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These are the user uploaded subtitles that are being translated: 1 00:00:01,401 --> 00:00:05,393 ♪♪ 2 00:00:05,432 --> 00:00:11,921 In a universe that shines with innumerable stars, 3 00:00:11,955 --> 00:00:14,606 born from countless more stars 4 00:00:14,642 --> 00:00:19,910 that have come and gone before them, 5 00:00:19,952 --> 00:00:26,594 rages the life-giving fire of our sun. 6 00:00:26,636 --> 00:00:27,956 The sun is the king of the solar system. 7 00:00:27,979 --> 00:00:32,168 It has essentially all the mass and all the energy. 8 00:00:32,202 --> 00:00:36,707 Familiar and yet unknown. 9 00:00:36,743 --> 00:00:38,639 Even though we've looked at it for a really long time, 10 00:00:38,662 --> 00:00:42,752 the sun is still full of mysteries. 11 00:00:42,788 --> 00:00:46,431 Why is it hotter in its atmosphere than on its surface? 12 00:00:46,466 --> 00:00:48,408 What drives the solar wind? 13 00:00:52,383 --> 00:00:55,448 Only now we take our first steps closer 14 00:00:55,485 --> 00:00:58,583 to understanding our star... 15 00:00:58,619 --> 00:01:00,659 It is the first time 16 00:01:00,698 --> 00:01:02,424 that we're actually going in to touch the sun. 17 00:01:04,472 --> 00:01:05,601 And it's already really started 18 00:01:05,624 --> 00:01:06,848 to truly transform our understanding 19 00:01:06,871 --> 00:01:07,830 for how the sun works. 20 00:01:09,750 --> 00:01:15,563 Uncovering the secret power of all stars... 21 00:01:15,603 --> 00:01:20,205 As you can imagine, when you have a huge blob of flaming gas, 22 00:01:20,240 --> 00:01:21,931 the core is usually the hottest. 23 00:01:24,111 --> 00:01:26,499 And it is where the magic is happening. 24 00:01:26,540 --> 00:01:29,507 Perhaps even finding clues 25 00:01:29,547 --> 00:01:32,329 to the stars that came before it... 26 00:01:32,362 --> 00:01:33,458 If we understand where the sun comes from, 27 00:01:33,481 --> 00:01:35,107 we can understand a little bit more 28 00:01:35,144 --> 00:01:37,697 about where life has come from. 29 00:01:37,927 --> 00:01:41,439 And, ultimately, its fate. 30 00:01:41,477 --> 00:01:45,273 It has about another 4.6 billion years of nuclear fusion left. 31 00:01:45,315 --> 00:01:47,933 And then it will start to change. 32 00:01:47,970 --> 00:01:49,595 It will start to evolve. 33 00:01:49,633 --> 00:01:51,205 We really need to understand 34 00:01:51,360 --> 00:01:53,661 what will happen to our own sun, 35 00:01:53,695 --> 00:01:58,363 because that will impact Earth. 36 00:01:58,397 --> 00:02:00,404 The sun is just one among 37 00:02:00,443 --> 00:02:06,965 hundreds of billions of stars in a galaxy among trillions. 38 00:02:06,999 --> 00:02:09,301 ♪♪ 39 00:02:09,334 --> 00:02:14,035 We live in "The Age of Stars." 40 00:02:14,068 --> 00:02:15,977 Right now, on "NOVA." 41 00:02:16,019 --> 00:02:17,743 ♪♪ 42 00:02:39,687 --> 00:02:42,337 ♪ See me when I float like a dove ♪ 43 00:02:42,373 --> 00:02:45,340 ♪ The skies above are lined with trees ♪ 44 00:02:45,379 --> 00:02:48,575 ♪ I'm on my knees, begging please ♪ 45 00:02:48,610 --> 00:02:55,285 ♪ Come and take me away ♪ 46 00:03:03,930 --> 00:03:08,468 ♪♪ 47 00:03:13,941 --> 00:03:17,420 93 million miles from Earth, 48 00:03:17,459 --> 00:03:20,622 our nearest star, the sun. 49 00:03:20,657 --> 00:03:24,518 ♪♪ 50 00:03:28,557 --> 00:03:31,523 A permanent fixture for life on our planet. 51 00:03:37,288 --> 00:03:39,776 Humans have always been fascinated by the sun. 52 00:03:39,815 --> 00:03:41,375 I think because it is so constant 53 00:03:41,415 --> 00:03:43,935 compared to our daily life. 54 00:03:43,973 --> 00:03:47,201 ♪♪ 55 00:03:47,235 --> 00:03:50,496 It's been rising and setting since the day that we were born. 56 00:03:50,529 --> 00:03:54,358 We keep time by it, we keep our calendars by it. 57 00:03:54,400 --> 00:03:56,821 Without it, life wouldn't be possible here on Earth. 58 00:03:57,054 --> 00:03:59,988 ♪♪ 59 00:04:00,029 --> 00:04:01,916 The sun is just one of more than 60 00:04:01,948 --> 00:04:07,183 a billion trillion stars in the universe. 61 00:04:07,225 --> 00:04:12,461 Why is it around our star that life has emerged? 62 00:04:12,502 --> 00:04:14,526 We want to know where do we come from, 63 00:04:14,549 --> 00:04:16,338 and what are our cosmic origins. 64 00:04:18,739 --> 00:04:20,681 If we understand where the sun comes from, 65 00:04:20,721 --> 00:04:22,183 we can understand a little bit more 66 00:04:22,225 --> 00:04:23,414 about where life has come from. 67 00:04:25,456 --> 00:04:27,528 But our star is an enigma. 68 00:04:30,189 --> 00:04:33,058 The sun is still full of mysteries. 69 00:04:33,099 --> 00:04:35,968 Why is it hotter in its atmosphere than on its surface? 70 00:04:36,010 --> 00:04:39,686 What drives the solar wind? 71 00:04:39,720 --> 00:04:43,613 We've spent millennia studying from afar. 72 00:04:43,654 --> 00:04:46,719 But only now are we getting close enough 73 00:04:46,948 --> 00:04:51,103 to truly reveal its secrets. 74 00:04:53,920 --> 00:04:59,069 ♪♪ 75 00:04:59,101 --> 00:05:00,520 The sun's not a very nice environment. 76 00:05:03,515 --> 00:05:04,772 It's not easy to get up close to the sun. 77 00:05:04,795 --> 00:05:09,267 ♪♪ 78 00:05:09,304 --> 00:05:11,573 It's an enormous ball of hydrogen, 79 00:05:11,607 --> 00:05:13,525 and it's putting out a tremendous amount of energy. 80 00:05:16,405 --> 00:05:20,811 Its surface is a bubbling caldron of 10,000-degree plasma. 81 00:05:20,851 --> 00:05:24,908 We can actually see cells of hot gas 82 00:05:24,945 --> 00:05:27,366 rising and falling, it's incredible imagery. 83 00:05:27,407 --> 00:05:30,189 And then above that, you have this 84 00:05:30,221 --> 00:05:31,254 very thin atmosphere that's a million degrees. 85 00:05:31,277 --> 00:05:34,375 Super-hot. 86 00:05:34,411 --> 00:05:37,793 Seeing these images is like revealing something 87 00:05:37,833 --> 00:05:41,061 that's been right in front of us, but hidden for so long. 88 00:05:41,096 --> 00:05:44,227 Occasionally you might see this enormous coronal mass ejection 89 00:05:44,262 --> 00:05:47,393 erupting from the star. 90 00:05:50,307 --> 00:05:53,622 We now stand on the threshold 91 00:05:53,665 --> 00:05:55,454 of being able to survive a close encounter. 92 00:05:55,488 --> 00:05:57,725 ♪♪ 93 00:05:57,951 --> 00:06:00,852 With a new heat-resistant probe 94 00:06:00,894 --> 00:06:03,260 that's giving us an up-close look 95 00:06:03,292 --> 00:06:05,332 at our sun for the first time. 96 00:06:06,714 --> 00:06:08,208 Status check. 97 00:06:08,250 --> 00:06:09,460 Go Delta. 98 00:06:09,497 --> 00:06:11,024 Go PSP. 99 00:06:11,064 --> 00:06:12,341 Minus 15. 100 00:06:12,375 --> 00:06:13,869 Launch night, 101 00:06:13,911 --> 00:06:15,318 I was sick to my stomach. 102 00:06:15,349 --> 00:06:17,259 Five, four, 103 00:06:17,301 --> 00:06:22,002 three, two, one, zero. 104 00:06:22,034 --> 00:06:23,922 Lift off, 105 00:06:23,953 --> 00:06:26,953 of the mighty Delta 4 heavy rocket with NASA's 106 00:06:26,992 --> 00:06:28,056 Parker Solar Probe. 107 00:06:28,079 --> 00:06:29,388 There we go. 108 00:06:33,165 --> 00:06:36,547 The Delta 4 heavy is a very slow rocket 109 00:06:36,587 --> 00:06:38,856 compared to the other launches I've seen. 110 00:06:38,889 --> 00:06:40,744 So I just saw fireballs, 111 00:06:40,777 --> 00:06:43,230 and was very, very frightened for a while. 112 00:06:43,272 --> 00:06:45,660 25 seconds into flight. 113 00:06:45,702 --> 00:06:48,570 It is quite scary to think about all that power in the rocket 114 00:06:48,804 --> 00:06:50,812 underneath that, you know, 115 00:06:50,851 --> 00:06:52,395 relatively small spacecraft sitting on top. 116 00:06:52,418 --> 00:06:55,713 Continue to look good on all three boosters. 117 00:06:55,745 --> 00:06:58,079 Then realizing that this was all okay 118 00:06:58,112 --> 00:07:01,013 as it slowly made its way up into the sky. 119 00:07:01,054 --> 00:07:03,507 Now 50 seconds into flight. 120 00:07:09,466 --> 00:07:13,043 And we have jettisoned both strap-on boosters. 121 00:07:13,079 --> 00:07:16,340 Parker is just an exquisite mission. 122 00:07:16,374 --> 00:07:19,275 It will be the closest that our species has thus far come 123 00:07:19,508 --> 00:07:20,861 to literally touching the sun itself. 124 00:07:20,884 --> 00:07:24,777 ♪♪ 125 00:07:32,398 --> 00:07:34,983 The Parker Solar Probe is traveling to a place 126 00:07:35,020 --> 00:07:39,110 that has been completely unexplored up close. 127 00:07:48,293 --> 00:07:50,530 Until now. 128 00:07:52,579 --> 00:07:55,677 ♪♪ 129 00:07:58,144 --> 00:08:01,405 NASA's Parker Solar Probe, 130 00:08:01,439 --> 00:08:03,708 a daring mission to shed light 131 00:08:03,741 --> 00:08:07,799 on the mysteries of our closest star. 132 00:08:17,718 --> 00:08:23,150 This is a journey into Never-Never Land, you might say. 133 00:08:26,769 --> 00:08:29,223 During its seven year mission, 134 00:08:29,264 --> 00:08:32,559 the Parker Solar Probe will attempt a series of dives 135 00:08:32,590 --> 00:08:35,307 towards the surface of the sun. 136 00:08:37,388 --> 00:08:41,794 Its goal is to understand how the sun sheds its energy. 137 00:08:42,025 --> 00:08:45,636 ♪♪ 138 00:08:45,863 --> 00:08:49,211 Orbiting a total of 24 times... 139 00:08:53,699 --> 00:08:57,888 Each pass taking it perilously closer. 140 00:08:57,921 --> 00:09:03,635 ♪♪ 141 00:09:03,678 --> 00:09:07,539 So close it will enter the sun's atmosphere. 142 00:09:07,580 --> 00:09:12,150 ♪♪ 143 00:09:12,186 --> 00:09:16,974 Braving temperatures no spacecraft has ever endured. 144 00:09:17,015 --> 00:09:22,315 ♪♪ 145 00:09:25,490 --> 00:09:27,759 And traveling faster 146 00:09:27,794 --> 00:09:30,640 than any other human-made object has before. 147 00:09:30,672 --> 00:09:35,275 ♪♪ 148 00:09:37,804 --> 00:09:42,658 ♪♪ 149 00:09:42,698 --> 00:09:47,781 The mission is still in its early days. 150 00:09:47,815 --> 00:09:51,261 But in the coming years, the Parker Solar Probe 151 00:09:51,301 --> 00:09:56,350 will help us unlock not only the secrets of our own sun 152 00:09:56,387 --> 00:10:00,095 but all stars. 153 00:10:00,128 --> 00:10:06,552 Including those that hold the key to the sun's origins, 154 00:10:06,588 --> 00:10:07,898 and our own. 155 00:10:07,932 --> 00:10:10,965 ♪♪ 156 00:10:11,003 --> 00:10:14,351 We can look at the processes, look at what's inside the sun, 157 00:10:14,393 --> 00:10:17,687 and understand how it had to become that. 158 00:10:17,719 --> 00:10:20,436 What were the generations of stars before that? 159 00:10:20,470 --> 00:10:21,429 What was its ancestry? 160 00:10:26,227 --> 00:10:29,575 ♪♪ 161 00:10:32,975 --> 00:10:36,236 The sun's story can be traced back 162 00:10:36,270 --> 00:10:40,131 to its most distant stellar ancestors, 163 00:10:40,171 --> 00:10:43,487 the very first stars in the universe. 164 00:10:52,773 --> 00:10:57,921 Almost 100 million years after the Big Bang, 165 00:10:57,954 --> 00:11:02,687 the universe is dark and cold... 166 00:11:02,720 --> 00:11:08,020 Not a single star shining. 167 00:11:08,061 --> 00:11:12,053 But this universe is far from empty. 168 00:11:12,090 --> 00:11:14,708 ♪♪ 169 00:11:14,745 --> 00:11:17,712 Something is growing in the void. 170 00:11:20,886 --> 00:11:23,253 Stretching out tendrils. 171 00:11:26,675 --> 00:11:30,602 The early universe was largely hydrogen and helium, 172 00:11:30,641 --> 00:11:32,364 and only small amounts of other materials. 173 00:11:35,278 --> 00:11:38,180 None of the elements we see these days, 174 00:11:38,221 --> 00:11:41,003 no carbon, oxygen, iron, none of that. 175 00:11:45,321 --> 00:11:47,393 Even though the name "the Cosmic Dark Ages" 176 00:11:47,433 --> 00:11:49,604 suggests that there might not have been 177 00:11:49,639 --> 00:11:52,672 anything particularly interesting going on, 178 00:11:52,709 --> 00:11:54,597 it was really kind of laying the groundwork 179 00:11:54,628 --> 00:11:56,832 for the construction of 180 00:11:56,868 --> 00:11:58,722 the cosmic web. 181 00:12:00,833 --> 00:12:02,655 The cosmic web is literally 182 00:12:02,688 --> 00:12:04,476 the structure of the universe itself. 183 00:12:04,511 --> 00:12:07,358 ♪♪ 184 00:12:17,305 --> 00:12:21,973 The cosmic web is unimaginable in scale. 185 00:12:22,006 --> 00:12:26,674 Huge clouds of gas are drawn together 186 00:12:26,708 --> 00:12:31,082 by the gravity of a mysterious, invisible form of matter 187 00:12:31,121 --> 00:12:35,244 called dark matter, 188 00:12:35,279 --> 00:12:37,700 creating a great network of filaments. 189 00:12:40,716 --> 00:12:44,457 A web the size of the cosmos. 190 00:12:44,491 --> 00:12:50,053 ♪♪ 191 00:12:53,030 --> 00:12:55,583 The gas in these tendrils 192 00:12:55,620 --> 00:12:59,580 is made up of mostly hydrogen and helium. 193 00:12:59,618 --> 00:13:06,588 ♪♪ 194 00:13:06,622 --> 00:13:09,076 Where these great filaments cross 195 00:13:09,117 --> 00:13:14,004 are the places where the first stars will one day be born. 196 00:13:15,226 --> 00:13:17,877 ♪♪ 197 00:13:25,365 --> 00:13:28,626 The cosmic web has been shaping our universe 198 00:13:28,659 --> 00:13:30,569 for 13.8 billion years. 199 00:13:33,457 --> 00:13:37,100 And it's still doing so today. 200 00:13:37,135 --> 00:13:40,069 But it's only recently 201 00:13:40,109 --> 00:13:45,770 that we've actually been able to see it. 202 00:13:45,803 --> 00:13:48,617 The image that we have here is absolutely amazing. 203 00:13:48,649 --> 00:13:50,097 It's one of the most fundamental pictures 204 00:13:50,120 --> 00:13:52,062 that we can take in our universe. 205 00:13:52,103 --> 00:13:54,013 And it's actually a direct image 206 00:13:54,054 --> 00:13:55,502 of some of the largest structures that exist, 207 00:13:55,525 --> 00:13:57,827 the filaments of the cosmic web. 208 00:13:57,860 --> 00:14:00,096 Now the bright dots that you see over here, 209 00:14:00,131 --> 00:14:01,757 they're entire galaxies. 210 00:14:01,794 --> 00:14:03,681 Now, if I take those away, 211 00:14:03,713 --> 00:14:05,469 what you can see much more clearly 212 00:14:05,504 --> 00:14:07,805 is the faint glow of the hydrogen and helium 213 00:14:07,839 --> 00:14:09,846 that exists on the tendrils of the cosmic web. 214 00:14:09,886 --> 00:14:11,708 And it's on this cosmic web, 215 00:14:11,741 --> 00:14:13,170 that the story of our sun 216 00:14:13,212 --> 00:14:16,473 and the stars in the night sky begins. 217 00:14:16,507 --> 00:14:21,393 ♪♪ 218 00:14:33,202 --> 00:14:36,168 As time passes in the early universe, 219 00:14:36,208 --> 00:14:38,509 the cosmic web continues to grow... 220 00:14:42,541 --> 00:14:46,663 Gas, rushing along these great tendrils, 221 00:14:46,699 --> 00:14:49,862 traveling down towards the intersections. 222 00:14:52,903 --> 00:14:55,357 It is being pulled to these points by gravity. 223 00:15:00,195 --> 00:15:06,816 And as more gas joins, this force becomes ever stronger, 224 00:15:06,848 --> 00:15:10,011 creating great clouds staggering in size. 225 00:15:13,053 --> 00:15:16,630 They grow denser, 226 00:15:16,667 --> 00:15:19,797 hotter, 227 00:15:19,834 --> 00:15:23,760 as gas is relentlessly added 228 00:15:23,799 --> 00:15:29,939 until, at last, the conditions become so extreme 229 00:15:29,972 --> 00:15:32,393 that there is a sudden moment of ignition. 230 00:15:32,435 --> 00:15:40,103 ♪♪ 231 00:15:40,591 --> 00:15:44,517 The birth of the very first star in the universe. 232 00:15:44,556 --> 00:15:47,141 ♪♪ 233 00:15:47,179 --> 00:15:50,473 Born 17 times hotter than the sun. 234 00:15:50,505 --> 00:15:57,343 ♪♪ 235 00:15:57,381 --> 00:16:00,283 This star is a blue monster. 236 00:16:00,516 --> 00:16:04,922 ♪♪ 237 00:16:18,778 --> 00:16:22,257 ♪♪ 238 00:16:31,220 --> 00:16:32,682 The first stars 239 00:16:32,723 --> 00:16:36,170 were unlike anything we can see around us today, 240 00:16:36,209 --> 00:16:39,852 which is what makes them so incredible. 241 00:16:39,887 --> 00:16:42,407 When the very first stars formed, 242 00:16:42,446 --> 00:16:44,748 these stars ended up with giant masses 243 00:16:44,780 --> 00:16:46,602 of 500 to 600 times the mass of the sun. 244 00:16:49,770 --> 00:16:53,861 Stars today are perhaps as hot as 100,000 degrees. 245 00:16:53,896 --> 00:16:56,613 And these stars were nearly twice as hot as that. 246 00:16:56,647 --> 00:16:58,766 And the very hot color tends to also make them look blue. 247 00:16:58,789 --> 00:17:02,171 ♪♪ 248 00:17:02,211 --> 00:17:05,026 But this first star is not alone for long. 249 00:17:07,937 --> 00:17:11,613 At intersections across the cosmic web, 250 00:17:11,646 --> 00:17:15,606 it's soon joined by others. 251 00:17:15,644 --> 00:17:20,345 ♪♪ 252 00:17:20,379 --> 00:17:23,760 An entire generation of first stars... 253 00:17:29,077 --> 00:17:32,011 lighting up the universe. 254 00:17:32,052 --> 00:17:36,240 ♪♪ 255 00:17:36,466 --> 00:17:38,505 But this isn't all they do. 256 00:17:38,545 --> 00:17:44,653 ♪♪ 257 00:17:44,685 --> 00:17:48,645 These stars are also forging new elements, 258 00:17:48,683 --> 00:17:53,832 creating the ingredients for all the planets 259 00:17:53,864 --> 00:17:57,790 and, ultimately, even for life to exist. 260 00:18:00,581 --> 00:18:01,581 The birth of the first stars 261 00:18:01,604 --> 00:18:03,034 signaled a complete transformation 262 00:18:03,076 --> 00:18:05,694 in the makeup of the universe. 263 00:18:05,731 --> 00:18:09,342 Before they existed, all we had was hydrogen and helium, 264 00:18:09,376 --> 00:18:13,270 but nuclear fusion completely changed all of that. 265 00:18:13,310 --> 00:18:17,302 The cores of the first stars were so hot, 266 00:18:17,341 --> 00:18:20,820 they reached more than 100 million degrees. 267 00:18:20,859 --> 00:18:25,014 And that forced hydrogen atoms to change. 268 00:18:25,048 --> 00:18:27,040 Now under the very high temperatures and pressures 269 00:18:27,063 --> 00:18:28,973 that you find in the cores of these stars, 270 00:18:29,014 --> 00:18:30,291 they were smashed together, 271 00:18:30,325 --> 00:18:33,620 fusing a heavier element, helium. 272 00:18:33,652 --> 00:18:36,913 But the first stars didn't stop there. 273 00:18:36,946 --> 00:18:38,920 After a few million years, 274 00:18:38,961 --> 00:18:41,262 the hydrogen completely runs out. 275 00:18:41,296 --> 00:18:44,328 So instead, the helium atoms are forced to be smashed together, 276 00:18:44,366 --> 00:18:46,154 creating even heavier elements, 277 00:18:46,189 --> 00:18:51,555 such as carbon, oxygen, and iron. 278 00:18:51,594 --> 00:18:54,725 The new elements these first stars forged 279 00:18:54,761 --> 00:18:59,975 are the elements that seed other types of stars, planets, 280 00:19:00,006 --> 00:19:01,916 and even us. 281 00:19:01,957 --> 00:19:04,510 ♪♪ 282 00:19:04,740 --> 00:19:08,001 In other words, the elements for life. 283 00:19:11,712 --> 00:19:15,540 But the era of blue giants can't last. 284 00:19:18,428 --> 00:19:20,730 Fusion at the center of a star 285 00:19:20,763 --> 00:19:23,130 eventually ends as it runs out of fuel, 286 00:19:23,162 --> 00:19:25,234 so the process can't go on forever. 287 00:19:25,272 --> 00:19:28,022 ♪♪ 288 00:19:28,055 --> 00:19:29,997 When fusion stops, 289 00:19:30,038 --> 00:19:33,267 you lose that internal pressure which pushes against gravity. 290 00:19:33,300 --> 00:19:35,721 You lose a tug of war, 291 00:19:35,764 --> 00:19:38,316 and the gravity starts to push down on the star. 292 00:19:38,354 --> 00:19:42,825 ♪♪ 293 00:19:42,864 --> 00:19:45,035 You know that saying, "Live fast, die young"? 294 00:19:45,070 --> 00:19:47,209 That really applies to stars, right? 295 00:19:47,245 --> 00:19:49,830 So the most massive, luminous stars 296 00:19:49,868 --> 00:19:51,046 have the shortest lifetimes. 297 00:19:51,083 --> 00:19:52,905 Even though they have much more hydrogen fuel 298 00:19:52,939 --> 00:19:54,761 than an ordinary star like our sun, 299 00:19:54,794 --> 00:19:57,695 they burn it so quickly that they only live 300 00:19:57,736 --> 00:20:01,477 a few million years before they burn out. 301 00:20:01,510 --> 00:20:03,931 And a few million years, in astronomy time, 302 00:20:03,973 --> 00:20:05,795 that's the blink of an eye. 303 00:20:09,442 --> 00:20:14,230 With its fuel spent, fusion reactions stop. 304 00:20:17,757 --> 00:20:20,310 And gravity takes over. 305 00:20:24,505 --> 00:20:29,490 ♪♪ 306 00:20:49,037 --> 00:20:51,491 The core collapses. 307 00:20:53,675 --> 00:20:59,586 ♪♪ 308 00:20:59,623 --> 00:21:02,143 Gas suddenly falls inwards. 309 00:21:05,956 --> 00:21:10,014 ♪♪ 310 00:21:19,134 --> 00:21:23,540 And then rebounds 311 00:21:23,579 --> 00:21:28,247 in a colossal explosion called a supernova. 312 00:21:28,281 --> 00:21:31,793 ♪♪ 313 00:21:50,413 --> 00:21:53,030 A shockwave of energy, 314 00:21:53,068 --> 00:21:58,695 followed by material hurtling outwards into space. 315 00:22:05,253 --> 00:22:09,442 Supernovae explosions rocked the universe. 316 00:22:09,475 --> 00:22:11,450 They are amongst the most explosive events 317 00:22:11,490 --> 00:22:13,759 that we now know about. 318 00:22:13,792 --> 00:22:18,101 Briefly, a single supernova can outshine an entire galaxy. 319 00:22:21,468 --> 00:22:25,329 This was a very important moment in the history of the universe. 320 00:22:25,371 --> 00:22:28,217 It allowed the universe to kind of start evolving. 321 00:22:30,360 --> 00:22:33,556 After the first stars exploded, 322 00:22:33,590 --> 00:22:36,437 the material that has been forged in their interiors 323 00:22:36,469 --> 00:22:39,981 was spewn out into space. 324 00:22:40,019 --> 00:22:44,720 They seeded the universe with these heavy elements 325 00:22:44,752 --> 00:22:47,119 and paved the way for subsequent generations of stars. 326 00:22:52,717 --> 00:22:56,938 Generations of stars that we can see in the night sky. 327 00:23:00,520 --> 00:23:02,691 The Hubble Space Telescope 328 00:23:02,727 --> 00:23:05,061 has been studying them for more than 30 years. 329 00:23:06,309 --> 00:23:09,156 ♪♪ 330 00:23:13,314 --> 00:23:18,266 Showing us this epic cycle of cosmic death and renewal. 331 00:23:20,318 --> 00:23:24,092 ♪♪ 332 00:23:24,124 --> 00:23:26,906 It’s not only the first stars which enriched the universe. 333 00:23:29,305 --> 00:23:31,247 As you go on for the second, the third, 334 00:23:31,480 --> 00:23:33,651 the fourth generation of stars, 335 00:23:33,687 --> 00:23:36,272 they're all creating more and more heavy elements 336 00:23:36,309 --> 00:23:38,219 which get expelled into the universe. 337 00:23:38,261 --> 00:23:44,369 ♪♪ 338 00:23:49,486 --> 00:23:54,122 Hubble reveals to us how stars have evolved 339 00:23:54,156 --> 00:23:58,857 from a primitive universe dominated by blue stars 340 00:23:58,890 --> 00:24:02,663 to our universe today, 341 00:24:02,696 --> 00:24:08,357 populated by stars of every color, size, and configuration. 342 00:24:08,389 --> 00:24:11,454 ♪♪ 343 00:24:11,491 --> 00:24:14,241 Neutron stars 344 00:24:14,274 --> 00:24:19,455 violently spinning up to 700 times a second, 345 00:24:19,487 --> 00:24:21,853 spitting out jets of radiation. 346 00:24:27,547 --> 00:24:29,369 Stars so huge, 347 00:24:31,673 --> 00:24:34,803 that more than a billion suns could fit inside them. 348 00:24:37,910 --> 00:24:39,261 There are many types of stars. 349 00:24:39,284 --> 00:24:43,756 Wolf-Rayet stars, red giant stars, white dwarf stars. 350 00:24:43,794 --> 00:24:46,314 All of them have their own unique characteristics. 351 00:24:46,353 --> 00:24:51,207 ♪♪ 352 00:24:51,246 --> 00:24:53,035 And some that aren't alone. 353 00:24:56,140 --> 00:24:59,914 They are kept company by systems of planets, 354 00:24:59,946 --> 00:25:04,701 including rocky worlds built of ingredients 355 00:25:04,743 --> 00:25:07,971 like carbon, silicon, and iron. 356 00:25:14,882 --> 00:25:17,020 So stars really are the engines 357 00:25:17,057 --> 00:25:19,423 of higher-order complexity in the universe, right? 358 00:25:19,456 --> 00:25:22,041 They're the factories that make up the heavier elements 359 00:25:22,078 --> 00:25:23,485 that are the seeds of things 360 00:25:23,517 --> 00:25:25,721 like planets. 361 00:25:28,539 --> 00:25:32,662 Stars have changed the entirety of the universe, 362 00:25:32,697 --> 00:25:37,911 filling it with all manner of wondrous celestial objects, 363 00:25:38,134 --> 00:25:41,101 and ultimately paving the way for a star 364 00:25:41,140 --> 00:25:47,182 that has all the right conditions to make us. 365 00:25:47,217 --> 00:25:51,078 The sun must have relied on many, many generations 366 00:25:51,119 --> 00:25:53,258 of previous stars for the material 367 00:25:53,486 --> 00:25:55,493 that's there today in our solar system. 368 00:25:55,532 --> 00:25:56,994 Probably thousands of other stars 369 00:25:57,036 --> 00:25:58,036 that would have had to explode. 370 00:25:58,059 --> 00:26:03,076 ♪♪ 371 00:26:11,204 --> 00:26:14,717 Nine billion years after the birth of the first star. 372 00:26:17,729 --> 00:26:20,576 The universe has been enriched 373 00:26:20,608 --> 00:26:23,923 with dozens of new elements. 374 00:26:29,179 --> 00:26:33,433 Here, gravity draws one cloud together 375 00:26:33,465 --> 00:26:37,904 and our own star is born. 376 00:26:40,789 --> 00:26:46,766 ♪♪ 377 00:26:53,102 --> 00:26:57,225 But not all of the material is used to create the sun. 378 00:27:03,721 --> 00:27:07,037 ♪♪ 379 00:27:07,080 --> 00:27:10,243 Some remains in orbit. 380 00:27:13,188 --> 00:27:15,555 And it's from these leftovers 381 00:27:15,587 --> 00:27:21,117 that eight extraordinary planets form our solar system. 382 00:27:22,943 --> 00:27:24,831 The sun has a very tight relationship 383 00:27:24,862 --> 00:27:26,396 with all the planets in the solar system. 384 00:27:28,093 --> 00:27:29,509 Not just because of its enormous gravity, 385 00:27:29,532 --> 00:27:31,953 but because of the light that it provides. 386 00:27:36,152 --> 00:27:39,981 Some of these worlds seem just too far away from the sun 387 00:27:40,022 --> 00:27:41,615 for complex life to take hold. 388 00:27:46,003 --> 00:27:50,312 Deprived of light, they may be devoid of any life at all. 389 00:27:53,775 --> 00:27:56,360 ♪♪ 390 00:27:59,692 --> 00:28:03,335 These are the gas and ice giants. 391 00:28:03,370 --> 00:28:06,239 ♪♪ 392 00:28:08,551 --> 00:28:11,071 In contrast, others are too close to the sun. 393 00:28:14,308 --> 00:28:16,446 They are relentlessly blasted... 394 00:28:20,385 --> 00:28:23,232 Until they become scorched deserts. 395 00:28:28,029 --> 00:28:30,844 But there is a sweet spot. 396 00:28:30,875 --> 00:28:34,900 ♪♪ 397 00:28:34,937 --> 00:28:37,904 Neither too far nor too close to the sun. 398 00:28:43,029 --> 00:28:45,298 It's in this place... 399 00:28:49,170 --> 00:28:50,185 that the chemical legacy 400 00:28:50,225 --> 00:28:56,333 of generations of long-gone stars 401 00:28:56,367 --> 00:29:01,100 would form something astonishing. 402 00:29:06,089 --> 00:29:07,911 We are, on the Earth, on kind of 403 00:29:07,944 --> 00:29:09,286 this special, sweet zone. 404 00:29:09,319 --> 00:29:10,694 They call it the Goldilocks zone. 405 00:29:10,726 --> 00:29:14,108 This exciting distance from a star 406 00:29:14,148 --> 00:29:16,003 where a planet could conceivably have 407 00:29:16,036 --> 00:29:17,246 liquid water on its surface. 408 00:29:19,043 --> 00:29:21,792 Water is the medium that facilitates 409 00:29:21,824 --> 00:29:23,647 the biochemical reactions 410 00:29:23,680 --> 00:29:25,109 that are responsible for life. 411 00:29:28,158 --> 00:29:29,542 Earth's relationship with the sun 412 00:29:29,565 --> 00:29:32,281 is the most important relationship there is. 413 00:29:32,316 --> 00:29:37,170 ♪♪ 414 00:29:40,983 --> 00:29:45,291 The sun is constantly reaching out to our planet, 415 00:29:45,333 --> 00:29:49,106 something the Parker Solar Probe is helping us understand. 416 00:29:52,753 --> 00:29:55,403 What makes Parker so great is the fact that 417 00:29:55,439 --> 00:29:58,286 it has a great set of instruments that work together 418 00:29:58,318 --> 00:30:01,612 in order to look in all directions. 419 00:30:01,644 --> 00:30:04,905 So there's this sun-facing part of the probe 420 00:30:04,939 --> 00:30:06,946 that peeks above the heat shield 421 00:30:06,985 --> 00:30:08,480 and literally looks directly at the sun. 422 00:30:11,175 --> 00:30:14,654 The Parker Solar Probe is spotting holes 423 00:30:14,694 --> 00:30:17,475 in the sun's atmosphere... 424 00:30:17,508 --> 00:30:19,875 Vents that release 425 00:30:19,906 --> 00:30:23,167 a blizzard of charged particles 426 00:30:23,201 --> 00:30:25,982 at more than a million miles an hour. 427 00:30:26,015 --> 00:30:29,941 What we call the solar wind. 428 00:30:29,981 --> 00:30:32,403 We can tell how the energy flows, 429 00:30:32,444 --> 00:30:34,353 where the wind is coming off, 430 00:30:34,395 --> 00:30:35,856 how much of the wind is coming off. 431 00:30:38,649 --> 00:30:42,325 The solar wind travels billions of miles, 432 00:30:42,359 --> 00:30:45,675 bombarding the planets with radiation. 433 00:30:47,380 --> 00:30:49,616 The charged particles in the solar wind 434 00:30:49,651 --> 00:30:52,552 can be detrimental to life. 435 00:30:52,593 --> 00:30:55,342 On Earth, we're protected by the Earth's magnetic field, 436 00:30:55,376 --> 00:30:56,937 which deflects the particles. 437 00:30:56,975 --> 00:30:59,341 So it's kind of like we have our shields up, 438 00:30:59,566 --> 00:31:01,191 and our shield is our magnetic field. 439 00:31:04,363 --> 00:31:07,429 Earth has defenses that protect life 440 00:31:07,466 --> 00:31:09,768 from our star's violent tendencies. 441 00:31:11,815 --> 00:31:14,116 But the sun also provides 442 00:31:14,150 --> 00:31:16,539 something essential to our planet. 443 00:31:16,581 --> 00:31:18,468 At the core of it, 444 00:31:18,500 --> 00:31:22,296 the sun is forging hydrogen into helium, 445 00:31:22,338 --> 00:31:24,509 which is what is releasing the energy 446 00:31:24,544 --> 00:31:27,446 that we get here on Earth. 447 00:31:27,487 --> 00:31:28,829 The photons, 448 00:31:28,863 --> 00:31:32,277 these packets of energy, when they are formed, 449 00:31:32,316 --> 00:31:35,130 they don't go straight from the center 450 00:31:35,163 --> 00:31:37,465 rushing through to the surface. 451 00:31:37,498 --> 00:31:39,986 They go through a very bumpy ride. 452 00:31:40,025 --> 00:31:43,407 They get tossed from one atom to the other. 453 00:31:43,447 --> 00:31:47,918 They get absorbed and spit out, absorbed and spit out. 454 00:31:47,957 --> 00:31:51,501 So it takes a really convoluted path out of that sun, 455 00:31:51,539 --> 00:31:52,881 and that can take millions of years. 456 00:31:55,248 --> 00:31:57,801 Once these photons arrive at the surface, 457 00:31:57,839 --> 00:32:01,613 they're liberated as sunshine. 458 00:32:01,646 --> 00:32:09,314 ♪♪ 459 00:32:13,095 --> 00:32:15,964 The light races across the solar system. 460 00:32:17,669 --> 00:32:21,312 ♪♪ 461 00:32:21,347 --> 00:32:25,918 Unobstructed, it flashes past the planets 462 00:32:25,952 --> 00:32:30,740 at 180,000 miles per second. 463 00:32:30,782 --> 00:32:34,229 If you could take all the energy that humans are producing 464 00:32:34,269 --> 00:32:35,730 and store it in batteries, 465 00:32:35,772 --> 00:32:38,706 the entire civilization, for 50,000 years, 466 00:32:38,746 --> 00:32:41,811 you could make the sun shine for one second. 467 00:32:42,967 --> 00:32:48,977 ♪♪ 468 00:32:49,013 --> 00:32:52,046 It takes just over eight minutes 469 00:32:52,083 --> 00:32:54,472 for the sun's light to reach Earth. 470 00:32:58,575 --> 00:33:02,884 That stream of light is like an umbilical cord of energy 471 00:33:02,925 --> 00:33:05,478 coming down to us here on the Earth. 472 00:33:05,516 --> 00:33:08,647 And it's been pretty much constant and unbroken 473 00:33:08,682 --> 00:33:11,235 for nearly five billion years. 474 00:33:11,273 --> 00:33:15,167 And it's this combination of the stability of light, 475 00:33:15,207 --> 00:33:19,264 stability of energy over billions of years, 476 00:33:19,301 --> 00:33:21,689 that means complex life that we see around us 477 00:33:21,732 --> 00:33:24,185 here on the Earth has been able to form 478 00:33:24,226 --> 00:33:26,048 and has been able to thrive. 479 00:33:28,927 --> 00:33:33,334 ♪♪ 480 00:33:39,834 --> 00:33:43,095 ♪♪ 481 00:33:49,014 --> 00:33:52,395 We don't know exactly how life emerges on early Earth. 482 00:33:58,193 --> 00:34:01,988 But what we do know is that primitive cells, 483 00:34:02,031 --> 00:34:06,818 living in the ocean, begin to use the sun's energy 484 00:34:06,860 --> 00:34:09,641 to power life-giving chemical reactions. 485 00:34:10,666 --> 00:34:14,440 ♪♪ 486 00:34:14,471 --> 00:34:17,886 These cells are the bridge between sun and Earth. 487 00:34:22,052 --> 00:34:24,898 Tiny machines that harness the power of our star. 488 00:34:27,777 --> 00:34:32,597 The cells use sunlight to turn carbon dioxide and water 489 00:34:32,639 --> 00:34:35,453 into food in the form of sugar. 490 00:34:39,803 --> 00:34:42,672 This process, photosynthesis, 491 00:34:42,713 --> 00:34:47,446 is a direct use of the sun's power. 492 00:34:52,052 --> 00:34:55,150 ♪♪ 493 00:34:55,186 --> 00:34:59,146 It has driven the evolution of complexity on Earth... 494 00:34:59,184 --> 00:35:04,268 ♪♪ 495 00:35:04,302 --> 00:35:06,407 From primitive bacteria, 496 00:35:06,444 --> 00:35:09,477 to plants and trees... 497 00:35:13,033 --> 00:35:15,848 An unbroken line of living things. 498 00:35:17,895 --> 00:35:21,604 All connected to the power source in the sky. 499 00:35:25,571 --> 00:35:29,182 Everything from the little blade of grass 500 00:35:29,216 --> 00:35:31,583 to the biggest oak tree, 501 00:35:31,616 --> 00:35:34,931 they use the sunlight 502 00:35:34,973 --> 00:35:38,420 to photosynthesize and produce the energy 503 00:35:38,460 --> 00:35:40,881 that we later consume 504 00:35:40,923 --> 00:35:43,705 to sustain ourselves. 505 00:35:43,737 --> 00:35:45,493 So in a way, 506 00:35:45,528 --> 00:35:48,081 we have been feeding on starlight. 507 00:35:48,119 --> 00:35:55,699 ♪♪ 508 00:35:55,731 --> 00:35:59,919 Trillions of stars have existed since the universe began. 509 00:35:59,953 --> 00:36:04,937 But ours is the only one we know of 510 00:36:04,974 --> 00:36:09,129 that has nurtured that wonderful thing, life. 511 00:36:09,164 --> 00:36:14,399 Not only nourished by the sun's light, 512 00:36:14,441 --> 00:36:18,182 but also granted protection and the time to grow and change, 513 00:36:18,215 --> 00:36:24,410 eventually creating complex life. 514 00:36:24,452 --> 00:36:27,354 The sun is connected to our very existence. 515 00:36:27,394 --> 00:36:29,303 It provides the light 516 00:36:29,346 --> 00:36:33,600 and the energy that's necessary to sustain life. 517 00:36:33,631 --> 00:36:34,951 There would absolutely be no life on Earth 518 00:36:34,974 --> 00:36:35,933 if there was no sun. 519 00:36:35,966 --> 00:36:43,635 ♪♪ 520 00:36:43,770 --> 00:36:45,973 The sun is a creator... 521 00:36:48,376 --> 00:36:51,855 Bringing together atoms 522 00:36:51,893 --> 00:36:55,154 forged in generations of ancient stars. 523 00:36:55,188 --> 00:36:57,195 ♪♪ 524 00:37:00,561 --> 00:37:05,317 To create us, 525 00:37:05,359 --> 00:37:10,060 beings capable of exploring the cosmos. 526 00:37:10,092 --> 00:37:16,735 ♪♪ 527 00:37:16,776 --> 00:37:20,158 And uncovering our own stellar ancestry. 528 00:37:23,621 --> 00:37:25,563 It's a wonderful thing, 529 00:37:25,604 --> 00:37:30,207 how we share this intimate connection with stars, 530 00:37:30,242 --> 00:37:34,975 because they are part of our cosmic heritage. 531 00:37:35,007 --> 00:37:38,868 We are the children of these stars. 532 00:37:38,909 --> 00:37:43,098 ♪♪ 533 00:37:53,461 --> 00:37:57,486 There are up to 400 billion stars in our galaxy. 534 00:38:02,161 --> 00:38:06,316 And there are two trillion galaxies in our universe. 535 00:38:10,924 --> 00:38:13,891 But it wasn't always that way. 536 00:38:17,769 --> 00:38:20,932 We are living in the age of stars. 537 00:38:20,967 --> 00:38:26,399 ♪♪ 538 00:38:26,436 --> 00:38:31,868 An era of light in the universe. 539 00:38:31,906 --> 00:38:35,004 Stars have always been important to us. 540 00:38:35,040 --> 00:38:37,494 They have helped us navigate the land 541 00:38:37,534 --> 00:38:39,803 and the open seas for millennia. 542 00:38:39,837 --> 00:38:44,473 ♪♪ 543 00:38:44,506 --> 00:38:48,880 If you just think back at the countless sonnets and poems 544 00:38:48,921 --> 00:38:51,287 and songs, there is always some kind of 545 00:38:51,319 --> 00:38:52,115 celestial connection. 546 00:38:52,151 --> 00:38:55,249 ♪♪ 547 00:38:55,477 --> 00:38:57,135 One of the reasons why 548 00:38:57,172 --> 00:38:59,822 looking up into the stars is so significant 549 00:38:59,858 --> 00:39:03,436 is because we realize that others are doing 550 00:39:03,473 --> 00:39:07,945 the same exact thing, and so in a very real way, 551 00:39:07,982 --> 00:39:10,436 we feel connected to people both past and present. 552 00:39:13,164 --> 00:39:16,578 From our fleeting, human perspective, 553 00:39:16,618 --> 00:39:19,203 the stars seem everlasting. 554 00:39:22,087 --> 00:39:24,869 A constant in our night sky. 555 00:39:30,691 --> 00:39:34,073 But seen across the age of the universe, 556 00:39:34,113 --> 00:39:35,071 the picture changes. 557 00:39:37,727 --> 00:39:40,573 Because this era cannot last. 558 00:39:43,196 --> 00:39:46,610 The stars will eventually wane. 559 00:39:46,651 --> 00:39:50,577 ♪♪ 560 00:39:50,616 --> 00:39:52,787 And as they go, 561 00:39:52,823 --> 00:39:55,691 they once again change the character of the universe. 562 00:39:58,420 --> 00:40:04,583 Their cores, where fusion once raged, cool. 563 00:40:04,625 --> 00:40:11,976 ♪♪ 564 00:40:21,032 --> 00:40:24,130 And eventually solidify, 565 00:40:24,167 --> 00:40:28,127 locking precious elements away beneath the surface. 566 00:40:31,202 --> 00:40:35,456 And starving the universe of the material needed 567 00:40:35,489 --> 00:40:37,856 to make new stars and planets. 568 00:40:38,847 --> 00:40:44,409 ♪♪ 569 00:40:44,444 --> 00:40:46,331 The chance 570 00:40:46,363 --> 00:40:47,890 that a star is going to be born nowadays 571 00:40:47,930 --> 00:40:50,199 is, is much, much lower than it was 572 00:40:50,233 --> 00:40:53,582 billions of years in the past. 573 00:40:53,623 --> 00:40:57,451 Just as there was a very first star in the universe, 574 00:40:57,493 --> 00:40:59,860 there will come a time 575 00:40:59,892 --> 00:41:01,464 when the era of stars will come to an end. 576 00:41:04,402 --> 00:41:09,135 The age of stars is not as enduring as it might seem. 577 00:41:22,376 --> 00:41:24,710 I have here a timeline of the universe, 578 00:41:24,743 --> 00:41:28,190 and I'm here at the start when the universe formed 579 00:41:28,229 --> 00:41:32,483 13.8 billion years ago during the Big Bang. 580 00:41:32,515 --> 00:41:35,002 Now it took a while for the first stars to form... 581 00:41:35,041 --> 00:41:37,146 In fact, a few hundred million years. 582 00:41:37,185 --> 00:41:38,843 Let's call that 400 million years. 583 00:41:38,879 --> 00:41:42,620 So on my scale, stars start to form here, 584 00:41:42,654 --> 00:41:43,910 and those stars carried on forming, 585 00:41:43,933 --> 00:41:46,780 and then we reach this point here, 586 00:41:46,811 --> 00:41:50,225 four billion years since the Big Bang, 587 00:41:50,266 --> 00:41:54,640 and a time when the most stars are forming in the universe. 588 00:41:54,679 --> 00:41:57,907 Our sun, though, didn't form 589 00:41:57,942 --> 00:42:00,308 until nine billion years had passed. 590 00:42:00,340 --> 00:42:03,122 And that's my marker here. 591 00:42:03,155 --> 00:42:07,562 And then we move forward again, and we get to this point here, 592 00:42:07,601 --> 00:42:09,772 which is the present day, 593 00:42:09,807 --> 00:42:14,694 13.8 billion years since the formation of the universe. 594 00:42:14,732 --> 00:42:17,121 Now our sun won't live forever, 595 00:42:17,163 --> 00:42:19,978 and in fact it will start to die and end its life 596 00:42:20,010 --> 00:42:22,246 in around five billion years' time. 597 00:42:22,281 --> 00:42:24,386 But the sun will be outlived 598 00:42:24,423 --> 00:42:27,270 by the least massive stars in the universe. 599 00:42:27,302 --> 00:42:30,913 They have lifetimes of a few hundred billion years, 600 00:42:30,948 --> 00:42:34,908 and that's about 200 meters on my scale. 601 00:42:34,946 --> 00:42:37,848 But even when those stars die, 602 00:42:38,081 --> 00:42:40,698 that doesn't mark the end of the universe. 603 00:42:40,735 --> 00:42:43,582 The universe could live forever, 604 00:42:43,613 --> 00:42:47,835 with the timeline stretching far off into the distance. 605 00:42:47,867 --> 00:42:49,755 And that means that the age of starlight 606 00:42:49,786 --> 00:42:51,542 that I've mapped out here 607 00:42:51,578 --> 00:42:54,893 is like the blink of an eye to the universe. 608 00:42:54,936 --> 00:43:01,294 It's the age of darkness that goes on and on and on. 609 00:43:01,333 --> 00:43:05,455 ♪♪ 610 00:43:05,490 --> 00:43:09,199 Stars won't suddenly disappear, of course. 611 00:43:11,407 --> 00:43:14,156 They'll be here for hundreds of billions, 612 00:43:14,190 --> 00:43:17,931 perhaps even trillions, of years to come. 613 00:43:17,963 --> 00:43:21,312 But slowly over time, 614 00:43:21,354 --> 00:43:25,575 the universe will become darker. 615 00:43:25,608 --> 00:43:27,974 Emptier. 616 00:43:33,315 --> 00:43:35,039 As it expands, 617 00:43:35,074 --> 00:43:38,270 the distances between these little islands of light 618 00:43:38,305 --> 00:43:42,908 become greater and greater. 619 00:43:42,943 --> 00:43:47,448 Until one day, only one type of star will remain. 620 00:43:47,485 --> 00:43:50,648 ♪♪ 621 00:43:50,682 --> 00:43:52,024 Red dwarfs... 622 00:43:54,872 --> 00:44:00,271 The longest lived of all stars in the universe. 623 00:44:00,310 --> 00:44:06,025 Trappist 1 is one of these near immortals. 624 00:44:06,067 --> 00:44:13,134 This ancient star is likely more than seven billion years old, 625 00:44:13,167 --> 00:44:15,054 almost twice as old as our sun. 626 00:44:15,949 --> 00:44:21,381 ♪♪ 627 00:44:24,265 --> 00:44:27,166 But Trappist is tiny, 628 00:44:27,207 --> 00:44:29,117 a similar size to Jupiter. 629 00:44:35,204 --> 00:44:38,138 And less than one percent as bright as our sun. 630 00:44:41,408 --> 00:44:45,052 It is a cool star, slow burning. 631 00:44:47,709 --> 00:44:53,620 ♪♪ 632 00:44:53,657 --> 00:44:56,657 And that is the secret of its longevity. 633 00:45:00,214 --> 00:45:03,148 The lifetime of a star is determined 634 00:45:03,189 --> 00:45:07,825 by its reservoir of hydrogen, of nuclear fuel. 635 00:45:07,858 --> 00:45:09,265 As long as it has something to burn, 636 00:45:09,298 --> 00:45:10,825 it will continue to survive. 637 00:45:10,865 --> 00:45:13,069 But paradoxically, 638 00:45:13,103 --> 00:45:17,029 the stars with the least amount of hydrogen live the longest. 639 00:45:17,070 --> 00:45:20,233 And that's because they are miserly. 640 00:45:20,267 --> 00:45:24,063 They spend their fuel so slowly. 641 00:45:24,105 --> 00:45:29,570 And so it's those smaller, more quiescent, less energetic stars 642 00:45:29,606 --> 00:45:31,461 that ultimately become 643 00:45:31,494 --> 00:45:32,989 the greatest historians of the universe. 644 00:45:35,588 --> 00:45:39,580 It's especially exciting because this particular star 645 00:45:39,617 --> 00:45:41,657 is going to continue fusing hydrogen 646 00:45:41,697 --> 00:45:44,795 into helium in its core and continue shining 647 00:45:44,831 --> 00:45:48,376 for potentially hundreds of billions of years. 648 00:45:48,413 --> 00:45:56,081 ♪♪ 649 00:46:04,117 --> 00:46:06,931 Like the sun, 650 00:46:06,964 --> 00:46:09,167 Trappist has its own planets. 651 00:46:16,846 --> 00:46:19,813 Seven worlds, each roughly the size of Earth. 652 00:46:19,852 --> 00:46:24,259 ♪♪ 653 00:46:24,298 --> 00:46:28,355 Some may have atmospheres, 654 00:46:28,392 --> 00:46:30,846 and even oceans. 655 00:46:33,222 --> 00:46:36,418 But there the similarities end. 656 00:46:39,874 --> 00:46:44,183 Because these are strange worlds. 657 00:46:44,224 --> 00:46:48,533 Just as one side of the moon always faces Earth, 658 00:46:48,574 --> 00:46:52,882 these planets may be what we call "tidally locked" 659 00:46:52,924 --> 00:46:55,825 in their orbits... 660 00:46:55,865 --> 00:46:57,688 One side permanently looking towards 661 00:46:57,721 --> 00:47:01,517 the red dwarf Trappist 1, 662 00:47:01,559 --> 00:47:08,202 soaking up what light and warmth it can from the faint star; 663 00:47:08,243 --> 00:47:11,591 the other side permanently frozen, 664 00:47:11,633 --> 00:47:14,087 facing the cold void of space. 665 00:47:18,286 --> 00:47:21,155 These planets are witnesses 666 00:47:21,197 --> 00:47:24,044 to much of the life of the universe. 667 00:47:24,075 --> 00:47:26,563 They were born near the start, 668 00:47:26,602 --> 00:47:30,496 and they will survive to near the end of the age of stars. 669 00:47:30,728 --> 00:47:32,800 ♪♪ 670 00:47:32,838 --> 00:47:38,782 They will see entire galaxies merge, 671 00:47:38,820 --> 00:47:42,561 and eventually begin to fade in their night skies. 672 00:47:42,593 --> 00:47:45,211 ♪♪ 673 00:47:45,248 --> 00:47:49,240 They watch as countless stars come and go. 674 00:47:53,372 --> 00:47:56,241 Bearing witness to the time, 675 00:47:56,282 --> 00:47:58,802 about five billion years from now, 676 00:47:58,841 --> 00:48:03,727 when a distant star begins to fade... 677 00:48:06,356 --> 00:48:11,144 And vanishes from the night sky 678 00:48:11,187 --> 00:48:18,701 as our sun finally exhausts its fuel and disappears forever. 679 00:48:30,793 --> 00:48:35,134 Ultimately, once the fusion process is over in the sun, 680 00:48:35,174 --> 00:48:37,508 it will begin to expand 681 00:48:37,541 --> 00:48:40,889 into what astronomers call a red giant, 682 00:48:40,931 --> 00:48:46,079 and the outer envelope of the sun will expand. 683 00:48:46,112 --> 00:48:48,894 It's going to gulp up some of the planets around it. 684 00:48:52,412 --> 00:48:53,787 Unfortunately, Earth is one of them. 685 00:48:56,506 --> 00:49:02,036 And as the sun dies, so too will many others like it. 686 00:49:02,072 --> 00:49:07,853 The age of stellar creation in the universe is waning. 687 00:49:07,893 --> 00:49:09,772 The universe is like a slow-motion fireworks show. 688 00:49:11,602 --> 00:49:14,024 And we're kind of watching the end of it. 689 00:49:14,066 --> 00:49:21,646 ♪♪ 690 00:49:23,628 --> 00:49:26,116 It's unlikely that Trappist 1 691 00:49:26,155 --> 00:49:28,391 will be the very last star in the universe. 692 00:49:31,976 --> 00:49:35,837 But we do believe the last star will be a red dwarf. 693 00:49:39,781 --> 00:49:42,780 ♪♪ 694 00:49:42,818 --> 00:49:47,192 As its fuel runs out, 695 00:49:47,232 --> 00:49:50,079 fusion comes to an end. 696 00:49:50,846 --> 00:49:56,059 ♪♪ 697 00:49:56,092 --> 00:49:59,637 The last star 698 00:49:59,674 --> 00:50:03,829 slowly cools, 699 00:50:03,864 --> 00:50:06,798 and fades away. 700 00:50:10,452 --> 00:50:15,982 ♪♪ 701 00:50:21,198 --> 00:50:25,507 With its passing, 702 00:50:25,548 --> 00:50:30,216 the universe becomes cold and dark. 703 00:50:34,504 --> 00:50:40,218 Without light and, most likely, 704 00:50:40,261 --> 00:50:41,755 without life. 705 00:50:58,363 --> 00:51:01,046 When the last red dwarf stars die out, 706 00:51:01,082 --> 00:51:05,336 that will be the end of stars in the universe. 707 00:51:05,368 --> 00:51:08,237 And it was starlight 708 00:51:08,278 --> 00:51:09,522 that really lit up its story. 709 00:51:09,557 --> 00:51:13,550 ♪♪ 710 00:51:13,587 --> 00:51:19,149 A universe without light may be unfathomable to us humans. 711 00:51:19,184 --> 00:51:22,085 Stars made us and our planet. 712 00:51:25,005 --> 00:51:29,793 They define the universe as we know it today. 713 00:51:29,834 --> 00:51:33,608 It was like a gift given to humanity, 714 00:51:33,641 --> 00:51:36,062 that it took a cosmos to make you. 715 00:51:36,103 --> 00:51:41,284 ♪♪ 716 00:51:41,317 --> 00:51:46,017 A cosmos eventually defined more by darkness than by light. 717 00:51:48,129 --> 00:51:54,357 But for now, we exist and learn and grow 718 00:51:54,590 --> 00:51:57,556 as tiny sparks within the bright 719 00:51:57,596 --> 00:52:01,937 and light-filled childhood of our universe. 720 00:52:01,978 --> 00:52:04,879 We live in "The Age of Stars." 53001

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