Hey, please take a second and leave us a review on Apple Podcasts, Spotify, or wherever you listen to the podcast. Thanks a lot. Hey, Welcome to Science Stuff reproduction of iHeartRadio. I'm hore, Hey cham and today we're answering the question is the North Pole moving? What actually is the true North Pole of the Earth? Is it changing? And should
Santa Claus consider moving somewhere else. We're going to talk to a planetary scientists about this, and as you'll see, there are a lot of surprising things to learn about what we call the North Pole. Now, this is part of a two part holiday special, so be sure to check out next week's episode about how the New Year is changing. But for now, check under the tree because we're going to find out if scientists have been naughty or nice in tracking scantus address. Enjoy and happy holidays.
Hey everyone, So the holidays are upon us, and I thought I check in with my friend, planetary scientist, doctor Matt Siegler, a professor at the University of Hawaii who works with NASA and the European Space Agency on several projects. The first thing I asked was what exactly is the North Pole? So here's my conversation with doctor Siegler. Well, welcome back, doctor Siegler. Happy holidays.
Oh, happy holidays to you.
Do you have any big plans for the holidays? You're in Hawaii? Is it weird to celebrate Christmas in Hawaii? Yeah?
This is actually going to be our first Christmas staying over in Hawaii, So we'll see what Hawaii Christmas has the store.
Did they just play that song male Likelikimaka twenty four to seven there?
Yeah, yeah, until you go and say, at least it's a catchy song. It could be worse, and.
It always puts a smile on your face. Nothing wrong with that.
We'll see after a whole season of it.
Well, today, I thought it'd be fun to ask some holiday and New Year's related questions about science. And you're a planetary scientist, so I thought you'd be the perfect person to talk to us about this. Okay, great, Okay. The first question is what is the North Pole? Yeah?
So there are two North poles? Wait what this is the first thing to think about. There's the North Pole that we spin on right the rotational axis of the Earth. But on top of that, there's this magnetic North Pole, and we'd really love it if the two lined up right, that would make the Earth make sense that there's a big magnet in the center of the Earth and it's spinning right.
Uh huh.
But they don't.
They don't. Okay, here's the first thing to know about the North Pole. There are actually two North poles. There's the pole around which the Earth spins, and then there's the pole of the Earth's magnetic field. And they're both different and they're both changing. Okay, we'll tackle them one at a time, and we'll start with the earth spin axis.
The spin act of the Earth that we rotate around does points in different directions over time.
We're spinning in place. We're also spinning around the Sun. But you're saying, on top of that, like we're sort of like a top that's kind of wobbling. Yeah.
Then there are a couple of ways you wabble. There's the one where the stick on top of the top goes in a little circle.
Uh huh.
That's called procession of the orbit. And then there's the how the top like tips to the side or not, and that's called obliquity change.
Wait wait, wait, so we're wobbling and we're tilting at the same time right now.
Yes, yes, okay, we're always wobbling and tilting.
So it turns out the spinning of the Earth is changing in two ways. Think of the Earth like a top, like the toy you spin and throw on the table. That top doesn't usually stay perfectly upright. It wobbles, and eventually it starts to tilt. The wobbling is called procession, and it's sort of like if you stuck your arm up above your head and then waved it around in a circle. And the tilting is called obliquity, and it's kind of how tilted we are relative to the sun.
And it turns out both of those things are changing with different timescales.
It happens like the procession. That wobble circle is about twenty six thousand years.
Twenty six thousand years to do one wobble.
Yes, to be one wah. So the north Star will be the north Star, but thirteen thousand years from now or so, a star called Vega is going to be the north Star.
Really, we're wobbling that much.
Yeah, And so we move across the sky like that.
Yes, the north Star won't always be the north Star. And this one just effect whether you can navigate in the open ocean. It could affect who you are if you believe in astrology.
And one of the big ramifications this change, this procession causes those zodiac signs to change by about one sign every two thousand years.
You mean they shift in the sky kind of. Yeah.
So the zodiac sign is the sign that's behind the sun the day you were born, but now, because of this procession of the equinoxes and moving about in two thousand years, your zodiac sign is actually off by a month from what the ancient Greeks use the zodiac signs.
Wait, wait a minute, are you saying that astrology has not kept up with modern physics. Is that what you're saying.
Yeah, most astrologers have not kept up with modern astronomy and the change of the zodiac signs. I hope this doesn't like end anyone's marriage or cause anyone trouble that you've been reading the wrong zodiac sign your whole life.
It's like, oh, I thought I loved you because you were a Gemini, but it turns out, actually, in two thousand years, you're gonna be a pisson. It's over. It's over.
Yeah, love is not eternal. It's only for roughly a two thousand year period.
Yes, the wabbling of the Earth means you can't really trust zodiac signs, which I know is totally a Scorpio thing to say. And it turns out we have all the other planets to blame for this wobble. Wow, I'd never review that. And why are we processing? Is that the right word? Why are we wobbling?
So that has to do a little bit with how all the planets yank on each other. Jupiter is the big dominant one in the Solar system, so that has a big effect on us. Venus is the closest one to us, so that has an effect. And the way all the gravity of these different planets kind of yank on each other a little bit causes these tops to wobble in this weird way. Whoah, And so we influence how Venus wobbles and Mars wobbles.
Interesting, So right now we are breaking up marriages in bars, I guess. So that's our wobble. But like doctor Seger says, our overall tilt relative to the Sun is also changing about every forty one thousand years.
That's our obliquity. So it's the twenty three and a half degree tilt that the Earth has that causes seasons and all that, and that wobbles a little, but only like about a degree or so over time, I see. And that's good because that little wobble of the degree or so and the power round or oval Earth's orbit is all those things mess with our climate. So when we go in and out of ice ages, it's because of these orbital changes, these things called Malankovitch cycles.
No kidding, go on.
But luckily this tilt, the obliquity doesn't change very much because the Moon actually is so big and massive compared to the Earth, and that's enough that it kind of acts as a balance.
It gives more like inertia kind of.
Yeah, And so that moment of inertia of the Earth Moon system is pretty big, and so we don't wobble that much other planets. Wow, And so we don't have as extreme ice ages as Mars does for instance.
Interesting, all thanks of the Moon.
Yeah, thank you many yes.
So this holiday season, if you're feeling thankful, be sure to thank the Moon for the fact we're not living in an ice age. Okay, when we come back, we're going to tackle the other North pole of the Earth the magnetic north pole, and we're going to talk about how it used to be in the south pole. Stay merry with us, We'll be right back. Welcome back. We're celebrating the holidays by asking if the North pole is moving, and the answer is yes. We just talked about how
the spinning axis of the Earth is changing. It's wobbling and it's tilting in cycles that last twenty six and forty one thousand years due to the polling of the Earth by the other planets in the Solar System. Now, as it turns out, there is a third way in which the spinning north pole of the Earth is changing, and that is because of plate tectonics. Here's planetary scientists, doctor Matt Siegler.
If you slowly move continents around over you know, millions of years, that will actually change the axis along which we rotate.
No wait, like the moving continents can cause the Earth to wobble too, yeah, or.
Cause the spin axis to change, because the axis upon which we spin is controlled by that moment of inertia of the planet and by where you put your mass on that ball.
What doctor Ziegler is saying is that as the continents move because of plate tectonics. That changes how the mass of the Earth is distributed, which can change which way the Earth is spinning, sort of like if you're an ice skater and you're spinning on the ice, if you suddenly move an arm or one leg out, you're going to be thrown out of balance.
That's a called true polar wander. Whoah, if it's different from this apparent polar wander, this motion that I was talking about relative to the zodiac signs uh huh. But true polar wander is that the spin axis can actually change if you move enough mass around woa, like continent scale masses, big big masses.
So then the spin axis has been changing relative to the Earth.
Yes, but that's over a very slow time, right, because it takes millions of billions of years for continents to really move that much.
And now we get to the magnetic north pole of the Earth. As you probably know, the Earth acts like a giant magnet. He creates a big magnetic field and the center of that field is a line that runs through the Earth. One side of that line is what we call the North pole and the other side is what we call the South cole. That magnetic North Pole is where all compasses point to, and according to doctor Siegler, where that North pole is has been changing a lot. I mean, Santa, you better pack your bags.
So the magnetic pole of the Earth has actually moved quite a bit. So right now it's kind of in northern Canada somewhere, but a couple hundred years ago it was in Siberia, and a couple hundred years before that it had moved around Greenland, and then now it's like kind of moving back towards Siberia.
That's right. The magnetic north pole changes on the scale of a hundred years. In fact, it's changing right now. Scientists estimate that the North pole is moving on the surface of the Earth about a kilometer a week, which is about one hundred and forty meters a day. This means where your compass points to today is different from where your compass will point to tomorrow. And where is it going to point next. Scientists don't really know.
So the magnetic north pole has been doing its own like chaotic journey around roughly the physical spinning north Pole.
Uh huh, but it's chaotic, I mean it's unpredictable.
Yeah, it kind of changes its direction sometimes and it's going on its weird separate wobble, but it's a little more bizarre how it does.
So we can't tell where the magnetic north pole is going to move to. It's unpredictable. And that is because of what actually makes the Earth's magnetic field, which is the Earth's core.
So Earth has a big iron core, iron, nickel, sulfur or a few other molecules in there or whatever, and that core is about as big as Mars, right, So it's a big why core?
Right? Yeah?
Yeah, So Mars is about half the diameter of Earth, and so we have this huge chunk of iron in the center of the Earth as big as Mars.
That's incredible. I didn't know if that big.
Yeah, it's really high pressure. It's really hot down there, and it's hot enough that at least for the outer part of that core, it becomes liquid. And then roughly the inner third of that liquid core is under so much pressure that it's a solid again, right, like solid hunk of iron.
At the very very center. Yeah. Okay, okay, So we've.
Got a little ball of iron swimming in a Mars size ball of liquid iron, and those two things spin kind of differently from each other really, yeah, such that the solid one is kind of like the spinning blade of the blender, and then you have the liquid around that's kind of getting churned up and mixed up.
So at the center of the Earth, we have a solid ball of iron that's about two thousand kilometers wide, and that's spinning inside of a swirling ocean of liquid iron that's about two thousand kilometers And all that moving and spinning iron is what causes the earth magnetic field.
And so that ore is mostly made of iron, which you know conducts electricity. And when you take a conductor and you spin it, you cause a magnetic field.
Just see any metal, if you spin any metal. Yeah, Like if I take a bar of iron and I spin it, it's going to create a magnetic.
Field, yes, And then that causes a magnetic field in the core. And then there's this feedback where the magnetic field gets stronger and stronger, and that's what we call a magnetic dynamo.
So the spinning iron core of the Earth is what makes the earth magnetic field. But here's the thing. The part of the core that's liquid doesn't spin and flow smoothly. Yes, turbulence and swirls and eddies, and all that turbulence makes the overall magnetic field on predictable.
The solid core is spinning. In the liquid core, it causes little turbulence and eddies and such in the liquid core.
Uh huh.
Those are motion of electrical conducting material, and so those all cause a little magnetic field, uh uh huh. And they all kind of build together and give you north pole on a south pole for the whole Earth.
Oh, it's like there's a massive magnetic fields down there in the Earth's core, but overall you can they just add up together. By the time you pull out to like the Earth's surface, it just feels like one big giant magnetic field exactly.
And so because you have all this weird turbulence going on, it doesn't actually always line up in the right direction to be pointing due.
North right, uh huh.
It kind of wobbles around a lot, right, as all these little eddies and currents going on inside interact. Sometimes they'll line up with the spin axis of the Earth, and sometimes they don't. And that's happening on the scale of hundreds of years. It's like a tug of war where the pole of the magnetic field of the Earth is just migrating around.
Yes, if you look up pictures of where the magnetic north pole has been where scientists think it may go next, it's not a smooth path. It looks like the path a drunk elf would take if they had too much echnogy. And it gets even wilder. Scientists believe that in the past, the magnetic field of the Earth has even flipped, it has turned completely around to the point where the north pole was actually in the south pole of the Earth.
That would be a huge move for Santa Claus. So when we come back, we'll talk about why this happened, how we know it happened, and whether we can tell if it's going to happen again. So ho ho, hold on, don't go anywhere, We'll be right back. Hey, welcome back. We're talking about whether the North pole is changing, and so far we've learned that it's totally changing. The spin ax of the Earth is changing in like three different ways, and the magnetic north pole of to Earth is also changing.
It's meandering around worse than a drunk elf today after Christmas. In fact, scientists believe that the magnetic north pole of the Earth can even switch and flip upside down, and that this has happened several times in the history of the Earth.
Yeah, So that's where it gets even crazier. Right, So we have all of these spinning, rotating fluids and the solid core of the Earth. So you have all these eddies all interacting with each other and right now all kind of lining up where the net magnetic field points to the north pole. But because they're all fluid and can interact in these weird ways, they can all kind of work together and flip, and so sometimes the north pole magnetically becomes the South pole. Why and vice versa.
Yes, the magnetic north pole of the Earth can change so much it can even end up in the South pole. So your compass would point to Antarctica as being due north. And this has not just happened once before. It's happened maybe thousands of times in the history of the Earth.
And that switch between the north pole pointing north and the north pole pointing south magnetically has happened roughly every five hundred thousand years or so. Sometimes it's longer, sometimes it's shorter.
Okay, you might be wondering how we know this and the answer is that there's a record of the Earth's magnetic field at the bottom of the ocean. At the middle of the oceans, there are enormous seams where the Earth's tectonic plates are separating, and as they separate, lava comes up, creezes and forms thew c floor. Now, when the lava freezes and becomes rock, the metal in the rock records the magnetic field at the time the lava froze.
So if you measure the magnetism of the rocks the bottom of the ocean, you'll see bands parallel to the seam or ocean ridge where the rocks magnetism points one way and then another way, and then another way. And from the age of the rocks, scientists can tell that this flipping of Earth's magnetic field happens on average about every five hundred thousand years or so. Sometimes it happens more frequently and sometimes less frequently. The last time it
happened was almost eight hundred thousand years ago. But here's the big mystery. Scientists don't know if the magnetic north pole switches to the south pole really quickly or really slowly, and what happens in between.
It's unclear how long it takes the switch from pointing north to pointing south. Does it happen in one day or does it happen in a couple thousand years?
We don't know.
Most estimates are its probably takes a few thousand years, But that is a timescale that's difficult to measure on the geologic record, right, we can measure hundreds of thousands of years. Yeah, that we can measure pretty precisely. When you were talking about is it six days or two thousand years, like, we can't tell. It's a little tricky
to tell that precision. That's wild and it's probably a little different every time, right, because it's driven by this chaotic stirring of the core of the Earth, right, and so that's when the Earth's magnetic field will flip, uh huh. You'll kind of get this weird period in between where the compass would point to all sorts of random directions, right.
Like there might be a six day or one thousand year period where your compass will point to like Panama true north of the Earth.
Yes, because that's where the magnetic field happens to be popping out that day. And then from tradition or whatever, from the record that we see, it will eventually end up where the north pole of your compass would point south, and then we'll stay that way, probably for five hundred thousand years, and then flip back the other way.
So the fact that my compass points north now it just happens to be like that. Now, at some point it's going to change, and it has changed before.
Yeah, there's a whole history of how this affected early navigation when the fourteen hundreds plus, right, especially when you live in Europe and you're at pretty high latitudes, that little difference matters whether the magnetic north is right on
the north pole, uh huh. And so this inability to actually tell where doe north was really one of the things that led the history of exploration of the world by the Europeans to be so so kind of random in a way where oh, yeah, sometimes we ended up in the wrong place and we thought it was somewhere else.
It's because the magnetic hole moved.
Yeah, the compass was just not a reliable way to navigate perfectly.
Okay, So that's the Earth's magnetic north pole and it's moving all over the place, and the spinning north poole of the Earth is also changing. Does this mean Santa is doomed to have to keep moving around forever, like maybe keep his toy workshop and reindeer stables in trailers. Well, it turns out there is a third North pool here on Earth, and that's the one defined by our GPS systems.
A lot of the expeditions in the late eighteen hundreds and early nineteen hundreds to the north and south pole of the Earth were driven by trying to find where the heck this actual magnetic North pole wash. And then they got there and realized, oh, it's moving.
Like I put a flag here last time, it's not here anymore.
Yeah, exactly, And that's part of why. Now we don't navigate by compass is, but we navigate with Global Positioning satellites right, GPS system. We've created a more reliable navigation pole than the magnetic north Oh.
That's a third pole. Now we have like a GPS pole exactly. Yeah.
Yeah, we have a way to navigate ourselves with respect to the GPS and that won't wobble with the Earth. It won't with the magnetic field. It's kind of a fixed thing that we can reference.
Okay, great, we can use GPS. Does that mean that we finally have a fixed North pole one that doesn't change, Not quite.
It might drift a little over time. The gravity field of the Earth is not perfectly symmetric, right, It's not the perfect round ball in terms of gravity. The equator is a little fatter than the poles because of us spinning.
You mean the equator has a different body type.
Yeah, yeah, yes, yes, the equator has a different body type. So if you have a satellite that's trying to go around the North Pole, uh huh, the equator will cause a little gravity that would yank it to be eventually be in an equatorial orbit.
Wait, you mean like our GPS satellite system could be kind of drifting or getting wobbled and we might not even know it. Yeah.
Maybe, And there are all sorts of asymmetries. There's this big bulge from the spinning of the equator, but then there's also just kind of random places that have more or less gravity. Huh. And they had something to do with the structure of the continents and the structure of the mantle and how much density there are in different places. So if you're over the Himalayas, the gravity is a little different than if you're over Iowa.
So now we have three poles on Earth. We have the spinning axes, the magnetic North Pole, and now we have this GPS reference and all three I mean, they're all tied together obviously through physics, but they're not necessarily the same or staying constant to each other.
Yeah, over longer pier then we probably care about. But if you're trying to navigate a fighter jet by GPS, you probably do care about.
But if you try to fly the same jet in one hundred thousand years, who knows if you'll end up in the same spot exactly.
If your instruments haven't updated their internal system.
You've literally shaken my world. Mad, I feel like I can't trust GPS anymore. Like I thought that was the gold standard. The Earth might be doing all kinds of crazy things inside of this GPS sphere.
I think we can very slowly, very slowly.
Well, I think to summarize, like, if you were looking for the North Pole, you could look it up in three different systems and you could end up in three different places.
Yeah, so the North Pole itself has a little mystery around it, right, uh huh. Depending on how you want to address it. It could be in a little bit different place. So that's why it's a good place for Santa.
It all makes sense. Santa has a degreen physics and planetary science, and he's like, where's the one place on Earth where it's going to be extra hard for people to find me? The North Pole?
Exactly, and especially because the North Pole is covered with sea ice. Right, uh huh, antarcticle, we have land, we have land at the South Pole, but the North Pole is ice, so that drifts around too a so, so yeah, I think it's it's a safe spot.
Now does that mean Santa has to move every couple of thousand years or do you think he likes the drifting part of it, like he's a drifter at heart.
Yes, Santa's a drifter at heart. Let the elves control the GPS system.
Oh my goodness, you said on a conspiracy theory. Maybe in a given year, if kids get a lot of GPS based toys, that's Santa trying to cover his tracks. Oh yeah, He's like, let them find me. Here's all these GPS A little do they know I'm not at the GPS North Pole?
Give them compasses that don't go the wrong no pole, Yeah, lead them astray. Yeah, so maybe this whole magnetic North Pole migrating so much is just a way of hiding the secret location of the workshop. Pretty much darker tone to Santa than I've ever heard before.
Do you think he lived in Antarctica then, like five hundred thousand years ago? Yeah?
Does he migrate with the migration of the magnetic spinpole or the physical spin pole?
He's like, well, I'm just waiting for the time where the North Pole points in Panama, and then I'll move to Panama in the tropics and live at the beach. Yeah, exactly, all right. Well, uh, dear Santa, if you're listening, please don't put me on your naughty list or divulging your North Pole secrets. But if you do, please don't put a piece of coal in my stocking. Instead, leave a magnet. I could use it to make a compass that'll work for at least a few hundred thousand years. And to
everyone else, thanks for joining us. Happy holidays for everyone here at sign Stuff. See you next time you've been listening to Science Stuff. The production of iHeartRadio written and produced by me or Hey Cham, edited by Rose Seguda executive producer Jerry Rowland and audio engineer and mixer Kasey Peckram. And you can follow me on social media. Just search for PhD Comics and the name of your favorite platform.
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