Earth’s Tilt Makes Time Slippery

0:01Welcome to the Rest of Science. I'm Hannah Fry. And I am Michael Stevens. And today, I want to talk about sundials and why they are so bad. What did you say? I said, yes, please. Well, good. That's good. I'm glad. I'm glad. I just heard something come out of your mouth. I was staring at the camera for dramatic effect and I thought, oh my gosh, comments from the peanut gallery already. Should we take opposing positions on sundials for comedic effect throughout the course of this episode? Yeah. Do you want to be pro or against? Oh, I'm definitely pro. Okay. I'll be against. Boy, having to be anti-sundial is a very strange position for me to take as someone who loves sundials, but I've always been disappointed in them

0:45because they never agree with my watch or my phone. You'll find them in parks or public places or private residences, and they're beautiful. They're often like so cool. And I want them to be so powerful. And yet when I really look at it and I say, oh, okay, so it's, it's 1211. And I look and it's actually like 1225. And I'm like, oh, well, you know, is this just not set up right? And they're like, no, it's set up by like a expert sundial crafter and astronomer. And, and I'm like, well, why is it not, not right? And they're like, well, why is it not right? And they're like, well, what does it mean to be right? What time is it really? And I'm like, well, why doesn't it agree with the time on my phone, the time that we

1:35live our lives by, civil time? And the answer is the equation of time. And it's something that I have not been able to, I think, explain or even understand myself clearly enough. I might be getting close. And so I wanted to kind of talk through it today, because it has a lot to say about the way we live in society today and what the earth actually does. This episode is brought to you by Cancer Research UK. All right, here's something really cool. The earliest written description of cancer that we've ever found is from an ancient Egyptian papyrus that was around before even Cleopatra was on the throne. It described tumors being removed by a tool that they called the fire drill, which we think was used to burn off diseased tissue.

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4:42Serious allergic reactions, increased risk of infections or lower ability to fight them, and liver problems may occur. Before treatment, get checked for infections and tuberculosis. Tell your doctor if you have an infection, flu-like symptoms, or need a vaccine. Explore what's possible. Ask your doctor about Tramfiya today. Call 1-800-526-7736 to learn more or visit Tramfiaradio.com. So, you know, we've done an episode on time and how we keep time. I think it's called something like, What Day Is It Really? And you guys should go listen to that one after this. I won't be repeating much information at all from that older episode. But today I wanted to talk about the problem that happens with a sundial. So first

5:30of all, what is a sundial trying to do? It's trying to do what people did for most of human history, which is get a sense of when it was by looking at where the sun is or isn't. And one way, a way that we know that people did in very ancient times was to say, well, the day begins when the sun comes up. Like, that's even how a lot of people think of it today. Having to explain to my daughter, well, actually, the day begins at midnight. She's like, what the heck? Why doesn't it begin when the sun comes up? It's also confusing to say, well, you know, days are shorter in the winter for us. And she's like, yeah, that makes sense. And I'm like, oh, by the way, they're not actually shorter civilly.

6:14It's still midnight to midnight, but the sun is up for longer. And that used to be what a day was. Aye, aye, aye. Except they still a while shorter. Yeah, exactly. It winds up being a really uneven way to measure a day. If you just say from sunrise to sunset in the winter, days are like really short. And then in the summer, they're really long. And if you try to build any kind of clock, any kind of mechanism that's regularly doing something, say dropping sand from the top to the bottom or drops of water, it just winds up not dropping the same amount day to day because the days are getting longer and shorter throughout the year. And a slightly less messy way to measure the day came about a little bit later in our

7:07history, but still in ancient times. And it was the concept of a solar day. Okay. Instead of focusing on when the sun rose and set, you focus on how long, how much time passes between when the sun is at its highest point in the sky to when it's back at its highest point in the sky? That's noon to noon. Right. And that is a lot less variable. In the winter, the sun is, you know, rising a lot later, but it's reaching its highest point with a little less variability. But it still varies. And that's the problem. That's the heart of this problem. Sundials are set around solar time. And solar time from noon to noon is still just not always the same throughout the year. When I first read about that, I was pretty blown away.

7:59I think it just never occurred to me that this whole phrase, meantime, was saying, oh, you need to find an average across the course of the year because there's a variation, right? It was wild to me that I just never made that connection. Wild to me that the length of noon to noon could actually be different across the course of the year. But then of course it is, it's a wobbly rock in space. It's a wobbly rock in space and it's not going around the sun in a perfect circle at the same speed all the time. Funny enough for us in the Northern hemisphere in the winter, the earth is a bit closer to the sun. So it's moving faster. It's speeding around, trying to finish its lap, its yearly lap faster in our winter

8:49in the Southern Hemisphere's summer. So January is like when we're closest to the sun. A sundial uses shadows cast by what's called a gnomon. And that shadow falls on the face of the dial and the shadow should point at what time it is. And the way you set up a sundial is that you say, okay, I want the shortest shadow it ever casts to be at noon. Because noon is when the sun is highest in the sky, shadows are the shortest. So that's noon. You run into all kinds of problems, of course, besides just the wobbly rock that we live on when you try to measure time this way. You also, of course, run into the problem of where are we measuring this? Because when the sun is really at its maximum peak, its highest point in the sky for me, it's not in the highest point for someone who is a thousand kilometers west of me.

9:45That wasn't really a problem until we invented railroads and we could suddenly move across the earth so quickly that we were like, oh, shoot, wait a second. I'm hungry, but it's not lunchtime yet. Oh, oh, that's right. I've gone around the curve of the earth. The I'm finding the sun later. I'm leaving the earth's shadow later. Wait, can I ask you some questions? Yes. How much does the length of a day change across a year? How much are we talking here? Are we talking minutes? Are we talking seconds? What's the variation? We're talking minutes. So a sundial is going to run as much as 16 minutes ahead in November, compared to civil time, which is we're trying to keep time really regularly. In November, a sundial is going to wind up being fast.

10:40It's going to be ahead of what our clock times say, like our civil clocks that are built to be really regular. The sundial will be 16 minutes faster than the timekeepers are trying to be regular. And then in February, they're about 14 minutes slower. So that doesn't mean, just to be clear about this, because I think I've made this mistake in the past, that doesn't mean that a day in February is 14 minutes longer, shorter, whatever. Because it's just cumulative. If you're down by a few seconds every day, the clock runs slower, and then it turns around and comes back. That's right. Yeah. So it accumulates this difference between the behavior of the sun and our regular clocks that are trying to like every second is the same length and there should be a certain number of them per day.

11:29Those fall off and then they catch back up and then now we're too far ahead. Now we're too far behind. And this happens every single year. And it happens for two reasons. Now, first of all, if the Earth was not tilted and the Sun was just always over the equator, directly overhead at the equator, and the Earth orbited the Sun in a perfect circle, there would never be any disparity. We really could use an atomic clock to predict and count the same number of ticks between noon and noon everywhere on earth. It would be really easy, but that's not the world that we live in. Instead... Hold on, hold on, hold on, hold on. I want to stress test this because you just said an atomic clock. I mean, surely there's also like energy loss, right?

12:29So over millennia, longer, millions of years, you would end up getting some slippage. Yes. Okay. That's a very good point. in, I wasn't factoring in the really small variabilities caused by changes in Earth's rotation or its orbit because of, you know, the mass of Jupiter out there. There is variability. There's a wobble to Earth's orbit. I'm imagining a perfect, precise model where the Earth is spinning at the same speed around the sun in a perfect circle at the same speed okay the the plane of earth's orbit exactly intersects right through the equator okay that that's the world where atomic clock time and astronomical time are the same just as a side note it is slowing down because you can tell

13:20by looking at fossilized coral oh so and i'd love this so much but basically coral is i mean it's a living organism and it and it puts down layers every single day and you can see if you look at microscopically you can see the fluctuations that happen in these layers as you go from day to night but also across the seasons so you can go back to coral that's like millions of years old and you can see in it that there used to be more days per year than there currently is. Ah, so the days were shorter. Days were shorter, more of them quicker spin. So the earth is slowing down. Anyway, but that's fine. We'll ignore that. For the purposes of this, we'll ignore that. We're going to ignore it just to focus on what's causing the majority of this regular

14:11swinging back and forth of the sundial versus the civil clock. But I do love that we can do that. And now that you bring that up, I remember, I think I even talked about this before, that days used to be different and the moon used to be closer. I mean, man, if you could go back 2 billion years and walk around on earth, it would be a whole nother planet. You know, it really was. And it reminds me too, that we can look at other evidence like that. For example, there are fish, there were ancient fish, Their bones grew seasonally. And so we can look at their bones and figure out when in the year they died. And that's how we were able to pinpoint the impact of the Chicxulub meteor, the one that eventually led to the extinction of the dinosaurs, to within, you know, 65 million years ago, plus or minus a bunch. But we know what happened in the spring. We know less about what year that hit than the season.

15:13I love that. I love that so much. The solar system is a mess. It's not perfect. If you wanted to set a watch by it, good luck. Actually- You're going to be late for your meeting. You're going to be late for your meetings. But is that the fault of the solar system or the fault of us for trying to invent the way we think time should go? Well, we'll get to that later. But basically, if you try to measure a day, a solar day, by clocking when the sun is at its highest point in the sky to when it's next at its highest point in the sky, what you're doing is you're measuring time by saying, when is my meridian pointed at the sun and when is it pointed at the sun again? A meridian is an imaginary line

15:56that you are on right now, your own personal meridian. And it's a line that stretches from the North Pole to the South Pole and goes through you. And when that line points at the sun, it is noon for you right where you are. Someone who is a mile west of you isn't quite experiencing noon yet. Earth is going to still turn a little bit for them, and the sun is going to appear to be a little higher in the sky later for them. But for you, it's going to be just going down after that point. The sundial works off of that principle. So if I put a sundial in Colorado and I put one in Utah, they're not going to have short shadows. They're not going to show noon simultaneously. All right. That's pretty easy to understand.

16:42Which is also good though, you know, it's not good if you're running trains. Sure. But it is sort of more connected to the world you actually live in. Exactly. It's not embodied, but it's in earthed, you know, you're getting time as it's given to you by major features of your environment. So we've got Earth. Imagine your meridian line from the North Pole to the South Pole passing through you. It's pointed directly at the sun, all right? Now, that doesn't mean that the sun's right overhead. We're going to get to that later. But it doesn't mean that the sun's the highest. It'll be in the sky that day. Now, in order for another day to start, you need to go all the way around and point your meridian back at the sun.

17:30Now, Earth's rotation is pretty darn constant. There isn't a lot slowing it down. It's certainly not being slowed down by friction with outer space. There are things that affect it, as we've just mentioned. But a much bigger cause of the discrepancy in that being regular is the fact that the Earth is also orbiting the sun. In the time it takes the Earth to turn around once around its own axis, it's already moved about a 365th of its orbit around the sun. Okay? I see where you're going with this. See where I'm going with this. And this is where it really helps to do some experiments with like a globe or a ball in your hand at home. But to kind of give us some context here, the earth turns so that the West chases the East. I always think

18:19of it as the United States, the shape of the U S is kind of like an animal where Florida is a leg and, and Texas is the other leg and Maine is like the head. And it's just it's running forward. OK, so the West is chasing the East. So if you were to look down at the North Pole, the Earth is turning counterclockwise. Mm hmm. And it's also orbiting the sun counterclockwise. OK, it's good to remember that. So we see it in movies. You can always be like, Ooh, that's right. Or, Ooh, they did that wrong. Anyway. Anyway, what happens is that in order for the day to end, you are sort of like trying to move east to catch up with where you were the day before with this, with your meridian pointing at the sun. But if you have moved a little bit, by the time you've turned 360 degrees,

19:08the sun isn't right in front of you anymore. The sun is now a little bit behind because you've moved. So you basically have to go, so just to copy your thing. So if I was right here every single time, it'd be like, okay, and bam. But actually, I've sort of moved this way that's right while turning you turn 360 degrees and now you're not pointed back at us again you've got an average of four more minutes of rotation every day that you have to do to complete and point back at the sun now the the very distant stars move a lot less, okay, as Earth orbits, right? And so that day, which is called the sidereal day, it is a lot more constant, okay? The sidereal day, funny enough, I was like, what's the etymology of sidereal? And it comes from Latin side or sitis, which meant stars. And it's possible that words like consider

20:08come from the same root word. So when you consider something, originally you were with the stars, sitis, sidereal, consider. You're with the stars. So there's this theory that the word consider may have come from navigation. That originally, when you tried to figure out where to go, you would look at the stars. And when you tried to figure out where to go and what decisions to make in life, you would also look to the stars for answers. You would consider them. Now, that's not totally proven. There's also a theory that the word consider comes from stretch or length, which is like where the word side comes from. So considering maybe just like looking at the whole thing. But I love that there might have been this time in human history where we gradually started to think on our own more,

21:14feel a little bit less guided by either voices in our heads or instinct or ancestors or feelings. And we did a lot more internal interior cognition. And so we just kind of took the same word for being guided by something outside of us and made it what it's like to think for yourself. Consider with the stars, consider in my own head by myself. But that makes a lot of sense though, why people would navigate with the stars stars the fact that they're so much further away this extra effect because i mean i always thought it was like why are you using the stars you know if it's cloudy if it's like bad weather you've got no hope whereas the sun good luck missing the sun you know exactly where it is even on a cloudy day and this is like crazy cloudy But you've got a much better chance of like working out where the sun is.

22:07But that's the reason why they would navigate by the stars, because you just end up with, I guess, a more accurate sense of when it is and thus where you are. Yeah. I mean, people figured out that, yeah, the sun is different, but like we can still find regularities in it and tell the time, the solar time. But, okay, so we understand that the Earth has to rotate 360 degrees around for there to be a day. And then an additional four more minutes of rotation for there to have been a solar day. But that's still just, you know, if it's just four minutes every day, then that's still a regular amount. It's the same amount every day. The reason it's not is twofold. One is that Earth's orbit is eccentric, okay?

22:58It's a bit of an ellipse. Instead of just going regularly at one speed around the sun, it kind of whips and goes far away and comes back in and whips again and whips again. So in the winter, when we're speed around the sun, it goes, it kind of whips and goes far away and comes back in and whips again and whips again. So in the winter, when we're closer to the sun, Northern Hemisphere winter in January, we are moving faster around the sun and we're closer to it, which means there's more rotation, more duration of rotating the earth has to do for the solar day to end and for a new one to begin. So there's that variation. There's another variation that's really hard to visualize, but the way I'm gonna recommend doing it

23:34is to just imagine that someone is holding a rod horizontally in front of you, okay? It's parallel to the ground, okay? And this person is doing what you just did in your chair. They're spinning around on their own axis. I've got a straw hung on. Okay. Get a straw. It's a long pink straw. So hold that horizontal, perfectly horizontal. And we're going to imagine that that's the equator. Okay. And we're going to imagine that we, the viewers looking at you are the sun, you're the earth. And we're looking at that equator. Now, if you turn all the way around your own axis. I'm the earth, yeah? You're the earth. So turn, yep. And now you've come back. A solar day is done. But now do it and orbit us a little bit.

24:19Okay. All right, okay. Here we go. This is really good, by the way. We did not reverse this. Okay. Now you got to turn a little bit more. Okay. So as you can see, as she orbited us, she kind of dragged the old noon point to our left. Okay. So that point was dragged actually like exactly just, it was just dragged along that equator line. So she had to make up all of that time. She had to rotate to make up for that eastward shift. But in the spring and fall, the earth's tilt makes it so that the equator isn't pointing right at the sun. It's tilted. Okay. So the Earth's orbit drags that equator or that sub-solar point at noon, not just directly east, but instead northeast or southeast. Of course. Of course. Okay. So let's say that

25:26you've got the middle point at that. Should I do it? Yeah. So now go ahead and rotate with this tilted equator. Okay. So now it's like... Yep. There you go. This is how I expected my life to turn out, Michael. Okay. And now the point that needs to come back to me has just shifted kind of not just to what would be your West, but a little bit North or South. And so I don't have as much rotation to the East to do, or you don't, in order for the day to complete. Okay. Now those two things combine to cause the length of the solar day to be variable in a really messy way. So if you ever find a really good sundial, it'll probably have a plaque next to it that has a graph that's got months and days of the year and then a number of minutes to add or subtract. And then it'll have a little curve,

26:25not a regular curve, but some kind of thing that goes up and then it comes down a lot and then up a little bit. It's a mess. That's showing you the combined effect of Earth's eccentric orbit and its axial tilt on the length of the solar day. So when you look at the sundial and it says, yep, it's noon right now, you need to look at that equation of time plaque and it'll say, oh, okay, well, if it's July 8th, then you need to add or subtract this many minutes to what the sundial says to match what civil mean time is. And that number is going to be different every day. The time it takes from noon to noon on a sundial is sometimes a little bit shorter than average, sometimes a little bit longer than average.

27:11And the equation of time allows us to correct the sundial so that it matches what our regular beating mechanical clocks on Earth say the time should be. So I was always sort of disappointed in this, not only because it meant that a sundial was off by either 16 minutes ahead or 14 behind throughout the year, but it also was so hard to visualize in my mind why it was happening. But I dedicated myself to it, and I've made a few videos about it and now I've talked about it on a podcast but what I want to show you is the Schmoyer sundial oh yeah this is a sundial that was invented by Richard Schmoyer back in 1958 and he called it the SunQuest sundial and this is it or at least this is a version of it.

28:09Right. Okay. We should describe, we should describe for people who are listening here. So what Michael is holding up, it's almost like two horseshoes that are attached perpendicular to one another, almost as though you took a globe and you cut out all of the volume of the earth and just left a line along the longitude and one along the latitude that meet in a particular way. And then through the middle of the earth, it's got a little pin and attached to it is what can only be described as a plastic bit of bacon. Yes, yes. Bacon is a really great description for this because it's a wavy piece of plastic. And so this gnomon is what you're describing. It's what casts, well, it does cast a shadow, but we'll get more to that later. It's wavy so that

28:53the way light passes through it is sometimes a little bit later and sometimes a little bit earlier, depending on the time of year. And also, instead of casting a shadow, this casts a ray of light onto the time because there's a slit in that piece of bacon in the gnomon and the sun passes through this. And as you can see, if I turn it, that strip is like almost an S shape. And so sometimes the sunlight will come through it early because we're at the back of the S and sometimes it's going to take the sun a little longer to line up with the part of the S that's forward. So depending on the time of the year, this will either cast the sun's shadow a little bit sooner or a little bit later and that curve is exactly what's called the analemma

29:43which means that this corrects for the equation of time automatically. No. Yeah. No, that's amazing. The tradeoff is that you have to adjust this nomen every time you want to check the time. You can't just sit there and you come and look at the shadow or the ray of light. You have to point this nomen towards the sun and create as narrow of a beam of light, you have to point this gnomon towards the sun and create as narrow of a beam of light as you can. And when it gets really narrow, that's the correct time. And it will be the time, when I say correct time, I mean, it will be the time that your phone connected to the grid says it is. Hang on, hang on. Could you not do some elaborate thing where you attach attach it to

30:26like a full-cut pendulum or something that changes according to the rotation of the earth so there's like some automatic way but that uses sort of you know like mechanics rather than electronics well sure yeah i mean you could you could create a model of the Earth and Sun system and build the correction in that way. When you're twisting it, you're twisting it based on basically the time of day rather than the time of the year or anything. Yes. You're twisting it so that you only capture sunlight through a very narrow slit. And that slit, depending on how high up the sun is, is either going to be part of the slit that's more like east or more west because it's like this S-shaped slit. And the amount of curve in that slit is exactly lined up to correct for the equation of time.

31:20So when was this invented? In the late 50s. It's amazing. I love it. Yeah, it's amazing. And I just love it because you really could make all of your Zoom calls and get your kids to school at the right time by using the sun if this was your sundial. And it was. That's why, if you look, this one that I'm holding, it's pretty like brown. It used to be a nice clean gray, but this has just been outside telling us time every day. Yeah. You have it in your house, in your garden. Well, I did in Los Angeles. I now live in Colorado. So to be, and some of, some of you eagle eyed viewers may have already noticed that I have this set for a location in Los Angeles, not in Colorado. I have not set this outside here in Colorado. One problem is that we

32:06don't have as much direct sun here. We've got a lot more tree cover where we live. So I wouldn't actually be able to tell time very well with this most of the time. But in LA, we had direct sun all day. Every day, maybe. Part of our yard. So that was a perfect solar timekeeping corner of the yard. I love this. And I loved it so much that we, me and the Curiosity Box team reached out to the North American Sundial Society and said, can you get a hold of Richard Schmoyer? And they were like, no, he's deceased. But we got a hold of his family. And we said, we want to make these. And so I'm holding one that we made. We licensed the design from them. And we said, is there anything that you would like us to add? And they were like,

32:50yes, we want it to work in both the Northern and Southern hemisphere. So we did that. And you'll notice that you can actually take this apart and this Northern hemisphere can be switched over so that the Southern hemisphere is on top. You just turn this piece over and now you can use it Let's switch it. Oh, yeah. we sent this out to our subscribers, we got a message from the North American Sundial Society saying, whoa, you know what? You guys just became the largest single maker of sundials in human history. Yeah. So the woman who reached out to us was the vice president of the North American Sundial Society, Tahisha Way. And she said, look, the single entity that made the most sundials in history was probably a painter who went around and painted

33:53sundials on people's homes and then stuck a gnomon in. So, you know, you've got like, oh, the shadow kind of tells you the time. But she was like, in a lifetime, these painters at most would have made like 5,000. But we made more than 20,000 of these. Amazing. Now, I don't know how to feel about that because I feel like there's got to be some company in China that's made a whole bunch of like cheap, you know, sundial pendants or something. But in terms of sundials that are really able to tell you the time and were built for that purpose with a lot of thought behind them. I think claim it. Look, honestly, I think claim it. Claim it. Claim it. That's good. I think you deserve a plaque on the wall.

34:34A plaque on the wall with a shadow that's cast. Yeah. Maybe you should do it like Indiana Jones, where the plaque on the wall doesn't tell you anything until it's exactly noon. And at that moment in time, you can see that you hold the record. There you go. I love that. I love those kinds of things. And we're going to talk about some things like that after the break, when we dive a little deeper into this sub-solar point. Shaq here. What's it like to buy a car from Carvana 100% online and get it delivered to your door? Let me tell you. Your car is here, Mr. Shaq. Thank you, Mr. Carvana guy. Can't wait to take it for a spin. Only the best for you, Mr. Shaq. Hey, have you always been so big, tall, and handsome?

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36:08I got you. Serum moisturizer or moisturizer serum. Let's get into layering. My concealer is making me look worse. Sounds like the wrong shade. Let's get you matched. There's only one store that really gets what you're going for. Get beauty from people who get beauty. Only at Sephora. Hi, I, uh... Let's get you a basket. Okay, welcome back. So we've been talking about solar time, which is reckoned by the subsolar point. I think it's been pretty clear but the subsolar point is the point on earth directly underneath the Sun and when that point hits your meridian boom it's solar noon. Anyway, what I've always loved about the subsolar point is that sometimes you can be at it meaning the Sun is at the zenith which is the point of the sky directly

37:07above your head, meaning the sun is right above you. And this is only possible in tropical and subtropical regions on earth. So it's never going to happen for me in Colorado or you in London. The sun will never be directly above your head because of the way- Are we talking here, we're talking about essentially a place where at midday there are literally no shadows? Exactly. Okay. Yeah. Or, I mean, there are shadows, but they go directly down. They project directly down from the object to the ground. So if you have something like a bollard in the ground that has vertical sides, it casts no shadow at all. Even in direct sunlight, it's just lit all over because its shadow is falling directly below itself

37:51where its base is. And so everything looks weird. If you haven't seen photos of the world when the sun is directly overhead, look them up because it looks fake. It looks like everything's photoshopped in. You know, there's just, they're not casting shadows. Obviously like a car will have a visible shadow because you can look underneath the car, but the car's shadow is the exactly the size of the car right below it. And a person stands there and they've got maybe a little tiny shadow around their feet from their body or where their nose pokes out. But it's really trippy. Have you ever seen it? I've never seen it in person. I've never been in the right place at the right time. You know what we need to do? We need to go

38:34and do we need to rest, rest to science tour to go. Yeah, we do. And you know what, unlike trying to find a good place on Earth's surface for an eclipse, directly overhead sun is happening all the time. I mean, in fact, there's a really cool subsolar point website. We'll put this in the description, rl.se slash subsolar point. And the subsolar point right now is, drumroll please, it is just off the coast of South America. Okay, so it's just a little... Yeah, we'll get on a boat. Okay, so right now, it's only, I'd say, a few hundred, maybe 500 miles southeast of the Galapagos Islands. And I love to look at this website every now and then and be like, oh yeah's who's directly under the sun right now?

39:26The only place in the United States where the sun is ever directly overhead is in Hawaii. And they have a name for the event of of the shadows disappearing. They call it Lahaina noon. Lahaina means cruel sun. La means sun or day and Haina means cruel. So it's called the cruel sun. Interestingly, that's not the traditional name. That name was come up within, I think like the 80s or 90s by a university. The traditional name that the Hawaiian native people gave the sun being right above them was Kaukala'i Kalolo. And that means the sun is resting on its brains. I don't know what they meant by that. I looked through a Hawaiian dictionary to figure out like, what do they mean by the sun resting on its brains? And I still don't know. If anyone can help, let me know. But I love that.

40:31It's a longer thing to say. So I've just looked up a map of America, and I don't think I'd realize this until now, but Hawaii is further south than every other point, including Florida, which is why they're the only place that gets it, right? That's right. That's right. And I think that a lot of me, I'm speaking for myself here, when I was younger, I thought Hawaii was more like off the coast of California because that's the way maps would do it. They'd be like, oh, and then we're going to put Hawaii over here. But really, it's off the coast of Mexico. It's down south. I've loved Lahaina Noon for as long as I ever knew about the concept. In Hawaii, there's a sculpture made by Osamu Noguchi called Skygate. And it is a wavy loop that rests on, I think, three supports. It looks like a silly band bracelet, you know,

41:26that's parallel to the ground. And every day, the shadow cast by it is this goofy circular, it's this goofy, wavy loop, except during Lahaina noon, where its projection onto the ground is a perfect circle. Yeah. Don't. I love it. Oh my Lord, I love it. And I've been to it at a time when its shadow was a wavy, loopy, inflatable tube man. But on Lahaina Noon, it's a perfect circle. And one of my dreams is to be there and witness that when it happens. You only have a few minutes to experience Lahaina Noon. Okay, I was home alone in Los Angeles one night. And I looked outside and there was a full moon. So it was quite bright. The sky was clear. And I was kind of freaked out. And I couldn't place why everything looked so weird until I realized that the moon was almost directly

42:26overhead. And so- It's a Lahaina midnight. A Lahaina midnight, right? That's what I was like, oh my gosh, I've never heard of this. So I took a bunch of photos and I took a croquet stick and shoved it in the ground to try to capture it with no shadow. Because of course, everything else outside, like lawn chairs and stuff, they did have shadows. They were just directly underneath. But underneath, right. Yeah. I wanted to put things out that would have no shadow and it didn't quite happen. I waited around. The shadow was a little, a little bit off center. So they had little tiny moon shadows. And I just kept waiting, hoping that like the moon would keep getting closer and hit the center. And it never did. But Lahaina Midnight

43:11was the name that I thought of first for that. But it's not quite the right name because what's happening isn't midnight. The sun isn't on the opposite side of the earth as me. It's Lahaina moon. Yeah. Lahaina moon, but Lahaina moon would mean cruel sun moon, which maybe isn't that off. But just a few weeks ago, I revisited this and I looked at what Lahaina noon meant. And I saw that la means sun,ina means cruel. And I said, well, what is Hawaiian for moon? And Hawaiian for moon is mahina. So let me just make sure I've got this right. So cruel moon would be mahina heina. And that is when the moon is directly above you. Now, unfortunately, it doesn't happen in the UK. You guys are too far north for the moon to ever be at the zenith.

44:16The highest the moon ever gets in the sky for London is 67.1 degrees above the horizon, not a full 90. And that happens only once every about 18.6 years. So the next one- So sorry, you're gonna have to go south. The next one won't happen until 2043. Do you know what? Seriously, too far south for the Northern Lights, too far north for the excellent solar events like this, which is worth the point in being here. Well, I know. That's how I feel too. I have a funny thing though. Did you guys notice anything interesting on October 2nd? No, tell me. You didn't notice that the moon was at 66.8 degrees above the horizon in London. Do you know what? Yeah, actually it passed me by, I'm sorry. It was at 5.32

45:03in the morning, you didn't notice? Okay. No, I think I was sleeping. All right. Well, 66.8 degrees is just shy, just three tenths of a degree shy of the highest it can ever get in London. So it's a special, special moment. Right. Okay. Yeah. I mean, that does feel pretty special. Have you come across Henry Segerman? Yes. I've met him a number of times he's fantastic he's so great so what he does he prints these shapes uh sort of mathematical 3d printing and one of them i got for a friend for a wedding present they were these uh candle holders and they're basically they're sort of like wrapped up um in this globe and it's all you know got these like little spokes on it but when you when you view it overhead uh from with a single light source centrally above it the shadow flattens out

45:56on the surface below to be to make this perfect rectangular grid it's like it's the most glorious thing oh man i, I didn't know that he made candle holders. What a brilliant idea. Maybe it wasn't a candle holder originally. And I just, but that's what you did with it. I've seen him do that. Let's do that with a flashlight. He puts inside them, but yeah, just put a candle inside. If you'll humor me for 20 seconds. I'll find his book and we can show them. I'm back. Did you get it? I couldn't find it. I think it might be at home with my art books because it's hard to place him sometimes. Right, totally. He's a mathematician, but he's also an artist. I found my Sundials book, so, you know, it wasn't a total loss.

46:43But yeah, I love his work. On the note of like, the wasn't a total loss. But yeah, I love his work. On the note of like the moon is sometimes directly overhead, it made me remember the silliest thing. This guy Artem that I work with at the Curiosity Box, he loved our Uranus, Sworch Child Radius shirt so much. He got really obsessed with Uranus and now it sounds like your anus. And he built a calculator that will calculate when Uranus will be closest to you in the next number of however many years you want to put in. I don't even know what to say. Like, I'll send you the link. We can put it in the description if anyone wants to calculate. But you just type in your exact coordinates on Earth, including your altitude, and it

47:22spits out when in the next however many years you want it to look for when uranus will be closest to you and i was like oh cool man um oh hang on you've got to know your exact latitude and longitude yeah i'm just gonna do london you guys you can just tap london okay look i'll tell you what we're basically it's super duper close right now. Well, you're only searching within a year. So by default. But it's the closest it'll be all year. Right now. I feel very lucky. Oh, yeah. I think maybe that's why we're talking about this. It's the Uranus influence. It's on our minds, literally closer to our minds than it's been all year. Absolutely. Hang on, let me look at California. Because surely it doesn't actually matter that much what part of the world you're in.

48:12I mean, a bit, but we're talking about much bigger distances than the radius of the Earth, right? But I think that where you are in the world will change the closest approach by, you know, up to half a day. Okay, I agree. I agree. And then based on your elevation by, you know, up to half a day. Okay. Agree. Agree. And then based on your elevation by a few seconds, maybe. Yes, you're right. And it also, he's giving it, he's giving it to the nearest kilometer. So, um, yeah. Although the overall curve about how close and far away is, look guys, right now it's really close. Okay. So if you want to, if you want to get out there, do Uranus spotting,ting, this is the time. Yeah, I think it probably doesn't look that much different in a telescope.

48:50Maybe there's some mystic way in which its proximity affects our Uranus glands or something. I don't know. But anyway, he did it. He made the calculator and it's the only one on the internet so far that I've ever found. So thanks, Artem. There's the shout out. Now I've given the world knowledge about your creation. While we're just covering wild stuff, I learned this in my research on this topic. The Pacific Ocean is so big, it contains its own antipode, meaning there are two points in the Atlantic Ocean that are on opposite sides of the earth and they're still the same ocean. Yeah. Where, where are these two points? Good question. The first one is just in the armpit of South America. Okay. So just maybe, um, like a few

49:40hundred kilometers off the coast of Chile and Peru where, where they, where they border each other. And if you were to dig a hole there under the ocean through the center of Chile and Peru, where they border each other. And if you were to dig a hole there under the ocean through the center of the earth, and you came out on the other side, digging a straight line hole, you'd come out in the Gulf of Tonkin. Which is where? Well, just off the coast of Vietnam. Right. In the South China Sea. It's between Vietnam and the Chinese province of Hainan. Which is the same distance as here to New Zealand. I mean, if you're in London. Yeah, more or less. I think New Zealand's true antipode is like in Spain.

50:14But yeah, like Spain and New Zealand, Europe and New Zealand, antipodal. But also the Pacific Ocean and the Pacific Ocean, antipodal. Wow. That's incredible. I knew it was big. I knew that there's a water hemisphere on Earth where you can look at the Earth and see nothing but ocean, the Pacific Ocean. But that's so large that there are two points on it that are on opposite sides. You float a piece of bread just in the armpit of South America, you float one in the Gulf of Tonkin, you've made an Earth sandwich that's really wet. Yeah. Yeah, my daughter was saying the other day about how she had learned this fact that the earth is 70% water on the surface of it. Yeah. And I was like, you know what?

51:00You're right. 30% land. It really isn't very much, is it? It's really not very much. No, it's not very much. Have you seen the map of the world, but from the perspective of the ocean? Oh, yeah. The map of the world if you were a fish. Yeah, it's like the fish's map of the world. You've got these borders and then mysterious, we don't know what's there for the land. But it's cool because usually we're happy to cut the oceans up when we make map projections but for the fish they would just cut up the land because who cares they want the ocean yeah and you realize that we just have this one big global ocean and there happen to be some islands in it but we give them different names we say well that's the atlantic and that's the indian ocean it's like well where's the line

51:44between them because it looks like a whole bunch of water the whole way. Tell you what, though, sundials would be useless on Lahaina noon, wouldn't they? That's right. They would cast no shadow. The gnomon would just, well, there'd be no shadow on it. You'd be like, well, you'd say, I don't know what time it is. So it's probably Lahaina noon. It must be that once every year noon. But you know what? Everyone's going to be late that day. No one's going to have any idea. Well, yeah, because as soon as it's like 15 past noon, the shadow that the gnomon creates is going to be just like a little splodge. It's going to barely reach any numbers. No one's going to know. It's going to be a huge mess.

52:19It's a disaster. Thank goodness we don't experience it where we live. Thank goodness. Do you know what? Suddenly I take it all back. This northern latitude, I'm fine with it after all. Look, maybe that's why we got so much done. Everyone was on time. Yeah, they had to make clocks because the sun was just too variable. I mean, we can't also see the sun here. So there's also that. But separate points, separate points. Too grey and cloudy. But don't worry about that right well i think we've i think we've learned a lot this episode um we've learned well i'm certainly very anti-sundial now if i'm honest with you i've completely changed we started with that but we didn't really end anywhere i mean

52:56i ended with sundials i was kind of against them but i think that they can be made to work except there's one other problem we haven't discussed, and that is clouds and Earth's shadow, also known as nighttime. Whoops. There are lunar sundials, lunar dials. But again, they only work when the moon is bright enough and there aren't clouds in the sky. And the moon is up, right? I mean, the moon doesn't just come up because the sun's down. It's up all the time when it wants to. And so, you know, sometimes you got to just live by feel. What time does it feel like? You know, don't let other people tell you what time it is. The earth's telling you one thing, society's telling you another. You can only rely on yourself.

53:41You know what? This is all, it's all nonsense. It's all, everything is nonsense apart from this from this podcast so thanks for listening we will be back later this week with an episode of field notes until then goodbye aloha We'll be right back. a Hogwarts superfan cousin? The Harry Potter 25th Anniversary Collection. New and exclusive scents for your beauty-obsessed bestie? Now that's just the thing. Target's got all the gifts, so you can gift it your all. Restrictions apply. What's the secret to being a great host this season? Keeping things deliciously simple, like mixing Simply Cranberry into a festive drink as guests arrive, or serving up a warm mug of Simply Apple on a chilly night. That means less time behind the scenes and more time in the moment with everyone.

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