Original subtitles

Our Moon is a familiar face in the night sky.

She illuminates the way for animals on the move.

But even when her light fades,

she has an unseen power,

which guides creatures across the entire planet.

A humpback whale mum and her new calf

relax in the warm waters of the Hawaiian archipelago.

It's the perfect nursery.

The calf was born just a few months ago.

The tropical waters give him warmth.

There's shelter from the waves...

...and from the strong currents of the open ocean beyond.

But he'll have to face them soon.

He must build his strength, Mum must rest.

Their journey is about to begin.

They'll need to use the unseen power of the Moon to find their way.

Our Moon shapes life on Earth in extraordinary ways.

Creating the swelling tides...

...dictating the length of day...

...summoning the seasons.

She can light the way to love...

...reveal hidden pathways...

...bring times of plenty...

...or strip away chances of survival.

With each phase,

from full moon to new,

less light is reflected to Earth...

...but the more powerful the Moon becomes.

As the Moon aligns with the sun,

their combined gravitational pull on our planet

is at its strongest.

This shift in gravity...

...is the signal to start an ocean odyssey.

This calf has only known the shelter of these Hawaiian seas

since he was born.

The waters may be calm, but they are not always safe.

A male.

He's looking for the chance to impress.

And now he's joined by other males, who are all searching for a mate.

It's not known why,

but a new moon brings out their competitive side.

They are keen to show the female they've got what it takes.

In these displays, they can accidentally drown a young calf.

The males use the deeper water to fight for dominance.

Mum takes a chance to slip away.

She has led her calf to the safety of the shallows.

In a few short months,

he's already doubled in size drinking mum's rich milk.

But she hasn't eaten in six months.

This nursery comes at a cost.

There's not enough food for mum here.

And their feeding grounds are 5,000km away

in Northwest Alaska.

It's a journey all the humpbacks here in Hawaii must take,

and one the calf must learn.

This is the only time his mother will guide him north.

There's little margin for error.

Set off too early, and they'll arrive in frozen seas.

Stay too long, and they'll starve on the long voyage ahead.

The new moon is their signal.

Mum and calf can sense the greater gravitational pull.

For mum, it's time to head north.

For the calf, this new feeling

is the first lesson on the unseen power of the Moon.

They'll need to keep on course,

and pinpoint their feeding grounds

among thousands of kilometres of coastline.

And the Moon's power will guide them each step of the way.

Every month, the Moon changes not just her phase, but her position.

Higher in winter, appearing longer in the night sky...

...lower in summer, shining for less time,

only skimming the horizon.

It's these changes in phase and position

which set animal migrations in motion.

In the lowlands of Southern England...

...a nightjar rests in the heath.

She's a nocturnal hunter...

...and she's waiting for the Moon to rise.

In the cool of the night...

...the heath comes alive.

The full moon signals to the nightjar.

It's time to come out into the light.

She's searching for moths.

They spend these summer nights looking for a mate.

Using the Moon to navigate,

they'll keep it at a constant angle as they fly.

But tonight, the full moon is their downfall.

The nightjar's huge eyes

drink in every photon of light the Moon provides.

Tonight's bright full moon

helps her pick out insects silhouetted against the dark sky.

Under a full moon,

nightjars are twice as effective at catching prey.

And she must catch as many moths as she can.

Packed with protein,

insects are the ideal fuel.

But this Moon is more than a hunting aid.

It's a countdown to the start of her migration.

In late summer,

the low full moon will only stay above the horizon for a short while.

Nightjars' lives are tuned to the phase and light of the Moon.

And she won't be alone on this journey.

Nightjars all across Europe will start their migration

ten days after this low full moon of late summer.

Using the Moon as a clock,

they can synchronise their departure,

ensuring there's safety in numbers on their long journey ahead.

Thousands of nightjars will head to Central Africa...

...chasing an endless summer.

The changing height and phase are both clock and calendar...

...a seasonal signal and a call to arms.

Beneath the glow of a high winter moon

in Southern Australia...

...a transformation is underway.

Every year, spider crabs must moult their spiky armour

in order to grow.

But it'll take days for their new shell to harden.

So they're vulnerable.

Long legs help this crab travel around seven kilometres

from the rocky depths to the cool, calm shallows.

He's searching for a safe place to moult,

and needs to find it fast.

His body has already started to transform,

it can't be stopped.

The Moon has triggered others to migrate here to moult...

...but they've been followed.

A three-metre-long broad ray.

With no place for the crabs to hide...

...a lone crab is defenceless...

...and delicious.

They pin them to the sea floor.

Port Jackson sharks mop up the stragglers.

The Moon draws more crabs out of the deep.

In winter, the water is calm and cold...

...the perfect conditions to moult.

The full moon allows thousands of crabs

to co-ordinate their march to the shallows.

And as they gather, they begin to band together.

To shed his shell,

this crab needs to find the safety of the swarm.

He can't drop his guard.

He's no heavyweight...

...but can still pack a pinch.

Nipping at the ray's soft undersides...

...is just enough to put it off.

The safety of a huge mound is in sight.

It's a lucky escape.

Now he has an army who's got his back.

The mountain of crabs should make an easy meal.

But the mound is now a sea of spines and claws...

...which sways and shifts.

So the ray can't grip even a single crab.

There are as many as 20,000 crabs in this small sandy bay.

And with this sheer force of numbers,

they create an impenetrable fortress.

Surrounded by his band of brothers,

he'll moult, transforming in safety,

until his new armour hardens.

The crabs will disappear back into the depths until next year...

when the high winter moon signals the army to rise up once more.

The full Moon is 400,000 times less bright than the Sun.

But it's no pale imitation.

She can extend the day and open up new opportunities.

And there's no more important time than when raising a family.

In the lush forests of Kyushu Island, Japan...

...a red shield bug guards her tiny babies,

tucked into the leaf litter.

This is the only brood she'll ever have.

Shield bugs' lives are short.

Being a mum is the last thing she'll do.

To ensure they can get the best start in life,

she must leave them in search of food.

Among the tangle of vines and trees...

...she's searching for a special type of ripe fruit.

She keeps an eye on the pattern of light and shade in the canopy,

which will guide her home.

She's locked on to a scent.

The fruit of the Boro Boro tree.

But the light is fading...

...and her map has gone.

She can't find her way back to her babies.

A dark forest is a dangerous place for a lost little bug.

But the Moon is here to help.

It reilluminates the canopy.

It may not be as bright as the Sun,

but the contrast between the moonlight and dark

creates a clearer pattern.

The little bug can read these like points on a map.

So she's able to take the most direct route home to her babies

in minutes, not hours.

It's these full moon nights

which give her valuable extra foraging time.

Tomorrow, the Moon will shine less bright,

the canopy map dimmer,

harder to read, less time to feed her babies.

But tonight, it won't set until dawn,

so she must make the most of this extended opportunity

to find food on this long, moonlit night.

On the nights after the full moon,

the amount of reflected light fades fast.

A crescent moon is barely visible...

...but even a silver sliver can keep animals on track.

African savannah elephants

take the definition of a midnight snack to the extreme.

They can spend 16 hours eating,

and consume over 100kg of food a day.

They'll spend so much time eating,

that they're awake nearly all night.

And all that food has predictable consequences.

Life in the shadow of giants is a dangerous game.

This little beetle could easily be crushed.

But it's a risk he must take if he's to win a mate.

For this beetle, dung is a prized possession.

A big ball of dung is exactly what a female beetle is looking for

to lay her eggs in.

And this pile has already attracted other males.

To beat the competition, he needs to be quick.

It's time to get dirty.

Using his strong legs,

he sculpts a ball five times his size.

He needs the moonlight to make a clean getaway.

A straight line is the fastest way.

But which way to go?

The small amount of light from a crescent moon

is scattered by particles in the atmosphere.

And this creates lines of light in the night sky...

...known as polarised light.

Even head down and facing backwards,

he can follow these lines of light.

But beware the thief in the night.

With such a big ball,

stopping to check your position can be risky.

Equally matched, it's now a battle of stamina.

he needs to stay on top.

Losing the higher ground could mean it's game over.

But he won't give up.

With the chance of other dung-ball bandits nearby...

...he pushes on, following the polarised light.

Finally, his new ball of dung

brings him the female attention he desires.

The ball will become home for their new brood.

He'll keep pushing,

until he finds soil soft enough to bury the ball.

His moonlight guided great escape...

...finally complete.

Moonlight offers a visible guide to animals on the move.

But the Moon has an unseen,

and even more powerful way to guide navigators.

The Moon's proximity to Earth

means her gravitational pull helps power an immense force.

Under the Earth's crust,

the iron-rich rock is molten.

Just as the Moon's gravitational pull acts on the tides,

it also tugs on the swirling rock deep underground.

This movement adds electromagnetic energy,

creating powerful magnetic fields.

These fields align and oppose each other...

...creating our North and South Poles.

When charged particles from space strike this magnetic field...

...it causes the atmosphere to glow,

and it becomes visible as an aurora.

An ever-present power,

felt all across the entire planet.

Even in the middle of the world's largest ocean, the Pacific.

155 million square kilometres

of endless blue.

Its sheer size means storms and strong currents

swirl across it uninterrupted.

Our humpback mum and her young calf...

...are 2,000km from land.

In the open ocean, they could easily be knocked off course.

The calf sticks close to mum, riding her slip stream,

saving valuable energy.

But mum is now burning through

hundreds of thousands of calories a day.

Make a mistake in navigation now, and it could cost them their lives.

As they journey, the visible Moon will change phase and position,

so it can't be relied upon as a guide.

But the magnetic field is an all-pervasive power.

Inside their brains,

mum and calf both have tiny iron particles,

called magnetite.

These align with the magnetic field,

triggering a cellular reaction.

It lets them sense how steep and how strong the field is.

From this, they can work out their position,

and in what direction to swim.

Their own biological map and compass.

So mum can find her way across this seemingly featureless ocean.

And now the calf is learning how to use this sense...

...for a life as a long-distance ocean voyager.

The magnetic field touches every part of the planet,

from the deepest oceans...

...to high mountain peaks.

From the largest animals on the longest migrations...

...to the smaller, but no less mighty.

Deep in a European forest...

...the spring sunshine stirs a sleepy Alpine newt.

After a year in the woods,

instinct now drives him to find water.

He's looking for a mate.

This finger length newt is too small to see which way to go.

He'll need to rely on his superpower to find his pond.

But he's not alone.

A grass snake,

energised by the sun, is on the hunt.

The snake relies on its speed and strength

to chase down and strangle its prey.

Little legs struggle in the dense forest.

But for a tiny newt, there are plenty of places to hide.

The setting sun is a sign it's safe.

A grass snake can't hunt in the dark.

But now disorientated from the hunt,

he needs to work out which way his pond is.

He, too, has magnetite in him.

His superpower, which allows him to sense the magnetic field.

Just like following a compass,

he's keeping his whole body aligned to the angle of the field...

...and can head in the direction of the pond he left a year ago.

A spring storm doesn't bother him, either.

The magnetic force flows whatever the weather.

With his internal compass,

this tiny newt can travel as far as four kilometres.

As the dense forest thins out,

the newt can now smell that water is close.

Finally, his pond.

Time for a well-earned dip.

But he can't rest, it's time to find a mate.

As the season turns to summer,

he'll return to the forest,

but next spring, wherever he is in the woods,

he'll find his way back to this pond,

using the lunar-charged magnetic field to point the way.

As the magnetic field wraps around the planet,

its angle changes.

At the poles, it's vertical.

At the equator, it's parallel to the surface,

creating a map for those who can read it.

Where the waters of the vast Atlantic

meet the Congo jungle,

the coastline is one of the few places in the world

suitable... for ocean giants to emerge.

Four kilometres of sand...

...just soft enough, the beach not too steep.

This Leatherback turtle

touches land for the first time in three years.

The Moon has gifted her a high tide,

helping her part of the way.

She'll need all the energy she has to haul herself up the beach.

Using a Moon-powered map,

she's travelled from her feeding grounds in Brazil,

six thousand kilometres away,

back to the place she first hatched...

...on the coast of equatorial Africa.

This time, she's here to lay eggs of her own.

Her eggs will be incubated in the warm sand...

...where they'll develop a super-sense.

Mum has done all she can.

She's leaving her eggs in the care of the Moon.

As the eggs develop,

the lunar charged magnetic field courses through them,

deep in the sand.

The hatchlings have particles of magnetite within them,

and can also sense the angle of the magnetic field.

So each one is born with a magnetic imprint

of this stretch of coastline.

This beach is their first mark on their magnetic map.

But it's the visible Moon which guides their first steps.

Instinctively, they head out

to the brightest part of their new world...

...moonlight reflected on the sea.

They'll ride the ocean currents in search of food.

As they travel, the angle of the magnetic field will change.

They'll add new markers on their internal map -

the key to long-distance navigation.

From the shores of central Africa...

...a whole ocean awaits.

The Moon has had influence over the Earth

for billions of years...

...creating profound physical changes to our planet.

These allow animals on the final stretch of their long migration

to home in with amazing accuracy.

The gravitational pull of the Moon strains the Earth's thin crust.

This has helped create volcanic peaks,

and vast canyons, even underwater.

Such are the scale of these formations,

their huge mass alters the gravity on Earth,

slightly stronger where there are mountains,

slightly weaker in deep canyons.

These are gravitational signposts for those who can feel it.

Mum and calf can sense the slight change in gravity

caused by the mountains and canyons on the ocean floor.

They've made it,

across 5,000km of open ocean

to the cool Alaskan waters.

The calf now has a thick layer of blubber to keep him warm.

But mum has lost nearly half her bodyweight

since she left these shores seven months ago.

These green seas

are a sign her fasting will soon be over.

Plankton-rich waters have drawn in millions of herring,

and this is why mum and calf have come so far.

Weeks of travelling with the Moon as their guide,

they've arrived at the right place and at the right time.

And there's one final skill the calf can learn.

How to work as part of a pod...

...and master the art of the hunt.

The males put their fighting aside, and now work together.

Each humpback in the group has a role to play.

One releases air,

whilst swimming in a circular pattern towards the surface.

As the bubbles rise, they form vertical curtains...

...forcing the fish together.

Calls from the others further concentrate the shoal...

...and then, a co-ordinated surge.

The bubble-net size, shape and amount of air is adjusted,

depending on the type of prey.

Not all humpbacks catch food this way.

it's unique to only a few groups in Alaska.

This calf is part of a special community of whales.

He'll need to spend the summer finding his place in the pod.

After a well-earned feed, it's time to play.

But there's another reason for his breaching.

It's now thought the young humpback

is also resetting his senses.

As he freefalls back into the water,

he's calibrating to the gravity signposts

of the underwater mountains and canyons

at these rich feeding grounds.

Once autumn arrives and the herring leave,

the calf will join his mum on the return back to Hawaii.

The next time he travels back to these waters,

he'll do so alone.

On his long journey triggered by the Moon phase...

...kept on course by the magnetic field...

...and guided by gravity.

The Moon's all-pervasive power and influence

will be with him every step of the way.

To film the lunar lives of leatherback turtles in Gabon,

the team partnered with a local NGO devoted to their survival.

Didier doesn't have to go far to reconnect.

Only ten kilometres from the capital Libreville

is Pongara National Park,

one of the world's most important nesting beaches

for endangered leatherback turtles.

Adult turtles can get tangled and drown in discarded fishing nets.

And Pongara's proximity to the capital

brings a greater threat.

Timber from Gabon's vast forests

is taken by sea to sawmills in the capital.

Not all the huge trees make it.

Leatherbacks have existed since the time of the dinosaurs,

and it's down to the hard work of Didier and his team

to help them survive the pressures of the modern world,

and ensure Pongara remains a vital nesting ground -

critical not only for Gabon, but of global importance.

Subtitles by Sky Access Services www.skyaccessibility.sky