Daniel and Kelly’s Extraordinary Universe - Could the Earth be at the center of the solar system?

Episode Date: June 4, 2026

Daniel and Kelly explain the bizarre Tychonic model of the solar system, which for centuries stood as a valid theory alongside the Copernican model.See omnystudio.com/listener for privacy information.

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Listen to Saigon on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. When and how did we learn that the sun is at the center of the solar system? And if distance and location are just relative, what does center mean anyway? There's a commonly told story about all of this, how Copernicus and Kepler overthrew geocentrism with better data and clever math. but as usual, that story is missing a lot of the fun nuance. Did you know that it wasn't just geocentrism versus heliocentrism, but that there was a third even weirder theory in the mix that also explained the data very nicely? And that it was shockingly recently that we were able to nail any of this down?

Understanding the true history of science is super fun because it shows you how puzzles are actually sorted out and how things seem obvious in hindsight, but when you're standing at the forefront of human knowledge, the path forward is very unclear. Welcome to Daniel and Kelly's extraordinary universe. Many parasites and space, and I'm looking forward to seeing how many different incorrect ways I can say Tycho Brahe today.

That's probably one. Hi, I'm Daniel. I study particles and aliens, And even though I speak Danish, I'm not going to try the correct pronunciation of Tico Brahe's name. So that wasn't it. That was not it because that's like a Latinization of his name, which has some other Danish formulation, which I've heard Dane say, and I'm not going to try to reproduce because it uses one of those many Danish vowels that doesn't exist in English.

And you said Tihoh? Tico Brahe is the like the Latinization of it. But yeah, it's very different in the actual. Danish. Okay, I was closer than I think probably any of us would have guessed. So that's pretty good. All right. Points today for Kelly, right off the bat. Woohoo for not being so far off. So today we're talking about sort of misconceptions about the way the universe works. And so my question for you is, and I'll be honest, mostly this is just because I want to share a funny story. My question for you is what is a misconception that you have heard?

from a child or a misconception that you had as a child that you thought was pretty funny and you'd like to share. It was shockingly recently that one of my children, I won't embarrass them by naming which one, revealed that they didn't understand that stars were distant sons. What? We had a moment at the tenor table when I said, wait, you know that stars are just other sons and their jaw just dropped. Like, that was the moment they learned that. And I felt surprised and confused and embarrassed. Like, how can my child not have known this until fairly recently?

Oh, my gosh. I have failed as a parent and as an educator. What did they think they were? Like aliens shining laser pointers? That was my follow-up question. And they were like, you know, I just never really gave it much thought. And I was like, what are you doing with your life? You never thought about what the stars are.

Oh, my gosh. And how have I failed you with a parent? A plus. A plus. So I mentioned to one of my kids, I also will not say which one, that my husband's middle name is Alexander. And they go, Alexander, that's like a name for magicians. And I was like, magicians. And she goes, yeah, like Alexander the Great. Who I saw in Vegas.

He was great. He was great. And I was like, Alexander the Great was like. commander who like killed a bunch of people to make one of the largest empires in history. He wasn't pulling rabbits out of a hat. And he goes, what? Oh, oh wait. And they, whichever child it was that did that, said, what?

Anyway, and then I started laughing so hard I cried. And so that they started laughing so hard they cried. And we both had a really good laugh about it. And now we joke about Alexander the Great, the magician. Also, not the main character. from Alexander and the No Good, Very Bad, Terrible Day. Oh, I loved that book when I was a kid. Yeah.

Another great one. Another great Alexander, but not Alexander the Great. Absolutely. And today we are trying to clear up some of your great misconceptions about the history of physics, how we figure it all out. Because, you know, physics and science, more broadly, is not a linear step from A to B. It's multiple branching paths, dead ends, and wrong ideas, which persist. for centuries before we figured stuff out. And though we often tell the stories as a linear progression, obviously moving from one step to the next, it's much more interesting when you dig

into the details and learn the nuance. And I feel like we often don't hear those stories because they're harder to tell, but it's a much more accurate depiction of, you know, how humans as a society work. And so we're going to try to tell that story today because we like challenges. And I started looking through our outline today. And I looked at the question. you sent are extraordinary. And I have to think that maybe they're wondering what's happening to the podcast that they're listening to because the question you asked them is, could the sun orbit the earth? And maybe Kelly next week is going to send out how many times have you seen Bigfoot or how tall

is Bigfoot? But I guess we'll see what they had to say. That's right. Is Heliocentrism a government scam? That's right. Are the lizard people running the world? That's right. But there was a caveat also in the question, right?

The question was, is it possible that the sun orbits the Earth with all the other planets orbiting the sun? Oh. Right? An even weirder idea. Oh, you wrote that in smaller text and so I skipped it. All right. So think about your mental picture of the solar system. Is it possible that the sun could be moving around the Earth?

with all the other planets orbiting the sun, or is that just too weird to be true? Here's what the extraordinaries had to say. I don't think so, just based on what we know about the masses of the sun, Earth, and other planets. I think technically the sun and Earth orbit their common center of mass, but I'm not sure that might still be inside the sun. As I understand it, it's not that the sun would orbit the Earth.

It's that orbits are the two objects orbiting around one point. And if you were to expand this out to all of the planets in the solar system, they are all orbiting some point, which is probably inside the sun. No, I do not think it is possible that the sun orbits the Earth, with all of our planets orbiting the Sun. I think we've had this figured out since Copernicus. Now, if the Sun orbited the Earth, but all the planets still orbited it, that would make Helios really upset, I would have expected, and also be, more than a three-body problem. No. Since motion is relative,

you could describe the motions of these things in such a way, but for that to hold with all we know about gravity, the masses of these objects and star formation. Is it possible that the sun orbits the Earth with all other planets

orbiting the sun? I don't think so, because otherwise that would mean that the earth is the center of gravity, and if the sun orbits the earth, then all other planets will also orbit the Earth. All right. So at least one of our extraordinarily are 100% onto you and provided the historical context. I think you confuse some of them. And the rest of them are switching over to real science podcast now, Daniel. Join us next week.

We'll be interviewing Bigfoot on his theory of heliocentrism. Okay, but what is the context for why you asked this question in particular? The context is the history of how we figured out the geometry of the solar system and, crucially, how it moves in relation to the rest of the universe. And it turns out the usual story of like the Earth is the center of the solar system, to the sun is the center of the solar system and that we moved to this new idea about 500 years ago misses a lot of interesting nuance about the history of physics and the alternative ideas, which took a long time to squash.

All right. Well, let's start at the very beginning then. What was like the first theory for what was happening with the Earth and the Sun? I mean, fortunately, some people who were not your kids were looking outwards and we're thinking what's going on out there. Ouch. Ouch. Ouch, oh, that stings. I won't pick on your kids anymore. No, that's a blow against me as a parent.

Ooh. You know, if you read ancient theology and ancient writing about the solar system, people were curious about it for a long, long time, and they had sort of a mental picture of how things worked. And, you know, some of them were geometric thinkers, and they imagined the earth as a flat disk covered in a dome, and the stars were, like, lights in that dome somehow. and other theories like the Chinese, they were more arithmetic, just looking at the patterns in the sky,

not always assembling like a geometric picture of like where everything was at the same time. I think the first, like, credible theory for how things work comes from the ancient Greeks. You know, we're talking like Aristotle days, 300-ish BC, which rests, of course, on the knowledge that the earth is a sphere and not a flat disk. I've been reading a little bit more about the history of medicine and just kind of like the history of science. Does every piece of information we know, like go back to Aristotle? It feels like everybody has to have a like, what did Aristotle think about this moment in their history? Yeah.

Well, you know, Aristotle and the Greeks get a lot more credit than people usually give them because their theory of geocentrism was honestly pretty good. Okay. It fit the data. It was the best explanation for the data. and we're going to explain why in a minute. And I've often been guilty of dismissing the Greeks as being pre-scientific about just like sitting in a cave and thinking about the universe. But that's too simple.

Like they really did use data and look at the universe and try to make their theories fit with their observations. And it's like not technically empiricism because that didn't come for a couple thousand more years, but it's almost empiricism. I mean, like, how did they know that the Earth was a sphere to begin with? You know, they could see that like the constellations were different in the northern and southern hemisphere, right? You see different stars, which suggests that you have a different view because you're looking out on a different part of a round ball, right? You're not just standing on a disc where you would see the same view all through the year. They could also see the shape of the earth when they saw a lunar eclipse, right? Remember, a lunar eclipse is when the earth is between the sun and the moon. So the earth is making a shadow on the moon, instead of the the moon making a shadow on the earth, which means you can see the shape of the earth on the moon. It's super amazing, right?

It's like the universe is revealing the shape of the earth. It's like if you did hand puppets, right? You stood up on the edge of the earth and you stuck your hand out during a lunar eclipse. Technically, you could do like hand puppets on the surface of the moon. The moon is the screen there, right? It's amazing. But wouldn't a flat, maybe I'm not going to, maybe I'm not going to want this on the record. No, no.

Do it. Wouldn't a flat disk make a similar shadow as a sphere? A flat disk would make a similar shadow if it was perfectly aligned, right? Otherwise, it would be like an ellipse or it would look like a line depending on its alignment between the Earth and the Sun. So you could, if you only had that one piece of data, argue that the Earth could be a flat disk that was perfectly aligned to make a circular shadow, yes. Okay. So that one piece of information is not enough. Got it.

Okay. And I had heard that another piece of information that they'd use is they'd watch. as they'd watch ships, and as the ships went away, you could see the, like, bottom part of the ship going away, but you'd still see there, the masts and the sails. Yeah, exactly. You can literally see the curvature of the earth if you look over long distances, because you can see the top of the ship, and you can no longer see the bottom of the ship, right? And there's also an experiment they did where you look at shadows at different parts of the earth. And, you know, if the sun is straight overhead in one city, so it makes no shadow, you can measure the length of a shadow in another city. and you can deduce whether or not you're on a flat surface or on a curve based on the length of that shadow.

And flat earthers also argue like, oh, but that would also be true if the sun was not super far away. If it was close, it could cause the same effect. But you can rule that out by just adding a couple more sticks and measuring more shadows. So anyway, the earth is not flat and the Greeks knew that, right? And that raised an obvious question to them, which is like, okay, if the earth is a sphere, why don't we fall off the bottom of it, right? And why does the stuff in the sky not fall to the earth? Because, like, you drop an apple, it does fall. You don't need Newton to observe apples falling to see that apples do fall. So this is a very natural next question for Aristotle. And this is where his theory sort of falls apart because his theory here is sort of just like, well, because. He says, apples and people are made out of a certain kind of stuff, which we'll call like earthy stuff. And, And earthy stuff is defined as stuff that falls to the center of the universe.

For no reason, that's just the nature of earthy stuff to do. And heavenly stuff, star stuff, doesn't. It's embedded in crystal spheres and so it doesn't fall. And so like, why don't we fall off the surface of the earth? Because it's not in our nature to fall off the surface of the earth. We are made out of earthy stuff and everything falls towards the center of the universe, which is the center of the earth. And everything out in the heavens is not made of that stuff.

And so it doesn't fall to the earth. And it seems kind of quaint now, doesn't it? Yes. Yeah. Why don't I go to California? Well, because I'm made out of Virginia East. And so I tend to fall into Virginia. And, yes, and you're made of, like, crystals that stay in California.

Yes, we are made of crystals out here, exactly. Hence our shimmering lifestyle. And because stuff doesn't fall to the earth, it's made out of heavenly stuff, and therefore it's perfect, and it moves in perfect circles. And this is the first idea that the Earth is at the center and everything moves around it. And you might initially think like, well, this is kind of a goofy idea, right? Why did they come up with this plan? And this is the first place where I think the Greeks don't get enough credit and the story is more nuanced than people understand. Because the Greeks considered the idea that the Earth was not at the center.

They thought about, well, what if the sun is at the center? Could that be? And they examined what that would mean for the solar system, and they actually thought of a way to test it, which is super cool, right? Because you shouldn't just sit in your toga and eat olives and think about the universe. You should figure out a way to force the universe to reveal to you the truth, right? That's what experimental physics is all about. And they realized that if the Earth was not at the center of the universe, if it moved around the sun, right? If the sun was at the center and the Earth moved, they should be able to tell because they should see the

Stars Wiggling. Oh. And is there a technical name for Wiggling? Are you insisting that I use a Latin term instead of explaining the concepts? No, no, let's stick with Wiggling. That's it. The whole episode, I want you to stick with Wiggling. Well, you want to learn more about it.

You're going to need to know the official term, which is Parallax. But we call it Stars Wiggling. Oh, oh, wait. So when I want to explain a species, is it okay if I just say, well, the listeners might want to know more about U. up Larkas Californiansis, which is why I need to tell you the species name. I didn't realize that worked. If anybody actually wanted to know more and... Who would not want to know more about brain infecting parasites of fish?

Hard to imagine. Hard to imagine. All right. All right. Parallax. Got it. Stars wiggling is called parallax. Yeah, exactly. And this is something that's very easy to understand. This is actually how your eyes work to see distance. Like if you hold your thumb out in front of you and you look at it with one eye versus the other eye, it moves, right? It's not in the same location relative to the two eyes. So your two eyes have a different view of your thumb. And as your thumb gets further away, the difference shrinks. And as your thumb gets closer to your eyes, the different gets larger.

And this is binocular vision. This is how your brain can tell how far away something is. When a basketball is flying towards your head, your brain does this calculation based on the different view from the two eyeballs to tell you how close is it, right? How rapidly is it approaching? And so you can do the same thing with the earth. If the earth was moving around the sun, then we should get two views of the heavens in different times of year. Like in June and in December, we would have a different relationship to the stars and we should see them move.

We should see them wiggle. And they looked, they looked at the stars, unlike my kids, and they did not see them wiggle. And they said, oh, look, the stars are not wiggling. therefore, because the stars must be close enough to wiggle if we were moving, we are not moving. And that was the flaw in their logic. They could not fathom that the stars were far enough away to be wiggling, but invisibly, because they were so crazy far away. And they said, well, the stars can't be that far away.

And we don't see them wiggling. Therefore, the earth is not moving. And that is solid logic. But the stars are so tiny. How could they not consider it? Well, you know what? That is impressive, that they did the experiments and they figured out Paralax that, like, props to the Greeks in their togas.

And of course, now we know with hindsight that the stars were wiggling. It's just that the wiggle is so small because the stars are crazy bonkers far away, so much further away than they could even ever imagine. So far away that we didn't see Parallax, we couldn't measure it until 1838, fairly recently. This was just a theoretical concept for a very, very long time. And turns out to be quite relevant to this story. So the Greeks, a thought of parallax, and they ruled out a sun-centered universe because they didn't see it. There's a logical flaw there, but you got to give them props for using experimental data, for actually testing these two theories. And if I was in their shoes,

I would probably come to the same conclusion. Yeah, yeah. This is the kind of stuff that keeps me up at night thinking, oh my gosh, what else do we think like, oh, yeah, well, we thought of that and we ruled it out. Yeah, exactly. What else? You make one very reasonable sounding assumption. The stars are not crazy bonkers distant away, and you go down the wrong track for a thousand years. Or more than a thousand years, but yes.

All right, let's take a break. And when we get back, we will jump into the ideas of Ptolemy with the silent P. Pride is like love. You feel it in your heart. IR. Radio. Canada's number one streaming app for radio and podcasts, including IHart Pride Canada, your favorite hits and must have party bangers, plus personalized and curated playlists.

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on the IHeart radio app, Apple Podcasts, or wherever you get your podcast. Kelly, you are inviting some Greek speaker to write in and tell us that we are mispronouncing Ptolemy. Maybe there's just like a really subtle pee in there. Oh, Ptolemy. I don't know how to do it. Greek speakers write in and tell us if we are mangling Ptolemy and pterodactals. Oh, I mean, nobody's going to be surprised at least mangling names. But all right, let us know. So the first problem with Aristotle's theory that things in heaven are perfect and move in perfect circles is that they don't, right? If you follow the planets, you can see that they do not move in perfect circles in the heavens.

They go sometimes into a retrograde. This is not an astrology podcast. We're not talking about whether you should be making big moves in your romance life when Mercury is in retrograde. Retrograde is also an astronomical thing. it's when planets change their apparent direction in the sky. Are they actually changing direction or do they just look like they're changing direction because of how we're moving? What's the difference? I mean, everything is relative, right?

And so we are looking at the motion of the planet against the background stars from our point of view. So from the point of view of the sun, planets don't change direction. They move in an orbit going the same direction all the time. But planets move at different speeds around the sun. And so sometimes they can pass each other. So from our point of view, sometimes it looks like they're moving one way and then we pass them so they're going backwards. And then it looks like they're moving forwards again. Just like, you know, if you're on the highway and somebody is really far ahead of you, you can tell that they're going forwards because they're passing stuff, right?

But then as you pass them, it looks momentarily like they're going backwards relative to you, right? In your car's window, they're going backwards. Then once you're far away from them again, you can tell, oh, look, they're going forwards relative to the background mountains. That's sort of what's happening with the planets. If you look at Mars and you write down its location in the sky every night, you'll see it moving through the ecliptic, and then you'll see it go backwards and then go forwards again. It does this like S-shaped zigzag. And that was a big problem for Aristotle's theory that like everything is perfect in the heavens and moves in these perfect crystal in circles. What is the ecliptic? The ecliptic is the plane of the solar system.

And so everything in the solar system is roughly in the same plane, right? The sun rotates and it rotates around an axis, and a plane perpendicular to that axis has all the planets in it. So if you're on the earth and you track the motion of the sun, it moves in a line through the sky. That's the ecliptic. And all the planets tend to move in that same line. So if you're looking up in the night sky, you shouldn't just see planets everywhere willy-nilly. They're all in the same plane in the solar system, which is a line in our sky. Got it. Okay.

All right. So to explain how do planets sometimes zigzag, they had to add the famously mocked epicycles, right? They're like, okay, we're not giving up on circles. The Greeks love their geometry in their circles, but they're just going to have circles within circles. So now Mars moves in a circle around the Earth, but in that circle isn't Mars, it's another circle. So Mars is moving within a little circle and that little circle is moving within a bigger circle. So is it like every once in a while it'll stop and like take a little walk around a cul-de-sac or is it just constantly doing like pirouettes as it goes around in its big circle? It's constantly going around the little circle and the little circle is constantly going around the big circle. Oh, wow. And the thing about this theory is that it seems kind of ridiculous, but it worked really, really well. Like compared to the previous theory with no circles within circles, it could really describe the data. And you had to take a bunch of measurements, and it was a lot of tedious calculations to find all the parameters, like how big is this circle, how fast is it moving? And there's a guy whose job there was to do this in the 1200s. And he's famous for saying, quote, had I been present at the creation of the universe, I would have preferred a simpler design. Amazing. But for 1,500 years, this is how people understood the motion of the planets in the heavens. And it worked. You know,

it described the data really well. So, like, yes, circles within circles or epicycles is used to describe the scenario where you, like, made your theory too complicated, too baroque. You know, you had to add too many wheels within wheels to fit the data. But it did work. It did fit the data, right? And it's just two layers deep. It's not like circles within circles, within circles, within circles, right?

Just circles within circles, just two layers of circles described what was happening in the heavens for the first time ever. So, like, that's a big step forward, folks. We really don't know of anyone who was like, actually, like, wouldn't it all just be easier if we put the sun in the center, guys? That theory was out there, but it was refuted by parallax. Oh, okay. We had a reason to reject that theory, right? Got it.

Okay. People had thought of it, and it was in the bin, right? Like, that theory didn't work. Got it, got it. So everyone was reminded of parallax, and we still didn't realize the stars were very far away. Yeah, exactly. Okay. Who's next?

All right. So next up is a famous player, Copernicus, in the 1500s. And there's a lot of stories out there by Copernicus. He's often described as a Polish priest, but he wasn't actually a priest. He was a canon of the cathedral, which is more like a church administrator. He was never ordained as a priest. But, you know, he was part of the church, and he held an administrative post his whole life. And he was not against the church. He developed his theory of heliocentrism that the sun was at the center, but he didn't want to, like, attack the church or embarrass the church. And so famously, he withheld publishing his theory, and it was only published on his deathbed. So he got the first

printed copy of his theory, May 24th, 1543, the day he died. Okay. So that sounds less like he didn't want to embarrass the church and more like he was worried about his own skin if he still wants it to come out, but not until it can't hurt him anymore. Yeah, exactly. There's a lot of complicated stuff in here. Also, it turns out that the printer who printed his book, Andreas Ossander, was trying to, like, minimize the impact on the church. And so he added a preface, which said, like, you know, this is just like mathematics.

This is not the truth or anything. Oh, slice. I know. So this might have also helped a little bit, but probably Copernicus would have been. furious. Or who knows, maybe he wanted to, like, you know, not embarrass the church, and he would have agreed with that. But his motivation was also religious. He just thought that Ptolemy's theory, circles within circles, was kind of ugly. And it didn't reflect like the divine work of the best and greatest artist. So he wanted to put the sun at the center, not because he had any insight into

astronomy, and not because it explained the data any better. In fact, it explained the data worse, but because he just felt like the sun should be at the center because that made the explanation simpler. You no longer needed circles within circles. You could explain retrograde motion. So you put the sun at the center and now you can just have everything moving in a circle around the sun. But what about parallax? Yeah. So this does not solve the parallax problem, right? And so this is the reason why people were not going for heliocentrism. For 1500 years, his new theory does not solve. solve that problem. He suggested, well, maybe the stars are just too far away for us to notice, right? Good idea, Copernicus. Every thought, ha-ha, that's ridiculous. What are you talking about? But the other thing I think it's important to understand is that when he moves the sun to the center of the solar system, it does not give a better description of the data. So even though it's like,

we know it's true, and it feels like we're getting towards the truth, his theory did not describe observations any better than Ptolemy's theory of circles within circles, right? It's simpler, but Ptolemy had this flexibility in his theory. It's a little baroque and complicated, but it could describe the data. So what is heliocentrism from Copernicus really get you? It can't explain parallax unless you believe the stars are super duper far away, for which there was no evidence. And it doesn't describe the data any better. So I think people typically like, this was the revolution in astronomy, but it really wasn't. Okay. It's just pretty. It's just a little prettier.

Yeah, exactly. Was that the dominant theory? Or was this just a theory that was out there? Because from what you've said to me, it's not clear that this should have become immediately the dominant theory. Yeah, what we really needed at this point was better data. Okay. You know, the reason we couldn't tell the difference between the two theories that both of them described the data is the data was kind of fuzzy. This is pre-Galileo, right?

So we don't have telescopes looking at the sky, taking careful measurements. This is all a naked eye astronomy. And so that really relies on people's ability to take measurements. And so it wasn't until Tico Brahe, who built a world-class observatory using money from King Frederick of Denmark and took really careful observations, he got higher quality data that finally let us move forward and understand something else about the universe. So I think we probably can't have a conversation about good old Tico without

out talking about his nose. So tell us the nose story. So Tico Brahe, kind of a crazy dude. And remember kind of unhinged and also a little bit mean. And when he was 20, he fought a duel with a fellow Danish nobleman over math. Right. They had an argument about, like, who was the better mathematician? And they fought a duel, like with swords.

And he lost a big chunk of his nose. And so for the rest of his life, he had a prosthetic. nose, which was like brass or maybe a silver gold alloy that he had to like stick on because otherwise he just looked really weird and you can't be like part of polite society with a huge slicing your nose taken out. So he walked around with this like box of adhesive paste to stick this fake nose onto his face. Which I think is a failing of polite society back then and remains to be a failing of polite society today. We should all be much more chill. But anyway. But in 1576, Six, King Frederick of Denmark gave him an island.

This is the island of then, which I've been to. It's a beautiful place. You can bike around. It's gorgeous. He has a castle there. Uranabor, Castle of the heavens, later renamed Castle of the Stars, Stianabor. And it's essentially one of the first, like, astronomical research facilities in the world, you know, like built to see the stars to take careful measurements.

So if you have a facility that's gigantic, You probably need a lot of people to work at that facility. What was it like working for good old Brahe? Yeah, so Brahe was not a kind employer. You know, he was famous for being brutal to the local peasants, demanding all sorts of stuff from them. He was also a really weird guy. He had like an elk that he kept in his house.

And sometimes he would feed it too much beer and it would fall down the stairs. What? Like, this was a weird dude. He apparently died of a bladder infection from sitting at a wrong. royal banquet for too long and refusing to get up to urinate, which was apparently rude and rupturing his bladder because of that. So he was definitely a weird guy, but there's some things about him which resonate with me. Like, he was trying to look at the heavens and to observe things, and there was supposed to be an alignment of Jupiter and Saturn. But it happened two days after it

was predicted, and that's because the measurements were just not great. Like, we did not have precise measurements of stuff. And so predicting what was going to happen in the sky is limited by the measurements that we could make. So that was his motivation. It's like, I want to understand the heavens better. So he measured the positions of celestial objects in the sky to one arc minute, a 60th of a degree, which is precision of like a fingernail at arm's length, right?

These are naked eye observations. No telescopes, no lenses, right? That's amazing. So this data that he gathered is like, 10 times more accurate than any data anybody's had about the sky. And this is what fueled the revolution in astronomy is like needing to actually describe the universe more precisely. And neither the Ptolemaic nor the Copernican models fit that data. Oh boy. So you might be expecting, oh, we take better data, and that's when we learn the heliocentrism is the truth. Oh, no, we take better data and we

discover neither of those two models actually worked. So what do we do? Yeah, Tycho could not make this work either, right? And the issue, of course, was not going to be solved until later when Kepler came up with his ideas of ellipses, but we're not there yet. Because Tycho rejected Ptolemy's theory that the Earth was at the center of the universe. He also rejected Copernicus's theory that the sun was at the center of the universe. He had his own theory, the tyconic system of the solar system, which sounds like a died plan from medieval Europe, but it was like a new vision of how the universe might work. I hope it doesn't involve drinking beer and sitting at a table for a real long time.

With an elk. Sounds dangerous. So he liked the idea that the Earth was in the center. Tycho said the Earth was a hulking, lazy body unfit from motion. And it made no sense to him that the Earth was in motion. And also remember, we were not seeing parallax. So he really wanted to keep the Earth at the center of the solar system. But he also liked the simplicity.

of the Copernicus system, right, where you don't have circles within circles, where you can explain retrograde motion by having the planets move around the sun. So Tycho was like, hmm, I want the Earth of the center and I want the planets to move around the sun, because no los dos, right? I don't think he spoke Spanish, but that was the inspiration, right? And it was probably before that commercial, so. So that's the iconic model of the solar system is you have the Earth of the center, the sun moves around the earth and all the planets move around the sun, not around the earth, right?

That's complicated. So it's geoheliocentric, right? Wow. So the Earth is at the center. The sun moves around the Earth and all the planets orbit the sun. So like together, our sun is bringing all the planets with it as it orbits around the Earth. It's kind of bonkers. Does this actually do a great job with the data?

So, you know, this explains retrograde motion, right, because you have the planets moving around the sun, not the Earth. Okay. And it explains no parallax observation. We didn't see parallax. Why? Because the Earth was not moving relative to the distant stars, right? Okay. So this was kind of a great idea.

And this Tychonic model, though you never hear about it anymore, survived for centuries and was taken seriously for centuries because it fit the data very well. Wow. Now, he still used circles, right? This is pre-Kepleur. So he wasn't actually able to fit his own data any better than Ptolemy or Copernicus. Anybody still using circles for these planets was still not getting great predictions because actually the planets move in ellipses, not in circles. But he did explain retrograde motion and parallax observation. And Tycho thought that Copernicus's idea that the stars were so distant and that's why we couldn't observe parallax was crazy, because he calculated they would have to be at least 700 times more distant than Saturn, which to him was like a bonkers number.

If you can see their size and you have an estimate of their distance, you can calculate how big they must be. And he got a number, which was huge, much bigger than the sun. And he was like, well, that's crazy. Now, of course, we know there are some really, really big stars out there. And they were really onto something. But these numbers were just so bonkers to them that they dismissed it. Right? So Tico Brahe preferred putting the earth at the center of the solar system rather than accepting the stars were super distant and some of them were super duper big.

I thought maybe you said this idea was accepted for centuries and maybe I'm, I misheard you, but I thought it looks like Kepler in like decades comes up with a better idea. But did what Kepler's idea is not? So Kepler, soon after Tico Brahe comes up with the idea of ellipses, right? Because he's Brahi's assistant. And he's tasked with his job of like, look, I like this theory, but it's not really quite working. He can't explain the data. And he was struggling and struggling and struggling to make the orbit of Mars work in particular. So Kepler couldn't make this work. He struggled for years. And finally, he was like, okay, let's use ellipses.

Let's take a break. And when we come back, let's go ahead and settle this debate, which is what you'd expect us to do in the third segment of our show. Pride is like love. You feel it in your heart. IR. Radio, Canada's number one streaming app for radio and podcasts, including IHart Pride Canada, your favorite hits and must have party bangers, plus personalized and curated playlists. Like back in the day pride.

Come together, celebrate love. Take pride with you anytime, anywhere. Just ask your smart speaker to play IHart Pride Canada. Stream us on your phone. Or listen now at IHartRate. Radio.ca. Hey, it's us, the Jonas Brothers, and guess what? We have some big news.

What's the news, new? Huge news. We created our own podcast called, Hey Jonas. We invented a podcast? Well, we didn't invent it. We just contributed to it. We're the first people to do podcasts. Pretty, yeah, pretty wide range of podcasts.

We're starting a trend. But this one's extra special. So how do we actually come up with a name, Hey Jonas, guys? I honestly don't remember. I think it was on a call about what we should call it. And, well, we were thinking I'm originally calling it one of the early names of our band before Jonas Brothers. This is how you guys remember it going down? Yes.

I have a very different memory of this. We were talking about a thing, a bit for the podcast, where people could call in and say, hey, Jonas. And then I wrote down on my little notepad, Hey Jonas, and offered it up as a potential title for the podcast. But thanks for remembering that, guys. Listen to Hey Jonas on the IHeart Radio app, Apple Podcasts, or wherever you get your podcast. Just listen. We don't care where you hear it. Mainstream media is full of cruel depictions of the unhoused, stories that shame and blame and paint the unhoused as a monolith. We The Un-House is the podcast that's changing that.

I'm Theo Henderson, creator and host, and for years I've created a space where the Un-Hows and their advocates can tell their own stories. In the last few months alone, I've interviewed unhoused parents, immigrants, mutual aid organizers, veterans, the LGBTQTIA plus community, and the policymakers who make the laws that impact the unhoused existence. Woody and Houses a two-time Webby and Signal Award-winning show with many exciting guests on the horizon. Tune in this week for my interview with Dr. Jill Wichor, a street doctor turned influencer whose work with the unhoused community has made a huge impact online and in her community.

Listen to Wey and Hous on the IHard Radio app, Apple Podcasts, or wherever you get your podcast. Here's something that should not be as complicated as it is. Getting a racist statue removed. And here's something that should be a whole lot easier than it is. Getting a new one put up in its place. As long as there's a politics of race in America, there's going to be a politics of remembering the Civil War. To get to school, I had to go down Robert Lee Boulevard. Get to the grocery store.

I had to go down Jefferson Davis, If you're an historian and you leave out half of what the history is, you're not doing your job. I'm Akila Hughes, and Rebel Spirit Season 2 goes deep on both of those things. The fights, the politics, the people who won, and my personal campaign to add something to the Kentucky State House that's actually worth the wall space. We are more than our bodies. We contain essence. We contain spirit.

How do you represent that? They are just fueling a fire that is really catching. You'll see what I mean. Listen to Rebel Spirit Season 2 on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. And we're back, and we are finally going to settle this geocentrism, heliocentrism debate. What's going on with parallax? Daniel, let's settle this thing. Right. So we have the Ptolemaic version. The Earth is at the center. We have the Copernicus version. The Sun is at the center.

We have the Tyconic version, which puts the Earth of the center and all the other planets, the sun, right? And none of them are working very well. The reason is that all of them are still based on circles. All the orbits are circles. So Kepler comes in. He's trying hard to make this work. He can't make it work. He comes up with the idea of ellipses, right? He adds this to Copernicus's theory, right? So the Kepler view of the universe now is Copernicus, but with ellipses instead of with circles. And this matches the data. This works really, really well. And ellipses being long circles? Yeah.

Elypses are like the shape of an egg, right? So a circle is perfectly round, and ellipse is like a squished circle, right? Got it. And he can also upgrade Tico Brahe's theory to use ellipses, right? So now the Ticonic model can have ellipses. The Copernican model can have ellipses. The Ptolemaic model does not allow for ellipses because, you know, they're going for, like, perfect circles, right? But you can always just add more ellipses to Ptolemy.

So it is possible to fit Ptolemy's theory to Brahe's observations. You've just got to add more and more circles. And so it's not really true that Tico Brahe's data killed the Ptolemaic system, right? Because the Ptolemaic system allowed you to just add more and more circles as you liked. What really killed the Ptolemaic system was Venus. What? How did the goddess of love kill Ptolemy? So remember, Ptolemy could always just add.

more circles, no matter what data you took, he could actually fit it. But Galileo realized that observing Venus would help us understand whether Venus was orbiting the Sun or orbiting the Earth. So Galileo comes around late 1500s, early 1600s, and he realized that your view of Venus would depend on whether it was orbiting the Earth or orbiting the Sun. Okay. So if Venus is orbiting the sun, right, it's moving around the Sun, there's going to be some point at which Venus is is on the other side of the sun than we are, right? Then the sun is going to be between Earth and Venus. And in that configuration, we should see an entire side of Venus lit up, right?

We should see like a full side of Venus. Venus should be like full in the sky, not a crescent, but a full circle in the sky. When it's on the other side of the sun. When it's on the other side of the sun, because in the light from the sun hits the whole surface of Venus, and then we see that whole thing. just like how you can see a full moon, right? You can see a full moon when the whole side of the moon is being illuminated by the sun. Okay, I guess when I'm imagining it's on the other side of the sun, I can't see it because it's blocked by the sun. So what is my mental model missing there? You're right that if it's exactly behind the sun, you couldn't see it. But now let it move like a little bit around from behind the sun. And you can see essentially the entire surface of Venus is lit up by the sun, right? Perfect. Okay.

Okay. So now in Ptolemy's model, Venus is orbiting the Earth and not orbiting the Sun. And so never is it on the other side of the Sun. In Ptolemy's model, Venus has its orbit around the Earth and the Sun has its orbit around the Earth, and their relative distances are fixed. And so in Ptolemy's model, Venus is always between the Earth and the Sun. And so you should never see like the fall phase of Venus. You always see a crescent. Okay. So you can just look, you just watch Venus. And if you look at Venus, you can see that the phases of Venus are perfectly predicted by Venus orbiting the Sun instead of orbiting the Earth. So it's the phases of Venus that finally kill off the Ptolemaic system. Direct hit. Ptolemy goes down. But here's an important wrinkle that I didn't fully understand until recently.

It does not kill off Tico-Brius system. Oh. Right? So we have Copernicus who says the... Sun is at the center and everything is orbiting the sun. We have Tico Brahe who says the Earth is at the center. The sun is orbiting the Earth and all the planets are orbiting the sun. That's consistent with the phases of Venus, right? So Tico-Brahe system is not killed off by the phases of Venus. It's still around. How do we kill that one off then? The thing to understand about the

difference between the Copernica system and the Tico-Brahe system is that even though they sound really, really different, they're actually totally equivalent for local motion. It's just a coordinate transformation. It just says, are you viewing it from the sun or are you viewing it from the Earth? They make exactly the same predictions for where things are in the solar system relative to each other. Their only difference is who's moving relative to the distant stars. Like, is the Earth motionless with respect to those stars or is the sun motionless with respect to those stars. Within the solar system, they're exactly the same prediction. Okay. And just to remind people like me, again, whose brains don't hold information,

Copernicus predicted. The sun at the center. The sun at the center. And Tico has the Earth at the center. The sun goes around the earth and the planets go around the sun. Yeah. And you said, that sounds a lot more complicated. Yeah. And it seems more complicated and it's harder to hold in your mind. But any prediction it makes is exactly the same as the Copernican system for insolns. the solar system. It's just a coordinate transformation. It just says, from whose perspective, are you seeing this? So the only way to tell the difference between these two systems is to ask, well, who's moving relative to the distant stars? And you might think, okay, finally, here's where parallax has got to come in. Eventually, we figured out parallax, and that's what killed Tico Brahe's system,

right? Maybe. Wrong. It was not Parallax that killed off Tico Brahe's system. It was at something totally different. It was stellar aberration. I don't know what that is at all. Stellar aberration is super famous in the history of physics for killing off the ether theory. That's a whole other podcast episode. But the idea is you can measure our velocity relative to the stars by looking at how their angle changes during the year. This is different from parallax, right? Parallax just says that if you're in a different location, you'll see them in a different point in the sky. This is sensitive to our velocity relative to the stars. Because if you imagine the light coming from the star, it's going to come down your telescope tube. So you have to point your tube of your telescope where the star is.

But if the star is moving, right, then the light's going to come in at a different angle. And so you have to point your telescope tube slightly differently in order to catch it. And so the star appears at a different place in the sky than it really is if it's in motion. Now, if you have constant velocity relative to the stars, then you'd see them at a shifted angle all year. You wouldn't be able to tell anything. But if our velocity changes during the year because of our orbit around the sun, then this aberration, this change in the angle, changes with respect to the year. One easy way to think about it is that parallax comes from changing your position, while aberration comes from changing your velocity. Parallax is the same effect you see when you look at your thumb with one eye, and you're not.

and then the other. Aboration is more like tilting an umbrella forward when you're walking through the rain because your motion changes the apparent direction the raindrops are coming from. And this was observed 110 years before parallax. And that proves that the Earth is moving relative to the distant stars just the way you'd expect if it's orbiting the sun. If you did that measurement on the sun, you'd see much less aberration because the sun is moving less relative to the distant stars. And so this is what finally killed off Tico Brahe's theory that the Earth was at the center and not moving relative to the distant stars. Ha ha! Okay. And so now Kepler wins.

So now Kepler and Copernicus win. And it's not until 100 years later that we observe parallax. The thing that the Greek said was the key to understanding whether the Earth or the sun is at the center of the solar system. And this comes because Bessel invented something called. the heliometer, which uses relative measurements rather than absolute measurements. So instead of like trying to really precisely measure the location of the stars, you just measured the motion of the stars. So it's sort of like subtracting away a source of your systematic uncertainty to only look at changes in your measurements.

So really cool story there. But 100 years too late to actually be relevant to this debate. What do you think the takeaways are here? Because like, so you've got a bunch of models that do a good job of explaining the data, but they were still wrong. But we kept thinking about it and trying to do a better and better job. But how would, what is the Daniel uplifting message here? You know, I think that the story is a lot more complicated than people usually tell it. You know, I think the not widely understood takeaways are that Copernicus and Ptolemy both describe the pre-Cepler data really, really well.

And the Greeks had a good reason to put the Earth at the center. of the solar system. And that there was a third player in this whole debate, right? Tico Brahe is sort of forgotten. Nobody talks about the ticonic system, even though it survived until the 1700s. And that Kepler's analysis and ellipses didn't actually disprove geocentrism, right? It just made Ptolemaic less likely because it required more circles within those circles. It was the phases of Venus that finally killed off Ptolemy.

And that it wasn't until aberration and then eventually parallax that Tico Brahe's system was finally disproven. The more data you have, the better you're going to do. We had to know about Venus. We had to know about parallax. We had to know about stellar aberrations. All of this came together to tell our story. Exactly.

And so this tells you that our exploration of the universe can go down weird paths for hundreds of years sometimes before somebody takes the right piece of data or has the right idea. And that many of the stories we tell about the history of scientific discoveries are vastly oversimplified. and that if you're standing at the forefront of human knowledge at any given moment, it's not always obvious what the next step is, even if it seems like it in hindsight. That's right. All right. Thanks, Daniel, for this walk-through science history.

I had a great time. Until next time, Extraordinaries. Thanks, everybody for listening. Please go and do us a favor and rate the show on whatever podcast app you're using. It really helps people find us. Daniel and Kelly's Extraordinary Universe is edited by the amazing Matt Kesselman. He really is a wizard. You can also find us online on Blue Sky, Instagram, and X, D&K Universe.

Come engage with us. You can email us at Questions at Danielandkelly.org. We really do want to hear from you. And you can find our website, www. www. danielandkelly.org, where you'll also find an invitation to join our Discord, where everybody comes and talks about the amazing universe. And we also have the most amazing moderators. This is an I-heart podcast. Thanks for joining us.

It's a record sold. Awards, sold-out tours. You think that Jonas Brothers are satisfied? Nope. It's podcast time. We get to ask other people questions because we're sick and tired of being asked questions. Hey Jonas is available now, and their first guest is a big one. Paul Rudd.

You know, Steve Carell is a great singer. Can you tell you not to audition at the office or something? I told him. Whoa. We were filming Anchorman. Clearly, I was the idiot. Thank God he didn't listen to me, right? If listen to Hey Jonas on the Iheart radio app, Apple Podcasts, or wherever you get your podcasts.

June is Black Music Month, and on the Drink Chams podcast, we're speaking with the hottest names in the culture, like Sway Lee. Do you realize how legendary you are? I appreciate that. I'd be seeing it, but I'm like, man, I still got, like, so much more to do. Like, Prince, he dropped, like, 30 albums. We dropped, like, five right now. That's the rate we got to be going. Yep, that's a good attitude.

No matter the era, Drink Chams brings you the biggest names and the most understant. filtered conversations. Listen to Drink Chams from the Black Effect Podcast Network on the IHeart Radio app, Apple Podcasts, or wherever you get your podcast. Hey, it's Alec Baldwin. This season on my podcast, here's the thing. I talk to composer Mark Shaman. It's about the hang. It's the pleasure of hanging out with the people that you're with. You know, Rob and I was always a great hang. And director Morgan Neville. Film school teaches you all the wrong things about making documentary. What do you want to say? Documentary is all by your ear. What do you? What do you? hear. I feel like my job is listening really, really hard.

Listen to Here's the Thing on the IHeart Radio app Apple Podcasts, or wherever you get your podcasts. This is Saigon, the story of my family and of the country that shaped us. From IHeart Podcasts, Saigon. You don't think I'm serious about a free Vietnam? One city, a divided country, and the war that tore America apart. This is for Vietnam. They're pouring patril all over here. Freedom for Vietnam. There's a fire coming to this country and it's going to burn out everything.

Listen to Saigon on the IHeart radio app, Apple Podcasts, or wherever you get your podcasts. This is an IHeart podcast. Guaranteed human.