Space's Deepest Secrets

The giant planets Jupiter, Saturn,

Uranus, and Neptune have megastorms

on a scale that defies belief...

Hurricanes larger than entire worlds

and thunderstorms that would lay waste to the Earth.

We think we have storms on Earth.

Compare it to the storms on the giant planets,

it's on a whole other scale.

Now, astronomers are using these epic storms

to unlock the secrets

of how giant planets across the galaxy might work.

Gas giants remain some of the greatest mysteries

of our solar system, but if you can better understand

the weather that happens within them,

you can start to unlock their secrets.

A fleet of advanced space probes

is helping astronomers study these storms

in unprecedented detail,

revealing astonishing forces at work

deep within the most mysterious planets in the universe.

We have literally

just scratched the surface of these planets.

There's so much to learn about these things,

and we're just barely getting started.

The secrets of the outer planets are revealed

as we plunge into the heart of space's megastorms.

captions paid for by discovery communications

In countless solar systems throughout the galaxy,

two types of planets exist...

Planets made mostly from rock, like the Earth,

and giant planets made mostly from gas.

We have a pretty good handle on how rocky planets work

because we live on the surface of one,

but the gas giant planets are a mystery

because they hide their secrets

below thick, impenetrable clouds.

To decode their inner workings, astronomers must first unlock

the mysteries of the gas giants in our solar system.

To understand how any planet in the universe might work,

we need to first understand how our own solar system

and how our own gas giants work,

and so the only way they we can better understand

what lies beneath these topmost layers

is by studying the storms on the planet's surface.

Can these megacyclones

shed light on the hidden processes

that make all gas giant planets tick?

Astronomers start with

the closet gas giants to the Earth...

Saturn and Jupiter.

These planets are hundreds of times more massive

than the Earth.

Hydrogen and helium fill their atmospheres,

which are thousands of miles thick.

When you compare the Earth and Jupiter,

they are so different.

It's hard to believe they're both called planets,

they're so different, and our weather is different.

Planetary scientist Amy Simon investigates

this radically different weather.

Chasing epic storms on planets over 400 million miles away

is no simple task.

The biggest difficulty in studying these distant objects

is the fact that we can't monitor them all the time,

so if we look at Jupiter once a year,

that's equivalent to looking at the Earth weather once a month

and then trying to figure out what's going on

on the whole planet.

Scientists like Amy now have a fleet

of advanced space probes to help...

Juno around Jupiter

and Cassini around Saturn.

Saturn's weird weather is the first under the microscope.

As Cassini passes over its north pole,

the space probe sends back an astonishing picture

of this strange storm.

It's unlike anything seen on the Earth

and traces out the shape of a perfect 6-sided hexagon.

One of the truly amazing things about being an astronomer is,

sometimes you see things out there

that are completely unexpected,

and the hexagon storm on Saturn was just that.

You see this clear hexagon turning almost as a solid body

at the pole of Saturn, and the first time we saw that,

we just looked at it and said, "no. That's impossible."

How could

such a perfectly symmetrical storm form?

It's easy to assume that it's a one-off,

an outrageous planetary fluke.

But then in 2017,

Juno sends back an image of Jupiter's north pole.

This is a place no astronomer has seen before.

The image reveals a second bizarre weather system...

This time an 8-sided octagon shape.

This is a geometric storm system on a truly breathtaking scale.

Eight megacyclones swirl around a central storm.

Winds rage within each storm at almost 200 miles per hour,

faster than a category 5 hurricane.

Each violent maelstrom is almost 2,500 miles across,

storms the size of the continental USA,

and they gather an incredible 8-sided flower

around the pole.

One of the most amazing things we've seen lately

is actually very close views of Jupiter's Poles.

At this point, we've seen this same pattern for about a year,

so it does seem to be stable, and just being able to see this

on a pole is so much different than what we have here on Earth.

How can such symmetrical storm systems form,

the hexagon on Saturn and the octagon on Jupiter?

And what can they reveal about what's going on below?

Physicist Peter read is trying to find out.

He believes that the rotation of the giant planets

creates the hexagon and octagon storms.

Tighten that up there.

To test his theory, Peter is going to try

and make his own geometric storm in his lab.

Unlike the Earth, the gas giants have no solid surface.

Instead, they are spinning balls made almost entirely of gas

and high-pressure liquid.

Peter uses a tank of spinning water to replicate

Jupiter and Saturn’s atmospheres.

When we look down on this experiment from above,

it's as if we were sitting over the north pole of Saturn

and actually looking down,

so the water represents the atmosphere.

The center of the tank represents

the pole of the planet, and the outer part represents

a lower-latitude part of the atmosphere.

To try and create a geometric storm,

Peter makes the tank rotate in the same way

as one of the gas giants.

The central disk rotates slowly,

forcing the water above it to rotate slower

than the water in the outer part of the tank.

That mimics the gas giants where the rest of the planet

rotates much quicker than the Poles.

Peter believes that sections of the atmosphere

rotating at different speeds right next to each other

create the geometric storms.

To see if he's right,

he needs to track the flow of water in the tank.

What we're now going to do is, we're going to inject some dye,

and we should be able to see

what kind of flow we've produced.

Where the quick-flowing water

on the outside of the tank meets the slower water at the center,

something astonishing happens.

A stable edge forms that traces out a geometric shape.

Well, you can already see a structure.

It's got corners in it,

but it looks as though this has produced something

more like 5-sided figure rather than a 6-sided figure.

It's always a matter of...

To exactly which pattern will emerge.

This experimental run creates a 5-sided Pentagon.

Subtle changes of the exact conditions

in the tank determine what shape forms.

By changing the rotation of the disk,

we can produce anything from triangles, squares,

Pentagons,

hexagons,

octagons.

You name it.

In Saturn’s case,

the conditions give rise to a stunning 6-sided hexagon.

On Jupiter, they create an 8-sided octagon,

and in this case, each side of the octagon

holds a giant storm in place.

So the flow would effectively be acting a little bit

like a kind of barrier

against which the cyclones can bump up against,

and then once they've taken up that position,

then they're basically held in an equilibrium,

and that's what we see.

Although Jupiter and Saturn seem very different,

these incredible storms reveal that the same forces

drive the weather on both planets,

and potentially on all other gas giants across the cosmos.

There is another mystery

surrounding the storms on Jupiter.

On the Earth, the heat from the sun drives the weather,

but Jupiter is much further away

and only gets 4% of the heat that falls on the Earth.

What drives its extreme weather patterns?

Jupiter is a true giant,

large enough to fit all the other planets

in the solar system within its vast globe,

yet we know very little

about what's happening beneath its swirling clouds.

Unlocking its secrets is important

for our understanding of the solar system

and alien worlds that orbit distant stars.

But we now have countless observations of gas giants

orbiting other stars.

They're giant Jupiter-like planets not like Earth,

and so we need to better understand

how planets like Jupiter work in order to understand

how planets beyond our solar system work.

On the Earth,

we know that heat from the sun drives the weather