Earth from Space

From high in space,

we can see the familiar shapes of countries...

...and continents.

But now, satellite images

allow us to look closer...

...revealing our planet as a patchwork

of extraordinary landscapes...

...created by natural forces...

...by animals...

...and by us.

These patterns give an insight into the health of our planet.

Behind every line and every pattern...

...there's a story.

Around the world...

...tropical coastlines are fringed with coral reefs.

At first glance,

their shapes seem random.

But a closer look reveals a pattern...

...pale discs surrounding patches of dark coral.

Using satellite images,

scientists have now found these shapes

on coral reefs across the globe.

Understanding how they are formed

offers a new insight into the health of our oceans...

...and the animals that call them home.

For fish that live on coral reefs, there are different strategies

for finding food.

Some stay close to the reef...

...feeding from the coral itself.

Others venture out

to the surrounding seabed.

But feeding in the open...

...can be dangerous.

Predators, like coral groupers...

...and sharks,

patrol the reef perimeter.

So small fish only feed as far from the coral

as is absolutely necessary...

...staying within easy reach of safety.

Over time, the seabed around each patch of coral is stripped of food...

...creating rings of bare sand

that scientists call grazing halos.

They are a sign that both predator and prey populations are healthy.

But where this pattern disappears,

it may be a sign that predator numbers are falling.

These halos now allow scientists

to monitor the reefs' delicate balance from space.

Satellite cameras can now look down on every part of our planet...

...allowing us to explore Earth's most remote habitats.

The Congo jungle in central Africa.

This forest is home to thousands of animal species.

But from space, it appears as little more than a blanket of green...

...except, that is, if we look down over one remote corner.

Satellite images reveal a strange shape...

...with dozens of trails leading in from the surrounding forest.

This shape was created by the Congo's mightiest residents.

They spend most of their lives hidden in the thick jungle...

...but travel hundreds of kilometres to gather here.

Forest elephants.

Locals call this place Dzanga Bai...

...the Village of Elephants.

Forest elephants spend most of their lives in small family groups.

But here, up to 150 individuals

are drawn together every day.

Their diet of tough leaves and jungle fruit is lacking in vital minerals.

So generations of elephants have come to this one spot in the forest...

...where deposits of sodium, potassium and calcium

lie just below the surface.

Using their tusks to dig at the soil

and their trunks to blow into the water...

...these elephants have excavated a network of boreholes...

...allowing them to extract these minerals from underground.

Over hundreds of years, the constant digging

and movement of elephants has caused this clearing to grow.

It's now more than 500 metres long...

...and clearly visible from space.

For a young forest elephant, a first visit to the Bai

is full of new experiences.

While the adults drink effortlessly...

...she's still getting to grips with her trunk.

Infants are raised by their mothers for up to four years...

...and learning how to drink from these wells

is one of life's vital lessons.

For a calf who spends most of her time with her mother...

...this is a rare opportunity to socialise.

Relationships formed at this young age can last a lifetime.

But while they play...

...mothers must keep a close watch.

Male forest elephants are also drawn here.

This gathering is the ideal place to find a fertile female.

To display their size and strength...

...bull elephants charge around the clearing.

And if more than one male appears...

...tensions run high.

Young forest elephants have been killed here by charging males.

Mother retreats to the safety of the forest.

Her baby should be able to return to this clearing throughout its lifetime.

But these elephants face an uncertain future.

In the last 20 years,

more than half of all the forest elephants in the world

have been killed by poachers for their ivory.

But cameras in space may be able to help.

Scientists can now use satellite images

to identify other clearings used by forest elephants...

...protecting them from poachers...

...and preserving these unique gatherings.

But you don't need to be as big as an elephant

to make a mark visible from space.

In South Australia...

...the outback is speckled with mysterious light patches...

...interlinked with narrow trails...

...the work of an unlikely architect.

He's a southern hairy-nosed wombat...

...a marsupial only found in this part of Australia.

Exposing the thinner fur of his belly

helps to keep him cool as he waits for the midday heat to pass.

Then there's work to be done.

It's springtime,

and with each passing day temperatures are steadily rising.

In just a few weeks,

it could be close to 50 degrees Celsius.

Wrapped in a thick fur coat, this heat could be deadly.

But the wombat has a solution.

With sharp claws and short, powerful limbs,

he's built for digging.

It's 15 degrees cooler below ground...

...a hiding place from the worst of the summer sun.

But high temperatures aren't the only threat wombats face.

Habitat loss and the impact of invasive species

caused wombat numbers to plummet in the early 20th century.

But now, using satellite images to locate their burrows...

...scientists can see they're bouncing back...

...with around one million southern hairy-nosed wombats

now living in this corner of Australia.

In South America,

vast areas are covered with lush, green tropical forest.

But on the coast of north-east Brazil,

the forest is interrupted by a very different landscape.

Vegetation is being swallowed up by sand.

Washed up by the ocean and blown inland over thousands of years...

...a field of sand dunes covering more than 800 square kilometres.

The Lençóis Maranhenses.

The surface of the scorched sand

can reach 80 degrees Celsius.

To survive here you have to be made of tough stuff.

A Pininga turtle.

She's left the surrounding forest behind...

...and is making her way into the heart of this desert...

...walking for days

beneath the burning sun...

...each step on the soft sand sapping away her precious energy.

Without food and water, she won't survive for long.

But she's made this journey for a reason.

It's the wet season.

And in these dunes, the rain changes everything.

Only from space can we see the scale of the transformation.

Once a year, rainwater floods the desert...

...forming thousands of freshwater lagoons.

Beneath the sand, a layer of solid rock stops rainwater escaping...

...creating a landscape

like nowhere else on Earth.

And that's just what she came for.

As the lagoons grow,

fish make their way into the pools from surrounding rivers.

They'll keep her fed for weeks.

But this water won't last forever.

In the tropical sun, these lagoons will soon evaporate.

Dozens of desert species now race

to make the most of the life-giving water...

...even after the sun has set.

A tiny four-eyed frog.

He's been lying dormant in the cool sand.

But the rains have triggered the breeding season.

And there are thousands just like him.

In other parts of the world,

frogs migrate for kilometres to reach their breeding pools.

But here, the water has come to them.

Around the lagoons, grasses have sprung up,

creating sheltered spots for breeding.

And it's not only four-eyed frogs who come here.

Seven different species of frogs and toads

are all hoping to breed.

It's a struggle to make yourself heard above the noise.

Eventually, the four-eyed frogs find each other.

Each pair may produce more than a thousand eggs...

...an explosion of new life.

And just in time.

When the rains ease, the lagoons begin to disappear...

...and sand reclaims this corner of Brazil.

Around the world, the forces of nature

create mysterious and intriguing patterns

visible only from space.

Star-like shapes in the Sahara desert

are sand dunes whipped up by the wind.

In West Africa, a ring of concentric circles...

...formed by magma forcing its way through the Earth's crust.

And in Iran's salt desert,

these abstract swirls are the remains of an ancient ocean...

...sculpted by the wind over millions of years.

In the Amazon rainforest, hundreds of rivers wind through the jungle.