yeah. I'm a cancer, so. 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 were 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. Okay. I got a lousy - If you ask astrologers, there are 12 prominent constellations in the sky.
52:41Neil deGrasse Tyson:No, they're not. Dad. Most of them. There's like three that 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. 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 haven't memorized 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.
53:21Neil deGrasse Tyson:StarTalk Explains. Neil deGrasse Tyson. Keep looking up.
53:55Transcription by CastingWords Outdoor deterrence requires a SimpliSafe Active Guard outdoor protection plan starting at$49.99 a month. Visit SimpliSafe.com slash licenses for alarm license information. Tennessee 2012. You wouldn't take financial advice from a 72 hours in a single day alpha influencer, would you?
54:10Neil deGrasse Tyson:Same goes if you're in a car accident or any accident. Who you choose matters. That's why Morgan & Morgan exists. They're the largest injury law firm in America, and they've built the reputation by actually winning cases, not just talking about it. Over a thousand lawyers across all 50 states and$30 billion recovered. Injured? Go to forthepeople.com slash podcast. That's forthepeople.com slash podcast.
From the publisher
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.