All language subtitles for our.universe.s01e05.1080p.web.h264-bigdoc

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 sucks 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?