1 00:00:05,931 --> 00:00:09,767 We pulled the stars from the skies... 2 00:00:12,037 --> 00:00:15,039 ...and brought them down to Earth. 3 00:00:25,717 --> 00:00:28,486 But at what cost? 4 00:00:28,520 --> 00:00:31,655 When we turned on all these lights... 5 00:00:31,690 --> 00:00:34,258 we lost something precious. 6 00:00:34,292 --> 00:00:36,694 The stars. 7 00:02:30,803 --> 00:02:32,303 "Sisters of the Sun" 8 00:02:36,748 --> 00:02:40,518 A long time ago, in a world lit only by fire, 9 00:02:40,552 --> 00:02:42,353 our relationship with the stars 10 00:02:42,387 --> 00:02:44,622 was far more... 11 00:02:44,656 --> 00:02:46,123 personal. 12 00:02:46,158 --> 00:02:47,825 For thousands of generations, 13 00:02:47,859 --> 00:02:48,993 we watched the stars 14 00:02:49,027 --> 00:02:51,062 as if our lives depended on it. 15 00:02:51,096 --> 00:02:53,497 Because they did. 16 00:02:55,000 --> 00:02:57,535 We humans were not the biggest, 17 00:02:57,569 --> 00:02:58,903 the strongest, nor the fastest 18 00:02:58,937 --> 00:03:00,905 of all the animals we competed against. 19 00:03:00,939 --> 00:03:02,907 But we did have one thing going for us... 20 00:03:02,941 --> 00:03:04,675 our intelligence. 21 00:03:04,710 --> 00:03:07,044 One aspect of that was a genius 22 00:03:07,079 --> 00:03:08,512 for pattern recognition. 23 00:03:08,547 --> 00:03:11,215 Night after night, we watched the stars. 24 00:03:11,249 --> 00:03:14,185 And over time, our ancestors noticed 25 00:03:14,219 --> 00:03:17,388 that the motions of the stars across the nights of the year 26 00:03:17,422 --> 00:03:19,190 foretold changes on Earth 27 00:03:19,224 --> 00:03:22,059 that threatened or enhanced our chances for survival. 28 00:03:22,094 --> 00:03:23,728 In a time when our imaginations 29 00:03:23,762 --> 00:03:26,931 were the only stage where stories came to life, 30 00:03:26,965 --> 00:03:28,699 before there were movies or TVs 31 00:03:28,734 --> 00:03:31,202 or electronic devices of any kind, 32 00:03:31,236 --> 00:03:34,372 every human culture connected the dots 33 00:03:34,406 --> 00:03:36,274 to form their own pictures. 34 00:03:38,076 --> 00:03:40,945 These images became the illustrations of a storybook 35 00:03:40,979 --> 00:03:44,782 that, on a deeper level, was also a survival manual. 36 00:03:44,816 --> 00:03:47,885 The names and personalities of the gods, heroes, 37 00:03:47,920 --> 00:03:50,054 farm animals or familiar objects 38 00:03:50,088 --> 00:03:52,256 varied from culture to culture. 39 00:03:52,291 --> 00:03:56,694 But there was one particularly gorgeous group of stars 40 00:03:56,728 --> 00:04:00,431 known to the Ancient Greeks and to us today 41 00:04:00,465 --> 00:04:02,767 as the Pleiades, 42 00:04:02,801 --> 00:04:06,270 a star cluster formed about 100 million years ago. 43 00:04:06,305 --> 00:04:09,607 Each of them is some 40 times brighter than our Sun. 44 00:04:09,641 --> 00:04:12,610 And Alcyone, the most luminous, 45 00:04:12,644 --> 00:04:16,147 outshines our Sun 1,000 times. 46 00:04:16,181 --> 00:04:19,116 For ages, the Pleiades have been used as an eye test 47 00:04:19,151 --> 00:04:22,453 for people all over the world. 48 00:04:22,487 --> 00:04:25,323 If you could see at least six of them, 49 00:04:25,357 --> 00:04:27,158 you were considered normal. 50 00:04:27,192 --> 00:04:28,993 If you saw more than seven, 51 00:04:29,027 --> 00:04:32,129 you were an ideal candidate for a warrior or scout. 52 00:04:32,164 --> 00:04:35,299 Among the Ancient Celts and Druids of the British Isles, 53 00:04:35,334 --> 00:04:38,669 the Pleiades were believed to have a haunting significance. 54 00:04:38,704 --> 00:04:40,571 On the night of the year that they reach 55 00:04:40,606 --> 00:04:42,740 the highest point in the sky at midnight, 56 00:04:42,774 --> 00:04:46,410 the spirits of the dead were thought to wander the Earth. 57 00:04:46,445 --> 00:04:49,313 This is believed to be the origin of the holiday 58 00:04:49,348 --> 00:04:51,415 once known as Samhain, 59 00:04:51,450 --> 00:04:52,950 now called Halloween. 60 00:04:52,985 --> 00:04:55,286 All over the Earth, our ancestors told 61 00:04:55,320 --> 00:04:57,355 wonderful stories to explain 62 00:04:57,389 --> 00:05:00,758 how the Pleiades came to be in the sky. 63 00:05:00,792 --> 00:05:03,127 For the Kiowa people of North America, 64 00:05:03,161 --> 00:05:05,296 it happened something like this. 65 00:05:13,005 --> 00:05:15,773 Long, long ago, some young women 66 00:05:15,807 --> 00:05:17,875 snuck away from their campsite 67 00:05:17,910 --> 00:05:20,344 to dance freely beneath the stars. 68 00:05:54,046 --> 00:05:55,746 Rock, save us! 69 00:05:55,781 --> 00:05:59,350 Rock, take pity on us! 70 00:05:59,384 --> 00:06:03,421 The rock heard their cries and grew taller. 71 00:06:09,261 --> 00:06:13,598 Until it became what is today known as the Devil's Tower. 72 00:06:18,070 --> 00:06:22,340 The maidens were transformed into the stars of the Pleiades, 73 00:06:22,374 --> 00:06:25,977 which may be seen hanging above the tower in midwinter. 74 00:06:27,880 --> 00:06:30,181 The Ancient Greeks also saw those seven jewels 75 00:06:30,215 --> 00:06:32,283 as seven maidens, 76 00:06:32,317 --> 00:06:35,887 the seven daughters of Atlas, 77 00:06:35,921 --> 00:06:38,623 pursued not by bears, but by... 78 00:06:38,657 --> 00:06:40,625 Orion the hunter, 79 00:06:40,659 --> 00:06:43,594 who spied them when he was out walking one day. 80 00:06:52,638 --> 00:06:56,240 Orion became mad with desire. 81 00:07:03,248 --> 00:07:06,984 For seven years, he chased them relentlessly. 82 00:07:08,587 --> 00:07:10,922 - Exhausted... - Zeus, help us. 83 00:07:10,956 --> 00:07:13,424 ...they prayed to Zeus for deliverance. 84 00:07:15,594 --> 00:07:20,064 Zeus, the king of the gods, felt sorry for them, 85 00:07:20,098 --> 00:07:22,300 and transformed those seven maidens 86 00:07:22,334 --> 00:07:25,603 into the Pleiades. 87 00:07:33,145 --> 00:07:36,481 But the gods are, if anything, capricious. 88 00:07:36,515 --> 00:07:40,084 When Orion was killed by the sting of a scorpion, 89 00:07:40,119 --> 00:07:43,454 Zeus placed him in the sky where he could resume his pursuit 90 00:07:43,489 --> 00:07:45,423 of the seven gorgeous sisters. 91 00:07:45,457 --> 00:07:47,592 Our ancestors, they wove 92 00:07:47,626 --> 00:07:49,160 brilliantly imaginative stories. 93 00:07:49,194 --> 00:07:51,629 But they can bring us no closer to the stars 94 00:07:51,663 --> 00:07:52,997 than our dreams. 95 00:07:53,031 --> 00:07:55,800 It took yet another few thousand years 96 00:07:55,834 --> 00:07:58,102 until three brilliant scientists unlocked the secrets 97 00:07:58,137 --> 00:08:01,072 of the true lives of the stars. 98 00:08:13,979 --> 00:08:15,613 In 1901, 99 00:08:15,647 --> 00:08:18,583 Harvard was a man's world. 100 00:08:18,617 --> 00:08:21,352 But an astronomer named Edward Charles Pickering 101 00:08:21,386 --> 00:08:23,054 broke that rule. 102 00:08:25,958 --> 00:08:28,893 Oh, Pickering's office is just down the hallway. 103 00:08:28,927 --> 00:08:31,095 And that door over there leads to the room 104 00:08:31,129 --> 00:08:34,599 where he keeps his computers. 105 00:08:45,344 --> 00:08:49,046 We're supposed to call those women "computers," but, uh, 106 00:08:49,081 --> 00:08:51,649 I've heard more than one fellow refer to those gals 107 00:08:51,683 --> 00:08:54,585 as "Pickering's Harem." 108 00:08:54,620 --> 00:08:56,954 Pickering assembled a team of women 109 00:08:56,989 --> 00:08:59,957 to map and classify the types of stars. 110 00:08:59,992 --> 00:09:03,427 One of them provided the key to our understanding 111 00:09:03,462 --> 00:09:05,129 of the substance of the stars. 112 00:09:05,163 --> 00:09:07,965 And another devised a way for us to calculate 113 00:09:08,000 --> 00:09:10,935 the size of the universe. 114 00:09:10,969 --> 00:09:14,605 For some reason, you probably never heard of either of them. 115 00:09:14,640 --> 00:09:17,108 Wonder why. 116 00:09:18,777 --> 00:09:22,446 That's Annie Jump Cannon, the leader of the team. 117 00:09:22,481 --> 00:09:24,348 Before she was through, 118 00:09:24,383 --> 00:09:26,784 she catalogued a quarter of a million stars. 119 00:09:28,487 --> 00:09:31,956 Number 11 is a B7. 120 00:09:31,990 --> 00:09:34,926 That's Alcyone in the Pleiades. 121 00:09:34,960 --> 00:09:37,461 Cannon lost her hearing during a bout of scarlet fever 122 00:09:37,496 --> 00:09:38,696 when she was a young woman. 123 00:09:38,730 --> 00:09:42,133 Number 12 is a B6. 124 00:09:42,167 --> 00:09:45,002 That's Henrietta Swan Leavitt. She's also deaf. 125 00:09:45,037 --> 00:09:48,973 And she's the other great scientist in the room. 126 00:09:49,007 --> 00:09:52,176 Leavitt discovered the law that astronomers still use 127 00:09:52,211 --> 00:09:53,945 more than a century later 128 00:09:53,979 --> 00:09:55,813 to measure the distances to the stars 129 00:09:55,848 --> 00:09:58,416 and the size of the cosmos itself. 130 00:10:00,385 --> 00:10:03,287 Annie Jump Cannon sent out a Christmas card explaining 131 00:10:03,322 --> 00:10:06,357 what she and her sisters were actually doing. 132 00:10:06,391 --> 00:10:08,326 The light from a star is allowed 133 00:10:08,360 --> 00:10:11,829 to fall through a prism placed in the telescope, she wrote. 134 00:10:11,864 --> 00:10:15,533 Thus magnified, the starlight is split up into a band 135 00:10:15,567 --> 00:10:17,969 showing its component colors, 136 00:10:18,003 --> 00:10:22,306 the red rays going to one end and the violet to the other. 137 00:10:22,341 --> 00:10:24,675 This is the spectrum of the star. 138 00:10:24,710 --> 00:10:27,578 It shows the presence of fine, dark lines. 139 00:10:27,613 --> 00:10:29,747 By comparing them with lines given 140 00:10:29,781 --> 00:10:32,049 by glowing substances in the laboratory, 141 00:10:32,084 --> 00:10:35,686 we can determine that the same elements familiar to us 142 00:10:35,721 --> 00:10:39,023 on the Earth also exist in the outermost star. 143 00:10:50,035 --> 00:10:53,771 This is plate number 12358B. 144 00:10:59,077 --> 00:11:03,881 Number one at this plate is a B-type star. 145 00:11:05,818 --> 00:11:09,587 Make that a B2. 146 00:11:11,590 --> 00:11:13,291 It took Cannon decades 147 00:11:13,325 --> 00:11:15,193 to classify the spectral character 148 00:11:15,227 --> 00:11:17,628 of hundreds of thousands of stars 149 00:11:17,663 --> 00:11:20,198 according to the scheme that she devised. 150 00:11:20,232 --> 00:11:22,633 Cannon discovered that the stars fell 151 00:11:22,668 --> 00:11:26,737 into a continuous sequence of seven broad categories 152 00:11:26,772 --> 00:11:29,073 according to their spectral line patterns. 153 00:11:29,108 --> 00:11:31,442 Each was designated by a letter. 154 00:11:31,477 --> 00:11:35,379 But the spectral lines of two stars in the same letter class 155 00:11:35,414 --> 00:11:37,548 could differ in subtle ways, 156 00:11:37,583 --> 00:11:39,750 minute variations that Cannon learned 157 00:11:39,785 --> 00:11:41,452 to recognize from memory. 158 00:11:41,487 --> 00:11:44,122 To distinguish these spectra from one another, 159 00:11:44,156 --> 00:11:48,793 she assigned ten numerical subcategories for each class. 160 00:11:48,827 --> 00:11:51,629 Annie Jump Cannon organized the stars, 161 00:11:51,663 --> 00:11:53,965 but it would fall to another scientist to decipher 162 00:11:53,999 --> 00:11:56,267 the hidden meaning in her work. 163 00:11:58,303 --> 00:12:01,739 In the England of 1923, women were forbidden 164 00:12:01,774 --> 00:12:04,108 from pursuing advanced degrees in science. 165 00:12:04,143 --> 00:12:07,011 But Cecelia Payne had attended a lecture in London 166 00:12:07,045 --> 00:12:09,280 by the astronomer Sir Arthur Eddington, 167 00:12:09,314 --> 00:12:11,916 the first scientist to provide evidence 168 00:12:11,950 --> 00:12:13,584 that Einstein's revolutionary 169 00:12:13,619 --> 00:12:15,787 General Theory of Relativity was correct. 170 00:12:15,821 --> 00:12:17,321 From that moment on, 171 00:12:17,356 --> 00:12:19,023 she knew that nothing would deter her 172 00:12:19,057 --> 00:12:21,526 from pursing her big dreams. 173 00:12:23,028 --> 00:12:25,363 She resolved to emigrate to America, 174 00:12:25,397 --> 00:12:27,698 where women had already gained the freedom 175 00:12:27,733 --> 00:12:29,834 to study the stars. 176 00:12:29,868 --> 00:12:32,870 Her application was accepted at Harvard. 177 00:12:32,905 --> 00:12:35,306 What she would discover there would challenge 178 00:12:35,340 --> 00:12:37,508 one of the central beliefs of astronomy. 179 00:12:37,543 --> 00:12:40,144 The resulting impact 180 00:12:40,179 --> 00:12:43,514 would be the dawn of modern astrophysics. 181 00:12:52,525 --> 00:12:54,326 As the decades passed, 182 00:12:54,361 --> 00:12:57,563 Annie Jump Cannon and her team kept sifting the stars, 183 00:12:57,597 --> 00:12:59,398 checking each one's spectral signature 184 00:12:59,432 --> 00:13:02,234 with a fleeting glance and then dropping them 185 00:13:02,269 --> 00:13:04,069 into one of seven categories. 186 00:13:04,104 --> 00:13:06,905 They became hundreds of thousands of dots 187 00:13:06,940 --> 00:13:10,242 in a larger picture which no one could yet understand. 188 00:13:10,277 --> 00:13:15,147 Into this community of women came one more. 189 00:13:16,549 --> 00:13:18,250 Well, hello there. 190 00:13:18,285 --> 00:13:21,420 You must be Miss Payne. 191 00:13:21,454 --> 00:13:22,721 We've been waiting for you. 192 00:13:22,756 --> 00:13:24,924 Come on in. 193 00:13:24,958 --> 00:13:27,626 Cecilia Payne had never experienced such kindness 194 00:13:27,661 --> 00:13:30,195 in a scientific setting before. 195 00:13:30,230 --> 00:13:32,865 This sisterhood generously shared 196 00:13:32,899 --> 00:13:34,967 the fruits of their labors with her, 197 00:13:35,001 --> 00:13:36,802 and she turned their observations 198 00:13:36,836 --> 00:13:40,372 into a radical new understanding of the stars. 199 00:13:40,407 --> 00:13:43,509 The two women became great friends. 200 00:13:43,543 --> 00:13:45,244 Cannon taught Payne everything she had learned 201 00:13:45,278 --> 00:13:46,779 about stellar spectra. 202 00:13:46,813 --> 00:13:48,581 And Payne began to analyze Cannon's data 203 00:13:48,615 --> 00:13:52,318 to see if she could determine the actual chemical composition 204 00:13:52,352 --> 00:13:54,553 and physical state of the stars. 205 00:13:54,588 --> 00:13:56,889 She brought to this work her expertise 206 00:13:56,923 --> 00:13:58,757 in theoretical and atomic physics. 207 00:14:01,595 --> 00:14:04,430 The most prominent features in the spectra of stars 208 00:14:04,464 --> 00:14:06,165 showed the presence of heavy elements 209 00:14:06,199 --> 00:14:10,135 such as calcium... and iron, 210 00:14:10,170 --> 00:14:13,105 which are among the most abundant elements in the Earth. 211 00:14:13,139 --> 00:14:15,107 So astronomers naturally concluded 212 00:14:15,141 --> 00:14:16,976 that the stars were made 213 00:14:17,010 --> 00:14:18,944 of the same elements as the Earth 214 00:14:18,979 --> 00:14:21,113 and in roughly the same proportions. 215 00:14:21,147 --> 00:14:26,018 In 1924, Henry Norris Russell was the dean 216 00:14:26,052 --> 00:14:29,321 of American astronomers, having made major contributions 217 00:14:29,356 --> 00:14:31,690 to our understanding of the stars. 218 00:14:31,725 --> 00:14:34,460 40 to 45 of the chemical elements 219 00:14:34,494 --> 00:14:36,328 that we have here on Earth 220 00:14:36,363 --> 00:14:39,131 are also present in the spectrum of the Sun. 221 00:14:39,165 --> 00:14:42,668 So we can assume that the composition of the Sun 222 00:14:42,702 --> 00:14:45,538 resembles that of the Earth. 223 00:14:45,572 --> 00:14:49,041 If one were to heat the crust of the Earth to incandescence, 224 00:14:49,075 --> 00:14:52,645 its spectrum would resemble that of the Sun. 225 00:15:07,227 --> 00:15:11,163 Annie, I think I now understand what it all means. 226 00:15:11,198 --> 00:15:13,065 All your years of work. 227 00:15:13,099 --> 00:15:14,333 Tell me. 228 00:15:14,367 --> 00:15:15,968 I've calculated what the spectra 229 00:15:16,002 --> 00:15:18,037 should look like across a wide range 230 00:15:18,071 --> 00:15:19,705 of temperatures, and they match 231 00:15:19,739 --> 00:15:22,541 your system of classification perfectly. 232 00:15:22,576 --> 00:15:26,745 The spectrum of any star tells you exactly how hot it is. 233 00:15:26,780 --> 00:15:32,751 Your "O-B-A-F-G-K-M" is really a temperature scale of the stars 234 00:15:32,786 --> 00:15:35,287 from the hottest to the coldest. 235 00:15:37,457 --> 00:15:40,259 Here's the headline, Annie. Thanks to your work, 236 00:15:40,293 --> 00:15:42,328 I've discovered that the stars are made almost entirely 237 00:15:42,362 --> 00:15:43,996 of hydrogen and helium. 238 00:15:44,030 --> 00:15:47,099 There's a million times more hydrogen and helium 239 00:15:47,133 --> 00:15:49,268 than the metals in the stars. 240 00:15:49,302 --> 00:15:51,937 I know, it sounds daft. 241 00:15:51,972 --> 00:15:54,006 Are you certain? 242 00:15:54,040 --> 00:15:58,744 Has anyone else checked your calculations? 243 00:15:58,778 --> 00:16:01,347 Not yet, but it's all in my thesis, 244 00:16:01,381 --> 00:16:03,816 which is already on its way to Professor Russell. 245 00:16:15,428 --> 00:16:17,463 Poor woman. 246 00:16:17,497 --> 00:16:20,733 Russell felt sorry for Cecilia Payne. 247 00:16:20,767 --> 00:16:24,270 Her thesis appeared to him to be fundamentally flawed. 248 00:16:31,845 --> 00:16:35,281 It is clearly impossible that hydrogen should be 249 00:16:35,315 --> 00:16:37,983 a million times more abundant than the metals. 250 00:16:42,189 --> 00:16:45,958 Her carefully gathered evidence flew in the face 251 00:16:45,992 --> 00:16:48,627 of conventional scientific wisdom. 252 00:16:48,662 --> 00:16:50,596 "How could I be right," she asked, 253 00:16:50,630 --> 00:16:52,832 "if that must mean 254 00:16:52,866 --> 00:16:55,835 that such a distinguished scientist was wrong?" 255 00:16:57,537 --> 00:17:00,573 Despite her confidence in the quality of her research, 256 00:17:00,607 --> 00:17:03,676 she caved and added a sentence to her thesis 257 00:17:03,710 --> 00:17:06,679 that undermined its greatest insight. 258 00:17:12,219 --> 00:17:13,652 It would be four years 259 00:17:13,687 --> 00:17:16,422 before Russell realized that Payne was right. 260 00:17:16,456 --> 00:17:19,592 To his credit, as soon as he did, 261 00:17:19,626 --> 00:17:21,961 he acknowledged that it was her discovery. 262 00:17:25,398 --> 00:17:29,201 Payne's "Stellar Atmospheres" is widely regarded 263 00:17:29,236 --> 00:17:31,337 as the most brilliant PhD thesis 264 00:17:31,371 --> 00:17:33,172 ever written in astronomy. 265 00:17:33,206 --> 00:17:37,543 It became the standard text in its field. 266 00:17:37,577 --> 00:17:41,280 I was to blame for not having pressed my point. 267 00:17:41,314 --> 00:17:46,152 I had given in to authority when I believed I was right. 268 00:17:46,186 --> 00:17:48,220 If you are sure of your facts, 269 00:17:48,255 --> 00:17:50,689 you should defend your position. 270 00:17:52,092 --> 00:17:54,160 The words of the powerful 271 00:17:54,194 --> 00:17:56,996 may prevail in other spheres of human experience, 272 00:17:57,030 --> 00:18:01,000 but in science, the only thing that counts is the evidence 273 00:18:01,034 --> 00:18:03,502 and the logic of the argument itself. 274 00:18:03,537 --> 00:18:06,906 Cecilia Payne's interpretation of Annie Jump Cannon's sequence 275 00:18:06,940 --> 00:18:09,675 of stellar spectra made it possible for us 276 00:18:09,709 --> 00:18:11,911 to read the life stories of the stars 277 00:18:11,945 --> 00:18:15,915 and to trace the story of life itself back to its beginnings 278 00:18:15,949 --> 00:18:18,951 in their fiery deaths. 279 00:18:28,474 --> 00:18:31,242 There are many kinds of stars. 280 00:18:31,277 --> 00:18:33,811 Some are bright like the Sun. 281 00:18:33,846 --> 00:18:35,947 Some are dim. 282 00:18:35,981 --> 00:18:38,082 The greatest stars are ten million times larger 283 00:18:38,117 --> 00:18:40,318 than the smallest ones. 284 00:18:40,352 --> 00:18:42,921 Some stars are old beyond imagining, 285 00:18:42,955 --> 00:18:46,124 more than ten billion years of age. 286 00:18:46,158 --> 00:18:48,493 Others are being born right now. 287 00:18:52,231 --> 00:18:55,200 When atoms fuse in the hearts of stars, 288 00:18:55,234 --> 00:18:56,501 they make starlight. 289 00:18:56,535 --> 00:18:58,436 Stars are born in litters, 290 00:18:58,470 --> 00:19:02,106 formed from the gas and dust of interstellar clouds. 291 00:19:02,141 --> 00:19:05,043 The mass of the individual stars in a litter 292 00:19:05,077 --> 00:19:07,378 can range from the runts-- not much larger 293 00:19:07,413 --> 00:19:09,447 than the largest planets-- 294 00:19:09,481 --> 00:19:12,250 to the supergiant stars that dwarf the Sun. 295 00:19:18,424 --> 00:19:22,327 The stars in the nebula below Orion's Belt are newborns, 296 00:19:22,361 --> 00:19:24,062 around five million years old, 297 00:19:24,096 --> 00:19:27,298 and still swaddled in the gas and dust 298 00:19:27,333 --> 00:19:29,500 that gave birth to them. 299 00:19:29,535 --> 00:19:32,670 The stars in the Pleiades are already toddlers, 300 00:19:32,705 --> 00:19:34,572 about 100 million years old. 301 00:19:34,607 --> 00:19:36,708 They've shed their blankets of gas and dust, 302 00:19:36,742 --> 00:19:38,643 but they're still bound together 303 00:19:38,677 --> 00:19:40,578 by their mutual gravity. 304 00:19:40,613 --> 00:19:42,514 Another few hundred million years, 305 00:19:42,548 --> 00:19:45,150 and they'll drift apart and go their separate ways, 306 00:19:45,184 --> 00:19:47,685 never to meet again. 307 00:19:47,720 --> 00:19:51,322 Most of the stars of the Big Dipper are adolescents, 308 00:19:51,357 --> 00:19:53,892 roughly half a billion years old. 309 00:19:53,926 --> 00:19:56,494 They've already drifted apart from their birth cluster, 310 00:19:56,529 --> 00:19:59,564 although we can still trace their common ancestry. 311 00:19:59,598 --> 00:20:03,001 Eventually, they'll spread out around the Milky Way galaxy. 312 00:20:03,035 --> 00:20:05,870 But most of the familiar constellations 313 00:20:05,905 --> 00:20:09,240 are a mix of entirely unrelated stars, 314 00:20:09,275 --> 00:20:11,042 some faint and nearby, 315 00:20:11,076 --> 00:20:14,212 others bright and far away. 316 00:20:16,749 --> 00:20:18,283 Our own Sun? 317 00:20:18,317 --> 00:20:20,285 From the distance of even a few light-years, 318 00:20:20,319 --> 00:20:23,721 it's hard to find amidst the other stars. 319 00:20:23,756 --> 00:20:25,757 It's that one. 320 00:20:27,393 --> 00:20:28,893 Our Sun is middle-aged 321 00:20:28,928 --> 00:20:30,862 and a long way from where it was born. 322 00:20:30,896 --> 00:20:32,564 Its sister stars, 323 00:20:32,598 --> 00:20:34,365 hatched from the same interstellar cloud, 324 00:20:34,400 --> 00:20:37,235 are dispersed throughout the galaxy. 325 00:20:37,269 --> 00:20:39,904 Many of them have their own planets. 326 00:20:39,939 --> 00:20:41,806 Perhaps some of them nurture 327 00:20:41,841 --> 00:20:44,909 the evolution of life and intelligence. 328 00:20:44,944 --> 00:20:47,045 Most of the stars in our night sky 329 00:20:47,079 --> 00:20:50,715 actually orbit around one or more stellar companions. 330 00:20:50,749 --> 00:20:52,250 With the naked eye, 331 00:20:52,284 --> 00:20:53,818 we usually can't see the fainter members 332 00:20:53,853 --> 00:20:56,087 in such double and multiple star systems. 333 00:20:58,824 --> 00:21:00,725 On a world with three suns, 334 00:21:00,759 --> 00:21:02,660 the nights would be rare 335 00:21:02,695 --> 00:21:06,331 and the days might alternate between red and blue. 336 00:21:12,838 --> 00:21:15,573 It is the destiny of stars to collapse. 337 00:21:15,608 --> 00:21:17,575 Of the thousands of stars you see 338 00:21:17,610 --> 00:21:19,744 when you look up at the night sky, 339 00:21:19,779 --> 00:21:21,079 every one of them is living 340 00:21:21,113 --> 00:21:23,248 in an interval between two collapses... 341 00:21:23,282 --> 00:21:26,117 an initial collapse of a dark, interstellar gas cloud 342 00:21:26,152 --> 00:21:27,752 to form the star, 343 00:21:27,787 --> 00:21:30,321 and a final collapse of the luminous star 344 00:21:30,356 --> 00:21:33,091 on its way to its ultimate fate. 345 00:21:33,125 --> 00:21:34,793 Gravity makes stars contract, 346 00:21:34,827 --> 00:21:37,028 unless some other force intervenes. 347 00:21:37,062 --> 00:21:40,365 The Sun is a great, big ball of incandescent gas. 348 00:21:40,399 --> 00:21:43,334 The super hot gas in its core 349 00:21:43,369 --> 00:21:45,370 pushes the Sun to expand outward. 350 00:21:45,404 --> 00:21:48,206 At the same time, the Sun's own gravity 351 00:21:48,240 --> 00:21:50,275 pulls it inward to contract. 352 00:21:50,309 --> 00:21:53,011 And our Sun is poised between these two forces 353 00:21:53,045 --> 00:21:54,879 in a stable equilibrium 354 00:21:54,914 --> 00:21:58,049 between gravity and nuclear fire, 355 00:21:58,084 --> 00:21:59,551 a balance it will maintain 356 00:21:59,585 --> 00:22:01,886 for another four billion years. 357 00:22:01,921 --> 00:22:04,222 But as the Sun consumes hydrogen, 358 00:22:04,256 --> 00:22:07,192 its core very slowly shrinks, 359 00:22:07,226 --> 00:22:10,695 and the Sun's surface gradually expands in response. 360 00:22:10,729 --> 00:22:12,163 It happens very slowly, 361 00:22:12,198 --> 00:22:13,665 imperceptibly, 362 00:22:13,699 --> 00:22:15,400 over the course of millions of years. 363 00:22:15,434 --> 00:22:17,502 But in about a billion years, 364 00:22:17,536 --> 00:22:19,471 the Sun will be ten percent brighter 365 00:22:19,505 --> 00:22:21,673 than it is today. 366 00:22:24,343 --> 00:22:26,311 Ten percent may not sound like much, 367 00:22:26,345 --> 00:22:30,348 but that extra heat will have a big effect on Earth. 368 00:22:37,456 --> 00:22:40,091 When the Sun finally exhausts its nuclear fuel 369 00:22:40,126 --> 00:22:42,761 four or five billion years from now, 370 00:22:42,795 --> 00:22:46,398 its gas will cool and the pressure will fall. 371 00:22:46,432 --> 00:22:47,832 The Sun's interior 372 00:22:47,867 --> 00:22:49,367 can no longer support the weight 373 00:22:49,402 --> 00:22:51,035 of the outer layers, 374 00:22:51,070 --> 00:22:54,406 and the initial collapse will resume. 375 00:22:54,440 --> 00:22:56,274 Nothing lasts forever. 376 00:22:56,308 --> 00:22:58,777 Even the stars die. 377 00:22:58,811 --> 00:23:01,079 Helium, the ash 378 00:23:01,113 --> 00:23:03,047 of ten billion years of hydrogen fusion, 379 00:23:03,082 --> 00:23:05,283 has built up in the core. 380 00:23:05,317 --> 00:23:07,852 With no nuclear fire to sustain its weight, 381 00:23:07,887 --> 00:23:10,355 the core collapses until it becomes hot enough 382 00:23:10,389 --> 00:23:13,725 to start fusing helium into carbon and oxygen. 383 00:23:13,759 --> 00:23:15,360 The core of the Sun 384 00:23:15,394 --> 00:23:17,595 is now much hotter than it was before. 385 00:23:17,630 --> 00:23:20,365 Its atmosphere rapidly expands. 386 00:23:20,399 --> 00:23:23,468 Over the next billion years, it'll become bloated 387 00:23:23,502 --> 00:23:25,970 to more than 100 times its original size-- 388 00:23:26,005 --> 00:23:29,107 a red giant star. 389 00:23:32,111 --> 00:23:34,312 It will envelop and devour 390 00:23:34,346 --> 00:23:36,915 the planets Mercury... 391 00:23:39,452 --> 00:23:41,820 ...and Venus... 392 00:23:46,192 --> 00:23:48,293 ...and possibly the Earth. 393 00:23:50,296 --> 00:23:52,130 I like to think that 394 00:23:52,164 --> 00:23:54,666 tens of millions of years before that far distant future, 395 00:23:54,700 --> 00:23:57,902 if there still be life born of Earth, 396 00:23:57,937 --> 00:24:01,539 it will have found new homes among the stars. 397 00:24:03,509 --> 00:24:05,577 Once the Sun burns through its helium, 398 00:24:05,611 --> 00:24:07,779 it will become highly unstable, 399 00:24:07,813 --> 00:24:10,715 casting off its outer layers into space. 400 00:24:13,119 --> 00:24:14,853 The exposed, super hot core 401 00:24:14,887 --> 00:24:16,588 will flood its surroundings 402 00:24:16,622 --> 00:24:18,990 with high-energy ultraviolet light. 403 00:24:21,227 --> 00:24:25,063 The atoms will perform a wild, fluorescent dance. 404 00:24:31,237 --> 00:24:34,139 The Sun will collapse like a souffl�, 405 00:24:34,173 --> 00:24:37,308 shrinking a hundredfold to the size of the Earth. 406 00:24:37,343 --> 00:24:39,978 And at that point, the Sun will be so dense 407 00:24:40,012 --> 00:24:42,547 that its overcrowded electrons will push back, 408 00:24:42,581 --> 00:24:44,849 stopping any further contraction. 409 00:24:44,884 --> 00:24:46,618 The kernel of light at the center 410 00:24:46,652 --> 00:24:50,055 will be the only part of the Sun that endures, 411 00:24:50,089 --> 00:24:53,525 a white dwarf star that will go on shining dimly 412 00:24:53,559 --> 00:24:56,227 for another 100 billion years. 413 00:24:56,262 --> 00:24:58,563 Will the beings of a distant future, 414 00:24:58,597 --> 00:25:00,999 sailing past this wreck of a star, 415 00:25:01,033 --> 00:25:05,904 have any idea of the life and worlds that it once warmed? 416 00:25:29,258 --> 00:25:31,326 The psychedelic death shrouds 417 00:25:31,360 --> 00:25:34,363 of ordinary stars are fleeting, 418 00:25:34,397 --> 00:25:37,733 lasting only tens of thousands of years 419 00:25:37,767 --> 00:25:41,169 before dissipating in the interstellar gas and dust 420 00:25:41,204 --> 00:25:43,238 from which the new stars will be born. 421 00:25:47,744 --> 00:25:50,145 The stars in a binary star system 422 00:25:50,179 --> 00:25:52,247 can have a different fate. 423 00:25:52,281 --> 00:25:55,417 Sirius, the brightest star in the night sky, 424 00:25:55,451 --> 00:25:58,520 has a very faint stellar companion-- 425 00:25:58,554 --> 00:25:59,921 a white dwarf. 426 00:25:59,956 --> 00:26:01,857 It was once a Sun-like star. 427 00:26:01,891 --> 00:26:04,659 Someday, when Sirius runs out of fuel 428 00:26:04,694 --> 00:26:06,495 and becomes a red giant, 429 00:26:06,529 --> 00:26:09,331 it will shed its substance onto the white dwarf. 430 00:26:09,365 --> 00:26:12,434 The intense gravity of the companion 431 00:26:12,468 --> 00:26:14,069 will attract that gas, 432 00:26:14,103 --> 00:26:16,505 pulling it into a spiraling disk. 433 00:26:16,539 --> 00:26:18,674 When the gas from the larger star 434 00:26:18,708 --> 00:26:20,676 falls onto the surface of the white dwarf, 435 00:26:20,710 --> 00:26:23,612 it will trigger nuclear explosions. 436 00:26:27,417 --> 00:26:29,284 The greatest burst will release 437 00:26:29,318 --> 00:26:32,054 100,000 times more energy than the Sun. 438 00:26:33,823 --> 00:26:36,892 Each one of those star bursts is called a "nova," 439 00:26:36,926 --> 00:26:40,128 from the Latin for "new." 440 00:26:40,163 --> 00:26:43,065 A star about 15 times as massive as the Sun, 441 00:26:43,099 --> 00:26:46,034 one like Rigel, the blue supergiant 442 00:26:46,069 --> 00:26:48,136 that forms the right foot of Orion, 443 00:26:48,171 --> 00:26:49,971 has a different fate in store. 444 00:26:50,006 --> 00:26:53,608 Its collapse will not be stopped by the pressure of electrons. 445 00:26:55,745 --> 00:26:58,947 The star will keep falling in on itself, 446 00:26:58,982 --> 00:27:01,984 until its nuclei become so overcrowded 447 00:27:02,018 --> 00:27:04,453 that they push back. 448 00:27:06,756 --> 00:27:09,791 Rigel will shrink down about 100,000 times, 449 00:27:09,826 --> 00:27:13,128 until there's no space left between the nuclei 450 00:27:13,162 --> 00:27:15,364 and it can shrink no more. 451 00:27:20,136 --> 00:27:21,570 At that point, it ignites 452 00:27:21,604 --> 00:27:25,607 a more powerful nuclear reaction, a supernova. 453 00:27:30,980 --> 00:27:32,514 Most stellar evolution 454 00:27:32,548 --> 00:27:34,616 takes millions or billions of years. 455 00:27:34,651 --> 00:27:36,351 But the interior collapse 456 00:27:36,386 --> 00:27:39,254 that triggers a supernova explosion takes only seconds. 457 00:27:39,288 --> 00:27:42,758 What remains will be an atomic nucleus 458 00:27:42,792 --> 00:27:45,460 the size of a small city-- 459 00:27:45,495 --> 00:27:49,331 a rapidly rotating neutron star called a pulsar. 460 00:28:02,011 --> 00:28:03,478 But for a star more than 461 00:28:03,513 --> 00:28:05,480 30 times as massive as the Sun-- 462 00:28:05,515 --> 00:28:08,483 a star like Alnilam, in Orion's Belt-- 463 00:28:08,518 --> 00:28:11,453 there will be no stopping its collapse. 464 00:28:11,487 --> 00:28:13,188 In a few million years, 465 00:28:13,222 --> 00:28:14,990 when Alnilam runs out of fuel, 466 00:28:15,024 --> 00:28:17,025 it, too, will go supernova. 467 00:28:17,060 --> 00:28:20,395 The imploding core of Alnilam 468 00:28:20,430 --> 00:28:23,899 will be so massive that not even nuclear forces 469 00:28:23,933 --> 00:28:26,902 will be strong enough to hold off its collapse. 470 00:28:26,936 --> 00:28:29,805 Nothing can withstand such gravity. 471 00:28:29,839 --> 00:28:32,107 And such a star has an astonishing destiny. 472 00:28:36,913 --> 00:28:38,880 It will continues to collapse, 473 00:28:38,915 --> 00:28:41,483 crossing a boundary in space-time 474 00:28:41,517 --> 00:28:43,685 called the "event horizon," 475 00:28:43,720 --> 00:28:45,754 beyond which we cannot see. 476 00:28:45,788 --> 00:28:47,856 When it traverses that frontier, 477 00:28:47,890 --> 00:28:51,126 the star will vanish completely from sight. 478 00:28:53,029 --> 00:28:55,664 It will be inside a black hole, 479 00:28:55,698 --> 00:28:58,400 a place where gravity is so strong 480 00:28:58,434 --> 00:29:01,870 that nothing, not even light, can escape. 481 00:29:06,542 --> 00:29:07,743 But there's an even 482 00:29:07,777 --> 00:29:09,011 more dramatic fate 483 00:29:09,045 --> 00:29:11,079 that awaits a rare kind of star. 484 00:29:11,114 --> 00:29:13,248 There's one of them in our galaxy. 485 00:29:13,283 --> 00:29:15,784 It's so unstable that when it goes, 486 00:29:15,818 --> 00:29:19,254 it won't become a mere nova or supernova. 487 00:29:19,289 --> 00:29:21,790 It'll become something far more catastrophic... 488 00:29:21,824 --> 00:29:24,092 a hypernova. 489 00:29:24,127 --> 00:29:26,929 And it could happen in our lifetime. 490 00:29:37,907 --> 00:29:40,742 There are few places on Earth to get a better view 491 00:29:40,777 --> 00:29:43,812 of the night sky than the Australian Outback. 492 00:29:45,615 --> 00:29:47,950 No buildings, 493 00:29:47,984 --> 00:29:50,886 no cars, streetlights, nothing out here; 494 00:29:50,920 --> 00:29:52,754 just lots of starlight... 495 00:29:52,789 --> 00:29:55,123 and the occasional kangaroo. 496 00:29:55,158 --> 00:29:56,725 You can get a particularly good view 497 00:29:56,759 --> 00:29:58,627 of the Milky Way from down here. 498 00:29:58,661 --> 00:30:00,329 The center of our galaxy 499 00:30:00,363 --> 00:30:01,964 rises high in the sky, 500 00:30:01,998 --> 00:30:03,999 and it arches across the heavens 501 00:30:04,033 --> 00:30:06,668 like the backbone of night. 502 00:30:06,703 --> 00:30:08,437 We live in a spiral galaxy. 503 00:30:08,471 --> 00:30:10,439 And when we look at the Milky Way, 504 00:30:10,473 --> 00:30:14,409 we're seeing light from billions of stars in its spiral disk. 505 00:30:14,444 --> 00:30:16,845 And under this beautiful dark sky, 506 00:30:16,879 --> 00:30:20,482 you can see that the Milky Way isn't a uniform band of light. 507 00:30:20,516 --> 00:30:23,619 There are dark patches, breaks in the starlight. 508 00:30:23,653 --> 00:30:27,522 Those dark patches are caused by interstellar dust. 509 00:30:27,557 --> 00:30:31,159 The dust blocks the starlight, and there's lots of it. 510 00:30:32,895 --> 00:30:35,364 Most cultures looked up at the stars 511 00:30:35,398 --> 00:30:36,698 and connected the dots 512 00:30:36,733 --> 00:30:38,867 to form familiar images in the sky. 513 00:30:38,902 --> 00:30:41,003 Constellations. 514 00:30:46,175 --> 00:30:48,510 But the Aboriginal people of Australia 515 00:30:48,545 --> 00:30:50,679 saw a pattern in the darkness 516 00:30:50,713 --> 00:30:52,781 running through the Milky Way. 517 00:30:52,815 --> 00:30:55,517 They saw an emu, a large bird 518 00:30:55,552 --> 00:30:57,819 native to this continent. 519 00:30:57,854 --> 00:31:01,757 Not in the stars, but in the absence of stars. 520 00:31:04,928 --> 00:31:07,663 There are so many ways to look at the night sky. 521 00:31:07,697 --> 00:31:10,699 For a million years or more, we've watched the sky. 522 00:31:10,733 --> 00:31:12,401 And a lot's happened in that time. 523 00:31:12,435 --> 00:31:16,305 Supernova explode in our galaxy about once a century. 524 00:31:16,339 --> 00:31:19,374 If we could compress all those nights of stargazing 525 00:31:19,409 --> 00:31:21,176 into a single minute, 526 00:31:21,211 --> 00:31:23,779 this is what we would see. 527 00:31:28,785 --> 00:31:30,919 Now, if our eyes were telescopes, 528 00:31:30,954 --> 00:31:33,655 if they were light buckets as big as wagon wheels 529 00:31:33,690 --> 00:31:37,326 and our vision was not limited to just one kind of light, 530 00:31:37,360 --> 00:31:41,763 then this is the Milky Way we would see. 531 00:31:41,798 --> 00:31:44,499 A galaxy in near-infrared light 532 00:31:44,534 --> 00:31:46,668 with streaming tendrils of dust 533 00:31:46,703 --> 00:31:49,371 hurled outward by those exploding supernovas, 534 00:31:49,405 --> 00:31:51,373 silhouetted against a backdrop 535 00:31:51,407 --> 00:31:54,209 of countless stars. 536 00:31:54,244 --> 00:31:57,179 About 7,500 light-years away, 537 00:31:57,213 --> 00:31:59,414 in another part of our galaxy, 538 00:31:59,449 --> 00:32:01,583 there is a place of upheaval 539 00:32:01,618 --> 00:32:04,052 on an inconceivable scale. 540 00:32:12,792 --> 00:32:15,927 This is the Carina Nebula. 541 00:32:15,962 --> 00:32:18,363 A star-making machine. 542 00:32:22,168 --> 00:32:26,138 It takes a ray of light 50 years to cross it. 543 00:32:29,175 --> 00:32:32,511 The titanic stars born here 544 00:32:32,545 --> 00:32:34,780 sear the surrounding gas and dust 545 00:32:34,814 --> 00:32:37,816 with their fierce ultraviolet radiation. 546 00:32:37,850 --> 00:32:40,285 When a massive star dies, 547 00:32:40,319 --> 00:32:43,555 it blows itself to smithereens. 548 00:32:46,225 --> 00:32:48,927 Its substance is propelled across the vastness 549 00:32:48,961 --> 00:32:50,962 to be stirred by starlight 550 00:32:50,997 --> 00:32:53,265 and gathered up by gravity. 551 00:32:53,299 --> 00:32:55,133 Stars to dust 552 00:32:55,168 --> 00:32:57,969 and dust to stars. 553 00:32:58,004 --> 00:33:00,872 In the cosmos, nothing is wasted. 554 00:33:03,009 --> 00:33:06,912 But there's an upper limit to how massive a star can be. 555 00:33:09,248 --> 00:33:11,650 Back in the 17th century, when Edmond Halley 556 00:33:11,684 --> 00:33:14,352 crossed the equator to map the southern constellations, 557 00:33:14,387 --> 00:33:17,622 Eta Carinae seemed like just another faint star. 558 00:33:17,657 --> 00:33:20,459 But in 1843, Eta Carinae 559 00:33:20,493 --> 00:33:23,195 suddenly became the second brightest star in the sky, 560 00:33:23,229 --> 00:33:25,897 outshined only by Sirius. 561 00:33:25,932 --> 00:33:28,533 And it's been flipping out ever since. 562 00:33:31,003 --> 00:33:33,171 That dumbbell-shaped cloud 563 00:33:33,206 --> 00:33:36,408 is the expanding remnant of that event. 564 00:33:40,947 --> 00:33:44,015 At its center is one crazy star. 565 00:33:44,050 --> 00:33:45,917 Talk about unstable-- 566 00:33:45,952 --> 00:33:47,886 Eta Carinae is at least 100 times 567 00:33:47,920 --> 00:33:49,521 more massive than the Sun, 568 00:33:49,555 --> 00:33:52,824 and pouring out five million times more light. 569 00:33:52,859 --> 00:33:58,330 It's pushing the upper limit of what a star can be. 570 00:33:58,364 --> 00:34:01,166 What's more, there's evidence that Eta Carinae 571 00:34:01,200 --> 00:34:04,936 is being gravitationally tormented by an evil twin-- 572 00:34:04,971 --> 00:34:08,006 another massive star in orbit around it 573 00:34:08,040 --> 00:34:11,910 as close as Saturn is to the Sun. 574 00:34:11,944 --> 00:34:15,881 The core of a supermassive star pours out so much light 575 00:34:15,915 --> 00:34:19,418 that the outward pressure can overwhelm the star's gravity. 576 00:34:19,452 --> 00:34:21,887 If a star is too massive, 577 00:34:21,921 --> 00:34:24,556 its radiation pressure overpowers its gravity 578 00:34:24,590 --> 00:34:27,426 and blows the star apart. 579 00:34:29,228 --> 00:34:31,196 The fate of Eta Carinae was sealed 580 00:34:31,230 --> 00:34:33,632 when it was born millions of years ago. 581 00:34:33,666 --> 00:34:35,734 When it finally does blow up-- 582 00:34:35,768 --> 00:34:38,069 and who knows, maybe it already has; 583 00:34:38,104 --> 00:34:40,806 after all, we're looking at it by light that left the star 584 00:34:40,840 --> 00:34:43,308 7,500 years ago-- 585 00:34:43,342 --> 00:34:47,279 it will be a cataclysm unlike anything we've seen before. 586 00:34:47,313 --> 00:34:49,247 A hypernova. 587 00:35:01,194 --> 00:35:04,162 An explosion so powerful, it'll make a supernova 588 00:35:04,197 --> 00:35:07,065 seem like a firecracker by comparison. 589 00:35:07,100 --> 00:35:09,267 If there are nearby solar systems 590 00:35:09,302 --> 00:35:13,605 with planets harboring life, their days are numbered. 591 00:35:13,639 --> 00:35:16,942 A hypernova spews so much radiation into space-- 592 00:35:16,976 --> 00:35:20,245 not just light, but X-rays and gamma rays-- 593 00:35:20,279 --> 00:35:22,280 that planets that are dozens 594 00:35:22,315 --> 00:35:24,649 or perhaps hundreds of light-years away 595 00:35:24,684 --> 00:35:26,618 could be stripped of their atmospheres 596 00:35:26,652 --> 00:35:29,287 and bathed in deadly radiation. 597 00:35:29,322 --> 00:35:30,789 It would wreak havoc 598 00:35:30,823 --> 00:35:33,525 in thousands of nearby star systems. 599 00:35:34,213 --> 00:35:36,848 Right about now, you're probably asking yourself, 600 00:35:36,883 --> 00:35:39,284 "Are we safe?" 601 00:35:39,318 --> 00:35:41,653 If Eta Carinae blows up, 602 00:35:41,687 --> 00:35:44,322 what happens to Earth? 603 00:35:44,357 --> 00:35:47,526 Rest assured, Earth will be just fine. 604 00:35:47,560 --> 00:35:49,928 Remember, we're 7,500 light-years 605 00:35:49,962 --> 00:35:51,630 away from Eta Carinae. 606 00:35:51,664 --> 00:35:53,765 The intensity of radiation from a star, 607 00:35:53,800 --> 00:35:55,634 even an exploding star, 608 00:35:55,668 --> 00:35:57,869 falls off rapidly with distance. 609 00:35:57,904 --> 00:36:01,306 But still, Eta Carinae in its death throes 610 00:36:01,340 --> 00:36:03,308 will put on quite a show. 611 00:36:03,342 --> 00:36:05,811 It will light up the night of the southern hemisphere 612 00:36:05,845 --> 00:36:08,180 with the brightness of a second moon. 613 00:36:08,214 --> 00:36:12,484 The most dramatic swan song a star can sing. 614 00:36:17,824 --> 00:36:20,492 Our ancestors worshipped the Sun. 615 00:36:20,526 --> 00:36:23,562 And they were far from foolish. 616 00:36:23,596 --> 00:36:27,299 It makes good sense to revere the Sun and stars, 617 00:36:27,333 --> 00:36:29,701 because we are their children. 618 00:36:29,736 --> 00:36:33,171 The silicon in the rocks, the oxygen in the air, 619 00:36:33,206 --> 00:36:37,042 the carbon in our DNA, the iron in our skyscrapers, 620 00:36:37,076 --> 00:36:39,344 the silver in our jewelry 621 00:36:39,379 --> 00:36:43,181 were all made in stars billions of years ago. 622 00:36:43,216 --> 00:36:46,885 Our planet, our society and we ourselves 623 00:36:46,919 --> 00:36:49,388 are stardust. 624 00:36:50,957 --> 00:36:54,092 Well, what is it that makes the atoms dance? 625 00:36:54,127 --> 00:36:56,862 How is the energy of a star transformed 626 00:36:56,896 --> 00:36:59,898 into everything that happens in the world? 627 00:36:59,932 --> 00:37:02,167 What is energy? 628 00:37:02,201 --> 00:37:03,869 We're awash in it. 629 00:37:03,903 --> 00:37:06,671 When hydrogen atoms fuse inside the Sun, 630 00:37:06,706 --> 00:37:08,373 they make helium atoms. 631 00:37:08,408 --> 00:37:10,876 And this fusion emits a burst of energy 632 00:37:10,910 --> 00:37:14,179 that can wander inside the Sun for ten million years 633 00:37:14,213 --> 00:37:16,681 before making its way to the surface. 634 00:37:16,716 --> 00:37:19,217 And once there, it's free to fly 635 00:37:19,252 --> 00:37:21,420 straight from the Sun to the Earth 636 00:37:21,454 --> 00:37:24,089 as visible light. 637 00:37:24,123 --> 00:37:27,259 If it should strike the surface of a leaf, 638 00:37:27,293 --> 00:37:30,228 it will be stored in the plant as chemical energy. 639 00:37:30,263 --> 00:37:32,264 Sunshine... 640 00:37:32,298 --> 00:37:34,166 into moonshine. 641 00:37:53,586 --> 00:37:57,289 I can feel my brain turning the chemical energy of the wine 642 00:37:57,323 --> 00:37:59,458 into the electrical energy of my thoughts 643 00:37:59,492 --> 00:38:01,226 and directing my vocal chords 644 00:38:01,260 --> 00:38:03,995 to produce the acoustic energy of my voice. 645 00:38:04,030 --> 00:38:06,465 Such transformations of energy 646 00:38:06,499 --> 00:38:09,067 are happening everywhere all the time. 647 00:38:09,102 --> 00:38:10,736 Energy from our star 648 00:38:10,770 --> 00:38:12,771 drives the wind and the waves 649 00:38:12,805 --> 00:38:14,606 and the life around us. 650 00:38:14,640 --> 00:38:18,076 How lucky we are to have this vast source of clean energy 651 00:38:18,111 --> 00:38:22,013 falling like manna from heaven on all of us. 652 00:38:22,048 --> 00:38:23,949 To Annie Jump Cannon, 653 00:38:23,983 --> 00:38:25,617 Henrietta Swan Leavitt 654 00:38:25,651 --> 00:38:27,285 and Cecilia Payne 655 00:38:27,320 --> 00:38:30,255 for blazing the trail to modern astrophysics. 656 00:38:30,289 --> 00:38:34,192 And to all the sisters of the Sun. 657 00:38:40,133 --> 00:38:44,102 There's no refuge from change in the cosmos. 658 00:38:44,137 --> 00:38:46,972 Some ten or 20 million years from now, 659 00:38:47,006 --> 00:38:49,274 it'll seem for a cosmic moment 660 00:38:49,308 --> 00:38:53,011 as if Orion is finally about to catch the seven sisters. 661 00:38:53,046 --> 00:38:55,614 But before he has them in his clutches, 662 00:38:55,648 --> 00:38:59,317 the biggest stars of Orion will go supernova. 663 00:38:59,352 --> 00:39:02,454 Orion's pursuit of the Pleiades will finally end, 664 00:39:02,488 --> 00:39:03,955 and the seven sisters 665 00:39:03,990 --> 00:39:06,825 will glide serenely into the waiting arms 666 00:39:06,859 --> 00:39:09,227 of the Milky Way. 667 00:39:11,898 --> 00:39:14,666 We on Earth marvel-- and rightly so-- 668 00:39:14,701 --> 00:39:17,502 at the return of our solitary Sun. 669 00:39:17,537 --> 00:39:19,871 But from a planet orbiting a star 670 00:39:19,906 --> 00:39:21,873 in a distant globular cluster, 671 00:39:21,908 --> 00:39:25,010 a still more glorious dawn awaits. 672 00:39:26,279 --> 00:39:28,413 Not a sunrise... 673 00:39:28,448 --> 00:39:31,383 but a galaxy rise. 674 00:39:31,417 --> 00:39:35,487 A morning filled with 200 billion suns. 675 00:39:35,521 --> 00:39:38,490 The rising of the Milky Way. 676 00:39:38,524 --> 00:39:42,227 An enormous spiral form with collapsing gas clouds, 677 00:39:42,261 --> 00:39:45,897 condensing planetary systems, luminous supergiants, 678 00:39:45,932 --> 00:39:49,835 stable middle-aged suns, red giants, white dwarfs, 679 00:39:49,869 --> 00:39:52,270 planetary nebulas, supernovas, 680 00:39:52,305 --> 00:39:55,240 neutron stars, pulsars, black holes 681 00:39:55,274 --> 00:39:57,776 and, there is every reason to think, 682 00:39:57,810 --> 00:40:02,080 other exotic objects that we have yet to discover. 683 00:40:02,115 --> 00:40:05,951 From such a world, high above the Milky Way, 684 00:40:05,985 --> 00:40:08,620 it would be clear, as it is beginning 685 00:40:08,654 --> 00:40:10,856 to be clear on our world, 686 00:40:10,890 --> 00:40:15,193 that we are made by the atoms and the stars, 687 00:40:15,228 --> 00:40:17,262 that our matter and our form 688 00:40:17,296 --> 00:40:21,900 are forged by the great and ancient cosmos, 689 00:40:21,934 --> 00:40:24,603 of which we are a part.