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Bigger is better 00:00:06:18,00:00:09:04, At night, your eyes adapt to the dark. 00:00:09:05,00:00:13:08, Your pupils widen to let more|light into your eyes. 00:00:13:09,00:00:18:14, As a result, you can see dimmer|objects, and fainter stars. 00:00:18:15,00:00:22:10, Now imagine you had pupils|one metre across. 00:00:22:11,00:00:26:16, You'd look pretty strange but you'd|also have supernatural eyesight! 00:00:26:17,00:00:30:03, And that's what telescopes do for you. 00:00:32:14,00:00:35:08, A telescope is like a funnel. 00:00:35:09,00:00:40:23, Its main lens or mirror collects the starlight|and brings it all together into your eye. 00:00:43:18,00:00:48:12, The bigger the lens or the mirror of a telescope,|the fainter the objects you can see. 00:00:48:13,00:00:51:10, So size really is everything. 00:00:51:11,00:00:54:02, But how big can you make a telescope? 00:00:54:03,00:00:57:03, Well, actually not too big if it's a refractor. 00:01:00:03,00:01:03:10, The starlight has to pass through the main lens. 00:01:03:11,00:01:06:19, And so you can only support it around its edge. 00:01:06:20,00:01:12:15, Now if you make the lens too big it becomes too heavy,|and it starts deforming under its own weight. 00:01:12:16,00:01:16:08, That means that the image will be distorted. 00:01:18:01,00:01:25:01, The largest refractor in history was completed in 1897,|at Yerkes Observatory outside Chicago. 00:01:25:02,00:01:28:05, Its main lens was just over one metre across. 00:01:28:06,00:01:32:20, But its tube was an incredible 18 metres long. 00:01:32:21,00:01:39:10, With the completion of the Yerkes telescope, the builders of|refracting telescopes had pretty much reached their limit. 00:01:39:11,00:01:41:14, You want bigger telescopes? 00:01:41:15,00:01:43:13, Think mirrors. 00:01:47:18,00:01:53:19, In a reflecting telescope, the starlight bounces|off a mirror instead of passing through a lens. 00:01:53:20,00:02:00:03, That means that you can make the mirror a lot thinner|than a lens, and you can support it from the back. 00:02:00:04,00:02:05:08, The result is that you can build|a lot larger mirrors than lenses. 00:02:06:07,00:02:10:10, Big mirrors came to southern|California a century ago. 00:02:10:11,00:02:15:15, Back then, Mount Wilson was a remote peak in|the wilderness of the San Gabriel mountains. 00:02:15:16,00:02:19:20, The sky was clear and the nights were dark. 00:02:19:21,00:02:24:09, Here, George Ellery Hale first built|a 1.5 metre telescope. 00:02:24:10,00:02:29:02, Smaller than Lord Rosse's retired Leviathan,|it was of much better quality. 00:02:29:03,00:02:32:22, And at a much better site, too. 00:02:32:23,00:02:38:09, Hale talked local businessman John Hooker|into financing a 2.5 metre instrument. 00:02:38:10,00:02:43:06, Tonnes of glass and riveted steel|were hauled up Mount Wilson. 00:02:43:07,00:02:46:18, The Hooker telescope was completed in 1917. 00:02:46:19,00:02:50:24, It would remain the largest telescope|in the world for 30 years. 00:02:51:00,00:02:56:03, A big piece of cosmic artillery,|ready to attack the Universe. 00:02:59:04,00:03:01:20, And attack it did. 00:03:01:21,00:03:04:23, Along with the incredible size of|the new telescope came 00:03:04:24,00:03:07:23, transformations in the way|the image was viewed. 00:03:07:24,00:03:11:12, Astronomers no longer peered through|the eyepiece of the new giant. 00:03:11:13,00:03:16:16, But instead collected the light on|photographic plates for hours on end. 00:03:16:17,00:03:21:13, Never before had anyone peered|so far into the cosmos. 00:03:21:14,00:03:25:21, Spiral nebulae turned out to be|brimming with individual stars. 00:03:25:22,00:03:30:07, Could they be sprawling stellar|systems like our own Milky Way? 00:03:30:08,00:03:34:12, In the Andromeda Nebula, Edwin Hubble|discovered a particular type of star 00:03:34:13,00:03:38:02, that changes its brightness with clocklike precision. 00:03:38:03,00:03:42:11, From his observations Hubble was able|to deduce the distance to Andromeda: 00:03:42:12,00:03:46:17, almost a million light-years. 00:03:46:18,00:03:53:11, Spiral nebulae, like Andromeda, were clearly|individual galaxies in their own right. 00:03:55:03,00:03:58:01, But that wasn't the only incredible thing. 00:03:58:02,00:04:02:18, Most of these galaxies were found to be|moving away from the Milky Way. 00:04:02:19,00:04:08:08, At Mount Wilson, Hubble discovered that the|nearby galaxies were receding at small velocities 00:04:08:09,00:04:13:05, whereas the distant galaxies were|moving away at a much faster pace. 00:04:13:06,00:04:14:11, The conclusion? 00:04:14:12,00:04:17:06, The Universe was expanding. 00:04:17:07,00:04:24:03, The Hooker telescope had given scientists the most|profound astronomical discovery of the 20th century. 00:04:26:19,00:04:31:08, Thanks to the telescope, we have|traced the history of the Universe. 00:04:31:09,00:04:35:15, A little less than 14 billion years ago,|the Universe was born 00:04:35:16,00:04:39:23, in a huge explosion of time and space,|matter and energy, called 00:04:39:24,00:04:42:07, the Big Bang. 00:04:42:08,00:04:48:04, Tiny quantum ripples grew into|dense patches in the primordial brew. 00:04:48:05,00:04:50:22, From these, galaxies condensed. 00:04:50:23,00:04:54:13, A stunning variety of sizes and shapes. 00:04:57:06,00:05:01:03, Nuclear fusion in the cores of|stars produced new atoms. 00:05:01:04,00:05:05:14, Carbon, oxygen, iron, gold. 00:05:05:15,00:05:10:08, Supernova explosions blew these|heavy elements back into space. 00:05:10:09,00:05:13:20, Raw material for the formation of new stars. 00:05:13:21,00:05:15:13, And planets! 00:05:17:13,00:05:25:15, Someday, somewhere, somehow, simple|organic molecules evolved into living organisms. 00:05:25:16,00:05:31:07, Life is one miracle in an|ever-evolving Universe. 00:05:31:08,00:05:33:15, We are stardust. 00:05:33:16,00:05:37:18, It's a grand vision and a sweeping story. 00:05:37:19,00:05:41:22, Brought to us through telescopic observations. 00:05:41:23,00:05:46:09, Imagine: without the telescope we|would know about just six planets 00:05:46:10,00:05:48:22, one moon, and a few thousand stars. 00:05:48:23,00:05:53:03, Astronomy would still be in its infancy. 00:05:54:08,00:05:58:04, Like buried treasures, the outposts of|the Universe have beckoned to the 00:05:58:05,00:06:00:18, adventurous from immemorial times. 00:06:00:19,00:06:06:04, Princes and potentates, political or|industrial, equally with men of science 00:06:06:05,00:06:10:23, have felt the lure of the uncharted|seas of space, and through their provision 00:06:10:24,00:06:16:03, of instrumental means the sphere|of exploration has rapidly widened. 00:06:30:11,00:06:33:09, George Ellery Hale had one final dream: 00:06:33:10,00:06:37:16, to build a telescope twice as large|as the previous record holder. 00:06:37:17,00:06:41:15, Meet the grand old lady of|20th century astronomy. 00:06:41:16,00:06:46:15, The five metre Hale telescope at Palomar Mountain. 00:06:46:16,00:06:51:06, Over five hundred tonnes of moving weight,|yet so precisely balanced 00:06:51:07,00:06:55:09, that it moves as gracefully as a ballerina. 00:06:55:10,00:07:00:23, Its 40 tonne mirror reveals stars|40 million times fainter than the eye can see. 00:07:00:24,00:07:05:23, Completed in 1948, the Hale telescope|gave us unsurpassed views of planets 00:07:05:24,00:07:09:13, star clusters, nebulae and galaxies. 00:07:11:18,00:07:15:17, Giant Jupiter, with its many moons. 00:07:15:18,00:07:19:19, The stunning Flame Nebula. 00:07:19:20,00:07:24:23, Faint wisps of gas in the Orion Nebula. 00:07:30:13,00:07:32:20, But could we go bigger still? 00:07:32:21,00:07:36:23, Well, soviet astronomers|tried in the late 1970s. 00:07:36:24,00:07:41:08, High up in the Caucasus mountains,|they built the Bolshoi Teleskop Azimutalnyi 00:07:41:09,00:07:45:15, sporting a primary mirror|six metres in diameter. 00:07:45:16,00:07:48:08, But it never really lived|up to its expectations. 00:07:48:09,00:07:52:11, It was simply too big, too expensive,|and too difficult. 00:07:52:12,00:07:55:17, So did telescope builders have|to give up at that point? 00:07:55:18,00:07:59:05, Did they have to bury their dreams|of even bigger instruments? 00:07:59:06,00:08:02:17, Had the history of the telescope|come to a premature end? 00:08:02:18,00:08:04:02, Well, of course not. 00:08:04:03,00:08:07:05, Today we have 10 metre|telescopes in operation. 00:08:07:06,00:08:09:21, And even bigger ones are|on the drawing board. 00:08:09:22,00:08:11:10, What was the solution? 00:08:11:11,00:08:13:08, New technologies.