The Supermassive Podcast - 40: Becky Loves Saturn

Episode Date: April 29, 2023

It's FINALLY happening. Izzie is letting Dr Becky have an entire episode about her favourite planet, Saturn.  Professor Geraint Jones from UCL's Mullard Space Science Laboratory tells the Supermassive Team about the Saturnian system. Plus, Professor John Zarnecki shares his experiences of being involved with the Cassini-Huygens mission. And, as always, Dr Robert Massey is on hand to take on listener questions and share his stargazing tips for the month.  The Supermassive Podcast is a Boffin Media production for The Royal Astronomical Society by Izzie Clarke and Richard Hollingham. 

One of its moons, Mimas, looks like the Death Star from Star Wars. When we landed on the surface, that moment for me was so overwhelming. The first time I looked through my telescope and I saw Saturn, it's brilliant. Hello, welcome to the Supermassive podcast from the Royal Astronomical Society, with me, science journalist Izzy Clark and astrophysicist Dr. Becky Smethurst. It's happening, Izzy. It's finally happening. Everybody stay calm. What's the procedure? I knew this was going to happen. If you can't tell everyone, I'm very excited because this month we are talking about my favorite planet the one the only sun so for any new listeners

welcome but there is some context here becky if you haven't noticed already is obsessed with saturn and we've never made an episode about it never i wasn't it wasn't it's not there's nothing personal becky but we're, three years down the line. And I know, Robert, you normally give a quick intro into the topic. Do you mind if we hand that over to Becky just for this episode? You know, it would be like ruining Christmas if I said no. She has to do this. Okay, so Becky, starters for 10. Why do you love Saturn so much? I've been prepping for this moment for three years. here we go as we how do i love thee let me count the reasons why who would have known an office reference and a shakespeare reference like within two minutes

you know we're cultured here anyway so this is the obvious reason for saturn right it is clearly beautiful everybody falls for it when they look at it through a telescope for the first time and see those rings, and I am the same. It's got the rings far more spectacular than Uranus's rings. It can sit down. It looks far more spectacular than Jupiter, in my opinion, as well. It's got far more interesting storms in the Great Red Spot, like the hexagonal storm raging away at its North Pole, but for some reason, not at its South Pole. So there's a mystery there as well. It held the crown of having the most moons for a while, although as we heard last month's episode, Jupiter has just pipped it to the post there. It also,

in the very early days of the solar system, held Jupiter back from migrating inwards. Saturn's pull on Jupiter stopped it moving inwards, which meant that it never interacted with the inner planets of the solar system, meaning the Earth didn't just get ejected, yeeted out of the solar system. We're all here because of Saturn, you could say, if you wanted to. For a long time, we didn't know how long the day was on Saturn.

Like we didn't know how long it took for it to rotate because its gas and its magnetic field all rotates differently. So that was a bit of a mystery. And also its moons are some of the most likely places in the solar system that we could find life outside of Earth. So things like Enceladus and Titan. One of its moons, Mimas, looks like the Death Star from Star Wars. Hyperion, honest to God, looks like a sponge that you plucked straight out of the sea.

Like I could go on, Izzy, but I feel like you're all getting slightly bored now. I'm literally like, that's so many facts off the top of your head. Like, damn, she loves this planet. I do. I really do. Okay, Robert, while we're here, do you have any particular thoughts on Saturn? I do, but I can't really top that can i um no it it's it i think becky's read that it's the picture book planet so obviously it's the one you know it the iconic ring around the planet is in every cartoon in every children's book everywhere and on every you know so many logos

and so on so and it does blow you away if you look at it for the first time through a small telescope you think wow the rings what i also recommend if you ever get the chance to go to something like i don't know the stargazing evenings in a place like greenwich have a look at it through a larger telescope as well and that is mind-blowing because you see the there's absolutely exquisite you know the sort of inner dusky rings the kind of the shading of the top of the planet and so on. It's a total visual feast. So I don't think anybody I've ever shown the rings to hasn't been blown away, even with a tiny telescope. If you get a chance at all, go and look at it through a slightly bigger one. It's true. I mean, I think it was last summer, my boyfriend and I went camping and I took the telescope with us.

And I was like, have a look at this. You'll see Saturn. And he literally swore he was so surprised he was we were in the middle of this field i was just like that's like oh sorry everyone but he was so surprised just because i think it's the stereotypical planet isn't it if you see cartoons as you say it's just like and it's just so stunning um It's a breathtaking moment. And do you know what? It's the only planet, except for Earth, it's the only planet with an emoji. Very important. Key.

To me, yes. Want to guess what's in my most recently used emoji? It's just only Saturn. That's it. Okay, so there's no doubt that Saturn is pretty cool and Becky I'll give you that but what's it like on this gas giant and how much do we know about Saturn as a system to answer that I spoke to Professor Geraint Jones from UCL's Mullard Space Science Laboratory who was involved in the Cassini-Huygens mission, the most recent spacecraft to visit the planet.

Saturn is very different to the Earth. It's huge. It's still about nine and a half times wider than the Earth is, so absolutely enormous. So when we look at features in the clouds and things of Saturn, they're comparable, many of them, to the size of the Earth itself. But it's a gas giant. So like Jupiter, Uranus and Neptune, you could parachute down into the atmosphere and go down and down and down and you would be crushed by the increasing pressure of the atmosphere before you'd hit any solid surface. So it's mostly gas, very far down. And then there is some core to it, but it's not a place where we could ever send anything to roam around on the surface. It's too deep in. where we could ever send anything to roam around on the surface. It's too deep in. Okay, okay. So won't be sending humans there anytime soon, I would say. What about its rings?

I think one of my favourite moments of just generally stargazing, planet gazing, whatever you want to call it, was the first time I looked through my telescope and I saw Saturn and its rings. And it's so distinctive. It's brilliant. And I would recommend anyone who has a telescope to go and have a look and its rings. And it's so distinctive. It's brilliant. And I would recommend anyone who has a telescope to go and have a look and do that. Absolutely. Yeah.

And I remember the first time I saw the rings as well. It's really weird. They sort of pop out and that looks like a UFO or something. Yeah, they're enormous. All four of the giant planets have got ring systems, but Saturn has got the most spectacular one by far. They're wide enough to cover the distance roughly from the Earth to the moon. They're enormous. But actually, they're pretty thin, despite being extremely wide.

They're made of billions upon billions of icy rocks, rubble, dust. All of those little rocks are in orbit around Saturn over the equator, and they're actually quite thin. So they're probably only a few tens of meters high, not much bigger than someone's house in height. But because of the seasons of Saturn, occasionally we have an interesting way of looking at them when the sun is exactly side on. So equinox, when the sun crosses the equator, I mean the Cassini-Huygens mission, which was our last project to explore Saturn.

The Cassini spacecraft was able to look down at the rings and saw that at the edges of the rings, there are big waves and cliffs, in a way, made up of all these rubble pieces at the edges of the rings. So they were casting shadows of the rest of the rings. So you could see it was actually not perfectly flat. There are waves and other features. Oh, wow. Okay.

And you mentioned something there that I'd like to pick up on. You mentioned seasons. So what are seasons like on Saturn and what are the conditions of the planet? Okay. We've got summer, autumn, winter, etc. on Saturn. The poles of Saturn are tilted with respect to the sun. But because Saturn takes over 29 years to go once around the sun,

so that's Earth years, things change much more gradually. So we go through different phases lasting a few Earth years where you have one hemisphere where it's summer, so more sunlight. And then the other hemisphere will be having less sunlight. And on top of that, because Saturn's rings are so thick, they block a lot of the light from falling onto the winter hemisphere as well. So obviously then it's colder in the winter, both on the night side and the day side as well. And we can actually see the effect of both on the night side and the day side as well. And we can actually see the effect of that on the clouds of Saturn as well. We see different colours, so suggesting

there's different chemistry going on because there's less ultraviolet light coming from the sun, causing the clouds to change colour and things. But Saturn, because it's about 10 times further away from the sun than the Earth is, it's lot colder so we're talking about temperatures of roughly minus 200 degrees celsius on saturn itself and and on the moons but even at the height of summer it's obviously far far colder than it is here yeah oh my gosh yeah and we talk about jupiter being like this monster and you, all of these storms and everything is incredibly extreme. Is it similar on Saturn? Do we see those storms that are, you know, quite energetic? Is it the same thing going on on Saturn? Similar, yeah, but it's more subdued.

So like Jupiter, there are bands of clouds on Saturn. We have these lines across parallel to the equator, but they're much more tricky to observe because it looks like there's a haze covering most of the atmosphere, so they don't really stand out as much. But every few decades, a big storm arises on Saturn. So there was a quite famous British film star at the time, Will Hay, discovered this bright spot on Saturn, which turned out to be a massive storm in 1933. Then there was another one in the 1990s, which the Hubble Space Telescope observed.

And then during the Cassini mission as well, amateurs discovered another storm, the spectacular storm that arose in Saturn's atmosphere and actually spread the clouds around the planet. And it was a bit like a snake eating its own tail eventually. Oh wow. Now I understand that when we talk about the orbit of Saturn and a rotation or how long a day is, there is a bit of a mystery around that. Can you explain that for me? Yeah, so it sounds really bizarre but when the first flybys by spacecraft of Saturn took place, they thought that they'd nailed what the rotation rates of the length of the day on Saturn was. So you get slightly different answers, which I'll get to in a moment.

So it's roughly 10.7 hours. Ish. Ish, yes. So the rotation rate was measured because there were radio pulses coming from the planet and it was assumed there was one of these every rotation, which made sense, and it was pretty stable. And that's what appeared in all the textbooks and things. This is the rotation period of Saturn out on the day.

And then Cassini arrived and found that the length of the day was a bit different. And then as the Cassini mission carried on, they found that these radio pulses had different periods in the north and south of the planet. So it's as if it had two rotation periods, which weren't in step. And those periods were changing as well. So there was a lot of debate about what's going on, how long is a day on Saturn? And I think ultimately we could say we're not 100% sure, but there are other ways of measuring it as well. But it's really bizarre. You'd think that a fundamental thing like how long is a day on the planet is a really easy thing to measure.

But because all the clouds are moving around, there's no solid surface that we can measure. It's actually quite tricky to do. Oh, that makes so much sense. Okay. And obviously, we can't talk about Saturn without mentioning its moons. So how many moons does Saturn have?

And what are they like? Yeah, it depends where you draw the line of what a moon is. Because if we count all the boulders and the rings, there are billions of them. Well, yeah. So a sensible answer is, yeah, just over 80. And most of these are fairly small, a few tens of kilometres across, but it has some bigger moons as well.

So a few hundred kilometres across, there are several of those. So one of them, Mimas, orbits quite close in to Saturn. That's got an enormous crater on it, which was almost big enough to break it up. And it looks like the Death Star. So it's very strange. Yeah. So that crater is named Herschel after the astronomer who discovered it. Most of them have got water ice as their crusts. So what we're looking at is water ice mostly on the surface. So there's another fascinating moon called Enceladus, and it's about 500 kilometres across. But it's very reflective. So it's the most reflective body we know of in the solar system. And there were some odd measurements by the magnetometer on Cassini, which suggested that it had an atmosphere, which is really weird for a body that's this small. And the camera took images

of the moon as well. And it turned out there were jets of material coming out of the South Pole. So we now know that Enceladus is a moon which has got active ice volcanoes or geysers squirting out icy water, water ice grains into space, that there's a liquid water ocean under the surface. So it's one of these few places in our solar system when maybe we've got the conditions for life. Whether it's arisen or not, it's a big question we won't know for a very long time. Amazing. And I mean, we've mentioned this a little bit, and we're going to be talking about one particular mission in more depth later on in this episode. But how do we know all of this information on Saturn and its moons? How have we been able to look at

this planet? Yeah, so great question. So first of all, Galileo turned his telescope towards Saturn, and he saw blobs. He couldn't figure out what he was seeing. It was a few decades later when Huygens, another astronomer, realised that it was a ring around the planet itself. And then in the past couple of decades, obviously, telescopes got better. So we were able to get clearer and clearer images. Most of what we know about Saturn and its moons come from space missions. Pioneer 11 was the first spacecraft to go past in the late 1970s. And then that was followed by the two Voyager

spacecraft, Voyager 1 and Voyager 2, that revealed how spectacular the rings were and the moons as well. And Voyager 1 actually was specifically directed to Titan because we knew that Titan was this fascinating place with its own thick atmosphere as well. But if you have an orbiting spacecraft, you can learn much, much more. So that's how the Cassini-Huygens arose. So NASA led, but with big contributions from the European Space Agency and Italian Space Agency. And that was an orbiter launched in 1997, arriving in 2004. And the biggest European contribution was the Huygens probe that was targeted to land on Titan. Thank you to Professor Geraint Jones. So aside from the storm that happens every few decades, and Becky, you you mentioned this the next storm that i want to

talk about it's this strange hexagonal storm at saturn's north pole so how much do we know about it i know you said it was a mystery but like let's go into that a bit more what is going on yeah so i mean we know a lot of the properties of this storm so just to give you some context so it is a perfect hexagon and its sides are 14 500 kilometers long each blimey that's 2 000 kilometers wider than the earth's diameter yeah so just this this thing is way bigger than the earth this is why i'm like jupiter's great red spot gets blown out of the water because that's, you know, just a little bit bigger than the Earth. This thing, you could fit at least six Earths on the edges and then still have room.

Yeah, yeah, fair enough. Oh, no, this episode's going to convert me, isn't it? See, see. The gas is moving at something like 320 kilometers an hour in the atmosphere of Saturn up there as well. It really is like a storm and there is like a vortex at the center that you see as well and it was first spotted by voyager one in when it's fly by was about 1981 or so and then the cassini mission which was obviously around uh saturn for a very long time as we just heard that actually saw it

changing color from blue to gold and that's because it's on the North Pole and eventually sort of, you know, the North Pole was in darkness during Saturn's winter and then it came back round in the summer. And we think that's due to the fact that, you know, the sunlight hit it and it changed sort of like how much haze was in the atmosphere. And that's what caused the change in colour. But in terms of like why it's the shape that it is, like a hexagon, right? It's weird. why it's the shape that it is, like a hexagon, right? It's weird. It's so weird because, like, naturally it's not a shape that you see in nature.

Yeah, like, let's go round. Right, hurricanes, round. Planets, round. Right. Ish. Ish. Saturn's probably the least round of all the planets. It's very squashed. But, yeah, it's um you know everything's generally

round ish right eventually it was actually a research study that was done in a lab at Oxford University as well that figured this out with essentially just giant big fluid tanks colors to actually sort of simulate what was happening and they figured out you could actually make not just a hexagon but other sort of like even octagons and various other different sort of sharp sided shapes. Say that one three times faster. Other sharp sided shapes by having differently moving gas. So essentially the center of your storm at the very pole is moving a lot faster than gas that is much lower down so at lower latitudes and what happens is if you have an extreme difference in the speeds of those gas

so a very sort of steep gradient from one to the two with a latitude you essentially get this boundary being set up between the two and this can cause essentially a standing wave to get set up so you know when you you know take a skipping rope and you can you know sort of shake it at the exact right sort of speed frequency and you get that sort of perfect you know jump rope right shape where you just get one or sometimes if you take it even faster you can get the two where the middle of the skipping rope just isn't moving at all yeah slinkies and all sorts right yeah basically that's what's happening and it's setting up this standing wave that actually has these sharp corners giving you this hexagonal shape and so

basically what we think and again like this has only really been done once in this lab we think is that the south pole doesn't have those exact right conditions to give you this standing wave because it's very temperamental whether you actually get one or not and what shape you get as well so there's also another strange phenomenon on saturn's rings and they're these sort of dark markings blobs however you want to call them they're called spokes so what are they do we know um i don't know. Robert, do you know? I think the answer is we don't properly know. There's an idea that there's somehow there's some kind of electromagnetic effect holding dust in place, but they're seasonal as well. They're not always there and they were discovered properly.

Well, actually, the first part, there was someone who saw them, a really talented visual observer called Stephen O'Meara, saw them in 1977, noted the observation. No one took it very seriously. And then four years later, first, I think it was Voyager 1 got there first to Saturn. And it found them as well. So the weird thing is they go round with the rings. But that doesn't really make sense because the rings, because they're not solid, they're made of lots of particles going at different speed, they go more quickly closer to the planet than further out. So something like a spoke should not really exist or they didn't think it would exist to begin with.

So that all these stories at the time shows what I am again. You know, I remember the stories about this defies the laws of physics. And of course it doesn't. It's just something we can't explain entirely yet. But yeah, the best explanation appears to be there's some weird electromagnetic effect holding these dusty spokes in place but they're not always there if anybody out there is such a talented observer they can actually see them with a telescope i guess we'd like to hear that too and maybe they should tag us on social media and show us an image absolutely and actually if you go on youtube you can see videos of these spokes in the rings they're just kind of strange but they do look like spokes on a on a bike wheel okay so becky what about the future are there any future plans to study saturn

and its moons yeah i mean i'm really excited for the nasa's dragonfly mission so this is essentially like you know like a little helicopter drone thing little drone just face drone hopping around you know in the atmosphere and surface of Titan, investigating it, seeing if it is hospitable to life, if there's life exists there at the moment as well. And the sort of drone nature allows it to explore much easier than a traditional rover would that's very stuck to the surface. So that'll be a whole new way of exploring this planet.

And it's why the Ingenuity drone that's on the surface of Mars right now with the Mars rover, Perseverance, like it's why its flights have been so important. Obviously we proved that it was possible to do this, but also it's proved that, you know, in a future mission, we could actually do this as well. And so all the flights has been done.

I haven't just tested, you know, how far could we push Ingenuity, but it's also like, how will that then inform the design of Dragonfly as well? i don't think that's set to launch until about 2027 and then not get there until 2034 so again with like all of these solar system exploration missions we have to be a little bit patient sadly there's no funded projects to explore the likes of enceladus so this moon of saturn which we think has this sort of ocean underneath a very icy crust and has been giving off these plumes of sort of water vapor from its south pole that Cassini

flew through as well. Again, a very big candidate for life outside of Earth. Obviously, Cassini studied Saturn and its moons in quite great detail, and we had it there for a very long time. Started in 2004 and ended in 2017. So, you know, over a decade of exploration. So when new missions are proposed right now, it's kind of like, well, you just had one. And there's probably a bit more of a push to explore the likes of Uranus and Neptune, which have only ever been visited by the likes of Voyager

and they were flybys. So they were very, very quick. So we'd like to explore those more and I think Saturn unfortunately unless it's a designated mission to Enceladus or like Dragonfly to Titan I think we're gonna have to wait a while for the next Saturn orbiter sadly and maybe who knows in the next three years we'll cover Uranus and Neptune and get to them at some point yeah as we've just been saying much of what we know about saturn and its moons comes from the international cassini huyghens mission so this joint nasa european space agency and italian space agency mission launched from cape canaveral in 1997 it arrived at saturn in

2004 after a very successful research mission, we said our goodbyes as it finally entered Saturn's atmosphere in 2017. It was a mission of firsts. The first to orbit Saturn, the first landing in the outer solar system, and the first to sample an extraterrestrial ocean. But how did it do all of that? I spoke with Professor John Czarnecki, who was the principal investigator for the surface science package on board the Huygens probe. Well, I suppose the aims were very simple in one sense. It was to study the Saturnian system and especially the largest moon of Saturn, Titan. Cassini-Huygens, you can divide it into two quite easily. Cassini, which was the

main, larger spacecraft, and that was provided by NASA. And then Huygens, the European probe, which looks a bit like a flying saucer, really, and that was bolted on the side, and that was the European contribution. So Cassini carried 12 instruments with the sort of, can I say, the usual array, so cameras, spectrometers, instruments to measure magnetic field, to look at particles, to look at the dust.

So really to characterize the environment physically and chemically. And Huygens, which was going to, the plan was for it to detach from Cassini once it arrived at the Saturnian system. And the aim then was to parachute down through Titan's atmosphere and land on the surface. So there were six instruments that were designed really primarily for making measurements in the atmosphere during descent. And my instrument was the only one that was optimized

for making measurements on the surface. And why was Titan so interesting? What was going on there? What did you want to find? One of the reasons that Titan is so interesting is that we knew before we went that it's the only planetary satellite in the solar system with its own atmosphere.

You know, most are like our moon, completely devoid of an atmosphere. But Titan has an atmosphere and a thick atmosphere. So it's thicker than Earth's atmosphere. So, you know, what's going on here? And so we were able to, or the aim was to parachute down. We had no direct idea of what the surface would be like. And that is why we had no idea whether we would survive the

touchdown because we didn't know what we'd be landing on. And so that's why it was optimized for making measurements in the atmosphere. Anything else would be a bonus. Yeah. So let's talk about the studying of Titan a bit more. What were some of the things that were discovered thanks to the Huygens probe? Well, let me say that what we knew about Titan, mostly, not exclusively, but mostly came from the Voyager flybys in the very early 1980s. The trouble is Titan is completely covered with an orange smog or haze. So we had no direct evidence of what was going on at the surface.

But from all of this, there was some indirect evidence that there might actually be liquid on the surface of Titan. In fact, there were some theories that suggested it was covered with a global ocean, that suggested it was covered with a global ocean, not of water, because we did know that the temperature at the surface was minus 170 degrees centigrade. So it would be liquid hydrocarbons, probably methane and ethane. Those were some of the reasons that Titan was selected for special study. To cut a long story short, what did we find? And this is between

Huygens and Cassini. We found that it is, in some senses, it has some similarities to Earth. It has a nitrogen-dominated atmosphere. It has weather. It rains on Titan. it has rivers and lakes and seas. So in some senses, that sounds quite familiar. But the materials are very different. So instead of a rocky body, as the Earth is, Titan is an icy body. So we've got a place that has, in some senses, quite familiar processes. I mean, after all, the laws of physics are the same there, but with quite alien materials. Yeah. And you were responsible for the surface science package.

So how did that work exactly? What information was that taking in and then, you know, relaying back to us? Well, our problem was that when we were designing this instrument, as I say, we didn't know what we were going to land on. So what we had to do was we came up with nine different sensors which would sort of span the spectrum of surfaces that we thought we might encounter. As it was, we landed on the edge of a dried up lake so it was ostensibly dry although the data implies that it was probably damp so it it had been wet right that there are seasons on titan

and they're probably wet and dry seasons so it was probably the edge of a lake which had been perhaps quite recently you know even only years ago full of a lake, which had been perhaps quite recently, you know, even only years ago, full of liquid, but it had dried out. So we were able to make measurements of, for example, the hardness, the granularity of the surface. We measured the temperature, some of the thermal and electrical properties. But also during the descent, we made measurements of the motion of the probe. And all of this just helped to create a picture of really what it's like below those orange clouds that prevent us from seeing Titan from outside.

And then how did this work hand in hand with Cassini? You know, let's explore some of the other moons. What else was discovered and how significant has that been? Well, the big surprise, I suppose, of the mission was Enceladus. So Enceladus is one of the smaller moons. It's a few hundred kilometres across. And I mean, I don't think that anybody expected it to be that dramatic. But on one of the flybys of Enceladus, the magnetic instrument, which incidentally is a UK-led instrument, the magnetometer detected some really strange anomalies in the magnetic field around Enceladus. So that was followed up. And what transpired was that Enceladus is actually spewing material out from cracks in its surface out into the local environment. And that stuff is mostly water, but it also includes organic molecules

and dust. And the instruments on Cassini were able to analyze some of this material. So it seems that we have a body which, as I say, is relatively small by planetary standards, is relatively small by planetary standards. And yet it probably has below its surface very large reservoirs of some sort of water and it looks like also organic molecules. So maybe it's fanciful, but it's not impossible that a place like that could be a niche where certain very simple forms of life could be harbored.

And, you know, I think this was a tremendous surprise. And it perhaps tells us, I think it's pointing us in the direction of understanding that in our solar system, there are probably many, many niches where the conditions for life could exist, or in fact do exist. That doesn't, of course, mean that life has got going there and has been sustained, but it throws open that possibility. And we said goodbye to Cassini as it entered into Saturn's atmosphere. So was that collecting data even up until that final point? Oh, it absolutely was, yes. I mean, some of that data, of course, is unique because it was from so close in

as it plunged into the upper atmosphere and clouds of Saturn. Yeah, that was a pretty emotional moment, especially for the people who, you know, worked for all of those years on Cassini to say goodbye to their craft. And, you know, really, as scientists, we're sort of trained to be detached. But, you know, I'll let you into a secret. We actually get quite emotional at times. You know, I'll let you into a secret. We actually get quite emotional at times. I myself, for example, when we we landed on the surface, that that that moment for me was so overwhelming. I went into the corner of the control room and shed a few tears.

You know, it was really that emotional. Thank you to John Czarnecki. This is the Supermassive podcast from the Royal Astronomical Society with me, astrophysicist Dr. Becky Smethurst, and with science journalist Izzy Clark. This month is all about Becky's favourite planet, Saturn. Before we get on to everyone's questions, can we just reflect on all of the space news from just the past month i mean there's something in the air and the space vacuum i don't know what it is but yeah like we had the juice launch didn't we and we talked about that last month with the the jupiter episode so that's finally on its way you know i don't think it's gonna go there until like 2034 or something because it's taking a very long roundabout lots of slingshot routes to jupiter

but it still it was great to see that the first images sent back from that so you could you know beautiful shots back at the earth essentially and there's just something about watching a launch where you're just like come on up you go yeah it's just so exciting you go little one you go i put it in my calendar at work like no one contacted me and then it got delayed because of lightning so what happened did you have to rebook just like shuffle that over like still don't talk to me and then we had space x's starship launch and uh rapid unscheduled disassembly well i don't know about that i mean it was a success in the fact that you know it exploded because it was supposed to explode because you know they launched it and they got all the data from it and then

it started to tumble and you don't want an out of control rocket falling to earth so it was like okay let's make let's explode this thing it was always a test right it was never going anywhere so yeah i enjoyed um you know so it was also on the day that all the blue ticks disappeared on twitter so i think it was g James, the BBC Radio 1 presenter, who tweeted like, well, I might have lost my blue tick, but your rocket exploded. And I didn't want to be the person that tweeted back like, well, actually, it was supposed to explode.

But it was very funny. I thought it was very, very funny. And then to top that off, we had a solar eclipse and then the Artemis 2 astronauts were named as well. So this is that mission that is going to loop around the moon and is going to take humans further than we've ever been. I mean, it's so exciting. It is so exciting. Yeah.

So this is Artemis 2 is basically a complete rerun of Artemis 1, which we had back in November 2022. So that was basically just to prove that you could send this craft and loop it around the moon the furthest, you know, it's ever been looped before and bring it back. And this time with Artemis 2, actually doing that with astronauts, a crew on board. And that's going to be either late 2024 or early 2025. And so they announced that the astronauts, they're actually going to be on board that, the four astronauts, including Christina Koch, who's going to be the first woman ever assigned to a lunar mission. And then also Victor Glover, the first black astronaut ever assigned to a lunar mission. So, you know, missions of first, which is really, really exciting to see as well. And then you've also got Reid Wiseman and Jeremy Hansen as well, who was also from the Canadian Space Agency. So, I mean, it's something to celebrate, I guess.

I mean, we have sort of talked about on here before how Artemis, well, is it sort of a politically motivated reason to go back to the moon necessarily, not always the science. It's going to do science while it's there, but is it really sort of like a political thing, like we should go back to the moon? But still, I think we can all celebrate the fact

that it's going to be the first female astronaut and also a black astronaut to loop as far as we have ever looped around the moon. Absolutely. Absolutely. OK, so I think we should get on to everyone's questions. As always, there were a few. So thank you to everyone that sent them in. Robert, let's start with this one from Brian Ross, who asks, hope everyone is doing well and enjoying the spring weather. Here's my question.

I believe I read a while ago that Saturn's atmosphere extends out to its moons. Is this true? And if so, does it affect them significantly? In other words, would it create drag on the moons to slow their orbits or affect the moon's atmosphere or geology? Well, Brian, I've looked around about this. As far as I can tell, it's not significantly present, the atmosphere that is, at the distance that the moons are. Although Saturn's atmosphere is much, much deeper than the Earth's, for example, hundreds of kilometres deep. And if you go deeper down, it just basically, the pressure rises until it becomes liquid. But it doesn't extend as far as the moons, as far as I can see. I mean, maybe there's a very tenuous thinning as there is with any atmosphere around the planet, but probably not that significant.

However, there are a few links, though. So you're onto something here. One of them is a fairly recent story, which is that an astronomer, Lothi Ben Jaffel in Paris, used data from the Hubble Space Telescope. Does everybody remember Hubble? It's still going. It's still going. It's still there. It's still there.

And poor old Hubble. Trucking along. And the Cassini mission and even the two Voyager missions can find the data for all of them. And looked at the atmosphere of Saturn and he found that it's a bit warmer than is expected. And attributes that to material falling in from the ring system. So there is that sort of connection between the rings, the little moonlets that shepherd them and the planet. And one thing that definitely does affect them is that Saturn's got a really, really big and powerful magnetic field, not as big as Jupiter's, but still pretty big, a million kilometers across, and it envelops Titan. So possibly without that, given that Titan

is within it 95% of the time, it might be helping Titan to keep its thick atmosphere. Because if you don't have a magnetic field or some kind of protection, then the solar wind can over time strip away atmospheres. I think that when I first saw that question from Brian, that was my first thought, that it was the magnetosphere necessarily that they were looking at because it is so big on Saturn.

Yeah. Okay. And Becky, Joe on email, has this question about Saturn's rings. If the rings are made up of broken moons, asteroids, etc., why are there large gaps between the rings? Wouldn't all the debris bounce around hitting each other and spread evenly to make one big ring?

Yeah, or even coalesce to make one moon as well, right? You might expect that eventually to happen. And they are fairly young, the rings, as well. My favourite fact is that some of the dinosaurs, if they had telescopes back then, they would looked at saturn and not seen rings so we're very lucky that we're sort of living through the the era of rings on saturn um but in terms of like the the gaps it's essentially all to do with the moons again so you know a few of the gaps are essentially caused by the fact there's moons orbiting there and they are literally clearing out that gap as they go and

stopping it from um you know filling up essentially and a bit those bits of the rings will probably end up sort of being accreted onto the surface of those moons so for example the Enka gap is possibly the most famous most obvious that's caused by the moon Pan because it orbits there you've also got the Keeler gap from like the moon Daphnis as well so that's obviously quite obvious why the moons cause those gaps. But other moons cause gaps, not because they orbit there, because they orbit quite far out,

but then they cause resonances. So that's due to the fact that these moons, it's fairly strong gravity compared to these little bits of debris and dust and ice and everything in the moons, will pull on those little particles quite a lot. So for example, Mimas, the Death Star Moon that we talked about before,

orbits fairly close to the rings. And actually it causes one of the gaps because of a 5-3 resonance. So for every three times Mimas orbits, it causes some of the particles in one of Saturn's rings to orbit five times for every three that it orbits. That's what I mean by a 5-3 resonance. It's because it's tugging on that all the time.

And so there's a lot of those out there. You know, There's sort of a 7-8 resonance out there as well. And that causes a lot of the sort of structure that you see in the rings. Now, obviously, those resonances can only happen when you have particles traveling at a certain speed or in a certain location as well, which is why you then this this very fine structure of these gaps and sort of like chunks in the rings and you end up with you know all this like crazy naming the a ring the b ring the d ring the f ring the the methone like all sorts in terms of the structure of saturn's rings i think you know it's one of those things if you if you look from far out enough you're like oh there's like four main rings and then you like zoom in you're like oh god there's caps everywhere okay okay so i hope that clears that up joe um and so spoiler alert for listeners the rings will disappear but that's likely in like 100 million years or so so robert rob jf8

asks given that some think saturn's rings were formed from one of its moons being ripped apart, and we also know the rings won't last forever, are any of Saturn's current moons good candidates for or at risk of becoming future rings? And when could that happen? Such a good question. It is a really good question. So one of the recent models of the formation of the rings involves Titan, the biggest moon, moving out. And as it did so, disturbing, I'm not necessarily close to it, disturbing another moon, which was given the name Chrysalis, which no longer exists. That's the one that we think was ripped apart. It was disturbed, moved in a bit and Saturn's gravity pulled it to bits. But for that to happen, oh, by the way, to mention the Death Star again, Chrysalis was probably about as big as Mimas. So just to get that one there. Thank you for that context. Couldn't you for that contact but for that to happen again you need to have a moon which is a close enough to saturn

be also big enough so as far as i can see none of the ones that you have now the shepherd moons within the ring system are all rather small you need something a bit bigger and a bit closer to saturn for that to happen now i don't know enough about orbital mechanics to think about what will titan do this again i don't think so. It's too far out. Is there some other mechanism that could do it? But probably not. Now, the other thing to know about the rings is that some of the other rings, apart from the main bright ones, form through different mechanisms too. So the F ring might have been formed by the debris from the collision of two moons.

Not destroying them, but bashing bits off. Pandora and Prometheus bashed together, generating destroying them, but bashing bits off. Pandora and Prometheus bashed together, generating some dust, and that formed a ring. And the E ring seems to be made up of material ejected from the water plume jets of Enceladus. And then the outermost rings of Saturn seem to be formed differently again. They seem to be micrometeorods blasting bits on the smaller moon. And also, that's the explanation, or the accepted one, for Jupiter, Uranus, and Neptune too. so you could argue that that little slow infinitesimal bashing that's going on is making these moons very very very very slowly become rings too but as for a really big one being

broken apart i just don't think there are any candidates and i'm secretly hoping that like i mean we are all scared of meteors i know everyone, oh, what if an asteroid is going to come here? I'm like, yeah, but what if it hit the moon and then the debris got thrown up and then Earth got a ring? Like that would be cool. Of course that's what you think. Of course that's where you go. Oh, gosh. Okay.

Well, Becky, on that, Max on Twitter also has a question. Why are the Enceladus jets in the south only? Is the interior hotter there or is the icy crust thinner? P.S. Titan is weird, lol. Sorry, not a question, just an observation. Titan is weird. I agree with you there. Although, you know what is weird?

You know, what's normal, what's weird? Is it just because, you know, methane, we don't, you know, it's not part of our atmosphere or water system like on Earth? I don't know. Maybe we need to renormalize what weird is. Anyway, Enceladus is Jets. It seems like the crust in the south pole of Enceladus is younger there. So it's very tectonically active.

You see lots of like ridges and fractures. And that could have been due to like impacts with asteroids you know sort of disturbing all of that and deforming it essentially which gives these plumes sort of the space to escape essentially from underneath the ocean if it is quite sort of high pressured or it could just be that's where the tectonic plates you know are colliding and interacting the most on Enceladus's surface you know know, in the same way that we have the Ring of Fire around Indonesia on Earth, right, with a very tectonically active region,

we get a lot of volcanoes there. It just so happens that is the location where it is. And so it just, you know, you say, okay, why don't we have that on the antipode of Earth opposite to Indonesia? It's like saying, you know, why you have it on the South Pole of Enceladus and not on the North Pole.

It just so happens that's the most tectonically active region, we think. Cool. Well, thank you both. And thank you to everyone who sent in questions. And if you want to send any questions to us for a future episode, then email podcast at ras.ac.uk, tweet at Royal Astrosoc or slide into the DMs on Instagram. It's at SupermassivePod. So, Robert, what can we see in the night sky this month well look i mean we're getting into may the nights are getting shorter the weather's warming up which is all nice in some ways but it does mean we have to stay a bit later to look at the stars but while you're doing that there are it's actually got a nice view in

twilight right now uh if you look for example on 20th of May, you can find a super thin moon. I'll let Becky get that reference in slightly later, with just about 1.4% of the hemisphere that we can see illuminated. So this is one of those very special, very thin crescent moons. And it's so thin that if you looked at it with a telescope, it might even look a bit broken because it's just illuminated. So the sun is just rising on the edge of it. So do take a look for that if it's clear. And also Venus, though, is really, really obvious in the western sky right now. If you've been looking out in the west, you know, driving home or out early evening, and you think, what is this incredibly bright thing?

That is Venus. The closest planet to the Earth reflects a lot of light, and it's going to get brighter still, and it'll be around for the next couple of months. If you look at it through a telescope, you see about half of its disk lit up, but not much more. It just seems to sort of hang there, doesn't it? It's crazy bright. People are weirded out by it. Like, is it a plane?

Is it like some sort of drone? It's just Venus just like, hi, I'm here. There are cases. If it's dark enough, it doesn't set till after midnight. And if it's dark enough, it's bright enough to cast shadows. Now, I've never seen that. But if you're in a very dark place, it should be possible. And unlike the sun, they should be really, really pin sharp because it's a point source.

So do look out for that. If anybody lives in the kind of place that's possible. Nearby, you've got Mars, which is about 200 times fainter, you know, really quite a long way from the Earth now and slowly moving behind the sun from our perspective. But I'm sorry to say, Becky, if you want to see Saturn, you need to get up or stay up if you've got a life till 3.30 in the morning. Or just, you know, you wake up in Italy in the night and you just crack the curtains and you just have a little cheeky look at yourself.

And then at least until, you know, mid-May, it's still getting probably dark enough to see, you know, a lot of stars, even in the north of the UK. And you can look out for the signposts of the plough, the Big Dipper. Look out, the cheesy way of remembering this is this line, follow the arc of the UK. And you can look out for the signpost of the plough, the Big Dipper. Look out. The cheesy way of remembering this is this line, follow the arc of the plough down to Arcturus and then the fourth brightest star in the sky

and then speed on to Spica, which is in Virgo, the zodiac constellation. And that's a nice thing to look at because there's a lot of galaxies there, one of which, Messier 87, has maybe a trillion stars in it and a big black hole in the middle. And it's also, though, apart

from at night, it's also a really good time to be safely, stress safely, getting a safe solar filter that you buy from a reputable dealer, fitted over your telescope at the end of it. It's a good time to be studying the sun because it's a really, really active year. 2023 is turning out to be really busy. Loads of spots on it. And that also means ejections of solar materials, some of which leads to displays the northern lights on earth now apps like aurora watch uk can tell you when that's happening now i just have to say that just before this recording i last night i had the app alerting me and was it clear no it was not clear i went out several times i got wet a little bit looking when i went to bed

it was a bit clear still didn't see anything then i believe at 3 a.m there were some auroral sightings where i was but in the north of the country it was really really good so generally if you're a bit further north and obviously it's probably dark then you can see these things but you know in astronomy you've got to be optimistic you've got to do these things just look out for them except the fact we live in the uk but have a look anyway yeah and i feel like we should say if you're in the uk and trying to see the aurora just always look north yeah Yeah, yes. Because it's always going to be on the northern horizon. They're not going to be above your head

like you see in sort of amazing videos online because that's sort of in the Arctic Circle area. But yeah, look north and see if you see that glow. And if you don't know which direction north is, think of in the summer, which direction do you sit in your garden to sunbathe and face the sun and face the other direction?

Always got helpful tips. I feel like everyone always knows that the sun and face the other direction always got helpful tips i feel like everyone always knows that the sun's over there in summer right he's like that's that's where i get my sun so well i think that is it for this month and we'll be back next time with our bonus episode where we take on more of your questions and then more satin questions here we go and if anyone wants to keep sending in satin questions we're gonna have to do like

bonus episodes of bonus episodes with just special satin content only but yeah once we get through all of that

we'll then be back with another main episode on the next generation of ground-based observatories and to get in touch if you have a

question for the team it's at royalastrosoc on Twitter or you can email your questions to podcast at ras.ac.uk or find us at supermassivepod on Instagram and we try and cover the questions in a future episode. Until then though everybody, happy stargazing.