1 00:00:05,240 --> 00:00:08,800 By taking our sense of sight far beyond the realm of our forebears' 2 00:00:08,880 --> 00:00:13,200 imagination, these wonderful instruments, the telescopes, open the way to 3 00:00:13,280 --> 00:00:17,240 a deeper and more perfect understanding of nature. - René Descartes, 1637 4 00:00:17,720 --> 00:00:22,520 For millennia mankind gazed out into the mesmerising night sky 5 00:00:22,600 --> 00:00:28,320 without recognising the stars of our own Milky Way Galaxy as other suns 6 00:00:28,400 --> 00:00:33,400 or the billions of sister galaxies making up the rest of our Universe 7 00:00:35,440 --> 00:00:38,760 or that we are merely punctuation in the Universe’s 8 00:00:38,840 --> 00:00:42,480 13.7 billion year-long story. 9 00:00:42,560 --> 00:00:46,080 With only our eyes as observing tools we had no means of 10 00:00:46,160 --> 00:00:50,120 finding solar systems around other stars, or of determining 11 00:00:50,200 --> 00:00:55,000 whether life exists elsewhere in the Universe. 12 00:00:58,080 --> 00:01:00,320 Today we are well on our way to unravelling many of the 13 00:01:00,400 --> 00:01:03,520 mysteries of the Universe, living in what may be the most remarkable 14 00:01:03,600 --> 00:01:05,920 age of astronomical discovery. 15 00:01:05,960 --> 00:01:08,960 I am Dr. J and I will be your guide to the telescope - 16 00:01:09,040 --> 00:01:11,840 the amazing instrument that proved to be mankind's 17 00:01:11,920 --> 00:01:15,480 gateway to the Universe. 18 00:01:17,920 --> 00:01:21,840 EYES ON THE SKIES 400 Years of Telescopic Discovery 19 00:01:22,200 --> 00:01:26,920 1. New views from the skies 20 00:01:28,960 --> 00:01:32,120 Four centuries ago, in 1609, a man walked out 21 00:01:32,240 --> 00:01:34,600 into the fields near his home. 22 00:01:34,680 --> 00:01:39,000 He pointed his homemade telescope at the Moon, the planets and the stars. 23 00:01:39,080 --> 00:01:42,560 His name was Galileo Galilei. 24 00:01:44,040 --> 00:01:47,280 Astronomy would never be the same again. 25 00:02:07,440 --> 00:02:12,400 Today, 400 years after Galileo first pointed a telescope to the skies 26 00:02:12,600 --> 00:02:18,280 astronomers use giant mirrors on remote mountaintops to survey the heavens. 27 00:02:18,360 --> 00:02:23,480 Radio telescopes collect faint chirps and whispers from outer space. 28 00:02:23,560 --> 00:02:27,640 Scientists have even launched telescopes into Earth orbit 29 00:02:27,720 --> 00:02:31,920 high above the disturbing effects of our atmosphere. 30 00:02:33,440 --> 00:02:38,640 And the view has been breathtaking! 31 00:02:42,960 --> 00:02:46,600 However, Galileo did not, in fact, invent the telescope. 32 00:02:46,680 --> 00:02:49,720 That credit goes to Hans Lipperhey, a slightly obscure 33 00:02:49,800 --> 00:02:53,400 Dutch-German spectacle maker. 34 00:02:53,480 --> 00:02:57,840 But Hans Lipperhey never used this telescope to look at the stars. 35 00:02:57,920 --> 00:03:00,800 Instead, he though his new invention would mainly benefit 36 00:03:00,880 --> 00:03:03,600 seafarers and soldiers. 37 00:03:03,760 --> 00:03:07,240 Lipperhey came from Middelburg, then a large trading city 38 00:03:07,320 --> 00:03:10,440 in the fledgling Dutch Republic. 39 00:03:13,960 --> 00:03:18,040 In 1608 Lipperhey found that when viewing a distant object 40 00:03:18,120 --> 00:03:24,000 through a convex and a concave lens, the object would be magnified, if the 41 00:03:24,080 --> 00:03:29,600 two lenses were placed at just the right distance from one another. 42 00:03:29,680 --> 00:03:33,760 The telescope was born! 43 00:03:33,840 --> 00:03:37,480 In September 1608, Lipperhey revealed his new invention to 44 00:03:37,560 --> 00:03:39,840 Prince Maurits of the Netherlands. 45 00:03:39,920 --> 00:03:42,800 He could not have chosen a more advantageous moment because 46 00:03:42,880 --> 00:03:45,840 at that time the Netherlands were embroiled in the 47 00:03:45,920 --> 00:03:49,320 80 Years' War with Spain. 48 00:03:55,320 --> 00:03:59,080 The new spyglass could magnify objects and so it could reveal 49 00:03:59,160 --> 00:04:02,280 enemy ships and troops that were too distant to be seen 50 00:04:02,360 --> 00:04:04,360 by the unaided eye. 51 00:04:04,440 --> 00:04:07,440 A very useful invention indeed! 52 00:04:07,520 --> 00:04:12,000 But the Dutch government never granted Lipperhey a patent for his telescope. 53 00:04:12,080 --> 00:04:15,400 The reason was that other merchants also claimed the invention 54 00:04:15,480 --> 00:04:19,200 especially Lipperhey's competitor Sacharias Janssen. 55 00:04:19,280 --> 00:04:21,480 The dispute was never resolved. 56 00:04:21,560 --> 00:04:27,880 And to this day, the true origins of the telescope remain shrouded in mystery. 57 00:04:28,880 --> 00:04:32,680 Italian astronomer Galileo Galilei, the father of modern physics 58 00:04:32,760 --> 00:04:37,600 heard about the telescope and decided to build his own. 59 00:04:38,320 --> 00:04:42,360 About ten months ago, a report reached my ears that a certain 60 00:04:42,440 --> 00:04:48,200 Fleming had constructed a spyglass by means of which visible objects 61 00:04:48,280 --> 00:04:52,960 though very distant from the eye of the observer, were distinctly 62 00:04:53,040 --> 00:04:56,120 seen as if nearby. 63 00:04:56,480 --> 00:04:59,440 Galileo was the greatest scientist of his time. 64 00:04:59,520 --> 00:05:02,560 He was also a strong supporter of the new worldview advocated 65 00:05:02,640 --> 00:05:06,160 by the Polish astronomer Nicolaus Copernicus, who proposed that 66 00:05:06,240 --> 00:05:10,440 the Earth orbited the Sun, instead of the other way around. 67 00:05:11,520 --> 00:05:14,240 Based on what he had heard of the Dutch telescope, Galileo 68 00:05:14,320 --> 00:05:16,560 constructed his own instruments. 69 00:05:16,640 --> 00:05:19,160 They were of a much better quality. 70 00:05:20,520 --> 00:05:25,320 Finally, sparing neither labour nor expenses, I succeeded 71 00:05:25,400 --> 00:05:29,640 in constructing for myself so excellent an instrument that 72 00:05:29,720 --> 00:05:33,880 objects seen by means of it appeared nearly one thousand 73 00:05:33,960 --> 00:05:38,800 times larger than when regarded with our natural vision. 74 00:05:39,680 --> 00:05:43,600 It was time to train the telescope on the heavens. 75 00:05:45,880 --> 00:05:49,640 I have been led to the opinion and conviction that the surface 76 00:05:49,760 --> 00:05:53,480 of the moon is not smooth, uniform and precisely spherical 77 00:05:53,720 --> 00:05:57,440 as a great number of philosophers believe it to be 78 00:05:57,520 --> 00:06:01,680 but is uneven, rough, and full of cavities and prominences 79 00:06:01,760 --> 00:06:06,240 being not unlike the face of the Earth. 80 00:06:11,600 --> 00:06:15,320 A landscape of craters, mountains, and valleys. 81 00:06:15,400 --> 00:06:18,320 A world like our own! 82 00:06:19,560 --> 00:06:24,040 A few weeks later, in January 1610, Galileo looked at Jupiter. 83 00:06:24,120 --> 00:06:28,560 Close to the planet he saw four pricks of light that changed 84 00:06:28,680 --> 00:06:32,960 their position on the sky night after night along with Jupiter. 85 00:06:33,040 --> 00:06:37,880 It was like a slow, cosmic ballet of satellites orbiting the planet. 86 00:06:37,960 --> 00:06:40,720 These four pricks of light would come to be known as 87 00:06:40,800 --> 00:06:43,560 the Galilean moons of Jupiter. 88 00:06:43,680 --> 00:06:46,240 What else did Galileo discover? 89 00:06:46,320 --> 00:06:48,400 The phases of Venus! 90 00:06:48,520 --> 00:06:51,880 Just like the Moon, Venus waxes and wanes from crescent to 91 00:06:51,960 --> 00:06:54,200 full and back again. 92 00:06:54,280 --> 00:06:58,560 Strange appendages on either side of Saturn. 93 00:06:58,680 --> 00:07:01,160 Dark spots on the face of the Sun. 94 00:07:01,280 --> 00:07:03,440 And, of course, stars. 95 00:07:03,520 --> 00:07:06,400 Thousands of them, maybe even millions. 96 00:07:06,480 --> 00:07:09,320 Each too faint to be seen by the naked eye. 97 00:07:09,440 --> 00:07:13,880 It was as if mankind had suddenly thrown off its blindfold. 98 00:07:13,960 --> 00:07:18,000 There was a whole Universe to discover out there. 99 00:07:23,440 --> 00:07:27,720 News about the telescope spread across Europe like wildfire. 100 00:07:27,840 --> 00:07:32,080 In Prague, at the court of Emperor Rudolph II, Johannes Kepler 101 00:07:32,200 --> 00:07:34,760 improved the design of the instrument. 102 00:07:34,840 --> 00:07:38,800 In Antwerp, Dutch cartographer Michael van Langren produced 103 00:07:38,920 --> 00:07:41,880 the first reliable maps of the Moon showing what he believed to be 104 00:07:41,960 --> 00:07:44,400 continents and oceans. 105 00:07:44,520 --> 00:07:49,640 And Johannes Hevelius, a wealthy brewer in Poland, built huge 106 00:07:49,720 --> 00:07:53,200 telescopes at his observatory in Danzig. 107 00:07:53,280 --> 00:07:57,840 This observatory was so large that it covered three rooftops! 108 00:07:59,200 --> 00:08:02,240 But the best instruments of the time were probably constructed 109 00:08:02,320 --> 00:08:05,360 by Christiaan Huygens in the Netherlands. 110 00:08:05,440 --> 00:08:11,080 In 1655, Huygens discovered Titan, the largest moon of Saturn. 111 00:08:11,160 --> 00:08:15,160 A few years later, his observations revealed Saturn's ring system 112 00:08:15,240 --> 00:08:20,320 something Galileo had never understood. 113 00:08:20,400 --> 00:08:24,600 And last but not least, Huygens saw dark markings and bright 114 00:08:24,680 --> 00:08:27,360 polar caps on Mars. 115 00:08:27,440 --> 00:08:31,080 Could there be life on this remote, alien world? 116 00:08:31,160 --> 00:08:35,240 The question occupies astronomers to this day. 117 00:08:35,880 --> 00:08:39,480 The earliest telescopes were all refracting telescopes that used 118 00:08:39,560 --> 00:08:42,640 lenses to collect and bring together the starlight. 119 00:08:42,720 --> 00:08:45,440 Later the lenses were replaced with mirrors. 120 00:08:45,520 --> 00:08:49,080 This reflecting telescope was first built by Niccolò Zucchi 121 00:08:49,160 --> 00:08:52,000 and later refined by Isaac Newton. 122 00:08:52,080 --> 00:08:55,720 Now in the late 18th century, the largest mirrors in the world 123 00:08:55,800 --> 00:08:59,560 were cast by William Herschel, an organist turned astronomer 124 00:08:59,640 --> 00:09:02,480 who worked with his sister Caroline. 125 00:09:02,560 --> 00:09:06,200 In their house in Bath, in England, the Herschels poured red-hot 126 00:09:06,280 --> 00:09:09,840 molten metal into a mould and when the whole thing had cooled 127 00:09:09,920 --> 00:09:15,440 off, they would polish the surface so that it would reflect starlight. 128 00:09:15,520 --> 00:09:20,320 During the course of his life, Herschel built more than 400 telescopes. 129 00:09:24,480 --> 00:09:28,360 The largest of these was so huge that he needed four servants to 130 00:09:28,440 --> 00:09:31,560 operate all the various ropes, wheels and pulleys that were 131 00:09:31,640 --> 00:09:36,000 required to track the motions of the stars across the night sky 132 00:09:36,080 --> 00:09:39,440 which is of course caused by the Earth's rotation. 133 00:09:39,520 --> 00:09:43,080 Now Herschel was like a surveyor, he scanned the heavens and 134 00:09:43,160 --> 00:09:46,680 catalogued hundreds of new nebulae and binary stars. 135 00:09:46,760 --> 00:09:50,280 He also discovered that the Milky Way must be a flat disc. 136 00:09:50,360 --> 00:09:54,120 And he even measured the motion of the Solar System through that disk 137 00:09:54,200 --> 00:09:58,800 by observing the relative motions of the stars and the planets. 138 00:09:58,880 --> 00:10:06,360 And then on the 13th of March in 1781, he discovered a new planet - Uranus. 139 00:10:06,440 --> 00:10:10,640 It was over 200 years until NASA's Voyager 2 spacecraft 140 00:10:10,720 --> 00:10:15,840 gave astronomers their first close-up look of this distant world. 141 00:10:16,760 --> 00:10:21,240 In the lush and fertile countryside of central Ireland, William Parsons 142 00:10:21,320 --> 00:10:26,520 the third Earl of Rosse, built the largest telescope of the 19th century. 143 00:10:26,600 --> 00:10:30,520 With a metal mirror a whopping 1.8 metres across, the giant 144 00:10:30,600 --> 00:10:35,240 telescope became known as "The Leviathan of Parsonstown". 145 00:10:35,320 --> 00:10:39,320 On the occasional clear, moonless nights, the Earl sat at the eyepiece 146 00:10:39,440 --> 00:10:44,400 and sailed on a journey through the Universe. 147 00:10:45,280 --> 00:10:50,160 To the Orion Nebula - now known to be a stellar nursery. 148 00:10:50,280 --> 00:10:55,880 On to the mysterious Crab Nebula, the remnant of a supernova explosion. 149 00:10:55,960 --> 00:10:57,880 And the Whirlpool Nebula? 150 00:10:57,960 --> 00:11:02,520 Lord Rosse was the first to note its majestic spiral shape. 151 00:11:02,600 --> 00:11:08,400 A galaxy like our own, with intricate clouds of dark dust and glowing gas 152 00:11:08,480 --> 00:11:12,400 billions of individual stars, and who knows - 153 00:11:12,480 --> 00:11:16,520 maybe even planets like Earth. 154 00:11:18,880 --> 00:11:24,880 The telescope had become our vessel to explore the Universe. 155 00:11:29,400 --> 00:11:33,800 2. Bigger is better 156 00:11:35,760 --> 00:11:38,160 At night, your eyes adapt to the dark. 157 00:11:38,240 --> 00:11:42,320 Your pupils widen to let more light into your eyes. 158 00:11:42,400 --> 00:11:47,560 As a result, you can see dimmer objects, and fainter stars. 159 00:11:47,640 --> 00:11:51,400 Now imagine you had pupils one metre across. 160 00:11:51,480 --> 00:11:55,640 You'd look pretty strange but you'd also have supernatural eyesight! 161 00:11:55,720 --> 00:11:59,120 And that's what telescopes do for you. 162 00:12:01,600 --> 00:12:04,320 A telescope is like a funnel. 163 00:12:04,400 --> 00:12:09,920 Its main lens or mirror collects the starlight and brings it all together into your eye. 164 00:12:12,760 --> 00:12:17,480 The bigger the lens or the mirror of a telescope, the fainter the objects you can see. 165 00:12:17,560 --> 00:12:20,400 So size really is everything. 166 00:12:20,480 --> 00:12:23,080 But how big can you make a telescope? 167 00:12:23,160 --> 00:12:26,120 Well, actually not too big if it's a refractor. 168 00:12:29,160 --> 00:12:32,400 The starlight has to pass through the main lens. 169 00:12:32,480 --> 00:12:35,760 And so you can only support it around its edge. 170 00:12:35,840 --> 00:12:41,600 Now if you make the lens too big it becomes too heavy, and it starts deforming under its own weight. 171 00:12:41,680 --> 00:12:45,320 That means that the image will be distorted. 172 00:12:47,080 --> 00:12:54,040 The largest refractor in history was completed in 1897, at Yerkes Observatory outside Chicago. 173 00:12:54,120 --> 00:12:57,200 Its main lens was just over one metre across. 174 00:12:57,280 --> 00:13:01,800 But its tube was an incredible 18 metres long. 175 00:13:01,880 --> 00:13:08,400 With the completion of the Yerkes telescope, the builders of refracting telescopes had pretty much reached their limit. 176 00:13:08,480 --> 00:13:10,560 You want bigger telescopes? 177 00:13:10,640 --> 00:13:12,520 Think mirrors. 178 00:13:16,760 --> 00:13:22,760 In a reflecting telescope, the starlight bounces off a mirror instead of passing through a lens. 179 00:13:22,840 --> 00:13:29,120 That means that you can make the mirror a lot thinner than a lens, and you can support it from the back. 180 00:13:29,200 --> 00:13:34,320 The result is that you can build a lot larger mirrors than lenses. 181 00:13:35,320 --> 00:13:39,400 Big mirrors came to southern California a century ago. 182 00:13:39,480 --> 00:13:44,600 Back then, Mount Wilson was a remote peak in the wilderness of the San Gabriel mountains. 183 00:13:44,680 --> 00:13:48,800 The sky was clear and the nights were dark. 184 00:13:48,880 --> 00:13:53,360 Here, George Ellery Hale first built a 1.5 metre telescope. 185 00:13:53,440 --> 00:13:58,080 Smaller than Lord Rosse's retired Leviathan, it was of much better quality. 186 00:13:58,160 --> 00:14:01,880 And at a much better site, too. 187 00:14:01,960 --> 00:14:07,360 Hale talked local businessman John Hooker into financing a 2.5 metre instrument. 188 00:14:07,440 --> 00:14:12,240 Tonnes of glass and riveted steel were hauled up Mount Wilson. 189 00:14:12,320 --> 00:14:15,720 The Hooker telescope was completed in 1917. 190 00:14:15,800 --> 00:14:19,960 It would remain the largest telescope in the world for 30 years. 191 00:14:20,040 --> 00:14:25,120 A big piece of cosmic artillery, ready to attack the Universe. 192 00:14:28,200 --> 00:14:30,800 And attack it did. 193 00:14:30,880 --> 00:14:33,920 Along with the incredible size of the new telescope came 194 00:14:33,960 --> 00:14:36,920 transformations in the way the image was viewed. 195 00:14:36,960 --> 00:14:40,480 Astronomers no longer peered through the eyepiece of the new giant. 196 00:14:40,560 --> 00:14:45,640 But instead collected the light on photographic plates for hours on end. 197 00:14:45,720 --> 00:14:50,520 Never before had anyone peered so far into the cosmos. 198 00:14:50,600 --> 00:14:54,840 Spiral nebulae turned out to be brimming with individual stars. 199 00:14:54,920 --> 00:14:59,280 Could they be sprawling stellar systems like our own Milky Way? 200 00:14:59,360 --> 00:15:03,480 In the Andromeda Nebula, Edwin Hubble discovered a particular type of star 201 00:15:03,560 --> 00:15:07,080 that changes its brightness with clocklike precision. 202 00:15:07,160 --> 00:15:11,440 From his observations Hubble was able to deduce the distance to Andromeda: 203 00:15:11,520 --> 00:15:15,680 almost a million light-years. 204 00:15:15,760 --> 00:15:22,440 Spiral nebulae, like Andromeda, were clearly individual galaxies in their own right. 205 00:15:24,160 --> 00:15:27,040 But that wasn't the only incredible thing. 206 00:15:27,120 --> 00:15:31,720 Most of these galaxies were found to be moving away from the Milky Way. 207 00:15:31,800 --> 00:15:37,320 At Mount Wilson, Hubble discovered that the nearby galaxies were receding at small velocities 208 00:15:37,360 --> 00:15:42,200 whereas the distant galaxies were moving away at a much faster pace. 209 00:15:42,280 --> 00:15:43,440 The conclusion? 210 00:15:43,520 --> 00:15:46,240 The Universe was expanding. 211 00:15:46,320 --> 00:15:53,120 The Hooker telescope had given scientists the most profound astronomical discovery of the 20th century. 212 00:15:55,800 --> 00:16:00,320 Thanks to the telescope, we have traced the history of the Universe. 213 00:16:00,400 --> 00:16:04,600 A little less than 14 billion years ago, the Universe was born 214 00:16:04,680 --> 00:16:08,920 in a huge explosion of time and space, matter and energy, called 215 00:16:08,960 --> 00:16:11,280 the Big Bang. 216 00:16:11,360 --> 00:16:17,160 Tiny quantum ripples grew into dense patches in the primordial brew. 217 00:16:17,240 --> 00:16:19,880 From these, galaxies condensed. 218 00:16:19,960 --> 00:16:23,520 A stunning variety of sizes and shapes. 219 00:16:26,280 --> 00:16:30,120 Nuclear fusion in the cores of stars produced new atoms. 220 00:16:30,200 --> 00:16:34,560 Carbon, oxygen, iron, gold. 221 00:16:34,640 --> 00:16:39,320 Supernova explosions blew these heavy elements back into space. 222 00:16:39,400 --> 00:16:42,800 Raw material for the formation of new stars. 223 00:16:42,880 --> 00:16:44,520 And planets! 224 00:16:46,560 --> 00:16:54,600 Someday, somewhere, somehow, simple organic molecules evolved into living organisms. 225 00:16:54,680 --> 00:17:00,280 Life is one miracle in an ever-evolving Universe. 226 00:17:00,360 --> 00:17:02,600 We are stardust. 227 00:17:02,680 --> 00:17:06,720 It's a grand vision and a sweeping story. 228 00:17:06,800 --> 00:17:10,880 Brought to us through telescopic observations. 229 00:17:10,960 --> 00:17:15,360 Imagine: without the telescope we would know about just six planets 230 00:17:15,400 --> 00:17:17,880 one moon, and a few thousand stars. 231 00:17:17,960 --> 00:17:22,120 Astronomy would still be in its infancy. 232 00:17:23,360 --> 00:17:27,160 Like buried treasures, the outposts of the Universe have beckoned to the 233 00:17:27,240 --> 00:17:29,720 adventurous from immemorial times. 234 00:17:29,800 --> 00:17:35,160 Princes and potentates, political or industrial, equally with men of science 235 00:17:35,240 --> 00:17:39,920 have felt the lure of the uncharted seas of space, and through their provision 236 00:17:39,960 --> 00:17:45,120 of instrumental means the sphere of exploration has rapidly widened. 237 00:17:59,480 --> 00:18:02,360 George Ellery Hale had one final dream: 238 00:18:02,440 --> 00:18:06,640 to build a telescope twice as large as the previous record holder. 239 00:18:06,720 --> 00:18:10,600 Meet the grand old lady of 20th century astronomy. 240 00:18:10,680 --> 00:18:15,600 The five metre Hale telescope at Palomar Mountain. 241 00:18:15,680 --> 00:18:20,240 Over five hundred tonnes of moving weight, yet so precisely balanced 242 00:18:20,320 --> 00:18:24,360 that it moves as gracefully as a ballerina. 243 00:18:24,440 --> 00:18:29,920 Its 40 tonne mirror reveals stars 40 million times fainter than the eye can see. 244 00:18:29,960 --> 00:18:34,920 Completed in 1948, the Hale telescope gave us unsurpassed views of planets 245 00:18:34,960 --> 00:18:38,520 star clusters, nebulae and galaxies. 246 00:18:40,760 --> 00:18:44,680 Giant Jupiter, with its many moons. 247 00:18:44,760 --> 00:18:48,760 The stunning Flame Nebula. 248 00:18:48,840 --> 00:18:53,920 Faint wisps of gas in the Orion Nebula. 249 00:18:59,560 --> 00:19:01,800 But could we go bigger still? 250 00:19:01,880 --> 00:19:05,920 Well, soviet astronomers tried in the late 1970s. 251 00:19:05,960 --> 00:19:10,320 High up in the Caucasus mountains, they built the Bolshoi Teleskop Azimutalnyi 252 00:19:10,400 --> 00:19:14,600 sporting a primary mirror six metres in diameter. 253 00:19:14,680 --> 00:19:17,320 But it never really lived up to its expectations. 254 00:19:17,400 --> 00:19:21,440 It was simply too big, too expensive, and too difficult. 255 00:19:21,520 --> 00:19:24,680 So did telescope builders have to give up at that point? 256 00:19:24,760 --> 00:19:28,200 Did they have to bury their dreams of even bigger instruments? 257 00:19:28,280 --> 00:19:31,680 Had the history of the telescope come to a premature end? 258 00:19:31,760 --> 00:19:33,080 Well, of course not. 259 00:19:33,160 --> 00:19:36,200 Today we have 10 metre telescopes in operation. 260 00:19:36,280 --> 00:19:38,840 And even bigger ones are on the drawing board. 261 00:19:38,920 --> 00:19:40,400 What was the solution? 262 00:19:40,480 --> 00:19:42,320 New technologies. 263 00:19:44,000 --> 00:19:48,760 3. Technology to the rescue 264 00:19:48,960 --> 00:19:52,800 Just as modern cars don't look like a Model T Ford anymore, so are present 265 00:19:52,880 --> 00:19:56,280 day telescopes radically different from their classic predecessors 266 00:19:56,360 --> 00:19:58,680 like the five metre Hale telescope. 267 00:19:58,760 --> 00:20:01,880 For one thing, their mounts are much smaller. 268 00:20:01,960 --> 00:20:05,840 The old-style mount is an equatorial one where one of the axis 269 00:20:05,920 --> 00:20:09,720 is always mounted parallel to the Earth's rotation axis. 270 00:20:09,800 --> 00:20:13,480 In order to keep track of the sky's motion, the telescope simply 271 00:20:13,560 --> 00:20:18,200 has to rotate around this axis at the same speed with which the Earth rotates. 272 00:20:18,280 --> 00:20:21,160 Easy, but space-hungry. 273 00:20:21,240 --> 00:20:26,040 The modern day altitude azimuth mounts are much more compact. 274 00:20:26,080 --> 00:20:30,440 With a mount like that, the telescope is pointed much like a cannon. 275 00:20:30,480 --> 00:20:35,240 One simply chooses the bearing, chooses the altitude, and off you go. 276 00:20:35,320 --> 00:20:38,640 The problem is to keep track of the sky's motion. 277 00:20:38,720 --> 00:20:44,240 The telescope pretty much has to rotate around both axis, and at varying speeds. 278 00:20:44,320 --> 00:20:50,720 Essentially this only became possible once telescopes were computer controlled. 279 00:20:50,800 --> 00:20:52,840 A smaller mount is cheaper to build. 280 00:20:52,920 --> 00:20:57,520 Moreover, it fits into a smaller dome which reduces the cost even further 281 00:20:57,600 --> 00:21:00,320 and it improves the image quality. 282 00:21:00,400 --> 00:21:03,800 Take the twin Keck Telescopes on Hawaii, for example. 283 00:21:03,880 --> 00:21:06,600 Although their 10 metre mirrors are twice as large as the one 284 00:21:06,680 --> 00:21:10,440 of the Hale telescope, they nevertheless fit into smaller domes 285 00:21:10,520 --> 00:21:13,240 than the one on Palomar Mountain. 286 00:21:15,080 --> 00:21:17,440 Telescope mirrors have evolved too. 287 00:21:17,520 --> 00:21:19,120 They used to be thick and heavy. 288 00:21:19,200 --> 00:21:21,840 Now they're thin and lightweight. 289 00:21:21,920 --> 00:21:26,800 Mirror shells that can be many metres wide are cast in giant, rotating ovens. 290 00:21:26,880 --> 00:21:30,320 And they are still less than 20 centimetres thick. 291 00:21:30,400 --> 00:21:32,960 An intricate support structure prevents the thin mirror 292 00:21:33,080 --> 00:21:35,200 from cracking under its own weight. 293 00:21:35,280 --> 00:21:39,120 Computer controlled pistons and actuators also help to keep the mirror 294 00:21:39,200 --> 00:21:40,840 in perfect shape. 295 00:21:43,400 --> 00:21:45,520 This system is called active optics. 296 00:21:45,600 --> 00:21:49,840 The idea is to compensate and to correct any deformations of the main mirror 297 00:21:49,920 --> 00:21:54,560 caused by gravity, the wind, or temperature changes. 298 00:21:54,640 --> 00:21:58,240 Now, a thin mirror also weighs much less. 299 00:21:58,320 --> 00:22:01,440 That means that its whole supporting structure, including the mount 300 00:22:01,560 --> 00:22:03,440 can also be a lot trimmer and lighter. 301 00:22:03,520 --> 00:22:05,560 And cheaper! 302 00:22:05,640 --> 00:22:08,360 Now here's the 3.6 metre New Technology Telescope 303 00:22:08,440 --> 00:22:11,760 built by European astronomers in the late 1980s. 304 00:22:11,840 --> 00:22:14,840 It served as a testbed for many of the new technologies 305 00:22:14,920 --> 00:22:16,120 in telescope building. 306 00:22:16,200 --> 00:22:20,960 And even its enclosure has nothing in common with traditional telescope domes. 307 00:22:21,080 --> 00:22:24,240 The New Technology Telescope was a great success. 308 00:22:24,320 --> 00:22:27,280 It was time to break the six metre barrier. 309 00:22:27,600 --> 00:22:31,400 Mauna Kea Observatory sits on the highest point in the Pacific 310 00:22:31,480 --> 00:22:34,960 4200 metres above sea level. 311 00:22:36,960 --> 00:22:41,120 On the beaches of Hawaii, tourists enjoy the Sun and the surf. 312 00:22:41,200 --> 00:22:44,520 But high above them astronomers face chilling temperatures 313 00:22:44,600 --> 00:22:51,160 and altitude sickness in their quest to unravel the mysteries of the Universe. 314 00:22:51,240 --> 00:22:54,120 The Keck Telescopes are among the largest in the world. 315 00:22:54,200 --> 00:22:59,120 Their mirrors are 10 metres across, and wafer-thin. 316 00:22:59,200 --> 00:23:04,040 Tiled like a bathroom floor, they consist of 36 hexagonal segments 317 00:23:04,120 --> 00:23:07,480 each controlled to nanometre precision. 318 00:23:07,560 --> 00:23:11,200 These are true giants, devoted to observing the heavens. 319 00:23:11,280 --> 00:23:14,120 The cathedrals of science. 320 00:23:14,200 --> 00:23:16,600 Nightfall on Mauna Kea. 321 00:23:16,680 --> 00:23:21,720 The Keck Telescopes begin collecting photons from the far reaches of the cosmos. 322 00:23:21,800 --> 00:23:24,520 Their twin mirrors combining to be effectively larger 323 00:23:24,600 --> 00:23:27,440 than all earlier telescopes. 324 00:23:27,520 --> 00:23:30,360 What will be tonight's catch? 325 00:23:34,680 --> 00:23:39,520 A pair of colliding galaxies, billions of light-years away? 326 00:23:39,600 --> 00:23:45,320 A dying star, gasping its last breath into a planetary nebula? 327 00:23:45,400 --> 00:23:51,040 Or maybe an extrasolar planet that might harbour life? 328 00:23:51,120 --> 00:23:55,920 On Cerro Paranal in the Chilean Atacama Desert - the driest place on Earth - 329 00:23:55,960 --> 00:24:00,040 we find by far the biggest astronomy machine ever built: 330 00:24:00,120 --> 00:24:03,560 the European Very Large Telescope. 331 00:24:16,200 --> 00:24:19,520 The VLT is really four telescopes in one. 332 00:24:19,600 --> 00:24:22,760 Each sporting an 8.2 metre mirror. 333 00:24:22,840 --> 00:24:24,120 Antu. 334 00:24:24,200 --> 00:24:25,240 Kueyen. 335 00:24:25,320 --> 00:24:26,320 Melipal. 336 00:24:26,400 --> 00:24:27,760 Yepun. 337 00:24:27,840 --> 00:24:33,440 Native Mapuche names for the Sun, the Moon, the Southern Cross and Venus. 338 00:24:33,520 --> 00:24:37,800 The huge mirrors were cast in Germany, polished in France, shipped to Chile 339 00:24:37,880 --> 00:24:41,240 and then slowly transported across the desert. 340 00:24:41,320 --> 00:24:44,960 At sunset, the telescope enclosures open up. 341 00:24:45,040 --> 00:24:48,560 Starlight rains down on the VLT mirrors. 342 00:24:49,280 --> 00:24:52,080 New discoveries are made. 343 00:24:55,920 --> 00:24:58,160 A laser pierces the night sky. 344 00:24:58,240 --> 00:25:00,680 It projects an artificial star into the atmosphere 345 00:25:00,760 --> 00:25:03,840 90 kilometres above our heads. 346 00:25:03,920 --> 00:25:06,920 Wavefront sensors measure how the star's image is distorted 347 00:25:06,960 --> 00:25:09,120 by the atmospheric turbulence. 348 00:25:09,200 --> 00:25:12,960 Then, fast computers tell a flexible mirror how it has to 349 00:25:13,040 --> 00:25:15,800 deform itself in order to correct the distortion. 350 00:25:15,880 --> 00:25:18,960 In effect untwinkling the stars. 351 00:25:19,040 --> 00:25:22,600 This is called adaptive optics and it's the big magic trick 352 00:25:22,680 --> 00:25:24,320 of present day astronomy. 353 00:25:24,400 --> 00:25:28,840 Without it, our view of the Universe would look blurred by the atmosphere. 354 00:25:28,920 --> 00:25:32,880 But with it, our images are razor-sharp. 355 00:25:35,480 --> 00:25:39,480 The other piece of optical wizardry is known as interferometry. 356 00:25:39,560 --> 00:25:43,360 The idea is to take the light from two separate telescopes and to 357 00:25:43,440 --> 00:25:46,640 bring it together in a single point, while preserving the 358 00:25:46,720 --> 00:25:49,320 relative shifts between the lightwaves. 359 00:25:49,400 --> 00:25:53,160 If it is done precisely enough the result is that the two telescopes 360 00:25:53,240 --> 00:25:56,600 act as if they were part of a single, colossal mirror 361 00:25:56,680 --> 00:25:59,920 as large as the distance between them. 362 00:25:59,960 --> 00:26:04,040 In effect, interferometry gives your telescope eagle-like vision. 363 00:26:04,120 --> 00:26:07,600 It allows smaller telescopes to reveal a level of detail that 364 00:26:07,680 --> 00:26:12,440 would otherwise only be visible with a much larger telescope. 365 00:26:12,520 --> 00:26:15,600 The twin Keck Telescopes on Mauna Kea regularly team up 366 00:26:15,680 --> 00:26:17,520 as an interferometer. 367 00:26:17,600 --> 00:26:21,440 In the case of the VLT, all four telescopes can work together. 368 00:26:21,520 --> 00:26:24,760 In addition, several smaller auxiliary telescopes can also 369 00:26:24,840 --> 00:26:28,880 join the ranks in order to sharpen up the view even more. 370 00:26:29,840 --> 00:26:33,400 Other big telescopes can be found all over the globe. 371 00:26:33,480 --> 00:26:37,480 Subaru and Gemini North on Mauna Kea. 372 00:26:37,560 --> 00:26:42,240 Gemini South and the Magellan Telescopes in Chile. 373 00:26:42,320 --> 00:26:46,280 The Large Binocular Telescope in Arizona. 374 00:26:48,200 --> 00:26:50,800 They are constructed at the best available sites. 375 00:26:50,840 --> 00:26:53,720 High and dry, clear and dark. 376 00:26:53,840 --> 00:26:56,640 Their eyes are as large as swimming pools. 377 00:26:56,760 --> 00:27:00,400 All kitted out with adaptive optics to counteract the blurring 378 00:27:00,440 --> 00:27:02,080 effects of the atmosphere. 379 00:27:02,200 --> 00:27:05,960 And sometimes they can have the resolution of a virtual behemoth 380 00:27:06,040 --> 00:27:08,640 thanks to interferometry. 381 00:27:09,680 --> 00:27:11,800 Here's what they've shown us. 382 00:27:11,920 --> 00:27:13,400 Planets. 383 00:27:16,600 --> 00:27:18,240 Nebulae. 384 00:27:19,360 --> 00:27:23,960 The actual sizes - and squashed shapes - of some stars. 385 00:27:23,960 --> 00:27:27,160 A cool planet orbiting a brown dwarf. 386 00:27:27,200 --> 00:27:31,480 And giant stars whirling around the core of our Milky Way Galaxy 387 00:27:31,600 --> 00:27:36,720 governed by the gravity of a supermassive black hole. 388 00:27:36,840 --> 00:27:40,400 We've come quite a way since Galileo's day. 389 00:27:40,000 --> 00:27:44,760 4. From silver to silicon 390 00:27:45,840 --> 00:27:49,000 400 years ago, when Galileo Galilei wanted to show others what he 391 00:27:49,120 --> 00:27:53,000 saw through his telescope, he had to make drawings. 392 00:27:53,120 --> 00:27:56,240 The pockmarked face of the Moon. 393 00:27:56,360 --> 00:28:00,400 The dance of the Jovian satellites. 394 00:28:00,520 --> 00:28:02,160 Sunspots. 395 00:28:02,280 --> 00:28:04,160 Or the stars in Orion. 396 00:28:04,280 --> 00:28:06,720 He took his drawings and published them in a small book 397 00:28:06,760 --> 00:28:08,400 The Starry Messenger. 398 00:28:08,440 --> 00:28:10,800 That was the only way he could share his discoveries 399 00:28:10,920 --> 00:28:12,400 with others. 400 00:28:12,440 --> 00:28:16,640 For well over two centuries, astronomers also had to be artists. 401 00:28:16,760 --> 00:28:19,000 Peering through their eyepieces, they made detailed 402 00:28:19,120 --> 00:28:20,960 drawings of what they saw. 403 00:28:21,040 --> 00:28:23,080 The stark landscape of the Moon. 404 00:28:23,200 --> 00:28:25,960 A storm in the atmosphere of Jupiter. 405 00:28:26,040 --> 00:28:29,000 The subtle veil of gas in a distant nebula. 406 00:28:29,120 --> 00:28:32,320 And sometimes they over-interpreted what they saw. 407 00:28:32,440 --> 00:28:36,560 Dark linear features on the surface of Mars were thought to be canals 408 00:28:36,680 --> 00:28:39,880 suggesting civilised life on the surface of the red planet. 409 00:28:39,960 --> 00:28:43,480 We now know that the canals were an optical illusion. 410 00:28:43,600 --> 00:28:47,160 What astronomers really needed was an objective way to record 411 00:28:47,280 --> 00:28:51,480 the light collected by the telescopes without the information first having to 412 00:28:51,520 --> 00:28:54,480 pass through their brains and their drawing pens. 413 00:28:54,600 --> 00:28:57,400 Photography came to the rescue. 414 00:28:58,760 --> 00:29:01,160 The first daguerreotype of the Moon. 415 00:29:01,200 --> 00:29:03,880 It was made in 1840 by Henry Draper. 416 00:29:03,920 --> 00:29:07,240 Photography was less than 15 years old, but astronomers 417 00:29:07,360 --> 00:29:10,880 had already seized on its revolutionary possibilities. 418 00:29:10,920 --> 00:29:13,080 So how did photography work? 419 00:29:13,120 --> 00:29:17,160 Well the sensitive emulsion of a photographic plate contained 420 00:29:17,280 --> 00:29:19,400 small grains of silver halide. 421 00:29:19,440 --> 00:29:22,160 Expose them to light, and they turn dark. 422 00:29:22,200 --> 00:29:24,800 So the result was a negative image of the sky 423 00:29:24,920 --> 00:29:28,080 with dark stars on a light background. 424 00:29:28,200 --> 00:29:31,560 But the real bonus was that a photographic plate can be 425 00:29:31,680 --> 00:29:33,960 exposed for hours on end. 426 00:29:34,040 --> 00:29:36,720 When you take in the night sky with your own eyes 427 00:29:36,760 --> 00:29:39,640 once they're dark adapted, you don't see more and more 428 00:29:39,680 --> 00:29:42,320 stars just by looking longer. 429 00:29:42,440 --> 00:29:45,240 But with a photographic plate you can do just that. 430 00:29:45,360 --> 00:29:48,480 You can collect and add up the light over hours on end. 431 00:29:48,600 --> 00:29:52,880 So a longer exposure reveals more and more stars. 432 00:29:52,920 --> 00:29:54,160 And more. 433 00:29:54,200 --> 00:29:55,240 And more. 434 00:29:55,360 --> 00:29:57,320 And then some. 435 00:29:58,360 --> 00:30:02,000 In the 1950s, the Schmidt telescope at the Palomar Observatory 436 00:30:02,120 --> 00:30:05,160 was used to photograph the entire northern sky. 437 00:30:05,280 --> 00:30:10,080 Almost 2000 photographic plates, each exposed for nearly an hour. 438 00:30:10,120 --> 00:30:12,960 A treasure trove of discovery. 439 00:30:12,960 --> 00:30:17,080 Photography had turned observational astronomy into a true science. 440 00:30:17,200 --> 00:30:21,480 Objective, measurable, and reproducible. 441 00:30:21,600 --> 00:30:23,240 But silver was slow. 442 00:30:23,280 --> 00:30:25,480 You had to be patient. 443 00:30:27,120 --> 00:30:29,880 The digital revolution changed all that. 444 00:30:29,920 --> 00:30:31,640 Silicon replaced silver. 445 00:30:31,760 --> 00:30:34,480 Pixels replaced grains. 446 00:30:36,360 --> 00:30:40,000 Even in consumer cameras, we no longer use photographic film. 447 00:30:40,120 --> 00:30:43,560 Instead, images are recorded on a light-sensitive chip: 448 00:30:43,600 --> 00:30:47,800 a charge coupled device, or CCD for short. 449 00:30:47,920 --> 00:30:51,560 Professional CCDs are extremely efficient. 450 00:30:51,680 --> 00:30:54,640 And to make them even more sensitive, they are cooled down 451 00:30:54,680 --> 00:30:57,960 to well below freezing, using liquid nitrogen. 452 00:30:58,040 --> 00:31:00,720 Almost every photon is registered. 453 00:31:00,760 --> 00:31:05,640 As a result, exposure times can be much shorter. 454 00:31:05,760 --> 00:31:09,480 What the Palomar Observatory Sky Survey achieved in an hour 455 00:31:09,600 --> 00:31:13,160 a CCD can now do in a few short minutes. 456 00:31:13,200 --> 00:31:15,560 Using a smaller telescope. 457 00:31:15,600 --> 00:31:18,080 The silicon revolution is far from over. 458 00:31:18,200 --> 00:31:21,080 Astronomers have built huge CCD cameras with 459 00:31:21,200 --> 00:31:23,560 hundreds of millions of pixels. 460 00:31:23,600 --> 00:31:26,320 And there's more to come. 461 00:31:28,120 --> 00:31:32,560 The big advantage of digital images is that they're, well, digital. 462 00:31:32,600 --> 00:31:35,800 They're all set and ready to be worked on with computers. 463 00:31:35,840 --> 00:31:38,800 Astronomers use specialised software to process their 464 00:31:38,840 --> 00:31:40,880 observations of the sky. 465 00:31:40,880 --> 00:31:45,080 Stretching, or contrast enhancing, reveals the faintest features 466 00:31:45,200 --> 00:31:47,640 of nebulae or galaxies. 467 00:31:47,760 --> 00:31:51,240 Colour coding enhances and brings out the structures that 468 00:31:51,280 --> 00:31:53,640 would otherwise be difficult to see. 469 00:31:53,680 --> 00:31:57,880 Moreover, by combining multiple images of the same object that 470 00:31:57,920 --> 00:32:00,400 were taken through different colour filters, one can 471 00:32:00,520 --> 00:32:04,320 produce spectacular composites that blur the boundary 472 00:32:04,440 --> 00:32:06,720 between science and art. 473 00:32:06,840 --> 00:32:09,880 You too can benefit from digital astronomy. 474 00:32:09,960 --> 00:32:13,960 It has never been so easy to dig up and enjoy the amazing 475 00:32:13,960 --> 00:32:15,800 images of the cosmos. 476 00:32:15,920 --> 00:32:20,080 Pictures of the Universe are always just a mouse click away! 477 00:32:20,680 --> 00:32:24,160 Robotic telescopes, equipped with sensitive electronic detectors 478 00:32:24,280 --> 00:32:27,800 are keeping watch over the sky, right now. 479 00:32:27,920 --> 00:32:30,880 The Sloan telescope in New Mexico has photographed 480 00:32:30,960 --> 00:32:34,000 and catalogued over a hundred million celestial objects 481 00:32:34,120 --> 00:32:38,160 measured distances to a million galaxies, and discovered 482 00:32:38,280 --> 00:32:41,480 a hundred thousand new quasars. 483 00:32:41,520 --> 00:32:44,000 But one survey is not enough. 484 00:32:44,120 --> 00:32:47,400 The Universe is an ever-changing place. 485 00:32:47,520 --> 00:32:51,240 Icy comets come and go, leaving scattered debris 486 00:32:51,280 --> 00:32:53,640 in their wake. 487 00:32:53,760 --> 00:32:56,720 Asteroids zip by. 488 00:32:56,840 --> 00:33:00,560 Distant planets orbit their mother stars, temporarily 489 00:33:00,680 --> 00:33:02,880 blocking part of the star's light. 490 00:33:02,960 --> 00:33:08,800 Supernovas explode, while elsewhere new stars are born. 491 00:33:08,840 --> 00:33:17,960 Pulsars flash, gamma-ray bursts detonate black holes accrete. 492 00:33:18,040 --> 00:33:21,720 To keep track of these grand plays of Nature, astronomers 493 00:33:21,840 --> 00:33:25,240 want to carry out all-sky surveys every year. 494 00:33:25,360 --> 00:33:26,840 Or every month. 495 00:33:26,920 --> 00:33:28,640 Or twice a week. 496 00:33:28,680 --> 00:33:33,800 At least that's the ambitious goal of the Large Synoptic Survey Telescope. 497 00:33:33,920 --> 00:33:39,400 If completed in 2015, its three- gigapixel camera will open up 498 00:33:39,440 --> 00:33:42,080 a webcam window on the Universe. 499 00:33:42,200 --> 00:33:45,960 More than fulfilling astronomers' dreams, this reflecting telescope 500 00:33:46,040 --> 00:33:51,080 will photograph almost the entire sky every three nights. 501 00:33:56,000 --> 00:34:00,760 5. Seeing the invisible 502 00:34:02,360 --> 00:34:05,080 When you listen to your favourite piece of music, your ears pick up 503 00:34:05,160 --> 00:34:08,800 on a very wide range of frequencies, from the deepest rumblings of the 504 00:34:08,920 --> 00:34:12,120 bass to the very highest pitched vibrations. 505 00:34:12,200 --> 00:34:14,960 Now imagine your ears were only sensitive to a very limited 506 00:34:15,360 --> 00:34:16,920 range of frequencies. 507 00:34:16,960 --> 00:34:19,520 You'd miss out on most of the good stuff! 508 00:34:19,600 --> 00:34:23,000 But that's essentially the situations that astronomers are in. 509 00:34:23,080 --> 00:34:26,160 Our eyes are only sensitive to a very narrow range 510 00:34:26,240 --> 00:34:29,000 of light frequencies: visible light. 511 00:34:29,080 --> 00:34:31,560 But we are completely blind to all other forms of 512 00:34:31,640 --> 00:34:33,600 electromagnetic radiation. 513 00:34:33,680 --> 00:34:36,640 However, there are many objects in the Universe that do emit 514 00:34:36,720 --> 00:34:39,960 radiation at other parts of the electromagnetic spectrum. 515 00:34:40,040 --> 00:34:43,760 For example, in the 1930s it was discovered by accident 516 00:34:43,840 --> 00:34:47,240 that there are radio waves coming from the depths of space. 517 00:34:47,320 --> 00:34:49,960 Some of these waves have the same frequency as your favourite 518 00:34:50,040 --> 00:34:53,160 radio station, but they are weaker and of course there's 519 00:34:53,240 --> 00:34:55,280 nothing to listen to. 520 00:34:56,520 --> 00:34:59,960 In order to "tune in" to the radio Universe, you need some sort 521 00:35:00,040 --> 00:35:02,560 of receiver: a radio telescope. 522 00:35:02,680 --> 00:35:06,960 Now for all but the longest wavelengths, a radio telescope is just a dish. 523 00:35:07,040 --> 00:35:10,080 Much like the main mirror of an optical telescope. 524 00:35:10,200 --> 00:35:14,400 But because radio waves are so much longer than visible lightwaves 525 00:35:14,440 --> 00:35:17,240 the surface of a dish doesn't have to be nearly as smooth 526 00:35:17,360 --> 00:35:19,000 as the surface of a mirror. 527 00:35:19,120 --> 00:35:21,640 And that's the reason why it's so much easier to build a 528 00:35:21,680 --> 00:35:26,800 large radio telescope than it is to build a large optical telescope. 529 00:35:26,840 --> 00:35:30,960 Also, at radio wavelengths, it is much easier to do interferometry. 530 00:35:30,960 --> 00:35:34,080 That is, to increase the level of detail that can be seen 531 00:35:34,120 --> 00:35:37,960 by combining the light from two separate telescopes, as if 532 00:35:38,040 --> 00:35:41,560 they were part of a single, giant dish. 533 00:35:41,600 --> 00:35:44,640 The Very Large Array in New Mexico, for example, consists of 534 00:35:44,680 --> 00:35:49,720 27 separate antennas, each measuring 25 metres across. 535 00:35:49,760 --> 00:35:52,960 Now each antenna can be moved around individually, and in 536 00:35:53,040 --> 00:35:56,400 its most extended configuration, the virtual dish mimicked by the 537 00:35:56,520 --> 00:36:00,800 array measures 36 kilometres across. 538 00:36:00,920 --> 00:36:03,560 So what does the Universe look like in the radio? 539 00:36:03,680 --> 00:36:08,000 Well, for a start our Sun shines very brightly at radio wavelengths. 540 00:36:08,120 --> 00:36:10,720 So does the centre of our Milky Way Galaxy. 541 00:36:10,760 --> 00:36:12,400 But there's more. 542 00:36:12,520 --> 00:36:16,480 Pulsars are very dense stellar corpses that emit radio waves 543 00:36:16,520 --> 00:36:18,640 only into a very narrow beam. 544 00:36:18,680 --> 00:36:21,800 In addition, they rotate at speeds of up to several hundred 545 00:36:21,840 --> 00:36:23,720 revolutions per second. 546 00:36:23,760 --> 00:36:27,800 So in effect, a pulsar looks like a rotating radio lighthouse. 547 00:36:27,920 --> 00:36:31,320 And what we see from them is a very regular and fast 548 00:36:31,360 --> 00:36:34,320 sequence of very short radio pulses. 549 00:36:34,440 --> 00:36:36,640 Hence the name. 550 00:36:36,680 --> 00:36:39,320 The radio source known as Cassiopeia A is in fact 551 00:36:39,440 --> 00:36:43,640 the remnant of a supernova that exploded in the 17th century. 552 00:36:43,680 --> 00:36:48,240 Centaurus A, Cygnus A and Virgo A are all giant galaxies that 553 00:36:48,280 --> 00:36:50,640 pour out huge amounts of radio waves. 554 00:36:50,680 --> 00:36:55,960 Each galaxy is powered by a massive black hole at its centre. 555 00:36:56,040 --> 00:37:00,000 Some of these radio galaxies and quasars are so powerful that 556 00:37:00,120 --> 00:37:05,320 their signals can still be detected from a distance of 10 billion light-years. 557 00:37:05,360 --> 00:37:08,880 And then there's the faint, relatively short-wavelength radio hiss 558 00:37:08,960 --> 00:37:11,320 that fills the entire Universe. 559 00:37:11,360 --> 00:37:14,160 This is known as the cosmic microwave background 560 00:37:14,200 --> 00:37:16,400 and it is the echo of the Big Bang. 561 00:37:16,440 --> 00:37:20,560 The very afterglow of the hot beginnings of the Universe. 562 00:37:22,120 --> 00:37:26,400 Each and every part of the spectrum has its own story to tell. 563 00:37:26,440 --> 00:37:29,960 At millimetre and submillimetre wavelengths, astronomers study 564 00:37:29,960 --> 00:37:33,080 the formation of galaxies in the early Universe, and the origin 565 00:37:33,200 --> 00:37:37,240 of stars and planets in our own Milky Way. 566 00:37:37,280 --> 00:37:41,400 But most of this radiation is blocked by water vapour in our atmosphere. 567 00:37:41,520 --> 00:37:44,400 To observe it, you need to go high and dry. 568 00:37:44,440 --> 00:37:47,320 To Llano de Chajnantor, for example. 569 00:37:47,440 --> 00:37:50,960 At five kilometres above sea level, this surrealistic plateau 570 00:37:50,960 --> 00:37:53,960 in northern Chile is the construction site of ALMA: 571 00:37:54,040 --> 00:37:56,880 the Atacama Large Millimeter Array. 572 00:37:56,920 --> 00:38:01,880 When completed in 2014, ALMA will be the largest astronomical 573 00:38:01,920 --> 00:38:04,320 observatory ever built. 574 00:38:04,840 --> 00:38:09,960 64 antennas each weighing 100 tonnes, will work in unison. 575 00:38:09,960 --> 00:38:13,880 Giant trucks will spread them out over an area as large as London to 576 00:38:13,960 --> 00:38:16,800 increase the detail of the image, or bring them close together to 577 00:38:16,880 --> 00:38:19,000 provide a wider view. 578 00:38:19,120 --> 00:38:23,240 Each move will be made with millimetre precision. 579 00:38:24,680 --> 00:38:28,160 Many objects in the Universe also glow in the infrared. 580 00:38:28,280 --> 00:38:31,960 Discovered by William Herschel, infrared radiation is often also called 581 00:38:32,040 --> 00:38:36,720 "heat radiation" because it is emitted by all relatively warm objects 582 00:38:36,760 --> 00:38:39,080 including humans. 583 00:38:41,840 --> 00:38:45,240 You may be more familiar with infrared radiation than you think. 584 00:38:45,360 --> 00:38:48,240 Because on Earth, this kind of radiation is used by 585 00:38:48,360 --> 00:38:51,160 night vision goggles and cameras. 586 00:38:51,280 --> 00:38:55,160 But to detect the faint infrared glow from distant objects, astronomers 587 00:38:55,280 --> 00:38:58,960 need very sensitive detectors, cooled down to just a few degrees 588 00:38:59,040 --> 00:39:04,000 above absolute zero, in order to suppress their own heat radiation. 589 00:39:06,920 --> 00:39:11,720 Today, most big optical telescopes are also equipped with infrared cameras. 590 00:39:11,760 --> 00:39:15,320 They allow you to see right through a cosmic dust cloud, revealing the 591 00:39:15,440 --> 00:39:20,240 newborn stars inside, something that just cannot be seen in the optical. 592 00:39:20,280 --> 00:39:25,080 For example, take this optical image of the famous stellar nursery in Orion. 593 00:39:25,200 --> 00:39:27,400 But look how different it is when seen through the eyes 594 00:39:27,520 --> 00:39:30,080 of an infrared camera! 595 00:39:30,200 --> 00:39:33,320 Being able to see in the infrared is also very helpful when studying 596 00:39:33,360 --> 00:39:35,960 the most distant galaxies. 597 00:39:35,960 --> 00:39:41,000 The newborn stars in a young galaxy shine very brightly in the ultraviolet. 598 00:39:41,120 --> 00:39:45,000 But then this ultraviolet light has to travel for billions of years across 599 00:39:45,120 --> 00:39:46,640 the expanding Universe. 600 00:39:46,760 --> 00:39:50,560 The expansion stretches the lightwaves so that when they are received 601 00:39:50,600 --> 00:39:55,240 by us, they've been shifted all the way into the near-infrared. 602 00:39:56,600 --> 00:40:00,240 This stylish instrument is the MAGIC telescope on La Palma. 603 00:40:00,360 --> 00:40:02,960 It searches the sky for cosmic gamma rays 604 00:40:02,960 --> 00:40:06,800 the most energetic form of radiation in Nature. 605 00:40:08,360 --> 00:40:10,960 Lucky for us, the lethal gamma rays are blocked by the 606 00:40:10,960 --> 00:40:12,320 Earth's atmosphere. 607 00:40:12,360 --> 00:40:16,000 But they do leave behind footprints for astronomers to study. 608 00:40:16,120 --> 00:40:19,000 After hitting the atmosphere, they produce cascades of 609 00:40:19,120 --> 00:40:20,640 energetic particles. 610 00:40:20,760 --> 00:40:25,320 These, in turn, cause a faint glow that MAGIC can see. 611 00:40:26,920 --> 00:40:30,640 And here's the Pierre Auger Observatory in Argentina. 612 00:40:30,680 --> 00:40:33,080 It doesn't even look like a telescope. 613 00:40:33,120 --> 00:40:38,960 Pierre Auger consists of 1600 detectors, spread over 3000 614 00:40:38,960 --> 00:40:40,240 square kilometres. 615 00:40:40,360 --> 00:40:44,560 They catch the particle fallout of cosmic rays from distant supernovas 616 00:40:44,600 --> 00:40:46,480 and black holes. 617 00:40:47,680 --> 00:40:52,400 And what about neutrino detectors, built in deep mines or beneath the 618 00:40:52,520 --> 00:40:55,720 surface of the ocean, or in the Antarctic ice. 619 00:40:55,840 --> 00:40:57,880 Could you call those telescopes? 620 00:40:57,960 --> 00:40:59,400 Well, why not? 621 00:40:59,520 --> 00:41:03,800 After all, they do observe the Universe, even if they don't capture data from 622 00:41:03,840 --> 00:41:06,080 the electromagnetic spectrum. 623 00:41:06,120 --> 00:41:09,880 Neutrinos are elusive particles that are produced in the Sun 624 00:41:09,960 --> 00:41:12,240 and supernova explosions. 625 00:41:12,360 --> 00:41:15,800 They were even produced in the Big Bang itself. 626 00:41:15,920 --> 00:41:20,640 Unlike other elementary particles, neutrinos can pass through regular 627 00:41:20,680 --> 00:41:25,640 matter, travel near the speed of light and have no electric charge. 628 00:41:25,760 --> 00:41:30,240 Although these particles may be difficult to study, they are plentiful. 629 00:41:30,280 --> 00:41:34,160 Each second more than 50 trillion electron neutrinos from the Sun 630 00:41:34,200 --> 00:41:36,560 pass through you. 631 00:41:36,680 --> 00:41:40,800 Finally, astronomers and physicists have joined forces to build gravitational 632 00:41:40,920 --> 00:41:42,640 wave detectors. 633 00:41:42,680 --> 00:41:46,640 These "telescopes" do not observe radiation or catch particles. 634 00:41:46,680 --> 00:41:51,240 Instead, they measure tiny ripples in the very structure of space-time - 635 00:41:51,280 --> 00:41:56,960 a concept predicted by Albert Einstein's theory of relativity. 636 00:41:57,040 --> 00:42:01,160 With a stunning variety of instruments, astronomers have opened up the full 637 00:42:01,200 --> 00:42:06,960 spectrum of electromagnetic radiation, and have even ventured beyond. 638 00:42:07,040 --> 00:42:11,240 But some observations simply can't be done from the ground. 639 00:42:11,280 --> 00:42:12,800 The answer? 640 00:42:12,920 --> 00:42:15,240 Space telescopes. 641 00:42:22,000 --> 00:42:26,560 6. Beyond Earth 642 00:42:28,560 --> 00:42:30,400 The Hubble Space Telescope. 643 00:42:30,480 --> 00:42:33,360 It is by far the most famous telescope in history. 644 00:42:33,440 --> 00:42:34,800 And for good reason. 645 00:42:34,880 --> 00:42:38,560 Hubble has revolutionised so many fields in astronomy. 646 00:42:38,640 --> 00:42:42,040 By modern standards, Hubble's mirror is actually quite small. 647 00:42:42,120 --> 00:42:45,040 It only measures about 2.4 metres across. 648 00:42:45,120 --> 00:42:48,640 But its location is literally out of this world. 649 00:42:48,720 --> 00:42:52,360 High above the blurring effects of the atmosphere, it has an exceptionally 650 00:42:52,440 --> 00:42:54,600 sharp view of the Universe. 651 00:42:54,680 --> 00:42:59,360 And what's more, Hubble can see ultraviolet and near-infrared light. 652 00:42:59,440 --> 00:43:02,480 This light just cannot be seen by ground-based telescopes because 653 00:43:02,560 --> 00:43:05,880 it is blocked by the atmosphere. 654 00:43:05,960 --> 00:43:09,880 Cameras and spectrographs, some as big as a telephone booth 655 00:43:09,960 --> 00:43:14,600 dissect and register the light from distant cosmic shores. 656 00:43:14,680 --> 00:43:19,320 Just like any ground-based telescope, Hubble is upgraded from time to time. 657 00:43:19,400 --> 00:43:22,760 Spacewalking astronauts carry out servicing missions. 658 00:43:22,840 --> 00:43:24,440 Broken parts get refurbished. 659 00:43:24,520 --> 00:43:27,000 And older instruments get replaced with newer and 660 00:43:27,080 --> 00:43:29,800 state-of-the-art technology. 661 00:43:29,880 --> 00:43:33,280 Hubble has become the powerhouse of observational astronomy. 662 00:43:33,360 --> 00:43:37,240 And it has transformed our understanding of the cosmos. 663 00:43:39,840 --> 00:43:44,800 With its keen eyesight, Hubble observed seasonal changes on Mars 664 00:43:45,920 --> 00:43:48,800 a cometary impact on Jupiter 665 00:43:50,520 --> 00:43:53,880 an edge-on view of Saturn's rings 666 00:43:56,920 --> 00:44:00,400 and even the surface of tiny Pluto. 667 00:44:00,480 --> 00:44:06,320 It revealed the life cycle of stars, from their very birth and baby days 668 00:44:06,600 --> 00:44:12,560 in a nursery of dust-laden clouds of gas, all the way to their final farewell: 669 00:44:12,640 --> 00:44:17,800 as delicate nebulae, slowly blown into space by dying stars 670 00:44:17,920 --> 00:44:24,960 or as titanic supernova explosions that almost outshine their home galaxy. 671 00:44:25,040 --> 00:44:28,960 Deep in the Orion Nebula, Hubble even saw the breeding ground of new 672 00:44:29,040 --> 00:44:34,080 solar systems: dusty disks around newborn stars that may soon 673 00:44:34,120 --> 00:44:36,080 condense into planets. 674 00:44:36,200 --> 00:44:40,320 The space telescope studied thousands of individual stars in giant globular 675 00:44:40,440 --> 00:44:45,960 clusters, the oldest stellar families in the Universe. 676 00:44:46,040 --> 00:44:48,320 And galaxies, of course. 677 00:44:48,440 --> 00:44:51,960 Never before had astronomers seen so much detail. 678 00:44:51,960 --> 00:44:58,800 Majestic spirals, absorbing dust lanes, violent collisions. 679 00:45:01,040 --> 00:45:05,480 Extremely long exposures of blank regions of sky even revealed 680 00:45:05,520 --> 00:45:10,080 thousands of faint galaxies billions of light-years away. 681 00:45:10,120 --> 00:45:13,960 Photons that were emitted when the Universe was still young. 682 00:45:14,040 --> 00:45:18,400 A window into the distant past, shedding new light on the 683 00:45:18,440 --> 00:45:21,560 ever-evolving cosmos. 684 00:45:22,200 --> 00:45:24,880 Hubble is not the only telescope in space. 685 00:45:24,920 --> 00:45:29,800 This is NASA's Spitzer Space Telescope, launched in August 2003. 686 00:45:29,920 --> 00:45:33,720 In a way, it is Hubble's equivalent for the infrared. 687 00:45:33,760 --> 00:45:37,960 Spitzer has a mirror that is only 85 centimetres across. 688 00:45:37,960 --> 00:45:41,080 But the telescope is hiding behind a heat shield that protects 689 00:45:41,200 --> 00:45:42,480 it from the Sun. 690 00:45:42,520 --> 00:45:47,160 And its detectors are tucked away in a dewar filled with liquid helium. 691 00:45:47,200 --> 00:45:50,080 Here the detectors are cooled down to just a few degrees 692 00:45:50,200 --> 00:45:51,800 above absolute zero. 693 00:45:51,920 --> 00:45:55,560 Making them very very sensitive. 694 00:45:55,680 --> 00:45:58,720 Spitzer has revealed a dusty Universe. 695 00:45:58,760 --> 00:46:02,560 Dark, opaque clouds of dust glow in the infrared when heated 696 00:46:02,680 --> 00:46:04,560 from within. 697 00:46:04,600 --> 00:46:08,720 Shock waves from galaxy collisions sweep up dust in telltale rings 698 00:46:08,760 --> 00:46:13,480 and tidal features, new sites for ubiquitous star formation. 699 00:46:15,520 --> 00:46:19,080 Dust is also produced in the aftermath of a star's death. 700 00:46:19,200 --> 00:46:23,080 Spitzer found that planetary nebulae and supernova remnants are laden 701 00:46:23,200 --> 00:46:28,320 with dust particles, the prerequisite building blocks of future planets. 702 00:46:28,440 --> 00:46:32,080 At other infrared wavelengths, Spitzer can also see right through a dust 703 00:46:32,200 --> 00:46:37,720 cloud, revealing the stars inside, hidden in their dark cores. 704 00:46:37,840 --> 00:46:40,960 Finally, the space telescope's spectrographs have studied 705 00:46:40,960 --> 00:46:44,880 the atmospheres of extrasolar planets - gas giants like Jupiter 706 00:46:44,920 --> 00:46:48,880 that race around their parent stars in just a few days. 707 00:46:50,680 --> 00:46:52,880 So what about X-rays and gamma rays? 708 00:46:52,920 --> 00:46:55,560 Well, they are completely blocked by the Earth's atmosphere. 709 00:46:55,680 --> 00:46:59,160 And so without space telescopes, astronomers would be totally blind 710 00:46:59,200 --> 00:47:02,080 to these energetic forms of radiation. 711 00:47:03,680 --> 00:47:07,080 X-ray and gamma ray space telescopes reveal the hot 712 00:47:07,120 --> 00:47:11,800 energetic and violent Universe of galaxy clusters, black holes 713 00:47:11,840 --> 00:47:16,080 supernova explosions, and galaxy collisions. 714 00:47:18,760 --> 00:47:20,840 They are very hard to build, though. 715 00:47:20,920 --> 00:47:24,440 Energetic radiation passes right through a conventional mirror. 716 00:47:24,520 --> 00:47:29,680 X-rays can only be focused with nested mirror shells made of pure gold. 717 00:47:29,760 --> 00:47:33,120 And gamma rays are studied with sophisticated pinhole cameras 718 00:47:33,200 --> 00:47:36,560 or stacked scintillators that give off brief flashes of normal light 719 00:47:36,640 --> 00:47:39,680 when struck by a gamma ray photon. 720 00:47:40,960 --> 00:47:45,120 In the 1990s, NASA operated the Compton Gamma Ray Observatory. 721 00:47:45,200 --> 00:47:48,280 At the time, it was the largest and most massive scientific 722 00:47:48,360 --> 00:47:49,880 satellite ever launched. 723 00:47:49,960 --> 00:47:53,120 A fully fledged physics lab in space. 724 00:47:53,200 --> 00:47:56,480 In 2008, Compton was succeeded by GLAST: 725 00:47:56,560 --> 00:48:00,520 the Gamma Ray Large Area Space Telescope. 726 00:48:00,600 --> 00:48:04,120 It will study everything in the high-energy Universe from dark 727 00:48:04,200 --> 00:48:06,520 matter to pulsars. 728 00:48:08,440 --> 00:48:12,360 Meanwhile, astronomers have two X-ray telescopes in space. 729 00:48:12,440 --> 00:48:17,400 NASA's Chandra X-ray Observatory and ESA's XMM-Newton Observatory 730 00:48:17,480 --> 00:48:21,480 are both studying the hottest places in the Universe. 731 00:48:23,960 --> 00:48:27,680 This is what the sky looks like with X-ray vision. 732 00:48:27,760 --> 00:48:32,160 Extended features are clouds of gas, heated to millions of degrees by 733 00:48:32,240 --> 00:48:35,680 shock waves in supernova remnants. 734 00:48:35,760 --> 00:48:39,960 The bright point sources are X-ray binaries: neutron stars or 735 00:48:39,960 --> 00:48:43,640 black holes that suck in matter from a companion star. 736 00:48:43,720 --> 00:48:47,280 This hot, infalling gas emits X-rays. 737 00:48:47,360 --> 00:48:51,560 Likewise, X-ray telescopes reveal supermassive black holes in 738 00:48:51,640 --> 00:48:53,760 the cores of distant galaxies. 739 00:48:53,840 --> 00:48:57,800 Matter that spirals inward gets hot enough to glow in X-rays 740 00:48:57,880 --> 00:49:02,160 just before it plunges into the black hole and out of sight. 741 00:49:02,240 --> 00:49:06,840 Hot but tenuous gas also fills the space between individual galaxies 742 00:49:06,920 --> 00:49:08,320 in a cluster. 743 00:49:08,400 --> 00:49:12,240 Sometimes, this intracluster gas is shocked and heated even more 744 00:49:12,320 --> 00:49:16,480 by colliding and merging galaxy clusters. 745 00:49:16,560 --> 00:49:20,760 Even more exciting are gamma ray bursts, the most energetic 746 00:49:20,840 --> 00:49:22,600 events in the Universe. 747 00:49:22,680 --> 00:49:26,920 These are catastrophic terminal explosions of very massive, rapidly 748 00:49:26,960 --> 00:49:28,760 spinning stars. 749 00:49:28,840 --> 00:49:32,760 In less than a second, they release more energy than the Sun does in 750 00:49:32,840 --> 00:49:35,760 10 billion years. 751 00:49:38,200 --> 00:49:42,160 Hubble, Spitzer, Chandra, XMM-Newton and GLAST 752 00:49:42,240 --> 00:49:44,600 are all versatile giants. 753 00:49:44,680 --> 00:49:47,640 But some space telescopes are much smaller and have much more 754 00:49:47,720 --> 00:49:49,240 focused missions. 755 00:49:49,320 --> 00:49:51,280 Take COROT, for example. 756 00:49:51,360 --> 00:49:54,880 This French satellite is devoted to stellar seismology and the study 757 00:49:54,960 --> 00:49:56,880 of extrasolar planets. 758 00:49:56,960 --> 00:50:01,240 Or NASA's Swift satellite, a combined X-ray and gamma ray observatory 759 00:50:01,320 --> 00:50:05,720 designed to unravel the mysteries of gamma ray bursts. 760 00:50:05,800 --> 00:50:10,160 And then there's WMAP, the Wilkinson Microwave Anisotropy Probe. 761 00:50:10,240 --> 00:50:13,840 In just over two years in space, it had already mapped the cosmic 762 00:50:13,920 --> 00:50:17,280 background radiation to unprecedented detail. 763 00:50:17,360 --> 00:50:21,200 WMAP gave cosmologists the best view yet of one of the earliest 764 00:50:21,280 --> 00:50:26,680 phases of the Universe, more than 13 billion years ago. 765 00:50:26,760 --> 00:50:29,640 Opening up the space frontier has been one of the most exciting 766 00:50:29,720 --> 00:50:32,240 developments in the history of the telescope. 767 00:50:32,320 --> 00:50:34,760 So what's next? 768 00:50:37,400 --> 00:50:40,280 7. What's next? 769 00:50:42,286 --> 00:50:45,080 In Arizona, the first mirror has been cast for the 770 00:50:45,160 --> 00:50:47,000 Giant Magellan Telescope. 771 00:50:47,080 --> 00:50:50,280 This huge instrument will be built at the Las Campanas 772 00:50:50,360 --> 00:50:51,960 Observatory in Chile. 773 00:50:52,040 --> 00:50:55,640 Its seven mirrors, each well over eight metres across 774 00:50:55,720 --> 00:50:58,800 will be arranged like the petals of a flower. 775 00:50:58,880 --> 00:51:01,800 And together they will capture more than four times the 776 00:51:01,880 --> 00:51:05,399 amount of light any current telescope can catch. 777 00:51:05,480 --> 00:51:09,840 The Californian Thirty Meter Telescope, planned for 2015 778 00:51:09,920 --> 00:51:12,680 is more like a giant version of Keck. 779 00:51:12,760 --> 00:51:15,960 Hundreds of individual segments make up one enormous mirror 780 00:51:16,040 --> 00:51:20,120 as tall as a six-storey apartment. 781 00:51:20,200 --> 00:51:24,920 In Europe, plans are ready for a European Extremely Large Telescope. 782 00:51:25,399 --> 00:51:28,760 At 42 metres in diameter 783 00:51:28,840 --> 00:51:32,240 its mirror will be as large as an Olympic swimming pool - twice the surface area of the 784 00:51:32,320 --> 00:51:34,440 Thirty Meter Telescope. 785 00:51:34,520 --> 00:51:39,000 These future monsters, optimised for infrared observations, will 786 00:51:39,080 --> 00:51:43,760 all be outfitted with sensitive instruments and adaptive optics. 787 00:51:43,840 --> 00:51:46,440 They should reveal the very first generation of galaxies 788 00:51:46,520 --> 00:51:49,720 and stars in the history of the Universe. 789 00:51:49,800 --> 00:51:52,720 Moreover, they may provide us with the first true picture 790 00:51:52,800 --> 00:51:55,760 of a planet in another solar system. 791 00:51:55,840 --> 00:51:59,600 For radio astronomers, 42 metres is peanuts. 792 00:51:59,680 --> 00:52:02,320 They hook up many smaller instruments to synthesise 793 00:52:02,399 --> 00:52:04,680 a much larger receiver. 794 00:52:04,760 --> 00:52:08,399 In the Netherlands, the Low Frequency Array, or LOFAR 795 00:52:08,480 --> 00:52:10,120 is under construction. 796 00:52:10,200 --> 00:52:15,440 Fibre optics will connect 30 000 antennas to a central supercomputer. 797 00:52:15,520 --> 00:52:19,040 The novel design has no moving parts, but it can observe in 798 00:52:19,120 --> 00:52:22,440 eight different directions simultaneously. 799 00:52:22,520 --> 00:52:25,720 LOFAR technology will probably find its way into the Square 800 00:52:25,800 --> 00:52:28,200 Kilometre Array, which is now topping the wish-list 801 00:52:28,280 --> 00:52:30,160 of radio astronomers. 802 00:52:30,240 --> 00:52:34,240 The international array will be built in Australia or South Africa. 803 00:52:34,320 --> 00:52:38,160 Large dish antennas and small receivers will team up to provide 804 00:52:38,240 --> 00:52:42,520 incredibly detailed views of the radio sky. 805 00:52:42,600 --> 00:52:46,320 And with a total collecting area of one square kilometre, the 806 00:52:46,399 --> 00:52:50,040 new array will be by far the most sensitive radio instrument 807 00:52:50,120 --> 00:52:52,520 ever constructed. 808 00:52:52,600 --> 00:52:57,640 Evolving galaxies, powerful quasars, blinking pulsars 809 00:52:57,760 --> 00:53:01,399 no single source of radio waves will be safe from the spying eyes 810 00:53:01,480 --> 00:53:04,360 of the Square Kilometre Array. 811 00:53:04,399 --> 00:53:07,880 The instrument will even look for possible radio signals from 812 00:53:07,960 --> 00:53:11,440 extraterrestrial civilisations. 813 00:53:11,520 --> 00:53:14,760 And what about space? 814 00:53:14,840 --> 00:53:18,640 Well, after its fifth and final servicing mission, the Hubble Space 815 00:53:18,720 --> 00:53:24,080 Telescope will be on active duty until 2013 or so. 816 00:53:24,160 --> 00:53:28,320 Around that time, its successor will be launched. 817 00:53:30,360 --> 00:53:34,320 Meet the James Webb Space Telescope, a space infrared 818 00:53:34,399 --> 00:53:40,080 observatory named after a former NASA administrator. 819 00:53:40,160 --> 00:53:44,440 Once in space, its 6.5 metre segmented mirror unfolds 820 00:53:44,520 --> 00:53:48,080 like a blooming flower - one seven times as sensitive 821 00:53:48,160 --> 00:53:50,960 as Hubble's. 822 00:53:51,040 --> 00:53:54,120 A large sunshade keeps the optics and the low-temperature 823 00:53:54,200 --> 00:53:57,560 instruments in permanent shadow, allowing them to operate near 824 00:53:57,640 --> 00:54:02,600 a whopping minus 233 degrees Celsius. 825 00:54:03,800 --> 00:54:07,480 The James Webb Space Telescope won't orbit the Earth. 826 00:54:07,560 --> 00:54:11,240 Instead, it will be parked 1.5 million kilometres from our 827 00:54:11,320 --> 00:54:15,480 planet, in a wide orbit around the Sun. 828 00:54:15,560 --> 00:54:18,680 Half a century ago, the Hale telescope on Palomar Mountain 829 00:54:18,760 --> 00:54:20,560 was the largest in history. 830 00:54:20,600 --> 00:54:24,720 Now, an even bigger one will be flying into the depths of space. 831 00:54:24,760 --> 00:54:29,040 We can only speculate about the exciting discoveries it will make. 832 00:54:29,120 --> 00:54:31,280 Stay tuned! 833 00:54:31,760 --> 00:54:34,480 Meanwhile, creative engineers come up with revolutionary 834 00:54:34,560 --> 00:54:37,320 designs for new telescopes all the time. 835 00:54:37,399 --> 00:54:41,640 In Canada, scientists have built a so-called "liquid mirror telescope". 836 00:54:41,720 --> 00:54:44,800 In this kind of telescope the starlight is reflected not by 837 00:54:44,880 --> 00:54:48,960 a solid mirror but rather by the curved surface of a rotating 838 00:54:49,040 --> 00:54:52,200 reservoir of liquid mercury. 839 00:54:52,280 --> 00:54:55,960 Because of their design, mercury telescopes can only look straight up, 840 00:54:56,040 --> 00:54:58,720 but their advantage is that they're relatively cheap 841 00:54:58,800 --> 00:55:00,960 and easy to build. 842 00:55:01,040 --> 00:55:04,040 Radio astronomers want to put a LOFAR-like array of small 843 00:55:04,120 --> 00:55:06,960 antennas onto the surface of the Moon, as far away as 844 00:55:07,040 --> 00:55:10,480 possible from terrestrial sources of interference. 845 00:55:10,560 --> 00:55:13,120 Who knows, one day there might even be a big optical 846 00:55:13,200 --> 00:55:15,960 telescope on the far side of the Moon. 847 00:55:16,040 --> 00:55:18,960 And using space telescopes and occulting disks, X-ray 848 00:55:19,040 --> 00:55:21,560 astronomers hope to improve their eyesight tremendously 849 00:55:21,640 --> 00:55:22,640 in the future. 850 00:55:22,720 --> 00:55:25,320 They may even succeed in imaging the very edge 851 00:55:25,399 --> 00:55:27,360 of a black hole. 852 00:55:29,160 --> 00:55:32,160 One day, the telescope may answer one of the most profound 853 00:55:32,240 --> 00:55:38,440 questions puzzling humanity: are we alone in the Universe? 854 00:55:42,080 --> 00:55:45,400 We know that there are other solar systems out there. 855 00:55:45,520 --> 00:55:47,880 We suspect there are even planets like Earth, with 856 00:55:48,000 --> 00:55:49,800 liquid water. 857 00:55:49,920 --> 00:55:50,800 But 858 00:55:50,920 --> 00:55:53,040 is there life? 859 00:55:53,920 --> 00:55:57,720 Locating such extrasolar planets proves difficult. 860 00:55:57,840 --> 00:56:00,280 They are often hidden from astronomers by the intense 861 00:56:00,320 --> 00:56:03,560 light radiated by their mother stars. 862 00:56:04,520 --> 00:56:07,640 Interferometers launched into the darkness of space may 863 00:56:07,760 --> 00:56:10,360 provide a novel answer. 864 00:56:10,399 --> 00:56:13,120 Right now NASA is considering a project called the 865 00:56:13,160 --> 00:56:15,720 Terrestrial Planet Finder. 866 00:56:15,840 --> 00:56:20,280 And in Europe, scientists are designing the Darwin Array. 867 00:56:20,399 --> 00:56:23,960 Six space telescopes orbit the Sun in formation. 868 00:56:24,080 --> 00:56:28,120 Lasers control their mutual distances to the nearest nanometre. 869 00:56:28,160 --> 00:56:31,800 Together they have incredible resolving power, cancelling out 870 00:56:31,840 --> 00:56:35,640 the light from overbearing stars so scientists can actually see 871 00:56:35,760 --> 00:56:39,400 Earth-like planets around other stars. 872 00:56:40,240 --> 00:56:44,480 Next astronomers must study the light reflected by the planet. 873 00:56:44,600 --> 00:56:49,560 It carries the spectroscopic fingerprint of the planet's atmosphere. 874 00:56:49,600 --> 00:56:52,880 Who knows, in 15 years time we may detect the signatures 875 00:56:52,920 --> 00:56:55,200 of oxygen, methane and ozone. 876 00:56:55,320 --> 00:56:58,400 The signposts of life. 877 00:57:00,600 --> 00:57:03,120 The Universe is full of surprises. 878 00:57:03,240 --> 00:57:05,560 The sky never ceases to impress. 879 00:57:05,680 --> 00:57:08,560 No wonder that hundreds of thousands of amateur astronomers 880 00:57:08,600 --> 00:57:11,120 across the globe go out every clear night to marvel 881 00:57:11,240 --> 00:57:12,800 at the cosmos. 882 00:57:12,840 --> 00:57:15,120 Their telescopes are much better than the instruments 883 00:57:15,240 --> 00:57:16,560 used by Galileo. 884 00:57:16,600 --> 00:57:20,200 Their digital images even surpass the photographic images taken 885 00:57:20,240 --> 00:57:23,360 by professionals just a few decades ago. 886 00:57:23,480 --> 00:57:26,800 Astronomers' quest for cosmic understanding, their telescopic 887 00:57:26,840 --> 00:57:30,360 exploration of the Universe, is only 400 years old. 888 00:57:30,399 --> 00:57:34,640 There's still a lot of uncharted territory out there. 889 00:57:35,160 --> 00:57:38,480 We've come a long way since Galileo began charting the heavens 890 00:57:38,600 --> 00:57:41,800 with his telescope four centuries ago. 891 00:57:41,840 --> 00:57:45,040 Today we still observe the Universe with telescopes 892 00:57:45,080 --> 00:57:50,400 not only from Earth but in the limitless regions of space. 893 00:57:50,520 --> 00:57:54,120 The seed of humanity lies in our seemingly endless supply 894 00:57:54,240 --> 00:57:57,280 of ingenuity and curiosity. 895 00:57:57,399 --> 00:57:59,960 We have just begun answering some of the greatest 896 00:58:00,000 --> 00:58:02,040 questions conceived. 897 00:58:02,080 --> 00:58:04,720 We have charted over 300 planets around other stars in 898 00:58:04,760 --> 00:58:08,800 our own Milky Way and located organic molecules on planets 899 00:58:08,840 --> 00:58:12,360 around far flung stars. 900 00:58:12,399 --> 00:58:17,040 These incredible discoveries may seem like the zenith of human exploration, 901 00:58:17,120 --> 00:58:21,120 but the best is undoubtedly yet to come. 902 00:58:21,240 --> 00:58:24,040 You too can join the discoverers. 903 00:58:24,080 --> 00:58:28,800 Look up and wonder.