1 00:00:00,000 --> 00:00:01,960 Welcome back to Cosmos in a Pod, Space, 2 00:00:01,960 --> 00:00:05,040 and Astronomy series, episode 14. 3 00:00:05,920 --> 00:00:10,200 Today, we're going deep, deep into the Milky Way galaxy, 4 00:00:10,200 --> 00:00:11,360 our cosmic home. 5 00:00:11,360 --> 00:00:12,200 That's right. 6 00:00:12,200 --> 00:00:14,660 We'll be journeying through billions of years 7 00:00:14,660 --> 00:00:17,760 from the Milky Way's formation to its ultimate fate, 8 00:00:17,760 --> 00:00:19,400 uncovering fascinating facts 9 00:00:19,400 --> 00:00:21,440 and some mind-blowing concepts along the way. 10 00:00:21,440 --> 00:00:22,520 It'll be a wild ride. 11 00:00:22,520 --> 00:00:23,400 Buckle up. Yeah. 12 00:00:23,400 --> 00:00:26,560 Okay, let's rewind all the way back to the Big Bang, 13 00:00:26,560 --> 00:00:29,080 roughly 13.8 billion years ago. 14 00:00:29,080 --> 00:00:29,920 Yeah. 15 00:00:29,920 --> 00:00:32,120 Where does the story of the Milky Way even begin? 16 00:00:32,120 --> 00:00:34,360 So it all starts with these tiny fluctuations, 17 00:00:34,360 --> 00:00:36,380 little, little tiny fluctuations 18 00:00:36,380 --> 00:00:39,400 in the density of dark matter and gas 19 00:00:39,400 --> 00:00:41,520 just moments after the Big Bang. 20 00:00:41,520 --> 00:00:43,080 Think of them like little seeds 21 00:00:43,080 --> 00:00:45,780 scattered across the vastness of space. 22 00:00:45,780 --> 00:00:47,880 Gravity gradually pulled these seeds together, 23 00:00:47,880 --> 00:00:49,880 causing them to grow and merge, 24 00:00:49,880 --> 00:00:52,120 eventually forming the first galaxies, 25 00:00:52,120 --> 00:00:53,880 including our own Milky Way. 26 00:00:53,880 --> 00:00:55,680 So from these tiny irregularities, 27 00:00:55,680 --> 00:00:58,080 something as immense as the Milky Way emerged. 28 00:00:58,080 --> 00:00:59,580 It's hard to wrap my head around that. 29 00:00:59,580 --> 00:01:01,840 These early building blocks, what were they like? 30 00:01:01,840 --> 00:01:04,200 Yeah, so these were proto-galaxies, 31 00:01:04,200 --> 00:01:07,400 swirling clouds of mostly hydrogen and helium, 32 00:01:07,400 --> 00:01:09,440 the leftover ingredients from the Big Bang. 33 00:01:09,440 --> 00:01:10,280 Okay. 34 00:01:10,280 --> 00:01:12,000 Imagine this cosmic dance 35 00:01:12,000 --> 00:01:15,120 with these proto-galaxies constantly colliding and merging, 36 00:01:15,120 --> 00:01:18,080 creating larger and more complex structures. 37 00:01:18,080 --> 00:01:21,700 So the early universe was a pretty wild and chaotic place 38 00:01:21,700 --> 00:01:23,680 with these proto-galaxies just bumping 39 00:01:23,680 --> 00:01:24,840 and grinding into each other. 40 00:01:24,840 --> 00:01:25,680 Yeah. 41 00:01:25,680 --> 00:01:27,600 I'd imagine things were pretty hot and explosive back then. 42 00:01:27,600 --> 00:01:29,040 Absolutely, you're right. 43 00:01:29,040 --> 00:01:32,640 Within these proto-galaxies, the very first stars ignited. 44 00:01:32,640 --> 00:01:35,000 These were the population thousand stars, 45 00:01:35,000 --> 00:01:38,520 massive giants composed purely of hydrogen and helium. 46 00:01:38,520 --> 00:01:40,880 These stars lived fast and died young, 47 00:01:40,880 --> 00:01:43,720 ending their lives in spectacular supernova explosions. 48 00:01:43,720 --> 00:01:46,220 Supernovae, I remember learning about those in school. 49 00:01:46,220 --> 00:01:47,940 They're like cosmic fireworks, right? 50 00:01:47,940 --> 00:01:49,500 But they're more than just pretty lights, aren't they? 51 00:01:49,500 --> 00:01:50,540 Precisely. 52 00:01:50,540 --> 00:01:53,240 Supernovae are essential for creating the elements 53 00:01:53,240 --> 00:01:56,580 that make up, well, everything we know, including ourselves. 54 00:01:56,580 --> 00:01:58,680 When these massive stars explode, 55 00:01:58,680 --> 00:02:02,000 they forge heavier elements like carbon, oxygen, and iron 56 00:02:02,000 --> 00:02:03,800 and scatter them across space. 57 00:02:03,800 --> 00:02:05,560 These elements become the building blocks 58 00:02:05,560 --> 00:02:08,440 for future generations of stars and planets 59 00:02:08,440 --> 00:02:10,280 and ultimately life itself. 60 00:02:10,280 --> 00:02:12,840 Wow, so we literally owe our existence 61 00:02:12,840 --> 00:02:14,400 to those ancient exploding stars. 62 00:02:14,400 --> 00:02:15,440 That's incredible. 63 00:02:15,440 --> 00:02:18,940 Okay, so we had these mergers creating a larger galaxy, 64 00:02:18,940 --> 00:02:22,520 but how did the Milky Way get its iconic spiral shape? 65 00:02:22,520 --> 00:02:23,680 That's a great question. 66 00:02:23,680 --> 00:02:25,200 About 10 billion years ago, 67 00:02:25,200 --> 00:02:28,320 gravity and the spinning motion of all that gas and dust, 68 00:02:28,320 --> 00:02:32,360 it caused the Milky Way to flatten out into a rotating disk. 69 00:02:32,360 --> 00:02:33,920 Think of it like spinning pizza dough. 70 00:02:33,920 --> 00:02:36,400 It spreads out and becomes thinner as it spins. 71 00:02:36,400 --> 00:02:38,240 This disk is where the action is. 72 00:02:38,240 --> 00:02:39,960 It's full of gas and dust, 73 00:02:39,960 --> 00:02:42,160 the perfect ingredients for forming new stars, 74 00:02:42,160 --> 00:02:43,680 including our own sun. 75 00:02:43,680 --> 00:02:46,200 So the disk is like the bustling heart of the Milky Way, 76 00:02:46,200 --> 00:02:48,100 a cosmic nursery for stars. 77 00:02:48,100 --> 00:02:50,200 What about those mesmerizing spiral arms? 78 00:02:50,200 --> 00:02:52,720 They're so prominent in images of spiral galaxies. 79 00:02:52,720 --> 00:02:53,960 What even creates them? 80 00:02:53,960 --> 00:02:56,800 Yeah, those spiral arms, they aren't fixed structures, 81 00:02:56,800 --> 00:02:58,480 but rather waves of density 82 00:02:58,480 --> 00:03:00,220 that move through the galaxy's disk. 83 00:03:00,220 --> 00:03:01,960 Think of it like a traffic jam in space. 84 00:03:01,960 --> 00:03:02,800 Okay. 85 00:03:02,800 --> 00:03:06,120 As these waves pass through, they compress gas and dust, 86 00:03:06,120 --> 00:03:08,320 triggering bursts of star formation. 87 00:03:08,320 --> 00:03:10,100 This is why spiral arms appear so bright. 88 00:03:10,100 --> 00:03:11,920 They're filled with young hot stars. 89 00:03:11,920 --> 00:03:13,560 So it's not just a beautiful design, 90 00:03:13,560 --> 00:03:15,000 it's a dynamic process 91 00:03:15,000 --> 00:03:16,640 that's constantly shaping the galaxy. 92 00:03:16,640 --> 00:03:18,040 That's fascinating. 93 00:03:18,040 --> 00:03:20,640 Now, we can't forget about the central bulge, 94 00:03:20,640 --> 00:03:23,800 that bright, dense region at the heart of the Milky Way. 95 00:03:23,800 --> 00:03:24,760 What's happening in there? 96 00:03:24,760 --> 00:03:27,760 The central bulge is like a time capsule, 97 00:03:27,760 --> 00:03:30,440 home to some of the Milky Way's oldest stars, 98 00:03:30,440 --> 00:03:32,640 formed early in the galaxy's history. 99 00:03:32,640 --> 00:03:34,880 It's a dense and crowded region, 100 00:03:34,880 --> 00:03:36,880 and at its very heart lies a monster. 101 00:03:36,880 --> 00:03:37,720 Oh. 102 00:03:37,720 --> 00:03:41,040 Supermassive black hole called Sagittarius A. 103 00:03:41,040 --> 00:03:41,880 A black hole. 104 00:03:41,880 --> 00:03:43,360 Now, that's what I call a plot twist. 105 00:03:43,360 --> 00:03:44,200 Tell me more. 106 00:03:44,200 --> 00:03:46,260 Sagittarius A is a gravitational giant 107 00:03:46,260 --> 00:03:49,400 with a mass equivalent to about four million suns. 108 00:03:49,400 --> 00:03:50,640 While we can't see it directly, 109 00:03:50,640 --> 00:03:53,080 its immense gravity affects the motion of stars 110 00:03:53,080 --> 00:03:54,400 and gas all around it. 111 00:03:54,400 --> 00:03:56,820 So this invisible monster is essentially controlling 112 00:03:56,820 --> 00:03:58,200 the galactic center, 113 00:03:58,200 --> 00:04:00,140 pulling the strings of the entire region. 114 00:04:00,140 --> 00:04:01,040 You got it. 115 00:04:01,040 --> 00:04:02,560 Its influence is profound. 116 00:04:02,560 --> 00:04:04,320 It plays a key role in the evolution 117 00:04:04,320 --> 00:04:05,720 of the galaxy as a whole. 118 00:04:05,720 --> 00:04:08,600 So we've got this bustling disk where stars are forming, 119 00:04:08,600 --> 00:04:10,680 the majestic spiral arms, 120 00:04:10,680 --> 00:04:13,160 and this enigmatic central bulge 121 00:04:13,160 --> 00:04:16,760 with its supermassive black hole lurking within. 122 00:04:16,760 --> 00:04:18,880 But the Milky Way doesn't stop there, does it? 123 00:04:18,880 --> 00:04:20,900 There's more to explore beyond the disk, right? 124 00:04:20,900 --> 00:04:22,240 You are absolutely right. 125 00:04:22,240 --> 00:04:23,840 Surrounding the disk in the bulge 126 00:04:23,840 --> 00:04:27,240 is a vast spherical region called the Galactic Halo. 127 00:04:27,240 --> 00:04:29,380 It's like a giant invisible bubble 128 00:04:29,380 --> 00:04:32,040 encompassing the entire Milky Way. 129 00:04:32,040 --> 00:04:33,640 What's out there in this halo? 130 00:04:33,640 --> 00:04:35,160 Is it just empty space? 131 00:04:35,160 --> 00:04:36,320 No, not at all. 132 00:04:36,320 --> 00:04:38,480 The halo is home to ancient stars, 133 00:04:38,480 --> 00:04:40,220 some of the oldest in the Milky Way, 134 00:04:40,220 --> 00:04:41,740 as well as globular clusters, 135 00:04:41,740 --> 00:04:43,600 tightly packed groups of thousands 136 00:04:43,600 --> 00:04:45,040 or even millions of stars. 137 00:04:45,040 --> 00:04:45,860 Wow. 138 00:04:45,860 --> 00:04:47,320 These objects provide valuable clues 139 00:04:47,320 --> 00:04:49,000 about the galaxy's early history, 140 00:04:49,000 --> 00:04:50,640 acting like cosmic fossils, 141 00:04:50,640 --> 00:04:52,960 preserving remnants of the Milky Way's past. 142 00:04:52,960 --> 00:04:55,920 So the halo is like a treasure trove of ancient relics, 143 00:04:55,920 --> 00:04:57,840 offering glimpses into the Milky Way's 144 00:04:57,840 --> 00:04:59,920 long and eventful history. 145 00:04:59,920 --> 00:05:03,800 Now, I've heard about this concept of galactic cannibalism. 146 00:05:03,800 --> 00:05:06,700 Is that something that the Milky Way has engaged in? 147 00:05:06,700 --> 00:05:07,760 Indeed. 148 00:05:07,760 --> 00:05:10,160 The Milky Way, it didn't reach its current size 149 00:05:10,160 --> 00:05:12,340 by simply existing peacefully. 150 00:05:12,340 --> 00:05:14,600 It has a history of merging with 151 00:05:14,600 --> 00:05:18,180 and absorbing smaller galaxies over billions of years. 152 00:05:18,180 --> 00:05:21,980 So the Milky Way has been on a cosmic shopping spree, 153 00:05:21,980 --> 00:05:23,660 gobbling up its smaller neighbors. 154 00:05:23,660 --> 00:05:24,840 You could say that. 155 00:05:24,840 --> 00:05:26,120 And we can actually see evidence 156 00:05:26,120 --> 00:05:28,040 of this galactic cannibalism 157 00:05:28,040 --> 00:05:30,040 in the form of stellar streams. 158 00:05:30,040 --> 00:05:33,880 These are long, ribbon-like trails of stars left behind 159 00:05:33,880 --> 00:05:36,120 as dwarf galaxies are torn apart 160 00:05:36,120 --> 00:05:37,620 by the Milky Way's gravity. 161 00:05:37,620 --> 00:05:40,200 It's like the Milky Way leaves a trail of cosmic crumbs 162 00:05:40,200 --> 00:05:42,400 behind after its galactic feast. 163 00:05:42,400 --> 00:05:45,280 What about our galactic neighbors, the Magellanic Clouds? 164 00:05:45,280 --> 00:05:47,560 Are they also destined to be consumed by the Milky Way? 165 00:05:47,560 --> 00:05:49,160 That's a very real possibility. 166 00:05:49,160 --> 00:05:50,160 The Magellanic Clouds, 167 00:05:50,160 --> 00:05:51,960 they're currently orbiting the Milky Way, 168 00:05:51,960 --> 00:05:53,360 but their fate is uncertain. 169 00:05:53,360 --> 00:05:56,960 It's a cosmic dance with these gravitational forces at play, 170 00:05:56,960 --> 00:05:58,920 potentially leading to their eventual merger 171 00:05:58,920 --> 00:05:59,960 with our galaxy. 172 00:05:59,960 --> 00:06:02,440 So the Milky Way might continue to grow and evolve, 173 00:06:02,440 --> 00:06:04,400 adding to its already impressive collection 174 00:06:04,400 --> 00:06:05,560 of stars and gas. 175 00:06:05,560 --> 00:06:07,540 Okay, so let's recap. 176 00:06:07,540 --> 00:06:10,640 We have this magnificent barred spiral galaxy 177 00:06:10,640 --> 00:06:12,640 with its distinctive spiral arms, 178 00:06:12,640 --> 00:06:15,480 the center bulge housing a supermassive black hole, 179 00:06:15,480 --> 00:06:18,560 and this vast halo surrounding it all. 180 00:06:18,560 --> 00:06:22,080 But where do we fit into this grand cosmic picture? 181 00:06:22,080 --> 00:06:24,040 Where's our little solar system located 182 00:06:24,040 --> 00:06:25,600 within this vast structure? 183 00:06:25,600 --> 00:06:28,200 Our solar system resides in the Orion Arm, 184 00:06:28,200 --> 00:06:29,920 a relatively minor spiral arm 185 00:06:29,920 --> 00:06:33,400 located about 26,000 light years from the galactic center. 186 00:06:33,400 --> 00:06:35,540 It's a relatively quiet and calm region, 187 00:06:35,540 --> 00:06:36,680 which has been beneficial 188 00:06:36,680 --> 00:06:38,120 for the development of life on Earth. 189 00:06:38,120 --> 00:06:40,760 So we're tucked away in a peaceful corner of the Milky Way, 190 00:06:40,760 --> 00:06:43,140 far from the chaos of the galactic center. 191 00:06:43,140 --> 00:06:44,280 That's good to know. 192 00:06:44,280 --> 00:06:46,000 Now, to put things into perspective, 193 00:06:46,000 --> 00:06:47,740 how big is the Milky Way exactly? 194 00:06:47,740 --> 00:06:50,120 The Milky Way is a true behemoth. 195 00:06:50,120 --> 00:06:53,540 It spans about 100,000 light years in diameter. 196 00:06:53,540 --> 00:06:54,880 To put that into perspective, 197 00:06:54,880 --> 00:06:57,020 if you could travel at the speed of light, 198 00:06:57,020 --> 00:07:00,840 it would still take you 100,000 years to cross our galaxy. 199 00:07:00,840 --> 00:07:03,360 It contains hundreds of billions of stars. 200 00:07:03,360 --> 00:07:06,120 Some estimates put it at its highest 400 billion, 201 00:07:06,120 --> 00:07:09,400 along with countless planets, moons, asteroids, 202 00:07:09,400 --> 00:07:11,840 and vast clouds of gas and dust. 203 00:07:11,840 --> 00:07:14,000 Those numbers are mind-boggling. 204 00:07:14,000 --> 00:07:17,260 It makes you realize just how small and insignificant we are 205 00:07:17,260 --> 00:07:18,600 in the grand scheme of things. 206 00:07:18,600 --> 00:07:21,560 So we're just one tiny planet orbiting one star 207 00:07:21,560 --> 00:07:24,400 among hundreds of billions in this vast galaxy. 208 00:07:24,400 --> 00:07:27,020 And the Milky Way itself is just one of countless galaxies 209 00:07:27,020 --> 00:07:28,400 in the observable universe. 210 00:07:28,400 --> 00:07:29,240 That's right. 211 00:07:29,240 --> 00:07:30,240 It's a humbling realization 212 00:07:30,240 --> 00:07:32,280 that puts our everyday worries into perspective. 213 00:07:32,280 --> 00:07:35,060 Now let's talk about the Milky Way's ultimate fate. 214 00:07:35,060 --> 00:07:37,160 What does the future hold for our galaxy? 215 00:07:37,160 --> 00:07:39,680 In about 4.5 billion years, 216 00:07:39,680 --> 00:07:41,560 the Milky Way is on a collision course 217 00:07:41,560 --> 00:07:44,040 with our nearest major galactic neighbor, 218 00:07:44,040 --> 00:07:45,360 the Andromeda Galaxy. 219 00:07:45,360 --> 00:07:46,800 A galactic collision. 220 00:07:46,800 --> 00:07:48,680 That sounds like something out of a science fiction movie. 221 00:07:48,680 --> 00:07:50,920 It's certainly a dramatic event, 222 00:07:50,920 --> 00:07:53,560 but it's not as catastrophic as you might imagine. 223 00:07:53,560 --> 00:07:55,680 The distances between stars are so vast 224 00:07:55,680 --> 00:07:58,360 that individual stars colliding is unlikely. 225 00:07:58,360 --> 00:08:00,960 Instead, it'll be more of a galactic merger. 226 00:08:00,960 --> 00:08:03,840 The gravitational forces will reshape both galaxies, 227 00:08:03,840 --> 00:08:07,360 eventually creating a new, larger elliptical galaxy, 228 00:08:07,360 --> 00:08:09,480 often nicknamed Milcomeda. 229 00:08:09,480 --> 00:08:10,800 Milcomeda, I love it. 230 00:08:10,800 --> 00:08:12,080 It's like a cosmic mashup, 231 00:08:12,080 --> 00:08:14,500 the ultimate blend of two galaxies. 232 00:08:14,500 --> 00:08:16,200 So the Milky Way, as we know it, 233 00:08:16,200 --> 00:08:18,080 will cease to exist, 234 00:08:18,080 --> 00:08:21,240 but it'll be reborn as part of this new giant galaxy. 235 00:08:21,240 --> 00:08:22,760 It's a reminder that the universe 236 00:08:22,760 --> 00:08:24,560 is constantly evolving and changing. 237 00:08:24,560 --> 00:08:25,400 Exactly. 238 00:08:25,400 --> 00:08:27,260 And this collision is just one chapter 239 00:08:27,260 --> 00:08:30,000 in the Milky Way's long and eventful story. 240 00:08:30,000 --> 00:08:32,760 Well, this deep dive has already been incredibly insightful. 241 00:08:32,760 --> 00:08:34,920 We've journeyed through the Milky Way's formation, 242 00:08:34,920 --> 00:08:36,200 explored its structure, 243 00:08:36,200 --> 00:08:38,520 and even glimpsed its ultimate fate. 244 00:08:38,520 --> 00:08:41,440 But I know there's still so much more to uncover. 245 00:08:41,440 --> 00:08:43,720 Are there any lingering mysteries about the Milky Way 246 00:08:43,720 --> 00:08:45,840 that scientists are still trying to solve? 247 00:08:45,840 --> 00:08:46,960 Absolutely. 248 00:08:46,960 --> 00:08:48,480 Despite all we've learned, 249 00:08:48,480 --> 00:08:52,000 there are still many unanswered questions about our galaxy. 250 00:08:52,000 --> 00:08:54,440 For example, we're still trying to understand 251 00:08:54,440 --> 00:08:56,080 how Sagittarius A, 252 00:08:56,080 --> 00:08:58,600 that supermassive black hole at the center, 253 00:08:58,600 --> 00:09:00,360 actually formed. 254 00:09:00,360 --> 00:09:03,280 Another big mystery is the nature of dark matter. 255 00:09:03,280 --> 00:09:05,440 This mysterious substance seems to make up 256 00:09:05,440 --> 00:09:08,280 a significant portion of the Milky Way's mass, 257 00:09:08,280 --> 00:09:10,380 but we still don't know what it is. 258 00:09:10,380 --> 00:09:12,640 So even with all our technological advancements, 259 00:09:12,640 --> 00:09:15,620 the Milky Way still holds many secrets. 260 00:09:15,620 --> 00:09:18,380 It seems like there's always more to learn and explore. 261 00:09:18,380 --> 00:09:19,940 That's the beauty of science. 262 00:09:19,940 --> 00:09:22,040 It's a continuous journey of discovery, 263 00:09:22,040 --> 00:09:24,980 and the Milky Way is a vast and complex laboratory 264 00:09:24,980 --> 00:09:27,540 full of wonders waiting to be revealed. 265 00:09:27,540 --> 00:09:29,680 Well, this has been an absolutely mind-blowing start 266 00:09:29,680 --> 00:09:31,580 to our deep dive into the Milky Way. 267 00:09:31,580 --> 00:09:33,000 We've covered so much ground, 268 00:09:33,000 --> 00:09:34,260 from the galaxy's formation 269 00:09:34,260 --> 00:09:36,440 to its eventual merger with Andromeda. 270 00:09:36,440 --> 00:09:39,560 Join us for part two of our Milky Way exploration, 271 00:09:39,560 --> 00:09:41,800 where we'll delve into the mysteries of dark matter, 272 00:09:41,800 --> 00:09:43,640 uncover the secrets of exoplanets, 273 00:09:43,640 --> 00:09:45,320 and explore the ongoing research 274 00:09:45,320 --> 00:09:47,160 that's pushing the boundaries of our understanding 275 00:09:47,160 --> 00:09:48,280 of our cosmic home. 276 00:09:48,280 --> 00:09:49,720 Until then, keep looking up 277 00:09:49,720 --> 00:09:51,560 and never stop questioning the universe. 278 00:09:51,560 --> 00:09:52,400 I'll see you there. 279 00:09:52,400 --> 00:09:53,560 All right. Bye. 280 00:09:53,560 --> 00:09:54,820 Bye. 281 00:09:54,820 --> 00:09:58,400 Welcome back to our cosmic journey through the Milky Way. 282 00:09:58,400 --> 00:10:01,560 Last time, we talked about the Milky Way's impressive size, 283 00:10:01,560 --> 00:10:04,480 its dramatic history of galactic cannibalism, 284 00:10:04,480 --> 00:10:07,200 and its future collision with Andromeda. 285 00:10:07,200 --> 00:10:09,720 This time, we'll delve into some of the more mysterious 286 00:10:09,720 --> 00:10:13,320 aspects of our galaxy, starting with dark matter. 287 00:10:13,320 --> 00:10:15,400 You mentioned earlier that dark matter makes up 288 00:10:15,400 --> 00:10:18,240 a significant portion of the Milky Way's mass, 289 00:10:18,240 --> 00:10:21,200 but we can't see it or directly detect it. 290 00:10:21,200 --> 00:10:22,320 It sounds like something straight out 291 00:10:22,320 --> 00:10:23,400 of a science fiction novel. 292 00:10:23,400 --> 00:10:24,220 It is. 293 00:10:24,220 --> 00:10:27,360 It's one of the biggest mysteries in astrophysics. 294 00:10:27,360 --> 00:10:29,680 It's fascinating and a little bit spooky 295 00:10:29,680 --> 00:10:34,160 to think about all that unseen matter just out there. 296 00:10:34,160 --> 00:10:36,440 So how do we even know it's there if we can't see it? 297 00:10:36,440 --> 00:10:38,600 Well, we can infer its presence 298 00:10:38,600 --> 00:10:40,560 through its gravitational effects. 299 00:10:40,560 --> 00:10:43,120 So imagine you're watching a merry-go-round spinning. 300 00:10:43,120 --> 00:10:43,520 OK. 301 00:10:43,520 --> 00:10:45,200 You notice that the horses on the outer edge 302 00:10:45,200 --> 00:10:47,040 are moving much faster than you'd expect, 303 00:10:47,040 --> 00:10:49,280 based on the visible structure of the merry-go-round. 304 00:10:49,280 --> 00:10:51,120 That would suggest there's some unseen mass, 305 00:10:51,120 --> 00:10:53,320 some hidden force providing the extra gravity 306 00:10:53,320 --> 00:10:55,560 to keep those horses from flying off. 307 00:10:55,560 --> 00:10:57,520 That's a great analogy. 308 00:10:57,520 --> 00:10:59,800 So we see stars and gas moving faster 309 00:10:59,800 --> 00:11:02,840 than they should in galaxies, including the Milky Way, 310 00:11:02,840 --> 00:11:06,080 indicating there's something massive out there that we can't see. 311 00:11:06,080 --> 00:11:08,400 What could this mysterious dark matter be? 312 00:11:08,400 --> 00:11:10,760 That's the million dollar question. 313 00:11:10,760 --> 00:11:13,160 Scientists have proposed many theories. 314 00:11:13,160 --> 00:11:15,640 Some believe it's made up of exotic particles, 315 00:11:15,640 --> 00:11:18,440 unlike anything we've ever detected before. 316 00:11:18,440 --> 00:11:21,080 Others propose it could be tiny black holes, 317 00:11:21,080 --> 00:11:23,600 or other objects that don't emit light. 318 00:11:23,600 --> 00:11:26,560 The search is ongoing, with experiments and observations 319 00:11:26,560 --> 00:11:29,440 around the world and in space trying to unravel 320 00:11:29,440 --> 00:11:31,120 the secrets of dark matter. 321 00:11:31,120 --> 00:11:33,480 It's incredible to think that something so fundamental 322 00:11:33,480 --> 00:11:36,200 to the universe remains such a mystery. 323 00:11:36,200 --> 00:11:38,120 Speaking of mysteries, let's shift gears a bit 324 00:11:38,120 --> 00:11:40,520 and talk about another fascinating topic. 325 00:11:40,520 --> 00:11:41,880 Exoplanets. 326 00:11:41,880 --> 00:11:45,040 These are planets that orbit stars outside our solar system, 327 00:11:45,040 --> 00:11:47,520 and it seems like we're discovering new ones all the time. 328 00:11:47,520 --> 00:11:50,720 How do we find these exoplanets, considering they're so far away 329 00:11:50,720 --> 00:11:53,880 and often overshadowed by the brilliance of their host stars? 330 00:11:53,880 --> 00:11:56,920 It's a remarkable feat of scientific ingenuity. 331 00:11:56,920 --> 00:11:59,000 There are a couple of clutter methods. 332 00:11:59,000 --> 00:12:00,640 One is called the transit method. 333 00:12:00,640 --> 00:12:02,960 So imagine you're watching a distant star 334 00:12:02,960 --> 00:12:05,400 and a planet passes in front of it, 335 00:12:05,400 --> 00:12:07,440 blocking a tiny bit of its light. 336 00:12:07,440 --> 00:12:10,280 We can detect this dip in brightness 337 00:12:10,280 --> 00:12:12,840 and use it to infer the presence of a planet. 338 00:12:12,840 --> 00:12:15,760 So it's like a miniature eclipse, but on a cosmic scale. 339 00:12:15,760 --> 00:12:16,760 That's amazing. 340 00:12:16,760 --> 00:12:17,800 Precisely. 341 00:12:17,800 --> 00:12:20,600 Another method is called the radial velocity method. 342 00:12:20,600 --> 00:12:24,080 As a planet orbits a star, its gravity tugs on the star, 343 00:12:24,080 --> 00:12:26,000 causing it to wobble slightly. 344 00:12:26,000 --> 00:12:28,320 We can detect this wobble by carefully measuring 345 00:12:28,320 --> 00:12:31,240 the star's light spectrum, revealing the presence 346 00:12:31,240 --> 00:12:32,880 of an unseen companion. 347 00:12:32,880 --> 00:12:35,880 So by carefully observing the light from distant stars, 348 00:12:35,880 --> 00:12:37,880 we can indirectly detect the presence 349 00:12:37,880 --> 00:12:39,520 of planets orbiting them. 350 00:12:39,520 --> 00:12:42,640 It's like deciphering a secret code hidden within starlight. 351 00:12:42,640 --> 00:12:43,440 Exactly. 352 00:12:43,440 --> 00:12:45,720 And these techniques have revealed a truly astonishing 353 00:12:45,720 --> 00:12:47,440 diversity of exoplanets. 354 00:12:47,440 --> 00:12:49,880 We've found gas giants larger than Jupiter, 355 00:12:49,880 --> 00:12:52,880 rocky planets like Earth, and everything in between. 356 00:12:52,880 --> 00:12:54,880 We've even found planets orbiting two stars, 357 00:12:54,880 --> 00:12:56,480 like something out of Star Wars. 358 00:12:56,480 --> 00:12:57,240 Wow. 359 00:12:57,240 --> 00:12:58,200 That's incredible. 360 00:12:58,200 --> 00:13:00,760 Makes you wonder what other strange and wonderful worlds 361 00:13:00,760 --> 00:13:02,640 are out there waiting to be discovered. 362 00:13:02,640 --> 00:13:04,680 Now back to the Milky Way. 363 00:13:04,680 --> 00:13:06,680 How many exoplanets do we think are 364 00:13:06,680 --> 00:13:08,840 out there in our own galaxy? 365 00:13:08,840 --> 00:13:10,400 Based on our current understanding, 366 00:13:10,400 --> 00:13:12,960 it's estimated that there could be more planets than stars 367 00:13:12,960 --> 00:13:13,840 in the Milky Way. 368 00:13:13,840 --> 00:13:17,280 So potentially hundreds of billions of planets 369 00:13:17,280 --> 00:13:18,880 in our galaxy alone. 370 00:13:18,880 --> 00:13:20,600 That's mind boggling. 371 00:13:20,600 --> 00:13:23,360 Do we think any of these planets could be habitable, 372 00:13:23,360 --> 00:13:24,280 like Earth? 373 00:13:24,280 --> 00:13:27,280 That's a question that drives a lot of current research. 374 00:13:27,280 --> 00:13:29,080 The search for habitable exoplanets 375 00:13:29,080 --> 00:13:32,040 is one of the most exciting areas of astronomy. 376 00:13:32,040 --> 00:13:34,200 We're looking for planets in the habitable zone 377 00:13:34,200 --> 00:13:37,760 of their stars, the region where conditions might be just right 378 00:13:37,760 --> 00:13:40,200 for liquid water to exist on the surface, which 379 00:13:40,200 --> 00:13:42,760 is considered a key ingredient for life as we know it. 380 00:13:42,760 --> 00:13:45,280 It's thrilling to think that there could be other worlds out 381 00:13:45,280 --> 00:13:47,640 there with oceans, continents, and maybe even 382 00:13:47,640 --> 00:13:48,960 some form of life. 383 00:13:48,960 --> 00:13:51,880 It makes you feel a little less alone in the vastness of space. 384 00:13:51,880 --> 00:13:53,080 It certainly does. 385 00:13:53,080 --> 00:13:55,360 The possibility of finding life beyond Earth 386 00:13:55,360 --> 00:13:57,320 is one of the most profound questions 387 00:13:57,320 --> 00:13:58,920 humanity has ever asked. 388 00:13:58,920 --> 00:14:02,040 This deep dive into the Milky Way has been incredible. 389 00:14:02,040 --> 00:14:05,040 It's humbling to learn about the sheer scale and complexity 390 00:14:05,040 --> 00:14:07,600 of our galaxy, and to realize how much 391 00:14:07,600 --> 00:14:09,520 we still don't know. 392 00:14:09,520 --> 00:14:12,280 But as you said earlier, that's the beauty of science. 393 00:14:12,280 --> 00:14:14,200 It's a journey of discovery. 394 00:14:14,200 --> 00:14:16,720 And the Milky Way provides an endless frontier 395 00:14:16,720 --> 00:14:18,440 for exploration. 396 00:14:18,440 --> 00:14:21,480 Join us for the final part of our Milky Way deep dive, 397 00:14:21,480 --> 00:14:23,440 where we'll discuss some of the ongoing research 398 00:14:23,440 --> 00:14:25,400 and future missions that are poised 399 00:14:25,400 --> 00:14:27,200 to revolutionize our understanding 400 00:14:27,200 --> 00:14:28,800 of our cosmic home. 401 00:14:28,800 --> 00:14:31,560 Until then, keep looking up and never stop 402 00:14:31,560 --> 00:14:34,600 questioning the universe. 403 00:14:34,600 --> 00:14:37,320 Welcome back to the final part of our deep dive 404 00:14:37,320 --> 00:14:38,720 into the Milky Way. 405 00:14:38,720 --> 00:14:41,200 We've explored the galaxy's dramatic history, 406 00:14:41,200 --> 00:14:44,040 uncovered the mysteries of dark matter and exoplanets, 407 00:14:44,040 --> 00:14:46,280 and contemplated the Milky Way's eventual merger 408 00:14:46,280 --> 00:14:47,800 with Andromeda. 409 00:14:47,800 --> 00:14:50,560 Now let's turn our attention to the present and future. 410 00:14:50,560 --> 00:14:53,000 What are some of the ongoing research efforts and missions 411 00:14:53,000 --> 00:14:54,440 that are expanding our understanding 412 00:14:54,440 --> 00:14:56,360 of this incredible galaxy we call home? 413 00:14:56,360 --> 00:14:58,160 Well, there are so many exciting projects underway. 414 00:14:58,160 --> 00:15:00,040 One that stands out is the Gaia mission, 415 00:15:00,040 --> 00:15:02,840 a space observatory launched by the European Space Agency. 416 00:15:02,840 --> 00:15:06,000 It's creating a 3D map of the Milky Way 417 00:15:06,000 --> 00:15:08,760 by measuring the positions, distances, and motions 418 00:15:08,760 --> 00:15:10,760 of over a billion stars. 419 00:15:10,760 --> 00:15:12,640 A billion stars? 420 00:15:12,640 --> 00:15:14,880 That's an astronomical amount of data. 421 00:15:14,880 --> 00:15:17,640 How does Gaia even begin to collect all that information? 422 00:15:17,640 --> 00:15:21,080 Gaia is equipped with incredibly precise instruments 423 00:15:21,080 --> 00:15:23,880 that allow it to pinpoint the locations and movements 424 00:15:23,880 --> 00:15:26,360 of stars with remarkable accuracy. 425 00:15:26,360 --> 00:15:30,080 It's like having a cosmic GPS, mapping out the stars 426 00:15:30,080 --> 00:15:31,640 with incredible detail. 427 00:15:31,640 --> 00:15:33,440 That's incredible feat of engineering. 428 00:15:33,440 --> 00:15:35,680 What kind of insights are we gaining from all this data? 429 00:15:35,680 --> 00:15:38,280 Gaia's data is revolutionizing our understanding 430 00:15:38,280 --> 00:15:41,440 of the Milky Way's structure, evolution, and history. 431 00:15:41,440 --> 00:15:43,280 We're learning about stellar streams, 432 00:15:43,280 --> 00:15:46,000 those remnants of ancient galactic mergers, 433 00:15:46,000 --> 00:15:49,320 and gaining a clearer picture of how dark matter is distributed 434 00:15:49,320 --> 00:15:50,440 throughout the galaxy. 435 00:15:50,440 --> 00:15:53,560 So it's like piecing together a giant cosmic puzzle, 436 00:15:53,560 --> 00:15:56,400 revealing the intricate workings of the Milky Way. 437 00:15:56,400 --> 00:15:58,320 You mentioned earlier that scientists are still 438 00:15:58,320 --> 00:16:00,840 trying to understand the nature of dark matter. 439 00:16:00,840 --> 00:16:03,040 Are there any missions specifically focused 440 00:16:03,040 --> 00:16:04,480 on solving that mystery? 441 00:16:04,480 --> 00:16:06,280 There are many experiments around the world 442 00:16:06,280 --> 00:16:09,320 and in space dedicated to detecting and characterizing 443 00:16:09,320 --> 00:16:11,040 dark matter particles. 444 00:16:11,040 --> 00:16:13,200 These experiments use a variety of techniques 445 00:16:13,200 --> 00:16:16,560 to try to capture these elusive particles, 446 00:16:16,560 --> 00:16:19,320 hoping to shed light on their properties and origins. 447 00:16:19,320 --> 00:16:21,760 It's like a cosmic detective story, 448 00:16:21,760 --> 00:16:23,280 with scientists searching for clues 449 00:16:23,280 --> 00:16:25,640 to unlock the secrets of this invisible substance that 450 00:16:25,640 --> 00:16:27,560 permeates the universe. 451 00:16:27,560 --> 00:16:29,880 Now, I can't let you go without asking about the James Webb 452 00:16:29,880 --> 00:16:31,080 Space Telescope. 453 00:16:31,080 --> 00:16:33,160 It's been making headlines with its stunning images 454 00:16:33,160 --> 00:16:35,080 of distant galaxies. 455 00:16:35,080 --> 00:16:38,560 What role is it playing in our understanding of the Milky Way? 456 00:16:38,560 --> 00:16:40,680 The James Webb Space Telescope is a game changer 457 00:16:40,680 --> 00:16:41,800 for astronomy. 458 00:16:41,800 --> 00:16:43,000 It's powerful. 459 00:16:43,000 --> 00:16:45,080 Its powerful infrared capabilities 460 00:16:45,080 --> 00:16:47,080 allow it to see through dust clouds, 461 00:16:47,080 --> 00:16:49,960 revealing hidden regions of star formation within the Milky 462 00:16:49,960 --> 00:16:50,520 Way. 463 00:16:50,520 --> 00:16:52,880 It's also providing us with unprecedented views 464 00:16:52,880 --> 00:16:54,600 of the galactic center, giving us 465 00:16:54,600 --> 00:16:57,320 a closer look at the supermassive black hole lurking 466 00:16:57,320 --> 00:16:58,080 there. 467 00:16:58,080 --> 00:17:00,640 Wow, it's amazing to think that we can now 468 00:17:00,640 --> 00:17:03,480 observe these cosmic phenomena with such clarity. 469 00:17:03,480 --> 00:17:06,400 With all these incredible missions and research efforts, 470 00:17:06,400 --> 00:17:09,160 it seems like we're entering a golden age of astronomy. 471 00:17:09,160 --> 00:17:10,160 Absolutely. 472 00:17:10,160 --> 00:17:12,400 We're living in an exciting time for anyone 473 00:17:12,400 --> 00:17:14,000 who's ever looked up at the night sky 474 00:17:14,000 --> 00:17:16,760 and wondered about our place in the cosmos. 475 00:17:16,760 --> 00:17:20,280 With each new discovery, we're gaining a deeper understanding 476 00:17:20,280 --> 00:17:23,120 of the Milky Way, our cosmic home. 477 00:17:23,120 --> 00:17:25,600 This deep dive has been an incredible journey. 478 00:17:25,600 --> 00:17:28,800 It's reminded me of the vastness and beauty of the universe 479 00:17:28,800 --> 00:17:32,760 and the importance of continuing to explore and ask questions. 480 00:17:32,760 --> 00:17:35,120 Thank you for joining us on this cosmic adventure. 481 00:17:35,120 --> 00:17:38,000 We hope you've enjoyed exploring the Milky Way with us. 482 00:17:38,000 --> 00:17:40,240 And remember, the universe is full of wonders 483 00:17:40,240 --> 00:17:41,520 waiting to be discovered. 484 00:17:41,520 --> 00:17:43,360 So keep looking up, stay curious, 485 00:17:43,360 --> 00:17:45,480 and don't forget to follow and subscribe to Cosmos 486 00:17:45,480 --> 00:17:59,680 and a pod for more explorations of the universe.