The Universe (2007–…): Season 1, Episode 1 - Secrets of the Sun - full transcript

The sun is the superpower
of our solar system,

a thermonuclear blast furnace,
erupting with massive explosions.

It can be the same amount
of mass of mont Everest

coming out from the Sun and
flying out into the space.

At 93 million miles away it would seem
that we are safe from the sun's wrath.

But are we?

It matters, especially in modern times,

what the sun is doing.

From the center of the
sun, as it rotates around,

as the kill zone.

With some experts predicting the most
violent outbreak of solar activity



in modern history.

it?s never been more
important to understand

the secrets of the sun.

The Universe episode 1x01
- Secrets of The Sun

There are bilions of
stars in the universe

but one alone dominates
our cosmic neighborhood:

the Sun

It's an infernal sphere, of
mostly hydrogen and helium,

superheated into a plasma, that
burns at millions of degrees.

Its surface reages
with violent explosions,

as expelled outstorm of deadly
radiation, milions of miles into space.

Our Sun is a type of star,
known as a yellow dwarf.

Yellow because of the
color of its surface.

And dwarf because it's small for a star.



But small it's relative.

Within its boundaries, you
can fit one milion earths.

In our solar system, there's
simply no bigger star than the Sun.

At a milion miles across, it's
a massive celestial blockbuster.

The Sun is really pretty huge.

It dominates our solar system.

Not only is the bigger
star of the Solar system,

it's the only star of the solar system.

It's sorrounded by a
bunch a smaller stuff,

that we called planets,
comets and moons.

But the Sun is our star.

Our star is an enormous
source of heat and energy.

It has a surface temperature
of 10.000? Farenheit.

An generates 380 billion
billion megawatts of power.

This dwarf anything on a human scale.

Hoover Dam in Nevada only
generates 280 megawatts.

In one second the sun
churns out more energy

than has been used in
all of human civilization.

All that power in the blink of an eye.

Incredibly, it's been burning
this way for billions of years.

Early astronomers didn't
quite understand how

the Sun could generate so much
energy for that long period of time.

though is the first mistery was really
how the sun generate this energy.

In the early nineteenth century,

scientists assumed that the Sun
work just like any fire on Earth,

that there was a source of fuel, pheraps
coal, that was slowly burning away.

But that was a serious
problem with this theory:

I've got a fire in front of me here,

if I wanna as keep burning, I
had to keep adding woods to it.

This fire last maybe an hour,
must to add some more woods.

Now, if I had a pile of the
woods the size of the all Sun,

and somehow enough oxygen to burn it,

it would only take about 5000
or 6000 years to burn out.

That's a long time, but it's not
long enough to substain life on Earth.

By the early twentieth century,

carbon dating of earth rocks
and fossils have prooved it,

that the Sun was in existence at a
temperature warm enough to substain life

not for thousand of
years, but for 3 billions.

If you want to build a fire
that would last that long,

you'd need 72 trillions
cords of firewood.

That's 12 thousand cords for each
man, woman and child on the planet.

Clearly, there had to
be some other process,

unknow on Earth, that
would powering the Sun.

In the 1920's scientists
found the answer to the puzzle,

in a process that would later be
harnest to fuel the hydrogen bomb.

Nuclear fusion.

Fusion occurs when atoms are smashed
together in a high rate of speed

and literally fused.
To get this to happen,

conditions have to be just right.

For any interaction that happen
there's two proton, each has

a positive electric charge and
so they would repell each other.

So you got to get in
close enough together,

and to do that, it's got
to be hot, which means

The part is moving fast, and dense
enough that they, they hit each other

and they can get close enough
together and actually fused.

The core of the Sun is the
perfect coaler for nuclear fusion.

It's the hottest place in the solar
system, as it sweltering 27 milion? F.

And it's also incerdibly dense.

It's so dense, it's ten
times the density of lead,

and you would think that high density
should be a solid, but it's not

because it's so hot
that remains a plasma.

If you heat a gas to
high enough temperatures

electrons fall off the atoms
and float around in the soup.

And so it has behavior that's
different from what a gas would do,

that we have a different
word for it, called plasma.

To truly understand what goes
on in the core of the Sun,

you have to find someway to
imagine the almost "unimaginable".

In addition to study
the Sun, I also play pool

and the Sun is a place where
there are billion of particles,

colliding interacting with each other.

And it is really not unlike a cosmic
pool table, on an imaginable scale.

It doesn't matter how
hard you hit a ball.

You would never hit
hard enough to actually

fuse that ball together
with another ball.

But there's so much pressure and such
high density in the core of the Sun,

that two objects impacting
each other, will actually fused.

In the Sun, these objects
are hydrogen atoms,

flowned together by immense
pressure, to form helium atoms.

In this fusion process, the resulting
atom is slightly less massive

than the ones they created it.

The missing mass is given off as energy.

Each second, inside the Sun, 600
million tons of hydrogen are fused

into 595 million tons of helium.

That five million tons of mass lost
in the process is converted into energy

equal to one billion one
megaton hydrogen bombs.

That's every second.

When you look out into the cosmos

the process that gives you
the highest return of energy

for free, is what goes on in the
center of a star like the Sun.

So, we now know that the Sun
is powered by nuclear fusion.

It's the only fuel we know,

that can substain the
burning in the Sun long enough

to substain life on
Earth, billions of years.

Sunlight:

it's so central to life that we
don't often give it a second taught.

But how light gets from there, to here
turns out to be an incredible story.

The energy created in the fusion
process is carried out of the core

by particles of light
and heat called photons.

They are what bring the warming
race of the Sun to Earth.

To reach our planet, these glowing
travelers from our nearest star

must first take a long whining
road to all the layers of the Sun,

like Dante's journey
to the levels of Hell.

First, a foton entries the
185.000 miles take radiating zone,

the region is so densily pathed

that fotons constantly
bums into other particles,

like hydrogen and helium atoms.

It struggles outward in a chaotic zigzag

pattern that scientists
called the random walk.

A foton can't escape without
interacting over and over and over again,

getting absorbed by atoms and readmitted

and it can be absorbed and
readmitted milions of times.

As the density decreases as
you get further up in the Sun,

it become easier and collusions
and interactions are less.

When it finally reaches to a thin
130.000 miles from the surface,

the foton enter the convective zone,

and the pace suddenly quickins.

It's carried outwards
by a kind of boiling

riding along in huge columns of
gas at hundreds of miles in hour.

Taking only ten days to
emerge on the solar surface.

The incredible journey is almost over

as the photon lifts off through the
wispy gasses of the solar atmosphere

From there it takes only 8 minutes

for it to zip across 93
million miles of space.

To our planet.

Incredibly by the time
sunlight actually reaches Earth

It's already been in existence

for hundreds of thousands
if not millions of years.

For the Sun even a million
years is a small blip in time.

The simple perfect disc of the sunset,

the lies the long, violent
history of our star.

It is a ball of fire
spawned billions of years ago

in a massive explosion
known as a supernova.

After this titanic explosion where a
star much larger than the sun exploded

There would have been a huge cloud of gas
many times larger than the solar system.

and small nuts of material
would have gradually collapsed

in this very large cloud.

About five billion years ago

Some ten billion years
after the big bang,

that scientists believe
kickstarted our universe

This cloud started to collapse
under the pull of gravity.

Our solar system probably
arose from one such nuts

of self gravitating gas
that pulled itself together

and gradually span itself up

it is pulled in, like a skater
pointing his arms in bringin spin

Until the star and the various
planets collapsed around it.

Ultimately, when the star was
dense enough it would have turned on

fusion, started glowing
and giving off sunlight.

Why do scientists believe the Sun was
born from the ashes of a supernova?

The evidence lies beneath our feet.

Complex heavy elements

like the uranium we mine from the
Earth to fuel our nuclear powerplants

could not have been forged in the Sun,

there was simply not enough
heat in a star of that size

to create elements
any heavier than iron.

Heavy elements, like uranium,

can only be created in a
catastrophic cosmic explosion

Earth and the other
planets in the solar system

formed out of the same nut
of gas that produced the Sun

In this process the Sun
holded 99% of the mass

This means that's the biggest
object in our celestial neighborhood

With the strongest gravitational power

that's why everything
else revolves around it.

Of all the planets Earth earned a
privileged place in relation to the Sun.

If we were closer in

our oceans would boil away and the
ground would be hot enough to melt lead.

If we were further out our planet
would be a frozen wasteland.

So that's like Goldylocks
and the three bears

not too hot, not too
cold, it's just right.

Here we are at about
93 million miles away

from the Sun and we're happy to
be here, we're lucky to be here.

In some sense we're here because it's
the right circumstance for us to be here.

Earth may be just the right
place in the solar system.

But we're also close enough to
the Sun to be a target of its fury.

Thousands of magnetic explosions
rock our Sun every year.

You might expect this explosive force to
come from nuclear reactions in the core

but in reality what drives all
outburstive solar violence is magnetism.

Since Earth rotates as a solid,

our magnetism is simple, we
have two poles: North and South

This is what a compass so useful for
finding your way around the planet.

But imagine if instead of two
poles you had 1 to 10 million.

This is what happens on the Sun.

The Sun's magnetic field

is a tangled web because even
tough it's held together by gravity

the plasma doesn't rotate evenly.

Plasma at the equator

rotates once every 25 Earth days

while plasma at the poles takes
roughly 35 days to circle once.

The Sun has what we call
differential rotation

You have all this plasma...

that is really turning and turning

and that causes magnetic
field lines to become twisted

and inner twiddled and mixed up.

Although magnetic fields
lines are invisible

we know they exist on the Sun

by looking at features called
"coronal loops" and "prominences".

Rising up into the solar atmosphere.

Just as metal shavings line up
in the presence of a simple magnet

These loops of plasma

perfectly outline the magnetic
structure that supports them from below.

These plasma arches are so tall and wide

that you could slide a planet as
big as Jupiter right through them.

Sometimes magnetic
fields can twist plasma

in the Sun's atmosphere into majestic
helical shapes called flux ropes

A magnetic flux rope is
sort of like a slinky.

The magnetic field line is wrapped
around many times in a helical structure

And when you have highly
twisted magnetic field lines

it carries a lot of
stored free magnetic energy

and sometimes it will
even kink in on itself

which kinks even more
stored magnetic free energy.

These plasma prominencies
can last for weeks or months,

but eventually the stored
up energy has to be released.

And the mass is flown off in the space.

Where the Sun's magnetic field
is at its most twisted and complex

Heat bubbling up from below is kept

and the material is cooled
by as much as 1000 degrees.

what results are
relatively dark blemishes

on the solar surface
called "sun-spots".

Sunspots are only dark in relation
to the bright material around them.

If you could somehow
suspend one alone up in space

it would shine 10 times
brighter than the full Moon.

These apparently tiny blemishes

are actually plasma creatures
the size of the entire Earth.

Galileo was one the first modern
scientists to observe sun spots

Using a telescope he projected the image
of the Sun on the paper and traced it.

He realized that the blemishes were
moving across the face of the star

which was the first
indication that Sun rotated.

Not only does the sun rotates
but some spots themselves can spin

and when they do, their magnetic
field lines become extremely twisted.

Twisted magnetic field
lines mean more energy

and more energy means the
potential for huge eruptions.

Think of a rubber band
as magnetic field line

If you twist it, and you twist enough
it's goin to have all the energy

and when you let it go
it's going to release it

If you just take an untwisted rubber
band and release it it's not going to fly.

When a Sun spot unleashes
its magnetic energy

what results are the most colossal
explosions on the solar system:

solar flares.

A single flare releases as much
as a billion megaton of energy.

The combined power of a million
vulcanic eruptions on Earth.

They appear as these very...

white regions and they're so bright
because the temperature is so high.

on the order of ten million
degrees and they can last for hours.

But the energy is massive.

The whole explosion...

is equivalent to
millions of nuclear bombs

leaving the surface
of the Sun all at once.

Solar flares don't just
explode out in the space.

They also funnel high energy particles

down to a layer of the
sun called the cromosphere,

where they quickly transfer their energy

like a cue ball striking the
rack in the game of billiards.

So you have a cue ball,
actually like one of these

very high energy particles
coming from the flare agent.

A cue ball smacks very
quickly into the 8-ball rack,

and once it impacts the head ball,

it's going to transfer that energy

to the balls behind it and then

they will all flyout because the
energy is transferred to all of them.

If a large flare shoots enough
high energy particles at once,

strange things start to happen.

This is actual footage

of a sunquake.

In 1998

there was a solar flare up in the

corona that was so powerful
that the material flying down

toward the surface of the sun

actually slack the surface and

cause ripples to spread out from there.

While thay may look
like ripples on a part,

these are actually waves two miles high

travelling at a maximum velocity of

250 thousand miles per hour.

The 1998 sunquake

would have measured in
11.3 on the Richter scale.

More than one million times stronger

than the 1989 earthquake that

shocked San Francisco.

In order to shake the
surface of the sun that much,

the solar flare had to release
a colossal amount of energy.

It turns out that's almost
the same amount of energy

as if you cover the entire land
mass of the earth with dinamite,

about a yard thick.

And set it all off at once.

These explosions are not small.

Earthquakes aren't the only natural
disasters with equivalents on the sun.

A flare can also
kick-off a solar tsunami.

As waves of plasma in the
sun's atmosphere rock it up

at 700 thousand miles per hour,

spreading around the
entire face of the star

in a matter of hours.

While sunquakes and solar tsunami

pose no danger to earth,

the violent action of a flare

frequently triggers dangerous eruptions

called coronal mass ejections, or CMEs.

In a CME

energy from a flare flees a blob of

highly charged radioactive plasma

out of the solar atmosphere.

Coronal mass ejections

range and speeds, but take in a curl

as quick as

800-900 miles per second,

which is extremely fast and it

expell a massive amount of material.

It can be the same amount of
mass as, say, mount Everest,

coming out from the sun and

flying out into the space.

Where does this blob of
superheated radioactive

plasma go when it leaves the sun?

Sometimes it sails out
harmlessly in the space.

Other times it may head closer to home.

Coronal mass ejections from the sun

are perhaps the most dangerous
threat you've never heard of.

Also known as solar storms,

they hurl a large masses
of supercharged particles

across 93 million miles of space.

Most takes several days to
travel from the sun to the earth,

but some rocket across the solar system

at up to 6 million miles an hour,

reaching our planet
in less than 16 hours.

These storms can induce
currents in the outer atmosphere

knocking out satellites and
cross-country power grids

and carry the potential to

rid just as much heavy
gunner our infrastructure

as a hurricane or a tornado.

But who on earth is keeping an eye

on this potentially
hazardous cosmic blasts?

This is the headquarters

of the National Oceanic and
Atmospheric Administration,

home to the US governments
national weather service.

Their daily forecasts,
whatches and warnings

are essential information for
everyday life on our planet.

But there is a lesser known
group of forecasters working here

in a special division called
"The Space Environment Center".

Out primary job is to monitor the sun

and put up the alerts,
watches and warnings

for solar activity.

Good morning and welcome
bright in briefing.

We have one unknown on the
ration seen flare from east slam

as a possible CME.

We have not had protons
but we have had electrons.

One thing you notice is that this region

pretty stall the activity in the sun.

Bristol thinks it might be packing
up your head the next couple of weeks.

These space forecasters

are on high alert for solar storms

that might disrupt life on earth.

Solar storm clouds are made
up of charged particles,

so they are initially
diverted around the planet

by a magnetic field,

just like waves breaking
around the bow of a boat.

It turns out to be very important

because if it impacts to the
outer atmosphere directly,

it would knock little bits of
the atmosphere off in the space.

One reason why Mars
doesn't have an atmosphere

is that it doesn't have a
strong internal magnetic field.

And so gradually over

million or maybe billions of years

the atmosphere was gradually
knocked off in the space

by the influence of the solar wind

and by the CMEs that
skim past the planet.

But our magnetic field is not the
perfect force field of scifi movies.

Some particles can penetrate it

charging up the upper atmosphere.

Solar storm would even bend and
break the magnetic field lines

on the far side of the earth,

allowing charged particles to
zip back down the field lines

toward the north and south poles.

Extremely powerful storms
distort the magnetic field

even further, inducing electric currents

that span a continent.

When this happens, technology
like long-distance powerlines

can become overloaded.

Because damaged the trasformers
at either end of the line.

In fact, in 1989

most of the canadian provinces

go back blacked-out because
a transformer was blown out

by a solar vent.

If we have that storm and hits our

communication system and hits our

our companies and all these
things that we depend on

there is all kind of chaos
that can lay out there.

If power operators have time to react,

thay can reduce the current

being sent over their wires

and avert disaster.

Satellite operators can also

prepare for the onslaught

with proper warning.

When there's a big space storm coming,

we'll actually put some
of the satellite to sleep,

so that the storm

doesn't cause an electrical short

or otherwise somehow
knock out the satellite.

So the more warning time
they have, the better.

We wouldn't go sailing

unless we knew what the
weather is going to be.

Similarly when we have a large system

like a power system or a
telephone grid that can be effected

by the weather and space,

we need to know what the
weather is going to be

so that we can try to mitigate it.

Solar storms can also disrupt
high frequency radiocommunications

used by aircraft.

In the 1980's

Airforce One was transporting
president Reagan on a trip to China

when a solar storm struck.

All communications were lost

for several hours,

effectively severing the head of

the United States government.

The urgency is just
like a worse weather.

One we have a tornado warning

we know the order is to
get that out to the public

to let the people know
that this is happening.

The same thing is with space weather.

Uses of this information

need to know what do
they need to know and now.

A just few hours back we
experience a coronal mass ejection.

We wanna see what this blast

is going out in,

and then we can measure then and see

how long it may take from that
to reach the Earth from the sun.

We're seeing a very huge explosion

of material that's coming out

and if you look at
this small image here,

here's the sun is covered up, and look at
the mass that's been thrown out in the space.

So it's huge, very huge.

Because magnetic field lines emanate
from the North and South Poles

energy from solar storms has
easy access to those regions.

For that reason, experts
worry that airplane passengers

flying over the Poles
during a powerful storm,

might be exposed to
armful levels of radiation,

perhaps are those equal
to a hundred chest x-rays.

It's not something that we want to
mess around with, because we never know

when that radiation might
all of a sudden become

a lot more intense while
there's an airplane in the sky.

The threat from solar radiation
is just one more reason

scientists keep a
close watch on our sun.

It matters, especially in modern times, what
the sun is doing. Earth is not an island.

We are partecipant in the
activities of the solar system.

Sunspots are the triggers for more severe solar
storms, so forecasters track them carefully,

as they rotate across
the surface of the sun.

Location, location, location. We
see CMEs all the time from the sun.

A lot of them are as the center is rotated
around from the backside of the sun.

That would not be face towards the
Earth, so that would be less of a concern.

As the sun rotates around and that active
region gets more into the center of the disk,

looking at us, then that's
when we'll be concern with.

From the center of the sun, as it
rotates around, as the kill zone.

As the sunspot rotates around and
begin to face directly the Earth,

that's when we really have
to worry about a storm.

If a big storm leaves off then,

it can aim directly at Earth, and the full
force of the storm slams into the planet.

It's like a shotgun
aiming at the target.

The more dead on the shot,

the more likely serious
damage would be inflicted.

With great danger also
comes astonishing beauty.

Solar storms generate
majestic planetary lightshows.

The shimmering courtains
of color, called the Aurora.

Auroras work like neon
signs, on an enormous scale.

In a neon sign, electricity introduces
charged particles into a gus filled tube.

The particles in the gas are
excited and start to glow.

If the tube has only neon
inside, it will glow red.

By adding other gases, like argon, a
whole range of colors can be produced.

The neon sign is driven by the
electric field inside the tube,

whereas the Auroras is actually driven by
the magnetic field and energy from the sun.

As the energetic
particles in a solar storm

stream along Earth's magnetic
field towards the Poles,

the excite elements in our
atmosphere, causing them to glow.

Oxygen molecules emit
a green or red color.

And nytrogen emits
pinks, blues and violets.

While these ghostly lights are
usually confined to the Poles,

extremely strong solar storms can
drive them closer to the Equator.

In 1859 a geomagnetic storm
ignited by a huge solar flair

created Auroras as far south as Rome.

The 1859 storm was an
unusually powerful event

that some have called
"the perfect solar storm".

The 1859 storm told us a little
something about what the sun can do.

The storm was so intense and
the alignment was so perfect,

that it simply overwhelmed
Earth's natural defences.

A huge solar flair erupts
on the surface of the sun.

Less than a day later
and 93 million miles away,

the wires the carries communications
across the Earth, begin to spark.

Business grinds to a whole world wide as
wild fires are ignited by the small lights.

At the same time, colorful Auroras light
up the skies of cities around the globe.

Earth has just been visited
by the perfect solar storm.

The sun kicked up this
just incredible solar flair

and a massive amount of
energy headed towards Earth.

Not only was this storm one of
the 2 most powerul on record.

It was also one of the fastest.

Ejecting from a sunspot
and directly at Earth,

it would race from the sun to
our planet in less than 18 hours.

Now, it takes a really fast
rocketship, years to get to the sun.

This storm, this cloud of electrified particles,
managed to get here in less than a day.

That's incredibly fast.

Fortunately, the perfect
solar storm took place in 1859,

when the only technology vulnerable
on Earth, was the telegraph.

Since the era in wich we've become
dependant on high technology,

we wait to see another
perfect solar storm.

The question remains.
Could it happen again?

What if we had another one like that?
Can we have another perfect storm?

I'd say yes we can,
there's no doubt about that.

The... effects that would be on us today,
compared to 1859 could be... devastating.

The effects on Earth and on
our communication systems...

We don't exactly know.
That's the scary part.

It's likely that our modern
technologies would be battered

like beachfront houses
during a hurricane.

Imagine if we lost all the satellite
that we lay cellphone calls,

television signals
and bank transactions.

And what if at the same time,

the failure of powergades cascaded the all
regions into darkness for hours, or weeks.

If these essential services couldn't be
restored quickly, caos wouldn't be far behind.

It would definitely be
a rip effect upon society

and every man and woman and
child that lives on this Earth.

Solar storms can be as hard
to predict as hurricanes.

Well, forecasters lack the technology
to fortell the next pefect storm.

They do know that one
would be more likely to hit

at the peek of the sun's
eleven years sunspots cycle.

What happens is the sun reverses the direction
of its magnetic field every eleven years.

So in 22 years it reverses
and comes back were it was.

As we're near to reversal
every eleven years,

the number of sunspots increases and
there's a spike in solar activity.

We call that period solar maximum

and those periods are inner spreeads by 5
years apart from periods we call solar minimum.

So you have this eleven year back and forth
between the sun beeing sometimes very feroscious,

and it goes crazy, it's like the 4th
of July with fireworks all the time.

And then it starts to r down and for few
years it gets quiter until it gets into

a low point where there is a firecrack
every now and then but not a lot going on.

Just like hurricane's seasons,
solar maximums vary in intensity.

Sun produce many more
powerful storms than others.

Although we're currently at solar
minimum, scientists are watching carefully

to see when may have the
next solar max might unleash.

The last solar maximum was in about 2001

and so the next one ought to be in
2012, but there's different predictions.

The whole field of solar
physics is basically

waiting to baite is breath
to see what actually happens.

There are some loudly divergent
opinions on what's gonna happen.

One group is suggesting
that this next solar

cycle could be the
strongest in modern times.

If those predictions are correct,
Earth could be in for a wild ride.

We might have to worry about
a repeat of the 1859 event.

If that would happen today
it would wreak untold damage.

We're gonna learn a whole
lot about what can happen

to modern technology
when the sun bows its top.

Much of the violence
in the sun erupts here,

in the hellish outer
atmosphere known as the corona.

This region has long held one
of the great solar mysteries.

Because even though it's half a million
miles from the heat generating core,

it burns at millions of degrees.

This seems to violate
the very laws of physics.

That's very strange. I
have a thermometer here.

If I hold the thermometer
close to the fire,

it reads a very high reading.

Where the probe is right
now it's over 200 degrees.

And if I pull the probe out a
little farther from the fire,

ok, it drops down to about 90 degrees.

Now, the farther I get from
the center, the cooler it gets.

In the atmosphere of the corona of the
sun the temperature soars hot as the core.

That's as if, I would say,
well, way half behind me there,

the heat from the fire is
as hot as the fire itself,

even though it's very far from the fire.

What force could possibly cause
the superheating of the corona?

The answer will rock you.

The hellish solar corona
rages at millions of degrees.

For centuries scientists
have been baffled

how anything so far from the sun's core

could still burn so hot.

Recently, as improved satellites offered
a closer view of the solar surface,

clues began to emerge.

Below the corona the sun's
surface is literally boiling.

The reason is that the
entire surface of the sun

is covered with convection cells, hot
material from the inside of the sun,

that rises up through, reaches
the surface, cools off by glowing,

giving off sunlight and
then sinks back down.

Each bubble of material that comes
up is about the size of Texas.

It spreads out across the surface,
cools off and sinks down in 5 minutes.

So, that's a tremendously
violent process

that's happening in, literally,
almost a milion places

over the entire surface of the sun,
all the time around the clock, 24/7.

This boiling is not only
violent. It's also extremely loud.

The sun is a tremendously loud place.

You can imagine... covering
the entire surface of the sun

with speakers being driven as hard as the
loudest rock concert you've ever been to.

That would be comparable to how loud
it really is on the surface of the sun.

The sun's churning surface
creates enough sound energy

to superheat the corona
to millions of degrees.

Scientists believe that the combination
of these sound waves and energy

from the sun's magnetic field

is responsible for the extreme
temperatures found in the corona.

The only time you can actually
see the corona from Earth

is at the climax of one of the most
dazzling displace in the solar system,

a total solar eclipse.

Before scientists understood them,

these unsparing events
instilled only fear.

The ancient Chineses believed that
a dragon was devouring the sun.

So what's really happening
in a solar eclipse?

In simplest terms it's when the
moon blocks our view of the sun.

Imagine that you're sitting in
a movies watching very happily

something going on on the
screen and then somebody

in the row in front of you comes across

and blocks your view.

In a movie, in theory you
might not want that person

to come across in
front of you, but at...

in a eclipse we're very lucky to
have the moon come across the sun,

we're lucky to have it come
right across the middle.

We're also lucky that the moon, although
is 400 times smaller than the sun,

is also 400 times closer to us.

This cosmic coincidence
means that the two objects

just happen to be the same
apparent size in our sky,

which allows for one to
completely block out the other.

This magnificent cosmic
event only happens

when the path of the moon intersects
the line between the earth and the sun.

The moon's orbit is tilted
slightly about 5 degrees.

If it wasn't we would have
an eclipse every month.

And then we'd be bored,

but we're not bored because most months

the moon goes above or below

the place where the line goes
from the earth to the sun.

So instead of one every
month we get a total eclipse

somewhere on earth about
once every year and a half.

As the moon slides in front of the sun,

it casts a shadow onto the earth.

The outer part, where
the shadow is fainter,

is called the penumbra.

If you're standing within the
swath traced by the penumbra,

as it moves along the earth's surface,

then you'll see only a partial eclipse.

But travel to a spot within the
path of the dark inner shadow,

called the umbra,

and you'll experience the
majesty of a total eclipse.

There's another option if you can't
travel to the path of totality,

wait in one place long enough

and a total eclipse will
pass right over your head

about once every 300 years.

The Sun, that shining
star of our solar system

is capable of both astonishing
beauty and ferocious violence.

It seems impossible to believe,

but it won't be around forever.

Eventually even the sun must die.

The sun has a fixed
amount of fuel in its core,

it is undergoing fusion, at
a rate that you can calculate.

So here's the rate it's using its fuel,

here's how much fuel you have,

so it's a simple calculation
to show when the sun will die,

and that's in about
a five billion years.

Well, unfortunately the sun
will not go out with a bang.

It's too small to erupt in a supernova.

However stars do a peculiar thing,

the one of the few things around
that get hotter as they cool off.

As it exausts its hydrogen
fuel our nearest star will cool

and gradually collapse
under the force of gravity.

Energy from this collapse will
start heating up the core again

to hundreds of millions of degrees,
hot enough to start burning helium.

Onto the extraheat of the helium burning

the star will expand into a
monstrous orb called a red giant.

It'll get so big it will engulf

the entire orbits of
Mercury, Venus and Earth.

You don't want to be around for that.

You'd wanna be **climbed**
upping your way to safety,

long before this happens.

The earth is likely to change it's
orbit slightly as the star expands,

so that we won't be engulfed.

Still, talking about global warming,
you wouldn't want to be here.

The outer layers of our sun will
eventually become so unstable

that they will fly off into space,

leaving behind a small core
about the size of the earth.

So now will be shrunk most of the sun,

which is a million miles across
to the size of the earth which is

well like 6000 miles across.

Our once great star reduced
to a slowly cooling cinder.

Life as we know it on
earth will cease to exist.

And that was the death of the sun.

All of this is bad
news for the human race,

but look on the bright side.

We've got five billion years
to repair for this disaster.

For now, humanity basks
in the glow of a sun

in the prime of its life.

Science has uncovered many of
the secrets of our nearest star,

but we remain awed by its beauty,

and ever more wary of its wrath.