All language subtitles for How the Universe Works (2021) - S09E03 - Secrets of the Sun_track3_[eng]

NARRATOR: There's a
violent star at the center

of our solar system.

The immense power, the
roiling, boiling surface,

the massive plumes.

It's ridiculous.

NARRATOR: And our
planet is at its mercy.

There are explosions and
big giant eruptions of plasma

that head straight to Earth.

We have to understand these
better to protect ourselves.

NARRATOR: The Sun is a churning
cauldron of nuclear reactions.

Revealing its inner workings
was once mission impossible.

But not anymore.

We've recruited this
network of spies, if you will.

We've built a fleet
of spacecraft that

monitor the Sun 24 hours a day.

NARRATOR: With the Sun
under close surveillance,

we just might have what it
takes to defend our planet.

[explosion]

September 6, 2017.

A flash of ultraviolet and
X-ray light erupts from the Sun,

sending a burst of
radiation toward Earth.

We call it a solar flare.

Flares are huge explosions
on the surface of the Sun,

throwing light out
into the solar system

and absolutely baking
anything in its path.

These are really powerful
events erupting from the Sun.

And we are fundamentally
in the line of fire.

NARRATOR: The flare
up is so intense it

causes radio blackouts
across the side

of the Earth facing the Sun.

And the timing could
not have been worse.

The problem was
at this time, there

were hurricanes in the Atlantic
bearing down on the Caribbean.

And there were people trying to
get in there and rescue folks.

NARRATOR: Radio communication
between disaster relief teams

goes down for most of the day.

Space weather and Earth weather
combined to create chaos.

HAKEEM OLUSEYI: It's not
just an academic exercise.

Your very lifestyle
depends on understanding

how the Sun behaves.

We need to be able
to predict what

the Sun is going to do next.

And in order to do that, we
need to have eyes on the Sun,

as many eyes as we can get.

RADIO VOICE: 3, 2, 1.

NARRATOR: That's why NASA has
put together an elite unit.

RADIO VOICE: We have ignition.

And we have liftoff.

NEWSCASTER VOICES: Liftoff.

And liftoff.

On an international mission
of the solar physics.

NARRATOR: A fleet of
daring spacecraft.

We humans have come a long way.

If you go back a
few thousand years,

people were worshipping the Sun.

And today, we've built
a fleet of spacecraft

that monitor the
Sun 24 hours a day,

observing it from
every angle, predicting

what it's going to do next.

That's nuts.

NARRATOR: Leading
the pack is the Solar

Dynamics Observatory, or SDO.

It keeps a telescopic
eye on flares blasting

out from the Sun's surface.

24 hours a day, the
probe is on the lookout.

It's constantly vigilant.

PHIL PLAIT: It looks
at the Sun and a lot

of different wavelengths
in exquisite detail

so that we can see exactly
what sort of high-energy events

are happening on the Sun.

NARRATOR: The record
for the longest service

goes to SOHO, our sentinel
monitoring the Sun

and its faint outer atmosphere.

PHIL PLAIT: The
Solar and Heliosphere

Observatory, or SOHO, is the
old hand at studying the Sun.

It's been up there for
25 years observing,

not just the Sun itself, but
the environment around it.

NINA LANZA: Instead of
looking directly at it,

it actually blocks
out most of the lights

that we can see all these
beautiful structures

that surround the Sun.

NARRATOR: And then
there's the new recruit...

The Parker Solar Probe.

Our scout going deep
behind enemy lines.

PAUL M. SUTTER: The
Parker Solar Probe

is going to give us the
closest look at the Sun

that we have ever had in
the history of humanity.

DAN DURDA: We're flying
so close to the Sun,

we're flying through the
gases of its atmosphere.

NARRATOR: 29 other
craft make up the fleet,

each with their
own role to play.

PHIL PLAIT: This
fleet of spacecraft

that we have, the overall
mission is to observe the Sun

scientifically, learn about its
behavior, but also importantly,

to learn about the effects
that it has on Earth.

NARRATOR: Our look-out
probe, the Solar

Dynamics Observatory, or
SDO, spots something hellish.

PHIL PLAIT: Today's
forecast for the Sun

is predicted to be 10,000
degrees Fahrenheit with winds

of up to 600 miles per second.

And a pretty decent
chance of rain.

You don't want to
be in this rainstorm

because your umbrella
isn't going to help you.

Solar rain isn't water.

It's plasma.

Hot plasma.

NARRATOR: Rather than a
solid, liquid, or gas,

the entire Sun is made up of a
strange fourth state of matter.

Plasma.

MICHELLE THALLER: Plasma is
just simply gas that's very hot.

So hot it's lost
some of its electrons

and become electrically charged.

And the wonderful
thing about plasma

is that once it has
that electric charge,

you can direct it
with a magnetic field.

NARRATOR: And the Sun has the
most powerful magnetic field

in the solar system.

It twists and flows
through the entire star.

PHIL PLAIT: The
Sun's magnetic field

is incredibly complicated.

There are lots of loops
of magnetic lines coming

out of the Sun's surface.

GIBOR BASRI: As you
go above the surface,

the magnetic field begins to
control where the gas can go,

and you get these beautiful
loops and other structures

above the Sun that
are just showing you

where the magnetic field is.

NARRATOR: The SDO spacecraft's
jaw-dropping videos

of rain on the Sun show
plasma flowing along

huge looping magnetic field
lines that have punched

through the Sun's surface.

PHIL PLAIT: Because the
surface of the Sun is a plasma,

and these loops of magnetic
fields are coming out of it,

it draws that plasma up
which then cools and rains

down as a plasma rain.

NARRATOR: Tracking these
loops of magnetic field

and plasma could help
explain solar flares.

And it could give
us some warning.

September 2017.

Minutes before the devastating
mid-hurricane radio blackout,

our solar lookouts
spotted an explosion

on the surface of the Sun.

PHIL PLAIT: Suddenly you have
this tremendous flow of energy

and an explosive release of it.

And we call this a solar flare.

This is SDO's specialty
of observation.

NARRATOR: The craft
tracked the magnetic loops

above the Sun's surface.

They were highly unstable.

SDO takes very detailed pictures

of where the flows are.

You can actually see gas
flowing from one place.

You can see the magnetic loops.

This magnetic flux loops
are kind of like wires

carrying electricity.

When they're on their
own they're fine.

But if they get too close, they
can connect and short circuit.

And then you get a
tremendous release of energy.

The Ghostbusters were
really on to something.

Don't cross the streams.

NARRATOR: The contact between
magnetic loops released an epic

explosion of high-energy light.

This radiation altered
our planet's atmosphere.

Radio waves jammed,
causing blackouts

at the worst possible moment.

PHIL PLAIT: Solar flares
are happening on the Sun

90 million miles away.

Who cares, right?

Well, think of it this way.

A really good solar
flare could be

the equivalent of,
oh, say 10 million

hydrogen bonds going off.

How's that sound?

Solar flares happen a lot.

And they do affect us.

They have affected
us in the past.

And they will again
in the future.

NARRATOR: But the Sun's
twisting magnetic fields

do more than just disrupt
our communications.

And when we see
flares, we've got

to keep an eye out on those.

But sometimes, there's
something even bigger.

NARRATOR: The Sun launches
huge clouds of plasma

across the solar system.

PHIL PLAIT: All of
that material can

come to the Earth and
really mess things up here...

Blow out our power grid, destroy
our satellites, even physically

harm our astronauts in orbit.

NARRATOR: Can the solar
fleet safeguard Earth?

November 5, 2018.

An explosive cloud
of plasma hits

the Parker Solar Probe
as it orbits just

15 million miles from the Sun.

We have this fleet of spacecraft

out there viewing the Sun.

And they are also under
attack by the Sun.

There are explosions
coming from its surface.

Is not just light, but
explosions of hot plasma.

And the Parker Solar
Probe got blasted.

And yet it survived.

NARRATOR: A huge
blast of high-energy

charged particles launches
into the solar system

at millions of miles an hour.

A coronal mass ejection.

But our solar scouts is
prepared for the onslaught.

PHIL PLAIT: The
Parker Solar Probe

gets very close to the Sun.

And it has a heat
shield to protect it.

But if it gets hit by a
coronal mass ejection,

it has to be protected
against that as well.

And so it's been
radiation hardened

to survive such an impact.

NARRATOR: Could these blasts
pose a danger to our planet?

A coronal mass
ejection accelerates

subatomic particles.

And it's not a little
bit of particles.

It could be up to a
billion tons of them

screaming across the solar
system at high speed.

And this is something we
need to take very seriously.

NARRATOR: To understand these
dangerous blasts of plasma, we

have to look at their source...

An area around the Sun
known as the corona.

PHIL PLAIT: The Sun's corona
is kind of like its atmosphere.

You can think of the Sun
itself as being a ball of gas.

And then outside of that is this
ethereally thin gas stretching

out for millions of miles.

NARRATOR: The corona
is a difficult thing

to study because the
surface of the Sun

is so bright it blocks our view.

We can only see the corona
during a total solar eclipse,

when the moon blocks
the Sun's bright glare.

Astronomers, though,
we're impatient.

We don't want to have to wait
for a total solar eclipse,

which only happens
once or twice a year.

So we figured out a way
to make an artificial one.

And it's really simple.

NARRATOR: One member of the
solar fleet has it covered.

Our solar sentinel, SOHO,
creates its own eclipse

by obscuring the blinding
Sun with a circular plate

in front of the probe's camera.

Sometimes the best solution
is the simplest solution.

You know, instead of trying
to make a sensor that could

actually see the full dynamic
range of the Sun's light,

why not just block out the
light that we don't need?

NARRATOR: In July
2012, SOHO spotted

a huge chunk of
the corona blasting

off into the solar system.

Seconds earlier, another probe
monitoring the solar surface

spotted a bright flare.

Were these events connected?

GIBOR BASRI: If
a flare goes off,

it can disrupt those loops.

And if you get the right
kind of disruption,

the whole thing
can just blow open.

And then you have
a tremendous amount

of billions of tons
of hydrogen blown

off into interplanetary space.

And that's a coronal
mass ejection.

NARRATOR: Coronal mass ejections
are solar flares on steroids.

If a solar flare
was a firecracker,

coronal mass ejection is
more like an atom bomb.

NARRATOR: And if a coronal
mass ejection comes our way,

it hits hard.

The first thing it
does is it compresses

Earth's magnetic field.

And then it wraps
around the Earth.

And this causes the magnetic
field itself to rearrange,

reconnect, and
streams of particles

travel down those magnetic
fields toward our poles

and impact the atmosphere.

Our shields are up.

But they are able to
penetrate our shields.

Our shield being our
own magnetic field.

NARRATOR: Once they
breach our defenses,

the particles of a coronal
mass ejection can wreak havoc.

In August of 1972, tensions
were running high in Vietnam.

[bombs exploding]

Two dozen sea mines
detonated at the same time

when their magnetic
sensors were tripped.

A satellite was lost because
of the electromagnetic pulse

that ripped through it.

And an Air Force sensor detected

what looked like a
nuclear explosion

somewhere here on the planet.

NARRATOR: Fortunately,
scientists

quickly found the real culprit.

A coronal mass
ejection had ripped

through the Earth's
magnetic field

and triggered magnetic sensors.

The crisis soon de-escalated.

PHIL PLAIT: The Sun is
an immense ball of plasma

860,000 miles across.

We are not going to be
able to stop it from doing

whatever it wants to do.

What we can do is learn to
predict what's going to happen.

So we're doing that now.

NARRATOR: Our new fleet
of solar observers

are our first line of defense.

PHIL PLAIT: The Sun
is a little over

90 million miles from Earth.

It takes light a little
over eight minutes

to get from there to here.

As rapidly as a coronal
mass ejection is traveling,

it still takes a few
days to get here.

We can watch the Sun to see
is there going to be an event,

or is an event starting?

And these satellites
can then tell

us, hey, you better be careful.

You might need to batten
down the hatches on Earth.

NARRATOR: But there
may be an earlier clue

the fleet can watch out for.

Vast, dark regions moving
across the solar surface

called sunspots.

HAKEEM OLUSEYI: We
know that this is

the wind up before the release.

This thing is getting
ready to blow.

NARRATOR: In March of
1989, a solar eruption

caused blackouts across
Canada and malfunctions

on board the space shuttle.

RADIO VOICE: We've been
seeing some erratic pressure

signatures out of tank 3, as
well as some manifold pressure

spikes in that system.

NARRATOR: 11 years
later, the Sun

emitted a flare that was
so powerful it blinded

the solar fleet's sensors.

11 years after
that, the Earth had

a near-miss with the most
powerful coronal mass

ejection ever recorded.

The Sun has a very
predictable, but actually quite

mysterious cycle of activity.

It gets very, very
active every 11 years.

And then it settles back down
to more of a peaceful existence.

NARRATOR: This 11-year
cycle has astronomers

scratching their heads.

One thing we do know is
that violent solar events

seem to be preceded by dark
patches on the solar surface.

Sunspots.

HAKEEM OLUSEYI: Sunspots are
large areas on the surface

of the Sun, much
bigger than the Earth,

that are caused by incredibly
strong magnetic fields

disrupting the flow of plasma.

NARRATOR: And every 11
years, these dark spots

grow in number like clouds
gathering before a storm.

When you start seeing
more and more sunspots,

there's an expectation
that you're

going to see more intense and
more frequent solar flares.

NARRATOR: But what drives
this 11-year cycle?

It's kind of ironic
that one of the most

predictable things about the
Sun is also the most mysterious.

PAUL M. SUTTER: We've been
puzzling over the sunspot cycle

for generations.

And now finally we have
spacecraft headed to the Sun

to try to give us some answers.

NARRATOR: The SOHO, SDO,
and STEREO spacecraft

monitor the Sun's atmosphere
using ultraviolet telescopes.

They spot flashes of
high-energy ultraviolet light

moving across the Sun.

These waves of light
could be connected

to the cycle of sunspots
and to the Sun's outbursts.

Because everything
we see on the Sun's

surface is controlled by violent
processes deep in its interior.

The Sun is a very simple onion.

At the very, very
center is the core where

the nuclear fusion happens.

A layer surrounding
that is known

as the radiative zone, where
most of the energy gets

pushed out through radiation.

Then surrounding
that is something

called the convective
zone, where there's

great plumes and
chains of plasma moving

up and down, up and down.

NARRATOR: But unlike an
onion, the layers spin.

MICHELLE THALLER: There
are currents inside the Sun

we don't see from the surface.

Layers of the Sun
deep down inside

are rotating at different
rates than the layers above.

GIBOR BASRI: So it turns out
the inner part of the Sun

is rotating at maybe
three times more

rapidly than the
outer part of the Sun.

We also can see on the
outer part of the Sun

that the equator is rotating
more rapidly than the pole.

NARRATOR: These layers of plasma
grinding against each other

generate the Sun's enormously
powerful magnetic field

and give rise to sunspots,
plasma loops, and solar flares.

This differential
rotation takes the field

and starts twisting
it around the Sun.

So as the magnetic
field gets too twisted,

it starts knotting up.

And these knots start
bubbling up to the surface.

And that's what we're seeing
actually with the sunspots.

And that's why you see
all these wonderful loops

and prominences
coming off the Sun.

Once the magnetic fields start
twisting and interacting,

they can direct the plasma
into vast rivers and loops

both above and below
the surface of the Sun.

NARRATOR: Why these events flare
up every 11 years is a mystery.

But now new observations
from the solar fleet

could provide a clue about
what triggers the solar cycle.

Giant, moving magnetic fields
beneath the Sun's surface.

We think that the ultraviolet
light flickers are telling

us where the magnetic field is.

In the course of
the 11-year cycle,

the Sun's magnetic
fields begin to move

down from the poles closer
and closer to the equator.

NARRATOR: As the magnetic field
lines move through the star,

they carry huge amounts
of plasma with them.

The magnetic field lines act
like shepherds for the plasma

underneath the surface.

And they push plasma down
to the equator of the Sun.

NARRATOR: The magnetic
fields trap enormous amounts

of plasma, like
water behind a dam,

until eventually
the floodgates open,

and the plasma
comes rushing out.

When the magnetic fields
meet, they cancel each other out

and release the plasma,
which goes as a tsunami wave

back to the polls.

MICHELLE THALLER:
When that plasma

rebounds from the equator and
hits the magnetic field coming

down from the poles
at the mid latitudes,

you get a huge burst
of magnetic activity.

NARRATOR: Magnetic activity that
triggers sunspots and loops.

Also explains the 11-year cycle.

We think that this
relationship between

the magnetic fields, the
ultraviolet flickers,

and the plasma drives
the 11-year cycle.

We think this is what's
actually doing the work.

NARRATOR: The solar cycle
has wound down for now.

But once the next plasma
tsunami rushes through the Sun,

our star will kick
start into action again.

Over the next few
years, we're going

to start to see more sunspots,
more activity, more flares,

more ejections, and
more space weather

that we have to deal with.

NARRATOR: Our fleet of solar
spies is poised and ready.

But flares and
coronal mass ejections

are not the only
solar attacks we have

to shield ourselves against.

There's a strange,
invisible force

flowing through the
entire solar system.

There is this great
wind of high-energy

particles from the Sun.

A million mile-an-hour wind.

NARRATOR: And it can be deadly.

[explosion]

In November 2019, the solar
fleet watched as Mercury

sailed across the Sun.

JESSIE CHRISTIANSEN: Mercury
is the closest planet

to our Sun in our solar system.

So it's on the
front line receiving

all of this radiation.

An incredible amount of energy.

And it's such a tiny planet.

NARRATOR: Temperatures on the
innermost planet's surface

reach 800 degrees Fahrenheit.

But scientists discovered
something unexpected

on Mercury.

Frozen pools of water
hidden in its craters.

It's one of the last places
in the solar system you might

expect to find ice, on
Mercury, one of the hottest

planets in the solar system.

KEVIN WALSH: Despite
the overall really

high temperatures
across the whole planet,

there are regions...

Typically deep within craters...

That are permanently shadowed.

So there's never direct sunlight
on those regions of Mercury.

And you can keep things as
cold as ice in those craters.

NARRATOR: But where
did the ice come from?

When we first saw that
there was ice on Mercury,

we thought something must
have brought it there.

Something like a comet,
which is made out of ice.

But there's a new
idea that maybe

the materials that
make this ice are

actually coming from the Sun.

NARRATOR: The Sun creating
ice sounds strange.

But recent research shows
it's not as crazy as it seems.

MICHELLE THALLER: We often
think of space as being empty.

But in fact, we are bathed
in a wind, a million

mile-an-hour wind of high-energy
particles from the Sun

all the time.

The solar wind.

NARRATOR: A stream of
subatomic particles

called protons
constantly flow out

from the Sun in all directions,
bombarding the planets

of our solar system.

CARLY HOWETT: The solar wind is
so strong when it hits Mercury

that it can break down
some of the minerals

and rocks on its surface
into their constituent parts.

And those parts, especially
if they have oxygen in them,

can go to reform and
form water, which

if it forms in the right
place, can then stick around.

NARRATOR: Protons in the solar
wind combined with oxygen

to form water molecules.

They condense and
freeze in craters

which never see sunlight.

So even on the Sun's closest
neighbor, ice builds up.

But the solar wind
doesn't stop at Mercury.

The solar wind has
a tremendous impact

on the world's of
our solar system.

We think it's responsible
for the planet Venus

becoming this hell hole of heat.

NARRATOR: Up until as recently
as 700 million years ago,

Venus was a lush water
world with conditions

suitable for life.

But the solar wind blasted
away the water vapor and oxygen

from Venus's atmosphere, leaving
carbon dioxide to dominate,

trapping the Sun's heat,
and causing surface

temperatures to skyrocket.

Mars was once habitable too.

But the solar wind quickly
took care of that as well.

PAUL M. SUTTER: We believe
that billions of years

ago, Mars had an atmosphere,
and it had oceans, and rivers.

It looked a lot like Earth.

It was gorgeous.

But that solar wind stripped
away the Martian atmosphere

and turned it into the barren
wasteland that it is today.

NARRATOR: And Earth is
in the line of fire too.

It's bombarded every day
with solar wind particles.

So how has life survived?

MICHELLE THALLER: One
of the things we really

take for granted is
how well protected

we are here on the Earth.

The atmosphere absorbs a lot
of harmful things from space

and from the Sun as well.

But also our magnetic
field deflects

the solar wind around us.

And we still have an atmosphere.

And when the charged
particles come from the Sun,

the magnetic field
lines trap those

charged particles
and redirect them

to the poles of the planet.

PHIL PLAIT: The physical effect,
the direct physical effect,

of getting bombarded
by these particles,

they can generate the Aurora
borealis, the Northern Lights.

And these are spectacular
and beautiful.

NARRATOR: Auroras are beautiful.

But they're also the front line
in the battle between Earth

and the solar wind.

Without our protective
shield, we'd suffer

the same fate as Venus or Mars.

But there is a mystery
surrounding the solar wind.

One of the things we
know about the solar wind

is that it is hugely energetic.

A million miles-an-hour.

What gives it that energy?

NARRATOR: Astronomers think
the source of the solar wind

lies in the inner corona, the
atmosphere of the Sun revealed

by our solar sentinel, SOHO.

SOHO's data shows that
near the Sun's surface,

the wind speed is close to zero.

But by the time the win
gets to the outer corona,

it accelerates to
720,000 miles-an-hour.

Something happens mysterious
between the surface of the Sun

and the corona that gives
a punch to the solar wind.

NARRATOR: To investigate,
we need to visit the corona.

So NASA sent a scout on a daring
mission behind enemy lines.

The Parker Solar Probe,
that's a daredevil.

This is designed to
dive bomb the Sun.

[explosion]

NARRATOR: The Sun exerts
a hostile influence

on the planets of
our solar system.

The solar wind.

It's fast.

It's lethal.

But we don't know how it works.

MICHELLE THALLER: We have
spacecraft between us

and the Sun that can actually
see what's coming towards us

and how it will impact us.

But what scientists have
never been able to explain

is what actually accelerates
the wind away from the Sun.

This has been one of the biggest
mysteries of the Sun so far.

NARRATOR: For decades, we
had no way of solving it.

Until now.

There really are some
of these wonderful moments

when you're a scientist.

And I was actually at the launch
of the Parker Solar Probe,

standing right next
to Dr. Eugene Parker,

who the probe is named after.

NEWSCASTER VOICE: Liftoff
of the Parker Solar Probe.

MICHELLE THALLER: Long
ago, he had proposed

the Sun probably had
a wind of particles

that affected the Earth.

And people basically
laughed at him.

But he was proven
right over time.

And as that giant delta rocket
slowly went up from the pad,

he and I both got to be bathed
in that light, and smile.

There has been
no spacecraft ever

in human history to
fly through the corona,

the very atmosphere of the Sun.

GIBOR BASRI: Didn't work
out well for Icarus.

And we hope it works
out well for Parker.

The thing about
going near the Sun

is, the closer you go to it,
the closer your temperature gets

to its surface temperature.

And its surface temperature
is 6,000 degrees,

which vaporizes metal easily.

NARRATOR: Surviving close
to the Sun is a big ask.

But reaching the Sun?

That's an even bigger challenge.

It's very hot.

It tends to melt
your spacecraft.

That's the obvious problem.

A less obvious problem is
it's just hard to get there.

This is something I think that
it's very hard for most people

to grasp.

There have been
suggestions of, you

know, let's send all our
nuclear waste into the Sun,

or our trash, or whatever.

And it turns out to be
very difficult to drop

anything into the Sun.

NARRATOR: The
reason is the Earth

is circling around the Sun
at 67,000 miles-an-hour.

That's good because that means
we don't drop in to the Sun.

We stay at the same distance.

But if you do want
to drop into the Sun,

you'd have to lose
that velocity.

And that's a lot of velocity.

NARRATOR: To lose speed
the Parker Solar Probe

swings by Venus, performing
a gravitational slingshot

in reverse.

MICHELLE THALLER: Now usually,
a gravitational slingshot

gives us more velocity.

So if we're flying out
to Pluto, for example,

we might whip the spacecraft
around the planet Jupiter.

It actually takes the spacecraft
and gravitationally slingshots

it forward, making go faster.

The thing that we have to
do with Parker Solar Probe

is the opposite.

We're going to use a
gravitational slingshot,

but not to speed it up...

To slow it down.

NARRATOR: Parker's
gravitational maneuvers

send the craft on a
trajectory inside the Sun's

extended corona,
closer to the Sun

than any spacecraft before it.

This probe actually dives
really deep toward the Sun.

So it's actually going through
some of these coronal material

and can actually observe
it directly in a way

that other probes can't.

NARRATOR: Using its extreme
ultraviolet telescope,

Parker spots vast,
dark regions below.

There's really
interesting regions

called coronal holes
where you can see

literally deeper into the Sun.

NARRATOR: Coronal holes are
areas of the Sun's coronavirus

where the atmosphere is
cooler and less dense.

And when the probe passes over
a hole in the coronavirus it

gets a bigger blast
of the solar wind.

NARRATOR: These coronal
holes appear to be

the source of the solar wind.

And we think it's
through these holes

that the solar wind is
able to escape the Sun.

NARRATOR: The big
question is, how

does the solar wind actually
accelerate away from the Sun?

It seems to defy logic.

You would think that as
something leaves the source,

it would probably start
to slow down, or at least

stay the same speed.

But this doesn't.

It gets faster.

MICHELLE THALLER: Something is
accelerating the solar wind.

It gets faster and
hotter as it moves away

from the surface of the Sun.

And the mechanism is a mystery.

NARRATOR: To solve the
mystery, our solar scout

dives close to the Sun...

Not to see what's going
on, but to listen.

[strange noises]

That sounded spooky.

That sounded really spooky.

You know, for something
that's so big and powerful,

it's very gentle sounding.

It really, you know,
disguises the fact

that it's incredibly
destructive and would

kill me in an instant.

NARRATOR: These
strange sounds could

actually reveal what
gives the solar wind

its destructive power.

Fluctuations in the
Sun's magnetic field

generate waves that roll
through the particles

of the solar wind.

These acoustic waves
transport particles with them

that give them energy.

Think about a surfer
actually going

down the surface
of a wave, going

faster and faster all the time.

NARRATOR: These waves could be
what accelerates the particles

in the solar wind from 0
to 720,000 miles-an-hour,

giving them the momentum
they need to reach

far into the solar system.

The solar winds travel
just incredible distances.

You know, they go past
the Earth, past Jupiter.

They've even been
seen past Pluto.

MICHELLE THALLER: It really does
pack a wallop, even all the way

at the edge of our solar system.

One of the things that really
surprised me is that Pluto...

There are bits of its
atmosphere being blasted off

by the solar wind all the time.

Tons of atmosphere a day
are being lost from Pluto.

NARRATOR: The solar
wind is powerful enough

to blast past the planets to the
very edges of our solar system.

When we sent members of the
solar fleet to investigate,

we witnessed a battle between
the Sun and interstellar space.

A battle that could decide
the fate of our planet.

[explosion]

The Sun blasts the solar system
with a storm of particles.

The solar wind.

But how far does
that wind reach?

For 40 years, the oldest
members of the solar fleet

have been on a
long-range reconnaissance

mission to find out.

The Voyager program,
it was a wonderful idea.

A grand tour of the outer
solar system in the latter part

of the 1970s.

In fact, both Voyagers
have traveled so far now

that they've effectively
reached the outer edges

of our solar system,
that boundary

zone where the Sun's influence
wanes and the stars take over.

NARRATOR: Over 11
billion miles away,

the Voyager probes cross
over into interstellar space.

But have they reached the
edge of the solar wind?

Voyager 2, it was able
to sample the environment

around it and found the usual
mix of solar wind particles

give way to a different
flavor of particles

with different energies,
the general interstellar

mix of particles that are just
hanging out in our galaxy.

The solar wind actually smashes

into and shocks up against the
gas of the interstellar medium.

We discovered the edge
of our solar system.

And it was much more
dramatic, much more active

than we anticipated.

NARRATOR: Interstellar
space is violent

and dangerous, teeming
with lethal radiation.

Supernova blasts and
colliding neutron stars

send cosmic rays across
the galaxy straight

toward our solar system.

But these deadly threats
are stopped in their tracks.

MICHELLE THALLER: We
really do live inside kind

of a protective bubble that's
being blown by the solar wind.

You see, as the solar wind
moves out into our solar system,

it carries with it the
Sun's magnetic field.

That magnetic field
protects us from the highest

energy particles the universe
can come up with... cosmic rays.

In some cases, a single
proton can have as much energy

as a 100 mile-an-hour fastball.

NARRATOR: Without this
protective bubble, called

the heliosphere, cosmic protons
would smash through your cells,

damaging your DNA.

Ironically, the
solar wind is deadly.

But without it, we
wouldn't be here.

PHIL PLAIT: Like
we saw with Mars,

the solar wind has the ability
to wipe out life on Earth.

But out there in the furthest
reaches of our solar system,

it's defending life on Earth.

So in a way, it's
a giver of life.

And it takes life.

A yin and a yang.

NARRATOR: And now
for the first time,

the Voyager probes have
looked back at the heliosphere

from the outside, revealing
what our solar system looks

like as it moves through space.

Something that we lose sight
of sitting here on Earth,

watching the Sun go around,
watching the planets go around,

is that the Sun itself is
actually hurtling through space

really, really fast on an
orbit around the center

of our galaxy.

If our Sun were
perfectly stationary,

then the heliosphere
would be a perfect sphere.

But because it's
moving, it's plowing

through that
interstellar medium.

And so that makes
one end shorter

and the other end longer.

And new research is showing it's
even more complicated than that

where we might have
like a double tail,

almost like a buttery
croissant surrounding the Sun.

NARRATOR: Our Sun
shapes our world

and protects us from the
dangers of interstellar space.

It's the engine that drives
the entire solar system.

And now, for the first time,
our fleet of solar spacecraft

shows us how it works.

We're pretty familiar
with the Sun, right?

You see it all the
time during the day.

Lights up the Earth.

Provides us with heat.

But observing it with all
these other satellites, all

these observatories, has
shown us a side of the Sun

that we knew nothing about.

JESSIE CHRISTIANSEN: We have
this whole fleet of spacecraft

orbiting the Sun taking
observations in all

of these different wavelengths.

X-ray, ultraviolet,
optical, infrared.

They tell us about the
functioning of the Sun

from its outer atmosphere
down to its deep core

and give us a window into its
functions and its evolution.

Put them all together, and we
finally have an understanding

of our source of life itself.