Every year for just a few short months…
…fresh water flows into the Okavango Delta…
creating the perfect home…
for a small family of elephants…
and a playground for their two young calves…
Bosigo…
…and her baby cousin, Metsi.
Bosigo and Metsi are only just beginning
their love affair with water.
But from now on,
their lives will be defined by it.
This one precious molecule…
…delivered to Earth…
…by the astonishing forces at work in our universe.
It has transformed this planet…
…into a haven…
…for life.
Summer has arrived.
And what was paradise is no more.
The fresh water that flooded the delta…
only stays for a few months.
And water holes are now vanishing.
Fast.
This means only one thing
for the thousands of elephants who've been living here.
It's time to move on.
This has been the only home Metsi and Bosigo have ever known.
But in a few weeks, all the water will be gone.
So they must leave the delta with the rest of their family.
A herd of females,
sisters, aunts, and cousins,
led by their grandmother,
the great matriarch, Pula.
They're embarking on a journey along with thousands of other families…
out into the desert…
in search of water.
For the next eight months,
they will migrate from water hole to water hole…
and navigate ancient elephant trails…
…using the matriarch Pula's knowledge,
handed down to her through generations.
The trek will put all their lives at risk.
And they'll need every one of their exceptional senses…
-…to endure the dangers.
Making this journey is not a choice.
Without water, they will die.
Even on our blue planet,
fresh liquid water is scarce.
And if we search beyond the shores of our own planet…
it's rarer still.
Even the most arid desert on Earth
is nothing compared to the rest of our solar system.
In the cold outer reaches…
…the only surface water is ice.
Like Saturn's frozen moons…
where fountains of ice
shoot kilometers into space.
Closer to the Sun on Mars,
water is stripped away by savage solar winds.
And on Venus,
it simply boils away.
There's only one world we know of
that has the gift of liquid water on its surface.
A pale blue dot.
Our home…
where right now,
water is driving one particular family
on a quest for survival.
Just a month after leaving the delta,
only a scattering of muddy pools remain.
And they're getting fewer and farther apart each day.
Pula is using her highly tuned memory to lead her family to a water hole.
She can remember the exact route,
even decades later.
It's been a long day's march,
and all of them are desperate for a drink.
But so are the other 130,000 elephants
that live in Botswana.
The dry season has drawn herds from far and wide…
…to this water hole.
All competing for the same shrinking resource.
The adults teach the young ones clever survival tricks,
like how to skim a muddy pool to get the freshest water.
And how to use some muddy water as refreshing sunscreen.
Their wrinkly skin is perfect for trapping water and keeping cool.
But Metsi and Bosigo are also learning…
mud pools aren't just a place to drink.
They're water parks too.
With so many thirsty elephants,
the water hole has been drained.
Pula's family must press on…
and try to make it to the next water hole before the blazing sun *s it dry.
This battle between sun and scorched earth
has raged ever since our world was born…
when our blue planet was anything but blue.
Four and a half billion years ago…
Earth was in its infancy.
A fireball of molten rock…
…destined to become a dry, barren world.
But millions of kilometers out in the coldest reaches
of the solar system…
water crystals were forming
on the surface of dust particles.
Over time, these grains of dust clumped together into asteroids.
Millions and millions of them.
And these became the asteroid belt.
A vast expanse of icy rocks.
Yet they've laid tantalizingly out of Earth's reach.
As luck would have it, however,
a giant was on the move.
Young Jupiter.
A monster of a planet.
Forces within the turbulent inner solar system
were slowly pulling it in toward the Sun.
A flight path that brought it into a collision course
with the asteroid belt.
As it thundered through the asteroids…
…its massive gravitational force
flung rocks in every direction.
And yet, from all this chaos and destruction
came the ultimate cosmic gift.
Icy, water-rich rocks were hurled towards the Earth…
…bringing the promise of life one step closer.
Over billions of years,
asteroids were woven into the fabric of Earth as it formed.
Caught in the turmoil wrought by Jupiter…
…driven deep into the Earth by asteroids,
water molecules did not have an easy journey getting here.
And they still had a long way to go,
imprisoned for millions of years,
locked within Earth's molten core…
waiting for another miracle…
to set them free.
Today, much of Earth's water is still trapped underground.
So elephants have evolved special skills
to find it.
Even the muddy pools are empty.
This dry season has become a full-on drought.
But Pula has a superpower.
Her incredible trunk,
packed with millions of sense receptors…
can smell water from kilometers away…
and pinpoint its sources deep underground.
But you have to dig for it.
Metsi isn't a big digger.
But Bosigo is a natural.
And Metsi is offered a seat at the bar.
These few sips won't last them long.
But if water had stayed trapped in the Earth,
there would be none to drink.
There would be no elephants.
No life at all.
After water was delivered here by asteroids
and consumed by the Earth…
it was locked into the rock as crystals
deep inside the planet.
It stayed buried for millions of years,
beneath a vast sea of magma.
Until slowly but surely, Earth cooled.
And its surface hardened to a thick crust.
Then, finally, the boiling interior broke through.
Enormous volcanoes
blasted gas and vapor kilometers into the sky.
At last, water molecules…
…were set free…
…and formed the first clouds.
Growing and building for millions of years,
becoming laden with water…
…until the temperature dropped just enough…
…for the very first raindrop…
…to form and fall.
What followed was a deluge…
that lasted thousands of years.
Puddles turned into rivers.
Lakes…
…became seas.
And great oceans flooded Earth's surface.
And here, water gave rise to something magical.
The first life.
From these first cells
sprang every living thing.
Water is the fundamental ingredient
of every cell of every creature on Earth.
And today…
the herd still carries this ancient water within them.
It transports nutrients and oxygen.
It powers every heartbeat.
And drives every breath.
Life evolved because of water,
which is why no life can survive without it.
In Botswana, the drought is only getting worse.
The elephants' world is on fire.
The herd manages to escape the burning forest…
but walks straight into a new threat.
In this drought, everyone is suffering…
…from thirst and hunger.
And for lions, baby elephants would satisfy both.
The adults rally around Metsi and Bosigo.
It's enough to keep the threat at bay.
But lions are patient creatures.
And the herd still has to cross an unforgiving wasteland…
before the next water hole.
They need a lifeline.
And the Earth provides it
in the most unexpected of places.
The acacia tree is a beacon of hope.
And a haven for creatures of all kinds.
Its long roots reach much deeper underground
than an elephant could ever dig…
…drawing water up to its branches…
and leaves.
It's just enough water to keep them going.
Especially vital for Metsi's mother,
still nursing her baby.
But this is so much more than just a local oasis.
It's the vital link in water's eternal cycle.
The acacia tree connects ground and sky…
…breathing oxygen and vapor into the air.
Feeding clouds
and powering water's journey around the planet.
Ever since rain
fed the first green shoots…
and gave life to the first tree…
…plants have made our planet habitable…
…bringing a once barren ball of rock
to life.
But the gifts our universe bestows
can also be taken away.
A long time ago,
there was another planet
whose surface was covered in liquid water.
A water world just like ours.
The same forces that delivered water to Earth
also gave it to Mars.
With an atmosphere in place,
clouds formed,
rain fell,
rivers flowed.
And an ocean surged across its surface.
It was a world of possibility.
It had the potential for life.
But it didn't last.
Because not far away was a raging nuclear inferno.
Our Sun.
It unleashes torrents of high-energy particles
so powerful and deadly…
…they can devastate planets.
This solar wind streams through space…
at 400 kilometers per second.
And it ripped through the Martian atmosphere,
tearing water molecules apart.
Bit by bit,
over millions of years,
the planet's protective layer was stripped away by the Sun's fury…
…until its ocean evaporated…
and its water was lost to space.
Mars became a desolate, frozen shadow
of its former self.
Consumed by dust storms.
Any chance of complex life…
gone forever.
This could have been our story too.
But somehow, on Earth,
water and life have found a way to cling on.
In Botswana,
after 200 days in the burning sun…
…there is no water to be found.
Violent winds whip the scorched earth
into a dust bowl.
And the elephants' struggle hasn't gone unnoticed.
In daylight, adults can usually protect their young.
But when night falls…
…it's a different story.
Lions are masters of chaos and confusion.
They pick the most vulnerable target…
…working as a pack…
…until there's nowhere left to run.
Without the entire herd as protection,
the lions overwhelm their prey.
The drought and endless search for food and water
have taken their ultimate toll on Bosigo.
Elephants form deep emotional bonds.
All the family mourn Bosigo's loss.
The herd gathers to comfort Metsi,
who feels it hardest of all.
The never-ending fight to survive
plays out every year,
across the Okavango…
across our planet…
and beyond.
But in this battle for survival,
Earth got truly lucky…
with a secret guardian that protects it.
Deep within…
…the planet's raging molten furnace burns
and churns…
…generating a powerful magnetic field
that extends from the heart of the planet…
…65,000 kilometers out towards the Sun.
A vital force field defending Earth…
…from the same savage solar winds
that stripped water from Mars.
Defeating them before they hit our atmosphere.
Safeguarding our essential water.
Hugging every drop close to our planet.
This is what makes our pale blue dot
unlike anywhere else.
A place where life can thrive.
Bringing relief to the elephants.
Ensuring rains return each year without fail.
In the distance, storm clouds are building.
Elephants can detect the low-frequency rumble of thunder
from 240 kilometers away.
And it's telling them it's time to return to the Okavango.
From the highlands of Angola,
water is weaving its way through Botswana…
…to rejuvenate the delta…
with the kiss of life.
Every step that brings the herd closer to home…
is a continuation of a much larger cosmic odyssey.
From tiny molecules hitching a ride on dust beyond Jupiter…
to surviving the crushing heat of early Earth.
Imprisoned in the planet's core…
…then set free…
…to sow the seeds of life…
…every drop of water has an amazing tale to tell.
Every molecule…
-…a link in an unbroken chain…
…cycling over tens of thousands of years…
…through air…
oceans…
rocks…
…and elephants.
After eight months and hundreds of kilometers,
Metsi and her family have finally reached
the life-giving waters of the delta.
It's well past time to drink…
and play.
And then, drink some more.
And show the newest member of the family…
…how they do things in the delta.
Metsi and her new baby cousin
are the latest in a long line
to benefit from water's miraculous arrival
on this planet.
They will forever be connected
to the universe
that gave our planet this magic ingredient
and gave us the ability to preserve and treasure it.
Next, the story of our universe concludes…
…with the force that brings everything we've seen so far together.
The great sculptor of the cosmos,
gravity.
It's a force of attraction that built our planet.
And we'll bring two penguins together at Earth's southern pole.
But when did gravity start exerting its influence?
How does it create both order and chaos?
And why does it make ours the perfect planet for life…
…and love?