Speaker 1: Welcome to Bedtime Astronomy. Explore the wonders of the cosmos
Speaker 1: with our soothing Bedtime Astronomy podcast. Each episode offers a
Speaker 1: gentle journey through the stars, planets, and beyond, perfect for
Speaker 1: unwinding after a long day. Let's travel through the mysteries
Speaker 1: of the universe as you drift off into a peaceful
Speaker 1: slumber under the night sky.
Speaker 2: Imagine, imagine sending a probe to the absolute coldest, darkest
Speaker 2: edges of our Solar System. You're expecting to find a
Speaker 2: completely frozen static block of ice, right.
Speaker 3: Right, I mean, that's what the math and the textbooks
Speaker 3: basically told us to expect for decades exactly.
Speaker 2: But what if decades later you realize you might have
Speaker 2: actually been looking at an ocean of boiling magma the
Speaker 2: entire time.
Speaker 3: It's wild to even think about. It completely flips our
Speaker 3: entire understanding of planetary physics on its.
Speaker 2: Head, it really does. And you know, for almost forty years,
Speaker 2: our science textbooks, the classroom posters we all grew up
Speaker 2: looking at our whole conceptual framework for the outer Solar
Speaker 2: System might have just been lying to us.
Speaker 3: Yeah, unintentionally, lying, of course, but lying Nonetheless, We've been
Speaker 3: so incredibly confident in our labeling we really have.
Speaker 2: I mean, think about those classic planetary neighborhoods we learned
Speaker 2: about as kids. You've got the rocky inner planets here,
Speaker 2: this un earth Mars, Venus.
Speaker 3: Sure.
Speaker 2: Then you have the massive gas giants Jupiter and Saturn
Speaker 2: just dominating the middle.
Speaker 3: Vacuum cleaners of the Solar System.
Speaker 2: Yeah right. And then way out in the freezing dark,
Speaker 2: practically hovering right on the edge of interstellar space, you
Speaker 2: have Uranus and Niptune. And the label pointing to them
Speaker 2: has always been so definitive. They are the ice giants, and.
Speaker 3: It's a label that paints a very specific, very rigid
Speaker 3: picture for people. When you hear ice giant, your mind
Speaker 3: is essentially forced to imagine a dormant world, like a planetary.
Speaker 2: Deep freeze, a giant snowball, exactly.
Speaker 3: And for a really long time, the scientific community leaned
Speaker 3: heavily into that categorization because it fit the very limited
Speaker 3: observational data we had at the time, and quite frankly,
Speaker 3: it made the mathematics of planetary formation in the outer
Speaker 3: Solar System somewhat manageable to calculate.
Speaker 2: But as we know, science is entirely dependent on anomalist data. Right,
Speaker 2: Like when observations refuse to fit the established model, eventually
Speaker 2: that model just has to break.
Speaker 3: It has to break. And in this case, the model
Speaker 3: isn't just breaking, it's it's having a complete meltdown, literally literally.
Speaker 2: So today we are going to explore this fundamental rethinking
Speaker 2: of our own solar system. It's a massive paradigm shift
Speaker 2: proposed by a team of researchers at UCLA led by
Speaker 2: Edward D. Young in his colleagues, right, And.
Speaker 3: They are suggesting something that sounds almost like science fiction.
Speaker 3: They're saying that beneath the atmospheric clouds of Uranus and Neptune,
Speaker 3: we aren't going to find hundreds of thousands of miles
Speaker 3: of slushy frozen ice at all.
Speaker 2: No ice.
Speaker 3: No, Instead, we are likely looking at massive, violently churning
Speaker 3: ocean of liquid magma.
Speaker 2: Okay, wait, magma like volcanoes on Earth. Kind of magma.
Speaker 3: Exactly like that, but on a scale that is almost
Speaker 3: impossible to comprehend. It completely changes the paradigm. And what
Speaker 3: is so compelling about this UCLA study is that it
Speaker 3: isn't simply an exercise in being contrarian, just for the
Speaker 3: sake of it.
Speaker 2: You know, they're just trying to be edgy planetary scientists.
Speaker 3: No, not at all. This magma ocean model is attempting
Speaker 3: to solve two of the most glaring, incredibly frustrating puzzles
Speaker 3: in modern astronomy, specifically the bizarre magnetic fields and the
Speaker 3: completely inexplicable heat distribution of these two planets.
Speaker 2: Puzzles that have basically baffled people since the nineteen eighties.
Speaker 3: Exactly for decades, astronomers have essentially been trying to force
Speaker 3: a square peg into a round hole. They've been trying
Speaker 3: to make this static ice interior somehow explain highly dynamic,
Speaker 3: chaotic planetary behavior, because I.
Speaker 2: Mean, if a solid block of ice traps heat, what
Speaker 2: state of matter actually allows that deep primordial heat to escape?
Speaker 2: And how on Earth do you get complex twisting magnetic
Speaker 2: fields from a frozen core.
Speaker 3: You don't, You simply don't. And those are the exact
Speaker 3: physical contradictions that drove this new research.
Speaker 2: But before we dive headfirst into the magma, I think
Speaker 2: we need to understand how we got so locked into
Speaker 2: this ice giant mindset in the first place, because it's
Speaker 2: not like planetary scientists just looked at how far they
Speaker 2: were from the Sun and lazily assumed everything out there
Speaker 2: was a giant ice cube, right, There.
Speaker 3: Was actual methodology behind it, There was a logical progression
Speaker 3: based on the math.
Speaker 2: So walk us through that. How did the textbooks get
Speaker 2: written this way?
Speaker 3: Well, the math essentially forced early astronomers into a corner
Speaker 3: where ice seemed like the only plausible conclusion. So if
Speaker 3: you look at Jupiter and Saturn, their composition is primarily
Speaker 3: hydrogen and helium.
Speaker 2: Just massive balls of.
Speaker 3: Gas exactly because they formed close enough to the Sun
Speaker 3: and they gathered enough mass quickly enough to just sweep
Speaker 3: up massive amounts of these really light gases from the
Speaker 3: primordial solar nebula. They are the true gas giants.
Speaker 2: But Uranus and Neptune are a different story, very different.
Speaker 3: They are much smaller than Jupiter, but crucially they're significantly denser.
Speaker 2: Okay, so they couldn't just be made of pure hydrogen
Speaker 2: and helium. The sheer density implies there has to be
Speaker 2: much heavier stuff packed in there summer Precisely.
Speaker 3: The way you figure this out is, well, you calculate
Speaker 3: the planet's mass based on its gravitational pull on its moons,
Speaker 3: and then you calculate its volume based on its visual
Speaker 3: size through a telescope ener geometry, right, And when you
Speaker 3: divide mass by volume, you get this very specific intermediate density.
Speaker 3: It's much heavier than a pure gas giant, but it's
Speaker 3: still way lighter than a dense, rocky terrestrial planet like
Speaker 3: Earth or Mars.
Speaker 2: So they were looking for a Goldilocks material, something not
Speaker 2: too light, not too heavy exactly.
Speaker 3: So they ask themselves what fits that intermediate density profile,
Speaker 3: and in the context of the cosmic abundances of elements,
Speaker 3: what was actually available out there when the Solar System formed.
Speaker 3: The most likely candidates were volatile compounds.
Speaker 2: Meaning things like water, ammonia and methane.
Speaker 3: Yes, water ammonia and methan. And because the ambient temperature
Speaker 3: in that region of the Solar System is, you know,
Speaker 3: hundreds of degrees below zero, the assumption was that these
Speaker 3: compounds had to exist in a frozen or maybe heavily slushy.
Speaker 2: State, because obviously it's freezing out there, right.
Speaker 3: That was the foundational logic. So the traditional model posited
Speaker 3: this relatively thin outer atmosphere of hydrogen and helium acting
Speaker 3: like a blanket hiding a vast, incredibly thick mantle made
Speaker 3: entirely of these highly pressurized ices, and all that was
Speaker 3: wrapped around a smaller, rocky core.
Speaker 2: Okay, that makes sense on paper. But the crucial context here,
Speaker 2: and this is the thing that I think is almost
Speaker 2: impossible for the average person to really wrap their head around,
Speaker 2: is the sheer lack of actual empirical data we have
Speaker 2: to support that old model.
Speaker 3: Oh, the data drought is staggering.
Speaker 2: I mean, humanity has only visited these planets one single
Speaker 2: time once NASA's Voyager two spacecraft flew by Uranus in
Speaker 2: nineteen eighty six, and then it reached Neptune in nineteen
Speaker 2: eighty nine.
Speaker 3: That's it, and that's all we have. Every textbook, diagram,
Speaker 3: every CGI documentary rendering of their interiors you've ever seen
Speaker 3: essentially stems from those two incredibly brief encounters.
Speaker 2: It's wild to think about. Voyager two is obviously one
Speaker 2: of the greatest engineering achievements in human history, but we
Speaker 2: have to remember the context of its technology. The spacecraft
Speaker 2: was built in the nineteen seventies.
Speaker 3: It was recording data on actual magnetic tape.
Speaker 2: Yes, magnetic tape, and it wasn't even orbiting these planets.
Speaker 2: It was performing flybys. It was screaming past them at
Speaker 2: tens of thousands of miles per hour.
Speaker 3: It's an incredibly constrained snapshot.
Speaker 2: It's like trying to understand the entire complex ecosystem of
Speaker 2: the deep ocean by just quickly driving a speedboat over
Speaker 2: the surface of the water once in nineteen eighty six. Ye,
Speaker 2: you know, like you take a couple of polaroids as
Speaker 2: you zoom passed, and then you spend the next forty
Speaker 2: years trying to build a comprehensive, highly detailed model of
Speaker 2: the Marianas Trench based solely on those blurry photos.
Speaker 3: That is an excellent way to frame it. Obviously, the
Speaker 3: models you build from that are going to have massive,
Speaker 3: massive blind spots.
Speaker 2: So what did those brief polaroids actually show us, because
Speaker 2: clearly they saw something that didn't quite make sense.
Speaker 3: Well, Voyager two measured a few key things. It measured
Speaker 3: the atmospheric compositions at the very top layer. It recorded
Speaker 3: the thermal emissions, the heat radiating out into space, and crucially,
Speaker 3: it measured the planetary magnetic fields.
Speaker 2: And here's where it gets really interesting. The magnetic fields.
Speaker 3: Yes, it was that last measurement the magnetic field data
Speaker 3: that immediately threw the scientific community into a state of
Speaker 3: total confusion because the data simply did not align with
Speaker 3: the ice giant model they had constructed.
Speaker 2: Let's get into the mechanics of that, because this seems
Speaker 2: to be the first major thread that eventually unraveled the
Speaker 2: whole icy paradigm. Now, I'm familiar with Earth's magnetic field.
Speaker 2: It's what makes a compass work right, right, And magnetic
Speaker 2: north is relatively close to the actual geographic north pole.
Speaker 2: It's somewhat aligned with how the planet rotates. So what
Speaker 2: did Voyager two actually find when I looked at Uranus
Speaker 2: and Neptune?
Speaker 3: It found sheer chaos, absolute chaos. How so, Well, to
Speaker 3: understand why it was so anomalous, we have to look
Speaker 3: at how planetary magnetic fields are generated in the first place.
Speaker 3: They aren't just giant, permanent magnets sitting dead in the
Speaker 3: center of a planet. They are actively generated by a
Speaker 3: complex process called a planetary dynamo. A dynamo okay, yeah,
Speaker 3: And for a dynamo to work, you need a massive
Speaker 3: volume of electrically conductive fluid deep inside the planet, and
Speaker 3: that fluid has to be physically churning and convecting like
Speaker 3: boiling water exactly on Earth. That churning fluid is our
Speaker 3: liquid iron outer core. The planet rotates, the intense heat
Speaker 3: makes the liquid iron convect upwards, and then the Coriolis
Speaker 3: effect from the rotation twists that moving conductive fluid into
Speaker 3: these complex spiraling columns, and that movement generates a massive,
Speaker 3: relatively stable magnetic field that roughly aligns with our axis
Speaker 3: of rotation.
Speaker 2: Okay, so the rotation of the planet basically organizes the
Speaker 2: chaotic churning of the liquid metal into a neat structured,
Speaker 2: planetary scale magnetic field.
Speaker 3: Under normal circumstances. Yes, that's the ideal model. But Voyager
Speaker 3: two revealed that the magnetic fields of Uranus and Neptune
Speaker 3: are heavily tilted, I mean severely tilted. We're talking fifty
Speaker 3: nine degrees off the axis of rotation for Uranus.
Speaker 2: Wow, fifty nine degrees that's almost sideways.
Speaker 3: It's completely skewed, and for Neptune it's forty seven degrees.
Speaker 3: But wait, it gets weirder. Furthermore, the magnetic fields aren't
Speaker 3: even centered.
Speaker 2: What do you mean not centered?
Speaker 3: They don't originate from the geometric core. Of the planets.
Speaker 3: They are completely off kilter, practically emerging from the sides
Speaker 3: of the planets rather than the center.
Speaker 2: That makes no sense. So if we picture the planetary
Speaker 2: dynamo as a spinning top, Earth's dynamo is like a
Speaker 2: perfectly balanced top spinning upright. But Urinus in Neptune have
Speaker 2: dynamos that act like a spinning top with the heavyweight
Speaker 2: glued to one side. It's wobbling, it's chaotic, and it's
Speaker 2: completely unstable.
Speaker 3: That mechanical instability is the key issue here, because if
Speaker 3: Urinus in Neptune were primarily post of a thick mantle
Speaker 3: of water, ammonia, and methane ice, you run into a
Speaker 3: massive physical contradiction.
Speaker 2: Because ice isn't a churning fluid exactly.
Speaker 3: Even if we assume the extreme pressures in the interior
Speaker 3: create exotic forms of ice, like there's a theoretical state
Speaker 3: called superionic water, which is somewhat conductive, it still behaves
Speaker 3: far too rigidly. Ice by definition, resists the rapid turbulent
Speaker 3: convection required to produce a highly active dynamo. It's too stiff,
Speaker 3: way too stiff, And even if it could somehow convect slightly.
Speaker 3: A thick, uniform ice mantle should theoretically produce a much
Speaker 3: more centralized, neatly aligned magnetic field. It absolutely shouldn't produce
Speaker 3: the chaotic off center mess that Voyager two observed.
Speaker 2: So the physics just break entirely.
Speaker 3: The physical properties of ice simply do not support the
Speaker 3: magnetic reality of these worlds. It was a glaring contradiction
Speaker 3: from day one.
Speaker 2: And the magnetic field wasn't the only thing that refused
Speaker 2: to make sense, right, Yeah, there's also the glaring problem
Speaker 2: of how these planets handle heat.
Speaker 3: Oh yes, the thermal anomaly is arguably even more perplexing
Speaker 3: than the magnetic one. Because planets are not just cold,
Speaker 3: dead rocks floating in space. They possess immense internal heat.
Speaker 2: Where does that heat come from if there are so
Speaker 2: far from the sun.
Speaker 3: Some of it is primordial heat, its energy left over
Speaker 3: from the violent accretion process of their actual formation, you know,
Speaker 3: when countless clintesimals and space rocks smashed together over billions
Speaker 3: of years, converting all that kinetic energy into thermal energy.
Speaker 2: So just the violence of birth creates heat that lasts
Speaker 2: billions of years.
Speaker 3: Exactly, and some of it also comes from the slow
Speaker 3: gravitational contraction of the planet over time. But regardless of
Speaker 3: the source, this intense internal heat eventually has to make
Speaker 3: its way from the deep core up to the surface,
Speaker 3: where it can finally radiate out into the vacuum of space.
Speaker 2: And the way that heat naturally travels through a fluid
Speaker 2: is primarily through convection. Right just like a pot of
Speaker 2: soup on a stove, the hot material deep down becomes
Speaker 2: less dense, it rises toward the cooler surface, releases its
Speaker 2: heat because denser again, and sinks back down a continuous
Speaker 2: rolling cycle.
Speaker 3: That's it. Convection is the absolute primary engine of planetary
Speaker 3: heat transport. But here is where the old ice giant
Speaker 3: model completely fails again. A massive thick layer of pressurized ice,
Speaker 3: even slushy exotic ice, ax as a phenomenal thermal insulator.
Speaker 2: It's basically a giant planetary thermos.
Speaker 3: Yes, it severely dampens any convection. If Uranus and Neptune
Speaker 3: were truly ice giants, that thick icy mantle would essentially
Speaker 3: trap the primordial heat deep deep in the core. It
Speaker 3: wouldn't be able to escape efficiently.
Speaker 2: But that's not what we actually see when we look
Speaker 2: at them.
Speaker 3: Is it not at all? The surface temperatures and the
Speaker 3: specific infrared radiation profiles that Voyager two measured, and you
Speaker 3: know that our modern telescopes continue to observe today, they
Speaker 3: show a highly dynamic heat flow. It strongly implies active,
Speaker 3: vigorous convection from the inside out.
Speaker 2: I remember reading a crazy stat about Neptune. Doesn't it
Speaker 2: radiate way more heat than it even gets from the sun.
Speaker 3: It does. Neptune radiates more than twice as much energy
Speaker 3: into space as it receives from solar radiation. That massive
Speaker 3: amount of internal heat is escaping somehow, it is not
Speaker 3: being insulated by a static block of ice.
Speaker 2: It feels like this massive cosmic historical irony. We literally
Speaker 2: gave them this incredibly specific moniker ice giants that actively
Speaker 2: fundamentally contradicts the actual physics we are observing.
Speaker 3: It really is ironic.
Speaker 2: I mean, we are watching them generate complex, highly energetic
Speaker 2: magnetic field and we are measuring massive amounts of heat
Speaker 2: actively flowing out of their deep interiors. Both of those
Speaker 2: things require fluid, dynamic, chaotic movement. Yet we slapped the
Speaker 2: label on them that implies a frozen static insulatory state.
Speaker 2: The name itself basically became a psychological barrier to actually
Speaker 2: understanding the physics.
Speaker 3: Which is exactly why Edward Deyung and his team at
Speaker 3: UCLA decided they had to discard the label entirely. They
Speaker 3: approached the problem from a completely blank slate. They didn't ask,
Speaker 3: how can we somehow mathematically force ice to fit this
Speaker 3: weird data, right.
Speaker 2: Which is what people had been doing for decades exactly.
Speaker 3: Instead, they asked, what specific internal structure, regardless of our
Speaker 3: preconceived notions, naturally produces the magnetic and thermal signatures we
Speaker 3: actually see.
Speaker 2: They just followed the evidence.
Speaker 3: They did. They utilized highly advanced computer simulations tools that
Speaker 3: were completely unavailable to the scientists during the voyager era
Speaker 3: in the eighties. They use these massive supercomputers to model
Speaker 3: the deep interiors based purely on the raw laws of thermodynamics,
Speaker 3: fluid dynamics, and high pressure chemistry.
Speaker 2: Okay, let's unpack this, Yeah, because this leads us right
Speaker 2: to the core of this whole paradigm shift. The UCLA
Speaker 2: models completely toss out the traditional massive block of ice,
Speaker 2: and they replace it with a highly complex three layer
Speaker 2: internal architecture.
Speaker 3: Right. The three layer model is incredibly elegant, because it
Speaker 3: actually resolves all of those decades old contradictions. So if
Speaker 3: we were moving from the outside of the planet inward,
Speaker 3: the first layer is the atmosphere.
Speaker 2: Okay, so that part hasn't really changed.
Speaker 3: No, this is the one part of the old model
Speaker 3: that remains largely intact. It's a massive gaseous envelope composed
Speaker 3: primarily of hydrogen and helium, along with trace amounts of methane,
Speaker 3: which is actually what gives both planets their beautiful signature
Speaker 3: blue hues.
Speaker 2: Right, the blue we see in all the photos.
Speaker 3: Exactly and dynamically, this top layer is essentially responsible for
Speaker 3: the final stage of heat transport. It carries the internal
Speaker 3: thermal energy up to the upper atmosphere, where it finally
Speaker 3: radiates out into the vacuum of space.
Speaker 2: Okay, so the gas planket makes total sense. That's the
Speaker 2: part we can actually see through our telescopes. But what
Speaker 2: happens beneath that hydrogen and helium atmosphere Because in the
Speaker 2: old model, this is exactly where you'd hit that endless
Speaker 2: insulating wall of ice, right.
Speaker 3: But in the new UCLA model, beneath the atmosphere you
Speaker 3: enter the second layer, which they call the boundary layer.
Speaker 3: And it is so crucial to understand here that planetary
Speaker 3: interiors are not always sharply defined like the neat layers
Speaker 3: of an onion.
Speaker 2: It's not just gas and then a sudden hard floor.
Speaker 3: Not at all. At these extreme depths, the pressure and
Speaker 3: temperature are so intense that they alter the very nature
Speaker 3: of chemistry. So the boundary layer is this massive, highly
Speaker 3: pressurized transition zone. It is a complex, multi component chemical
Speaker 3: soup containing hydrogen, helium, magnesium, silicon, monoxide, and oxygen.
Speaker 2: Okay, I've have to pause on the chemistry there. Magnesium
Speaker 2: and silicon monoxide. Why are those specific elements so crucial?
Speaker 2: That sounds less like the inside of a frozen planet
Speaker 2: and way more like the inside of an industrial blast furnace.
Speaker 3: Well, it is very much like a blast furnace. The
Speaker 3: presence of magnesium in silicon is the absolute key indicator
Speaker 3: of what lies beneath them. Because in planetary science we
Speaker 3: deal extensively with this concept called missibility.
Speaker 2: Missibility like how well things mix exactly.
Speaker 3: It's essentially the ability of two different substances to mix together.
Speaker 3: Think of oil and water. They are immissible under normal
Speaker 3: conditions on Earth, right.
Speaker 2: They separate, right, the oil just floats on top.
Speaker 3: But when you introduce unimaginable extreme heat and millions of
Speaker 3: time the atmospheric pressure of Earth, substances that normally wouldn't
Speaker 3: ever mix begin to fundamentally dissolve into one another. The
Speaker 3: boundary layer is exactly that, a region where the lighter
Speaker 3: gases from the upper atmosphere are violently interacting with and
Speaker 3: dissolving into the heavier, rocky molten materials rising up from below.
Speaker 2: Oh wow, and those heavier molten materials are coming directly
Speaker 2: from the third layer, the main event.
Speaker 3: Yes, the basal magma ocean. It just sounds crazy to
Speaker 3: say out loud, I know, but according to these new simulations,
Speaker 3: the vast majority of the interior volume of uranus and
Speaker 3: neptune is not ice at all, but it deeply buried,
Speaker 3: violently churning ocean of liquid silicate magma, liquid iron, and
Speaker 3: dissolved hydrogen.
Speaker 2: I think this is the exact point where the average
Speaker 2: person's intuition about space just completely breaks down. We're talking
Speaker 2: about planets situated nearly three billion miles away from the Sun.
Speaker 2: The ambient temperature of the vacuum around them is roughly
Speaker 2: three hundred and fifty degrees fahrenheit belows ear.
Speaker 3: It's unimaginably cold. So how on Earth does a planet
Speaker 3: sitting in the literal freezing depths of the outer Solar
Speaker 3: System maintain a churning ocean of liquid rock and iron.
Speaker 2: It is a phenomenal question, and it requires us to
Speaker 2: completely separate the concept of surface temperature from internal thermodynamics.
Speaker 2: The internal heat of a planet carry interior has almost
Speaker 2: nothing to do with the Sun. It is a completely
Speaker 2: self contained energetic system.
Speaker 3: So it's surviving purely on that primordial heat you mentioned earlier,
Speaker 3: if the heat leftover from its violent berth billions of
Speaker 3: years ago.
Speaker 2: Primordial heat is the absolute foundation. Yes, when a planet forms,
Speaker 2: the kinetic energy of millions of asteroid sized bodies slamming
Speaker 2: together over millennia is converted into intense thermal energy. But
Speaker 2: the reason that heat is maintained as a boiling liquid
Speaker 2: magma ocean billions of a year later comes down to
Speaker 2: the sheer crushing force of gravity. The pressure exactly the
Speaker 2: immense mass of the hydrogen and helium atmosphere, combined with
Speaker 2: the dense boundary layer beneath it is pressing down on
Speaker 2: the core with unimaginable weight. We are talking about pressures
Speaker 2: millions of times greater than what we feel standing on
Speaker 2: the surface of Earth, and as any basic high school
Speaker 2: physics class teaches us, when you exponentially increase pressure, you
Speaker 2: exponentially increase temperature exactly.
Speaker 3: The extreme gravitational pressure essentially locks the primordial heat inside,
Speaker 3: keeping everything melted. But crucially, unlike a solid static block
Speaker 3: of ice, a liquid magma ocean is highly conductive and
Speaker 3: highly fluid.
Speaker 2: It can convect, which solves our heat problem.
Speaker 3: Yes, the intense heat at the very core of the
Speaker 3: planet warms the liquid, silicates and the iron, making them buoyant.
Speaker 3: The superheated magma rises toward the boundary layer, releases its
Speaker 3: thermal energy, cool slightly, it becomes denser, and sinks back down.
Speaker 3: This continuous, violent churning creates a massive planetary scale convection engine.
Speaker 2: So magma is physically carrying the heat from the deep
Speaker 2: core up to the boundary layer, and then the boundary
Speaker 2: layer transfers it to the gas atmosphere, which radiates it
Speaker 2: into space. The whole insulation problem of the ice model
Speaker 2: is just gone.
Speaker 3: The thermal equation finally balances perfectly but more importantly, the
Speaker 3: magma ocean model beautifully solves the magnetic anomaly as well.
Speaker 2: Right the off center wabbling spinning top exactly.
Speaker 3: Remember those chaotic, heavily tilted magnetic fields observed by Voyager
Speaker 3: two while a deep churning ocean of highly electrically conductive
Speaker 3: silicate magma and liquid iron violently convecting under extreme pressure.
Speaker 3: That is the exact physical mechanism required to generate a
Speaker 3: chaotic dynamo.
Speaker 2: It fits perfectly.
Speaker 3: It does. The complex fluid dynamics of liquid rock moving
Speaker 3: at those extreme depths naturally produce the skewed, highly asymmetrical
Speaker 3: magnetic signatures that the old ice model completely failed to explain.
Speaker 2: It's so elegant. So that boundary layer basically acts like
Speaker 2: a highly pressurized chemical filter. It allows the heat to
Speaker 2: transfer upward, but it interacts with the magma just enough
Speaker 2: to keep the massive liquid ocean contained below, all while
Speaker 2: feeding those chaotic magnetic loops.
Speaker 3: That's a great summary. Yeah, the data from Voyager two
Speaker 3: wasn't wrong. Our fundamental assumption about what state of matter
Speaker 3: existed at those pressures was just wrong.
Speaker 2: And realizing that error, it feels like it opens up
Speaker 2: an entirely new avenue of after physics because the implications
Speaker 2: of this UCLA study they don't just stop at the
Speaker 2: edge of our Solar system.
Speaker 3: Oh not at all. If we connect this to the
Speaker 3: bigger picture, redefining Uranus and Neptune might actually be the
Speaker 3: single most important breakthrough we've had for understanding the rest
Speaker 3: of the galaxy.
Speaker 2: That is a massive statement. I mean, how does a
Speaker 2: magma ocean on Neptune help us understand the Milky Way?
Speaker 3: It all comes down to planetary demographics. Over the last
Speaker 3: two decades, thanks to incredibly sensitive instruments like the Kepler
Speaker 3: Space Telescope, we have discovered thousands of exoplanets orbiting other
Speaker 3: stars right the exoplanet boom exactly. And when astronomers compile
Speaker 3: the census of these distant worlds, they use detection methods
Speaker 3: like planetary transits.
Speaker 2: That's when they measure the slight dimming of starlight as
Speaker 2: a planet passes in front of its host star. Right.
Speaker 3: The transit method allows us to calculate their physical size
Speaker 3: and their orbital periods. And what we have found through
Speaker 3: all these surveys is that the galaxy is absolutely dominated
Speaker 3: by one specific class of planet, a class that we
Speaker 3: call sub neptunes.
Speaker 2: I've heard the term sub neptune thrown around in various
Speaker 2: exoplanet surveys, but what exactly constitutes one? Are we just
Speaker 2: talking about physical size or is it an assumption about
Speaker 2: their composition.
Speaker 3: It's primarily a size classification, but one that strongly hints
Speaker 3: at their internal composition. A sub neptune is defined as
Speaker 3: an exoplanet with a radius roughly between one point five
Speaker 3: and four times the radius of Earth.
Speaker 2: Okay, so bigger than us, smaller than the gas giants.
Speaker 3: Precisely, they sit right in the middle of this major
Speaker 3: planetary demographic gap. They are significantly larger and more massive
Speaker 3: than rocky terrestrial worlds like Earth or Venus, but they're
Speaker 3: definitively smaller than massive gas giants like Jupiter or Saturn.
Speaker 2: Which brings up a glaring, almost absurd cosmic irony to me.
Speaker 2: If sub neptunes are literally the most common type of
Speaker 2: planet in the entire galaxy, why don't we have one?
Speaker 2: It's so frustrating, right, we have small, rocky planets, we
Speaker 2: have massive gas giants, and we have Urinus and Neptune,
Speaker 2: which sit just slightly above that sub neptune size. Cutoff,
Speaker 2: but we don't have a true textbook sub neptune in
Speaker 2: our own backyard to easily study it.
Speaker 3: Is arguably one of the most frustrating blind spots in
Speaker 3: all of exoplanetary science, because we don't have a local analog.
Speaker 3: Understanding how sub neptunes form, what their internal structures actually
Speaker 3: look like, and how their atmospheres evolve has been heavily
Speaker 3: reliant on theoretical guesswork.
Speaker 2: We're just throwing darts in the dark pretty much.
Speaker 3: Are they scaled up rocky super earths with incredibly thick
Speaker 3: atmospheres or are they scaled down gas giants with massive,
Speaker 3: crushing hydrogen envelopes. Until now, we just haven't had a
Speaker 3: reliable local baseline to compare them to.
Speaker 2: But the UCLA study changes that baseline completely, Because if
Speaker 2: you're in this in Neptune, aren't unique, weird, anomalous balls
Speaker 2: of ice, but rather complex magma filled worlds. How does
Speaker 2: that apply to the sub neptunes that are light years away.
Speaker 3: Well, the researchers fundamentally argue that the physics of planetary
Speaker 3: formation are universal. A planet's basic internal chemistry and its
Speaker 3: physical state shouldn't be drastically different. Simply because it formed
Speaker 3: around a different star. The physics of pressure and heat
Speaker 3: are the same everywhere. So the brilliant insight of the
Speaker 3: Young study is that the atmospheric signatures we are just
Speaker 3: now beginning to detect on distant sub neptunes using super
Speaker 3: advanced instruments like the James Web Space Telescope, those signatures
Speaker 3: closely resemble the predicted atmospheric chemistry of a planet with
Speaker 3: a deep, boiling magma ocean.
Speaker 2: Oh wow, wait, so this implies that the boundary layer
Speaker 2: we discussed earlier, that violent transition zone where magnesium and
Speaker 2: silicon monoxide are interacting with the hydrogen atmosphere, that isn't
Speaker 2: just a quirk of Urinus, No, it's a universal mechanism exactly.
Speaker 3: The magma ocean and its complex boundary layer pose very specific,
Speaker 3: very rigid chemical constraints on the atmosphere above it. As
Speaker 3: the magma violently churns and interacts with the hydrogen envelope,
Speaker 3: it physically dictates what chemical compounds are absorbed into the magma,
Speaker 3: what is outgassed into the air, and ultimately what the
Speaker 3: upper atmosphere looks like to our telescopes here on Earth.
Speaker 2: So the UCLA studies basically suggesting that Uranus and Neptune
Speaker 2: are the perfect scaled up analogs for the most common
Speaker 2: planets in the universe.
Speaker 3: They are our cosmic Rosetta stone.
Speaker 2: That is incredible. If we can perfectly model the interactions
Speaker 2: between the magma ocean and the atmosphere on Neptune, we
Speaker 2: can apply those exact same thermodynamic and chemical equations to
Speaker 2: translate the fuzzy atmospheric data we receive from sub Neptunes
Speaker 2: thousands of light years away.
Speaker 3: Yes, we aren't just solving a localized anomaly in our
Speaker 3: own Solar system anymore. We are literally unlocking the architectural
Speaker 3: blueprint for the vast majority of planetary systems in the
Speaker 3: Milky Way.
Speaker 2: It completely unifies our understanding of planetary evolution. It suggests
Speaker 2: this beautiful continuum like Instead of treating ice giants as
Speaker 2: this bizarre, isolated category of planets that only exist in
Speaker 2: the deep frieze of the outer Solar System, we can
Speaker 2: integrate them into a much broader, galaxy wide understanding of
Speaker 2: how intermediate mass planets form, how they trap heat, and
Speaker 2: how they evolve over billions of years.
Speaker 3: It's incredibly exciting from a theoretical standpoint. It ties everything together.
Speaker 2: It really does, but it inevitably brings us to the
Speaker 2: hardest part of the scientific process. We have this elegant,
Speaker 2: mathematically sound computer model from UCLA. It neatly solves the
Speaker 2: magnetic field chaos, it perfectly balances the heat transport equations,
Speaker 2: and it completely bridges the gap to exoplanetary science. Right
Speaker 2: but at the end of the day, a computer model
Speaker 2: is still just a model. How do we definitively prove
Speaker 2: that there is an ocean of liquid fire churning beneath
Speaker 2: the clouds of Uranus. I mean, we can't just stare
Speaker 2: at the math forever. We have to know for sure.
Speaker 3: No, we cannot just stare at the math. Empirical validation
Speaker 3: is the final, non negotiable hurdle in all of planetary science.
Speaker 3: And as we noted at the beginning of our discussion,
Speaker 3: humanity has not physically visited these worlds since the Reagan.
Speaker 2: Administration, which is painful to think about it is.
Speaker 3: And there are currently no active, fully funded metal bending
Speaker 3: space missions on the manifest to return to the outer
Speaker 3: Solar System right now. The tyranny of distance, combined with
Speaker 3: the sheer immense budget required for deep space exploration means
Speaker 3: that these planets have been largely and tragically neglected.
Speaker 2: It is endlessly frustrating to think that the literal keys
Speaker 2: to understanding the entire galaxy are sitting right there in
Speaker 2: our own Solar system and we just aren't looking at them.
Speaker 2: But I know the planetary science community hasn't given up.
Speaker 2: There have to be mission concepts on the drawing board.
Speaker 2: If a space agency decided to fund a return trip tomorrow,
Speaker 2: what would that mission actually look like?
Speaker 3: Oh, the scientific community is actually highly organized on this
Speaker 3: exact front. Every ten years, planetary scientists get together and
Speaker 3: produce what is called a decatal survey. It basically outlines
Speaker 3: the absolute highest priorities for future exploration for the next decade.
Speaker 2: Right it's their ultimate wishless.
Speaker 3: Exactly, And in recent years, returning to the outer planets
Speaker 3: has skyrocketed straight to the top of that list. The
Speaker 3: most prominent, fully fleshed out mission concept that is currently
Speaker 3: seeking approval is known as the Urinus Orbiter and Probe
Speaker 3: or UOP.
Speaker 2: The UOP, and what makes this concept so vital is
Speaker 2: that it fundamentally changes the nature of the encounter. Because
Speaker 2: Voyager two is just a fly by, it had mere
Speaker 2: hours to gather data before it was hurled out into
Speaker 2: interstellar space, but the UOP is designed to stay.
Speaker 3: The shift from a quick flyby to a sustained orbiter
Speaker 3: is monumental. The UOP concept involves a massive primary spacecraft
Speaker 3: that would utilize a technique called propulsive orbit.
Speaker 2: Insertion, meaning it fires its engines backwards to slow down.
Speaker 3: Right, it fires its engines to decelerate enough to actually
Speaker 3: be captured by Uranus' gravity, and once it's in orbit,
Speaker 3: it would spend years conducting us sustained, highly comprehensive analysis
Speaker 3: of the planet so.
Speaker 2: It could really map that weird magnetic field exactly.
Speaker 3: It would map the chaotic magnetic field from every conceivable
Speaker 3: angle over a long period of time, specifically looking for
Speaker 3: the minute fluctuations that would definitively prove the existence of
Speaker 3: a confecting magma dynamo below. And it would utilize advanced
Speaker 3: infrared spectrometers to map the global heat flow, pinpointing exactly
Speaker 3: how that thermal energy is escaping the interior.
Speaker 2: But the orbiter is only half of the UOP mission.
Speaker 2: The probe aspect is the part that genuinely sounds like
Speaker 2: something straight out of science fiction.
Speaker 3: It is arguably the most daring engineering challenge currently proposed
Speaker 3: in modern planetary science. The UOP would physically detach a
Speaker 3: highly shielded atmospheric probe and send it on a direct,
Speaker 3: intentional collision course with uranus.
Speaker 2: I really want to break down the sheer mechanical terror
Speaker 2: of that descent, because it isn't just dropping a GoPro
Speaker 2: into the clouds. The probe has to survive plunging into
Speaker 2: an atmosphere moving at supersonic speeds while the atmosphere of
Speaker 2: pressure exponentially increases around it every single second.
Speaker 3: The engineering constraints are extreme. The probe would hit the
Speaker 3: upper atmosphere at thousands of miles per hour, relying on
Speaker 3: a highly advanced a blade of heat shield to just
Speaker 3: survive the initial friction of.
Speaker 2: Entry, which is going to generate insane.
Speaker 3: Heat, incredible heat. Once it finally discelerates enough, it would
Speaker 3: deploy a massive parachute system and begin a slow, terrifying
Speaker 3: descent deep through the hydrogen and helium cloud layers, and
Speaker 3: as it falls onboard, mass spectrometers and sensors would be
Speaker 3: furiously tasting the chemistry of the atmosphere in real time.
Speaker 2: It's actively sniffing the air as it falls.
Speaker 3: Yes, it would measure the exact isotopic ratios of the gases,
Speaker 3: the temperature gradients, and the pressure curves.
Speaker 2: So it's basically searching for the chemical signatures of the
Speaker 2: boundary layer we talked about earlier. It's looking for the
Speaker 2: trace elements that the magmotion is actively off gasing into
Speaker 2: the upper atmosphere.
Speaker 3: Exactly. It is looking for the empirical fingerprints of the mast.
Speaker 3: And the hardest part is it has to relay all
Speaker 3: of that massive data telemetry back up to the orbiter
Speaker 3: using radio transmitters, fighting through the thick, increasingly dense plasma
Speaker 3: of the lower atmosphere before the crushing pressure of the
Speaker 3: planet finally breaches the hull and destroys the probe.
Speaker 2: Entirely, it is a literal suicide mission for the hardware.
Speaker 3: It is, but it would provide the indisputable ground truth
Speaker 3: data that these computer models crave. It would tell us
Speaker 3: once and for all if UCLA is right.
Speaker 2: And we shouldn't leave Neptune out of the conversation entirely.
Speaker 2: I know there is a parallel, albeit maybe slightly less
Speaker 2: developed mission concept for the eighth planet.
Speaker 3: As well, yes there is. It's known as the Neptune Odyssey.
Speaker 3: It operates on a very similar architecture to the UOP,
Speaker 3: an advanced orbiter designed to deeply study the atmospheric dynamics,
Speaker 3: the thermal emissions, and the magnetic anomalies of Neptune. And crucially,
Speaker 3: both the UOP and Neptune Odyssey concepts place a massive
Speaker 3: emphasis on studying the moons that surround them giants.
Speaker 2: Which might seem like a tangent to some people, but
Speaker 2: the moons are actually critical to understanding the inside of
Speaker 2: the planets themselves right.
Speaker 3: They are entirely interconnected. You see, planetary moons essentially act
Speaker 3: as external gravitational probes. As a spacecraft orbits Uranus or Neptune.
Speaker 3: The complex gravitational tug of war between the massive planet
Speaker 3: and its various moons causes minute, measurable shifts in the
Speaker 3: spacecraft's trajectory.
Speaker 2: So you can track the wabble of the spacecraft right.
Speaker 3: By tracking those tiny orbible deviations over years, scientists can
Speaker 3: reverse engineer the exact density and mass distribution inside the planet.
Speaker 3: If there is a dense, churning ocean of heavy silicate
Speaker 3: magma down there, the Moon's gravitational interactions will betray its
Speaker 3: presence to the orbiter.
Speaker 2: Plus, the moons themselves are just bizarre, like Triton around
Speaker 2: Neptune has active cryovulcanism, literal ice volcanoes erupting in deep space,
Speaker 2: and Miranda around Urinus looks like it was shattered into
Speaker 2: pieces and glued back together. With these sheer cliffs that
Speaker 2: are miles high.
Speaker 3: They are fascinating worlds in their own right.
Speaker 2: Yes, studying how the tidal heating from the main planets
Speaker 2: physically powers the geology of those weird moons, I mean
Speaker 2: that gives us even more data about the energy systems
Speaker 2: of the entire planetary neighborhood exactly.
Speaker 3: The interconnectedness of the system is what makes sustained long
Speaker 3: term observations so vital. We simply cannot understand the core
Speaker 3: without understanding the atmosphere, and we cannot fully understand the
Speaker 3: planet without understanding how it gravitationally manipulates its moons.
Speaker 2: The stakes for these proposed missions just feel incredibly high.
Speaker 2: I mean, we're talking about designing intricate spacecraft that will
Speaker 2: take a decade just to build and another decade just
Speaker 2: to travel. The billions of miles for us empty space
Speaker 2: to reach their destinations.
Speaker 3: It's a generational commitment, it really is.
Speaker 2: We are relying entirely on the precision of human engineering
Speaker 2: and the predictive power of theoretical physics. We are essentially
Speaker 2: betting billions of dollars and the literal careers of countless
Speaker 2: scientists on the mathematical probability that an ocean of fire
Speaker 2: exists inside a world of ice.
Speaker 3: But you know, that is the fundamental essence of deep
Speaker 3: space exploration. The mathematical anomalies tell us exactly where the
Speaker 3: mysteries are hiding. The computer models provide a map of
Speaker 3: what might be physically possible, and then eventually human curiosity
Speaker 3: simply compels us to build the machine, launch it into
Speaker 3: the dark, and go see for ourselves if the models
Speaker 3: were right.
Speaker 2: It is an unbelievable intellectual journey we've taken today. We
Speaker 2: started with two planets that we all thought we understood
Speaker 2: so perfectly, the cold, static blue ice giants frozen on
Speaker 2: the edges of our childhood classroom.
Speaker 3: Posters, the dormant worlds right.
Speaker 2: We've explored how the limitations of nineteen eighties technology created
Speaker 2: a compelling but ultimately highly flawed illusion of total comprehension.
Speaker 2: We've broken down the bizarre magnetic chaos and the thermodynamic
Speaker 2: contradictions that simply refuse to fit the established.
Speaker 3: Narrative, the anomalies that broke the model.
Speaker 2: Exactly, and through the lens of modern astrophysics and the
Speaker 2: incredible work at UCLA, we've stripped away the ice entirely
Speaker 2: and rebuilt these worlds from the core or outward. We've
Speaker 2: replaced the static deep freeze with dynamic violently churning unimaginably
Speaker 2: hot magma oceans buffered by exotic chemical transition zones.
Speaker 3: It's a much more violent, active.
Speaker 2: Picture, it is. And in doing so, we've realized that
Speaker 2: unlocking the fiery secrets of Uranus and Neptune provides us
Speaker 2: with the ultimate cosmic blueprint for understanding the most abundant
Speaker 2: exoplanets in the entire galaxy.
Speaker 3: It really is a profound shift in perspective, and I
Speaker 3: think it serves as a powerful reminder of how scientific
Speaker 3: progress actually functions. In reality. Anomalist data like a magnetic
Speaker 3: field that sets fifty nine degrees off axis, or a
Speaker 3: heat signature that completely defies the insulatory properties of ice,
Speaker 3: that data is never something to be ignored, minimized, or
Speaker 3: forced into an outdated model.
Speaker 2: You can't just sweep it under the rug, exactly.
Speaker 3: It is the exact thread that, when you finally have
Speaker 3: the technological capability and the theoretical courage to actually pull it,
Speaker 3: it unravels our entire previous understanding and leads us to
Speaker 3: a much deeper, much more complex truth. The original ice
Speaker 3: giant model wasn't a failure of science necessarily, it was
Speaker 3: the absolutely necessary stepping stone that provided the foundation for
Speaker 3: us to eventually discover the magma.
Speaker 2: That is the absolute perfect way to frame it. Science
Speaker 2: is just a continuous, messy process of refining our models
Speaker 2: until they finally stop breaking. And that leads me with
Speaker 2: one final thought, something for you to chew on long
Speaker 2: after we wrap up this discussion. If we could fundamentally
Speaker 2: mischaracterize two of our closest largest celestial neighbors for nearly
Speaker 2: forty years, literally calling them frozen ice, when the math
Speaker 2: now strongly suggests they might actually be oceans of turning fire.
Speaker 2: What other established facts in our textbooks, foundational things we
Speaker 2: take for granted every single day, are just waiting for
Speaker 2: a new generation of scientists to come along, look at
Speaker 2: the anomalous data and melt them away.