[Music]
when it comes to Saturn it's hard to
summarize just how lucky we were to have
the Cassini hyan
Mission four robotic probes have visited
sattin but of those Cassini hyans has
hands down been the most impactful and I
mean that both literally and
scientifically its data has provided the
Bedrock for over 4,000 research papers
it discovered six new moons and helped
better understand their composition it
survived 20 years traveling 7 billion
kilm and spent 13 of those years around
Saturn itself Gathering data on Saturn's
gravity magnetosphere its rings and its
structure and Cassini kept Gathering
data right up until the last moment of
its life as it plunged into the mustard
clouds of Saturn's atmosphere and
ultimately broke into thousands of
people
pieces couple that with the fact that it
provided some of the most jaw-dropping
or inspiring images of Saturn and the
solar system to date and you have one
hell of a
mission I'm Alex molan and you're
watching Asam join with me today for
this Cassini super cut as we explore its
Grand Finale the period of time before
the dive what it discovered before and
during its plunge and the incredible
discoveries continuing to be made to
this day from the clues that Cassini
hyans provided
us if you want to see Saturn's Beauty
there is no better way to do it than
Through The Eyes of Cassini in its Grand
Finale the first probe to reach Saturn
was the Pioneer 11 probe in
1979 it was at this time that scientists
confirmed that Saturn's largest moon
Titan had an atmosphere
spere they knew they had to go back and
visit the moon but this time with a
Lander Now Voyager 1 and two were
already on route to Saturn at that point
so naturally it was too late to include
Alanda with those missions thus Cassini
hyans was born and in October 1997 it
was launched into
space getting a spacecraft to Saturn is
no mean feat as the whole trip was
combating the gravity of the sun trying
to pull Cassini back to the inner solar
system so to help achieve the speed
needed to reach Saturn Cassini used
planets as gravitational assists it flew
by Venus twice before returning back to
Earth Earth's gravity then slingshotted
it towards Jupiter which gave it the
final push needed to reach Saturn this
alignment of planets which allowed these
gravity assists only occurs once every
600 years so timing in this case was
crucial and Cassini really scraped past
Earth from the second time around too it
was only 1,100 kilm above Earth's
surface at its closest
approach this is made even more
interesting when you realize what
actually powered Cassini it was by three
rtgs or radioisotope thermoelectric
generators basically the power source
came from about 33 kg of radioactive
plutonium
it's this radioactive decay which gave
Cassini power and even until the end of
its life it still produced about 700
Watts the issue with the spacecraft
carrying this radioactive substance was
that if scientists had gotten their
calculations wrong and a crash landed on
Earth everybody on the planet would have
been exposed to the
radiation now 33 kg spread out over the
whole earth is a very small amount but
in the worst case scenario NASA
estimated it would have caused about
5,000 deaths from
cancer they put this down as an
acceptable risk though as the chances of
this happening were only one in a
million Cassini used RGS because solar
panel technology wasn't good enough at
the time for the sun to power something
so distant with rtgs Cassini would have
a very long operational life and it
might still be able to carry on even now
if it wasn't for the fact it eventually
ran out of propellant
fuel Cassini had numerous objectives to
understand the structure and dynamic
behavior of Saturn's rings explore
Saturn's moons more fully measure the
magnetosphere of Saturn study Saturn's
atmosphere and study Titan more
extensively this last part is where the
hyans part of Cassini hyans comes into
play you see hyans was a Lander attached
to the Cassini spacecraft designed to
see what was going on under the hazy
clouds of
Titan hyans is the part of the mission
built and operated by Isa the European
Space Agency the probe was only about
1.3 M wide and weighed 300 kg when it
detached from the Orbiter it spent 22
days in space before entering Titan's
atmosphere the only system aboard that
was active at this point was a wake up
timer due to wake up the probe only 15
minutes before it entered the
atmosphere and when it woke up what it
saw was
amazing this video is an actual Spar up
version of the 2 and 1 half hour
descent the main mission of Hans was
actually about this descent taking
readings from the atmospheric pressure
its composition wind speed and so on and
because the mission was only to measure
atmospheric readings the battery life
wasn't expected to last long Beyond The
Landing the scientists thought they
could be landing on an ocean or lake and
so had designed hyans
accordingly from what you see though it
actually landed on what could be the bed
of a dried up
Lake the mission for Cassini itself has
been remarkably successful as well as
scientific data it has picked up over
the course of those last 13 years is it
has been able to provide some of the
most stunning pictures found of space I
just want to showcase some of my
favorites of Saturn and of course
Saturn's moons are beautiful in their
own right too and some very dedicated
Souls have even taken 1 million photos
Cassini has taken to show us what it
would be like to be sitting on the
Cassini
spacecraft these are real images they've
only been color corrected and enhanced
and put in order to show movement
there's no CGI it's simply
amazing as cassini's fuel began to run
low scientists began to consider how
best to get the most data they could out
of the time they had left to achieve
this they sent commands to Cassini
telling it to perform some very close
flybys of the planet and some of its
moons getting closer to Saturn and his
rings than it ever had
before beginning on November 30th 2016
Cassini repeatedly climbed high above
Saturn's North Pole then plunged to a
point just outside the narrow F ring
which is the edge of the main Rings
completing 20 orbits in total then on
the 22nd of April
2017 Cassini would leap over the Rings
to begin its final series of Daring
Dives between the planet and the inner
edge of the Rings this was the Cassini
Grand Finale a series of loops and Dives
that brought the probe closer and closer
to its object of study facing greater
and greater danger as it flew until
finally as its data became purest as
Cassini would fly into the Embrace of
Saturn itself cassini's chance for
annihilation would become
certain NASA's website States the reason
for this final mission as it plunges
past Saturn during the grand finale
Cassini will collect some incredibly
rich and valuable information that the
mission's original planers might never
have imagined the spacecraft will make
detailed maps of Saturn's gravity and
magnetic fields revealing how the planet
is arranged on the inside and possibly
helping to solve the ome mystery of how
fast the interior is rotating it will
vastly improve our knowledge of how much
material is in the Rings bringing us
closer to understanding their Origins
cassini's particle detectors will sound
example icy ring particles being
funneled into the atmosphere by Saturn's
magnetic field and its cameras will take
amazing Ultra close images of Saturn's
rings and clouds No Other Mission has
explored this unique region so close to
the planet what we will learn from these
activities will help improve our
understanding of how giant planets and
families of planets everywhere form and
evolve at the end of its final orbit as
it would fall into Saturn's at
atmosphere Cassini would complete its
20year Mission by ensuring the
biologically interesting worlds
Enceladus and Titan would never be
contaminated by Hardy microbes that may
have stowed away and survived the
journey intact it's inspiring
adventurous and romantic and a fitting
end to this thrilling story of Discovery
but let's take a closer look at some of
these final
moments during cassini's Grand Finale
NASA became willing to trade cassini's
prospects for longevity for a chance at
unprecedented levels of closeness to
Saturn this was an easy trade to make
after all Cassini was running out of
fuel so its survival was already off the
table making this decision meant Cassini
was given the go-ahead to approach the
planet closer than ever before darting
in between the Rings but what did it see
did this unique perspective show
anything we've never seen before let's
take a look at some of the awesome sites
Cassini saw during its Grand
Finale well starting with the moons of
Saturn it has seen some of the shepherd
moons in unprecedented
detail this is a close approach of Atlas
a 40 km wide Moon near the outskirts of
the a-ring what looks remarkable about
this moon is the lack of impact craters
on its apparently smooth surface making
it look absolutely bizarre
dust from the Rings is collecting over
the surface particularly around the
equator of the Moon smoothing it over
and giving it this disc shape a similar
thing happens with the second innermost
Moon of Saturn pan at 30 km wide and
found in the enka Gap any particles from
the rings that stray into the 350 km
wide path get swept up by pan this keeps
the Anker Gap steady and
constant dap this is another Shepherd
Moon sadly not seen in quite so much
detail but due to the Gap it is located
in its effects can be seen for hundreds
of kilometers it is only 8 km in
diameter and is found in a very narrow
Gap in the a-ring called the Kila Gap
its gravity is very weak but it is just
enough to whisk the nearby dust
particles as it brushes by this creates
these waves or a ripple effect in the
nearby rings sometimes even ripping
material directly out of the ring
visible in this little Trail
here not only do these ripples move side
to side but up and down too as can be
seen by the Shadows they create I can
only imagine what it would be like to
sit on dness and watch as waves follow
its orbital path with glorious Saturn
and as many moons in the background it
would be quite the sight to
behold talking of the Rings that
Cassini has been able to capture some
spectacular images one of my favorites
from the grand finale is this one
showcasing the Janice 21 spiral density
wave amazingly what you're looking at
here is the result of the same process
that creates spiral galaxies just much
more tightly wound what appears to be
many separate Rings is actually only two
spiral arms looping around the planet
many times so every second line you see
in the image belongs to the same spiral
arm this image is part of the B ring at
a position where the ring orbits twice
for every one orbit of Saturn's moon
Janice causing an orbital
resonance this photo gives the illusion
that the image is tilted away at the top
left but this isn't the case the
illusion is created by the way density
waves propagate from the planet the
wavelength decreasing with the distance
from the resonance and this is where the
resonance gets even more
mind-blowing Janice the Moon that
contributes to the resonance switches
positions every four years with its
close neighbor Moon
Epimetheus every time this switch takes
place the Rings respond creating a new
Crest in the waves NASA says the
distance between any pair of crests
corresponds to four years worth of the
wave propagating Downstream from the
resonance which means the wave seen here
encodes many decades worth of the
orbital history of Janice and
Epimetheus according to this
interpretation the part of the wave at
the very upper left of this image
corresponds to the positions of Janice
and Epimetheus around the time of The
Voyage of flybys in 1980 and 1981 which
is the time at which Janus and epeus
were first proven to be two distinct
objects this encoding reminds me a bit
of a tree trunk encoding how many years
it's been alive by the amount of rings
it has simply
amazing apart from other beautiful and
detailed images of the Rings other
interesting sightings have been these
little propeller features dotted around
the Rings in a number of locations this
image shows both sides of the Rings the
top image shows the illuminated side and
the bottom the unlit side scientists do
this to compare and try to figure out
details even though the scale of the
image is only a about 500 m per pixel
the moonlet might not even be able to be
resolved you might just be able to see
some trace of it in this top image but
what can be seen is that the moonlet is
physically connected to the Rings by
this band of
materials as I mentioned this wasn't the
only moonlet trying to create a gap in
the Rings here is another found right
next to the Anchor Gap and here is
another and probably the biggest out of
all three
none of these moonlets are thought to be
bigger than 2 km and probably have the
density of a
snowball the last interesting thing
Cassini was able to image within the
Rings is extremely small but solid
objects which have formed around the
eering potentially caused by the
perturbations of some of the shepherd
moons around
there they seem to be solid as they have
survived crashing into the fing a number
of times kicking out dust and particles
which sometimes then even follow their
orbit as can be seen by the haze around
them the objects themselves are not
actually visible due to the dust
obscuring the
view lastly let's look at the planet
itself as Saturn's Northern Hemisphere
was in full summer at the time Cassini
flew by its remarkable hexagon around
the pole was in full view in the center
of the hexagon is found a permanent
polar vortex with the eyewall of a
massive
hurricane interestingly the pole seems
to be changing color with the season as
you can see quite clearly in comparison
to 2012 where the pole appeared quite
dark in color with the assistance of
other wavelengths of light other storms
are visible and could be seen dotted all
over the planet as well as bands
reminiscent of Jupiter just not quite so
vivid in natural
light also because of the proximity of
Cassini to the planet it was able to get
a good look at the planet's Horizon on
the left of the image can be seen a haze
in the stratosphere of the atmosphere
that disappears towards the right of the
image when Cassini did enter the
atmosphere on its Final Approach it was
thought it would not survive to even
reach this
Haze however scientists weren't too
worried about that what was of
particular interest to scientists is
what the atmosphere consists of Cassini
would dive into that atmosphere to find
that information and would burn up in
the process making it the last readings
that Cassini would ever
send but one week before it entered the
atmosphere Cassini was still taking
images some of these final images are
fantastic although be aware that Cassini
is not capable of real-time video
capture the videos I'm about to show you
are time lapses the splicing together of
countless individual images into
glorious visualizations of what it would
be like to fly with Cassini on his
ultimate journey into Saturn not all of
these images are of Saturn
itself the first time lapse we will look
at is from the 8th of September 2017
only one week before the end of
cassini's mission one of the main
focuses of Cassini during its mission
was the moon Enceladus one of the Prime
candidates in the solar system to
contain life in a subsurface
ocean Cassini discovered over 100 water
plumes erupting through the moon's crust
from this ocean water which freezes in
the space environment and has now formed
the beautiful e-ring around Saturn this
ring is very tenuous only visible when
back lit by the Sun and is potentially
The Bluest naturally occurring object in
the solar
system here is a great view of
enceladus's effect on the densest part
of the earring you can see the plumes
disturbing and replenishing the
ring cassini's final look at enceladus's
plumes were captured in this remarkable
time lapse taken over a 14-hour
period on the 11th of September Cassini
was near the furthest point of its final
orbit and captured this beautiful Mosaic
in natural
light visible are the thickest of
Saturn's rings D C B A and F with
Saturn's short Shadow being cast over
them Saturn's Norther Northern
Hemisphere was experiencing summer
during this time which means that
Saturn's most famous hexagon storm is
visible in all its Glory you can also
just about notice Saturn's subtle bands
in natural
light what's really interesting about
this image however is that the night
side of Saturn is dimly illuminated this
is due to light reflecting off the Rings
meaning Saturn's kns in the hemisphere
facing the sun don't get that dark below
the glow of the Rings Saturn is pitch
black as Cassini began to approach
Saturn again on the 12th of September he
took images of Saturn's atmosphere near
the planet's Terminator line incredibly
because the sun is so low in the sky
here huge Cloud structures can be seen
casting Shadows that stretch for many
kilometers you may think this is a
closeup of Saturn but actually we are
looking at the scene about 5,500 km
across Saturn's moon Titan could easily
fit in the
shot Cassini was getting closer and
closer to Saturn on the 13th of
September it appeared one last time at
dfes and some of you Keen observers will
notice ripples in front of the Moon as
well as behind this is due to orbital
speeds of the Rings and the moon the
inner ring orbits faster than dness
meaning the ripples overtake the moon
exposing more ring material to the
moon's gravity on the other hand the OU
to ring travels slower than dness
meaning the ripples lag behind the Moon
by the time the ring material reaches
dness on either side again the ripples
have already smoothed
out on the same day Cassini had one last
look around the satin system it captured
a view of Titan a moon it focused on
heavily during its Mission a remarkable
world with a thick nitrogen
atmosphere it also appeared at Saturn's
rings with the uneven F ring just about
visible at the bottom of the image and
as Saturn got bigger it took one last
look at Enceladus over a 40-minute
period before it disappeared from view
behind the limb of
Saturn the final image Cassini ever took
was looking over the region where it
would plunge into the atmosphere it was
night time here and so Saturn is lit up
by light reflected off the
rings on the final day photos were not
on the sci's agenda
as beautiful as they are they use up a
lot of valuable bandwidth and scientists
wanted to get every bit of data real
time before the spacecraft was destroyed
this was a unique opportunity we had
never probed Saturn before
this when Cassini first hit the tenuous
parts of Saturn's atmosphere it was
traveling
123,000
kmph the remnants of cassini's fuel were
deployed by its thrusters to keep
cassini's antenna aimed at Earth at this
point Cassini was 1,900 km above
Saturn's
clouds a minute later these thrusters
were firing at maximum capacity to keep
Cassini from spinning out of control
Cassini was directly sampling Saturn's
atmosphere but this atmosphere was also
heating Cassini
up just 10 seconds later the thrusters
were overcome and Cassini began to
Tumble cutting off communication with
Earth cassini's onboard computers at
this point would have been trying to
figure out what was going wrong
gyroscopes and star trackers would tell
the computer that it is spinning and it
would likely have gone into a safe mode
to divert power in an attempt to write
itself a minute or so later the
spacecraft would have disintegrated all
together and burned up in Saturn's
atmosphere as data started arriving one
and 1 half hours later on Earth this
final part of the mission was deemed to
be a great success Cassini recorded data
from direct analysis of Saturn's
atmosphere its ionosphere dust particles
in the atmosphere and from magnetic
field measurements and perhaps more that
has yet to be uncovered from the data
and that's the amazing thing about the
Cassini Mission it just keeps on giving
science papers and discoveries are still
being made as the data it collects is
analyzed and
[Music]
re-examined what have we discovered from
cassini's data in the years since his
ground breaking Mission you're about to
find out but be aware some of the things
Cassini has learned about Saturn has
only serve to make the planet even
stranger you may think you know Saturn
it's iconic rings are the largest in the
solar system and its hazy yellow surface
is both enigmatic and instantly
recognizable it is the second largest
planet the least dense and the sixth
from the Sun
and yet Saturn is an enigma there is a
vast mystery lurking beneath its
obscuring atmosphere uncovered by the
Cassini probe one that the scientific
Community still does not have consensus
about Saturn behaves in ways that our
conventional models claim is impossible
from its temperature to its
magnetosphere to even the very length of
its
days what is going on with Saturn and
what are our best attempts at explaining
these baffling
phenomena the Cassini probe arrived at
the gas giant on the first of July 2004
it was not the first probe to arrive at
Saturn three others had already done
flybys however it was the most
thorough as we have already mentioned it
spent 13 years circling the planet
collecting reams of data using its
various spectrometers magnetometers and
other equipment the knowledge it gave us
has been a huge benefit but sometimes
only serves to deepen Saturn's
Mysteries take for example that hexagon
storm on Saturn's North Pole the edges
of this 29,000 km wide storm could each
fit the Earth comfortably inside and as
best as we are able to tell does not
shift its longitude remaining fixed at
its location traveling with the rotation
of the planet unlike the rest of
Saturn's swirling clouds pushed Along by
its up to 1,800 kmh
winds the storm is undeniably a strange
one scientists do not yet have a full
explanation for it although there are
some lab experiments that have created
close approximations to hexagons on much
smaller scales but it is not
alone as the mountains of Cassini data
started getting analyzed in the years
since the end of its Mission more
Mysteries have started coming in it
started with a fairly innocuous question
how long is a day on
Saturn although we've watched Saturn in
our sky for thousands of years
scientists did not yet have a definitive
answer after all it wasn't as simple as
looking up at the planet and seeing how
long it took for its Rocky core to
rotate Saturn's thick cloud cover
obscures any landmar marks that might
exist on any hard surface below and
those clouds move at different speeds to
the core due to the powerful
wind the Rings themselves orbit Saturn
at different speeds so they don't settle
this question you can't look at how fast
they orbit and hope it's the same after
all most moons don't do this so rings
are no
different rather cleverly scientists do
have techniques for figuring out the
rotation of a gas giant by looking at
its magnetic field and it was hoped that
this method might be used on Saturn
planets with magnetic fields produce
them via a Dynamo effect as the planet
rotates liquid metal in the core spins
and shifts and this colossal motion of
molecules creates massive currents of
energy which in turn produce magnetic
fields one feature of this is that
thanks to this rotation the pole of this
magnetic field is always off from the
axis of rotation for the planet itself
if the two lined up the magnetic field
wouldn't survive for long so all you
have to do is detect the magnetic fields
around a planet which Cassini could do
and watch as the magnetic pole shifts in
a circle around the true axis of the
planet once the magnetic pole has
completed one rotation you have your
day only Saturn apparently does not play
by the rules and its magnetic pole is
almost perfectly aligned with its axis
of rotation to an order of accuracy of
less than 0.1 de and in spite of dynamo
theory claiming that this should be
impossible Saturn's magnetic field is
Alive and Well its Magnetic Moment is
580 times more powerful than Earth's and
is extremely influential on the Saturn
system as a whole scientists do not know
how this magnetic field occurs as it is
impossible under dynamo theory but no
other method for producing such a field
is proven either a planetary Dynamo is
at play in Saturn's core but some other
effect is occurring in the atmosphere to
warp the magnetic field lines to be
perfectly aligned with the axis of
rotation or we are observing a
completely new method of producing a
magnetic field on
Saturn so it was back to the drawing
board for solving a satin day
fortunately radiation proved to be of
more
help Saturn is an electrically live
system charged ions move between the
layers in its atmosphere even between
its rings and its ionosphere scientists
noticed that Saturn emitted radio waves
as a result of all the magnetic fields
at play and these radio waves Rose and
fell in
intensity in fact it seemed to mirror
what you might expect to see as a result
of the planet rotating higher levels of
radiation would appear every 11 hours or
so as a result scientists concluded with
some certainty that this was Saturn's
day length their initial estimate based
on Voyager data was 10 hours 39 minutes
and 23 seconds it was hoped that Cassini
would be able to improve the accuracy of
this
figure initially Cassini was able to do
so but then it got really weird because
over the course of the 13 years of
cassini's study of Saturn
this number started to shift it drifted
about 1% over the course of a year
sometimes Rising sometimes falling this
almost seemed to imply that the planet
itself was altering the speed of its
rotation sometimes speeding up and
sometimes slowing down to be clear a
planet as massive as Saturn should not
be doing that as such scientists
concluded that this wasn't happening and
some effect must be once again muddying
the waters around Saturn some aspect of
the atmosphere was causing shifts in the
fields making the radiation fluctuate
over time hiding the true rotation of
the planet beneath a cloaking
Shimmer another key consequence of the
planet's magnetic field is the auroras
that shine at Saturn's
poles but while on Earth our auroras are
the result of solar wind interacting
with our atmosphere it is thought that
this does not account for the auroras on
Saturn Cassini detected that at least
some of them occurred regardless of what
the solar wind was doing at the time
meaning that Saturn's auroras are nons
solar
originating something strange must be
going on inside Saturn it was hotter
than it ought to be too it radiates out
into space about twice as much as it
receives from the Sun and while some of
this may just be gravitational
compression of the Planet the rest
needed some other way to account for It
ultimately all of this needed some
unifying explanation and fascinatingly
thanks to cassini's data we discovered
the key to all of it may lie within
Saturn's gaseous
atmosphere Saturn is a gas giant it is
almost entirely made of hydrogen and
helium not all of this is gas as the
great mass of sattin means the deeper
into its atmosphere you go the more
intense the heat and pressure that you
are subjected to it is thought that this
pressure forces gaseous hydrogen to
become liquid
metal some scientists theorize that this
liquid hydrogen or perhaps even hydrogen
compressed so densely that it becomes
Diamond rains down into the depths of
Saturn and the friction this generates
explains some of Saturn's unusual heat
but the the rest comes from the auroras
although these are not fully understood
it is thought that they are the product
of electrically charged particles coming
into Saturn from its rings and moons
whatever their Source these auroras may
be creating enough heat to warm the
upper atmosphere of the
planet temperatures so hot create other
effects where warm fronts meet cold
powerful winds are formed it is
theorized that these winds carry charged
ions around Saturn's upper atmosphere
and these electrically charged winds are
what is skewing the data from Saturn's
radiation causing its variance perhaps
such motion of electrical currents might
also explain why Saturn's magnetic
fields are not where they are supposed
to be this could be caused by a
conductive layer within Saturn's clouds
moving at a different speed to the
others creating fields of their own at
least so goes the explanation
in all this it should be clear that many
of these answers lack final proof
scientists are trolling through the data
given by Cassini hoping for further
insights if these are not forthcoming
then ultimately it will take another
mission to Saturn to find the answers to
these puzzling
questions but what about the length of
Saturn's day thankfully this one mystery
does have an answer and it turned out
the clue lay in the Rings after all
rather than investigate the electrical
and magnetic effect of Saturn on its
rings scientists realized that Saturn
would also Target them through its
gravity this is fairly obvious but what
was more insightful was that Saturn
would not Target them uniformly Saturn
is not a perfectly round ball any
variance in its shape result in variance
in its gravitational field Saturn's
rings were a perfect canvas to look out
for such variants as Saturn pulled at
its rings with a rising and falling
Force at certain locations in the Rings
it would be able to detect
ripples scientists started looking for
these Ripples and located them by
measuring the distance between them it
was finally possible to calculate the
length of Saturn's day they weren't far
off it was 10 hours 33 minutes and 38
seconds and this this time scientists
are fairly certain that they've got it
right so at least this mystery was
solved and yet Saturn's other Mysteries
still persist the next mission to Saturn
will launch in 2027 with NASA's
dragonfly although this will focus more
on exploring Titan Saturn's largest moon
Titan is the most earthlike object in
the solar system as it is the only place
thought to have atmosphere filled with
nitrogen similar to ours albe it with no
oxygen and Rain cycles and liquid legs
on its surface although these are
methane rather than water so it's
understandable why scientists want to
give it a look still it means that it
may be some time before Saturn's deepest
Mysteries find themselves
answered Saturn breathes the winds that
might prove to be the lifeblood of the
system thrum and flow across its
atmosphere its delicate balance of
magnetic fields and gravity coax at its
rings keeping them perfectly aligned
Saturn's rings are thought to be
surprisingly young Saturn may be over 4
billion years old but there is evidence
that the Rings may have only formed in
the last 100 million years and they are
slowly draining back down into Saturn's
atmosphere so in another 100 million
years they may be gone this is sad to me
but I also feel strangely fortunate if
Humanity hadn't arrived when we did we
might have missed this beautiful Cosmic
site it may be unscientific to say that
as a planet has no real choice in
whether it gives us a gift or not but
I'm nonetheless grateful to have been
witness to the enigmatic and wondrous
world that is Saturn and seeing those
enigmas and wonders all the beauty all
the scientific data just would not have
been possible if it had not been for the
incredible Cassini ho
This truly was one of the greatest space
missions of our
time did you think space was
silent well it might be for audio or
compression waves but what if you were
in orbit around Saturn listening for
radio and plasma waves
the Cassini spacecraft which orbited
around Saturn for 15 years had a radio
and plasma wave science instrument on
board that could pick up what you were
hearing now being emitted by Saturn and
its moons
these radio waves have been compressed
for our benefit converting roughly 30
minutes worth of radio waves to a
minute's worth of Audio
Waves this wasn't just done to create a
creepy audio file but it had real
scientific purpose which was to examine
the source of these radio waves in the
case of this audio file the source was
Saturn's Aurora
you see the sun is always blasting out
bits of its mass in the form of
electrically charged particles called
the solar
wind planets with a magnetic field
surrounding them redirect this solar
wind around the planet to its poles
where the charged particles impact the
planet's atmosphere or more specifically
its
ionosphere this impact causes particles
in the atmosphere to become excited or
in other words the Collision ionizes the
particles in the atmosphere causing them
to emit electromagnetic
radiation we can see this ionization
with our own eyes invisible light but
Aurora also emit radio waves which we
need special instruments to detect like
the one that was on
Cassini these radio waves Bounce Around
within the planet's magnetic field which
is where Cassini picked them up how do
we know that this through another audio
file what you listening to here is the
Cassini spacecraft passing through the
bow shock of Saturn's
magnetosphere as I mentioned Saturn has
a large magnetic field surrounding it
called the planet's magnetosphere which
deflects the solar wind around
it for the first section of the audio
Cassini is outside of Saturn's
magnetosphere outside the magnetosphere
radio sources are quiet and there is
calm in the audio then cassini's orbit
takes it through the magnetosphere
boundary called the bow shock which is
the place where the magnetic field and
the solar wind Collide there is a sudden
increase in radio
waves past the bow Shar
Cassini begins to detect a lot more
radio waves bouncing around Saturn's
magnetosphere noticeably different from
the outside of the
[Music]
magnetosphere but Cassini heard a lot
more than just Aurora Cassini also made
some close approaches to Saturn
listening closely to the planet itself
Saturn has a thick and dynamic
atmosphere with massive storms spanning
the Planet one such storm sounded like
this what you are listening to here are
radio waves being generated by lightning
in one of Saturn's storms it may sound
small and almost puny but remember that
this is not the representation of audio
you're hearing these lightning strikes
are so powerful the Cassini could detect
their radio waves in space to give you
some kind of scale scientists estimate
that the lightning in Saturn storms are
roughly 1,000 times more powerful than
typical lightning on
Earth to get this close to Saturn
Cassini had to pass through its rings
during flybys like this Cassini listened
what do you think could be the cause of
this
audio I
cini was traveling extremely fast around
Saturn as fast as
121,000 km
hour as it orbited through the Janus
Epimetheus ring a very faint and Dusty
ring it would impact tiny particles
which would vaporize into clouds of
plasma these tiny charged explosions
could then be picked up by cassini's
radio and plasma wave science instrument
and these impacts were then converted
into the audio you are now
hearing the increased frequency of these
impacts showed the densest part of the
ring and as the impact subsided it
indicated that Cassini was moving away
from The Ring
again Cassini tried this again later in
the mission except this time through a
gap between satin and the d-ring
[Music]
a you'll notice this time that there
wasn't a noticeable increase in
collisions at first scientists thought
that this was because the gaps between
the Rings were just really Barren of
particles however a second orbit through
the Gap revealed bu something
different this time and every orbit
after that there was a noticeable
increase in particle collisions so what
happened the first
time well as it turns out there were
particle collisions but none of the
particles in that part of the Gap were
big enough for the rpws instrument to
detect Cassini had another useful
instrument on board however called The
Cosmic dust analyzer which could detect
particles up to only 1 millionth of a
millimeter in size and this instrument
did detect an increase in particle
collisions during the flyth
[Laughter]
through after passing the ring during
the second fly through you'll also
notice these Rising tones
[Applause]
scientists are unsure what causes these
exactly but it is reminiscent of what
Cassini detected earlier in the
[Music]
mission the other most interesting
source of radio and plasma waves around
Saturn is actually its moon
Enceladus 2 weeks before Cassini
plummeted into Saturn's atmosphere it
captured this as it passed by Enceladus
[Music]
these observations show that Enceladus
and sattin have a plasma circuit between
the
two much like IO and Jupiter just
perhaps to a lesser
extent although the strength of this
plasma circuit surprised scientists
greatly Cassini was also equipped with a
magnetometer this is what it detected by
Enceladus
during the flyby of Enceladus it was
able to detect a bending of the magnetic
field indicative of a thin
atmosphere the source of which is likely
to be the Jets and cryo volcanism near
the South Pole of the Tiny
Moon this geological activ ity draws
parallels again to Jupiter's moon IO the
magnetic fields of both planets interact
strongly with the ejected atmosphere of
the moons creating a flux tube or a
current of charged plasma
particles there's just one more place
that I want to have a look at around the
Saturn system and that is
Titan cassini's first major objective
upon reaching the Saturn system was to
launch the hyan probe towards Saturn's
biggest and perhaps most interesting
moon
Titan although hyans didn't have its own
rpws instrument it did have some other
instruments see if you can guess what
this is a recording of as it descended
towards Titan's surface
[Music]
ch
[Music]
if you guessed radar Echoes well done
hyans use this to determine its altitude
above the
surface and what about
this this is perhaps the most impressive
of any of the clips I've shown so far
why it doesn't sound that impressive
Until you realize that this is actual
audio taken by a microphone on the Hy's
probe as it descended through Titan's
atmosphere this is it leaving the vacuum
of space and diving into another world
what you are hearing is exactly what you
would have heard if you had been sitting
on hyans as it
descended this gives the clip such an
awe and perspective like nothing I've
heard
before somehow it's quite incredible for
me to think about we often have visuals
of other planets but I'm not really sure
if there's anything quite like this out
there and there we have it the sounds of
Saturn and a couple of its
moons today I'm super
excited
why because I get to show you the
amazing planet that is
Saturn as far as the planets go this is
probably my favorite planet outside of
Earth and I think by the end of this
video you may agree with me because
thanks to the Cassini probe we have some
astonishing imagery of this beautiful
planet I'm Alex molan and you're
watching astram and in this video I will
not only give you insights into some of
the spectacular Cassini images but I
will also give you an overview of almost
everything you could want to know about
the sixth planet from the
sun Saturn is Big it's a gas giant with
an average radius about nine times that
of Earth making it the second biggest
planet in our solar system I say average
radius because its equatorial and polar
radi differ by almost 10% it's 60,000 km
at the equator compared to 54,000 km
from pole to pole with an average
density of around 0.7 G per cm cubed it
is only 1/8 the average density of Earth
however because its volume is so large
Saturn's mass is over 95 five Earths
this low density makes Saturn the
lightest Planet per cubic cm by far and
it's the only planet of the solar system
that is less dense than water about 30%
less so if you had a bath toy of Saturn
that shares the same density as the
planet it would
float this is because Saturn is 96%
hydrogen which is the lightest of the
elements however average density doesn't
tell the full picture of what a planet
is like Saturn is classified as a gas
giant because what we see of the planet
is simply gas it doesn't have a rocky
surface under the cloud
layer however Saturn is most certainly
not gous all the way through it's got
too much mass for that you see the
further into Saturn you go the higher
the pressure
builds eventually the pressure becomes
so great that the hydrogen stops
behaving like a gas and starts acting
like a liquid so in a way under Saturn's
atmosphere is a liquid hydrogen ocean
even further below that it may be that
there is a metallic hydrogen layer where
the pressure is so great that hydrogen
starts acting like a metal and beneath
that could be a metallic and Rocky core
we do know that Saturn has a very hot
interior reaching
11,700 de C at the core this is twice as
hot as as the surface of the Sun if we
look at Saturn through the infrared we
can see Saturn's glow represented in
brilliant shades of electric blue
sapphire and mint green on the night
side where there is no sunlight Saturn's
own thermal radiation lights things up
this light is generated deep within
Saturn and it works its way upward
eventually escaping into space in fact
this infrared image reveals that Saturn
radiates 2.5 times more energy into
space than it receives from the Sun you
may not have noticed but Saturn's
atmosphere has a banded pattern similar
to
Jupiter's if you increase the contrast
when you look at images of Saturn this
becomes more apparent Saturn's bands are
much less chaotic than Jupiter's however
and are much wider near the
equator and ever wondered why Saturn is
yellow it's believed to be due to
ammonia crystals in the upper atmosphere
but while the atmosphere of Saturn may
appear calm the planet is actually
extremely active the winds on Saturn are
the second fastest among the solar
systems planets after Neptune they can
be a blistering 1,800 km per
hour visible storms are also known to
appear on Saturn like this one that
lasted just under a year in
2011 it had been the pattern that every
30 or so earth years the planet it
produces what is called a Great White
Spot which is a unique but short-lived
phenomenon believed to occur once every
saturnian year however we have spotted a
few of them over the last 30 years if it
does follow a 30-year pattern though we
can expect another one anytime
now sadly even if it does happen we will
only be able to see it through the
Hubble Space Telescope as the Cassini
Mission ended a few years
back Saturn has plenty of smaller storms
too where lightning is often produced
Cassini has even detected the sound of
[Music]
thunder while this might sound weak the
sound you are hearing is actually the
radio waves produced by the lightning
converted to
audio in reality lightning on Saturn is
about 1,000 times more powerful than
what we see on
[Music]
Earth still talking about storms but
moving on to the planet's poles we find
that each pole has giant permanent
storms NASA reported in November 2006
that Cassini had observed a
hurricane-like storm locked to the South
Pole that had a clearly defined eyewall
eyewall clouds had not previously been
seen on any Planet other than Earth the
ring is similar to the eyewall of a
hurricane but much larger the clear air
in the center is warm like the eye of a
hurricane but on Saturn it is locked to
the pole whereas a hurricane on Earth
drifts
around the North Pole is even more
unusual there is a persistent hexagon
shaped storm that rotates with the
planet not with the
atmosphere the straight sides of the
Polar hexagon are each about 13,800 km
long making them larger than the
diameter of the
earth why does this happen and to such a
large scale well we don't really know
however the speed differential and the
viscosity parameters between atmospheric
bands here are likely to be within
certain margins to allow such an unusual
polygon to form lab tests have since
been done where polygons could form in a
circular tank of liquid rotated at
different speeds at its Center and near
the outer boundary so this is the
leading theory at the
moment interesting
towards the center of this hexagon
another eye wall can be
found while not anywhere near as strong
as Jupiter's Saturn does have a
magnetosphere potentially generated in
the metallic hydrogen layer of the
planet it is large extending far beyond
the planet and it is strong enough to
deflect solar wind from the
Sun and much like other planets with
magnetospheres Saturn has auroras their
location and brightness strongly depend
on the solar wind pressure the auroras
become brighter and move closer to the
poles when the solar wind pressure
increases the same process produces
auroras on both Earth and Saturn where
electrons from the solar wind stream
along the magnetic field lines directed
into the upper atmosphere there they
collide with atoms and molecules
exciting them to higher energies the
atoms and molecules release this added
energy by radiating light at different
colors and wavelengths on Earth this
light is mostly from oxygen atoms and
nitrogen molecules on satin it is from
hydrogen the Rings for me are one of the
highlights of the planet Saturn has a
prominent ring system that consists of
10 continuous main Rings while they are
mainly named after letters of the
alphabet the naming conventions are a
little confusing so bear with me
the first five rings from the closest to
the planet outward are the d-ring which
is very faint the c
ring B ring which is the brightest and
widest of all the
Rings a-ring which is the last of the
large bright rings and then the F
ring the Rings extend from 66,000 km to
140,000 km above Saturn's Center and are
made up mostly of water ice with small
amounts of dust and rocks if we look in
the ultraviolet at a section of the
brightest Rings it shows there is more
ice towards the outer part of the Rings
than in the inner part the red in the
image indicates sparer ringlets likely
made of dirty and possibly smaller
particles than in the icier turquoise
ringlets if we look at a picture
representing radio alation we can judge
the size of the individual particles
that make up the Rings color is used to
represent information about Ring
particle sizes based on the measured
effects of three radio signals shades of
red show regions where particles are
larger than 5 cm in diameter green shows
particles smaller than 5 cm and blues
show particles less than 1 cm in size
overall it's thought that particles in
the Rings aren't bigger than 10 m and
most are mic roscopic in size the main
rings are thought to be as little as 10
m thick to 1 km
thick we can see that the Rings are not
perfectly symmetrical during the
planet's Equinox the Rings can get a bit
wonky look at the top of this video
where the B ring meets the A-
ring zooming in on the structure reveals
ridges and spokes a couple of kilometers
tall their presence given away by their
Shadows zooming out again we can see the
scale of how many spokes there are
during this
period oscillations happen all the time
in the Rings though perhaps due to the
presence of a Shepherd moon or even just
naturally the differences which can be
seen all in only a day can be up to 200
km so I've talked about the d c b and a
rings and also mentioned the FR ring the
F ring can also get quite wonky and has
a perfect example of what is called a
Shepherd moon it's called Prometheus and
it leaves a beautiful Ripple in the eing
as it orbits once during its 14.7 hour
orbit of Saturn Prometheus which is only
102 km across reaches the point in its
elliptical path where it is farthest
away from Saturn and closest to the fing
at this point prometheus's gravity is
just strong enough to draw a streamer of
material material out of the core region
of the eing and that's what causes these
ripples so what comes after the F ring
well this is where it gets
confusing first you have the Janis or
Epimetheus ring the G ring peni ring and
then the
e-ring I find this picture amazing as
these rings are much more visible being
backlit by the sun this bright blue ring
is the earring and you can just just
about see the faint peni ring at the top
of this picture the g- ring is the next
distinct ring and again you can just
about see the Janice or Epimetheus ring
at the top below it and can you see
us we are all in this picture
too here is Earth and the
moon the very last ring is the newly
discovered Phoebe ring a huge yet
disperse ring that extends far beyond
Saturn it's so large that if it were
visible from Earth its apparent diameter
would be the size of two full moons
across it probably originated from
Saturn's 200 km wide Moon Phoebe which
had been battered in its past Phoebe
orbits just outside of the ring and
probably keeps this dust contained from
going outward on the other hand it is
also suspected that dust in this ring is
falling inward eventually falling into
iapetus Saturn's outermost regular
Moon it has a bizarre combination of
colors because dust from the fee ring
settles on it but because iapetus is
tidily locked only one side of the moon
ever faces Saturn with the back side of
it exposed to the Phoebe ring meaning
its two faces look very
different so now you know about the
Rings I think you all agree that they
are so interesting in their own right
theories abound as to why they are are
there but we simply don't know we know
that some of the moons are responsible
for some of the material there and we
also know that some of the material
there is responsible for some of the
moons and talking of moons Saturn has at
least 802 of them they come in all
shapes and sizes and most uniquely
Saturn's largest moon Titan which is
even bigger than Mercury is the only
moon in the solar system with a thick
atmosphere around it
which I have done a separate video about
here I'm also going to throw in here
that Saturn has the Death Star orbiting
it biding its time we call it
mimus generally though most of Saturn's
moons are very small only a few
kilometers
across lastly I'm going to talk about
Saturn's orbit Saturn orbits about 9 to
10 times further away from the Sun than
Earth does and one year on Saturn takes
30 Earth years funnily enough a day on
Saturn is different depending on where
you were situated at the equator or at
the poles a day lasts about 10 hours and
14 minutes everywhere else on Saturn a
day lasts 10 hours and 38 minutes the
issue is because Saturn isn't solid it's
not bound to rotate at the same speed
all
over I just want to leave you with this
few sights in the solar system are more
strikingly beautiful and softly hued
Saturn embraced by the shadow of its
rings the gas planet's subtle northward
gradation from gold to Aur is a striking
visual effect that scientists don't
fully understand current thinking says
that it may be related to seasonal
influences tied to the cold temperatures
in the winter Hemisphere and despite all
that we have learned from Cassini Saturn
remains a world of
mystery thanks for watching
this video was in part made possible by
all the astronauts on patreon if you
think these videos add some educational
value to the world and want to give them
more stability than the algorithm you
can become a paid member on patreon to
contribute towards their creation when
you join you'll be able to watch the
whole video ad free see your name in the
credits and submit questions to our team
just sign up with the link in the
description once again a huge thank you
from myself and the whole astrom
team meanwhile click the link to this
playlist for more astrom content I'll
see you next time