All language subtitles for How the Universe Works s02e01 The Furnaces of Life.eng

Our solar system
is a savage place.

From the ice volcanoes
of Saturn's moon Enceladus,

to the vast lava fields
of Jupiter's Io,

to our own world, the Earth,

volcanoes destroy.

They also create.

It is literally true that,
if there weren't volcanoes here,

we would not be here either.

Volcanoes shape
and change our climate.

Volcanoes are the giver of life
and, also, the takers of life.

Today's space probes
and telescopes

reveal volcanoes
on worlds we once thought dead.

Finding volcanoes on an object
that's smaller than our own Moon

was a huge shock.

If volcanoes
exist on other worlds,

could we find life there, too?

== sync, corrected by elderman ==

Planet Earth -- a jewel
in the darkness of space.

Our home is timeless...

beautiful...

and incredibly violent.

Volcanoes are one of the most
powerful natural phenomena

on the planet.

They create new land,

destroy the old.

They blast out gases that
transform the air we breathe.

Deep in our oceans,

volcanic heat
fuels strange new life.

Volcanoes help power
the living Earth.

Now we search for signs of life
on alien worlds.

We know life needs water.

We know it needs energy.

And that's where volcanoes
come in --

they pump out
vast amounts of energy.

Find volcanoes
on other worlds,

and we might find life.

The search starts here --

the planet
orbiting closest to Earth...

Venus, a world that appears
very much like ours.

Venus and Earth
are roughly the same mass.

They're roughly the same
distance away from the Sun.

So they're kind of like twins.

3 billion years ago,

Earth and Venus
were very similar...

...new land, new oceans,
an atmosphere.

Both planets
were perfect for life.

But on Venus,
something went wrong.

Something made Venus

diverge radically
from the history of the Earth.

Venus took a definite turn to
the dark side a long time ago.

Venus is a hellhole,
our evil twin.

Today, Venus' surface
is like a furnace.

It's 900 degrees
Fahrenheit on the surface.

It's hot enough to melt,
actually, some metals,

so you wouldn't stand a chance.

Venus is a greenhouse world.

Its atmosphere
is thick with carbon dioxide.

It traps heat from the Sun
like a blanket.

These actual images
of Venus' surface

reveal a barren,
superheated wasteland.

Venus' thick blanket of CO2
killed the planet.

The CO2 came from volcanoes.

Orbiting space probes
gave the first clues.

Radar punched
through Venus' thick clouds...

...and revealed volcanic
formations across the planet...

...like formations we also see
right here on Earth --

the shield volcanoes of Hawaii.

Shield volcanoes get their name
from their round, flat shape.

These volcanoes ooze.

But they ooze
for thousands of years.

Once we were able to map
the entire surface of Venus

using cloud-penetrating radar,

we started to study
the landforms there,

and we saw a lot
that was actually very familiar.

In particular,
we saw giant shield volcanoes

that are very similar to the
shield volcanoes here in Hawaii.

The radar images of Venus

were dead ringers for
the shield volcanoes on Hawaii.

Sometime in the past,
Venus had volcanoes.

For the first time, we had
a picture of Venus revealed,

and, boy, were we shocked.

We found a scarred surface,
a volcanic surface.

There are at least a thousand
volcanoes that are very large

and maybe tens or even hundreds
of thousands of smaller ones.

3/4 of Venus' surface
is lava plains,

evidence
of an ancient cataclysm.

This could have been
a home for life.

Instead,
it was engulfed by fire.

Volcanoes belched trillions
of tons of carbon dioxide

into Venus' atmosphere.

Temperatures soared.

The seas boiled dry.

A runaway greenhouse process
began.

On Earth, carbon dioxide

is able to absorb
into the rocks.

It's able
to absorb into the ocean.

But on Venus, you have no water,

and it's now so hot

the carbon dioxide can't even
combine with the rocks.

So as carbon dioxide
was released into the atmosphere

by volcanoes a long time ago,

over time, there was
less and less of a method

to take it back
out of the atmosphere.

If Venus ever had life,

volcanoes
sterilized the entire world.

Earth remains the only
living world we know of.

That may change.

This is the gas giant Jupiter,

its moons frozen and dead...

...or so we thought.

Look closer,
and a mystery emerges...

...a cloud hanging
over a cold and lifeless world.

On Venus,

volcanoes turned an earth-like
world into a superheated hell.

Finding volcanoes
on an earth-like world

was no surprise.

But spotting volcanoes
on a moon was a shock.

In March 1979,

the Voyager 1 space probe

gave us our first close-up view
of Jupiter's tiny moon Io...

...a world we once thought
cold and dead.

And they saw
something really weird.

They saw this arc
next to the moon,

and it looked almost

as if like there was
another moon behind it.

And we scratched our heads
and said,

"Well, what could that be?

Everybody knows that io is dead,
boring, uninteresting."

And then people realized,
"Oh, my God.

It's a volcanic eruption."

We found that it's covered
with volcanoes.

It is tremendously
geologically active.

There are volcanoes
erupting all the time.

And what they're erupting
is a lot of sulfur,

and it gets very hot.

And sulfur, when it changes
temperature, changes color.

It can be red or orange
or yellow or black.

And so these pictures
of the face of Io

make it look like a pizza

covered with different kinds
of cheese and olives

where the little black spots
are.

Io is not dead.

It's alive and kicking.

It has
over 400 active volcanoes.

The largest, Pele, erupts
from a gigantic lava lake.

It reaches
nearly 250 miles into space.

If we could stand
on the edge of that lava lake

and watch that plume shooting
off into the blackness of space,

that would be
an incredible sight.

Pele's eruptions are
so huge because Io is so small.

There's nothing
to hold the lava back --

virtually no atmosphere
and very little gravity.

These vast eruptions

make Earth volcanoes
look like firecrackers.

How can such a tiny moon
be so volcanic?

The answer is Jupiter.

Just as the Moon
raises tides in Earth's oceans,

Jupiter raises tides on Io --

tides of solid rock.

Io's orbit around Jupiter
is not a circle.

Sometimes, it's closer.

Sometimes, farther away.

Jupiter gives Io
a gravitational pounding.

And so, Jupiter's gravity

pulls on it a little bit harder
and a little bit weaker.

And what happens is
the moon stretches, like this.

It's called a tidal force.

And it doesn't stretch
this much --

it's only a little bit.

But, in fact,
it's enough to heat it up.

It's just friction.

It's the same way when you rub
your hands together really fast,

they begin to feel warm.

Friction creates heat.

Jupiter's gravity

stretches and squeezes Io.

In every two-day orbit,

the ground rises and falls
by nearly 300 feet.

This pummeling generates intense
heat and gigantic pressure.

Wherever there's a weak part in
the crust, the lava rushes out.

So the volcanism
is on a planetary scale.

Unlike here on Earth,

where there are certain bits
that are active

around the plates
or in weak spots,

this is an entire moon
that's one active hot spot.

Thanks to the
incredible power of gravity,

Io is the most
volcanically active world

in the solar system.

The volcanism on Io
taught us something new.

It taught us
that internal sources of energy

can drive volcanism

in a way that's different
from that on Earth.

In outer space, tidal forces,

the differential squeezing
of the moons of a gas giant,

can also create
volcanic activity --

that was a game-changer.

Io is a lava world,
superheated and violent.

It's hard to imagine
anything surviving there.

Yet the volcanic principle here
is the same as on Earth --

pressurized, superheated magma
below the surface

blasts through fissures
in the crust.

But not all volcanoes
need magma.

They don't even need to be hot.

Travel out past Jupiter
into the outer solar system,

and it gets cold -- really cold.

The distant moon Triton
is so cold

that much of its tenuous
atmosphere can freeze solid.

Yet there are volcanoes here --

volcanoes that may hold
the secret of alien life.

We think of volcanoes
as mountains of solid rock.

Deep beneath,
rock is so hot and pressurized

that it bursts violently out
as lava.

But not all volcanoes
work this way.

There are volcanoes
on other worlds

that don't use molten rock
at all.

Right at the frontiers
of the sun's planetary system,

Triton orbits
the ice giant Neptune.

2 1/2 billion miles
from the Sun,

the temperature is
a frigid 390 degrees below zero.

When NASA's Voyager probe
flew past,

it revealed a world covered
mostly with frozen nitrogen ice.

But the probe
found something else.

When Voyager flew
by, it saw these black smudges,

and all of the smudges
were going in one direction,

almost as if there was a wind

blowing dark material, dust,
in one direction.

Signs of activity

on a world so cold,
it freezes nitrogen --

volcanoes at almost 400 degrees
below zero.

Forget molten rock.

Triton spews out a mixture
of nitrogen and moon dust.

And the geyser
not only has liquid nitrogen,

which is in a fluid form,

but, also, sort of dusty stuff
that's lighter,

that can even go farther
in the weak winds.

So you have this wonderful sort
of double plume of an icy area

and then a darker, smudgy area,

basically made of dust,
like moon dust.

Triton's surface
is nitrogen ice.

Underneath, there are lakes
of liquid nitrogen.

How?

Scientists believe it's because
nitrogen ice lets light in,

but doesn't let heat out.

There's almost a bit
of a greenhouse effect

going on on Triton,

that there's a layer of
nitrogen ice that's transparent.

And just like a greenhouse here
on Earth, when you have glass,

light can pass through it,

but then the heat
is trapped by the glass.

The Sun
shines through the surface

and warms the nitrogen beneath.

Just a few degrees

is all it takes
to turn nitrogen ice into gas.

A temperature gradient,
a change in that temperature --

that's what's important.

And that's enough to melt
the nitrogen

underneath the surface on Triton

and have it burst through
as a geyser.

This is a cryovolcano,

so cold
that the material it erupts

would freeze water
as hard as rock.

The solar system is more active
than we ever imagined.

We have found weird eruptions
on many planets and moons.

But so far, the only world

where volcanoes
are linked to life is ours...

or so we thought.

This is Europa.

It orbits Jupiter nearly
500 million miles from the Sun,

a frozen 2,000-mile-wide
rock-hard ball of ice.

From a distance,
its surface looks smooth.

Up close,
it's a different story.

Jupiter's enormous gravity
gives Europa a pounding,

just like its neighbor, Io.

The surface heaves and flexes,

creating ridges
and deep crevices.

When we first got close-up
images of Jupiter's moon Europa,

they looked a little familiar,

and it turns out
it looks like ice floes

that you see
when you fly over the Arctic.

And it turns out
it's the same thing.

Europa has a several-mile-thick
shell of ice on its surface,

and beneath that
is a global liquid ocean.

Magnetic readings
suggest Europa has an ocean

that's a staggering
60 miles deep.

Jupiter's gravitational pounding

heats the rocky core
and melts the ice above.

It's not unreasonable
to think that, as the core

is being stretched by tides and
heated up, possibly even molten,

there's some boundary

between a hot core
and a liquid-water ocean.

On Earth,

underwater eruptions
are surrounded by life.

The same could happen on Europa.

Here, the darkness is total...

the pressure -- a crushing
2,000 earth atmospheres.

A brutal world,
but perhaps a cradle for life.

If life got off the ground here
on Earth, why not on Europa?

All the ingredients are there --

an energy source --
volcanic activity --

a universal solvent --
liquid water --

a rich hydrocarbon chemistry.

We have this mixing bowl
of ingredients

that happened on the Earth
3 1/2 billion years ago,

and we have similar conditions
on Europa.

So some people are saying,

"If it happened here,
why not there?"

Life on Europa would
be hard, but not impossible.

On Earth, there is life
at every extreme --

searing heat, crushing pressure,
total darkness.

Alien life on Europa
might look surprisingly similar.

If life exists
under the ice cover of Europa,

they would be aquatic,
but without eyes,

because there's no light
to speak of.

They would probably use sonar

in order to make sense
of their surroundings --

organisms that literally feed
off the energy from the volcano.

On Europa, volcanoes
could be the source of new life.

It's even possible
that Europa is normal,

that this is how worlds
with life generally are.

Earth could be the exception.

Think of it --
Europa could be a template

for billions of moons out there
that have liquid oceans on them.

So, all of a sudden,

our horizons have expanded
several billion times

by looking
at the moons of Jupiter.

What a shock.

Our solar system alone
has over 170 moons.

Multiply that
across the Universe,

and that's a lot of places
where life might take hold.

All it takes is liquid water
and a source of energy.

Potentially,
volcanoes provide both.

And they are everywhere.

This is Saturn, twice as far
from the Sun as Jupiter.

Yet it, too, has volcanic moons.

And just like Jupiter's Europa,
these moons could harbor life.

This is one
of the strangest worlds

in our solar system -- Saturn --

a ring system
600,000 miles wide,

an amazing 62 moons,

and one with a secret.

Enceladus is one of Saturn's
smaller, more distant moons.

And it's been known for a long
time that it's covered in ice,

because it's very bright,
very reflective.

But when the Cassini spacecraft
went there,

it discovered something amazing.

The Cassini probe
revealed something incredible --

not on the planet itself,
but on Enceladus.

Backlit by the sun, a gigantic
plume bursts out into space --

a sure sign
of volcanic activity.

It was an amazing discovery,

and it helped answer a question

that has puzzled scientists
for decades --

the mystery
of Saturn's "E" ring.

Saturn's outermost ring is vast,

almost 200,000 miles across,

and it shouldn't exist.

The ice particles
that make up most of the ring

are too far from Saturn
to stay in orbit.

They constantly drift away
into space.

Something
replenishes the ring --

the ice volcanoes of Enceladus.

Those plumes

that are ejected
from Enceladus' south pole --

it turns out
that those are going into space.

And they're not just going away.

They're feeding a ring
around Saturn, the "E" ring.

So this little moon

is giving something back
to its parent planet.

Water blasts
from Enceladus' volcanoes,

hits the vacuum of space,

and instantly freezes
into tiny ice crystals,

creating the vast "E" ring.

One mystery solved.

Another replaces it.

What creates
the volcanic plumes?

Cassini's cameras zoom in
on the moon's south pole

and capture these huge chasms
scarring the surface.

There are
these wonderfully huge cracks

at the south pole of Enceladus,

and as Enceladus
goes around Saturn,

these cracks open and shut
as the tides go by.

Now, these cracks are huge.

They're hundreds of miles long.

And when they begin to open,
you would have this big crevasse

opening at maybe 100 miles
an hour down the length of that.

It'd be incredibly spectacular.

Huge gravitational forces

crack the surface open
and closed at enormous speeds.

Like Europa and Io's orbits
'round Jupiter,

Enceladus' orbit 'round Saturn
is elliptical.

This helps generate the heat
to melt ice

and create oceans of water
beneath the surface.

The conditions of the water

underneath Enceladus' surface

are absolutely perfect for life.

It's the right temperature.

It'd be a good pressure
for life.

Liquid water would be just
like seawater here on Earth.

And the chemistry of the water

we see shooting
out of these vents

suggests that it is
very similar -- there's salt.

There's organic material in it,
as well.

So we've identified a place
in the solar system

where there very well
may be life right now.

Cassini has detected
complex carbon molecules

in the ice plumes.

Combined with liquid water,

they suggest
that just maybe life

could survive deep
within this enigmatic moon.

Enceladus may not be alone.

Another of Saturn's moons
might also harbor life --

Titan, one of the largest moons
in our solar system,

the only moon
with a thick atmosphere...

...a frozen world --

ice as hard as rock,
lakes of liquid methane.

Yet here, too, we might find
evidence of volcanoes

and the tantalizing prospect
of alien life.

A raging inferno
on the surface of Io,

eruptions of ice and nitrogen
on Triton...

Volcanoes are one
of the most destructive forces

in our Universe.

But out of annihilation
comes the possibility of life,

even here on Saturn's
mysterious moon Titan.

It's 3,000 miles across,

larger than the planet Mercury.

It's the only moon
in our solar system

with a thick atmosphere.

There is weather here -- storms,
winds, rain, even lakes --

all so cold that liquid methane
takes the place of water.

And it's loaded with chemicals
that life needs to survive.

Titan has turned out to be
absolutely one

of the most interesting places
in the solar system.

It's an active world.

It's the only moon
with a thick atmosphere --

an atmosphere
very much like Earth,

because it's mostly nitrogen,

and it turns out, an atmosphere
loaded with organic molecules.

Methane gas
high in Titan's atmosphere

reacts with sunlight

and creates the kind
of chemicals life depends on.

But if sunlight converts methane
into organics continuously,

why doesn't the methane run out?

The atmosphere's
full of methane,

and yet we know methane

is being destroyed by sunlight
on a short time scale,

so it shouldn't be there.

There needs to be
a source of methane.

Something on Titan

pumps out a continuous
supply of methane.

Cassini has detected
what looks like a crater.

Its interior
is as deep as the Grand Canyon.

Infrared cameras
reveal different types

of materials
surrounding the crater.

Scientists believe the green
areas could be volcanic,

perhaps plains of lava
ejected from Titan's interior.

If it exists,

lava Titan-style
is a superchilled icy slush.

But compared
to the rest of Titan,

even ice slush is scalding hot.

On Titan, the hot liquid
spewing from volcanoes

might be ammonia or water.

Normally, those are frozen solid
on the surface,

but if they're heated
beneath the surface somehow,

they could erupt out.

On Titan, what comes out of
volcanoes is methane and ethane,

and that's probably the reason

why we have
this very thick cloud cover,

this orange haze around Titan.

This haze

probably came from outgassing
from the volcanoes of Titan.

Even for volcanoes on a world
as cold as Titan, you need heat.

That's what turns ice into
liquid and generates eruptions.

On Titan,
that heat has two sources.

Radioactive materials
warm the interior.

And Saturn's huge gravity
massages the moon,

just like Enceladus.

These two forces
generate enough heat

to turn ice into water

and liquid methane to gas.

We think of volcanoes
as being hot and ice as cold,

and yet if you're out on Titan,

where you're a billion miles
from the Sun

and it's -- it's quite cold,

then those floes

of just-barely-above-freezing
water ammonia ice --

they might be
the hottest things around.

So "hot" is a relative term,

depending on where
in the solar system you are.

Could volcanoes on Titan

give life a chance
to survive here?

Life as we know it
needs an atmosphere...

...a solid surface...

liquid water...

and the heat to drive
chemical reactions.

On Titan, volcanoes
could provide them all.

If you have a volcano on Titan,
you'll have heat added to that,

and all of a sudden,
you'll have liquid water

surrounded
by organic material --

I mean, literally, anything
you need for the start of life.

If life does exist on Titan,

it would be truly alien.

It would breathe hydrogen
in place of oxygen,

perhaps swimming through lakes
of liquid methane

at 300 degrees below zero.

Perhaps there are
oceans of ethane.

Perhaps there are tide pools

and perhaps volcanic activity
and hydrothermal activity.

Perhaps there are hot springs.

Perhaps volcanic heat

could generate enough to get
life off the ground in Titan.

That's a speculation,
but it can't be ruled out.

But we may not need
to travel this far

to find signs of life.

We may find it on a volcanic
world much closer to home...

...the red planet, Mars.

Volcanoes are everywhere

across the solar system.

Worlds like Io,
Titan, and Triton

are complex, dynamic,
and violent.

Once, we thought that Earth

was the only planet
with volcanoes and with life.

Now we find volcanoes
everywhere,

but we have yet
to find alien life.

Volcanoes embody the sheer power
of creation and destruction.

They go hand in hand.

It is literally true that,
if there weren't volcanoes here,

we would not be here either.

In the caldrons of volcanoes
is the origin of life.

Volcanoes create new landscapes,

seed the atmosphere
with complex chemicals,

replace the old with the new.

If volcanoes are bound up
with the processes of life,

then where is the life
on other worlds?

Perhaps the answer
originates in deep time,

when the solar system
was young...

...on a young planet
much like our own.

This is Mars.

3 billion years ago,
it had active volcanoes.

One still remains --

the largest volcano
in the solar system.

The cliffs leading to it
are over 6 miles high.

Mount Everest would sit
comfortably in their shadow,

and those are
just the foothills.

This is
the awe-inspiring Olympus Mons.

It covers an area
the size of Arizona.

Its crater alone
is 53 miles wide.

A goliath like this takes
millions of years to build,

time that volcanoes
here on Earth never get.

On Earth,
the crust is always moving.

Deep below, a single hot spot

pushes magma
through the surface,

building a new volcanic island.

But while the hot spot stays
still, the surface is moving.

The new island
moves away from the hot spot,

and a new volcanic island
takes its place.

Mars is different.

The crust is locked solid.

On Mars, there's just none
of that tectonic activity.

The crust
is one big solid plate,

and so if there's a hot spot,

it just sits there and builds
and builds and builds.

And you get a bigger
and bigger and bigger volcano.

And that's why Olympus Mons
is so huge.

Olympus Mons today

is a frozen relic
of a distant, warmer past.

Mars' shrunken atmosphere

means that Olympus
now reaches almost into space --

a true colossus, an extinct
volcano on a dying world.

But Mars'
ancient volcanic terrain

could, one day,
harbor life again.

The evidence
is right here on Earth.

On Hawaii, volcanoes

have created mysterious tunnels
called lava tubes,

channels left behind

when torrents of molten rock
surge into the sea.

But some are now empty,

and that offers us
an opportunity.

Lava tubes are formed when
you have an underground river

of hot basaltic lava,
2,000-degree magma, molten rock.

And picture it
like a frozen river of water,

with the ice crust
forming on the top.

It's the same thing,

only here,
the crust is solid rock

and the river keeps flowing
underneath and makes this cave,

this lava tube.

Extraordinary recent images

suggest Mars' volcanoes also
may have created lava tubes.

Any planet with basaltic
volcanism, any rocky planet,

will probably have lava tubes.

And now we've found
a couple of them on Mars,

in places
where there are skylights,

places where the roof
has collapsed

and you can see from orbit
right into those lava tubes.

If some tubes have collapsed,

perhaps many others
are still intact,

the ancient relics
of Mars' volcanic past.

Now, after lying dormant
for perhaps millions of years,

these lava tubes could bring
life back to the red planet.

That life will be us.

One of the challenges of
living on Mars for future humans

will be
the radiation environment.

And in particular,
when there are solar storms,

the cosmic rays coming in
can be deadly.

And having a storm shelter
under some large mass of rock

is really the best way

to protect yourself
from cosmic rays.

The tubes and caves
of Mars' extinct volcanoes

might one day
make a perfect home --

holding in air, shielding us
from deadly radiation.

A long-dead volcano

could help fill a world
with new life.

Volcanoes can destroy,
but they can also create.

From the superheated vents
of Europa's 60-mile-deep ocean

to the water volcanoes of Titan
and the rock volcanoes of Earth,

vast geologic processes

shape our worlds,
our imaginations,

and perhaps
the very stuff of life.

== sync, corrected by elderman ==

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