1 00:00:01,400 --> 00:00:04,733 ♪ ♪ 2 00:00:04,766 --> 00:00:11,633 NARRATOR: In a universe that shines with innumerable stars, 3 00:00:11,666 --> 00:00:14,266 {\an1}born from countless more stars 4 00:00:14,300 --> 00:00:19,633 that have come and gone before them, 5 00:00:19,666 --> 00:00:26,166 {\an1}rages the life-giving fire of our sun. 6 00:00:26,200 --> 00:00:27,533 {\an1}The sun is the king of the solar system. 7 00:00:27,566 --> 00:00:31,766 {\an1}It has essentially all the mass and all the energy. 8 00:00:31,800 --> 00:00:36,400 NARRATOR: Familiar and yet unknown. 9 00:00:36,433 --> 00:00:38,300 {\an1}Even though we've looked at it for a really long time, 10 00:00:38,333 --> 00:00:42,533 {\an1}the sun is still full of mysteries. 11 00:00:42,566 --> 00:00:46,233 {\an1}Why is it hotter in its atmosphere than on its surface? 12 00:00:46,266 --> 00:00:48,433 {\an1}What drives the solar wind? 13 00:00:48,466 --> 00:00:51,966 (clanging) 14 00:00:52,000 --> 00:00:55,566 {\an8}NARRATOR: Only now we take our first steps closer 15 00:00:55,600 --> 00:00:58,500 {\an7}to understanding our star... 16 00:00:58,533 --> 00:01:00,200 {\an8}KELLY KORRECK: It is the first time 17 00:01:00,233 --> 00:01:02,366 {\an1}that we're actually going in to touch the sun. 18 00:01:04,033 --> 00:01:05,300 GRANT TREMBLAY: And it's already really started 19 00:01:05,333 --> 00:01:06,800 {\an1}to truly transform our understanding 20 00:01:06,833 --> 00:01:07,833 {\an1}for how the sun works. 21 00:01:07,866 --> 00:01:09,233 (eruption) 22 00:01:09,266 --> 00:01:14,766 NARRATOR: ...Uncovering the secret power of all stars... 23 00:01:14,800 --> 00:01:20,133 RANA EZZEDDINE: As you can imagine, when you have a huge blob of flaming gas, 24 00:01:20,166 --> 00:01:22,333 {\an1}the core is usually the hottest. 25 00:01:23,766 --> 00:01:26,000 {\an1}And it is where the magic is happening. 26 00:01:26,033 --> 00:01:29,233 NARRATOR: ...Perhaps even finding clues 27 00:01:29,266 --> 00:01:31,800 {\an1}to the stars that came before it... 28 00:01:31,833 --> 00:01:33,000 PAYEL DAS: If we understand where the sun comes from, 29 00:01:33,033 --> 00:01:34,800 {\an1}we can understand a little bit more 30 00:01:34,833 --> 00:01:35,966 {\an1}about where life has come from. 31 00:01:37,533 --> 00:01:40,833 NARRATOR: ...And, ultimately, its fate. 32 00:01:40,866 --> 00:01:44,933 RAMAN PRINJA: It has about another 4.6 billion years of nuclear fusion left. 33 00:01:44,966 --> 00:01:47,733 {\an1}And then it will start to change. 34 00:01:47,766 --> 00:01:49,300 {\an1}It will start to evolve. 35 00:01:49,333 --> 00:01:51,133 GHINA HALABI: We really need to understand 36 00:01:51,166 --> 00:01:53,500 {\an1}what will happen to our own sun, 37 00:01:53,533 --> 00:01:58,133 {\an1}because that will impact Earth. 38 00:01:58,166 --> 00:01:59,833 NARRATOR: The sun is just one among 39 00:01:59,866 --> 00:02:07,066 {\an1}hundreds of billions of stars in a galaxy among trillions. 40 00:02:07,100 --> 00:02:09,433 ♪ ♪ 41 00:02:09,466 --> 00:02:14,000 {\an1}We live in "The Age of Stars." 42 00:02:14,033 --> 00:02:16,166 {\an1}Right now, on "NOVA." 43 00:02:16,200 --> 00:02:20,800 ♪ ♪ 44 00:02:38,066 --> 00:02:40,600 FOALS: ♪ See me when I float like a dove ♪ 45 00:02:40,633 --> 00:02:44,066 {\an1}♪ The skies above are lined with trees ♪ 46 00:02:44,100 --> 00:02:47,533 {\an1}♪ I'm on my knees, begging please ♪ 47 00:02:47,566 --> 00:02:54,900 {\an1}♪ Come and take me away ♪ 48 00:03:03,033 --> 00:03:07,800 ♪ ♪ 49 00:03:12,266 --> 00:03:16,066 NARRATOR: 93 million miles from Earth, 50 00:03:16,100 --> 00:03:19,466 {\an1}our nearest star, the sun. 51 00:03:19,500 --> 00:03:23,966 ♪ ♪ 52 00:03:27,200 --> 00:03:31,000 {\an1}A permanent fixture for life on our planet. 53 00:03:35,633 --> 00:03:38,233 KORRECK: Humans have always been fascinated by the sun. 54 00:03:38,266 --> 00:03:40,200 {\an8}I think because it is so constant 55 00:03:40,233 --> 00:03:43,000 {\an1}compared to our daily life. 56 00:03:43,033 --> 00:03:45,600 ♪ ♪ 57 00:03:45,633 --> 00:03:48,966 NIA IMARA: It's been rising and setting since the day that we were born. 58 00:03:49,000 --> 00:03:52,900 {\an1}We keep time by it, we keep our calendars by it. 59 00:03:52,933 --> 00:03:55,933 {\an7}Without it, life wouldn't be possible here on Earth. 60 00:03:55,966 --> 00:03:58,500 ♪ ♪ 61 00:03:58,533 --> 00:04:00,733 NARRATOR: The sun is just one of more than 62 00:04:00,766 --> 00:04:05,600 {\an1}a billion trillion stars in the universe. 63 00:04:05,633 --> 00:04:10,933 {\an1}Why is it around our star that life has emerged? 64 00:04:10,966 --> 00:04:13,500 ANJALI TRIPATHI: We want to know where do we come from, 65 00:04:13,533 --> 00:04:15,566 {\an7}and what are our cosmic origins. 66 00:04:17,166 --> 00:04:19,266 DAS: If we understand where the sun comes from, 67 00:04:19,300 --> 00:04:21,066 {\an7}we can understand a little bit more 68 00:04:21,100 --> 00:04:22,166 {\an7}about where life has come from. 69 00:04:24,033 --> 00:04:27,100 NARRATOR: But our star is an enigma. 70 00:04:28,800 --> 00:04:31,633 CHAPMAN: The sun is still full of mysteries. 71 00:04:31,666 --> 00:04:34,700 {\an7}Why is it hotter in its atmosphere than on its surface? 72 00:04:34,733 --> 00:04:38,100 {\an1}What drives the solar wind? 73 00:04:38,133 --> 00:04:42,133 NARRATOR: We've spent millennia studying from afar. 74 00:04:42,166 --> 00:04:45,733 {\an1}But only now are we getting close enough 75 00:04:45,766 --> 00:04:50,533 {\an1}to truly reveal its secrets. 76 00:04:52,966 --> 00:04:57,666 {\an8}♪ ♪ 77 00:04:57,700 --> 00:04:59,166 {\an1}The sun's not a very nice environment. 78 00:04:59,200 --> 00:05:02,166 (explosion) 79 00:05:02,200 --> 00:05:03,733 {\an1}It's not easy to get up close to the sun. 80 00:05:03,766 --> 00:05:07,600 ♪ ♪ 81 00:05:07,633 --> 00:05:10,200 BASRI: It's an enormous ball of hydrogen, 82 00:05:10,233 --> 00:05:12,633 {\an7}and it's putting out a tremendous amount of energy. 83 00:05:14,800 --> 00:05:19,233 NARRATOR: Its surface is a bubbling caldron of 10,000-degree plasma. 84 00:05:19,266 --> 00:05:23,500 PRINJA: We can actually see cells of hot gas 85 00:05:23,533 --> 00:05:25,900 {\an7}rising and falling, it's incredible imagery. 86 00:05:25,933 --> 00:05:28,533 {\an1}And then above that, you have this 87 00:05:28,566 --> 00:05:30,266 {\an1}very thin atmosphere that's a million degrees. 88 00:05:30,300 --> 00:05:32,933 Super hot. 89 00:05:32,966 --> 00:05:36,200 CHAPMAN: Seeing these images is like revealing something 90 00:05:36,233 --> 00:05:39,533 {\an1}that's been right in front of us, but hidden for so long. 91 00:05:39,566 --> 00:05:43,200 {\an1}Occasionally you might see this enormous coronal mass ejection 92 00:05:43,233 --> 00:05:46,700 {\an1}erupting from the star. 93 00:05:48,833 --> 00:05:52,200 NARRATOR: We now stand on the threshold 94 00:05:52,233 --> 00:05:54,400 {\an1}of being able to survive a close encounter. 95 00:05:54,433 --> 00:05:56,533 ♪ ♪ 96 00:05:56,566 --> 00:05:59,666 {\an1}With a new heat-resistant probe 97 00:05:59,700 --> 00:06:01,966 that's giving us an up-close look 98 00:06:02,000 --> 00:06:04,766 {\an1}at our sun for the first time. 99 00:06:05,633 --> 00:06:06,900 {\an1}MAN (over radio): Status check. 100 00:06:06,933 --> 00:06:08,166 {\an1}MAN (over radio): Go Delta. 101 00:06:08,200 --> 00:06:09,933 {\an1}MAN (over radio): Go PSP. 102 00:06:09,966 --> 00:06:11,300 {\an1}MAN (over radio): Minus 15. 103 00:06:11,333 --> 00:06:12,866 KORRECK: Launch night, 104 00:06:12,900 --> 00:06:14,066 {\an1}I was sick to my stomach. 105 00:06:14,100 --> 00:06:16,100 {\an1}MAN (over radio): Five, four, 106 00:06:16,133 --> 00:06:21,066 {\an1}three, two, one, zero. 107 00:06:21,100 --> 00:06:22,366 Lift off, 108 00:06:22,400 --> 00:06:25,466 {\an1}of the mighty Delta 4 heavy rocket with NASA's 109 00:06:25,500 --> 00:06:27,200 {\an7}Parker Solar Probe. (cheers and applause) 110 00:06:27,233 --> 00:06:29,200 {\an8}There we go. 111 00:06:31,833 --> 00:06:35,266 KORRECK: The Delta 4 heavy is a very slow rocket 112 00:06:35,300 --> 00:06:37,700 {\an1}compared to the other launches I've seen. 113 00:06:37,733 --> 00:06:39,233 {\an1}So I just saw fireballs, 114 00:06:39,266 --> 00:06:41,866 (chuckling): and was very, very frightened for a while. 115 00:06:41,900 --> 00:06:44,033 {\an1}MAN (over radio): 25 seconds into flight. 116 00:06:44,066 --> 00:06:47,500 CHRIS CHEN: It is quite scary to think about all that power in the rocket 117 00:06:47,533 --> 00:06:49,366 {\an7}underneath that, you know, 118 00:06:49,400 --> 00:06:50,933 {\an7}relatively small spacecraft sitting on top. 119 00:06:50,966 --> 00:06:54,300 {\an1}MAN (over radio): ...continue to look good on all three boosters. 120 00:06:54,333 --> 00:06:56,733 KORRECK: Then realizing that this was all okay 121 00:06:56,766 --> 00:06:59,500 {\an1}as it slowly made its way up into the sky. 122 00:06:59,533 --> 00:07:03,066 {\an1}MAN (over radio): Now 50 seconds into flight. 123 00:07:08,033 --> 00:07:11,433 (over radio): And we have jettisoned both strap-on boosters. 124 00:07:11,466 --> 00:07:15,100 TREMBLAY: Parker is just an exquisite mission. 125 00:07:15,133 --> 00:07:18,100 {\an7}It will be the closest that our species has thus far come 126 00:07:18,133 --> 00:07:20,033 {\an7}to literally touching the sun itself. 127 00:07:20,066 --> 00:07:24,366 ♪ ♪ 128 00:07:30,800 --> 00:07:33,666 NARRATOR: The Parker Solar Probe is traveling to a place 129 00:07:33,700 --> 00:07:38,833 {\an1}that has been completely unexplored up close. 130 00:07:44,466 --> 00:07:47,333 (clanging) 131 00:07:47,366 --> 00:07:50,100 {\an8}Until now. 132 00:07:51,666 --> 00:07:55,233 {\an8}♪ ♪ 133 00:07:56,600 --> 00:08:00,166 {\an7}MAN (over radio, echoing): NASA's Parker Solar Probe, 134 00:08:00,200 --> 00:08:02,233 {\an1}a daring mission to shed light 135 00:08:02,266 --> 00:08:07,366 on the mysteries of our closest star. 136 00:08:16,400 --> 00:08:22,900 {\an8}PARKER: This is a journey into Never-Never Land, you might say. 137 00:08:25,266 --> 00:08:27,966 NARRATOR: During its seven year mission, 138 00:08:28,000 --> 00:08:31,600 {\an1}the Parker Solar Probe will attempt a series of dives 139 00:08:31,633 --> 00:08:34,666 {\an1}towards the surface of the sun. 140 00:08:36,000 --> 00:08:40,900 {\an1}Its goal is to understand how the sun sheds its energy. 141 00:08:40,933 --> 00:08:44,600 ♪ ♪ 142 00:08:44,633 --> 00:08:48,733 {\an1}Orbiting a total of 24 times... 143 00:08:52,600 --> 00:08:56,866 {\an1}Each pass taking it perilously closer. 144 00:08:56,900 --> 00:09:02,266 ♪ ♪ 145 00:09:02,300 --> 00:09:06,666 {\an1}So close it will enter the sun's atmosphere. 146 00:09:06,700 --> 00:09:10,700 ♪ ♪ 147 00:09:10,733 --> 00:09:16,200 {\an1}Braving temperatures no spacecraft has ever endured. 148 00:09:16,233 --> 00:09:22,000 ♪ ♪ 149 00:09:24,566 --> 00:09:26,633 {\an1}And traveling faster 150 00:09:26,666 --> 00:09:29,766 {\an1}than any other human-made object has before. 151 00:09:29,800 --> 00:09:34,066 ♪ ♪ 152 00:09:34,100 --> 00:09:36,766 {\an1}(whirring intensifies) 153 00:09:36,800 --> 00:09:41,433 ♪ ♪ 154 00:09:41,466 --> 00:09:46,433 {\an1}The mission is still in its early days. 155 00:09:46,466 --> 00:09:49,766 {\an1}But in the coming years, the Parker Solar Probe 156 00:09:49,800 --> 00:09:55,500 {\an1}will help us unlock not only the secrets of our own sun 157 00:09:55,533 --> 00:09:58,633 but all stars. 158 00:09:58,666 --> 00:10:05,600 {\an1}Including those that hold the key to the sun's origins, 159 00:10:05,633 --> 00:10:07,166 and our own. 160 00:10:07,200 --> 00:10:09,366 ♪ ♪ 161 00:10:09,400 --> 00:10:13,066 CHAPMAN: We can look at the processes, look at what's inside the sun, 162 00:10:13,100 --> 00:10:16,366 {\an1}and understand how it had to become that. 163 00:10:16,400 --> 00:10:19,200 {\an1}What were the generations of stars before that? 164 00:10:19,233 --> 00:10:21,066 {\an1}What was its ancestry? 165 00:10:25,433 --> 00:10:29,166 ♪ ♪ 166 00:10:31,566 --> 00:10:34,900 NARRATOR: The sun's story can be traced back 167 00:10:34,933 --> 00:10:39,066 {\an1}to its most distant stellar ancestors, 168 00:10:39,100 --> 00:10:43,233 {\an1}the very first stars in the universe. 169 00:10:51,800 --> 00:10:56,800 {\an1}Almost 100 million years after the Big Bang, 170 00:10:56,833 --> 00:11:01,833 {\an1}the universe is dark and cold-- 171 00:11:01,866 --> 00:11:06,800 {\an1}not a single star shining. 172 00:11:06,833 --> 00:11:11,300 {\an1}But this universe is far from empty. 173 00:11:11,333 --> 00:11:13,700 ♪ ♪ 174 00:11:13,733 --> 00:11:17,333 {\an1}Something is growing in the void. 175 00:11:19,833 --> 00:11:22,900 {\an1}Stretching out tendrils. 176 00:11:25,300 --> 00:11:29,333 TRIPATHI: The early universe was largely hydrogen and helium, 177 00:11:29,366 --> 00:11:32,066 {\an1}and only small amounts of other materials. 178 00:11:34,033 --> 00:11:37,100 HALABI: None of the elements we see these days, 179 00:11:37,133 --> 00:11:40,833 {\an7}no carbon, oxygen, iron, none of that. 180 00:11:43,733 --> 00:11:46,266 SOWNAK BOSE: Even though the name "the Cosmic Dark Ages" 181 00:11:46,300 --> 00:11:48,300 {\an1}suggests that there might not have been 182 00:11:48,333 --> 00:11:51,466 {\an1}anything particularly interesting going on, 183 00:11:51,500 --> 00:11:53,600 {\an7}it was really kind of laying the groundwork 184 00:11:53,633 --> 00:11:56,033 {\an7}for the construction of 185 00:11:56,066 --> 00:11:58,400 the cosmic web. 186 00:11:59,766 --> 00:12:01,500 TREMBLAY: The cosmic web is literally 187 00:12:01,533 --> 00:12:03,600 {\an1}the structure of the universe itself. 188 00:12:03,633 --> 00:12:07,000 {\an8}♪ ♪ 189 00:12:15,800 --> 00:12:21,000 NARRATOR: The cosmic web is unimaginable in scale. 190 00:12:21,033 --> 00:12:25,366 {\an1}Huge clouds of gas are drawn together 191 00:12:25,400 --> 00:12:30,400 {\an1}by the gravity of a mysterious, invisible form of matter 192 00:12:30,433 --> 00:12:34,000 {\an1}called dark matter, 193 00:12:34,033 --> 00:12:37,433 {\an1}creating a great network of filaments. 194 00:12:39,733 --> 00:12:43,700 {\an1}A web the size of the cosmos. 195 00:12:43,733 --> 00:12:49,966 ♪ ♪ 196 00:12:52,166 --> 00:12:54,400 {\an1}The gas in these tendrils 197 00:12:54,433 --> 00:12:58,700 {\an1}is made up of mostly hydrogen and helium. 198 00:12:58,733 --> 00:13:05,566 ♪ ♪ 199 00:13:05,600 --> 00:13:07,900 {\an1}Where these great filaments cross 200 00:13:07,933 --> 00:13:13,733 {\an1}are the places where the first stars will one day be born. 201 00:13:14,533 --> 00:13:17,266 ♪ ♪ 202 00:13:17,300 --> 00:13:22,033 (birds chirping) 203 00:13:24,333 --> 00:13:27,700 {\an1}The cosmic web has been shaping our universe 204 00:13:27,733 --> 00:13:30,333 {\an1}for 13.8 billion years. 205 00:13:32,333 --> 00:13:36,033 {\an1}And it's still doing so today. 206 00:13:36,066 --> 00:13:38,966 {\an1}But it's only recently 207 00:13:39,000 --> 00:13:44,766 {\an1}that we've actually been able to see it. 208 00:13:44,800 --> 00:13:47,366 {\an7}The image that we have here is absolutely amazing. 209 00:13:47,400 --> 00:13:49,133 {\an1}It's one of the most fundamental pictures 210 00:13:49,166 --> 00:13:51,366 that we can take in our universe. 211 00:13:51,400 --> 00:13:52,633 {\an1}And it's actually a direct image 212 00:13:52,666 --> 00:13:54,733 {\an1}of some of the largest structures that exist, 213 00:13:54,766 --> 00:13:56,600 {\an1}the filaments of the cosmic web. 214 00:13:56,633 --> 00:13:59,200 {\an1}Now the bright dots that you see over here, 215 00:13:59,233 --> 00:14:00,900 {\an1}they're entire galaxies. 216 00:14:00,933 --> 00:14:02,800 {\an1}Now, if I take those away, 217 00:14:02,833 --> 00:14:04,200 {\an1}what you can see much more clearly 218 00:14:04,233 --> 00:14:06,533 {\an1}is the faint glow of the hydrogen and helium 219 00:14:06,566 --> 00:14:09,066 {\an1}that exists on the tendrils of the cosmic web. 220 00:14:09,100 --> 00:14:10,733 {\an1}And it's on this cosmic web, 221 00:14:10,766 --> 00:14:12,000 {\an1}that the story of our sun 222 00:14:12,033 --> 00:14:15,733 and the stars in the night sky begins. 223 00:14:15,766 --> 00:14:21,300 ♪ ♪ 224 00:14:31,733 --> 00:14:35,166 NARRATOR: As time passes in the early universe, 225 00:14:35,200 --> 00:14:38,266 {\an1}the cosmic web continues to grow... 226 00:14:41,433 --> 00:14:45,333 {\an1}Gas, rushing along these great tendrils, 227 00:14:45,366 --> 00:14:49,566 {\an1}traveling down towards the intersections. 228 00:14:51,700 --> 00:14:55,033 {\an7}It is being pulled to these points by gravity. 229 00:14:58,800 --> 00:15:05,666 {\an7}And as more gas joins, this force becomes ever stronger, 230 00:15:05,700 --> 00:15:09,900 {\an1}creating great clouds staggering in size. 231 00:15:12,266 --> 00:15:16,100 {\an7}They grow denser, 232 00:15:16,133 --> 00:15:18,866 {\an8}hotter, 233 00:15:18,900 --> 00:15:22,833 {\an7}as gas is relentlessly added 234 00:15:22,866 --> 00:15:28,866 {\an7}until, at last, the conditions become so extreme 235 00:15:28,900 --> 00:15:31,966 {\an7}that there is a sudden moment of ignition. 236 00:15:32,000 --> 00:15:39,433 {\an8}♪ ♪ 237 00:15:39,466 --> 00:15:43,966 {\an7}The birth of the very first star in the universe. 238 00:15:44,000 --> 00:15:45,966 ♪ ♪ 239 00:15:46,000 --> 00:15:49,966 {\an1}Born 17 times hotter than the sun. 240 00:15:50,000 --> 00:15:56,233 ♪ ♪ 241 00:15:56,266 --> 00:15:59,600 {\an1}This star is a blue monster. 242 00:15:59,633 --> 00:16:04,933 ♪ ♪ 243 00:16:17,933 --> 00:16:22,200 ♪ ♪ 244 00:16:30,466 --> 00:16:31,633 CHAPMAN: The first stars 245 00:16:31,666 --> 00:16:35,233 {\an7}were unlike anything we can see around us today, 246 00:16:35,266 --> 00:16:38,466 {\an1}which is what makes them so incredible. 247 00:16:38,500 --> 00:16:41,366 {\an1}COURTNEY DRESSING: When the very first stars formed, 248 00:16:41,400 --> 00:16:43,733 {\an7}these stars ended up with giant masses 249 00:16:43,766 --> 00:16:46,300 {\an7}of 500 to 600 times the mass of the sun. 250 00:16:48,466 --> 00:16:52,666 BASRI: Stars today are perhaps as hot as 100,000 degrees. 251 00:16:52,700 --> 00:16:55,433 {\an1}And these stars were nearly twice as hot as that. 252 00:16:55,466 --> 00:16:58,200 {\an7}And the very hot color tends to also make them look blue. 253 00:16:58,233 --> 00:17:01,200 ♪ ♪ 254 00:17:01,233 --> 00:17:04,700 NARRATOR: But this first star is not alone for long. 255 00:17:07,100 --> 00:17:10,833 At intersections across the cosmic web, 256 00:17:10,866 --> 00:17:14,866 {\an1}it's soon joined by others. 257 00:17:14,900 --> 00:17:19,566 ♪ ♪ 258 00:17:19,600 --> 00:17:23,833 {\an1}An entire generation of first stars... 259 00:17:28,233 --> 00:17:31,400 {\an1}lighting up the universe. 260 00:17:31,433 --> 00:17:35,466 ♪ ♪ 261 00:17:35,500 --> 00:17:37,766 {\an1}But this isn't all they do. 262 00:17:37,800 --> 00:17:43,700 ♪ ♪ 263 00:17:43,733 --> 00:17:47,766 {\an1}These stars are also forging new elements, 264 00:17:47,800 --> 00:17:52,966 {\an1}creating the ingredients for all the planets 265 00:17:53,000 --> 00:17:57,200 and, ultimately, even for life to exist. 266 00:17:57,233 --> 00:17:59,266 (birds chirping) 267 00:17:59,300 --> 00:18:00,766 DAS: The birth of the first stars 268 00:18:00,800 --> 00:18:02,500 {\an1}signaled a complete transformation 269 00:18:02,533 --> 00:18:04,600 {\an1}in the makeup of the universe. 270 00:18:04,633 --> 00:18:08,400 {\an1}Before they existed, all we had was hydrogen and helium, 271 00:18:08,433 --> 00:18:12,100 {\an1}but nuclear fusion completely changed all of that. 272 00:18:12,133 --> 00:18:16,233 NARRATOR: The cores of the first stars were so hot, 273 00:18:16,266 --> 00:18:20,000 {\an1}they reached more than 100 million degrees. 274 00:18:20,033 --> 00:18:23,800 {\an1}And that forced hydrogen atoms to change. 275 00:18:23,833 --> 00:18:26,066 DAS: Now under the very high temperatures and pressures 276 00:18:26,100 --> 00:18:28,266 {\an1}that you find in the cores of these stars, 277 00:18:28,300 --> 00:18:29,366 {\an1}they were smashed together, 278 00:18:29,400 --> 00:18:32,433 {\an1}fusing a heavier element, helium. 279 00:18:32,466 --> 00:18:35,833 NARRATOR: But the first stars didn't stop there. 280 00:18:35,866 --> 00:18:37,900 DAS: After a few million years, 281 00:18:37,933 --> 00:18:40,233 {\an1}the hydrogen completely runs out. 282 00:18:40,266 --> 00:18:43,600 {\an1}So instead, the helium atoms are forced to be smashed together, 283 00:18:43,633 --> 00:18:45,166 {\an1}creating even heavier elements, 284 00:18:45,200 --> 00:18:50,333 {\an1}such as carbon, oxygen, and iron. 285 00:18:50,366 --> 00:18:53,600 NARRATOR: The new elements these first stars forged 286 00:18:53,633 --> 00:18:59,300 {\an1}are the elements that seed other types of stars, planets, 287 00:18:59,333 --> 00:19:01,333 and even us. 288 00:19:01,366 --> 00:19:03,700 ♪ ♪ 289 00:19:03,733 --> 00:19:08,000 In other words, the elements for life. 290 00:19:10,733 --> 00:19:15,433 {\an1}But the era of blue giants can't last. 291 00:19:17,733 --> 00:19:19,833 ANJALI: Fusion at the center of a star 292 00:19:19,866 --> 00:19:22,466 {\an1}eventually ends as it runs out of fuel, 293 00:19:22,500 --> 00:19:24,633 {\an1}so the process can't go on forever. 294 00:19:24,666 --> 00:19:27,200 ♪ ♪ 295 00:19:27,233 --> 00:19:29,033 CHAPMAN: When fusion stops, 296 00:19:29,066 --> 00:19:32,733 {\an1}you lose that internal pressure which pushes against gravity. 297 00:19:32,766 --> 00:19:34,766 {\an1}You lose a tug of war, 298 00:19:34,800 --> 00:19:37,633 {\an1}and the gravity starts to push down on the star. 299 00:19:37,666 --> 00:19:41,700 ♪ ♪ 300 00:19:41,733 --> 00:19:44,233 TREMBLAY: You know that saying, "Live fast, die young"? 301 00:19:44,266 --> 00:19:46,600 {\an7}That really applies to stars, right? 302 00:19:46,633 --> 00:19:48,900 {\an7}So the most massive, luminous stars 303 00:19:48,933 --> 00:19:50,133 {\an7}have the shortest lifetimes. 304 00:19:50,166 --> 00:19:51,966 {\an7}Even though they have much more hydrogen fuel 305 00:19:52,000 --> 00:19:53,833 {\an7}than an ordinary star like our sun, 306 00:19:53,866 --> 00:19:56,933 {\an7}they burn it so quickly that they only live 307 00:19:56,966 --> 00:20:00,366 {\an1}a few million years before they burn out. 308 00:20:00,400 --> 00:20:03,100 {\an1}And a few million years, in astronomy time, 309 00:20:03,133 --> 00:20:05,866 {\an1}that's the blink of an eye. 310 00:20:08,300 --> 00:20:14,266 NARRATOR: With its fuel spent, fusion reactions stop. 311 00:20:17,066 --> 00:20:20,533 {\an1}And gravity takes over. 312 00:20:23,833 --> 00:20:29,466 ♪ ♪ 313 00:20:39,633 --> 00:20:43,066 (whooshing) 314 00:20:48,200 --> 00:20:51,400 {\an1}The core collapses. 315 00:20:53,200 --> 00:20:58,966 ♪ ♪ 316 00:20:59,000 --> 00:21:02,133 {\an1}Gas suddenly falls inwards. 317 00:21:05,433 --> 00:21:10,100 ♪ ♪ 318 00:21:14,700 --> 00:21:16,833 (explosion) 319 00:21:18,533 --> 00:21:22,733 {\an1}And then rebounds 320 00:21:22,766 --> 00:21:27,733 {\an1}in a colossal explosion called a supernova. 321 00:21:27,766 --> 00:21:31,866 ♪ ♪ 322 00:21:43,900 --> 00:21:45,666 (whooshing) 323 00:21:49,700 --> 00:21:52,100 {\an1}A shockwave of energy, 324 00:21:52,133 --> 00:21:58,833 {\an1}followed by material hurtling outwards into space. 325 00:22:04,166 --> 00:22:08,466 PRINJA: Supernovae explosions rocked the universe. 326 00:22:08,500 --> 00:22:10,966 {\an1}They are amongst the most explosive events 327 00:22:11,000 --> 00:22:12,666 {\an1}that we now know about. 328 00:22:12,700 --> 00:22:18,233 {\an7}Briefly, a single supernova can outshine an entire galaxy. 329 00:22:19,966 --> 00:22:24,366 EZZEDDINE: This was a very important moment in the history of the universe. 330 00:22:24,400 --> 00:22:28,166 {\an7}It allowed the universe to kind of start evolving. 331 00:22:29,800 --> 00:22:32,566 HALABI: After the first stars exploded, 332 00:22:32,600 --> 00:22:35,966 {\an1}the material that has been forged in their interiors 333 00:22:36,000 --> 00:22:38,833 {\an7}was spewn out into space. 334 00:22:38,866 --> 00:22:43,866 IMARA: They seeded the universe with these heavy elements 335 00:22:43,900 --> 00:22:47,433 {\an1}and paved the way for subsequent generations of stars. 336 00:22:51,700 --> 00:22:56,933 {\an8}NARRATOR: Generations of stars that we can see in the night sky. 337 00:22:59,766 --> 00:23:01,600 {\an1}The Hubble Space Telescope 338 00:23:01,633 --> 00:23:05,133 {\an1}has been studying them for more than 30 years. 339 00:23:05,900 --> 00:23:09,266 {\an8}♪ ♪ 340 00:23:12,333 --> 00:23:18,333 {\an7}Showing us this epic cycle of cosmic death and renewal. 341 00:23:19,833 --> 00:23:22,966 {\an8}♪ ♪ 342 00:23:23,000 --> 00:23:26,966 {\an8}CHAPMAN: Its not only the first stars which enriched the universe. 343 00:23:28,600 --> 00:23:30,866 {\an1}As you go on for the second, the third, 344 00:23:30,900 --> 00:23:33,033 {\an1}the fourth generation of stars, 345 00:23:33,066 --> 00:23:35,266 {\an1}they're all creating more and more heavy elements 346 00:23:35,300 --> 00:23:37,700 {\an1}which get expelled into the universe. 347 00:23:37,733 --> 00:23:44,500 {\an8}♪ ♪ 348 00:23:48,500 --> 00:23:53,200 NARRATOR: Hubble reveals to us how stars have evolved 349 00:23:53,233 --> 00:23:58,033 {\an1}from a primitive universe dominated by blue stars 350 00:23:58,066 --> 00:24:01,700 {\an1}to our universe today, 351 00:24:01,733 --> 00:24:08,066 {\an1}populated by stars of every color, size, and configuration. 352 00:24:08,100 --> 00:24:11,200 ♪ ♪ 353 00:24:11,233 --> 00:24:13,333 Neutron stars 354 00:24:13,366 --> 00:24:18,900 {\an1}violently spinning up to 700 times a second, 355 00:24:18,933 --> 00:24:21,800 {\an1}spitting out jets of radiation. 356 00:24:27,266 --> 00:24:29,366 {\an8}Stars so huge, 357 00:24:31,000 --> 00:24:34,900 {\an7}that more than a billion suns could fit inside them. 358 00:24:37,033 --> 00:24:38,400 DRESSING: There are many types of stars. 359 00:24:38,433 --> 00:24:42,933 {\an1}Wolf-Rayet stars, red giant stars, white dwarf stars. 360 00:24:42,966 --> 00:24:45,800 {\an1}All of them have their own unique characteristics. 361 00:24:45,833 --> 00:24:50,233 {\an8}♪ ♪ 362 00:24:50,266 --> 00:24:53,166 NARRATOR: And some that aren't alone. 363 00:24:55,133 --> 00:24:59,133 {\an1}They are kept company by systems of planets, 364 00:24:59,166 --> 00:25:04,166 {\an1}including rocky worlds built of ingredients 365 00:25:04,200 --> 00:25:08,166 {\an1}like carbon, silicon, and iron. 366 00:25:14,600 --> 00:25:16,133 {\an1}So stars really are the engines 367 00:25:16,166 --> 00:25:18,500 {\an1}of higher-order complexity in the universe, right? 368 00:25:18,533 --> 00:25:21,600 {\an1}They're the factories that make up the heavier elements 369 00:25:21,633 --> 00:25:23,300 {\an1}that are the seeds of things 370 00:25:23,333 --> 00:25:25,833 {\an8}like planets. 371 00:25:27,566 --> 00:25:31,733 {\an8}NARRATOR: Stars have changed the entirety of the universe, 372 00:25:31,766 --> 00:25:37,200 {\an7}filling it with all manner of wondrous celestial objects, 373 00:25:37,233 --> 00:25:40,266 {\an7}and ultimately paving the way for a star 374 00:25:40,300 --> 00:25:46,366 {\an8}that has all the right conditions to make us. 375 00:25:46,400 --> 00:25:50,333 {\an8}PRINJA: The sun must have relied on many, many generations 376 00:25:50,366 --> 00:25:52,633 {\an7}of previous stars for the material 377 00:25:52,666 --> 00:25:54,633 {\an7}that's there today in our solar system. 378 00:25:54,666 --> 00:25:56,433 {\an1}Probably thousands of other stars 379 00:25:56,466 --> 00:25:57,633 {\an1}that would have had to explode. 380 00:25:57,666 --> 00:26:03,200 ♪ ♪ 381 00:26:10,300 --> 00:26:14,900 NARRATOR: Nine billion years after the birth of the first star. 382 00:26:17,400 --> 00:26:20,066 {\an1}The universe has been enriched 383 00:26:20,100 --> 00:26:23,666 {\an1}with dozens of new elements. 384 00:26:23,700 --> 00:26:28,666 {\an1}(rumbling and crackling) 385 00:26:28,700 --> 00:26:33,033 {\an1}Here, gravity draws one cloud together 386 00:26:33,066 --> 00:26:38,133 {\an1}and our own star is born. 387 00:26:40,433 --> 00:26:47,100 ♪ ♪ 388 00:26:50,433 --> 00:26:52,166 (booming) 389 00:26:52,200 --> 00:26:57,333 {\an1}But not all of the material is used to create the sun. 390 00:27:03,400 --> 00:27:06,733 ♪ ♪ 391 00:27:06,766 --> 00:27:10,300 {\an1}Some remains in orbit. 392 00:27:12,333 --> 00:27:14,900 {\an1}And it's from these leftovers 393 00:27:14,933 --> 00:27:21,366 {\an1}that eight extraordinary planets form our solar system. 394 00:27:22,533 --> 00:27:24,200 {\an1}The sun has a very tight relationship 395 00:27:24,233 --> 00:27:25,833 {\an1}with all the planets in the solar system. 396 00:27:27,300 --> 00:27:28,733 {\an1}Not just because of its enormous gravity, 397 00:27:28,766 --> 00:27:32,200 {\an1}but because of the light that it provides. 398 00:27:35,233 --> 00:27:39,600 {\an8}NARRATOR: Some of these worlds seem just too far away from the sun 399 00:27:39,633 --> 00:27:41,700 {\an7}for complex life to take hold. 400 00:27:45,166 --> 00:27:50,966 {\an1}Deprived of light, they may be devoid of any life at all. 401 00:27:53,433 --> 00:27:56,333 {\an8}♪ ♪ 402 00:27:58,966 --> 00:28:03,133 {\an1}These are the gas and ice giants. 403 00:28:03,166 --> 00:28:06,400 ♪ ♪ 404 00:28:08,000 --> 00:28:11,266 {\an7}In contrast, others are too close to the sun. 405 00:28:14,033 --> 00:28:16,666 {\an1}They are relentlessly blasted... 406 00:28:19,733 --> 00:28:23,333 {\an7}Until they become scorched deserts. 407 00:28:27,633 --> 00:28:30,466 {\an1}But there is a sweet spot. 408 00:28:30,500 --> 00:28:34,333 ♪ ♪ 409 00:28:34,366 --> 00:28:38,133 Neither too far nor too close to the sun. 410 00:28:42,766 --> 00:28:44,866 {\an1}It's in this place... 411 00:28:44,900 --> 00:28:48,766 (wind howling) 412 00:28:48,800 --> 00:28:49,733 {\an1}that the chemical legacy 413 00:28:49,766 --> 00:28:55,666 of generations of long-gone stars 414 00:28:55,700 --> 00:29:00,800 {\an1}would form something astonishing. 415 00:29:00,833 --> 00:29:05,400 {\an1}(thunder rumbling) 416 00:29:05,433 --> 00:29:07,266 KORRECK: We are, on the Earth, on kind of 417 00:29:07,300 --> 00:29:08,400 {\an1}this special, sweet zone. 418 00:29:08,433 --> 00:29:10,000 They call it the Goldilocks zone. 419 00:29:10,033 --> 00:29:13,766 PHILIP MUIRHEAD: This exciting distance from a star 420 00:29:13,800 --> 00:29:15,666 {\an7}where a planet could conceivably have 421 00:29:15,700 --> 00:29:17,366 {\an7}liquid water on its surface. 422 00:29:18,433 --> 00:29:21,266 HALABI: Water is the medium that facilitates 423 00:29:21,300 --> 00:29:23,366 {\an1}the biochemical reactions 424 00:29:23,400 --> 00:29:25,333 {\an1}that are responsible for life. 425 00:29:27,400 --> 00:29:29,100 CHAPMAN: Earth's relationship with the sun 426 00:29:29,133 --> 00:29:31,866 {\an7}is the most important relationship there is. 427 00:29:31,900 --> 00:29:37,400 ♪ ♪ 428 00:29:39,966 --> 00:29:44,633 {\an8}NARRATOR: The sun is constantly reaching out to our planet, 429 00:29:44,666 --> 00:29:49,400 {\an7}something the Parker Solar Probe is helping us understand. 430 00:29:52,133 --> 00:29:54,800 {\an7}What makes Parker so great is the fact that 431 00:29:54,833 --> 00:29:57,666 {\an7}it has a great set of instruments that work together 432 00:29:57,700 --> 00:30:00,966 {\an1}in order to look in all directions. 433 00:30:01,000 --> 00:30:04,633 TREMBLAY: So there's this sun-facing part of the probe 434 00:30:04,666 --> 00:30:06,233 {\an7}that peeks above the heat shield 435 00:30:06,266 --> 00:30:08,333 {\an7}and literally looks directly at the sun. 436 00:30:10,366 --> 00:30:14,200 NARRATOR: The Parker Solar Probe is spotting holes 437 00:30:14,233 --> 00:30:17,266 {\an1}in the sun's atmosphere-- 438 00:30:17,300 --> 00:30:19,500 {\an1}vents that release 439 00:30:19,533 --> 00:30:22,366 {\an1}a blizzard of charged particles 440 00:30:22,400 --> 00:30:25,233 {\an1}at more than a million miles an hour. 441 00:30:25,266 --> 00:30:29,566 {\an1}What we call the solar wind. 442 00:30:29,600 --> 00:30:32,133 {\an1}We can tell how the energy flows, 443 00:30:32,166 --> 00:30:33,833 {\an1}where the wind is coming off, 444 00:30:33,866 --> 00:30:36,100 {\an1}how much of the wind is coming off. 445 00:30:37,700 --> 00:30:41,700 NARRATOR: The solar wind travels billions of miles, 446 00:30:41,733 --> 00:30:46,066 {\an1}bombarding the planets with radiation. 447 00:30:47,033 --> 00:30:49,466 {\an1}The charged particles in the solar wind 448 00:30:49,500 --> 00:30:51,800 {\an1}can be detrimental to life. 449 00:30:51,833 --> 00:30:54,800 {\an1}On Earth, we're protected by the Earth's magnetic field, 450 00:30:54,833 --> 00:30:56,633 {\an1}which deflects the particles. 451 00:30:56,666 --> 00:30:58,833 {\an7}So it's kind of like we have our shields up, 452 00:30:58,866 --> 00:31:01,466 {\an7}and our shield is our magnetic field. 453 00:31:03,433 --> 00:31:07,033 NARRATOR: Earth has defenses that protect life 454 00:31:07,066 --> 00:31:10,133 {\an1}from our star's violent tendencies. 455 00:31:11,666 --> 00:31:13,733 {\an1}But the sun also provides 456 00:31:13,766 --> 00:31:16,166 {\an1}something essential to our planet. 457 00:31:16,200 --> 00:31:17,933 EZZEDDINE: At the core of it, 458 00:31:17,966 --> 00:31:21,866 {\an1}the sun is forging hydrogen into helium, 459 00:31:21,900 --> 00:31:24,100 {\an7}which is what is releasing the energy 460 00:31:24,133 --> 00:31:27,033 {\an1}that we get here on Earth. 461 00:31:27,066 --> 00:31:28,233 HALABI: The photons, 462 00:31:28,266 --> 00:31:31,966 {\an1}these packets of energy, when they are formed, 463 00:31:32,000 --> 00:31:34,666 {\an7}they don't go straight from the center 464 00:31:34,700 --> 00:31:37,000 {\an7}rushing through to the surface. 465 00:31:37,033 --> 00:31:39,233 {\an8}They go through a very bumpy ride. 466 00:31:39,266 --> 00:31:42,733 {\an1}They get tossed from one atom to the other. 467 00:31:42,766 --> 00:31:47,266 {\an1}They get absorbed and spit out, absorbed and spit out. 468 00:31:47,300 --> 00:31:50,900 {\an1}So it takes a really convoluted path out of that sun, 469 00:31:50,933 --> 00:31:52,766 and that can take millions of years. 470 00:31:54,333 --> 00:31:57,400 NARRATOR: Once these photons arrive at the surface, 471 00:31:57,433 --> 00:32:01,500 {\an1}they're liberated as sunshine. 472 00:32:01,533 --> 00:32:10,666 ♪ ♪ 473 00:32:12,633 --> 00:32:16,333 {\an1}The light races across the solar system. 474 00:32:17,500 --> 00:32:20,933 ♪ ♪ 475 00:32:20,966 --> 00:32:25,233 Unobstructed, it flashes past the planets 476 00:32:25,266 --> 00:32:29,833 {\an1}at 180,000 miles per second. 477 00:32:29,866 --> 00:32:33,833 BASRI: If you could take all the energy that humans are producing 478 00:32:33,866 --> 00:32:35,300 {\an1}and store it in batteries, 479 00:32:35,333 --> 00:32:38,133 {\an1}the entire civilization, for 50,000 years, 480 00:32:38,166 --> 00:32:42,233 {\an1}you could make the sun shine for one second. 481 00:32:42,833 --> 00:32:48,266 ♪ ♪ 482 00:32:48,300 --> 00:32:51,766 NARRATOR: It takes just over eight minutes 483 00:32:51,800 --> 00:32:54,700 {\an1}for the sun's light to reach Earth. 484 00:32:57,733 --> 00:33:02,533 {\an7}That stream of light is like an umbilical cord of energy 485 00:33:02,566 --> 00:33:04,900 {\an7}coming down to us here on the Earth. 486 00:33:04,933 --> 00:33:08,166 {\an1}And it's been pretty much constant and unbroken 487 00:33:08,200 --> 00:33:10,500 {\an1}for nearly five billion years. 488 00:33:10,533 --> 00:33:14,700 {\an1}And it's this combination of the stability of light, 489 00:33:14,733 --> 00:33:18,633 {\an1}stability of energy over billions of years, 490 00:33:18,666 --> 00:33:21,233 {\an1}that means complex life that we see around us 491 00:33:21,266 --> 00:33:23,833 {\an1}here on the Earth has been able to form 492 00:33:23,866 --> 00:33:26,400 {\an1}and has been able to thrive. 493 00:33:29,000 --> 00:33:33,833 ♪ ♪ 494 00:33:39,600 --> 00:33:43,433 ♪ ♪ 495 00:33:48,366 --> 00:33:52,766 NARRATOR: We don't know exactly how life emerges on early Earth. 496 00:33:57,633 --> 00:34:01,300 {\an1}But what we do know is that primitive cells, 497 00:34:01,333 --> 00:34:06,166 {\an1}living in the ocean, begin to use the sun's energy 498 00:34:06,200 --> 00:34:10,000 {\an1}to power life-giving chemical reactions. 499 00:34:10,533 --> 00:34:13,933 {\an8}♪ ♪ 500 00:34:13,966 --> 00:34:18,366 {\an7}These cells are the bridge between sun and Earth. 501 00:34:21,333 --> 00:34:25,400 {\an1}Tiny machines that harness the power of our star. 502 00:34:27,166 --> 00:34:32,100 {\an1}The cells use sunlight to turn carbon dioxide and water 503 00:34:32,133 --> 00:34:36,066 {\an1}into food in the form of sugar. 504 00:34:39,300 --> 00:34:42,166 {\an1}This process, photosynthesis, 505 00:34:42,200 --> 00:34:47,066 is a direct use of the sun's power. 506 00:34:47,100 --> 00:34:51,833 (birds chirping) 507 00:34:51,866 --> 00:34:54,466 ♪ ♪ 508 00:34:54,500 --> 00:34:59,166 {\an1}It has driven the evolution of complexity on Earth... 509 00:34:59,200 --> 00:35:04,233 ♪ ♪ 510 00:35:04,266 --> 00:35:06,366 {\an1}From primitive bacteria, 511 00:35:06,400 --> 00:35:10,000 {\an1}to plants and trees... 512 00:35:12,400 --> 00:35:16,200 {\an1}An unbroken line of living things. 513 00:35:17,700 --> 00:35:22,033 {\an1}All connected to the power source in the sky. 514 00:35:25,066 --> 00:35:28,966 HALABI: Everything from the little blade of grass 515 00:35:29,000 --> 00:35:31,166 {\an1}to the biggest oak tree, 516 00:35:31,200 --> 00:35:34,266 {\an1}they use the sunlight 517 00:35:34,300 --> 00:35:38,066 {\an1}to photosynthesize and produce the energy 518 00:35:38,100 --> 00:35:40,733 {\an1}that we later consume 519 00:35:40,766 --> 00:35:43,566 {\an1}to sustain ourselves. 520 00:35:43,600 --> 00:35:44,966 So in a way, 521 00:35:45,000 --> 00:35:48,200 {\an1}we have been feeding on starlight. 522 00:35:48,233 --> 00:35:55,100 ♪ ♪ 523 00:35:55,133 --> 00:35:59,633 NARRATOR: Trillions of stars have existed since the universe began. 524 00:35:59,666 --> 00:36:04,733 {\an1}But ours is the only one we know of 525 00:36:04,766 --> 00:36:08,766 {\an1}that has nurtured that wonderful thing, life. 526 00:36:08,800 --> 00:36:13,733 {\an1}Not only nourished by the sun's light, 527 00:36:13,766 --> 00:36:17,700 {\an1}but also granted protection and the time to grow and change, 528 00:36:17,733 --> 00:36:23,966 {\an1}eventually creating complex life. 529 00:36:24,000 --> 00:36:27,066 IMARA: The sun is connected to our very existence. 530 00:36:27,100 --> 00:36:29,000 {\an7}It provides the light 531 00:36:29,033 --> 00:36:33,066 {\an1}and the energy that's necessary to sustain life. 532 00:36:33,100 --> 00:36:34,866 {\an1}There would absolutely be no life on Earth 533 00:36:34,900 --> 00:36:35,866 {\an1}if there was no sun. 534 00:36:35,900 --> 00:36:43,300 ♪ ♪ 535 00:36:43,333 --> 00:36:46,300 NARRATOR: The sun is a creator... 536 00:36:48,266 --> 00:36:51,466 {\an1}Bringing together atoms 537 00:36:51,500 --> 00:36:55,200 {\an1}forged in generations of ancient stars. 538 00:36:55,233 --> 00:36:57,266 ♪ ♪ 539 00:36:57,300 --> 00:37:00,466 {\an1}(animals bleating) 540 00:37:00,500 --> 00:37:05,100 To create us, 541 00:37:05,133 --> 00:37:10,100 beings capable of exploring the cosmos. 542 00:37:10,133 --> 00:37:16,166 ♪ ♪ 543 00:37:16,200 --> 00:37:20,633 {\an1}And uncovering our own stellar ancestry. 544 00:37:23,366 --> 00:37:25,100 HALABI: It's a wonderful thing, 545 00:37:25,133 --> 00:37:29,600 {\an1}how we share this intimate connection with stars, 546 00:37:29,633 --> 00:37:34,600 {\an1}because they are part of our cosmic heritage. 547 00:37:34,633 --> 00:37:38,966 {\an1}We are the children of these stars. 548 00:37:39,000 --> 00:37:43,600 ♪ ♪ 549 00:37:52,766 --> 00:37:58,066 NARRATOR: There are up to 400 billion stars in our galaxy. 550 00:38:01,600 --> 00:38:07,033 {\an1}And there are two trillion galaxies in our universe. 551 00:38:10,700 --> 00:38:14,433 {\an1}But it wasn't always that way. 552 00:38:17,333 --> 00:38:20,800 {\an1}We are living in the age of stars. 553 00:38:20,833 --> 00:38:26,533 ♪ ♪ 554 00:38:26,566 --> 00:38:31,366 {\an1}An era of light in the universe. 555 00:38:31,400 --> 00:38:34,766 HALABI: Stars have always been important to us. 556 00:38:34,800 --> 00:38:37,533 {\an1}They have helped us navigate the land 557 00:38:37,566 --> 00:38:40,033 {\an1}and the open seas for millennia. 558 00:38:40,066 --> 00:38:44,066 ♪ ♪ 559 00:38:44,100 --> 00:38:48,733 BOSE: If you just think back at the countless sonnets and poems 560 00:38:48,766 --> 00:38:51,200 {\an1}and songs, there is always some kind of 561 00:38:51,233 --> 00:38:52,233 {\an1}celestial connection. 562 00:38:52,266 --> 00:38:54,966 {\an8}♪ ♪ 563 00:38:55,000 --> 00:38:56,900 {\an8}IMARA: One of the reasons why 564 00:38:56,933 --> 00:38:59,533 {\an7}looking up into the stars is so significant 565 00:38:59,566 --> 00:39:03,033 {\an1}is because we realize that others are doing 566 00:39:03,066 --> 00:39:07,366 {\an1}the same exact thing, and so in a very real way, 567 00:39:07,400 --> 00:39:11,066 {\an1}we feel connected to people both past and present. 568 00:39:12,833 --> 00:39:16,566 {\an8}NARRATOR: From our fleeting, human perspective, 569 00:39:16,600 --> 00:39:19,900 {\an7}the stars seem everlasting. 570 00:39:22,100 --> 00:39:25,433 {\an1}A constant in our night sky. 571 00:39:30,566 --> 00:39:34,000 But seen across the age of the universe, 572 00:39:34,033 --> 00:39:35,400 {\an1}the picture changes. 573 00:39:37,666 --> 00:39:41,066 {\an1}Because this era cannot last. 574 00:39:43,433 --> 00:39:46,633 {\an1}The stars will eventually wane. 575 00:39:46,666 --> 00:39:50,666 ♪ ♪ 576 00:39:50,700 --> 00:39:52,400 And as they go, 577 00:39:52,433 --> 00:39:56,533 {\an1}they once again change the character of the universe. 578 00:39:58,100 --> 00:40:04,566 {\an1}Their cores, where fusion once raged, cool. 579 00:40:04,600 --> 00:40:12,033 ♪ ♪ 580 00:40:12,066 --> 00:40:15,300 (crackling) 581 00:40:21,000 --> 00:40:23,833 {\an1}And eventually solidify, 582 00:40:23,866 --> 00:40:28,700 {\an1}locking precious elements away beneath the surface. 583 00:40:30,766 --> 00:40:35,500 {\an1}And starving the universe of the material needed 584 00:40:35,533 --> 00:40:38,433 {\an1}to make new stars and planets. 585 00:40:39,133 --> 00:40:44,533 ♪ ♪ 586 00:40:44,566 --> 00:40:46,166 {\an8}TREMBLAY: The chance 587 00:40:46,200 --> 00:40:47,700 {\an7}that a star is going to be born nowadays 588 00:40:47,733 --> 00:40:50,000 {\an7}is, is much, much lower than it was 589 00:40:50,033 --> 00:40:53,033 {\an1}billions of years in the past. 590 00:40:53,066 --> 00:40:57,466 PRINJA: Just as there was a very first star in the universe, 591 00:40:57,500 --> 00:40:59,466 {\an7}there will come a time 592 00:40:59,500 --> 00:41:01,800 {\an7}when the era of stars will come to an end. 593 00:41:03,833 --> 00:41:09,900 NARRATOR: The age of stars is not as enduring as it might seem. 594 00:41:15,733 --> 00:41:19,600 {\an1}(insects chirping) 595 00:41:21,966 --> 00:41:24,333 GREEN: I have here a timeline of the universe, 596 00:41:24,366 --> 00:41:27,866 {\an1}and I'm here at the start when the universe formed 597 00:41:27,900 --> 00:41:32,166 {\an1}13.8 billion years ago during the Big Bang. 598 00:41:32,200 --> 00:41:34,966 {\an1}Now it took a while for the first stars to form-- 599 00:41:35,000 --> 00:41:36,933 in fact, a few hundred million years. 600 00:41:36,966 --> 00:41:38,633 Let's call that 400 million years. 601 00:41:38,666 --> 00:41:42,433 So on my scale, stars start to form here, 602 00:41:42,466 --> 00:41:43,700 {\an1}and those stars carried on forming, 603 00:41:43,733 --> 00:41:46,433 {\an1}and then we reach this point here, 604 00:41:46,466 --> 00:41:49,700 {\an1}four billion years since the Big Bang, 605 00:41:49,733 --> 00:41:54,533 {\an1}and a time when the most stars are forming in the universe. 606 00:41:54,566 --> 00:41:57,600 {\an1}Our sun, though, didn't form 607 00:41:57,633 --> 00:42:00,133 {\an1}until nine billion years had passed. 608 00:42:00,166 --> 00:42:02,933 {\an1}And that's my marker here. 609 00:42:02,966 --> 00:42:07,633 {\an1}And then we move forward again, and we get to this point here, 610 00:42:07,666 --> 00:42:09,433 {\an1}which is the present day, 611 00:42:09,466 --> 00:42:14,666 {\an1}13.8 billion years since the formation of the universe. 612 00:42:14,700 --> 00:42:16,900 {\an1}Now our sun won't live forever, 613 00:42:16,933 --> 00:42:19,500 {\an1}and in fact it will start to die and end its life 614 00:42:19,533 --> 00:42:22,066 {\an1}in around five billion years' time. 615 00:42:22,100 --> 00:42:24,166 {\an1}But the sun will be outlived 616 00:42:24,200 --> 00:42:27,066 {\an1}by the least massive stars in the universe. 617 00:42:27,100 --> 00:42:30,733 {\an1}They have lifetimes of a few hundred billion years, 618 00:42:30,766 --> 00:42:34,833 {\an1}and that's about 200 meters on my scale. 619 00:42:34,866 --> 00:42:37,566 {\an1}But even when those stars die, 620 00:42:37,600 --> 00:42:40,700 {\an1}that doesn't mark the end of the universe. 621 00:42:40,733 --> 00:42:43,333 {\an1}The universe could live forever, 622 00:42:43,366 --> 00:42:47,600 {\an1}with the timeline stretching far off into the distance. 623 00:42:47,633 --> 00:42:49,800 {\an1}And that means that the age of starlight 624 00:42:49,833 --> 00:42:51,166 {\an1}that I've mapped out here 625 00:42:51,200 --> 00:42:54,500 {\an1}is like the blink of an eye to the universe. 626 00:42:54,533 --> 00:43:01,433 {\an1}It's the age of darkness that goes on and on and on. 627 00:43:01,466 --> 00:43:05,133 ♪ ♪ 628 00:43:05,166 --> 00:43:09,766 NARRATOR: Stars won't suddenly disappear, of course. 629 00:43:11,200 --> 00:43:14,000 They'll be here for hundreds of billions, 630 00:43:14,033 --> 00:43:18,233 {\an1}perhaps even trillions, of years to come. 631 00:43:18,266 --> 00:43:21,466 {\an1}But slowly over time, 632 00:43:21,500 --> 00:43:25,966 {\an1}the universe will become darker. 633 00:43:26,000 --> 00:43:28,466 Emptier. 634 00:43:33,366 --> 00:43:34,866 As it expands, 635 00:43:34,900 --> 00:43:38,166 {\an1}the distances between these little islands of light 636 00:43:38,200 --> 00:43:42,766 {\an1}become greater and greater. 637 00:43:42,800 --> 00:43:47,633 {\an1}Until one day, only one type of star will remain. 638 00:43:47,666 --> 00:43:50,866 {\an8}♪ ♪ 639 00:43:50,900 --> 00:43:52,433 {\an8}Red dwarfs... 640 00:43:54,666 --> 00:44:00,133 {\an7}The longest lived of all stars in the universe. 641 00:44:00,166 --> 00:44:05,733 {\an1}Trappist 1 is one of these near immortals. 642 00:44:05,766 --> 00:44:13,166 {\an1}This ancient star is likely more than seven billion years old, 643 00:44:13,200 --> 00:44:15,566 {\an1}almost twice as old as our sun. 644 00:44:15,966 --> 00:44:22,266 ♪ ♪ 645 00:44:24,366 --> 00:44:27,300 {\an1}But Trappist is tiny, 646 00:44:27,333 --> 00:44:29,966 {\an1}a similar size to Jupiter. 647 00:44:34,733 --> 00:44:38,700 {\an1}And less than one percent as bright as our sun. 648 00:44:41,466 --> 00:44:45,666 {\an1}It is a cool star, slow burning. 649 00:44:47,833 --> 00:44:53,500 {\an8}♪ ♪ 650 00:44:53,533 --> 00:44:57,300 {\an7}And that is the secret of its longevity. 651 00:44:59,700 --> 00:45:03,033 {\an7}DAVID CHARBONNEAU: The lifetime of a star is determined 652 00:45:03,066 --> 00:45:07,733 {\an7}by its reservoir of hydrogen, of nuclear fuel. 653 00:45:07,766 --> 00:45:09,400 {\an7}As long as it has something to burn, 654 00:45:09,433 --> 00:45:11,166 {\an7}it will continue to survive. 655 00:45:11,200 --> 00:45:12,833 {\an7}But paradoxically, 656 00:45:12,866 --> 00:45:16,966 {\an7}the stars with the least amount of hydrogen live the longest. 657 00:45:17,000 --> 00:45:20,233 {\an1}And that's because they are miserly. 658 00:45:20,266 --> 00:45:23,633 {\an1}They spend their fuel so slowly. 659 00:45:23,666 --> 00:45:29,833 TREMBLAY: And so it's those smaller, more quiescent, less energetic stars 660 00:45:29,866 --> 00:45:31,533 {\an1}that ultimately become 661 00:45:31,566 --> 00:45:33,100 {\an1}the greatest historians of the universe. 662 00:45:35,000 --> 00:45:39,300 MUIRHEAD: It's especially exciting because this particular star 663 00:45:39,333 --> 00:45:41,400 {\an1}is going to continue fusing hydrogen 664 00:45:41,433 --> 00:45:44,766 {\an1}into helium in its core and continue shining 665 00:45:44,800 --> 00:45:48,600 {\an1}for potentially hundreds of billions of years. 666 00:45:48,633 --> 00:45:59,566 ♪ ♪ 667 00:46:04,200 --> 00:46:06,933 NARRATOR: Like the sun, 668 00:46:06,966 --> 00:46:10,100 {\an1}Trappist has its own planets. 669 00:46:16,466 --> 00:46:20,133 {\an1}Seven worlds, each roughly the size of Earth. 670 00:46:20,166 --> 00:46:24,200 ♪ ♪ 671 00:46:24,233 --> 00:46:28,566 {\an1}Some may have atmospheres, 672 00:46:28,600 --> 00:46:31,566 and even oceans. 673 00:46:33,466 --> 00:46:37,200 {\an1}But there the similarities end. 674 00:46:39,700 --> 00:46:44,066 Because these are strange worlds. 675 00:46:44,100 --> 00:46:48,233 {\an1}Just as one side of the moon always faces Earth, 676 00:46:48,266 --> 00:46:52,833 {\an1}these planets may be what we call "tidally locked" 677 00:46:52,866 --> 00:46:55,766 {\an1}in their orbits-- 678 00:46:55,800 --> 00:46:57,866 {\an1}one side permanently looking towards 679 00:46:57,900 --> 00:47:01,366 {\an1}the red dwarf Trappist 1, 680 00:47:01,400 --> 00:47:08,133 {\an1}soaking up what light and warmth it can from the faint star; 681 00:47:08,166 --> 00:47:11,766 {\an1}the other side permanently frozen, 682 00:47:11,800 --> 00:47:15,000 {\an1}facing the cold void of space. 683 00:47:18,500 --> 00:47:20,966 {\an1}These planets are witnesses 684 00:47:21,000 --> 00:47:24,133 {\an1}to much of the life of the universe. 685 00:47:24,166 --> 00:47:26,400 {\an1}They were born near the start, 686 00:47:26,433 --> 00:47:31,033 {\an1}and they will survive to near the end of the age of stars. 687 00:47:31,066 --> 00:47:32,900 ♪ ♪ 688 00:47:32,933 --> 00:47:38,566 {\an1}They will see entire galaxies merge, 689 00:47:38,600 --> 00:47:42,800 {\an1}and eventually begin to fade in their night skies. 690 00:47:42,833 --> 00:47:45,033 ♪ ♪ 691 00:47:45,066 --> 00:47:50,333 {\an1}They watch as countless stars come and go. 692 00:47:53,433 --> 00:47:56,066 {\an1}Bearing witness to the time, 693 00:47:56,100 --> 00:47:58,866 {\an1}about five billion years from now, 694 00:47:58,900 --> 00:48:04,566 {\an1}when a distant star begins to fade... 695 00:48:06,633 --> 00:48:11,033 {\an1}And vanishes from the night sky 696 00:48:11,066 --> 00:48:19,566 {\an1}as our sun finally exhausts its fuel and disappears forever. 697 00:48:20,400 --> 00:48:24,500 {\an1}(wind quietly whistling) 698 00:48:30,533 --> 00:48:35,500 IMARA: Ultimately, once the fusion process is over in the sun, 699 00:48:35,533 --> 00:48:37,633 {\an7}it will begin to expand 700 00:48:37,666 --> 00:48:40,633 {\an7}into what astronomers call a red giant, 701 00:48:40,666 --> 00:48:45,766 {\an1}and the outer envelope of the sun will expand. 702 00:48:45,800 --> 00:48:49,666 EZZEDDINE: It's going to gulp up some of the planets around it. 703 00:48:52,600 --> 00:48:54,466 {\an8}Unfortunately, Earth is one of them. 704 00:48:56,000 --> 00:49:01,733 NARRATOR: And as the sun dies, so too will many others like it. 705 00:49:01,766 --> 00:49:07,600 {\an1}The age of stellar creation in the universe is waning. 706 00:49:07,633 --> 00:49:09,866 {\an1}The universe is like a slow-motion fireworks show. 707 00:49:11,766 --> 00:49:14,466 {\an1}And we're kind of watching the end of it. 708 00:49:14,500 --> 00:49:22,633 ♪ ♪ 709 00:49:23,700 --> 00:49:26,233 NARRATOR: It's unlikely that Trappist 1 710 00:49:26,266 --> 00:49:29,266 {\an1}will be the very last star in the universe. 711 00:49:31,766 --> 00:49:36,666 {\an1}But we do believe the last star will be a red dwarf. 712 00:49:40,266 --> 00:49:43,300 ♪ ♪ 713 00:49:43,333 --> 00:49:47,566 {\an1}As its fuel runs out, 714 00:49:47,600 --> 00:49:50,766 {\an1}fusion comes to an end. 715 00:49:51,266 --> 00:49:56,500 {\an8}♪ ♪ 716 00:49:56,533 --> 00:49:59,933 {\an8}The last star 717 00:49:59,966 --> 00:50:04,366 {\an8}slowly cools, 718 00:50:04,400 --> 00:50:07,666 and fades away. 719 00:50:10,800 --> 00:50:16,800 ♪ ♪ 720 00:50:21,633 --> 00:50:25,733 {\an1}With its passing, 721 00:50:25,766 --> 00:50:31,133 {\an1}the universe becomes cold and dark. 722 00:50:34,700 --> 00:50:40,433 {\an1}Without light and, most likely, 723 00:50:40,466 --> 00:50:42,466 without life. 724 00:50:49,333 --> 00:50:53,000 (whooshing) 725 00:50:58,200 --> 00:51:01,200 PRINJA: When the last red dwarf stars die out, 726 00:51:01,233 --> 00:51:05,766 {\an1}that will be the end of stars in the universe. 727 00:51:05,800 --> 00:51:08,300 {\an1}And it was starlight 728 00:51:08,333 --> 00:51:09,800 {\an1}that really lit up its story. 729 00:51:09,833 --> 00:51:13,366 ♪ ♪ 730 00:51:13,400 --> 00:51:19,500 NARRATOR: A universe without light may be unfathomable to us humans. 731 00:51:19,533 --> 00:51:22,800 {\an1}Stars made us and our planet. 732 00:51:25,000 --> 00:51:29,600 {\an1}They define the universe as we know it today. 733 00:51:29,633 --> 00:51:33,433 HALABI: It was like a gift given to humanity, 734 00:51:33,466 --> 00:51:36,566 {\an1}that it took a cosmos to make you. 735 00:51:36,600 --> 00:51:40,933 ♪ ♪ 736 00:51:40,966 --> 00:51:47,000 NARRATOR: A cosmos eventually defined more by darkness than by light. 737 00:51:48,266 --> 00:51:54,600 But for now, we exist and learn and grow 738 00:51:54,633 --> 00:51:57,366 {\an1}as tiny sparks within the bright 739 00:51:57,400 --> 00:52:02,100 {\an1}and light-filled childhood of our universe. 740 00:52:02,133 --> 00:52:05,800 {\an1}We live in "The Age of Stars." 741 00:52:27,833 --> 00:52:32,533 {\an8}♪ ♪ 742 00:52:32,566 --> 00:52:34,600 {\an8}ALOK PATEL: Discover the science behind the news 743 00:52:34,633 --> 00:52:36,600 {\an7}with the NOVA Now podcast. 744 00:52:36,633 --> 00:52:40,200 {\an8}Listen at PBS.org/NovaNowPodcast, 745 00:52:40,233 --> 00:52:43,000 {\an7}or wherever you find your favorite podcasts. 746 00:52:43,033 --> 00:52:47,366 {\an8}ANNOUNCER: To order this program on DVD, visit ShopPBS. 747 00:52:47,400 --> 00:52:50,366 {\an7}Or call 1-800-PLAY-PBS. 748 00:52:50,400 --> 00:52:53,066 {\an7}Episodes of "NOVA" are available with Passport. 749 00:52:53,100 --> 00:52:56,900 {\an7}"NOVA" is also available on Amazon Prime Video. 750 00:52:59,433 --> 00:53:03,400 {\an8}♪ ♪ 751 00:53:16,366 --> 00:53:22,500 ♪ ♪