Cassini's Legacy: Saturn's Mysteries and Rings from NASA Mission Data

[00:00:00][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