1 00:00:00,000 --> 00:00:06,000 By scrutinising the Hubble Ultra Deep field – the deepest image of the sky ever made – 2 00:00:06,000 --> 00:00:11,000 the NASA/ESA Hubble Space Telescope and the NASA Spitzer Space Telescope have joined forces 3 00:00:11,000 --> 00:00:18,000 to discover nine of the smallest, faintest, most compact galaxies ever observed in the distant Universe. 4 00:00:37,000 --> 00:00:39,000 This is the Hubblecast! 5 00:00:39,000 --> 00:00:48,000 News and Images from the NASA/ESA Hubble Space Telescope. Travelling through time and space with our host Doctor J a.k.a. Dr Joe Liske. 6 00:00:49,000 --> 00:00:52,000 Hello and welcome to the Hubblecast! 7 00:00:52,000 --> 00:00:59,000 One of the most fundamental questions that we all ask – astronomers and laypersons alike – is: where do we come from? 8 00:00:59,000 --> 00:01:06,000 Now we, the Earth, the Sun and the rest of the Solar System, are all part of the Milky Way Galaxy, 9 00:01:06,000 --> 00:01:12,000 and so the question of our origin is closely linked to the birth and evolution of galaxies. 10 00:01:12,000 --> 00:01:16,000 Now, the Spitzer and Hubble Space Telescopes have joined forces 11 00:01:16,000 --> 00:01:23,000 to discover nine of the faintest, youngest and most compact galaxies ever observed in the distant Universe. 12 00:01:23,000 --> 00:01:32,000 Conventional theories of galaxy evolution predict that small galaxies in the early Universe evolved into the massive galaxies of today by 13 00:01:33,000 --> 00:01:39,000 merging together. The newly found young galaxies offer important new insights into the Universe’s formative period, 14 00:01:39,000 --> 00:01:42,000 just one billion years after the Big Bang. 15 00:01:42,000 --> 00:01:47,000 Hubble has detected sapphire blue stars residing within the nine pristine galaxies. 16 00:01:49,000 --> 00:01:52,000 Although they are glowing with the light of millions of stars, 17 00:01:52,000 --> 00:01:59,000 each of the newly discovered galaxies is actually a hundred to a thousand times fainter than our own Milky Way. 18 00:01:59,000 --> 00:02:09,000 Now usually, smaller things in space tend to be less interesting to astronomers than the larger ones, but in this case it’s the opposite. 19 00:02:09,000 --> 00:02:12,000 Three of the new galaxies appear to be slightly disrupted – 20 00:02:12,000 --> 00:02:19,000 instead of being shaped like rounded blobs, they appear to be stretched into tadpole-like shapes. 21 00:02:19,000 --> 00:02:28,000 Now this is a sign that they may be interacting and merging with neighbouring galaxies to form larger, cohesive structures, just as predicted by theory. 22 00:02:29,000 --> 00:02:35,000 The galaxies were observed in the Hubble Ultra Deep Field with Hubble’s Advanced Camera for Surveys 23 00:02:35,000 --> 00:02:41,000 and the Near Infrared and Multi-Object Spectrometer as well as Spitzer’s Infrared Array Camera 24 00:02:41,000 --> 00:02:46,000 and the European Southern Observatory’s Infrared Spectrometer and Array Camera. 25 00:02:48,000 --> 00:02:55,000 In today’s Hubblecast we have a special guest, Dr Martin Kümmel, from the European Hubble group in Munich. Welcome Martin. 26 00:02:55,000 --> 00:02:57,000 Hello Dr J! 27 00:02:57,000 --> 00:03:02,000 Now you and your colleagues are responsible for the particular instrument mode on Hubble that was used by the scientists. 28 00:03:02,000 --> 00:03:05,000 Can you tell us a little bit about that? 29 00:03:05,000 --> 00:03:13,000 The so-called Grism mode in the Advanced Camera for Surveys spreads the different colours emitted by the galaxies into short “trails”. 30 00:03:13,000 --> 00:03:19,000 This is an example of such a grism. One can see the rainbow colours as the light is spread out. 31 00:03:19,000 --> 00:03:22,000 So how was that used by the scientists? 32 00:03:22,000 --> 00:03:28,000 Well, the analysis of these short trails allows the detection of emission from glowing hydrogen gas, 33 00:03:28,000 --> 00:03:34,000 giving the distance as well as an estimate of the rate at which stars are formed. 34 00:03:34,000 --> 00:03:37,000 But could that not be done in a different way? 35 00:03:37,000 --> 00:03:45,000 Finely analysing such small and faint galaxies at such a great distance is at the very limit of the capabilities of the most powerful telescopes. 36 00:03:45,000 --> 00:03:50,000 The grisms onboard Hubble are the only instruments that can make this kind of discovery. 37 00:03:52,000 --> 00:03:59,000 By finding these nine tiny and exceedingly faint galaxy building blocks we followed another branch of our Galactic family tree 38 00:03:59,000 --> 00:04:05,000 and moved a small, but important, step closer to understanding our cosmic roots. 39 00:04:05,000 --> 00:04:12,000 We already know about the existence of much more massive – and therefore considerably brighter – galaxies at similarly great distances. 40 00:04:12,000 --> 00:04:21,000 How these monsters were assembled so quickly after the Big Bang remains a real puzzle for astronomers. But that is a story for another day... 41 00:04:22,000 --> 00:04:28,000 With the small galaxy building blocks we are basically witnessing galaxy formation in action. 42 00:04:28,000 --> 00:04:33,000 Something that is important if we want to understand our origin on the cosmic scale. 43 00:04:33,000 --> 00:04:36,000 This is Dr J signing off for the Hubblecast. 44 00:04:36,000 --> 00:04:41,000 Once again nature has surprised us beyond our wildest imagination … 45 00:04:42,000 --> 00:04:47,000 Hubblecast is produced by ESA/Hubble at the European Southern Observatory in Germany. 46 00:04:47,000 --> 00:04:53,000 The Hubble mission is a project of international cooperation between NASA and the European Space Agency.