The Planets and Beyond

Dazzling...

Legendary.

The most beautiful planet in the night sky.

But secretive Saturn has been holding out on us.

We've learned a vast amount about it,

and most of this has been very surprising.

We thought we knew those bodies.

We had no idea.

Saturn boils

with extreme weather and weird lights.

The rings ripple and twist,

bullied by over 60 remarkable moons.

- They are individual worlds. - They each have a story to tell.

This is a planetary explorer's dream.

Saturn's moons are the hottest property

in the search for alien life.

If there's one place in the solar system

I would put a bet that life exists there right now,

I would choose Saturn.

Have you ever dreamed about traveling out of this world?

My name is Mike Massimino,

and I turned that fantasy into a reality

when I space-walked to repair the Hubble space telescope.

Great job, Mike.

Now as we expand our knowledge of our solar system

from Mercury to the cosmic unknowns,

I want to take you on a personal journey to...

captions paid for by discovery communications

welcome to "the planets."

I'm astronaut Mike Massimino.

Walking in space gives you

an unparalleled view of planet earth.

It's so amazing, you can't believe it's real.

Now imagine looking at Saturn up close,

with its distinctive rings,

and try to fathom how breathtaking that would be.

But what's amazing about Saturn

is that its best features may be hidden.

Saturn, the Jewel of the night sky,

dazzles with its beauty and scale.

It's huge...

So big, you could fit more than 700 earths inside it.

But don't let size fool you.

One of the more interesting things about Saturn

is that it is so big, compared to how much stuff is in it,

that it's actually lower density than water.

The old joke is that if you could find a bathtub big enough

and fill it with water, Saturn would float,

but it would leave a ring.

Other planets have rings,

but none so vast and glorious as Saturn's.

The journey from the outside of the main rings

to the inside edge is 66,000 miles,

yet this vast collection of dust and ice particles

is whisper thin, just tens of feet in places.

Racing within the rings and orbiting far outside them

are over 60 moons made from rock and water ice.

They range in size from tiny snowballs

to worlds with active geology, liquid water,

weather systems, and possibly even life

a billion miles from the warmth of the sun.

It's so cold out there, we just thought

there'd be nothing there, and we were so wrong.

We were so wrong.

Saturn's first shocker...

Its wild weather.

The storms on Saturn are extremely violent,

unlike anything we see on the planet earth.

In fact, Saturn has the second-fastest winds

in the entire solar system.

These winds race through Saturn's cloud tops

at over 1,000 miles per hour,

four times faster than earth's strongest cyclones.

And lightning bolts flash

up to 10,000 times more powerfully

than those on earth.

Everything on Saturn is just so very, very much bigger.

I mean, there are weather systems

that are as big or bigger than the earth.

Saturn's ferocious weather is surprising,

because, on earth,

weather is driven by the heat of the sun.

It causes the seas to evaporate, creating clouds and rain.

Saturn lies too far from the sun to feel the same warmth,

so the heat that drives its weather

must be coming from somewhere else.

To understand this mysterious heat source,

we need to go back 4 1/2 billion years

to the birth of the ringed planet.

The planets of our solar system emerged

from a vast swirling cloud of ice, dust, and gas.

The same ingredients can still be found on earth today

in places like Iceland,

where volcanic ash mixes with icy glaciers.

If you want to build a giant planet like Saturn,

this pile of raw material here is a great visual analog.

There's a lot of oxygen and hydrogen in the universe.

That makes water. That makes water ice.

And the stuff, initially, that made the solar system

is basically this stuff here.

It's dirty ice, water ice with a little bit of...

Little bit of rocky and metallic minerals left in there...

Out there in the cold of space.

4 1/2 billion years ago,

a vast cloud of dirty ice particles

shrouded in hydrogen and helium

collapses under its own gravity,

and at the center, a new star, our sun, sparks into life.

The heat of the new star

melts the ice closest to it and blows away the gas,

leaving only rocky debris behind.

But farther out, icy material and gas survive.

A boundary forms, a frost line

between the rocky inner cloud and the icy gas beyond.

Once you fired up that campfire, if you will,

what would be left behind in the inner solar system's

gonna be this stuff,

the silicate minerals you make a planet like the earth from.

But far away from the sun, where it's colder,

you cross the frost line,

and what's out there is still cold enough

to maintain the ice behind,

and there's a lot of it there.

At first, you make sort of a solid core of this material,

but when you reach a critical mass,

you've got enough gravitational influence

to start to directly draw in some of the hydrogen and helium

in the interplanetary cloud.

Saturn's huge, solid core,

now 10 to 20 times the size of earth,

generates relentless gravity and draws in gas.

The bigger this gas ball gets, the more material it sucks in.

Saturn's massive gravity then gets to work

on its fledgling atmosphere, compressing it.

And like any gas under pressure, it gets seriously hot.

Even today, Saturn's high-pressure atmosphere

heats its core to 21,000 degrees,

twice the temperature of the surface of the sun.

And it's this heat rising up

which forms Saturn's distinctive bands

and drives its extreme weather.

Saturn's actually rotating very quickly.

It's a large planet.

It rotates once on its axis about every 10 hours.

So, as the weather comes up from the interior,

it gets smeared out into bands.

And at Saturn's north pole,

the bands do something

that, at first glance, seems impossible.

There is a gigantic vortex,

a spinning region of air

that's shaped like a perfect hexagon.

You have waves of pressure, density, and temperature

that start to interact with each other.

And these waves can actually interfere

and become one big wave

that goes all the way around the planet.

This giant wave settles into a long-lasting pattern,

because there's no rocky surface below

to disrupt the winds that form it.

They form a beautifully defined, regular hexagon.

It's one of the most spectacular things about Saturn.

It took robotic probes

to reveal the weird weather on Saturn.

But if these close-up shots of storms and lightning

took scientists by surprise,

they were nothing compared to the shock of what came next...

The rings are alive.

Without a doubt,

Saturn's rings are its most captivating feature.

Cassini, an unmanned spacecraft,

was the first probe to enter Saturn's orbit,

spending 10 years capturing images

of both the planet and its rings.

Before Cassini's photos,

we thought the rings were just static,

but now we know they're more like a chaotic motor speedway.

Imagine Saturn without its rings,

just a pale globe floating in the darkness of space.

With the rings, it's magical.

When I was 4 or 5 years old,

my parents bought a small department-store telescope.

And I remember looking down into that eyepiece

and seeing this perfect Jewel of a planet.

From the eyepiece of a small telescope,

the rings seem quiet and serene.

But up close, it's a very different picture.

We know this thanks to a space probe called "Cassini"

and liftoff.

Launched in 2007,

Cassini became the first spacecraft

to study Saturn and its moons up close.

It was also the first spacecraft to orbit Saturn

and send back photos from inside its wild rings.

Ice particles jostle for position like stock cars,

traveling inside the rings

at hundreds of thousands of miles per hour.

These particles range in size

from chunks of ice as big as houses

to the finest powder snow.