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00:00Our world is beautiful to look at.
00:25It's even more beautiful to understand.
00:42Generations of unimaginable power have forged our precious planet.
00:56They have created landscapes of endless variety and wonder.
01:06Earth is painted with stunning colours.
01:11Clues that reveal deep truths about what Earth is made of and how it works.
01:24Clues that allow us to search for planets like our own.
01:41On the 31st of August, 2014, a vast chasm opened up in the Earth.
02:11The Bauderbundga volcano in central Iceland.
02:22Thousands of tons of molten rock spewed out onto the surface, creating a lava field covering
02:2880 square kilometres, blazing at nearly 2,000 degrees Celsius and glowing orange-red.
02:45The light was so bright it could be seen from space.
03:03Six months after the eruption has ceased, particle physicist Professor Brian Cox visits
03:09the lava field.
03:20He explains that to understand how things make light involves looking at the world on
03:26a subatomic scale.
03:30Lumps of matter, like lava or me and you, are made of electrically charged particles
03:37And there's a fundamental law of nature which says that if you take an electric charge and
03:43you accelerate it, so you jiggle it, change its direction in some way, it will emit light.
03:53This is how all light is made.
03:56In the lava, atoms vibrate and particles of light are released.
04:03These particles are called photons.
04:06Particles of energy that we perceive as colour.
04:13Which colour is determined by the speed at which those atoms vibrate?
04:19Temperature is a measure of how fast the constituents, atoms and molecules, inside something are
04:25moving around.
04:26So the hotter it is, the faster they're moving around and the more energy they've got.
04:33Lava is a code.
04:38The colour of something hot can tell us how hot it is.
04:46At around 2,000 degrees Celsius, the lava's molecules emit red and orange photons.
05:00Lava is one of the hottest things on Earth.
05:03But in space, stars burn much hotter and more brightly.
05:15At over 6,000 degrees Celsius, the sun is so hot and its atoms move so quickly, they
05:23emit not just red and orange photons, but many more higher energy green and blue ones too.
05:37All these different coloured photons pouring out of the sun combine.
05:44Together, they create the white light that illuminates the Earth.
05:54A rain of colour photons pours down on our planet.
06:02Wherever you can find sunlight, you will find the colour hidden within.
06:09Even after dark.
06:25In a few places on Earth, on just a handful of nights of the year, the light of the full
06:37moon can be cracked open, revealing the unique code all light contains.
07:02Stéphane Wetter is consumed by a passion for night photography.
07:10He's come to this waterfall in Iceland to capture a rare phenomenon of colour that can
07:17only be seen at night.
07:21A moonbow.
07:32The sun's photons make an extraordinary journey to reach this waterfall.
07:47Travelling 150 million kilometres through space, they bounce off the surface of the
07:52moon and finally rain down on Earth.
07:56Their hidden colours are revealed by the spray of the waterfall.
08:01Only if the conditions are right.
08:18But tonight, Stéphane is in luck.
08:31A moonbow is a beautiful riot of colour, produced by delicate moonbeams.
08:51Rarely seen, a faint echo of the sun's light.
09:01The colours are created as light is scattered by the fine water droplets at the foot of
09:24walls, which split the moonbeams into all the colours of the rainbow, revealing the
09:31sun's hidden splendour.
09:34This night-time bridge to the sky shows us that colour exists no matter the time of day.
09:43It's a feature of light itself.
09:52After a 150 million kilometre journey, the sun's photons reach our world.
10:01The photons of every wavelength interact with whatever lies in their path.
10:09Some will be invisibly absorbed when they strike the stuff of this planet.
10:16The land, the sea and the air we breathe.
10:21Other photons will be reflected into our eyes.
10:28And they are revealed to us as colour.
10:33The colours we see have meaning.
10:38They are a code that reveals what Earth is made of.
10:51Of all the colours of the rainbow, one in particular glows back out into space.
11:01The iconic blue of our planet's oceans.
11:06A colour caused by the unique way that light interacts with water.
11:13There are few better places to see why water is blue than this crevasse in Iceland.
11:22This is Þingvellir.
11:26A rent in the Earth.
11:30Caused by the planet's tectonic plates drifting apart.
11:37In places, the rift has, over time, become flooded.
11:51Professional diver Ted Wignall has been exploring this site for years.
11:57The water's clear because it's been filtering for a very long time
12:02through the lava, the rock, that we have here in Iceland.
12:07It comes from Langeokull, Iceland's second largest glacier.
12:13The water's clear because it's been filtering for a very long time
12:19through the lava, the rock, that we have here in Iceland.
12:25When you first descend, you almost lose your sense of distance.
12:29You think that you're shallow, you're actually very deep
12:33because you can just see for so far through the water.
12:37The purity of the water not only increases visibility,
12:41it also provides the perfect environment to understand why water is blue.
12:49When the sun's light hits the water,
12:53photons get absorbed.
12:57But not all at the same rate.
13:01Red photons get absorbed by the water first.
13:05The reason is down to the structure of water molecules themselves.
13:13A water molecule is made of one oxygen and two hydrogen atoms.
13:19When the light streams into the water,
13:23the red photons happen to have just the right energy
13:27to make the bonds between the atoms vibrate.
13:31And so the light energy of the red photons is absorbed.
13:39As Ted dives deeper, the energy of more red photons
13:43is soaked up in the vibration of the water molecule.
13:47As you descend, you see that the first colour to drop off is red.
13:51So my beautiful bright red suit here,
13:55very quickly as we descend, the colour begins to fade away.
14:01Orange, yellow and green photons
14:05don't have the perfect amount of energy to make water bonds vibrate.
14:12But eventually, even they will be absorbed.
14:16What happens is the red ebbs out and we're left with a sort of rusty colour.
14:22At this depth, only blue photons
14:26have survived their passage through the water.
14:34And that's why water looks blue.
14:38The unique way the sun's photons interact with water
14:42is also what drives one of the planet's greatest migrations.
14:48Because when water absorbs photons,
14:52the energy contained within them is also absorbed.
14:58And that's why the sun's photons interact with water.
15:02Because when water absorbs photons,
15:04the energy contained within them is also absorbed
15:08and converted into heat.
15:15Every spring, marine biologist Osvaldo Vasquez's research
15:20takes him out onto the high seas.
15:22Charlie, is that well from the port battle over?
15:25We are at 11 o'clock. I'm sorry, one, one, one.
15:28He's in search of these waters' largest and most iconic seasonal visitors.
15:34Right there, coming up.
15:38Oh, look at this. Amazing.
15:49Humpback whales.
15:51Every year, some 10,000 humpbacks make the long journey
15:55from their feeding grounds in the northern Atlantic
15:59to the striking blue waters of the Silver Bank Marine Reserve.
16:07This is the greatest nursery of humpback whales in the world.
16:1285% of the North Atlantic population comes here for breeding,
16:18mating and giving birth.
16:25So, from this place depends the survival of this species.
16:34The warm blue waters of the Dominican Republic
16:37are a haven for the mothers and their young calves.
16:42There you go.
16:43Osvaldo seizes the opportunity
16:45to get into the water and study their behaviour up close.
17:08There's one. There's a calf.
17:10Right there, right there.
17:15Up again.
17:17You saw it? Yeah.
17:28Good, that's good. Go left.
17:31We became part of this group now.
17:34From the bottom, it looks like a whale.
17:41Slow down. Slow down.
17:45OK.
18:01The reason the whales choose this one place to give birth
18:05is intimately linked to the process that makes the sea blue.
18:09When water molecules absorb
18:11all the different coloured photons of light,
18:14they also absorb their energy.
18:18Water turns colour energy back into heat,
18:22just what the whale calves need.
18:27Whales are warm-blood animals
18:30and when they give birth,
18:32they have a very skinny body,
18:35and when they give birth,
18:37they have a very skinny calf with no blubber.
18:46Silverbank's waters are exposed
18:49to the full power of the tropical sun.
18:55The sun's photons heat the water to a balmy 27 degrees Celsius.
19:01They need a warm environment, as they had inside the mother.
19:05So here, Silverbank, it's warm and it's protected,
19:09so it's suitable for giving birth.
19:14Mother and calf will only stay here
19:17in the tropical blue waters for a few months.
19:23The warmth created by water's interaction with photons
19:27is essential for the young calf.
19:31But once the calf has started to develop a layer of blubber,
19:35it will be time to leave.
19:39Mother and calf will start the long journey back
19:42to their feeding grounds,
19:44thousands of kilometres to the north,
19:47where the light of the sun is far weaker
19:50and the waters remain forbiddingly cold.
20:01The blue of the oceans covers 71% of the surface of the Earth...
20:11..giving our planet its distinctive colour from space...
20:17..flagging our world's abundance of life-giving water.
20:24But there's another distinctive colour on Earth's surface
20:28that signals life itself...
20:32..one which we all depend on.
20:37The green of plants.
20:40Earth is wrapped in a blanket of green
20:43produced by the pigment chlorophyll.
20:50Like all pigments, chlorophyll absorbs
20:52some of the sunlight's hidden colours and reflects others.
20:58But chlorophyll is extraordinary.
21:04It harvests the energy of red and blue photons
21:08and turns it into sugar.
21:18The green of chlorophyll creates food out of colour.
21:23But on the plains of the Serengeti in Africa,
21:26it's the dry season.
21:31It's been weeks since the last rains.
21:37The grass has been scorched brown
21:39by the glare of the intense African sun.
21:44The climate is changing.
21:48The climate is changing.
21:50Chlorophyll production has come to a halt.
21:56The grass has been drained of its life-sustaining colour.
22:03All that remains are the brown pigments
22:06of decaying cells and tannins.
22:11In the searing heat, the grass has turned to ash.
22:15Storing whatever nutrients it still has underground.
22:27And that is a problem.
22:31Because these are the homelands of the Maasai.
22:38The Maasai are the descendants of the Maasai.
22:41Herders who depend on their cattle to survive.
22:47For the Maasai, the dry season
22:49means months of hunger and hardship.
22:55Farakapuni, his son and brother,
22:58must say goodbye to their home valley
23:01and drive their cattle across the desiccated brown plains
23:05in search of enough grass and water
23:08to keep them alive.
23:33The Maasai are utterly dependent on their cattle
23:36for food.
23:44Cattle can use the sugars produced by green chlorophyll
23:47to fuel the production of meat and milk.
24:02At the end of their long journey,
24:04Maasai warriors from across the Serengeti
24:07gather on the banks of Lake Massek.
24:34Parakapuni's family's survival
24:36depends on them spending the dry season apart.
24:42While he tends the cattle,
24:44his wife Normaponi must stay behind
24:46to look after those too young or too old to make the trip.
24:54Without the cattle,
24:56the Maasai have no means of survival.
24:59Without the green grass to feed the cows,
25:02they must eke out an existence on the lifeless plains.
25:29With the cows away,
25:31Parakapuni's family must survive
25:34on a meagre diet of flour and water.
25:59After four long months apart,
26:02things are about to change.
26:29The coming of the rains
26:31triggers a dramatic transformation.
26:43Chlorophyll can start working again.
26:46And the plains are transformed into a vibrant green.
26:56Now, instead of the sun's light destroying the plants,
27:02the green grass and water
27:04can be used to create a new life.
27:07Now, instead of the sun's light destroying the plants,
27:12chlorophyll means grass can harness its energy once more
27:17in the process called photosynthesis.
27:24Each green blade of grass becomes a factory,
27:27taking some of the sun's light
27:29and using it to turn water and carbon dioxide into sugars.
27:33Sugars that can be used to build new chutes.
27:36Sugars that feed the cows.
27:54The greening of the Serengeti
27:56means a new life can be created.
27:59The greening of the Serengeti
28:01means Parakapuni can begin the long journey home.
28:29Music
28:59We are grateful to God.
29:06We are grateful to God.
29:08We are grateful to God.
29:14We are grateful to God.
29:16We are grateful to God.
29:23Parikapuni isn't the only one returning to the plains.
29:30The greening of the Serengeti brings with it immense herds of wildebeest.
29:38All life depends on the blanket of green plants that covers the earth.
29:47Chlorophyll fuels the food cycle of our planet.
29:53Thanks to the colour green, we all eat sunshine.
30:00While plants use sunlight to grow, we've evolved to use photons in a completely different way.
30:12To sense the world.
30:15Because vision is our primary sense.
30:21In fact, most creatures use light to perceive their environment.
30:29Many evolved the ability to detect the colours hidden in light.
30:39Being able to see colour made life able to use colour.
30:54Beneath the dense green canopy of Papua New Guinea
30:58live some of the most colourful creatures on the planet.
31:04Their colours carry important messages.
31:11Messages understood by both man and beast.
31:20Peter Kiap of the Anpang tribe dreams of knowing all the secrets of the forest.
31:28Peter is a hunter.
31:40To become a hunter, Peter has a lot to learn about life's language of colour.
31:52Precious knowledge that can only be passed on by the village elders.
31:58And Paulus Mulya, Peter's adopted grandfather, is the greatest hunter of them all.
32:18No one knows how old he is.
32:21But his skills have made him one of the most powerful and respected men in the village.
32:28Everything Peter wants for himself.
32:44Beyond the rich green of this forest, there are other colours to be found that convey meaning.
32:58The secret to Peter's success will be to know how to read the colours
33:05and ultimately exploit them.
33:08Red is particularly easy to spot against the abundant greenery.
33:14It's in the plants' interest for their fruit to be seen.
33:19It's a sign of the abundance of greenery.
33:24The plants lure in birds by making colourful fruits.
33:28Red is particularly easy to spot against the abundant greenery.
33:33It's in the plants' interest for their fruit to be seen.
33:37If the fruit gets eaten, its seeds get dispersed far and wide.
33:54Orange also stands out against green.
33:58In this jungle, there is a rare orange animal that uses its colour to signal danger.
34:08It's dangerous.
34:12It's dangerous.
34:15It's dangerous.
34:19It's dangerous.
34:22It's dangerous.
34:25It's dangerous.
34:31The hooded patui is one of the few poisonous birds in the world.
34:37Its bright orange feathers are an important announcement of the toxin they contain.
34:45Would-be predators quickly learn to associate the hooded patui's memorable colour with something to be wary of.
34:54So this unusual bird avoids becoming prey.
34:59Peter and Mulya are after an even more colourful prize.
35:04Birds of Paradise.
35:20Male birds of paradise have evolved bright, colourful feathers to attract a female.
35:25The colours signal that he is strong and healthy,
35:29that he has ample energy going spare and would make a good mate.
35:36And it's the colourful feathers that make the birds of paradise so prized by Peter and his tribe.
35:55It's the colourful feathers that make the birds of paradise so prized by Peter and his tribe.
36:26It's the colourful feathers that make the birds of paradise so prized by Peter and his tribe.
36:38Like the wildlife here, the local tribe's people use colour to communicate.
36:45The village is about to host a ceremony.
36:49It's important that Peter communicates the right message with his costume.
36:56Particularly to the opposite sex.
37:13Time, however, is not on Peter's side.
37:19Birds of paradise are only active for a couple of hours each day.
37:25If one does appear, he must try to remain absolutely silent.
37:55Birds of Paradise
38:19Peter comes back empty-handed and must turn to Mulya for help.
38:25Mulya, the leader of the tribe, helps Peter.
38:30When you were young, what did you do for a living?
38:37I was a farmer.
38:40I was a farmer, but I had no money.
38:44I had no money.
38:47Oh, I see.
38:49I had no money.
38:56As the village gathers for today's ceremony,
39:00plenty of time is devoted to dressing up and looking good.
39:10Sporting Mulya's gift in his headdress,
39:14Peter hopes it will help him attract some welcome attention.
39:17I love the temple.
39:21I want to go to the temple and pray there every day.
39:25I want to be a good farmer too.
39:29I want to plant lots of flowers there.
39:35Thanks to evolution,
39:38the natural world has dressed itself in myriad colours.
39:41The natural world has dressed itself in myriad colours.
39:47And so have we.
40:06Colour has provided us with a precious gift.
40:12A way to understand the world and succeed within it.
40:17However, we humans have also developed the capacity
40:20to sense something deeper in colour.
40:25And as we look around us,
40:28we see not just colour, but beauty.
40:36We need to get ready to go, don't we?
40:39Push!
40:42For eight years, the Nation family have been consumed by an obsession.
40:49So, 73, 98, 97.
40:5269, 98, 100.
40:56They've left their home on the south-east coast of England
40:59to live in the cold climes of northern Norway.
41:05Spending their weekends chasing the planet's most extraordinary
41:09and colourful phenomena.
41:12The northern lights, or the aurora borealis.
41:21It's an addiction, it's an absolute full-blown addiction.
41:24It's a buzz and it's a rush of adrenaline
41:27and it's a holding of your breath and...
41:29Wow.
41:31The aurora borealis is a light show like no other.
41:37Let's see if I can find a corona.
41:39You get this purple or pink in the centre,
41:42then the green comes out of the purple
41:44and then the white part that you can see is where it almost overexposes
41:48and that's the part that tends to move very quick.
41:53Our eldest aurora, she's 11, she's fascinated by
41:56why do those different gases make those different colours.
42:00Oshie, she likes the pink because she likes pink,
42:02it's her favourite colour.
42:04And Lyrica is quite a fact.
42:06She can explain to you what causes an aurora,
42:08where it comes from, the technical names,
42:11and, you know, what the magnetic field does
42:13and how it stops the solar wind from harming us.
42:18The aurora's ethereal colours are created
42:21when energetic particles from the sun
42:24interact with the Earth's upper atmosphere.
42:30When the aurora's colours are created,
42:34when they strike gas atoms,
42:36the energy makes those atoms vibrate
42:39and photons of light are released
42:42to dance across the dark night sky.
42:46However, the aurora can be elusive.
42:49To see it from Earth, conditions have to be just right.
42:55Part of the fun is succeeding against the odds
42:58and we've gone out in weather like this
43:01and then it's suddenly cleared
43:03and then the skies have suddenly opened up.
43:13Shall we go and play in a snowbank?
43:18To give themselves the best chance,
43:21the family pick a spot and set up camp under the stars.
43:25That's not a bad fire, is it?
43:27That's on the flame.
43:30Mum, are you going to burn it?
43:40They wait, sometimes for hours.
43:51The chances of seeing the aurora borealis
43:54are greater up here within the Arctic Circle
43:57because the charged particles streaming out from the sun
44:01are drawn towards the magnetic North Pole.
44:08Oh, oh, oh, oh, I can see some uprights there.
44:27There we go, look at it.
44:31Beautiful, look at it.
44:37Look how bright that is up there, look.
44:48Yeah, yes!
44:51Now that's what I'm talking about.
44:55Look!
44:56Oooh!
45:00Look, look, look, look, look, look, look.
45:02Corona, corona!
45:05Look at it.
45:08Stunning.
45:09Wow.
45:15Oh, oh, oh!
45:17It's so much better.
45:20And on the left, on the left, look, there's some pinks.
45:22Yeah, it's going to do corona, look, look, look, look, look.
45:35But the aurora isn't simply beautiful.
45:41The colours are a code to the physical world
45:44because they reveal the chemistry of our skies.
45:52Each chemical element is unique
45:55and each one gives off photons of a particular colour.
46:04The green comes from oxygen atoms, purple from nitrogen.
46:16The light shimmering across the sky
46:19reveals the oxygen and nitrogen-rich atmosphere
46:22that envelops our planet.
46:27This kind of coloured light doesn't only tell us about our world.
46:32It has also shown us the universe.
46:45The universe is unimaginably vast
46:48but light travels freely to us from its furthest reaches
46:53and when it arrives, it brings with it colours
46:56that are the chemical signatures of the cosmos.
47:02These are the vast clouds of a nebula,
47:05a star nursery heated up by a young star.
47:12They shine a deep pink.
47:15This is the colour of hydrogen,
47:17the gas that fuels the stars.
47:25Across the universe,
47:27pink clouds declare the abundance of hydrogen in the cosmos.
47:33Reading the colours of light travelling across the universe
47:36may reveal the answer to an eternal question.
47:40Are we alone?
47:45Is the presence of life here on Earth unique?
47:52It's a question that can only be answered
47:55by finding a planet that has just the right conditions.
48:00Like ours.
48:02As astronomers gaze out from the edges of our home planet,
48:05they explore distant worlds
48:07by analysing the colours in the light that shines from them.
48:24This planet is 42 light-years away.
48:28Yet from the light bouncing off the Earth's surface
48:31we know it's covered in swirling clouds.
48:38Alien photons crossing light-years of space to our telescopes
48:42are carrying stories of different worlds.
48:51Most astronomers believe it's only a matter of time
48:54before we discover a planet
48:56most astronomers believe it's only a matter of time
48:59before we discover a planet able to host life.
49:11Thanks to colour, one day we may find another Earth.
49:18Another potential home just as vibrant and colourful as our own.
49:26Transcribed by ESO, translated by —
49:56Transcribed by ESO, translated by —