NARRATOR: Our world, warm, comfortable, familiar...
...but when we look up, we wonder:
Do we occupy a special place in the cosmos?
Or are we merely a celestial footnote?
Is the universe welcoming or hostile?
We could stand here forever, wondering.
Or we could leave home, on the ultimate adventure.
To discover wonders.
Confront horrors.
Beautiful new worlds.
Malevolent dark forces.
The beginning of time.
The moment of creation.
Would we have the courage to see it through?
Or would we run for home?
There's only one way to find out.
Our journey through time and space begins with a single step.
At the edge of space, only 60 miles up...
...just an hour's drive from home.
Down there, life continues.
The traffic is awful, stocks go on trading...
...and Star Trek is still showing.
When we return home, if we return home...
...will it be the same?
Will we be the same?
We have to leave all this behind.
To dip our toes into the vast dark ocean.
On to the Moon.
Dozens of astronauts have come this way before us.
Twelve walked on the Moon itself.
Just a quarter of a million miles from home.
Three days by spacecraft.
Barren.
Desolate.
It's like a deserted battlefield.
But oddly familiar.
So close, we've barely left home.
Neil Armstrong's first footprints.
Looks like they were made yesterday.
There's no air to change them.
They could survive for millions of years.
Maybe longer than us.
Our time is limited.
We need to take our own giant leap.
One million miles, 5 million, 20 million miles.
We're far beyond where any human has ever ventured.
Out of the darkness, a friendly face.
The goddess of love, Venus.
The morning star.
The evening star.
She can welcome the new day in the east...
...say good night in the west.
A sister to our planet...
...she's about the same size and gravity as Earth.
We should be safe here.
But the Venus Express space probe is setting off alarms.
It's telling us, these dazzling clouds, they're made of deadly sulfuric acid.
The atmosphere is choking with carbon dioxide.
Never expected this. Venus is one angry goddess.
The air is noxious, the pressure unbearable.
And it's hot, approaching 900 degrees.
Stick around and we'd be corroded, suffocated, crushed and baked.
Nothing can survive here.
Not even this Soviet robotic probe.
Its heavy armor's been trashed by the extreme atmosphere.
So lovely from Earth, up close, this goddess is hideous.
She's the sister from hell.
Pockmarked by thousands of volcanoes.
All that carbon dioxide is trapping the Sun's heat.
Venus is burning up.
It's global warming gone wild.
Before it took hold, maybe Venus was beautiful, calm...
...more like her sister planet, Earth.
So this could be Earth's future.
Where are the twinkling stars?
The beautiful spheres gliding through space?
Maybe we shouldn't be out here, maybe we should turn back.
But there's something about the Sun, something hypnotic, like the Medusa.
Too terrible to look at, too powerful to resist.
Luring us onwards on, like a moth to a flame.
Wait, there's something else, obscured by the Sun.
It must be Mercury.
Get too close to the Sun, this is what happens.
Temperatures swing wildly here.
At night, it's minus 275 degrees...
...come midday, it's 800 plus.
Burnt then frozen.
The MESSENGER space probe is telling us something strange.
For its size, Mercury has a powerful gravitational pull.
It's a huge ball of iron, covered with a thin veneer of rock.
The core of what was once a much larger planet.
So where's the rest of it?
Maybe a stray planet slammed into Mercury...
...blasting away its outer layers in a deadly game of cosmic pinball.
Whole worlds on the loose careening wildly across the cosmos...
...destroying anything in their path.
And we're in the middle of it.
Vulnerable, exposed, small.
Everything is telling us to turn back.
But who could defy this?
The Sun in all its mesmerizing splendor.
Our light, our lives...
...everything we do is controlled by the Sun.
Depends on it.
It's the Greek god Helios driving his chariot across the sky.
The Egyptian god Ra reborn every day.
The summer solstice sun rising at Stonehenge.
For millions of years...
...this was as close as it got to staring into the face of God.
It's so far away...
...if it burned out, we wouldn't know about it for eight minutes.
It's so big, you could fit one million Earths inside it.
But who needs numbers? We've got the real thing.
We see it every day, a familiar face in our sky.
Now, up close, it's unrecognizable.
A turbulent sea of incandescent gas.
The thermometer pushes 10,000 degrees.
Can't imagine how hot the core is, could be tens of millions of degrees.
Hot enough to transform millions of tons of matter...
...into energy every second.
More than all the energy ever made by mankind.
Dwarfing the power of all the nuclear weapons on Earth.
Back home, we use this energy for light and heat.
But up close, there's nothing comforting about the Sun.
Its electrical and magnetic forces erupt in giant molten gas loops.
Some are larger than a dozen Earths.
More powerful than 10 million volcanoes.
And when they burst through, they expose cooler layers below...
...making sunspots.
A fraction cooler than their surroundings, sunspots look black...
...but they're hotter than anything on Earth.
And massive, up to 20 times the size of Earth.
But one day, all this will stop.
The Sun's fuel will be spent.
And when it dies, the Earth will follow.
This god creates life, destroys it...
...and demands we keep our distance.
This comet strayed too close.
The Sun's heat is boiling it away...
...creating a tail that stretches for millions of miles.
It's freezing in here.
There's no doubt where this comet's from, the icy wastes of deep space.
But all this steam and geysers and dust...
...it's the Sun again, melting the comet's frozen heart.
Strange.
A kind of vast, dirty snowball, covered in grimy tar.
Tiny grains of what looks like organic material...
...preserved on ice, since who knows when...
...maybe even the beginning of the solar system.
Say a comet like this crashed into the young Earth billions of years ago.
Maybe it delivered organic material and water...
...the raw ingredients of life.
It may even have sown the seeds of life on Earth...
...that evolved into you and me.
But say it crashed into the Earth now.
Think of the dinosaurs, wiped out by a comet or asteroid strike.
It's only a question of time.
Eventually, one day, we'll go the way of the dinosaurs.
If life on Earth was wiped out, we'd be stuck out here...
...homeless, adrift in a hostile universe.
We'd need to find another home.
Among the millions, billions of planets...
...there must be one that's not too hot, not too cold, with air, sunlight, water...
...where, like Goldilocks, we could comfortably live.
The red planet.
Unmistakably Mars.
For centuries, we've looked to Mars for company...
...for signs of life.
Could there be extraterrestrial life here?
Are we ready to rewrite the history books, to tear up the science books...
...to turn our world upside down?
What happens next could change everything.
Mars is the planet that most captures our imagination.
Think of B-movies, sci-fi comics, what follows?
Martians?
It's all just fiction, right?
But what if there really is something here?
Hard to imagine, though. Up close, this is a dead planet.
The activity that makes the Earth livable shut down millions of years ago here.
Red and dead.
Mars is a giant fossil.
Wait. Something is alive.
A dust devil, a big one.
Bigger than the biggest twisters back home.
There's wind here.
And where there's wind, there's air.
Could that air sustain extraterrestrial life?
It's too thin for us to breathe.
And there's no ozone layer.
Nothing to protect us against the Sun's ultraviolet rays.
There is water...
...but frigid temperatures keep it in a constant deep freeze.
It's hard to believe anything could live here.
Back on Earth, there are creatures that survive in extreme cold, heat...
...even in the deepest ocean trenches.
It's as though life is a virus.
It adapts, spreads.
Maybe that's what we're doing right now...
...carrying the virus of life across the universe.
Even in the most extreme conditions, life usually finds a way.
But on a dead planet?
With no way to replenish its soil, no heat to melt its frozen water?
All this dust, it's hard to see where we're going.
Olympus Mons, named after the home of the Greek gods.
A vast ancient volcano.
Three times higher than Everest.
There's no sign of activity.
Since its discovery in the 1970s, it's been declared extinct.
Hang on.
These look like lava flows.
But any sign of lava should be long gone, obliterated by meteorite craters.
Unless, this monster isn't dead, just sleeping.
There could be magma flowing beneath the crust right now...
...building up, waiting to be unleashed.
Volcanic activity could be melting frozen water in the soil...
...pumping gases into the atmosphere, recycling minerals and nutrients.
Creating all the conditions needed for life.
This makes the Grand Canyon look like a crack in the sidewalk.
Endless desolation...
...so vast it would stretch all the way across North America.
But here, signs of activity, erosion, and what looks like dried up river beds.
Maybe volcanic activity melted ice in the soil...
...sending water gushing through this canyon.
Underground volcanoes could still be melting ice, creating water.
And where there's water, there could be life.
The hunt for life is spearheaded by this humble fellow...
...the NASA rover, Opportunity.
It's finding evidence that these barren plains...
...were once ancient lakes or oceans that could have harbored life.
Look at those gullies.
Probes orbiting Mars keep spotting new ones.
More proof that Mars is alive and kicking...
...that water is flowing beneath its surface right now.
Water that could be sustaining Martian life.
Now, all we have to do is find it.
Maybe we've already found what we're looking for on Earth.
Some think that life started here and then migrated to Earth.
An asteroid impact could've blasted fragments of Mars...
...complete with tiny microbes out into space...
...and onto the young Earth where they sowed the seeds of life.
No wonder we find Mars fascinating, this could be our ancestral home.
It could be we are all Martians.
The Mars we thought we knew is gone...
...replaced by this new, active, changing planet.
And if we don't know Mars, our next door neighbor...
...how can we even imagine what surprises lie ahead?
Our compass points across the cosmos...
...back in time 14 billion years...
...to the moment of creation.
This is getting scary.
It's like being inside a giant video game.
But these are all too real.
Asteroids, some of them hundreds of miles wide.
This one must be about 20 miles long.
And there, perched on it, a space probe.
Can't have been easy...
...parking on an asteroid traveling at 50,000 miles an hour.
It's a lot of effort just to investigate some rubble.
Rubble that regularly collides...
...breaks up and rains down on Earth as meteorites.
Our ancestors saw shooting stars as magical omens.
And they were right.
Rubble like this came together to make the planets...
...including our own.
Pretty magical.
By dating the meteorites found on Earth...
...we can tell the planets were born 4.6 billion years ago.
These are the birth certificates of our solar system.
For some reason, these rocks didn't form into a planet.
Something must have stopped them.
Something powerful.
Jupiter.
What a monster.
At least a thousand times bigger than Earth...
...so vast you could fit all the other planets inside it.
Something this massive dominates its neighbors.
Its gravity is pulling the asteroids apart.
And it's breathtaking.
But this beauty is a beast.
It's almost all gas.
Land here and we'd sink straight through its layers into oblivion.
And Jupiter's good looks?
The product of ferocious violence.
It's spinning at an incredible rate...
...whipping up winds to hundreds of miles an hour...
...contorting the clouds into stripes, eddies, whirlpools...
...and this, the legendary Great Red Spot.
The biggest, most violent storm in the solar system.
At least three times the size of Earth, it's been raging for over 300 years.
All these churning clouds must have sparked an electrical storm.
Just one bolt is 10,000 times more intense than any at home.
Looks like the safest place to see Jupiter is from a distance.
Up there at the poles...
...those dancing lights, they're like the auroras back home.
But the Geiger counter is going wild.
Even these are deadly, generated by lethal radiation.
Out here, nothing is what it seems.
The universe is full of terrors, traps.
Maybe this is a safe haven, the multi-colored moon, Io.
Wrong.
Very wrong.
Those brilliant colors are molten rock, volcanoes spewing lava.
Our journey across the universe is turning into a struggle for survival.
We've got to hope that if we outlast the dangers...
...we'll be rewarded by wonders beyond imagination.
Four hundred million miles from Earth...
...flying a commercial airliner here would take nearly a century.
What a weird looking place...
...and yet, strangely familiar.
A bit like the Arctic, with all that ice, all those ridges and cracks.
It's Jupiter's moon, Europa.
And maybe, like the Arctic, this ice is floating on water, liquid water.
But we're half a billion miles from the Sun.
Surely, Europa is frozen solid.
Unless, Jupiter's gravity is creating friction deep inside...
...heating the ice into water, allowing life to develop in the waters...
...beneath its frozen crust.
We might be feet away from aliens.
From a whole ecosystem of microbes, crustaceans, maybe even squid.
The only thing between us and the possibility of alien life...
...this layer of ice.
But until we send a spacecraft to drill here...
...Europa's secrets will remain beyond reach.
It's captivated our imaginations, haunted our dreams.
And here it is, spinning before our eyes.
Saturn.
Named for the Roman god...
...who reigned over a golden age of peace and harmony.
This planet's a giant ball of gas, so light it would float on water.
Its spectacular rings would stretch almost from Earth to the Moon.
There's the Cassini orbiter.
It's picking up ghostly radio emissions.
Probably generated by auroras around Saturn's poles.
This is the real music of the spheres.
[HISSING PLAYING OVER RADIO]
Cassini's telling us where these rings came from.
They're the remnants of a moon shattered by Saturn's gravitational pull.
Incomparable beauty from total destruction.
Billions of shards of ice.
Some as small as ice cubes, others the size of houses.
They collide, break apart, reassemble.
It's like a snapshot of our early solar system...
...as dust and gas orbited the newly born Sun...
...and gravity worked its magic, pulling the lumps together...
...until from space trash like this, our home emerged.
We could stay here forever.
But there's so much further to go, so much more to see.
Like this moon wrapped in thick clouds, Titan.
There's an atmosphere down here.
There's wind, rain, even seasons.
Rivers, lakes and oceans.
It looks so familiar, so similar to Earth.
[THUNDER RUMBLING]
But that's not water, it's liquid natural gas.
Hundreds of times more natural gas than all the Earth's oil and gas reserves.
Maybe, one day, we'll use this energy to fuel a colony.
Assuming there isn't life here already.
The Huygens space probe is here to find out.
It's telling us there's organic material in the soil.
But it's so cold, minus 300 degrees.
There's no way life could develop.
Unless Titan warms up.
The Sun is supposed to get hotter.
When it does, maybe life will spring up here...
...just like it did on Earth.
And as the Earth gets too hot for us, maybe we'll move to Titan.
One day, we might call this distant land home.
Home.
We're at least 700 million miles away now.
After this, we lose visual contact with Earth.
We're standing on a cliff.
Looking out over a great chasm that stretches to the beginning of time.
Do we have the courage to jump?
We're in the solar system's outer reaches.
Unseen from Earth, unknown for most of history.
It's like diving into the depths of the ocean.
Those rings make it look like Uranus has been tilted off its axis...
...toppled over by a stray planet.
It's eerie out here.
Already beginning to feel small, lonely.
Maybe this is how we'll feel at the edge of the universe.
But we've barely left the shore.
If the solar system was one mile wide, so far we've traveled about 3 inches.
Out of the deep, another strange beast...
...the god of the sea, Neptune.
This world is covered in methane gas.
And a storm as big as Earth...
...whipped up by savage thousand mile-an-hour winds.
Back home, it's the Sun that drives the wind...
...but Neptune's far away.
Something else must be creating these ferocious winds.
But what?
We know very little about our own solar system.
After all those balls of gas, a solid moon...
...Triton.
Solid but not stable.
Just look at those geysers...
...cosmic smokestacks pumping out strange soot.
And this moon is revolving around Neptune...
...in the opposite direction of the planet's spin.
A cosmic battle of wills...
...that this angry moon is destined to lose.
Neptune's massive gravity is pulling on Triton.
Slowing it down, reeling it in.
One day, it will be ripped apart by Neptune.
And that's it.
No more moons, no more planets in our solar system.
It's getting colder, we're getting further from the Sun...
...slipping from the grip of its gravitational tentacles.
But this isn't a void.
It's teeming with frozen rocks.
Like Pluto.
Until recently, we thought Pluto was alone.
Beyond it, nothing.
We were wrong.
More frozen worlds.
Discoveries so new nobody can agree what to call them.
Plutinos, ice dwarves, cubewanos.
Our solar system is far more chaotic and strange than we had imagined.
Now we're 8 billion miles from home.
The most distant thing ever seen that orbits the Sun...
...another small, icy world, Sedna, discovered in 2003.
Its orbit takes 10,000 years to complete.
Hang on, there's something else out here.
Ten billion miles from home the space probe, Voyager 1.
This bundle of aluminum and antennae...
...gave us close up views of the giant planets...
...and discovered many of their strange moons.
It's traveling 20 times faster than a bullet, sending messages home.
That gold plaque...
...its a kind of intergalactic message in a bottle.
A greeting recorded in different languages.
BOY [OVER RADIO]: Hello, from the children of planet Earth.
[MAN AND WOMAN SPEAKING IN FOREIGN LANGUAGES OVER RADIO]
NARRATOR: And a map showing how to find our home solar system.
The great physicist, Stephen Hawking...
...thinks it was a mistake to roll out the welcome mat.
After all, if you're in the jungle, is it wise to call out?
These comets look like the ones we saw earlier.
There's a theory that the raw materials for life began out here...
...on a rock like this until something dislodged it...
...sending it hurtling towards the Earth.
And seeing all this ice, maybe comets carried water to Earth too.
The water in the oceans, in your body...
...all from this distant celestial ice machine.
We're 5 million, million, that's 5 trillion miles from home.
But this is still only a baby step.
Ahead, trillions of miles, billions of stars.
Time to stop looking back and start looking ahead...
...to step out into the big, wide universe.
Interstellar space.
Billions of stars like our own Sun...
...many with planets, many of those with moons.
It's hard to know which way to go.
There are infinite possibilities.
We're going to need a serious burst of acceleration.
Twenty-five trillion miles from home.
A 150,000-year ride in the space shuttle.
And we've only just reached the first solar system beyond our own...
...Alpha Centauri.
Not one but three stars.
Spinning around each other, locked in a celestial standoff.
Each star's gravity attracting the other...
...their blazing orbital speed keeping them apart.
Get between them and we'd be vaporized...
...trillions of miles from home.
So far that miles are becoming meaningless.
Out here, we measure in light years.
Light travels 6 trillion miles a year...
...so we are over four light-years from home.
Distances so vast they're mind-boggling.
Who knows what strange forces lie ahead...
...what we'll discover when--
If we reach the edge of the universe.
Ten light years from Earth, the star Epsilon Eridani.
Spectacular rings of dust and ice.
And somewhere in there, planets forming out of the debris...
...being born before our eyes.
Asteroids and comets everywhere.
We could almost be looking at our own solar system...
...billions of years ago.
With comets delivering the building blocks of life...
...to these young planets.
At the center of all the action, a star smaller than our sun...
...still in its infancy.
Any life in this solar system would be primitive at best.
There must be more mature solar systems out here...
...but finding them is like looking for a needle in a cosmic haystack.
Twenty light years from Earth.
Star Gliese 581.
It's about the same age as our sun.
This planet is just the right distance from its sun.
Any closer and water would boil away, any further and it would freeze.
Ideal conditions for life to emerge.
And if a comet has struck, delivering water and organic materials...
...then life, complex beings like us, even civilizations like our own...
...could be down there right now.
They could be tuning into our TV signals...
...watching shows from 20 years ago.
MAN [OVER TV]: And here's your host, Joe....
[PEOPLE APPLAUDING ON TV]
NARRATOR: But until we devise a way of communicating...
...over these vast distances, all we can do is speculate.
Us and them, living parallel lives...
...unaware of each other's existence.
Unless life has come and gone.
That's the problem with comets.
They're creators and destroyers...
...as the dinosaurs found out the hard way.
This is the needle in the cosmic haystack...
...the closest we've come to a habitable solar system like our own...
...but it's a chance encounter.
There could be hundreds...
...millions more solar systems like this out there or none at all.
Some of the atmosphere on this planet, Bellerophon...
...is being boiled away by its nearby star.
From Earth, we can't see planets this far out.
They're obscured by the brilliance of their neighboring stars.
But the planets have a minute gravitational pull on those stars.
Measure these tiny movements and we can prove they exist.
That's how we tracked down Bellerophon in the 1990's...
...and hundreds of other distant planets.
Sixty-five light years from Earth...
...turn on your TV here and you'd pick up Hitler's Berlin Olympics.
[MAN SPEAKING IN GERMAN ON TV]
The twin stars of Algol.
Known to the ancients as the demon star.
From Earth, it appears to blink as one star passes across the other.
Up close, it's even stranger.
One star is being sucked towards the other.
Almost 100 light years from home...
...faint whispers from one of the first ever radio broadcasts.
[STATIC HISSES OVER RADIO]
MAN [OVER RADIO]: We'd appreciate it...
...if anyone hearing this broadcast would communicate with us.
We are very anxious to know how far the broadcast can reach.
NARRATOR: From here on out, it's as if the Earth never existed.
Feels like a lifetime since we stood on that beach...
...looking up at the sky, wondering where and how we fit in.
We've learned one thing for sure.
The universe is too bizarre, too startling...
...for us to guess what lies ahead.
Deep inside our galaxy, the Milky Way.
Pinpricks of light that have inspired a thousand and one tales.
The Seven Sisters, the daughters of the ancient Greek god, Atlas...
...transformed into stars to comfort their father...
...as he held the heavens on his shoulders.
And this giant, Betelgeuse.
The brightest, biggest star we've seen so far.
Six hundred times wider than our sun.
But this, it's not a star...
...not a planet, not like anything we've seen.
A ghostly specter, more than 1,300 light years from Earth...
...Orion's dark cloud.
Dust and gas shrouding us.
There, deep inside, a light, pulling the dust and gas towards it...
...heating up, merging into a ball of burning hot gas.
Like a star, like our sun in miniature.
Inside, it's millions of degrees.
So hot, it's beginning to trigger nuclear reactions...
...the kind that keep our sun shining...
...making energy, radiation, light.
A star is being born.
Orion's dark cloud is a vast star factory.
We're witnessing the birth of the future universe.
We've come to expect destruction...
...but this is one of the universe's greatest acts of creation.
Star birth.
This doesn't look right.
Jets of gas exploding out with tremendous force...
...blasting dust and gas out for millions of miles.
It's unbelievably violent and creative.
Nebula...
...vast glowing clouds of gas hanging in space.
With no wind out here, they'll take thousands of years to disperse.
They seem to be forming a vast stellar sculpture.
Nature is more than a scientist, an engineer...
...it's an artist on the grandest of scales.
And this is a masterpiece.
Stars are born, grow up, and then, then what?
Do they die?
Do they slip quietly into the night or go out with a bang?
Somewhere between here and the edge of the universe lies the answer.
Luminous clouds, suspended in space...
...encircling what was once a star like our own sun.
All that's left of it are these brightly colored gases...
...elements formed by nuclear reactions deep inside...
...released into space on its death.
Green and violet, hydrogen and helium...
...the raw materials of the universe.
Red and blue, nitrogen and oxygen...
...the building blocks of life on Earth.
For us to live, stars like this had to die.
Every atom in our body was produced by nuclear fusion...
...in stars that died long before the Earth was even born.
We are all the stuff of stars.
Our family tree begins here.
At its heart, the ghost of a star...
...a white dwarf.
White, hot, small...
...but unbelievably dense.
In the star's dying moments, its atoms fused and squeezed together...
...making it so dense that just a teaspoon of this white dwarf would weigh 1 ton.
It's a chilling premonition of our sun's fate.
Six billion years from now, it will become a white dwarf.
Its death will herald the end of life on Earth.
Makes you wonder how many other worlds have come and gone...
...celestial stories left untold, lost forever.
But the greatest story of them all is still to be told.
We must go back through time to the very first chapter...
...to learn how the universe began.
The scattered remains of a dead star...
...the Crab Nebula.
Six thousand light years from home, deep inside a stellar graveyard.
We've learnt so much...
...seen things we'd never have believed possible.
Now, sights like this, wonders once beyond imagination...
...we take in our stride.
We're ready to face whatever lies ahead.
Determined to reach the edge of the universe.
This is the calm after the storm, after a massive explosion...
...a supernova that turned a star into dust and gas.
The eye of the storm.
A spinning pulsating star, a pulsar.
The gravity has squeezed the giant star's core down to this.
It's just 12 miles across, unimaginably dense.
One pinhead of this would weigh hundreds...
...maybe millions of tons.
And as it shrank, like a figure skater spinning on the spot...
...arms outstretched, then pulling them in...
...it began to spin faster.
Two beams of light, energy, radiation, spinning 30 times a second.
Powering the huge cloud of dust and gas.
There's so much radiation here, more even than on the Sun.
That was easily the deadliest thing we've encountered so far.
Once, it would have terrified us.
But now we realize that without the dangers...
...there'd be no wonders.
Without the nightmares, there'd be no dreams.
Getting a strange sensation.
A feeling as though there's something bad out here...
...a malevolent presence.
The one thing we didn't want to encounter.
Impossibly black, blotting out the stars behind it.
We're staring into the face of extinction...
...the remains of a giant star...
...a black hole.
Far denser than a pulsar...
...and impossible to resist.
Its gravity is so intense, not even light can escape.
This asteroid, it's a lump of solid rock...
...but it's actually stretching, being dragged towards the gaping hole.
Inside, there's no matter as we know it.
No time, no space, all the rules of physics collapse.
The asteroid is gone.
Nobody really knows where.
This is the edge of human understanding.
There could be millions of black holes creeping around our galaxy...
...more perhaps than all the stars in the sky...
...but we wouldn't see them until it was too late.
Like this star, spiraling...
...disappearing, down an invisible sinkhole.
Who's to say we don't live inside a vast black hole...
...that the whole universe isn't inside one right now...
...inside another universe?
Think about it for too long and your mind reels.
Sometimes it feels like the more we see, the less we know.
And we're still in our own galaxy, the Milky Way...
...the vastness of the universe beyond still lies ahead.
The wonders, the dangers, the secrets, they're out there...
...waiting to be discovered.
Seven thousand light years from home.
It's as though we're in a forest thick with trees.
Each so beautiful, so fascinating, it's impossible to look beyond...
...to see the bigger picture.
We have to find a way through...
...to reach the clearing at the galaxy's edge.
But faced with sights like this, it's hard to leave.
A colossal glowing cloud topped by these great towers of dust...
...the Pillars of Creation.
Like a gateway into the unknown.
A star factory packed with embryonic star systems...
...each larger than our solar system.
We have to resist its siren song, tear ourselves away...
...to carry on towards the edge of the galaxy.
Dazzled by the Milky Way's beauty, we've been blinded to its terrors...
...and strayed into a cosmic minefield.
Like an explosion in slow motion.
A massive star, millions of times brighter than our sun.
It's going into meltdown.
The fuel that sustains it is running out...
...the nuclear reactions that power it winding down.
We're watching its death throes.
An even bigger, dangerously unstable star.
But this one's about to explode.
And when a star this big dies...
...it's a hundred times more violent than a supernova.
We've stumbled into the most violent star death of all...
...a hypernova.
The core's collapsed, it's becoming a black hole.
And that's the shock wave, surging through the star...
...ripping its outer layers into space.
Deadly hypernovas, frozen comets...
...scorched planets, white dwarves, red giants.
Tiny drops in a vast pool of white light...
...our home galaxy, the Milky Way.
We wanted to know where we fit in.
Here's our answer.
Civilizations, past and present.
Everyone that's ever lived.
The smallest bug, the highest mountain...
...all of it invisible, not even a tiny speck.
Our home is a minor planet orbiting an insignificant star.
If it disappeared right now, who would even notice?
And yet, so far, we've found nowhere else we would rather live...
...nowhere we could live.
It's only now, far from home...
...that we're beginning to truly appreciate it.
Look at all these stars, hundreds of thousands of them.
Surely one of them, more than one, must be capable of supporting life.
Maybe here in this swarm of stars, the Great Cluster.
Back in the 1970's, astronomers sent a message in this direction...
...detailing the structure of our DNA and our solar system's location.
But the message won't arrive here for another 25,000 years.
We haven't found alien life yet.
But neither have we found any reason to believe...
...it isn't out there somewhere.
There's an equation devised...
...to estimate the number of other advanced civilizations.
The result is startling.
There could be millions of civilizations just in our own galaxy.
Everything we've seen so far is inside the Milky Way.
Now we're ready to leave our home galaxy...
...to enter intergalactic space.
Here's our chance to solve the ultimate mystery...
...and experience the moment of creation.
Beyond the Milky Way...
...through the vast expanse between galaxies.
Against all the odds, we've made it to intergalactic space.
Out here, there's no horizon in sight.
Even the closest galaxies are hundreds of thousands of light years away.
The remains of galaxies ripped apart...
...by the Milky Way's huge gravitational pull...
...scattered among nothing.
This is as close as the universe gets to a perfect vacuum.
But even this isn't totally empty.
There are thin wisps of gas, fine traces of dust.
And something else, dark matter.
So mysterious, we can't see it...
...feel it, taste it, touch it or even measure it.
Yet so common, it could make up over 90 percent...
...of all the matter in the universe.
If dark matter does exist...
...it means there's no such thing as empty space.
Even out here, we're surrounded by matter.
We think it exists because of its apparent hold on galaxies.
Like this one, the Large Magellanic Cloud.
A 6-billion-year journey in today's fastest spacecraft...
... 160 thousand light years from the Milky Way...
...at the edge of its gravitational reach.
This galaxy should spin off into space, but something is holding it here...
...something invisible, powerful, dark matter.
Stars, clusters of stars, nebulae...
...it's a vast astronomical treasure trove.
But look at this, it's like a string of gleaming pearls.
It's a fireball...
...expanding out from what must have been a massive explosion.
A supernova.
So bright that when light from the explosion reached Earth 20 years ago...
...it was visible to the naked eye.
And so violent, it triggered a string of nuclear reactions...
...forcing atoms together, creating new elements...
...gold, silver, platinum, blasting them out into space.
The gold in the ring on your finger...
...was forged in a massive supernova like this...
...trillions of miles away, billions of years ago.
Before we left home, the universe seemed separate...
...something out there, up in the sky.
But now we know better.
We are the universe, and it is within us.
It's comforting to remember as we venture through this abyss.
Further and further.
Faster and faster.
The Andromeda Galaxy two and a half million light years away.
It's racing through space...
...everything blown apart, like shrapnel in an explosion.
We're seeing this galaxy as it was...
...when our ape-like ancestors first walked on the African plains.
Further through space, and further back in time....
Hold on. This doesn't look right.
A whole galaxy exploding?
The only thing large enough to cause an explosion on this scale...
...is another galaxy.
It looks like the end of the world.
But this galaxy won't die, it will be reborn.
A new shape, perhaps even new stars...
...as dust and gas collide, creating friction, shockwaves...
...triggering the birth of stars.
There's order in this chaos, a pattern behind the infinite variety...
...an endless cycle of birth and death, creation and destruction.
It's a pattern woven through the vast fabric of space...
...that binds each of these galaxies.
There are billions of galaxies...
...each with billions, even trillions of stars.
Maybe more stars than there are grains of sand...
...on all the beaches on Earth.
We're finally beginning to see the big picture...
...and it's grander than we ever imagined.
This galaxy, the huge Pinwheel Galaxy...
...is so far from Earth that if we send a message home now...
...it will take 27 million years to get there.
Who knows whether our species, our planet...
...will still be around to receive it?
We travel on, back through time.
Past the point where the dinosaurs were wiped out...
...past the moment where the first creatures crawled onto land.
Two billion light years from home.
Closing in on the edge of the universe.
Going back to the beginning of time.
This isn't a galaxy. It's brighter than a hundred galaxies.
A blinding beam of energy surging for trillions of miles.
Something this big, this bright, must be incredibly powerful.
Experience tells us, out here, power equals danger.
It looks like a quasar, the deadliest thing in the universe.
Our journey could be over.
The deadliest, most powerful thing in the universe.
A quasar.
A swirling cauldron of superheated gas.
This beast has a heart of darkness, a super-massive black hole...
...as heavy as a billion suns.
It's ripping apart whole stars...
...devouring them until they're nothing...
...lost forever from the visible universe.
We think, we hope, we pray...
...we've seen the worst the universe can throw at us.
But no one can know what lies ahead.
We'll need to go further, go faster.
Eight billion light years from home.
More galaxies, but these look different.
Ragged, small, close together.
We're so far back in time...
...we're seeing these galaxies as they were before the Earth was born.
They're still young, still growing.
We're getting close to where and how it all began.
Look at the galaxies now.
They're more like primitive plankton floating in a vast dark ocean.
Clouds of dust and gas...
...dancing, twirling, merging to make embryonic galaxies.
They're disappearing.
We've gone back before the stars were born...
...into a cosmic dark age.
And before that, light, the afterglow...
...from the massive explosion that created the known universe.
This is it.
We've made it.
The edge of the universe...
...80 billion trillion miles from home...
... 13 and a half billion years ago.
The very instant of the Big Bang...
...the most violent, most creative moment in history.
Everything that's ever happened follows from this moment.
Every religion, every culture, has pondered it.
But we still don't know what sparked this act of creation or why.
This is where our journey ends...
...and the universe begins.
An infinitely hot, small, dense point erupts.
Creating space, time, matter, our universe itself.
First, it's the size of a subatomic particle.
The tiniest fraction of a second later...
...it's big enough to hold in the palm of your hand.
Moments later, it's the size of the Earth.
Today, the light from the Big Bang is still spreading out.
You can hear it as a radio hiss.
See it as television static.
All the wonders we've seen on our journey...
...are sparks flying out from the Big Bang.
Galaxies, stars, planets...
...all cosmic debris.
We go forward through time...
...riding the blast wave.
Until we reach another cooling cinder...
...swirling in the afterglow of the Big Bang.
We're back where we started.
Home.
Only now can we really know it.
Smaller, more fragile than we ever imagined.
Destined to die, swallowed by a dying sun.
But we shouldn't despair. We should rejoice.
We've managed to experience the wonders of the universe.
We should celebrate our achievements...
...and enjoy our moment in the sun.