1 00:00:01,046 --> 00:00:07,150 To many, Hubble is best known for its stunning images of celestial objects. 2 00:00:07,150 --> 00:00:12,344 But among astronomers, it is admired for the valuable data it delivers, 3 00:00:12,344 --> 00:00:16,000 which have helped revolutionise many areas of astronomy 4 00:00:16,000 --> 00:00:18,782 over the past 27 years. 5 00:00:20,000 --> 00:00:23,150 This is the second part of an exploration 6 00:00:23,150 --> 00:00:27,969 of some of Hubble’s most important discoveries throughout its history. 7 00:00:34,080 --> 00:00:38,191 Hubble's biggest discoveries — part II 8 00:00:39,500 --> 00:00:41,391 In the first episode 9 00:00:41,391 --> 00:00:45,600 we saw how Hubble had explored the early Universe, 10 00:00:45,600 --> 00:00:51,521 calculated its age, and helped in the search for the elusive dark energy. 11 00:00:52,249 --> 00:00:54,024 Dark energy, however, 12 00:00:54,024 --> 00:00:57,911 was not the only invisible thing Hubble helped to reveal. 13 00:00:58,363 --> 00:01:04,947 The telescope carried out a survey to study a huge swathe of the night sky, 14 00:01:04,947 --> 00:01:09,688 searching for clues about the equally mysterious — but unrelated — 15 00:01:09,688 --> 00:01:11,231 dark matter. 16 00:01:12,439 --> 00:01:17,398 Astronomers used Hubble to create a map of everyday, visible matter, 17 00:01:17,398 --> 00:01:21,944 from which they could trace the large-scale distribution of dark matter 18 00:01:21,944 --> 00:01:25,065 by studying how its gravitational presence 19 00:01:25,065 --> 00:01:27,457 distorted light in the images. 20 00:01:28,862 --> 00:01:31,617 Maps like these are a key step 21 00:01:31,617 --> 00:01:36,087 in understanding this mysterious component of the Universe. 22 00:01:39,255 --> 00:01:42,087 While dark matter is still a mystery, 23 00:01:42,087 --> 00:01:45,538 Hubble lifted the veil surrounding the cosmic monsters 24 00:01:45,538 --> 00:01:48,616 that lurk at the centre of most galaxies: 25 00:01:48,616 --> 00:01:51,444 supermassive black holes. 26 00:01:52,542 --> 00:01:56,031 Using its spectroscopic observing capabilities, 27 00:01:56,031 --> 00:02:00,982 Hubble peered into the galaxy cores and found that the stars there 28 00:02:00,982 --> 00:02:04,989 moved in tight orbits at enormous velocities. 29 00:02:05,266 --> 00:02:07,495 This strange behaviour 30 00:02:07,495 --> 00:02:12,501 indicated the presence of a truly colossal gravitational field — 31 00:02:12,501 --> 00:02:15,672 produced by a supermassive black hole. 32 00:02:16,272 --> 00:02:21,270 This was the first solid proof of their existence! 33 00:02:22,023 --> 00:02:25,994 Today it is known that black holes are located in the centres 34 00:02:25,994 --> 00:02:28,565 of almost all galaxies. 35 00:02:29,069 --> 00:02:31,000 Some of them are very active 36 00:02:31,000 --> 00:02:33,500 consuming gas from their surroundings — 37 00:02:33,500 --> 00:02:36,233 and even whole stars! 38 00:02:40,008 --> 00:02:45,457 In 2008, Hubble made something else visible for the first time. 39 00:02:45,457 --> 00:02:48,556 While studying the bright star Fomalhaut, 40 00:02:48,556 --> 00:02:51,152 the telescope discovered a tiny point of light 41 00:02:51,152 --> 00:02:54,506 in the extensive dusty ring surrounding it. 42 00:02:56,130 --> 00:02:59,412 Hubble turned its attention to planet hunting, 43 00:02:59,412 --> 00:03:03,399 taking the first direct visible-light image of a planet 44 00:03:03,399 --> 00:03:05,409 in another star system. 45 00:03:05,909 --> 00:03:09,396 While not one of its original science goals, 46 00:03:09,396 --> 00:03:14,000 Hubble has since made a name for itself as an exoplanet explorer — 47 00:03:14,000 --> 00:03:18,579 in particular studying exoplanet atmospheres. 48 00:03:19,300 --> 00:03:22,631 The chemical makeup of a planet’s atmosphere 49 00:03:22,631 --> 00:03:27,046 leaves a unique fingerprint on the starlight that passes through it. 50 00:03:27,046 --> 00:03:28,062 In this way, 51 00:03:28,062 --> 00:03:33,000 Hubble analysed for the first time the atmosphere of a super-Earth, 52 00:03:33,000 --> 00:03:35,344 40 light-years away. 53 00:03:36,400 --> 00:03:38,253 And in the future, 54 00:03:38,253 --> 00:03:44,167 Hubble could possibly find hints of life in one of these fingerprints. 55 00:03:49,345 --> 00:03:52,873 Beyond discovering and imaging exoplanets, 56 00:03:52,873 --> 00:03:57,020 Hubble has also revolutionised our overall understanding 57 00:03:57,020 --> 00:03:59,450 of planet formation. 58 00:03:59,450 --> 00:04:03,866 Studying the Orion Nebula, Hubble made the stunning discovery 59 00:04:03,866 --> 00:04:06,845 that at least half of the stars in the region 60 00:04:06,845 --> 00:04:11,283 were surrounded by vast discs of rotating gas and dust — 61 00:04:12,488 --> 00:04:16,797 the raw materials necessary for the formation of planets. 62 00:04:19,446 --> 00:04:21,050 Prior to Hubble’s work, 63 00:04:21,050 --> 00:04:25,264 just one planetary system had ever been confirmed. 64 00:04:25,264 --> 00:04:29,180 Hubble’s observations showed that planets are being formed 65 00:04:29,180 --> 00:04:32,774 around many more stars than previously thought, 66 00:04:32,774 --> 00:04:38,154 increasing the possibility that life could exist somewhere out there. 67 00:04:41,328 --> 00:04:43,896 Alongside planet formation, 68 00:04:43,896 --> 00:04:48,207 Hubble has always been interested in the birth, life and death 69 00:04:48,207 --> 00:04:50,399 of their parent stars. 70 00:04:51,805 --> 00:04:54,857 Hubble’s high resolving power has been crucial 71 00:04:54,857 --> 00:04:57,926 in the investigation of star formation regions, 72 00:04:57,926 --> 00:05:01,799 both in the Milky Way and in other galaxies; 73 00:05:04,100 --> 00:05:07,900 and its infrared capabilities have allowed it to peer through 74 00:05:07,900 --> 00:05:12,420 the thick clouds of dust and gas present in these regions. 75 00:05:20,430 --> 00:05:25,793 The death of a star can be as beautiful and interesting as its birth. 76 00:05:25,793 --> 00:05:28,753 Hubble has observed both Sun-like stars 77 00:05:28,753 --> 00:05:32,841 as they come to the end of their lives in the form of planetary nebulae, 78 00:05:32,841 --> 00:05:38,707 and massive stars experiencing explosive deaths as supernovae. 79 00:05:44,025 --> 00:05:47,794 By studying them at different times in their lives, 80 00:05:47,794 --> 00:05:51,898 Hubble has allowed us to paint a more complete picture of stars, 81 00:05:51,898 --> 00:05:54,545 the building blocks of galaxies. 82 00:05:57,264 --> 00:06:02,035 Throughout the last 27 years, Hubble — and nature itself — 83 00:06:02,035 --> 00:06:06,931 have continued to surprise us beyond our wildest imaginations. 84 00:06:06,931 --> 00:06:12,194 And there is no doubt that they will continue to do so in the future. 85 00:06:15,104 --> 00:06:25,683 Transcription by ESA/Hubble; translation by —