How the Universe Works

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?

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.