WEBVTT 00:00:10.721 --> 00:00:13.921 ‫Brian Cox: Our universe ‫is a place of infinite variety. 00:00:15.921 --> 00:00:18.121 ‫Two trillion galaxies. 00:00:22.081 --> 00:00:25.001 ‫Billions and billions of stars. 00:00:28.081 --> 00:00:29.841 ‫And countless planets 00:00:30.881 --> 00:00:33.321 ‫Worlds beyond imagination 00:00:37.961 --> 00:00:39.721 ‫The universe is so vast, 00:00:39.801 --> 00:00:43.201 ‫so incomprehensible, so terrifying, 00:00:43.281 --> 00:00:45.241 ‫that I think it's quite natural ‫for us to choose 00:00:45.321 --> 00:00:48.161 ‫to live out our lives ‫completely oblivious to it. 00:00:51.921 --> 00:00:56.201 Perhaps that's why there's a sense of relief that rises with the dawn. 00:00:56.281 --> 00:01:01.041 The brightening sky hides the stars and the questions that they pose. 00:01:03.161 --> 00:01:06.361 A fter all, they are the biggest questions. 00:01:09.321 --> 00:01:11.161 How did the universe come to be? 00:01:12.641 --> 00:01:13.761 Why are we here? 00:01:15.361 --> 00:01:17.121 And how will it all end? 00:01:23.481 --> 00:01:25.321 We have to face those questions 00:01:25.401 --> 00:01:30.041 if we 're ever to acquire a truly deep understanding of ourselves. 00:01:30.121 --> 00:01:33.201 You see, astronomy challenges us. 00:01:33.281 --> 00:01:36.841 From one perspective, we're just grains of sand adrift 00:01:36.921 --> 00:01:39.801 in an infinite and indifferent ocean. 00:01:39.881 --> 00:01:44.601 But from another perspective, we are nature's most magnificent creation. 00:01:44.681 --> 00:01:49.281 Collections of atoms that can think and wonder about the universe 00:01:49.361 --> 00:01:52.081 and choose to explore it. 00:01:54.121 --> 00:01:58.161 In distinct voices: Five, four, three, two, one. 00:01:58.521 --> 00:02:00.921 We have lift-off. All systems go. 00:02:06.641 --> 00:02:11.041 Cox: In our quest for answers, we 're venturing ever further from home, 00:02:11.641 --> 00:02:13.321 far beyond the planets... 00:02:16.801 --> 00:02:18.921 And out to the stars. 00:02:22.601 --> 00:02:27.081 Our spacecraft are sending back a stream of extraordinary revelations. 00:02:29.441 --> 00:02:31.841 Visions of alien worlds... 00:02:34.281 --> 00:02:37.361 With the ingredients to create life. 00:02:44.481 --> 00:02:46.681 We've seen galaxies collide, 00:02:51.161 --> 00:02:54.241 black holes devouring star systems. 00:02:57.521 --> 00:03:02.041 And we may have glimpsed the origin of the cosmos itself. 00:03:04.921 --> 00:03:08.761 With every new observation, with every new piece of knowledge, 00:03:08.841 --> 00:03:12.681 there is the opportunity to acquire a deeper understanding. 00:03:12.761 --> 00:03:15.841 And, as we answer question after question 00:03:15.921 --> 00:03:18.481 we get ever closer to being able to tell 00:03:18.561 --> 00:03:22.561 what is surely the greatest story ever told. 00:04:09.241 --> 00:04:11.881 Man over radio: Na sa '5 Parker solar probe, 00:04:11.961 --> 00:04:13.961 a daring mission to shed light 00:04:15.481 --> 00:04:19.201 on the mysteries of our closest star. 00:04:29.401 --> 00:04:34.641 Eugene Parker: This is a journey into ne ver-ne ver land you might say. 00:04:44.161 --> 00:04:50.681 Cox: NASA's Parker solar probe is the first spacecraft to touch a star. 00:05:15.401 --> 00:05:18.841 It's designed to fly through the sun's atmosphere, 00:05:21.241 --> 00:05:25.081 bra ving temperatures no spacecraft has ever endured. 00:05:54.361 --> 00:05:58.241 The Parker solar probe is allowing us to know our star 00:05:58.881 --> 00:06:00.481 as we've never known it before. 00:06:05.641 --> 00:06:10.401 And it's also helping us to tell the story of all the stars. 00:06:20.081 --> 00:06:25.041 Our sun is from a long line of stars dating back to the dawn of time. 00:06:27.321 --> 00:06:29.361 From fierce blue giants 00:06:30.961 --> 00:06:33.161 which first lit up the universe, 00:06:36.241 --> 00:06:38.081 to later generations, 00:06:40.521 --> 00:06:44.161 whose deaths enriched the cosmos with precious elements, 00:06:49.161 --> 00:06:51.481 the building blocks of our solar system, 00:06:58.801 --> 00:07:04.361 And allowed our sun to create the thing which brings meaning to the cosmos. 00:07:12.121 --> 00:07:13.361 Life. 00:07:14.681 --> 00:07:17.081 You and me. 00:07:57.001 --> 00:08:00.081 We have a strange relationship with the stars, 00:08:00.161 --> 00:08:03.481 somewhere between awe and indifference. 00:08:05.161 --> 00:08:07.801 I think we take our star, the sun, for granted, 00:08:07.881 --> 00:08:09.801 partly because of its predictability. 00:08:09.881 --> 00:08:13.441 Every day it rises in the east and sets in the west, 00:08:15.601 --> 00:08:19.441 without any help or reverence from us. 00:08:24.041 --> 00:08:27.161 But many ancient cultures deified the sun. 00:08:27.921 --> 00:08:29.681 They treated it as a god 00:08:30.481 --> 00:08:34.841 and the sun gods were creators and destroyers of worlds. 00:08:35.481 --> 00:08:37.041 So which is it? 00:08:38.081 --> 00:08:43.641 Well, I think that the modern story of the stars as told by science, 00:08:43.721 --> 00:08:46.401 which is indisputably an epic story 00:08:46.481 --> 00:08:50.921 stretching back over 13 billion years to the origin of the universe, 00:08:51.001 --> 00:08:54.561 places them firmly in the realm of the gods. 00:09:06.161 --> 00:09:09.401 If we want to understand where these gods came from... 00:09:11.521 --> 00:09:12.961 We have to go back... 00:09:18.481 --> 00:09:21.081 To a time before the stars. 00:09:50.561 --> 00:09:54.801 In the beginning the universe was dark. 00:10:00.721 --> 00:10:03.041 But it was not empty. 00:10:07.281 --> 00:10:10.081 Something was lurking in the void, 00:10:13.321 --> 00:10:15.441 stretching out tendrils. 00:10:37.761 --> 00:10:41.601 The cosmic web grew to become a vast structure, 00:10:46.881 --> 00:10:49.161 Criss-crossing the entire universe. 00:10:54.521 --> 00:10:58.521 It was formed by interlocking filaments of dark matter, 00:11:04.161 --> 00:11:06.881 And it was at the places where these filaments met, 00:11:10.081 --> 00:11:11.641 the intersections, 00:11:18.121 --> 00:11:24.521 That the first stars, our sun's earliest ancestors, were born. 00:12:01.081 --> 00:12:04.201 The cosmic web is the scaffolding of the universe, 00:12:05.401 --> 00:12:09.521 the vast and intricate structure that spans the void. 00:12:15.081 --> 00:12:18.121 The web is made primarily out of dark matter, 00:12:18.201 --> 00:12:22.001 a mysterious substance that dominates the universe, 00:12:22.081 --> 00:12:24.721 although we don't know what it is. 00:12:24.801 --> 00:12:26.801 It's one of the great mysteries in modern physics. 00:12:26.881 --> 00:12:32.601 It's probably some kind of particle that interacts very weakly with itself 00:12:32.681 --> 00:12:34.321 and with light. 00:12:34.401 --> 00:12:36.081 If it doesn't interact with light, 00:12:36.161 --> 00:12:38.441 we can't see it, which is why it's called dark matter. 00:12:40.721 --> 00:12:45.041 But it does influence the universe through its gravity. 00:12:49.801 --> 00:12:52.481 It was in the dark heart of the cosmic web 00:12:53.121 --> 00:12:56.361 that gravity began to sculpt the early universe, 00:13:00.201 --> 00:13:03.281 drawing together the two simplest elements, 00:13:03.361 --> 00:13:05.401 hydrogen and helium. 00:13:07.321 --> 00:13:11.081 The raw material for the very first stars. 00:13:14.441 --> 00:13:18.601 Hydrogen gas clings to the filaments of the web, 00:13:18.721 --> 00:13:22.441 attracted there by the gravitational pull of the dark matter. 00:13:23.801 --> 00:13:26.281 And where those filaments cross, 00:13:26.361 --> 00:13:30.761 the gas can become dense enough to collapse under its own gravity 00:13:30.841 --> 00:13:35.521 to form great clusters of galaxies, each filled with billions of stars. 00:13:52.361 --> 00:13:55.361 The universe was approaching a turning point. 00:13:57.281 --> 00:13:59.961 Hydrogen and helium poured into the regions 00:14:00.041 --> 00:14:01.721 where the filaments crossed, 00:14:04.521 --> 00:14:07.001 gathering into ever denser clouds. 00:14:12.001 --> 00:14:14.281 Gra vity asserted its grip, 00:14:17.521 --> 00:14:20.441 and the clouds of gas began to collapse, 00:14:25.401 --> 00:14:28.001 becoming denser and denser. 00:14:31.401 --> 00:14:33.761 And in the densest regions, 00:14:33.841 --> 00:14:35.801 the gas became so hot... 00:14:38.321 --> 00:14:41.081 That nuclear fusion reactions began. 00:15:03.001 --> 00:15:04.721 And out of maelstrom, 00:15:05.961 --> 00:15:08.841 the first gods emerged, 00:15:11.681 --> 00:15:13.241 and there was light. 00:16:00.361 --> 00:16:02.961 The stars illuminate the universe, 00:16:03.921 --> 00:16:07.681 but that is the least interesting thing that they do. 00:16:09.561 --> 00:16:11.401 The thing that makes the universe interesting, 00:16:11.481 --> 00:16:17.641 that brings meaning to the universe is that, life. You and me. 00:16:17.721 --> 00:16:20.641 And life is just chemistry. 00:16:20.721 --> 00:16:24.561 And chemistry requires complex chemical elements. 00:16:24.641 --> 00:16:27.721 The only thing that existed in the universe before the stars 00:16:27.801 --> 00:16:29.801 was hydrogen and helium. 00:16:29.881 --> 00:16:33.361 Life requires carbon and oxygen and iron. 00:16:33.441 --> 00:16:37.441 All those things were made in a process called nuclear fusion 00:16:37.521 --> 00:16:39.201 in the cores of stars, 00:16:39.281 --> 00:16:43.921 or even the heavier elements, like gold, in the collisions of stars. 00:16:44.001 --> 00:16:48.881 So, without the stars, the universe would be uninteresting. 00:16:48.961 --> 00:16:50.721 It would be meaningless. 00:16:50.801 --> 00:16:54.321 It would be just an infinite box of gas. 00:17:07.041 --> 00:17:09.281 The first stars were monsters. 00:17:17.961 --> 00:17:20.801 Hundreds of times as massive as our sun. 00:17:25.801 --> 00:17:30.001 They burnt with such ferocity that they shone blue, 00:17:33.961 --> 00:17:38.561 with surface temperatures in excess of 700, 000 degrees. 00:17:42.641 --> 00:17:45.841 They were the largest stars ever to have lived. 00:17:47.681 --> 00:17:50.401 I/iolent and volatile giants. 00:18:00.681 --> 00:18:03.401 A star is essentially a balancing act. 00:18:03.481 --> 00:18:07.201 The force of gravity is constantly trying to collapse it, 00:18:07.281 --> 00:18:09.481 and that pushes its ingredients, 00:18:09.561 --> 00:18:11.429 primarily hydrogen, single protons, 00:18:11.453 --> 00:18:13.641 closer and closer together. 00:18:14.121 --> 00:18:17.121 Now, when those protons get close enough together, 00:18:17.201 --> 00:18:19.521 another of the fundamental forces of nature, 00:18:19.601 --> 00:18:22.481 the strong nuclear force, takes over, 00:18:22.561 --> 00:18:24.641 and it can stick the protons together. 00:18:24.721 --> 00:18:29.801 That releases energy which creates a pressure which holds the star up. 00:18:29.881 --> 00:18:34.121 Now the more massive the star, the stronger the inward pull of gravity 00:18:34.201 --> 00:18:37.881 and the more energy has to be released to maintain the balance, 00:18:37.961 --> 00:18:40.881 and so the faster the ingredients are used up. 00:19:01.401 --> 00:19:04.721 These giant stars were in a struggle for survival, 00:19:06.281 --> 00:19:09.321 fighting the relentless pull of gra vity, 00:19:13.881 --> 00:19:17.241 consuming more and more hydrogen fuel 00:19:17.321 --> 00:19:20.281 to maintain their precarious equilibrium. 00:19:37.361 --> 00:19:40.281 For most of its life, a star burns hydrogen, 00:19:40.361 --> 00:19:43.561 the simplest chemical element with one proton in its nucleus, 00:19:44.241 --> 00:19:46.641 into helium with two protons. 00:19:47.721 --> 00:19:50.041 Now, when it runs out of hydrogen in the core, 00:19:50.121 --> 00:19:53.001 the core starts to collapse and heat up, 00:19:53.081 --> 00:19:57.961 and the star responds by building ever more complex elements. 00:19:58.041 --> 00:20:02.081 So it makes carbon with six protons and oxygen with eight protons, 00:20:02.161 --> 00:20:04.921 releasing more and more energy as it goes. 00:20:08.081 --> 00:20:11.521 But when the star has assembled iron in its core, 00:20:11.601 --> 00:20:14.161 with 26 protons in its nucleus, 00:20:14.241 --> 00:20:17.001 no more energy can be released. 00:20:17.121 --> 00:20:20.401 The star loses its battle against gravity. 00:20:20.481 --> 00:20:25.641 It collapses and in a final moment of creation, 00:20:25.761 --> 00:20:28.561 salvaged if you like, from its destruction, 00:20:28.641 --> 00:20:32.481 it distributes those newly minted heavy chemical elements 00:20:32.561 --> 00:20:34.721 out into the universe. 00:20:49.841 --> 00:20:53.361 Imagine we could journey back in time 00:20:53.441 --> 00:20:58.681 and watch the first star live out its brief luminous life. 00:21:19.361 --> 00:21:24.881 After only a million years the star used up all of its fuel. 00:21:36.001 --> 00:21:37.801 The core collapsed. 00:21:52.921 --> 00:21:55.001 The star imploded. 00:22:07.441 --> 00:22:12.121 And then rebounded... In a colossal explosion. 00:22:13.601 --> 00:22:15.001 A supernova. 00:22:37.281 --> 00:22:41.801 In death, the first stars began to transform the cosmos, 00:22:45.361 --> 00:22:48.761 enriching the ocean of hydrogen and helium 00:22:48.841 --> 00:22:52.561 which filled the universe with heavy elements... 00:22:55.041 --> 00:22:59.281 To build new generations of more complex stars. 00:23:08.081 --> 00:23:11.681 Over time, these elements gathered together, 00:23:20.281 --> 00:23:24.041 Creating rich clouds of gas and dust. 00:23:33.281 --> 00:23:38.361 Nurseries where new generations of stars were born. 00:23:44.761 --> 00:23:48.841 And not just stars, but families of stars. 00:23:51.201 --> 00:23:52.841 The first galaxies. 00:24:00.481 --> 00:24:01.681 And around this time, 00:24:02.561 --> 00:24:09.161 some of the earliest star systems formed in our own galaxy, the milky way. 00:24:20.281 --> 00:24:23.961 A new age of complexity was dawning in the universe. 00:24:26.721 --> 00:24:29.561 Now, there were stars of different sizes, 00:24:35.641 --> 00:24:37.161 And different colours. 00:24:51.321 --> 00:24:55.321 And crucially new bodies had appeared. 00:25:04.401 --> 00:25:05.761 Planets. 00:25:07.801 --> 00:25:14.201 Places where the rich chemical elements built by previous generations of stars 00:25:14.761 --> 00:25:17.841 could finally find a home. 00:25:33.601 --> 00:25:35.921 Countless billions of stars have come and gone 00:25:36.001 --> 00:25:39.841 since those first giants illuminated the darkness. 00:25:39.921 --> 00:25:42.281 Each enriching the universe 00:25:42.361 --> 00:25:45.561 with the material out of which the next generation formed. 00:25:46.241 --> 00:25:50.241 Blue stars and white stars, single stars, double stars, 00:25:50.321 --> 00:25:53.761 even triple star systems orbiting around each other. 00:25:57.081 --> 00:25:59.001 The conditions were now right 00:25:59.081 --> 00:26:02.121 for those stars to drive the universe 00:26:02.201 --> 00:26:05.401 into a new and profound age of complexity. 00:26:35.081 --> 00:26:39.521 Our sun was formed from the ashes of generations of ancestors. 00:26:54.481 --> 00:27:00.281 Just one small star in a galaxy of billions of brilliant gods. 00:27:09.681 --> 00:27:14.561 For the first million years of its life, the sun was virtually alone, 00:27:16.881 --> 00:27:20.281 wreathed in clouds of gas and dust. 00:27:23.521 --> 00:27:26.081 The dust slowly clumped together... 00:27:30.681 --> 00:27:33.281 Forming clusters the size of pebbles. 00:27:36.601 --> 00:27:38.441 Then, boulders. 00:27:45.121 --> 00:27:46.601 And finally... 00:27:48.561 --> 00:27:49.801 Planets. 00:27:56.161 --> 00:27:58.561 But the planets were lifeless rocks. 00:28:06.081 --> 00:28:11.841 Only the sun had the power to turn them into worlds. 00:28:19.081 --> 00:28:21.721 Some were too faraway from the sun. 00:28:35.001 --> 00:28:36.441 Ice giants, 00:28:37.801 --> 00:28:42.121 frozen, seemingly into infertility. 00:28:46.961 --> 00:28:49.641 Others formed too close to the sun, 00:28:52.601 --> 00:28:55.361 seared by a relentless light. 00:28:58.361 --> 00:29:01.441 They became scorched desert worlds. 00:29:05.001 --> 00:29:08.041 But there was a planet in the sun's family 00:29:09.961 --> 00:29:15.201 that, quite by chance, formed neither too close nor too far away. 00:29:21.841 --> 00:29:27.641 An arcadia, where our star could breathe life into dust. 00:29:52.561 --> 00:29:56.441 The planets are just the leftovers from the formation of stars. 00:29:56.521 --> 00:29:58.841 Debris, if you like. 00:30:00.201 --> 00:30:04.441 They're just little specks orbiting around those magnificent flames. 00:30:06.761 --> 00:30:10.321 But the planets are also the places in the universe 00:30:10.401 --> 00:30:13.681 where gravity has concentrated the heavy elements built 00:30:13.761 --> 00:30:16.481 by previous generations of stars. 00:30:16.561 --> 00:30:21.441 And that makes the planets the canvas on which the stars can create. 00:30:24.241 --> 00:30:27.761 "The canvas on which the stars can create." What do I mean by that? 00:30:27.841 --> 00:30:29.361 Well, just look around. 00:30:29.441 --> 00:30:32.521 Everywhere you look on earth there is complexity. 00:30:32.601 --> 00:30:37.121 Not only mountains and rivers, but living things, animals and plants, 00:30:37.201 --> 00:30:39.801 human beings, human civilisation, 00:30:39.881 --> 00:30:43.921 the most complex thing we know of anywhere in the universe. 00:30:44.001 --> 00:30:45.961 So, you have to ask yourself 00:30:46.041 --> 00:30:49.641 how can it be that such complexity can emerge 00:30:49.721 --> 00:30:52.561 completely naturally in the universe? 00:30:57.601 --> 00:31:02.081 Well, the answer, in fact, was known in the 79th century 00:31:02.161 --> 00:31:04.881 and it comes from the science of thermodynamics. 00:31:07.801 --> 00:31:08.961 In the 19th century, 00:31:09.041 --> 00:31:11.481 people were interested in the efficiency of steam engines, 00:31:11.561 --> 00:31:16.041 and steam engines are, after all, the machines that powered the factories 00:31:16.121 --> 00:31:19.601 that allowed people to build increasingly complex things. 00:31:20.081 --> 00:31:24.161 And it turns out that the only thing that matters for a steam engine, 00:31:24.241 --> 00:31:26.321 the thing that determines its efficiency, 00:31:26.401 --> 00:31:30.001 the thing that allows it to do work and build things 00:31:30.081 --> 00:31:33.601 is the temperature difference between the fire, 00:31:33.681 --> 00:31:36.521 the furnace at the heart of the steam engine, 00:31:36.601 --> 00:31:39.801 and the cold environment surrounding it. 00:31:41.961 --> 00:31:46.801 In the universe, the stars are hot spots in a cold sky. 00:31:46.881 --> 00:31:52.081 We are sitting, in a very real sense, inside a giant steam engine, 00:31:52.161 --> 00:31:54.681 powered by the furnace of the sun. 00:31:56.361 --> 00:31:58.281 And it's in that sense 00:31:58.361 --> 00:32:03.481 that the stars are the creators of complexity in the universe. 00:32:07.521 --> 00:32:11.161 But creating complexity is a subtle art. 00:32:14.121 --> 00:32:19.561 You need an engine, in this case a star, that's not too wild and flashy. 00:32:24.441 --> 00:32:29.121 A star which is consistent enough for long enough 00:32:29.201 --> 00:32:31.321 to kindle the sparks of life, 00:32:37.241 --> 00:32:41.401 And allow those sparks to flicker and flourish. 00:32:54.361 --> 00:32:59.761 The most important property of a star, if it's to nurture a civilisation... 00:33:01.801 --> 00:33:05.081 Is magnificent dependability. 00:33:30.041 --> 00:33:33.921 No one knows exactly how life on earth emerged. 00:33:41.121 --> 00:33:44.721 But what we do know is that at some point 00:33:44.801 --> 00:33:50.241 primitive cells living in the ocean began using the sun's energy 00:33:50.321 --> 00:33:53.641 to power life-giving chemical reactions. 00:33:56.241 --> 00:34:01.441 These cells formed a bridge between earth and sun. 00:34:03.481 --> 00:34:07.761 Delicate engines which harness the fires of our star, 00:34:09.481 --> 00:34:15.241 using sunlight to turn carbon dioxide and water into food. 00:34:21.921 --> 00:34:28.561 This process, known as photosynthesis, unleashed the sun's creative power, 00:34:42.761 --> 00:34:46.041 And drove the evolution of complexity. 00:34:54.721 --> 00:34:56.641 From primitive bacteria, 00:34:57.681 --> 00:35:00.481 to plants and trees... 00:35:12.841 --> 00:35:16.881 And ultimately, to you and me. 00:35:20.841 --> 00:35:22.561 You know, photosynthesis is a process 00:35:22.641 --> 00:35:25.121 that's very easy to describe in words. 00:35:25.681 --> 00:35:27.641 The plants take energy from the sun, 00:35:28.761 --> 00:35:32.441 then use it to react carbon dioxide and water together 00:35:32.521 --> 00:35:35.921 to make sugars and a waste product, oxygen. 00:35:36.001 --> 00:35:39.361 Really easy to say. Very difficult to do. 00:35:39.441 --> 00:35:42.921 There's a part of that photosynthetic machinery 00:35:43.001 --> 00:35:44.641 in everything you see here. 00:35:44.721 --> 00:35:47.601 Every plant on the planet has got photosystem ii. 00:35:47.681 --> 00:35:52.841 It's comprised of 46, 630 atoms 00:35:52.921 --> 00:35:56.481 all working together in an intricate machine. 00:35:56.601 --> 00:36:00.441 Very efficient. It took billions of years of evolution. 00:36:01.081 --> 00:36:02.441 Then we eat the plants, 00:36:02.521 --> 00:36:05.121 or we eat something that's eaten the plants 00:36:05.201 --> 00:36:07.761 and we do the reverse reaction. 00:36:07.841 --> 00:36:12.441 We take those sugars and we breathe in that waste product, oxygen. 00:36:12.521 --> 00:36:14.681 React them together, release a bit of energy, 00:36:14.761 --> 00:36:17.201 a bit of the stored sunlight if you like, 00:36:17.281 --> 00:36:22.921 and we use that energy to maintain our structure, to grow, to live. 00:36:30.521 --> 00:36:34.121 T rillions of stars have existed since the universe began. 00:36:39.121 --> 00:36:43.681 But ours has nurtured that most miraculous thing, 00:36:45.281 --> 00:36:46.441 life. 00:36:49.961 --> 00:36:54.481 And that makes the sun a truly remarkable star. 00:37:03.161 --> 00:37:06.041 That is the only star we know of anywhere 00:37:06.121 --> 00:37:10.721 where there are collections of atoms in orbit around it, you and me, 00:37:10.801 --> 00:37:15.081 that have named it the sun. Our sun. 00:37:15.161 --> 00:37:18.881 We worshipped it, deified it since the dawn of history. 00:37:18.961 --> 00:37:22.201 In fact, it's been argued that the sun lies at the foundation 00:37:22.281 --> 00:37:26.681 of all religion, and there may be some truth in that. 00:37:26.761 --> 00:37:29.801 In fact, I think there is a deep truth in that 00:37:29.881 --> 00:37:32.521 because we all owe our existence, 00:37:32.601 --> 00:37:37.001 this brief time we have in the universe to that star. 00:37:37.081 --> 00:37:40.401 In fact, in a deeper sense to all the stars. 00:37:40.481 --> 00:37:45.801 We don't need to invent imaginary gods to explain the universe. 00:37:45.881 --> 00:37:48.721 We can replace them with the real thing. 00:38:02.601 --> 00:38:04.161 Everyone we love. 00:38:09.881 --> 00:38:12.121 Everything we value. 00:38:15.041 --> 00:38:19.721 Our supreme accomplishments as a civilisation... 00:38:23.481 --> 00:38:26.401 Were created and crafted... 00:38:30.081 --> 00:38:31.361 By stars. 00:38:51.241 --> 00:38:55.481 There are over 200 billion stars in our galaxy. 00:39:00.521 --> 00:39:05.081 And there are two trillion galaxies in the observable universe. 00:39:14.481 --> 00:39:16.841 We 're living in the age of stars. 00:39:27.761 --> 00:39:31.121 An era of light and life in the cosmos. 00:39:37.281 --> 00:39:39.921 From our fleeting human perspective, 00:39:40.721 --> 00:39:42.801 stars seem eternal. 00:40:02.681 --> 00:40:06.521 But even gods are not immortal. 00:40:10.841 --> 00:40:12.721 Where there is light, 00:40:15.321 --> 00:40:16.761 there is darkness. 00:40:21.881 --> 00:40:23.641 Stars are creators, 00:40:29.561 --> 00:40:32.921 But they can be jealous guardians of their creations. 00:40:38.321 --> 00:40:43.361 Many smaller stars don't die in spectacular explosions. 00:40:45.201 --> 00:40:49.801 Instead, they slowly fade away. 00:40:51.681 --> 00:40:55.601 They hang on to the precious elements they made, 00:40:57.721 --> 00:40:59.481 becoming fossil stars. 00:41:04.041 --> 00:41:06.721 And as more fossils litter the universe, 00:41:09.401 --> 00:41:13.041 more life giving elements remain locked away, 00:41:15.721 --> 00:41:17.961 starving the cosmos 00:41:18.041 --> 00:41:21.961 of the material needed to make new generations of stars. 00:41:39.881 --> 00:41:42.841 The age of stars may seem infinite, 00:41:45.121 --> 00:41:46.641 but it had a beginning, 00:41:48.401 --> 00:41:50.881 and it will also have an end. 00:41:54.681 --> 00:41:57.601 Imagine a timeline of the universe 00:41:57.681 --> 00:42:00.641 and imagine that this is the origin of the universe, 00:42:00.721 --> 00:42:03.521 the big bang 13.8 billion years ago. 00:42:04.241 --> 00:42:08.041 After 100 million years or so, the first stars formed. 00:42:08.121 --> 00:42:13.121 On this scale, one centimetre is about 20 million years. 00:42:13.201 --> 00:42:17.801 After four billion years the peak rate of star formation occurred. 00:42:17.881 --> 00:42:21.361 The maximum number of new stars were born. 00:42:21.441 --> 00:42:26.121 After nine billion years, our sun was born. 00:42:26.961 --> 00:42:31.561 And, today, we stand 13.8 billion years later, 00:42:31.641 --> 00:42:34.681 about halfway through the lifetime of our sun. 00:42:35.601 --> 00:42:38.161 Now, in about five billion years' time, 00:42:38.241 --> 00:42:41.601 our sun will die but new stars will be born, 00:42:42.201 --> 00:42:44.601 and many of the older stars in the universe, 00:42:44.681 --> 00:42:47.801 the smaller stars, will continue to shine. 00:42:47.881 --> 00:42:52.441 In fact, we think that the last star will cease to shine, 00:42:52.521 --> 00:42:57.121 the universe will go dark, in around ten trillion years. 00:42:58.761 --> 00:43:03.521 On this scale, that's about 5000 metres away from the big bang. 00:43:04.041 --> 00:43:05.601 But that's not the end of the universe. 00:43:05.681 --> 00:43:11.081 As far as we know, the universe will continue expanding forever. 00:43:11.601 --> 00:43:16.761 And so, the age of starlight is the briefest moment of time 00:43:16.841 --> 00:43:19.001 in the infinite history of the universe. 00:43:19.081 --> 00:43:24.481 The age of darkness will go on and on and on. 00:43:31.161 --> 00:43:34.121 Stars won't just disappear, of course. 00:43:37.041 --> 00:43:39.921 They'll be here for aeons to come. 00:43:43.481 --> 00:43:45.721 But, over time, 00:43:45.801 --> 00:43:51.721 the universe will grow darker, colder and emptier. 00:44:02.161 --> 00:44:03.921 There are stars around today 00:44:04.001 --> 00:44:07.801 that existed close to the beginning of the age of stars. 00:44:16.481 --> 00:44:20.281 And some of them will also witness the end. 00:44:24.921 --> 00:44:28.161 They're the longest-lived stars in the universe. 00:44:30.081 --> 00:44:31.361 Red dwarfs. 00:44:39.961 --> 00:44:42.721 T rappist-7 is one of these ancients. 00:44:50.001 --> 00:44:53.281 It's already more than seven billion years old. 00:44:54.721 --> 00:44:56.881 Almost twice as old as our sun. 00:45:06.521 --> 00:45:09.921 But only around a tenth of the size, 00:45:15.921 --> 00:45:18.761 And less than one percent as bright. 00:45:22.721 --> 00:45:24.361 It's a cool star. 00:45:26.161 --> 00:45:27.681 Slow burning. 00:45:33.721 --> 00:45:36.801 And that is the secret of its longevity. 00:45:41.881 --> 00:45:43.601 Because they burn slowly, 00:45:44.961 --> 00:45:48.081 red dwarfs live for a very long time, 00:45:54.881 --> 00:45:58.241 Far longer than any other star. 00:46:04.121 --> 00:46:07.681 Like the sun, trappist-7 has its own planets. 00:46:09.841 --> 00:46:11.881 Seven rocky worlds, 00:46:14.761 --> 00:46:17.201 each roughly the size of earth. 00:46:21.681 --> 00:46:26.081 Some may have atmospheres, and even oceans. 00:46:35.321 --> 00:46:37.841 But there the similarity ends, 00:46:49.801 --> 00:46:52.201 Because these are strange worlds. 00:46:55.241 --> 00:46:58.961 Every one of these planets is locked in its orbit, 00:47:01.081 --> 00:47:03.761 one side facing t rappist-7, 00:47:05.761 --> 00:47:07.681 the other side frozen, 00:47:07.761 --> 00:47:11.761 permanently exposed to the cold void of space. 00:47:24.041 --> 00:47:27.881 If you could stand on the surface of one of these ancient worlds, 00:47:34.521 --> 00:47:37.001 As the aeons passed, 00:47:41.161 --> 00:47:46.041 you could watch the future of the cosmos slowly unfold. 00:47:56.241 --> 00:48:01.241 And one day, five billion years from now, 00:48:03.721 --> 00:48:07.081 you 'd see our sun flicker 00:48:08.361 --> 00:48:11.721 and fade away forever. 00:48:40.121 --> 00:48:43.241 The death of our sun will probably go unremarked. 00:48:46.001 --> 00:48:47.961 I doubt that we'll be around to see it. 00:48:48.041 --> 00:48:51.921 Maybe some alien astronomer, on a world far away 00:48:52.001 --> 00:48:53.801 across the milky way, will see it 00:48:53.881 --> 00:48:55.961 through the end of their telescope 00:48:56.041 --> 00:48:57.937 but I don't think they'll give it a second thought. 00:48:57.961 --> 00:49:02.641 I mean, we've seen hundreds of stars die and we don't give them a second thought. 00:49:02.721 --> 00:49:07.641 But, I think the death of our sun will matter here, locally, 00:49:07.721 --> 00:49:10.481 in this little corner of the galaxy, 00:49:10.561 --> 00:49:13.481 because it will Mark the end of a glorious time 00:49:13.561 --> 00:49:15.001 in the history of our galaxy, 00:49:15.161 --> 00:49:19.041 where meaning, where science and literature 00:49:19.121 --> 00:49:22.321 and art and poetry and music existed here. 00:49:22.961 --> 00:49:24.241 And that does matter. 00:49:28.241 --> 00:49:30.521 Why does meaning have to be eternal? 00:49:30.601 --> 00:49:34.841 It's the fragility of our lives that makes them valuable. 00:49:40.201 --> 00:49:43.561 I think the wonderful thing is that our star has 00:49:43.641 --> 00:49:47.881 taken the laws of nature, here on this planet, 00:49:47.961 --> 00:49:51.681 and crafted such a magnificent expression of them. 00:49:51.761 --> 00:49:56.201 You and me, and all this. 00:50:24.681 --> 00:50:29.841 Stars like trappist-7 will linger on long after the death of our sun. 00:50:37.961 --> 00:50:41.401 We will never know the name of the last star. 00:50:49.081 --> 00:50:53.681 But we know that the last star to shine 00:50:55.561 --> 00:50:57.001 will be a red dwarf. 00:51:04.241 --> 00:51:06.841 The last star will slowly cool... 00:51:10.801 --> 00:51:12.081 And fade away. 00:51:26.081 --> 00:51:28.681 With its passing the universe will become, 00:51:29.521 --> 00:51:32.241 once again, a void, 00:51:37.321 --> 00:51:38.721 Without light, 00:51:41.121 --> 00:51:42.241 or life, 00:51:45.641 --> 00:51:46.801 or meaning. 00:52:05.721 --> 00:52:07.681 The stars illuminate the universe 00:52:07.761 --> 00:52:10.201 and create its most intricate structures. 00:52:14.601 --> 00:52:17.281 And one day, they will all be gone. 00:52:21.361 --> 00:52:24.961 The stars are gods, but the y're mortal gods. 00:52:25.361 --> 00:52:28.601 And, when that time comes and the last stars have faded, 00:52:28.681 --> 00:52:34.321 and all possibility of life and meaning in the universe has faded with them, 00:52:34.401 --> 00:52:37.521 they will have left the most profound legacy. 00:52:37.601 --> 00:52:42.041 Because, for a moment in the long history of the universe, 00:52:42.121 --> 00:52:45.121 the stars illuminated the dark, 00:52:45.201 --> 00:52:48.281 and allowed us to illuminate it, too. 00:53:22.561 --> 00:53:26.921 Raman prinja: We want to study the sun because it teaches us a lot about stars. 00:53:27.001 --> 00:53:30.961 It teaches us a lot about all the other millions and billions of stars 00:53:31.041 --> 00:53:32.681 in our galaxy and beyond. 00:53:40.961 --> 00:53:42.321 Kelly korreck: There was a moment, 00:53:42.401 --> 00:53:44.097 when we were putting the spacecraft together, 00:53:44.121 --> 00:53:46.097 that I just took a moment and looked at the spacecraft 00:53:46.121 --> 00:53:47.361 and realised, 00:53:47.441 --> 00:53:49.761 this is going into a star, 00:53:50.441 --> 00:53:53.961 and to realise how special it was 00:53:54.241 --> 00:53:56.641 to be able to have worked on this, 00:53:56.721 --> 00:54:00.681 and that humanity decided this was something we wanted to do. 00:54:01.481 --> 00:54:03.601 - Male 1: Minus 30. - Male 2: Status check. 00:54:03.921 --> 00:54:06.281 - Male 1: Pro delta. - —male 2:60 PSP. 00:54:06.841 --> 00:54:08.001 Male voice 1: Minus 75. 00:54:08.161 --> 00:54:10.761 Korreck: Launch night, I was sick to my stomach. 00:54:11.201 --> 00:54:16.641 Male 3: Five, four, three, two, one, zero. 00:54:17.521 --> 00:54:19.657 - Lift-off of the mighty delta I I/... - — (ch eeri n g) 00:54:19.681 --> 00:54:23.161 Hea vy rocket with NASA's Parker solar probe. 00:54:23.241 --> 00:54:25.481 -There we go. —(Applause) 00:54:25.561 --> 00:54:27.001 Dr chen: The spacecraft is the first 00:54:27.081 --> 00:54:29.081 that NASA has named after a living person, 00:54:29.481 --> 00:54:31.281 because Eugene Parker is 00:54:31.361 --> 00:54:33.721 really such, you know, an eminent physicist in our field. 00:54:36.081 --> 00:54:39.041 Korreck: The delta iv heavy is a very slow rocket 00:54:39.121 --> 00:54:41.121 compared to the other launches I've seen, 00:54:41.241 --> 00:54:43.121 so I just saw fireballs, 00:54:43.201 --> 00:54:46.161 and was very, very frightened for a while. 00:54:46.241 --> 00:54:47.881 Male 1: T wenty-five seconds into flight. 00:54:50.201 --> 00:54:52.761 Temp and pressures continue to look good on all three boosters. 00:54:52.921 --> 00:54:58.081 Then realising that this was all okay as it slowly made its way up into the sky. 00:54:59.161 --> 00:55:00.841 Male 1: Now 50 seconds into flight. 00:55:07.361 --> 00:55:10.281 Korreck: Parker solar probe is so revolutionary 00:55:10.361 --> 00:55:13.921 because it's the first time that we're actually going in to touch the sun. 00:55:15.521 --> 00:55:17.601 We 're going 94% of the way 00:55:17.681 --> 00:55:19.481 from the earth to the sun 00:55:19.561 --> 00:55:23.401 to actually experience the solar corona, the sun's atmosphere. 00:55:24.641 --> 00:55:26.881 I think, at closest approach, 00:55:26.961 --> 00:55:30.001 it'll be about eight solar radii from the sun 00:55:30.081 --> 00:55:32.921 which is just mind-blowingly close. 00:55:36.601 --> 00:55:39.721 Korreck: So, we were expecting things to be very hot, 00:55:39.841 --> 00:55:42.801 over 2, 500 fahrenheit, 00:55:42.881 --> 00:55:46.081 but in a soup of a million degree plasma. 00:55:50.561 --> 00:55:52.137 That's a real challenge for the spacecraft 00:55:52.161 --> 00:55:53.641 to survive that environment. 00:55:53.881 --> 00:55:54.921 So, in order to do that, 00:55:55.001 --> 00:55:57.921 there's a very large heat shield on the front of the spacecraft 00:55:58.001 --> 00:56:00.441 which protects the majority of the instruments 00:56:00.521 --> 00:56:02.721 which are sat behind on the spacecraft body. 00:56:05.041 --> 00:56:07.681 Korreck: What makes Parker so great is the fact 00:56:07.761 --> 00:56:09.321 that it has a set of instruments 00:56:09.401 --> 00:56:12.481 that work together in order to look in all directions 00:56:12.561 --> 00:56:16.001 in order to solve those big mysteries about the solar wind. 00:56:23.321 --> 00:56:27.081 The solar corona has been mysterious to us since we've known about it, 00:56:27.161 --> 00:56:28.641 so it's a very strange thing. 00:56:28.721 --> 00:56:32.521 The surface of the sun is sort of 6,000 degrees 00:56:32.601 --> 00:56:35.161 and then, above that, you have this very thin atmosphere 00:56:35.241 --> 00:56:36.641 that's a million degrees. 00:56:36.721 --> 00:56:37.841 Super-hot. 00:56:37.921 --> 00:56:39.841 And the way that's heated, 00:56:39.921 --> 00:56:42.361 we know it has something to do with magnetic fields 00:56:42.441 --> 00:56:44.521 but we don't know exactly how it works. 00:56:44.641 --> 00:56:46.641 That's where the solar wind is generated. 00:56:46.721 --> 00:56:48.681 We don't know quite exactly how that works either. 00:56:51.081 --> 00:56:54.681 Korreck: Other things that have come out of this are 00:56:54.761 --> 00:56:56.481 coronal mass ejections. 00:56:56.561 --> 00:56:59.081 When we originally did the proposal, 00:56:59.161 --> 00:57:02.521 we were thinking that we would see five in the entire seven-year mission, 00:57:02.601 --> 00:57:04.161 if we were lucky. 00:57:06.041 --> 00:57:08.841 We ended up seeing around four to five in the first year. 00:57:10.641 --> 00:57:13.881 So, there has been just a total switch 00:57:13.961 --> 00:57:17.361 in terms of how active the sun is 00:57:17.441 --> 00:57:19.481 or what we classify as coronal mass ejections. 00:57:19.561 --> 00:57:20.881 Maybe a little bit of both. 00:57:27.161 --> 00:57:30.401 It is ajoy to see all the data coming back. 00:57:30.481 --> 00:57:32.761 It's a joy to share it with others 00:57:32.841 --> 00:57:36.761 and to see them be as curious as I have been for the last decade. 00:57:40.441 --> 00:57:42.321 50, Parker has just begun its mission really, 00:57:42.401 --> 00:57:46.681 and it's already really started to truly transform our understanding for how the sun works.