1 00:00:03,829 --> 00:00:05,353 [crickets] 2 00:00:05,527 --> 00:00:10,097 [owl hoot] 3 00:00:19,584 --> 00:00:22,370 TYSON: John Goodricke was a man who was permitted only the 4 00:00:22,544 --> 00:00:24,459 briefest glimpse of the stars. 5 00:00:25,242 --> 00:00:27,592 And yet, it could be said that he made one of the 6 00:00:27,766 --> 00:00:29,638 greatest discoveries of all. 7 00:00:33,163 --> 00:00:36,079 He had been left completely deaf by a childhood illness. 8 00:00:36,949 --> 00:00:39,648 And maybe that's why he looked so carefully. 9 00:00:43,434 --> 00:00:45,871 On a clear summer night in 1784, 10 00:00:46,785 --> 00:00:50,485 he went outside to see if a particular star was still 11 00:00:50,659 --> 00:00:53,531 doing something that mystified him. 12 00:00:54,358 --> 00:00:58,014 Something that no other astronomer had ever reported before. 13 00:00:59,972 --> 00:01:02,627 Goodricke couldn't believe his own eyes. 14 00:01:03,106 --> 00:01:05,108 The star, called Beta Lyrae, 15 00:01:05,282 --> 00:01:09,199 changed regularly in brightness over a very brief period of time. 16 00:01:09,678 --> 00:01:11,854 Only days. 17 00:01:12,028 --> 00:01:14,726 What could possibly make a star do that? 18 00:01:18,034 --> 00:01:20,602 Even more surprising, Goodricke found that he could 19 00:01:20,776 --> 00:01:22,995 predict its variations with high accuracy. 20 00:01:25,346 --> 00:01:27,478 What could cause such a change in a star's brightness? 21 00:01:29,611 --> 00:01:31,917 None of the scenarios that came to mind explained the 22 00:01:32,092 --> 00:01:34,268 evidence before him. 23 00:01:36,052 --> 00:01:38,446 And then, he thought of another possibility. 24 00:01:43,799 --> 00:01:46,671 Suppose there was something orbiting Beta Lyrae 25 00:01:46,845 --> 00:01:49,283 that eclipsed the star on a regular basis. 26 00:01:54,549 --> 00:01:56,507 But what could it be? 27 00:02:08,040 --> 00:02:10,434 "A world perhaps?" 28 00:02:22,185 --> 00:02:24,666 How about a trillion? 29 00:02:31,368 --> 00:02:36,895 [theme music plays]. 30 00:02:57,046 --> 00:03:03,270 ♪ ♪ 31 00:03:22,811 --> 00:03:28,556 ♪ ♪ 32 00:03:34,518 --> 00:03:36,477 TYSON: When John Goodricke's discovery came to the attention 33 00:03:36,651 --> 00:03:39,610 of the prestigious British Royal Society in 1786, 34 00:03:40,655 --> 00:03:42,700 he was immediately made a member. 35 00:03:46,138 --> 00:03:49,054 Word of this honor never reached him, 36 00:03:49,620 --> 00:03:52,754 days later he was dead of pneumonia. 37 00:03:55,060 --> 00:03:57,846 He was only 21. 38 00:04:02,546 --> 00:04:05,506 It would be 150 years before another astronomer 39 00:04:05,680 --> 00:04:07,899 would solve Goodricke's mystery. 40 00:04:08,335 --> 00:04:12,426 And in the process, change our cosmos forever. 41 00:04:13,340 --> 00:04:16,256 Even as a child, Gerard Peter Kuiper could 42 00:04:16,430 --> 00:04:18,083 see farther than anyone else. 43 00:04:19,868 --> 00:04:22,914 He saw stars too distant and too faint for others 44 00:04:23,088 --> 00:04:25,090 to find without a telescope. 45 00:04:26,657 --> 00:04:29,617 This was in the Netherlands more than a century ago. 46 00:04:30,487 --> 00:04:32,794 Back then, the son of a poor tailor could not 47 00:04:32,968 --> 00:04:35,231 hope to become an astronomer. 48 00:04:35,405 --> 00:04:38,321 But the boy would not be stopped. 49 00:04:38,756 --> 00:04:41,759 Back then, astronomers thought that the cosmos consisted of 50 00:04:41,933 --> 00:04:45,241 only a handful of planets, those of our own solar system. 51 00:04:46,851 --> 00:04:50,377 The great multitude of other stars were just barren points 52 00:04:50,551 --> 00:04:53,510 of light that had never given birth to worlds. 53 00:04:55,077 --> 00:04:59,429 We on Earth could still feel special. 54 00:05:00,212 --> 00:05:02,302 Our star system, the scientists told us, 55 00:05:02,476 --> 00:05:06,784 was the rarest of all, one blessed by worlds and moons. 56 00:05:14,531 --> 00:05:17,708 Kuiper yearned to know how our Sun and its planets 57 00:05:17,882 --> 00:05:20,145 came to be. 58 00:05:21,930 --> 00:05:24,585 And made his way to the University of Leiden, 59 00:05:24,759 --> 00:05:26,587 where he quickly distinguished himself. 60 00:05:28,850 --> 00:05:31,505 He was invited to join the dynamic astronomical community 61 00:05:31,679 --> 00:05:34,986 in the United States, but Kuiper had rough edges, 62 00:05:36,205 --> 00:05:38,816 he was argumentative and easily drawn into conflict 63 00:05:38,990 --> 00:05:40,731 with his colleagues. 64 00:05:40,905 --> 00:05:44,169 The prospect of directing a remote observatory far away 65 00:05:44,344 --> 00:05:46,650 from the capitals of scientific culture must have 66 00:05:46,824 --> 00:05:48,478 appealed to him. 67 00:05:48,652 --> 00:05:51,786 And besides, you could see the stars better there 68 00:05:51,960 --> 00:05:54,528 than just about anywhere else. 69 00:05:55,355 --> 00:05:58,880 Kuiper was given an appointment at the McDonald Observatory, 70 00:05:59,054 --> 00:06:02,100 situated in a corner of West Texas. 71 00:06:03,275 --> 00:06:06,061 At the turn of the century, it had been discovered that half 72 00:06:06,235 --> 00:06:09,934 the visible stars were really gravitational pairs. 73 00:06:11,588 --> 00:06:13,895 Most binary stars are like twins, 74 00:06:14,069 --> 00:06:16,985 forming from the same womb of gas and dust. 75 00:06:18,203 --> 00:06:20,771 Others come of age separately and become gravitationally 76 00:06:20,945 --> 00:06:23,818 involved with each other later in their development. 77 00:06:24,645 --> 00:06:28,257 And the other half remain single throughout their lives. 78 00:06:29,040 --> 00:06:31,956 Kuiper chose to concentrate on the binary stars. 79 00:06:32,957 --> 00:06:35,003 He wondered if they could shed light on the way that the 80 00:06:35,177 --> 00:06:38,136 planets in our solar system formed and came to be 81 00:06:38,310 --> 00:06:40,704 gravitationally bound to our Sun. 82 00:06:41,183 --> 00:06:43,664 KUIPER: Bright ascension. 18 hours, 50 minutes. 83 00:06:43,968 --> 00:06:46,493 Declination plus 33 degrees. 84 00:06:46,667 --> 00:06:48,625 2175 minutes. 85 00:06:49,060 --> 00:06:50,453 ASSISTANT: Mm-hmm. 86 00:06:50,888 --> 00:06:53,021 TYSON: Kuiper looked at the very same star that 87 00:06:53,195 --> 00:06:55,806 had baffled John Goodricke 150 years before, 88 00:06:56,633 --> 00:07:00,289 but Kuiper was looking at it with a much bigger telescope. 89 00:07:01,899 --> 00:07:04,728 And Kuiper was armed with an awesome power that didn't 90 00:07:04,902 --> 00:07:08,166 exist in Goodricke's time, spectroscopy. 91 00:07:08,950 --> 00:07:11,387 Spectroscopy is a way to dissect the light of any 92 00:07:11,561 --> 00:07:14,695 single star to find its particular atomic and 93 00:07:14,869 --> 00:07:16,523 molecular composition. 94 00:07:17,306 --> 00:07:19,830 Kuiper looked at the spectrum of the light produced 95 00:07:20,004 --> 00:07:23,007 by Beta Lyrae and saw that, as with all stars, 96 00:07:23,573 --> 00:07:25,793 there was plenty of hydrogen and helium, 97 00:07:25,967 --> 00:07:29,884 but there was also iron sodium and silicon. 98 00:07:30,493 --> 00:07:32,234 So far, no surprises there. 99 00:07:32,408 --> 00:07:34,454 Now, here comes the twist. 100 00:07:35,193 --> 00:07:36,586 Bright lines? 101 00:07:36,760 --> 00:07:39,067 Where were those bright lines coming from? 102 00:07:39,241 --> 00:07:42,505 At that time, no astronomer understood why bright lines 103 00:07:42,679 --> 00:07:44,289 would appear in the spectrum of a star. 104 00:07:45,508 --> 00:07:48,250 Kuiper leapt to the conclusion that the two stars 105 00:07:48,424 --> 00:07:50,992 were so close that they were exchanging matter, 106 00:07:52,297 --> 00:07:55,257 super-hot gases that would produce such a signature. 107 00:07:56,650 --> 00:07:59,217 In trying to understand what he had seen that night, 108 00:07:59,957 --> 00:08:03,091 Kuiper discovered and named the most intimate stellar 109 00:08:03,265 --> 00:08:05,876 relationship in the cosmos. 110 00:08:06,181 --> 00:08:09,750 Stars that are physically locked in everlasting oneness, 111 00:08:09,924 --> 00:08:13,014 bound together by gravity and a bridge of fire 112 00:08:13,971 --> 00:08:15,930 made of star stuff. 113 00:08:18,498 --> 00:08:22,110 A bridge eight million miles long, 114 00:08:23,415 --> 00:08:25,287 connecting two stars, 115 00:08:25,461 --> 00:08:28,116 one three times more massive than our Sun, 116 00:08:28,290 --> 00:08:31,946 the other 13 times greater still. 117 00:08:34,296 --> 00:08:37,604 A contact binary star system. 118 00:08:37,952 --> 00:08:40,781 Why aren't they round like our own star? 119 00:08:41,129 --> 00:08:43,087 They are so closed to one another, 120 00:08:43,261 --> 00:08:46,613 tidal forces of gravity pull them together and stretch them 121 00:08:46,787 --> 00:08:49,354 into flaming teardrops. 122 00:08:50,834 --> 00:08:55,230 The Beta Lyrae system is about 1,000 light-years from earth. 123 00:08:55,839 --> 00:08:58,712 The largest telescopes of the mid-20th century were just not 124 00:08:58,886 --> 00:09:01,976 powerful enough to resolve them as individual stars. 125 00:09:03,325 --> 00:09:05,762 You needed that new power of spectroscopy 126 00:09:06,067 --> 00:09:08,373 to disentangle them. 127 00:09:08,548 --> 00:09:10,985 Kuiper imagined how the formation of the contact 128 00:09:11,159 --> 00:09:14,075 binary star system could have happened. 129 00:09:14,641 --> 00:09:17,426 He deduced that they were formed when a vast cloud of 130 00:09:17,600 --> 00:09:22,387 gas and dust become so dense that gravitational whirlpools formed. 131 00:09:27,610 --> 00:09:30,265 In thinking about these contact binaries, 132 00:09:30,439 --> 00:09:33,050 Kuiper couldn't help but wonder if any of these stellar 133 00:09:33,224 --> 00:09:35,662 courtships ever failed to catch on fire. 134 00:09:38,012 --> 00:09:41,929 Kuiper asked himself, was our world, 135 00:09:42,103 --> 00:09:45,367 our Moon and all the planets of our solar system nothing 136 00:09:45,541 --> 00:09:48,022 more than a failed binary star system? 137 00:09:49,676 --> 00:09:53,593 And if that's how our solar system was created, 138 00:09:53,941 --> 00:09:57,335 had the same thing happened around other stars throughout the cosmos? 139 00:10:03,777 --> 00:10:06,301 Gerard Kuiper had a special power, 140 00:10:06,475 --> 00:10:09,086 he could see farther than anyone else. 141 00:10:09,565 --> 00:10:12,742 He was the first to envision the universe we now live in. 142 00:10:13,482 --> 00:10:17,268 Not a barren vastness meagerly dotted by childless stars, 143 00:10:18,008 --> 00:10:20,489 but one overflowing with possible worlds, 144 00:10:20,663 --> 00:10:23,144 countless planets and moons. 145 00:10:25,581 --> 00:10:29,411 In 1949, Kuiper astonished the world by declaring that 146 00:10:29,585 --> 00:10:32,849 our solar system was not so special after all, 147 00:10:33,502 --> 00:10:37,027 that every other star had its own family of worlds. 148 00:10:39,726 --> 00:10:42,250 A world perhaps? 149 00:10:43,730 --> 00:10:47,516 But science wasn't ready for that universe, 150 00:10:47,951 --> 00:10:51,868 it wasn't even ready to take its first baby steps off the planet. 151 00:10:52,042 --> 00:10:53,478 Why not? 152 00:10:53,653 --> 00:10:56,307 Science was carved up into little kingdoms, 153 00:10:56,481 --> 00:10:59,136 the various scientific disciplines and scientists of 154 00:10:59,310 --> 00:11:01,922 one discipline didn't collaborate with anyone from another. 155 00:11:03,445 --> 00:11:06,535 But this had to change for us to venture beyond Earth. 156 00:11:07,188 --> 00:11:10,670 It all came to a head in a feud between Kuiper and 157 00:11:10,844 --> 00:11:12,976 another great scientist. 158 00:11:13,977 --> 00:11:16,501 Like two stars of a contact binary system, 159 00:11:16,676 --> 00:11:18,416 they could not disengage. 160 00:11:18,590 --> 00:11:20,592 But despite their loathing for each other, 161 00:11:20,767 --> 00:11:23,813 they managed to create a new kind of science and they 162 00:11:23,987 --> 00:11:26,381 pioneered the Space Age, 163 00:11:26,729 --> 00:11:29,819 mentoring its greatest visionary and voice. 164 00:11:36,086 --> 00:11:38,959 ♪ ♪ 165 00:11:44,573 --> 00:11:50,100 ♪ ♪ 166 00:11:50,405 --> 00:11:52,799 TYSON: Sometimes, the cosmos just barges right in 167 00:11:52,973 --> 00:11:55,062 and breaks down your door, like tonight. 168 00:11:57,499 --> 00:11:59,283 What's going on here? 169 00:11:59,457 --> 00:12:02,896 Our planet is passing through the epic remnants of a comet, 170 00:12:03,287 --> 00:12:05,812 a debris field millions of miles long. 171 00:12:06,508 --> 00:12:09,554 That's why it looks like it's raining stars tonight. 172 00:12:10,077 --> 00:12:11,992 But they're not stars at all, 173 00:12:12,166 --> 00:12:14,690 just bits of rock and ice burning up in Earth's atmosphere. 174 00:12:15,822 --> 00:12:17,911 It's called a meteor shower. 175 00:12:18,085 --> 00:12:20,652 And this one happens at the same time every year. 176 00:12:21,784 --> 00:12:23,438 Why? 177 00:12:23,612 --> 00:12:25,353 Because it takes a year for Earth to orbit the Sun and 178 00:12:25,527 --> 00:12:27,398 return to that same place where the comets 179 00:12:27,572 --> 00:12:29,923 streaked by so long ago. 180 00:12:30,097 --> 00:12:32,186 That's what a year is. 181 00:12:33,100 --> 00:12:37,408 This could be a piece of that comet or possibly 182 00:12:37,582 --> 00:12:39,367 a fragment of an asteroid. 183 00:12:39,976 --> 00:12:41,717 It came from another world, 184 00:12:41,891 --> 00:12:44,851 a leftover from the creation of our solar system. 185 00:12:45,025 --> 00:12:47,723 But how to understand it? 186 00:12:48,202 --> 00:12:49,986 Well, back in Gerard Kuiper's time, 187 00:12:50,160 --> 00:12:51,771 during the middle of the 20th century, 188 00:12:51,945 --> 00:12:54,774 it depended on what kind of a scientist you were. 189 00:12:55,557 --> 00:12:58,212 The geologists would bring their hammers and break this 190 00:12:58,386 --> 00:13:01,258 sucker apart and look at its dust under a microscope to 191 00:13:01,432 --> 00:13:04,348 study its crystalline structure. 192 00:13:04,653 --> 00:13:07,047 It was their way of finding out which missing piece in 193 00:13:07,221 --> 00:13:09,701 this puzzle of Earth the meteorite could provide. 194 00:13:11,094 --> 00:13:13,575 The chemists were searching for the same answers, 195 00:13:13,749 --> 00:13:16,056 but they would drop it in acid to see if it could be 196 00:13:16,230 --> 00:13:18,449 transformed from one compound into another, 197 00:13:19,494 --> 00:13:21,496 torturing it to see if it would give up 198 00:13:21,670 --> 00:13:23,672 its secrets about nature. 199 00:13:29,765 --> 00:13:33,769 The physicists would want to see it at its most naked. 200 00:13:36,119 --> 00:13:39,296 Stripped down to its mass, its density, its hardness. 201 00:13:40,080 --> 00:13:43,083 Its resistance to heat. 202 00:13:43,605 --> 00:13:47,130 The biologist wouldn't even stop to pick it up. 203 00:13:47,478 --> 00:13:50,177 Back then, they would've walked right by it because 204 00:13:50,351 --> 00:13:53,093 they didn't think there was any chance that a meteorite 205 00:13:53,267 --> 00:13:56,661 from space had anything to do with them. 206 00:13:57,053 --> 00:14:02,189 Life could only be from one place, right here, Earth. 207 00:14:07,977 --> 00:14:10,110 And you want to know the craziest thing? 208 00:14:10,675 --> 00:14:12,068 Back then, 209 00:14:12,242 --> 00:14:14,766 the astronomers would've walked right by it, too. 210 00:14:14,941 --> 00:14:17,900 Their sights were focused on the distance and we can't 211 00:14:18,074 --> 00:14:19,684 really blame them. 212 00:14:19,859 --> 00:14:22,122 What was happening in astronomy back then? 213 00:14:22,296 --> 00:14:25,516 Big ideas about things far beyond our solar system, 214 00:14:26,126 --> 00:14:28,432 Einstein's theory of relativity, 215 00:14:28,606 --> 00:14:31,566 with its vision of riding a light beam across the cosmos 216 00:14:32,132 --> 00:14:35,483 and Edwin Hubble's discovery that the universe was expanding, 217 00:14:36,440 --> 00:14:39,443 that distant galaxies were flying away from one another. 218 00:14:39,617 --> 00:14:42,969 That's what raised goosebumps, not looking at a dumb rock 219 00:14:43,143 --> 00:14:45,319 lying in your own backyard. 220 00:14:45,623 --> 00:14:47,974 Studying the planets, moons, comets and meteors of our own 221 00:14:48,148 --> 00:14:50,977 tiny solar system seemed like little league. 222 00:14:53,109 --> 00:14:55,633 Until Kuiper dared to venture into territories 223 00:14:55,807 --> 00:14:58,332 off-limits to astronomy. 224 00:14:58,636 --> 00:15:00,987 Night after night, he would stay up here... 225 00:15:01,161 --> 00:15:05,469 A virtuoso playing the 45-ton instrument like a violin. 226 00:15:05,817 --> 00:15:09,038 Searching the solar system for clues to its origin. 227 00:15:09,386 --> 00:15:12,824 A mystery that he alone recognized was insoluble 228 00:15:12,999 --> 00:15:17,090 without the cooperative enterprise of all the scientific disciplines. 229 00:15:18,178 --> 00:15:21,224 But the scientists didn't know they needed one another. 230 00:15:21,616 --> 00:15:24,053 There wasn't a single university department where 231 00:15:24,227 --> 00:15:27,970 scientists of multiple disciplines could study planetary astronomy. 232 00:15:28,710 --> 00:15:31,931 So here, in the middle of nowhere, 233 00:15:32,888 --> 00:15:36,936 in a corner of West Texas, Kuiper conducted his one-man 234 00:15:37,110 --> 00:15:39,329 exploration of the solar system. 235 00:15:52,821 --> 00:15:55,824 He looked at Titan, one of Saturn's moons, 236 00:15:55,998 --> 00:15:58,348 and discovered that it had an atmosphere, 237 00:15:58,914 --> 00:16:01,569 it was thick with methane. 238 00:16:01,873 --> 00:16:05,486 A point of light in the sky had suddenly become a real place. 239 00:16:06,574 --> 00:16:09,794 Kuiper used the spectroscope to probe the acrid clouds in 240 00:16:09,969 --> 00:16:13,755 the upper atmosphere of Jupiter to see what they were made of, 241 00:16:13,929 --> 00:16:16,236 their chemical and atomic structures. 242 00:16:16,410 --> 00:16:18,586 And when he looked at the red planet, Mars, 243 00:16:18,760 --> 00:16:21,981 he found carbon dioxide in its atmosphere and he wondered, 244 00:16:22,894 --> 00:16:27,377 "Am I looking at my planet's future or its past?" 245 00:16:28,291 --> 00:16:32,252 But to some people, Kuiper was doing nothing more than trespassing. 246 00:16:33,035 --> 00:16:35,298 Butting into chemical matters where an astronomer 247 00:16:35,472 --> 00:16:37,605 had no business. 248 00:16:37,779 --> 00:16:40,521 Harold Urey was a chemist. 249 00:16:40,782 --> 00:16:42,262 Like Gerard Kuiper, 250 00:16:42,436 --> 00:16:45,439 he also had to fight his way into science. 251 00:16:45,787 --> 00:16:48,311 Urey's family was poor like Kuiper's. 252 00:16:48,485 --> 00:16:51,619 So he took a job teaching grammar school in a 253 00:16:51,793 --> 00:16:54,143 mining camp in Montana. 254 00:16:55,710 --> 00:16:57,581 The parents of one of his students urged him to 255 00:16:57,755 --> 00:17:00,149 find a way to get to college. 256 00:17:01,759 --> 00:17:03,979 Harold Urey took that advice all the way to a 257 00:17:04,153 --> 00:17:06,590 Nobel Prize in chemistry. 258 00:17:08,636 --> 00:17:11,552 By 1949, he was riding high, 259 00:17:12,161 --> 00:17:15,382 a distinguished professor at the University of Chicago. 260 00:17:15,730 --> 00:17:17,253 Then, and now, 261 00:17:17,427 --> 00:17:20,256 one of the world's great capitals of science. 262 00:17:20,604 --> 00:17:22,389 But when Urey read his morning paper, 263 00:17:22,563 --> 00:17:24,956 something began to curdle inside him, 264 00:17:25,131 --> 00:17:27,785 a rising resentment. 265 00:17:27,959 --> 00:17:31,702 First, a pang at a fellow scientist's heightened celebrity. 266 00:17:31,963 --> 00:17:34,270 Well, that was normal. 267 00:17:34,618 --> 00:17:38,709 Then he got to the part about the origin of the planets. 268 00:17:39,014 --> 00:17:41,538 He was offended that an astronomer was making 269 00:17:41,712 --> 00:17:44,976 pronouncements about the chemical nature of the solar system. 270 00:17:45,325 --> 00:17:47,718 That was his turf. 271 00:17:50,199 --> 00:17:52,332 Scientists are human. 272 00:17:52,506 --> 00:17:54,029 We're primates. 273 00:17:54,377 --> 00:17:57,554 We carry the same evolutionary baggage as everyone else. 274 00:17:58,773 --> 00:18:01,776 Kuiper and Urey were two alpha males who chose 275 00:18:01,950 --> 00:18:04,344 scientific argument as their weapon of combat. 276 00:18:06,476 --> 00:18:09,784 And the two men fought over a single hostage, 277 00:18:10,132 --> 00:18:12,003 a young student. 278 00:18:16,269 --> 00:18:17,966 When Carl Sagan was a kid, 279 00:18:18,140 --> 00:18:21,100 he lived here, in a small apartment in Brooklyn. 280 00:18:25,843 --> 00:18:29,108 [ticking] 281 00:18:31,545 --> 00:18:34,635 [street sounds] 282 00:18:39,292 --> 00:18:42,382 In the mid-1940s, he made this drawing, 283 00:18:42,556 --> 00:18:44,558 filled with predictions, 284 00:18:44,732 --> 00:18:47,952 that is now in the US Library of Congress. 285 00:18:58,180 --> 00:19:02,010 ♪ ♪ 286 00:19:07,668 --> 00:19:12,673 MAN [over PA]: 3, 2, 1, 0. All engine running. 287 00:19:13,935 --> 00:19:16,459 Liftoff, we have a liftoff! 288 00:19:18,200 --> 00:19:20,246 TYSON: In an era where life here was in the last seconds 289 00:19:20,420 --> 00:19:22,987 of its four billion captivity on Earth, 290 00:19:23,988 --> 00:19:27,818 he dreamed of going to the planets and even to the stars. 291 00:19:30,038 --> 00:19:32,736 But he didn't want to just go in his imagination, 292 00:19:32,910 --> 00:19:34,738 he wanted to really go. 293 00:19:35,174 --> 00:19:38,089 He wanted to know what those worlds were really like. 294 00:19:39,134 --> 00:19:42,964 And he knew that the only way to do that was to become a scientist. 295 00:19:45,009 --> 00:19:48,099 The boy would come under the wings of the two warring giants. 296 00:19:49,100 --> 00:19:50,928 As much as they hated each other, 297 00:19:51,102 --> 00:19:53,540 he loved them both. 298 00:19:53,844 --> 00:19:56,282 Together, the three of them would tear down the walls 299 00:19:56,456 --> 00:19:58,545 between the scientists. 300 00:19:58,719 --> 00:20:01,330 And the boy would tear down the tallest wall, 301 00:20:01,504 --> 00:20:05,160 the one between science and everyone else. 302 00:20:13,516 --> 00:20:15,214 TYSON: Do something for me. 303 00:20:15,388 --> 00:20:18,478 I need you to pretend that we live in a time before any 304 00:20:18,652 --> 00:20:22,133 spacecraft or human had ever left Earth, 305 00:20:22,525 --> 00:20:25,572 no one had ever seen our world from space. 306 00:20:26,529 --> 00:20:29,271 The most extravagant fantasies of the greatest artists were 307 00:20:29,445 --> 00:20:31,926 no match for what was coming. 308 00:20:32,579 --> 00:20:35,321 This is how one of them imagined Earth must look from space. 309 00:20:36,931 --> 00:20:39,455 And then, in one instant on a single day, 310 00:20:40,630 --> 00:20:42,893 everything changed. 311 00:20:44,591 --> 00:20:48,421 This is how Mother Earth looked when she was naked, 312 00:20:48,595 --> 00:20:51,467 before nearly 5,000 satellites were in orbit around her, 313 00:20:53,252 --> 00:20:56,603 before anyone had ever counted backwards from ten. 314 00:20:59,170 --> 00:21:05,133 [counting down from ten in Russian]. 315 00:21:11,618 --> 00:21:15,056 [counting down from ten in Russian]. 316 00:21:45,739 --> 00:21:48,002 TYSON: On October 4, 1957, 317 00:21:48,176 --> 00:21:51,353 the Soviet Union became the first nation to dip its 318 00:21:51,527 --> 00:21:55,139 toe into the shallows of the cosmic ocean. 319 00:21:56,706 --> 00:21:59,230 It launched Sputnik 1, 320 00:21:59,796 --> 00:22:04,148 a simple radio transmitter that circled Earth every 96 minutes. 321 00:22:11,808 --> 00:22:14,463 All over the planet, people came outside to find 322 00:22:14,637 --> 00:22:18,772 this new light in the sky, a man-made moon. 323 00:22:20,687 --> 00:22:22,515 Nothing could stop us from achieving our 324 00:22:22,689 --> 00:22:26,083 most daring dreams. 325 00:22:26,257 --> 00:22:31,175 Think of it, something we made was a new light in the night sky. 326 00:22:32,089 --> 00:22:35,354 Something like a star. 327 00:22:35,658 --> 00:22:37,268 As this was happening, 328 00:22:37,443 --> 00:22:40,141 the boy was becoming a scientist, 329 00:22:40,533 --> 00:22:44,493 and this new knowledge moved him as nothing before had. 330 00:22:45,451 --> 00:22:47,844 All he could think was that he wanted to share it with 331 00:22:48,018 --> 00:22:50,238 everyone on Earth, 332 00:22:50,586 --> 00:22:53,546 but that kind of thing was frowned upon by scientists, 333 00:22:53,850 --> 00:22:56,940 they saw themselves as being members of an elite club. 334 00:22:58,246 --> 00:23:01,858 In 1950, when Carl Sagan was just a high school student, 335 00:23:02,032 --> 00:23:04,731 he wrote a paper that earned him an invitation to work in 336 00:23:04,905 --> 00:23:07,342 the lab of H.J. Muller, 337 00:23:07,516 --> 00:23:10,563 who had won the Nobel Prize for his discovery that radiation 338 00:23:10,737 --> 00:23:13,174 causes mutations in genes. 339 00:23:14,784 --> 00:23:17,439 By the time Carl got to the University of Chicago, 340 00:23:17,613 --> 00:23:20,442 he was beginning to make a name for himself, 341 00:23:20,616 --> 00:23:23,184 and Harold Urey chose to mentor him. 342 00:23:23,619 --> 00:23:25,316 Urey, the chemist, 343 00:23:25,491 --> 00:23:28,015 was now doing the thing that he had resented Kuiper for, 344 00:23:28,189 --> 00:23:31,192 trespassing on the turf of another scientific discipline. 345 00:23:32,193 --> 00:23:34,369 This time it was biology. 346 00:23:34,543 --> 00:23:37,416 Urey and his team wanted to know how life could have 347 00:23:37,590 --> 00:23:39,766 originated from lifeless matter. 348 00:23:42,116 --> 00:23:44,335 Working with another student of his, 349 00:23:45,075 --> 00:23:48,514 Stanley Miller, Urey designed an experiment to simulate the 350 00:23:48,688 --> 00:23:51,908 chemical conditions of the atmosphere on the early Earth. 351 00:23:52,648 --> 00:23:55,172 They wanted to see whether those basic chemicals could 352 00:23:55,346 --> 00:23:59,133 have led to amino acids, the building blocks of life. 353 00:24:01,701 --> 00:24:05,661 Could lightning have provided the spark that awakened matter into life? 354 00:24:07,576 --> 00:24:10,753 "And if it could happen here on Earth, 355 00:24:11,232 --> 00:24:14,278 where else could it have happened?" Carl wondered. 356 00:24:16,716 --> 00:24:19,283 When he wrote a paper speculating on that possibility, 357 00:24:19,458 --> 00:24:21,721 Urey responded harshly. 358 00:24:22,678 --> 00:24:25,681 He scolded his apprentice for venturing beyond his expertise. 359 00:24:26,943 --> 00:24:29,859 But still, Carl loved Urey because he knew that this 360 00:24:30,033 --> 00:24:32,775 toughness would make him a better scientist. 361 00:24:34,429 --> 00:24:37,345 In the summer, Carl traveled to the enemy camp, 362 00:24:37,519 --> 00:24:39,086 to McDonald Observatory, 363 00:24:39,260 --> 00:24:42,002 to observe Mars with Gerard Kuiper, 364 00:24:42,263 --> 00:24:45,701 the only planetary astronomer on Earth. 365 00:24:45,875 --> 00:24:48,878 That year, Mars was in a favorable opposition to Earth. 366 00:24:50,271 --> 00:24:54,014 The two worlds would be the closest they'd been in 30 years. 367 00:24:54,841 --> 00:24:57,365 But the weather didn't cooperate, 368 00:24:57,539 --> 00:24:59,802 not in Texas, but on Mars. 369 00:25:00,673 --> 00:25:03,937 A global windblown dust storm there prevented Kuiper 370 00:25:04,111 --> 00:25:06,548 and Sagan from seeing anything new. 371 00:25:07,418 --> 00:25:09,377 Instead, they spent those summer nights talking 372 00:25:09,551 --> 00:25:11,248 of many things. 373 00:25:11,422 --> 00:25:13,599 The older man taught the young scientist the 374 00:25:13,773 --> 00:25:17,211 most efficient ways to test his bold new ideas. 375 00:25:17,733 --> 00:25:20,606 They fantasized about what those possible worlds circling 376 00:25:20,780 --> 00:25:23,260 other stars might be like. 377 00:25:23,565 --> 00:25:26,394 These two fearless scientific imaginations ventured 378 00:25:26,568 --> 00:25:29,353 throughout the galaxy all that summer. 379 00:25:29,702 --> 00:25:33,314 The gates to the wonderworld were swinging open for Carl. 380 00:25:33,662 --> 00:25:35,795 And all of this was happening as we were reaching 381 00:25:35,969 --> 00:25:39,581 beyond the planet for the very first time. 382 00:25:40,495 --> 00:25:44,717 [Sputnik radio signal] 383 00:25:47,589 --> 00:25:49,896 Soviet Union's Sputnik scared the hell out of 384 00:25:50,070 --> 00:25:51,811 the United States. 385 00:25:51,985 --> 00:25:54,944 The Cold War was a contest between dueling ideologies 386 00:25:55,118 --> 00:25:57,338 about property and freedom. 387 00:25:57,947 --> 00:25:59,732 When the Russians got there first, 388 00:25:59,906 --> 00:26:02,822 it seemed to reflect badly on our world view. 389 00:26:03,387 --> 00:26:06,695 And if they could send an object into orbit above our heads, 390 00:26:06,869 --> 00:26:09,872 we could no longer protect our skies. 391 00:26:10,264 --> 00:26:12,266 Suddenly, there was a new delivery system 392 00:26:12,440 --> 00:26:13,876 for nuclear weapons. 393 00:26:14,050 --> 00:26:15,530 Nowhere on Earth could be safeguarded against 394 00:26:15,704 --> 00:26:17,837 espionage or attack. 395 00:26:18,011 --> 00:26:20,709 We needed a space program of our own. 396 00:26:21,318 --> 00:26:23,930 The National Aeronautics and Space Administration was 397 00:26:24,104 --> 00:26:26,802 founded a year after Sputnik in 1958. 398 00:26:27,977 --> 00:26:31,024 Science was at last ready to see Earth as Kuiper 399 00:26:31,198 --> 00:26:33,853 had been seeing it for years, as a planet. 400 00:26:35,158 --> 00:26:36,769 What a concept. 401 00:26:37,160 --> 00:26:40,033 It may seem obvious to us now, but in a time of fanatical, 402 00:26:40,207 --> 00:26:43,471 fight to the death nationalism, it was a thunderbolt. 403 00:26:45,429 --> 00:26:48,171 But Kuiper's feud with Urey still raged, 404 00:26:48,345 --> 00:26:49,869 even as they both took leadership roles in the 405 00:26:50,043 --> 00:26:52,262 fledgling space program. 406 00:26:52,828 --> 00:26:55,788 Carl continued ferrying between their warring labs. 407 00:26:56,266 --> 00:27:00,009 The enmity between the two men was emotionally so corrosive 408 00:27:00,183 --> 00:27:02,098 that he said at the time he, 409 00:27:02,272 --> 00:27:04,666 "Felt like the child of divorced parents and he was 410 00:27:04,840 --> 00:27:07,974 the only bridge left between them." 411 00:27:08,322 --> 00:27:11,151 Urey fought for NASA to go to the Moon. 412 00:27:11,325 --> 00:27:14,981 Among his reasons was a desire to know, at last, 413 00:27:15,938 --> 00:27:18,637 how the solar system formed. 414 00:27:24,120 --> 00:27:27,036 Kuiper predicted what it would be like when we got there. 415 00:27:27,210 --> 00:27:30,561 That when we stepped down on the lunar surface for the first time, 416 00:27:30,736 --> 00:27:33,652 it would feel like walking on crunchy snow. 417 00:27:35,915 --> 00:27:38,918 The Moon is a silent world because it has no atmosphere 418 00:27:39,092 --> 00:27:41,094 to carry sound waves. 419 00:27:41,268 --> 00:27:44,663 But Neil Armstrong later said that he felt Kuiper's crunchy 420 00:27:44,837 --> 00:27:47,230 snow when he stepped down onto the surface for the 421 00:27:47,404 --> 00:27:49,885 very first time. 422 00:27:50,625 --> 00:27:53,628 Some of the things the wanderers left behind. 423 00:28:00,853 --> 00:28:02,681 Thanks to Urey and Kuiper, 424 00:28:02,855 --> 00:28:05,422 Carl Sagan was part of this great adventure. 425 00:28:06,293 --> 00:28:09,513 He was living his most extravagant childhood fantasies. 426 00:28:10,253 --> 00:28:12,212 He briefed the Apollo astronauts before they left 427 00:28:12,386 --> 00:28:13,735 for the Moon. 428 00:28:13,909 --> 00:28:16,042 And he was there when scientists first met to 429 00:28:16,216 --> 00:28:18,784 evaluate the information gained from the dawn 430 00:28:18,958 --> 00:28:21,003 of space exploration. 431 00:28:21,612 --> 00:28:25,094 For the first time ever, the biologist, the geologist, 432 00:28:25,704 --> 00:28:27,183 the astronomers, 433 00:28:27,357 --> 00:28:29,620 the physicists, the chemists were all talking 434 00:28:29,795 --> 00:28:31,318 to one another. 435 00:28:31,492 --> 00:28:33,450 Actually, mostly shouting. 436 00:28:34,234 --> 00:28:36,323 The young Carl Sagan stood up at one of their 437 00:28:36,497 --> 00:28:39,021 joint scientific meetings and said, 438 00:28:39,195 --> 00:28:43,678 "Hey, guys, we're the first generation of scientists to receive these riches. 439 00:28:44,940 --> 00:28:47,464 We're in this together." 440 00:28:47,769 --> 00:28:51,381 He set a tone for planetary science that still holds today. 441 00:28:53,296 --> 00:28:56,430 He edited the first modern interdisciplinary journal for 442 00:28:56,604 --> 00:28:59,085 researchers studying the world of the cosmos, 443 00:29:00,303 --> 00:29:03,089 Icarus, which continues to this day. 444 00:29:03,698 --> 00:29:05,439 And he did something else. 445 00:29:05,613 --> 00:29:08,311 He started a lifelong campaign to bring the revelations of 446 00:29:08,485 --> 00:29:12,751 science to everyone, and he was one of a handful of 447 00:29:13,186 --> 00:29:15,841 scientists who made the search for possible worlds, 448 00:29:16,015 --> 00:29:19,366 for extra-terrestrial life and for intelligence respectable 449 00:29:19,540 --> 00:29:21,542 scientific pursuits. 450 00:29:22,586 --> 00:29:25,894 We've only been hunting for new worlds for a few decades, 451 00:29:26,068 --> 00:29:28,984 but we've already discovered many thousands of them. 452 00:29:31,160 --> 00:29:33,684 We think some of them are hospitable to life and at 453 00:29:33,859 --> 00:29:36,905 least a dozen of them are earth-like. 454 00:29:40,517 --> 00:29:43,433 What will they be like? 455 00:29:44,652 --> 00:29:46,741 Come with me. 456 00:30:01,060 --> 00:30:03,584 TYSON: Carl Sagan wanted to liberate a scientific 457 00:30:03,758 --> 00:30:07,022 imagination from the single example of life that we know, 458 00:30:08,197 --> 00:30:09,808 Earth life. 459 00:30:09,982 --> 00:30:12,332 He envisioned what the life of another very different 460 00:30:12,506 --> 00:30:14,290 world would be like. 461 00:30:14,464 --> 00:30:17,685 Sagan collaborated with fellow astrophysicist Ed Salpeter in 462 00:30:17,859 --> 00:30:21,645 the design of plausible ecological systems for life in 463 00:30:21,820 --> 00:30:23,865 the roiling clouds of Jupiter. 464 00:30:25,693 --> 00:30:28,827 The challenge was to imagine such life-forms without 465 00:30:29,001 --> 00:30:32,178 violating the laws of physics, chemistry or biology. 466 00:30:34,397 --> 00:30:39,794 Is life so tenacious that it could even make a home in this storm of hydrogen, 467 00:30:40,403 --> 00:30:43,319 helium, water, ammonia and methane? 468 00:30:44,625 --> 00:30:47,149 There's no accessible solid surface. 469 00:30:47,323 --> 00:30:50,544 It's just this thick cloudy atmosphere in which organic 470 00:30:50,718 --> 00:30:53,764 molecules are falling like manna from heaven, 471 00:30:54,853 --> 00:30:59,466 like the products of Harold Urey and Stanley Miller's laboratory experiment on life's origin. 472 00:30:59,988 --> 00:31:03,035 However, this environment poses a problem for life. 473 00:31:03,644 --> 00:31:07,909 The atmosphere is turbulent and deep down it's very hot. 474 00:31:08,736 --> 00:31:11,478 An organism must be careful that it's not carried downward 475 00:31:11,652 --> 00:31:14,002 to the hell below. 476 00:31:15,482 --> 00:31:17,440 One way to make a living under these conditions is to 477 00:31:17,614 --> 00:31:20,139 reproduce before you sink and get fried. 478 00:31:21,575 --> 00:31:24,230 Your only hope is that convection will carry some of 479 00:31:24,404 --> 00:31:26,797 your offspring to the higher and cooler layers 480 00:31:26,972 --> 00:31:29,365 of the atmosphere. 481 00:31:31,106 --> 00:31:33,674 Such organisms could be very small. 482 00:31:34,370 --> 00:31:36,851 Sagan and Salpeter call them "sinkers." 483 00:31:39,854 --> 00:31:42,204 But you could also be a "floater," 484 00:31:42,378 --> 00:31:46,426 a vast hydrogen blimp pumping helium and heavier gases out of your interior and 485 00:31:46,600 --> 00:31:49,559 retaining only the lightest gas, hydrogen. 486 00:31:51,518 --> 00:31:54,477 Sagan and Salpeter reasoned that like a hot air balloon 487 00:31:54,651 --> 00:31:57,872 you'd stay buoyant by keeping your interior warm using 488 00:31:58,046 --> 00:32:00,875 energy acquired from the foods you eat. 489 00:32:01,397 --> 00:32:04,879 A floater must eat organic molecules or make its own food 490 00:32:05,053 --> 00:32:07,882 from sunlight and air, as plants do on Earth. 491 00:32:10,276 --> 00:32:13,627 The bigger a floater is, the more efficient it will be, 492 00:32:13,801 --> 00:32:16,021 up to a point. 493 00:32:16,673 --> 00:32:19,633 Floaters would be immense, several kilometers across, 494 00:32:21,548 --> 00:32:24,855 enormously larger than the greatest whale that ever was, 495 00:32:25,421 --> 00:32:28,076 beings the size of cities. 496 00:32:28,250 --> 00:32:30,078 The floaters may propel themselves through the 497 00:32:30,252 --> 00:32:32,863 planetary atmosphere with gusts of gas, 498 00:32:33,038 --> 00:32:34,996 like a ramjet or a rocket. 499 00:32:36,911 --> 00:32:39,783 Sagan and Salpeter imagined them arranged in great lazy 500 00:32:39,958 --> 00:32:42,395 herds for as far as the eye could see. 501 00:32:44,223 --> 00:32:47,226 The patterns on their skin are adaptive camouflage, 502 00:32:47,400 --> 00:32:50,142 implying that they have problems, too, 503 00:32:50,446 --> 00:32:54,407 because there's at least one other ecological niche in such an environment... 504 00:33:02,676 --> 00:33:04,765 Hunters. 505 00:33:04,939 --> 00:33:07,289 Hunters are fast, maneuverable. 506 00:33:12,120 --> 00:33:13,774 Hunters eat the floaters, 507 00:33:13,948 --> 00:33:16,081 both for their organic molecules and for their 508 00:33:16,255 --> 00:33:18,387 store of pure hydrogen. 509 00:33:42,890 --> 00:33:46,807 There cannot be very many hunters because if they consume all the floaters, 510 00:33:47,677 --> 00:33:50,028 the hunters themselves will parish. 511 00:34:03,824 --> 00:34:06,609 When scientists of the 21st century tested Sagan's 512 00:34:06,783 --> 00:34:09,525 imaginary life-forms against what they knew of life, 513 00:34:10,483 --> 00:34:13,964 they realized that the concept of a habitable zone 514 00:34:14,139 --> 00:34:16,184 had to be expanded. 515 00:34:16,358 --> 00:34:19,144 It moved into the cloud tops of gas giants and 516 00:34:19,318 --> 00:34:21,537 the subsurface oceans of ice worlds, 517 00:34:22,060 --> 00:34:24,888 and places we've yet to imagine. 518 00:34:25,585 --> 00:34:28,501 Of all those worlds, of all those stars, 519 00:34:30,068 --> 00:34:32,983 one must have been first. 520 00:34:36,161 --> 00:34:39,164 Come with me to the oldest world we know. 521 00:34:47,389 --> 00:34:49,870 TYSON: We're in a globular cluster, 522 00:34:50,044 --> 00:34:54,309 a densely packed ball of a million stars, called M4, 523 00:34:54,701 --> 00:34:57,573 on the outskirts of the Milky Way galaxy. 524 00:34:57,878 --> 00:35:00,576 When pulsars, rapidly rotating neutron stars, 525 00:35:00,750 --> 00:35:04,189 were first discovered, scientists wondered if they 526 00:35:04,363 --> 00:35:07,540 were a sign of intelligent life because of the regularity 527 00:35:07,714 --> 00:35:09,542 of their radio signals. 528 00:35:10,586 --> 00:35:13,589 Once upon a time, this star was a blue supergiant, 529 00:35:13,763 --> 00:35:16,636 but after a few million years, it ran out of fuel, 530 00:35:17,245 --> 00:35:20,553 went supernova, then collapsed into this ball of neutrons, 531 00:35:21,423 --> 00:35:23,904 no larger than a small town. 532 00:35:24,078 --> 00:35:26,515 It's nearby companion, a white dwarf star, 533 00:35:26,689 --> 00:35:28,735 another burnt-out stellar corpse, 534 00:35:28,909 --> 00:35:31,607 orbits only a few million miles away. 535 00:35:31,781 --> 00:35:33,783 That's not why we've come here. 536 00:35:33,957 --> 00:35:37,396 We've come in search of the oldest known planet in the cosmos. 537 00:35:40,399 --> 00:35:42,357 The cosmos was young when this star, 538 00:35:42,531 --> 00:35:46,056 a white dwarf, was born, 12.7 billion years ago. 539 00:35:47,449 --> 00:35:50,365 The star was single then, long before it was captured 540 00:35:50,539 --> 00:35:53,325 by the pulsar that gave birth to a world. 541 00:35:54,064 --> 00:35:56,284 That world is out here somewhere, 542 00:35:56,458 --> 00:35:59,505 taking 100 Earth years to orbit these two shrunken stars. 543 00:36:01,637 --> 00:36:04,727 The fact that it exists bodes well for those who dream of 544 00:36:04,901 --> 00:36:07,121 virtually infinite possible worlds. 545 00:36:08,557 --> 00:36:12,431 If it formed less than a billion years after the cosmos itself, 546 00:36:12,605 --> 00:36:15,608 then stars started fostering planets soon after 547 00:36:15,782 --> 00:36:18,263 the beginning of time. 548 00:36:18,828 --> 00:36:22,267 Nurturing worlds is what stars do. 549 00:36:23,920 --> 00:36:27,402 And what will the fate of this oldest of planets be? 550 00:36:28,142 --> 00:36:30,840 Sorry to say, it's a lonely one. 551 00:36:31,014 --> 00:36:33,234 Sometime in the next billion years, 552 00:36:33,408 --> 00:36:37,107 the two stars will be gravitationally ambushed by a third. 553 00:36:44,985 --> 00:36:48,641 A red dwarf star will come barreling into their vicinity. 554 00:36:48,815 --> 00:36:52,210 It's gravity will send this ancient world careening out of 555 00:36:52,384 --> 00:36:57,258 its system and into the lonely dark between the stars. 556 00:36:58,085 --> 00:37:02,916 A rogue planet doomed to wander a never-ending oblivion. 557 00:37:04,091 --> 00:37:07,573 But there are also homes away from home that call to us, 558 00:37:07,747 --> 00:37:10,228 illuminated in warmth not by one star, 559 00:37:10,402 --> 00:37:11,707 but three. 560 00:37:12,099 --> 00:37:15,363 I want to take you to Gliese 667, 561 00:37:15,668 --> 00:37:18,018 a triple-star system with six worlds, 562 00:37:18,192 --> 00:37:22,588 three of them enough like earth to hold the promise of life as we know it. 563 00:37:38,343 --> 00:37:42,999 Stars A and B are both a little smaller than our Sun. 564 00:37:44,871 --> 00:37:48,222 This pair of orange dwarfs orbit each other. 565 00:37:49,267 --> 00:37:52,879 Star C orbits them both, it's a red dwarf. 566 00:37:54,359 --> 00:37:57,187 They're the most common kind of star in the galaxy. 567 00:37:57,710 --> 00:38:00,713 As many as 80% of all the stars in the cosmos may 568 00:38:00,887 --> 00:38:03,281 be red dwarfs. 569 00:38:03,629 --> 00:38:06,109 They consume their hydrogen fuel slowly, 570 00:38:06,284 --> 00:38:08,286 so they last longer. 571 00:38:08,460 --> 00:38:10,592 More massive stars, like blue giants, 572 00:38:10,766 --> 00:38:14,292 maintain such high pressures that they burn out quickly. 573 00:38:27,870 --> 00:38:31,526 This outermost world of the Gliese 667 system is 574 00:38:31,700 --> 00:38:35,008 four times the size of earth, but it's too far from 575 00:38:35,182 --> 00:38:38,359 its stars to have liquid water on its surface. 576 00:38:38,794 --> 00:38:40,666 That doesn't mean it's lifeless. 577 00:38:40,840 --> 00:38:43,103 We don't yet know enough about life to say what 578 00:38:43,277 --> 00:38:46,324 might be going on beneath its frozen shell. 579 00:38:46,802 --> 00:38:48,587 We haven't yet reached the habitable zone of 580 00:38:48,761 --> 00:38:50,415 this star system. 581 00:38:50,589 --> 00:38:53,200 Getting closer, but not there yet, 582 00:38:53,809 --> 00:38:55,898 this even larger world is impressive, 583 00:38:56,769 --> 00:38:59,467 but still just outside that region considered to be 584 00:38:59,641 --> 00:39:04,037 hospitable to life and to the human scientific imagination. 585 00:39:08,476 --> 00:39:10,913 Now, this is more like it. 586 00:39:11,392 --> 00:39:14,656 The kind of atmosphere that promises life is here. 587 00:39:34,328 --> 00:39:40,116 ♪ ♪ 588 00:40:00,049 --> 00:40:02,051 ♪ ♪ 589 00:40:03,401 --> 00:40:06,578 [animal call] 590 00:40:37,478 --> 00:40:43,397 [waves and wind] 591 00:40:44,137 --> 00:40:48,750 [distant animal calls] 592 00:41:07,726 --> 00:41:12,121 [waves and wind] 593 00:41:29,922 --> 00:41:32,577 This isn't the stuff of distant worlds, 594 00:41:32,751 --> 00:41:34,927 this little guy is one of our own. 595 00:41:35,318 --> 00:41:39,148 All the other life-forms we've just seen were actually homegrown, 596 00:41:39,322 --> 00:41:41,281 right here on Earth. 597 00:41:41,629 --> 00:41:43,457 We haven't even begun to get to know all the 598 00:41:43,631 --> 00:41:46,155 living things on this tiny world. 599 00:41:46,721 --> 00:41:48,418 Think of all the possibilities, 600 00:41:48,593 --> 00:41:51,117 the different kinds of life there must have been, 601 00:41:51,291 --> 00:41:54,381 and are, and will be in the cosmos. 602 00:41:54,816 --> 00:41:56,209 Thanks to Gerard Kuiper, 603 00:41:56,383 --> 00:41:58,733 Harold Urey and so many other scientists, 604 00:41:58,907 --> 00:42:03,390 we now know that it takes just a few million years for stars to evolve, 605 00:42:03,912 --> 00:42:07,263 and planets and moons to coalesce out of gas and dust. 606 00:42:08,308 --> 00:42:11,180 In other words, a solar system. 607 00:42:21,408 --> 00:42:23,279 It's a long period of gestation, 608 00:42:23,453 --> 00:42:25,151 but far from rare. 609 00:42:25,325 --> 00:42:28,371 In our own galaxy, it happens about once every month. 610 00:42:28,937 --> 00:42:30,678 In the observable universe, 611 00:42:30,852 --> 00:42:32,506 which we now think contains as many as 612 00:42:32,680 --> 00:42:35,161 a trillion galaxies, containing some 613 00:42:35,335 --> 00:42:38,730 200 million trillion stars, 614 00:42:40,035 --> 00:42:44,692 a cosmos of 200 million trillion stars, 615 00:42:45,998 --> 00:42:49,784 1,000 solar systems may be forming every single second. 616 00:42:51,133 --> 00:42:54,006 That's 1,000 new solar systems right there. 617 00:42:55,834 --> 00:42:57,487 1,000 new solar systems. 618 00:42:58,488 --> 00:42:59,838 1,000 new solar systems. 619 00:43:00,708 --> 00:43:02,101 1,000 new solar systems. 620 00:43:03,058 --> 00:43:04,973 1,000 new solar systems. 621 00:43:05,583 --> 00:43:08,281 1,000 new solar systems. 622 00:43:08,455 --> 00:43:10,457 1,000 new solar systems. 623 00:43:11,023 --> 00:43:12,154 [finger snap] 624 00:43:12,894 --> 00:43:14,069 [finger snap] 625 00:43:53,805 --> 00:43:55,720 Captioned by Cotter Captioning Services.