WEBVTT 1 00:00:03.399 --> 00:00:07.719 Welcome to Bedtime Astronomy. Explore the wonders of the cosmos 2 00:00:07.759 --> 00:00:12.279 with our soothing Bedtime Astronomy podcast. Each episode offers a 3 00:00:12.359 --> 00:00:16.320 gentle journey through the stars, planets, and beyond, perfect for 4 00:00:16.399 --> 00:00:20.239 unwinding after a long day. Let's travel through the mysteries 5 00:00:20.239 --> 00:00:22.440 of the universe as you drift off into a peaceful 6 00:00:22.480 --> 00:00:23.839 slumber under the night sky. 7 00:00:27.000 --> 00:00:32.240 Imagine, imagine sending a probe to the absolute coldest, darkest 8 00:00:32.320 --> 00:00:35.560 edges of our Solar System. You're expecting to find a 9 00:00:35.640 --> 00:00:39.840 completely frozen static block of ice, right. 10 00:00:39.759 --> 00:00:41.920 Right, I mean, that's what the math and the textbooks 11 00:00:41.960 --> 00:00:44.799 basically told us to expect for decades exactly. 12 00:00:45.240 --> 00:00:48.119 But what if decades later you realize you might have 13 00:00:48.159 --> 00:00:50.640 actually been looking at an ocean of boiling magma the 14 00:00:50.799 --> 00:00:51.439 entire time. 15 00:00:51.640 --> 00:00:54.960 It's wild to even think about. It completely flips our 16 00:00:55.159 --> 00:00:57.759 entire understanding of planetary physics on its. 17 00:00:57.640 --> 00:01:01.320 Head, it really does. And you know, for almost forty years, 18 00:01:01.840 --> 00:01:05.599 our science textbooks, the classroom posters we all grew up 19 00:01:05.599 --> 00:01:09.040 looking at our whole conceptual framework for the outer Solar 20 00:01:09.040 --> 00:01:10.680 System might have just been lying to us. 21 00:01:10.760 --> 00:01:14.560 Yeah, unintentionally, lying, of course, but lying Nonetheless, We've been 22 00:01:14.599 --> 00:01:17.359 so incredibly confident in our labeling we really have. 23 00:01:17.439 --> 00:01:19.879 I mean, think about those classic planetary neighborhoods we learned 24 00:01:19.879 --> 00:01:22.439 about as kids. You've got the rocky inner planets here, 25 00:01:22.480 --> 00:01:24.079 this un earth Mars, Venus. 26 00:01:24.200 --> 00:01:24.480 Sure. 27 00:01:24.599 --> 00:01:27.640 Then you have the massive gas giants Jupiter and Saturn 28 00:01:28.159 --> 00:01:29.879 just dominating the middle. 29 00:01:29.760 --> 00:01:31.400 Vacuum cleaners of the Solar System. 30 00:01:31.519 --> 00:01:34.799 Yeah right. And then way out in the freezing dark, 31 00:01:35.040 --> 00:01:38.519 practically hovering right on the edge of interstellar space, you 32 00:01:38.599 --> 00:01:42.159 have Uranus and Niptune. And the label pointing to them 33 00:01:42.359 --> 00:01:46.439 has always been so definitive. They are the ice giants, and. 34 00:01:47.040 --> 00:01:49.879 It's a label that paints a very specific, very rigid 35 00:01:49.920 --> 00:01:53.560 picture for people. When you hear ice giant, your mind 36 00:01:53.640 --> 00:01:58.239 is essentially forced to imagine a dormant world, like a planetary. 37 00:01:57.680 --> 00:01:59.959 Deep freeze, a giant snowball, exactly. 38 00:02:00.239 --> 00:02:02.920 And for a really long time, the scientific community leaned 39 00:02:02.959 --> 00:02:06.879 heavily into that categorization because it fit the very limited 40 00:02:06.920 --> 00:02:10.159 observational data we had at the time, and quite frankly, 41 00:02:10.199 --> 00:02:12.680 it made the mathematics of planetary formation in the outer 42 00:02:12.719 --> 00:02:14.960 Solar System somewhat manageable to calculate. 43 00:02:15.159 --> 00:02:19.080 But as we know, science is entirely dependent on anomalist data. Right, 44 00:02:19.159 --> 00:02:23.120 Like when observations refuse to fit the established model, eventually 45 00:02:23.120 --> 00:02:24.319 that model just has to break. 46 00:02:24.520 --> 00:02:26.280 It has to break. And in this case, the model 47 00:02:26.319 --> 00:02:30.120 isn't just breaking, it's it's having a complete meltdown, literally literally. 48 00:02:30.759 --> 00:02:33.879 So today we are going to explore this fundamental rethinking 49 00:02:33.919 --> 00:02:37.360 of our own solar system. It's a massive paradigm shift 50 00:02:37.520 --> 00:02:40.879 proposed by a team of researchers at UCLA led by 51 00:02:41.039 --> 00:02:43.520 Edward D. Young in his colleagues, right, And. 52 00:02:43.479 --> 00:02:46.000 They are suggesting something that sounds almost like science fiction. 53 00:02:46.080 --> 00:02:49.280 They're saying that beneath the atmospheric clouds of Uranus and Neptune, 54 00:02:49.319 --> 00:02:51.800 we aren't going to find hundreds of thousands of miles 55 00:02:51.800 --> 00:02:53.719 of slushy frozen ice at all. 56 00:02:53.879 --> 00:02:54.280 No ice. 57 00:02:54.479 --> 00:02:59.240 No, Instead, we are likely looking at massive, violently churning 58 00:02:59.400 --> 00:03:01.319 ocean of liquid magma. 59 00:03:01.439 --> 00:03:05.000 Okay, wait, magma like volcanoes on Earth. Kind of magma. 60 00:03:04.639 --> 00:03:06.840 Exactly like that, but on a scale that is almost 61 00:03:06.840 --> 00:03:10.240 impossible to comprehend. It completely changes the paradigm. And what 62 00:03:10.360 --> 00:03:13.800 is so compelling about this UCLA study is that it 63 00:03:13.879 --> 00:03:16.759 isn't simply an exercise in being contrarian, just for the 64 00:03:16.800 --> 00:03:17.319 sake of it. 65 00:03:17.479 --> 00:03:20.080 You know, they're just trying to be edgy planetary scientists. 66 00:03:20.159 --> 00:03:22.879 No, not at all. This magma ocean model is attempting 67 00:03:22.919 --> 00:03:26.520 to solve two of the most glaring, incredibly frustrating puzzles 68 00:03:26.520 --> 00:03:30.240 in modern astronomy, specifically the bizarre magnetic fields and the 69 00:03:30.240 --> 00:03:33.879 completely inexplicable heat distribution of these two planets. 70 00:03:33.879 --> 00:03:37.360 Puzzles that have basically baffled people since the nineteen eighties. 71 00:03:37.560 --> 00:03:41.000 Exactly for decades, astronomers have essentially been trying to force 72 00:03:41.039 --> 00:03:44.000 a square peg into a round hole. They've been trying 73 00:03:44.000 --> 00:03:49.599 to make this static ice interior somehow explain highly dynamic, 74 00:03:49.719 --> 00:03:53.759 chaotic planetary behavior, because I. 75 00:03:53.719 --> 00:03:56.759 Mean, if a solid block of ice traps heat, what 76 00:03:56.960 --> 00:04:01.360 state of matter actually allows that deep primordial heat to escape? 77 00:04:01.400 --> 00:04:04.280 And how on Earth do you get complex twisting magnetic 78 00:04:04.280 --> 00:04:05.560 fields from a frozen core. 79 00:04:05.879 --> 00:04:08.719 You don't, You simply don't. And those are the exact 80 00:04:08.719 --> 00:04:11.000 physical contradictions that drove this new research. 81 00:04:11.159 --> 00:04:14.080 But before we dive headfirst into the magma, I think 82 00:04:14.120 --> 00:04:16.160 we need to understand how we got so locked into 83 00:04:16.199 --> 00:04:19.399 this ice giant mindset in the first place, because it's 84 00:04:19.399 --> 00:04:21.839 not like planetary scientists just looked at how far they 85 00:04:21.839 --> 00:04:24.439 were from the Sun and lazily assumed everything out there 86 00:04:24.519 --> 00:04:26.079 was a giant ice cube, right, There. 87 00:04:26.000 --> 00:04:28.759 Was actual methodology behind it, There was a logical progression 88 00:04:28.759 --> 00:04:29.480 based on the math. 89 00:04:29.600 --> 00:04:31.639 So walk us through that. How did the textbooks get 90 00:04:31.639 --> 00:04:32.319 written this way? 91 00:04:32.560 --> 00:04:36.160 Well, the math essentially forced early astronomers into a corner 92 00:04:36.199 --> 00:04:41.120 where ice seemed like the only plausible conclusion. So if 93 00:04:41.120 --> 00:04:44.680 you look at Jupiter and Saturn, their composition is primarily 94 00:04:44.920 --> 00:04:47.120 hydrogen and helium. 95 00:04:46.519 --> 00:04:47.920 Just massive balls of. 96 00:04:47.879 --> 00:04:50.639 Gas exactly because they formed close enough to the Sun 97 00:04:50.680 --> 00:04:53.759 and they gathered enough mass quickly enough to just sweep 98 00:04:53.839 --> 00:04:56.560 up massive amounts of these really light gases from the 99 00:04:56.600 --> 00:04:59.839 primordial solar nebula. They are the true gas giants. 100 00:05:00.040 --> 00:05:03.040 But Uranus and Neptune are a different story, very different. 101 00:05:03.079 --> 00:05:07.800 They are much smaller than Jupiter, but crucially they're significantly denser. 102 00:05:07.959 --> 00:05:10.680 Okay, so they couldn't just be made of pure hydrogen 103 00:05:10.720 --> 00:05:13.480 and helium. The sheer density implies there has to be 104 00:05:13.600 --> 00:05:16.079 much heavier stuff packed in there summer Precisely. 105 00:05:16.480 --> 00:05:19.360 The way you figure this out is, well, you calculate 106 00:05:19.399 --> 00:05:22.600 the planet's mass based on its gravitational pull on its moons, 107 00:05:22.800 --> 00:05:25.519 and then you calculate its volume based on its visual 108 00:05:25.560 --> 00:05:29.079 size through a telescope ener geometry, right, And when you 109 00:05:29.120 --> 00:05:33.360 divide mass by volume, you get this very specific intermediate density. 110 00:05:34.000 --> 00:05:37.079 It's much heavier than a pure gas giant, but it's 111 00:05:37.120 --> 00:05:41.360 still way lighter than a dense, rocky terrestrial planet like 112 00:05:41.480 --> 00:05:42.560 Earth or Mars. 113 00:05:42.680 --> 00:05:44.839 So they were looking for a Goldilocks material, something not 114 00:05:44.879 --> 00:05:46.439 too light, not too heavy exactly. 115 00:05:46.639 --> 00:05:50.319 So they ask themselves what fits that intermediate density profile, 116 00:05:50.639 --> 00:05:53.519 and in the context of the cosmic abundances of elements, 117 00:05:53.600 --> 00:05:56.160 what was actually available out there when the Solar System formed. 118 00:05:56.519 --> 00:06:00.480 The most likely candidates were volatile compounds. 119 00:06:00.120 --> 00:06:02.519 Meaning things like water, ammonia and methane. 120 00:06:02.600 --> 00:06:07.199 Yes, water ammonia and methan. And because the ambient temperature 121 00:06:07.279 --> 00:06:09.360 in that region of the Solar System is, you know, 122 00:06:09.519 --> 00:06:12.720 hundreds of degrees below zero, the assumption was that these 123 00:06:12.759 --> 00:06:16.439 compounds had to exist in a frozen or maybe heavily slushy. 124 00:06:16.079 --> 00:06:18.399 State, because obviously it's freezing out there, right. 125 00:06:18.279 --> 00:06:21.160 That was the foundational logic. So the traditional model posited 126 00:06:21.199 --> 00:06:25.040 this relatively thin outer atmosphere of hydrogen and helium acting 127 00:06:25.079 --> 00:06:28.439 like a blanket hiding a vast, incredibly thick mantle made 128 00:06:28.600 --> 00:06:32.000 entirely of these highly pressurized ices, and all that was 129 00:06:32.000 --> 00:06:33.879 wrapped around a smaller, rocky core. 130 00:06:34.199 --> 00:06:37.600 Okay, that makes sense on paper. But the crucial context here, 131 00:06:37.639 --> 00:06:39.279 and this is the thing that I think is almost 132 00:06:39.319 --> 00:06:42.120 impossible for the average person to really wrap their head around, 133 00:06:42.560 --> 00:06:46.399 is the sheer lack of actual empirical data we have 134 00:06:46.639 --> 00:06:48.000 to support that old model. 135 00:06:48.639 --> 00:06:51.480 Oh, the data drought is staggering. 136 00:06:51.639 --> 00:06:55.399 I mean, humanity has only visited these planets one single 137 00:06:55.480 --> 00:07:00.879 time once NASA's Voyager two spacecraft flew by Uranus in 138 00:07:00.959 --> 00:07:03.600 nineteen eighty six, and then it reached Neptune in nineteen 139 00:07:03.639 --> 00:07:04.120 eighty nine. 140 00:07:04.480 --> 00:07:07.240 That's it, and that's all we have. Every textbook, diagram, 141 00:07:07.279 --> 00:07:10.519 every CGI documentary rendering of their interiors you've ever seen 142 00:07:10.800 --> 00:07:13.959 essentially stems from those two incredibly brief encounters. 143 00:07:14.000 --> 00:07:16.279 It's wild to think about. Voyager two is obviously one 144 00:07:16.319 --> 00:07:18.759 of the greatest engineering achievements in human history, but we 145 00:07:18.839 --> 00:07:21.319 have to remember the context of its technology. The spacecraft 146 00:07:21.360 --> 00:07:22.519 was built in the nineteen seventies. 147 00:07:22.519 --> 00:07:25.199 It was recording data on actual magnetic tape. 148 00:07:25.040 --> 00:07:28.360 Yes, magnetic tape, and it wasn't even orbiting these planets. 149 00:07:28.399 --> 00:07:31.560 It was performing flybys. It was screaming past them at 150 00:07:31.600 --> 00:07:33.279 tens of thousands of miles per hour. 151 00:07:33.399 --> 00:07:35.360 It's an incredibly constrained snapshot. 152 00:07:35.639 --> 00:07:39.560 It's like trying to understand the entire complex ecosystem of 153 00:07:39.600 --> 00:07:43.439 the deep ocean by just quickly driving a speedboat over 154 00:07:43.480 --> 00:07:46.480 the surface of the water once in nineteen eighty six. Ye, 155 00:07:46.639 --> 00:07:48.720 you know, like you take a couple of polaroids as 156 00:07:48.759 --> 00:07:50.800 you zoom passed, and then you spend the next forty 157 00:07:50.879 --> 00:07:55.480 years trying to build a comprehensive, highly detailed model of 158 00:07:55.519 --> 00:07:58.879 the Marianas Trench based solely on those blurry photos. 159 00:07:58.959 --> 00:08:00.879 That is an excellent way to frame it. Obviously, the 160 00:08:00.959 --> 00:08:02.920 models you build from that are going to have massive, 161 00:08:03.079 --> 00:08:04.240 massive blind spots. 162 00:08:04.319 --> 00:08:07.399 So what did those brief polaroids actually show us, because 163 00:08:07.480 --> 00:08:10.040 clearly they saw something that didn't quite make sense. 164 00:08:10.120 --> 00:08:13.480 Well, Voyager two measured a few key things. It measured 165 00:08:13.480 --> 00:08:17.040 the atmospheric compositions at the very top layer. It recorded 166 00:08:17.079 --> 00:08:21.600 the thermal emissions, the heat radiating out into space, and crucially, 167 00:08:21.720 --> 00:08:24.199 it measured the planetary magnetic fields. 168 00:08:24.199 --> 00:08:26.759 And here's where it gets really interesting. The magnetic fields. 169 00:08:26.959 --> 00:08:30.399 Yes, it was that last measurement the magnetic field data 170 00:08:30.519 --> 00:08:33.279 that immediately threw the scientific community into a state of 171 00:08:33.399 --> 00:08:36.799 total confusion because the data simply did not align with 172 00:08:36.840 --> 00:08:38.759 the ice giant model they had constructed. 173 00:08:38.960 --> 00:08:40.919 Let's get into the mechanics of that, because this seems 174 00:08:40.919 --> 00:08:44.519 to be the first major thread that eventually unraveled the 175 00:08:44.559 --> 00:08:48.360 whole icy paradigm. Now, I'm familiar with Earth's magnetic field. 176 00:08:48.480 --> 00:08:51.279 It's what makes a compass work right, right, And magnetic 177 00:08:51.320 --> 00:08:55.120 north is relatively close to the actual geographic north pole. 178 00:08:55.399 --> 00:08:58.399 It's somewhat aligned with how the planet rotates. So what 179 00:08:58.440 --> 00:09:01.639 did Voyager two actually find when I looked at Uranus 180 00:09:01.679 --> 00:09:02.440 and Neptune? 181 00:09:02.559 --> 00:09:06.320 It found sheer chaos, absolute chaos. How so, Well, to 182 00:09:06.440 --> 00:09:08.519 understand why it was so anomalous, we have to look 183 00:09:08.559 --> 00:09:11.960 at how planetary magnetic fields are generated in the first place. 184 00:09:12.399 --> 00:09:15.200 They aren't just giant, permanent magnets sitting dead in the 185 00:09:15.240 --> 00:09:18.279 center of a planet. They are actively generated by a 186 00:09:18.279 --> 00:09:22.600 complex process called a planetary dynamo. A dynamo okay, yeah, 187 00:09:22.600 --> 00:09:24.799 And for a dynamo to work, you need a massive 188 00:09:24.879 --> 00:09:28.919 volume of electrically conductive fluid deep inside the planet, and 189 00:09:28.919 --> 00:09:31.720 that fluid has to be physically churning and convecting like 190 00:09:31.799 --> 00:09:36.519 boiling water exactly on Earth. That churning fluid is our 191 00:09:36.559 --> 00:09:40.440 liquid iron outer core. The planet rotates, the intense heat 192 00:09:40.519 --> 00:09:43.519 makes the liquid iron convect upwards, and then the Coriolis 193 00:09:43.519 --> 00:09:46.879 effect from the rotation twists that moving conductive fluid into 194 00:09:46.919 --> 00:09:51.399 these complex spiraling columns, and that movement generates a massive, 195 00:09:51.799 --> 00:09:55.399 relatively stable magnetic field that roughly aligns with our axis 196 00:09:55.399 --> 00:09:55.919 of rotation. 197 00:09:56.159 --> 00:09:58.799 Okay, so the rotation of the planet basically organizes the 198 00:09:58.879 --> 00:10:02.559 chaotic churning of the liquid metal into a neat structured, 199 00:10:02.600 --> 00:10:04.600 planetary scale magnetic field. 200 00:10:04.440 --> 00:10:08.679 Under normal circumstances. Yes, that's the ideal model. But Voyager 201 00:10:08.720 --> 00:10:11.519 two revealed that the magnetic fields of Uranus and Neptune 202 00:10:11.519 --> 00:10:14.679 are heavily tilted, I mean severely tilted. We're talking fifty 203 00:10:14.759 --> 00:10:17.440 nine degrees off the axis of rotation for Uranus. 204 00:10:17.600 --> 00:10:19.720 Wow, fifty nine degrees that's almost sideways. 205 00:10:19.759 --> 00:10:23.080 It's completely skewed, and for Neptune it's forty seven degrees. 206 00:10:23.120 --> 00:10:26.159 But wait, it gets weirder. Furthermore, the magnetic fields aren't 207 00:10:26.200 --> 00:10:26.840 even centered. 208 00:10:26.960 --> 00:10:28.039 What do you mean not centered? 209 00:10:28.159 --> 00:10:31.000 They don't originate from the geometric core. Of the planets. 210 00:10:31.080 --> 00:10:34.600 They are completely off kilter, practically emerging from the sides 211 00:10:34.600 --> 00:10:36.200 of the planets rather than the center. 212 00:10:36.480 --> 00:10:39.240 That makes no sense. So if we picture the planetary 213 00:10:39.279 --> 00:10:42.080 dynamo as a spinning top, Earth's dynamo is like a 214 00:10:42.120 --> 00:10:46.440 perfectly balanced top spinning upright. But Urinus in Neptune have 215 00:10:46.559 --> 00:10:49.159 dynamos that act like a spinning top with the heavyweight 216 00:10:49.200 --> 00:10:53.240 glued to one side. It's wobbling, it's chaotic, and it's 217 00:10:53.320 --> 00:10:54.399 completely unstable. 218 00:10:54.519 --> 00:10:58.000 That mechanical instability is the key issue here, because if 219 00:10:58.120 --> 00:11:01.240 Urinus in Neptune were primarily post of a thick mantle 220 00:11:01.279 --> 00:11:04.519 of water, ammonia, and methane ice, you run into a 221 00:11:04.559 --> 00:11:06.399 massive physical contradiction. 222 00:11:05.960 --> 00:11:08.279 Because ice isn't a churning fluid exactly. 223 00:11:08.679 --> 00:11:11.320 Even if we assume the extreme pressures in the interior 224 00:11:11.399 --> 00:11:14.559 create exotic forms of ice, like there's a theoretical state 225 00:11:14.679 --> 00:11:18.200 called superionic water, which is somewhat conductive, it still behaves 226 00:11:18.240 --> 00:11:22.519 far too rigidly. Ice by definition, resists the rapid turbulent 227 00:11:22.600 --> 00:11:26.360 convection required to produce a highly active dynamo. It's too stiff, 228 00:11:26.519 --> 00:11:29.519 way too stiff, And even if it could somehow convect slightly. 229 00:11:29.919 --> 00:11:33.320 A thick, uniform ice mantle should theoretically produce a much 230 00:11:33.320 --> 00:11:37.840 more centralized, neatly aligned magnetic field. It absolutely shouldn't produce 231 00:11:37.879 --> 00:11:40.759 the chaotic off center mess that Voyager two observed. 232 00:11:40.840 --> 00:11:43.120 So the physics just break entirely. 233 00:11:43.519 --> 00:11:46.200 The physical properties of ice simply do not support the 234 00:11:46.200 --> 00:11:49.639 magnetic reality of these worlds. It was a glaring contradiction 235 00:11:49.679 --> 00:11:50.440 from day one. 236 00:11:50.639 --> 00:11:52.799 And the magnetic field wasn't the only thing that refused 237 00:11:52.799 --> 00:11:56.159 to make sense, right, Yeah, there's also the glaring problem 238 00:11:56.200 --> 00:11:57.799 of how these planets handle heat. 239 00:11:57.919 --> 00:12:01.879 Oh yes, the thermal anomaly is arguably even more perplexing 240 00:12:01.919 --> 00:12:04.799 than the magnetic one. Because planets are not just cold, 241 00:12:04.879 --> 00:12:09.440 dead rocks floating in space. They possess immense internal heat. 242 00:12:09.639 --> 00:12:11.360 Where does that heat come from if there are so 243 00:12:11.480 --> 00:12:12.240 far from the sun. 244 00:12:12.879 --> 00:12:16.320 Some of it is primordial heat, its energy left over 245 00:12:16.360 --> 00:12:20.039 from the violent accretion process of their actual formation, you know, 246 00:12:20.080 --> 00:12:24.279 when countless clintesimals and space rocks smashed together over billions 247 00:12:24.279 --> 00:12:27.360 of years, converting all that kinetic energy into thermal energy. 248 00:12:27.559 --> 00:12:30.279 So just the violence of birth creates heat that lasts 249 00:12:30.320 --> 00:12:31.600 billions of years. 250 00:12:31.399 --> 00:12:34.080 Exactly, and some of it also comes from the slow 251 00:12:34.120 --> 00:12:37.919 gravitational contraction of the planet over time. But regardless of 252 00:12:37.960 --> 00:12:40.759 the source, this intense internal heat eventually has to make 253 00:12:40.799 --> 00:12:42.919 its way from the deep core up to the surface, 254 00:12:43.200 --> 00:12:46.279 where it can finally radiate out into the vacuum of space. 255 00:12:46.639 --> 00:12:49.759 And the way that heat naturally travels through a fluid 256 00:12:49.840 --> 00:12:52.480 is primarily through convection. Right just like a pot of 257 00:12:52.480 --> 00:12:55.519 soup on a stove, the hot material deep down becomes 258 00:12:55.600 --> 00:12:59.440 less dense, it rises toward the cooler surface, releases its 259 00:12:59.440 --> 00:13:02.879 heat because denser again, and sinks back down a continuous 260 00:13:03.039 --> 00:13:03.799 rolling cycle. 261 00:13:04.000 --> 00:13:08.000 That's it. Convection is the absolute primary engine of planetary 262 00:13:08.000 --> 00:13:11.240 heat transport. But here is where the old ice giant 263 00:13:11.279 --> 00:13:16.120 model completely fails again. A massive thick layer of pressurized ice, 264 00:13:16.320 --> 00:13:20.039 even slushy exotic ice, ax as a phenomenal thermal insulator. 265 00:13:20.120 --> 00:13:22.039 It's basically a giant planetary thermos. 266 00:13:22.240 --> 00:13:26.279 Yes, it severely dampens any convection. If Uranus and Neptune 267 00:13:26.320 --> 00:13:29.799 were truly ice giants, that thick icy mantle would essentially 268 00:13:29.799 --> 00:13:32.320 trap the primordial heat deep deep in the core. It 269 00:13:32.320 --> 00:13:33.840 wouldn't be able to escape efficiently. 270 00:13:33.919 --> 00:13:35.480 But that's not what we actually see when we look 271 00:13:35.519 --> 00:13:35.759 at them. 272 00:13:35.840 --> 00:13:37.840 Is it not at all? The surface temperatures and the 273 00:13:37.879 --> 00:13:41.360 specific infrared radiation profiles that Voyager two measured, and you 274 00:13:41.399 --> 00:13:44.480 know that our modern telescopes continue to observe today, they 275 00:13:44.480 --> 00:13:48.039 show a highly dynamic heat flow. It strongly implies active, 276 00:13:48.200 --> 00:13:49.960 vigorous convection from the inside out. 277 00:13:50.159 --> 00:13:53.080 I remember reading a crazy stat about Neptune. Doesn't it 278 00:13:53.200 --> 00:13:55.840 radiate way more heat than it even gets from the sun. 279 00:13:56.080 --> 00:13:59.279 It does. Neptune radiates more than twice as much energy 280 00:13:59.320 --> 00:14:02.720 into space as it receives from solar radiation. That massive 281 00:14:02.720 --> 00:14:05.840 amount of internal heat is escaping somehow, it is not 282 00:14:05.919 --> 00:14:08.000 being insulated by a static block of ice. 283 00:14:08.279 --> 00:14:12.600 It feels like this massive cosmic historical irony. We literally 284 00:14:12.639 --> 00:14:17.279 gave them this incredibly specific moniker ice giants that actively 285 00:14:17.639 --> 00:14:20.480 fundamentally contradicts the actual physics we are observing. 286 00:14:20.600 --> 00:14:21.399 It really is ironic. 287 00:14:21.559 --> 00:14:24.559 I mean, we are watching them generate complex, highly energetic 288 00:14:24.600 --> 00:14:28.039 magnetic field and we are measuring massive amounts of heat 289 00:14:28.120 --> 00:14:31.720 actively flowing out of their deep interiors. Both of those 290 00:14:31.759 --> 00:14:35.919 things require fluid, dynamic, chaotic movement. Yet we slapped the 291 00:14:35.960 --> 00:14:39.039 label on them that implies a frozen static insulatory state. 292 00:14:39.279 --> 00:14:42.440 The name itself basically became a psychological barrier to actually 293 00:14:42.519 --> 00:14:43.919 understanding the physics. 294 00:14:43.559 --> 00:14:45.720 Which is exactly why Edward Deyung and his team at 295 00:14:45.799 --> 00:14:49.320 UCLA decided they had to discard the label entirely. They 296 00:14:49.320 --> 00:14:52.320 approached the problem from a completely blank slate. They didn't ask, 297 00:14:52.759 --> 00:14:56.000 how can we somehow mathematically force ice to fit this 298 00:14:56.080 --> 00:14:57.440 weird data, right. 299 00:14:57.360 --> 00:15:00.000 Which is what people had been doing for decades exactly. 300 00:15:00.240 --> 00:15:05.320 Instead, they asked, what specific internal structure, regardless of our 301 00:15:05.360 --> 00:15:09.960 preconceived notions, naturally produces the magnetic and thermal signatures we 302 00:15:10.039 --> 00:15:10.720 actually see. 303 00:15:10.840 --> 00:15:12.240 They just followed the evidence. 304 00:15:12.320 --> 00:15:16.919 They did. They utilized highly advanced computer simulations tools that 305 00:15:16.960 --> 00:15:20.440 were completely unavailable to the scientists during the voyager era 306 00:15:20.519 --> 00:15:24.679 in the eighties. They use these massive supercomputers to model 307 00:15:24.720 --> 00:15:28.519 the deep interiors based purely on the raw laws of thermodynamics, 308 00:15:28.519 --> 00:15:30.919 fluid dynamics, and high pressure chemistry. 309 00:15:30.960 --> 00:15:33.360 Okay, let's unpack this, Yeah, because this leads us right 310 00:15:33.399 --> 00:15:36.759 to the core of this whole paradigm shift. The UCLA 311 00:15:36.879 --> 00:15:41.080 models completely toss out the traditional massive block of ice, 312 00:15:41.480 --> 00:15:43.960 and they replace it with a highly complex three layer 313 00:15:44.039 --> 00:15:45.120 internal architecture. 314 00:15:45.200 --> 00:15:48.399 Right. The three layer model is incredibly elegant, because it 315 00:15:48.440 --> 00:15:52.039 actually resolves all of those decades old contradictions. So if 316 00:15:52.080 --> 00:15:54.159 we were moving from the outside of the planet inward, 317 00:15:54.240 --> 00:15:56.080 the first layer is the atmosphere. 318 00:15:56.120 --> 00:15:57.840 Okay, so that part hasn't really changed. 319 00:15:58.240 --> 00:16:00.360 No, this is the one part of the old model 320 00:16:00.399 --> 00:16:05.480 that remains largely intact. It's a massive gaseous envelope composed 321 00:16:05.519 --> 00:16:09.600 primarily of hydrogen and helium, along with trace amounts of methane, 322 00:16:09.840 --> 00:16:13.559 which is actually what gives both planets their beautiful signature 323 00:16:13.679 --> 00:16:14.799 blue hues. 324 00:16:14.679 --> 00:16:16.440 Right, the blue we see in all the photos. 325 00:16:16.519 --> 00:16:20.720 Exactly and dynamically, this top layer is essentially responsible for 326 00:16:20.759 --> 00:16:24.320 the final stage of heat transport. It carries the internal 327 00:16:24.360 --> 00:16:27.240 thermal energy up to the upper atmosphere, where it finally 328 00:16:27.360 --> 00:16:29.200 radiates out into the vacuum of space. 329 00:16:29.320 --> 00:16:31.639 Okay, so the gas planket makes total sense. That's the 330 00:16:31.639 --> 00:16:34.200 part we can actually see through our telescopes. But what 331 00:16:34.399 --> 00:16:38.120 happens beneath that hydrogen and helium atmosphere Because in the 332 00:16:38.120 --> 00:16:41.120 old model, this is exactly where you'd hit that endless 333 00:16:41.200 --> 00:16:43.000 insulating wall of ice, right. 334 00:16:43.080 --> 00:16:46.840 But in the new UCLA model, beneath the atmosphere you 335 00:16:47.000 --> 00:16:49.519 enter the second layer, which they call the boundary layer. 336 00:16:50.080 --> 00:16:52.840 And it is so crucial to understand here that planetary 337 00:16:52.879 --> 00:16:56.360 interiors are not always sharply defined like the neat layers 338 00:16:56.399 --> 00:16:56.919 of an onion. 339 00:16:57.039 --> 00:16:59.559 It's not just gas and then a sudden hard floor. 340 00:17:00.240 --> 00:17:03.519 Not at all. At these extreme depths, the pressure and 341 00:17:03.600 --> 00:17:07.119 temperature are so intense that they alter the very nature 342 00:17:07.160 --> 00:17:11.400 of chemistry. So the boundary layer is this massive, highly 343 00:17:11.440 --> 00:17:16.039 pressurized transition zone. It is a complex, multi component chemical 344 00:17:16.079 --> 00:17:20.559 soup containing hydrogen, helium, magnesium, silicon, monoxide, and oxygen. 345 00:17:20.720 --> 00:17:23.119 Okay, I've have to pause on the chemistry there. Magnesium 346 00:17:23.960 --> 00:17:28.440 and silicon monoxide. Why are those specific elements so crucial? 347 00:17:29.079 --> 00:17:31.599 That sounds less like the inside of a frozen planet 348 00:17:32.039 --> 00:17:34.960 and way more like the inside of an industrial blast furnace. 349 00:17:35.160 --> 00:17:37.000 Well, it is very much like a blast furnace. The 350 00:17:37.039 --> 00:17:40.440 presence of magnesium in silicon is the absolute key indicator 351 00:17:40.480 --> 00:17:43.559 of what lies beneath them. Because in planetary science we 352 00:17:43.599 --> 00:17:46.200 deal extensively with this concept called missibility. 353 00:17:46.319 --> 00:17:48.480 Missibility like how well things mix exactly. 354 00:17:48.480 --> 00:17:51.720 It's essentially the ability of two different substances to mix together. 355 00:17:51.880 --> 00:17:54.680 Think of oil and water. They are immissible under normal 356 00:17:54.720 --> 00:17:55.799 conditions on Earth, right. 357 00:17:55.640 --> 00:17:57.400 They separate, right, the oil just floats on top. 358 00:17:57.559 --> 00:18:02.279 But when you introduce unimaginable extreme heat and millions of 359 00:18:02.319 --> 00:18:06.400 time the atmospheric pressure of Earth, substances that normally wouldn't 360 00:18:06.400 --> 00:18:09.720 ever mix begin to fundamentally dissolve into one another. The 361 00:18:09.759 --> 00:18:13.039 boundary layer is exactly that, a region where the lighter 362 00:18:13.079 --> 00:18:16.000 gases from the upper atmosphere are violently interacting with and 363 00:18:16.000 --> 00:18:21.079 dissolving into the heavier, rocky molten materials rising up from below. 364 00:18:21.200 --> 00:18:25.160 Oh wow, and those heavier molten materials are coming directly 365 00:18:25.160 --> 00:18:26.960 from the third layer, the main event. 366 00:18:27.279 --> 00:18:30.839 Yes, the basal magma ocean. It just sounds crazy to 367 00:18:30.880 --> 00:18:34.079 say out loud, I know, but according to these new simulations, 368 00:18:34.119 --> 00:18:36.799 the vast majority of the interior volume of uranus and 369 00:18:36.799 --> 00:18:39.559 neptune is not ice at all, but it deeply buried, 370 00:18:39.799 --> 00:18:43.599 violently churning ocean of liquid silicate magma, liquid iron, and 371 00:18:43.640 --> 00:18:44.640 dissolved hydrogen. 372 00:18:44.880 --> 00:18:47.279 I think this is the exact point where the average 373 00:18:47.319 --> 00:18:51.599 person's intuition about space just completely breaks down. We're talking 374 00:18:51.640 --> 00:18:55.200 about planets situated nearly three billion miles away from the Sun. 375 00:18:55.680 --> 00:18:57.960 The ambient temperature of the vacuum around them is roughly 376 00:18:58.000 --> 00:19:00.039 three hundred and fifty degrees fahrenheit belows ear. 377 00:19:00.440 --> 00:19:03.839 It's unimaginably cold. So how on Earth does a planet 378 00:19:03.920 --> 00:19:06.720 sitting in the literal freezing depths of the outer Solar 379 00:19:06.720 --> 00:19:10.359 System maintain a churning ocean of liquid rock and iron. 380 00:19:10.839 --> 00:19:13.319 It is a phenomenal question, and it requires us to 381 00:19:13.359 --> 00:19:18.759 completely separate the concept of surface temperature from internal thermodynamics. 382 00:19:19.240 --> 00:19:22.319 The internal heat of a planet carry interior has almost 383 00:19:22.319 --> 00:19:24.880 nothing to do with the Sun. It is a completely 384 00:19:24.920 --> 00:19:26.640 self contained energetic system. 385 00:19:26.720 --> 00:19:30.200 So it's surviving purely on that primordial heat you mentioned earlier, 386 00:19:30.240 --> 00:19:32.640 if the heat leftover from its violent berth billions of 387 00:19:32.720 --> 00:19:33.160 years ago. 388 00:19:33.279 --> 00:19:37.240 Primordial heat is the absolute foundation. Yes, when a planet forms, 389 00:19:37.240 --> 00:19:40.359 the kinetic energy of millions of asteroid sized bodies slamming 390 00:19:40.440 --> 00:19:44.440 together over millennia is converted into intense thermal energy. But 391 00:19:44.519 --> 00:19:47.519 the reason that heat is maintained as a boiling liquid 392 00:19:47.559 --> 00:19:50.480 magma ocean billions of a year later comes down to 393 00:19:50.519 --> 00:19:54.359 the sheer crushing force of gravity. The pressure exactly the 394 00:19:54.400 --> 00:19:58.039 immense mass of the hydrogen and helium atmosphere, combined with 395 00:19:58.079 --> 00:20:00.960 the dense boundary layer beneath it is pressing down on 396 00:20:01.000 --> 00:20:04.440 the core with unimaginable weight. We are talking about pressures 397 00:20:04.680 --> 00:20:06.799 millions of times greater than what we feel standing on 398 00:20:06.839 --> 00:20:09.920 the surface of Earth, and as any basic high school 399 00:20:09.920 --> 00:20:14.079 physics class teaches us, when you exponentially increase pressure, you 400 00:20:14.279 --> 00:20:16.640 exponentially increase temperature exactly. 401 00:20:16.920 --> 00:20:21.000