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These are the user uploaded subtitles that are being translated: 1 00:00:04,120 --> 00:00:08,960 Our galaxy, far in the future. 2 00:00:11,500 --> 00:00:16,360 A planet shrouded in turbulent, dense clouds. 3 00:00:21,870 --> 00:00:23,170 Buried deep below, 4 00:00:23,170 --> 00:00:25,810 an alien landscape... 5 00:00:28,180 --> 00:00:31,310 Extreme pressures, and a scorched surface 6 00:00:31,310 --> 00:00:34,550 with sky-high temperatures. 7 00:00:36,950 --> 00:00:41,360 But this isn't a distant extraterrestrial world. 8 00:00:45,400 --> 00:00:51,600 It's earth's future, maybe a billion years from now. 9 00:00:51,600 --> 00:00:56,810 We know this because earth has a twin... 10 00:00:56,810 --> 00:00:58,540 Venus. 11 00:00:58,540 --> 00:01:02,410 And Venus has already descended into hell. 12 00:01:07,780 --> 00:01:11,850 Have you ever dreamed about travelling out of this world? 13 00:01:11,860 --> 00:01:13,390 My name is Mike Massimino, 14 00:01:13,390 --> 00:01:15,720 and I turned that fantasy into a reality 15 00:01:15,730 --> 00:01:18,830 when I space-walked to repair the Hubble space telescope. 16 00:01:18,830 --> 00:01:21,800 Great job, Mike. 17 00:01:21,800 --> 00:01:24,600 Now, as we expand our knowledge of our solar system 18 00:01:24,600 --> 00:01:27,500 from Mercury to the cosmic unknowns, 19 00:01:27,500 --> 00:01:30,000 I want to take you on a personal journey to... 20 00:01:34,440 --> 00:01:38,150 "The planets." 21 00:01:38,150 --> 00:01:39,710 Welcome to "the planets." 22 00:01:39,720 --> 00:01:41,350 I'm Mike Massimino. 23 00:01:41,350 --> 00:01:43,380 I got to live out my childhood dream 24 00:01:43,390 --> 00:01:44,690 when I first travelled to space 25 00:01:44,690 --> 00:01:47,020 in 2002. 26 00:01:47,020 --> 00:01:48,860 Looking down at the earth from the Hubble space telescope, 27 00:01:48,860 --> 00:01:52,130 I was blown away by this perfect blue sphere 28 00:01:52,130 --> 00:01:53,600 in the middle of space. 29 00:01:53,600 --> 00:01:56,630 As peaceful and inviting as our planet is, 30 00:01:56,630 --> 00:02:00,000 our neighbor, Venus, is the complete opposite... 31 00:02:00,000 --> 00:02:02,700 No water, scorching temperatures, 32 00:02:02,710 --> 00:02:04,410 and crushing pressure. 33 00:02:04,410 --> 00:02:06,540 And just when you think there's nothing in common 34 00:02:06,540 --> 00:02:08,380 between these two planets, 35 00:02:08,380 --> 00:02:11,710 it turns out they're actually siblings. 36 00:02:13,420 --> 00:02:17,250 Take a look around the solar system... 37 00:02:17,250 --> 00:02:22,990 Eight planets orbiting a central star, the sun. 38 00:02:22,990 --> 00:02:25,230 Among them is earth 39 00:02:25,230 --> 00:02:27,730 and its neighbor, Venus. 40 00:02:29,830 --> 00:02:34,840 Earth, our home, is an oasis for life. 41 00:02:34,840 --> 00:02:37,840 Venus is the stuff of nightmares. 42 00:02:40,110 --> 00:02:43,650 Venus and earth couldn't be more different. 43 00:02:43,650 --> 00:02:45,310 The earth is this beautiful planet, 44 00:02:45,320 --> 00:02:46,610 and there's water everywhere. 45 00:02:46,620 --> 00:02:49,150 It's ice at the poles. It's water in the ocean. 46 00:02:49,150 --> 00:02:51,850 It's in the atmosphere as water vapor. 47 00:02:53,660 --> 00:02:55,290 But then you look at Venus. 48 00:02:55,290 --> 00:02:57,760 It is the worst place imaginable. 49 00:02:57,760 --> 00:03:00,800 It is so hot on the surface, crushing pressures. 50 00:03:00,800 --> 00:03:04,370 It couldn't be any less supportive of life. 51 00:03:06,440 --> 00:03:07,770 To me, the planet Venus 52 00:03:07,770 --> 00:03:10,440 is sort of a classic definition of the word "hell." 53 00:03:12,880 --> 00:03:14,810 If you were to transport to Venus 54 00:03:14,810 --> 00:03:18,010 and experience the environment there, 55 00:03:18,010 --> 00:03:21,220 you'd quickly want to return back to earth. 56 00:03:21,220 --> 00:03:22,720 The conditions on Venus 57 00:03:22,720 --> 00:03:27,760 are among the most inhospitable in the solar system. 58 00:03:27,760 --> 00:03:29,960 It's going to be a competition between whether or not 59 00:03:29,960 --> 00:03:32,830 you're gonna be cooked to death or crushed to death. 60 00:03:38,770 --> 00:03:45,870 Earth and Venus may seem like very different worlds, 61 00:03:45,880 --> 00:03:48,880 but they shouldn't be. 62 00:03:48,880 --> 00:03:53,680 They're roughly the same size, same mass, 63 00:03:53,680 --> 00:03:57,990 and made from the same stuff. 64 00:03:57,990 --> 00:04:01,090 And they started out as twins. 65 00:04:01,090 --> 00:04:03,860 Early Venus and early earth were very similar. 66 00:04:03,860 --> 00:04:05,290 They were twins, 67 00:04:05,300 --> 00:04:09,400 probably nearly identical twins, at their earliest stages. 68 00:04:09,400 --> 00:04:13,640 Given that Venus is so earth-like in so many ways, 69 00:04:13,640 --> 00:04:16,270 it's really odd that it is so different than the earth. 70 00:04:16,270 --> 00:04:18,410 And this makes it one of the biggest mysteries 71 00:04:18,410 --> 00:04:20,580 in the solar system. 72 00:04:20,580 --> 00:04:23,610 Somewhere in their two histories, 73 00:04:23,610 --> 00:04:28,150 the earth and Venus took two very different paths. 74 00:04:28,150 --> 00:04:29,180 The result? 75 00:04:29,190 --> 00:04:32,650 Two totally different worlds. 76 00:04:32,660 --> 00:04:35,160 Their paths were so different, you could hardly believe 77 00:04:35,160 --> 00:04:36,890 that one would have been related to the other. 78 00:04:36,890 --> 00:04:39,060 But now, the opposite thing's going to happen. 79 00:04:39,060 --> 00:04:41,260 We're gonna catch up with our twin. 80 00:04:41,260 --> 00:04:45,900 We're gonna evolve to be a lot more like Venus in the future. 81 00:04:45,900 --> 00:04:46,970 In the future, 82 00:04:46,970 --> 00:04:50,300 the two planets' paths will converge, 83 00:04:50,310 --> 00:04:54,410 and they will become twin-like once again. 84 00:04:56,350 --> 00:05:01,620 There is going to be hell on earth. 85 00:05:01,620 --> 00:05:05,650 The oceans will vaporize. The land will melt. 86 00:05:05,660 --> 00:05:08,960 Our hospitable blue planet will vanish, 87 00:05:08,960 --> 00:05:13,960 replaced by a fiery, molten world. 88 00:05:13,960 --> 00:05:15,800 We are actually on the earth at a time 89 00:05:15,800 --> 00:05:17,500 when there's water and rain, 90 00:05:17,500 --> 00:05:19,600 and it was so easy for life to take hold. 91 00:05:19,600 --> 00:05:21,040 But that's gonna change. 92 00:05:21,040 --> 00:05:24,410 And take a look in at Venus and have a look at our future. 93 00:05:31,880 --> 00:05:33,920 How will this happen? 94 00:05:39,090 --> 00:05:41,290 The roots of our home world's destruction 95 00:05:41,290 --> 00:05:44,860 are buried deep in our twin planet's past. 96 00:05:47,400 --> 00:05:50,930 It's very much true that, in studying the past of Venus, 97 00:05:50,930 --> 00:05:55,670 we are also studying the distant future of earth. 98 00:05:55,670 --> 00:05:59,610 Both planets share a violent birth, 99 00:05:59,610 --> 00:06:03,140 scarred by brutal planet formation, 100 00:06:03,150 --> 00:06:07,180 giant cosmic impacts, and rampant volcanism. 101 00:06:07,180 --> 00:06:09,220 We're trying to reconstruct things 102 00:06:09,220 --> 00:06:10,990 that happened in the ancient, ancient past. 103 00:06:10,990 --> 00:06:13,690 It's almost like forensic planetary geology. 104 00:06:17,560 --> 00:06:22,060 4.6 billion years ago, hundreds of infant planets 105 00:06:22,070 --> 00:06:24,830 begin to form around the new sun. 106 00:06:27,900 --> 00:06:32,510 Among them, the baby Venus and earth. 107 00:06:32,510 --> 00:06:35,610 And as they hurtle around the sun, 108 00:06:35,610 --> 00:06:38,580 collisions are inevitable. 109 00:06:40,350 --> 00:06:43,520 Planet formation is like a demolition derby. 110 00:06:43,520 --> 00:06:45,550 In a derby, the cars are racing around a track, 111 00:06:45,560 --> 00:06:48,760 going around in circles at different speeds. 112 00:06:48,760 --> 00:06:50,420 Well, it's the same thing with planets. 113 00:06:50,430 --> 00:06:51,890 The material is orbiting the sun. 114 00:06:51,900 --> 00:06:54,260 It's going around, and they're all going at different speeds, 115 00:06:54,260 --> 00:06:56,030 at different angels, different trajectories. 116 00:06:56,030 --> 00:06:57,900 And sometimes, boom. 117 00:07:06,540 --> 00:07:10,550 In this derby, planet hits planet. 118 00:07:10,550 --> 00:07:12,910 Two become one... 119 00:07:12,920 --> 00:07:14,250 Violently. 120 00:07:19,560 --> 00:07:21,720 You have these large bodies that are hitting each other 121 00:07:21,720 --> 00:07:23,190 at really high velocity. 122 00:07:26,360 --> 00:07:29,800 It's really a very hot, violent mess. 123 00:07:33,200 --> 00:07:34,240 The amount of energy released 124 00:07:34,240 --> 00:07:36,370 in these impacts is huge. 125 00:07:36,370 --> 00:07:38,040 It completely dwarfs 126 00:07:38,040 --> 00:07:40,880 all of the nuclear weapons on earth combined. 127 00:07:40,880 --> 00:07:43,380 And yet, somehow, on these scales, 128 00:07:43,380 --> 00:07:47,220 you wind up forming gigantic objects that we call planets. 129 00:07:49,820 --> 00:07:56,620 Earth and Venus become voracious planet eaters. 130 00:07:56,630 --> 00:08:00,130 But two spectacular collisions set the twins 131 00:08:00,130 --> 00:08:03,760 on very different paths. 132 00:08:03,770 --> 00:08:06,500 That was the moment Venus and earth went through 133 00:08:06,500 --> 00:08:08,940 this divergence to what has now become 134 00:08:08,940 --> 00:08:11,170 these really dramatically different worlds. 135 00:08:13,240 --> 00:08:14,680 The divergence begins 136 00:08:14,680 --> 00:08:17,480 when a Mars-sized object hits earth. 137 00:08:24,220 --> 00:08:29,420 The impact makes our planet spin faster. 138 00:08:29,430 --> 00:08:32,060 The core spins with it, generating 139 00:08:32,060 --> 00:08:35,930 a powerful magnetic field around the planet. 140 00:08:39,340 --> 00:08:43,910 The field fends off the worst of the sun's radiation. 141 00:08:48,880 --> 00:08:50,710 Around the same time, 142 00:08:50,710 --> 00:08:54,350 Venus takes a head-on hit from another infant planet. 143 00:08:56,690 --> 00:09:02,390 This impact explains something very weird about Venus. 144 00:09:02,390 --> 00:09:03,960 Venus is actually rotating 145 00:09:03,960 --> 00:09:05,890 in the wrong direction. 146 00:09:05,900 --> 00:09:07,160 How could that be? 147 00:09:07,160 --> 00:09:10,600 Well, what if it got hit really hard by some object? 148 00:09:10,600 --> 00:09:11,630 That could do it. 149 00:09:13,770 --> 00:09:16,000 An object so huge, 150 00:09:16,010 --> 00:09:21,740 Venus stops in its tracks and begins to spin backwards. 151 00:09:21,740 --> 00:09:24,610 If you think about how much energy 152 00:09:24,610 --> 00:09:28,780 and what size you need to change a planet's spin, 153 00:09:28,790 --> 00:09:31,390 that is an incredibly large hit. 154 00:09:34,360 --> 00:09:36,860 But the backspin is slow... 155 00:09:36,860 --> 00:09:40,630 243 times slower than earth. 156 00:09:43,800 --> 00:09:45,670 Without a fast spin, 157 00:09:45,670 --> 00:09:50,810 Venus' core can't generate a strong magnetic field. 158 00:09:50,810 --> 00:09:53,370 It has no protection from the deadly stream 159 00:09:53,380 --> 00:09:57,910 of particles blasted from the sun. 160 00:09:57,910 --> 00:10:00,920 Venus does not have a strong magnetic field, 161 00:10:00,920 --> 00:10:03,380 and so it has suffered the full brunt 162 00:10:03,390 --> 00:10:05,790 of this wind blasted out from the sun. 163 00:10:08,860 --> 00:10:11,190 The tale of two planets 164 00:10:11,190 --> 00:10:13,090 now splits radically. 165 00:10:15,100 --> 00:10:16,830 Venus will roast 166 00:10:16,830 --> 00:10:20,330 under a violent, suffocating atmosphere. 167 00:10:20,340 --> 00:10:23,300 Earth will give birth to oceans, 168 00:10:23,310 --> 00:10:27,070 life, and intelligence. 169 00:10:27,080 --> 00:10:30,040 But ultimately, these twins' fates 170 00:10:30,050 --> 00:10:32,550 are the same. 171 00:10:32,550 --> 00:10:36,580 Earth's future is Venus... 172 00:10:36,590 --> 00:10:38,390 Pure hell. 173 00:10:43,860 --> 00:10:46,690 4.6 billion years ago, 174 00:10:46,700 --> 00:10:49,260 two nearly-identical planets formed... 175 00:10:49,270 --> 00:10:51,130 Earth and Venus. 176 00:10:51,130 --> 00:10:53,630 Earth blossomed into a colorful haven 177 00:10:53,640 --> 00:10:55,300 for life to thrive, 178 00:10:55,300 --> 00:10:58,470 while Venus is the definition of hell. 179 00:10:58,470 --> 00:11:00,770 How did they turn out so different? 180 00:11:00,780 --> 00:11:04,480 Images from space probes sent to Venus provide the answer. 181 00:11:08,050 --> 00:11:10,990 Venus is a vision of hell. 182 00:11:10,990 --> 00:11:16,160 And one day, we'll meet our twin's fate. 183 00:11:16,160 --> 00:11:17,790 So, how will our blue planet 184 00:11:17,790 --> 00:11:20,900 become a superheated wasteland? 185 00:11:20,900 --> 00:11:23,630 Only Venus can really tell us. 186 00:11:25,940 --> 00:11:28,500 Something happened to Venus long in its past 187 00:11:28,500 --> 00:11:31,040 to make it a completely different planet 188 00:11:31,040 --> 00:11:33,140 with a completely different personality 189 00:11:33,140 --> 00:11:35,540 than the earth as we know it today. 190 00:11:35,550 --> 00:11:39,480 Two, three, four. 191 00:11:39,480 --> 00:11:41,920 We earthlings sent our first probe 192 00:11:41,920 --> 00:11:44,990 to our sister planet in 1967, 193 00:11:44,990 --> 00:11:47,520 and we've been sending them ever since. 194 00:11:50,490 --> 00:11:58,300 What they found blew scientists' minds... 195 00:11:58,300 --> 00:12:01,870 Rocks that look like granite. 196 00:12:01,870 --> 00:12:04,410 What makes that interesting is that, to make granite, 197 00:12:04,410 --> 00:12:06,040 you need water. 198 00:12:08,040 --> 00:12:11,010 That means that there must have been abundant water 199 00:12:11,010 --> 00:12:13,450 for it to have formed in the first place. 200 00:12:18,250 --> 00:12:21,690 Abundant water on scorched Venus? 201 00:12:21,690 --> 00:12:23,420 Hard to imagine. 202 00:12:26,330 --> 00:12:29,330 But Dr. Lewis Dartnell thinks you can get a glimpse 203 00:12:29,330 --> 00:12:32,500 of a wet Venus here in Iceland. 204 00:12:35,910 --> 00:12:38,040 There's the possibility 205 00:12:38,040 --> 00:12:40,270 that, maybe, in the early solar system, 206 00:12:40,280 --> 00:12:43,040 there were not one, but two planets with oceans... 207 00:12:43,050 --> 00:12:47,150 Two water worlds... Earth and Venus. 208 00:12:47,150 --> 00:12:50,250 And if Venus did once have oceans, 209 00:12:50,250 --> 00:12:53,450 maybe they would've looked a lot like this here, 210 00:12:53,460 --> 00:12:57,220 with a raw, volcanic landscape 211 00:12:57,230 --> 00:12:58,630 descending down into the ocean 212 00:12:58,630 --> 00:13:01,300 with the waves lapping against the coastline, 213 00:13:01,300 --> 00:13:06,170 and maybe a overcast and a misty, hazy atmosphere, 214 00:13:06,170 --> 00:13:08,270 not unlike what we are seeing here today. 215 00:13:10,610 --> 00:13:13,570 But Venus couldn't hold on to its water. 216 00:13:17,780 --> 00:13:19,810 All of that water is gone. 217 00:13:19,820 --> 00:13:22,150 It's just gone. Where did it go? 218 00:13:22,150 --> 00:13:25,720 Something happened, either catastrophically or over time, 219 00:13:25,720 --> 00:13:29,520 to basically dry out this twin of the earth. 220 00:13:31,760 --> 00:13:34,500 The culprit was the young sun. 221 00:13:34,500 --> 00:13:38,630 Since its birth, it's grown stronger. 222 00:13:38,630 --> 00:13:40,500 Our sun, when we look out at it during the day, 223 00:13:40,500 --> 00:13:42,700 seems the same today as it was yesterday. 224 00:13:42,710 --> 00:13:44,340 But that's on a human time scale. 225 00:13:44,340 --> 00:13:45,440 On cosmic time scale, 226 00:13:45,440 --> 00:13:47,410 the sun has been getting hotter and hotter. 227 00:13:49,480 --> 00:13:53,880 Every billion years, the sun gets 10% hotter, 228 00:13:53,880 --> 00:13:57,250 slowly turning up the temperature on Venus. 229 00:14:00,460 --> 00:14:02,060 Not only that, 230 00:14:02,060 --> 00:14:07,900 Venus formed 26 million miles closer to our star. 231 00:14:07,900 --> 00:14:11,930 As it turns out, that distance to the sun was critical. 232 00:14:11,930 --> 00:14:14,470 It's just an unfortunate circumstance 233 00:14:14,470 --> 00:14:18,910 of being in the wrong place at the wrong time. 234 00:14:18,910 --> 00:14:21,380 Earth is far enough away from the sun 235 00:14:21,380 --> 00:14:23,140 to hold on to its water. 236 00:14:25,250 --> 00:14:29,020 But Venus can't take the heat. 237 00:14:29,020 --> 00:14:31,820 The intensity of its sunlight got sort of 238 00:14:31,820 --> 00:14:33,350 just a little bit too much. 239 00:14:33,360 --> 00:14:35,560 It passed this threshold where Venus 240 00:14:35,560 --> 00:14:39,730 couldn't hold its water on the surface anymore. 241 00:14:39,730 --> 00:14:41,560 As temperatures rise, 242 00:14:41,560 --> 00:14:45,900 the oceans start to evaporate. 243 00:14:45,900 --> 00:14:47,800 All of that water in the oceans, 244 00:14:47,800 --> 00:14:50,140 all of those millions of cubic miles of water, 245 00:14:50,140 --> 00:14:51,870 would become water vapor... 246 00:14:51,870 --> 00:14:54,710 Basically steam clouds covering the entire planet, 247 00:14:54,710 --> 00:14:58,450 hiding the surface from the outside. 248 00:14:58,450 --> 00:15:01,180 Water vapor is a greenhouse gas. 249 00:15:01,180 --> 00:15:04,850 The clouds covering Venus trap the sun's heat. 250 00:15:08,120 --> 00:15:12,930 Temperatures on the surface rise. 251 00:15:12,930 --> 00:15:17,930 But the process can't go on forever, 252 00:15:17,930 --> 00:15:20,570 because the clouds of water vapor in the atmosphere 253 00:15:20,570 --> 00:15:24,100 start to disappear, 254 00:15:24,110 --> 00:15:27,040 ripped away by the solar wind. 255 00:15:29,280 --> 00:15:31,880 Over time, if a water molecule was in the upper part 256 00:15:31,880 --> 00:15:33,180 of Venus' atmosphere, 257 00:15:33,180 --> 00:15:35,280 light from the sun could break it apart 258 00:15:35,280 --> 00:15:37,420 into oxygen and hydrogen. 259 00:15:37,420 --> 00:15:40,950 And then, the solar wind could blow that stuff away. 260 00:15:44,960 --> 00:15:47,390 But that is just the beginning. 261 00:15:47,400 --> 00:15:49,730 Without its water vapor to trap heat, 262 00:15:49,730 --> 00:15:53,930 the temperature stops rising temporarily. 263 00:15:55,700 --> 00:15:57,370 Soon, a new force 264 00:15:57,370 --> 00:16:01,310 will send surface temperatures rocketing again. 265 00:16:01,310 --> 00:16:03,840 It will become so hot, 266 00:16:03,850 --> 00:16:06,650 metal snow will fall. 267 00:16:11,950 --> 00:16:13,550 When I think of Venus, 268 00:16:13,560 --> 00:16:16,760 the words "hot," "hazy," and "dead zone" 269 00:16:16,760 --> 00:16:18,030 come to mind... 270 00:16:18,030 --> 00:16:20,890 The exact opposite of our planet. 271 00:16:20,900 --> 00:16:23,500 But scientists believe that one day, 272 00:16:23,500 --> 00:16:26,200 these might be the words to describe earth. 273 00:16:26,200 --> 00:16:29,770 By studying volcanoes, you can start to understand why. 274 00:16:32,910 --> 00:16:34,710 Four billion years ago, 275 00:16:34,710 --> 00:16:38,010 Venus and earth were twins with oceans. 276 00:16:38,010 --> 00:16:43,280 But soon, the two planets' paths diverged. 277 00:16:43,290 --> 00:16:47,020 The growing sun burned off Venus' oceans... 278 00:16:47,020 --> 00:16:51,730 A terrible omen for earth. 279 00:16:51,730 --> 00:16:53,230 On the planet Venus, 280 00:16:53,230 --> 00:16:56,330 we think there could have been oceans, lakes, water, and rain. 281 00:16:56,330 --> 00:17:00,470 But all of that came to an end. 282 00:17:00,470 --> 00:17:03,670 That tells you that the earth's environment has to change, too. 283 00:17:03,670 --> 00:17:04,770 Nothing is forever. 284 00:17:07,780 --> 00:17:09,540 A few billion years ago, 285 00:17:09,550 --> 00:17:10,980 when you looked in our solar system, 286 00:17:10,980 --> 00:17:12,750 you might have seen two earths. 287 00:17:12,750 --> 00:17:15,850 Well, a few billion years from now, in the future, 288 00:17:15,850 --> 00:17:17,550 you might look at our solar system 289 00:17:17,550 --> 00:17:19,620 and see two Venuses. 290 00:17:22,260 --> 00:17:27,660 So we can look to Venus' past and see our fate. 291 00:17:27,660 --> 00:17:30,460 We know that temperatures skyrocketed, 292 00:17:30,470 --> 00:17:33,570 and the scarred surface hints at why. 293 00:17:35,570 --> 00:17:38,940 In Hawaii, planetary geologist Jani Radebaugh 294 00:17:38,940 --> 00:17:42,910 studies the islands' volcanoes. 295 00:17:42,910 --> 00:17:46,750 These volcanoes are a perfect model for early Venus. 296 00:17:50,020 --> 00:17:53,590 What we're seeing out here are lava flows 297 00:17:53,590 --> 00:17:56,990 encroaching on the town of Pahoa, 298 00:17:56,990 --> 00:17:59,890 come all the way down from the Pu'u 'o'o vent 299 00:17:59,900 --> 00:18:04,000 which is about 15 miles away. 300 00:18:04,000 --> 00:18:05,870 Oh, there's hot. You can see that hot stuff. 301 00:18:05,870 --> 00:18:07,600 You can see hot. Quick, quick, quick, quick. 302 00:18:07,600 --> 00:18:09,940 Right there. 303 00:18:09,940 --> 00:18:11,210 It's really beautiful. 304 00:18:14,180 --> 00:18:16,380 Hawaii's volcanic lava fields 305 00:18:16,380 --> 00:18:21,450 look like Venus in miniature. 306 00:18:21,450 --> 00:18:24,990 Both produce the same kind of runny lava, 307 00:18:24,990 --> 00:18:27,590 building flat, shield-like volcanoes. 308 00:18:29,730 --> 00:18:30,960 The big difference is 309 00:18:30,960 --> 00:18:34,460 there are only five active volcanoes on Hawaii. 310 00:18:38,030 --> 00:18:42,300 Venus is covered in them. 311 00:18:42,300 --> 00:18:44,540 One thing that really jumps out all around the planet 312 00:18:44,540 --> 00:18:48,480 is the number and variety of volcanoes. 313 00:18:48,480 --> 00:18:53,310 I mean, Venus could almost be nicknamed "volcano world." 314 00:18:53,320 --> 00:18:55,220 But it's not the erupting lava 315 00:18:55,220 --> 00:18:57,080 that turns up the heat. 316 00:18:57,090 --> 00:18:58,850 It's what comes out with it. 317 00:18:58,850 --> 00:19:01,160 When you think back to the histories of Venus, 318 00:19:01,160 --> 00:19:02,523 I think we must have seen a landscape 319 00:19:02,530 --> 00:19:04,320 very similar to this one, 320 00:19:04,330 --> 00:19:06,360 where you have massive amounts of lava 321 00:19:06,360 --> 00:19:08,230 flowing out of the surface, 322 00:19:08,230 --> 00:19:10,530 dumping huge amounts of gases into the atmosphere, 323 00:19:10,530 --> 00:19:13,230 carbon dioxide, tons of the gas into the atmosphere 324 00:19:13,240 --> 00:19:15,270 every single day. 325 00:19:15,270 --> 00:19:17,140 It would have been amazing to see. 326 00:19:23,280 --> 00:19:25,080 Up close on the surface, 327 00:19:25,080 --> 00:19:27,980 Jani can see the origin of the gases. 328 00:19:30,550 --> 00:19:33,450 If we look behind us, we can see volcanic gases 329 00:19:33,460 --> 00:19:35,090 gushing out of steam vents. 330 00:19:35,090 --> 00:19:37,590 We've got carbon dioxide being delivered to the atmosphere. 331 00:19:37,590 --> 00:19:40,030 It's exactly like what has happened on Venus. 332 00:19:42,830 --> 00:19:45,000 Carbon dioxide has been delivered out of volcanoes 333 00:19:45,000 --> 00:19:49,500 over and over and over again throughout its history, 334 00:19:49,510 --> 00:19:50,640 so that now we have 335 00:19:50,640 --> 00:19:53,810 just a tremendously thick, dense atmosphere. 336 00:19:55,710 --> 00:19:58,210 The net result of all of these volcanic gases 337 00:19:58,210 --> 00:20:01,950 pouring out of volcanoes, major greenhouse gases, 338 00:20:01,950 --> 00:20:03,220 is that they have been absorbing heat 339 00:20:03,220 --> 00:20:06,050 for billions of years of the history of Venus. 340 00:20:06,060 --> 00:20:08,490 The temperature has been gradually creeping up 341 00:20:08,490 --> 00:20:12,890 until, today, the surface of Venus is 900 degrees. 342 00:20:14,900 --> 00:20:16,500 It's like if you go into your kitchen 343 00:20:16,500 --> 00:20:18,530 and set your oven to broil, 344 00:20:18,530 --> 00:20:21,030 wait a couple of minutes and stick your head in it, 345 00:20:21,040 --> 00:20:23,940 and even that's not quite hot enough. 346 00:20:23,940 --> 00:20:27,370 It's a crazy, horrible, hellish spot. 347 00:20:32,580 --> 00:20:38,490 It's hard to imagine such extreme temperatures. 348 00:20:38,490 --> 00:20:40,520 But probes orbiting the planet 349 00:20:40,520 --> 00:20:46,130 revealed just how insanely hot it is. 350 00:20:46,130 --> 00:20:48,060 Scientists studying the images 351 00:20:48,060 --> 00:20:53,600 noticed something strange on the planet's mountains. 352 00:20:53,600 --> 00:20:55,470 It looks like, on the mountains, 353 00:20:55,470 --> 00:20:57,910 that there's apparently snow-like structures. 354 00:21:00,510 --> 00:21:05,380 But this is unlike any snow found on earth. 355 00:21:05,380 --> 00:21:08,650 So, if you look at the white-peaked mountains of Venus, 356 00:21:08,650 --> 00:21:10,120 you would think that it was snow, 357 00:21:10,120 --> 00:21:12,250 but it's actually metals that have rained down 358 00:21:12,250 --> 00:21:14,790 and deposited on the top of those mountains. 359 00:21:17,860 --> 00:21:20,590 Metals like bismuth and lead melt. 360 00:21:22,830 --> 00:21:25,670 Then, they evaporate into the atmosphere. 361 00:21:28,870 --> 00:21:31,840 As they rise, they cool 362 00:21:31,840 --> 00:21:36,640 until they finally fall like snow on the mountaintops. 363 00:21:38,680 --> 00:21:40,910 It's pretty insane... Raining metals. 364 00:21:40,920 --> 00:21:44,320 Where would you ever think about that existing? 365 00:21:44,320 --> 00:21:45,590 On Venus. 366 00:21:48,920 --> 00:21:50,260 In the future, 367 00:21:50,260 --> 00:21:54,490 metallic snow is forecast for earth, too. 368 00:21:54,500 --> 00:21:58,830 And our scorching mountain caps will glitter like Venus. 369 00:22:02,470 --> 00:22:07,610 But Venus tells us that things will get even worse. 370 00:22:11,550 --> 00:22:16,680 The atmosphere will grow heavy enough to crush cars. 371 00:22:22,790 --> 00:22:24,590 Earth and Venus... 372 00:22:24,590 --> 00:22:27,790 In the beginning, they were not so different. 373 00:22:27,800 --> 00:22:30,660 But these two planets have such similar births, 374 00:22:30,670 --> 00:22:33,700 how has earth been able to defend itself 375 00:22:33,700 --> 00:22:37,300 against the gruesome forces that so changed Venus? 376 00:22:37,310 --> 00:22:40,970 The answers are found in our atmosphere. 377 00:22:44,210 --> 00:22:47,480 Earth and Venus were born twins, 378 00:22:47,480 --> 00:22:49,880 but they took different paths. 379 00:22:49,890 --> 00:22:53,920 Earth slowly evolved into a habitable world. 380 00:22:57,360 --> 00:23:01,030 Venus was covered in thick volcanic gases, 381 00:23:01,030 --> 00:23:03,160 trapping the sun's heat. 382 00:23:03,170 --> 00:23:07,700 Temperatures Rose to 900 degrees. 383 00:23:11,210 --> 00:23:12,710 Extreme temperatures 384 00:23:12,710 --> 00:23:15,640 weren't the only problem on Venus' surface. 385 00:23:18,950 --> 00:23:24,150 The thick clouds of gas kept on building up. 386 00:23:24,150 --> 00:23:28,960 A 155-mile-deep layer of carbon dioxide 387 00:23:28,960 --> 00:23:31,330 piles up around the planet. 388 00:23:31,330 --> 00:23:33,860 We don't think about gases as weighing anything, 389 00:23:33,860 --> 00:23:35,430 but they actually do. 390 00:23:35,430 --> 00:23:37,930 Trillions and trillions of tons 391 00:23:37,930 --> 00:23:41,470 of gas press downwards. 392 00:23:41,470 --> 00:23:44,270 There is simply so much air on Venus 393 00:23:44,270 --> 00:23:46,370 that, on the surface, it's pushing down 394 00:23:46,380 --> 00:23:47,810 with a huge amount of force. 395 00:23:47,810 --> 00:23:50,840 Well, atmospheric pressure on Venus is a monster. 396 00:23:50,850 --> 00:23:53,810 Think about it this way. 397 00:23:53,820 --> 00:23:55,750 All right, car. 398 00:23:55,750 --> 00:23:57,620 It's time for you to be crushed, baby. 399 00:24:04,090 --> 00:24:06,030 If you're on Venus, you're gonna have 400 00:24:06,030 --> 00:24:09,400 155 miles of atmosphere above your head. 401 00:24:09,400 --> 00:24:10,630 As a result, 402 00:24:10,630 --> 00:24:13,830 atmospheric pressure is 90 times that on earth. 403 00:24:13,840 --> 00:24:19,870 So, on earth, it's about 14.6 pounds per square inch. 404 00:24:19,880 --> 00:24:23,840 On Venus, we're talking about 1,300 pounds per square inch. 405 00:24:23,850 --> 00:24:26,680 So, if you're driving your car in Venus, 406 00:24:26,680 --> 00:24:28,620 this is what might happen. 407 00:24:32,550 --> 00:24:35,960 This crusher delivers the same force 408 00:24:35,960 --> 00:24:38,690 as the weight of Venus' atmosphere. 409 00:24:38,690 --> 00:24:41,130 This is pretty serious stuff. 410 00:24:47,770 --> 00:24:49,770 And this is why it's so hard on Venus. 411 00:24:49,770 --> 00:24:51,270 You get down to the surface, 412 00:24:51,270 --> 00:24:54,310 you have the crushing atmosphere to deal with. 413 00:24:57,950 --> 00:24:59,950 The extreme pressure and heat 414 00:24:59,950 --> 00:25:04,280 makes Venus nearly impossible to explore. 415 00:25:09,260 --> 00:25:14,190 Only one nation has ever gotten a probe to the planet's surface. 416 00:25:17,200 --> 00:25:19,770 Truly, one of the engineering triumphs of the human race 417 00:25:19,770 --> 00:25:22,040 was the Soviet union's Venera program. 418 00:25:22,040 --> 00:25:26,040 The Russians sent over a dozen probes to the planet Venus. 419 00:25:26,040 --> 00:25:28,710 And only a few of them were able to survive long enough 420 00:25:28,710 --> 00:25:31,240 to even be able to take pictures from the surface. 421 00:25:34,280 --> 00:25:36,620 The probe that sent back these images 422 00:25:36,620 --> 00:25:39,720 was crushed and burnt out in 90 minutes. 423 00:25:42,460 --> 00:25:43,720 Some day in the future, 424 00:25:43,730 --> 00:25:46,190 there are going to be interplanetary tour guides 425 00:25:46,200 --> 00:25:48,500 taking people to every planet in the solar system. 426 00:25:48,500 --> 00:25:51,570 And you can imagine going to Saturn and seeing the rings 427 00:25:51,570 --> 00:25:53,970 and Jupiter and it's panoply of moons. 428 00:25:53,970 --> 00:25:55,800 There are all these great tourist attractions 429 00:25:55,800 --> 00:25:56,970 in the solar system. 430 00:25:56,970 --> 00:26:01,010 At the very bottom of that list is Venus. 431 00:26:01,010 --> 00:26:03,510 That is the last place in the solar system 432 00:26:03,510 --> 00:26:05,310 I would ever want to visit. 433 00:26:07,820 --> 00:26:10,450 The sun's heat and volcanic gases 434 00:26:10,450 --> 00:26:14,320 have transformed Venus into a nightmarish world. 435 00:26:18,660 --> 00:26:23,130 So, why hasn't earth followed the same path? 436 00:26:23,130 --> 00:26:26,700 That's because earth formed farther away from the sun, 437 00:26:26,700 --> 00:26:31,610 staying cool enough to hold on to its oceans. 438 00:26:31,610 --> 00:26:34,270 Oceans do a lot of things for us on earth 439 00:26:34,280 --> 00:26:36,610 because not only, obviously, are we water creatures, 440 00:26:36,610 --> 00:26:40,280 and we depend on the water cycle for our existence 441 00:26:40,280 --> 00:26:41,410 in so many ways, 442 00:26:41,420 --> 00:26:43,720 but people don't realize the oceans also help 443 00:26:43,720 --> 00:26:46,290 to regulate the climate of earth. 444 00:26:46,290 --> 00:26:49,360 Our oceans are full of tiny creatures 445 00:26:49,360 --> 00:26:51,730 that eat carbon dioxide. 446 00:26:54,630 --> 00:26:57,600 Richard Zeebe from the university of Hawaii 447 00:26:57,600 --> 00:27:02,270 is diving on the island's coral reefs. 448 00:27:02,270 --> 00:27:05,040 He's studying how tiny marine organisms 449 00:27:05,040 --> 00:27:10,010 turn carbon dioxide into rock. 450 00:27:10,010 --> 00:27:12,110 What you see here as this white stuff, 451 00:27:12,110 --> 00:27:14,280 this is what we call calcium carbonate. 452 00:27:14,280 --> 00:27:16,780 And on top of this, where you see these brown layers, 453 00:27:16,790 --> 00:27:19,220 this is essentially the living organism. 454 00:27:19,220 --> 00:27:21,390 This is the coral itself. 455 00:27:21,390 --> 00:27:23,260 It takes calcium out of the seawater 456 00:27:23,260 --> 00:27:25,030 and takes carbonate out of the seawater, 457 00:27:25,030 --> 00:27:29,400 combines them, and makes this piece of calcium carbonate. 458 00:27:29,400 --> 00:27:32,500 There's over 70 million billion tons 459 00:27:32,500 --> 00:27:36,500 of carbon locked up in carbonate rocks. 460 00:27:36,510 --> 00:27:38,840 This helps regulate carbon dioxide levels 461 00:27:38,840 --> 00:27:43,480 in the atmosphere, keeping temperatures from rising. 462 00:27:43,480 --> 00:27:47,080 If all the carbon that is being locked up in carbonate rocks 463 00:27:47,080 --> 00:27:50,980 in these corals would be put into the atmosphere as co2, 464 00:27:50,990 --> 00:27:53,320 that would be certainly bad news for us. 465 00:27:53,320 --> 00:27:55,460 Currently, our carbon cycle 466 00:27:55,460 --> 00:27:58,660 helps stabilize our climate. 467 00:27:58,660 --> 00:28:02,400 But in the future, this won't be able to save us. 468 00:28:07,270 --> 00:28:10,600 Forces far greater than the ones at work on earth 469 00:28:10,610 --> 00:28:12,840 will overpower our systems. 470 00:28:15,510 --> 00:28:19,750 Like Venus, our oceans will burn off. 471 00:28:19,750 --> 00:28:21,650 Temperatures will rocket 472 00:28:21,650 --> 00:28:26,020 as our live-giving sun becomes a monster. 473 00:28:32,890 --> 00:28:34,790 By looking at Venus' past, 474 00:28:34,800 --> 00:28:37,230 we can get a glimpse into earth's future. 475 00:28:37,230 --> 00:28:39,170 And it doesn't look bright. 476 00:28:39,170 --> 00:28:41,070 One of our best planetary features 477 00:28:41,070 --> 00:28:43,400 might become our worst enemy. 478 00:28:45,470 --> 00:28:47,640 Venus' hellish landscape 479 00:28:47,640 --> 00:28:51,340 is a glimpse into earth's future. 480 00:28:51,350 --> 00:28:52,780 There will be no more rain. 481 00:28:52,780 --> 00:28:54,280 There will be no more oceans. 482 00:28:54,280 --> 00:28:57,180 This wonderful, life-friendly environment we enjoy now 483 00:28:57,190 --> 00:29:00,590 just won't be here in some hundreds of millions of years. 484 00:29:05,560 --> 00:29:09,300 Right now, we live just the right distance from the sun, 485 00:29:09,300 --> 00:29:10,730 where it's just the right temperature 486 00:29:10,730 --> 00:29:13,300 for water to exist as a liquid. 487 00:29:16,040 --> 00:29:22,510 But that's going to change, just as it did for Venus. 488 00:29:22,510 --> 00:29:24,840 Venus started off, probably, in the habitable zone. 489 00:29:24,850 --> 00:29:28,550 And then the inner limit of the habitable zone crossed 490 00:29:28,550 --> 00:29:30,550 the distance of Venus' orbit. 491 00:29:30,550 --> 00:29:33,150 Well, it's gonna cross the distance of earth's orbit, too. 492 00:29:33,150 --> 00:29:35,420 There is an expiration date to the earth. 493 00:29:35,420 --> 00:29:37,720 And that's due to the sun's evolution. 494 00:29:40,260 --> 00:29:45,730 Ever since its birth, the sun has been getting hotter. 495 00:29:45,730 --> 00:29:50,440 That increased heat devastated Venus. 496 00:29:50,440 --> 00:29:55,610 And, in the future, it will destroy earth. 497 00:29:55,610 --> 00:29:57,680 In 1.1 billion years, 498 00:29:57,680 --> 00:30:02,080 the sun is 10% hotter than today. 499 00:30:02,080 --> 00:30:06,520 The oceans start to evaporate into thick clouds, 500 00:30:06,520 --> 00:30:10,460 which trap more of the sun's heat. 501 00:30:10,460 --> 00:30:14,490 Catastrophically, very rapidly on a geological time scale, 502 00:30:14,500 --> 00:30:17,530 the oceans will put so much water vapor into the atmosphere 503 00:30:17,530 --> 00:30:19,970 that we will get a runaway greenhouse effect. 504 00:30:21,400 --> 00:30:24,170 The clouds forming in the atmosphere 505 00:30:24,170 --> 00:30:26,340 trap more and more heat, 506 00:30:26,340 --> 00:30:29,110 driving temperatures even higher. 507 00:30:31,650 --> 00:30:35,180 Spiraling temperatures cause more evaporation, 508 00:30:35,180 --> 00:30:37,550 so the clouds get thicker. 509 00:30:39,790 --> 00:30:42,790 Which led to more heating, which led to more evaporation. 510 00:30:42,790 --> 00:30:44,190 And you can see where this is going. 511 00:30:44,190 --> 00:30:47,190 It's a vicious cycle. It's a positive feedback. 512 00:30:49,960 --> 00:30:53,070 We have all of this water that will go into the atmosphere, 513 00:30:53,070 --> 00:30:56,540 covering the earth and shrouding it in, basically, steam. 514 00:31:00,680 --> 00:31:04,680 Earth has had oceans for billions of years, 515 00:31:04,680 --> 00:31:08,180 but it could lose them in just 10,000. 516 00:31:10,920 --> 00:31:12,890 All of the water in the earth's oceans 517 00:31:12,890 --> 00:31:14,150 will be in the atmosphere. 518 00:31:14,160 --> 00:31:17,060 We'll have an incredibly dense cloud cover system 519 00:31:17,060 --> 00:31:18,590 where the temperatures on earth 520 00:31:18,590 --> 00:31:22,660 will be approaching 1,000 degrees. 521 00:31:22,660 --> 00:31:24,500 Like Venus in the past, 522 00:31:24,500 --> 00:31:26,970 earth will get hotter and hotter. 523 00:31:26,970 --> 00:31:32,040 But unlike Venus, which topped out at 900 degrees, 524 00:31:32,040 --> 00:31:35,310 temperatures on earth will keep on climbing. 525 00:31:39,050 --> 00:31:45,380 Venus lost its water to space, blasted away by the solar wind. 526 00:31:45,390 --> 00:31:49,690 But earth holds on to its water. 527 00:31:49,690 --> 00:31:53,360 It's protected by our magnetic shield. 528 00:31:53,360 --> 00:31:57,960 But that's no longer a good thing. 529 00:31:57,970 --> 00:32:00,000 That water will stay with us. 530 00:32:00,000 --> 00:32:04,840 The earth could have a thicker, hotter greenhouse atmosphere 531 00:32:04,840 --> 00:32:08,640 than Venus does today, much worse. 532 00:32:09,880 --> 00:32:12,440 This huge volume of water vapor 533 00:32:12,450 --> 00:32:17,150 all pushes down on the surface, 534 00:32:17,150 --> 00:32:20,220 around 4,000 pounds. 535 00:32:20,220 --> 00:32:22,920 That's the weight of the average American car 536 00:32:22,920 --> 00:32:26,390 pressing down on every square inch of earth. 537 00:32:29,830 --> 00:32:32,300 Surface pressure goes through the roof, 538 00:32:32,300 --> 00:32:37,600 reaching 270 times higher than today. 539 00:32:37,610 --> 00:32:40,340 It is ironic to think that the water on earth 540 00:32:40,340 --> 00:32:43,240 will one day help contribute to its demise. 541 00:32:43,240 --> 00:32:46,650 After all, the water has been the source of life on earth. 542 00:32:46,650 --> 00:32:49,350 But, in the far future, it'll become our enemy. 543 00:32:52,220 --> 00:32:55,550 And with no oceans and their microscopic creatures 544 00:32:55,560 --> 00:32:58,220 to absorb the carbon dioxide, 545 00:32:58,230 --> 00:33:03,530 there is nothing to hold back the rising temperatures. 546 00:33:03,530 --> 00:33:08,000 There's no way back for the earth. 547 00:33:15,080 --> 00:33:17,280 In 1.2 billion years, 548 00:33:17,280 --> 00:33:23,550 a probe visiting earth would see an alien world... 549 00:33:23,550 --> 00:33:26,320 A scorched, barren landscape. 550 00:33:29,520 --> 00:33:32,890 The pressure is crushing. 551 00:33:32,890 --> 00:33:37,900 Temperatures reach 1,200 degrees. 552 00:33:37,900 --> 00:33:43,540 Molten metals snow down on the mountaintops. 553 00:33:43,540 --> 00:33:47,240 It's so hot that granite rock melts. 554 00:33:49,940 --> 00:33:54,210 The surface liquefies. 555 00:33:54,220 --> 00:33:56,880 At that point, the earth will become a molten ball 556 00:33:56,880 --> 00:34:00,450 very similar to what it was at the very beginning. 557 00:34:00,450 --> 00:34:04,820 Earth and Venus started as twins. 558 00:34:04,830 --> 00:34:09,390 Venus was destroyed by rampant global warming. 559 00:34:09,400 --> 00:34:15,070 Earth will follow the same path, then overtake it. 560 00:34:15,070 --> 00:34:18,240 It is inevitable that the earth will someday 561 00:34:18,240 --> 00:34:21,240 not only be like Venus, but actually put it to shame. 562 00:34:23,940 --> 00:34:31,450 In 1.3 billion years, earth could hit 3,600 degrees, 563 00:34:31,450 --> 00:34:34,220 four times hotter than Venus. 564 00:34:36,820 --> 00:34:39,730 It will be the hottest and deadliest planet 565 00:34:39,730 --> 00:34:41,690 in our solar system. 566 00:34:46,030 --> 00:34:50,870 For earth and its inhabitants, it's the end of the road. 567 00:34:50,870 --> 00:34:53,870 We couldn't survive the extreme temperatures 568 00:34:53,870 --> 00:34:56,110 or crushing pressure. 569 00:34:56,110 --> 00:35:00,010 Maybe we'll escape to space. 570 00:35:00,010 --> 00:35:05,980 But there's one absolutely crazy way we could stay here... 571 00:35:05,990 --> 00:35:10,420 Move our planet further away from the sun. 572 00:35:16,360 --> 00:35:19,930 I've seen my fair share of crazy ideas at NASA 573 00:35:19,930 --> 00:35:21,470 that end up being the solution 574 00:35:21,470 --> 00:35:23,170 to a big problem. 575 00:35:23,170 --> 00:35:25,670 During my final mission aboard Atlantis, 576 00:35:25,670 --> 00:35:28,270 while a making a repair to the Hubble space telescope, 577 00:35:28,280 --> 00:35:31,840 I stripped a screw and was completely stuck. 578 00:35:31,850 --> 00:35:34,980 Mission control suggested using brute force 579 00:35:34,980 --> 00:35:36,850 and a simple piece of tape. 580 00:35:36,850 --> 00:35:40,350 Likewise, scientists have come up with an unusual solution 581 00:35:40,350 --> 00:35:42,990 to save earth from ending up like Venus. 582 00:35:48,000 --> 00:35:49,830 Earth of the future will become 583 00:35:49,830 --> 00:35:53,830 the most inhospitable planet in the solar system. 584 00:35:53,830 --> 00:35:59,670 Its ocean will boil off, and its surface will melt. 585 00:35:59,670 --> 00:36:01,310 A billion years from now, 586 00:36:01,310 --> 00:36:06,880 earth could be an unimaginably terrible place. 587 00:36:06,880 --> 00:36:09,980 Right now, today, Venus is the evil twin of earth. 588 00:36:09,980 --> 00:36:11,620 But in the distance future, 589 00:36:11,620 --> 00:36:14,720 earth could be the evil twin of Venus. 590 00:36:14,720 --> 00:36:16,260 Earth's surface temperature 591 00:36:16,260 --> 00:36:18,890 will reach 3,600 degrees 592 00:36:18,890 --> 00:36:24,400 with pressure 270 times than today. 593 00:36:24,400 --> 00:36:26,030 At these kind of temperatures, 594 00:36:26,030 --> 00:36:29,570 where rock on the surface of the earth is molten, 595 00:36:29,570 --> 00:36:32,270 it's hard to imagine any place there could be life. 596 00:36:35,940 --> 00:36:38,210 But there is hope. 597 00:36:41,820 --> 00:36:44,120 Astrobiologist Lewis Dartnell thinks 598 00:36:44,120 --> 00:36:46,690 that some forms of life could survive 599 00:36:46,690 --> 00:36:50,690 such terrible conditions. 600 00:36:50,690 --> 00:36:54,530 We're here on top of a volcanic outcrop in Iceland 601 00:36:54,530 --> 00:36:57,660 with this howling Gale whistling past our ears, 602 00:36:57,670 --> 00:37:01,670 the stench of hydrogen sulfide, of sulfurous fumes, 603 00:37:01,670 --> 00:37:03,170 filling our nostrils. 604 00:37:03,170 --> 00:37:05,640 And this is about as close as you get can on earth 605 00:37:05,640 --> 00:37:08,670 to high up in the Venusian atmosphere. 606 00:37:08,680 --> 00:37:13,150 About 30, 35 miles above the surface of the planet Venus, 607 00:37:13,150 --> 00:37:15,250 the air pressure is about the same 608 00:37:15,250 --> 00:37:16,620 as on the earth's surface. 609 00:37:16,620 --> 00:37:20,450 The temperature is pretty similar, as well. 610 00:37:20,450 --> 00:37:24,620 But the cloud droplets are full of concentrated sulfuric acid, 611 00:37:24,630 --> 00:37:27,930 many, many times more concentrated than battery acid. 612 00:37:27,930 --> 00:37:32,100 It's a hostile, horrible environment. 613 00:37:32,100 --> 00:37:33,900 But bizarrely enough, 614 00:37:33,900 --> 00:37:36,170 there's good reasons to think that there may be life, 615 00:37:36,170 --> 00:37:38,870 Venusian life, high up in the clouds 616 00:37:38,870 --> 00:37:42,880 that are kind of high-altitude aerial biosphere. 617 00:37:45,550 --> 00:37:48,510 High above Venus, there are nutrients, 618 00:37:48,520 --> 00:37:53,390 solar energy, and traces of water. 619 00:37:53,390 --> 00:37:57,720 If life can live up there, then perhaps it might survive 620 00:37:57,730 --> 00:38:02,360 high up in the clouds of future earth. 621 00:38:02,360 --> 00:38:06,100 You can easily imagine these micro-organisms evaporating 622 00:38:06,100 --> 00:38:08,270 in water particles and being transported 623 00:38:08,270 --> 00:38:10,600 to the upper atmosphere. 624 00:38:10,600 --> 00:38:15,110 Even though it turned into this toxic greenhouse planet, 625 00:38:15,110 --> 00:38:16,980 life could potentially still survive 626 00:38:16,980 --> 00:38:18,710 in that upper atmosphere. 627 00:38:21,720 --> 00:38:24,050 But what about us? 628 00:38:24,050 --> 00:38:26,250 We couldn't survive the high temperatures 629 00:38:26,250 --> 00:38:28,620 or pressures at the surface. 630 00:38:28,620 --> 00:38:32,420 And a life in the clouds doesn't seem likely. 631 00:38:32,430 --> 00:38:35,760 What's our future? 632 00:38:35,760 --> 00:38:38,060 If there was this life on Venus, 633 00:38:38,070 --> 00:38:40,300 clearly, they weren't advanced enough 634 00:38:40,300 --> 00:38:42,630 to stop the changes in their atmosphere 635 00:38:42,640 --> 00:38:44,700 that led to Venus' current state. 636 00:38:44,710 --> 00:38:46,670 The question is, are we? 637 00:38:48,840 --> 00:38:51,240 Perhaps we will leave our planet 638 00:38:51,250 --> 00:38:53,450 and find a new home. 639 00:38:56,620 --> 00:38:59,650 But there is a more outlandish solution... 640 00:38:59,650 --> 00:39:03,690 Stay on earth and move it farther from the sun. 641 00:39:03,690 --> 00:39:06,890 Moving the earth is at least imaginable because, in fact, 642 00:39:06,890 --> 00:39:09,060 as objects exchange gravitational energy, 643 00:39:09,060 --> 00:39:10,930 they move in or out in the solar system. 644 00:39:10,930 --> 00:39:12,360 It's happened to our planet. 645 00:39:12,370 --> 00:39:14,900 So I could imagine engineering things 646 00:39:14,900 --> 00:39:17,570 where we directed large asteroids and comets 647 00:39:17,570 --> 00:39:19,770 close to the earth, but not to hit it. 648 00:39:23,110 --> 00:39:25,440 The gravity from these large objects 649 00:39:25,450 --> 00:39:29,250 would slowly alter our orbit. 650 00:39:29,250 --> 00:39:30,920 Gravitational energy would be exchanged, 651 00:39:30,920 --> 00:39:33,620 and the earth could slowly move out. 652 00:39:37,160 --> 00:39:38,720 Each gravitational jolt 653 00:39:38,730 --> 00:39:43,330 would only move earth a short distance. 654 00:39:43,330 --> 00:39:46,970 But do it thousands or millions of times, 655 00:39:46,970 --> 00:39:50,300 and we could push the earth away from the sun... 656 00:39:50,300 --> 00:39:53,440 In theory, at least. 657 00:39:53,440 --> 00:39:56,140 Over a billion-year period, it's possible to imagine. 658 00:39:56,140 --> 00:39:58,140 It would require incredible technology 659 00:39:58,150 --> 00:40:00,310 and incredible coordination. 660 00:40:00,310 --> 00:40:01,880 The technology is possible. 661 00:40:01,880 --> 00:40:04,750 Whether humanity as a species could ever coordinate it 662 00:40:04,750 --> 00:40:08,720 is something I'm a little more skeptical about. 663 00:40:08,720 --> 00:40:12,420 It's a crazy option, but if we don't do something, 664 00:40:12,430 --> 00:40:15,230 earth and all of us will die, 665 00:40:15,230 --> 00:40:19,000 and we'll become just like Venus. 666 00:40:23,100 --> 00:40:25,000 Earth and Venus were probably born together 667 00:40:25,010 --> 00:40:27,770 as identical twins, but then their paths diverged. 668 00:40:27,780 --> 00:40:30,980 But now, lifetime is gonna send that cycle all the way back, 669 00:40:30,980 --> 00:40:35,550 and they'll die as identical twins again. 670 00:40:35,550 --> 00:40:37,420 In the grand scheme of things, 671 00:40:37,420 --> 00:40:39,450 they'll just be two charred twins 672 00:40:39,450 --> 00:40:43,020 spinning to oblivion in a backwater of the universe. 673 00:40:47,490 --> 00:40:51,460 On the cosmic scale, life is short. 674 00:40:53,470 --> 00:40:57,570 When you look at how earth evolved and how Venus evolved, 675 00:40:57,570 --> 00:40:59,400 you can see the difference, 676 00:40:59,410 --> 00:41:02,640 even though it's two almost twin planets, 677 00:41:02,640 --> 00:41:06,580 how life and habitability could change over time. 678 00:41:06,580 --> 00:41:11,520 So, habitability isn't always a permanent thing. 679 00:41:11,520 --> 00:41:12,720 On human scales, 680 00:41:12,720 --> 00:41:16,190 the universe seems the same every single day. 681 00:41:16,190 --> 00:41:19,090 But, of course, that's because human life 682 00:41:19,090 --> 00:41:20,190 and human civilization 683 00:41:20,190 --> 00:41:24,460 is but a brief instant in cosmic time. 684 00:41:24,470 --> 00:41:28,470 On cosmic scales, the universe evolves and changes, 685 00:41:28,470 --> 00:41:31,670 and that makes the history of the universe remarkable. 686 00:41:34,740 --> 00:41:38,840 Our tale of two planets converges in the end, 687 00:41:38,850 --> 00:41:43,780 a cautionary tale about forces beyond our control. 688 00:41:46,820 --> 00:41:50,490 Perhaps a billion years of learning from Venus 689 00:41:50,490 --> 00:41:54,890 will save us from the same terrible fate. 690 00:41:54,900 --> 00:41:57,900 Captions by vitac... www.Vitac.Com 691 00:41:57,900 --> 00:42:00,670 captions paid for by discovery communications 54217

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