Pod Insights StarTalk Podcast Things You Thought You Knew – Where the Sun Don’t Shine About this episode Does being in space mean there is no gravity? What does noon have to do with the Artemis Mission? Neil deGrasse Tyson and comedian Chuck Nice break down weightlessness, planetary alignments, and what is going on on the south pole of the moon.
Transcript Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.
0:00 Neil deGrasse Tyson? You're in free fall.
0:01 Chuck Nice? Oh, wait, let me say something that makes me sound smart. You will be falling to whatever pulls you, no matter where that is, unless you happen to be in a La Grange Point. Ow, ow, ah!
0:17 Neil deGrasse Tyson? Welcome to StarTalk, your place in the universe where science and pop culture collide. StarTalk begins right now.
0:30 Neil deGrasse Tyson? This is StarTalk, Things You Thought You Knew Edition. And of course, I'm doing this with my co-host Chuck Nice. So Chuck.
0:39 Chuck Nice? Yeah.
0:40 Neil deGrasse Tyson? I've done this experiment. I ask people, where's the sun at 12 noon?
0:44 Chuck Nice? Right.
0:44 Neil deGrasse Tyson? Invariably, more than half the cases, they point straight up.
0:48 Chuck Nice? Straight up, high noon.
0:49 Neil deGrasse Tyson? And what's odd is it means they've never looked. Because for the entire continental United States.
0:58 Chuck Nice? Right.
0:59 Neil deGrasse Tyson? At no time of day and no day of the year.
1:02 Chuck Nice? Okay.
1:03 Neil deGrasse Tyson? Is the sun ever directly overhead.
1:05 Chuck Nice? You know why? I think it's difficult because it's hard to look at the sun.
1:11 Neil deGrasse Tyson? Yeah, and you shouldn't look at the sun.
1:15 Neil deGrasse Tyson? But you might notice, maybe at noon, the shadows go away because it's pointing straight down.
1:20 Chuck Nice? True.
1:20 Neil deGrasse Tyson? But so it just means modern people, just not observant. They repeat things they've heard.
1:26 Chuck Nice? True.
1:26 Neil deGrasse Tyson? And plus the word "high" in front of noon leaves people thinking that it's directly overhead. It's just not true.
1:32 Chuck Nice? It leaves some people thinking it's directly overhead. It leaves other people thinking something totally different.
1:39 Neil deGrasse Tyson? High noon, it's a very Western concept.
1:41 Chuck Nice? Yes, it's where you kill a man in the middle of the day.
1:45 Neil deGrasse Tyson? No, Chuck, no, stop!
1:49 Neil deGrasse Tyson? No, it's where you have a shootout in the middle of the day. Whether or not anybody dies, that's right.
1:54 Chuck Nice? True, true, true, true, right.
1:56 Neil deGrasse Tyson? Meet you at high noon. All right, so there are places on Earth where the sun is occasionally directly overhead. And it's between 23 and 1/2 degrees north latitude and 23 and 1/2 degrees south latitude. And 23 and 1/2 degrees is the tilt of Earth's axis.
2:12 Chuck Nice? Okay.
2:13 Neil deGrasse Tyson? In our orbit. So that's where that number comes from. If you go in that range, those are what we call the tropics. And there are days of the year where the sun is actually directly overhead. Okay. Cool. If you're between those two zones. Right. And the tropic of cancer, which is the northern one, tropic of Capricorn is the southern limit. The tropic of cancer is falls just below Key West.
2:42 Neil deGrasse Tyson? Just below Key West. Okay. So, so that's why nobody in the continental United States. Has ever. Hawaii is about fifteen degrees north latitude. So Hawaii gets to experience this, but not anybody else in the, in the continental United States. Okay. The general trend here is the farther away you are from the equator, the closer you are to the poles. Right. The lower the noon time sun gets. Gotcha. Okay. So if in the tropics, it's occasionally directly overhead, as you inch your way out of the tropics, the noon time sun gets lower and lower and lower in the sky. Right. Okay.
3:26 Neil deGrasse Tyson? Now that will change seasonally. In New York City, where we live, where we record StarTalk, the noon sun in the winter, on December twenty first, first day of winter, doesn't get more than twenty-six degrees above the horizon. Oh. That's high noon, December twenty first. Wow. Now you go to June twenty first, the high noon sun is higher, but still not directly overhead. Gotcha. All right, directly overhead would be ninety degrees up. Right. It's about, I gotta look it up, it's seventy-four degrees, something like that. Wow. High. That's high, but it's not still. That's a long way from directly overhead. A long way from directly overhead. Yeah.
4:07 Neil deGrasse Tyson? So, all I'm saying is that the highest the sun gets on any day of the year. Right. Is lower as you approach the pole. Okay. Got you. Okay, alright. So. You keep marching. You get to the Arctic Circle. Okay. Sixty-six and a half degrees. Of latitude. There is a day where the sun never sets and it stays that way throughout the summer. And then it drop drift back down to the horizon and then it goes below the horizon for the winter months. And then it's not to be seen again. Oh. Until summertime. Yeah. So they basically just have day and night.
4:51 Neil deGrasse Tyson? Yes, two seasons, day and night. Day. Exactly. Day and night. Alright. So now that makes an interesting fact. Okay, let's go to the moon. Alright. Let's go to the moon and go to the poles. Alright. Okay. Let's go to the South Pole. No different, we can go to the North Pole, but I got, we got good stuff going on in the South Pole for this explainer. Okay. Alright. So you go to the South Pole. As you approach the pole. The sun. The height of the sun above the horizon doesn't get very high, right? Just like I described here on Earth. Right. Okay.
5:30 Neil deGrasse Tyson? So the noon time sun in the South Pole of the moon is very low on the horizon. Okay. Are we there? That makes, okay, I'm with you. Now. There are craters on the moon. Yes. As you've surely seen. Mm-hmm. Some craters are at the South Pole. Okay. Craters everywhere, summer and so. Craters have rims. Mm-hmm. Okay. Rims. That stick up a little bit above the terrain. Right. Alright. Hmm, craters are deep. Yes. I got a deep crater and a rim and I'm at the South Pole. Oh my gosh.
6:15 Neil deGrasse Tyson? When the sun is up.
6:18 Neil deGrasse Tyson? At the moon's south pole, it does not get high enough to peer above the rim of the crater. So the base of some craters at the lunar south pole never ever sees someone. Saw the sun. Wow. Okay. So it is literally where the sun don't shine. Hehehe. Okay. You know, there's another south pole where the sun don't shine. Just letting you know. Okay, okay, okay. So, so now what's interesting on the moon is because there's no air
6:59 Neil deGrasse Tyson? and there's no sky getting illuminated by sunlight, right? Why do we have a blue sky? Because light comes from the sun, scatters into the atmosphere. So you say, oh, we have clear skies. Actually, no. You're looking at blue light scattered off of air molecules. Right. You're not actually looking at the universe. Right. Universe is cloaked by the scattered light. And because the scattered light is everywhere, if something is in a shadow, it's a little darker, but you could see it. Because light's coming from everywhere other than the sun as well. Right. All right. I mean, think about it. If the sun were over to the left and there's a tree and the tree makes a shadow, you shouldn't be able to see anything inside the shadow because the sun is not illuminating it. It should be completely dark, but it's not.
7:45 Neil deGrasse Tyson? Because light is coming from all the scattered light elsewhere in the atmosphere. On the moon, where there is no atmosphere, there's no scattered light. Shadows are pitch black. Ooh. All right. That's actually kind of cool. It is kind of cool. It is kind of, unless you have something reflecting light into the shadow. Right. There's no scattered light from the atmosphere. Oh, by the way, there are people who are sure we did not land on the moon. And they looked at the photos of Neil Armstrong and Buzz Aldrin in daylight. And they say, we know you're supposed to see stars in daylight, and I don't see any stars in this photo. Right. Okay, so therefore we didn't really go to the moon.
8:24 Neil deGrasse Tyson? As though NASA wouldn't know to fake that if that were the case.
8:29 Chuck Nice? Oh, that's okay.
8:30 Neil deGrasse Tyson? You think NASA are idiots?
8:32 Chuck Nice? That, that, that kinda makes a lot of sense. If you know that, well, then we, the space people, definitely knew it too.
8:39 Neil deGrasse Tyson? Definitely know it.
8:40 Chuck Nice? So why wouldn't we just throw, throw a little dots in the back and let you see some stars?
8:44 Neil deGrasse Tyson? Okay, what the person doesn't know is how photography works. Okay, the terrain is so bright from the sun.
8:50 Chuck Nice? Right.
8:50 Neil deGrasse Tyson? The aperture of the camera closes down and cannot register the light of things such as the stars in the sky. So that's why, that's how that plays out.
8:59 Chuck Nice? There you go, that's true, that's absolutely the case.
9:02 Neil deGrasse Tyson? Alright, so let's get back to the South Pole.
9:03 Chuck Nice? Okay.
9:04 Neil deGrasse Tyson? So it's not, the sun not only doesn't shine, you can't even see in it.
9:07 Chuck Nice? Right.
9:08 Neil deGrasse Tyson? Alright, so now, what's making these craters?
9:11 Chuck Nice? Um, some, well, a meteor or something, something hit it.
9:17 Neil deGrasse Tyson? Thank you, I don't, I don't ask complicated questions.
9:20 Chuck Nice? Yeah, something hit it, it was just like.
9:21 Neil deGrasse Tyson? Something hit it, okay? So meteors can be made of rock, or they can be made of ice. There are comet fragments that are out there, so both can make these craters.
9:31 Chuck Nice? Right.
9:32 Neil deGrasse Tyson? Alright, so now, if a comet hits the moon, and the, so the material is now not rock, it's like water and other ices, like ammonia ice and things. Let's look, focus on the water. The water molecules, there's a lot of energy there, it'll evaporate. The water molecule flies up, okay? And then falls back to the moon's surface. Alright.
9:56 Chuck Nice? Right.
9:57 Neil deGrasse Tyson? Alright, well, if it falls to a part of the surface that's in sunlight, it'll eventually evaporate and escape.
10:04 Chuck Nice? Right.
10:05 Neil deGrasse Tyson? But suppose it happens to fall where the sun don't shine?
10:10 Chuck Nice? It stays frozen.
10:11 Neil deGrasse Tyson? It stays frozen, it's called a cold trap. That's the official term for it.
10:16 Chuck Nice? Nice.
10:17 Neil deGrasse Tyson? Cold trap. And falls in there, and it stays there for billions of years.
10:22 Chuck Nice? Oh.
10:22 Neil deGrasse Tyson? Let me say that right.
10:24 Chuck Nice? Billions of years.
10:26 Neil deGrasse Tyson? Billions of years. And so, the next mission to the moon, Artemis, okay? The, the one where we're gonna land, Artemis 3.
10:37 Chuck Nice? Right.
10:38 Neil deGrasse Tyson? Okay, this is NASA's mission to, why, Artemis is the twin sister of Apollo. And Artemis was the goddess of the moon and other, other, and other related things. So, so they're, they're targeting the South Pole to land.
10:53 Neil deGrasse Tyson? To check and verify that there is water there inside those craters. We think, we not only think there is theoretically, we have some measurements that there's likely water there, and now we're gonna go and verify for sure. Because if there is, you don't need to bring water to the moon to drink. Oh, look at that. It's part of what's called ISRU, in situ resource utilization, which is a NASA thing. And, uh, so- Why, why, why bring sand to the beach? Why bring water to the moon? You ain't gotta bring water to the moon. Right, right, right. I like that. Why bring sand to the beach? Very good. There you go. Unless your beach ain't got no sand.
11:32 Neil deGrasse Tyson? If it's a rocky beach, I might bring sand. Right, right. So, so, all of this is related to the fact that the sun doesn't get very high in the sky at the poles. That's all. That's true. That's why I started on Earth and I landed on the moon for this explainer. That's very cool. That I love. I love it. That's why NASA, we're checking out the South Pole. It'll be a geologically, chemically interesting next place to visit. Wow. So we go to the moon to look for water in a cold trap? In a cold trap. And they'll need their own lights to see their way around. Plus, I, I, it's not this way, because it's like molecule deposits, but you'd have to mine the water through the material. You bring the lunar material through and sift out the
12:15 Neil deGrasse Tyson? water molecules, and then you have a puddle of water. What they could do is sprinkle the water back in and then go ice skating, maybe. Oh, that'd be good. That's kinda cool. Unless it's too cold to ice skate. That could happen.
12:32 Speaker 02 Hi, I'm Chris Cohen from Hallworth, New Jersey, and I support StarTalk on Patreon. Please enjoy this episode of StarTalk Radio with your and my favorite personal astrophysicist, Neil deGrasse Tyson.
12:53 Neil deGrasse Tyson? Every time you see a space movie or something and people are in space, they're always weightless. You ever notice that?
12:58 Chuck Nice? That's true. And you know that because they're, well, if you're Sandra Bullock, your hair is like Afro. You got a little space Afro going on.
13:10 Neil deGrasse Tyson? Except she didn't. In the movie Gravity, her bangs always seemed to know which way down was.
13:15 Chuck Nice? That's funny.
13:16 Neil deGrasse Tyson? Everything else was floating in the capsule. So it leaves people thinking that space equals no gravity.
13:24 Chuck Nice? Right.
13:24 Neil deGrasse Tyson? It leaves people thinking that. Like you just go up into space and all of a sudden you're weightless. And weightlessness is a very special condition
13:34 Chuck Nice? Oh.
13:35 Neil deGrasse Tyson? that for which you do not have to be in space to achieve. So I just want to just tease this out of people's misunderstandings.
13:44 Chuck Nice? I'm not gonna push back on you. I'm just gonna say that maybe your people have something to do with this.
13:52 Chuck Nice? Here's why. Whenever you see people, you know, in space, in the space station, whatever, they always say they're in zero G. Well, we think zero G means zero gravity. That's what we're gonna think.
14:05 Neil deGrasse Tyson? Correct. It is zero G because there's no net gravitational force acting on them. Okay? No net gravitational, there's an important distinction here. And I don't want to be too pedantic, semantic about it.
14:19 Chuck Nice? Yeah.
14:19 Neil deGrasse Tyson? But, but, okay? If you are in orbit around Earth.
14:26 Chuck Nice? Okay.
14:27 Neil deGrasse Tyson? You are falling towards Earth. We did a whole explainer on this.
14:30 Chuck Nice? Yes, we did.
14:31 Neil deGrasse Tyson? How do you achieve orbit? All right? And
14:34 Chuck Nice? Talk about Newton and shooting the cannonball off.
14:36 Neil deGrasse Tyson? All of it, the cannonball and your duck and all of that. So here's my point. Let's say you are en route towards the moon.
14:44 Chuck Nice? Okay.
14:45 Neil deGrasse Tyson? Okay. Do you know how we do that? How does NASA do that? Well, they go in orbit.
14:49 Chuck Nice? The subway?
14:50 Neil deGrasse Tyson? Then they do a TLI, Translunar Injection, where they leave Earth orbit and aim towards where the moon will be
14:57 Chuck Nice? Will be.
14:57 Neil deGrasse Tyson? when they get there. Okay?
14:58 Chuck Nice? Nice.
14:59 Neil deGrasse Tyson? All right. So at that point, they shut off their engines.
15:04 Neil deGrasse Tyson? If you're in space and your engines are shut off, you are falling towards whatever is pulling you wherever it is.
15:13 Chuck Nice? There it is, right.
15:14 Neil deGrasse Tyson? You're in free fall.
15:15 Chuck Nice? Oh wait, let me say something that makes me sound smart. And I learned this from an explainer that we did. This is why you need to listen to the explainers, people. You will be falling to whatever pulls you, no matter where that is, unless you happen to be in a Lagrange point.
15:32 Neil deGrasse Tyson? Oh.
15:33 Chuck Nice? Ow. Ah! Ow! Look at that! Ah!
15:40 Chuck Nice? This is what I love this job, cuz I didn't know that. Like, however, whenever I didn't know it, I didn't know it.
15:45 Neil deGrasse Tyson? Okay, so there are five of them, and we don't have to get into that just now. But all I'm saying is, if you are coasting, then you are falling towards where whatever is pulling you at that point.
15:59 Chuck Nice? Right.
15:59 Neil deGrasse Tyson? Okay? You will be weightless as long as you are coasting.
16:03 Chuck Nice? Right, okay.
16:04 Neil deGrasse Tyson? No matter what, okay? And so here's what'll happen. They have transluter injection, which is enough speed to make it to the, one of the Lagrange points between Earth and the Moon. That's called L1. At that point, the Earth's pull towards Earth equals the Moon pull towards the Moon.
16:27 Chuck Nice? Uh huh.
16:27 Neil deGrasse Tyson? That's a balance point, okay? So now, if I have enough energy to cross that point, now I will guaranteed to fall towards the Moon.
16:39 Chuck Nice? Towards the Moon.
16:40 Neil deGrasse Tyson? Exactly. Now, if I don't have enough speed to reach that point, guess what happens?
16:44 Chuck Nice? Uh, Earth says, "Where you going? Come on back. The hell you think you doing? Oh, you trying to sneak out? You trying to sneak out on me? Get your ass back there."
16:55 Neil deGrasse Tyson? Get your ass back here right now. So if you don't make it to that first Lagrange point, you will fall back to Earth, exactly, okay? But that entire time, you're still just falling, okay? As you're leaving Earth, you are falling, Earth's gravity is pulling back on you, slowing you down, but you're in free fall, even though you're leaving Earth, and you're in free fall when you turn around, and you're in free fall when you come back. You're weightless that entire time, okay? If you cross the boundary point, you're weightless crossing it. You're weightless the whole time, okay? You are weightless until...
17:31 Neil deGrasse Tyson? You hit the moon.
17:35 Neil deGrasse Tyson? Then you are one-sixth Earth's gravity, okay, on the moon. After you collide, alright? Or if you turn on your engines. Okay. If you turn on your rocket engines anywhere in space. Okay. When you were otherwise just coasting. Right. You will have what is effectively a gravitational field inside your rocket. Alright. Cause the rockets will be accelerating the spaceship. Gotcha. Okay, it'll be accelerating. Right. So, so what's a good way to show that? Um, alright, so how about this? So, we're in a rocket sort of headed towards Mars, let's say, okay?
18:20 Neil deGrasse Tyson? We're standing on the bottom of the rocket. Okay. Okay, so the bottom, the trail end of this thing headed towards Mars. But we're weightless. We're weightless, but we're glued to the bottom. And I toss you something, it'll just go straight towards you. Right. Okay, cause everything is weightless. Everything, nothing's falling, it'll just go straight towards you. Can I watch? I now ignite the rockets. The moment I toss the object. Right. The rocket is going at a particular speed the instant I let go of the object. And the rocket is going faster in the next instant and still faster in the instant after that. So the object will look like it'll fall towards the floor of the rocket. Towards the back, which is our floor. Which is our floor.
19:04 Neil deGrasse Tyson? It'll look like it's falling towards the rocket, towards the bottom of the rocket. Whereas it's the bottom of the rocket accelerating towards the object. Right. Einstein figured out that if you're in a rocket, you cannot know the difference.
19:23 Neil deGrasse Tyson? Between the rocket accelerating through space and whether the rocket is sitting there on Earth.
19:28 Chuck Nice? Right, because the rocket is creating an artificial gravity.
19:32 Neil deGrasse Tyson? Correct, by having, by having the acceleration. Now, I managed to catch in a couple of episodes of The Expanse.
19:40 Chuck Nice? I love that show.
19:41 Neil deGrasse Tyson? Anyway, The Expanse is like, there's the, the folks from Mars, and then the asteroid belt, then the Earth Federation, and of course, there's wars and things, and fighting and bad people. Alright, point is, when they put on their rockets, there's acceleration inside the rocket.
19:57 Chuck Nice? That's right.
19:58 Neil deGrasse Tyson? They, they, there's basically, they have a way to attach to the surfaces when they are in zero G, and they make sure you know that, so they're not playing loosey goosey with the laws of physics.
20:09 Chuck Nice? They wear gravity boots.
20:10 Neil deGrasse Tyson? They're basically bad, but in other conditions and other circumstances, and I haven't seen all seasons, but the few I've seen, they're thinking about this.
20:18 Chuck Nice? They, they play, they play it straight, yeah.
20:19 Neil deGrasse Tyson? They play it straight, and when the, when it's accelerating, there is an effective field of gravity in the ship. And the higher that acceleration is, the higher that gravity will feel, okay? Unlike the film, what's the one where they had moon pirates? Uh, don't get me started, um, oh, it had Tommy Lee Jones in it, and, oh, yes you do, um, Ad Astra.
20:45 Chuck Nice? Oh, yes, Ad Astra.
20:46 Neil deGrasse Tyson? In Ad Astra, they're, they're in rockets accelerating to the moon, so it takes faster than three days to get there.
20:54 Chuck Nice? Right.
20:54 Neil deGrasse Tyson? And in the accelerating rockets, everybody's weightless.
20:58 Chuck Nice? Yes, that's correct.
21:00 Neil deGrasse Tyson? No, that's not how that works.
21:02 Chuck Nice? So great.
21:03 Neil deGrasse Tyson? If you want to get to the moon in a few hours, everybody's sitting in their chair feeling this gravity.
21:07 Chuck Nice? Might as well, you might as well be on a 737 to, you know, New York City.
21:11 Neil deGrasse Tyson? Thank you.
21:12 Chuck Nice? Because it's the same thing.
21:13 Neil deGrasse Tyson? Same thing.
21:13 Chuck Nice? What a great catch, because I now remember that, but that, uh, I didn't even catch that, I didn't even make that connection.
21:18 Neil deGrasse Tyson? They all float around weightless, and you see the rockets firing in the back, it's not how that works. Well, the difference between what a 737 is, in the 737, you still feel Earth's gravity down, because you're not in orbit and you're not in free fall.
21:31 Chuck Nice? Right.
21:32 Neil deGrasse Tyson? That's why balloons, if you're floating, but you still have a, if you put a scale under your feet, you're gonna still weigh as much as you do on Earth.
21:39 Chuck Nice? Right.
21:40 Neil deGrasse Tyson? Because it's not in free fall.
21:41 Chuck Nice? Right.
21:42 Neil deGrasse Tyson? Okay.
21:43 Chuck Nice? Right.
21:43 Neil deGrasse Tyson? It's all about free fall. Now, if now, if I put you in an elevator, cut the cable.
21:49 Chuck Nice? Right.
21:49 Neil deGrasse Tyson? You're in free fall.
21:51 Chuck Nice? Right.
21:51 Neil deGrasse Tyson? So you're gonna fall and the and the and the chalk that you're holding is falling with the ball. And everything's falling and it looks like it's floating in front of your face.
21:59 Chuck Nice? So you could let go of your drink, your little soda can. While you're falling in the elevator and it would just stay right there, right with you.
22:07 Neil deGrasse Tyson? Correct, correct. And you wanna know a really cool experiment? Okay, you could do this at home, but we'll do it in the elevator first. Cause these are experiments you do in the elevator before you die at the bottom. Okay, so this is, but it's for science.
22:20 Chuck Nice? Well, we might as well get those experiments out of the way, I mean.
22:25 Neil deGrasse Tyson? If you're gonna die, let it not be in vain, okay?
22:27 Chuck Nice? Exactly.
22:27 Neil deGrasse Tyson? Uh, when the elevator hits the bottom. So if you if you if you have one of these big gulps, okay? So it's a huge container and you're sitting there and the elevator's on the, you know, hundredth floor. And you puncture a hole in the side of your your big gulp vessel. Okay, so what's gonna happen?
22:46 Chuck Nice? Well, it should start, you know, sprinkling out.
22:49 Neil deGrasse Tyson? It wasn't a sprinkle, it's a nice hole.
22:51 Chuck Nice? It's a stream, it's a stream.
22:52 Neil deGrasse Tyson? It'll stream out. It'll have a nice arc as it goes down, okay? It's coming out because it feels pressure from the weight of the water above the hole.
23:01 Chuck Nice? Above the hole, right.
23:02 Neil deGrasse Tyson? Uh, go back to our water tower.
23:04 Chuck Nice? Water towers, yeah.
23:05 Neil deGrasse Tyson? Uh, if you wanna know about the weight of water. So, and by the way, if you put multiple holes, the one at the bottom will make a longer stream than the ones that are above it. Because it's under higher pressure.
23:16 Chuck Nice? Right.
23:16 Neil deGrasse Tyson? Okay, so have a long stream and middle stream and a little stream. If you can punch three holes in it simultaneously.
23:22 Chuck Nice? Right.
23:23 Neil deGrasse Tyson? That's the weight of the water putting pressure to have the water exit the hole. So now, cut the cable.
23:30 Chuck Nice? Okay.
23:31 Neil deGrasse Tyson? You fall, the cup falls, the the soda falls. Everything is falling and everything is in free fall and everything is weightless. You're in zero G. If you are in zero G, the water is no longer under pressure. Because the water above it doesn't weigh anything.
23:51 Chuck Nice? Right.
23:51 Neil deGrasse Tyson? And if the water above it doesn't weigh anything, there is no pressure for the water to come out the hole. The water does not know to exit the hole and all three of those spillages cuts off instantly.
24:06 Chuck Nice? Nice.
24:06 Neil deGrasse Tyson? For the entire journey until you die at the bottom.
24:10 Chuck Nice? Right. In which case, you just got a little, a bigger mess on the floor than you have to worry about with the big gulp. You know, believe me.
24:17 Neil deGrasse Tyson? Okay, so now, the way to do this is go get a big gulp, right? Ready? Here's what you do. Puncture three holes in it, three vertical holes, and then put tape, one piece of tape over it. Okay? Now, fill it up with some liquid that doesn't make a mess. Now, stand up on some ladder. All right? Or above some stairs or something, right? Now, hold it up high and film this. Film this, okay?
24:47 Chuck Nice? Okay.
24:48 Neil deGrasse Tyson? Take the tape, quickly remove it.
24:51 Chuck Nice? Rip it off.
24:52 Neil deGrasse Tyson? You'll see the three streams and then let it go. And all three streams will just stop, like they would just cut off. Because while the cup is falling, it is weightless. And it'll continue that way until it hits the ground.
25:06 Chuck Nice? Very cool.
25:07 Neil deGrasse Tyson? If you are accelerating, this is what happens. And by the way, NASA calls it microgravity. To this day, I do not understand why. Or rather, I'll make a stronger statement. They have misnamed it by calling it microgravity.
25:21 Chuck Nice? Okay.
25:21 Neil deGrasse Tyson? Gravity is identically zero on an orbiting spacecraft. They're worried because we're still in Earth's gravitational field.
25:30 Chuck Nice? Right.
25:30 Neil deGrasse Tyson? Okay? So I think they're worried that that might confuse people. So that's why you say zero G, because that's a, that's a force, zero G force.
25:38 Chuck Nice? Gotcha.
25:39 Neil deGrasse Tyson? That's a, it is a zero G, zero G. And Walther Cronkite in the 1960s, when we, when Apollo was eight, Apollo, Apollo eight or 10, when we first went to the moon before the astronauts landed. This, one of his broadcasts said, um, as of 4:45 this afternoon, the astronauts have left the gravitational pull of the Earth. It's like...
26:04 Chuck Nice? And then he, then he had to say, this just in, I'm an idiot.
26:11 Chuck Nice? I've just been told that I'm a complete dumbass because that's not true.
26:14 Neil deGrasse Tyson? Because they're en route to the moon, which last we checked is held to earth by earth's gravity. Right? So what he meant there was that it crossed from earth's influence to the moon's influence. It crossed one of the Lagrange points.
26:28 Chuck Nice? Right.
26:28 Neil deGrasse Tyson? So he lost an education, a, a, a, a learning opportunity for the audience. And so, yeah, there's no micro nothing. Okay? It is zero freaking G, period.
26:38 Chuck Nice? There you go.
26:39 Neil deGrasse Tyson? Zero G.
26:40 Chuck Nice? This was fun. Um, this was great.
26:44 Neil deGrasse Tyson? All right. And, and this thing with acceleration and earth's gravity, uh, the, that's called to Einstein, the equivalence principle. And it's one of the deepest, I, most brilliant ideas ever advanced in the history of physics.
26:56 Chuck Nice? The equivalence principle.
26:58 Neil deGrasse Tyson? Right. That gravitational acceleration is not only equivalent, it is indistinguishable from acceleration by rockets or anything else that would move you through space. If you did that with, in a, in a box with no windows, you would not be able to tell that. Correct.
27:16 Chuck Nice? Look at that.
27:17 Neil deGrasse Tyson? Am I on earth or am I accelerating through space at one G? You would not know.
27:23 Chuck Nice? Science. You gotta love it.
27:24 Neil deGrasse Tyson? And, and, and one last thing, the units of acceleration, that's why they have this weird construct. Okay? So the acceleration of gravity is 32 feet per second, per second. That is, those are the units. What does that mean? Per second, per second? What does that mean? And it's actually per second squared, if you did it out. What that means is for every second, you increase your speed by 32 feet per second.
27:52 Chuck Nice? Right.
27:53 Neil deGrasse Tyson? So how fast are you going after two seconds?
27:56 Chuck Nice? 64 feet.
27:57 Neil deGrasse Tyson? How fast are you going after three seconds?
27:59 Chuck Nice? 128 per second.
28:01 Neil deGrasse Tyson? No, 96.
28:02 Chuck Nice? I'm sorry, 96 feet. Oh, oh, no, it's 32, not 64.
28:05 Neil deGrasse Tyson? 32, right, right, okay.
28:06 Chuck Nice? It's just another 32.
28:07 Neil deGrasse Tyson? Oh, another 32. So for every second.
28:09 Chuck Nice? Every second, it's another 32.
28:11 Neil deGrasse Tyson? And it's, well, never stop.
28:12 Chuck Nice? Right.
28:13 Neil deGrasse Tyson? Never stop. Well, it'll stop until you hit.
28:15 Chuck Nice? Oh, wait. Now you just made me think of the expanse again. I just got something that they do in that show.
28:21 Neil deGrasse Tyson? What do they do?
28:22 Chuck Nice? When they're approaching a planet, even though they're really far away from the planet, the rockets are firing in the opposite direction.
28:30 Neil deGrasse Tyson? Yes. Yes. Yes, otherwise they'll just free fall down.
28:35 Chuck Nice? They'll free fall down.
28:36 Neil deGrasse Tyson? And they'll, and they'll crash land. So it's, so you have to, so you turn around, the rockets slow you down. That will give you an acceleration, by the way. Okay? It, it'll give you, so all of a sudden they'll have some kind of, uh, G forces operating on them, and they can take that all the way in if they want.
28:53 Chuck Nice? Yeah, but it, it, it looks weird because they're like nowhere near the planet, but yet they're still firing retro rockets. Well, yeah, cuz they've been speeding up so fast that whole way.
29:02 Neil deGrasse Tyson? Falling towards them.
29:03 Chuck Nice? Falling towards the planet. They have to do that in, in order to put on the brakes.
29:08 Neil deGrasse Tyson? In fact, one of the ideas of how to get to Mars without being zero G for nine months is you accelerate at one G halfway to Mars.
29:20 Chuck Nice? Right.
29:20 Neil deGrasse Tyson? Then you turn around and decelerate at one G to Mars. And so you're in Earth's gravity, one G, the entire trip. That's how you do that. And then you'll need the medical examiner looking at your, or whoever they are.
29:34 Chuck Nice? Something's happened to his bone density. We're not exactly sure what it is.
29:38 Neil deGrasse Tyson? Yeah, no bone density issue. Yeah.
29:52 Neil deGrasse Tyson? You've looked up at the night sky before.
29:54 Chuck Nice? I have indeed.
29:55 Neil deGrasse Tyson? All right, and, and you've been perhaps prompted from time to time to no- notice what the press with Bill as a planetary alignment of note.
30:08 Chuck Nice? There was a big one that happened that was on the news some time ago, a lo- a last year.
30:12 Neil deGrasse Tyson? Yeah, that's what I'm saying.
30:13 Chuck Nice? It was huge. Everybody was talking about it.
30:15 Neil deGrasse Tyson? Talking about it. Everybody, did you see it?
30:18 Chuck Nice? No, I didn't, to be honest.
30:19 Neil deGrasse Tyson? Okay, of course you didn't. Okay.
30:22 Chuck Nice? I will be honest, I did not see it.
30:23 Neil deGrasse Tyson? You did not see it.
30:24 Chuck Nice? They, they made a giant deal out of it, and I was like, okay.
30:27 Neil deGrasse Tyson? Okay, so if I say the planets are aligned, what would that mean to you? What do you think that means?
30:33 Chuck Nice? Well, for me, like, just the intuitive thought would be that you go out, look up, and you see a line of dots in the sky, the, like they're in, you know, in queue to come, you know, get some ice cream or something like that.
30:48 Neil deGrasse Tyson? In a line, okay.
30:48 Chuck Nice? In a line.
30:49 Neil deGrasse Tyson? Planetary alignment. Okay. So, so put a pin in there and consider the following.
30:55 Chuck Nice? Okay.
30:56 Neil deGrasse Tyson? Okay? We have the sun in the middle of. Its own star system, the solar system. And first out, we have Mercury.
31:05 Chuck Nice? Right.
31:06 Neil deGrasse Tyson? Okay. Orbits the sun. Then you have Venus. Then you have Earth. Then you have Mars. Then you have Jupiter. Then you have Saturn. And then you have Uranus and Neptune. Okay?
31:16 Chuck Nice? Right.
31:17 Neil deGrasse Tyson? You realize that all of those planets orbit the sun in about the same plane.
31:25 Chuck Nice? Right.
31:26 Neil deGrasse Tyson? Okay?
31:27 Chuck Nice? Mm hmm.
31:28 Neil deGrasse Tyson? So with like one giant pizza pie with the sun in the middle.
31:32 Chuck Nice? Okay.
31:33 Neil deGrasse Tyson? Okay.
31:33 Chuck Nice? So far, so good.
31:34 Neil deGrasse Tyson? Oh, by the way, Pluto orbits thirty degrees out of that plane. One of the many reasons why it does not belong among us.
31:43 Chuck Nice? Well, you know, because Pluto was just like, look, I've marched to the beat of my own drum.
31:48 Neil deGrasse Tyson? Okay.
31:48 Chuck Nice? Okay.
31:49 Neil deGrasse Tyson? So therefore, you are your own damn. That's your own. Pluto has his own rhythms, for sure.
31:56 Chuck Nice? Right.
31:56 Neil deGrasse Tyson? All right. So, so everybody is orbiting in the same plane, plane, geometric plane, flattened plane around the solar system. And by the way, everybody's moving in the same direction, which was a deep hint for us to tell us how the solar system formed. Okay? Like, do these planets fly in randomly? Well, if they did, then they'd have random orbits around the sun.
32:20 Chuck Nice? Right.
32:21 Neil deGrasse Tyson? And then some going forward, some going, quote, backwards. So they all go in the same direction and all in the same plane. And so it was concluded, this is now thinking that's been two, two hundred and fifty years ago, that maybe we started from a big gas cloud that collapsed into this pancake. And in that pancake, the planets formed with the sun in the middle. That gets you, everybody orbiting in the same direction and in the same plane. Okay. So now, let's go down to Earth and look up into the sky.
33:00 Neil deGrasse Tyson? Where are you going to find all the planets? Are you, are they gonna be everywhere in the sky?
33:07 Chuck Nice? No.
33:08 Neil deGrasse Tyson? No!
33:09 Chuck Nice? They're gonna be on the same plane as you are.
33:12 Neil deGrasse Tyson? Plane as we are, okay. So, not only that, at any given moment, at night, you're looking at half the sky.
33:25 Chuck Nice? Right.
33:27 Neil deGrasse Tyson? So, on average, half the stuff is gonna be in the sky when you're looking up?
33:35 Neil deGrasse Tyson? On average.
33:36 Chuck Nice? Right.
33:37 Neil deGrasse Tyson? Half the stuff, okay.
33:39 Chuck Nice? Cause we are on a ball, and so.
33:43 Neil deGrasse Tyson? You're looking one side.
33:44 Chuck Nice? One side of the ball, and you see half of what's out there.
33:48 Neil deGrasse Tyson? You see half the sky, okay?
33:50 Chuck Nice? The other side of the ball is looking at the other half of what's out there.
33:53 Neil deGrasse Tyson? Half the sky, okay, and you gotta wait till it's nighttime for them, but they see the other half, okay? All right, half the sky. So, point is, of the planets, including the moon, okay, which is also tilted a little out of the plane, but not enough to be important for this example. And the sun is in the plane, almost by definition, cause we're orbiting the sun, okay? So, the classical planets of antiquity, which are all the objects that moved against the background stars, that wandered. The Greek word for wanderer is planetis, which is where we get the word planet.
34:38 Neil deGrasse Tyson? And there were seven planets.
34:42 Neil deGrasse Tyson? The sun, the moon, Mercury, Venus, Mars, Jupiter, and Saturn. And the seven days of the week, the names we give to the seven days of the week are traceable to the gods that oversaw those days, dating back to Greek and Roman mythologies. Uh, we've also touched with Norse mythologies, so the Norse counterpart gods to the Greek and Roman gods share the same day. Okay, so Thursday is whose day?
35:17 Chuck Nice? Thor.
35:18 Neil deGrasse Tyson? Thor. Thor wheels the lightning bolt? Who in Roman legend wheels lightning bolt?
35:24 Chuck Nice? Uh, Zeus.
35:24 Neil deGrasse Tyson? Zeus? Well, Zeus is Greek.
35:26 Chuck Nice? Zeus is Greek.
35:26 Neil deGrasse Tyson? Jupiter is Roman? So, so if you look at the Romance languages, the word for Thursday is named for Jupiter. Okay? And, uh, what is it? Uh, in, in Span- no, Spanish. Um, uh, lunus martes mercuris webis. Webis, that's Ju- that's Jupiter. Okay? It's named for Jupiter. Point is, all of these objects, in any given night, are always in a line.
36:00 Neil deGrasse Tyson? Period.
36:00 Chuck Nice? Right.
36:03 Chuck Nice? So it's...
36:04 Neil deGrasse Tyson? I don't know how else to bring the news to you.
36:08 Neil deGrasse Tyson? We are in the plane of the solar system, and we're looking out, and we see other objects in the plane of the solar system. And if you take a circle, put it on its side, it's a line.
36:21 Chuck Nice? There you go. So it's, it's, it's a news story that happens every single night. Every single... Today in the news, planetary alignment once again.
36:32 Neil deGrasse Tyson? Once again. So, the way they try to bump it up is, if some planets are a little closer to each other in our sightline than at other months. Okay? So if they're a little closer, then you don't have to sort of turn your head along the line to see them. You might catch them in one glimpse. Okay, fine. Generally, that is what they want to call planetary alignments, but it leaves people thinking that planets are not aligned at any other time. Whereas they are always aligned.
37:10 Chuck Nice? Right.
37:11 Neil deGrasse Tyson? Period.
37:11 Chuck Nice? Period. Yes.
37:12 Neil deGrasse Tyson? Period.
37:14 Chuck Nice? This just it.
37:14 Neil deGrasse Tyson? And the moon is among them.
37:15 Chuck Nice? And the moon too.
37:17 Neil deGrasse Tyson? The moon is among them. So, at any given night, if you see the moon over here on the right and Venus over there on the left, make an arc between them and co- complete that arc across the sky, look for other planets on that arc.
37:31 Chuck Nice? And that, and you'll find them.
37:32 Neil deGrasse Tyson? You'll find them. You'll find them. You'll find Jupiter, Saturn. And if not that half of the night, wait till the other half of the night.
37:38 Chuck Nice? Right.
37:38 Neil deGrasse Tyson? Okay?
37:39 Chuck Nice? Hmm. Our top story tonight, once again, the planets decided to line up. For, for film at 11.
37:46 Neil deGrasse Tyson? Okay. Now, here's something else they do. They'll say, uh, the planets are aligned and this lineup will not repeat for another 150,000 years.
37:57 Chuck Nice? That's the one that happened last year that everybody was going crazy.
38:01 Neil deGrasse Tyson? So, uh, you, so you want to put that on your calendar? That's not going to repeat for another 150,000 years. Well, by the way,
38:09 Neil deGrasse Tyson? every night will not repeat.
38:11 Chuck Nice? For another 150,000 years.
38:13 Neil deGrasse Tyson? Whatever. I mean, you can calculate what the, it's, the point is, it's possible for something to be rare and completely uninteresting.
38:23 Chuck Nice? Right.
38:25 Neil deGrasse Tyson? Because every night is equally as rare.
38:28 Chuck Nice? Exactly. Hey, if we're all special, nobody's special.
38:32 Neil deGrasse Tyson? Then nobody's special.
38:34 Chuck Nice? Right.
38:35 Neil deGrasse Tyson? We knew that. We learned that from The Incredibles. Right. So, I just try to put, people say, oh, you're such a downer and I put it on, you know, on social media. Why are you such a downer? Why'd I look it up? There are other reasons to look up.
38:47 Chuck Nice? Right.
38:47 Neil deGrasse Tyson? Okay? I don't have to fake a reason for you to look up. Um, you know, the asteroid might be coming. Why don't you look up for that? All right?
38:55 Chuck Nice? No, no, don't look up.
38:56 Neil deGrasse Tyson? Really?
38:59 Neil deGrasse Tyson? I saw that documentary.
39:00 Chuck Nice? That's a, a documentary?
39:02 Neil deGrasse Tyson? Don't look up.
39:04 Chuck Nice? That's funny. That was funny.
39:06 Neil deGrasse Tyson? So that's all I gotta say about, about.
39:08 Chuck Nice? The planetary alignment.
39:10 Neil deGrasse Tyson? Planetary alignments. Yeah, just chill.
39:13 Chuck Nice? Yeah, there you go, guys. So it's BS.
39:18 Neil deGrasse Tyson? And because we're orbiting the sun, we're always getting new angles on how everybody's aligned. And it's always, it's always new and it's not going to repeat for hundreds of thousands of years. But every single day is that. So, you know, there it is. By the way, there is something called a conjunction.
39:35 Chuck Nice? Oh.
39:36 Neil deGrasse Tyson? Which sounds like you'd need ointment for it.
39:38 Chuck Nice? What's a function?
39:41 Chuck Nice? Yeah, conjunction.
39:42 Neil deGrasse Tyson? I got some ointment to fix your conjunction, alright? A conjunction is-
39:46 Chuck Nice? Make sure you wash your hands if you get a conjunction, okay?
39:49 Neil deGrasse Tyson? Conjunction is you get like, three planets, and I'll include the moon among them, as a classical planet, that wanders against the, by the way, they called them wanderers because they didn't understand the physics of gravity.
40:02 Chuck Nice? Right.
40:03 Neil deGrasse Tyson? Right? After Newton, they're not wandering at all. They know exactly what they're doing.
40:06 Chuck Nice? Exactly. We actually know where they're going.
40:08 Neil deGrasse Tyson? And so do they, right?
40:10 Chuck Nice? Right.
40:11 Neil deGrasse Tyson? So, nobody's wandering. So, so a conjunction is when you have at least three objects that are in the same part of the sky, where you can like, you know, look through binoculars and all of them are in one field of view. We call those conjunctions. Those are worth coming out to check out.
40:31 Chuck Nice? Okay, cool.
40:32 Neil deGrasse Tyson? But this notion that, of alignment, no. And it's even made it into our language, oh, uh, things are going so well, the planets must have aligned, right? It's worked its way into our culture. And, so you say, yeah, things work out for me all the time, because in fact, the planets are always aligned.
40:51 Chuck Nice? Hmm, exactly. Yeah. Also, I'm the master of my own fate, you know? I would like to thank me.
41:05 Neil deGrasse Tyson? No, no, you get the, you know, the boxer who wins and say, "Thank God."
41:08 Chuck Nice? Right.
41:09 Neil deGrasse Tyson? For, like, for the ability to pummel your other person.
41:12 Chuck Nice? Yeah.
41:12 Neil deGrasse Tyson? So, they should go to the other person and they're saying, "I blame God."
41:16 Chuck Nice? Exactly.
41:17 Neil deGrasse Tyson? If one gets a "thank God."
41:18 Chuck Nice? God hates me.
41:20 Neil deGrasse Tyson? Somebody else want to get to blame God.
41:22 Chuck Nice? Yeah, "I lost because God hates me, okay? It's that simple." "If God liked me, I wouldn't be here right now."
41:29 Neil deGrasse Tyson? Yeah. All right. We gotta call it quits there on StarTalk's Things You Thought You Knew Edition. Chuck, always good to have you. I'm Neil deGrasse Tyson, your personal astrophysicist. As always, I bid you to keep looking up.
Previous Will AI Replace Us? with Matt Ginsberg Next Things You Thought You Knew – What is Energy? Page updated September 29, 2026 · transcript and summary are machine-generated
