Original subtitles

The human eye, one of the most powerful instruments on Earth.

On a clear day we can spot the smallest detail in the widest view.

But what the eye sees is not the full picture.

Alongside the world we see is a very different world.

An invisible world

of hidden forces and powers that

shapes every aspect of life on Earth.

Now technology can open a door on that hidden world

revealing its mysteries and showing us the true wonder

of the world we live in.

An ordinary everyday scene, a street, houses, people, cars,

number 12's parked in the wrong place, again.

What could be more normal?

Except this scene is incomplete.

Our picture of it is only partial.

There's something else going on out here, something that the eye

could never capture, but that's as real as the road beneath my feet.

The extraordinary truth is that the picture we see is only

the tiniest, minutest fragment of a far, far greater reality.

But now we can glimpse that wider world, the invisible world, and see

the many ways it shapes our lives.

These men in beige gloves are hunting a lethal force.

HELICOPTER WHIRS

A force that's present all over the world, but completely invisible.

To find it, they're doing something of quite awe-inspiring danger,

and I don't just mean riding on the outside of a helicopter.

They're about to fly

within inches of a power line carrying half a million volts.

Adrenaline rush at times, yes.

There are certain situations you can get into that are very, very hairy.

This might seem like insane showing off,

but they're doing it for a reason.

These power lines carry a massive and potentially lethal danger.

There is an invisible force field.

You cannot see it, but if you get close enough, yes, you can touch and,

you know, you can feel the electricity around it.

And it's a pretty good potential to get you killed.

You don't say! But now, for the first time, specialist cameras

can see the hidden force that could reduce him to a pair of

smouldering beige gloves.

What appeared to be a normal power line is actually revealed to

have a violent discharge signalling a potentially

catastrophic leak of electricity.

It's a phenomenon known as corona.

So what exactly is this phenomenon?

Inside that power line above me hundreds of thousands of volts

of electricity are creating a massive electric field radiating out

from around the line.

You can't see it at the moment and that's not just because it's dark.

Let me show you how strong that field actually is.

Now, right now I am the tallest thing around here...

Yes, all right, I just am!

So that electric field is going through me to the earth,

but if I step away it's strong enough to do this.

Now, there's no other power going in, it's just

that electric field that's switching on all of these lights.

And these lines are perfectly normal and well insulated, but if there's

a leak or a fault on the line that electrical field becomes massively

intensified, so intense that it charges the air around it

and causes a discharge called a corona.

The more intense the invisible corona, the bigger the leak of

high voltage electricity.

If it's not taken care of, it could lead to all manner of

unpleasantness, including power cuts, dangerous short circuits,

even fires.

It needs to be fixed and that's where this lucky chap comes in.

So, he's next to a half million volt power line,

and what's he going to do now? Yep, he's going to attach himself to it.

OK.

HELICOPTER WHIRS

Right now the crew are protected only by their mesh suits

and the fact that they're not earthed.

For a few seconds, the helicopter and the power line

are bonded together, a huge electrical field surging around.

Caught by the specialist camera, the images reveal concentrated

hotspots of corona where the sharp points of the rotor blade bend

and intensify the electrical field.

When the air reacts with this intense electrical field

it creates an invisible light discharge and it's this light

that the camera is tuned to detect.

But to the naked eye

it's completely invisible.

Which, in the circumstances, is probably for the best!

Suffice to say it's a good job these two blokes get on.

Being that we know each other so well, a lot of it is just by the way

he may be posturing.

If he moves his head to the left or, you know, reaches for the left I'll

be heading to the left.

Basically, Tracy and I don't even really have to talk to each other

any more. We know each other so well that we get all everything

ready to go, suited up, I give him the OK and we're on line.

And when he says on line, he means actually sitting

on a live power line

and starting the precise manoeuvre to disconnect from the helicopter.

And as he does that, the corona keeps on surging around them.

But as soon as the link is broken

the corona on the helicopter vanishes, leaving just a few spots

on the lineman just to remind him you

he's still sitting on a live power line!

The corona is as real as the power lines themselves, but it's part of a

vast invisible world that lies hidden from our sight.

I will need this.

Because although our eyes are incredibly clever and powerful,

they're only sensitive to a very narrow band of light.

If you pass light through a prism, like a sheet of water, it splits

what the brain sees as white light into a spectrum of

seven different colours, each in a well-defined place.

Red, orange, yellow,

green, blue, indigo and violet, the visible light spectrum.

Together these seven colours account for all the wavelengths

of light that we can see, but what lies beyond this spectrum,

in other words out here past violet or over here beyond red?

Well, as far as the eye is concerned,

nothing, but that's far from true.

In fact, the light spectrum

stretches far beyond the visible light we can see.

You can think of the spectrum of light as a bit like the notes

on a piano. Imagine these seven notes

represent the visible spectrum and the familiar colours of red, orange,

yellow, green, blue, indigo and violet.

So all that we can see accounts for this octave.

But that, in fact, is just a tiny

percentage of the entire spectrum of light.

If you want to be exact,

it's 0.00000000001%.

And just like this piano has many other notes,

light exists in many other wavelengths

with infrared down here and ultraviolet up here.

And that is just a beginning.

If our visible spectrum is just one octave on this piano, then

to represent the entire spectrum from gamma rays to X-rays

and right through to radio waves,

you'd need the keyboard to extend...

And extend...

And extend...

Still going...

Still going,

right out as far as the sun 93 million miles away.

That's a very big piano!

And in that huge invisible realm

even the most familiar things are not quite what they seem.

Our own sun, a benign source of warmth,

life and the vague hope that you might have a barbecue tomorrow.

But go beyond what we see and we get a very different picture

of our nearest star.

In ultraviolet our benign sun becomes a writhing mass of violent

and dangerous activity.

These UV images from a space telescope reveal supercharged gases

a million degrees hot and solar flares rising thousands of miles

above the sun's surface.

We can even see the intense magnetic fields that create dark sunspots

and solar storms.

And X-ray telescopes reveal what we could never see with the naked eye,

the sun's outer atmosphere,

a ring of glowing gases hotter than the sun itself.

Back down on Earth, it's X-rays that have transformed our visible world,

letting us see it in a completely new way.

The idea of using X-rays comes from a very simple property of light.

We see the world around us because visible light bounces off objects

and enters our eyes where receptors in our retina can detect it.

Switch that light off and...

..nothing.

To see beneath the surface of things we need light that's powerful enough

to pass through objects. It's a bit like when light from a torch

passes through your hand and sort of hints at the shape of

the bones beneath. But to really see that I outline clearly,

we need something more powerful, much, much more powerful,

and that's what light in the X-ray part of the spectrum offers.

This is one of the world's most advanced X-ray machines

and what it allows seems like pure science fiction - X-ray vision

in high speed and high definition.

For the first time, we can see exactly how the body works in motion

and we can explore some of the mysteries of the inner workings of

everything from a man in a vest

to a myriad of animals.

A rat, for example, can clamber up this chain with ease, but it's only

with X-ray vision that the secrets of its superb agility become clear.

Rather than making its legs

do all the work it flexes its back like a caterpillar,

bending its spine to lift most of its body weight.

Yeah, that's how they got the plague on ships, like that.

A moving X-ray shows a unique feature of the chameleon.

It's the only lizard that can climb narrow branches

because of an extraordinarily mobile shoulder that allows it to twist its

legs inwards to grasp the branch.

Oh, vest man's back!

Even a quail is quite interesting when seen in X-ray vision.

Look, it's carrying an egg!

With this astonishing X-ray vision,

we can understand the precision engineering of a top athlete,

like this man in a vest, and see how it compares to some of

the extraordinary abilities of the animal kingdom.

As humans, we get along by being just good enough at a huge number

of different things, but that's a very different approach to the

specialised movement of a predator evolved to hunt and to kill.

You might not think of your pet cat as a supreme gymnast,

but that's exactly what it is.

Even the most powerful human athletes

struggle to jump safely much beyond twice their height.

But a cat can comfortably fall more than ten times its height

and stroll away to sleep on the shed roof as if nothing has happened.

Now we can see why.

The human body has minimal cushioning in the knees and ankles,

little flexibility in these joints to absorb the impact of landing.

But a cat is very different.

First, a cat's ear isn't just for detecting when you're using

a tin opener. It works like an ultra fast gyroscope, telling it which way

is up so it can twist in the air and always land feet first.

But it's in the mechanics of the skeleton where

the difference really lies.

These are the first ever images to show how a cat really works.

The muscles holding the shoulder joint stretch

and then the shoulder blade comes up

moving right up beyond the body.

It's the perfect shock absorber

and, like being able

to sleep on the sofa for 18 hours, it's unique to cats.

The everyday world would look

rather different if we could see the X-ray part of the spectrum,

and that's just one of many invisible worlds out there.

Just beyond violet in the rainbow lies ultraviolet.

It's completely invisible to us,

but not to certain animals.

Here's the vole. It uses splashes

of urine to mark out territories in the undergrowth where it lives.

The urine has its own smell

of course, but to us it is completely invisible.

The clever thing about vole wee is that it contains special pigments

that reflect ultraviolet light.

What to us appears to be an ordinary patch of grass

is really packed with bright markings.

The fresher the splashes of urine the stronger the UV signature.

The urine tells other voles how fresh a path is,

even the sex of the animal that left it.

But there's a twist to this

invisible pee talk because whilst it is very useful to the voles, there's

another animal taking an interest in their secret communications.

To the kestrel this is dinner.

But first he's got to find it.

A vole's visible colourings are perfect camouflage against

the background, which means it's incredibly difficult to spot,

even for a bird with eyes as good as a kestrel.

Unfortunately for the vole, a kestrel can see in ultraviolet.

And in ultraviolet, the location of the vole is blindingly obvious

leading the kestrel straight to the main cause.

The invisible world of ultraviolet

has many other things to reveal about the life of animals.

Alongside the garden that we see,

there's an invisible garden, a garden of hidden signs

and codes, all designed to attract the interest of passing insects.

That's because insects can't see

our world clearly at all, but they can see ultraviolet.

Take the honey bee.

Many flowers need bees in order to pollinate.

No visits from bees, no pollination,

no pollination, no reproduction, so it's actually a matter of survival.

And flowers have had to learn to advertise themselves to bees

in a way that bees can understand

because to the bee this garden looks very different.

For the first time, high-definition cameras can give us

a bee's view of the garden

revealing hidden patterns in flowers that are normally invisible

to humans.

Patterns that to us are completely invisible.

Seen in ultraviolet, new markings appear on the flowers,

like secret ink.

The markings are caused by special compounds in

the flowers called flavonoids.

To the bees, they're like aircraft landing lights

guiding them straight

into the nectar and pollen at the heart of the flower.

But if there's this ultraviolet world

all around us why can't we see it?

The answer lies in the evolution of

this,

the eye. That's not the human eye, that is, was, a pig's eye, but

physiologically very similar to ours.

So at the front there's this, the cornea, it's a protective layer.

And then behind it...

It's all right, I'm cringing, too.

Behind the protective cornea

is the lens.

That is what plays

such a crucial part in determining what light gets through to our eye.

But it's not just about letting light through, it's evolved

to be a filter, filtering out ultraviolet light that could,

over time, harm our eye.

That's perhaps why the kestrel can see ultraviolet,

because their lifespan is short.

They wouldn't be alive long enough for the ultraviolet light

to harm their eyes, so they haven't evolved the filter.

But there are a few rare individuals who lack that filter

and so can get a glimpse right into that invisible realm.

Alan Bradley's whole career has been based on vision.

As a television engineer, he specialised in translating

the world we can see into the pixels of light on our television screens.

I have always had an absolute gripping fascination with light.

Light has always been the whole world to me.

In 2003 Alan had

an operation to remove cataracts and replace the lenses in his eye.

It had a rather weird side effect.

The operation was successful,

but something else seemed to have happened to his sense of sight.

I was in the store and had gathered up a basket of fruit

and veggies and walked up to the cash register at the front of the store.

As he approached the checkout Adam was suddenly exposed to

a strange glow of a kind he'd never previously seen.

The effect was like having someone

punch you hard on the end of the nose.

It was like receiving an electric shock through the eyes.

What Alan was seeing was ultraviolet light

from the shop's blacklight used to detect fake banknotes.

Normally the lens in our eyes blocks ultraviolet,

but Alan's new artificial lens was somehow allowing it through.

One of the eyes was seeing the bulb in a deep purple,

as most people see a blacklight.

To the other eye it looked fluorescent blue,

it had a glow around it like blue purple neon.

Alan suddenly has a view of the world most of us will never share.

I see things that I could never have dreamed of before.

This happens looking at the raindrops with sun coming through them.

In rainbows there is this shimmering fragmented part of the spectrum,

which is much more enhanced than anything that I ever saw before.

Alan Bradley's operation transformed his sense of sight beyond

what he'd ever imagined to be possible.

100 years ago, cataracts were dealt with in a less sophisticated way.

They simply took out the lens altogether.

This is a work by the French impressionist painter Claude Monet,

famous for his use of blazing, swirling colours.

Late in Monet's life, a cataract in his right eye began to

affect his sight and he agreed to an operation to remove the lens.

You can see in his paintings that it completely changed

his perception of colour.

With his left eye, he painted this,

but in the right eye that was missing the lens

that same garden looked

very different, swathed in a bluey-white wash.

Maybe he'd run out of red paint!

The more likely answer is that he too was able to see in ultraviolet.

Being able to see the invisible spectrum beyond the naked eye

has shown us the wider world all around us.

How cats work, how flowers are really tiny advertising hoardings.

These are the secrets X-rays and ultraviolet can reveal.

But further along the spectrum, just beyond red, lies infrared

and if we could see this part of the spectrum, it would transform

our understanding of the world.

This, as you can probably tell, is a forest fire.

It's one of the most frighteningly destructive

forces of nature on the planet.

'Hundreds of homes have been...'

'Bush fires are raging out of control across thousands of acres...'

Once it takes hold, a fire like this is almost impossible to put out.

That is terrifying.

It really is terrifying in there, but I know I'm perfectly safe.

I'm wearing protective gear, I know the name of the pyrotechnic

guy who's controlling the flames, but fire, it is the most elemental

and destructive force on the planet so we see it, we're scared.

But just the sight of it is not the full story. To really appreciate

what's going on in there we need to see into the invisible.

Even before the fire reaches, say,

a branch on a tree, something's already happening that we can't see.

Seen in infrared, the branch looks like it's already on fire.

What we're seeing here is a build-up of heat before any flames appear,

but what's really crucial it's what's happening around the branch.

Super hot gases

in the air catch fire first and they ignite the branch.

There it goes.

Watching something burn it's easy to think that

the flames are actually on the thing that's burning, eating away at it,

because that's what it looks like, but it's not that simple.

What's happening is the heat is causing the object to give off

combustible gases and as they escape it's those combustible gases

in contact with the oxygen in the air that cause the fire.

So those flames are not in the thing that's burning,

they're in the air around it.

That's why fire can spread so quickly as waves of super hot gases,

fanned by the wind, set fire to everything they touch.

HELICOPTER WHIRS

Stopping a forest fire before that can happen is vital.

We can head over to our left and look at what's along that clearing.

Here in the wilds of Alberta

firefighters fly over the forest

looking for the first signs of trouble.

We try and catch the wildfire while it's small so that it doesn't grow to

a size that we can no longer manage.

It could be just as small as one tree burning, so

we have to spot one tree in a forest.

It's not what you'd call a relaxing job,

but seeing into the invisible could

make it a lot easier, and that's where this small animal comes in.

This is the jewel beetle and, weirdly, while every

other animal is fleeing the blaze

this extraordinary creature has travelled miles to find it.

It has a strange fire-detecting super sense

that no human could match.

We look at this and see, well, trees, but look at it in infrared

and a fire is screaming its presence.

The visible fire may be hidden deep within the forest,

but even a small fire has an infrared signature.

Close up, we can sense this radiation as heat,

but the fire is transmitting infrared much further than this.

Long-wave infrared from the fire travels vast distances

and it's this a beetle can detect, allowing it to sense fires from

as far as 50 kilometres away.

The jewel beetle is tuned to this long-range infrared light thanks to

two tiny pit organs on its chest, each containing some 70 sensors.

Now scientists are copying the beetle's extraordinary infrared

super sense to spot the very first sign of forest fires from the air.

And even from space.

Thousands of miles above the Earth infrared sensors on satellites

can detect forest fires, showing them clearly as hotspots.

If firefighters could routinely

harness this new technology, it would revolutionise their job.

Ideal situation is if we

did have eyes in the sky essentially so that we can try and catch the fire

early enough to be able to put it out at a small size.

Infrared is also bringing to light

some amazing things about the natural world.

Take the honey bee. You might think of these as

just slightly annoying creatures that can ruin a picnic.

But with its worker bees, drones and queen a beehive is like mine,

a collective intelligence as powerful as the biggest computer,

except that your PC doesn't make honey.

Bees are amazing.

It might look like chaos in there,

but in fact inside that humble wooden box is one of

the most sophisticated living things in the history of evolution.

One bee on its own might not add up to much,

but taken together a very different picture emerges.

To really appreciate the brilliance

of this super organism, of how it works and controls the environment

around it, you need to see into the invisible realm.

Seen normally, all these bees may look the same,

but go beyond the visible into the infrared

and some bees are warmer than others.

Some glow bright orange

like hot coals, radiating heat to their surroundings,

others are dark and cool.

Looking beyond what our eyes can usually see into the realms

of the invisible reveals it's the precise control of heat that allows

a bee colony to be such a unique and successful form of organisation.

But what exactly is all this heat for?

Well, look closely and the infrared camera reveals how heat

is concentrated in one central area, the brood nest at the heart of

the hive where young bee pupae are growing.

This bee might seem relatively still, but seen in infrared

it's bright orange, revealing its role as a specialist heater bee.

The bee warms itself up by vibrating its flight muscles,

vibrations that allow it to reach up to 44 degrees centigrade,

previously thought to be high enough to kill it.

Others that seem like they might be grabbing a quiet snooze

are actually tight little balls of fire.

They're doing this because they have a special role to mother these young

by keeping them warm, because without that warmth

these babies can't grow and develop.

And now we know why bees much spend so much time foraging for the nectar

that will be turned into honey,

because it's honey that fuels these heater bees.

Two thirds of the hive's honey goes on that central heating

to keep the young warm.

This rarely-seen moment captured in infrared shows how exhausted

heater bees are topped up with fresh reserves of honey by refuelling bees

before, recharged, they return to their task of providing that warmth.

These images have revealed something extraordinary.

By precisely controlling the temperature, these heater bees

control the destiny of the young.

Incubated at 34 degrees

this newly-born bee is likely to become a humble housekeeper,

but kept just 1.5 degrees higher, it may instead turn into

an intelligent forager, living up to ten times longer.

None of these amazing new discoveries would have been possible

without that ability to see beyond our visible spectrum

into the secrets of the hive.

It's not just the behaviour of

honey bees that the infrared spectrum helps to reveal.

Right across the animal kingdom there are creatures we can only

fully understand by looking into this part of the invisible world.

These caves in the southern United States have been home to

the free-tailed bat for over 5,000 years.

But what they get up to in here has always been a mystery

because as soon as scientists turn on a light to see them,

their natural behaviour changes.

BAT WINGS FLUTTER

Every evening, at dusk, tens of thousands of bats

pour out of the cave entrance to search for food.

It looks like utter chaos,

but infrared cameras have made it possible to see through the darkness

and it turns out that this isn't chaos at all.

Instead, the bats stick to specific flight paths as they climb in

a spiral out of the cave and return back again.

Once inside the cave,

the infrared camera reveals how these bats really live.

The bright orange bits are actually

hundreds of thousands of bats hanging from the cave ceiling.

That's half a million bats crammed into just 200 square metres.

But it's not that they're short of space.

The intense orange shows that they're regulating their temperature

by huddling together for warmth.

And looking into the infrared gives a new insight into bat behaviour.

These colder dark blue areas are their wings.

We know that they need to stretch and beat them in a vital warm-up

before taking to the air.

In every street of every town, the invisible world is all around us.

If our eyes could see into the infrared part of the spectrum

your kitchen would suddenly become an insane world

of hidden forces and actions.

These are swirling air currents propelled by the heat of our bodies.

And here, beyond our normal vision,

is the very moment an egg transforms.

Around 80 degrees Celsius, the proteins in the egg crumple.

It's this that turns the white of an egg, well, white!

We can see the dull red glow of a heating element,

but what we can't see is the vast outpouring of infrared light...

..triggering the formation

of a molecule called acetyl tetrahydropyridine...

giving us toast.

Toasting, boiling, cooking -

things that are only possible thanks to the invisible world of infrared.

Infrared and ultraviolet are quite close to the visible spectrum.

Now we're travelling much further along it,

right out to the far reaches of the invisible world

to a part of the light spectrum

that has utterly changed our modern world -

radio waves.

Yes, they're part of the light spectrum, too.

When German physicist Heinrich Hertz discovered radio waves in 1857

his students may have been impressed, but he wasn't.

This is what he said,

though he actually said it in German, obviously.

"We just have these mysterious electromagnetic waves

"that we cannot see with the naked eye, but they are there.

"They're of no use whatsoever".

Yeah, mobile phones, television, radio, all these things

use something that's of no use whatsoever.

Radio waves have changed the world we live in,

transmitting conversations, music, pictures, information

sometimes over thousands of miles and in thousands of different ways,

but, because we can't see, or smell, or feel them,

it's easy to forget just how fundamental they are

to our modern way of life.

INDISTINCT RADIO TRANSMISSIONS

The air around us might look completely empty

when, in fact, it's anything but.

If we could actually see it, we'd realise just how crowded

our 21st century airwaves have become.

And, happily, scientists like this man

can precisely measure those signals so that we can visualise

this invisible world all around us.

Mum, hello.

Yes.

This is a world that's almost entirely man-made.

Natural sources of radio waves on Earth are very rare,

they're mostly made by extreme weather like lightning, but the

air around us is crammed with the radio traffic of the 21st century.

Every mobile phone is its own little radio transmitter.

Things as varied as microwave ovens and the WiFi for your computer

all work by radio.

Whenever you lock or unlock your car that's a radio pulse in action.

In fact, there are now hundreds of different applications

pouring out radio waves.

At any one time, there could be thousands, hundreds of thousands

or even millions of discrete messages being transmitted.

BABBLE OF MIXED RADIO TRANSMISSIONS

Radio has turned the empty air around us

into a dense, crowded web of invisible signals,

which really isn't bad for something with no use whatsoever(!)

Seeing into this part of the spectrum

is helping us understand more than our own planet.

It's revealing the mysteries of the entire universe,

answering some of the most fundamental questions of all.

Look up into the night and, even if you're lucky and it's a clear one,

there's not really that much to see.

Stars, a few galaxies maybe.

But that image we have of the night sky is very limited

because beyond that visible picture

there's another far more detailed one.

But to see that for yourself you need help.

You need one of these, a telescope designed to see the invisible.

Telescopes like this one at Jodrell Bank,

are transforming our view of the universe...

..allowing scientists for the first time to see into the depths of space

far beyond what our eyes can see.

This is an image of our Milky Way in the visible spectrum.

Visible telescopes can do much better than the naked eye,

but there are still large areas of it that appear entirely dark.

That's because much of space is filled with, well, dust basically,

cosmic debris from dead stars, and this dust blocks our view,

so this is pretty much the limit of what we can see

with a bit of assistance in the visible part of the spectrum.

But now, a new generation of telescopes are able to look at

that very same image of our visible Milky Way

in other parts of the spectrum.

From radio to gamma rays,

X-rays and infrared.

These aren't just a series

of cool images, they offer a more revealing picture

of our universe. Take this area of space.

The visible spectrum reveals a shadowy gas cloud...

..but seeing into the infrared reveals a dense concentration

of stellar material.

This is the very process that forms new stars.

Five, four,

three, two, one and liftoff of the Space Shuttle Discovery.

The dawn of the Space Age has allowed scientists to see

even further into the invisible sky.

Telescopes in orbit around the Earth can detect light

from the furthest parts of space, like X-rays and gamma rays.

Here's another image of the visible sky,

but seen in X-ray it revealed this.

This extraordinary image

shows nothing less than the death of a star.

You'd think that space was empty and quiet.

Actually, it's violent and dynamic and explosive.

This is the control room at Jodrell Bank,

still at the forefront of modern astronomy,

but on top of the discoveries of this generation of telescopes

there's a whole new generation of monster telescopes

being built to see even further into the invisible.

And now they're helping probe one of the most fundamental

and intriguing mysteries of the universe,

the presence of black holes.

Now, I don't wish to be alarmist

but, according to theory, there should be a super massive black hole

right at the centre of our own galaxy.

A central dark mass

around which the galaxy was formed, but, well, how do you find it?

It sounds obvious when you think about it, but seeing a black hole

is an immense challenge for the simple reason a black hole

doesn't emit ANY light from ANY part of the spectrum.

In a sense, it's the ultimate invisible object.

So, finding it is, as you'd imagine, quite tricky

unless of course you've got

one of the world's most powerful invisible telescopes.

And here in the high Andes of Chile, that's exactly what this is.

Looking into the infrared, astronomers began probing

deeper and deeper into one tiny and precise patch of sky.

And, finally,

they discovered a collection of stars apparently locked in orbit

around a vast area

of nothing.

They'd found it, a super massive black hole,

three million times bigger than the Sun,

right at the heart of our own Milky Way.

Being able to see what was once invisible

helps us to unlock the great mysteries of the universe -

where it came from, where it's heading

and the sheer scale of a cosmos where our Sun

is just one lonely star in a galaxy of 100 billion,

and our galaxy just one

of 100 billion others across the known universe.

But even if planet Earth is just one tiny planet

in that vast, vast universe,

seen across that invisible spectrum

from ultraviolet...

to infrared and beyond...

..it's shown to be a rather wonderful and remarkable one.

So the next time you step out of your front door into the world,

remember, there's whole lot more going on around us

if only we could see it.

Thank you.

Subtitles by Red Bee Media Ltd.

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