1 00:00:02,350 --> 00:00:03,930 This is the ESOcast! 2 00:00:04,580 --> 00:00:07,800 Cutting-edge science and life behind the scenes of ESO, 3 00:00:07,800 --> 00:00:10,360 the European Southern Observatory, 4 00:00:10,360 --> 00:00:17,650 exploring the ultimate frontier with our host Dr J, a.k.a. Dr Joe Liske. 5 00:00:20,360 --> 00:00:23,230 Hello and welcome to this special episode of the ESOcast. 6 00:00:23,230 --> 00:00:27,790 Leading up to ESO’s 50th anniversary in October 2012 7 00:00:27,790 --> 00:00:30,330 we will showcase eight special features 8 00:00:30,330 --> 00:00:35,490 portraying ESO’s first 50 years of exploring the southern sky. 9 00:00:40,060 --> 00:00:44,620 Seeing Sharp 10 00:00:46,000 --> 00:00:49,570 Bigger is better - at least when it comes to telescope mirrors. 11 00:00:49,570 --> 00:00:54,650 But larger mirrors have to be thick, so that they don't deform under their own weight. 12 00:00:55,320 --> 00:00:59,590 And really large mirrors deform anyway, no matter how thick and heavy they are. 13 00:01:00,660 --> 00:01:07,340 The solution? Thin, lightweight mirrors - and a magic trick called active optics. 14 00:01:08,310 --> 00:01:11,330 ESO pioneered this technology in the late 1980s, 15 00:01:11,330 --> 00:01:14,020 with the New Technology Telescope. 16 00:01:15,430 --> 00:01:17,690 And this is the state of the art. 17 00:01:17,690 --> 00:01:23,740 The mirrors of the Very Large Telescope – the VLT – are 8.2 metres across... 18 00:01:23,740 --> 00:01:26,480 ...but only 20 centimetres thick. 19 00:01:27,310 --> 00:01:28,310 And here’s the magic: 20 00:01:28,970 --> 00:01:31,310 a computer-controlled support system ensures 21 00:01:31,310 --> 00:01:37,060 that the mirror keeps its desired shape at all times to nanometre precision. 22 00:01:53,620 --> 00:01:56,930 The VLT is ESO’s flagship facility. 23 00:01:56,930 --> 00:02:03,840 Four identical telescopes, joining forces on top of Cerro Paranal, in the north of Chile. 24 00:02:03,840 --> 00:02:06,020 Built in the late 1990s, 25 00:02:06,020 --> 00:02:10,720 they provided astronomers with the best available technologies. 26 00:02:15,560 --> 00:02:20,910 In the middle of the Atacama Desert, ESO created an astronomer’s paradise. 27 00:02:36,220 --> 00:02:38,540 Scientists stay in La Residencia, 28 00:02:38,540 --> 00:02:42,220 a guest house partly buried under the dirt and rubble 29 00:02:42,220 --> 00:02:44,370 of one of the driest places on the planet. 30 00:02:44,850 --> 00:02:50,920 But inside are lush palm trees, a swimming pool, and... delicious Chilean sweets. 31 00:02:54,240 --> 00:02:54,510 Of course, 32 00:02:54,510 --> 00:02:59,000 the unique selling point of the Very Large Telescope is not its swimming pool, 33 00:02:59,000 --> 00:03:02,770 but its unequalled view of the Universe. 34 00:03:07,580 --> 00:03:11,690 Without thin mirrors and active optics, the VLT would not be possible. 35 00:03:12,180 --> 00:03:13,260 But there’s more. 36 00:03:13,260 --> 00:03:18,530 Stars appear blurry, even when observed with the best and largest telescopes. 37 00:03:18,530 --> 00:03:22,570 The reason? The Earth’s atmosphere distorts the images. 38 00:03:27,280 --> 00:03:31,390 Enter the second magic trick: adaptive optics. 39 00:03:33,110 --> 00:03:39,390 On Paranal, laser beams shoot out into the night sky to create artificial stars. 40 00:03:39,390 --> 00:03:43,000 Sensors use these stars to measure the atmospheric distortions. 41 00:03:43,000 --> 00:03:46,130 And hundreds of times per second, 42 00:03:46,130 --> 00:03:50,400 the image is corrected by computer-controlled deformable mirrors. 43 00:03:51,910 --> 00:03:57,670 And the end effect? As if the turbulent atmosphere were completely removed. 44 00:03:58,070 --> 00:03:59,430 Just look at the difference! 45 00:04:06,450 --> 00:04:09,860 The Milky Way is a giant spiral galaxy. 46 00:04:09,860 --> 00:04:14,170 And at its core – 27 000 light-years away – 47 00:04:14,170 --> 00:04:19,610 lies a mystery that ESO’s Very Large Telescope helped to unravel. 48 00:04:21,839 --> 00:04:25,490 Massive dust clouds block our view of the Milky Way’s core. 49 00:04:25,490 --> 00:04:29,540 But sensitive infrared cameras can peer through the dust 50 00:04:29,540 --> 00:04:32,270 and uncover what lies behind. 51 00:04:38,200 --> 00:04:43,540 Assisted by adaptive optics they reveal dozens of red giant stars. 52 00:04:43,850 --> 00:04:47,480 And over the years, these stars are seen to move! 53 00:04:47,480 --> 00:04:52,250 They orbit an invisible object at the very centre of the Milky Way. 54 00:04:54,020 --> 00:04:59,650 Judging from the stellar motions, the invisible object must be extremely massive. 55 00:05:00,420 --> 00:05:06,980 A monstrous black hole, weighing in at 4.3 million times the mass of our Sun. 56 00:05:07,710 --> 00:05:11,740 Astronomers have even observed energetic flares from gas clouds 57 00:05:11,740 --> 00:05:13,490 falling into the black hole. 58 00:05:13,490 --> 00:05:18,440 All exposed by the sheer power of adaptive optics. 59 00:05:20,320 --> 00:05:25,030 So thin mirrors and active optics make it possible to build giant telescopes. 60 00:05:25,030 --> 00:05:28,030 And the adaptive optics take care of the atmospheric turbulence, 61 00:05:28,030 --> 00:05:31,410 providing us with extremely sharp images. 62 00:05:32,190 --> 00:05:34,240 But we're not done yet with our magic tricks. 63 00:05:34,240 --> 00:05:38,420 There's a third one. And it's called interferometry. 64 00:05:41,060 --> 00:05:44,010 The VLT consists of four telescopes. 65 00:05:44,010 --> 00:05:50,150 Together, they can act as a virtual telescope measuring 130 metres across. 66 00:05:52,710 --> 00:05:58,330 Light collected by the individual telescopes is channelled through evacuated tunnels 67 00:05:58,330 --> 00:06:01,440 and brought together in an underground laboratory. 68 00:06:03,200 --> 00:06:09,260 Here, the light waves are combined using laser metrology and intricate delay lines. 69 00:06:14,140 --> 00:06:19,050 The net result is the light-gathering power of four 8.2-metre mirrors, 70 00:06:19,050 --> 00:06:25,350 and the eagle-eyed vision of an imaginary telescope as large as fifty tennis courts. 71 00:06:28,220 --> 00:06:31,990 Four auxiliary telescopes give the network more flexibility. 72 00:06:31,990 --> 00:06:35,320 They may appear tiny next to the four giants. 73 00:06:35,320 --> 00:06:39,970 Yet, they sport mirrors 1.8 metres across. 74 00:06:39,970 --> 00:06:45,560 That’s bigger than the largest telescope in the world just a hundred years ago! 75 00:06:47,280 --> 00:06:50,050 Optical interferometry is something of a miracle. 76 00:06:50,050 --> 00:06:54,250 Starlight magic, wielded in the desert. 77 00:06:54,250 --> 00:06:58,250 And the results are impressive. 78 00:07:00,360 --> 00:07:04,830 The Very Large Telescope Interferometer reveals fifty times more detail 79 00:07:04,830 --> 00:07:06,900 than the Hubble Telescope. 80 00:07:09,970 --> 00:07:14,200 For instance, it gave us a close-up of a vampire double star. 81 00:07:16,160 --> 00:07:19,030 One star is stealing material from its companion. 82 00:07:23,670 --> 00:07:28,450 Irregular puffs of stardust have been detected around Betelgeuse — 83 00:07:28,450 --> 00:07:32,410 a stellar giant about to go supernova. 84 00:07:34,750 --> 00:07:40,000 And in dusty discs surrounding newborn stars, astronomers have found ... 85 00:07:40,990 --> 00:07:44,350 ... the raw material of future Earth-like worlds. 86 00:07:45,080 --> 00:07:50,690 The Very Large Telescope is mankind’s sharpest eye on the sky. 87 00:07:51,380 --> 00:07:54,760 But astronomers have other means to expand their horizons 88 00:07:54,760 --> 00:07:56,870 and broaden their views. 89 00:07:56,870 --> 00:07:59,700 At the European Southern Observatory, 90 00:07:59,700 --> 00:08:05,590 they have learned to see the Universe in a completely different kind of light. 91 00:08:10,250 --> 00:08:14,010 This is Dr J, signing off from this special episode of the ESOcast. 92 00:08:14,010 --> 00:08:17,390 Join me again next time for another cosmic adventure. 93 00:08:20,000 --> 00:08:21,290 ESOcast is produced by ESO, 94 00:08:21,290 --> 00:08:23,470 the European Southern Observatory. 95 00:08:23,470 --> 00:08:25,290 ESO, the European Southern Observatory, 96 00:08:25,290 --> 00:08:27,470 is the pre-eminent intergovernmental science and technology organisation in astronomy, 97 00:08:27,470 --> 00:08:30,000 designing, constructing and operating the world’s most advanced ground-based telescopes. 98 00:08:32,000 --> 00:08:39,000 Transcription by ESO; translation by — 99 00:08:51,530 --> 00:08:54,330 Now that you've caught up with ESO, 100 00:08:56,260 --> 00:08:59,730 head 'out of this world' with Hubble. 101 00:09:02,400 --> 00:09:04,730 The Hubblecast highlights the latest discoveries 102 00:09:04,730 --> 00:09:08,430 of the world´s most recognized and prized space observatory, 103 00:09:11,020 --> 00:09:14,420 The NASA/ESA Hubble Space Telescope.