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We live in a world ablaze with colour.
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Rainbows and rainforests, oceans and humanity.
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Earth is the most colourful place we know of.
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It's easy to take our colourful world for granted.
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Red, yellow and blue are some of the first words we learn
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but the colours we see are far more complex
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and fascinating than they appear.
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Each one has its own story to tell.
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I'm Dr Helen Czerski.
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I'm a physicist and I'm fascinated by colour.
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In this series, I'm going to uncover exactly what it is, how it
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works and how it has written the story of our planet.
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'I'll seek out the colours that transformed the Earth,
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'from a ball of rock to a vivid jewel...'
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This salt and this colour
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has a little bit more to it than meets the eye.
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'..and the colours that life has used to survive and thrive.'
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So these insects are broadcasting a code. It's almost like Morse code.
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This is communication in colour.
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'And I'm going in search of the colours that
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'exist beyond the rainbow...'
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We're observing the invisible.
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'..to discover why our future will be shaped by colours our eye
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'can't even perceive.'
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We've developed a completely new technology that can image people.
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That's a huge step forward.
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I'm going to tell our story from an unusual perspective...
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..by looking at 15 colours that made the world and us.
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Just look at all of this.
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Blue lake, green trees, blue sky, red and yellow apple.
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The Earth is a fantastically colourful place.
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These colours emerged deep in the past.
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Each one is a clue to a vital process that has shaped the Earth.
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And each helps answer a fundamental question -
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how did our world come to be this way?
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In this programme, I'm going in search of five colours that
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tell the story of our planet.
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It's a story that begins with light.
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Our planet is bathed in light from our nearest star...
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..the sun.
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When we think of the colour of the sun, we usually think of yellow,
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and it certainly looks yellowish at the moment,
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but it isn't really that colour.
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The yellow hue of the sun conceals the real nature of sunlight.
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Hidden within each sunbeam are the secrets of colour -
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what it is and what it does.
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I'm on my way to a place where I can reveal the essence of sunlight.
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This is the Big Bear Solar Observatory,
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set on a lake in the mountains of Southern California.
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It's the largest solar telescope in the world.
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Professor Dale Gary is director of the observatory.
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The intriguing question is, what makes this unusual spot
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a good place to study the workings of the sun?
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Why would you build an observatory here, in the middle of a lake?
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Here, we want to observe in the daytime,
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and that's when the land would normally be heating up.
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So what we want to do is be in the vicinity of a lake,
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have a nice, cool lake that keeps the sun's heat from heating up
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the atmosphere above it.
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High-altitude lakes are the perfect place to observe the sun.
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For most of human history, people thought sunlight was pure
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and unchangeable.
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The bright orb in the sky bathes the world in light,
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pure, white light.
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But then came one of the biggest revelations in science,
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which came about when Sir Isaac Newton experimented with a prism.
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Isaac Newton was the first person to appreciate
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the significance of a really simple experiment.
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When he did it, he blacked out a room in his house
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and just let in a single sunbeam through a chink in the curtains.
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And in front of that he put a prism,
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something that was relatively new at that time.
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I've got a much more sophisticated set-up here
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because I'm taking advantage of this fantastic solar telescope,
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and this is a modern prism,
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but Isaac Newton would absolutely have recognised this experiment.
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When the light comes through the prism,
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the prism slows it down and it bends it.
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And what Isaac Newton saw coming out of the prism told him
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something really fundamental about the nature of light.
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And it was this.
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This is the visible spectrum,
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from red through orange and yellow
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through green and blue and all the way to violet.
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White light isn't an absence of colour,
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it's all the colours folded in together.
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And what Newton realised is that if you put those components back
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together, you get white light once more.
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But that white light hides within in it all
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the ingredients for our visual world.
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What we'd believed to be pure,
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immutable white light was actually a vivid spectrum.
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At one end, shorter wavelengths of light that we see as blue
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ranging through to the other end,
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longer wavelengths of light that we see as red.
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The combination of different wavelengths of light
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is what creates every hue and shade that we can see.
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It's an amazing thought - that light can't exist without colour...
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..and colour can't exist without light.
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Today, nearly four centuries after Newton's revelation,
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the solar astronomers at Big Bear are able to study
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the sun in intricate detail, helping to reveal another
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fundamental truth about what colour actually is.
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By using filters to look at the sun in all the different
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colours of the spectrum, scientists can detect
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features on its surface that were previously unknown.
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It's a seething, dynamic world
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where vast magnetic fields can spit matter and energy
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out into space, sending them rippling through the solar system.
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So here, we see lots of features here
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that are following the magnetic field, so these linear...
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They look like twisted ropes, almost. That's right.
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And the twisting is actually an indication of stored energy.
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They begin to twist and some of it starts to unravel,
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so when they unravel enough, it becomes very sudden
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and you see this flare occur over just a few minutes.
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Oh, wow! And then suddenly, the flare is generated.
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This is really thrilling. What I've just seen is a solar flare -
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a massive ejection of electromagnetic energy from the sun.
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These are some of the highest-energy events in our solar system.
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Each one is capable of sending the same energy
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as a billion nuclear bombs hurtling towards our planet.
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So the sun very occasionally launches things out into space
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and if the Earth is in the firing line, we feel their influence.
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That's right. And it can be as often as a couple of times a month.
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When they do arrive, then you can have magnetic disturbances which
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can affect satellite signals and GPS signals...
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..and cellphones and the power grids...
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..and then actually cause great currents to flow and
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destroy transformers, and that can be very bad for a big power system.
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It's easy to think of the sun as just a sort of yellow
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circle in the sky but, in fact, it's a dynamic system. It's doing things
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and it's sending material out in our direction.
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Yes.
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If the sun didn't have magnetic fields and this activity,
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it would be as boring as most astronomers believe it is.
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SHE LAUGHS
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The Earth is bathed in a colossal flood of energy from the sun.
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A tiny part of that energy is the sunlight we see.
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All light, and therefore all colour, carries energy...
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..and the variety of different wavelengths
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leads to another essential truth about colour.
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This is Betelgeuse - a star that's glowing red.
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This colour tells us its temperature is about 3,000 degrees Celsius.
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From this, we know we're looking at an ageing star
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coming to the end of its life.
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And this is Sirius - a star that's glowing blue.
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This colour indicates a temperature of nearly 10,000 degrees,
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so we know it's a younger and hotter star.
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So colour isn't just energy, it's also information,
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and astronomers have learned to read the information
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contained in colour to discover what different stars are made of.
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As Newton first did with his prism,
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they bend the light from a star to break it into its colour spectrum.
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Dark lines in the spectrum
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mark the presence of specific chemical elements,
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each of which absorbs a precise wavelength of coloured light.
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So the pattern of dark lines reveals exactly which
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elements are present in the star.
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And what of our own sun?
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This view from the International Space Station shows how it
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looks to the rest of the universe.
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Here, above Earth's atmosphere, it glows a milky white.
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This is the sun's true colour.
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It's a striking view,
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one that only a handful of humans have seen with their own eyes.
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Below, you can see the sun's reflection on the Earth's
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surface, and it is a rich yellow,
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the colour that we Earthbound humans see when we look at the sun.
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That's because when sunlight reaches the Earth,
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it interacts with our planet's thick atmosphere.
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The blue wavelengths are scattered, making the sky blue...
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..and the sun appear yellow.
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As the sun sets, our view of its colour becomes ever more distorted.
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The atmosphere acts like a giant version of Newton's prism,
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bending the light first to orange then red and,
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if the conditions are just right, a brief and final glimpse of green.
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And in the darkness of night,
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we can perhaps best appreciate the full significance of colour.
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There's a huge richness in the colourful world around us,
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offering all kinds of clues as to what's going on,
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but we can only see those colours
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because there's light shining on them.
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If there's no light, no colour, no information.
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It's only in sunlight that the Earth explodes in colour.
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And there's one colour that seems to dominate our world.
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But the paradox of blue is that
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while it seems to be all around us, very rarely is it solid or tangible.
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Blue's absent from the palate of the land itself
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and scarce in the plants and animals that inhabit it.
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There are exceptions, striking to our eye because they're unusual.
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IT SQUAWKS
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This scarcity meant that our early human ancestors had very
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little contact with the colour blue.
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It's almost entirely absent from ancient art and literature...
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..and many languages still don't have a specific word for it, even today.
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Perhaps that's because it's always out of reach.
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We can't touch the blueness of the sky
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or capture the deep blue of the oceans.
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Yet, in some remote corners,
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the Earth does harbour this elusive colour.
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The way it got there
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provides a clue to how our vivid planet came into existence.
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And to get my hands on it, I'm about to enter a very different world.
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David Margulies is an artist, historian
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and devotee of the colour blue.
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In his London studio, he works with some of the rarest minerals
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and pigments on Earth.
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Among them all, the most spectacular are the blues.
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And one blue in particular takes pride of place on his shelves.
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This is a piece of lapis lazuli that's come from the one
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mountain in Afghanistan.
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So the important thing here is this blue colour
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and that is lapis lazuli.
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It is. It was the most precious and most expensive of all the pigments.
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There aren't many blue things in nature,
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so this must have been a spectacular thing to display and to find.
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Someone had walked through the mountains of Afghanistan
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and come across a blue stone.
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And it makes me wonder whether they believed that the sky had
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fallen to the Earth and turned to rock.
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I love that idea, the sky that had fallen into a rock.
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That's exactly what it looks like, isn't it?
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'The colour is so stunning.
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'I can imagine the impact it must have made when lapis first
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'arrived in Europe, when trade routes from the east opened up.'
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It was seen as extremely valuable.
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In Renaissance Italy it was
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so expensive it was the equivalent of the price of gold.
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To have this was a status symbol
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and the most visible way of having it was to put it on a painting
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cos you could paint this colour onto a big canvas
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and show that you had this commodity.
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So it's not a subtle way of displaying your status.
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It's saying, for everyone to see... I don't think it's subtle at all.
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I think the most important aspect is that lapis
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does have a slightly mystical quality.
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So, when it came to painting,
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quite often the blue was used
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to paint the robes of Mary.
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Probably the most famous artist to have used it is Titian.
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'There's something entrancing about this colour,
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'but to discover what it can tell us about our planet,
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'I need to do what painters do,
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'and get right inside this rock.'
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An artist is presented with a lump of this rock,
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and they have to make paint out of it. What do they do?
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They hammer it. Not very sophisticated.
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Hammer it until it gets smaller and smaller.
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It's quite satisfying, this.
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This is the first time it's been a colour cos this has never seen daylight before.
252
00:18:06,000 --> 00:18:08,000
That bit of rock I've just smashed has just become
253
00:18:08,000 --> 00:18:10,000
a colour for the first time.
254
00:18:10,000 --> 00:18:13,000
So the next one along... So now we've got a lot of broken up bits,
255
00:18:13,000 --> 00:18:17,000
and you can start to see blue powder... That's right.
256
00:18:17,000 --> 00:18:19,000
..and that's what the pigment is, it's the powder,
257
00:18:19,000 --> 00:18:22,000
when it becomes a powder. That's right.
258
00:18:24,000 --> 00:18:27,000
It's a horrible noise. It's such a horrible noise.
259
00:18:27,000 --> 00:18:29,000
You might smell it as well.
260
00:18:29,000 --> 00:18:33,000
Oh! There's a really strong smell of sulphur.
261
00:18:33,000 --> 00:18:36,000
It is sulphur. Sulphur is what makes the rock blue.
262
00:18:37,000 --> 00:18:38,000
And then the final stage,
263
00:18:38,000 --> 00:18:42,000
when it's broken down, is what we've got in the last one here.
264
00:18:42,000 --> 00:18:44,000
This is the bluest thing I've ever seen.
265
00:18:46,000 --> 00:18:49,000
'It's the chemistry of this rock that creates its colour.
266
00:18:51,000 --> 00:18:54,000
'Sulphur more often produces yellowish compounds...
267
00:18:54,000 --> 00:18:57,000
This is lovely, lovely stuff.
268
00:18:57,000 --> 00:19:00,000
'..but in lapis lazuli, the unique combination of sulphur with
269
00:19:00,000 --> 00:19:06,000
'other elements, produces this deep, rich blue we call ultramarine.'
270
00:19:16,000 --> 00:19:19,000
And this is it. This is the final step.
271
00:19:20,000 --> 00:19:24,000
The blue powder has been mixed with oil and some wax
272
00:19:24,000 --> 00:19:26,000
and it's a paint.
273
00:19:26,000 --> 00:19:29,000
And so this rock that looks like it fell from the sky
274
00:19:29,000 --> 00:19:30,000
is becoming sky all over again.
275
00:19:34,000 --> 00:19:38,000
When we look at this, we just see a blue rock,
276
00:19:38,000 --> 00:19:41,000
but the secret to that colour is hidden in the atoms
277
00:19:41,000 --> 00:19:43,000
that make this up.
278
00:19:43,000 --> 00:19:46,000
But the atoms themselves aren't enough.
279
00:19:46,000 --> 00:19:50,000
To get this you need to transform them.
280
00:19:50,000 --> 00:19:53,000
For a transformation to this dramatic blue
281
00:19:53,000 --> 00:19:56,000
you need the sorts of pressures and temperatures
282
00:19:56,000 --> 00:19:58,000
with which planets are forged.
283
00:20:21,000 --> 00:20:26,000
Humans have made lapis a part of our culture in exquisite, delicate ways.
284
00:20:26,000 --> 00:20:28,000
But its origins couldn't be more different,
285
00:20:28,000 --> 00:20:31,000
and they're certainly a very long way from a sophisticated art gallery.
286
00:20:36,000 --> 00:20:40,000
'I've come high into the mountains of Southern California,
287
00:20:40,000 --> 00:20:44,000
'one of the few places on the planet where lapis lazuli can be found.
288
00:20:47,000 --> 00:20:50,000
'It takes a unique set of conditions to produce the vivid colour
289
00:20:50,000 --> 00:20:53,000
'of this rock,
290
00:20:53,000 --> 00:20:54,000
'and Professor George Rossman,
291
00:20:54,000 --> 00:20:58,000
a geologist at the California Institute of Technology,
292
00:20:58,000 --> 00:21:01,000
'is going to help me understand how it formed.'
293
00:21:01,000 --> 00:21:04,000
Here's an example. The blue is kind of interesting.
294
00:21:04,000 --> 00:21:05,000
It comes from sulphur.
295
00:21:05,000 --> 00:21:08,000
The important thing is we have to get three sulphur atoms,
296
00:21:08,000 --> 00:21:11,000
and we have to line them up in a row - one, two, three atoms in a chain,
297
00:21:11,000 --> 00:21:15,000
trapped inside a cage inside the mineral, to make this happen.
298
00:21:19,000 --> 00:21:22,000
'It takes extreme temperatures
299
00:21:22,000 --> 00:21:26,000
'and pressures to force sulphur atoms to combine in this particular way.
300
00:21:26,000 --> 00:21:31,000
'So the very existence of this rock is a telltale sign of the powerful
301
00:21:31,000 --> 00:21:36,000
'forces that formed our planet, and are still at work deep within it.'
302
00:21:36,000 --> 00:21:39,000
When we look at this, we see this amazing colour,
303
00:21:39,000 --> 00:21:42,000
and everyone loves looking at it, but, really, what we're looking at is
304
00:21:42,000 --> 00:21:46,000
evidence, direct evidence, that this was deep down in the Earth's crust.
305
00:21:46,000 --> 00:21:49,000
Oh, this has been down in the cauldron of geological fire,
306
00:21:49,000 --> 00:21:51,000
down 35km, 40km below the surface.
307
00:21:51,000 --> 00:21:55,000
And then that has to get taken into a really active geological area
308
00:21:55,000 --> 00:21:57,000
to be heated up.
309
00:21:57,000 --> 00:22:01,000
Molten rock came in, rock like this one right here,
310
00:22:01,000 --> 00:22:05,000
and then the heat from this rock started a series of chemical reactions.
311
00:22:05,000 --> 00:22:07,000
So it's a very specific type of oven, that.
312
00:22:07,000 --> 00:22:08,000
Oh, yes.
313
00:22:08,000 --> 00:22:10,000
So it would have been red hot that deep down,
314
00:22:10,000 --> 00:22:12,000
and then as it came up it became blue.
315
00:22:12,000 --> 00:22:15,000
Absolutely correct. Through earthquakes and tectonic activity
316
00:22:15,000 --> 00:22:19,000
these rocks have been slowly brought up over tens of millions of years,
317
00:22:19,000 --> 00:22:21,000
so they're now 2km to 3km above sea level.
318
00:22:21,000 --> 00:22:23,000
It's an amazing process.
319
00:22:30,000 --> 00:22:34,000
This rock has been deep down into the Earth's crust
320
00:22:34,000 --> 00:22:38,000
and it's been transformed by the processes that shape our planet.
321
00:22:38,000 --> 00:22:40,000
And its colour is a reminder of that.
322
00:22:41,000 --> 00:22:44,000
It's appropriate that that colour is blue, perhaps,
323
00:22:44,000 --> 00:22:46,000
because we live on a blue planet.
324
00:22:49,000 --> 00:22:53,000
'Just how dominant this colour truly is, is a fairly recent discovery.
325
00:22:54,000 --> 00:22:56,000
'It's only within the past 60 years,
326
00:22:56,000 --> 00:23:02,000
'when humans got into space and gained the ability to look back at ourselves,
327
00:23:02,000 --> 00:23:05,000
'that we've been able to see our planet in its colourful entirety.
328
00:23:07,000 --> 00:23:12,000
'A single photograph, taken a quarter of a million miles from Earth,
329
00:23:12,000 --> 00:23:15,000
'changed our view of our home, forever.
330
00:23:17,000 --> 00:23:20,000
'On Christmas Eve, 1968,
331
00:23:20,000 --> 00:23:24,000
'as Apollo Eight made its way around the dark side of the Moon,
332
00:23:24,000 --> 00:23:27,000
'astronaut Bill Anders picked up his camera
333
00:23:27,000 --> 00:23:29,000
'and began to take pictures.'
334
00:23:32,000 --> 00:23:34,000
I just clicked away and just kept turning,
335
00:23:34,000 --> 00:23:37,000
and I took at least a dozen, maybe 50 pictures,
336
00:23:37,000 --> 00:23:41,000
one of which was selected by others to be Earthrise.
337
00:23:42,000 --> 00:23:44,000
'This is phenomenal.'
338
00:23:44,000 --> 00:23:49,000
Out of the lunar horizon came this beautiful blue.
339
00:23:51,000 --> 00:23:53,000
'Earthrise depicted our home planet
340
00:23:53,000 --> 00:23:57,000
'in a way that nobody back on Earth had ever seen before...
341
00:23:59,000 --> 00:24:02,000
'Let there be light. And there was light.'
342
00:24:04,000 --> 00:24:07,000
'..a planet dominated by the colour blue.'
343
00:24:10,000 --> 00:24:14,000
Even though we were hard-bitten test and fighter pilots,
344
00:24:14,000 --> 00:24:16,000
this thing was beautiful.
345
00:24:17,000 --> 00:24:20,000
'Our home is defined by this single colour.
346
00:24:22,000 --> 00:24:25,000
'A vibrant blue orb,
347
00:24:25,000 --> 00:24:28,000
'suspended against the blackness of the cosmos.
348
00:24:33,000 --> 00:24:36,000
'It's from this vast expanse of space
349
00:24:36,000 --> 00:24:39,000
'that one of our most celebrated colours emerged.
350
00:24:41,000 --> 00:24:44,000
'It's a colour we've worshipped for millennia.
351
00:24:45,000 --> 00:24:47,000
'Wars have been fought over it,
352
00:24:47,000 --> 00:24:51,000
'and yet its very presence on the face of the Earth is an accident.
353
00:24:53,000 --> 00:24:55,000
'There's an extraordinary story here,
354
00:24:55,000 --> 00:24:59,000
'one that reveals the next great force that shaped our planet.
355
00:25:12,000 --> 00:25:14,000
'And to tell it,
356
00:25:14,000 --> 00:25:17,000
'I'm going to start somewhere most of us would never normally get to see.'
357
00:25:20,000 --> 00:25:23,000
I'm somewhere close to central London, but I can't tell you where
358
00:25:23,000 --> 00:25:26,000
and that's because I'm on my way to a secret location.
359
00:25:31,000 --> 00:25:34,000
'I'm about to get my hands on this most precious
360
00:25:34,000 --> 00:25:36,000
'and mysterious of colours.'
361
00:25:40,000 --> 00:25:43,000
It's worth all the secrecy when you get to this.
362
00:25:43,000 --> 00:25:46,000
It's absolutely unmistakable.
363
00:25:46,000 --> 00:25:49,000
There's only one metal that's this colour,
364
00:25:49,000 --> 00:25:51,000
and it's gold.
365
00:25:51,000 --> 00:25:55,000
This is very, very pure gold. It's 99.99% pure
366
00:25:55,000 --> 00:25:58,000
and it's also frighteningly valuable.
367
00:25:58,000 --> 00:26:03,000
At today's prices, it's apparently worth ?26,000.
368
00:26:03,000 --> 00:26:06,000
You can see why humans value this so much.
369
00:26:07,000 --> 00:26:09,000
It is stunningly beautiful.
370
00:26:11,000 --> 00:26:16,000
'The secret of gold's mesmerising colour comes from its chemistry.
371
00:26:16,000 --> 00:26:19,000
'Gold atoms reflect yellow and red wavelengths,
372
00:26:19,000 --> 00:26:22,000
'producing a deep, rich yellow,
373
00:26:22,000 --> 00:26:26,000
'that's accentuated by gold's metallic shine.
374
00:26:28,000 --> 00:26:31,000
'This unique combination of factors
375
00:26:31,000 --> 00:26:34,000
'makes it seem like gold is generating a warm light of its own.
376
00:26:36,000 --> 00:26:40,000
'It's this property that's enchanted us since ancient times.
377
00:26:43,000 --> 00:26:45,000
'But it's only due to an accident of history,
378
00:26:45,000 --> 00:26:49,000
'that we're able to get our hands on gold at all.
379
00:26:49,000 --> 00:26:51,000
'The story of this precious colour
380
00:26:51,000 --> 00:26:54,000
'reveals one of the most dramatic events that shaped our planet.
381
00:27:00,000 --> 00:27:04,000
'Gold didn't exist when the universe was first formed.
382
00:27:04,000 --> 00:27:07,000
'To make gold and other heavy metals,
383
00:27:07,000 --> 00:27:10,000
'it took unimaginably powerfully forces
384
00:27:10,000 --> 00:27:13,000
'to fuse the atoms of lighter elements together.
385
00:27:13,000 --> 00:27:17,000
'Perhaps the explosion of a supernova, a dying star.
386
00:27:22,000 --> 00:27:25,000
'Or perhaps, as recent research has suggested,
387
00:27:25,000 --> 00:27:29,000
'the colossal energy of two neutron stars,
388
00:27:29,000 --> 00:27:32,000
'tearing each other apart to form a black hole.
389
00:27:38,000 --> 00:27:40,000
'In the early solar system,
390
00:27:40,000 --> 00:27:43,000
'there was a sprinkling of this newly forged metal
391
00:27:43,000 --> 00:27:47,000
'in the swirling mass of dust that would eventually form the planets.
392
00:27:52,000 --> 00:27:55,000
'But this is where the story of gold becomes really intriguing.'
393
00:28:01,000 --> 00:28:04,000
Most of the time when we pick up gold, a necklace or a bracelet,
394
00:28:04,000 --> 00:28:09,000
it's something small, and so you don't really notice how heavy it is.
395
00:28:09,000 --> 00:28:12,000
But with these, it's really noticeable that they're really,
396
00:28:12,000 --> 00:28:13,000
really heavy.
397
00:28:14,000 --> 00:28:16,000
We've all heard someone say
398
00:28:16,000 --> 00:28:18,000
that a person is worth their weight in gold.
399
00:28:18,000 --> 00:28:23,000
Well, this is the pile of gold that weighs the same as me.
400
00:28:23,000 --> 00:28:27,000
It's worth ?1.6 million.
401
00:28:27,000 --> 00:28:29,000
The thing is, it's quite a small pile.
402
00:28:29,000 --> 00:28:32,000
It doesn't take up nearly as much space as I do.
403
00:28:32,000 --> 00:28:36,000
It's been squashed down, so it only fills up a very small space.
404
00:28:36,000 --> 00:28:39,000
Each individual gold atom is very, very big,
405
00:28:39,000 --> 00:28:43,000
but the consequence is that gold is very dense and very heavy.
406
00:28:45,000 --> 00:28:49,000
'But I shouldn't be able to hold this dense metal in my hands
407
00:28:49,000 --> 00:28:53,000
'because gold shouldn't really exist on the surface of the planet at all.
408
00:28:56,000 --> 00:28:59,000
'The early Earth was a ball of molten rock.
409
00:29:01,000 --> 00:29:03,000
'In these furnace temperatures,
410
00:29:03,000 --> 00:29:06,000
'gold and other metals existed as a viscous molten mass.
411
00:29:08,000 --> 00:29:10,000
'Over tens of millions of years,
412
00:29:10,000 --> 00:29:13,000
'this mixture of metals sank,
413
00:29:13,000 --> 00:29:18,000
'dragging gold deep into the Earth's core,
414
00:29:18,000 --> 00:29:20,000
'thousands of miles beyond our reach.
415
00:29:28,000 --> 00:29:31,000
'And yet, in certain places on Earth,
416
00:29:31,000 --> 00:29:34,000
'gold lies tantalisingly close to the surface...
417
00:29:36,000 --> 00:29:39,000
'..just waiting to be plucked from the ground.'
418
00:29:45,000 --> 00:29:47,000
This is Jamestown in California,
419
00:29:47,000 --> 00:29:51,000
and it's a town that's got gold woven through its history.
420
00:29:52,000 --> 00:29:55,000
In the hills about 80 miles north of here,
421
00:29:55,000 --> 00:29:57,000
in 1848,
422
00:29:57,000 --> 00:30:02,000
James W Marshall saw the first glint of gold in California.
423
00:30:03,000 --> 00:30:04,000
As the news spread,
424
00:30:04,000 --> 00:30:08,000
hundreds of thousands of people flooded here,
425
00:30:08,000 --> 00:30:10,000
seeking their fortune,
426
00:30:10,000 --> 00:30:14,000
each desperately hoping to see that same golden glimmer.
427
00:30:14,000 --> 00:30:17,000
It became known as the California Gold Rush.
428
00:30:26,000 --> 00:30:30,000
'But if gold did sink deep into Earth's core,
429
00:30:30,000 --> 00:30:34,000
'where did the gold that fuelled the California Gold Rush come from?
430
00:30:36,000 --> 00:30:42,000
'Steve Mojzsis is Professor of Geology at the University of Colorado
431
00:30:42,000 --> 00:30:44,000
'and he's brought with him a clue that points
432
00:30:44,000 --> 00:30:48,000
'to an exotic and violent origin for the gold we find on Earth...'
433
00:30:49,000 --> 00:30:53,000
This one fell in Siberia in 1947.
434
00:30:53,000 --> 00:30:55,000
'..a fragment of a meteorite.'
435
00:30:58,000 --> 00:31:01,000
A very interesting story emerges.
436
00:31:01,000 --> 00:31:04,000
Meteorites are the leftovers of planet formation.
437
00:31:04,000 --> 00:31:09,000
In a sense they're a chemical museum of the early Solar System.
438
00:31:09,000 --> 00:31:11,000
What's inside a meteorite, then?
439
00:31:11,000 --> 00:31:16,000
What they contain are all of the elements that go into making the Earth,
440
00:31:16,000 --> 00:31:18,000
including abundant gold.
441
00:31:22,000 --> 00:31:25,000
So there were meteorites flying around the solar system
442
00:31:25,000 --> 00:31:26,000
full of precious metals?
443
00:31:26,000 --> 00:31:30,000
That's correct, and occasionally these would have struck the Earth.
444
00:31:34,000 --> 00:31:37,000
So we think it was meteorites that delivered the precious
445
00:31:37,000 --> 00:31:41,000
cargo of gold to Earth's surface early in its history.
446
00:31:43,000 --> 00:31:46,000
'Many scientists think there's only one explanation
447
00:31:46,000 --> 00:31:49,000
'for the presence of gold near the Earth's surface.
448
00:31:50,000 --> 00:31:55,000
'It had to be transported here from outer space
449
00:31:55,000 --> 00:31:58,000
'during an intense period of meteorite
450
00:31:58,000 --> 00:32:01,000
'and comet bombardment nearly four billion years ago.
451
00:32:03,000 --> 00:32:07,000
'This violent event left scars across our Solar System,
452
00:32:07,000 --> 00:32:11,000
'including many of the craters that we can still see on the surface of the Moon.
453
00:32:16,000 --> 00:32:19,000
'The craters left on Earth have long since gone,
454
00:32:19,000 --> 00:32:22,000
'worn away by tectonic movement, weathering and erosion.
455
00:32:23,000 --> 00:32:26,000
'But what the meteorites brought with them remains.'
456
00:32:28,000 --> 00:32:31,000
Here's the Earth, all well-separated
457
00:32:31,000 --> 00:32:33,000
with all of the metals where
458
00:32:33,000 --> 00:32:35,000
they're supposed to be in the core,
459
00:32:35,000 --> 00:32:38,000
and then this planet was salted
460
00:32:38,000 --> 00:32:44,000
with meteorite debris that brought metals with it, including gold.
461
00:32:44,000 --> 00:32:49,000
That's the surprising conclusion of the origin of gold to Earth's surface.
462
00:32:55,000 --> 00:32:57,000
Even though the planet had a new supply of gold,
463
00:32:57,000 --> 00:33:01,000
there wasn't anything to see because it was just too dilute.
464
00:33:01,000 --> 00:33:05,000
The gold that there was, was a tiny fraction of the Earth's crust
465
00:33:05,000 --> 00:33:08,000
and it was spread out around the planet. It was really rare.
466
00:33:09,000 --> 00:33:12,000
And yet, billions of years later,
467
00:33:12,000 --> 00:33:17,000
a human could just pick up a nugget of gold out of the landscape.
468
00:33:17,000 --> 00:33:21,000
To get from one to the other, the planet had one final trick to play.
469
00:33:27,000 --> 00:33:31,000
'With only one gram of gold for every thousand tonnes of the Earth's
470
00:33:31,000 --> 00:33:34,000
'crust, there had to be a way to concentrate the tiny
471
00:33:34,000 --> 00:33:37,000
'particles of gold, into the colour we see today.
472
00:33:42,000 --> 00:33:46,000
'And across the surface of the planet is something that can do just that.
473
00:33:49,000 --> 00:33:51,000
'In the streams around Jamestown,
474
00:33:51,000 --> 00:33:55,000
'prospector Brent Shock relies on the properties of water
475
00:33:55,000 --> 00:33:59,000
'to seek his fortune, just like the original Gold Rush pioneers.
476
00:34:01,000 --> 00:34:04,000
'In doing so, he's mimicking the planetary processes
477
00:34:04,000 --> 00:34:06,000
'that finally brought us gold.'
478
00:34:09,000 --> 00:34:10,000
Just sprinkle a little in here.
479
00:34:10,000 --> 00:34:12,000
So this is just dirt from the side there?
480
00:34:12,000 --> 00:34:14,000
This is it. Yeah.
481
00:34:14,000 --> 00:34:15,000
So it's like a little ladder here
482
00:34:15,000 --> 00:34:17,000
and the stream's bouncing over the ladder?
483
00:34:17,000 --> 00:34:20,000
It creates a low-pressure area. Water slows, gold drops. Yes.
484
00:34:20,000 --> 00:34:22,000
You've got your crevices here.
485
00:34:22,000 --> 00:34:25,000
You've got your low-pressure areas there with the ripples.
486
00:34:27,000 --> 00:34:29,000
And if it's dancing a little bit,
487
00:34:29,000 --> 00:34:31,000
the gold can work its way down
488
00:34:31,000 --> 00:34:33,000
and they will grab hold of the fine gold.
489
00:34:33,000 --> 00:34:36,000
So it's getting caught just behind these ridges?
490
00:34:36,000 --> 00:34:37,000
Exactly.
491
00:34:39,000 --> 00:34:42,000
And then you just look through this and look for the colour?
492
00:34:42,000 --> 00:34:45,000
Yeah, we look, we don't put our fingers in. Oh. really?
493
00:34:45,000 --> 00:34:48,000
THEY LAUGH That's me told, isn't it!
494
00:34:48,000 --> 00:34:49,000
So this looks really simple,
495
00:34:49,000 --> 00:34:52,000
but actually there's a very sophisticated thing going on.
496
00:34:52,000 --> 00:34:54,000
You're the scientist.
497
00:34:56,000 --> 00:35:00,000
A stream can replicate, naturally, this set-up here? Yeah.
498
00:35:00,000 --> 00:35:04,000
Constantly rolling. Constantly rising and settling.
499
00:35:04,000 --> 00:35:06,000
Every time the water rises and then starts,
500
00:35:06,000 --> 00:35:09,000
you can come out here a find gold laying on the bedrock.
501
00:35:09,000 --> 00:35:11,000
Almost a renewable resource.
502
00:35:11,000 --> 00:35:13,000
So we keep shovelling this stuff in.
503
00:35:16,000 --> 00:35:18,000
You want to look at the gold.
504
00:35:18,000 --> 00:35:19,000
Is it coarse, is it smooth?
505
00:35:19,000 --> 00:35:22,000
The smoother it is, the farther it's travelled.
506
00:35:22,000 --> 00:35:23,000
Then you want to triangulate your way up
507
00:35:23,000 --> 00:35:26,000
to find out where the vein is, where the source is.
508
00:35:26,000 --> 00:35:30,000
That's what everybody wants, the source of what's feeding this.
509
00:35:33,000 --> 00:35:37,000
'Over millions of years, water picked up gold,
510
00:35:37,000 --> 00:35:39,000
'transported, sorted,
511
00:35:39,000 --> 00:35:42,000
'and concentrated it,
512
00:35:42,000 --> 00:35:46,000
'and then deposited in a form that made it easier for us to find.
513
00:35:47,000 --> 00:35:49,000
It's a process that's still happening,
514
00:35:49,000 --> 00:35:52,000
'and drives our continued obsession
515
00:35:52,000 --> 00:35:55,000
'with one of Earth's most alluring colours.'
516
00:35:59,000 --> 00:36:03,000
This spectacular colour has been on quite a journey.
517
00:36:03,000 --> 00:36:06,000
These atoms have travelled from a distant star in time to be
518
00:36:06,000 --> 00:36:08,000
there for the birth of the solar system.
519
00:36:08,000 --> 00:36:11,000
And then they hit the Earth in an impact which left a golden
520
00:36:11,000 --> 00:36:13,000
signature on our landscape.
521
00:36:13,000 --> 00:36:15,000
And even then it didn't stop,
522
00:36:15,000 --> 00:36:17,000
because there were sorting processes,
523
00:36:17,000 --> 00:36:20,000
first by geology and then by water,
524
00:36:20,000 --> 00:36:23,000
until humans could pluck nuggets like this from the landscape.
525
00:36:23,000 --> 00:36:25,000
And still it carries on,
526
00:36:25,000 --> 00:36:28,000
because there are atoms from Egyptian jewellery
527
00:36:28,000 --> 00:36:30,000
or Inca trinkets that are almost certainly
528
00:36:30,000 --> 00:36:33,000
part of modern wedding rings or gold bullion.
529
00:36:36,000 --> 00:36:38,000
So the cycling carries on,
530
00:36:38,000 --> 00:36:42,000
but this fantastic colour stays exactly the same.
531
00:36:49,000 --> 00:36:52,000
'It's amazing to think that we would never have seen the colour gold
532
00:36:52,000 --> 00:36:54,000
'if it wasn't for the action of water.
533
00:36:57,000 --> 00:37:00,000
'But water has shaped our planet in more fundamental ways.
534
00:37:01,000 --> 00:37:04,000
'Some of its powers we can witness for ourselves...
535
00:37:08,000 --> 00:37:12,000
'..but others, no less important, are hidden from view.
536
00:37:14,000 --> 00:37:16,000
'And to show you,
537
00:37:16,000 --> 00:37:19,000
'I've come to one of the driest places on Earth
538
00:37:19,000 --> 00:37:21,000
'in search of one particular colour.'
539
00:37:32,000 --> 00:37:35,000
I'm 2km up above the floor of Death Valley,
540
00:37:35,000 --> 00:37:38,000
here in the USA, looking out over this tremendous view.
541
00:37:40,000 --> 00:37:44,000
It looks like an alien landscape, but there's a colour down there
542
00:37:44,000 --> 00:37:48,000
which has a huge amount to tell us about things we see every day.
543
00:37:49,000 --> 00:37:54,000
We think of white as a colour of innocence and purity,
544
00:37:54,000 --> 00:37:57,000
but down there, in this harsh landscape,
545
00:37:57,000 --> 00:38:00,000
those white streaks have two stories to tell.
546
00:38:01,000 --> 00:38:04,000
The first is the story of the tiny,
547
00:38:04,000 --> 00:38:08,000
of how this colour works and why it's so common.
548
00:38:08,000 --> 00:38:12,000
And the second is the story of the gigantic,
549
00:38:12,000 --> 00:38:15,000
because the way that this colour is concentrated here
550
00:38:15,000 --> 00:38:19,000
is a reminder of the scale of the processes that sculpt our planet
551
00:38:19,000 --> 00:38:22,000
and paint vast swathes of it in specific colours.
552
00:38:34,000 --> 00:38:38,000
From that fabulous viewpoint, I'm driving down into the valley,
553
00:38:38,000 --> 00:38:42,000
to a place with a fantastic name. It's called the Badwater Basin
554
00:38:42,000 --> 00:38:43,000
and it's very, very low down.
555
00:38:43,000 --> 00:38:46,000
It's not just the lowest place in this valley,
556
00:38:46,000 --> 00:38:48,000
it's the lowest place in all of North America,
557
00:38:48,000 --> 00:38:52,000
and the bottom of it is 85m below sea level.
558
00:39:10,000 --> 00:39:14,000
This is what I could see from above the valley and it's salt.
559
00:39:14,000 --> 00:39:17,000
There are hundreds of square kilometres of it here.
560
00:39:17,000 --> 00:39:19,000
It's just sodium chloride,
561
00:39:19,000 --> 00:39:21,000
what you'd find on your dinner table,
562
00:39:21,000 --> 00:39:25,000
but this salt, and this colour, has a little bit more to it than meets the eye.
563
00:39:31,000 --> 00:39:35,000
'As far as I can see, and crunching under my boots,
564
00:39:35,000 --> 00:39:39,000
'is what appears to be a solid carpet of brilliant white.
565
00:39:43,000 --> 00:39:45,000
'But look at this salt more closely
566
00:39:45,000 --> 00:39:47,000
'and something strange happens.'
567
00:39:49,000 --> 00:39:51,000
Here it is, a handful of salt,
568
00:39:51,000 --> 00:39:54,000
and it's bright white, just like all the salt around me.
569
00:39:54,000 --> 00:39:55,000
But the salt isn't t really white,
570
00:39:55,000 --> 00:39:59,000
and we can see its true nature if we look at it under a microscope.
571
00:39:59,000 --> 00:40:01,000
And then this little camera
572
00:40:01,000 --> 00:40:04,000
is projecting an image onto the screen here.
573
00:40:04,000 --> 00:40:07,000
And what you can see is that each little crystal is a square
574
00:40:07,000 --> 00:40:09,000
and that's because the salt crystals are cubes.
575
00:40:09,000 --> 00:40:13,000
They've got flat edges. There's an orange card behind
576
00:40:13,000 --> 00:40:16,000
and we can see that orange card through these crystals.
577
00:40:16,000 --> 00:40:19,000
Light is going straight through them and coming straight back out.
578
00:40:19,000 --> 00:40:22,000
And what that tells us is that these crystals aren't white,
579
00:40:22,000 --> 00:40:24,000
they're completely transparent.
580
00:40:26,000 --> 00:40:28,000
'We don't see the colour of the card any differently,
581
00:40:28,000 --> 00:40:31,000
'whether a salt crystal is in the way or not.
582
00:40:33,000 --> 00:40:35,000
'White light from the sun comes in,
583
00:40:35,000 --> 00:40:38,000
'and orange light bounces back from the card to our eyes.'
584
00:40:41,000 --> 00:40:43,000
So if the crystals themselves don't have any colour at all,
585
00:40:43,000 --> 00:40:50,000
why is it that my little pile of salt here, and all of this, looks white?
586
00:40:50,000 --> 00:40:51,000
Well, we can see why
587
00:40:51,000 --> 00:40:54,000
if we start to move the microscope to where there's a big pile of them.
588
00:40:54,000 --> 00:40:57,000
If you've got a stack of crystals all together,
589
00:40:57,000 --> 00:41:00,000
the light comes in and it's bent as it passes through the first
590
00:41:00,000 --> 00:41:02,000
crystal and then bent again as it passes through the second crystal.
591
00:41:02,000 --> 00:41:05,000
And so it zigzags its way through the pile of salt,
592
00:41:05,000 --> 00:41:08,000
and it eventually it finds its way out to our eyes.
593
00:41:10,000 --> 00:41:12,000
'With a pile of salt crystals,
594
00:41:12,000 --> 00:41:17,000
'the sunlight bounces around inside them and never reaches the orange card,
595
00:41:17,000 --> 00:41:21,000
'so its orange colour remains hidden beneath and never gets to our eyes.'
596
00:41:23,000 --> 00:41:26,000
White light went in, bounced around, and white light came out,
597
00:41:26,000 --> 00:41:28,000
and that's why we see salt as white.
598
00:41:33,000 --> 00:41:36,000
'It isn't just salt that's white because of this.
599
00:41:39,000 --> 00:41:42,000
'Many things we see as white on a big scale
600
00:41:42,000 --> 00:41:45,000
'are actually made up of tiny, transparent components.
601
00:41:48,000 --> 00:41:51,000
'Clouds are small particles of colourless water
602
00:41:51,000 --> 00:41:53,000
'suspended in colourless air.
603
00:41:57,000 --> 00:41:59,000
'The white foam of breaking waves
604
00:41:59,000 --> 00:42:02,000
'is just a turbulent mixture of water and air.
605
00:42:08,000 --> 00:42:12,000
'And snow is made up of tiny, colourless ice crystals.
606
00:42:25,000 --> 00:42:28,000
'In fact anything transparent that's small enough
607
00:42:28,000 --> 00:42:31,000
'to bounce sunlight around on a tiny scale,
608
00:42:31,000 --> 00:42:32,000
'like these bubbles,
609
00:42:32,000 --> 00:42:34,000
'will look white on a bigger scale.
610
00:42:42,000 --> 00:42:46,000
'But the secret of the colour white is just the beginning of what
611
00:42:46,000 --> 00:42:48,000
'this landscape can reveal.
612
00:42:49,000 --> 00:42:52,000
'Even the presence of this mass of white salt
613
00:42:52,000 --> 00:42:55,000
'tells us a much bigger story about our planet.
614
00:42:58,000 --> 00:43:02,000
'Geologist Garry Hayes has spent years working in Death Valley
615
00:43:02,000 --> 00:43:05,000
'and studying the process by which these salt flats formed.'
616
00:43:09,000 --> 00:43:13,000
We're in the hottest, driest place in the entire Northern Hemisphere.
617
00:43:13,000 --> 00:43:17,000
And the windiest, it feels like. And the windiest, it feels like.
618
00:43:17,000 --> 00:43:20,000
So, I'm just going to pick a bit up here.
619
00:43:20,000 --> 00:43:23,000
What's quite striking is that this is just mud,
620
00:43:23,000 --> 00:43:26,000
and then there's this layer of salt on top just like icing.
621
00:43:26,000 --> 00:43:30,000
Exactly. This feels wet to me but that's brine. It is wet.
622
00:43:30,000 --> 00:43:32,000
It's very salty. It is wet, but it's drying quickly.
623
00:43:32,000 --> 00:43:33,000
SHE LAUGHS
624
00:43:35,000 --> 00:43:38,000
And every two or three years you would be standing in a lake
625
00:43:38,000 --> 00:43:40,000
right now, a foot or two deep of water.
626
00:43:42,000 --> 00:43:45,000
The water evaporates, the salt stays.
627
00:43:45,000 --> 00:43:48,000
This salt has been accumulating in this one low area
628
00:43:48,000 --> 00:43:50,000
for the last couple of million years.
629
00:43:53,000 --> 00:43:57,000
'So even here, in one of the driest places on Earth,
630
00:43:57,000 --> 00:44:00,000
'it's water that has shaped and coloured the landscape.
631
00:44:02,000 --> 00:44:07,000
'Water collects here at Badwater Basin from a vast area all around.
632
00:44:07,000 --> 00:44:10,000
'There's no lower point it can flow to.
633
00:44:10,000 --> 00:44:14,000
'so under the baking sun, there's only one place it can go -
634
00:44:16,000 --> 00:44:17,000
'Up.'
635
00:44:20,000 --> 00:44:23,000
So, water brought the salt here, but where did the water come from?
636
00:44:23,000 --> 00:44:27,000
There is a vast amount of ground water underneath this region,
637
00:44:27,000 --> 00:44:30,000
especially underneath these mountains, so water actually travels
638
00:44:30,000 --> 00:44:33,000
and trickles through the mountains rather than around them.
639
00:44:33,000 --> 00:44:35,000
The mountains around us formed between 300
640
00:44:35,000 --> 00:44:38,000
and 600 million years ago on the bottom of the sea.
641
00:44:38,000 --> 00:44:41,000
And these rocks have been pushed up and they've been eroded,
642
00:44:41,000 --> 00:44:44,000
and there are small amounts of salt in the rocks themselves.
643
00:44:44,000 --> 00:44:47,000
So the salt dissolves into the water as the water's flowing here?
644
00:44:47,000 --> 00:44:48,000
Absolutely, yes.
645
00:44:48,000 --> 00:44:50,000
And when it gets here, the salt has nowhere else to go?
646
00:44:50,000 --> 00:44:52,000
It has nowhere else to go.
647
00:44:52,000 --> 00:44:55,000
And it's sitting right below us, right now? It is.
648
00:44:59,000 --> 00:45:01,000
'Here on Death Valley's salt flats,
649
00:45:01,000 --> 00:45:05,000
'the forces that shaped and painted our planet are still in play.
650
00:45:09,000 --> 00:45:13,000
'Every year, about 5cm of rain falls,
651
00:45:13,000 --> 00:45:16,000
'but the evaporation rate is so high,
652
00:45:16,000 --> 00:45:19,000
'it could remove a lake 4m deep in that time.
653
00:45:22,000 --> 00:45:24,000
'So the salt flats continue to grow.
654
00:45:26,000 --> 00:45:31,000
'Beneath my feet is a staggering 3km of salty sediment.
655
00:45:32,000 --> 00:45:35,000
'The intense sun dries out the surface,
656
00:45:35,000 --> 00:45:38,000
'creating this vivid layer of white.'
657
00:45:41,000 --> 00:45:43,000
Look out at this enormous valley
658
00:45:43,000 --> 00:45:46,000
and imagine the slow geological
659
00:45:46,000 --> 00:45:51,000
processes that have shifted and transformed it over eons.
660
00:45:51,000 --> 00:45:54,000
And in this, the place of extremes,
661
00:45:54,000 --> 00:45:57,000
incredibly hot, incredibly dry,
662
00:45:57,000 --> 00:45:59,000
and way below sea level,
663
00:45:59,000 --> 00:46:02,000
those processes have concentrated one colour.
664
00:46:03,000 --> 00:46:09,000
But the details of that colour come from the tiny shape of the crystals.
665
00:46:09,000 --> 00:46:14,000
So you need both the minuscule and the gigantic to generate this,
666
00:46:14,000 --> 00:46:16,000
the purest of colours.
667
00:46:27,000 --> 00:46:32,000
'Our planet's story is captured in the colours it has forged.
668
00:46:32,000 --> 00:46:36,000
'In blue, we see the sheer power of the forces that heaved within
669
00:46:36,000 --> 00:46:39,000
'the young Earth, creating mountains and continents.
670
00:46:45,000 --> 00:46:48,000
'Gold bears witness to a time when meteorites crashed to Earth
671
00:46:48,000 --> 00:46:51,000
'with a cargo of riches, '
672
00:46:51,000 --> 00:46:53,000
that changed our planet forever.
673
00:46:56,000 --> 00:47:01,000
'The dazzling white of salt crystals reveals water as a hidden force,
674
00:47:01,000 --> 00:47:04,000
'sculpting the face of the Earth in unseen ways.
675
00:47:07,000 --> 00:47:11,000
'But there's one more colour that can reveal our planet's final
676
00:47:11,000 --> 00:47:13,000
'and most vital transformation...
677
00:47:16,000 --> 00:47:19,000
'..the one that led to life
678
00:47:19,000 --> 00:47:21,000
'and, ultimately, to us.'
679
00:47:40,000 --> 00:47:42,000
Deep underground isn't the sort of place you would expect to go
680
00:47:42,000 --> 00:47:44,000
looking for a colour.
681
00:47:44,000 --> 00:47:47,000
This colour has only been present for half of Earth's history,
682
00:47:47,000 --> 00:47:50,000
but once it did appear, it appeared on a massive scale.
683
00:47:54,000 --> 00:47:57,000
Hidden right beneath my feet is a colour that represents
684
00:47:57,000 --> 00:48:00,000
one of the biggest transitions in Earth's history.
685
00:48:04,000 --> 00:48:07,000
'I've come to Clearwell Caves in the Forest of Dean,
686
00:48:07,000 --> 00:48:11,000
'a natural cave system, which extends for 30km
687
00:48:11,000 --> 00:48:14,000
'under the Gloucestershire countryside.
688
00:48:14,000 --> 00:48:18,000
'These caves have been mined for more than 4,000 years,
689
00:48:18,000 --> 00:48:22,000
'since the earliest human societies settled in this part of the world.
690
00:48:34,000 --> 00:48:36,000
'The substance those miners were digging for
691
00:48:36,000 --> 00:48:40,000
'is a clue to a remarkable event that transformed Earth
692
00:48:40,000 --> 00:48:41,000
'more than two billion years ago.'
693
00:48:47,000 --> 00:48:50,000
Thousands of miners have been down here
694
00:48:50,000 --> 00:48:53,000
and some of them were looking for this, and this is iron ore.
695
00:48:53,000 --> 00:48:56,000
It's got tremendous potential for civilisation.
696
00:48:56,000 --> 00:48:59,000
Just think of all the things you can turn this into.
697
00:48:59,000 --> 00:49:02,000
A knife or armour or an ornament,
698
00:49:02,000 --> 00:49:04,000
or, later on, a Spitfire.
699
00:49:04,000 --> 00:49:08,000
Tools for neurosurgery or a steam engine.
700
00:49:08,000 --> 00:49:10,000
But this isn't a particularly colourful rock
701
00:49:10,000 --> 00:49:12,000
and it's not what I've come down here to see.
702
00:49:19,000 --> 00:49:23,000
'Another material has been mined here for far longer than iron ore.
703
00:49:26,000 --> 00:49:29,000
'It comes from the same rock, but whilst iron ore is dull
704
00:49:29,000 --> 00:49:31,000
'metallic grey,
705
00:49:31,000 --> 00:49:34,000
'the same can't be said for its colourful cousin.'
706
00:49:42,000 --> 00:49:45,000
This is it. This is red ochre
707
00:49:45,000 --> 00:49:48,000
and it's a really dramatic colour. You don't expect to see
708
00:49:48,000 --> 00:49:52,000
something this striking down in a dark cave like this.
709
00:49:52,000 --> 00:49:55,000
It's actually quite disconcerting sitting here because,
710
00:49:55,000 --> 00:50:00,000
sitting in this hollow of red is a bit like sitting in the mouth of a monster.
711
00:50:00,000 --> 00:50:03,000
It's no coincidence that the iron ore
712
00:50:03,000 --> 00:50:06,000
and the red ochre are found in the same caves,
713
00:50:06,000 --> 00:50:09,000
because to get vast quantities of this red,
714
00:50:09,000 --> 00:50:12,000
what you need is iron and then one very specific molecule.
715
00:50:18,000 --> 00:50:21,000
'With iron filings
716
00:50:21,000 --> 00:50:24,000
'and some salty water,
717
00:50:24,000 --> 00:50:27,000
'it's a process that's remarkably easy to replicate.'
718
00:50:36,000 --> 00:50:39,000
To get this fabulous red colour from grey iron filings,
719
00:50:39,000 --> 00:50:41,000
the trick is to add oxygen.
720
00:50:43,000 --> 00:50:46,000
I just sped it up a little bit, but, basically, adding the water
721
00:50:46,000 --> 00:50:48,000
and a little bit of salt makes the iron
722
00:50:48,000 --> 00:50:51,000
and the oxygen react together a little bit faster.
723
00:50:51,000 --> 00:50:55,000
Because all this is, is a beaker of rust.
724
00:50:55,000 --> 00:50:57,000
And so the combination of oxygen
725
00:50:57,000 --> 00:50:59,000
and iron has just turned this red very, very quickly.
726
00:50:59,000 --> 00:51:02,000
But it's also, over geological time,
727
00:51:02,000 --> 00:51:04,000
what's turned all of these rocks red.
728
00:51:09,000 --> 00:51:11,000
'Go back three billion years
729
00:51:11,000 --> 00:51:15,000
'and the formation of these rocks would have been impossible.
730
00:51:16,000 --> 00:51:20,000
'That's because the atmosphere lacked one crucial ingredient -
731
00:51:20,000 --> 00:51:22,000
'oxygen.
732
00:51:22,000 --> 00:51:25,000
'The fact that these red rocks are here today
733
00:51:25,000 --> 00:51:28,000
'is a clue to, perhaps, the most fundamental change
734
00:51:28,000 --> 00:51:30,000
'in our planet's history.
735
00:51:30,000 --> 00:51:32,000
'The arrival of oxygen created an atmosphere
736
00:51:32,000 --> 00:51:34,000
'that could sustain complex life.
737
00:51:37,000 --> 00:51:40,000
'With me deep underground is Dr Corinna Abesser.
738
00:51:41,000 --> 00:51:44,000
'She's an expert in the chemistry of Earth's atmosphere
739
00:51:44,000 --> 00:51:47,000
'and water systems, and how they've changed over time.'
740
00:51:49,000 --> 00:51:52,000
The Earth would have been a very different place back then.
741
00:51:52,000 --> 00:51:55,000
The atmosphere would have been mostly carbon dioxide.
742
00:51:55,000 --> 00:51:59,000
And back then, there was iron actually in the water of the ocean?
743
00:51:59,000 --> 00:52:03,000
The ocean would contain a lot of dissolved iron.
744
00:52:03,000 --> 00:52:07,000
So even though this is our own planet, this was a very alien world.
745
00:52:07,000 --> 00:52:09,000
Acidic oceans with dissolved iron
746
00:52:09,000 --> 00:52:11,000
and a horrible atmosphere, by our standards.
747
00:52:17,000 --> 00:52:19,000
'And then something changed,
748
00:52:19,000 --> 00:52:21,000
'that changed all that chemistry.'
749
00:52:22,000 --> 00:52:25,000
So around three billion years ago,
750
00:52:25,000 --> 00:52:27,000
new organisms developed called cyanobacteria.
751
00:52:31,000 --> 00:52:33,000
And they used all the ingredients that
752
00:52:33,000 --> 00:52:38,000
existed in abundance at the time, namely carbon dioxide,
753
00:52:38,000 --> 00:52:40,000
water and sunlight,
754
00:52:40,000 --> 00:52:42,000
to produce energy, food.
755
00:52:42,000 --> 00:52:45,000
And a waste product of that is oxygen.
756
00:52:48,000 --> 00:52:52,000
'Cyanobacteria are microscopically tiny organisms
757
00:52:52,000 --> 00:52:55,000
'that evolved in the early oceans.
758
00:52:55,000 --> 00:52:57,000
'They were the first living things to use the process
759
00:52:57,000 --> 00:53:00,000
'we call photosynthesis.
760
00:53:00,000 --> 00:53:03,000
'That is, they used carbon dioxide, water and sunlight
761
00:53:03,000 --> 00:53:06,000
'to produce food to sustain themselves,
762
00:53:06,000 --> 00:53:09,000
'the same process plants still use today.
763
00:53:09,000 --> 00:53:14,000
'And, crucially, the waste product of that chemical reaction is oxygen.
764
00:53:18,000 --> 00:53:23,000
'The presence of this vital new element had a dramatic effect on the planet's oceans.'
765
00:53:26,000 --> 00:53:29,000
These early organisms, the cyanobacteria,
766
00:53:29,000 --> 00:53:31,000
were producing oxygen as waste,
767
00:53:31,000 --> 00:53:34,000
so suddenly there's oxygen creeping into the ocean environment.
768
00:53:34,000 --> 00:53:35,000
Where did it go?
769
00:53:35,000 --> 00:53:40,000
Initially, that would have been used up by all the free iron that was...
770
00:53:40,000 --> 00:53:43,000
or the dissolved iron that was in the ocean,
771
00:53:43,000 --> 00:53:47,000
to form iron oxides, which is a red mineral.
772
00:53:47,000 --> 00:53:50,000
And then you've got, basically, red dust raining out of the oceans
773
00:53:50,000 --> 00:53:52,000
and just falling to the ocean floor
774
00:53:52,000 --> 00:53:54,000
and building up over a very long period of time.
775
00:53:54,000 --> 00:53:56,000
Covering the oceans in a layer of red.
776
00:53:59,000 --> 00:54:02,000
'So, at first, oxygen combined with the dissolved
777
00:54:02,000 --> 00:54:05,000
'iron in the oceans to form solid iron oxide.
778
00:54:08,000 --> 00:54:11,000
'Eventually, when this iron had been used up,
779
00:54:11,000 --> 00:54:15,000
'oxygen continued to accumulate and made its way into our atmosphere...
780
00:54:21,000 --> 00:54:24,000
'..transforming it gradually into the air we breathe today,
781
00:54:24,000 --> 00:54:26,000
'essential for life as we know it.
782
00:54:28,000 --> 00:54:32,000
'And that oxygen also reacted with other elements in the environment.
783
00:54:32,000 --> 00:54:34,000
'changing the colour of our planet.'
784
00:54:35,000 --> 00:54:38,000
And once you've got free oxygen in the atmosphere,
785
00:54:38,000 --> 00:54:41,000
and that's part of what's generated the ochre around us here?
786
00:54:41,000 --> 00:54:45,000
Yes, iron will react with oxygen to form iron oxide,
787
00:54:45,000 --> 00:54:48,000
and that's what we see here in these caves.
788
00:54:48,000 --> 00:54:52,000
So these tiny organisms changed the colour of the planet?
789
00:54:52,000 --> 00:54:54,000
Yes.
790
00:55:04,000 --> 00:55:07,000
'Even though the combination of iron and oxygen
791
00:55:07,000 --> 00:55:10,000
'has painted swathes of our planet red,
792
00:55:10,000 --> 00:55:12,000
'it's created other colours. too.
793
00:55:18,000 --> 00:55:21,000
'Iron oxide can exist in various forms,
794
00:55:21,000 --> 00:55:24,000
'all of which have their own distinctive colour.'
795
00:55:31,000 --> 00:55:35,000
Ochre isn't just the red colours, the haematite.
796
00:55:35,000 --> 00:55:36,000
There's lots of others as well.
797
00:55:36,000 --> 00:55:39,000
Right here there's yellow, and there are also purples and browns,
798
00:55:39,000 --> 00:55:44,000
so just this one compound has a whole paint box associated with it.
799
00:55:47,000 --> 00:55:51,000
And it's a strange thought that 2.3 billion years ago
800
00:55:51,000 --> 00:55:53,000
in an ancient ocean,
801
00:55:53,000 --> 00:55:56,000
one of the simplest organisms we know of
802
00:55:56,000 --> 00:55:59,000
started producing a waste product, oxygen.
803
00:55:59,000 --> 00:56:04,000
And that heralded the first appearance of these colours.
804
00:56:04,000 --> 00:56:06,000
And then 2.3 billion years after that,
805
00:56:06,000 --> 00:56:09,000
one of the most complicated organisms we know of,
806
00:56:09,000 --> 00:56:11,000
a human being,
807
00:56:11,000 --> 00:56:14,000
walked up to a wall like this
808
00:56:14,000 --> 00:56:17,000
and did what comes naturally. They did this.
809
00:56:27,000 --> 00:56:31,000
'Ochre is so common and so colourful that it's been
810
00:56:31,000 --> 00:56:34,000
'used in art for more than 75,000 years...
811
00:56:36,000 --> 00:56:40,000
'..reflecting the importance our ancestors placed on the colour red.
812
00:56:46,000 --> 00:56:50,000
'It's found in prehistoric cave paintings across Europe,
813
00:56:50,000 --> 00:56:52,000
'the Americas and Australasia.
814
00:56:54,000 --> 00:56:57,000
'Even though these distant civilisations never met,
815
00:56:57,000 --> 00:57:00,000
'the content of their art is remarkably similar.
816
00:57:01,000 --> 00:57:05,000
'And their ubiquitous use of red symbolises the relationship
817
00:57:05,000 --> 00:57:08,000
'between them and the land from which they sourced this colour.'
818
00:57:20,000 --> 00:57:25,000
These are ancient colours, both for our planet and for our species,
819
00:57:25,000 --> 00:57:28,000
but what an accident of history these represent.
820
00:57:29,000 --> 00:57:34,000
A waste product, oxygen, seeped into the early Earth,
821
00:57:34,000 --> 00:57:35,000
ended an era,
822
00:57:35,000 --> 00:57:37,000
and began another.
823
00:57:37,000 --> 00:57:40,000
The raw mineral colours of Earth
824
00:57:40,000 --> 00:57:43,000
were about to become the background for a far richer palette
825
00:57:43,000 --> 00:57:46,000
because the arrival of oxygen made possible
826
00:57:46,000 --> 00:57:47,000
the arrival of complex life.
827
00:57:49,000 --> 00:57:53,000
This new palette would be driven by evolution
828
00:57:53,000 --> 00:57:57,000
and so these colours represent the transition of Earth
829
00:57:57,000 --> 00:58:01,000
from a hostile, young planet to something new.
830
00:58:01,000 --> 00:58:02,000
A home.
831
00:58:04,000 --> 00:58:06,000
'Next time, the colours of life.
832
00:58:08,000 --> 00:58:09,000
'I'll discover the bizarre
833
00:58:09,000 --> 00:58:13,000
'and beautiful ways that the living world has harnessed colour...
834
00:58:13,000 --> 00:58:16,000
The forest here is green and healthy.
835
00:58:16,000 --> 00:58:21,000
'..from basic survival to the strange and sophisticated.'
836
00:58:21,000 --> 00:58:25,000
Deep-down physiological changes, broadcast in colour.
837
00:58:27,000 --> 00:58:30,000
Discover more about the story of the colours of the Earth
838
00:58:30,000 --> 00:58:32,000
with The Open University.
839
00:58:32,000 --> 00:58:35,000
Go to...
840
00:58:35,000 --> 00:58:38,000
..and follow the links to The Open University.
72636
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