[pensive music playing]
[Freeman] Nightfall…
reveals our planet's connection to the universe.
[whooshing]
A shooting star.
Ancient rock from the depths of space…
falling to Earth.
Inside it are the chemical elements that built our universe.
[pensive music continues]
[ethereal tinkling]
For countless generations,
sea turtles have roamed the oceans,
gathering cosmic elements in the food they eat.
And as they've done for hundreds of millions of years…
every new generation
recycles this same stardust…
to produce the next.
-[fire roaring] -[majestic music playing]
Born in The Big Bang…
[whooshing]
…and forged in the hearts of stars…
[whooshing, exploding]
…90 chemical elements have created everything.
Endlessly recycled and reconfigured
throughout the entire history of the universe.
[whooshing]
And now…
using the same elements,
each new turtle begins a life cycle…
-[zapping] -[majestic music crescendos]
…that mirrors the lives of the stars.
[dramatic music playing]
[calm music playing]
[bird squawking]
[Freeman] On Australia's Great Barrier Reef…
[squawking continues]
…something magical has happened.
[calm music continues]
After 50 days beneath the sand,
chemical elements from across the cosmos have created life.
Combining to form the next generation
of green sea turtles.
[egg rustling]
[calm music continues]
[egg cracking]
The eggs have now exhausted their supply of life-giving elements.
[calm music continues]
And today, the baby turtles will take their first taste of air.
And as her brothers and sisters scramble to make it to the water…
a little female…
is last to be born.
In order to grow to adulthood,
she will need to harvest chemical elements from across the ocean.
It's a dangerous journey…
[ominous music playing]
…with treachery at every turn.
[bird squawking]
But for the baby turtles,
the call of the ocean is irresistible.
[birds squawking loudly]
[ominous music continues]
From a nest of 100,
sometimes only one will survive.
Sometimes none.
[birds continue squawking]
[suspenseful music playing]
But despite the risk,
the little female knows
she must make it to the water.
[birds squawking]
[suspenseful music continues]
[birds continue squawking]
[suspenseful music continues]
She spots an opening…
and takes her chance.
[pensive music playing]
Today…
she's a lucky one.
The hatchling won't stop swimming until she has left the reef far behind.
[pensive music continues]
Safely past the predators that gather in the shallow coastal waters,
she'll disappear into the great void of the open ocean…
to spend her childhood feeding on atoms.
[whooshing, zapping]
Atoms whose origins go back through the entire life of the cosmos.
[energetic rock music playing]
[whooshing]
To the time our universe
was in its infancy.
[pulsing]
[whooshing]
Expanding from nothing to everything in an instant.
Our universe was born in The Big Bang.
[calm music playing]
At first,
it was nothing but a hot, dense fog.
[wind howling]
But as it continued to expand…
the fog began to cool.
And on the tiniest scale imaginable…
[zapping]
…something astounding began to occur.
[pulsing]
[uplifting music playing]
The first atoms condensed out of the fog.
[zapping]
Atoms of hydrogen.
[high-pitched squeaking]
The very first element in the universe.
[uplifting music continues]
And in the ocean,
juvenile turtles are hunting it down.
As they emerge from the blue
to forage in the shallow waters of the reef.
This is Stella.
One of the lucky ones that made it off the beach
and into the ocean.
[pensive music playing]
She's already more than 2,000 times her hatching weight
and growing fast.
Feeding on creatures she's found drifting in the open ocean,
she's harvested one element more than any other.
[majestic music playing]
Hydrogen.
It makes up more than half of all the atoms in the food she eats.
And is the most abundant element in all living things.
From fish
to invertebrates.
Anemones and coral.
Hydrogen atoms formed at the dawn of the universe
have been passed on from star to planet,
planet to animal…
and from prey to predator.
[Stella exhales sharply]
Which means, for Stella,
the waters around the reef are full of danger.
[suspenseful music playing]
Tiger sharks, hungry for the same atoms,
hunt sea turtles throughout their adult lives.
Stella's main defense is her trusty armor.
Its bone toughened with calcium and phosphorus.
[suspenseful music continues]
Elements that date back to another pivotal moment…
in the life of our universe.
[ethereal music playing]
For the first 300 million years after The Big Bang…
there are no planets and no stars.
The dark ages of the universe.
[ominous music playing]
Concealed in the gloom,
vast tendrils of hydrogen gas crisscross the cosmos.
And then, incredibly,
as they were drawn together by gravity…
[roaring]
…the first stars were born.
[zapping]
This is the cosmic dawn.
[ethereal music playing]
The moment the lights came on.
[buzzing]
[crackling]
And deep within those first stars…
a remarkable process began.
[ethereal music continues]
[pulsing]
Temperatures and pressures were so extreme…
[whooshing]
…that new elements were created.
Atoms of hydrogen were forced together to make helium.
As they fused, energy was released.
[zapping]
Creating a chain reaction that produced increasingly heavier elements.
[pulsing]
Including those essential for life.
[zapping]
Three helium atoms combined to make carbon.
[dramatic music playing]
The element on which all life is based.
Carbon and helium made oxygen.
The air we breathe.
[intriguing music playing]
Oxygen atoms combined to make phosphorus.
Then silicon and calcium.
[zapping]
The elements that make up every living thing
were created in the hearts of the very first stars.
[dramatic music playing]
[penguins chirping]
[elephant huffing]
[dramatic music crescendos]
For Stella,
some elements are so important…
[pensive music playing]
…she'll travel great distances to find them.
The warm, shallow waters between Australia and Papua New Guinea
are a paradise of vibrant seagrass.
[intriguing music playing]
The prairies of the ocean.
Stella has traveled all the way here to access their magic ingredients.
[whooshing]
As it grows,
seagrass absorbs elements from outer space
that have found their way to the ocean floor.
Burgeoning fronds rich in calcium and phosphorus
provide Stella with precisely the minerals she needs
to build and sustain her protective shell.
[intriguing music continues]
Hardening her armor for the trials ahead.
Stella will spend her adolescent years
searching the ocean
for atoms born in the stars.
[intriguing music swells]
Her journey toward maturity…
paralleled in the story of our universe.
[whooshing]
Because three billion years after The Big Bang…
[ethereal music playing]
…the universe was also coming of age.
It was entering an incredibly active phase of star formation.
[pulsing]
As they grew,
stars were pulled together into vast galaxies.
Like our Milky Way.
[dramatic music playing]
And within those galaxies,
the chemical elements each star produced…
[whooshing]
…were transformed into planets and moons.
[dramatic music continues]
After billions of years,
chemical elements have matured into the Earth we know today.
Stella is now fully grown herself.
[ethereal music playing]
Over a meter long,
she has a thick shell covered in green algae.
Ideal camouflage for cruising coral reefs.
She is now at one with the ocean.
Atoms from the stars
perfectly adapted to life at sea.
[ethereal music continues]
Just one example of life on Earth…
exquisitely shaped from the cosmos.
Stella is now ready for the next stage of her life.
[ethereal music continues]
Because she's about to become a mother herself.
Inside her body…
she's carrying a clutch of 100 eggs.
The first of many she'll have over her lifetime.
Her own precious cargo of stardust.
All across the reef,
atoms are being assembled into new life.
Creating one of the richest ecosystems on Earth.
But our planet…
[whooshing]
…is an outlier.
In the rest of the solar system,
the very same elements
have created worlds far less suited to life.
[whooshing]
[eerie music playing]
Closest to the sun,
Mercury is a planet rich in carbon.
[fizzling]
But rather than creating life,
the carbon is baked into its crust.
On a world scorched by starlight.
[whooshing]
While in the farthest reaches of the solar system,
Neptune's freezing temperatures
cause carbon and hydrogen to form clouds of methane.
[wind gusting]
The suffocating gas that gives it its brilliant blue.
[whooshing]
And even on Mars,
a planet with all the same ingredients as Earth…
the lack of an oxygen-rich atmosphere
means complex life couldn't survive here.
[eerie music continues]
Only on Earth are conditions just right.
But even here,
competition for elements is fierce.
And danger…
[ominous music playing]
…is never far away.
Luckily, Stella has become an expert at hide-and-seek.
[ominous music continues]
[ominous music intensifies]
[calm music playing]
Safe for now…
Stella faces the biggest challenge of her life.
To return to the Great Barrier Reef
and the island of her birth…
to lay her own eggs in the sand.
But a lifetime spent wandering the ocean
means she's now 2,000 kilometers away.
[calm music continues]
How Stella navigates home
is one of the wonders of the natural world.
[humming]
Deep within the Earth,
our planet's core generates a magnetic field…
which gives every place on its surface a unique magnetic signature.
[intriguing music playing]
When she hatched,
her island's signature was imprinted in Stella's brain.
And to find her way back,
she'll rely on yet another chemical element.
One that connects her to the planet's core.
An element that's only created when stars die.
[ethereal music playing]
In a nearby part of the galaxy,
two and a half million years ago,
a dramatic change took place in the core of a giant star.
[hissing]
For all its life, it had been powered by nuclear fusion.
[pulsing]
The energy released…
[zapping]
…creating heavier and heavier elements.
[whooshing]
Until the core became so hot,
it started creating…
[whooshing, zapping]
…iron.
Which caused a fundamental change to take place.
[whooshing, zapping]
Because making iron doesn't release energy.
It consumes it.
[cracking]
As more and more of the metal was produced,
it spread through the core like a disease.
Feeding off the star's heat.
[cracking rapidly]
Throttling it.
[ethereal music continues]
[cracking continues]
With no heat source to hold it up.
[gurgling]
From this moment onward…
[ethereal tinkling]
…the star was doomed.
[rumbling]
[booming, ringing]
The resulting explosion shone with the brightness of 10 billion suns.
[whooshing, zapping]
[rumbling]
A supernova which propelled iron-rich dust across the galaxy.
[wind whipping]
[ethereal music playing]
All the way to our planet.
And even now,
100 tons of stardust enters Earth's atmosphere every day.
Some left over from the formation of the solar system.
[ethereal tinkling]
Some blown here from distant supernovas.
A direct link between our planet and the stars.
[ethereal music continues]
And it's the iron in this dust
that allows Stella to find her way.
[ethereal tinkling]
Because deep in her brain…
[whooshing]
[pulsing]
…specialized cells are thought to contain crystals of magnetite.
An iron-rich mineral that aligns itself to the Earth's magnetic field.
[intriguing music playing]
A compass,
pointing her in the right direction.
Allowing Stella to find the unique magnetic fingerprint of home.
[intriguing music continues]
And so an element forged in a supernova…
[ethereal music playing]
…will now guide her across kilometers of featureless ocean.
Back to the island…
on which she was born.
But there are other creatures with magnetic homing abilities.
[ominous music playing]
The tiger sharks have it too.
And it's leading them back to the same island.
Because for a few months every year,
thousands of female turtles come here to lay their eggs.
It's the largest gathering of green sea turtles
anywhere on the planet.
[ominous music continues]
And as they come to shore,
the feeding begins.
[ominous music crescendos]
[tense music playing]
Stella must wait for the right moment…
to find an opening…
and avoid the onslaught.
[tense music continues]
[calm music playing]
[birds squawking]
When the danger has passed…
she finally swims ashore.
[triumphant music playing]
After an epic journey…
Stella emerges onto the sand
she last touched as a hatchling.
[triumphant music continues]
The elements she spent a lifetime collecting…
are now safely delivered into the sand.
Stella's mission is complete,
and she returns to the ocean…
to begin gathering stardust once more.
The cycle of her life
mirroring the grandest cycle of all.
The lives and deaths of the stars.
[ethereal music playing]
Because far away across the galaxy,
the ashes of countless supernovas
have come together to form a giant nebula.
[ethereal tinkling]
A cloud of stardust tens of light-years across.
And buried within it are places where the next generation of stars
are beginning to form.
[ethereal music continues]
Called proplyds.
They're like vast cosmic eggs.
Each one bigger than our solar system.
Inside their shells of ionized gas,
the force of gravity is pulling stardust together.
[whooshing]
And the stardust inside Stella's eggs…
is also beginning to take shape.
[ethereal music continues]
[heartbeat thumping]
As the elements she collected are being transformed…
into something that's starting to resemble a tiny creature.
[dramatic music playing]
And within the proplyd…
gases like hydrogen and helium…
[rumbling]
…are feeding an embryonic star.
[dramatic music continues]
And what was once an embryo…
is now a tiny turtle…
with shell, flippers, and beak.
Elements reimagined…
for a life at sea.
[heartbeat thumping]
In the proplyd,
the new star's development is also nearing completion.
Reborn from the ashes of the previous generation,
its light now reveals a family of growing planets in orbit.
New worlds.
But perhaps, new possibilities for life.
[dramatic music continues]
And beneath the sand,
the same stardust,
passed down through countless generations of stars and turtles…
will start yet another journey.
[egg cracking]
Each new life
directly connected to the origin of the universe.
[dramatic music crescendos]
Each new story beginning at the end of the last.
-[thunder rumbling] -[lightning zapping]
And so, the story of our universe continues…
[ethereal tinkling]
…with Earth's most precious resource…
[ethereal music playing]
…water.
And a family of elephants on a dangerous mission to find it.
[elephant huffing]
Their journey every bit as extraordinary…
[lion growls]
…as water's journey across the vastness of space to our planet.
But why is Earth the only world in the solar system
whose surface is covered with liquid water?
And why is it so essential for life?
[elephant trumpets]
[dramatic music playing]