All language subtitles for Solar.System.S01E05.Strange.Worlds.1080P.WEB-DL.x264-skorpion_track3_[eng]

We all know the familiar faces of our
solar system.

The worlds we grew up with.

But there's another side to our solar
system

we're now discovering.

The misfits and oddballs.

Worlds of freakish shape and size.

Of extreme landscapes...

..mysterious phenomena...

..and hidden secrets.

Our neighbourhood is far stranger than
we ever imagined.

So, how did all these weird worlds
come about?

Well, to answer that question,

we'll have to explore the force that
sculpted

and created them - gravity -

and the forces that resist its
relentless inward pull.

And also, at a deeper level,

because there's always a deeper level,

we'll be forced to contemplate why
there is anything of complexity

and beauty in our universe at all.

Welcome to the solar system of the
weird.

From a cloud of gas and dust,

gravity, the great sculptor of our
universe,

fashioned our star and all the worlds

and moons around it...

..creating the solar system.

And gravity has continued to shape
these myriad worlds ever since.

Let me give you a little 30-second
lecture on gravity.

And I'm going to use Newton's picture,

not Einstein's,

because we don't need the additional
accuracy

delivered by relativity.

Gravity is a force of attraction
between objects -

and it only attracts,

so that means that it tends to clump
things together.

And it's a force that only depends on
the distance between objects,

not the angle,

and so it tends to make spheres.

It's this property of gravity...

..that shaped the moons and planets.

But beyond the near-perfect spheres
that dominate our solar system...

..out past the giant orbs...

..of gas and ice...

..in a distant realm of the solar
system...

..we found something strange.

Only one craft has been sent to
explore the worlds

of this distant region.

And on its epic, ongoing journey,

the probe caught a glimpse of
something truly bizarre

moving in the dark.

Not a sphere like Earth, or even
Pluto...

..but a giant, 2,000-kilometre-long
egg-shaped world.

Orbiting around it,

two glittering moons.

Mountains of icy rock and a faint
ring.

If you were standing on Haumea's
surface,

the stars would wheel above you six
times faster than here on Earth.

Haumea is a truly unexpected and
bizarre-shaped object.

The first like it ever discovered.

Leaving the question...

..what created such a seemingly
gravity-defying world?

Now, for rocky worlds,

the force resisting the inward pull of
gravity

is created by this,

the rigidity of the rock.

And the thing about pressure is that
it acts equally

outwards in all directions,

so if you have a force that's
squashing everything inwards,

equally in all directions,

and a force that's resisting that
squashing,

equally in all directions,

then the shape that's naturally
produced is a sphere.

And you might say, well, why is
something like that

not a sphere, then?

I mean, it's made of rock,

it's got a gravitational pull,

but it's a very weak gravitational
pull

because it's not very massive.

And that's the point.

So the gravitational forces on the
surface here

trying to squash it down are nowhere
near big enough

to overcome the strength of the rock.

So, how big does a thing have to be

such that the gravitational force is
strong enough

to overcome the strength of the rock

and allow it to deform into a sphere?

And you find, if you wave your hands
around a bit,

that that size, the radius, is
something like

200, 300km.

It's called the potato radius.

And indeed, you find that,

if you look out into the solar system,

anything that's smaller than about a
couple of hundred kilometres

in radius looks like that.

And anything that's bigger than a
couple of hundred kilometres

in radius looks like the Earth.

From what we observe,

it seems that the potato radius is a
pretty strictly-followed rule.

The larger worlds are,

the more spherical they become.

Yet it's a rule Haumea breaks.

Way over the potato radius,

Haumea should be a round world.

So, if its egg shape is not down to
its size,

then what is it?

There is a clue,

found by looking at our world in a
slightly unusual way.

This is a photograph of us working on
the beach today.

I use the term loosely.

And what we did is we took a
time-lapse.

But it's an interesting time-lapse.

We used an astronomical mount,

and so we fixed the camera at a single
point in the sky -

the Sun.

And then, can you see what happens?

So, it's holding its position.

It doesn't look right

because the whole ground is rotating
around.

So, usually, our experience on the
surface of the Earth

is watching the sky and the sun and
the moon and the stars

rotate around us.

But if you take that motion out,

then what you're seeing here is the
Earth

rotating beneath the sky.

This unusual view really brings home
the fact

that we live on a spinning ball of
rock.

And there are consequences for sitting
on the surface

of something that's spinning.

New forces are introduced,

forces that are so called fictitious
forces -

but there's nothing fictitious about
them.

Actually, you'll know that if you've
tried to hang on

to a spinning roundabout.

If you let go, you go flying off.

That's not a fiction.

And that force is called the
centrifugal force.

Like the Earth, all worlds in the
solar system spin.

But Haumea is spinning incredibly
quickly.

The entire 2,000-kilometre-long
world...

..whips around once every four hours.

And that makes the centrifugal force
very powerful indeed.

And I can show you...

..by taking a small thing...

..let's say that's Haumea...

..and spinning it really fast.

So, can you see what's happening?

It was a sphere, and now it's bulging
out.

And it's bulging out along its
equator.

Look at that. That's because the
centrifugal force

tends to flatten things.

Oh!

BRIAN LAUGHS

See?!

You see that?

I mean, there it is, right?

Those are fictitious forces at work.

And that's essentially, actually, what
happened

to some bits of Haumea, we think.

We think it was spinning so fast that
some bits got thrown off.

And...

In fact, there it is.

So what you just saw there was a
demonstration

of how we think this system was
created.

This is the best photo we have of that
system.

And these bits are essentially that
bit

that's now over there somewhere.

There we are. If you look.

Haumea.

The battle between spin and gravity
has created

a truly strange world.

Gravity shapes everything in the solar
system,

and our next destination has the scars
to prove it.

Let the pull from our star draw us
inwards...

..past Neptune...

..until we reach the inner most ice
giant.

Uranus is pretty odd to begin with.

The entire planet is knocked over on
its side,

likely by a giant impact in the past.

But it's not only the planet that's
strange.

Voyager 2 is the only spacecraft to
have visited the moon Miranda.

As it flew past the south pole...

..its cameras saw a truly weird
patchwork landscape.

A jumble of towering mountains the
height of Everest

and plunging chasms deeper than the
Grand Canyon.

One of the most astonishing surfaces
in all the solar system...

..where strange cliffs rise to
unimaginable heights...

..unlike anything seen on Earth.

So, what created the truly bizarre
face of Miranda?

The geology of our world is
awe-inspiring,

even though we're really familiar with
it.

I mean, this island rises two and a
half kilometres

from the surface of the Atlantic
Ocean.

But just imagine what it would be like
standing on the surface

of Miranda.

I mean, there's a slope not unlike
this

that stretches for something like
10,000 metres.

And I remember when Voyager 2 arrived

at Miranda in 1986

and sent back images like this.

That slope is up here.

But one of the scientists at the time

said that this world is exotic.

And you can see why.

One of the explanations for why it's
like this

was that it must have been hit by
something

and then reassembled.

It's like a Frankenstein world.

But we now know the explanation for
this strange geology is,

if anything, even more exotic.

We're pretty sure that Miranda must
receive the occasional impact.

The result would look like it was
playing out in slow motion.

Debris taking the best part of ten
minutes

to slowly tumble to the bottom of
those great slopes.

On Earth, it would take only 50
seconds

to fall the same distance.

Because on this moon -

smaller than the width of the UK -

the pull of gravity is much weaker.

One hundredth of the strength on our
world.

Now, the basic explanation for
Miranda's strange surface

really is just basic physics.

Miranda's very small.

It's only about 470km in diameter -

not too far away from the potato
radius.

And so its gravity is just not quite
strong enough

to squash it down into a sphere.

But there's more to the geology,

to the surface of a world,

than just basic physical principles.

There's also the history of the world.

Miranda's weak gravity is what makes
this landscape possible,

but it's not alone responsible for
sculpting it.

Something must have happened to
Miranda

to create its battered and scarred
surface.

All we have to go on are the glimpses
of this world

captured as Voyager 2 flew by...

..which suggest this moon had a
troubled past.

The key to unlocking the mystery of
Miranda

is to notice that this surface is not
as chaotic as it looks.

It's not entirely random.

There are these three distinct
regions,

which are known as Corona.

And at least on these two external
regions,

there are ridges, fault lines that
surround them -

and to a geologist that's a smoking
gun.

What it suggests is that this surface

was not created by external forces,

by impacts from the outside -

it was created from within.

And it's similar to this landscape
here.

This is new land.

These are volcanoes.

They were created by a hot spot deep
underneath

the surface of the Earth -

and by buoyant hot material rising up

through the surface of the Atlantic
Ocean.

And we think that's what's happened
here.

Buoyant, less dense material rising to
the surface,

creating these features.

It's thought that it was this internal
turmoil

that left ruler-straight canyons

running for hundreds of kilometres
across the face of the moon.

Formed when warm material,

pushing up from the interior,

caused the surface to crack along
fault lines.

Part of the active geology that, over
millions of years,

created this Frankenstein world.

But that raises another mystery,

because Earth's geology is driven by
the heat

stored away from its formation four
and a half billion years ago,

along with the energy released by
radioactive decay.

But Miranda is far too small to have
retained

any of the heat from its formation.

So, where did all that energy come
from?

For the answer, you have to look at
Miranda's relationship

with its parent planet,

and another quirk of gravity.

Probably several times in its history,

Miranda was in a more elliptical orbit
around Uranus.

That meant that it went close to the
planet,

far away, close and far away.

And the changing gravitational forces
injected the heat

into the moon, and that's what drove
its geology.

Gravity sculpting one of the most
tortured landscapes

in the Solar System.

I think the story of Miranda reveals
something quite deep, actually,

about the way that the laws of nature
sculpted

the strange worlds in our solar
system,

and actually the way that they sculpt

everything in the universe.

Because the basic shape, in this case
a sphere,

reflects the simplicity and beauty and
symmetry

of the laws of nature that created it
-

in this case gravity.

But the detail of the surface,

the complexity reflects a turbulent
and often chaotic past.

So you're seeing history frozen in
time.

And it is this interaction between
simplicity

and symmetry and complexity

that truly makes our universe
beautiful.

Beautiful and strange.

Travel further into the solar system

and we enter the realm of the outer
gas giant.

Home to a sight unrivalled in the
solar system.

A structure of outrageous size and
shape.

Rings of rock and ice.

Split into hundreds of ordered,
repeating tracks and gaps

almost engineered in their
precision...

..and looping for thousands of
kilometres

through the void.

So, how did nature create the
intricate, ordered beauty,

the spiralling gaps and tracks of
Saturn's rings?

One of the most obvious things you can
say about our universe

is that, at first sight,

it is very complicated indeed.

But one of the deepest things you can
say about it

is that complexity emerges from the
action of very simple laws.

If you just think about this desert
landscape -

there's all these beautiful sand dunes
and ripples.

But if you look more closely,

there's regularity in the ripples.

And if you look at the sand dunes,

this angle that they fall away at is
always the same.

So there's regularity and beauty and
structure

emerging from the action of simple
laws.

In this case, it's just the wind
blowing sand grains

and gravity pulling them down to the
ground.

And I think the best and certainly the
most evocative example

of that in the solar system has to be
the rings of Saturn.

Yet at first sight, there's nothing
simple about Saturn's rings.

We think they formed when an icy moon

strayed too close to Saturn...

..and was pulled apart by its
gravity...

..creating a jumble of trillions of
individual fragments of ice.

So, what turned such chaos into the
ordered beauty of Saturn's rings?

Nasa's Cassini probe captured the
rings in stunning detail.

And orbiting within them,

it saw one of the most startling
objects

in the entire Saturnian system.

Pan is the most wonderful, bizarre
object.

I mean, look at these photographs
taken by Cassini.

I mean, this is... It looks like a
cross between a UFO

and a piece of pasta.

And it's really small!

It's less than 30km in diameter.

But its impact on the rings is
profound.

The shape, actually, is the key to
understanding how it is that

Saturn's rings are so wonderfully
complex.

And you can see the basic idea...

..here.

So, there's Pan.

And the moon is orbiting inside the
ring.

And so that means that ring particles

can essentially hit them.

They fall onto the surface.

And because Pan has got a very weak
gravitational field,

it's too small - way below the potato
radius.

They don't get squashed into a sphere.

They stay there, sort of a ridge.

So part of the explanation for the
gaps

is that the rings are slowly being
eaten.

For millions of years,

Pan has been nibbling away,

clearing icy particles out of its
orbit.

And yet,

Pan is only 28km across -

but it sits within a track that is
over 300km wide.

Clearly far broader than Pan could
clear through snacking alone.

This moon doesn't just create a tiny
gap in the rings.

It creates a very big gap indeed.

It's so big, in fact, it's called the
Encke Gap.

That gap was discovered using 19th
century telescopes.

It's about ten times the diameter of
the moon.

And the way it does that is really key
to understanding

the complexity of Saturn's rings.

So, I have to tell you one thing,

a very important thing about orbits.

Here's Saturn.

And here is Pan, orbiting around.

Now, it's a property of orbits

that the further away from the planet
you are,

the slower you move.

That's actually traced back all the
way

to the beautiful simplicity of
Newton's law

of universal gravitation.

So that means that ring particles

on the inside of Pan

are orbiting faster.

They're overtaking the moon.

These particles get a gravitational
tug

that tends to slow them down.

They are pulled back by Pan's gravity.

And ring particles further out are
moving slower.

Right, now Pan is overtaking them.

And that tends to give them a
gravitational kick

which speeds them up.

And the effect of that

is that Pan's gravitational pull on
the particles

that are overtaking it tends

to cause them to fall down towards the
planet

and its gravitational pull on the
particles outside -

that it's overtaking -

tend to get raised to a higher orbit
around the planet.

And so Pan clears a much bigger gap in
the rings

than you might otherwise expect.

And Pan is not alone.

Daphnis,

a moon a mere 8km across,

clears its own track.

Tiny worlds

creating structures on a staggering
scale.

What's more puzzling is that so far

these are the only moons we've seen
directly

clearing a track like this.

But there are thousands of looping
spirals and gaps

seemingly created by nothing at all.

Including one of the biggest -

the Cassini Division -

over 3,000 kilometres wide.

So, what's creating these other
structures?

Surprisingly, the answer lies not
within the rings

but out beyond the discs of ice.

There really is tremendous complexity

and structure in Saturn's rings.

Not only gaps, but also sort of
structures -

density waves that wrap around the
planet,

often several times, like the grooves
on a record.

And all those structures ultimately

are caused by hundreds of moons.

Actually, over 140 largish moons at
the last count -

and countless smaller ones.

And all those have a gravitational
influence on the particles

in the rings.

One of the key culprits or drivers of
complexity is this moon,

which looks like a space station - but
it's not a space station.

It's a moon. It's called Mimas.

Another truly odd, almost science
fiction world...

..with its dominant impact crater.

Yet it's not obvious why this moon
should influence the rings,

as it's about 40,000km away.

So, Mimas, it's orbiting outside the
rings,

such that it goes round Saturn once

for every two orbits

of particles that would be inside the
Cassini Division.

So that means that those particles
would regularly meet

Mimas on its orbit.

There's a gravitational interaction,

that disrupts the orbits of these
particles

and moves them out of the division.

Each time the moon and the ice
particles align,

Mimas' gravity tugs at the fragments
of ice and rock

like an invisible hand.

Over millions of years

opening up the giant gap.

And Mimas is just one of over 140
known moons...

..each capable of creating their own
resonances with the rings.

Look at this picture. This is an image

from the Cassini spacecraft.

And you see the complexity here - it's
mind boggling.

This is a resonance with a moon called
Prometheus

that orbits 14 times around Saturn

for every 15 orbits of the particles
in there.

And that causes this disruption,

this structure in the rings.

Here's a moon called Janus.

That creates a recognisable structure

in the rings, and so on.

And these are just the structures that
we've observed.

The orbital dance of Saturn's moons

recorded in the rings.

Creating a pattern we're lucky to see.

Imagine how complicated the
gravitational field

is around Saturn,

and that's what you're seeing.

It's very beautiful.

It's as if someone had sprinkled ice
crystals

over the gravitational field so that
we can see it.

And I suppose that a vinyl record
really is a bit like Saturn's rings.

There's a structure here, a physical
structure, which can give rise

to something that we can perceive now
- sound made solid, in a sense.

When you put a needle on there...

A stylus needle... All right, Grandad!

But also there is of course a sense of
history about a recording

on a record. It tells you something
about the past.

And so it is with the pattern that we
see in the rings.

RECORD CRACKLES

MUSIC PLAYS

In Saturn's rings we can see gravity
at work, shaping our Solar System.

Over half a billion kilometres closer
to the Sun

is a planet on a mind-boggling scale,

so huge you could fit all the other
planets inside it.

Jupiter's immense gravity has helped
shape an astonishing world.

Since 2016, Nasa's Juno spacecraft

has been exploring Jupiter and its
moons...

..including the largest moon in the
Solar System.

Ganymede is a very strange world
indeed.

A moon playing at being a planet.

It's the only moon we know of with an
internally generated

magnetic field, producing strange
aurora.

And elsewhere on its surface,

Juno witnessed bizarre scars gouged
into its icy crust.

These phenomena suggest Ganymede may
be hiding an extraordinary secret.

Ganymede is becoming, I think it's
fair to say,

one of the most fascinating places in
the Solar System.

This is one of our best images of
Ganymede, taken by Juno.

It is a big moon.

This is the eighth largest object
orbiting the Sun,

bigger than Mercury and not much
smaller than Mars.

But it doesn't look particularly
different from our Moon.

But a series of observations are
beginning to suggest to us

that there may be something extremely
interesting indeed

going on below the surface.

One clue comes from Ganymede's aurora.

Detailed observations have shown that
it

behaves in an unexpected way.

To have an aurora, then a planet or
moon needs two things basically,

it needs a tenuous atmosphere and it
needs a magnetic field.

So, what's happening on Ganymede is
that charged particles,

primarily from Jupiter, they're being
funnelled down the magnetic

field lines to the poles, and there
they hit particles in the

atmosphere, they excite them and cause
them to emit light, to glow.

And that's the same process that we
see

here on Earth in the Northern and
Southern Lights.

However, Jupiter also has a magnetic
field,

and that will affect the aurora on
Ganymede.

And so what was done is some computer
modelling. You get Ganymede

with its field and its aurora, and you
get Jupiter with its magnetic

field and you put it all into the
computer and you see what happens,

and you find there is a prediction,
that the aurora on Ganymede

should kind of wobble around, wander
in the vicinity of the pole.

And we observed that.

But we observed that the aurora
wanders far less than it should,

so that implies there's something else
going on.

If Ganymede had an additional, second
magnetic field,

it would interfere with the aurora,
causing it to wander less.

But the only way to generate that
extra field would be

if another layer within the moon
conducts electricity.

I really was never very good in the
lab.

No, it doesn't work!

Have we got another battery?
- Yeah.
- Let's plug another battery in.

Here's an electrical circuit.

There's a battery and a bulb.

And if I connect it, the electrons
flow and the bulb lights up.

But now, look what happens if I take
these two wires,

but connect it by dipping the wires
into salt water.

Very cool, isn't it? So, in here the
circuit is being completed.

Saltwater is a conductor of
electricity.

An electrical current flows and that
can produce a magnetic field.

So, we think that is the origin of
that third magnetic field

that's making the aurora wander far
less than it should.

The implication is, that beneath the
surface of Ganymede,

there's a saltwater ocean.

Welcome to the largest ocean of water
in the Solar System.

It's estimated that there's a layer of
water over 100km

deep wrapped around the moon.

One that never sees the light of day,

hidden beneath 150km of rock-hard ice.

But how can liquid water exist in such
enormous

quantities beneath the frozen surface?

One fascinating theory involves those
strange gouges in the surface.

These are impact craters.

Not single craters, like those found
on other worlds...

..but long chains.

You know, quite a lot of the answer
actually of how it came to be

that Ganymede has an ocean is the
presence of Jupiter.

Yeah, I can see clouds on the surface
of Jupiter through

this pretty small telescope, even
though tonight

it's about 600 million kilometres
away.

You can fit over 1,000 Earths inside
it.

It's massive.

And being massive, it means it's got a
strong gravitational pull.

And Jupiter tends to attract things,

suck things in that come within its
vicinity and rip them apart.

And we've seen that. This is a great
image.

It's one of the most famous images

in astronomy in recent times,
actually.

And you see that? So, that is comet
Shoemaker-Levy 9.

This is a comet that came too close to
Jupiter,

it was drawn in by its gravitational
field, ripped to

bits by its gravitational field, and
then ultimately hit Jupiter.

And it hit Jupiter with such ferocity
that we saw

the impact in the clouds.

And some of them were bigger than the
Earth.

Now, you look at that...

..and then look at that -

the surface of Ganymede.

Being so close to Jupiter puts
Ganymede in the firing line.

EXPLOSION

Ferocious impacts...

..that create the chain craters.

These scars are just a fraction of
what Ganymede has suffered,

living so close to Jupiter.

And that's key to understanding how it
may have got its hidden ocean.

THUNDERCLAP

The early Solar System was a much more
chaotic place than it is today.

Impacts were common.

Everything got hit.

Jupiter's immense gravity drew in
countless asteroids and comets...

..and Ganymede was caught in the
crossfire.

Impacts delivered enough energy to
heat the moon...

..and kick start a process

that caused it to melt and separate
into layers.

Dense heavy metals at the core...

..and an outer shell made of water and
ice.

And we think Ganymede has retained
enough of that heat

to produce a saltwater ocean with more
water actually than all the

oceans of the Earth combined below the
frozen surface of Ganymede.

A strange giant moon with an ocean

and aurora nearly a billion kilometres
away from the Sun.

We're talking about potentially a
habitat for life.

This is a big world, a planet-sized
moon, which has a magnetic field

and a saltwater ocean and a ready
source of energy, it seems.

All the things that we think are
necessary for the origin of life.

And it's important because we used to
think of what's called

a habitable zone around a star, which
is where the

Earth orbits, and indeed Mars and
Venus, just about,

which is the zone where you could
potentially have liquid

water on the world, on the surface of
the world in that case.

But now looking at places like this,

we understand that there might be
habitable zones far

away from stars, in this case a
habitable zone around a gas giant.

And that habitability here is
delivered by gravity.

Leaving this distant ocean moon
behind,

we head inwards on the final leg of
our journey...

..passing through the asteroid belt,

rubble left over from when gravity
failed to pull a planet together...

..until we reach the inner rocky
planets.

The worlds here are home to phenomena

and landscapes that are mesmerising.

So strange and alien.

But amongst all these wonders

lurks perhaps the strangest world of
all.

Welcome to Earth.

It is the biggest rocky world.

Radius about 6,370 kilometres or so.

It's a bit unusual in that it's got a
single moon,

but the thing that makes it very
unusual indeed

is the presence of that - liquid water
on the surface.

You might not think of Earth as
strange,

because we live on it, but it is in
fact a very rare world.

You know, this is a really wonderful

and unusual thing to be able to do in
our Solar System,

because there is no other world where
the conditions

of temperature and pressure on the
surface allow liquid water to exist.

It's a very narrow range.

And that range is set by the details
of our atmosphere.

There are tons... Tons of atmosphere
pressing down

on this rock pool to stop it from
boiling away.

The nature of our atmosphere is
defined by the history

of our world, our place in the Solar
System and gravity.

Now, if you imagine that you'd reduced
the mass of the planet

just a bit, then the pressure would
fall and this would boil away.

If I carried on doing that and reduced
the gravitational

pull some more, the whole atmosphere
would disappear off into space.

All the myriad properties of our
planet have combined,

to allow liquid water to persist here
for over four billion years...

..leading to planet Earth's most
unique feature...

..life.

As we explore the Solar System,

we're discovering ever stranger
places...

.all born of the interplay between
beautifully simple

laws of nature...

..and the deep history of each and
every world...

..creating endless wonders of the
Solar System...

..including...

..us.

Just look at these telescopes,

our eyes on the universe.

Now, I find it so remarkable that on
one strange world in our Solar

System, collections of atoms have come
together that can do astronomy,

because there's nothing particularly
special about the Earth.

It is just another lump of stuff

that has found a way to avoid
gravitational collapse.

But somewhere in between the
relentless inward

pull of gravity and the sheer bloody
mindedness of matter,

some of that stuff has found a way to
contemplate

its place in the universe.

- No other planet has rings quite like
Saturn does. They're beautiful.

But it's odd to think that they might
not be there forever.

- Far from a permanent structure,

we now know that these strange loops
of rock

and ice are constantly changing and
may one day disappear completely.

- We have big questions about Saturn's
rings.

How old are the rings?

How did they form and what is their
evolution like?

How long are they going to last?

- Nasa's Cassini spacecraft studied
Saturn

and its rings for 13 years in search
of answers.

- Cassini allowed us to see

Saturn from closer up than ever
before, but also from new

vantage points that we had never been
able to access from the Earth.

- Cassini witnessed a series of
bizarre moons,

clearing paths in the rings.

But one of the biggest insights came
from its encounter with

a strange kind of rain falling onto
Saturn.

- It was Voyager that gave us

the first hints that particles could
be falling into Saturn.

Towards the end of the Cassini
mission,

when we flew the spacecraft between
the rings and the planet, we were

able to detect small ring particles
that were falling into the planet,

so-called ring rain.

- The immense gravity of Saturn is
pulling on these particles,

eroding the rings.

- Ring rain causes the rings to slowly
die.

But what we don't know is the rate at
which the rings are perishing.

We just know that they are.

- Flying through the icy rain falling
from ring to planet was

one of Cassini's last endeavours.

In 2017, the mission came to an end
before Cassini could find out

how long the rings had left.

To get a definitive answer on the
lifespan of Saturn's rings,

we needed a brand-new mission.

- So, JWST isn't like a normal
telescope

that you would find on Earth.

It's not at the top of a mountain like
the big

telescopes that we have here.

Instead, it is 1.5 million kilometres
away in space.

- The space telescope is designed

to peer into the depths of the
universe.

But its infrared cameras are also
showing us

our Solar System in a strange new
light...

..illuminating the faint rings around
the outer planets

normally invisible to us.

- It's extremely difficult to get to
the outer Solar System,

and so an instrument like JWST that
can look at these distant

objects is invaluable.

- Amongst its targets is Saturn and
its rings...

..where the hope is that the telescope
will be able to help

answer how fast the ring rain is
falling.

- So the rings are made of mostly
water ice

and some of the smallest pieces

flow up the magnetic field and fall
into the planet.

That happens all the way around,

so in our observations, we see this
kind of infrared glow

all the way around the planet, that
location,

which indicates that there is ring
material flowing in.

- In the next few years,

JWST will measure the intensity of the
infrared glow in that band,

revealing how fast the rings are
losing particles...

- I'm very excited to find out

how quickly Saturn's rings are eroding
today

because finding out what's going on
today

is really important for mapping their
past

and predicting their future.

- ..bringing us ever closer to
understanding exactly how

long Saturn's stunning rings of ice
are likely to last.

- There's something about seeing
Saturn's rings.

You have this almost childlike
fascination

and a professional curiosity that come
together in a very unique way.

- Knowing that Saturn's rings won't be
around forever and that we're

here at the exact moment when they are
here is really amazing.

I feel really lucky that we get to
experience them.

- # We're standing on a tightrope wire

# They push me but I don't fall down

# We'll stand until the end together

# Forever and ever... #