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Eight Wonders Of Our Solar System | The Planets | BBC Earth Science
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the fate of the planets is intricately
tied with that of the star that they
orbit so for our own solar system the
sun dictates Our
Fate as our sun has
changed so has the potential for life on
our neighboring
planets their history show shows that
balance that doesn't always [Music]
last there is only one planet that has
retained its water and
habitability and that's
Earth what remarkable about Earth is the
stability of those conditions that Earth
has been able to maintain Oceanic
conditions at its surface throughout its
entire history through billions of years
and that's what's facilitated the very
rich biological evolution of Earth Earth
is a very special place it's the only
place in the universe where we know
definitively that there is life for that
to happen you need not just liquid water
appearing on a planet but liquid water
staying on a planet and that's the magic
thanks to the size and geology of our
planet the atmosphere has remained
stable enough for billions of
years protecting the precious water that
evolve life has woven itself into the
[Music]
oceans so that
atmosphere that protects our fragile ecosystems
but as the sun continues to grow [Music]
[Music]
hotter temperatures on Earth [Music]
droughts as plants around the world die
plummet around a billion years from now
the age of complex life on
Earth will finally draw to a close
Earth will ultimately be like uh Venus
and Mars Just mostly CO2 there'll be no
nothing else really in the atmosphere
and it will remain in that state as a
sort of hot oven Planet until ultimately
the sun when it uh uses up its hydrogen
and goes into a different phase will
become what we call a red giant you know
as we've seen in other stars throughout
our galaxy throughout the Universe our
sun will continue to get hotter and
hotter over time and in that point it
will expand greatly to the point where
it will uh nearly engulf the Earth
entirely and at that point the uh
planets will will lose their atmospheres
away as it exhausts its hydrogen
fuel the sun's Outer Edge
inflates as our star enters its red giant
giant
phase expanding millions of kilometers
sealed some models predict that Earth
neighbors hanging on Beyond the Edge of
but the long era of the four terrestrial
over the lives lived on one of them
nothing more than a distant [Music]
memory poor Uranus it's got rather
boring clouds truth be told so there
cameras passing close to the planet
featureless temperatures here are the
coldest of any world in the solar [Music]
system there's simply not enough heat to
Saturn Uranus is an entirely new class of
Planet an ice Giant [Music]
[Music]
[Music] come
come
rings we knew long ago from telescopic
observations the Rings were there at
Uranus we didn't didn't know their
shape Voyager begins to explore the ring
shadows two moons Cordelia on the inner
edge of the brightest ring and ailia on
the Outer
particles within the Rings can be moved
inwards or outwards as these tiny
objects called Shepherd moons whose
gravitational force can shape and sculpt
but it's the orientation of the orbits
of these moons and the Rings
themselves that singles out
Worlds Uranus looks bizarre the Rings
rather than looking like that when you
look through a telescope they're
actually orbiting up and over the top of
Planet the whole thing is tipped like a spinning
spinning
top this bizarre orientation hints at an unusual
past since the beginning everything in
the solar system has been circling in
direction it begins with a vast cloud of
planets today they all orbit the
Sun and spin on their axes in the same
counterclockwise direction as that primordial
Cloud except for Venus and Uranus which
spin in the opposite
direction but Uranus is even
stranger because the entire planet is on its
its
side this was a really strange system so
why is Uranus so tipped on its side if a
roughly earth-sized object smashed into
Uranus late in its formation history
then that would have had the proper
amount of momentum to basically knock it
and the Collision may also help to
explain another of Uranus's
cold that impact presumably relinquished
all of that internal energy that the
planet had when it first formed and has
left it as a relatively dead and
[Music]
Encounter but Voyager strangest
what powers weather is very different
depending on where you find yourself in
system the Earth's atmosphere and the
weather on Earth is is driven largely by
one thing and that's the sun and the sun
pours its energy down through the
atmosphere and it hits the surface and
the surface of the Earth then warms
up with Earth you've got all the energy
coming in from the Sun heating up the
surface creating thermals that then uh
then drive the atmospheric flows that we
see somewhere like Saturn doesn't have a
surface to be heated up so when you
compare the weather systems on these
giant planets to those that we have on
Earth you have to sort of tear up the
rule book a little
bit the sun is the great controller of Earth's
Earth's
atmosphere but in the outer reaches of
the solar system where Saturn lives Sun
light is 100 times
weaker it means some other heat Source
weather as Cassini studied the cloud
tops of Saturn it was able to infer a
huge amount about the truly strange
world that must lie beneath and the
energy source that helps power this
planet we had a whole variety of
scientific goals at Saturn and one of
the main ones was to understand the
meteorology of the Saturn atmosphere and
what energizes the winds that we see on
it and so on and we have affirmed now
the belief that atmospheric systems on
Saturn are actually powered by energy
from below from an internal heat Source
on Saturn they're not powered by
earth looking deep inside the planet
pressure within huge clouds of water
Cassini records lightning 10,000 times
this lightning transforms methane
so at 8,000 km deep the pressure of the
atmosphere is 80 times greater than that
at the bottom of our deepest
oceans enough to transform form this graphite
diamonds but even these diamonds are
likely destroyed by the pressures of [Music]
[Music]
30,000 km down and Saturn's heat source is
is
revealed here pressures are so intense
that the atmosphere behaves like a
electricity in this state molon helium
Falls like
rain and as it merges with the surrounding
surrounding
material kinetic energy is released as
heat and it's this extraordinary heat
source that helps Drive Saturn's [Music]
[Music]
weather sent to look for conditions
where where life could have
Orbiter mro sends back more data than
has three cameras on board the first is
the Marcy weather camera it sees Horizon
to Horizon on every orbit so it builds
up a map of the entire planet every day
so you can see a global weather map
Mars the second camera is the context
camera it provides high resolution and
[Music]
mro has made more than 60,000 [Music]
orbits its high resolution cameras
revealing Mars in unprecedented
detail discovering polar [Music]
[Music]
dunes and what look look like seasonal
meltwater then in
2017 mro turns its gaze to one of the
red planet's oldest features the aidonia
Basin thought to have been an ancient
sea aridia Basin is a huge Basin in some
of the most ancient crusts on Mars it
formed about 3.8 billion years ago and
it held more water than 10 times that of
the great lakes or three times that of
[Music]
Earth and it is on the ancient
remarkable emeros saw a massive 400 met
thick deposit formed from a mineral that
formed forms in deep sea hydrothermal
environments such as one that might have undersea
vents Mars not only had the same
ingredients for life as
Earth it also had an active
action aridia Basin was an ancient sea
3.7 to 3.8 billion years ago and that's
about the same time when life was first
emerging on
Earth this might have been a place where
life could have
existed because those hydrothermal vents
underneath that sea might have created a
very conducive environment for
life these initial conditions in the
history of both planets look so similar
that it seems reasonable to expect that
life these actively fertile
conditions are thought to survive in
places like the aidonia Basin for
hundreds of millions of [Music]
[Music]
years but then 3.7 billion years
ago something happens that transforms
prospects for Life on
Mars underwent a fairly substantial
transformation in its climate climate
got colder what liquid water there was
either soaked into the ground and froze
or froze at the surface a lot of It
ultimately would get transported to the
poles where it forms these big thick ice
today at the same time time as the temperature
flooding water rages down from the Southern
Highlands until in a place known as easma
easma
High creating the largest waterfall the
solar system has ever seen [Music]
cascading into a spectacular Canyon 10
km wide by 100 km [Music]
long once the floods subside the water
disappears The only trace it ever
[Music] surface
Neptune an ice giant 17 times the mass of
Earth over 1 and A2 billion kilom
farther from the Sun than Uranus Neptune
yet bizarrely it couldn't be more
different Neptune in a way was almost a
relief because it it wasn't featur L you
know it's like oh good a planet with
again Neptune was a great excitement
it's got swirling clouds really strong wind
wind at 1500 mph incredibly fast the
fastest winds that we've got in the solar
system one of the things that Voyager
discovered was an immense dark Vortex
spot we say it's a giant storm but just
those words don't fully contain we're
talking about a storm the size of a
larger and the surprises keep [Music]
[Music]
coming even though it's much farther
out Voyager discovers Neptune is warmer than
Uranus and the source of the heat is
another Oddity of this strange
planet in fact when we look at this
Dynamic activity in these
extraordinarily cold regions we really
are at a loss to understand just what's
going on
here one theory is that the buildup of
pressure beneath the thick layers of cloud
turns the carbon and the methane into a
diamonds they then melt as they fall
into the interior of the
heat as the heat makes its way out into
the Frozen coals of
space it churns the entire
atmosphere whipping up winds around the
globe there are no mountain ranges no
valleys no Continental boundaries to get
in the way of the perfect fluid dynamical
flows what that means is that when you
start a weather pattern going when you
start a Vortex spinning or you start a
plume Rising there's very little to get
in the way of it so those winds that
develop and go around they just keep
going around around and around there's
nothing to slow them down no friction
surface and the extreme cold
winds that outpace anything seen on
Mercury the least explored of the rocky
planets because of the difficulty of
getting into orbit around a Planet so
Sun 5 4 3 main engine start 2 1 and zero
and lift off of messenger on NASA's
Mercury a planetary Enigma in our inner solar
[Music]
system now going through the sound barrier
barrier
following a direct route to Mercury
would be [Music]
[Music]
impractical a spacecraft would arrive at
such high velocity it would need to haul
a prohibitive amount of heavy fuel in
order to slow down enough we uh just had spacecraft
spacecraft
jettison so messenger controls its speed
by stepping from one planet to the next
using their
itself even so messenger still
approaches Mercury moving so fast that
it is forced to fly past the planet
three times
pass until after nearly 7 years of flawless
flawless
orbit at last able to begin its mission
surface that first image ever acquired
from orbit around Mercury was amazing
when it finally came in it looked
perfect it looked exactly like we
expected it to
be for me that was the real moment when
I realized that we had successfully made
it into orbit and everything was
working this pioneering Voyage has led
to a completely new idea of how Mercury
Mercury is the most cratered planet in
system with many puzzling features that
past mercury has a very unusual orbit if
you were on the surf surface of the
planet you would actually have to go
around the Sun twice to get one full
Mercury solar
day also highly unusual is the planet's
disproportionately large core Mercury is
basically a big ball of metal surrounded
like a tiny bit of rock how do you end
up with a planet that has so much metal
inside and then almost none on its
surface that was a huge mystery and the
major question is is why why is it like
aren't a clue to understanding these strange
strange
features was found in Mercury's
chemistry so very soon after we got into
orbit we started to get chemical data
back from the surface and we immediately
surprises the tiny probe detects
volatile chemical elements in
concentrations that no one had thought
Sun these are elements that go into
rocks but that evaporate at relatively low
temperatures and immediately told us
that some of the older ideas of how
Mercury formed could not be
correct what messenger discovered about
Mercury could suggest a new twist in the
system just a few million years after its
its
formation the young Mercury is seething
slowly a crust
elements if it had been close to the
Sun these elements would have evaporated
before the rock
hardened so what could explain why
they're so abundant on Mercury
today the orbits of the planets and
their current locations have changed
over the history of the solar system so
where things are today doesn't mean
that's necessarily where they formed
they could have and probably did move
from different locations to where they
are now one possible thing is that
mercury didn't form where it is today it
form much closer to the other planets
maybe even outside of Venus or Earth or
in somewhere in between there if Mercury
had formed near Earth and remained at a
Sun its Destiny could have been very different
but it wasn't to
be so what turned it into the strange
today we don't know the full story what
we have right now are theories and as we
have new observations we are trying to
change everything to fit those observations
observations [Music]
[Music]
Messengers evidence of the volatiles on
Mercury surface and the unusual size of
Theory it's possible Mercury began life
as much as 160 million kilm further from
today in the region of space where the
forming a region with scores of
position in the chaos it's possible that
something large pushes Mercury off orbit
Mercury brushes against another planetary
embryo this glancing blow removing much
now little more than a metallic planetary
sun ending up in the peculiar elliptical
today before we sent the messenger
mission to Mercury I think we had a very
simplistic idea of what it was going to
be like and Mercury turns out to be a
more complex place with a more
interesting and complex history than we
had previously imagined but of course
all things have to come to an end and
once we were out of fuel we could no
longer burn our engines to keep from
launch after 4 years of observations
out and the spacecraft adds yet another
crater to this tiny
world where any prospects for life were
scorched away when it was thrown too
the sun's outer Corona Burns at a
scorching 1 million
de releasing a barrage of charged
second the solar [Music]
wind this Onslaught would strip away our
atmosphere but for the power power ful
force that protects
field solar wind is this stream of
charged particles that come streaming
out from the Sun and at Earth which has
a powerful magnetic field when those
charged particles begin to get close to
Earth they get diverted around Earth by
interactions with that magnetic field
that protection keeps solar wind and
other ionizing radiation off of the
surface so on Earth where we have this
really great magnetic field we are nice
safe and sound inside the shell of that
protected from all that radiation the
magnetic field of Earth effectively
forms a protective bubble around the Earth's
Earth's
atmosphere and when the sun dips below the
the
Horizon there are times when Earth's
protective force field is visible [Music]
[Music]
the Aurora is a stunning display of
Earth's magnetic field in [Music]
[Music]
action it's best seen at the poles but
across earth it's protecting our
planet this vital protective shield is
the way a magnetic field is generated
inside a planet is when you have
convective Motion in a fluid that is
capable of conducting
electricity and in the earth that
electrically conducting fluid is liquid
iron and the molten portion of the
earth's core is a place where these
motions take place and it can set up a
magnetic field [Music]
[Music]
just like Earth Mars once had a molten metallic
metallic
core generating a magnetic field around the
the [Music]
poles protecting its atmosphere and seas below
last in the oldest rocks on Mars you see
evidence of a once powerful magnetic
field you get to the younger rocks rocks
that are 3 billion 2 billion 1 billion
years old no evidence of a magnetic
field whatsoever and there is no
today half a bill million years after it
out the bright auroras above its poles
away as the shield that protects the
good once it stops then what happens is
all the atmospheric components things
like hydrogen oxygen that make up water
they get stripped away because you don't
have the shield the magnetic Shield
anymore so the high energy particles
that come in from the Sun and from outer
space they begin to strip away the
water without its magnetic field to
protect it Mars's atmosphere and then
shield what happened deep beneath its
surface that stopped Mars from
Earth the answer lies at the beginning
of Mars's
4.6 billion years ago when the planets
were forming from the dust cloud
sun early differences between Mars and
Earth set the young planets on very different
paths Mars forms further from the Sun
where crucially there is less Rocky
planet Mars is different because it's
not just further out it's actually much
smaller if a planet gets to be too small
through Mars is just half the diameter of
of
quickly and so it lost the heat that
powered the Dynamo that generated its protective
shield Mars's small
millions of years
Moon perhaps 400 km
ice but this Moon is
doomed it's orbiting just too close to
resist the immense forces of Saturn's [Applause]
[Applause]
Gravity the Rings probably formed from
an object that got too close to Saturn
there's this invisible boundary around
Saturn called the RO limit and that's
the limit depending on what you're made
of where Saturn's gravity is strong
enough will actually pull you apart that
the gravity on the side closer to Saturn
is strong enough that compared to the
gravity on the other side that will L
literally rip you apart you don't have
together a leading theory suggests that
just beyond Saturn's
atmosphere an ice Moon approaches close
as Saturn's immense gravitational force
pulls it apart the moon begins to rupture
catastrophically a world ripped apart by
Saturn and thanks to the speeds this
material is traveling it's like likely
that in just a few days it spreads out
[Music]
giant Saturn's iconic
ring is now in [Music]
place but as Cassini turns its
instruments towards it it sees a single
the images we returned they were
phenomenal they were resolution factor
of maybe 20 times better than anything
we had had [Music]
before Cassini reveals how Saturn's
evolved this debris now forms a dis
wider than
Jupiter yet on average just 10 m
thick within moon-sized chunks of ice
voids turning one
many but it's as Cassini captures images
with the sun directly above the
equator that the most surprising feature
of the Rings
emerges we knew this was going to be a
time for us to investigate the third
dimension something that you don't get
to see when you just look at picture of
Saturn's rings and what we found was staggering
just right out of the gate we saw
vertical structures I just can't tell
you how surprised we were to see this
unanticipated I have just
imagined flying along in a
shuttlecraft across the ring right close
to the ring so to my perspective it
would be almost like it was an infinite
sheet of gleaming debris and I'm flying
along and flying along and flying along
and suddenly I come upon a wall of
High I mean is that cool or
what really i' I've said over and over
movie this once Tiny World of rock and
Ice that is has seen the most dramatic
Transformations is today the Solar
Jewel after more than a decade in orbit
Cassini has forever deepened our
understanding of
as the young Jupiter circles the sun it
clears a path through the gas cloud that
envelops the early solar
system but that process causes it to do something
alarming Jupiter begins to spiral inwards
plowing straight through the region of
belt when the young Jupiter moves
through the primordial asteroid belt
things get scattered around things get
gravitationally deflected and as a
consequence of all of this gravitational
interaction more than 99% of the
original mass that was there is
the asteroid belt has been disrupted
over time by the movement of the giant
planets and this has acted to throw
material from the asteroid belt out of
system these protoplanetary cores like
series were never able to graduate to
full-fledged planets because there was
just not enough material in the orbital neighborhood
neighborhood [Music]
when Jupiter passed through the
primordial asteroid belt it starved
growth and the dwarf planet was
condemned to live out its life as a cold
but siries isn't the only World in our
short Mars would suffer a similar fate
Jupiter after marauding through what
would become the asteroid belt
Jupiter enters the region of space where
forming continuing its Journey spiraling
its immense gravity scatters material in all
directions some is sent careering into the
Sun and some is thrown out into Interstellar
space it is because of the gravitational
clearing of this neighborhood by Jupiter
that Mars was unable to grow to more
than 10% of that of the Earth this is
and by clearing material out of the
inner solar
system the giant planet may also have
prevented the formation of the super
systems and if it had continued moving
formed but then just as it looks like
Jupiter will sweep everything
tracks because in the shadows of the
outer solar
forming the solar system second gas giant
everything as Jupiter moved inwards
Saturn moved inwards and caught up to
Jupiter's orbit when this happened the
two locked into a special configuration
known as a mean motion resonance this is
where the planets begin to interact
gravitationally in a very coherent
Manner and now locked as a unit the two
reversed their Mig migration course and
out
retreat leaving behind just enough
material from which the inner planets could
home Earth is in exactly the right
location to provide the environment for
life to develop so if Jupiter had moved
around even more who knows maybe life
never would have developed in the solar
It And as its voyage across the solar
system draws to a
close Jupiter helps to provide our
living world with its most precious [Music]
ingredient today 2/3 of our planet
surface is covered by
ocean more than one 1.3 billion cubic km of
of [Music]
[Music]
life one of the big questions about the
evolution of our solar system is how did
we get water here on this planet so we
think that the inner planets didn't
naturally form with a lot of water water
is primarily in the outer solar system
system but if you end up having Jupiter
and Saturn moving
outwards then that is able to suddenly
system locked in a gravitational dance with
with
Saturn Jupiter moves back through the asteroid
asteroid
belt and as it does so water Rich
material is flung inward
where it is incorporated into the
growing terrestrial
worlds so the movement of the giant
planets have actually played an
important role in the delivery of water
to the inner solar
system in a sense it is Jupiter's
outwards motion through the asteroid
belt that we have to thank for the
delivery of water to the surface of the
Earth the Earth would be quite a
different planet if not for Jupiter's
around 100 million years
ago an asteroid 10 kilm across is
belt dislodged from its orbit by
Jupiter it is now on a collision course
with Earth [Music]
when it
strikes the impact generates a fireball so
hot anything within a 1,000 km radius
the impact throws some 300 billion tons
atmosphere and during the nuclear winter that
that
follows 75% of species plant and animal
are wiped from the face of the
Earth in including the largest creatures
surface by driving the dinosaurs to Extinction Jupiter cleared the way for
Extinction Jupiter cleared the way for us to inherit the
earth and although it still occasionally flings asteroids our
for objects heading toward Earth from the far reaches of the solar
the far reaches of the solar system the giant planet's immense
system the giant planet's immense gravity acts as a
shield around 100 years ago a lump of rock and ice for km
rock and ice for km across is hurdling towards the inner
across is hurdling towards the inner solar
system but Jupiter stands in its way 5 4 3 2 1 we have ignition and liftoff of
3 2 1 we have ignition and liftoff of Atlanta and the Galileo spacecraft Bound
Atlanta and the Galileo spacecraft Bound for
Jupiter 70 years later a mission launches that will witness just how
launches that will witness just how effective a shield Jupiter can
be on board the space shuttle [Music]
[Music] Atlantis the Galileo
Orbiter 3 years after Galileo launches Comet Shoemaker le9 has been captured by
Comet Shoemaker le9 has been captured by Jupiter's
gravity and now locked in the giant planet's deadly
planet's deadly Embrace tidal forces begin to tear the
Embrace tidal forces begin to tear the comet
apart its journey into the inner solar system cut
system cut short what happens next presents the
short what happens next presents the Galileo scientists with a unique
opportunity and so everyone was observing it and they realized two
observing it and they realized two things one is that it had just passed
things one is that it had just passed very close to Jupiter and probably had
very close to Jupiter and probably had gotten pulled apart by Jupiter's tides
gotten pulled apart by Jupiter's tides and the other was that it was going to
and the other was that it was going to crash into Jupiter two years later the
crash into Jupiter two years later the discovery that a comet was about to hit
discovery that a comet was about to hit Jupiter was a huge surprise and very
Jupiter was a huge surprise and very exciting
after crossing the inner solar system Galileo is approaching the
Galileo is approaching the spot where it will witness the comet's
spot where it will witness the comet's final
final moments we knew Galo would be able to
moments we knew Galo would be able to see the flashes
see the flashes directly we knew that the impacts were
directly we knew that the impacts were going to occur on the night side and
going to occur on the night side and that Galo was going to be able to see
that Galo was going to be able to see him
on July 16th Galileo sees the first fragments of the
fragments of the Comet enter Jupiter's southern
hemisphere at 60 kmet per second the fragments really heated The Atmosphere
fragments really heated The Atmosphere Red Hot almost to the temperatures of
Red Hot almost to the temperatures of the sun and the pieces hit the planet
the sun and the pieces hit the planet one after the
one after the other pieces of comet Shoemaker Ley 9
other pieces of comet Shoemaker Ley 9 strike Jupiter over the course of 6
strike Jupiter over the course of 6 days they look like big flashes on
days they look like big flashes on Jupiter the pictures of the impact were
fantastic these tiny Points of Light captured from 240 million km
captured from 240 million km away are the only only time a comet
away are the only only time a comet strike has ever been
witnessed the most destructive impact releases energy equivalent to 6
impact releases energy equivalent to 6 million megatons of
million megatons of TNT leaving behind a giant Dark Cloud
TNT leaving behind a giant Dark Cloud 12,000 km across
by capturing objects in its orbit and incinerating them on impact Jupiter
incinerating them on impact Jupiter protects us from bodies that might
protects us from bodies that might otherwise collide with Earth
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