Practice English Speaking&Listening with: The Sun

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[tranquil music]

DAVID: A Perfect Planet.

[sizzles, splutters]

DAVID: There is a nuclear reactor 93 million miles away.

We call it the Sun.

Its rays, travelling through space,

reach the Earth in just eight minutes

and give power to life throughout the planet.

[whale squeals]

DAVID: Its daily and yearly rhythms

shape the existence of every creature on Earth.

[tranquil music]

DAVID: And has done so for over three billion years.

[waves crashing]

[grand music]

DAVID: In the beginning...

there was light.

Surprisingly perhaps,

almost every part of the Earth's surface

receives the same quantity of sunlight each year.

4,380 hours of it.

But it's delivered in varying amounts,

at different times of the year, depending on where you are.

[birds chirping]

It's only here in the tropics, close to the Equator,

that there are 12 hours of guaranteed

daily sunlight the year round.

[animal squeaks]

[birds chirping]

And here that has created a great richness of life,

the tropical forest.

Each leaf is a natural solar panel,

which collects the sun's energy and fuels a multitude of plants.

And in southeast Asia, gibbons live here.

[howling]

DAVID: A five-year-old female

and her lifelong partner

are on a mission.

Every morning, they head out across their territory

to look for ripe fruit.

[gibbons howling]

DAVID: There is one kind of tree here

that they need more than any other.

The fig tree.

These are the only plants in the entire forest

that produce fruit all year round.

Their flowers grow in dense clusters

inside undeveloped figs.

But these have not yet been pollinated

and are not yet edible.

The gibbons

will have to wait.

To produce ripe fruit,

the fig still needs two things.

A large dose of sunlight

and some of the smallest creatures in the forest.

Tiny fig wasps.

They're only two millimetres long.

The figs have a unique partnership with these insects.

A female wasp has the space of just a single day

when the fig will allow her to burrow

into the undeveloped fruit.

It's such a tight squeeze that her wings are ripped off,

but she's not going to use them again.

Once inside,

she makes her way to the tiny tightly packed internal flowers.

And here within,

she lays hundreds of eggs.

She then carefully unpacks fig pollen from her abdomen

and with it, fertilises the tiny flowers.

When she's finished laying,

she dies

inside the unripe fig,

alongside her eggs.

The sunlight now slowly ripens the figs

and helps the young wasps inside to develop.

After just five weeks,

the eggs start to hatch.

The first to emerge are the golden wingless males.

Things now become stranger than fiction.

These males start to mate

with their unhatched sisters.

To reach them, they use a telescopic penis

that's twice their body length.

While their now pregnant sisters

are beginning to hatch,

the males themselves burrow their way to the outside world.

[tranquil music]

The brother's final act

is a chivalrous one.

They sacrifice themselves to marauding ants.

They're serving as decoys,

so their sisters can take to the skies.

The young females, loaded with pollen,

live for just 48 hours

in which time they must find another fig tree

at just the right stage

into which they themselves can burrow as their mothers did.

With the sun's helping hand,

the figs are now ready to eat.

[grand music]

DAVID: The gibbons know all the fig trees

in their territory,

and each day, they travel up to two miles to find one

with fruit that's ready to eat.

Ripe figs at last,

a major part of their diet and available the year round.

Thousands of animals rely on fig trees.

This abundance is only possible

in a world without seasons,

and constant daily sunlight.

But this 12-hour cycle of light and darkness

only happens close to the Equator.

Elsewhere, the amount of sunlight

fluctuates across the year.

That is because the Earth does not spin in an upright way.

Its axis is on a tilt.

23.5 degrees.

So as the Earth makes its annual orbit around the Sun,

keep your eye on the North Pole.

For the first half of the year, its angled away from the Sun,

bringing darkness and winter to the Northern Hemisphere.

For the second part of the year,

the North Pole swings towards the Sun bringing summer.

The Earth's tilt gives us the seasons.

And life has adapted

to deal with even the most extreme changes in light.

The high Arctic.

After six months of being angled towards the Sun,

it begins six months of freezing darkness.

[eerie music]

DAVID: This is Ellesmere Island,

the closest land to the North Pole.

It's winter,

and for the last four long months,

the only light here has come from the moon.

Few creatures can survive this sustained darkness.

They have become specialists in living for months

without sunlight.

[wind howling]

DAVID: Muskox,

remnants of the last ice age.

Having grazed all summer, they've built up fat reserves

that will enable them to survive the brutal cold of winter.

And this makes them

a prime target for other sub-zero specialists.

Arctic wolves.

The moon provides just enough light for them to see.

[ominous music]

DAVID: This alpha female leads the hunt.

Target in sight.

If her pack is to survive,

they need to make a large kill

at least once every three weeks.

[grunting]

[low growls]

The alpha female signals the start of the attack.

[suspenseful music]

They run at the muskox

and the herd panics.

The muskox close ranks.

The wolves look for weakness.

[low growl]

[roars louder]

Charging risks isolation from the crowd.

And that is just what the wolf pack wants.

[muskox roars continue]

[wolves whimper]

DAVID: The wolves can sense victory.

But the herd comes to the rescue.

And once again, they close ranks.

Most winter hunts end in failure for the wolves.

As the long polar nights drag on,

the hungry wolves turn

to their only other source of food.

Arctic hares.

[whimsical music]

They've gathered together in their hundreds, for safety.

Trying to catch one hare amongst hundreds

is harder than you might think.

Even if they do catch one, it's not much of a meal.

Sometimes,

you just have to admit defeat.

But life is about to get better for the wolves.

[tranquil music]

For the first time in six months,

the sun rises above the horizon.

Its appearance marks the beginning

of half a year of continuous light.

The sun's warmth will allow the muskox to give birth,

and that will provide easier hunting for the wolves.

[tranquil music]

It's early spring

and much of North America

is still locked in ice.

As our tilted planet orbits the Sun,

the Northern Hemisphere receives increasing sunlight,

and wakens an animal

with an almost supernatural ability.

[suspenseful music]

It is frozen solid, like a block of ice,

and has been all winter.

An ordinary looking frog,

but an extraordinary one.

A Wood Frog.

Its heart has stopped beating completely.

But as the sun's power increases,

almost miraculously, it begins to change.

Its frozen blood is melting

and begins to flow through its veins...

as his heart begins to beat again.

The Wood Frog is cryogenic.

In just 12 hours, it thaws

and comes back to life as if by magic.

This defrosting ability

means it's ready for the moment when, at last,

spring arrives.

All across the Northern Hemisphere,

the sun's warmth is bringing dramatic change.

[grand music]

[bird chirping]

As the sun rises higher

and spring takes hold,

the warming air reaches the ground

and the rocks beneath.

Here, thousands of animals begin to stir.

Garter Snakes,

one of Canada's most northerly reptiles.

[suspenseful music]

After six months of hibernation,

the males are the first to emerge.

They haven't eaten for months.

Even so, it's not food that is on their minds.

It's something else.

Females.

But they stand no chance of doing anything about that

until they've charged their batteries.

Snakes are cold-blooded and they need to absorb the sun's heat

before they're able to move quickly.

After a few hours, the males are raring to go.

Twenty thousand snakes.

The largest emergence of reptiles anywhere on Earth.

Now, a few females appear.

They're much bigger than the males

and warming will take them longer.

She releases a scent, a pheromone,

that attracts the males.

They outnumber her a hundred to one.

To speed her own return to activity,

she will absorb heat from them.

Intoxicated by her scent,

the males compete for her, wrapping themselves around her.

She now has hundreds of males on top of her,

making mating near impossible.

But she has a way of weeding out the men from the boys.

She'll make a daring ascent

of the nearby cliff.

She barges her way through the crowd to get to the rock face.

As she climbs, only the strongest, fittest males

can keep up with her.

[suspenseful music]

[music rising]

DAVID: She's made it to the top.

Only a few of her suitors have managed to rise to the occasion.

And she may reward them all.

This entire mating jamboree

only lasts for one short week in the year.

And when it's over,

they all move off into the forest.

There, they disperse to lead solitary lives

searching for food, until winter drives them back

to the shelter of the rocks below ground.

[birds chirping]

[animal cawing]

It's June,

halfway through the Earth's annual journey around the Sun,

and summer has arrived in the Northern Hemisphere.

Karrak Lake, in Canada,

north of the Arctic Circle.

The summer will be brief,

but there is sunlight for 24 hours every day.

So, the next few months are vital

for every living thing here.

And this Arctic fox knows it.

[squeals]

Winter has been hard for her,

and now with a new family to support,

she must make the most of the summer's abundance.

Her three-week-old pups

have just emerged from the den.

[squealing]

DAVID: Each of these little bundles of fur

needs nearly 300 calories of food every day.

A tall order for Mum.

But a solution for her problem is just arriving.

[honking]

Snow Geese.

They have flown over a thousand miles from the United States,

timing their arrival to coincide with the end of the snow.

[honking continues]

DAVID: More than half a million will spend the summer here,

nesting and feeding on the grass.

There's fierce competition between couples

for the safest nesting sites.

[honking]

The losers will have to nest on the outskirts of the colony,

the first part to be raided by the foxes.

[tranquil music]

[geese honking in the distance]

Mother is after eggs.

But getting them is not going to be easy.

[suspenseful music]

[honking]

DAVID: The geese will risk their lives to protect their eggs.

If they lose them,

they can't produce another clutch this season.

The fox wins.

[honking]

DAVID: She gives the first eggs to her young pups.

And then, heads back for more.

[geese honking, hissing]

DAVID: Some of the eggs, she stashes away.

They will be food to help her through the coming winter.

In just three weeks,

she will steal over 800 eggs from the geese.

But eating a big egg is not easy

if one is rather small.

It's a technique

the pups haven't quite yet cracked.

Mum shows how it's done.

[squeaks]

Goslings are now hatching all across the colony.

And they will need all the food they can get

to build up their fat before their journey south.

Now that the chicks have hatched,

they can all find safety on the water.

In these brief sunlit months,

there's time for the cubs to play.

But there is no playtime for mum.

But the Arctic is warming

and the timing of the seasons and the migration of the geese

is becoming unpredictable.

Although the sun stays above the horizon

continuously throughout the Arctic summer,

its rays are comparatively feeble.

Closer to the Equator, in our planet's deserts,

cloud cover is rare.

[eerie music]

DAVID: The sun here is not a friend,

but an enemy.

Africa.

The Sahara.

Few creatures can live here.

Get caught out in the open, at the wrong time of day,

and it's game over.

By ten in the morning,

the temperature on the surface of the sand

is pushing 60 degrees Celsius.

Even the toughest will soon have to take cover.

But one creature is waiting underground

for the sun to get even hotter.

Temperatures are now so high

that everything else has to shelter.

[rumbling, explosion]

DAVID: The desert now belongs

to the Earth's greatest solar specialist.

The Saharan Silver Ant.

At midday, when the sun is at its fiercest,

they emerge to look for creatures

killed by the scorching heat.

They're one of the fastest insects on Earth.

And they need to be with just five minutes to find food

before the heat kills them.

Getting lost would mean certain death.

So, every few seconds, they spin round,

taking a bearing from the sun.

When others are frying,

these ants have solar tech

to stop them from overheating.

Special glassy hairs and shining bodies

that reflect the sun's lethal rays.

It buys them precious time.

To get their prize back as quickly as possible

to their underground den

demands teamwork.

But shelter is a long way away.

Any technique will do.

The push and slide.

The spin.

Even dune surfing.

[suspenseful music]

DAVID: The nest is still 70 metres away.

Some are already collapsing in the heat.

Reinforcements are needed urgently.

Now, the heat

whips up violent gusts of hot desert air.

[wind roaring, rumbling]

For an ant, these are hurricanes.

[ground rumbling]

DAVID: They must get their prize underground as soon as possible,

and blown sand has blocked the entrance to their den.

Any longer out here and they will be toast.

One final effort.

The last of the team race home.

Shade at last.

Much of the land on our planet

could become as scorched and lifeless as this

if we allow our activities

to continue to change the atmosphere.

The Sahara alone has expanded

by an area twice the size of France

in just the last hundred years.

[wind hissing]

Part of a global desert invasion

that threatens a third of all land.

The sun can certainly be a lethal threat.

But it could also be our saviour.

The solar energy that strikes our planet in just an hour,

contains more power than that used by all of humanity

in an entire year.

By October,

as the Earth completes

its annual journey around the Sun,

day lengths in the Northern Hemisphere

are shortening once again.

[birds chirping, cawing]

DAVID: The sun's power is diminishing.

Trees are beginning to shut down their solar panels.

The green chlorophyll with which they collected the sun's energy

is broken down chemically and reabsorbed.

[tranquil music]

And the forests turn from emerald to gold.

It's autumn.

Once again, the living world away from the tropics

is transformed.

Plants stop growing

and many animals begin to prepare

for tough times ahead.

[animal honking]

The forests of Central China.

Home to the golden snub-nosed monkey.

[monkeys squeaking]

They will not survive the fast approaching winter,

unless they stock up on calorie-rich food.

Top of their autumn menu,

pine cones.

They grew during the summer sunlight and are rich in fats.

Few are now left

and time to gather them is running out.

Dominant males patrol the troop,

making sure they get the pick of the crop.

[squealing]

As the number of pine cones dwindles,

tensions between rival families increase.

[high-pitched squeals]

Mere threats between two males

may not be enough to settle disputes.

Conflict is in the air.

There's going to be a fight.

[suspenseful music]

[loud squeals]

Vital food is at stake,

so every pine cone is worth fighting for.

[squeals continue]

The victor and his family enjoy the spoils of war.

The losers get no more than a few dead leaves,

and will have fewer energy reserves for the coming winter.

The sun's power dims.

Temperatures drop.

Everything slows down.

Ahead lies months of crippling cold.

[squeaks softly]

[dramatic music]

DAVID: Most of the life on Earth away from the tropics

has managed to adapt to the changing seasons.

But there are some creatures

that have found a way to avoid the cold of winter altogether.

Snares Islands, New Zealand,

deep in the Southern Hemisphere.

[loud caws]

Here, sooty shearwaters

have been nesting throughout the long summer

and gorging themselves on fish.

As a result, they have piled on quite a few pounds.

But the sun is now fading

and the southern winter is approaching.

No time to hang around.

When you're a touch tubby,

launching into the air...

[birds cawing]

DAVID: ...is a leap of faith.

They won't see land again for four weeks.

Setting off across the Pacific,

they're starting on one of the longest journeys

made by any living thing.

Their aim,

to avoid the consequences of the Earth's tilt,

and follow the sun's warmth,

as it dwindles in the south and increases in the north.

For those who survive the 10,000 mile marathon,

there will be a great prize.

The reward for travelling from

one end of the planet to the other

is long summer days the year round.

This is their destination.

Alaska's Aleutian Islands.

While the south of our planet is slipping into autumn,

here, summer is just beginning.

[water flowing]

DAVID: Below the waves,

vast clouds of plankton are blooming

triggered by the sunlight.

These tiny marine organisms

are food for crustaceans.

Krill.

This is the sun-fuelled bounty

for which the shearwaters have crossed the planet.

[birds cawing]

DAVID: By cheating the tilt,

they're able to enjoy the riches of summer the year round.

But shearwaters are not the only ones to visit the warming seas.

[whales moaning]

Humpback whales.

[whale blows]

DAVID: They've been breeding in the tropics

and haven't fed for six months.

Up to 6,000 whales are now heading for these islands.

The only place where they can find food

in the quantities they need.

The shearwaters begin to dive into a huge shoal of krill.

[grand music]

DAVID: The humpbacks attack from below.

[strong blow]

Each year, a million shearwaters join the whales

in these dramatic feeding frenzies.

[shearwaters cawing]

[whales moaning]

DAVID: It's one of the greatest gatherings of life on Earth.

And it only happens

because some whales and some birds

have found a way to live in a summer that never ends.

[uplifting music]

The Description of The Sun