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Stars... they're big, they're hot,

and they are everywhere.

Stars rule the universe.

Our destiny is linked to the destiny of stars.

Born in violence, dying in epic explosions.

They fill the universe with stardust,

the building blocks of life.

Every atom in your body

was produced inside the fiery core of a star.

Stars are what make our universe work.

All life begins here.

The night sky is packed with stars.

On a clear night in the country, if you're lucky,

you can see maybe 3,000 stars.

But that's just the tip of a vast cosmic iceberg.

In our galaxy alone, there are over 100 billion stars.

And, in fact, there are over 100 billion galaxies

in the observable universe.

There are more stars than there are specks of sand on Earth.

Every star is powerful,

creating the basic matter

for everything in the universe...

...including us.

Most are so far away, we know little about them.

But there is one star that's really close,

and virtually everything we know about stars,

we've learned from that neighbor.

The sunlight from our sun that bathes us

and warms us every day is nothing but starlight

because our sun is nothing but a star like all the rest.

Seen from Earth,

our sun is a blinding ball of light.

But take away the glare,

and one of the most powerful objects in the universe

appears in our own backyard.

It's a ball of superheated gas that's been lighting

our solar system for 4.6 billion years

and dominates all life on Earth.

The Sun is 93 million miles away.

And that means, in actuality, it's immense.

You could fit a million Earths inside the Sun.

It's nearly a million miles in diameter,

yet our sun is tiny

compared to the really big stars out there.

Eta Carinae... over five million times larger than our sun.

Betelgeuse... 300 times larger than Eta Carinae.

If it was our sun, it would reach as far out as Jupiter.

And then there's this monster... V.Y. Canis Majoris,

the largest star ever discovered.

A billion times bigger than our sun.

Stars burn in different colors, from red to yellow to blue.

Some live alone.

Others in pairs, orbiting each other...

...and coming together in huge galaxies...

entire cities made up of billions of stars.

Each star is a one of a kind.

But they all start life in the same way...

As clouds of dust and gas called nebulas.

Many billions of miles across,

they drift through space, forming spectacular shapes.

The Flame nebula.

The Horsehead nebula.

The Orion nebula.

Each nebula is a star nursery

where millions of new stars are being born.

But this birth is hidden from view.

Some of the more dramatic parts of a nebula

are not the beautiful glowing gas

that you see but the dark parts.

The dark parts have areas of dense gas and dust,

and that's where the real action is happening

in terms of star formation.

The dust clouds are so thick,

regular telescopes can't see inside.

There's nothing more important to us than stars,

but for a long time,

the way they formed was a complete mystery.

We couldn't observe them. Imagine that.

We could not see the first moments of a star at all.

Until 2004 when NASA launched the Spitzer space telescope.

And liftoff.

Seeking hidden secrets

and the evolution of our universe.

Spitzer is an infrared telescope.

It only sees heat.

Heat passes through the thick dust of the nebulas,

allowing Spitzer to see new stars coming to life inside.

These remarkable pictures

capture the earliest moments in a star's life

as pockets of hydrogen gas begin to heat up.

Any little bit of gas and dust is glowing.

Areas that were entirely dark now became bright.

We can actually see the very earliest parts

of star formation.

All you need to make a star is hydrogen, gravity, and time.

Gravity pulls the dust and gas into a giant swirling vortex.

Gravity brings matter together.

And when you bring matter together

and you squeeze things into smaller spaces,

they necessarily heat up.

It's a simple law of chemistry.

You compress something, you drive the temperature up.

Over hundreds of thousands of years,

the cloud gets thicker and forms a giant spinning disk

bigger than our entire solar system.

At its center, gravity crushes the gas

into a superdense, super-hot ball.

Pressure builds until huge jets of gas

burst out from the center.

That really shows you

how violent a process star formation is.

These jets are many light-years across.

Something is literally accelerating material very fast

across unimaginable distances.

Gravity keeps the pressure on,

sucking in gas and dust particles

that smash into each other, generating more and more heat.

Over the next half a million years,

the young star gets smaller, brighter, and hotter.

Temperatures at its core reach 15 million degrees.

Only at that mind-boggling temperature

can atoms of gas begin to fuse together,

releasing massive amounts of energy.

And just like that, a star is born.

It will shine for millions,

even billions,

or perhaps even trillions of years.

Stars produce massive amounts of heat and light

over billions of years.

But that takes fuel and lots of it.

Until the early 20th century,

no one had any idea what this fuel was.

The greatest problem facing physics

at the turn of the last century was,

what drives the energy of stars?

All you had to do was look outside

and realize there was a huge gaping hole

in our understanding.

To solve the secret of the stars,

we needed a new engine.

We needed a fabulous source of energy

that could drive a star for billions of years at a time.

And it took a genius to discover it...

Albert Einstein.

His theories proved

that stars could tap into the energy inside atoms.

The secret of the stars is Einstein's equation e=mc2.

In some sense, matter, which makes up our body,

is concentrated energy, condensed energy...

energy that has condensed into the atoms

that make up our universe.

Einstein showed that it's possible

to release this energy by smashing atoms together.

It's called fusion, the same force that powers stars.

It's astonishing to realize that the physics

of the very small subatomic particle physics

determines the structure and nature of stars.

From Einstein's theories,

we learned how to release the energy inside an atom.

Now science is trying to simulate

a star's energy source

to control the power of fusion in a lab.

Inside this laboratory near Oxford, England,

there's an 80,000-pound machine.

Every day, Andy Kirk and his team

transform it into a star...

On Earth.

This machine is called a tokamak.

It's effectively a large magnetic bottle...

a cage to hold a very hot plasma.

We're able to re-create the conditions within a star.

Inside the tokamak,

hydrogen atoms naturally repel each other.

To smash hydrogen atoms together,

the tokamak heats them to more than 166 million degrees.

At these temperatures, the energized hydrogen atoms

are moving so fast,

they can't avoid smashing into each other.

If you heat it up, heat is motion.

And the motion of hot particles

will be enough to overcome the repulsive force.

All personnel, be prepared to leave.

Come off the machine area.

When everything goes right,

the result is the single best power plant in the universe...

nuclear fusion.

Traveling at over 1,000 miles a second,

the hydrogen atoms smash into each other and fuse...

...creating a new element... helium...

...and a small amount of pure energy.

The hydrogen gas weighs slightly more than the helium.

You lost mass in the process of burning.

That mass that you lost, the missing mass,

turns into energy.

The tokamak can only maintain fusion

for a fraction of a second.

But inside a real star,

fusion continues for billions of years.

The reason is simple... size.

The engine which drives a star is gravity.

That's why stars are big.

Stars are huge.

You need that amount of gravity in order to compress the star

to create fantastic amounts of heat

sufficient to ignite nuclear fusion.

That is the secret of the stars.

That's why stars shine.

Fusion at the core of a star generates the explosive force

of a billion nuclear bombs every second.

A star is a gigantic hydrogen bomb,

so why doesn't it simply blow apart?

It's because gravity is compressing the outer layers of the star.

Gravity and fusion lock horns in an epic battle.

We have this constant tension between gravity,

which wants to crush a star to smithereens,

and, also, the energy released by the fusion process,

which wants to blow the star apart.

And that tension, that balancing act,

creates a star.

This power struggle plays out

over the entire life of a star...

two awesome forces of nature in the dynamic stand off.

as that battle reaches

the star blast out light and heat

but also something far more destructive.

Each beam of starlight makes an epic journey.

Light travels at 1080 million miles an hour.

A beam of light could travel around the Earth

seven times in one second.

Nothing in the universe moves faster.

Yet most stars are so far away,

their light takes hundreds, thousands, millions,

even billions of years to reach us.

So, when the Hubble space telescope

looks into the far corners of our universe,

it sees light that's been traveling for billions of years.

The light we see today from Eta Carinae

left that star when our ancestors

first farmed the land 8,000 years ago.

Light from Betelgeuse has been traveling

since Columbus discovered America 500 years ago.

Even light from our own sun takes eight minutes to reach us.

But even before light starts its journey through space,

it's already been traveling for thousands of years.

When the Sun fuses hydrogen into helium in its core,

it creates a photon of light, a particle of light.

That new ray of light has a long way to go

just to reach the star's surface.

There's a whole star in its way.

And so when the photon is created,

it doesn't get very far

before it immediately slams into another atom...

another proton, another neutron, something.

It gets absorbed and then shot off in another direction.

And so it's sort of randomly moving around inside of the Sun,

and it has to work its way out.

For the photons, it's a wild ride,

smashing into atoms of gas billions of times

as they struggle to escape from inside the star.

What's funny about this whole process

is that it takes the photon thousands and thousands of years

to get from the core of the Sun to the surface.

And yet once it hits the surface,

it's only an eight-minute trip from there to here.

Photons are the source of light and heat,

but they also cause something far more destructive...

the solar wind.

As they reach the surface,

photons heat up the outer layers of the Sun...

...sending it hurtling around the star,

creating extreme turbulence and intense shock waves.

It's so violent, we can actually hear it.

Picked up by the orbiting SOHO satellite,

this is the sound of the Sun.

The speeding gases also generate powerful magnetic fields.

As the star rotates,

the fields clash and burst through the surface.

Giant magnetic loops erupt into space.

Some are so large,

the Earth could pass right through them

with thousands of miles to spare.

They are spectacular, and they are deadly,

blasting a stream of electrical particles deep into space.

This is the solar wind.

It can damage spaceships and satellites,

even put astronauts' lives in jeopardy.

To discover how the magnetic loops trigger the solar wind,

a team of scientists at CalTech re-create the surface of a star

right here on Earth.

It's very exciting to be able to create in a laboratory

the same sort of physics that are on the solar surface.

We can't go there. We can't even send probes there.

But we can try to study what's happening there.

An airless chamber simulates the vacuum of space.

An enormous electric current

produces a pair of man-made magnetic loops.

The main difference

between the plasma loops we make in the lab

and the ones on the surface of the Sun

is just their size.

The ones we make in lab are, you know, about this big,

and the ones on the surface of the Sun

can be many times the size of the Earth.

Their experiment reveals

that when magnetic loops clash in the lab,

they trigger a massive burst of energy.

When giant loops collide on the surface of a star,

the energy released sends temperatures soaring

from 10,000 to 10 million degrees.

That extreme heat triggers the solar wind,

sending millions of tons of particles

streaming out into space.

The bigger the star, the more deadly the wind.

If we were orbiting a star like Eta Carinae

at the same distance,

it would be hell on earth, quite literally.

The amount of energy blasting down on the Earth

would strip away our atmosphere,

boil our oceans, melt the surface.

Understanding how stars work could help us protect ourselves

by predicting their most destructive forces.

But there's nothing we can do

to protect ourselves when a star dies.

In its final moments,

it annihilates everything around it.

From the moment of its birth,

every star is destined to die.

Its fuel will run out.

Then gravity will win the battle with fusion,

triggering a chain of events that will destroy the star.

Our sun is no exception.

Every second, it burns through 600 million tons

of the hydrogen fueled in its core.

At that rate, the hydrogen will run out...

In about seven billion years.

As the hydrogen gets used up,

it slows down the fusion at the star's core.

This gives gravity the edge.

With less fusion pushing outward,

gravity crushes the star in on itself.

But fusion fights back, heating the star's outer layers.

When you heat up a gas, it expands.

And so the Sun will actually expand up.

Instead of being a million miles across like it is now,

it'll swell up until it's about 100 million miles across.

Our sun will become a red giant.

Imagine a sunrise 7 billion A.D.

It's not just a little, yellow disk

coming up all cheerful and nice.

What you would see is a huge, swollen, bloated, red disk

slowly reaching up over the horizon.

And when the Sun is fully up in the sky,

it's blasting down heat on the Earth.

It would be like sticking your head in an oven set to "broil."

Temperatures here on Earth will reach thousands of degrees.

The oceans will boil, the mountains will melt,

and we'll have the last nice day on the planet Earth.

Then the bloated star will engulf the Earth.

But the giant red star is self-destructing.

Its core becomes dangerously unstable.

With no hydrogen left to fuel it,

the star begins burning helium and fusing it into carbon.

The star is now destroying itself from the inside out,

blasting violent surges of energy

from its core to its surface.

These energy waves blow away the star's outer layers.

Slowly, it disintegrates.

The star is dead.

All that remains is an intensely hot, dense core.

The red giant has become a white dwarf.

By the time a star reaches the white-dwarf stage,

the fusion process has stopped.

The engine has finally come to rest.

Our sun will end its life as a white dwarf

no larger than the Earth but a million times denser.

A white dwarf is a pretty amazing object.

It's incredibly dense.

If you could take

a sugar-cube-sized chunk of white dwarf

and put it on the surface of the Earth,

it would be so dense,

it would fall right through the ground.

At the heart of a white dwarf,

astronomers believe there's a giant crystal

of pure carbon.

A cosmic diamond thousands of miles across.

The idea that the Sun will become

this sort of cool, dark lump of cinder material

is kind of sad.

But that really will be

sort of a trillion-trillion- trillion-karat diamond.

Think of that... a diamond in the sky.

but star can create something much more pressure than a massive diamond.

when star much bigger than our sun die, their death is much more violent.

but in dying, they create the building blocks of life.

Giant stars live fast, burn bright, and die hard.

But from their destruction comes life.

The death of massive stars

creates the building blocks of the universe...

The seeds of life itself.

Less than 600 light-years from Earth,

the monster star Betelgeuse is near death...

well, in space years.

It's younger than our sun...

millions, not billions of years old.

But the fusion at its core is far more intense.

Betelgeuse is a different beast from the Sun entirely.

It's a red supergiant.

And the reason is because Betelgeuse is more massive.

It has 20 times the mass of the Sun,

and that means what's going on in its core

is very different than what's going on in the Sun's.

Massive stars generate pressures and temperatures

greater than anywhere else in the universe.

The gravity of Betelgeuse is so powerful,

it can smash together bigger and bigger atoms.

The core of a massive star is a kind of factory,

manufacturing heavier and heavier elements...

...which is what also leads to the star's destruction.

Once it makes the element iron, the star is doomed.

In the world of science fiction, there are many ideas

about what a star-killer machine might be like.

Strangely enough, it's as run of the mill as something as iron.

To a star,

iron is the most dangerous element in the universe.

It's poison.

Iron absorbs energy.

From the moment a massive star creates iron,

it has only seconds to live.

The star is trying to dump energy into that iron ball

and trying to make it fuse, but it can't.

And so that ball is robbing the star of energy,

and it's that energy that is supporting the star itself.

So, as soon as that iron starts to be created in the core,

the star has written its own death sentence.

The battle between gravity trying to crush the star

and fusion trying to blow it apart is over.

With iron, fusion hits a dead end.

Gravity always wins.

The iron core collapses.

The outer layers of the star slam down into it,

and a huge explosion is generated.

It's the single most violent event in the universe...

a supernova.

In just a few seconds,

supernovas create more energy than our sun ever will.

Within a couple seconds after beginning to make iron,

the star explodes in a supernova.

So, think about that

when you're holding one of your iron frying pans.

The iron killed a star in just a few seconds...

dangerous stuff.

Telescopes around the world scan the skies for supernovas.

In 1987, a brilliant light appeared

in a nearby galaxy 170,000 light-years away.

These pictures record the events

following the death of a massive star

as a fireball trillions of miles wide

hurtles out into space.

But there's no record of the actual moment of death

when the star first ripped itself apart.

The only way to know what happens

inside a massive star when it explodes

is to make our own supernova.

What's amazing when these stars explode

is that they almost turn inside out.

Here in this lab in Rochester, New York,

scientists are making a supernova with a giant laser.

Telescopes can't see inside the dying star.

With this laser, we can detect the processes

that occur as the star explodes.

Working with these tools

is the most exciting thing I can imagine doing.

This massive machine amplifies the power

of a single laser beam 1,000 million million times.

That's enough power to supply 30 cities the size of Detroit.

And all that energy will be directed

toward an area the size of a pinhead.

Look at this tiny target as a star's core.

The laser simulates

the most violent explosion in the universe.

This would not be a safe place to be when the laser was fired.

If a human were struck by all these laser beams,

they would drill a hole right through them.

Now going to closed access in the laser bay.

Main doors locked.

Final preparations are complete.

5... 4... 3... 2... 1...

The target is vaporized by the laser.

The explosion lasts just 1/100,000 of a second.

But a high-speed camera

captures the shock wave expanding outwards.

Some of the inner material comes out

and trades places with the outer material,

and that turning inside out

is just what happens in a stellar explosion.

Material from deep inside a star's core

surfs the shock wave out into space.

In the extreme heat and turmoil of the explosion,

heavier elements are forged.

Among them, gold, silver, and platinum.

And because there's so little time for the elements to form,

they are the rarest and most valuable in the universe.

Silver, gold, everything else are created

by the explosion of the star, by the immense energy released,

and that's how they come to us.

But even after the universe's most violent explosion,

there's something left behind.

We scientists used to believe

that after a supernova explosion,

a star would literally blow itself to bits,

and there'd be nothing left.

Well, we were wrong.

There's a corpse... a corpse of a supernova explosion.

Some of the most excotic matter known to science

called a neutron star... solid nucleonic matter,

the most fantastic state of matter in the universe.

The superdense core is now a neutron star.

It's around 20 miles across and unbelievably heavy.

It's incredibly dense.

Just a cubic centimeter,

just the size of a sugar cube of neutron-star material

would weigh as much as all the cars

in the United States of America combined.

The dying star

doesn't just leave the corpse of a neutron star.

It blasts the new elements far out into space.

These clouds contain the building blocks

of the universe.

Everything we know and love is built from this stardust.

Only a supernova has enough energy to fuse these elements,

which are so essential for life.

Without supernovae, there's no life.

There's no you, and there's no me.

When massive stars die...

...they seed the universe with stardust...

...full of elements like hydrogen...

carbon...

oxygen...

silicon and iron

The raw materials to build new stars,

solar systems, planets, and, of course, us.

Everything we see around us

once blasted out from the core of a star.

You may wonder what stardust is.

Well, you're stardust because every atom in your body

was produced inside the fiery core of a star.

The atoms in your left hand may come from a different star

from the atoms in your right hand,

but you are literally a star child.

Long-dead stars provided the stardust

to create our solar system, the planets,

and everything on them.

So, you're made of carbon, you're made of oxygen.

There's iron in your blood.

All of those things had to be generated

inside the core of a star.

There's no other way to get them.

So, when you think about star stuff, look around you.

Everything that you're made of,

everything in the world around you is made of

had to come from the belly of a star

that blew up a long time ago.

Even the atoms in our own sun are recycled.

They're third or fourth generation...

leftover debris shot into space by dying stars a long time ago.

Our sun is our stepmother.

Our true mother died in a supernova explosion

to give birth to the elements which made up our body.

But how come the poets and the songwriters,

how come they don't write poems to our true mother?

It's perhaps they don't understand physics

and the laws of stellar evolution.

We live in an age of stars.

But it will come to an end.

There's only so much hydrogen in the universe.

Trillions of years from now, it'll all be used up.

And when there's no hydrogen left,

there'll be no new stars.

We live in a very brief period in the history of the universe.

Well, we still have stars illuminating the sky,

stars creating life as we know it,

but it's not gonna last forever.

Sooner or later, the stars will begin to blink out.

First, the massive stars will burn out,

then midsized stars like our sun,

leaving only the smallest.

Trillions of years later, they, too, will fade away.

Slowly, inexorably,

the universe will get colder and darker

until the last star burns out

and the universe becomes dark once again.

The age of stars will be over.

Honestly, the future of the universe looks kind of grim,

but you can take something positive out of that.

This is the best time to be alive.

This is the time where life can flourish, stars can form.

We are in the golden age of the universe right now.

We live in a season for life in the universe, if you will,

that lasts for a few billion years.

And that makes me, at least,

appreciate the way things are right now

because they weren't always that way,

and they won't always be.

We live in the stage

where stars glow and illuminate the night sky,

when stars create life as we know it.

We live in the best of all stages of the universe.

For now, stars will continue to shape our universe,

generating the building blocks of new worlds,

creating new stars and filling the darkness with light.