WEBVTT 1 00:00:03.439 --> 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 Astronomie 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 --> 00:00:23.800 slumber under the night sky. 7 00:00:26.960 --> 00:00:30.160 Welcome back today. You've brought us some really compelling material 8 00:00:30.280 --> 00:00:34.200 about one of the most perplexing discoveries to come out 9 00:00:34.240 --> 00:00:36.399 of the James Web Space Telescope recently. 10 00:00:36.520 --> 00:00:38.880 That's right. It comes from a Carnegie led team and 11 00:00:38.920 --> 00:00:43.039 it's all focused on one specific exoplanet that is well, 12 00:00:43.079 --> 00:00:45.359 it's really challenging some core assumptions, and. 13 00:00:45.280 --> 00:00:47.320 Our mission for this deep dive is to get to 14 00:00:47.359 --> 00:00:49.880 the heart of that. We want to unpack the data 15 00:00:49.920 --> 00:00:52.880 and figure out why a planet that by all rights 16 00:00:52.920 --> 00:00:56.200 should be a dead, scorched piece of rock seems to 17 00:00:56.240 --> 00:01:00.359 have a thick, thriving atmosphere. So the planet we're talking about, 18 00:01:00.359 --> 00:01:03.560 it's called TOI five sixty one B. And just to 19 00:01:03.560 --> 00:01:06.519 set the stage, this is a super earth. It's rocky, 20 00:01:06.599 --> 00:01:09.599 it's ultra hot, and it's so close to its star 21 00:01:09.719 --> 00:01:11.879 that honestly, the model is all predicted it would have 22 00:01:11.879 --> 00:01:15.000 been blasted clean of any atmosphere billions of years. 23 00:01:14.840 --> 00:01:19.200 Ago, and yet it hasn't. The data is it's pretty unambiguous. 24 00:01:19.319 --> 00:01:21.159 So this isn't just some small update. We're talking about 25 00:01:21.159 --> 00:01:24.200 something that could fundamentally rewrite our understanding of how planets 26 00:01:24.200 --> 00:01:27.079 survive in extreme environments exactly. 27 00:01:27.120 --> 00:01:30.079 And it's not just about survival this one observation. It 28 00:01:30.200 --> 00:01:34.120 just up ends the conventional wisdom about these so called 29 00:01:34.400 --> 00:01:36.239 ultra short period planet. 30 00:01:36.000 --> 00:01:40.000 Ultra short period meaning they orbit their star in what 31 00:01:40.439 --> 00:01:41.079 in less. 32 00:01:40.879 --> 00:01:44.359 Than one Earth day. It's an entirely different class of world. Yeah, 33 00:01:44.400 --> 00:01:46.560 and the context here is just as important. That this 34 00:01:46.640 --> 00:01:49.799 isn't just any star system. It's ancient. We're looking at 35 00:01:49.799 --> 00:01:52.480 a planet that is fundamentally different from anything in our 36 00:01:52.480 --> 00:01:56.599 Solar system, and it's giving us this incredible window into 37 00:01:56.680 --> 00:02:01.760 how planets might have formed in a a very different 38 00:02:01.799 --> 00:02:04.599 chemical environment way back in the early days of the universe. 39 00:02:04.640 --> 00:02:06.760 Okay, let's untack this. I think we have to start 40 00:02:06.760 --> 00:02:10.159 with the planet itself, the sheer extremity of its environment. 41 00:02:10.280 --> 00:02:12.479 Absolutely, the conditions are almost unimaginable. 42 00:02:13.000 --> 00:02:15.199 So let's lay out the basic profile. We know it's 43 00:02:15.199 --> 00:02:18.240 a rocky planet, a super Earth. What does that actually 44 00:02:18.280 --> 00:02:20.080 mean in terms of its size and mass? 45 00:02:20.120 --> 00:02:22.479 So super Earth is a category for planets that are 46 00:02:22.520 --> 00:02:26.680 more massive than Earth, but significantly less massive than our 47 00:02:26.719 --> 00:02:30.400 ice giants like Neptune. In this case, TOI Fi sixty 48 00:02:30.439 --> 00:02:33.439 one B is firmly terrestrial. It has a solid surface, 49 00:02:34.000 --> 00:02:36.680 but it's packing about twice the mass of our own planet. 50 00:02:36.400 --> 00:02:39.000 Twice the massive Earth. That's substantial, But you're right, the 51 00:02:39.000 --> 00:02:41.520 mass is only part of the story. The location is 52 00:02:42.280 --> 00:02:45.000 it's the real shock ra here really is. The sources 53 00:02:45.039 --> 00:02:47.879 say it orbits its star one fortieth the distance of 54 00:02:47.919 --> 00:02:50.719 Mercury from our Sun one fortieth. 55 00:02:51.199 --> 00:02:52.560 I'm trying to even picture that. 56 00:02:52.680 --> 00:02:55.199 It's hard to visualize. So take Mercury, which is already 57 00:02:55.439 --> 00:02:57.759 right up against the Sun, practically skimming its surface from 58 00:02:57.800 --> 00:03:00.159 our perspective right now, imagine moving it f forward thy 59 00:03:00.240 --> 00:03:03.000 times closer to that furnace that's the neighborhood TOI five 60 00:03:03.120 --> 00:03:04.080 sixty one B lives in. 61 00:03:04.280 --> 00:03:07.159 So a year on this planet, one full orbit is 62 00:03:07.280 --> 00:03:09.080 just ten point five six hours. 63 00:03:09.479 --> 00:03:11.800 Just over ten hours. It completes an entire trip around 64 00:03:11.840 --> 00:03:13.719 its star in less time than a work down Earth. 65 00:03:13.840 --> 00:03:17.120 That speed is just dizzying, and the radiation, I mean, 66 00:03:17.159 --> 00:03:20.000 the amount of energy hitting that surface must be terrifying. 67 00:03:20.360 --> 00:03:23.520 Terrifying is a good word for it. Scorching almost feels 68 00:03:23.520 --> 00:03:27.000 like an understatement if you were to calculate the flux 69 00:03:27.039 --> 00:03:31.479 of stellar energy bathing this planet, it's just astronomical. 70 00:03:31.560 --> 00:03:34.000 And what does that kind of intensity do to a 71 00:03:34.080 --> 00:03:35.919 planet's atmosphere. 72 00:03:35.639 --> 00:03:40.240 Well, it has a couple of immediate and usually devastating implications. First, 73 00:03:40.240 --> 00:03:44.159 the gas envelope is exposed to these incredibly powerful solar winds, 74 00:03:44.520 --> 00:03:48.240 and these winds are constantly, relentlessly stripping away the lighter 75 00:03:48.280 --> 00:03:52.639 elements hydrogen, helium. They're just getting blasted off the top 76 00:03:52.639 --> 00:03:53.840 of the atmosphere into space. 77 00:03:53.960 --> 00:03:56.199 So it's like a constant erosion. 78 00:03:55.759 --> 00:03:58.879 Process, a very aggressive one. And that's just the first problem. 79 00:03:58.919 --> 00:04:01.639 The second is the heat itself. The energy input is 80 00:04:01.719 --> 00:04:04.400 so high that the gas molecules get heated up, they 81 00:04:04.479 --> 00:04:07.800 move faster and faster, and they can actually achieve escape velocity. 82 00:04:07.840 --> 00:04:10.080 They literally boil off the planet over time. 83 00:04:10.280 --> 00:04:12.639 So, based on everything we thought we knew, if this 84 00:04:12.719 --> 00:04:16.240 planet ever had an atmosphere should be long gone. 85 00:04:16.519 --> 00:04:19.920 It should be a distant memory. For a small, hot, 86 00:04:20.079 --> 00:04:24.439 rocky planet like this, any primordial atmosphere it formed with 87 00:04:24.680 --> 00:04:28.240 should have been lost within say, the first few hundred 88 00:04:28.279 --> 00:04:28.839 million years of. 89 00:04:28.839 --> 00:04:31.199 Its life, and this star system is much much older 90 00:04:31.240 --> 00:04:31.720 than that. 91 00:04:31.639 --> 00:04:33.959 Much older. We're talking about a system that's around ten 92 00:04:34.040 --> 00:04:37.680 billion years old. After that amount of time, any atmospheric 93 00:04:37.720 --> 00:04:42.600 remnant should be well negligible, a wisp of vapor at most. 94 00:04:42.759 --> 00:04:44.959 But that is not what the JWST is telling us. 95 00:04:45.000 --> 00:04:47.800 And there's another complication. The proximity to the star means 96 00:04:47.920 --> 00:04:51.439 this planet is almost certainly tidally locked. Can you explain 97 00:04:51.439 --> 00:04:53.519 what that means for a planet, especially one this close 98 00:04:53.560 --> 00:04:54.079 to its star? 99 00:04:54.399 --> 00:04:57.399 Sure? Tidal locking is what happens when the gravitational pull 100 00:04:57.439 --> 00:05:00.519 of a large body like a star forces a smaller 101 00:05:00.639 --> 00:05:04.040 orbiting body, the planet, to synchronize this rotation with its orbit. 102 00:05:04.360 --> 00:05:06.360 Like our moon is with Earth, we only ever see 103 00:05:06.399 --> 00:05:08.079 one side exactly. 104 00:05:07.759 --> 00:05:10.720 The same principle. Since Doi five sixty one b's orbit 105 00:05:10.759 --> 00:05:13.560 is ten point five to six hours its rotational period, 106 00:05:13.639 --> 00:05:15.879 the length of its day is also ten point five 107 00:05:15.959 --> 00:05:18.639 six hours. The practical upshot is that one hemisphere is 108 00:05:18.639 --> 00:05:22.040 locked in perpetual unending daylight, while the other is trapped 109 00:05:22.040 --> 00:05:23.000 in eternal darkness. 110 00:05:23.160 --> 00:05:25.360 So one side is constantly being cooked and the other 111 00:05:25.480 --> 00:05:26.040 is frozen. 112 00:05:26.240 --> 00:05:30.160 If it were a bare, airless rock, yes, the consequences 113 00:05:30.160 --> 00:05:33.480 would be an unimaginable temperature gradient. The day side would 114 00:05:33.480 --> 00:05:38.279 be superheated to thousands of degrees, easily hot enough to 115 00:05:38.360 --> 00:05:40.160 vaporize rock into a magma. 116 00:05:39.920 --> 00:05:42.959 Ocean, a literal ocean of lava, a permanent one. 117 00:05:43.639 --> 00:05:46.519 Meanwhile, the night side, facing the cold of deep space, 118 00:05:46.759 --> 00:05:50.000 would radiate its heat away and cool down rapidly. It 119 00:05:50.000 --> 00:05:53.279 would likely be solid rock, perhaps even frozen solid depending 120 00:05:53.279 --> 00:05:54.480 on the composition. 121 00:05:54.199 --> 00:05:57.639 And that difference in temperature from molten to solid rock 122 00:05:57.879 --> 00:06:00.560 that must create some incredible physical stress. 123 00:06:00.160 --> 00:06:03.360 On the planet, immense thermal stress. It would likely lead 124 00:06:03.360 --> 00:06:07.279 the huge cracks, faults, and rampant vulcanism as the planet 125 00:06:07.279 --> 00:06:11.079 tries to sort of equalize that energy. It really should 126 00:06:11.079 --> 00:06:12.879 be a world defined by thermal catastrophe. 127 00:06:12.920 --> 00:06:14.600 So this is a world that should have no air, 128 00:06:14.680 --> 00:06:17.560 should be half molten and half frozen, and basically be 129 00:06:17.720 --> 00:06:21.720 tearing itself apart. But the evidence suggests it's resilient, and 130 00:06:21.759 --> 00:06:24.040 the key to this whole puzzle seems to lie with 131 00:06:24.079 --> 00:06:25.319 its parent star it does. 132 00:06:25.360 --> 00:06:26.519 It all comes back to the star. 133 00:06:26.800 --> 00:06:29.360 Our sources say the star TOI five point fifty one 134 00:06:29.680 --> 00:06:32.199 is a bit smaller and cooler than our Sun, but 135 00:06:32.279 --> 00:06:35.879 it's ancient, twice the age of the Sun. And critically, 136 00:06:36.000 --> 00:06:39.439 it's described as iron pore and located in the thick 137 00:06:39.519 --> 00:06:42.879 disk of the Milky Way. Let's unpack that because that 138 00:06:42.959 --> 00:06:45.439 sounds like a lot of astronomical jargon. What does that 139 00:06:45.480 --> 00:06:47.319 combination of traits actually tell us? 140 00:06:47.439 --> 00:06:50.480 Okay, so the location is hugely important. The Milky Way 141 00:06:50.519 --> 00:06:54.000 galaxy isn't just a uniform blob. It has structure. There's 142 00:06:54.040 --> 00:06:56.120 a thin disc, which is where we live, where our 143 00:06:56.160 --> 00:06:58.879 Sun is. It's dense, it's where most of the star 144 00:06:58.959 --> 00:07:00.000 formation is happening now. 145 00:07:00.160 --> 00:07:01.759 And then there's the thick disk right. 146 00:07:02.040 --> 00:07:05.040 The thick disk is an older, more diffuse, sort of 147 00:07:05.120 --> 00:07:08.480 puckier structure that surrounds the thin disk. Stars in the 148 00:07:08.519 --> 00:07:11.279 thick disk are ancient. They formed very early in the 149 00:07:11.279 --> 00:07:14.399 galaxy's history, probably between eight and ten billion years ago. 150 00:07:14.800 --> 00:07:17.040 So finding the star there is what gives us that 151 00:07:17.120 --> 00:07:18.360 incredible age estimate. 152 00:07:18.480 --> 00:07:21.480 So it's like finding a fossil from the galaxy's childhood. 153 00:07:21.560 --> 00:07:24.680 A perfect analogy, and a key characteristic of these fossil 154 00:07:24.680 --> 00:07:28.360 stars is that they are metal poor. Now, we have 155 00:07:28.399 --> 00:07:30.600 to be clear about what astronomers mean by metals. 156 00:07:30.879 --> 00:07:32.519 It's not just iron and gold right. 157 00:07:32.600 --> 00:07:35.839 Right to an astronomer, a metal is any element on 158 00:07:35.879 --> 00:07:39.439 the periodic table that isn't hydrogen or helium. Ah Okay, 159 00:07:39.560 --> 00:07:42.000 the early universe was made of almost nothing but hydrogen 160 00:07:42.000 --> 00:07:46.000 and helium. It took generations of massive stars living fast 161 00:07:46.040 --> 00:07:49.360 and dying young, exploding at supernovae to forge all the 162 00:07:49.399 --> 00:07:54.720 heavier elements and then seed the galaxy with them carbon, oxygen, silicon, iron, 163 00:07:55.199 --> 00:07:56.160 All of that is metal. 164 00:07:56.360 --> 00:07:59.519 So an iron poor star means it was borne from 165 00:07:59.560 --> 00:08:02.160 a cloud of gas that just hadn't been enriched with 166 00:08:02.199 --> 00:08:06.079 those heavier elements. Yet the galaxy wasn't fully seasoned. 167 00:08:06.120 --> 00:08:09.160 I guess exactly. The protoplanetary disc of gas and dust 168 00:08:09.240 --> 00:08:12.519 that TOI five sixty one B formed from was fundamentally 169 00:08:12.600 --> 00:08:15.160 deficient in those heavier elements compared to the one that 170 00:08:15.199 --> 00:08:17.199 our own Solar system formed from about four and a 171 00:08:17.199 --> 00:08:18.000 half billion years. 172 00:08:17.839 --> 00:08:19.959 Ago, And that has to have a direct impact on 173 00:08:19.959 --> 00:08:21.319 the kind of planet that can form. 174 00:08:21.319 --> 00:08:23.319 A huge impact. It gives us a major clue about 175 00:08:23.360 --> 00:08:26.480 the planet's internal structure, but more importantly, it makes the 176 00:08:26.480 --> 00:08:29.720 fact that it has a sustained, volatile rich atmosphere even 177 00:08:29.720 --> 00:08:32.879 more bizarre. Why is that because the very building blocks 178 00:08:32.879 --> 00:08:36.679 for a complex atmosphere and even the planet itself were 179 00:08:36.720 --> 00:08:39.879 just scarcer back then. So the fact that this small, 180 00:08:40.000 --> 00:08:44.240 ancient and highly irradiated world not only formed but held 181 00:08:44.240 --> 00:08:47.240 onto its atmosphere, well, it runs contrary to basically every 182 00:08:47.240 --> 00:08:48.840 model of planetary survival we have. 183 00:08:49.039 --> 00:08:52.919 So we have a theoretical model that's screaming barren, scorched rocks, 184 00:08:53.000 --> 00:08:56.559 screaming it. Yes, but the scientists weren't just relying on theory. 185 00:08:56.879 --> 00:09:00.000 They had an early clue, a piece of circumstantial evidence 186 00:09:00.200 --> 00:09:02.519 that something was off, and it came down to a 187 00:09:02.559 --> 00:09:05.759 pretty basic measurement the planet's density, right. 188 00:09:05.639 --> 00:09:08.159 The mass to volume ratios. The first red flag. 189 00:09:08.320 --> 00:09:11.799 This density calculation really became the central puzzle, the thing 190 00:09:11.840 --> 00:09:16.039 that kicked off this whole intensive observation campaign with the JWST. 191 00:09:16.320 --> 00:09:19.200 When they first measured TOI five sixty one B, they 192 00:09:19.200 --> 00:09:22.240 found it had a really low bulk density. Now, the 193 00:09:22.279 --> 00:09:24.039 sources are clear to point out it's not one of 194 00:09:24.039 --> 00:09:26.679 those super puff or cotton candy planets, which are almost 195 00:09:26.840 --> 00:09:27.600 entirely gas. 196 00:09:27.919 --> 00:09:31.639 No, it's definitely a rocky world. But for a super 197 00:09:31.679 --> 00:09:34.399 Earth with twice the mass of our planet, it was 198 00:09:35.200 --> 00:09:37.799 it was lighter than it should have been. The numbers 199 00:09:37.840 --> 00:09:39.679 just didn't quite line up with an earth. 200 00:09:39.679 --> 00:09:44.200 Like composition, and that discrepancy, that low density immediately presented 201 00:09:44.240 --> 00:09:46.440 to competing hypotheses. 202 00:09:45.879 --> 00:09:47.600 Right, and the team had to figure out which one 203 00:09:47.639 --> 00:09:51.200 was correct because they lead to radically different conclusions about 204 00:09:51.240 --> 00:09:51.639 the planet. 205 00:09:51.720 --> 00:09:53.840 Let's talk about the first one, hypothesis one. 206 00:09:53.919 --> 00:09:56.519 So hypothesis one goes right back to the planet's heritage 207 00:09:56.519 --> 00:09:59.960 where we were just discussing. The star system is ancient 208 00:10:00.360 --> 00:10:03.399 and iron core, so it stands to reason that the 209 00:10:03.399 --> 00:10:05.039 planet itself must reflect that. 210 00:10:05.360 --> 00:10:09.120 So its composition is just different from Earth's exactly. 211 00:10:09.639 --> 00:10:13.000 The lower density could be explained by more you could say, 212 00:10:13.039 --> 00:10:16.720 exotic interior. Perhaps it has a much smaller iron core 213 00:10:16.919 --> 00:10:20.559 proportionally than Earth does, and maybe it's mantle. The rocky 214 00:10:20.639 --> 00:10:24.320 layer is made of lower density minerals, things formed from 215 00:10:24.360 --> 00:10:27.039 the lighter elements that were more common in that ancient 216 00:10:27.080 --> 00:10:28.159 protoplanetary disk. 217 00:10:28.360 --> 00:10:31.600 So that's the geological explanation. The ingredients were just naturally 218 00:10:31.679 --> 00:10:32.559 lighter from the start. 219 00:10:32.840 --> 00:10:36.720 Precisely. It's a very neat and tidy explanation. It connects 220 00:10:36.720 --> 00:10:39.919 the formation context, the thick disk the iron pore star 221 00:10:40.440 --> 00:10:43.399 directly to the measurement they made. It's elegant, but. 222 00:10:43.399 --> 00:10:46.759 It wasn't the only possibility, And the second hypothesis is 223 00:10:46.799 --> 00:10:50.279 the one that really brought the JWST into the picture. 224 00:10:50.399 --> 00:10:54.559 Yes, hypothesis too, proposed that the low density wasn't due 225 00:10:54.600 --> 00:10:57.480 to the planet's core composition at all. It suggested it 226 00:10:57.519 --> 00:10:59.200 was an observational. 227 00:10:58.559 --> 00:11:00.799 Artifact, an artifact caused by what. 228 00:11:01.039 --> 00:11:05.360 Caused by something hiding in plain sight, a surprisingly thick atmosphere. 229 00:11:05.440 --> 00:11:09.000 Ah okay, how does an atmosphere make a planet seem 230 00:11:09.159 --> 00:11:09.799 less dense? 231 00:11:10.080 --> 00:11:12.120 Well, think about how we measure the size of these 232 00:11:12.159 --> 00:11:15.480 distant planets. We use the transit method. We watch it 233 00:11:15.519 --> 00:11:17.879 pass in front of its star and measure how much 234 00:11:17.879 --> 00:11:18.799 starlight it blocks. 235 00:11:18.919 --> 00:11:20.840 Right, the bigger the planet, the bigger the dip. 236 00:11:20.679 --> 00:11:23.399 In light, exactly. But if a planet has a thick, 237 00:11:23.519 --> 00:11:26.440 opaque atmosphere, what you're actually measuring is the top of 238 00:11:26.480 --> 00:11:29.559 that gaseous envelope, not the surface of the solid rock core. 239 00:11:30.159 --> 00:11:33.240 The atmosphere makes the planet appear larger and radius than 240 00:11:33.279 --> 00:11:34.279 it actually is, So. 241 00:11:34.360 --> 00:11:36.559 You've got this inflated size measurement. 242 00:11:36.799 --> 00:11:39.320 You've got an inflated radius, but you're using the planet's 243 00:11:39.320 --> 00:11:43.000 true mass, which we can measure through its gravitational tug 244 00:11:43.120 --> 00:11:46.519 on the star. And when you calculate density mass divided 245 00:11:46.519 --> 00:11:49.639 by volume, a larger volume gives you a much lower density. 246 00:11:50.240 --> 00:11:53.000 So the low density itself was the first major hint 247 00:11:53.080 --> 00:11:56.320 that this planet was wrapped in a substantial blanket of gas. 248 00:11:56.399 --> 00:11:58.519 It was the strongest initial hint and it was a 249 00:11:58.559 --> 00:12:01.159 direct challenge to all the models that said it couldn't 250 00:12:01.159 --> 00:12:01.480 be there. 251 00:12:01.480 --> 00:12:04.000 So the mission was set figure out which it was 252 00:12:04.360 --> 00:12:08.919 an exotic iron pore interior or a surprisingly stubborn atmosphere. 253 00:12:09.720 --> 00:12:13.080 How did the team use JWST to solve this? It 254 00:12:13.120 --> 00:12:16.200 seems incredibly difficult to isolate the light from a tiny 255 00:12:16.200 --> 00:12:18.039 planet right next to its blazing star. 256 00:12:18.559 --> 00:12:20.840 It's an immense technical challenge, and this is really where 257 00:12:20.919 --> 00:12:24.360 the sheer power of the jam's webspased telescope shines. They 258 00:12:24.440 --> 00:12:28.440 used an instrument called the near infrared spectrograph or in 259 00:12:28.519 --> 00:12:31.200 our spec in our spec okay, and their entire method 260 00:12:31.279 --> 00:12:35.559 hinged on a very long, very painstaking observation. They stared 261 00:12:35.559 --> 00:12:38.440 at the system for over thirty seven hours straight, focusing 262 00:12:38.440 --> 00:12:41.159 on a specific event called the secondary eclipse. 263 00:12:40.799 --> 00:12:43.039 The secondary class. That's not the transit, when the planet 264 00:12:43.039 --> 00:12:43.759 goes in front, that's all. 265 00:12:44.000 --> 00:12:46.159 That's when the planet goes behind the star. From our 266 00:12:46.200 --> 00:12:46.639 point of view. 267 00:12:46.720 --> 00:12:47.840 Okay, so what does that tell you? 268 00:12:47.960 --> 00:12:50.440 It tells you exactly how much light the planet itself 269 00:12:50.480 --> 00:12:54.120 is giving off. Think about it, Just before the eclipse, 270 00:12:54.559 --> 00:12:57.799 our telescope is receiving light from the star plus the 271 00:12:57.879 --> 00:13:00.720 light radiating from the planet's scorching hot day. 272 00:13:00.559 --> 00:13:02.120 Side right a combined signal. 273 00:13:02.360 --> 00:13:04.879 Then for a short period the planet is hidden behind 274 00:13:04.919 --> 00:13:08.279 the star. During that time we only get the starlight. 275 00:13:09.039 --> 00:13:11.799 All we have to do is subtract the star only 276 00:13:11.919 --> 00:13:13.919 light from the star plus planet. 277 00:13:13.639 --> 00:13:16.559 Light, and what's left over is the light coming only 278 00:13:16.559 --> 00:13:18.039 from the planet's day side. 279 00:13:18.080 --> 00:13:22.159 Precisely, you can isolate the planet's thermal spectrum, its heat signature. 280 00:13:22.840 --> 00:13:24.840 That sounds I mean, that's like trying to measure the 281 00:13:24.879 --> 00:13:27.159 light from a single candle flame sitting right next to 282 00:13:27.200 --> 00:13:28.120 a giant searchlight. 283 00:13:28.200 --> 00:13:30.000 That's a very good way to put it. You are 284 00:13:30.000 --> 00:13:33.919 trying to isolate a tiny whisper of heat energy from 285 00:13:33.919 --> 00:13:37.840 a background source that is thousands or even millions of 286 00:13:37.879 --> 00:13:38.639 times brighter. 287 00:13:38.720 --> 00:13:41.480 How can an instrument even do that with any accuracy? 288 00:13:41.879 --> 00:13:46.080 It requires incredible stability and sensitivity. In our spec is 289 00:13:46.159 --> 00:13:49.879 specifically optimized to look at near infrared light, and that's 290 00:13:49.919 --> 00:13:53.080 exactly the wavelength where a super hot surface like the 291 00:13:53.159 --> 00:13:56.080 day side of TOI five point sixty one B would 292 00:13:56.120 --> 00:13:57.759 be radiating most of its energy. 293 00:13:57.840 --> 00:14:00.279 So it's looking in the perfect part of the spectrum it. 294 00:14:00.240 --> 00:14:04.840 Is, and by observing continuously for almost four full orbits 295 00:14:04.879 --> 00:14:07.600 of the planet, they were just taking a single snapshot. 296 00:14:07.919 --> 00:14:11.240 They were accumulating data points over and over again, which 297 00:14:11.279 --> 00:14:14.039 allows them to build up the signal and average out 298 00:14:14.120 --> 00:14:16.799 the noise. They're not looking for visible light reflecting off 299 00:14:16.840 --> 00:14:20.039 the planet. They're measuring its thermal glow, the infrared heat, 300 00:14:20.080 --> 00:14:22.399 which is a much more direct way to measure its temperature. 301 00:14:22.639 --> 00:14:26.000 A fascinating look at how these observatories actually work. But okay, 302 00:14:26.120 --> 00:14:30.000 let's get to the results. What did that meticulous measurement show. 303 00:14:30.279 --> 00:14:32.679 Here's where it gets really interesting. What was the number? 304 00:14:32.960 --> 00:14:35.440 The proof was in the numbers, absolutely and it came 305 00:14:35.480 --> 00:14:38.440 down to a massive discrepancy between what the temperature should 306 00:14:38.440 --> 00:14:40.360 have been and what they actually observed. 307 00:14:40.440 --> 00:14:43.240 Okay, so what was the prediction if TOI five point 308 00:14:43.240 --> 00:14:46.120 sixty one B was just a bare airless rock. 309 00:14:46.399 --> 00:14:49.320 The thermal models, assuming it's a perfect black body, just 310 00:14:49.399 --> 00:14:53.399 absorbing and reradiating all that stellar energy, predicting a day 311 00:14:53.399 --> 00:14:57.320 side temperature approaching a staggering forty nine hundred degrees here 312 00:14:57.399 --> 00:15:01.360 night nine hundred degrees or about twenty seven hundred degrees celsius. 313 00:15:01.360 --> 00:15:04.120 I can't even comprehend that that's far hotter than the 314 00:15:04.159 --> 00:15:06.960 melting point of most rocks. You'd have that magma ocean 315 00:15:07.000 --> 00:15:07.519 we talked. 316 00:15:07.320 --> 00:15:10.440 About, guaranteed it's hard enough to melt and boil steel 317 00:15:10.519 --> 00:15:13.360 almost instantly. That was a baseline prodution for a dead 318 00:15:13.480 --> 00:15:14.320 airless world. 319 00:15:14.720 --> 00:15:18.039 So what did JWST actually see? 320 00:15:18.120 --> 00:15:21.080 The NIR spectata revealed that the day side temperature was 321 00:15:21.159 --> 00:15:24.679 significantly cooler. How much cooler The measurement came in closer 322 00:15:24.679 --> 00:15:27.120 to three to two hundred degrees fahrenheit or about eighteen 323 00:15:27.240 --> 00:15:28.000 hundred celsius. 324 00:15:28.039 --> 00:15:30.600 Wait, a drop of seventeen hundred degrees fahrenheit. 325 00:15:30.759 --> 00:15:33.720 Yes, a massive, massive difference. It's more than nine hundred 326 00:15:33.759 --> 00:15:36.480 degrees celsius cooler than it should be. There's simply no 327 00:15:36.559 --> 00:15:38.559 way for a bare rock to be that cool under 328 00:15:38.559 --> 00:15:39.879 them atradiation. 329 00:15:39.480 --> 00:15:41.399 So something has to be getting in the way, Something 330 00:15:41.399 --> 00:15:43.759 has to be distributing that heat exactly. 331 00:15:44.279 --> 00:15:48.919 That significant cooling effect absolutely must be caused by something substantial, 332 00:15:49.440 --> 00:15:53.360 and the only plausible candidate is a thick atmosphere that's 333 00:15:53.519 --> 00:15:55.720 actively regulating the planet's temperature. 334 00:15:55.879 --> 00:15:58.240 So it's not just that an atmosphere is there, it's 335 00:15:58.320 --> 00:16:00.919 that it's actively working. It's adynamic system. 336 00:16:01.120 --> 00:16:04.039 It has to be A simple thin layer of gas 337 00:16:04.039 --> 00:16:07.960 wouldn't be enough. You need complex processes to explain that 338 00:16:08.080 --> 00:16:08.879 level of cooling. 339 00:16:09.200 --> 00:16:12.279 What about other explanations. Could something else be moving the 340 00:16:12.320 --> 00:16:15.879 heat around? What if the magma ocean itself was circulating 341 00:16:16.080 --> 00:16:17.600 carrying heat to the night side. 342 00:16:17.679 --> 00:16:20.399 That's a great question, and the team considered it. A 343 00:16:20.440 --> 00:16:23.960 magma ocean could certainly circulate some heat, but without an 344 00:16:23.960 --> 00:16:26.840 atmosphere to trap that heat and move it efficiently, the 345 00:16:26.960 --> 00:16:29.720 night side would still likely cool down so much that 346 00:16:29.759 --> 00:16:30.879 the rock would solidify. 347 00:16:31.080 --> 00:16:33.679 Ah, so you'd have a solid barrier on the night side, 348 00:16:33.720 --> 00:16:35.679 which would limit how much heat could flow from the 349 00:16:35.759 --> 00:16:36.399 day side. 350 00:16:36.559 --> 00:16:39.919 It would limit the flow, Yes, the circulation would be inefficient. 351 00:16:40.120 --> 00:16:43.240 You also might get a very thin atmosphere of vaporized 352 00:16:43.320 --> 00:16:47.080 rock silicate vapor. But again, a thin layer like that 353 00:16:47.360 --> 00:16:50.399 just doesn't provide the kind of global cooling effect that 354 00:16:50.480 --> 00:16:53.639 was observed. It can't explain a seventeen hundred degree temperature drop. 355 00:16:53.840 --> 00:16:56.559 So those simpler explanations just don't fit the data. 356 00:16:56.639 --> 00:16:59.679 They don't. As a researcher said, we really need a thick, 357 00:16:59.759 --> 00:17:02.919 vault little rich atmosphere to explain all the observations. 358 00:17:03.120 --> 00:17:06.440 Volatile rich meaning gas is light. Yeah, what are we 359 00:17:06.519 --> 00:17:07.359 talking about here? 360 00:17:07.480 --> 00:17:10.240 We're talking about things that are gases at lower temperatures 361 00:17:10.279 --> 00:17:15.319 than rock, water, vapor, carbon dioxide, maybe even oxygen or methane, 362 00:17:15.319 --> 00:17:19.079 though that's less likely these temperatures. Volatiles the stuff atmospheres 363 00:17:19.079 --> 00:17:19.599 are made of. 364 00:17:19.599 --> 00:17:22.640 And this thick, volatile rich atmosphere would have several ways 365 00:17:22.640 --> 00:17:23.960 of cooling that day side down. 366 00:17:24.119 --> 00:17:28.240 That's right. The model suggest at least three key cooling 367 00:17:28.279 --> 00:17:29.920 mechanisms are probably at play here. 368 00:17:29.960 --> 00:17:31.000 Okay, what's the first one. 369 00:17:31.079 --> 00:17:34.759 The first and maybe the most intuitive is wind, really 370 00:17:34.799 --> 00:17:35.720 really strong winds. 371 00:17:35.880 --> 00:17:39.200 Winds on a world that hot with a magma ocean. 372 00:17:39.240 --> 00:17:43.400 Exactly the extreme temperature difference between the super hot day 373 00:17:43.440 --> 00:17:47.119 side and the cooler night side would drive incredibly powerful 374 00:17:47.160 --> 00:17:51.000 atmospheric circulation. These winds would pick up heat from the 375 00:17:51.000 --> 00:17:54.160 scorching day side and physically transport it over to the 376 00:17:54.240 --> 00:17:54.759 night side. 377 00:17:54.839 --> 00:17:57.599 So it's like a planetary scale air conditioner. It's just 378 00:17:57.720 --> 00:18:00.319 moving the heat around the globe, preventing it from building 379 00:18:00.400 --> 00:18:01.319 up in one spot. 380 00:18:01.480 --> 00:18:04.200 That's the perfect way to think about it. It lowers 381 00:18:04.240 --> 00:18:06.799 the maximum temperature on the day side by spreading the 382 00:18:06.920 --> 00:18:07.960 energy out more evenly. 383 00:18:08.359 --> 00:18:10.880 Okay, so that's one. What's the second cooling effect? 384 00:18:11.160 --> 00:18:15.640 The second is gas absorption. Those volatile gases we mentioned water, 385 00:18:15.799 --> 00:18:19.079 carbon dioxide, things like that are very good at absorbing 386 00:18:19.240 --> 00:18:20.880 near infrared light, the. 387 00:18:20.839 --> 00:18:24.079 Very light that JWST is looking for the very same. 388 00:18:24.160 --> 00:18:27.359 So the hot surface is radiating this infrared light, but 389 00:18:27.440 --> 00:18:30.480 before that light can escape into space and reach our telescope, 390 00:18:30.720 --> 00:18:34.000 the atmosphere absorbs some of it. From our perspective, the 391 00:18:34.039 --> 00:18:37.759 planet just looks dimmer and therefore colder than it actually 392 00:18:37.799 --> 00:18:38.519 is at the surface. 393 00:18:38.559 --> 00:18:41.319 So the atmosphere acts like a filter, blocking some of 394 00:18:41.319 --> 00:18:42.920 the heat signature it does. 395 00:18:43.640 --> 00:18:46.599 It's another piece of the puzzle that contributes to that 396 00:18:46.799 --> 00:18:50.839 lower observed temperature, and the third mechanism. The third possibility 397 00:18:50.880 --> 00:18:51.519 is clouds. 398 00:18:51.960 --> 00:18:54.279 Clouds on a lava world. What would they even be 399 00:18:54.319 --> 00:18:54.680 made of? 400 00:18:55.480 --> 00:18:59.000 Well, not water, obviously, but you could potentially have clouds 401 00:18:59.000 --> 00:19:03.079