Forces Of Nature - S1.E4 - The Pale Blue Dot
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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.
28:29The park is producing
28:32new water for the Serengeti River basin.
28:41The water from the Serengeti
28:44is on the way to Parakapuni.
28:46I'm very happy to be here
28:48and I'm going to pray for all.
28:50I'm very happy to see
28:52that God has blessed us.
28:54This is why I'm very happy
28:56I am very happy and I keep praying.
28:59I keep thanking God.
29:06May we all continue to live in peace and harmony.
29:14This is God's will and He will continue to bless us.
29:18Thank you, God.
29:48Sunlight controls the food cycle of our planet.
29:54Thanks to the colour green, we all eat sunshine.
30:03While plants use sunlight to grow,
30:06we've evolved to use photons in a completely different way...
30:15..to sense the world.
30:18Sensation is our primary sense.
30:24In fact, most creatures use light to perceive their environment.
30:30Many evolved the ability to detect the colours hidden in light.
30:40Being able to see colour made life able to use colour.
30:49Beneath the dense green canopy of Papua New Guinea
30:53live some of the most colourful creatures on the planet.
31:00Their colours carry important messages.
31:07Messages understood by both man and beast.
31:12Peter Kiap of the Anpang tribe
31:14dreams of knowing all the secrets of the forest.
31:27To become a good hunter,
31:29you need to know the secrets of the forest.
31:36To become a hunter,
31:38Peter has a lot to learn about life's language of colour.
31:48Precious knowledge that can only be passed on by the village elders.
31:56And Paulus Mulya, Peter's adopted grandfather,
31:59is the greatest hunter of them all.
32:09He is the oldest hunter in the village.
32:18No-one knows how old he is.
32:22But his skills have made him one of the most powerful
32:25and respected men in the village.
32:29Everything Peter wants for himself.
32:39Beyond the rich green of this forest,
32:42there are other colours to be found that convey meaning.
32:53The secret to Peter's success
32:55will be to know how to read the colours
33:00and ultimately exploit them.
33:08The secret to Peter's success
33:11will be to know how to read the colours
33:14and ultimately exploit them.
33:24Plants lure in birds by making colourful fruits.
33:28Red is particularly easy to spot against the abundant greenery.
33:34It's in the plant's 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
34:01that uses its colour to signal danger.
34:08It's a very dangerous bird.
34:11It's dangerous.
34:14It's a very dangerous bird.
34:16If you see it, you have to run away.
34:19If you see it, you have to run away.
34:22The birds are very dangerous.
34:25They are dangerous.
34:31The hooded patui is one of the few poisonous birds in the world.
34:38Its bright orange feathers
34:40are an important announcement of the toxin they contain.
34:46Would-be predators quickly learn to associate
34:49the hooded patui's memorable colour with something to be wary of.
34:55So this unusual bird avoids becoming prey.
34:59Peter and Mulya are after an even more colourful prize,
35:03birds of paradise.
35:20Male birds of paradise have evolved bright, colourful feathers
35:24to attract a female.
35:26The 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
35:38that make the birds of paradise so prized by Peter and his tribe.
35:56The colourful feathers make the birds of paradise so prized by Peter and his tribe.
36:27Like the wildlife here,
36:29the local tribe's people use colour to communicate.
36:34The village is about to host a ceremony.
36:39It's important that Peter communicates the right message with his costume.
36:57Particularly to the opposite sex.
37:14Time, however, is not on Peter's side.
37:20Birds of paradise are only active for a couple of hours each day.
37:26If one does appear, he must try to remain absolutely silent.
37:56SILENT
38:20Peter comes back empty-handed and must turn to Mulya for help.
38:26MULYA
38:57As the village gathers for today's ceremony,
39:01plenty of time is devoted to dressing up and looking good.
39:12Sporting Mulya's gift in his headdress,
39:15Peter hopes it will help him attract some welcome attention.
39:27PETER
39:39Thanks to evolution,
39:41the natural world has dressed itself in myriad colours.
39:47And so have we.
39:56COLOUR
40:06Colour has provided us with a precious gift.
40:11A way to understand the world and succeed within it.
40:16However, we humans have also developed the capacity
40:19to sense something deeper in colour.
40:23And as we look around us,
40:26we see not just colour, but beauty.
40:34We need to get ready to go, don't we?
40:37Push!
40:42For eight years, the Nation family have been consumed by an obsession.
40:48So, 73, 98, 97.
40:5169, 98, 100.
40:54They've left their home on the south-east coast of England
40:58to live in the cold climes of northern Norway.
41:03Spending their weekends
41:05chasing the planet's most extraordinary and colourful phenomenon.
41:11The Northern Lights, or the Aurora Borealis.
41:18It's an addiction. It's an absolute full-blown addiction.
41:22It's a buzz and it's a rush of adrenaline
41:25and it's a holding of your breath and...
41:28Wow!
41:30The Aurora Borealis is a light show like no other.
41:35Let's see if I can find a corona.
41:37OK, this is like... This is a corona.
41:39You get this purple or pink in the centre,
41:42then the green comes out.
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.
41:52Our eldest Aurora, she's 11, she's fascinated by
41:56why do those different gases make those different colours.
41:59Oshie, she likes the pink because she likes pink.
42:02It's her favourite colour.
42:04And Lyrica is quite a fact box on everything.
42:07She can explain to you what causes an aurora,
42:10where it comes from, what causes it,
42:12what causes an aurora, where it comes from, the technical names
42:16and what the magnetic field does
42:18and how it stops the solar wind from harming us.
42:23The aurora's ethereal colours are created
42:26when energetic particles from the sun
42:29interact with the Earth's upper atmosphere.
42:35When they strike gas atoms, the energy makes those atoms vibrate
42:40and photons of light are released to dance across the dark night sky.
42:47However, the aurora can be elusive.
42:50To see it from Earth, conditions have to be just right.
42:56Part of the fun is succeeding against the odds
42:59and we've gone out in weather like this
43:02and then it's suddenly cleared and then the skies have suddenly opened up.
43:11SHE LAUGHS
43:13Shall we go and build a snowman?
43:15SHE SCREAMS
43:19To 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.
43:29Are you going to burn it?
43:34Careful, Louis.
43:36Don't lean too far forward.
43:40They wait.
43:42Sometimes for hours.
43:44That's the hottest part.
43:46Is it?
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.
44:05Ooh. Ooh, ooh, ooh.
44:07I can see some uprights there.
44:24There we go. Look at it.
44:28Beautiful.
44:30Look at it.
44:32Look how bright that is up there. Look.
44:42SHE LAUGHS
44:45Yeah! Yes!
44:47SHE LAUGHS
44:49Now that's what I'm talking about.
44:53Look. Ooh.
44:58Look, look, look, look.
45:00Look, look, look, look.
45:02Corona, corona.
45:05Look at it.
45:08Stunning. Wow.
45:15Oh, oh, oh.
45:17It's so much better.
45:19SHE LAUGHS
45:21And on the left, on the left, look, there's some pinks.
45:24Yeah, it's going to do a corona.
45:26SHE LAUGHS
45:31Ooh!
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.
46:01The green comes from oxygen atoms,
46:05purple from nitrogen.
46:15The light shimmering across the sky
46:18reveals the oxygen and nitrogen-rich atmosphere
46:21that envelops our planet.
46:26This kind of coloured light
46:28doesn't only tell us about our world,
46:31it has also shown us the universe.
46:44The universe is unimaginably vast,
46:47but light travels freely to us from its furthest reaches.
46:51And when it arrives,
46:53it brings with it colours
46:55that 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.
47:11They shine a deep pink.
47:14This 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
47:37may reveal the answer to an eternal question.
47:45Are we alone?
47:49Is the presence of life here on Earth unique?
47:56It's a question that can only be answered
47:58by finding a planet that has just the right conditions.
48:04Like ours.
48:06As astronomers gaze out from the edges of our home planet,
48:11they explore distant worlds
48:13by analysing the colours in the light that shines from them.
48:26This planet is 42 light-years away.
48:31Yet from the light bouncing off it,
48:33we know it's covered in swirling clouds.
48:40Alien photons crossing light-years of space to our telescopes
48:45are carrying stories of different worlds.
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,
49:20just as vibrant and colourful as our own.
49:25Transcribed by ESO, translated by —
49:55Transcribed by ESO, translated by —