1 00:00:00,000 --> 00:00:07,000 Have you ever wondered why some telescopes are launched into space while others are built on remote mountain tops? 2 00:00:07,000 --> 00:00:09,000 What is actually the best for astronomy? 3 00:00:09,000 --> 00:00:17,000 Here we provide a ringside view of the fight for the elusive photons from deep space – is it a battle of the telescope giants? 4 00:00:35,000 --> 00:00:37,000 This is the Hubblecast! 5 00:00:37,000 --> 00:00:47,000 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 00:00:48,000 --> 00:00:50,000 Welcome to the Hubblecast! 7 00:00:50,000 --> 00:00:55,000 Now when I was a kid, I often used to stare at the night sky and wonder what it was all about. 8 00:00:55,000 --> 00:01:01,000 Now back then I usually only used my eyes, or at most a pair of binoculars. 9 00:01:01,000 --> 00:01:06,000 But astronomers have telescopes that are much more powerful than the naked eye 10 00:01:06,000 --> 00:01:10,000 and which can be used to uncover the faintest and most distant objects in the Universe. 11 00:01:20,000 --> 00:01:28,000 Now in today’s Hubblecast we will take a small detour from our usual flow of amazing discoveries and images from the NASA/ESA Hubble Space Telescope 12 00:01:28,000 --> 00:01:33,000 and look at the most fundamental tool used by astronomers – the telescope. 13 00:01:33,000 --> 00:01:41,000 Now it all began nearly 400 years ago when Galileo Galilei for the first time looked at the Universe through a small telescope. 14 00:01:41,000 --> 00:01:49,000 Now this momentous occasion will actually be celebrated in 2009, which has been declared the International Year of Astronomy. 15 00:01:51,000 --> 00:01:55,000 Today we have telescopes of many different sizes and shapes. Some are on the ground, 16 00:01:56,000 --> 00:02:03,000 like ESO’s Very Large Telescope, located on a remote 2600-metre high mountain in the Atacama desert in Chile - 17 00:02:03,000 --> 00:02:07,000 it’s seen here in one of the most sophisticated computer models ever made. 18 00:02:47,000 --> 00:02:54,000 Some telescopes are in space, like the Hubble Space Telescope in orbit around Earth almost 600 kilometres further up. 19 00:03:07,000 --> 00:03:09,000 So how does a telescope work? 20 00:03:09,000 --> 00:03:19,000 Well, common to almost all telescopes, regardless of size or purpose, is that they have a mirror, some instruments and a few supporting systems. 21 00:03:19,000 --> 00:03:27,000 Now the main function of the mirror is to collect as much light as possible from distant stars and galaxies. It is not to magnify anything 22 00:03:28,000 --> 00:03:33,000 as many people think. Then there are a number of secondary mirrors that send the light to the instruments. 23 00:03:33,000 --> 00:03:36,000 Now there are two main types of instruments. 24 00:03:36,000 --> 00:03:43,000 First, there are cameras, which essentially do what any normal digital camera does - they take images. 25 00:03:43,000 --> 00:03:54,000 And then there are the spectrographs that spread the incoming light into its constituent colours like a rainbow, which can tell a lot about the physics of distant objects. 26 00:03:55,000 --> 00:04:04,000 Ingenious engineers and imaginative astronomers around the world compete in a scientific battle of how to unveil the secrets of the Universe. 27 00:04:04,000 --> 00:04:12,000 So who is winning? Are the ground-based telescopes better because they are larger and collect more light from faint stars and galaxies? 28 00:04:12,000 --> 00:04:19,000 Or are the space-based telescopes winning the race as they can make sharper images above the clouds and the disturbing atmosphere? 29 00:04:19,000 --> 00:04:23,000 On that count, ground-based astronomy is fast catching up. 30 00:04:23,000 --> 00:04:30,000 Advanced techniques such as adaptive optics have been developed to correct for the atmospheric blurring and twinkling! 31 00:04:30,000 --> 00:04:34,000 On the other hand, the atmosphere blocks certain wavelengths of light. 32 00:04:34,000 --> 00:04:42,000 Only space telescopes, like Hubble, that fly above the atmosphere can access the ultraviolet and infrared parts of the spectrum, 33 00:04:42,000 --> 00:04:44,000 which are invisible from the ground. 34 00:04:44,000 --> 00:04:50,000 Ground-based telescopes on the other hand can observe larger portions of the sky in one go, 35 00:04:50,000 --> 00:04:56,000 and also usually have more specialised instruments that are easier to change when new techniques are developed. 36 00:04:57,000 --> 00:05:07,000 It would of course make for a much more exciting Hubblecast episode if we could show you a bloody battle between furious ground-based and space-based astronomers. 37 00:05:07,000 --> 00:05:12,000 But in reality there is no battle between ground-based and space-based telescopes. 38 00:05:12,000 --> 00:05:20,000 Observing teams often use combinations of different telescopes, on the ground and in space to solve the riddles of the Universe. 39 00:05:21,000 --> 00:05:24,000 So the bottom line is it’s not a competition. 40 00:05:24,000 --> 00:05:29,000 It’s the synergy and complementarity between all the different kinds of telescope that matter, 41 00:05:29,000 --> 00:05:35,000 whether they are small or large, in the Southern or Northern hemisphere, on the ground or in space. 42 00:05:35,000 --> 00:05:42,000 What matters is that they’re all working towards a common cause: discovering the secrets of the world around us. 43 00:05:44,000 --> 00:05:46,000 This is Dr J signing off for the Hubblecast, 44 00:05:46,000 --> 00:05:53,000 which by the way, will be available from today onwards in High-Definition from spacetelescope.org. 45 00:05:54,000 --> 00:05:58,000 Hubblecast is produced by ESA/Hubble at the European Southern Observatory in Germany. 46 00:05:58,000 --> 00:06:03,000 The Hubble mission is a project of international cooperation between NASA and the European Space Agency.