How the Universe Works

NASA's revolutionary Juno probe

is on a daring voyage to Jupiter.

Its goal... to reveal the the deepest mysteries

of our solar system.

Everything we see in the solar system today

is affected by Jupiter somehow in the past or now,

all the asteroids, all the planets,

the moons, the comets, everything.

So in many ways, Juno is actually giving us a view

into the history of our planetary system,

even the history of Earth.

Juno's mission is risky.

Jupiter could eat the spacecraft like that.

But by diving perilously close

to this monstrous world,

Juno could change everything we know about our solar system.

If you want to know what's happening,

you got to get up close and personal.

captions paid for by discovery communications

Independence day, 2016...

Juno arrives at Jupiter

and gets to work.

The probe angles its high-resolution camera

towards this stormy world.

Juno's snaps do not disappoint.

The images returned from Juno are just beautiful.

Suddenly you have this magnificent mosaic

of this planet.

As a human being, I'm like, "oh, my gosh, look at this.

This is amazing. This is coming back from Jupiter."

These are the closest-ever views

of Jupiter, a world 500 million miles away.

But we didn't send Juno just to take pictures.

One of its main goals is to peer deep into Jupiter's dark heart.

One of the big questions we have about Jupiter is,

does it have a core?

And you'd think, well, of course it has a core

like every planet has a core.

The Earth has a core. Everything does.

Well, it turns out, Jupiter might not.

Knowing what lies at a planet's core

allows scientists to wind back the clock billions of years

to the formation of the planets.

If Juno can reveal what lies deep within Jupiter,

it could change our understanding

of how the gas giant formed.

If Juno finds a solid core, it could mean

Jupiter first formed as a rocky planet like earth

then kept growing,

but if Juno finds no core,

it could mean that Jupiter skipped the rocky stage

and formed straight from a cloud of gas.

Answering this question could shine a light

on other mysteries, too.

If we can figure out how Jupiter formed,

we can figure out the rest of the story of the solar system.

So how do you probe down into the interior of a planet

when all you can really see are the very tops of the clouds?

Well, incredibly, you can use gravity.

As Juno orbits Jupiter,

it can sense in its orbit

tiny little variations

in the gravitational pull of Jupiter.

As Juno speeds around Jupiter,

gravitational spikes tug on the craft.

Turns out, some parts of Jupiter are denser than others.

If Jupiter were some solid ball, then as Juno passes by it,

as it passes very close above its cloud tops,

the orbit, the trajectory would be very smooth,

but in fact, if Jupiter has layers,

or places where there is more mass

and places where there's less, then it's gonna pull on Juno

a little bit differently.

Passing over areas of concentrated mass

gives Juno a speed boost.

So what they do is, the engineers back on earth

can basically just say,

"how fast is it moving right now?

How about now? How about now?"

And you build up a map of where the mass is in Jupiter

underneath the spacecraft as it passes around.

Juno's instruments begin to map out

the heart of gas giant,

revealing the mysterious core for the first time.

What Juno found was this amorphous mass,

a fuzzy thing in the center of Jupiter.

It's not as solid as we expected

if it were just a metal and rock core,

but there is something there.

In the center of the planet,

Juno detects hydrogen and rocky material

dissolved and blended together.

It's a type of planetary core we've never seen before.

Astronomers describe it as fuzzy.

We thought we were gonna find an avocado.

Instead, we found a bowl of chili.

It's a hydrogen fluid chili con carne.

So none of our models of the interior of Jupiter

turned out to be correct.

That means we have to go back to the drawing board.

One theory is that Jupiter

didn't form from rocks or gas

but from tiny pebbles less than an inch wide strewn

across the early solar system 4.6 billion years ago.

These pebbles came together.

They accreted to form a massive object

that was the sort of seed, the core of Jupiter.

The swarm of pebbles

clumped together to form one giant core

20 times the mass of Earth,

but these pebbles can't sustain this growing planet for long.

Eventually, we need to make a jump

from those centimeter-size particles

up to really large things, like 100-kilometer planetesimals,

to really kick-start growth of a planet.

As Jupiter grows, its appetite becomes insatiable.

The cores of other would-be planets are drawn in

by its immense pull and absorb on impact,

causing Jupiter's core to transform.

Huge chunks of incoming rock are mixed up with gas

and the pebbles that originally built the core.

We think that core material that might've been there is actually

dissolved and mixed in with the rest of the planet.

This mix of rock, gas, and pebbles

leaves the core in a strange state

somewhere between solid and liquid

or, in other words, fuzzy.

Once Jupiter's core reaches a critical mass,

its gravity pulls in all nearby hydrogen gas,

building the Jovian atmosphere

and leaving the fuzzy core

trapped beneath thousands of miles of thick clouds.

And that is what formed Jupiter as we know and love it today.

Juno's discovery of Jupiter's fuzzy core

could rewrite the book on

Jupiter's early years, but Juno is just getting started.

We haven't even scratched the surface

of the number of mysteries there are.

There's more to Jupiter than meets the eye

as Juno's instruments begin to reveal a darker side

to this giant world.

Jupiter's environment is one of the most vicious

in the solar system, and that's because

of its incredibly strong magnetic field.

And Juno is caught right in the middle of it.

The gas giant Jupiter

holds clues to the mysteries of our solar system,

and in 2011,

NASA launched a billion-dollar mission to uncover them.

Three, two, one, ignition.

And liftoff of the Atlas V

with Juno on a trek to Jupiter.

To reach its target,

Juno embarks on a five-year journey.

Sending any spacecraft to another planet

is gonna be tough, but sending one to Jupiter

is really pushing things pretty hard.

Juno weaves through the solar system

with extreme precision.

The craft battles violent temperature changes

and navigates carefully through the asteroid belt.

If there's a fleck of dust in your path

and that thing slams into your spacecraft,

it could do significant damage.

1.7 billion miles into its mission,

Juno finally nears its target,

but the probe is hurtling towards Jupiter

at 165,000 miles an hour.

Juno is moving really fast.

It's one of the fastest spacecraft ever.

You need to go fast enough to get there, but then you need

to be slow enough to be captured by the gravity of the planet.

You need to get it just right.

Entering orbit around

Jupiter is the trickiest part of the mission.

Get it wrong and Juno could slam into the planet

or drift out into deep space.

To successfully get Juno to enter a stable orbit around

Jupiter as almost the same as, say,

shooting a basketball from London

and having it on the land on the front of the rim in New York

and just sitting there balanced.

I could do it, but can NASA do it with Juno?

NASA has a neat game plan.

Juno performs a backflip in space

and fires its thruster towards Jupiter.

Everything is going smoothly.

We're continuing to burn and change our velocity.

The rocket burns for 35 nail-biting minutes,

reducing the craft's speed by 1,200 miles an hour.

Finally, the probe achieves orbit around Jupiter.

Right on July 4th during the fireworks

we just got into orbit.

In many ways, we're firing a rocket motor.

I mean, it is fireworks.

Safe in orbit,

Juno turns its instruments to the planet

for a crucial part of the mission...

investigating Jupiter's magnetic field.

Deep below the stormy surface, liquid metallic hydrogen