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 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 Imagine for just a second that you are standing outside 8 00:00:30.239 --> 00:00:34.439 on like a perfectly clear, crisp night You're just looking 9 00:00:34.479 --> 00:00:37.159 up at the vast, sprawling expanse of the night sky right. 10 00:00:37.200 --> 00:00:39.159 Right, getting that full cosmic. 11 00:00:38.719 --> 00:00:43.960 Perspective exactly, And the stars they appear completely fixed. The 12 00:00:44.039 --> 00:00:50.880 planets are slowly silently tracing these ancient, mathematically predictable paths. 13 00:00:51.000 --> 00:00:53.200 It's basically orbital mechanics doing its thing. 14 00:00:53.320 --> 00:00:56.479 Yeah, and everything just feels ordered. Like the universe from 15 00:00:56.520 --> 00:00:59.280 our terrestrial vantage point, anyway, it looks like a flawless, 16 00:00:59.560 --> 00:01:00.759 frictionless clock. 17 00:01:00.679 --> 00:01:02.439 A very large, very cold clock. 18 00:01:02.600 --> 00:01:06.359 Right now, I want you to imagine locking your eyes 19 00:01:06.400 --> 00:01:10.719 onto a specific celestial object that's just hurtling through the darkness. 20 00:01:10.799 --> 00:01:12.079 Okay, I'm picturing it. 21 00:01:12.079 --> 00:01:15.239 It has mass, it has momentum, it has been traveling 22 00:01:15.280 --> 00:01:19.200 on this massive elliptical track for centuries, literally doing exactly 23 00:01:19.200 --> 00:01:22.640 what the laws of thermodynamics and gravity demand that it do. 24 00:01:22.760 --> 00:01:25.519 Because that's how physics works. You can't argue with inertia, 25 00:01:25.560 --> 00:01:26.000 you can't. 26 00:01:26.040 --> 00:01:29.120 But then, right as you're watching it, the impossible happens. 27 00:01:29.239 --> 00:01:32.319 This ancient object completely slams on the brakes. 28 00:01:32.120 --> 00:01:32.799 Which is wild. 29 00:01:33.040 --> 00:01:36.519 The rotation just grinds to a dead stop, and then, 30 00:01:37.000 --> 00:01:41.159 completely defying everything we intuitively understand about momentum inertia and 31 00:01:41.920 --> 00:01:45.280 you know, the absolute vacuum of space, it starts violently 32 00:01:45.280 --> 00:01:47.120 spinning in the exact opposite direction. 33 00:01:47.319 --> 00:01:51.280 Yeah, it fundamentally breaks the brain's intuitive physics engine totally, 34 00:01:51.519 --> 00:01:55.519 because when an object with that much mass and that 35 00:01:55.599 --> 00:01:59.439 much established inertia suddenly reverses course in a frictionless environment, 36 00:01:59.480 --> 00:02:01.519 it feels like glitch. In reality, it. 37 00:02:01.439 --> 00:02:04.680 Really does, like someone just hit reverse under remote control. 38 00:02:04.840 --> 00:02:08.400 Exactly. It goes against our fundamental understanding of how large 39 00:02:08.439 --> 00:02:11.479 celestial bodies are supposed to behave. I mean, you expect 40 00:02:11.520 --> 00:02:14.599 a planet or a moon to gradually slow down over say, 41 00:02:14.919 --> 00:02:17.000 billions of years due to tidal. 42 00:02:16.719 --> 00:02:19.599 Forces, billions of years, not not over a week end. 43 00:02:19.479 --> 00:02:24.199 Exactly, a sudden, violent mechanical reversal on a human timescale 44 00:02:24.599 --> 00:02:28.080 that requires a localized application of force so massive and 45 00:02:28.120 --> 00:02:31.680 so chaotic that it almost seems engineered, which is. 46 00:02:31.599 --> 00:02:34.560 Why this is arguably one of the most fascinating astronomical 47 00:02:34.599 --> 00:02:37.319 anomalies on record. We aren't just talking about like a 48 00:02:37.360 --> 00:02:40.719 theoretical model or a broken piece of video game physics here. 49 00:02:41.000 --> 00:02:42.719 No, this is heavily documented. 50 00:02:42.800 --> 00:02:46.360 It's a very real event surrounding a specific object known 51 00:02:46.400 --> 00:02:50.879 to astronomers as comment forty one pe total Giacobini krisoc 52 00:02:51.000 --> 00:02:53.560 quite the mouthful. Yeah, we are definitely gonna call it 53 00:02:53.639 --> 00:02:55.599 forty one p to save oxygen. 54 00:02:55.639 --> 00:02:56.080 Good call. 55 00:02:56.280 --> 00:02:58.759 Okay, let's unpack this because our mission today is to 56 00:02:59.000 --> 00:03:03.199 entirely break down on this unprecedented event. We're talking about 57 00:03:03.199 --> 00:03:06.719 the first ever observed instance of a comet throwing itself 58 00:03:06.719 --> 00:03:07.680 into a reverse spin. 59 00:03:07.879 --> 00:03:11.400 And what makes this story truly brilliant isn't just the 60 00:03:11.520 --> 00:03:13.919 violent physics of the reversal itself. 61 00:03:14.000 --> 00:03:16.919 Oh right, it's how we found out about it exactly 62 00:03:16.960 --> 00:03:18.879 because we didn't catch this happening live. 63 00:03:19.360 --> 00:03:22.360 The evidence of this impossible cosmic spin out was just 64 00:03:23.159 --> 00:03:25.759 sitting quietly in a digital database. 65 00:03:25.319 --> 00:03:26.520 Like a ghost in the machine. 66 00:03:26.599 --> 00:03:29.840 Yeah, completely unnoticed until someone decided to sift through the 67 00:03:29.960 --> 00:03:32.599 archives and actually do the math. The archival nature of 68 00:03:32.639 --> 00:03:36.120 the discovery is perhaps the most compelling part of the narrative. 69 00:03:35.759 --> 00:03:40.719 Here because it completely recontextualizes how we view modern astronomy. 70 00:03:40.879 --> 00:03:41.800 We aren't just looking up. 71 00:03:41.719 --> 00:03:43.840 Anymore, right, we're looking back through the hard drives. 72 00:03:44.000 --> 00:03:46.400 So we're going to explore the chaotic physics of the 73 00:03:46.400 --> 00:03:50.120 inner Solar System, the rapid, almost violent life and death 74 00:03:50.159 --> 00:03:54.000 cycles of short period comets, and basically the hidden treasures 75 00:03:54.199 --> 00:03:56.719 buried inside decades of data. 76 00:03:56.840 --> 00:03:59.800 Because to really grasp the magnitude of what happened to 77 00:03:59.840 --> 00:04:04.080 for p, you have to understand the specific structural vulnerabilities 78 00:04:04.159 --> 00:04:05.400 of the comet itself. 79 00:04:05.520 --> 00:04:07.840 Yeah, it's not just a generic space rock. 80 00:04:07.879 --> 00:04:12.319 No, it is a remarkably fragile piece of primordial architecture. 81 00:04:12.360 --> 00:04:14.439 So let's start with that architecture. Yeah, Because if a 82 00:04:14.479 --> 00:04:18.480 solid object stops spinning in a vacuum, the kinetic energy 83 00:04:18.480 --> 00:04:20.319 doesn't just magically disappear, right right. 84 00:04:20.439 --> 00:04:23.639 Physics demands an equal and opposite reaction exactly. 85 00:04:23.800 --> 00:04:27.600 So before we can identify where that massive counterforce came from, 86 00:04:27.680 --> 00:04:30.000 we need to understand exactly what kind of object is 87 00:04:30.040 --> 00:04:32.279 receiving the blow. Let's meet our protagonist. 88 00:04:32.399 --> 00:04:32.879 Let's do it. 89 00:04:32.959 --> 00:04:36.000 Where does a rock like forty one pe actually come from? 90 00:04:36.439 --> 00:04:37.959 Like initially, Well. 91 00:04:37.800 --> 00:04:39.800 To find the true origin of forty one P you 92 00:04:39.839 --> 00:04:42.600 have to look outward, like far past the orbits of 93 00:04:42.639 --> 00:04:45.680 Neptune and Urinus. Way out there, Yeah, to the absolute 94 00:04:45.920 --> 00:04:48.879 freezing dark edges of our solar neighborhood. We're talking about 95 00:04:48.879 --> 00:04:49.680 the Kuiper Belt. 96 00:04:49.920 --> 00:04:51.240 Okay, the Kuiper Belt. 97 00:04:51.600 --> 00:04:56.959 It's this massive, incredibly sparse ring of primordial frozen debris. 98 00:04:57.680 --> 00:05:01.439 The objects out there are basically the leftover building blocks 99 00:05:01.439 --> 00:05:03.480 from the very formation of the Solar system, so. 100 00:05:03.560 --> 00:05:06.240 Roughly four point six billion years ago exactly. 101 00:05:06.600 --> 00:05:10.759 They are essentially preserved in a deep frieze, totally untouched 102 00:05:10.800 --> 00:05:13.600 by solar radiation, just drifting in a state of near 103 00:05:13.639 --> 00:05:15.279 perfect cryogenic suspension. 104 00:05:15.720 --> 00:05:19.399 So it basically spends billions of years just floating in 105 00:05:19.399 --> 00:05:21.839 the dark, like a dormant time capsule of ice and. 106 00:05:21.920 --> 00:05:23.120 Rock yep, just waiting. 107 00:05:23.879 --> 00:05:26.160 So, how does something locked in the deep frieze of 108 00:05:26.199 --> 00:05:29.639 the outer Solar System end up zooming past Earth? Like? 109 00:05:29.680 --> 00:05:31.920 How does it get hot enough to fundamentally alter its 110 00:05:31.920 --> 00:05:32.639 own mechanics. 111 00:05:33.439 --> 00:05:38.079 Well, it encounters the ultimate gravitational bully of our Solar system, Jupiter. 112 00:05:38.120 --> 00:05:41.759 It is so staggeringly massive that its immense gravity will 113 00:05:41.920 --> 00:05:44.480 dictates the architecture of basically everything around it. 114 00:05:44.480 --> 00:05:46.800 It's kind of cosmic vacuum cleaner, right, a vacum. 115 00:05:46.519 --> 00:05:49.680 Cleaner and a gravitational slingshot. Because at some point in 116 00:05:49.720 --> 00:05:54.079 forty one p's ancient history, it's slow, lazy orbit drifted 117 00:05:54.240 --> 00:05:57.120 just a fraction too close to Jupiter's sphere of influence, 118 00:05:57.480 --> 00:06:01.560 and the giant planet's gravity caught it, warped its trajectory 119 00:06:01.839 --> 00:06:04.519 and fundamentally flung it inward toward the Sun. 120 00:06:04.720 --> 00:06:09.000 It's basically orbital resonance, acting as an eviction notice permanent. 121 00:06:09.000 --> 00:06:14.279 One Yeah. That interaction completely rewrote the comet's destiny. It 122 00:06:14.360 --> 00:06:16.959 left forty one P locked into a brand new, highly 123 00:06:17.000 --> 00:06:17.839 elliptical path. 124 00:06:17.959 --> 00:06:18.160 Right. 125 00:06:18.519 --> 00:06:22.000 It became what astronomers classify as a Jupiter family comet. 126 00:06:22.240 --> 00:06:24.639 So its orbit now brings it swinging through the inner 127 00:06:24.680 --> 00:06:27.759 Solar System relatively close to the Sun and Earth every 128 00:06:27.800 --> 00:06:28.800 five point four years. 129 00:06:28.879 --> 00:06:30.480 Okay, five point four years. 130 00:06:30.319 --> 00:06:33.279 And based on dynamic orbital modeling, researchers believe it has 131 00:06:33.319 --> 00:06:35.680 actually been trapped in this exact five point four year 132 00:06:35.720 --> 00:06:37.839 loop for approximately fifteen hundred years. 133 00:06:38.120 --> 00:06:41.040 That is wild a millennium and a half of doing 134 00:06:41.120 --> 00:06:43.839 the exact same lap round and round five point four 135 00:06:43.920 --> 00:06:46.959 years out toward the cold Jupiter, then whipping back around 136 00:06:47.000 --> 00:06:50.800 into the searing heat of the Sun. But when I 137 00:06:50.879 --> 00:06:55.120 picture a comet surviving that kind of extreme thermal cycling 138 00:06:55.120 --> 00:06:57.839 for fifteen hundred years, I picture something the size of 139 00:06:57.839 --> 00:06:58.240 a city. 140 00:06:58.360 --> 00:07:00.600 Yeah, that's the standard mental imag. 141 00:07:00.319 --> 00:07:03.199 Right, Like I picture a massive apocalyptic mountain of ice, 142 00:07:03.319 --> 00:07:05.079 you know, like Hailbop or Haley's Comet. 143 00:07:05.279 --> 00:07:08.399 And that assumption is exactly why forty one P is 144 00:07:08.439 --> 00:07:12.319 such a profound mechanical anomaly. Okay, because the nucleus of 145 00:07:12.319 --> 00:07:14.959 commet forty one P, and I mean the actual solid 146 00:07:15.000 --> 00:07:19.360 core of rock, dust and ice beneath the glowing coma 147 00:07:19.399 --> 00:07:22.959 you see in photographs, it is almost unimaginably small. 148 00:07:23.000 --> 00:07:23.959 How small are we talking? 149 00:07:24.040 --> 00:07:26.079 It measures only about one kilometer. 150 00:07:25.680 --> 00:07:28.079 Across one kilometer. Okay. Just to give you a concrete 151 00:07:28.160 --> 00:07:32.399 visual anchor for that scale, picture the Eiffel Tower in Paris. 152 00:07:32.560 --> 00:07:32.879 Okay. 153 00:07:32.920 --> 00:07:36.079 Now imagine stacking three Eiffel towers and to end, that 154 00:07:36.160 --> 00:07:39.399 total height is roughly the diameter of this entire comet. 155 00:07:39.439 --> 00:07:41.279 It's a tiny on a human scale. 156 00:07:41.360 --> 00:07:43.800 Sure, looking up at three stacked Eiffel Towers floating in 157 00:07:43.839 --> 00:07:44.560 the sky would be. 158 00:07:44.519 --> 00:07:47.120 Massive, terrifying really, right, But. 159 00:07:47.240 --> 00:07:50.639 In the arena of orbital mechanics, in a space populated 160 00:07:50.639 --> 00:07:54.000 by moons and gas giants, that is essentially a microscopic 161 00:07:54.040 --> 00:07:54.439 speck of. 162 00:07:54.480 --> 00:07:57.720 Dust, it is remarkably diminutive, and that lack of physical 163 00:07:57.759 --> 00:08:01.360 volume translates directly to a severe lacks makes sense because 164 00:08:01.399 --> 00:08:04.240 four one P is so small its own self gravity 165 00:08:04.279 --> 00:08:07.160 is incredibly went. In fact, the escape velocity on a 166 00:08:07.160 --> 00:08:09.439 one kilometer commet is so low that if you were 167 00:08:09.480 --> 00:08:12.759 standing on its surface, you could simply jump and your 168 00:08:12.800 --> 00:08:15.720 leg muscles would provide enough kinetic energy to break the 169 00:08:15.759 --> 00:08:18.000 comet's gravitational hold entirely. 170 00:08:18.199 --> 00:08:19.959 Wait, really, you just jump into orbit. 171 00:08:20.079 --> 00:08:22.199 You would just float away into space. You've never come 172 00:08:22.199 --> 00:08:22.639 back down. 173 00:08:23.000 --> 00:08:26.720 That is insane, which means the comet itself barely has 174 00:08:26.759 --> 00:08:30.240 the internal cohesive strength to hold its own material together, 175 00:08:30.720 --> 00:08:32.519 let alone resist external forces. 176 00:08:32.679 --> 00:08:35.840 Exactly, it is highly susceptible to torque. 177 00:08:35.960 --> 00:08:36.240 Right. 178 00:08:36.320 --> 00:08:39.440 Torque, Yeah, torque is simply the measure of force that 179 00:08:39.480 --> 00:08:42.960 can cause an object to rotate about an access. When 180 00:08:42.960 --> 00:08:46.039 you have an object with substantial mass, say a fifty 181 00:08:46.120 --> 00:08:50.440 kilometer wide comet, it possesses a massive moment of inertia. 182 00:08:50.559 --> 00:08:53.639 It's heavy, right, It takes a staggering amount of energy 183 00:08:53.679 --> 00:08:57.559 to alter its rotation. It can essentially shrug off environmental forces. 184 00:08:57.960 --> 00:09:00.320 Forty one p does not have that luxury. It is 185 00:09:00.360 --> 00:09:01.000 a lightweight. 186 00:09:01.240 --> 00:09:02.879 Think of it like a quad copter drone. 187 00:09:03.080 --> 00:09:04.159 Oh that's a good comparison. 188 00:09:04.240 --> 00:09:07.000 Yeah, Like, if you have a massive military grade helicopter, 189 00:09:07.480 --> 00:09:10.440 a sudden gust of wind or a minor mechanical hiccup 190 00:09:10.639 --> 00:09:13.279 isn't going to flip it upside down. Its sheer mass 191 00:09:13.360 --> 00:09:16.519 anchors its momentum. But if you have a cheap, lightlyight, 192 00:09:16.639 --> 00:09:20.159 palm sized plastic drone and one of the four rotors 193 00:09:20.519 --> 00:09:23.679 suddenly fires at three hundred percent capacity while the others 194 00:09:23.720 --> 00:09:26.600 remain normal, the drone doesn't just drift. 195 00:09:26.480 --> 00:09:28.840 Sideways, No, it completely wipes out. 196 00:09:28.759 --> 00:09:32.320 Exactly the massive asymmetry and thrust against its low mass 197 00:09:32.559 --> 00:09:36.159 throws the entire machine into an uncontrollable, violent flat spin. 198 00:09:37.000 --> 00:09:40.360 In the grand chaotic mechanics of our solar system, comet 199 00:09:40.360 --> 00:09:43.759 forty one P is that tiny unbalanced drone. 200 00:09:43.840 --> 00:09:47.559 The drone analogy captures the mechanical vulnerability perfectly. It is 201 00:09:47.559 --> 00:09:50.879 structurally at the mercy of the thermodynamic environment. 202 00:09:50.480 --> 00:09:53.600 Around it, and that extreme vulnerability is really what sets 203 00:09:53.639 --> 00:09:56.200 the stage for the deeply bizarre sequence of events that 204 00:09:56.440 --> 00:09:58.559 astronomer David Jewett eventually uncovered. 205 00:09:58.639 --> 00:10:01.399 Yes, the entire time timeline a forty one p's twenty 206 00:10:01.399 --> 00:10:04.879 seventeen approach to the Sun basically reads like a forensic 207 00:10:04.919 --> 00:10:06.879 reconstruction of a mechanical failure. 208 00:10:07.000 --> 00:10:09.720 So let's trace that twenty seventeen timeline because it really 209 00:10:09.759 --> 00:10:10.720 is a detective story. 210 00:10:10.799 --> 00:10:11.320 It really is. 211 00:10:11.480 --> 00:10:14.039 We are following the breadcrumbs left in the digital archives, 212 00:10:14.480 --> 00:10:16.960 and it starts in March at twenty seventeen, when forty 213 00:10:16.960 --> 00:10:19.440 one P was making its standard five point four year 214 00:10:19.480 --> 00:10:20.399 swing toward the Sun. 215 00:10:20.799 --> 00:10:24.399 Right in March, the astronomical community had their eyes on it. 216 00:10:24.919 --> 00:10:29.080 Astronomers utilize the Discovery Channel telescope, which is a very 217 00:10:29.120 --> 00:10:33.480 powerful ground based optical observatory located at the Lowell Observatory 218 00:10:33.480 --> 00:10:34.080 in Arizona. 219 00:10:34.240 --> 00:10:35.279 Very famous telescope. 220 00:10:35.320 --> 00:10:39.720 Oh yeah, so they took standard photometric observations basically measuring 221 00:10:39.720 --> 00:10:42.840 the light curve of the comet as it tumbled through space. 222 00:10:42.960 --> 00:10:46.399 So a solid baseline measurement exactly. 223 00:10:46.360 --> 00:10:50.519 The March data established the comet's starting parameters. They calculated 224 00:10:50.600 --> 00:10:53.320 how fast it was spinning as it came in toward perihelion, 225 00:10:53.639 --> 00:10:56.159 which is its closest approach to the Sun, and what 226 00:10:56.240 --> 00:10:58.200 was it doing at that moment. It was behaving like 227 00:10:58.240 --> 00:11:01.919 a perfectly standard, albeit very small, Jupiter family comet. Its 228 00:11:02.000 --> 00:11:04.679 rotation was normal, its momentum was steady. 229 00:11:04.480 --> 00:11:07.480 Okay, But the narrative fractures just two months later. Right 230 00:11:07.559 --> 00:11:10.960 fast forward to May of twenty seventeen. If I'm David 231 00:11:11.000 --> 00:11:13.600 Jewett looking at this archival data, what am I seeing 232 00:11:13.639 --> 00:11:14.399 in the May files? 233 00:11:14.799 --> 00:11:19.080 You are seeing an inexplicable deceleration. In May researchers pulled 234 00:11:19.159 --> 00:11:25.720 data gathered from space, specifically from NASA's Neil Garrel's Swift Observatory. Now, 235 00:11:25.840 --> 00:11:28.879 SWIFT is primarily designed to hunt for gamma ray bursts 236 00:11:28.919 --> 00:11:29.960 deep in the cosmos. 237 00:11:29.960 --> 00:11:32.039 Oh really, not comets, right. 238 00:11:32.039 --> 00:11:35.399 But its ultraviolet and optical telescopes are occasionally pointed at 239 00:11:35.440 --> 00:11:39.240 local targets like commets, and the ultraviolet data from Swift 240 00:11:39.360 --> 00:11:41.279 reveals something entirely baffling. 241 00:11:41.399 --> 00:11:42.200 What did it true? 242 00:11:42.279 --> 00:11:45.240 In just an eight week span, the comet had experienced 243 00:11:45.279 --> 00:11:48.639 a massive, dramatic slowdown in its repational period. 244 00:11:48.919 --> 00:11:52.360 A slowdown in a vacuum implies a massive counter force. 245 00:11:52.559 --> 00:11:54.519 I mean, there's a no air resistance to bleed off 246 00:11:54.559 --> 00:11:55.559 that momentum right now. 247 00:11:55.639 --> 00:11:55.840 None. 248 00:11:56.159 --> 00:11:59.039 So what kind of deceleration are the swift numbers actually showing? 249 00:11:59.240 --> 00:12:02.240 The object was suddenly spending three times more slowly than 250 00:12:02.279 --> 00:12:03.720 its baseline measurement in March. 251 00:12:03.799 --> 00:12:04.399 Three times. 252 00:12:04.480 --> 00:12:07.240 Yeah, The rotation period had stretched out to a sluggish, 253 00:12:07.519 --> 00:12:10.879 agonizing crawl, taking anywhere from forty six to sixty hours 254 00:12:10.879 --> 00:12:13.639 to complete a single rotation. It was literally grinding to 255 00:12:13.720 --> 00:12:14.159 a halt. 256 00:12:14.279 --> 00:12:16.840 A comet that has been doing the same lap carrying 257 00:12:16.840 --> 00:12:20.320 the exact same momentum for fifteen hundred years suddenly loses 258 00:12:20.440 --> 00:12:23.399 two thirds of its rotational velocity in sixty days. 259 00:12:23.480 --> 00:12:24.320 It's unheard of. 260 00:12:24.720 --> 00:12:28.799 That alone is a terrifying display of localized force. It's 261 00:12:28.840 --> 00:12:32.720 a massive physics anomaly. But that isn't the climax of 262 00:12:32.759 --> 00:12:33.480 the archive, isit. 263 00:12:33.679 --> 00:12:35.399 No, the actual shot comes at the end of the year. 264 00:12:35.440 --> 00:12:36.320 Okay, let's get into that. 265 00:12:36.480 --> 00:12:39.360 We're moved to December twenty seventeen. This is the crucial 266 00:12:39.360 --> 00:12:42.960 file that Jewett eventually cracked open. The observations this time 267 00:12:43.039 --> 00:12:44.840 came from the Hubble Space telescope. 268 00:12:44.879 --> 00:12:46.919 Oh the big guns, the biggest. 269 00:12:47.200 --> 00:12:51.039 Hubble's optics are pristine. It operates entirely above the distortion 270 00:12:51.120 --> 00:12:55.639 of Earth's atmosphere, providing incredibly high resolution imaging. Right when 271 00:12:55.679 --> 00:12:58.720 the December light curves from Hubble were finally analyzed, they 272 00:12:58.759 --> 00:13:02.039 showed that the sluggish sixty hour crawl was totally gone. 273 00:13:02.279 --> 00:13:03.720 So the rotation sped back up. 274 00:13:03.799 --> 00:13:07.080 It accelerated wildly. It went from that sixty hour crawl 275 00:13:07.159 --> 00:13:11.240 back down to completing a full rotation in just fourteen hours. 276 00:13:11.519 --> 00:13:15.279 Ral it was whipping around. What's fascinating here is the 277 00:13:15.279 --> 00:13:18.360 direction of the rotation had flipped. It was spinning in 278 00:13:18.360 --> 00:13:22.000 the completely opposite direction from its March baseline. 279 00:13:21.399 --> 00:13:25.120 A violent, massive mechanical reversal over a span of just 280 00:13:25.240 --> 00:13:28.840 nine months. Think about the energy required to execute that maneuver. 281 00:13:29.720 --> 00:13:32.639 It had to continue slowing down after the May observation, 282 00:13:33.200 --> 00:13:37.240 eventually coming to an absolute dead mechanical stop in the 283 00:13:37.320 --> 00:13:42.159 vacuus space before being forcefully continuously pushed to accelerate backward. 284 00:13:42.440 --> 00:13:47.000 It really forces a complete reevaluation of the thermodynamic forces 285 00:13:47.000 --> 00:13:49.120 at play on the surface of these small bodies. I 286 00:13:49.120 --> 00:13:52.519 bet because to fundamentally alter the angular momentum of a 287 00:13:52.519 --> 00:13:57.320 one kilometer wide solid object, you need a continuous, targeted 288 00:13:57.360 --> 00:14:00.879 and immense application of force. You literally need engine. 289 00:14:00.559 --> 00:14:02.840 Which brings us to the mechanics of the vacuum itself. 290 00:14:02.879 --> 00:14:06.440 We have the forensic timeline right, normal spin, sudden deceleration, 291 00:14:06.559 --> 00:14:08.919 dead stop, violent reverse acceleration. 292 00:14:08.559 --> 00:14:09.679 The whole sequence. 293 00:14:09.840 --> 00:14:12.559 We know the mass is low, but where is the engine? 294 00:14:12.840 --> 00:14:15.480 Like what massive force in the solar SYSM could possibly 295 00:14:15.519 --> 00:14:18.559 act as a localized thruster system capable of throwing three 296 00:14:18.600 --> 00:14:19.879 Eiffel Towers into reverse. 297 00:14:20.000 --> 00:14:23.200 The engine is fueled by a very specific phase transition 298 00:14:23.279 --> 00:14:24.080 called sublimation. 299 00:14:24.519 --> 00:14:26.519 Okay, sublimation, let's break that down. 300 00:14:26.879 --> 00:14:29.399 When we interact with ice on Earth, we are dealing 301 00:14:29.399 --> 00:14:32.440 with atmospheric pressure. If you take an ice cube out 302 00:14:32.480 --> 00:14:35.759 of your freezer, the ambient heat causes the solid H 303 00:14:35.840 --> 00:14:38.840 two O to melt into liquid water. Right, it melts, 304 00:14:38.879 --> 00:14:41.799 and if you apply enough heat, that liquid water eventually 305 00:14:41.840 --> 00:14:45.399 boils and evaporates into a gas That is the standard 306 00:14:45.399 --> 00:14:48.399 thermodynamic progression solid liquid gas. 307 00:14:48.639 --> 00:14:51.840 But a comet operates in the deep vacuum of space. 308 00:14:52.159 --> 00:14:54.759 The atmospheric pressure is essentially zero. 309 00:14:54.720 --> 00:14:58.360 Exactly, and without atmospheric pressure, the liquid state of water 310 00:14:58.440 --> 00:15:02.639 simply cannot exist. Yeah, the physics won't allow it. So 311 00:15:02.799 --> 00:15:05.720 as Comet forty one P approaches the Sun, it is 312 00:15:05.759 --> 00:15:09.639 subjected to incredibly intense unshielded solar radiation. 313 00:15:09.759 --> 00:15:11.039 It's getting baked, baked. 314 00:15:11.159 --> 00:15:13.600 The surface of the comet heats up rapidly the frozen 315 00:15:13.679 --> 00:15:17.279 volatile things like water, ice, carbon monoxide, carbon dioxide. They 316 00:15:17.320 --> 00:15:20.519 react to this extreme thermal shock by instantly flashing from 317 00:15:20.519 --> 00:15:23.600 a solid state directly into a gaseous state. Wow, they 318 00:15:23.600 --> 00:15:25.360 bypass the liquid phase entirely. 319 00:15:25.480 --> 00:15:28.159 So it's flash boiling from a frozen rock straight into 320 00:15:28.159 --> 00:15:29.399 a violent cloud of vapor. 321 00:15:29.720 --> 00:15:34.000 Yes, and that vapor doesn't just passively float away like 322 00:15:34.039 --> 00:15:38.480 a morning mist, because it expands incredibly rapidly upon transitioning 323 00:15:38.519 --> 00:15:42.879 to a gas. It violently, forcefully ejects outward into the 324 00:15:42.960 --> 00:15:47.080 vacuum like get explosion. Very much so. This violent expulsion 325 00:15:47.120 --> 00:15:50.840 creates localized outgassing jets right on the surface of the 326 00:15:50.879 --> 00:15:51.799 comet's nucleus. 327 00:15:52.120 --> 00:15:54.960 This is where David Jewett's analysis of the Hubble data 328 00:15:55.000 --> 00:15:58.720 becomes so brilliant because he looked at these outgassing jets 329 00:15:59.200 --> 00:16:03.240 and just applied absolute foundational Newtonian physics to them. 330 00:16:03.360 --> 00:16:05.080 Newton's third law right. 331 00:16:05.200 --> 00:16:07.559 For every action, there is an equal and opposite reaction. 332 00:16:07.960 --> 00:16:11.480 As the sublimating gas violently fires outward into space, the 333 00:16:11.480 --> 00:16:14.519 physical force of that ejection pushes back against the solid 334 00:16:14.519 --> 00:16:15.480 surface of the comet. 335 00:16:15.600 --> 00:16:18.200 It is the exact same mechanical principle that propels a 336 00:16:18.240 --> 00:16:20.039 SpaceX rocket off a launch pad. 337 00:16:20.159 --> 00:16:21.360 That's a great way to picture it. 338 00:16:21.440 --> 00:16:25.399 The rocket forces combustion gases downward, and the equal opposite 339 00:16:25.399 --> 00:16:28.600 reaction pushes the massive physical structure of the rocket upward. 340 00:16:28.840 --> 00:16:32.440 On forty one p the sublimating ice is acting identically 341 00:16:32.480 --> 00:16:36.720 to chemical propellant. The comet has essentially grown a series 342 00:16:36.759 --> 00:16:41.679 of organic, entirely uncontrollable rocket thrusters all over its surface. 343 00:16:41.840 --> 00:16:44.799 The wait, if you have thrusters covering the entire surface 344 00:16:44.840 --> 00:16:48.000 of a sphere pushing equally in all directions, the forces 345 00:16:48.000 --> 00:16:49.000 would just cancel each. 346 00:16:48.840 --> 00:16:51.039 Other out, you would think, so, yes, the comet. 347 00:16:50.720 --> 00:16:54.080 Would just sit inside a glowing ball of its own gas. Yeah, 348 00:16:54.080 --> 00:16:56.360 I mean it might get pushed slightly outward away from 349 00:16:56.360 --> 00:16:59.360 the sun by solar wind, but its spin would violently 350 00:16:59.360 --> 00:17:00.519 throw itself into reverse. 351 00:17:00.720 --> 00:17:00.919 Right. 352 00:17:01.039 --> 00:17:05.559 But you are assuming a comet is a perfect smooth sphere, 353 00:17:05.599 --> 00:17:08.160 and they almost never are because forty one P is 354 00:17:08.200 --> 00:17:12.839 so small it lacks the necessary mass to achieve hydrostatic equilibrium, 355 00:17:12.880 --> 00:17:16.079 which is what that's the gravitational force that pulls planets 356 00:17:16.079 --> 00:17:19.279 and large moons into perfect round shapes. Forty one P 357 00:17:19.480 --> 00:17:23.720 is lumpy, irregular, scarred, and completely asymmetrical. It looks more 358 00:17:23.759 --> 00:17:25.480 like a battered potato than a billiard ball. 359 00:17:25.640 --> 00:17:29.359 Ah okay, And because the shape is asymmetrical, the distribution 360 00:17:29.440 --> 00:17:30.559 of the ice is asymmetrical. 361 00:17:30.720 --> 00:17:35.079 Exactly, the active areas, the exposed patches of volatilized that 362 00:17:35.119 --> 00:17:40.240 create the strongest jets, were unevenly distributed across its irregular. 363 00:17:39.720 --> 00:17:42.559 Surface, so it's not a uniform push, not at all. 364 00:17:43.000 --> 00:17:46.400 So when the sun hit those patches, the thrusters didn't 365 00:17:46.400 --> 00:17:50.440 fire symmetrically. They fired off center, they fired at odd angles, 366 00:17:50.920 --> 00:17:53.799 and the dominant force of those asymmetrical jets happened to 367 00:17:53.839 --> 00:17:56.839 push directly against the comet's original rotational motion. 368 00:17:57.200 --> 00:18:00.039 Here's where it gets really interesting because Jewett used a 369 00:18:00.079 --> 00:18:03.559 brilliant analogy in his analysis to make sense of this torque. 370 00:18:03.599 --> 00:18:07.119 He compared the comet to a playground merry go round. 371 00:18:07.279 --> 00:18:09.000 Such a helpful visual it really is. 372 00:18:09.319 --> 00:18:12.759 Imagine a heavy metal merry go round spinning steadily to 373 00:18:12.799 --> 00:18:14.720 the left. If you run up to it and start 374 00:18:14.759 --> 00:18:18.079 aggressively pushing against the metal bars, forcing them to the right, 375 00:18:18.519 --> 00:18:21.000 the merry go round doesn't just instantly snap into reverse. 376 00:18:21.160 --> 00:18:22.480 No, as momentum right. 377 00:18:22.559 --> 00:18:25.400 The first thing that happens is it begins to aggressively decelerate. 378 00:18:25.640 --> 00:18:29.640 Your pushing is fighting against the established angular momentum. 379 00:18:29.160 --> 00:18:32.680 And that deceleration is exactly what the Swift observatory captured 380 00:18:32.680 --> 00:18:36.599 in May of twenty seventeen AH the slowdown. Yes, the 381 00:18:36.640 --> 00:18:41.000 Sun's intense heat had activated the comet's asymmetrical thrusters, and 382 00:18:41.039 --> 00:18:45.319 the physical force of those gas ejections started pushing continuously 383 00:18:45.440 --> 00:18:49.039 against the comet's natural forward spin. The spin was bleeding 384 00:18:49.039 --> 00:18:52.640 off energy, slowing to that sluggish sixty hour crawl. 385 00:18:52.799 --> 00:18:56.599 But the Sun doesn't just turn off. The thermal shot continues. 386 00:18:56.680 --> 00:19:00.720 As the comet gets closer to perihelion, the sublimation doesn't stop. 387 00:19:00.839 --> 00:19:02.880 It actually accelerates. 388 00:19:02.440 --> 00:19:06.519 Right, so back to the playground. You don't stop pushing 389 00:19:06.519 --> 00:19:09.319 the merry go round to the right. You keep applying force. 390 00:19:09.759 --> 00:19:13.039 Eventually the forward momentum is entirely depleted. The merry go 391 00:19:13.119 --> 00:19:14.440 round grounds to a dead stop. 392 00:19:14.519 --> 00:19:15.640 It is your own momentum. 393 00:19:15.680 --> 00:19:18.160 And then, because you are still leaning your entire weight 394 00:19:18.240 --> 00:19:20.839 into it pushing right, it begins to accelerate into a 395 00:19:20.920 --> 00:19:22.559 right word spin exactly. 396 00:19:22.680 --> 00:19:27.640 The continuous, wildly uneven outgassing eventually overpowered the entirety of 397 00:19:27.640 --> 00:19:29.599 the comet's original angular momentum. 398 00:19:29.640 --> 00:19:31.160 It's mind boggling, it really is. 399 00:19:31.200 --> 00:19:33.880 It applied enough counter torque to stop a one kilometer 400 00:19:33.960 --> 00:19:36.079 rock dead in its tracks, and then functioned as a 401 00:19:36.119 --> 00:19:38.880