WEBVTT 00:00:14.200 --> 00:00:17.600 Every year for just a few short months… 00:00:19.240 --> 00:00:23.160 …fresh water flows into the Okavango Delta… 00:00:27.680 --> 00:00:29.280 creating the perfect home… 00:00:31.360 --> 00:00:33.480 for a small family of elephants… 00:00:38.000 --> 00:00:42.280 and a playground for their two young calves… 00:00:44.520 --> 00:00:45.600 Bosigo… 00:00:47.680 --> 00:00:50.760 …and her baby cousin, Metsi. 00:00:59.440 --> 00:01:03.680 Bosigo and Metsi are only just beginning 00:01:03.760 --> 00:01:05.400 their love affair with water. 00:01:09.000 --> 00:01:10.320 But from now on, 00:01:11.200 --> 00:01:13.720 their lives will be defined by it. 00:01:15.960 --> 00:01:19.000 This one precious molecule… 00:01:21.400 --> 00:01:22.720 …delivered to Earth… 00:01:25.400 --> 00:01:29.640 …by the astonishing forces at work in our universe. 00:01:36.200 --> 00:01:38.560 It has transformed this planet… 00:01:41.760 --> 00:01:42.920 …into a haven… 00:01:48.600 --> 00:01:49.560 …for life. 00:02:26.200 --> 00:02:27.720 Summer has arrived. 00:02:30.360 --> 00:02:34.200 And what was paradise is no more. 00:02:37.360 --> 00:02:39.840 The fresh water that flooded the delta… 00:02:42.800 --> 00:02:44.760 only stays for a few months. 00:02:46.720 --> 00:02:48.800 And water holes are now vanishing. 00:02:50.520 --> 00:02:51.360 Fast. 00:02:58.520 --> 00:03:00.320 This means only one thing 00:03:00.400 --> 00:03:03.640 for the thousands of elephants who've been living here. 00:03:06.240 --> 00:03:08.080 It's time to move on. 00:03:21.960 --> 00:03:26.120 This has been the only home Metsi and Bosigo have ever known. 00:03:28.720 --> 00:03:32.200 But in a few weeks, all the water will be gone. 00:03:36.160 --> 00:03:40.000 So they must leave the delta with the rest of their family. 00:03:41.160 --> 00:03:43.120 A herd of females, 00:03:43.200 --> 00:03:46.200 sisters, aunts, and cousins, 00:03:48.080 --> 00:03:49.680 led by their grandmother, 00:03:50.760 --> 00:03:53.520 the great matriarch, Pula. 00:03:58.360 --> 00:04:02.440 They're embarking on a journey along with thousands of other families… 00:04:05.160 --> 00:04:06.400 out into the desert… 00:04:10.280 --> 00:04:11.600 in search of water. 00:04:18.840 --> 00:04:20.480 For the next eight months, 00:04:20.560 --> 00:04:24.840 they will migrate from water hole to water hole… 00:04:27.320 --> 00:04:30.160 and navigate ancient elephant trails… 00:04:31.200 --> 00:04:33.920 …using the matriarch Pula's knowledge, 00:04:35.320 --> 00:04:37.640 handed down to her through generations. 00:04:40.480 --> 00:04:43.040 The trek will put all their lives at risk. 00:04:45.080 --> 00:04:48.720 And they'll need every one of their exceptional senses… 00:04:48.800 --> 00:04:51.120 -…to endure the dangers. 00:04:55.640 --> 00:04:58.840 Making this journey is not a choice. 00:05:04.640 --> 00:05:07.080 Without water, they will die. 00:05:11.320 --> 00:05:13.880 Even on our blue planet, 00:05:13.960 --> 00:05:16.960 fresh liquid water is scarce. 00:05:20.160 --> 00:05:23.400 And if we search beyond the shores of our own planet… 00:05:25.480 --> 00:05:27.000 it's rarer still. 00:05:30.320 --> 00:05:32.880 Even the most arid desert on Earth 00:05:33.640 --> 00:05:38.240 is nothing compared to the rest of our solar system. 00:05:41.560 --> 00:05:44.080 In the cold outer reaches… 00:05:50.360 --> 00:05:52.720 …the only surface water is ice. 00:05:56.880 --> 00:05:59.320 Like Saturn's frozen moons… 00:06:01.640 --> 00:06:03.280 where fountains of ice 00:06:04.880 --> 00:06:07.400 shoot kilometers into space. 00:06:14.520 --> 00:06:17.800 Closer to the Sun on Mars, 00:06:18.720 --> 00:06:21.840 water is stripped away by savage solar winds. 00:06:32.640 --> 00:06:34.240 And on Venus, 00:06:34.320 --> 00:06:36.040 it simply boils away. 00:06:45.560 --> 00:06:48.320 There's only one world we know of 00:06:48.400 --> 00:06:51.800 that has the gift of liquid water on its surface. 00:06:57.120 --> 00:06:59.280 A pale blue dot. 00:07:00.920 --> 00:07:02.000 Our home… 00:07:08.160 --> 00:07:09.960 where right now, 00:07:10.800 --> 00:07:14.280 water is driving one particular family 00:07:14.800 --> 00:07:16.840 on a quest for survival. 00:07:24.600 --> 00:07:26.840 Just a month after leaving the delta, 00:07:27.920 --> 00:07:30.720 only a scattering of muddy pools remain. 00:07:34.840 --> 00:07:40.120 And they're getting fewer and farther apart each day. 00:07:43.840 --> 00:07:48.480 Pula is using her highly tuned memory to lead her family to a water hole. 00:07:55.040 --> 00:07:57.120 She can remember the exact route, 00:07:57.880 --> 00:07:59.480 even decades later. 00:08:03.680 --> 00:08:05.760 It's been a long day's march, 00:08:06.480 --> 00:08:09.640 and all of them are desperate for a drink. 00:08:13.800 --> 00:08:17.920 But so are the other 130,000 elephants 00:08:18.000 --> 00:08:19.600 that live in Botswana. 00:08:31.280 --> 00:08:34.800 The dry season has drawn herds from far and wide… 00:08:39.840 --> 00:08:42.000 …to this water hole. 00:08:52.160 --> 00:08:56.360 All competing for the same shrinking resource. 00:09:15.120 --> 00:09:19.240 The adults teach the young ones clever survival tricks, 00:09:20.000 --> 00:09:23.920 like how to skim a muddy pool to get the freshest water. 00:09:29.240 --> 00:09:34.000 And how to use some muddy water as refreshing sunscreen. 00:09:36.880 --> 00:09:40.800 Their wrinkly skin is perfect for trapping water and keeping cool. 00:09:49.480 --> 00:09:53.080 But Metsi and Bosigo are also learning… 00:09:56.120 --> 00:09:58.440 mud pools aren't just a place to drink. 00:10:00.080 --> 00:10:01.640 They're water parks too. 00:10:15.000 --> 00:10:16.960 With so many thirsty elephants, 00:10:17.480 --> 00:10:19.720 the water hole has been drained. 00:10:26.160 --> 00:10:28.000 Pula's family must press on… 00:10:31.840 --> 00:10:37.600 and try to make it to the next water hole before the blazing sun *s it dry. 00:10:40.720 --> 00:10:44.080 This battle between sun and scorched earth 00:10:44.160 --> 00:10:47.280 has raged ever since our world was born… 00:10:52.040 --> 00:10:56.000 when our blue planet was anything but blue. 00:11:04.160 --> 00:11:06.840 Four and a half billion years ago… 00:11:12.600 --> 00:11:15.160 Earth was in its infancy. 00:11:16.640 --> 00:11:18.920 A fireball of molten rock… 00:11:23.440 --> 00:11:27.360 …destined to become a dry, barren world. 00:11:31.440 --> 00:11:34.560 But millions of kilometers out in the coldest reaches 00:11:34.640 --> 00:11:35.880 of the solar system… 00:11:41.040 --> 00:11:42.720 water crystals were forming 00:11:43.680 --> 00:11:46.760 on the surface of dust particles. 00:11:54.480 --> 00:11:59.760 Over time, these grains of dust clumped together into asteroids. 00:12:01.520 --> 00:12:03.920 Millions and millions of them. 00:12:06.080 --> 00:12:09.600 And these became the asteroid belt. 00:12:11.240 --> 00:12:14.440 A vast expanse of icy rocks. 00:12:17.640 --> 00:12:21.880 Yet they've laid tantalizingly out of Earth's reach. 00:12:25.840 --> 00:12:27.680 As luck would have it, however, 00:12:28.400 --> 00:12:30.160 a giant was on the move. 00:12:39.080 --> 00:12:40.160 Young Jupiter. 00:12:41.160 --> 00:12:43.120 A monster of a planet. 00:12:48.080 --> 00:12:50.920 Forces within the turbulent inner solar system 00:12:51.640 --> 00:12:55.520 were slowly pulling it in toward the Sun. 00:13:00.760 --> 00:13:03.880 A flight path that brought it into a collision course 00:13:04.760 --> 00:13:06.440 with the asteroid belt. 00:13:22.080 --> 00:13:24.560 As it thundered through the asteroids… 00:13:28.480 --> 00:13:30.800 …its massive gravitational force 00:13:31.800 --> 00:13:34.000 flung rocks in every direction. 00:13:41.880 --> 00:13:46.160 And yet, from all this chaos and destruction 00:13:46.240 --> 00:13:49.040 came the ultimate cosmic gift. 00:13:55.120 --> 00:14:00.760 Icy, water-rich rocks were hurled towards the Earth… 00:14:06.360 --> 00:14:11.360 …bringing the promise of life one step closer. 00:14:15.720 --> 00:14:17.280 Over billions of years, 00:14:17.360 --> 00:14:21.480 asteroids were woven into the fabric of Earth as it formed. 00:14:25.680 --> 00:14:29.240 Caught in the turmoil wrought by Jupiter… 00:14:30.920 --> 00:14:34.120 …driven deep into the Earth by asteroids, 00:14:35.800 --> 00:14:39.800 water molecules did not have an easy journey getting here. 00:14:42.760 --> 00:14:45.160 And they still had a long way to go, 00:14:46.320 --> 00:14:49.320 imprisoned for millions of years, 00:14:50.200 --> 00:14:52.640 locked within Earth's molten core… 00:14:55.640 --> 00:14:57.400 waiting for another miracle… 00:15:00.600 --> 00:15:01.960 to set them free. 00:15:12.040 --> 00:15:15.960 Today, much of Earth's water is still trapped underground. 00:15:23.880 --> 00:15:28.120 So elephants have evolved special skills 00:15:28.200 --> 00:15:29.240 to find it. 00:15:39.400 --> 00:15:41.960 Even the muddy pools are empty. 00:15:43.240 --> 00:15:46.120 This dry season has become a full-on drought. 00:15:49.560 --> 00:15:51.880 But Pula has a superpower. 00:15:54.200 --> 00:15:55.720 Her incredible trunk, 00:15:57.240 --> 00:15:59.880 packed with millions of sense receptors… 00:16:02.000 --> 00:16:04.440 can smell water from kilometers away… 00:16:09.040 --> 00:16:12.880 and pinpoint its sources deep underground. 00:16:23.720 --> 00:16:25.080 But you have to dig for it. 00:16:33.880 --> 00:16:35.640 Metsi isn't a big digger. 00:16:40.840 --> 00:16:43.080 But Bosigo is a natural. 00:16:51.520 --> 00:16:54.680 And Metsi is offered a seat at the bar. 00:17:00.360 --> 00:17:02.640 These few sips won't last them long. 00:17:07.280 --> 00:17:09.880 But if water had stayed trapped in the Earth, 00:17:11.520 --> 00:17:13.240 there would be none to drink. 00:17:17.800 --> 00:17:19.680 There would be no elephants. 00:17:23.200 --> 00:17:25.280 No life at all. 00:17:37.800 --> 00:17:41.160 After water was delivered here by asteroids 00:17:41.240 --> 00:17:43.480 and consumed by the Earth… 00:17:45.640 --> 00:17:48.280 it was locked into the rock as crystals 00:17:50.200 --> 00:17:51.800 deep inside the planet. 00:17:57.560 --> 00:18:00.160 It stayed buried for millions of years, 00:18:01.160 --> 00:18:04.360 beneath a vast sea of magma. 00:18:12.920 --> 00:18:17.880 Until slowly but surely, Earth cooled. 00:18:21.360 --> 00:18:25.880 And its surface hardened to a thick crust. 00:18:29.680 --> 00:18:34.240 Then, finally, the boiling interior broke through. 00:18:43.720 --> 00:18:45.600 Enormous volcanoes 00:18:47.080 --> 00:18:50.880 blasted gas and vapor kilometers into the sky. 00:18:58.720 --> 00:19:01.520 At last, water molecules… 00:19:03.000 --> 00:19:04.200 …were set free… 00:19:11.080 --> 00:19:13.800 …and formed the first clouds. 00:19:18.480 --> 00:19:21.080 Growing and building for millions of years, 00:19:21.600 --> 00:19:23.400 becoming laden with water… 00:19:28.320 --> 00:19:31.120 …until the temperature dropped just enough… 00:19:38.920 --> 00:19:41.480 …for the very first raindrop… 00:19:46.920 --> 00:19:50.560 …to form and fall. 00:20:08.800 --> 00:20:11.000 What followed was a deluge… 00:20:16.240 --> 00:20:18.640 that lasted thousands of years. 00:20:30.040 --> 00:20:32.080 Puddles turned into rivers. 00:20:41.520 --> 00:20:42.720 Lakes… 00:20:44.400 --> 00:20:45.760 …became seas. 00:20:53.480 --> 00:20:57.560 And great oceans flooded Earth's surface. 00:21:15.920 --> 00:21:20.120 And here, water gave rise to something magical. 00:21:25.320 --> 00:21:26.840 The first life. 00:21:31.080 --> 00:21:33.680 From these first cells 00:21:35.000 --> 00:21:38.040 sprang every living thing. 00:21:40.640 --> 00:21:43.960 Water is the fundamental ingredient 00:21:44.040 --> 00:21:48.000 of every cell of every creature on Earth. 00:21:57.360 --> 00:21:58.440 And today… 00:22:01.320 --> 00:22:06.400 the herd still carries this ancient water within them. 00:22:18.040 --> 00:22:20.240 It transports nutrients and oxygen. 00:22:30.200 --> 00:22:32.000 It powers every heartbeat. 00:22:38.920 --> 00:22:41.160 And drives every breath. 00:22:46.640 --> 00:22:49.240 Life evolved because of water, 00:22:51.000 --> 00:22:54.960 which is why no life can survive without it. 00:23:01.920 --> 00:23:05.480 In Botswana, the drought is only getting worse. 00:23:11.080 --> 00:23:13.880 The elephants' world is on fire. 00:23:22.600 --> 00:23:25.520 The herd manages to escape the burning forest… 00:23:29.040 --> 00:23:31.320 but walks straight into a new threat. 00:23:37.560 --> 00:23:40.360 In this drought, everyone is suffering… 00:23:43.680 --> 00:23:46.160 …from thirst and hunger. 00:23:52.600 --> 00:23:56.960 And for lions, baby elephants would satisfy both. 00:24:14.200 --> 00:24:17.320 The adults rally around Metsi and Bosigo. 00:24:24.720 --> 00:24:26.960 It's enough to keep the threat at bay. 00:24:30.680 --> 00:24:32.880 But lions are patient creatures. 00:24:36.880 --> 00:24:40.400 And the herd still has to cross an unforgiving wasteland… 00:24:42.600 --> 00:24:44.280 before the next water hole. 00:24:48.520 --> 00:24:50.680 They need a lifeline. 00:24:53.760 --> 00:24:56.040 And the Earth provides it 00:24:57.720 --> 00:25:00.120 in the most unexpected of places. 00:25:05.320 --> 00:25:08.000 The acacia tree is a beacon of hope. 00:25:13.880 --> 00:25:16.800 And a haven for creatures of all kinds. 00:25:24.880 --> 00:25:28.320 Its long roots reach much deeper underground 00:25:28.400 --> 00:25:30.400 than an elephant could ever dig… 00:25:41.240 --> 00:25:43.360 …drawing water up to its branches… 00:25:47.360 --> 00:25:48.520 and leaves. 00:26:01.000 --> 00:26:04.480 It's just enough water to keep them going. 00:26:08.280 --> 00:26:10.840 Especially vital for Metsi's mother, 00:26:12.720 --> 00:26:14.320 still nursing her baby. 00:26:18.320 --> 00:26:21.800 But this is so much more than just a local oasis. 00:26:25.360 --> 00:26:28.480 It's the vital link in water's eternal cycle. 00:26:32.720 --> 00:26:36.800 The acacia tree connects ground and sky… 00:26:43.600 --> 00:26:46.080 …breathing oxygen and vapor into the air. 00:26:55.000 --> 00:26:56.480 Feeding clouds 00:26:56.560 --> 00:26:59.320 and powering water's journey around the planet. 00:27:07.400 --> 00:27:08.880 Ever since rain 00:27:10.120 --> 00:27:12.400 fed the first green shoots… 00:27:16.320 --> 00:27:18.840 and gave life to the first tree… 00:27:24.120 --> 00:27:27.720 …plants have made our planet habitable… 00:27:35.280 --> 00:27:37.680 …bringing a once barren ball of rock 00:27:39.440 --> 00:27:40.280 to life. 00:27:45.880 --> 00:27:48.760 But the gifts our universe bestows 00:27:50.320 --> 00:27:52.760 can also be taken away. 00:28:01.280 --> 00:28:02.760 A long time ago, 00:28:04.080 --> 00:28:05.680 there was another planet 00:28:06.680 --> 00:28:09.480 whose surface was covered in liquid water. 00:28:18.080 --> 00:28:20.600 A water world just like ours. 00:28:25.720 --> 00:28:28.440 The same forces that delivered water to Earth 00:28:29.440 --> 00:28:32.000 also gave it to Mars. 00:28:35.200 --> 00:28:37.440 With an atmosphere in place, 00:28:37.520 --> 00:28:38.640 clouds formed, 00:28:40.480 --> 00:28:41.480 rain fell, 00:28:43.000 --> 00:28:44.440 rivers flowed. 00:28:48.800 --> 00:28:52.160 And an ocean surged across its surface. 00:28:57.240 --> 00:28:59.520 It was a world of possibility. 00:29:00.040 --> 00:29:02.320 It had the potential for life. 00:29:06.600 --> 00:29:08.080 But it didn't last. 00:29:13.720 --> 00:29:19.080 Because not far away was a raging nuclear inferno. 00:29:21.040 --> 00:29:22.040 Our Sun. 00:29:24.120 --> 00:29:27.520 It unleashes torrents of high-energy particles 00:29:27.600 --> 00:29:29.800 so powerful and deadly… 00:29:32.480 --> 00:29:34.480 …they can devastate planets. 00:29:43.960 --> 00:29:47.840 This solar wind streams through space… 00:29:52.320 --> 00:29:55.640 at 400 kilometers per second. 00:30:00.480 --> 00:30:03.160 And it ripped through the Martian atmosphere, 00:30:04.640 --> 00:30:06.800 tearing water molecules apart. 00:30:15.040 --> 00:30:16.520 Bit by bit, 00:30:16.600 --> 00:30:18.160 over millions of years, 00:30:19.600 --> 00:30:24.480 the planet's protective layer was stripped away by the Sun's fury… 00:30:29.680 --> 00:30:31.640 …until its ocean evaporated… 00:30:37.640 --> 00:30:41.040 and its water was lost to space. 00:30:48.600 --> 00:30:52.400 Mars became a desolate, frozen shadow 00:30:52.920 --> 00:30:54.280 of its former self. 00:31:03.360 --> 00:31:05.920 Consumed by dust storms. 00:31:12.520 --> 00:31:14.480 Any chance of complex life… 00:31:16.480 --> 00:31:18.280 gone forever. 00:31:27.560 --> 00:31:29.640 This could have been our story too. 00:31:44.360 --> 00:31:46.640 But somehow, on Earth, 00:31:47.560 --> 00:31:51.280 water and life have found a way to cling on. 00:32:06.320 --> 00:32:07.960 In Botswana, 00:32:08.040 --> 00:32:10.640 after 200 days in the burning sun… 00:32:12.840 --> 00:32:15.000 …there is no water to be found. 00:32:23.680 --> 00:32:26.040 Violent winds whip the scorched earth 00:32:26.120 --> 00:32:27.600 into a dust bowl. 00:32:45.320 --> 00:32:49.440 And the elephants' struggle hasn't gone unnoticed. 00:33:02.920 --> 00:33:06.800 In daylight, adults can usually protect their young. 00:33:18.240 --> 00:33:19.800 But when night falls… 00:33:25.480 --> 00:33:26.920 …it's a different story. 00:33:37.520 --> 00:33:40.400 Lions are masters of chaos and confusion. 00:33:53.440 --> 00:33:55.880 They pick the most vulnerable target… 00:34:00.800 --> 00:34:02.120 …working as a pack… 00:34:08.200 --> 00:34:10.280 …until there's nowhere left to run. 00:34:27.240 --> 00:34:29.600 Without the entire herd as protection, 00:34:30.960 --> 00:34:34.080 the lions overwhelm their prey. 00:34:36.880 --> 00:34:40.600 The drought and endless search for food and water 00:34:41.440 --> 00:34:44.880 have taken their ultimate toll on Bosigo. 00:34:55.040 --> 00:34:58.240 Elephants form deep emotional bonds. 00:35:09.920 --> 00:35:13.080 All the family mourn Bosigo's loss. 00:35:30.480 --> 00:35:32.840 The herd gathers to comfort Metsi, 00:35:34.680 --> 00:35:36.960 who feels it hardest of all. 00:35:48.480 --> 00:35:50.720 The never-ending fight to survive 00:35:50.800 --> 00:35:52.480 plays out every year, 00:35:54.280 --> 00:35:55.720 across the Okavango… 00:35:58.000 --> 00:35:59.280 across our planet… 00:36:01.960 --> 00:36:03.040 and beyond. 00:36:07.080 --> 00:36:09.560 But in this battle for survival, 00:36:10.440 --> 00:36:12.000 Earth got truly lucky… 00:36:14.000 --> 00:36:17.440 with a secret guardian that protects it. 00:36:24.360 --> 00:36:25.480 Deep within… 00:36:28.520 --> 00:36:32.280 …the planet's raging molten furnace burns 00:36:32.920 --> 00:36:33.920 and churns… 00:36:37.840 --> 00:36:40.240 …generating a powerful magnetic field 00:36:41.920 --> 00:36:44.360 that extends from the heart of the planet… 00:36:46.160 --> 00:36:50.680 …65,000 kilometers out towards the Sun. 00:36:52.600 --> 00:36:55.880 A vital force field defending Earth… 00:36:58.320 --> 00:37:01.040 …from the same savage solar winds 00:37:02.080 --> 00:37:04.040 that stripped water from Mars. 00:37:10.480 --> 00:37:13.920 Defeating them before they hit our atmosphere. 00:37:26.520 --> 00:37:28.760 Safeguarding our essential water. 00:37:30.520 --> 00:37:34.160 Hugging every drop close to our planet. 00:37:41.040 --> 00:37:43.960 This is what makes our pale blue dot 00:37:44.480 --> 00:37:46.160 unlike anywhere else. 00:37:49.520 --> 00:37:52.920 A place where life can thrive. 00:37:56.960 --> 00:37:59.080 Bringing relief to the elephants. 00:38:01.600 --> 00:38:04.880 Ensuring rains return each year without fail. 00:38:09.680 --> 00:38:14.000 In the distance, storm clouds are building. 00:38:29.200 --> 00:38:33.800 Elephants can detect the low-frequency rumble of thunder 00:38:33.880 --> 00:38:36.480 from 240 kilometers away. 00:38:43.400 --> 00:38:47.880 And it's telling them it's time to return to the Okavango. 00:38:56.600 --> 00:38:58.440 From the highlands of Angola, 00:39:00.200 --> 00:39:03.080 water is weaving its way through Botswana… 00:39:12.000 --> 00:39:14.280 …to rejuvenate the delta… 00:39:22.640 --> 00:39:24.720 with the kiss of life. 00:39:34.480 --> 00:39:37.480 Every step that brings the herd closer to home… 00:39:40.760 --> 00:39:45.280 is a continuation of a much larger cosmic odyssey. 00:39:51.640 --> 00:39:57.280 From tiny molecules hitching a ride on dust beyond Jupiter… 00:40:03.000 --> 00:40:05.800 to surviving the crushing heat of early Earth. 00:40:13.680 --> 00:40:16.160 Imprisoned in the planet's core… 00:40:18.200 --> 00:40:19.880 …then set free… 00:40:21.240 --> 00:40:23.080 …to sow the seeds of life… 00:40:27.360 --> 00:40:31.880 …every drop of water has an amazing tale to tell. 00:40:34.640 --> 00:40:36.000 Every molecule… 00:40:36.080 --> 00:40:39.120 -…a link in an unbroken chain… 00:40:40.440 --> 00:40:43.400 …cycling over tens of thousands of years… 00:40:46.480 --> 00:40:47.800 …through air… 00:40:50.840 --> 00:40:51.800 oceans… 00:40:55.680 --> 00:40:56.560 rocks… 00:41:04.800 --> 00:41:05.960 …and elephants. 00:41:11.680 --> 00:41:16.040 After eight months and hundreds of kilometers, 00:41:17.720 --> 00:41:21.520 Metsi and her family have finally reached 00:41:21.600 --> 00:41:24.960 the life-giving waters of the delta. 00:41:38.040 --> 00:41:41.640 It's well past time to drink… 00:41:43.880 --> 00:41:45.080 and play. 00:41:47.440 --> 00:41:50.160 And then, drink some more. 00:41:59.560 --> 00:42:02.040 And show the newest member of the family… 00:42:06.360 --> 00:42:09.200 …how they do things in the delta. 00:42:22.360 --> 00:42:25.360 Metsi and her new baby cousin 00:42:25.440 --> 00:42:28.240 are the latest in a long line 00:42:28.320 --> 00:42:31.560 to benefit from water's miraculous arrival 00:42:32.800 --> 00:42:33.720 on this planet. 00:42:44.480 --> 00:42:46.440 They will forever be connected 00:42:46.520 --> 00:42:47.880 to the universe 00:42:48.800 --> 00:42:52.280 that gave our planet this magic ingredient 00:42:54.040 --> 00:42:59.920 and gave us the ability to preserve and treasure it. 00:43:10.840 --> 00:43:15.120 Next, the story of our universe concludes… 00:43:16.280 --> 00:43:22.160 …with the force that brings everything we've seen so far together. 00:43:23.560 --> 00:43:26.320 The great sculptor of the cosmos, 00:43:26.960 --> 00:43:27.800 gravity. 00:43:29.160 --> 00:43:32.520 It's a force of attraction that built our planet. 00:43:35.560 --> 00:43:39.160 And we'll bring two penguins together at Earth's southern pole. 00:43:41.040 --> 00:43:44.120 But when did gravity start exerting its influence? 00:43:45.680 --> 00:43:50.080 How does it create both order and chaos? 00:43:52.920 --> 00:43:57.640 And why does it make ours the perfect planet for life… 00:43:59.920 --> 00:44:00.920 …and love?