1 00:00:06,687 --> 00:00:09,247 Take a walk on planet Earth. 2 00:00:10,607 --> 00:00:13,075 It's a wonderful place. 3 00:00:13,927 --> 00:00:18,955 But don't take it for granted, because one day it might just vanish - forever. 4 00:00:28,207 --> 00:00:31,040 This is the story of the universe we live in... 5 00:00:32,207 --> 00:00:35,279 ..and the dangers we face just by being here. 6 00:00:42,647 --> 00:00:47,516 We'll fly with the comets and asteroids which threaten all life on our planet. 7 00:00:51,327 --> 00:00:56,117 Here on Earth, we'll recreate our sun's headlong plunge around the galaxy 8 00:00:56,287 --> 00:01:00,724 and watch disasters unfold which could spell the end for us all. 9 00:01:04,447 --> 00:01:07,359 Our planet is under threat. 10 00:01:09,767 --> 00:01:11,564 Our mission... 11 00:01:13,287 --> 00:01:15,562 ..is to stay alive. 12 00:01:39,687 --> 00:01:42,838 If you're a gambler, this is the planet to live on, 13 00:01:43,007 --> 00:01:45,999 because just by being here, we're all taking a risk. 14 00:01:48,287 --> 00:01:51,438 And the odds are stacked against us. 15 00:01:53,607 --> 00:01:56,246 Do you feel lucky? You should do. 16 00:01:56,407 --> 00:01:59,558 You may not realise it, but we are all winners. 17 00:02:04,407 --> 00:02:07,080 We human beings are lucky to be here, 18 00:02:07,247 --> 00:02:10,557 because the universe keeps trying to wipe us out. 19 00:02:13,167 --> 00:02:14,566 Trying... 20 00:02:17,247 --> 00:02:19,203 ..and failing. 21 00:02:21,967 --> 00:02:27,405 We have survived every disaster the universe has ever thrown at us - so far. 22 00:02:29,487 --> 00:02:32,206 But our run of luck won't last forever. 23 00:02:36,967 --> 00:02:41,006 When it ends, our planet and our entire species will cease to exist... 24 00:02:44,967 --> 00:02:47,879 ..unless we can do something about it. 25 00:02:56,167 --> 00:02:59,637 Could our whole planet really be in danger? 26 00:02:59,807 --> 00:03:05,359 What could threaten a globe 13,000 km across, or 6 billion people? 27 00:03:11,167 --> 00:03:15,445 To understand the threat, you have to see it first hand. 28 00:03:19,087 --> 00:03:23,160 I want to show you planet Earth as it was in its earliest days. 29 00:03:23,327 --> 00:03:25,761 (WHOOSHING AND CRACKLING) 30 00:03:28,127 --> 00:03:31,324 This is where it all begins. 31 00:03:33,767 --> 00:03:36,486 We're lucky there's even a planet here for us to live on, 32 00:03:36,647 --> 00:03:40,845 because it was very nearly blown apart before life had even begun. 33 00:03:46,567 --> 00:03:52,164 This is planet Earth, billions of years ago, at the very beginning of its life. 34 00:03:52,327 --> 00:03:55,922 As you can see, it is under attack. 35 00:03:56,967 --> 00:04:02,724 These are asteroids, rocks left over from the creation of the planets themselves. 36 00:04:07,567 --> 00:04:13,039 Some of them were vast, and one of them was on a collision course with Earth. 37 00:04:19,327 --> 00:04:22,558 This collision nearly smashed our Earth to pieces. 38 00:04:23,847 --> 00:04:29,797 We were hit by a ball of molten rock the size of Mars travelling at colossal speed. 39 00:04:32,767 --> 00:04:35,600 (EXPLOSION) 40 00:04:51,287 --> 00:04:54,802 The impact ripped huge chunks out of our planet. 41 00:04:54,967 --> 00:04:58,676 Somehow it survived. But what about the future? 42 00:04:58,847 --> 00:05:02,999 Smaller chunks of rock are still flying around our solar system today. 43 00:05:06,327 --> 00:05:08,636 We call them asteroids, 44 00:05:08,807 --> 00:05:12,322 and they could put an end to human civilisation. 45 00:05:17,607 --> 00:05:21,725 Asteroids range in size from pebbles to mountains, or even bigger. 46 00:05:21,887 --> 00:05:25,926 And they're dangerous. They're flying around at incredible speeds. 47 00:05:26,087 --> 00:05:30,399 To get an idea of the damage they can do, just take a trip to the moon. 48 00:05:30,567 --> 00:05:36,119 (MISSION CONTROL) Three, two one, zero. All engines running. 49 00:05:36,287 --> 00:05:40,519 (BROADCAST) Man, a species born and who's lived all his life on Earth, 50 00:05:40,687 --> 00:05:43,360 moves with this journey out into the solar system. 51 00:05:43,527 --> 00:05:46,883 What can you say about a sight like that? 52 00:05:47,047 --> 00:05:50,119 (MISSION CONTROL) You are go to continue power descent. 53 00:05:53,167 --> 00:05:55,886 In 1969, for the first time ever, 54 00:05:56,047 --> 00:05:59,437 human beings walked on the surface of another world... 55 00:05:59,607 --> 00:06:03,919 (BANG, FOLLOWED BY ASTRONAUT'S VOICE) 56 00:06:04,087 --> 00:06:06,043 ..the moon. 57 00:06:08,007 --> 00:06:10,885 Tranquillity Base here. The eagle has landed. 58 00:06:11,047 --> 00:06:13,925 (MISSION CONTROL) Roger, Tranquillity, we copy. 59 00:06:18,207 --> 00:06:23,361 And what a world it was - airless, barren, hostile. 60 00:06:31,247 --> 00:06:35,286 And bearing the disturbing evidence of a terrifying threat. 61 00:06:37,287 --> 00:06:39,676 The moon is scarred with craters, 62 00:06:39,847 --> 00:06:43,442 the marks of countless asteroids that have slammed into it. 63 00:06:48,167 --> 00:06:50,556 The moon is under attack. 64 00:06:55,247 --> 00:07:00,924 And travelling through space, alongside the moon, is another planet, 65 00:07:01,087 --> 00:07:03,920 the one we call home. 66 00:07:05,047 --> 00:07:08,198 So why aren't we taking the same pounding? 67 00:07:16,327 --> 00:07:18,761 There's a simple answer to that... 68 00:07:22,327 --> 00:07:23,965 we are. 69 00:07:33,727 --> 00:07:39,006 This crater was formed in a few seconds about 49,000 years ago. 70 00:07:40,607 --> 00:07:45,442 It's almost 1.2 kilometres in diameter. It's almost 200 metres deep. 71 00:07:45,607 --> 00:07:49,520 It was caused by an asteroid about 40 metres in diameter. 72 00:07:49,687 --> 00:07:53,839 It came in with a velocity of about 25 km/second, 73 00:07:54,007 --> 00:07:57,795 and it exploded with the force of a 15-megaton hydrogen bomb. 74 00:07:57,967 --> 00:08:00,003 (EXPLOSIONS) 75 00:08:05,287 --> 00:08:07,926 This is Meteor Crater in Arizona. 76 00:08:08,087 --> 00:08:13,844 Geologist Jeff Wynn thinks that what happened here could happen again, soon. 77 00:08:18,847 --> 00:08:21,486 Local effects would have been devastating. 78 00:08:21,647 --> 00:08:27,040 Anything within the circumference of the crater would have been obliterated. 79 00:08:28,807 --> 00:08:34,518 If you were an animal grazing within a few kilometres, you would have been killed. 80 00:08:34,687 --> 00:08:37,918 If you were beyond that, depending on where the wind was blowing, 81 00:08:38,087 --> 00:08:41,079 the ejector coming down would have killed you. 82 00:08:41,247 --> 00:08:46,116 This is just one example of what could happen if one of these things did hit. 83 00:08:48,287 --> 00:08:53,725 Geologists are discovering more and more evidence of asteroid impacts here on Earth. 84 00:08:56,247 --> 00:08:58,807 Meteor Crater would be hard to miss. 85 00:08:58,967 --> 00:09:01,561 Other impacts are more difficult to spot. 86 00:09:06,287 --> 00:09:10,644 But we have seen them. We've photographed them from space. 87 00:09:10,807 --> 00:09:16,962 These are the remains of titanic collisions, some of them vast, 20 or 30 km across. 88 00:09:20,207 --> 00:09:23,802 The Earth is being pounded all the time. 89 00:09:25,287 --> 00:09:29,246 Siberia, 1908, an entire forest was flattened. 90 00:09:33,287 --> 00:09:36,484 There was an impact in Saudi Arabia in 1933. 91 00:09:38,127 --> 00:09:40,118 (MUFFLED ROAR) 92 00:09:41,287 --> 00:09:44,882 This was caught on camera in Canada in 1972. 93 00:09:45,047 --> 00:09:49,996 A near miss - it flew back out into space. If it had crashed on Earth, 94 00:09:50,167 --> 00:09:54,206 it would have exploded with more force than an atom bomb. 95 00:10:00,447 --> 00:10:04,360 Amazingly, in all these events, no one at all was killed. 96 00:10:08,287 --> 00:10:13,759 But even if an asteroid doesn't hit us, it could do something even more dangerous. 97 00:10:18,207 --> 00:10:20,596 It could hit the sea. 98 00:10:22,447 --> 00:10:27,202 If a big asteroid smashes into the ocean, it could create a huge deadly wave 99 00:10:27,367 --> 00:10:30,723 that could wipe out entire cities. 100 00:10:39,087 --> 00:10:41,476 (WYNN) I think there's a realistic possibility 101 00:10:41,647 --> 00:10:46,277 that something like this could cause serious problems to human civilisation 102 00:10:46,447 --> 00:10:48,881 some time in the next century or two. 103 00:10:50,247 --> 00:10:54,001 It's not an appealing thought, but the threat is real. 104 00:10:54,167 --> 00:10:57,239 Whole cities could be obliterated from space. 105 00:11:04,687 --> 00:11:07,121 Whether it's your city comes down to luck. 106 00:11:07,287 --> 00:11:10,199 But before you feel too lucky, think about this. 107 00:11:10,367 --> 00:11:12,722 It may not matter where you live. 108 00:11:12,887 --> 00:11:17,722 There are things out there which could wipe all life from the face of the planet. 109 00:11:26,127 --> 00:11:29,324 Space contains dangers that make asteroids... 110 00:11:30,807 --> 00:11:32,798 ..seem utterly insignificant. 111 00:11:34,247 --> 00:11:38,525 Our telescopes have captured images of truly colossal disasters. 112 00:11:40,847 --> 00:11:44,840 This photograph shows a star a hundred times bigger than our sun 113 00:11:45,007 --> 00:11:48,602 blasting incandescent gas out into space. 114 00:11:57,007 --> 00:11:58,998 And this is a black hole 115 00:11:59,167 --> 00:12:03,479 spewing out jets of super-hot matter at close to the speed of light. 116 00:12:05,367 --> 00:12:10,566 If these had been near us, there's almost no chance that we'd have survived. 117 00:12:18,207 --> 00:12:21,677 It looks as though fortune has been on our side. 118 00:12:22,927 --> 00:12:25,760 At least it has so far. 119 00:12:25,927 --> 00:12:28,521 But for how much longer? 120 00:12:31,607 --> 00:12:37,364 Professor Mike Rampino thinks the odds for long-term survival of life on Earth are slim. 121 00:12:38,887 --> 00:12:43,039 Luck plays a big role in the existence of life on the planet Earth. 122 00:12:43,207 --> 00:12:46,722 You have to realise that the galaxy is a very violent place. 123 00:12:46,887 --> 00:12:51,324 If we get unlucky, that could put an end to complex life on the planet. 124 00:12:58,247 --> 00:13:00,238 Here's the problem. 125 00:13:02,247 --> 00:13:05,762 We don't notice it, but planet Earth is on the move. 126 00:13:08,127 --> 00:13:10,243 While we get on with our lives, 127 00:13:10,407 --> 00:13:15,606 the world is hurtling around our galaxy at 230 kilometres a second. 128 00:13:17,887 --> 00:13:22,802 And high speed means high risk - some you win, some you lose. 129 00:13:27,087 --> 00:13:31,478 We may not realise it, but we're on the ride of our lives. 130 00:13:33,847 --> 00:13:37,726 Think of the Earth's orbit as a kind of cosmic roller-coaster ride. 131 00:13:41,607 --> 00:13:46,806 As we move in this orbit, we're moving past gas clouds. 132 00:13:56,007 --> 00:13:59,124 We can come close to black holes. 133 00:14:05,647 --> 00:14:08,445 We can get close to stars. 134 00:14:12,327 --> 00:14:15,285 We can come close to supernova explosions. 135 00:14:18,967 --> 00:14:22,562 Any of these objects could cause catastrophes on the Earth. 136 00:14:29,687 --> 00:14:32,281 Sound incredible? It's very real. 137 00:14:32,447 --> 00:14:35,962 Life on Earth has been all but eradicated on 20 separate occasions. 138 00:14:36,127 --> 00:14:39,324 And to make matters worse, it's going to happen again. 139 00:14:41,447 --> 00:14:45,326 After all, remember what happened to the dinosaurs. 140 00:14:51,367 --> 00:14:54,518 Flying through space is a dangerous business. 141 00:15:01,247 --> 00:15:05,160 It's not just that we're moving, it's where we're going. 142 00:15:05,327 --> 00:15:10,879 Planet Earth regularly flies through some of the most dangerous areas of the galaxy. 143 00:15:13,807 --> 00:15:16,037 (RAMPINO) If one could speed up time 144 00:15:16,207 --> 00:15:20,439 and watch the orbit of the Earth through the galaxy and around the galaxy, 145 00:15:20,607 --> 00:15:24,486 it would look like a very, very fast carousel - 146 00:15:24,647 --> 00:15:29,198 the sun and the planets moving up and down, 147 00:15:29,367 --> 00:15:33,963 and at the same time moving around the galaxy very rapidly. 148 00:15:36,167 --> 00:15:40,206 We go around the galaxy about once every 250 million years. 149 00:15:40,367 --> 00:15:44,565 But, also, we go through the densest part of the galaxy every 30 million years. 150 00:15:44,727 --> 00:15:46,558 That's the danger zone. 151 00:15:53,327 --> 00:15:58,879 Every 30 million years, planet Earth travels through a region heavily packed with stars. 152 00:16:01,847 --> 00:16:05,362 And it so happens that it's every 30 million years or so 153 00:16:05,527 --> 00:16:08,758 that life on Earth comes close to being wiped out. 154 00:16:11,247 --> 00:16:13,044 Coincidence? 155 00:16:25,767 --> 00:16:31,842 Here is our galaxy, a huge flat pancake of 400,000 million stars, all whirling around. 156 00:16:32,007 --> 00:16:36,205 The brightest areas are where the stars are most tightly packed. 157 00:16:36,367 --> 00:16:39,040 These are the danger zones. 158 00:16:39,207 --> 00:16:42,916 And this star is our sun. 159 00:16:45,287 --> 00:16:48,279 At the moment... 160 00:16:49,127 --> 00:16:54,804 ..it's just there, just another pinprick in the cloud of stars that makes up our galaxy. 161 00:16:54,967 --> 00:16:58,676 But take a closer look and see how it's moving. 162 00:17:08,407 --> 00:17:12,002 It doesn't just go round the galaxy. It also goes up and down. 163 00:17:12,167 --> 00:17:14,727 And where the sun goes, the Earth goes. 164 00:17:14,887 --> 00:17:18,800 So, regular as clockwork, we plunge through the danger zone. 165 00:17:19,847 --> 00:17:23,681 And every time we do so, the odds are stacked against us. 166 00:17:29,327 --> 00:17:31,602 Here's how it works. 167 00:17:35,327 --> 00:17:40,037 This is our sun, and each of those other dots is a star. 168 00:17:42,327 --> 00:17:45,603 As our sun bobs up and down through the galaxy, 169 00:17:45,767 --> 00:17:48,122 we're passing them by the million. 170 00:17:48,287 --> 00:17:52,917 And where the stars are densest, the danger is greatest. 171 00:18:01,167 --> 00:18:04,000 The reason those other stars are dangerous 172 00:18:04,167 --> 00:18:07,716 is the powerful effect of their gravity on our solar system. 173 00:18:11,007 --> 00:18:15,046 Fly outwards from the sun, away from the Earth and the other planets, 174 00:18:15,207 --> 00:18:19,246 and eventually you encounter these: chunks of ice, trillions of them, 175 00:18:19,407 --> 00:18:22,160 a vast cloud in space. 176 00:18:24,367 --> 00:18:29,043 If another star comes too close, its gravity disturbs the cloud... 177 00:18:31,327 --> 00:18:34,922 ..and catapults ice chunks in towards the sun. 178 00:18:39,207 --> 00:18:43,758 More than 10 km across, travelling at 40 km a second, 179 00:18:43,927 --> 00:18:48,239 it begins its million-year journey into the heart of our solar system. 180 00:18:51,247 --> 00:18:54,762 We know these huge snowballs by another name. 181 00:18:56,247 --> 00:18:58,681 This is a comet. 182 00:19:03,247 --> 00:19:08,765 As it plunges towards the sun, it warms up and belches out a haze of gas and dust. 183 00:19:12,527 --> 00:19:16,486 An immense cloud trails through space behind it... 184 00:19:18,327 --> 00:19:20,716 ..the comet's tail. 185 00:19:22,327 --> 00:19:27,959 But this comet doesn't hit the sun. It skims round it and out. 186 00:19:31,327 --> 00:19:36,765 It drifts past Mercury, and the planet's gravity swings it onto a new path. 187 00:19:41,287 --> 00:19:44,085 Finally, it shoots past the moon 188 00:19:44,247 --> 00:19:47,398 and on to a collision course with Earth. 189 00:20:03,367 --> 00:20:08,316 This is what happened to the dinosaurs 65 million years ago. 190 00:20:09,207 --> 00:20:11,641 How much time have WE got? 191 00:20:16,247 --> 00:20:19,717 (RAMPINO) So far we've been lucky. If you look at the history of life on the Earth, 192 00:20:19,887 --> 00:20:23,766 the average lifetime of a species is just a few million years. 193 00:20:23,927 --> 00:20:27,397 Human beings have been around for a few million years. 194 00:20:29,967 --> 00:20:35,246 It doesn't bode well for the future of the existence of human beings on the Earth. 195 00:20:39,567 --> 00:20:43,321 We last passed through the danger zone one million years ago. 196 00:20:43,487 --> 00:20:46,399 But that doesn't mean we're safe yet. 197 00:20:49,807 --> 00:20:54,927 Because a million years is how long it takes for comets to enter our solar system. 198 00:21:00,327 --> 00:21:05,003 And in July 1994, one smashed straight into Jupiter, 199 00:21:05,167 --> 00:21:08,000 drawn in by its immense gravity. 200 00:21:12,327 --> 00:21:16,764 These blurred photographs reveal a colossal explosion. 201 00:21:21,087 --> 00:21:24,682 It covered an area bigger than our entire planet. 202 00:21:32,287 --> 00:21:37,600 If Jupiter hadn't intercepted that comet, if it had hit the Earth instead, 203 00:21:37,767 --> 00:21:40,361 it could have been the end of us. 204 00:22:00,567 --> 00:22:02,956 I told you we were lucky. 205 00:22:07,447 --> 00:22:12,237 It's not just that Jupiter saved us six years ago. It's saved us thousands of times. 206 00:22:16,087 --> 00:22:19,204 It's been doing so since the dawn of our solar system. 207 00:22:19,367 --> 00:22:22,996 Without Jupiter, life on Earth would never even have got started. 208 00:22:28,687 --> 00:22:31,997 Remember all those asteroids in the early solar system? 209 00:22:32,167 --> 00:22:37,321 There were so many of them flying around that life couldn't even get started. 210 00:22:40,647 --> 00:22:43,764 What changed that was Jupiter. 211 00:22:43,927 --> 00:22:47,761 Its powerful gravity sucks in anything that comes too close. 212 00:22:57,727 --> 00:23:00,366 You're watching at a million years per second. 213 00:23:00,527 --> 00:23:02,757 Jupiter made life on Earth possible. 214 00:23:02,927 --> 00:23:07,079 It drew the asteroids' fire and shielded our planet. 215 00:23:12,327 --> 00:23:15,524 It's still catching asteroids today. 216 00:23:17,287 --> 00:23:23,556 But unfortunately for us, the number of asteroids out there is all but limitless. 217 00:23:28,047 --> 00:23:31,926 Sooner or later our luck will run out, just as it did for the dinosaurs. 218 00:23:32,087 --> 00:23:36,285 Jupiter can't catch them all. And one is all it takes. 219 00:23:36,447 --> 00:23:38,677 This one, for example. 220 00:23:48,607 --> 00:23:52,395 The question is, what on earth are we going to do about it? 221 00:24:04,207 --> 00:24:07,005 It seems we have a problem. 222 00:24:12,407 --> 00:24:15,683 This asteroid is huge, 50 km across, 223 00:24:15,847 --> 00:24:20,159 100 billion tonnes of rock surrounded by clouds of dust and debris. 224 00:24:20,327 --> 00:24:23,000 It's travelling at 40 km a second. 225 00:24:24,047 --> 00:24:27,164 And it's heading straight towards Earth. 226 00:24:33,287 --> 00:24:36,279 So what ARE we going to do about it? 227 00:24:36,447 --> 00:24:39,325 The American military are on alert. 228 00:24:40,327 --> 00:24:45,959 The man who runs Earth's asteroid detection system is Sergeant Rob Medrano. 229 00:24:52,607 --> 00:24:55,485 Comets and asteroids represent 230 00:24:55,647 --> 00:24:58,957 the most significant threat that we have from space. 231 00:25:00,287 --> 00:25:05,361 They do impact the Earth routinely, but mostly objects that are very small. 232 00:25:08,447 --> 00:25:14,443 We're concerned about those large objects that penetrate the Earth's atmosphere. 233 00:25:14,607 --> 00:25:19,078 With that in mind, on average we're discovering about four a month. 234 00:25:27,287 --> 00:25:33,157 The asteroid passes Mars. It is now only 45 days from the Earth. 235 00:25:36,567 --> 00:25:39,127 Already time is running out for us all. 236 00:25:39,287 --> 00:25:44,884 Detecting the threat is not enough. The point is to DO something about it. 237 00:25:51,647 --> 00:25:53,046 (WYNN) There are several possibilities. 238 00:25:53,207 --> 00:25:58,804 One is to send a rocket up with a nuclear device and blow it to pieces. 239 00:25:59,927 --> 00:26:04,079 Another possibility is to put chemical rockets on the object 240 00:26:04,247 --> 00:26:06,238 and try to shove it out of the way. 241 00:26:06,407 --> 00:26:13,040 This all requires that we have time to mount a project and do something about it. 242 00:26:26,927 --> 00:26:32,320 There are two possibilities for human beings to survive far into the future. 243 00:26:32,487 --> 00:26:35,445 One is some kind of planetary protection. 244 00:26:36,967 --> 00:26:42,087 The other is insurance - moving off of this planet onto other planets... 245 00:26:45,287 --> 00:26:48,643 ..so if there are catastrophes on this individual planet, 246 00:26:48,807 --> 00:26:52,277 it wouldn't wipe out human beings entirely. 247 00:27:00,687 --> 00:27:04,646 The potential exists for an asteroid to impact the Earth 248 00:27:04,807 --> 00:27:09,597 that would essentially wipe out life as we know it. 249 00:27:12,087 --> 00:27:14,806 (MUFFLED ROAR) 250 00:27:14,967 --> 00:27:17,720 (ALARM) 251 00:27:17,887 --> 00:27:21,004 In terms of defending ourselves today, 252 00:27:21,167 --> 00:27:26,321 predicting where the asteroid is going to actually impact, that's really all that we have. 253 00:27:28,087 --> 00:27:30,078 (MUFFLED ROAR) 254 00:27:38,327 --> 00:27:41,160 So far, we have survived. 255 00:27:43,327 --> 00:27:48,640 But what about the future? To safeguard that, we should be acting now. 256 00:27:51,407 --> 00:27:55,286 One day our planet's luck will run out. It's a matter of time. 257 00:27:55,447 --> 00:27:58,405 We must develop the technology to defend ourselves. 258 00:28:02,167 --> 00:28:05,876 Because if we're not prepared, the odds are that one day... 259 00:28:06,047 --> 00:28:08,800 (ROAR) 260 00:28:14,407 --> 00:28:18,605 ..one day the human race may cease to exist.